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Sample records for screw augmentation techniques

  1. Minimally Invasive Technique for PMMA Augmentation of Fenestrated Screws.

    PubMed

    Klingler, Jan-Helge; Scholz, Christoph; Kogias, Evangelos; Sircar, Ronen; Krüger, Marie T; Volz, Florian; Scheiwe, Christian; Hubbe, Ulrich

    2015-01-01

    To describe the minimally invasive technique for cement augmentation of cannulated and fenestrated screws using an injection cannula as well as to report its safety and efficacy. A total of 157 cannulated and fenestrated pedicle screws had been cement-augmented during minimally invasive posterior screw-rod spondylodesis in 35 patients from January to December 2012. Retrospective evaluation of cement extravasation and screw loosening was carried out in postoperative plain radiographs and thin-sliced triplanar computed tomography scans. Twenty-seven, largely prevertebral cement extravasations were detected in 157 screws (17.2%). None of the cement extravasations was causing a clinical sequela like a new neurological deficit. One screw loosening was noted (0.6%) after a mean follow-up of 12.8 months. We observed no cementation-associated complication like pulmonary embolism or hemodynamic insufficiency. The presented minimally invasive cement augmentation technique using an injection cannula facilitates convenient and safe cement delivery through polyaxial cannulated and fenestrated screws during minimally invasive screw-rod spondylodesis. Nevertheless, the optimal injection technique and design of fenestrated screws have yet to be identified. This trial is registered with German Clinical Trials DRKS00006726.

  2. Minimally Invasive Technique for PMMA Augmentation of Fenestrated Screws

    PubMed Central

    Kogias, Evangelos; Sircar, Ronen; Krüger, Marie T.; Volz, Florian; Scheiwe, Christian; Hubbe, Ulrich

    2015-01-01

    Purpose. To describe the minimally invasive technique for cement augmentation of cannulated and fenestrated screws using an injection cannula as well as to report its safety and efficacy. Methods. A total of 157 cannulated and fenestrated pedicle screws had been cement-augmented during minimally invasive posterior screw-rod spondylodesis in 35 patients from January to December 2012. Retrospective evaluation of cement extravasation and screw loosening was carried out in postoperative plain radiographs and thin-sliced triplanar computed tomography scans. Results. Twenty-seven, largely prevertebral cement extravasations were detected in 157 screws (17.2%). None of the cement extravasations was causing a clinical sequela like a new neurological deficit. One screw loosening was noted (0.6%) after a mean follow-up of 12.8 months. We observed no cementation-associated complication like pulmonary embolism or hemodynamic insufficiency. Conclusions. The presented minimally invasive cement augmentation technique using an injection cannula facilitates convenient and safe cement delivery through polyaxial cannulated and fenestrated screws during minimally invasive screw-rod spondylodesis. Nevertheless, the optimal injection technique and design of fenestrated screws have yet to be identified. This trial is registered with German Clinical Trials DRKS00006726. PMID:26075297

  3. Ultrasound melted polymer sleeve for improved screw anchorage in trabecular bone--A novel screw augmentation technique.

    PubMed

    Schmoelz, W; Mayr, R; Schlottig, F; Ivanovic, N; Hörmann, R; Goldhahn, J

    2016-03-01

    Screw anchorage in osteoporotic bone is still limited and makes treatment of osteoporotic fractures challenging for surgeons. Conventional screws fail in poor bone quality due to loosening at the screw-bone interface. A new technology should help to improve this interface. In a novel constant amelioration process technique, a polymer sleeve is melted by ultrasound in the predrilled screw hole prior to screw insertion. The purpose of this study was to investigate in vitro the effect of the constant amelioration process platform technology on primary screw anchorage. Fresh frozen femoral heads (n=6) and vertebrae (n=6) were used to measure the maximum screw insertion torque of reference and constant amelioration process augmented screws. Specimens were cut in cranio-caudal direction, and the screws (reference and constant amelioration process) were implanted in predrilled holes in the trabecular structure on both sides of the cross section. This allowed the pairwise comparison of insertion torque for constant amelioration process and reference screws (femoral heads n=18, vertebrae n=12). Prior to screw insertion, a micro-CT scan was made to ensure comparable bone quality at the screw placement location. The mean insertion torque for the constant amelioration process augmented screws in both, the femoral heads (44.2 Ncm, SD 14.7) and the vertebral bodies (13.5 Ncm, SD 6.3) was significantly higher than for the reference screws of the femoral heads (31.7 Ncm, SD 9.6, p<0.001) and the vertebral bodies (7.1 Ncm, SD 4.5, p<0.001). The interconnection of the melted polymer sleeve with the surrounding trabecular bone in the constant amelioration process technique resulted in a higher screw insertion torque and can improve screw anchorage in osteoporotic trabecular bone. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. A new technique of bone cement augmentation via the disc space for percutaneous pedicle screw fixation.

    PubMed

    Park, Chang Kyu; Park, Choon Keun; Lee, Dong Chan; Lee, Dong Geun

    2016-01-01

    In elderly patients with severe osteoporosis, instrumented lumbar interbody fusion may result in fixation failure or nonunion because of decreased pedicle screw pullout strength or increased interbody graft subsidence risk. Thus, given its many advantages, percutaneous pedicle screw fixation with cement augmentation can be an effective method to use in elderly patients. The authors report on an easy, safe, and economical technique for bone cement augmentation using a bone biopsy needle inserted into the disc space in 2 osteoporotic patients who were treated with posterior interbody fusion and percutaneous pedicle screw fixation. Two elderly patients who complained of back pain and intermittent neurological claudication underwent posterior interbody fusion with percutaneous pedicle screw fixation. After routinely assembling rods on the screws, a bone biopsy needle was inserted into the disc space via the operative field; the needle was then placed around the tips of the screws using fluoroscopic radiography for guidance. Bone cement was injected through the bone biopsy needle, also under fluoroscopic radiography guidance. Both patients' symptoms improved after the operation, and there was no evidence of cage subsidence or screw loosening at the 4-month follow-up. The indirect technique of bone cement augmentation via the disc space for percutaneous screw fixation could be an easy, safe, and economical method.

  5. How Effective Is the Tent Screw Pole Technique Compared to Other Forms of Horizontal Ridge Augmentation?

    PubMed

    Deeb, George R; Tran, Dan; Carrico, Caroline K; Block, Erin; Laskin, Daniel M; Deeb, Janina Golob

    2017-06-13

    The tent screw pole technique is one of the methods available for practitioners to perform horizontal ridge augmentation to facilitate dental implant placement. The purpose of this study was to evaluate the efficacy of the tent screw pole technique for horizontal ridge augmentation and to compare the results with those of the tunnel technique and open ridge augmentation. In this retrospective cohort study, 35 patients underwent horizontal ridge augmentation with the tent screw pole technique, a 1:1 ratio of mineralized freeze-dried bone allograft and particulate bovine hydroxyapatite, and a resorbable collagen membrane. The incidence of early wound dehiscence and membrane exposure, the number of courses of antibiotics and postoperative visits required for their management, and the number of sites that subsequently had successful implant placement were recorded. These parameters were compared with those in 21 patients who had undergone horizontal ridge augmentation by the tunnel technique and 31 patients who had been treated using an open procedure and a resorbable polytetrafluoroethylene (PTFE) membrane in the authors' previous study (J Oral Maxillofac Surg 74:1752, 2016). Implant placement rate was similar for all 3 methods (71 to 97%). However, there were significant differences among the 3 surgical techniques for membrane exposure and wound dehiscence (P = .0033), graft loss (P = .0256), courses of antibiotics (P = .0017), and postoperative visits (P = .0043). The PTFE method consistently had the highest rate of complications, whereas the tent screw and tunnel techniques were comparable. All 3 techniques allowed a high rate of implant placement; however, the PTFE technique was consistently associated with increased postoperative complications compared with the other 2 methods. The tent screw technique might be more favorable than the tunnel technique in cases in which the bony deficiency is flat. Copyright © 2017 American Association of Oral and

  6. A new technique for cement augmentation of the sliding hip screw in proximal femur fractures.

    PubMed

    Stoffel, Karl K; Leys, Toby; Damen, Nikki; Nicholls, Rochelle L; Kuster, Markus S

    2008-01-01

    Fractures of the osteoporotic proximal femur are a significant source of mortality and morbidity in today's ageing population. Even with modern fixation techniques such as the sliding hip screw, a certain percentage of fixations will fail due to cut-out of the screw. This study presents a new method for augmenting hip screws with cement to reinforce the fixation. Unstable pertrochanteric fractures were created in paired osteoporotic cadaver femora (n=10). The fractures were fixed using either standard fixation techniques (dynamic hip screw), or using a dynamic hip screw augmented with cement. Cement was introduced using a customised jig to guide cement into a region superior to the screw in the femoral head. Cut-out resistance was assessed using a biaxial material testing machine, with loading applied in compression until failure. The new cement augmentation technique significantly improved the cut-out strength of the fixation (mean 42%; P=0.032). The failure mechanism for both groups was the same, with failure occurring through compression of the cancellous bone superior to the screw. The mean increase in temperature at the femoral neck was 3.7 degrees C in augmented bones, which is much lower than values previously reported for polymethylmethacrylate cements. Several benefits with this technique have emerged. The method is technically straightforward. The risk of cement penetration into the joint is reduced, and cement is targetted to the areas of the femoral head where it is most needed. The exothermic reaction is minimised by reducing the volume of cement used. The first clinical results are promising.

  7. Influence of the screw augmentation technique and a diameter increase on pedicle screw fixation in the osteoporotic spine: pullout versus fatigue testing.

    PubMed

    Kueny, Rebecca A; Kolb, Jan P; Lehmann, Wolfgang; Püschel, Klaus; Morlock, Michael M; Huber, Gerd

    2014-10-01

    For posterior spinal stabilization, loosening of pedicle screws at the bone-screw interface is a clinical complication, especially in the osteoporotic population. Axial pullout testing is the standard pre-clinical testing method for new screw designs although it has questioned clinical relevance. The aim of this study was to determine the fixation strength of three current osteoporotic fixation techniques and to investigate whether or not pullout testing results can directly relate to those of the more physiologic fatigue testing. Thirty-nine osteoporotic, human lumbar vertebrae were instrumented with pedicle screws according to four treatment groups: (1) screw only (control), (2) prefilled augmentation, (3) screw injected augmentation, and (4) unaugmented screws with an increased diameter. Toggle testing was first performed on one pedicle, using a cranial-caudal sinusoidal, cyclic (1.0 Hz) fatigue loading applied at the screw head. The initial compressive forces ranged from 25 to 75 N. Peak force increased stepwise by 25 N every 250 cycles until a 5.4-mm screw head displacement. The contralateral screw then underwent pure axial pullout (5 mm/min). When compared to the control group, screw injected augmentation increased fatigue force (27 %, p = 0.045) while prefilled augmentation reduced fatigue force (-7 %, p = 0.73). Both augmentation techniques increased pullout force compared to the control (ps < 0.04). Increasing the screw diameter by 1 mm increased pullout force (24 %, p = 0.19), fatigue force (5 %, p = 0.73), and induced the least stiffness loss (-29 %) from control. For the osteoporotic spine, screw injected augmentation showed the best biomechanical stability. Although pullout testing was more sensitive, the differences observed were not reflected in the more physiological fatigue testing, thus casting further doubt on the clinical relevance of pullout testing.

  8. [Cement augmentation of pedicle screws : Pros and cons].

    PubMed

    Schnake, K J; Blattert, T R; Liljenqvist, U

    2016-09-01

    Cement augmentation of pedicle screws biomechanically increases screw purchase in the bone. However, clinical complications may occur. The pros and cons of the technique are discussed from different clinical perspectives.

  9. Pullout strength of pedicle screws with cement augmentation in severe osteoporosis: A comparative study between cannulated screws with cement injection and solid screws with cement pre-filling

    PubMed Central

    2011-01-01

    Background Pedicle screws with PMMA cement augmentation have been shown to significantly improve the fixation strength in a severely osteoporotic spine. However, the efficacy of screw fixation for different cement augmentation techniques, namely solid screws with retrograde cement pre-filling versus cannulated screws with cement injection through perforation, remains unknown. This study aimed to determine the difference in pullout strength between conical and cylindrical screws based on the aforementioned cement augmentation techniques. The potential loss of fixation upon partial screw removal after screw insertion was also examined. Method The Taguchi method with an L8 array was employed to determine the significance of design factors. Conical and cylindrical pedicle screws with solid or cannulated designs were installed using two different screw augmentation techniques: solid screws with retrograde cement pre-filling and cannulated screws with cement injection through perforation. Uniform synthetic bones (test block) simulating severe osteoporosis were used to provide a platform for each screw design and cement augmentation technique. Pedicle screws at full insertion and after a 360-degree back-out from full insertion were then tested for axial pullout failure using a mechanical testing machine. Results The results revealed the following 1) Regardless of the screw outer geometry (conical or cylindrical), solid screws with retrograde cement pre-filling exhibited significantly higher pullout strength than did cannulated screws with cement injection through perforation (p = 0.0129 for conical screws; p = 0.005 for cylindrical screws). 2) For a given cement augmentation technique (screws without cement augmentation, cannulated screws with cement injection or solid screws with cement pre-filling), no significant difference in pullout strength was found between conical and cylindrical screws (p >0.05). 3) Cement infiltration into the open cell of the test block led to

  10. Cement leakage in pedicle screw augmentation: a prospective analysis of 98 patients and 474 augmented pedicle screws.

    PubMed

    Mueller, Jan U; Baldauf, Joerg; Marx, Sascha; Kirsch, Michael; Schroeder, Henry W S; Pillich, Dirk T

    2016-07-01

    OBJECTIVE Loosening and pullout of pedicle screws are well-known problems in pedicle screw fixation surgery. Augmentation of pedicle screws with bone cement, first described as early as 1975, increases the pedicle-screw interface and pullout force in osteoporotic vertebrae. The aim of the present study was to identify cement leakage and pulmonary embolism rates in a large prospective single-center series of pedicle screw augmentations. METHODS All patients who underwent cement-augmented pedicle screw placement between May 2006 and October 2010 at the authors' institution were included in this prospective cohort study. Perivertebral cement leakage and pulmonary cement embolism were evaluated with a CT scan of the area of operation and with a radiograph of the chest, respectively. RESULTS A total of 98 patients underwent placement of cement-augmented pedicle screws; 474 augmented screws were inserted in 237 vertebrae. No symptomatic perivertebral cement leakage or symptomatic pulmonary cement embolism was observed, but asymptomatic perivertebral cement leakage was seen in 88 patients (93.6%) and in 165 augmented vertebrae (73.3%). Cement leakage most often occurred in the perivertebral venous system. Clinically asymptomatic pulmonary cement embolism was found in 4 patients (4.1%). CONCLUSIONS Perivertebral cement leakage often occurs in pedicle screw augmentation, but in most cases, it is clinically asymptomatic. Cement augmentation should be performed under continuous fluoroscopy to avoid high-volume leakage. Alternative strategies, such as use of expandable screws, should be examined in more detail for patients at high risk of screw loosening.

  11. Pedicle screw design and cement augmentation in osteoporotic vertebrae: effects of fenestrations and cement viscosity on fixation and extraction.

    PubMed

    Choma, Theodore J; Pfeiffer, Ferris M; Swope, Ryan W; Hirner, Jesse P

    2012-12-15

    Experimental, human cadaveric study. To assess the fixation effects of injecting cement augmentation before screw insertion or after insertion of fenestrated screws; the effect of modulating cement viscosity; and the effects of these techniques on screw removal. It seems clear that cement augmentation can enhance pedicle screw fixation in osteoporotic bone. What remains to be demonstrated is the aspects of optimal technique such that fixation is enhanced with the greatest safety profile. Part I: Human osteoporotic vertebrae were instrumented with solid (nonaugmented) screws, solid screws with polymethylmethacrylate (PMMA), partially cannulated fenestrated (Pfen) screws, or fully cannulated fenestrated (Ffen) screws through which PMMA was injected. Screw fixation was tested in pullout. Part II: Ffen screws were augmented with standard low-viscosity PMMA versus high-viscosity PMMA. Part III: Sample cohorts were extracted from vertebrae to assess required torque and characterize difficulty of extraction. Part I: Pfen screws demonstrated the greatest fixation with mean failure force of 690 ± 182 N. All methods of cement augmentation demonstrated significant increases in screw fixation. Part II: Ffen screws did not demonstrate a significant difference in pullout strength when high-viscosity PMMA was used as compared with low-viscosity PMMA. Part III: Mean extraction torque values for solid augmented screws, Ffen screws, and Pfen screws were 1.167, 1.764, and 1.794 Nm, respectively, but these differences did not reach significance. None of the osteoporotic vertebrae sustained catastrophic failure during augmented screw extraction. Polymethylmethacrylate cement augmentation clearly enhances pedicle screw fixation in osteoporotic vertebrae when tested in pure pullout. The technique used for cement injection and choice of specialty screws can have a significant impact on the magnitude of this effect. Fenestrated screws have the capacity to confine cement placement in the

  12. [Augmentation technique on the proximal humerus].

    PubMed

    Scola, A; Gebhard, F; Röderer, G

    2015-09-01

    The treatment of osteoporotic fractures is still a challenge. The advantages of augmentation with respect to primary in vitro stability and the clinical use for the proximal humerus are presented in this article. In this study six paired human humeri were randomized into an augmented and a non-augmented group. Osteosynthesis was performed with a PHILOS plate (Synthes®). In the augmented group the two screws finding purchase in the weakest cancellous bone were augmented. The specimens were tested in a 3-part fracture model in a varus bending test. The augmented PHILOS plates withstood significantly more load cycles until failure. The correlation to bone mineral density (BMD) showed that augmentation could partially compensate for low BMD. The augmentation of the screws in locked plating in a proximal humerus fracture model is effective in improving the primary stability in a cyclic varus bending test. The targeted augmentation of two particular screws in a region of low bone quality within the humeral head was almost as effective as four screws with twice the amount of bone cement. Screw augmentation combined with a knowledge of the local bone quality could be more effective in enhancing the primary stability of a proximal humerus locking plate because the effect of augmentation can be exploited more effectively limiting it to the degree required. The technique of augmentation is simple and can be applied in open and minimally invasive procedures. When the correct procedure is used, complications (cement leakage into the joint) can be avoided.

  13. Pedicle screw augmentation in osteoporotic spine: indications, limitations and technical aspects.

    PubMed

    Hoppe, S; Keel, M J B

    2017-02-01

    The need for spinal instrumented fusion in osteoporotic patients is rising. In this review, we try to give an overview of the current spectrum of pedicle screw augmentation techniques, safety aspects and indications. Review of literature and discussion of indications, limitations and technical aspects. Various studies have shown higher failure rates in osteoporotic patients, most probably due to reduced bone quality and a poor bone-screw interface. Augmentation of pedicle screws with bone cement, such as polymethylmethacrylate or calcium based cements, is one valid option to enhance fixation if required. Crucial factors for success in the use of augmented screws are careful patient selection, a proper technique and choice of the ideal cement augmentation option.

  14. The Efficacy of Hydroxyapatite for Screw Augmentation in Osteoporotic Patients

    PubMed Central

    Jang, Sang Hoon; Lee, June Ho; Cho, Ji Young; Lee, Ho-Yeon; Lee, Sang-Ho

    2013-01-01

    The stability of screw constructs is of considerable importance in determining the outcome, especially in spinal osteoporosis. Polymethylmethacrylate (PMMA) has been proven as an effective material for increasing the pullout strength of pedicle screws inserted into the osteoporotic bones. However, PMMA has several disadvantages, such as its exothermic properties, the risk of neural injury in the event of extravasation, and difficulties in performing revision surgery. In the current study, we used hydroxyapatite (HA) cement for screw augmentation in spinal osteoporosis. We conclude that HA cement is a useful tool for screw augmentation and recommend it as a promising option for spinal instrumentation in osteoporotic patients. PMID:24201099

  15. A Biomechanical Comparison of Expansive Pedicle Screws for Severe Osteoporosis: The Effects of Screw Design and Cement Augmentation

    PubMed Central

    Tai, Ching-Lung; Tsai, Tsung-Ting; Lai, Po-Liang; Chen, Yi-Lu; Liu, Mu-Yi; Chen, Lih-Huei

    2015-01-01

    Expansive pedicle screws significantly improve fixation strength in osteoporotic spines. However, the previous literature does not adequately address the effects of the number of lengthwise slits and the extent of screw expansion on the strength of the bone/screw interface when expansive screws are used with or without cement augmentation. Herein, four designs for expansive pedicle screws with different numbers of lengthwise slits and different screw expansion levels were evaluated. Synthetic bones simulating severe osteoporosis were used to provide a comparative platform for each screw design. The prepared specimens were then tested for axial pullout failure. Regardless of screw design, screws with cement augmentation demonstrated significantly higher pullout strength than pedicle screws without cement augmentation (p < 0.001). For screws without cement augmentation, solid screws exhibited the lowest pullout strength compared to the four expansive groups (p < 0.01). No significant differences in pullout strength were observed between the expansive screws with different designs (p > 0.05). Taken together, our results show that pedicle screws combined with cement augmentation may greatly increase screw fixation regardless of screws with or without expansion. An increase in both the number of slits and the extent of screw expansion had little impact on the screw-anchoring strength. Cement augmentation is the most influential factor for improving screw pullout strength. PMID:26720724

  16. A Biomechanical Comparison of Expansive Pedicle Screws for Severe Osteoporosis: The Effects of Screw Design and Cement Augmentation.

    PubMed

    Tai, Ching-Lung; Tsai, Tsung-Ting; Lai, Po-Liang; Chen, Yi-Lu; Liu, Mu-Yi; Chen, Lih-Huei

    2015-01-01

    Expansive pedicle screws significantly improve fixation strength in osteoporotic spines. However, the previous literature does not adequately address the effects of the number of lengthwise slits and the extent of screw expansion on the strength of the bone/screw interface when expansive screws are used with or without cement augmentation. Herein, four designs for expansive pedicle screws with different numbers of lengthwise slits and different screw expansion levels were evaluated. Synthetic bones simulating severe osteoporosis were used to provide a comparative platform for each screw design. The prepared specimens were then tested for axial pullout failure. Regardless of screw design, screws with cement augmentation demonstrated significantly higher pullout strength than pedicle screws without cement augmentation (p < 0.001). For screws without cement augmentation, solid screws exhibited the lowest pullout strength compared to the four expansive groups (p < 0.01). No significant differences in pullout strength were observed between the expansive screws with different designs (p > 0.05). Taken together, our results show that pedicle screws combined with cement augmentation may greatly increase screw fixation regardless of screws with or without expansion. An increase in both the number of slits and the extent of screw expansion had little impact on the screw-anchoring strength. Cement augmentation is the most influential factor for improving screw pullout strength.

  17. [Venous Paravasation After Augmentation of Pedicle Screws - An Underestimated Risk].

    PubMed

    Prokop, Axel; Sagerer, Manuela; Rupp, Wolfgang; Chmielnicki, Marc

    2017-06-30

    Cement-augmented pedicle screws can increase the stability of fixators for unstable vertebral fractures in the elderly. Fixators can be inserted quickly and with minimally invasive techniques, reducing surgical risks. From March 2012 until July 2014, we treated 40 patients with percutaneous augmented fixators for unstable vertebral fractures. Average age was 77.5 years. During the six month observation period, no patients died. There were no neurological deficits. On VAS, average pain decreased from 8.5 to 4.1 points postoperatively. The average Cobb angle of 4.1° was improved after surgery. After 6 months, bony consolidation yielded angles of 1 to 4°, average 2.6°. There was often venous extravasation of cement leaking from the augmented vertebrae, even extending to pulmonary embolism. The emboli were usually asymptomatic. We report a case where the patient required resuscitation immediately after cement application because of pulmonary emboli. The patient survived because of the immediately implemented critical care measures. Little has been published about this risk, which is underestimated despite increasing numbers of augmented fixator operations. The risk can be reduced with slower cement injection, smaller cement applicators, and short term positive pressure ventilation with PEEP. Georg Thieme Verlag KG Stuttgart · New York.

  18. Prophylactic bioactive screw fixation as an alternative augmentation for femoroplasty.

    PubMed

    Hananouchi, Takehito

    2015-04-01

    Femoroplasty is theoretically a prophylactic surgical procedure for femoral neck fracture. Although bone cement is generally used for augmentation, its distribution cannot be easily controlled. This study investigated whether a bioactive screw is feasible for femoroplasty as an alternative augmentation material. A mechanical test was done to compare the strength of four types of augmentation bioactive screw (Superfixsorb), two bioinert cements, or no intervention in a composite femoral bone. The peak load to fracture under simulated falling was compared among the four groups. The mean peak load to failure in the bioactive screw group (2667 N) was significantly higher than that in the intact group (2391 N) (p=0.028), comparable to that in the Simplex P cement group (2864 N) (p=0.11), and significantly lower than that of the cranioplastic cement group (3022 N) (p=0.006). The strength of a composite femur with the bioactive screw was higher than that of an intact bone and comparable to one cement augmentation. Thus, this bioactive screw can be potentially used as augmentation material for femoroplasty.

  19. Biomechanical analysis of stiffness and fracture displacement after using PMMA-augmented sacroiliac screw fixation for sacrum fractures.

    PubMed

    Höch, Andreas; Schimpf, Richard; Hammer, Niels; Schleifenbaum, Stefan; Werner, Michael; Josten, Christoph; Böhme, Jörg

    2017-03-15

    Cement augmentation of pedicle screws is the gold standard for the stabilization of osteoporotic fractures of the spine. In-screw cement augmentation, in which cement is injected through the cannula, is another option for fracture stabilization of fragility fractures of the sacrum. However, biomechanical superiority of this technique compared to conventional sacroiliac screw fixation has not been tested. The present study compares the stability of cement-augmented and non-cement-augmented sacroiliac screw fixation in osteoporotic sacrum fractures under cyclic loading. Eight human donor pelvises with intact ligaments and 5th lumbar vertebra were dissected. A vertical shear fracture was created as a combination of a sacrum fracture and cutting of the symphysis. Both sides were tested in a single-limb-stance setup with 10,000 loading cycles applied. Stiffness of the pelvis and displacement of the fracture were measured using a hydraulic testing machine and a 3D image correlation system. The augmented screw fixation failed in two of eight pelvises, and the non-augmented screws failed in three of eight pelvises. CT scans showed no leakage of cement. In-screw polymethylmethacrylate (PMMA) augmentation showed no advantage based on measured displacement of the sacrum fractures or stiffness for sacroiliac screw fixation of fragility fractures of the sacrum.

  20. Biomechanical comparison of anatomic trajectory pedicle screw versus injectable calcium sulfate graft-augmented pedicle screw for salvage in cadaveric thoracic bone.

    PubMed

    Derincek, Alihan; Wu, Chunhui; Mehbod, Amir; Transfeldt, Ensor E

    2006-06-01

    Many salvage options for failed thoracic pedicle screws exist including the use of a different trajectory or the augmentation of the screw with polymethylmethacrylate cement. Although polymethylmethacrylate immediately increases the construct stiffness and the pull-out strength, it may cause bone necrosis, toxin relaxation, and/or neural injury. On the other hand, calcium sulfate bone grafts have a high potential for biologic incorporation and no thermal damage effect. In the current study, polyaxial pedicle screws were first inserted with a straightforward approach on both sides in 17 fresh human cadaveric thoracic vertebrae. The maximal insertion torque for each screw was measured and then the pull-out strengths were recorded. Afterward, these pedicle screws were randomly assigned to be replaced either by graft augmentation or by anatomic trajectory technique for salvage. The graft-augmented screws were placed using the previous holes. The maximum insertional torque for each anatomic trajectory screw was measured. Finally, the pull-out strengths of the revision screws were recorded. The mean maximum insertional torque decreased with the anatomic trajectory salvage technique when compared with the straightforward approach, 0.23 versus 0.38 Nm, respectively (P=0.003). The anatomic trajectory revision resulted in decreased pull-out strength when compared with the pull-out strength of the straightforward technique, 297 versus 469 N, respectively (P=0.003). The calcium sulfate graft augmentation increased the pull-out strength when compared with the pull-out strength of the straightforward technique, 680 versus 477 N, respectively (P=0.017). The mean pull-out strength ratio of revised screw to original was 0.71 for anatomic trajectory and 1.8 for graft-augmented screws, a statistically significant difference (P=0.002).

  1. Biomechanical study of expandable pedicle screw fixation in severe osteoporotic bone comparing with conventional and cement-augmented pedicle screws.

    PubMed

    Chen, Yi-Long; Chen, Wen-Chuan; Chou, Chi-Wei; Chen, Jou-Wen; Chang, Chia-Ming; Lai, Yu-Shu; Cheng, Cheng-Kung; Wang, Shih-Tien

    2014-11-01

    Pedicle screws are widely utilized to treat the unstable thoracolumbar spine. The superior biomechanical strength of pedicle screws could increase fusion rates and provide accurate corrections of complex deformities. However, osteoporosis and revision cases of pedicle screw substantially reduce screw holding strength and cause loosening. Pedicle screw fixation becomes a challenge for spine surgeons in those scenarios. The purpose of this study was to determine if an expandable pedicle screw design could be used to improve biomechanical fixation in osteoporotic bone. Axial mechanical pull-out test was performed on the expandable, conventional and augmented pedicle screws placed in a commercial synthetic bone block which mimicked a human bone with severe osteoporosis. Results revealed that the pull-out strength and failure energy of expandable pedicle screws were similar with conventional pedicle screws augmented with bone cement by 2 ml. The pull-out strength was 5-fold greater than conventional pedicle screws and the failure energy was about 2-fold greater. Besides, the pull-out strength of expandable screw was reinforced by the expandable mechanism without cement augmentation, indicated that the risks of cement leakage from vertebral body would potentially be avoided. Comparing with the biomechanical performances of conventional screw with or without cement augmentation, the expandable screws are recommended to be applied for the osteoporotic vertebrae. Copyright © 2014 IPEM. Published by Elsevier Ltd. All rights reserved.

  2. Pullout characteristics of percutaneous pedicle screws with different cement augmentation methods in elderly spines: An in vitro biomechanical study.

    PubMed

    Charles, Y P; Pelletier, H; Hydier, P; Schuller, S; Garnon, J; Sauleau, E A; Steib, J-P; Clavert, P

    2015-05-01

    Vertebroplasty prefilling or fenestrated pedicle screw augmentation can be used to enhance pullout resistance in elderly patients. It is not clear which method offers the most reliable fixation strength if axial pullout and a bending moment is applied. The purpose of this study is to validate a new in vitro model aimed to reproduce a cut out mechanism of lumbar pedicle screws, to compare fixation strength in elderly spines with different cement augmentation techniques and to analyze factors that might influence the failure pattern. Six human specimens (82-100 years) were instrumented percutaneously at L2, L3 and L4 by non-augmented screws, vertebroplasty augmentation and fenestrated screws. Cement distribution (2 ml PMMA) was analyzed on CT. Vertebral endplates and the rod were oriented at 45° to the horizontal plane. The vertebral body was held by resin in a cylinder, linked to an unconstrained pivot, on which traction (10 N/s) was applied until rupture. Load-displacement curves were compared to simultaneous video recordings. Median pullout forces were 488.5 N (195-500) for non-augmented screws, 643.5 N (270-1050) for vertebroplasty augmentation and 943.5 N (750-1084) for fenestrated screws. Cement augmentation through fenestrated screws led to significantly higher rupture forces compared to non-augmented screws (P=0.0039). The pullout force after vertebroplasty was variable and linked to cement distribution. A cement bolus around the distal screw tip led to pullout forces similar to non-augmented screws. A proximal cement bolus, as it was observed in fenestrated screws, led to higher pullout resistance. This cement distribution led to vertebral body fractures prior to screw pullout. The experimental setup tended to reproduce a pullout mechanism observed on radiographs, combining axial pullout and a bending moment. Cement augmentation with fenestrated screws increased pullout resistance significantly, whereas the fixation strength with the vertebroplasty

  3. Cement Augmentation in Sacroiliac Screw Fixation Offers Modest Biomechanical Advantages in a Cadaver Model.

    PubMed

    Osterhoff, Georg; Dodd, Andrew E; Unno, Florence; Wong, Angus; Amiri, Shahram; Lefaivre, Kelly A; Guy, Pierre

    2016-11-01

    Sacroiliac screw fixation in elderly patients with pelvic fractures is prone to failure owing to impaired bone quality. Cement augmentation has been proposed as a possible solution, because in other anatomic areas this has been shown to reduce screw loosening. However, to our knowledge, this has not been evaluated for sacroiliac screws. We investigated the potential biomechanical benefit of cement augmentation of sacroiliac screw fixation in a cadaver model of osteoporotic bone, specifically with respect to screw loosening, construct survival, and fracture-site motion. Standardized complete sacral ala fractures with intact posterior ligaments in combination with ipsilateral upper and lower pubic rami fractures were created in osteoporotic cadaver pelves and stabilized by three fixation techniques: sacroiliac (n = 5) with sacroiliac screws in S1 and S2, cemented (n = 5) with addition of cement augmentation, and transsacral (n = 5) with a single transsacral screw in S1. A cyclic loading protocol was applied with torque (1.5 Nm) and increasing axial force (250-750 N). Screw loosening, construct survival, and sacral fracture-site motion were measured by optoelectric motion tracking. A sample-size calculation revealed five samples per group to be required to achieve a power of 0.80 to detect 50% reduction in screw loosening. Screw motion in relation to the sacrum during loading with 250 N/1.5 Nm was not different among the three groups (sacroiliac: 1.2 mm, range, 0.6-1.9; cemented: 0.7 mm, range, 0.5-1.3; transsacral: 1.1 mm, range, 0.6-2.3) (p = 0.940). Screw subsidence was less in the cemented group (3.0 mm, range, 1.2-3.7) compared with the sacroiliac (5.7 mm, range, 4.7-10.4) or transsacral group (5.6 mm, range, 3.8-10.5) (p = 0.031). There was no difference with the numbers available in the median number of cycles needed until failure; this was 2921 cycles (range, 2586-5450) in the cemented group, 2570 cycles (range, 2500-5107) for the sacroiliac specimens, and

  4. True anteroposterior view pedicle screw insertion technique

    PubMed Central

    Bai, Jia-yue; Zhang, Wei; An, Ji-long; Sun, Ya-peng; Ding, Wen-yuan; Shen, Yong

    2016-01-01

    Background The wide use of minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) surgery in the treatment of degenerative disc disease of lumbar spine in spinal surgery highlights the gradual decrease in the use of traditional pedicle screw insertion technology. This study aims to analyze the accuracy of the true anteroposterior view pedicle screw insertion technique in MIS-TLIF surgery, compare it with conventional pedicle screw insertion technology, and discuss its clinical application value. Methods Fifty-two patients undergoing true anteroposterior view (group A) and 87 patients undergoing conventional pedicle screw insertion (group B) were diagnosed with lumbar disc herniation or lumbar spinal stenosis. Time for screw placement, intraoperative irradiation exposure, accuracy rate of pedicle screw insertion, and incidence of neurovascular injury were compared between the two groups. Results The time for screw placement and intraoperative irradiation exposure was significantly less in group A. Penetration rates of the paries lateralis of vertebral pedicle, medial wall of vertebral pedicle, and anterior vertebral wall were 1.44%, 0%, and 2.40%, respectively, all of which were significantly lower than that in group B. No additional serious complications caused by the placement of screw were observed during the follow-up period in patients in group A, but two patients with medial penetration underwent revision for unbearable radicular pain. Conclusion The application of true anteroposterior view pedicle screw insertion technique in MIS-TLIF surgery shortens time for screw placement and reduces the intraoperative irradiation exposure along with a higher accuracy rate of screw placement, which makes it a safe, accurate, and efficient technique. PMID:27418828

  5. Maintaining space in localized ridge augmentation using guided bone regeneration with tenting screw technology.

    PubMed

    Chasioti, Evdokia; Chiang, Tat Fai; Drew, Howard J

    2013-01-01

    Prosthetic guided implant surgery requires adequate ridge dimensions for proper implant placement. Various surgical procedures can be used to augment deficient alveolar ridges. Studies have examined new bone formation on deficient ridges, utilizing numerous surgical techniques and biomaterials. The goal is to develop time efficient techniques, which have low morbidity. A crucial factor for successful bone grafting procedures is space maintenance. The article discusses space maintenance tenting screws, used in conjunction with bone allografts and resorbable barrier membranes, to ensure uneventful guided bone regeneration (GBR) enabling optimal implant positioning. The technique utilized has been described in the literature to treat severely resorbed alveolar ridges and additionally can be considered in restoring the vertical and horizontal component of deficient extraction sites. Three cases are presented to illustrate the utilization and effectiveness of tenting screw technology in the treatment of atrophic extraction sockets and for deficient ridges.

  6. Biomechanical comparison of augmented versus non-augmented sacroiliac screws in a novel hemi-pelvis test model.

    PubMed

    Grüneweller, Niklas; Raschke, Michael J; Zderic, Ivan; Widmer, Daniel; Wähnert, Dirk; Gueorguiev, Boyko; Richards, Robert Geoff; Fuchs, Thomas; Windolf, Markus

    2016-08-26

    Operative treatment of sacral insufficiency fractures is frequently being complicated by osteopenic bone properties. Cement augmentation of implanted sacroiliac screws may lead to superior construct stability and prevent mechanical complications. A novel hemi-pelvis test model with dissected symphysis was developed. Five fresh-frozen cadaveric pelvises were vertically osteotomized at the sacrum on both sides and fixed with sacroiliac screws in both corridors of the first sacral vertebral body. One side was randomly augmented with bone cement. Cyclic testing consisting of torsional loading (±2.5 Nm) combined with progressively increasing axial loading (+50 N compression, -10 N traction, ±0,01 N/cycle) was performed until failure; simulated physiological loads derived from inverse dynamic calculations. The fixation was analyzed fluoroscopically quantifying screw migrations and assessing failure mechanisms. Failure modes were cut-out, pull-out, screw-out, and washer penetration. Motion at fracture site was analyzed via optical motion tracking. Unscrewing was provoked four times with non-augmented and twice with augmented screws. When focusing on the sacral region only, cement augmentation significantly improved screw fixation in terms of increased number of cycles to failure (p = 0.043). However, when considering overall construct stability, there was no significant difference between augmented and non-augmented state due to washer penetration at the iliac bone. The generated hemi-pelvis model was found to be valid due to the reproduction of the clinically observed failure mode (unscrewing). Unscrewing was not fully prevented by cement augmentation. Augmentation effects stability at the screw tip, but particularly in porotic bone, failure may shift to the next weak point. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.

  7. Advanced intellect-augmentation techniques

    NASA Technical Reports Server (NTRS)

    Engelbart, D. C.

    1972-01-01

    User experience in applying our augmentation tools and techniques to various normal working tasks within our center is described so as to convey a subjective impression of what it is like to work in an augmented environment. It is concluded that working-support, computer-aid systems for augmenting individuals and teams, are undoubtedly going to be widely developed and used. A very special role in this development is seen for multi-access computer networks.

  8. Advanced Intellect-Augmentation Techniques.

    ERIC Educational Resources Information Center

    Engelbart, D. C.

    This progress report covers a two-year project which is part of a program that is exploring the value of computer aids in augmenting human intellectual capability. The background and nature of the program, its resources, and the activities it has undertaken are outlined. User experience in applying augmentation tools and techniques to various…

  9. In vivo study of pedicle screw augmentation using bioactive glass in osteoporosis sheep.

    PubMed

    Li, Yang; Cheng, Huan; Liu, Zhi-chen; Wu, Jian-wei; Yu, Long; Zang, Yuan; He, Qiang; Lei, Wei; Wu, Zi-xiang

    2013-06-01

    Augmentation of pedicle screws with bioactive glass (BG) was performed in osteoporotic ovine spine in vivo. Biomechanical tests, micro-computed tomography (CT) analysis, and histologic observation were performed. To investigate the biomechanical stability of pedicle screws augmented by BG in osteoporotic sheep and observe the bone-screw interface histologically. There is little information on the long-term biomechanical performance and screw-bone interfacial bonding of pedicle screws augmented with BG in osteoporotic spine in vivo. Twelve months after ovariectomy combined with methylprednisolone injection, 8 adult female sheep were randomly divided into 2 groups (3- and 6-mo time point groups). In each time point group, pedicles were randomly selected from the lumbar spine (L1-L6) and implanted with (1) pedicle screw alone; (2) pedicle screw augmented by polymethylmethacrylate; or (3) pedicle screw augmented by BG. Three and 6 months after implantation, animals were labeled with tetracycline and calcein before being killed. Then vertebrae with pedicle screws were obtained, and a micro-CT scan, histologic analysis, and biomechanical tests were performed. Three months after implantation, micro-CT reconstruction showed that microstructural parameters of the BG group were significantly better compared with those in the other 2 groups (P<0.05). Histologic observation revealed that bone trabeculae around the screws in the BG group were more in number and denser than those in the control group. The average mineral apposition rate of the bone in the BG group was also higher than that in the other 2 groups (P<0.05). The mechanical properties in the BG group were also significantly higher than that in the control group. Six months after implantation, similar results except mineral apposition rate can be obtained among different groups. BG can significantly improve bone microstructure of the interface in osteoporosis condition and increase the hold strength of the pedicle

  10. Biomechanical in vitro assessment of screw augmentation in locked plating of proximal humerus fractures.

    PubMed

    Röderer, Götz; Scola, Alexander; Schmölz, Werner; Gebhard, Florian; Windolf, Markus; Hofmann-Fliri, Ladina

    2013-10-01

    Proximal humerus fracture fixation can be difficult because of osteoporosis making it difficult to achieve stable implant anchorage in the weak bone stock even when using locking plates. This may cause implant failure requiring revision surgery. Cement augmentation has, in principle, been shown to improve stability. The aim of this study was to investigate whether augmentation of particular screws of a locking plate aimed at a region of low bone quality is effective in improving stability in a proximal humerus fracture model. Twelve paired human humerus specimens were included. Quantitative computed tomography was performed to determine bone mineral density (BMD). Local bone quality in the direction of the six proximal screws of a standard locking plate (PHILOS, Synthes) was assessed using mechanical means (DensiProbe™). A three-part fracture model with a metaphyseal defect was simulated and fixed with the plate. Within each pair of humeri the two screws aimed at the region of the lowest bone quality according to the DensiProbe™ were augmented in a randomised manner. For augmentation, 0.5 ml of bone cement was injected in a screw with multiple outlets at its tip under fluoroscopic control. A cyclic varus-bending test with increasing upper load magnitude was performed until failure of the screw-bone fixation. The augmented group withstood significantly more load cycles. The correlation of BMD with load cycles until failure and BMD with paired difference in load cycles to failure showed that augmentation could compensate for a low BMD. The results demonstrate that augmentation of screws in locked plating in a proximal humerus fracture model is effective in improving primary stability in a cyclic varus-bending test. The augmentation of two particular screws aimed at a region of low bone quality within the humeral head was almost as effective as four screws with twice the amount of bone cement. Screw augmentation combined with a knowledge of the local bone quality

  11. Minimally Invasive Spinal Arthrodesis in Osteoporotic Population Using a Cannulated and Fenestrated Augmented Screw: Technical Description and Clinical Experience

    PubMed Central

    Lubansu, Alphonse; Rynkowski, Michal; Abeloos, Laurence; Appelboom, Geoffrey; Dewitte, Olivier

    2012-01-01

    We describe a percutaneous or minimally invasive approach to apply an augmentation of pedicle fenestrated screws by injection of the PMMA bone cement through the implant and determine the safety and efficiency of this technique in a clinical series of 15 elderly osteoporotic patients. Clinical outcome and the function were assessed using respectively the Visual Analogue Scale (VAS) score and the Oswestry Disability Index (ODI). Peri- and post-operative complications were monitored during a minimum of 2 years of follow-up. Radiographic follow-up was based on plain fluoroscopic control at 3, 6 and 12 months and every year. In this approach, four steps were considered with care: optimal positioning of the screws, correct alignment of the screw heads, waiting time before the injection of cement, fluoroscopic control of the cement injection. Using these precautions, only 2 minor complications occurred. VAS scores and ODI questionnaires showed a statistically significant improvement up to 13.3 months postoperatively. No radiological complications were observed. Based on this experience, PMMA augmentation technique through the novel fenestrated screws provided an effective and long lasting fixation in osteoporotic patients. Applying this procedure through percutaneous or minimally invasive approach under fluoroscopic control seems to be safe. PMID:22970360

  12. [Treatment of osteoporotic vertebral compression fractures with PMMA-augmented pedicle screw fixation].

    PubMed

    Padányi Csaba; Misik, Ferenc; Papp, Zoltán; Vitanovics, Dusan; Balogh, Attila; Veres, Róbert; Lipóth, László; Banczerowski, Péter

    2015-01-30

    Over the last few decades many innovative operation technique were developed due to the increase of porotic vertebral fractures. These new techniques aim to reach the required stability of the vertebral column. In case of significant instability, spinal canal stenosis or neural compression, decompressive intervention may be necessary, which results in further weakening of the column of the spine, the minimal invasive percutan vertebroplasty is not an adequate method to reach the required stability, that is why insertion of complementary pedicular screws is needed. Considering the limited screw-fixing ability of the porotic bone structure, with this new technique we are able to reach the appropriate stability of cement-augmented pedicle screws by dosing cement carefully through the screws into the vertebral body. We used this technique in our Institute in case of 12 patients and followed up the required stability and the severity of complications. Fifteen vertebral compression fractures of 12 patients were treated in our Institute. Using the classification proposed by Genant et al. we found that the severity of the vertebral compression was grade 3 in case of 13, while grade 2 in case of two fractures. The average follow up time of the patients was 22 months (12-39), during this period X-ray, CT and clinical control examinations were taken. During the surgery the involved segments were localised by using X-ray and after the exploration the canulated screws were put through the pedicles of the spine and the vertebral body was filled through the transpedicular screws with bone cement. Depending on the grade of the spinal canal stenosis, we made the decompression, vertebroplasty or corpectomy of the fractured vertebral body, and the replacement of the body. Finally the concerned segments were fixed by titanium rods. In all cases the stenosis of spinal canal was resolved and the bone cement injected into the corpus resulted in adequated stability of the spine. In case

  13. Evaluation of calcium sulfate paste for augmentation of lumbar pedicle screw pullout strength.

    PubMed

    Rohmiller, Michael T; Schwalm, Dugan; Glattes, R Chris; Elalayli, Tarek G; Spengler, Dan M

    2002-01-01

    Many authors have evaluated the components responsible for ultimate pullout strength of pedicle screws. In these studies, one important variable has been the screw fixation. Because pedicle screw fixation has increased in popularity over recent years, so has the need for augmentation in difficult situations. Polymethylmethacrylate (PMMA) has been established as the gold standard in terms of strength of fixation but has the potential for severe complications when applied in spine surgery. Calcium sulfate is an alternative to PMMA, because it lacks the exothermic reaction, is potentially osteoconductive and is resorbed by the body in 30 to 60 days. To determine the strength of a new calcium sulfate cement in terms of pedicle screw augmentation. The purpose was to evaluate calcium sulfate versus PMMA in terms of pullout strength. PMMA was considered the gold standard in terms of strength for this experiment. Lumbar vertebrae implanted with pedicle screws were subjected to axial pullout tests. The force required to cause implant failure was measured and compared for three methods of fixation. Force to failure (Newtons) for each pedicle test was recorded and analyzed with results from similarly augmented pedicles. Lumbar vertebrae were harvested from four cadavers and implanted with pedicle screws. These screws were either placed in native bone or augmented with either calcium sulfate paste or PMMA. In those pedicles that had augmentation, the material was permitted to set for a minimum of 24 hours. Axial pullout tests were then performed using an MTS (Materials Testing System Corporation, Minneapolis, MN) testing machine. The screws were pulled out over a distance of up to 6 mm at 0.25 mm/sec. This rate and distance ensured failure in each case. The load to failure was recorded for each pedicle. Calcium sulfate augmentation improved pedicle screw pullout strength significantly when compared with native bone (p=.0003). This represented an average increase of 167% over

  14. Variability of the pullout strength of cancellous bone screws with cement augmentation.

    PubMed

    Procter, P; Bennani, P; Brown, C J; Arnoldi, J; Pioletti, D P; Larsson, S

    2015-06-01

    Orthopaedic surgeons often face clinical situations where improved screw holding power in cancellous bone is needed. Injectable calcium phosphate cements are one option to enhance fixation. Paired screw pullout tests were undertaken in which human cadaver bone was augmented with calcium phosphate cement. A finite element model was used to investigate sensitivity to screw positional placement. Statistical analysis of the data concluded that the pullout strength was generally increased by cement augmentation in the in vitro human cadaver tests. However, when comparing the individual paired samples there were surprising results with lower strength than anticipated after augmentation, in apparent contradiction to the generally expected conclusion. Investigation using the finite element model showed that these strength reductions could be accounted for by small screw positional changes. A change of 0.5mm might result in predicted pullout force changes of up to 28%. Small changes in screw position might lead to significant changes in pullout strength sufficient to explain the lower than expected individual pullout values in augmented cancellous bone. Consequently whilst the addition of cement at a position of low strength would increase the pullout strength at that point, it might not reach the pullout strength of the un-augmented paired test site. However, the overall effect of cement augmentation produces a significant improvement at whatever point in the bone the screw is placed. The use of polymeric bone-substitute materials for tests may not reveal the natural variation encountered in tests using real bone structures. Copyright © 2015 Elsevier Ltd. All rights reserved.

  15. Influence of screw augmentation in posterior dynamic and rigid stabilization systems in osteoporotic lumbar vertebrae: a biomechanical cadaveric study.

    PubMed

    Hoppe, Sven; Sven, Hoppe; Loosli, Yannick; Yannick, Loosli; Baumgartner, Daniel; Daniel, Baumgartner; Heini, Paul; Paul, Heini; Benneker, Lorin; Lorin, Benneker

    2014-03-15

    Biomechanical cadaveric study. To determine whether augmentation positively influence screw stability or not. Implantation of pedicle screws is a common procedure in spine surgery to provide an anchorage of posterior internal fixation into vertebrae. Screw performance is highly correlated to bone quality. Therefore, polymeric cement is often injected through specifically designed perforated pedicle screws into osteoporotic bone to potentially enhance screw stability. Caudocephalic dynamic loading was applied as quasi-physiological alternative to classical pull-out tests on 16 screws implanted in osteoporotic lumbar vertebrae and 20 screws in nonosteoporotic specimen. Load was applied using 2 different configurations simulating standard and dynamic posterior stabilization devices. Screw performance was quantified by measurement of screwhead displacement during the loading cycles. To reduce the impact of bone quality and morphology, screw performance was compared for each vertebra and averaged afterward. All screws (with or without cement) implanted in osteoporotic vertebrae showed lower performances than the ones implanted into nonosteoporotic specimen. Augmentation was negligible for screws implanted into nonosteoporotic specimen, whereas in osteoporotic vertebrae pedicle screw stability was significantly increased. For dynamic posterior stabilization system an increase of screwhead displacement was observed in comparison with standard fixation devices in both setups. Augmentation enhances screw performance in patients with poor bone stock, whereas no difference is observed for patients without osteoporosis. Furthermore, dynamic stabilization systems have the possibility to fail when implanted in osteoporotic bone.

  16. Comparison between two pedicle screw augmentation instrumentations in adult degenerative scoliosis with osteoporosis

    PubMed Central

    2011-01-01

    Background The operative treatment of adult degenerative scoliosis combined with osteoporosis increase following the epidemiological development. Studies have confirmed that screws in osteoporotic spines have significant lower-screw strength with more frequent screw movements within the vertebra than normal spines. Screws augmented with Polymethylmethacrylate (PMMA) or with autogenous bone can offer more powerful corrective force and significant advantages. Methods A retrospective analysis was conducted on 31 consecutive patients with degenerative lumbar scoliosis combined with osteoporosis who had surgery from December 2000. All had a minimum of 2-year follow-up. All patients had posterior approach surgery. 14 of them were fixed with pedicle screw by augmentation with Polymethylmethacrylate (PMMA) and the other 17 patients with autogenous bone. Age, sex and whether smoking were similar between the two groups. Surgical time, blood loss, blood transfusion, medical cost, post surgery ICU time, hospital day, length of oral pain medicines taken, Pre-and postoperative Oswestry disability index questionnaire and surgical revision were documented and compared. Preoperative, postoperative and final follow up Cobb angle, sagittal lumbar curve, correction rate, and Follow up Cobb loss were also compared. Results No significant differences were found between the autogenous bone group and Polymethylmethacrylate group with regards to all the targets above except for length of oral pain medicines taken and surgery cost. 2 patients were seen leakage during operation, but there is neither damage of nerve nor symptom after operation. No revision was needed. Conclusion Both augmentation pedicle screw with Polymethylmethacrylate (PMMA) and autogenous bone treating degenerative lumbar scoliosis combined with osteoporosis can achieve a good surgical result. Less oral pain medicines taken are the potential benefits of Polymethylmethacrylate augmentation, but that is at the cost of more

  17. Pullout performance comparison of novel expandable pedicle screw with expandable poly-ether-ether-ketone shells and cement-augmented pedicle screws.

    PubMed

    Aycan, Mehmet Fatih; Tolunay, Tolga; Demir, Teyfik; Yaman, Mesut Emre; Usta, Yusuf

    2017-02-01

    Aim of this study is to assess the pullout performance of various pedicle screws in different test materials. Polyurethane foams (Grade 10 and Grade 40) produced in laboratory and bovine vertebrae were instrumented with normal, cannulated (cemented), novel expandable and normal (cemented) pedicle screws. Test samples were prepared according to the ASTM F543 standard testing protocols and surgical guidelines. To examine the screw placement and cement distribution, anteriosuperior and oblique radiographs were taken from each sample after insertion process was completed. Pullout tests were performed in an Instron 3369 testing device. Load versus displacement graphs were recorded and the ultimate pullout force was defined as the maximum load (pullout strength) sustained before failure of screw. Student's t-test was performed on each group whether the differences between pullout strength of pedicle screws were significant or not. While normal pedicle screws have the lowest pullout strength in all test materials, normal pedicle screws cemented with polymethylmethacrylate exhibit significantly higher pullout performance than others. For all test materials, there is a significant improvement in pullout strength of normal screws by augmentation. While novel expandable pedicle screws with expandable poly-ether-ether-ketone shells exhibited lower pullout performance than normal screws cemented with polymethylmethacrylate, their pullout performances in all groups were higher than the ones of normal and cannulated pedicle screws. For all test materials, although cannulated pedicle screws exhibit higher pullout strength than normal pedicle screws, there are no significant differences between the two groups. The novel expandable pedicle screws with expandable poly-ether-ether-ketone shells may be used instead of normal and cannulated pedicle screws cemented with polymethylmethacrylate due to their good performances.

  18. Augmentation of pedicle screw fixation strength using an injectable calcium sulfate cement: an in vivo study.

    PubMed

    Yi, Xiaodong; Wang, Yu; Lu, Hailin; Li, Chunde; Zhu, Tianyue

    2008-11-01

    An in vivo landrace model of cement augmentation of pedicle screw was established, and axial pull-out tests and histological analysis were performed. To investigate the long-term in vivo biomechanical performance of pedicle screws augmented with calcium sulfate cement. Little information is available on the long-term biomechanical performance of pedicle screws augmented with calcium sulfate cement in vivo. Ten pedicle screws were implanted into the lumbar vertebrae of 15 adult females landraces weighing 105 to 115 kg. The pedicle screws were augmented with Polymethyl methacrylate (PMMA), augmented with the calcium sulfate cement, or not augmented. The landraces were randomized into 3 study periods of day 1, 6 weeks, and 12 weeks. At the end of the assigned study periods, the animals were killed and axial pull-out tests and histological analyses were conducted on the isolated specimen vertebrae. No significant difference was found among the 1-day, 6-week,and 12-week control group (P > 0.18), no significant difference was found among the 1-day, 6-week and 12-week PMMA group (P > 0.59), and no significant difference was found among the 1-day, 6-week and 12-week calcium sulfate group (P > 0.27). The maximum POS of the PMMA groups was significantly greater than that of the calcium sulfate groups (P < 0.002), the maximum POS of the calcium sulfate groups was significantly greater than that of the control groups (P < 0.004). Histologically progressive absorption of the calcium sulfate was evident. The bone walls around the screws in the 12-week calcium sulfate group were statistically significantly thicker than that of the 12-week control group and that of the 12-week PMMA group. Results of this study demonstrate that the injectable calcium sulfate cement can significantly improve the immediate POS of pedicle screw fixation, and this effect can be maintained even if the calcium sulfate cement has been absorbed completely, which may result from that the calcium sulfate

  19. Short segment pedicle screw instrumentation and augmentation vertebroplasty in lumbar burst fractures: an experience

    PubMed Central

    Akbar, Saleem; Dhar, Shabir A.

    2008-01-01

    To assess the efficacy and feasibility of vertebroplasty and posterior short-segment pedicle screw fixation for the treatment of traumatic lumbar burst fractures. Short-segment pedicle screw instrumentation is a well described technique to reduce and stabilize thoracic and lumbar spine fractures. It is relatively a easy procedure but can only indirectly reduce a fractured vertebral body, and the means of augmenting the anterior column are limited. Hardware failure and a loss of reduction are recognized complications caused by insufficient anterior column support. Patients with traumatic lumbar burst fractures without neurologic deficits were included. After a short segment posterior reduction and fixation, bilateral transpedicular reduction of the endplate was performed using a balloon, and polymethyl methacrylate cement was injected. Pre-operative and post-operative central and anterior heights were assessed with radiographs and MRI. Sixteen patients underwent this procedure, and a substantial reduction of the endplates could be achieved with the technique. All patients recovered uneventfully, and the neurologic examination revealed no deficits. The post-operative radiographs and magnetic resonance images demonstrated a good fracture reduction and filling of the bone defect without unwarranted bone displacement. The central and anterior height of the vertebral body could be restored to 72 and 82% of the estimated intact height, respectively. Complications were cement leakage in three cases without clinical implications and one superficial wound infection. Posterior short-segment pedicle fixation in conjunction with balloon vertebroplasty seems to be a feasible option in the management of lumbar burst fractures, thereby addressing all the three columns through a single approach. Although cement leakage occurred but had no clinical consequences or neurological deficit. PMID:18193300

  20. Bone Cement-Augmented Percutaneous Screw Fixation for Malignant Spinal Metastases: Is It Feasible?

    PubMed Central

    Kim, Pius; Kim, Seok Won

    2017-01-01

    Objective We evaluated the validity of bone cement-augmented percutaneous screw fixation for treating malignant spinal metastases. Methods Between 2011 and 2015, 14 patients (eight men and six women) who underwent bone cement-augmented percutaneous screw fixation for malignant spinal metastases were enrolled in this study. Their life expectancy was considered to be more than one month and less than one year, based on the revised Tokuhashi scoring system. Clinical findings including the back pain scale score, functional outcome, procedure related complications, and survival were assessed preoperatively, postoperatively, and then six months after the procedure. Results Twelve of the patients (86%) survived up to six months after the procedure. Three required mini-open decompressive laminectomy for severe epidural compression. Bone cement-augmented percutaneous screw fixation was performed one level above, one level below, and at the pathologic level itself. The mean operation time was 60 minutes (45–180) and blood loss was less than 100 mL. Prior to surgery, the mean pain score on the visual analogue scale was 8.8, while one month after the procedure, it had reduced to 3.0; this improvement was maintained until the six-month assessment in the surviving patients. All patients were able to sit within the first two days after surgery, and no patient experienced neurological deterioration at the one-month follow up after the surgery. No patient experienced screw loosening during the six months of follow-up. Asymptomatic cement leakage into the epidural space was observed in two patients, but no major complications were observed. Conclusion For selected patients with malignant spinal metastases, bone cement-augmented percutaneous screw fixation can provide significant pain relief and improve quality of life. PMID:28264239

  1. [Polymethylmethacrylate augmentation of bone cement-injectable cannulated pedicle screws for the treatment of degenerative lumbar diseases with osteoporosis].

    PubMed

    Sun, H L; Li, C D; Yang, Z C; Yi, X D; Liu, H; Lu, H L; Li, H; Wang, Y

    2016-12-18

    To describe the application of polymethylmethacrylate augmentation of bone cement-injectable cannulated pedicle screws for the treatment of degenerative lumbar diseases with osteoporosis. Observation group included 14 cases of degenerative lumbar diseases with osteoporosis received polymethylmethacrylate augmentation of bone cement-injectable cannulated pedicle screws from November 2014 to July 2015, control group included 12 cases of degenerative lumbar diseases with osteoporosis received polymethylmethacrylate augmentation with traditional pedicle screws.The operation time, blood loss, number of pedicle screws and number of augmented pedicle screws in the two groups were compared. The bone cement leakage and pulmonary bone cement embolism in the two groups were also compared. The fusion rate and pedicle screws loosening by lumbar X ray and dynamic X ray were evaluated. The clinical results were assessed by visual analog scale (VAS) of pain on lumbar and lower limbers, lumbar Japanese Orthopaedic Association scores (JOA), Prolo functional scores and Oswestry disability (ODI) scores. Differences of operation time and blood loss in the two groups were not statistically significant. The average number of pedicle screws was 9.9±4.7 and the average number of augmented pedicle screws was 5.9±2.6 in observation group while the average number of pedicle screws was 7.1±2.8 and the average number of augmented pedicle screws was 3.0±1.9 in control group. The ratio of augmented pedicle screws was higher in observation group than in control group (0.69±0.30 vs.0.47±0.30,P<0.05). The bone cement leakage rate was lower in observation group than in control group (5/83 vs. 12/42, P<0.01). All the cases in observation group were without leakage to the interspinal canal while one case in control group suffered from bone cement leakage to the interspinal canal with augmentation of 3 pedicle screws. The follow up period was (10.6±2.3) months in observation group and (36.5±7

  2. An accuracy study of computer-planned implant placement in the augmented maxilla using osteosynthesis screws.

    PubMed

    Verhamme, L M; Meijer, G J; Soehardi, A; Bergé, S J; Xi, T; Maal, T J J

    2017-04-01

    Previous research on the accuracy of flapless implant placement of virtually planned implants in the augmented maxilla revealed unfavourable discrepancies between implant planning and placement. By using the osteosynthesis screws placed during the augmentation procedure, the surgical template could be optimally stabilized. The purpose of this study was to validate this method by evaluating its clinically relevant accuracy. Twelve consecutive fully edentulous patients with extreme resorption of the maxilla were treated with a bone augmentation procedure. Virtual implant planning was performed and a surgical template was manufactured. Subsequently, six implants were installed using the surgical template, which was only supported by the osteosynthesis screws. Implant deviations between planning and placement were calculated. A total of 72 implants were installed. Mean deviations found in the mesiodistal direction were 0.817mm at the implant tip and 0.528mm at the implant shoulder. The angular deviation was 2.924°. In the buccolingual direction, a deviation of 1.038mm was registered at the implant tip and 0.633mm at the implant shoulder. The angular deviation was 3.440°. This study showed that implant placement in the augmented maxilla using a surgical template supported by osteosynthesis screws is accurate.

  3. A modified technique for removing a failed abutment screw from an implant with a custom guide tube.

    PubMed

    Taira, Yohsuke; Sawase, Takashi

    2012-04-01

    Fracture of abutment screw is a serious prosthodontic complication. When the abutment screw is fractured at the junction of the screw shank and screw thread, removal of the fractured screw fragment from the screw hole can be difficult. This article describes a modified technique for removing the failed abutment screw with a custom guide tube and tungsten carbide bur. The failed screw can be removed speedily without damaging the screw hole of the implant body or the screw threads.

  4. Modified technique of chin augmentation with MEDPOR for Asian patients.

    PubMed

    Lin, Jinde; Chen, Xiaoping

    2012-09-01

    Commonly used chin implants are made of silicone, expanded polytetrafluoroethylene (e-PTFE), or high-density porous polyethylene (MEDPOR). Although MEDPOR is an effective implant for chin augmentation, modification of the external aspect of the implant is recommended, particularly for Asian patients, to create an appropriate shape for the new chin. It is often difficult to contour the inner aspect of the implant to conform to the patient's mandible. Without modification, a gap may exist between the implant and mandible. To address this problem, a modified augmentation technique was developed. The authors describe their modified technique for MEDPOR chin augmentation, which includes removal of the genial tubercles and, if necessary, the mental protuberance. Ninety-five patients underwent the modified MEDPOR technique of chin augmentation. Before placement of the contoured implant, a drill was used to remove the patient's genial tubercles. If the mental protuberance was deemed too prominent, it was removed as well. The implant was inserted and fixed to the mandible with 2 titanium screws. Results were satisfactory in 90 cases. Chin shape was too "strong" in 4 patients, and another patient had poor transition between the implant and mandible. Complications were minimal. The most common complication in this modified technique was lower lip numbness, which was transient in all cases. The MEDPOR chin implant can be effectively contoured to the mandible by removing the genial tubercle and/or mental protuberance. This technique is less invasive than chin osteotomy. Successful results can be achieved with minimal risks.

  5. Designs and Techniques That Improve the Pullout Strength of Pedicle Screws in Osteoporotic Vertebrae: Current Status

    PubMed Central

    Shea, Thomas M.; Laun, Jake; Gonzalez-Blohm, Sabrina A.; Doulgeris, James J.; Lee, William E.; Vrionis, Frank D.

    2014-01-01

    Osteoporosis is a medical condition affecting men and women of different age groups and populations. The compromised bone quality caused by this disease represents an important challenge when a surgical procedure (e.g., spinal fusion) is needed after failure of conservative treatments. Different pedicle screw designs and instrumentation techniques have been explored to enhance spinal device fixation in bone of compromised quality. These include alterations of screw thread design, optimization of pilot hole size for non-self-tapping screws, modification of the implant's trajectory, and bone cement augmentation. While the true benefits and limitations of any procedure may not be realized until they are observed in a clinical setting, axial pullout tests, due in large part to their reproducibility and ease of execution, are commonly used to estimate the device's effectiveness by quantifying the change in force required to remove the screw from the body. The objective of this investigation is to provide an overview of the different pedicle screw designs and the associated surgical techniques either currently utilized or proposed to improve pullout strength in osteoporotic patients. Mechanical comparisons as well as potential advantages and disadvantages of each consideration are provided herein. PMID:24724097

  6. Posterior arch C-1 screw technique: a cadaveric comparison study.

    PubMed

    Moisi, Marc; Fisahn, Christian; Tkachenko, Lara; Jeyamohan, Shiveindra; Reintjes, Stephen; Grunert, Peter; Norvell, Daniel C; Tubbs, R Shane; Page, Jeni; Newell, David W; Nora, Peter; Oskouian, Rod J; Chapman, Jens

    2017-03-17

    OBJECTIVE Posterior atlantoaxial stabilization and fusion using C-1 lateral mass screw fixation has become commonly used in the treatment of instability and for reconstructive indications since its introduction by Goel and Laheri in 1994 and modification by Harms in 2001. Placement of such lateral mass screws can be challenging because of the proximity to the spinal cord, vertebral artery, an extensive venous plexus, and the C-2 nerve root, which overlies the designated starting point on the posterior center of the lateral mass. An alternative posterior access point starting on the posterior arch of C-1 could provide a C-2 nerve root-sparing starting point for screw placement, with the potential benefit of greater directional control and simpler trajectory. The authors present a cadaveric study comparing an alternative strategy (i.e., a C-1 screw with a posterior arch starting point) to the conventional strategy (i.e., using the lower lateral mass entry site), specifically assessing the safety of screw placement to preserve the C-2 nerve root. METHODS Five US-trained spine fellows instrumented 17 fresh human cadaveric heads using the Goel/Harms C-1 lateral mass (GHLM) technique on the left and the posterior arch lateral mass (PALM) technique on the right, under fluoroscopic guidance. After screw placement, a CT scan was obtained on each specimen to assess for radiographic screw placement accuracy. Four faculty spine surgeons, blinded to the surgeon who instrumented the cadaver, independently graded the quality of screw placement using a modified Upendra classification. RESULTS Of the 17 specimens, the C-2 nerve root was anatomically impinged in 13 (76.5%) of the specimens. The GHLM technique was graded Type 1 or 2, which is considered "acceptable," in 12 specimens (70.6%), and graded Type 3 or 4 ("unacceptable") in 5 specimens (29.4%). In contrast, the PALM technique had 17 (100%) of 17 graded Type 1 or 2 (p = 0.015). There were no vertebral artery injuries found

  7. Biomechanical effects of calcar screws and bone block augmentation on medial support in locked plating of proximal humeral fractures.

    PubMed

    Katthagen, Jan Christoph; Schwarze, Michael; Meyer-Kobbe, Josefin; Voigt, Christine; Hurschler, Christof; Lill, Helmut

    2014-08-01

    The objective of this study was to investigate the biomechanical effects of medial fracture gap augmentation in locked plating of an unstable 2-part proximal humeral fracture with calcar screws and insertion of a corticocancellous bone block. Furthermore the mechanical behavior of dynamic locking screws in the non-parallel arrangement of a proximal humeral plate was of interest. Thirty-two fresh frozen humeri were randomized in four equal groups. An unstable 2-part fracture was fixed by locked plating in all specimens. The basic screw setup was supplemented by additional calcar screws in one group. Humeral head screws were replaced by dynamic locking screws in a second group. The third group featured an additional corticocancellous femoral head allograft. Assessment of stiffness was followed by cyclic loading and load to failure tests. Resulting stiffness, fracture gap deflection and ultimate load were compared utilizing Bonferroni corrected t-test for independent samples. The mechanical effect of additional calcar screws was non-significant as compared to the basic screw configuration whereas bone block insertion significantly increased construct stiffness and failure load. The use of dynamic locking screws did not significantly reduce construct stiffness when compared to conventional locking screws. Additional calcar screws alone did not improve the initial biomechanical properties of an unstable 2-part proximal humeral fracture model. However bone block augmentation appeared to be a reliable alternative of additional bony support by raising stiffness and failure load. Dynamic locking screws did not show their expected dynamic component when used in a non-parallel arrangement. Copyright © 2014 Elsevier Ltd. All rights reserved.

  8. Clinical outcome of modified cervical lateral mass screw fixation technique.

    PubMed

    Kim, Seong-Hwan; Seo, Won-Deog; Kim, Ki-Hong; Yeo, Hyung-Tae; Choi, Gi-Hwan; Kim, Dae-Hyun

    2012-08-01

    The purpose of this study was 1) to analyze clinically-executed cervical lateral mass screw fixation by the Kim's technique as suggested in the previous morphometric and cadaveric study and 2) to examine various complications and bicortical purchase that are important for b-one fusion. A retrospective study was done on the charts, operative records, radiographs, and clinical follow up of thirty-nine patients. One hundred and seventy-eight lateral mass screws were analyzed. The spinal nerve injury, violation of the facet joint, vertebral artery injury, and the bicortical purchases were examined at each lateral mass. All thirty-nine patients received instrumentations with poly axial screws and rod systems, in which one hundred and seventy-eight screws in total. No vertebral artery injury or nerve root injury were observed. Sixteen facet joint violations were observed (9.0%). Bicortical purchases were achieved on one hundred and fifty-six (87.6%). Bone fusion was achieved in all patients. The advantages of the Kim's technique are that it is performed by using given anatomical structures and that the complication rate is as low as those of other known techniques. The Kim's technique can be performed easily and safely without fluoroscopic assistance for the treatment of many cervical diseases.

  9. Biomechanical evaluation of a new augmentation method for enhanced screw fixation in osteoporotic proximal femoral fractures.

    PubMed

    von der Linden, P; Gisep, A; Boner, V; Windolf, M; Appelt, A; Suhm, N

    2006-12-01

    A biomechanical investigation on eight pairs of human cadaver proximal femurs was performed to evaluate the impact of a new augmentation method on the internal fixation of osteoporotic proximal femur fractures. The study focused on enhancing implant purchase to reduce the incidence of implant cut-out in osteoporotic bone. In a left-right comparison, a conventional hip screw fixation (control) was compared to the new cement augmentation method. After bone bed preparation through high pressure irrigation to remove fat, blood, and bone debris, the bones were augmented with low viscosity polymethylmethacrylate (PMMA) cement. Step-wise fatigue testing was performed by cyclically loading the femoral heads in a physiological manner, beginning at 1,500 N and increasing 500 N every 5,000 cycles to 4,000 N, and continuously monitoring head displacement. Failure was defined as >5.0 mm head displacement. The head displacement at 2,000 N was significantly smaller (p=0.018) for the augmented group as compared to the conventionally treated bones (0.09+/-0.01 mm vs. 0.90+/-0.32 mm; mean+/-SEM). The displacement rate at the second load step was significantly higher (p=0.018) for the conventionally treated bones as compared to the augmented ones. All of the nonaugmented specimens failed during testing, where 50% of the augmented specimens did not fail. The promising results of these experiments suggest that this new standardized irrigation/augmentation method enhances the implant anchorage and offers a potential solution to the problem of implant cut-out in osteoporotic metaphyseal bone. Copyright (c) 2006 Orthopaedic Research Society.

  10. Surgical treatment of osteoporotic thoraco-lumbar compressive fractures: the use of pedicle screw with augmentation PMMA.

    PubMed

    Girardo, Massimo; Cinnella, P; Gargiulo, G; Viglierchio, P; Rava, A; Aleotti, S

    2017-03-21

    The osteoporosis prevalence in population is age related. The aim of this single-center observational study was evaluate the middle- to long-term performance of cement (PMMA) augmented fenestrated pedicle screws in elderly patients with thoraco-lumbar compressive fractures by osteoporosis. From 2011 to 2015 we treated 52 patients (20 males and 32 females) suffering from somatic osteoporotic fractures (T10-L2). The average age was 73.4 years, with an age range between 65 and 82 years. The treatment consisted of stabilization with pedicle screw augmentation with PMMA cement. Patients were clinically evaluated with Visual Analyzing System scale (VAS scale) and with low back disability questionnaire Oswestry, in pre and post surgery and during the follow up at 12 and 24 months. A total of 410 fenestrated pedicle screws with PMMA augmentation were implanted. No cases of loosening or pulling out of screws were recorded. There have been n 3 cases of thrombophlebitis, treated with oral anticoagulant drugs and 1 case of post-operative death due to ventricular fibrillation. No neurological complications occurred during the study. The mean VAS score decreased from 8.5 to 4.8 and the result remained stable during follow up. Oswestry questionnaire showed a mean decrease of low back pain of 24% in post-op period. Fenestrated screws with PMMA augmentation offers a possibility to treat patients with reduced bone quality due to severe osteoporosis.

  11. Translaminar screws of the axis--an alternative technique for rigid screw fixation in upper cervical spine instability.

    PubMed

    Meyer, D; Meyer, F; Kretschmer, Th; Börm, W

    2012-04-01

    C2 pedicle screws or transarticular atlantoaxial screws are technically demanding and carry an increased risk of vertebral artery injury. In up to 20% of cases, pedicle and transarticular screw placement is not possible due to a high-riding vertebral artery or very small C2 pedicles in addition to other anatomical variations. Translaminar screws have been reported to rigidly capture posterior elements of C2 and therefore appear to be a suitable alternative. We present our first experiences and clinical results with this new method in two neurosurgical spine centers. Twenty-seven adult patients were treated between 2007 and 2010 in two neurosurgical spine departments with C2 translaminar screw fixation for upper cervical spine instability of various origins (e.g., trauma, tumor, dens pseudarthrosis). Eight patients were men and 19 were women. Mean age was 68.9 years. In most cases, translaminar screws were used because of contraindications for pedicle or transarticular screws as a salvage technique. All patients were clinically assessed and had CT scans postoperatively to verify correct screw placement. Follow-up was performed with reexamination on an ambulatory basis. Mean follow-up was 7.6 months for all patients. In 27 patients, 52 translaminar screws were placed. There were no intraoperative complications. Postoperatively, we identified four screw malpositions using a new accuracy grading scale. One screw had to be revised because of violation of the spinal canal >4 mm. None of the patients had additional neurological deficits postoperatively, and all showed stable cervical conditions at follow-up. Two patients died due to causes not associated with the stabilization technique. The fusion rate for patients with C1/C2 fixation is 92.9%. Translaminar screws can be used at least as an additional technique for cases of upper cervical spine instability when pedicle screw placement is contraindicated or not possible. The current data suggest comparable

  12. [Efficacy analysis of intermediate screws technique plus injectable calcium sulfate for thoracolumbar fracture in postmenopausal patients].

    PubMed

    Yu, Yan; Zeng, Zhi-li; Li, Shan-zhu; Jia, Yong-wei; Jia, Long; Wang, Jian-jie; Wu, Zhou-rui; Hu, Xiao; Xu, Wei; Maharjan, Sujan; Cheng, Li-ming

    2013-12-03

    To explore the clinical efficacies of intermediate screws plus injectable calcium sulfate MIIGX3 for thoracolumbar fracture in postmenopausal patients. A total of 21 postmenopausal patients with vertebral compression fractures reconstructed with posterior internal fixation of intermediate screws technique and anterior vertebral augmentation of MIIGX3 technique in three dimension were retrospectively analyzed. The changes of fracture vertebral height and Cobb's angle were compared.Visual analogue scale (VAS) was performed to evaluate their symptoms. All patients were followed up. Intermediate screws surgical technique plus MIIGX3 was successfully performed. The average injection dose was 4.6 ml.Leakage occurred intraoperatively in two cases. The average follow-up period was 15 (6-36) months. The VAS system demonstrated that pain decreased significantly (preoperative:7.8, postoperative:2.2). The height and Cobb's angle of fractured vertebra improved greatly. The preoperative values were 45.0 ± 6.4% and 19.4 ± 4.5° and postoperative ones 15.4 ± 3.9% and 8.64 ± 3.18° respectively. There was no occurrence of severe complications related with treatment.Except for 2 patients with a loss of 15% of vertebral height, the average heights of fractured vertebra in other 19 patients recovered to 85% of normal ones. Thoracolumbar fracture in postmenopausal patients may be managed satisfactorily by intermediate screws and injectable calcium sulfate technique.Such a technique is both safe and effective. And its stable and durable reduction offers significant improvement.

  13. Precision insertion of percutaneous sacroiliac screws using a novel augmented reality-based navigation system: a pilot study.

    PubMed

    Wang, Huixiang; Wang, Fang; Leong, Anthony Peng Yew; Xu, Lu; Chen, Xiaojun; Wang, Qiugen

    2016-09-01

    Augmented reality (AR) enables superimposition of virtual images onto the real world. The aim of this study is to present a novel AR-based navigation system for sacroiliac screw insertion and to evaluate its feasibility and accuracy in cadaveric experiments. Six cadavers with intact pelvises were employed in our study. They were CT scanned and the pelvis and vessels were segmented into 3D models. The ideal trajectory of the sacroiliac screw was planned and represented visually as a cylinder. For the intervention, the head mounted display created a real-time AR environment by superimposing the virtual 3D models onto the surgeon's field of view. The screws were drilled into the pelvis as guided by the trajectory represented by the cylinder. Following the intervention, a repeat CT scan was performed to evaluate the accuracy of the system, by assessing the screw positions and the deviations between the planned trajectories and inserted screws. Post-operative CT images showed that all 12 screws were correctly placed with no perforation. The mean deviation between the planned trajectories and the inserted screws was 2.7 ± 1.2 mm at the bony entry point, 3.7 ± 1.1 mm at the screw tip, and the mean angular deviation between the two trajectories was 2.9° ± 1.1°. The mean deviation at the nerve root tunnels region on the sagittal plane was 3.6 ± 1.0 mm. This study suggests an intuitive approach for guiding screw placement by way of AR-based navigation. This approach was feasible and accurate. It may serve as a valuable tool for assisting percutaneous sacroiliac screw insertion in live surgery.

  14. Quantitative comparison between the straight-forward and anatomical insertion technique for pedicle screw placement

    NASA Astrophysics Data System (ADS)

    Knez, Dejan; Mohar, Janez; Likar, Boštjan; Pernuš, Franjo; Vrtovec, Tomaž

    2016-03-01

    Spinal deformity correction with vertebral fixation is nowadays the preferred surgical treatment, where pedicle screws are inserted through pedicles into corresponding vertebral bodies and afterwards connected with rods. In clinical practice, the straight-forward and anatomical insertion technique are currently being used for pedicle screw placement surgery. However, it is difficult to quantitatively compare both techniques and determine which technique is more adequate for each planned pedicle screw before surgery (i.e. preoperatively). In this paper, we therefore describe a framework for quantitative comparison between the straight-forward and anatomical insertion technique for pedicle screw placement surgery by evaluating the screw fastening strength. Quantitative comparisons were performed on computed tomography images of 11 patients with 74 manually planned pedicle screws, who underwent the vertebral fixation procedure. The first quantitative comparison was performed between the straight-forward and anatomical pedicle screw insertion technique, which resulted in a relatively high agreement with mean absolute difference of 0.0mm in screw diameter, 2.9mm in screw length, 1.2mm in pedicle crossing point and 6.5° in screw inclinations. The second quantitative comparison was performed between the best resulting pedicle screw insertion technique and manually obtained pedicle screw plans, which again resulted in a relatively high agreement with mean absolute difference of 0.5mm in screw diameter, 4.7mm in screw length, 2.4mm in pedicle crossing point and 6.0° in screw inclinations. Both the straight-forward and anatomical insertion technique proved approximately equal in terms of the screw fastening strength.

  15. Cement-augmented screws in a cervical two-level corpectomy with anterior titanium mesh cage reconstruction: a biomechanical study.

    PubMed

    Hartmann, Sebastian; Thomé, Claudius; Tschugg, Anja; Paesold, Johannes; Kavakebi, Pujan; Schmölz, Werner

    2017-04-01

    Biomechanical investigation. Cervical two-level corpectomies with anterior-only instrumentation are associated with a high rate of implant-related complications. These procedures, therefore, often require an additional dorsal instrumentation to prevent screw loosening. Cement augmentation of the anterior screws in two-level corpectomies might stabilize the construct, so that a second dorsal procedure could be avoided. To evaluate the screw anchorage in cervical anterior-only procedures, an ex vivo evaluation of the range of motion (ROM) in two-level corpectomies (C4 and C5), with and without cement augmentation of the anterior screws, was carried out in this study. Twelve human cervical cadaveric spines (C2-T1) were divided into two groups of six specimens each. Corpectomies were performed in C4 and C5, with grafting and anterior instrumentation with and without cement augmentation of the anterior screw-and-plate system (0.3-0.5 mL cement/screw). Flexibility tests with pure moments (1.5 Nm) were carried out before and after three cyclic loading periods of 5000 cycles with increasing eccentric forces (100, 200, and 300 N). After corpectomy and instrumentation, the control group and the augmented group showed a significant reduction in ROM in comparison with the native states with average ROMs of 49% (±17%) and 24% (±10%), respectively (P = 0.006). The ROM in the control group increased significantly in all motion directions in the course of cyclic loading and approached native values after the third cyclic loading period, with an overall ROM of 78% (±22%). In contrast, the augmented group maintained a significantly decreased ROM in all motion directions during cyclic loading, with a final ROM of 32% (±14%) after the third period of cyclic testing. Inter-group comparison demonstrated a significant difference between the two groups in the course of cyclic loading. The cement-augmented group outperformed the control group in all motion directions, with a

  16. Augmentation cystoplasty: Contemporary indications, techniques and complications

    PubMed Central

    Veeratterapillay, Rajan; Thorpe, Andrew C.; Harding, Chris

    2013-01-01

    Augmentation cystoplasty (AC) has traditionally been used in the treatment of the low capacity, poorly compliant or refractory overactive bladder (OAB). The use of intravesical botulinum toxin and sacral neuromodulation in detrusor overactivity has reduced the number of AC performed for this indication. However, AC remains important in the pediatric and renal transplant setting and still remains a viable option for refractory OAB. Advances in surgical technique have seen the development of both laparoscopic and robotic augmentation cystoplasty. A variety of intestinal segments can be used although ileocystoplasty remains the most common performed procedure. Early complications include thromboembolism and mortality, whereas long-term problems include metabolic disturbance, bacteriuria, urinary tract stones, incontinence, perforation, the need for intermittent self-catheterization and carcinoma. This article examines the contemporary indications, published results and possible future directions for augmentation cystoplasty. PMID:24235795

  17. Easy retrieval of polyaxial tulip-head pedicle screws by “U” rod technique

    PubMed Central

    Isik, Cengiz; Altinel, Levent; Ates, Ali; Ozdemir, Mustafa

    2009-01-01

    The number of fusion surgeries increase each year which also increase the need for implant removal. In some cases, it can be extremely hard to remove a pedicle screw especially when there is a mismatch of the screw and the screwdriver. Also the screwdrivers can be contaminated during the operation, and this will cause a delay till the instruments are re-sterilized. There is a need for the removal of screws without special instruments. We describe a method for removing tulip-head polyaxial pedicle screws without special instruments. The screws are removed using an Allen key, a rod bender and a “U” shaped rod. We successfully removed 76 screws in 11 recent cases without any complications. The “U” rod technique is a simple and useful technique for the removal of tulip-head polyaxial screws. PMID:19618219

  18. Easy retrieval of polyaxial tulip-head pedicle screws by "U" rod technique.

    PubMed

    Kose, Kamil Cagri; Isik, Cengiz; Altinel, Levent; Ates, Ali; Ozdemir, Mustafa

    2010-01-01

    The number of fusion surgeries increase each year which also increase the need for implant removal. In some cases, it can be extremely hard to remove a pedicle screw especially when there is a mismatch of the screw and the screwdriver. Also the screwdrivers can be contaminated during the operation, and this will cause a delay till the instruments are re-sterilized. There is a need for the removal of screws without special instruments. We describe a method for removing tulip-head polyaxial pedicle screws without special instruments. The screws are removed using an Allen key, a rod bender and a "U" shaped rod. We successfully removed 76 screws in 11 recent cases without any complications. The "U" rod technique is a simple and useful technique for the removal of tulip-head polyaxial screws.

  19. Biomechanical analysis of a novel hook-screw technique for C1-2 stabilization.

    PubMed

    Reis, Marco Túlio; Nottmeier, Eric W; Reyes, Phillip M; Baek, Seungwon; Crawford, Neil R

    2012-09-01

    The Food and Drug Administration has not cleared the following medical devices for the use described in this study. The following medical devices are being discussed for an off-label use: cervical lateral mass screws. As an alternative for cases in which the anatomy and spatial relationship between C-2 and a vertebral artery precludes insertion of C-2 pedicle/pars or C1-2 transarticular screws, a technique that includes opposing laminar hooks (claw) at C-2 combined with C-1 lateral mass screws may be used. The biomechanical stability of this alternate technique was compared with that of a standard screw-rod technique in vitro. Flexibility tests were performed in 7 specimens (occiput to C-3) in the following 6 different conditions: 1) intact; 2) after creating instability and attaching a posterior cable/graft at C1-2; 3) after removing the graft and attaching a construct comprising C-1 lateral mass screws and C-2 laminar claws; 4) after reattaching the posterior cable-graft at C1-2 (posterior hardware still in place); 5) after removing the posterior cable-graft and laminar hooks and placing C-2 pedicle screws interconnected to C-1 lateral mass screws via rod; and 6) after reattaching the posterior cable-graft at C1-2 (screw-rod construct still in place). All types of stabilization significantly reduced the range of motion, lax zone, and stiff zone compared with the intact condition. There was no significant biomechanical difference in terms of range of motion or lax zone between the screw-rod construct and the screw-claw-rod construct in any direction of loading. The screw-claw-rod technique restricts motion much like the standard Harms technique, making it an acceptable alternative technique when aberrant arterial anatomy precludes the placement of C-2 pars/pedicle screws or C1-2 transarticular screws.

  20. Finite element analysis of Stryker Xia pedicle screw in artificial bone samples with and without supplemental cement augmentation.

    PubMed

    Pfeiffer, Ferris M; Choma, Theodore J; Kueny, Rebecca

    2015-01-01

    A validated, using in vitro biomechanical testing, finite element model was used to evaluate the affects of (1) cement augmentation and (2) an intact posterior cortex in osteoporotic bone. The presence of augmentation and/or a posterior cortical cortex increased the stabilization of the pedicle screw 2-5 fold. Placement of cement influenced failure load and toggle; with distal placement having the largest increase in failure load and decrease in cephalad-caudad toggle. The presence of posterior cortex caused a decrease in the amount of toggle, a proximal shift of the center of rotation and an increase in the maximum failure force.

  1. Biopolymer augmentation of the lag screw in the treatment of femoral neck fractures - a biomechanical in-vitro study

    PubMed Central

    2010-01-01

    The cut-out of the sliding screw is one of the most common complications in the treatment of intertrochanteric fractures. The reasons for the cut-out are: a suboptimal position of the hip-screw in the femoral head, the type of fracture and poor bone quality. The aim of this study was to reproduce the cut-out event biomechanically and to evaluate the possible prevention of this event by the use of a biopolymer augmentation of the hip screw. Concerning the density and compression force of osteoporotic femoral bone polyurethane foam according to the terms of the Association for Standard Testing Material (ASTMF 1839-97) was used as test material. The polyurethane foam Lumoltan 200 with a compression force of 3.3 Mpa and a density of 0.192 g/cm3 was used to reproduce the osteoporotic bone of the femoral fragment (density 12 lbm/ft3). A cylinder of 50 mm of length and 50 mm of width was produced by a rotary splint raising procedure with planar contact. The axial load of the system was performed by a hydraulic force cylinder of a universal test machine type Zwick 1455, Ulm, Germany. The CCD-angle of the used TGN-System was preset at 130 degrees. The migration pattern of the hip screw in the polyurethane foam was measured and expressed as a curve of the distance in millimeter [mm] against the applied load in Newton [N] up to the cut-out point. During the tests the implants reached a critical changing point from stable to unstable with an increased load progression of steps of 50 Newton. This unstable point was characterized by an increased migration speed in millimeters and higher descending gradient in the migration curve. This peak of the migration curve served as an indicator for the change of the hip screw position in the simulated bone material. The applied load in the non-augmented implant showed that in this group for a density degree of 12 (0,192 g/cm3) the mean force at the failure point was 1431 Newton (± 52 Newton). In the augmented implant we found that the

  2. Augmented osteosynthesis of OTA 44-B fractures in older patients: a technique allowing early weightbearing.

    PubMed

    Assal, Mathieu; Christofilopoulos, Panayiotis; Lübbeke, Anne; Stern, Richard

    2011-12-01

    To determine the effectiveness of an augmented technique of osteosynthesis in allowing early weightbearing in older patients with OTA 44-B (Danis-Weber B) fractures. Case series. University Level I trauma center. Thirty-six patients, nonconsecutive, with OTA 44-B fractures. Augmented internal fixation using an intramedullary wire, lateral plate, and screw augmentation with polymethylmethacrylate. Healed fracture with no loss of reduction. American Orthopaedic Foot and Ankle Society score; percentage of patients who returned to prefracture function. All patients began weightbearing as tolerated in a removable brace at a mean of 13.5 days postoperatively. Thirty patients were available for follow-up at a minimum of 12 months (range, 12-14 months). All fractures healed with no loss of reduction. The mean American Orthopaedic Foot and Ankle Society ankle-hindfoot score was 84.9 (range, 74-100), and 90% of patients returned to prefracture function. There were two infections, one in a 74-year-old diabetic woman and the other in a 92-year-old woman with pre-existing arterial insufficiency and a small ulcer over the tip of the second toe. Augmented internal fixation consisting of intramedullary wire, lateral plate, and screw augmentation with polymethylmethacrylate may allow for very early weightbearing without risk of secondary loss of reduction or disruption of the ankle mortise in older patients with OTA 44-B (Danis-Weber B) malleolar fractures.

  3. Achieving Interfragmentary Compression Without Special Drilling Technique or Screw Design.

    PubMed

    Eastman, Jonathan; Deafenbaugh, Bradley; Christiansen, Blaine; Garcia-Nolen, Tanya; Lee, Mark

    2017-09-08

    Traditional fracture fixation teaching suggests that fully threaded screws do not provide interfragmentary compression unless placed through a glide hole. Based on this assumption, pelvic surgeons typically use fully threaded screws in the treatment of comminuted transforaminal sacral fractures to limit iatrogenic neuroforaminal stenosis. Clinical experience with fully threaded screws suggests that interfragmentary compression actually does occur. We hypothesized that the use of a fully threaded screw does not produce any interfragmentary compression and that there is no difference in insertional torque between partially threaded and fully threaded screws. To test this hypothesis, fully and partially threaded 7.0 millimeter (mm) cannulated screws were placed across two synthetic bone blocks fabricated to simulate normal and osteoporotic bone. We compared two groups of normal and osteoporotic blocks for compression achieved and maximal insertional torque generated with fully threaded and partially threaded screw insertion. A micro computed tomography (CT) scan of the composite blocks was obtained to investigate for structural changes created during screw insertion. For both groups, compression was achieved with fully threaded screws and the maximal insertional torque was higher using fully threaded screws. Micro CT analysis demonstrated local bone damage with structural disruption in the near segment of the fully threaded screw path in comparison to the partially threaded. This study demonstrates that compression is generated using fully threaded screws without using a predrilled glide hole. The insertional torque required to generate compression with fully threaded screws is increased but is clinically applicable. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  4. Augmented reality surgical navigation with ultrasound-assisted registration for pedicle screw placement: a pilot study.

    PubMed

    Ma, Longfei; Zhao, Zhe; Chen, Fang; Zhang, Boyu; Fu, Ligong; Liao, Hongen

    2017-08-05

    We present a novel augmented reality (AR) surgical navigation system based on ultrasound-assisted registration for pedicle screw placement. This system provides the clinically desired targeting accuracy and reduces radiation exposure. Ultrasound (US) is used to perform registration between preoperative computed tomography (CT) images and patient, and the registration is performed by least-squares fitting of these two three-dimensional (3D) point sets of anatomical landmarks taken from US and CT images. An integral videography overlay device is calibrated to accurately display naked-eye 3D images for surgical navigation. We use a 3.0-mm Kirschner wire (K-wire) instead of a pedicle screw in this study, and the K-wire is calibrated to obtain its orientation and tip location. Based on the above registration and calibration, naked-eye 3D images of the planning path and the spine are superimposed onto patient in situ using our AR navigation system. Simultaneously, a 3D image of the K-wire is overlaid accurately on the real one to guide the insertion procedure. The targeting accuracy is evaluated postoperatively by performing a CT scan. An agar phantom experiment was performed. Eight K-wires were inserted successfully after US-assisted registration, and the mean targeting error and angle error were 3.35 mm and [Formula: see text], respectively. Furthermore, an additional sheep cadaver experiment was performed. Four K-wires were inserted successfully. The mean targeting error was 3.79 mm and the mean angle error was [Formula: see text], and US-assisted registration yielded better targeting results than skin markers-based registration (targeting errors: 2.41 vs. 5.18 mm, angle errors: [Formula: see text] vs. [Formula: see text]. Experimental outcomes demonstrate that the proposed navigation system has acceptable targeting accuracy. In particular, the proposed navigation method reduces repeated radiation exposure to the patient and surgeons. Therefore, it has promising

  5. Surgical Techniques to Increase Bone Augmentation Success.

    PubMed

    Resnik, Randy R

    2015-11-01

    Oral implantology has grown into awidely acceptedand ever expanding discipline. Due to this phenomenon, more and more clinicians are offering dental implant surgery in their respective practices. As the discipline of implantology grows, the prevalence of bone grafting will become more significant. Restoring the lost hard-tissue volume to allow ideal implant placement. is crucial to decrease the Morbidity of implants and the restorations they support. Bone augmentation comprises a wide range of materials, donor sites, and surgical approaches, with new advances arriving at a staggering rate. With all of the materials and varying techniques available today, the practitioner must have a solid understanding of adjunct techniques to increase the success of bone grafting.

  6. Screw augmentation reduces motion at the bone-implant interface: a biomechanical study of locking plate fixation of proximal humeral fractures.

    PubMed

    Schliemann, Benedikt; Seifert, Robert; Rosslenbroich, Steffen B; Theisen, Christina; Wähnert, Dirk; Raschke, Michael J; Weimann, Andre

    2015-12-01

    Shear forces at the bone-implant interface lead to a loss of reduction after locking plate fixation of proximal humeral fractures. The aim of the study was to analyze the roles of medial support screws and screw augmentation in failure loads and motion at the bone-implant interface after locking plate fixation of proximal humeral fractures. Unstable 3-part fractures were simulated in 6 pairs of cadaveric humeri and were fixed with a DiPhos-H locking plate (Lima Corporate, Udine, Italy). An additional medial support screw was implanted in 1 humerus of every donor. The opposite humerus was stabilized with a medial support screw and additional bone cement augmentation of the 2 anteriorly directed head screws. Specimens were loaded in the varus bending position. Stiffness, failure loads, plate bending, and the motion at the bone-implant interface were evaluated using an optical motion capture system. The mean load to failure was 669 N (standard deviation [SD], 117 N) after fixation with medial support screws alone and 706 N (SD, 153 N) after additional head screw augmentation (P = .646). The initial stiffness was 453 N/mm (SD, 4.16 N/mm) and 461 N/mm (SD, 64.3 N/mm), respectively (P = .594). Plate bending did not differ between the 2 groups. However, motion at the bone-implant interface was significantly reduced after head screw augmentation (P < .05). The addition of bone cement to augment anteriorly directed head screws does not increase stiffness and failure loads but reduces motion at the bone-implant interface. Thus, the risk of secondary dislocation of the head fragment may be reduced. Copyright © 2015 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.

  7. Comparison of oil refining and biodiesel production process between screw press and n-hexane techniques from beauty leaf feedstock

    NASA Astrophysics Data System (ADS)

    Bhuiya, M. M. K.; Rasul, M. G.; Khan, M. M. K.; Ashwath, N.

    2016-07-01

    The Beauty Leaf Tree (Callophylum inophyllum) is regarded as an alternative source of energy to produce 2nd generation biodiesel due to its potentiality as well as high oil yield content in the seed kernels. The treating process is indispensable during the biodiesel production process because it can augment the yield as well as quality of the product. Oil extracted from both mechanical screw press and solvent extraction using n-hexane was refined. Five replications each of 25 gm of crude oil for screw press and five replications each of 25 gm of crude oil for n-hexane were selected for refining as well as biodiesel conversion processes. The oil refining processes consists of degumming, neutralization as well as dewaxing. The degumming, neutralization and dewaxing processes were performed to remove all the gums (phosphorous-based compounds), free fatty acids, and waxes from the fresh crude oil before the biodiesel conversion process carried out, respectively. The results indicated that up to 73% and 81% of mass conversion efficiency of the refined oil in the screw press and n-hexane refining processes were obtained, respectively. It was also found that up to 88% and 90% of biodiesel were yielded in terms of mass conversion efficiency in the transesterification process for the screw press and n-hexane techniques, respectively. While the entire processes (refining and transesterification) were considered, the conversion of beauty leaf tree (BLT) refined oil into biodiesel was yielded up to 65% and 73% of mass conversion efficiency for the screw press and n-hexane techniques, respectively. Physico-chemical properties of crude and refined oil, and biodiesel were characterized according to the ASTM standards. Overall, BLT has the potential to contribute as an alternative energy source because of high mass conversion efficiency.

  8. Evaluation of different screw fixation techniques and screw diameters in sagittal split ramus osteotomy: finite element analysis method.

    PubMed

    Sindel, A; Demiralp, S; Colok, G

    2014-09-01

    Sagittal split ramus osteotomy (SSRO) is used for correction of numerous congenital or acquired deformities in facial region. Several techniques have been developed and used to maintain fixation and stabilisation following SSRO application. In this study, the effects of the insertion formations of the bicortical different sized screws to the stresses generated by forces were studied. Three-dimensional finite elements analysis (FEA) and static linear analysis methods were used to investigate difference which would occur in terms of forces effecting onto the screws and transmitted to bone between different application areas. No significant difference was found between 1·5- and 2-mm screws used in SSRO fixation. Besides, it was found that 'inverted L' application was more successful compared to the others and that was followed by 'L' and 'linear' formations which showed close rates to each other. Few studies have investigated the effect of thickness and application areas of bicortical screws. This study was performed on both advanced and regressed jaws positions.

  9. Lateral mass screw fixation of the atlas: surgical technique and anatomy.

    PubMed

    Joaquim, Andrei F; Ghizoni, Enrico; Rubino, Pablo A; Anderle, Diogo V; Tedeschi, Helder; Rhoton, Albert L; de Oliveira, Evandro

    2010-01-01

    The use of lateral mass atlas screws is an important technique to achieve fusion and stability at the craniocervical region affected by different pathologies (degenerative, traumatic, inflammatory, neoplastic, or congenital). This paper describes the anatomy and techniques necessary for proper insertion of posterior C1 lateral mass screws, using anatomic dissection and intraoperative pictures. Knowledge of the anatomy and the surgical technique of insertion of C1 lateral mass screws are of paramount importance to have good surgical results. Copyright © 2010 Elsevier Inc. All rights reserved.

  10. Cervical pedicle screw placement using the "key slot technique": the feasibility and learning curve.

    PubMed

    Lee, Sang-Hun; Kim, Ki-Tack; Abumi, Kuniyoshi; Suk, Kyung-Soo; Lee, Jung Hee; Park, Kyung-Jun

    2012-12-01

    A retrospective study. To present the accuracy and safety of a novel "key slot (KS)" technique for cervical pedicle screw (CPS) placement with the learning curve. Safety and learning curve are the issues preventing wide acceptance of CPS. On the basis of the local anatomy of the pedicle, the authors modified the conventional technique to increase the accuracy and comfortableness of CPS placement with minimal bone loss. A total of 277 subaxial CPS in 50 patients had been inserted using author's technique were reviewed. The KS-shaped entry was created on the medial half of the lateral mass with a 3 mm cutting burr. The shape of entry was a right-angled triangle on the axial plane. The apex of triangle was the virtual pedicle inlet and the oblique side was same as pedicle axis. After making entry, the pedicle was probed with a curved awl along the medial wall. On the postoperative vascular-enhanced computed tomography scan, we analyzed the direction and grade of pedicle perforation (grade 0: no perforation, 1:< 25%, 2: 20% to 50%, 3: > 50% of screw diameter) on the chronological group of consecutive 10 cases. Grade 2 and 3 were considered as incorrect position. The correct position was found in 250 screws (90.3%); grade 0 - 215 screws, 1 - 35 screws and the incorrect position in 27 screws (9.7%); grade 2 - 21 screws, grade 3 - 6 screws. The incidence of incorrect screw position was 18% in the initial 20 cases and 2.7% after that. There was no neurovascular complication related with CPS. We performed CPS placement using the KS technique and with 90% correct position without clinical complications. After the learning curve, the incidence was 2.7%. This technique could be considered relatively concrete and safe modification of conventional technique with minimal bone loss.

  11. Evaluation of a fiber reinforced drillable bone cement for screw augmentation in a sheep model--mechanical testing.

    PubMed

    Ahern, Benjamin J; Harten, Robert D; Gruskin, Elliott A; Schaer, Thomas P

    2010-06-01

    We evaluated the mechanical properties of a novel fiber reinforced calcium phosphate at time zero and after 12 weeks in vivo using a sheep long bone osteotomy model. Time zero data were obtained and compared by pullout testing of 4.5 mm bone screws from bone proper and overdrilled defects of 4.5 and 8 mm diameter. Defects were augmented with: polymethylmethacrylate (PMMA), calcium phosphate, and fiber reinforced calcium phosphate using cadaveric sheep tibiae. Twelve-week data were obtained from explanted tibiae of sheep that underwent unilateral tibial osteotomy surgery repaired with a locking compression plate. The most distal hole was overdrilled to 4.5 or 8 mm diameter, filled with fiber reinforced cement, drilled, tapped and a 4.5 mm screw was placed. Screw holding strength at t= 0 was significantly higher for reinforced when compared to nonreinforced cement, but not different from bone or PMMA in 4.5 mm defects. There was no difference in pullout strength for the 8 mm defect data. After 12 weeks fiber reinforced pullout strength increased by 45% and 8.9% for 4.5 and 8 mm defects, respectively, when compared to t= 0 testing. Fiber reinforced calcium phosphate bone cement can be drilled and tapped to support orthopedic hardware for trauma applications.

  12. Modified Tension - Slide Technique for Anatomical Distal Biceps Tenodesis using a Bicortical EndoButton and a Tenodesis Screw.

    PubMed

    Prabhu, Jagadish; Faqi, Mohammed Khalid; Al-Khalifa, Fahad; Awad, Rashad Khamis

    2016-01-01

    Many surgical techniques have been described in the literature. In this article, we describe surgical technical details along with tips and tricks of distal biceps tendon tenodesis using the EndoButton and tension - slide technique, a modification of the suspensory cortical button technique, which allows the surgeon to tension and repairs the biceps tendon through the single longitudinal anterior incision. This modification in surgical technique of using dual implants, i.e., EndoButton and interference screw as fixation tools and concept of tendon sliding principle made this procedure unique. In this article, we describe surgical technique along with tips and tricks of distal biceps tendon tenodesis using the EndoButton and tension - slide technique and also discussed about modification of EndoButton technique reported in many other articles to overcome the possible complications. We report six consecutive patients, presented with distal biceps tendon rupture (4 acute; 2 chronic cases) between June 2013 and March 2015, who underwent single-incision, anatomical distal biceps tenodesis procedure with bicortical EndoButton and tenodesis screw using tension slide technique. Radiographs were taken immediate post-operative to document for displacement or loosening of EndoButton if any. The use of an EndoButton and an interference screw for repairing distal biceps tendons have been previously described. We describe a modification of originally described technique which is worth considering, as it provides two levels of fixation, whilst avoiding possible complications of such procedures. It is ideal for repairing both acute and chronic ruptures, without the need for allograft or autograft augmentation and describes detailed technical steps to avoid possible iatrogenic complications.

  13. Augmentation techniques for rotator cuff repair.

    PubMed

    Papalia, Rocco; Franceschi, Francesco; Zampogna, Biagio; D'Adamio, Stefano; Maffulli, Nicola; Denaro, Vincenzo

    2013-01-01

    There is a high rate of recurrence of tear and failed healing after rotator cuff repair. Several strategies have proposed to augment rotator cuff repairs to improve postoperative outcome and shoulder performance. We systematically review the literature on clinical outcome following rotator cuff augmentation. We performed a comprehensive search of Medline, CINAHL, Embase and the Cochrane Central Registry of Controlled Trials, from inception of the database to 20 June 2012, using various combinations of keywords. The reference lists of the previously selected articles were then examined by hand. Only studies focusing on clinical outcomes of human patients who had undergone augmented rotator cuff repair were selected. We then evaluated the methodological quality of each article using the Coleman methodology score (CMS), a 10 criteria scoring list assessing the methodological quality of the selected studies (CMS). Thirty-two articles were included in the present review. Two were retrospective studies, and 30 were prospective. Biologic, synthetic and cellular devices were used in 24, 7 and 1 studies, respectively. The mean modified Coleman methodology score was 64.0. Heterogeneity of the clinical outcome scores makes it difficult to compare different studies. None of the augmentation devices available is without problems, and each one presents intrinsic weaknesses. There is no dramatic increase in clinical and functional assessment after augmented procedures, especially if compared with control groups. More and better scientific evidence is necessary to use augmentation of rotator cuff repairs in routine clinical practice.

  14. Stabilization of subaxial cervical spines by lateral mass screw fixation with modified Magerl's technique.

    PubMed

    Wu, Jau-Ching; Huang, Wen-Cheng; Chen, Yu-Chun; Shih, Yang-Hsin; Cheng, Henrich

    2008-12-01

    There are various techniques in lateral mass screw placement in the cervical spine currently available, including the Roy-Camille, Magerl, Anderson, and An techniques. Each has different entrance points and trajectories for screw insertion, and some even have different methods for different level of the subaxial cervical spine. The potential risk of vascular and neurologic injury varies with different techniques and different levels of the cervical spine. We proposed a modified technique with a universal method of screw placement suitable for stabilization of every level of the subaxial cervical spines, from C3 to C7. We have applied this modified technique on a large series of patients and obtained satisfactory results. A retrospective study was conducted of the charts, records, and clinical follow-up of 115 patients who received internal fixation with lateral mass screws and rods in the Department of Neurosurgery of Taipei Veterans General Hospital (Taipei, Taiwan) from 2004 to 2006. All patients received lateral mass screw placement in various levels of the subaxial cervical spines. The clinical and radiologic follow-up were carefully evaluated and analyzed. All 115 patients with different pathological situations requiring stabilization received instrumentations with polyaxial screws and rod systems, in which 673 screws in total were used in various levels of the cervical spine between C3 and C7: 129 screws in C3, 115 in C4, 193 in C5, 101 in C6, and 135 in C7. The most often used screw length was 16 mm (385/673, 57%). Good bony fusion was observed in all patients except 1 (99.1%). The mean follow-up period was 14 months (4-35 months). No neurologic or vascular injury was noted clinically. Follow-up radiologic examinations found that the screw placements were well positioned. Based on our experience, lateral mass fixation of subaxial cervical spines with our modified technique is safe and effective. This technique of lateral mass screw placement yielded good

  15. Accuracy and safety of pedicle screw placement in neuromuscular scoliosis with free-hand technique.

    PubMed

    Modi, Hitesh N; Suh, Seung Woo; Fernandez, Harry; Yang, Jae Hyuk; Song, Hae-Ryong

    2008-12-01

    It is a retrospective analytic study of 1,009 transpedicular screws (689 thoracic and 320 lumbosacral), inserted with free-hand technique in neuromuscular scoliosis using postoperative CT scan. The aim of paper was to determine the accuracy and safety of transpedicular screw placement with free-hand technique in neuromuscular scoliosis and to compare the accuracy at different levels in such population. All studies regarding accuracy and safety of pedicle screw in scoliosis represent idiopathic scoliosis using various techniques such as free-hand, navigation, image intensifier, etc., for screw insertion. Anatomies of vertebrae and pedicle are distorted in scoliosis, hence accurate and safe placement of pedicle screw is prerequisite for surgery. Between 2004 and 2006, 37 consecutive patients, average age 20 years (9-44 years), of neuromuscular scoliosis were operated with posterior pedicle screw fixation using free-hand technique. Accuracy of pedicle screws was studied on postoperative CT scan. Placement up to 2 mm medial side and 4 mm lateral side was considered within-safe zone. Of the 1,009 screws, 273 screws were displaced medially, laterally or on the anterior side showing that 73% screws (68% in thoracic and 82.5% in lumbar spine) were accurately placed within pedicle. Considering the safe zone, 93.3% (942/1009, 92.4% in thoracic and 95.3% in lumbar spine) of the screws were within the safe zone. Comparing accuracy according to severity of curve, accuracy was 75% in group 1 (curve <90 degrees ) and 69% in group 2 (curve >90 degrees) with a safety of 94.8 and 91.2%, respectively (P = 0.35). Comparing the accuracy at different thoracic levels, it showed 67, 64 and 72% accuracy in upper, middle and lower thoracic levels with safety of 96.6, 89.2 and 93.1%, respectively, exhibiting no statistical significant difference (P = 0.17). Pedicle screw placement in neuromuscular scoliosis with free-hand technique is accurate and safe as other conditions.

  16. Radiation-free Insertion of Distal Interlocking Screw in Tibial and Femur Nailing: A Simple Technique

    PubMed Central

    Soni, Ritesh Kumar; Mehta, Surender Mohan; Awasthi, Bhanu; Singh, Janith Lal; Kumar, Amit; Thakur, Lokesh; Tripathy, Sujit Kumar

    2012-01-01

    Background: Distal interlocking screw insertion in intramedullary nailing of long-bone fracture is a challenging task for orthopedic surgeons. It is difficult particularly when the surgeon is in his learning stage or when image intensifier is not available. We describe a radiation-free technique of distal interlocking screw insertion which is easy and practicable. Materials and Methods: In this technique, a same length nail is placed over the skin (outer nail) and through its distal-most screw hole, a 3.2 mm drill bit is inserted to drill the distal locking screw hole of the intramedullary nail (inner nail). With a small skin incision over the distal screw holes, the distal-most screw hole is identified; the bone window overlying the screw hole is widened with an awl and a locking bolt is inserted with a washer under direct visualization. The other distal interlocking screw is simply drilled by matching the other three holes of the outer and inner nails. We have operated 86 patients (39 femoral shaft fracture and 47 tibial shaft fracture) in 1 year where this technique was used. There were 41 open fracture and 45 closed fracture. Results: Within 6 months of follow-up, bony union was achieved in 36 of 39 femur fractures and 45 of 47 tibial fractures. No unwanted complications were observed during the postoperative period and in follow-up. Conclusion: This method of radiation-free distal interlocking screw insertion is simple and can be used in third world country where image intensifier facility is not available. However, surgeons are encouraged to use image intensifier facility where the facility is available. PMID:23066456

  17. COMPLICATIONS OF THE SCREW/WASHER TIBIAL FIXATION TECHNIQUE FOR KNEE LIGAMENT RECONSTRUCTION

    PubMed Central

    Almeida, Alexandre; Roveda, Gilberto; Valin, Márcio Rangel; Almeida, Nayvaldo Couto de; Sartor, Vanderlei; Alves, Soraya Melina

    2015-01-01

    To evaluate the presence of pain at the site of the surgical incision and the need to remove the tibial fixation screw in anterior cruciate ligament (ACL) reconstruction, in relation to sex and body mass index (BMI). Methods: A group of 265 patients who underwent ACL reconstruction with ipsilateral flexor tendon grafts from the thigh in which the tibial fixation technique consisted of using a cortical screw and metal washer, between July 2000 and November 2007, were evaluated. Results: 176 patients were evaluated for an average of 33.3 ± 19.5 months; median of 29.5 months; IIQ: 17-45 months; minimum of 8 and maximum of 87 months. There was no statistical difference regarding complaints of pain at the site of the screw (p = 0.272) and the need to remove the tibial screw (p = 0.633) between sexes. There was no statistical difference regarding complaints of pain at the site of the screw (p = 0.08) and the need to remove the tibial screw (p = 0.379) according to BMI. Conclusion: The pain complaint rate at the screw site from the screw and metal washer method used for tibial fixation in ACL reconstruction was of the order of 25%, and the screw had to be removed in 10.8% of the cases. There was no predominance of pain complaints at the surgical wound between the sexes. There was a greater tendency to complain about pain among patients with BMI < 25. There was no predominance of screw and washer removal between the sexes or between individuals with different BMIs. PMID:27022587

  18. A Simple Technique for Fabricating a Screw-Retained/Cemented Implant-Supported Crown.

    PubMed

    Helvey, Gregg A

    2017-03-01

    Many factors figure into the long-term success of an implant-supported restoration. While some are uncontrollable, others are manageable. The cement-retained implant-supported restoration is easier to fabricate, while the screw-retained implant-supported restoration involves more complicated, timeconsuming laboratory procedures. Most research has found the screw-retained restoration has had more minimal complications than the cement-retained counterpart. This article describes a simple, low-cost technique of converting a cement-retained implant crown to a screw-retained implant crown, which allows for easy retrievability and eliminates a number of laboratory steps and costs.

  19. Twin screw wet granulation: the study of a continuous twin screw granulator using Positron Emission Particle Tracking (PEPT) technique.

    PubMed

    Lee, Kai T; Ingram, Andy; Rowson, Neil A

    2012-08-01

    In this paper, Positron Emission Particle Tracking (PEPT) techniques are utilised to track the trajectory of single particles through the mixing and conveying zones of a Twin Screw Granulator (TSG). A TSG consisting of conveying zones and mixing zones is used in this study. The mixing zones are arranged with kneading discs at an angle of 30°, 60° or 90°. Experiments were carried out using different mixing configurations with various screw speed and total mass flow rate. The PEPT data obtained were then utilised to obtain the residence time distribution (RTD) and the Peclet number in an attempt to gain some insight into the mixing of the process. The fill level of the granulator was also estimated to study the mechanism of granulation. As might be expected, it was shown that the residence time of the granulation process increases with decreasing screw speed. It also increases with increasing angle of the arrangement of kneading blocks in the mixing zones, but will decreases when powder feed rate is increased. The fill level of the mixing zone in particular increases when the screw speed decreases or when powder feed rate increases. Furthermore, the fill level of the granulator will increase when the mixing zone configuration changes from 30° to 90°. It is shown that the granulator is never fully filled, even using 90° mixer elements implying limited compaction which may explain why the granules produced are porous compared with those from a high shear mixer. Interestingly, the RTD analysis reveals that the extent of axial mixing in the mixing zone of the granulator does not change significantly for different configurations and process conditions. There is evidence of a tail in the RTD which implies some material hold up and channelling.

  20. Using the freehand pedicle screw placement technique in adolescent idiopathic scoliosis surgery: what is the incidence of neurological symptoms secondary to misplaced screws?

    PubMed

    Dede, Ozgur; Ward, William Timothy; Bosch, Patrick; Bowles, Austin J; Roach, James W

    2014-02-15

    Retrospective case series. This study evaluated the incidence of postoperative neurological symptoms after a freehand pedicle screw insertion technique in idiopathic posterior scoliosis surgery. It is generally accepted that pedicle screws can be inserted by a freehand technique in the thoracic and lumbar spine in patients with adolescent idiopathic scoliosis (AIS) with a very low frequency of major complications. The prevalence of clinically significant screw misplacement, with or without the need for revision surgery is less well defined. Between January 1, 2000, and October 2, 2012, five hundred fifty-nine patients with AIS had thoracolumbar posterior instrumented spine surgery at the Children's Hospital of Pittsburgh. Each patient's chart and radiographs were reviewed and only those with AIS were included. Patients with neuromuscular and syndromic diagnoses were excluded as well as those with congenital or traumatic etiologies, incomplete charts, less than 3 months of follow-up and those without pedicle screws. The records were studied for complaints of radicular pain, neurological deficit, or severe headache that could be indicative of potential screw misplacement. Four hundred eighty-one patients with 5923 pedicle screws met the inclusion criteria. Nine patients (1.9%) developed symptoms and underwent computed tomographic scanning. Six patients were found to have pedicle screw malposition (8 screws) and 3 of these patients underwent revision surgery. Of the 3 revision patients, 2 presented with radicular symptoms (leg pain) and 1 with an orthostatic headache due to cerebrospinal fluid leakage. At the final follow-up, all revision patients had complete symptom resolution. In total, there were 8 symptomatic, misplaced pedicle screws (0.14%) in 6 patients (1.25%). During a 12-year period in a dedicated pediatric orthopedic hospital using the freehand placement technique, the incidence of symptomatic misplaced pedicle screws was exceedingly low. 4.

  1. The Effect of Polymethyl Methacrylate Augmentation on the Primary Stability of Cannulated Bone Screws in an Anterolateral Plate in Osteoporotic Vertebrae: A Human Cadaver Study.

    PubMed

    Rüger, Matthias; Sellei, Richard M; Stoffel, Marcus; von Rüden, Christian

    2016-02-01

    Study Design Cohort study. Objective Expandable anterolateral plates facilitate the reduction of posttraumatic deformities of thoracolumbar spine injuries and are commonly used in cases of unstable injuries or compromised bone quality. In this in vitro study, the craniocaudal yield load of the osseous fixation of an anterior angular stable plate fixation system and the effect of polymethyl methacrylate (PMMA) screw augmentation on the primary stability of the screw-bone interface during kyphosis reduction was evaluated in 12 osteoporotic human thoracolumbar vertebrae. Methods The anterolateral stabilization device used for this study is comprised of two swiveling flanges and an expandable midsection. It facilitates the controlled reduction of kyphotic deformities in situ with a geared distractor. Single flanges were attached to 12 thoracolumbar vertebrae. Six specimens were augmented with PMMA by means of cannulated bone screws. The constructs were subjected to static, displacement-controlled craniocaudal loading to failure in a servohydraulic testing machine. Results The uncemented screws cut out at a mean 393 ± 66 N, whereas the cemented screws showed significantly higher yield load of 966 ± 166 N (p < 0.02). We detected no significant correlation between bone mineral density and yield load in this setting. Conclusion Our results indicate that PMMA augmentation is an effective method to increase two- to threefold the primary stability of the screw-bone interface of an anterolateral spine stabilization system in osteoporotic bone. We recommend it in cases of severely compromised bone quality to reduce the risk of screw loosening during initial kyphosis correction and to increase long-term construct stability.

  2. A biomechanical study to evaluate the effect of PMMA augmentation and restoration of the strength of cervical vertebral screws inserted in an osteoporotic vertebral body.

    PubMed

    Chen, Chun; Zhao, Weidong; Liu, Dongxu; Sun, Peidong; Wu, Changfu; Ouyang, Jun

    2014-06-01

    An experimental study. To compare the peak pull-out force (PPF) of vertebral screws fixed in osteoporotic vertebrae versus polymethylmethacrylate (PMMA) used for augmentation or restoration, before and after fatigue. Failure of screw fixation in anterior cervical interbody fusion remains a significant clinical problem. However, little is known of the biomechanical characteristics of cervical vertebral screws before and after restoration or augmentation, especially after fatigue. Fifty fresh cervical vertebrae, of which 40 were randomly selected, from 12 adult cadavers were used. The vertebrae were divided into healthy controls, osteoporotic controls, a PMMA restoration group, and a PMMA augmentation group. In each of the control groups, 2 pilot holes on each side of 20 vertebral bodies were implanted with vertebral screws (4 mm in diameter). Each side randomly received either acute PPF or PPF beyond fatigue that was ensured using cyclic loading (2 Hz; 20,000 times). In the PMMA groups, pilot holes were drilled parallel to the sagittal plane and injected with 0.6-1.0 mL PMMA before the vertebral screw was inserted. Each side of each vertebral body randomly received either PPF or PPF beyond fatigue that was ensured using cyclic loading (2 Hz; 20,000 times). A Bose3510-AT fatigue testing machine measured the PPF of vertebral screws with or without PMMA for all specimens before and after fatigue. In all groups, the prefatigue PPF was significantly higher than the postfatigue PPF. Compared with the prefatigue PPF, postfatigue PPF was reduced by 37.40%, 43.10%, 32.08%, and 31.85% in the healthy controls, osteoporotic controls, PMMA restoration, and PMMA augmentation groups, respectively. The acute and postfatigue PPFs of the healthy controls were significantly higher from that of the osteoporotic controls. The acute and postfatigue PPFs of both control groups were significantly lower from that of both PMMA groups. There was no difference in acute and postfatigue PPFs

  3. Phase Diversity and Polarization Augmented Techniques for Active Imaging

    DTIC Science & Technology

    2007-03-01

    Phase Diversity and Polarization Augmented Techniques for Active Imaging DISSERTATION Peter M. Johnson, Captain, USAF AFIT/DS/ENG/07-05 DEPARTMENT OF...Force, Department of Defense, or the United States Government. AFIT/DS/ENG/07-05 Phase Diversity and Polarization Augmented Techniques for Active Imaging...must be used. To facilitate this, a multi-frame active phase diversity imaging (APDI) algorithm is derived and demonstrated for the statistics of

  4. Metaphyseal screw augmentation of the LISS-PLT plate with polymethylmethacrylate improves angular stability in osteoporotic proximal third tibial fractures: a biomechanical study in human cadaveric tibiae.

    PubMed

    Goetzen, Michael; Nicolino, Tomas; Hofmann-Fliri, Ladina; Blauth, Michael; Windolf, Markus

    2014-05-01

    The incidence of osteoporotic proximal tibial fractures has increased during the last 2 decades. A promising approach in osteoporotic fracture fixation is polymethylmethacrylate-based cement augmentation of implants to gain better implant purchase in the bone. This study investigates the biomechanical benefits of screw augmentation in less invasive stabilization system-proximal lateral tibial (LISS-PLT) plates in cadaveric extraarticular comminuted proximal tibial fractures (OTA-41-A3.3). Standardized extraarticular proximal tibial fractures were stabilized with the LISS-PLT plate in 6 paired osteoporotic cadaveric tibiae. Bone mineral density was measured with high-resolution, quantitative computed tomography scans to identify bone quality. In the augmented group, the 5 proximal screws of the LISS-PLT plate were augmented with 1 mL of bone cement each, whereas the contralateral tibia was instrumented conventionally as the control. Cyclic axial loading was applied to each specimen with a starting load of 150 N, using a ramp of 0.05 N per cycle to 10-mm axial displacement. Varus displacement was identified from anterior-posterior radiographs. Bone mineral density showed no significant difference between the 2 groups (P = 0.47). The nonaugmented group reached 9417 load cycles (SD 753) until failure, compared with 14,792 load cycles (SD 2088) in the augmented group (P = 0.002). In the early-onset failure (deformation at 8250 load cycles), varus displacement was significantly smaller in the augmented group (0.46 degrees, SD 0.6) than in the nonaugmented group (3.23 degrees, SD 1.7) (P = 0.01). This biomechanical study showed that cement augmentation of the LISS-PLT plate screws in osteoporotic proximal extraarticular tibial fractures significantly lowers the propensity toward screw migration and secondary varus displacement.

  5. Cortical lamina technique: A therapeutic approach for lateral ridge augmentation using guided bone regeneration

    PubMed Central

    Thomas, Raison; Baron, Tarun-Kumar; Shah, Rucha; Mehta, Dhoom-Singh

    2017-01-01

    Background The present study aimed at evaluating the efficacy of a novel technique, the bone lamina technique, in horizontal ridge augmentation clinically & radiographically using a combination of allogenic cortical shell, particulate xenograft and resorbable collagen membrane. Material and Methods Localized horizontal ridge defects, in ten patients (6 male, 4 female), with bucco-palatal ridge width less than 5 mm were included in this study. Localised ridge augmentation was performed using bone lamina technique with mineralised allogenic shell of 1 mm thickness trimmed to the appropriate size using stereo-lithographic models and fixed to the recipient site with stainless steel micro-screws of 1 mm diameter. The space between the shell & host bone was filled with particulate xenograft followed by placement of collagen membrane and primary closure of the site. Clinical parameters including ridge width before & after flap reflection & radiographic (CBCT) ridge width measurements were recorded pre-operatively,and six months after the augmentation procedure. Results obtained were analysed statistically. Results The mean clinical ridge width before flap reflection (BFR), after flap reflection (AFR) & radiographically was 3.7 ± 0.74 mm, 2 ± 0.70 mm & 1.77 ± 0.71 mm respectively at baseline which increased to 6.8 ± 0.95 mm, 5.15 ± 0.98 mm & 4.90 ± 0.90 mm with a mean gain in ridge width of 3.1 ± 0.63 mm (p< 0.005), 3.15 ± 0.63 mm (p<0.005) & 3.13 ± 0.70 mm (p< 0.005) respectively. Conclusions The present study demonstrates that bone lamina technique can be effective means of horizontal ridge augmentation and the use of mineralized allograft in combination with xenograft and collagen membrane leads to good amount of bone regeneration for subsequent implant placement. Key words:Dental implant, guided bone regeneration, horizontal ridge defect, ridge augmentation. PMID:28149458

  6. Comparison Between Gearshift And Drill Techniques For Pedicle Screw Placement By Resident Surgeons

    PubMed Central

    Allen, Jonathan; Akpolat, Yusuf T.; Kishan, Shyam; Peppers, Tim; Asgarzadie, Farbod

    2015-01-01

    Background Various techniques have been described for pedicle screw placement with established clinical and radiological success. Suboptimal screw trajectories can compromise bony purchase and, worse yet, cause neurological and vascular injuries. Thus, it is of paramount importance to achieve maximum accuracy of screw placement. Our objective is to evaluate the accuracy of pedicle screw placement in the thoracolumbar spine by resident surgeons. Two popular techniques, gearshift versus drill, were compared. Methods This is a a cadaveric surgical technique comparison study. Six resident surgeons instrumented the spine from T1 to S1 using both gearshift and drill techniques. Each pedicle was randomly assigned to either of the techniques. Pedicle screws were placed freehand without radiographic guidance. Violations (medial, lateral, anterior, superior and inferior) were recorded by studying the computerized tomographic scans of instrumented cadavers by blinded observers. Critical perforations were defined as greater than 2mm breach of the pedicle wall. Results A total of 100 vertebrae (200 pedicles) were instrumented in the six cadavers. 103 pedicles were breached (51.5% of total pedicles). Lateral violations were the most encountered (65% of violations, 67 total, 48 critical, 19 noncritical) followed by medial (24%, 25 total, 13 critical, 12 noncritical), and the rest were anterior (3%), superior (4%) and inferior (4%). There was no overall difference in violations comparing the gearshift technique (49.5%, 51 total, 37 critical, 14 noncritical) with drill technique (50.5%, 52 total, 33 critical, 19 noncritical). Analyzing the breaches at individual vertebra indicated most violations at T6 (11), T5 (10), followed by T3 (9) and T4 (9), decreasing towards the lumbosacral vertebrae. Conclusion The results of this study suggest that the gearshift and drill techniques for placement of pedicle screws in the thoracolumbar spine fare similarly with regards to risk of breach

  7. Biomechanical Comparison of All-Suture Anchor Fixation and Interference Screw Technique for Subpectoral Biceps Tenodesis.

    PubMed

    Chiang, Florence L; Hong, Chih-Kai; Chang, Chih-Hsun; Lin, Cheng-Li; Jou, I-Ming; Su, Wei-Ren

    2016-07-01

    To compare the biomechanical characteristics of the subpectoral Y-knot all-suture anchor fixation with those of the interference screw technique. Sixteen fresh-frozen human cadaveric shoulders with a mean age of 67.6 ± 5.8 years (range, 52 to 74 years) were studied. The specimens were randomly grouped into 2 experimental biceps tenodesis groups (n = 8): Y-knot all-suture anchor or interference screw. The specimens were cyclically tested to failure by applying tensile forces parallel to the longitudinal axis of the humerus. A preload of 5 N was applied for 2 minutes prior to cyclic loading for 500 cycles from 5 to 70 N at 1 Hz; subsequently, a load-to-failure test at 1 mm/s was performed. The ultimate failure load, stiffness, displacement at cyclic and failure loading, and mode of failure were recorded. The all-suture anchor technique displayed values of ultimate failure load and stiffness comparable to that of the interference screw technique. The displacement at cyclic and failure loading of the all-suture anchor trials were significantly greater than the interference screw (P = .0002). The all-suture anchor specimens experienced anchor pullout and tendon tear equally during the trials, whereas the interference screw group experienced tendon tear in most of the cases and screw pullout in 2 trials. The Y-knot all-suture anchor fixation provides equivalent ultimate failure load and stiffness when compared with the interference screw technique in tenodesis of the proximal biceps tendon from a subpectoral approach. However, the interference screw technique demonstrates significantly less displacement in response to cyclic and failure loading. The all-suture anchor fixation is an alternative technique for subpectoral biceps tenodesis even at greater displacement when compared with the interference screw fixation during cyclic and failure loading. Copyright © 2016 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.

  8. Vertical bone augmentation procedures: basics and techniques in dental implantology.

    PubMed

    Draenert, F G; Huetzen, D; Neff, A; Mueller, W E G

    2014-05-01

    An appropriate bony situation is essential for dental implant placement and bony support of soft tissues (pink esthetic). Loss of teeth often results in complex horizontal and vertical alveolar ridge defects. They demand advanced bone augmentation techniques for reconstruction. We present the different techniques and materials used in complex bone augmentation. Clinical cases show the application of the methods in the clinical setting. We present current techniques and materials used in complex bone augmentations. Clinical cases show the application of the methods in the clinical setting. Applied techniques include stabilized-guided bone regeneration (GBR), autologous local block augmentation, modified techniques such as Gellrich shell technique including piezosurgery, pelvic bone blocks, complex materials such as graft-derived bone blocks and their unique handling problems. Successful basic principles are reduction of cortical bone healing due to long remodeling time and possible late loss; extended application of materials with interconnecting porous system and particulate material resulting in fast healing analogous to cancellous bone; mechanical stabilization of the augmentation to allow bony healing in vertical defect situations. GBR and autologous bone blocks with minimal cortical thickness and a high volume of particulated material are most favorable techniques.

  9. Comparison of pelvic fixation techniques in neuromuscular spinal deformity correction: Galveston rod versus iliac and lumbosacral screws.

    PubMed

    Peelle, Michael W; Lenke, Lawrence G; Bridwell, Keith H; Sides, Brenda

    2006-09-15

    Retrospective radiographic and clinical review. To evaluate the safety and efficacy of iliac screws as a method of pelvic fixation in neuromuscular spinal deformity correction using the Galveston rod technique as a comparison group. Sacropelvic fixation in patients with neuromuscular spinal deformity has traditionally used Galveston rods placed into the iliac wing. Difficulties with radiographic halos around the rods (loosening), rod contouring, and attaching to lumbar spine anchors have prompted their replacement with iliac screws. A minimum 2-year radiographic and clinical follow-up compared 20 patients with the Galveston technique to 20 patients with an iliac screw undergoing posterior spinal fusion (T2/T3-pelvis) for neuromuscular spinal deformity. All patients with the Galveston technique had sublaminar wires for their lumbar anchors, while the majority of patients with an iliac screw technique had at least 2 lumbar and/or sacral screws placed in addition to the iliac screws. There were no significant differences between the 2 groups in preoperative, postoperative, and latest follow-up (mean 3.1 years) measurements for coronal Cobb measures, coronal and sagittal C7 plumblines, and T1 offset. Pelvic obliquity was similar in both groups preoperatively (22 degrees) but at latest follow-up was statistically improved in the patients with an iliac screw (4.4 degrees) versus those with the Galveston technique (7.3 degrees) (P = 0.04). There were 13 patients with the Galveston technique versus 6 with an iliac screw who had radiolucent halos more than 2 mm around the pelvic anchor devices at latest follow-up (P < 0.05). The Galveston technique group had 4 broken rods and 2 reoperations, while the iliac screw group had 1 broken screw and no reoperations. Using iliac screws for pelvic fixation in neuromuscular spinal deformity affords equivalent maintenance of pelvic obliquity and scoliosis correction compared to the Galveston technique. Furthermore, the iliac screw

  10. Safety of thoracic pedicle screw application using the funnel technique in Asians: a cadaveric evaluation.

    PubMed

    Chan, Chris Yin Wei; Kwan, Mun Keong; Saw, Lim Beng

    2010-01-01

    The objective of this cadaveric study is to determine the safety and outcome of thoracic pedicle screw placement in Asians using the funnel technique. Pedicle screws have superior biomechanical as well as clinical data when compared to other methods of instrumentation. However, misplacement in the thoracic spine can result in major neurological implications. There is great variability of the thoracic pedicle morphometry between the Western and the Asian population. The feasibility of thoracic pedicle screw insertion in Asians has not been fully elucidated yet. A pre-insertion radiograph was performed and surgeons were blinded to the morphometry of the thoracic pedicles. 240 pedicle screws were inserted in ten Asian cadavers from T1 to T12 using the funnel technique. 5.0 mm screws were used from T1 to T6 while 6.0 mm screws were used from T7 to T12. Perforations were detected by direct visualization via a wide laminectomy. The narrowest pedicles are found between T3 and T6. T5 pedicle width is smallest measuring 4.1 +/- 1.3 mm. There were 24 (10.0%) Grade 1 perforations and only 1 (0.4%) Grade 2 perforation. Grade 2 or worse perforation is considered significant perforation which would threaten the neural structures. There were twice as many lateral and inferior perforations compared to medial perforations. 48.0% of the perforations occurred at T1, T2 and T3 pedicles. Pedicle fracture occurred in 10.4% of pedicles. Intra-operatively, the absence of funnel was found in 24.5% of pedicles. In conclusion, thoracic pedicle screws using 5.0 mm at T1-T6 and 6.0 mm at T7-T12 can be inserted safely in Asian cadavers using the funnel technique despite having smaller thoracic pedicle morphometry.

  11. Biomechanical comparison of intramedullary cortical button fixation and interference screw technique for subpectoral biceps tenodesis.

    PubMed

    Buchholz, Arne; Martetschläger, Frank; Siebenlist, Sebastian; Sandmann, Gunther H; Hapfelmeier, Alexander; Lenich, Andreas; Millett, Peter J; Stöckle, Ulrich; Elser, Florian

    2013-05-01

    The purpose of this study was to biomechanically evaluate a new technique of intramedullary cortical button fixation for subpectoral biceps tenodesis and to compare it with the interference screw technique. We compared intramedullary unicortical button fixation (BicepsButton; Arthrex, Naples, FL) with interference screw fixation (Bio-Tenodesis screw; Arthrex) for subpectoral biceps tenodesis using 10 pairs of human cadaveric shoulders and ovine superficial digital flexor tendons. After computed tomography analysis, the specimens were mounted in a testing machine. Cyclic loading was performed (preload, 5 N; 5 to 70 N at 1.5 Hz for 500 cycles), recording the displacement of the tendon. Load to failure and stiffness were subsequently evaluated with a load-to-failure test (1 mm/s). Cyclic loading showed a displacement of 11.3 ± 2.8 mm for intramedullary cortical button fixation and 9 ± 1.7 mm for interference screw fixation (P = .112). All specimens within the cortical button group passed the cyclic loading test, whereas 3 of 10 specimens within the interference screw group failed by tendon slippage at the screw-tendon-bone interface after a mean of 252 cycles (P = .221). Load-to-failure testing showed a mean load to failure of 218.8 ± 40 N and stiffness of 27.2 ± 7.2 N/mm for the intramedullary cortical button technique. For the interference screw, the mean load to failure was 212.1 ± 28.3 N (P = .625) and stiffness was 40.4 ± 13 N/mm (P = .056). We could not find any major differences in load to failure when comparing the tested techniques for subpectoral biceps tenodesis. Intramedullary cortical button fixation showed no failure during cyclic testing. However, we found a 30% failure rate (3 of 10) for the interference screw fixation. Intramedullary cortical button fixation provides an alternative technique for subpectoral biceps tenodesis with comparable and, during cyclic loading, even superior biomechanical properties to interference screw fixation

  12. Current trends in pedicle screw stimulation techniques: lumbosacral, thoracic, and cervical levels.

    PubMed

    Isley, Michael R; Zhang, Xiao-Feng; Balzer, Jeffrey R; Leppanen, Ronald E

    2012-06-01

    Unequivocally, pedicle screw instrumentation has evolved as a primary construct for the treatment of both common and complex spinal disorders. However an inevitable and potentially major complication associated with this type of surgery is misplacement of a pedicle screw(s) which may result in neural and vascular complications, as well as impair the biomechanical stability of the spinal instrumentation resulting in loss of fixation. In light of these potential surgical complications, critical reviews of outcome data for treatment of chronic, low-back pain using pedicle screw instrumentation concluded that "pedicle screw fixation improves radiographically demonstrated fusion rates;" however the expense and complication rates for such constructs are considerable in light of the clinical benefit (Resnick et al. 2005a). Currently, neuromonitoring using free-run and evoked (triggered) electromyography (EMG) is widely used and advocated for safer and more accurate placement of pedicle screws during open instrumentation procedures, and more recently, guiding percutaneous placement (minimally invasive) where the pedicle cannot be easily inspected visually. The latter technique, evoked or triggered EMG when applied to pedicle screw instrumentation surgeries, has been referred to as the pedicle screw stimulation technique. As concluded in the Position Statement by the American Society of Neurophysiological Monitoring (ASNM), multimodality neuromonitoring using free-run EMG and the pedicle screw stimulation technique was considered a practice option and not yet a standard of care (Leppanen 2005). Subsequently, the American Association of Neurological Surgeons/Congress of Neurological Surgeons (AANS/CNS) Joint Section on Disorders of the Spine and Peripheral Nerves published their "Guidelines for the Performance of Fusion Procedures for Degenerative Disease of the Lumbar Spine" (Heary 2005, Resnick et al. 2005a, Resnick et al. 2005b). It was concluded that the "primary

  13. Percutaneous Pedicle Screw Fixation Technique in the Thoracic and Lumbar Spine-Tips and Tricks.

    PubMed

    Gazzeri, Roberto

    2016-04-01

    The need for spinal fixation in patients who cannot tolerate classical open surgery has led in recent years to the development of minimally invasive approaches. The use of percutaneous pedicle screw fixation offers several advantages, such as less blood loss and postoperative pain due to blunt separation of the muscles with reduction of soft tissue dissection. Medical records and demographic information, diagnosis, and preoperative pain levels of 63 patients who underwent percutaneous minimally invasive thoracolumbar spine stabilization using the Illico® Fixation System (Alphatec Spine, Carlsbad, California) were analysed: a total of 344 screws were implanted. Preoperative and postoperative clinical assessment of the patients were based on a visual analogue scale. Because percutaneous techniques do not allow gross visualization of the vertebra and erroneous placement of the screw may be high in the initial cases, we discuss the techniques for a safe implantation of pedicle screws using a single or double intraoperative fluoroscopy. We report tips and tricks for technical challenges including fixation in osteoporotic patients, percutaneous insertion of long rods, compression/distraction using multiaxial screws turning into monoaxial, and use of minimally invasive retractror for interbody fusion. Recently, indications for minimally invasive percutaneous fixation have expanded and my results support that it may be considered a safe and effective option for the treatment of degenerative and traumatic thoracolumbar spinal diseases.

  14. Pullout strength of fixation screws from polymethylmethacrylate bone cement.

    PubMed

    Flahiff, C M; Gober, G A; Nicholas, R W

    1995-05-01

    Polymethylmethacrylate bone cement is often used to fill voids and increase the strength of osteoporotic and pathological bone. However, it is unclear as to which method of cement augmentation provides optimal screw fixation. This study was conducted to determine which of the current cement augmentation techniques provides the strongest construct when used in association with orthopaedic fixation screws. Pullout strength was determined for screws placed in sawbones with no cement, soft cement, doughy cement and hard cement after drilling and tapping. All cement-screw constructs were significantly stronger than the no cement group. Screws placed in doughy cement had a significantly higher pullout force than those placed in hard cement. Pullout strength of screws placed in soft cement was intermediate between the other cement techniques but not significantly different from either group.

  15. A novel technique for unstable Hangman's fracture: lag screw-rod (LSR) technique.

    PubMed

    Wang, Song; Wang, Qing; Yang, Han; Kang, Jianping; Wang, Gaoju; Song, Yueming

    2017-04-01

    The goal of the study was to describe the lag screw-rod (LSR) technique for the treatment of unstable Hangman's fracture as an attempt to pull C2 vertebral body back to posterior elements easily and immobilize C2 relative to C3 simultaneously. Twenty-one patients with unstable Hangman's fracture were treated with the LSR technique from January 2008 to October 2014. The clinical and radiological records were reviewed retrospectively. The angulation and displacement of C2 on C3 were evaluated. Complications, neck pain, neurological improvement, and fusion rate were assessed. The LSR technique was used for C2-C3 pedicle fixation and fusion in all the patients. The C2 vertebral body was pulled back to posterior elements successfully. The angulation and displacement of C2 on C3 were rectified obviously. No intra-operative or post-operative spinal cord or vertebral injury was observed. Visual analogue scale (VAS) scores for neck pain decreased gradually after operation. The patients with spinal cord injury were recovered at final following up. All patients achieved bony fusion without internal fixation failures. The LSR technique is an effective and reliable treatment for unstable Hangman's fractures. The technique has the advantages of pulling back the C2 vertebral body back to posterior elements easily and immobilizing C2 relative to C3 simultaneously.

  16. Miniarthrotomy assisted percutaneous screw fixation for displaced medial malleolus fractures – A novel technique

    PubMed Central

    Saini, Pramod; Aggrawal, Abhinav; Meena, Sanjay; Trikha, Vivek; Mittal, Samarth

    2014-01-01

    Aim To describe here a technique of miniarthrotomy assisted percutaneous screw insertion for displaced Herscovici type B and C medial malleolar fractures. Method Incision was made centred over the superomedial angle of the ankle mortise, about half a cm medial to tibialis anterior. Arthrotomy was done and reduction obtained. Percuntaneously, two 4 mm cancellous cannulated screws were inserted through medial malleolus. Results and conclusion This approach allows direct visualization of reduction, removal of entrapped soft tissue and preservation of saphenous vein and nerve. PMID:25983507

  17. The Effect of Polymethyl Methacrylate Augmentation on the Primary Stability of Cannulated Bone Screws in an Anterolateral Plate in Osteoporotic Vertebrae: A Human Cadaver Study

    PubMed Central

    Rüger, Matthias; Sellei, Richard M.; Stoffel, Marcus; von Rüden, Christian

    2015-01-01

    Study Design Cohort study. Objective Expandable anterolateral plates facilitate the reduction of posttraumatic deformities of thoracolumbar spine injuries and are commonly used in cases of unstable injuries or compromised bone quality. In this in vitro study, the craniocaudal yield load of the osseous fixation of an anterior angular stable plate fixation system and the effect of polymethyl methacrylate (PMMA) screw augmentation on the primary stability of the screw–bone interface during kyphosis reduction was evaluated in 12 osteoporotic human thoracolumbar vertebrae. Methods The anterolateral stabilization device used for this study is comprised of two swiveling flanges and an expandable midsection. It facilitates the controlled reduction of kyphotic deformities in situ with a geared distractor. Single flanges were attached to 12 thoracolumbar vertebrae. Six specimens were augmented with PMMA by means of cannulated bone screws. The constructs were subjected to static, displacement-controlled craniocaudal loading to failure in a servohydraulic testing machine. Results The uncemented screws cut out at a mean 393 ± 66 N, whereas the cemented screws showed significantly higher yield load of 966 ± 166 N (p < 0.02). We detected no significant correlation between bone mineral density and yield load in this setting. Conclusion Our results indicate that PMMA augmentation is an effective method to increase two- to threefold the primary stability of the screw–bone interface of an anterolateral spine stabilization system in osteoporotic bone. We recommend it in cases of severely compromised bone quality to reduce the risk of screw loosening during initial kyphosis correction and to increase long-term construct stability. PMID:26835201

  18. [Cement augmentation on the spine : Biomechanical considerations].

    PubMed

    Kolb, J P; Weiser, L; Kueny, R A; Huber, G; Rueger, J M; Lehmann, W

    2015-09-01

    Vertebral compression fractures are the most common osteoporotic fractures. Since the introduction of vertebroplasty and screw augmentation, the management of osteoporotic fractures has changed significantly. The biomechanical characteristics of the risk of adjacent fractures and novel treatment modalities for osteoporotic vertebral fractures, including pure cement augmentation by vertebroplasty, and cement augmentation of screws for posterior instrumentation, are explored. Eighteen human osteoporotic lumbar spines (L1-5) adjacent to vertebral bodies after vertebroplasty were tested in a servo-hydraulic machine. As augmentation compounds we used standard cement and a modified low-strength cement. Different anchoring pedicle screws were tested with and without cement augmentation in another cohort of human specimens with a simple pull-out test and a fatigue test that better reflects physiological conditions. Cement augmentation in the osteoporotic spine leads to greater biomechanical stability. However, change in vertebral stiffness resulted in alterations with the risk of adjacent fractures. By using a less firm cement compound, the risk of adjacent fractures is significantly reduced. Both screw augmentation techniques resulted in a significant increase in the withdrawal force compared with the group without cement. Augmentation using perforated screws showed the highest stability in the fatigue test. The augmentation of cement leads to a significant change in the biomechanical properties. Differences in the stability of adjacent vertebral bodies increase the risk of adjacent fractures, which could be mitigated by a modified cement compound with reduced strength. Screws that were specifically designed for cement application displayed greatest stability in the fatigue test.

  19. Pedicle screw placement in the thoracic spine: a comparison study of computer-assisted navigation and conventional techniques.

    PubMed

    Han, Wu; Gao, Zhong-li; Wang, Jin-cheng; Li, Ying-pu; Peng, Xia; Rui, Jiang; Jun, Wei

    2010-08-11

    The technique of computer-assisted pedicle screw installation and its clinical benefit as compared with conventional pedicle screw installation was evaluated. Twenty-two patients had thoracic screw insertion under 3-dimentional computer-assisted navigation (92 screws) and 20 patients under conventional fluoroscopic control (84 screws). The 2 groups were compared for accuracy of screw placement, screw insertion time by postoperative thin-cut computed tomography scans, and statistical analysis. The cortical perforations were graded by 2-mm increments. In the computer group, 88 (95.65%) were grade I (good), 4 (4.35%) were grade II (<2 mm), and 0 were grade III (>2 mm) violations. There were 4 cortical violations (3.57%). In the conventional group, there were 14 cortical violations (16.67%), 70 (83.33%) were grade I (good), 11 (13.1%) were grade II (<2 mm), and 3 (3.57%) were grade III (>2 mm) violations (P<.001). The number (19.57%) of upper thoracic pedicle screws (T1-T4) inserted under 3-dimensional computer-assisted navigation was significantly higher than that (3.57%) by conventional fluoroscopic control (P<.001). Average screw insertion time in the conventional group was more than in the computer group (P<.001). Three-dimensional computer-assisted navigation pedicle screw placement can increase accuracy, reduce surgical time, and be performed safely and effectively at all levels of the thoracic spine, particularly the upper thoracic spine.

  20. A retrospective comparison of first metatarsophalangeal joint arthrodesis using a locked plate and compression screw technique.

    PubMed

    Hyer, Christopher F; Scott, Ryan T; Swiatek, Michael

    2012-10-01

    The historic primary treatment for end-stage first metatarsophalangeal (MTP) joint arthritis has been fusion. Traditionally, this has been accomplished by metaphyseal apposition between the proximal phalanx and metatarsal using crossed compression screws. Recently, locked plates have been introduced that help support this technique by offering added stability. We present our experience with 45 first MTP fusions in 45 feet using a locked plate and compression screw. A retrospective review of 45 patients who met the study criteria with a hallux rigidus correction using a locked plate with a compression screw was performed. Charts and radiographs were independently reviewed by 2 authors not involved in the index procedures to assess outcomes. There was a 93% fusion rate (42/45 feet) with 3 nonunions. The mean time to union was 51.1 days (range = 29-116 days, SD = 24.4). The mean patient age was 58.1 years (range = 29-80 years, SD = 10.1). The mean time to partial weight bearing was 7.0 days (range = 0-53 days, SD = 13.8) and the mean time to full weight bearing was 62.0 days (range = 29-57 days, SD = 17.9). We report on the results of first MTP fusion using a compression screw and locked plate technique. The results show that this is an effective means of creating a first MTP joint arthrodesis.

  1. A technique of anterior screw removal through a posterior costotransversectomy approach for posterior-based osteotomies.

    PubMed

    Lewis, Stephen J; David, Kenny; Singer, Syndie; Bacon, Sarah A; Kopka, Michaela; Gray, Randolph; Magana, Sofia

    2010-05-15

    Case report. To describe a novel technique to remove anterior instrumentation from a posterior approach while performing posterior-based osteotomies for spinal deformities. Posterior-based osteotomies such as pedicle subtraction osteotomies (PSOs) and vertebral column resections are performed to restore sagittal alignment. The removal of previously placed anterior implants at the desired osteotomy level can often be challenging. We propose a technique for the removal of anterior instrumentation through a posterior approach to facilitate osteotomy closure and deformity correction, while avoiding the need for an anterior incision. A 34-year-old woman presented with a residual deformity after several anterior and posterior procedures. The residual coronal Cobb angle measured 60 degrees between T7 and L2, with a 46 degrees thoracolumbar kyphosis between T10 and L2. The screw head at the desired osteotomy level was in close proximity to the liver after the previous right-sided thoracoabdominal approach. Therefore, the T11 anterior screw was accessed through a posterior costotransversectomy approach and disconnected from the rod proximally and distally with a high-speed side-cutting burr. A portion of the right lateral vertebral body of T11 was removed to expose the neck of the screw, which was separated from the shaft with the same burr. A PSO was performed at T11 and the remaining screw shank was removed with the posterior-based osteotomy. No major complications were encountered during the procedure. The anterior screw at T11 was removed from posteriorly, and the PSO was completed successfully. Postoperative recovery was without incident, and the patient was very satisfied with her results. This technique describes a novel, safe, and effective method to deal with anterior instrumentation from the posterior approach while performing posterior-based osteotomies for rigid spinal deformities.

  2. Strategy for salvage pedicle screw placement: A technical note.

    PubMed

    Fujibayashi, Shunsuke; Takemoto, Mitsuru; Neo, Masashi; Matsuda, Shuichi

    2013-01-01

    Salvage surgery for failed lumbar spine fusion with a loosened pedicle screw is challenging. In general, the strategy includes replacement with larger and longer pedicle screws, augmentation with polymethylmethacrylate cement or hydroxyapatite granules, and extension of fused segments. The purpose of this study is to introduce a new technique for pedicle screw replacement after failed lumbar spine fusion. Five salvage operations were performed using a different trajectory (DT) pedicle screw replacement technique based on 3-dimensional radiological information. Position of the alternative pedicle screws was planned carefully on the computer screen of a computed tomography-based navigation system before the operation. To obtain sufficient initial stability, 1 of 2 techniques was chosen, depending on the patient. One technique created a completely new route, which did not interfere with the existing screw hole, and the other involved penetration of the existing screw hole. DT pedicle screws were replaced successfully according to the preoperative plan. In all patients, bony union were achieved at the final follow-up period without any instrument failure. Extension of the fused segments could be avoided by using the DT pedicle screw replacement technique combined with transforaminal lumbar interbody fusion. The DT pedicle screw replacement technique is a treatment option for salvage lumbar spine surgery. The current technique is a treatment option for salvage operations that can both avoid extension of a fused segment and achieve successful bony union.

  3. Double-Step Image Superimposition Technique for Fabricating a Drilling Guide to Access the Abutment Screw in Implant Prostheses.

    PubMed

    Mai, Hang-Nga; Kim, Kyung-Rok; Lee, Du-Hyeong

    2016-01-01

    Limited retrievability is a major disadvantage of cement-retained implant restorations. Despite great progress in locating the abutment screw within crowns, the existing techniques are based on prior data or prefabricated devices and require significant work. This study introduces a new procedure for fabricating a guide template to drill a screw access hole using a double-step superimposition technique that incorporates intraoral optical scanning, cone beam computed tomography, and dental design software. The double-step superimposition technique with computer-aided design/computer-assisted manufacturing technology can enhance the convenience and accuracy of drilling the screw-access hole.

  4. Learning curve of thoracic pedicle screw placement using the free-hand technique in scoliosis: how many screws needed for an apprentice?

    PubMed

    Gang, Chen; Haibo, Li; Fancai, Li; Weishan, Chen; Qixin, Chen

    2012-06-01

    The purpose of this study is to evaluate the learning curve of thoracic pedicle screw (TPS) placement of an inexperienced apprentice in scoliosis with the free-hand technique. The patients with scoliosis who underwent TPS inserted with the free-hand technique by the apprentice under the direction of a chief surgeon were included in this study. The TPS placement by the apprentice was evaluated by examining the assessed position in chronological subgroups of 30 screws. The TPS position was assessed on the postoperative computed tomography (CT) scan images using Zdichavsky grading evaluation system and pedicle breach. The rates of good and dangerous screw placement and the rates of pedicle breaches in each apprentice subgroup were compared with those in the chief surgeon group. Thirty-eight patients with 311 TPS were retrospectively analyzed in our study. Of all screws, 154 pedicle screws were inserted by the apprentice, and were divided chronologically into five subgroups. The rates of dangerous placement performed by the apprentice in the first two subgroups were 26.7 and 23.3%, respectively, and were significantly higher than 9.1% by the chief surgeon (P < 0.05). Meanwhile, the breach rate was 46.6% in subgroup 1 and 50.0% in subgroup 2, and was significantly higher than 29.3% in chief surgeon (P < 0.05). Furthermore, after the first 60 TPS placements, the assessed rates in apprentice reached to a stable level, and no significant difference could be found among the subgroups (subgroup 3, 4 and 5) and the chief surgeon group (P > 0.05). For an apprentice, an experience of at least 60 screw placements under the direction of an experienced surgeon is needed for inserting the TPS in scoliosis using the free-hand technique independently.

  5. Inertial Measurement Unit-Assisted Implantation of Thoracic, Lumbar, and Sacral Pedicle Screws Improves Precision of a Freehand Technique.

    PubMed

    Jost, Gregory F; Walti, Jonas; Mariani, Luigi; Schaeren, Stefan; Cattin, Philippe

    2017-07-01

    A method applying inertial measurement units (IMUs) was developed to implant pedicle screws in the thoracic and lumbosacral spine. This was compared with a freehand technique. The study was done on 9 human cadavers. For each cadaver, a preoperative computed tomography (CT) scan was performed to measure the axial and sagittal tilt angles of the screw trajectories from T1 to S1. After the entry points were defined on the exposed spine, the IMU-equipped pedicle finder and screwdriver were used to reproduce these tilt angles and implant half of the screws. The other half was implanted with a freehand technique. Fluoroscopy was not used. The screw trajectories were analyzed on postoperative CTs. A hundred and sixty-two screws were placed with use of the IMUs and 162 screws were implanted by freehand. The IMU-guided technique matched the planned trajectories significantly better than the freehand technique (axial tilt P < 0.001, sagittal tilt P < 0.001). With IMU assistance, the mean offsets between the planned and postoperatively measured tilt angles of the screws were 3.3 degrees ± 3.5 degrees for the axial plane (median 2 degrees, range 0-23 degrees) and 3.4 degrees ± 3 degrees for the sagittal plane (median 3 degrees, range 0-13 degrees). For the freehand technique, the mean offsets between the planned and postoperatively measured tilt angles of the screws were 5.6 degrees ± 4.5 degrees for the axial plane (median 5 degrees, range 0-31 degrees) and 6.7 degrees ± 5.4 degrees for the sagittal plane (median 6 degrees, range 0-33 degrees). IMU-assisted implantation of pedicle screws may enhance the performance of a freehand technique in the thoracic and lumbosacral spine. Copyright © 2017 Elsevier Inc. All rights reserved.

  6. Unilateral lag-screw technique for an isolated anterior 1/4 atlas fracture

    PubMed Central

    Keskil, Semih; Göksel, Murat; Yüksel, Ulaş

    2016-01-01

    Study Design: Fractures of the atlas are classified based on the fracture location and associated ligamentous injury. Among patients with atlas fractures treated using external immobilization, nonunion of the fracture could be seen. Objective: Ideally, treatment strategy for an unstable atlas fracture would involve limited fixation to maintain the fracture fragments in a reduced position without restricting the range of motion (ROM) of the atlantoaxial and atlantooccipital joints. Summary of Background Data: Such a result can be established using either transoral limited internal fixation or limited posterior lateral mass fixation. However, due to high infection risk and technical difficulty, posterior approaches are preferred but none of these techniques can fully address anterior 1/4 atlas fractures such as in this case. Materials and Methods: A novel open and direct technique in which a unilateral lag screw was placed to reduce and stabilize a progressively widening isolated right-sided anterior 1/4 single fracture of C1 that was initially treated with a rigid cervical collar is described. Results: Radiological studies made after the surgery showed no implant failure, good cervical alignment, and good reduction with fusion of C1. Conclusions: It is suggested that isolated C1 fractures can be surgically reduced and immobilized using a lateral compression screw to allow union and maintain both C1-0 and C1-2 motions, and in our knowledge this is the first description of the use of a lag screw to achieve reduction of distracted anterior 1/4 fracture fragments of the C1 from a posterior approach. This technique has the potential to become a valuable adjunct to the surgeon's armamentarium, in our opinion, only for fractures with distracted or comminuted fragments whose alignment would not be expected to significantly change with classical lateral mass screw reduction. PMID:27041886

  7. Evaluation of Reduction Accuracy of Suture-Button and Screw Fixation Techniques for Syndesmotic Injuries.

    PubMed

    Kocadal, Onur; Yucel, Mehmet; Pepe, Murad; Aksahin, Ertugrul; Aktekin, Cem Nuri

    2016-12-01

    Among the most important predictors of functional results of treatment of syndesmotic injuries is the accurate restoration of the syndesmotic space. The purpose of this study was to investigate the reduction performance of screw fixation and suture-button techniques using images obtained from computed tomography (CT) scans. Patients at or below 65 years who were treated with screw or suture-button fixation for syndesmotic injuries accompanying ankle fractures between January 2012 and March 2015 were retrospectively reviewed in our regional trauma unit. A total of 52 patients were included in the present study. Fixation was performed with syndesmotic screws in 26 patients and suture-button fixation in 26 patients. The patients were divided into 2 groups according to the fixation methods. Postoperative CT scans were used for radiologic evaluation. Four parameters (anteroposterior reduction, rotational reduction, the cross-sectional syndesmotic area, and the distal tibiofibular volumes) were taken into consideration for the radiologic assessment. Functional evaluation of patients was done using the American Orthopaedic Foot & Ankle Society (AOFAS) ankle-hindfoot scale at the final follow-up. The mean follow-up period was 16.7 ± 11.0 months, and the mean age was 44.1 ± 13.2. There was a statistically significant decrease in the degree of fibular rotation (P = .03) and an increase in the upper syndesmotic area (P = .006) compared with the contralateral limb in the screw fixation group. In the suture-button fixation group, there was a statistically significant increase in the lower syndesmotic area (P = .02) and distal tibiofibular volumes (P = .04) compared with the contralateral limbs. The mean AOFAS scores were 88.4 ± 9.2 and 86.1 ± 14.0 in the suture-button fixation and screw fixation group, respectively. There was no statistically significant difference in the functional ankle joint scores between the groups. Although the functional outcomes were similar, the

  8. A systematic review assessing soft tissue augmentation techniques.

    PubMed

    Thoma, Daniel S; Benić, Goran I; Zwahlen, Marcel; Hämmerle, Christoph H F; Jung, Ronald E

    2009-09-01

    The aim of the present review was to systematically assess the dental literature in terms of soft tissue grafting techniques. The focused question was: is one method superior over others for augmentation and stability of the augmented soft tissue in terms of increasing the width of keratinized tissue (part 1) and gain in soft tissue volume (part 2). A Medline search was performed for human studies focusing on augmentation of keratinized tissue and/or soft tissue volume, and complemented by additional hand searching. Relevant studies were identified and statistical results were reported for meta-analyses including the test minus control weighted mean differences with 95% confidence intervals, the I-squared statistic for tests of heterogeneity, and the number of significant studies. Twenty-five (part 1) and three (part 2) studies met the inclusion criteria; 14 studies (part 1) were eligible for comparison using meta-analyses. An apically positioned flap/vestibuloplasty (APF/V) procedure resulted in a statistically significantly greater gain in keratinized tissue than untreated controls. APF/V plus autogenous tissue revealed statistically significantly more attached gingiva compared with untreated controls and a borderline statistical significance compared with APF/V plus allogenic tissue. Statistically significantly more shrinkage was observed for the APF/V plus allogenic graft compared with the APF/V plus autogenous tissue. Patient-centered outcomes did not reveal any of the treatment methods to be superior regarding postoperative complications. The three studies reporting on soft tissue volume augmentation could not be compared due to lack of homogeneity. The use of subepithelial connective tissue grafts (SCTGs) resulted in statistically significantly more soft tissue volume gain compared with free gingival grafts (FGGs). APF/V is a successful treatment concept to increase the width of keratinized tissue or attached gingiva around teeth. The addition of autogenous

  9. [Placement of short iliac screw using Galveston technique in lumbosacral fusion].

    PubMed

    Min, Shao-xiong; Jin, An-min; Duan, Yang; Zhang, Li; Cheng, Yuan-ming

    2010-07-01

    To evaluate the effect of placement of short iliac screw using Galveston technique in lumbosacral fusion. From October 2003 to August 2007, 18 consecutive patients (mean age 46 years ranging from 25 to 62 years) received placement of short iliac screw in lumbosacral fusion. The patients were followed up for a mean of 18 months (12-23 months), and the effect of lumbosacral fusion was evaluated according to standing anterior-posterior and lateral plain films taken before and after the operation and at the follow-up and also on the basis of symptom relief. The mean time of surgery was 210 min (180-290 min). No complications occurred during and after the operation. According to the evaluation criteria of surgical treatment of low back pain formulated by the spine group of Chinese Orthopedic Association, excellent clinical outcome was achieved in 12 cases, good outcome in 3 cases, and tolerable outcome in 2 cases, with the excellent and good outcome rate of 83%. The Galveston technique for short iliac screw placement can obtain satisfactory outcome in the lumbosacral fusion.

  10. A comparative study of pedicle screw fixation in dorsolumbar spine by freehand versus image-assisted technique: A cadaveric study

    PubMed Central

    Agarwal, Archit; Chauhan, Vijendra; Singh, Deepa; Shailendra, Raghuvanshi; Maheshwari, Rajesh; Juyal, Anil

    2016-01-01

    Background: New and expensive technology such as three-dimensional computer assisted surgery is being used for pedicle screw fixation in dorsolumbar spine. Their availability, expenses and amount of radiation exposure are issues in a developing country. On the contrary, freehand technique of pedicle screw placement utilizes anatomic landmarks and tactile palpation without fluoroscopy or navigation to place pedicle screws. The purpose of this study was to analyze and compare the accuracy of freehand and image-assisted technique to place pedicle screws in the dorsolumbar spine of cadavers by an experienced surgeon and a resident. Evaluation was done using dissection of pedicle and computed tomography (CT) imaging. Materials and Methods: Ten cadaveric dorsolumbar spines were exposed by a posterior approach. Titanium pedicle screws were inserted from D5 to L5 vertebrae by freehand and image-assisted technique on either side by an experienced surgeon and a resident. CT was obtained. A blinded radiologist reviewed the imaging. The spines were then dissected to do a macroscopic examination. Screws, having evidence of cortical perforation of more than 2 mm on CT, were considered to be a significant breach. Results: A total of 260 pedicle screws were placed. The surgeon and the resident placed 130 screws each. Out of 130 screws, both of them placed 65 screws each by freehand and image- assisted technique each. The resident had a rate of 7.69% significant medial and 10.76% significant lateral breach with freehand technique while with image-assisted had a rate of 3.07% significant medial and 9.23% significant lateral breach. The expert surgeon had a rate of 6.15% significant medial and 1.53% significant lateral breach with freehand technique while with image-assisted had a rate of 3.07% significant medial and 6.15% significant lateral breach on CT evaluation. Conclusion: Freehand technique is as good as the image-assisted technique. Under appropriate supervision, residents

  11. Suprapectoral biceps tenodesis: a biomechanical comparison of a new "soft anchor" tenodesis technique versus interference screw biceps tendon fixation.

    PubMed

    Baleani, Massimiliano; Francesconi, Dunia; Zani, Lorenzo; Giannini, Sandro; Snyder, Stephen J

    2015-02-01

    The interference screw technique is commonly used in tenodesis of the long head of the biceps for its well-documented robust fixation strength. Some complications may occur after tenodesis with interference screw such as persistent pain, bone fracture and cyst formation. A new technique using a small "soft anchor" has been proposed to avoid the risk of occurrence of the above-mentioned complications associated with the use of the interference screw. However, the proposed technique must provide adequate fixation strength. This study investigated the mechanical performance of the new technique and compared it with interference screw fixation. Fourteen human humeri and proximal biceps were tested after tenodesis using the two techniques. The fixation constructs were cycled 500 times between 20N and 100N at 1Hz to simulate some level of post-operative physical activity. Then, a tensile test to failure was performed to determine the strength of the two tenodesis constructs. The ultimate strength was 238N (SD 96N) and 172N (SD 58N) for the "soft anchor" and the interference screw, respectively (P=0.14). In two out of seven repetitions in both groups, failure occurred at low load level due to inaccuracies in performing tenodesis. Considering these cases as outliers, the strength values increased up to 290N (SD 40N) and 202N (SD 32N) for the "soft anchor" and the interference screw, respectively (P=0.02). The "soft anchor" technique provides a fixation strength comparable with the interference screw, but without using a screw. It could be considered as an alternative for suprapectoral biceps tenodesis. Copyright © 2014 Elsevier Ltd. All rights reserved.

  12. The Use of MMF Screws: Surgical Technique, Indications, Contraindications, and Common Problems in Review of the Literature

    PubMed Central

    Cornelius, Carl-Peter; Ehrenfeld, Michael

    2010-01-01

    Mandibulo-maxillary fixation (MMF) screws are inserted into the bony base of both jaws in the process of fracture realignment and immobilisation. The screw heads act as anchor points to fasten wire loops or rubber bands connecting the mandible to the maxilla. Traditional interdental chain-linked wiring or arch bar techniques provide the anchorage by attached cleats, hooks, or eyelets. In comparison to these tooth-borne appliances MMF screws facilitate and shorten the way to achieve intermaxillary fixation considerably. In addition, MMF screws help to reduce the hazards of glove perforation and wire stick injuries. On the downside, MMF screws are attributed with the risk of tooth root damage and a lack of versatility beyond the pure maintenance of occlusion such as stabilizing loose teeth or splinting fragments of the alveolar process. The surgical technique of MMF screws as well as the pros and cons of the clinical application are reviewed. The adequate screw placement to prevent serious tooth root injuries is still an issue to rethink and modify conceptual guidelines. PMID:22110819

  13. The Use of MMF Screws: Surgical Technique, Indications, Contraindications, and Common Problems in Review of the Literature.

    PubMed

    Cornelius, Carl-Peter; Ehrenfeld, Michael

    2010-06-01

    Mandibulo-maxillary fixation (MMF) screws are inserted into the bony base of both jaws in the process of fracture realignment and immobilisation. The screw heads act as anchor points to fasten wire loops or rubber bands connecting the mandible to the maxilla. Traditional interdental chain-linked wiring or arch bar techniques provide the anchorage by attached cleats, hooks, or eyelets. In comparison to these tooth-borne appliances MMF screws facilitate and shorten the way to achieve intermaxillary fixation considerably. In addition, MMF screws help to reduce the hazards of glove perforation and wire stick injuries. On the downside, MMF screws are attributed with the risk of tooth root damage and a lack of versatility beyond the pure maintenance of occlusion such as stabilizing loose teeth or splinting fragments of the alveolar process. The surgical technique of MMF screws as well as the pros and cons of the clinical application are reviewed. The adequate screw placement to prevent serious tooth root injuries is still an issue to rethink and modify conceptual guidelines.

  14. Compressive Force With 2-Screw and 3-Screw Subtalar Joint Arthrodesis With Headless Compression Screws.

    PubMed

    Matsumoto, Takumi; Glisson, Richard R; Reidl, Markus; Easley, Mark E

    2016-12-01

    Joint compression is an essential element of successful arthrodesis. Although subtalar joint compression generated by conventional screws has been quantified in the laboratory, compression obtainable with headless screws that rely on variable thread pitch to achieve bony contact has not been assessed. This study measured subtalar joint compression achieved by 2 posteriorly placed contemporary headless, variable-pitch screws, and quantified additional compression gained by placing a third screw anteriorly. Ten, unpaired fresh-frozen cadaveric subtalar joints were fixed sequentially using 2 diverging posterior screws (one directed into the talar dome, the other into the talar neck), 2 parallel posterior screws (both ending in the talar dome), and 2 parallel screws with an additional anterior screw inserted from the plantar calcaneus into the talar neck. Joint compression was quantified directly during screw insertion using a novel custom-built measuring device. The mean compression generated by 2 diverging posterior screws was 246 N. Two parallel posterior screws produced 294 N of compression, and augmentation of that construct with a third, anterior screw increased compression to 345 N (P < .05). Compression subsequent to 2-screw fixation was slightly less than that reported previously for subtalar joint fixation with 2 conventional lag screws, but was comparable when a third screw was added. Under controlled testing conditions, 2 tapered, variable-pitch screws generated somewhat less compression than previously reported for 2-screw fixation with conventional headed screws. A third screw placed anteriorly increased compression significantly. Because headless screws are advantageous where prominent screw heads are problematic, such as the load-bearing surface of the foot, their effectiveness compared to other screws should be established to provide an objective basis for screw selection. Augmenting fixation with an anterior screw may be desirable when conditions for

  15. Augmented PMMA distribution: improvement of mechanical property and reduction of leakage rate of a fenestrated pedicle screw with diameter-tapered perforations.

    PubMed

    Tan, Quan-Chang; Wu, Jian-Wei; Peng, Fei; Zang, Yuan; Li, Yang; Zhao, Xiong; Lei, Wei; Wu, Zi-Xiang

    2016-06-01

    OBJECTIVE This study investigated the optimum injection volume of polymethylmethacrylate (PMMA) to augment a novel fenestrated pedicle screw (FPS) with diameter-tapered perforations in the osteoporotic vertebral body, and how the distribution characteristics of PMMA affect the biomechanical performance of this screw. METHODS Two types of FPSs were designed (FPS-A, composed of 6 perforations with an equal diameter of 1.2 mm; and FPS-B, composed of 6 perforations each with a tapered diameter of 1.5 mm, 1.2 mm, and 0.9 mm from tip to head. Each of 28 human cadaveric osteoporotic vertebrae were randomly assigned to 1 of 7 groups: FPS-A1.0: FPS-A+1.0 ml PMMA; FPS-A1.5: FPS-A+1.5 ml PMMA; FPS-A2.0: FPS-A+2.0 ml PMMA; FPS-B1.0: FPS-B+1.0 ml PMMA; FPS-B1.5: FPS-B+1.5 ml PMMA; FPS-B2.0: FPS-B+2.0 ml PMMA; and conventional pedicle screws (CPSs) without PMMA. After the augmentation, 3D CT was performed to assess the cement distribution characteristics and the cement leakage rate. Axial pullout tests were performed to compare the maximum pullout force thereafter. RESULTS The CT construction images showed that PMMA bone cement formed a conical mass around FPS-A and a cylindrical mass around FPS-B. When the injection volume was increased from 1.0 ml to 2.0 ml, the distribution region of the PMMA cement was enlarged, the PMMA was distributed more posteriorly, and the risk of leakage was increased. When the injection volume reached 2.0 ml, the risk of cement leakage was lower for screws having diameter-tapered perforations. The pullout strengths of the augmented FPS-A groups and FPS-B groups were higher than that of the CPS group (p < 0.0001). All FPS-B groups had a higher pullout strength than the FPS-A groups. CONCLUSIONS The diameter of the perforations affects the distribution of PMMA cement. The diameter-tapered design enabled PMMA to form larger bone-PMMA interfaces and achieve a relatively higher pullout strength, although statistical significance was not reached. Study

  16. The application of rapid prototyping technique in chin augmentation.

    PubMed

    Li, Min; Lin, Xin; Xu, Yongchen

    2010-04-01

    This article discusses the application of computer-aided design and rapid prototyping techniques in prosthetic chin augmentation for mild microgenia. Nine cases of mild microgenia underwent an electrobeam computer tomography scan. Then we performed three-dimensional reconstruction and operative design using computer software. According to the design, we determined the shape and size of the prostheses and made an individualized prosthesis for each chin augmentation with the rapid prototyping technique. With the application of computer-aided design and a rapid prototyping technique, we could determine the shape, size, and embedding location accurately. Prefabricating the individual prosthesis model is useful in improving the accuracy of treatment. In the nine cases of mild microgenia, three received a silicone implant, four received an ePTFE implant, and two received a Medpor implant. All patients were satisfied with the results. During follow-up at 6-12 months, all patients remained satisfied. The application of computer-aided design and rapid prototyping techniques can offer surgeons the ability to design an individualized ideal prosthesis for each patient.

  17. Posterior approach for medial column beam screw in midfoot Charcot reconstruction: technique and structures at risk.

    PubMed

    Peterson, Kyle S; Hyer, Christopher F

    2015-01-01

    Charcot neuroarthropathy is frequently recognized as a major cause of morbidity in patients with neuropathic diabetes mellitus. Recently, intramedullary beam screw fixation has been used for midfoot Charcot reconstructions. Ten below-the-knee cadaveric specimens were used to demonstrate an antegrade, posterior approach for placement of a medial column beam screw, with specific attention to the proximity of the anatomic structures at risk. Six structures at risk were identified, including the sural nerve, ankle joint, flexor hallucis longus tendon, Achilles tendon, neurovascular bundle, and peroneal tendon sheath. The sural nerve was the most commonly injured structure, injured in 50% of the limbs. The Achilles and flexor hallucis longus tendons were injured in 20% and the ankle joint in 10% of the limbs. The neurovascular bundle and peroneal tendon sheath were located over 1 cm from the reference guidewire and were considered safe structures in this approach. Our results have demonstrated an alternative posterior approach to the delivery of an intramedullary medial column beam screw, instead of a retrograde technique beginning in the metatarsal heads. Our results have also made clear the need to be aware of the potential for damage to the sural nerve, Achilles tendon, flexor hallucis longus tendon, and ankle joint. Copyright © 2015 American College of Foot and Ankle Surgeons. Published by Elsevier Inc. All rights reserved.

  18. New Technique for C1 Double-Door Laminoplasty Using Allograft Spacers and Titanium Miniplate Screw Fixation: Technical Report.

    PubMed

    Kim, Seok Woo; Lee, Jae-Hoo; Lee, Ho-Won; Oh, Jae-Keun; Kwak, Yoon-Hae

    2016-03-01

    Although conventional C1 laminectomy is the gold standard for decompression at the atlas, it provides little space for the bone graft to fuse. The fusion area can be extended cranially up to the occipital bone, but it requires sacrificing the function of the craniocervical junction. To date, no reports have focused on surgical techniques for successful decompression and fusion without disruption of the posterior C1 arch while providing enough room for the bone graft to fuse. This study introduces a new technique for C1-C2 fusion and C1 double-door laminoplasty in patients with C1-C2 instability, canal stenosis, and cervical spondylotic myelopathy. A 66-year-old man who had undergone C1-C2 fusion at a local clinic 2 years earlier visited our hospital due to progressive myelopathy. A preoperative computed tomography (CT) scan showed the tip of the odontoid process, extending into the spinal canal. On the axial view of T2-weighted magnetic resonance images, the tip of the odontoid process significantly compressed the spinal cord on the left side. The atlantodental interval was 7 mm on radiography; however, C1-C2 instability was not evident on flexion-extension X-rays due to the previous screw fixation. The patient underwent C1-C2 decompression and fusion surgery with our new surgical technique. The segmental screws were repositioned at C1 and C2, and we performed C1 double-door laminoplasty augmented with an allograft spacer and a titanium miniplate. A marked reduction was seen at postoperative radiograph and CT scan. Neurologic symptoms were relieved dramatically after surgery without any discomfort. No complications were noted. We introduced a new surgical technique that allows bone grafting, decompression, and fusion to be performed without disruption of the posterior C1 arch in the event of C1-C2 canal stenosis combined with instability. This technique may be indicated for other conditions that cause instability and stenosis at the C1-C2 area. Georg Thieme

  19. Dual Surgical Navigation Using Augmented and Virtual Environment Techniques

    NASA Astrophysics Data System (ADS)

    Kim, Sungmin; Hong, Jaesung; Joung, Sanghyun; Yamada, Atsushi; Matsumoto, Nozomu; Kim, Sun I.; Kim, Young Soo; Hashizume, Makoto

    2011-04-01

    To obtain additional depth and visual information in endoscopic surgery, a dual surgical navigation system using virtual reality (VR) and augmented reality (AR) techniques complementarily was developed. A VR environment was constructed in the default 3-D view of the navigation software and an AR environment was developed as a plug-in module. The spatial relationships among the target organ, endoscope, and surgical tools were visualized, and the visual information superimposing invisible organs on the endoscopic images was supplied using the AR environment. Phantom experiments and preliminary clinical application showed promising results for surgical navigation.

  20. Biomechanical comparison of long head of biceps tenodesis with interference screw and biceps sling soft tissue techniques.

    PubMed

    Ahmed, Mohammed; Young, Brian T; Bledsoe, Gary; Cutuk, Adnan; Kaar, Scott G

    2013-07-01

    The purpose of our study was to compare biomechanically a long head biceps tenodesis using an all soft tissue biceps sling technique versus an interference screw technique. Six paired fresh frozen shoulder specimens were separated into 2 groups. One group used an all soft tissue biceps sling technique for tenodesis. The other group used the interference screw technique for subpectoral tenodesis of the long head biceps tendon. Specimens in both groups were sequentially loaded for 200 cycles, and the difference between the initial and final displacements were recorded. Specimens were then loaded to failure. Load and mode of failure were recorded. The mean displacement of all specimens undergoing the sling technique was significantly less than that of the interference technique at 3.0 mm (±0.80) versus 5.0 mm (±1.08) (P < .05). The biceps sling technique had a higher mean ultimate failure load (UFL) than did the interference screw tenodesis (216.9 N ± 91.6 v 171.7 N ± 101.4), although this was not statistically significant (P = .63). In the interference screw technique, 4 specimens failed at the tenodesis site by either tearing or complete pullout, whereas 2 failed at the biceps myotendinous junction. In the sling technique, 4 specimens failed at the biceps myotendinous junction, whereas one specimen tore at the tenodesis site and one detached the pectoralis tendon insertion from the humerus. One specimen in the biceps sling technique and 2 specimens in the interference screw technique failed before completing all 200 cycles. The results of this biomechanical study show that the biceps sling technique has construct stability similar to that of the interference screw technique. The biceps sling may be a reasonable alternative for treating symptomatic pathologic conditions of the long head biceps tendon. Copyright © 2013 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.

  1. Lateral Ridge Augmentation with Autogenous Bone Harvested Using Trephine Drills: A Noninvasive Technique

    PubMed Central

    Arab, H. R.; Moeintaghavi, A.; Taheri, M.; Sargolzaie, N.; Aghasizadeh, D.; Shiezadeh, F.

    2016-01-01

    Purpose: The aim of this pilot study was to evaluate the success rate of a chairside ridge augmentation procedure using bone autografts harvested with trephine drills and placed without the use of screws. Methods: Thirty patients were recruited for the study. After the surgical site was anesthetized and a crestal incision was made, an envelope flap was retracted using blunt dissection limited to the graft site, and the periosteum was raised intact and undamaged from the bone. The flap was extended laterally to obtain sufficient space for the bone graft. At the donor site, bone was obtained from the external oblique ridge area. A #5 or #6 trephine drill was used to harvest one or two pieces of bone. The bone blocks were placed inside the envelope flap at the recipient site, which was then sutured and covered with periodontal dressing. Antibiotics, analgesics, and mouthwash were prescribed. Measurements of ridge width were performed using CBCT before and 3 months after surgery. The pre- and post operative results were compared using paired t test. Results: Pre- and post-operative mean ridge widths were 2.23 ± 0.79 and 5.16 ± 0.68 mm, respectively. The mean increase in width was 2.92 ± 0.89 mm(P < 0.001). Conclusion: This non-invasive and simple technique provided an acceptable increase in ridge width. As the sample was small, we recommend further clinical investigation with larger samples to confirm that this technique may be used successfully as an alternative to current invasive augmentation methods. PMID:27006718

  2. Comparison of pullout strength of the thoracic pedicle screw between intrapedicular and extrapedicular technique: a meta-analysis and literature review.

    PubMed

    Wang, Hua; Wang, Huafeng; Sribastav, Shilabant Sen; Ye, Fubiao; Liang, Chunxiang; Li, Zemin; Wang, Jianru; Liu, Hui; Wang, Xin; Zheng, Zhaomin

    2015-01-01

    Intrapedicular fixation in thoracic spine is often limited, because of high risk of complication, especially in scoliosis patients. Extrapedicular screws fixation techniques provide an alternate solution for extremely small or abnormal thoracic pedicles deformity. However, the pullout resistance of extrapedicular screws has not been clearly defined. The aim of our study was to systematically review the existing evidence regarding the pullout resistance of thoracic extrapedicular screws compared with intrapedicular screws. A systematic search of all studies published through Nov 2014 was performed using Medline, EMBASE, OVID and other databases. All studies that compared the pullout resistance of thoracic extrapedicular screws with intrapedicular screws were selected. The data from the included studies were extracted and analyzed regarding pullout resistance force. Forest plots were constructed to summarize the data and compare the biomechanical stability achieved. Five studies were included, with a total of 27 cadaveric specimens and 313 screws. The vertebral levels of the cadavers potted were T1-T8, T2-T12, T7-T9, T6-T11 and T4-T12 respectively. Overall, the results demonstrated that there was no significant difference in ultimate pullout strength between intrapedicular screws and extrapedicular screws (95% CI=-63.73 to 27.74; P=0.44); extrapedicular screws significantly increased the length of placements by a mean of 6.24 mm (95% CI=5.38 to 7.10; P<0.001); while the stiffness in intrapedicular screws was significantly stronger by a mean of 45.82 N/mm compared with extrapedicular screws (95% CI=-70.09 to -21.56; P<0.001). Meta-analysis of the existing literature showed that thoracic extrapedicular screws provided comparable but slightly lower pullout strength compared with intrapedicular screws, extrapedicular screws placement is much safer than intrapedicular screws. So thoracic extrapedicular screws offer a good alternative when it is hard to insert by

  3. Clear Zone Formation around Screws in the Early Postoperative Stages after Posterior Lumbar Fusion Using the Cortical Bone Trajectory Technique

    PubMed Central

    Iwatsuki, Koichi; Ohnishi, Yu-Ichiro; Ohkawa, Toshika; Yoshimine, Toshiki

    2015-01-01

    Study Design Retrospective study. Purpose To evaluate the initial fixation using the cortical bone trajectory (CBT) technique for posterior lumbar fusion through assessment of the clear zones around the screws and the risk factors involved. Overview of Literature Postoperative radiolucent zones (clear zones) are an indicator of poor conventional pedicle screw fixation. Methods Between January 2013 and April 2014, 19 patients (8 men and 11 women) underwent posterior lumbar interbody fusion or posterior lumbar fusion using the CBT technique. A total of 109 screws were used for evaluation with measurement of the maximum insertional torque of last two screw rotations. Clear zone-positivity on plain radiographs was investigated 6 months after surgery. The relation between intraoperative insertional torque and clear zone-positivity was investigated by one-way analysis of variance. In addition, the correlation between clear zone-positivity and gender, age (<75 years old or >75 years old), or operative stabilization level (<2 or >3 vertebral levels) was evaluated using the chi-square test. Results Clear zones were observed around six screws (5.50%) in five patients (26.3%). The mean insertional torque (4.00±2.09 inlbs) of clear zone-positive screws was lower than that of clear zone-negative screws (8.12±0.50 in-lbs), but the difference was not significant. There was a significant correlation between clear zone-positivity and operative level of stabilization. Conclusions The low incidence of clear zone-positive screws indicates good initial fixation using the CBT technique. Multilevel fusions may be risk factors for clear zone generation. PMID:26713120

  4. [More than 10 years of follow up of the stop screw technique].

    PubMed

    Calvo Calvo, S; Marti Ciruelos, R; Rasero Ponferrada, M; González de Orbe, G; Viña Fernández, R

    2016-01-01

    Infantile flexible flatfoot does not require treatment in most cases. Symptomatic flexible flat feet are treated orthopaedically and surgery is only indicated when orthosis fails. Cases who underwent surgical treatment with the stop screw technique at the 12 de Octubre Hospital between 1995 and 2002 are reported. Patient progress is also analysed. Six angles are measured on the x-ray prior to surgery and those same x-ray angles are measured again before material extraction. They are then compared to see if the correction achieved is statistically significant. A more reduced sample is currently being assessed with the same radiological measurements and two clinical assessment scales: Lickert, and Smith and Millar. The latest x-rays are analysed by two radiologists to determine if there is subtalar arthrosis. In the short term, statistically significant differences are observed in all angles. The comparison between the post-surgery angles and the current angles does not show differences, except for the Giannestras angle, which has statistically significantly worsened. Clinical results and patient satisfaction is good. Incipient subtalar arthrosis is present in 68.5% of current patient x-rays. Stop screw method is a cheap, simple and effective technique to correct symptomatic flexible flatfoot that has not improved with conservative treatment. This technique provides short-term foot correction which can be maintained over time. Copyright © 2015 SECOT. Published by Elsevier Espana. All rights reserved.

  5. Traditional Versus Congruent Arc Latarjet Technique: Effect on Surface Area for Union and Bone Width Surrounding Screws.

    PubMed

    Dumont, Guillaume D; Vopat, Bryan G; Parada, Stephen; Cohn, Randy; Makani, Amun; Sanchez, George; Golijanin, Petar; Beaulieu-Jones, Brendin R; Sanchez, Anthony; Provencher, Matthew T

    2017-05-01

    To compare the surface area available for bony contact and the width of bone on each side of the Latarjet fixation screws in the traditional Latarjet technique versus the congruent arc modification of the Latarjet technique. Computed tomographic scans of 24 shoulders in patients with glenohumeral instability who underwent multiplanar reconstruction measurements with multiple dimensions of the coracoid. The surface area of the coracoid available for bony contact with the anterior glenoid and width of bone on each side of a 3.5-mm screw was compared for the traditional Latarjet technique versus the congruent arc modification. The surface area available for bony contact to the anterior glenoid was 5.65 ± 1.08 cm(2) using the traditional Latarjet technique compared with 3.64 ± 0.93 cm(2) using the congruent arc modification of the Latarjet technique (P < .001). The mean width of bone on each side of a 3.5-mm screw was 7.1 ± 1.0 mm using the traditional Latarjet technique compared with 4.1 ± 1.0 mm using the congruent arc modification (P < .001). The traditional Latarjet technique has greater bony contact with the glenoid and greater bone width on each side of the screws compared with the congruent arc modification of the Latarjet technique. This potentially allows for a larger surface for healing in the traditional Latarjet technique. Moreover, because of smaller width of the bone around the screw, the congruent arc modification is potentially less tolerant of screw-positioning error compared with the traditional Latarjet technique. Level III, retrospective comparative study. Copyright © 2016 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.

  6. Percutaneous Cannulated Compression Screw Osteosynthesis in Phalanx Fractures: The Surgical Technique, the Indications, and the Results

    PubMed Central

    Kisch, Tobias; Wenzel, Eike; Mailänder, Peter; Stang, Felix

    2017-01-01

    Objective: Fractures of metacarpals and phalanges are very common fractures, and there are a lot of treatment modalities. The purpose of the study was to describe the technique of percutaneous fixation of phalangeal fractures using a cannulated compression screw fixation system and its results. Methods: We conducted a prospective clinical study on 43 patients with different types of phalangeal fractures undergoing a percutaneous cannulated compression screw osteosynthesis. Parameters such as average operation time and clinical outcome were evaluated postoperatively. Results: Forty-three patients were treated using a percutaneous cannulated compression screw fixation system for phalanx fractures of the proximal (n = 26), middle phalanx (n = 16), or distal phalanx (n = 1). All fractures healed after 6 to 8 weeks except in 1 patient with secondary loss of reduction occurring 2.5 weeks after surgery. No infections were observed. The mean total active motion values were 247.56° ±16.16° and 244.35° ± 11.61° for the intra-articular fracture and 251.25° ± 19.86° for the shaft fractures; the mean Disabilities of the Arm, Shoulder, and Hand (DASH) score 3 months after the surgery was 1.67 ± 2.74. Conclusions: The advantages of this technique are the avoidance of an open procedure requiring extensive soft-tissue dissection with the risks of tendon adhesions and the achievement of interfragmentary compression. Because of the interfragmentary compression, it is superior to simple K-wires. With regard to indications, our primary focus was on unicondylar proximal interphalangeal joint fractures, shaft fractures, and simple oblique 2-fragment fractures. PMID:28293333

  7. Registration based on projective reconstruction technique for augmented reality systems.

    PubMed

    Yuan, M L; Ong, S K; Nee, A Y C

    2005-01-01

    In AR systems, registration is one of the most difficult problems currently limiting their application. In this paper, we propose a simple registration method using projective reconstruction. This method consists of two steps: embedding and tracking. Embedding involves specifying four points to build the world coordinate system on which a virtual object will be superimposed. In tracking, a projective reconstruction technique is used to track these four specified points to compute the model view transformation for augmentation. This method is simple, as only four points need to be specified at the embedding stage and the virtual object can then be easily augmented onto a real scene from a video sequence. In addition, it can be extended to a scenario using the projective matrix that has been obtained from previous registration results using the same AR system. The proposed method has three advantages: 1) It is fast because the linear least square method can be used to estimate the related matrix in the algorithm and it is not necessary to calculate the fundamental matrix in the extended case. 2) A virtual object can still be superimposed on a related area even if some parts of the specified area are occluded during the whole process. 3) This method is robust because it remains effective even when not all the reference points are detected during the whole process, as long as at least six pairs of related reference points correspondences can be found. Some experiments have been conducted to validate the performance of the proposed method.

  8. Arthroscopic Hip Labral Augmentation Technique With Iliotibial Band Graft.

    PubMed

    Locks, Renato; Chahla, Jorge; Frank, Jonathan M; Anavian, Jack; Godin, Jonathan A; Philippon, Marc J

    2017-04-01

    The importance of the acetabular labrum has been well documented for the function and overall health of the hip joint. Several biomechanical studies have shown the sealing effect of the acetabular labrum. In the past decade, labral repair procedures have gained increased attention, with the literature suggesting that the outcomes after hip arthroscopy are directly related to labral preservation. However, a primary labral repair can be challenging in cases of hypoplastic, ossified, or complex and irreparable labral tears in which there is insufficient tissue to perform a primary repair. For these cases, labral reconstruction becomes a viable option with good outcomes at short-term and midterm follow-up. A subset of these patients may show viable remnants of the labral circumferential fibers but, because of the low tissue volume, these remnant fibers are unable to maintain the suction seal. In this situation, a labral augmentation may be a viable alternative to labral reconstruction while preserving as much native labral tissue as possible. The purpose of this Technical Note is to describe an arthroscopic hip labral augmentation technique using iliotibial band autograft or allograft.

  9. Recording triggered EMG thresholds from axillary chest wall electrodes: a new refined technique for accurate upper thoracic (T2-T6) pedicle screw placement.

    PubMed

    Regidor, Ignacio; de Blas, Gema; Barrios, Carlos; Burgos, Jesús; Montes, Elena; García-Urquiza, Sergio; Hevia, Edurado

    2011-10-01

    This study was aimed at evaluating the sensitivity and safety of a new technique to record triggered EMG thresholds from axillary chest wall electrodes when inserting pedicle screws in the upper thoracic spine (T2-T6). A total of 248 (36.6%) of a total of 677 thoracic screws were placed at the T2-T6 levels in 92 patients with adolescent idiopathic scoliosis. A single electrode placed at the axillary midline was able to record potentials during surgery from all T2-T6 myotomes at each side. Eleven screws were removed during surgery because of malposition according to intraoperative fluoroscopic views. Screw position was evaluated after surgery in the remaining 237 screws using a CT scan. Malposition was detected in 35 pedicle screws (14.7%). Pedicle medial cortex was breached in 24 (10.1%). Six screws (2.5%) were located inside the spinal canal. Mean EMG threshold was 24.44 ± 11.30 mA in well-positioned screws, 17.98 ± 8.24 mA (p < 0.01) in screws violating the pedicle medial cortex, and 10.38 ± 3.33 mA (p < 0.005) in screws located inside the spinal canal. Below a threshold of 12 mA, 33.4% of the screws (10/30) were malpositioned. Furthermore, 36% of the pedicle screws with t-EMG stimulation thresholds within the range 6-12 mA were malpositioned. In conclusion, assessment of upper thoracic pedicle screw placement by recording tEMG at a single axillary electrode was highly reliable. Thresholds below 12 mA should alert surgeons to suspect screw malposition. This technique simplifies tEMG potential recording to facilitate safe placement of pedicle screws at upper thoracic levels.

  10. A New Entrance Technique for C2 Pedicle Screw Placement and the Use in Patients With Atlantoaxial Instability.

    PubMed

    Liu, Jia-Ming; Jiang, Jian; Liu, Zhi-Li; Long, Xin-Hua; Chen, Wen-Zhao; Zhou, Yang; Gao, Song; He, Lai-Chang; Huang, Shan-Hu

    2017-06-01

    A prospective study and a technique note. To introduce a new entrance technique for C2 pedicle screw placement and to measure the related linear and angular parameters about the entrance point on computed tomography (CT) images. The safety of this technique for patients with atlantoaxial instability was also evaluated. Although earlier studies have introduced different methods for C2 pedicle screw placement, the entry points and the angular parameters may be variable. Few studies have established a fixed entry point on the basis of the anatomic structure of C2 for pedicle screw placement. A total of 60 dry C2 vertebrae were obtained for anatomic measurement in the study. The posterior bilateral nutrient foramens of C2 lamina were selected as the entry points for pedicle screw placement. The foramens were marked with needles and then the vertebrae underwent CT scan. The axial and sagittal planes of C2 pedicles were harvested and 4 linear and 2 angular parameters about the entry point were determined. After that, we used the entrance technique on 31 patients with atlantoaxial instability in a prospective study. CT of the cervical spine was performed to evaluate the safety of the entrance technique. The nutrient foramens exist in 97% of the left lamina and 93% of the right lamina of the C2 vertebra. The overall mean distance from the entry point (nutrient foramen) to the superior border of lamina (PSD), to the inferior border of lamina (PID), to the medial border of the pedicle (PMD), and the length of pedicle screw trajectory (PL, transit the pedicle center) were 3.32±0.63, 8.33±1.21, 6.85±1.00, and 24.47±1.51, respectively. The averaged transverse angle (α) on the axial plane and the superior angle (β) on the sagittal plane were 19.83±3.83 and 30.12±6.02 degrees, respectively. Then, 31 patients underwent bilateral C2 pedicle screw fixation without screw violation into the spinal canal or vertebral artery injury by the new entrance technique. The overall mean

  11. Impact of tunnels and tenodesis screws on clavicle fracture: a biomechanical study of varying coracoclavicular ligament reconstruction techniques.

    PubMed

    Dumont, Guillaume D; Russell, Robert D; Knight, Justin R; Hotchkiss, William R; Pierce, William A; Wilson, Philip L; Robertson, William J

    2013-10-01

    The purpose of this study was to compare the load to fracture of distal clavicles with no tunnels, one tunnel, or 2 tunnels and to evaluate the effect of inserting tenodesis screws in the tunnels on load to fracture of the distal clavicle. Fifty right sawbone clavicles were obtained and divided into 5 groups (n = 10): group 1, normal clavicle; group 2, one tunnel, no tenodesis screw; group 3, 2 tunnels, no tenodesis screws; group 4, one tunnel with tenodesis screw; and group 5, 2 tunnels with 2 tenodesis screws. Tunnels were created using a 5-mm-diameter reamer, and 5.5 × 10 mm polyethyl ethyl ketone tenodesis screws were used. A 4-point bending load was applied to the distal clavicles. Load to failure was noted for each specimen. Load to failure in clavicles without tunnels was significantly higher (1,157.18 ± 147.10 N) than in all other groups (P < .0005). No statistical differences were noted between groups 2, 3, 4, and 5. Load to failure was not statistically different in clavicles with one versus 2 tunnels. In addition, the use of tenodesis screws in the tunnels did not affect the load required to fracture. The use of tunnels in the clavicle for coracoclavicular (CC) ligament reconstruction significantly reduces the load required to fracture the distal clavicle. The addition of tenodesis screws does not appear to significantly increase the strength of the clavicle in this construct. CC ligament reconstruction techniques commonly use tunnels in the distal clavicle, which may render the clavicle more susceptible to fracture. This study helps quantify the effect of these tunnels on the strength of the distal clavicle. Copyright © 2013 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.

  12. Comparison of Consecutive, Interval, and Skipped Pedicle Screw Techniques in Moderate Lenke Type 1 Adolescent Idiopathic Scoliosis.

    PubMed

    Luo, Ming; Shen, Mingkui; Wang, Wengang; Xia, Lei

    2017-02-01

    To compare perioperative, radiographic, and Scoliosis Research Society-22 (SRS-22) outcomes of consecutive, interval, and skipped pedicle screw techniques in patients with moderate Lenke type 1 adolescent idiopathic scoliosis (AIS). We retrospectively reviewed 65 consecutive moderate Lenke type 1 AIS patients at a single institution using all-pedicle screw constructs, with a minimum of 2 years of follow-up. In the consecutive group (C group, n = 22), pedicle screws were instrumented at consecutive levels bilaterally. In the interval group (I group, n = 18), pedicle screws were placed at every level on the concave side while skipping levels on the convex side. In the skipped group (S group, n = 25), pedicle screws were instrumented by skipping levels bilaterally. Perioperative, radiographic, and SRS-22 measurements were analyzed with a 1-way analysis of variance. No significant differences were found in length of hospital stay, fused levels, coronal correction, and SRS-22 scores among the 3 groups. Increased surgery time was found in the C group compared with the I and S groups (P = 0.001 and P = 0.005, respectively). Decreased blood loss and blood transfusions were found in the S group compared with the C group (P = 0.04 and P = 0.047, respectively). Decreased implant costs were found in the S group compared with the C and I groups (P < 0.001 and P = 0.03, respectively). Consecutive, interval, and skipped pedicle screw techniques all provide satisfactory deformity correction and SRS-22 outcomes with few complications. With better perioperative outcomes, interval and skipped pedicle screw techniques are the more cost-effective options for patients with moderate Lenke type 1 AIS. Copyright © 2016 Elsevier Inc. All rights reserved.

  13. Biomechanical comparison of two techniques for arthroscopic suprapectoral biceps tenodesis: interference screw versus implant-free intraosseous tendon fixation.

    PubMed

    Sampatacos, Nels; Getelman, Mark H; Henninger, Heath B

    2014-11-01

    A novel arthroscopic technique allows for intraosseous tendon placement in biceps tenodesis using bone tunnels and suture while avoiding the expense of an implant. No biomechanical characterization exists for this construct. Tensile tests were used to compare a suture-only biceps tenodesis technique (arthroscopic biceps intraosseous tenodesis [ABIT]) with interference screws in 7 pairs of cadaveric shoulders. The ABIT used a modified finger-trap suture method to secure the tendon to itself through an intraosseous bone tunnel. Interference screw placement followed the manufacturer's protocol for implantation. An open technique was used to provide consistency during laboratory preparation. During cyclic loading, the screws were significantly stiffer (P = .040) but dissipated more energy (P = .002). During failure loading, suture-only specimens showed significantly greater failure loads (P < .001) and deformation (P = .046). The failure mechanism for the ABIT method was tendon elongation with progressive tensioning and slippage of the tendon through the suture mass. No complete tendon failure occurred for the ABIT. Gross tendon failure occurred in all interference screw tests at the bone-tendon-screw interface. No screw or suture failed in any biceps tendon test. The ABIT construct showed significantly higher failure loads and deformation compared with interference screws. The comparable stiffness after cycling of both constructs suggests that micromotion at the bone-tendon interface is similar, which-in addition to the intraosseous fixation-may be important in promoting healing. The ABIT construct was found to absorb and restore more energy (hysteresis), suggesting potential for greater tendon preservation, which may translate into improved construct longevity. The suture-only method can eliminate the expense of an implant. Copyright © 2014 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.

  14. A technique for fabricating single screw-retained implant-supported interim crowns in conjunction with implant surgery.

    PubMed

    McRory, M Eric; Cagna, David R

    2014-06-01

    This article presents an intraoral technique for fabricating single screw-retained implant-supported interim crowns immediately after surgical implant placement in extraction sites. The technique may be used with any implant system that provides a provisional abutment or an open-tray impression coping that can be modified for use as a provisional abutment.

  15. Labia Majora Augmentation with Hyaluronic Acid Filler: Technique and Results.

    PubMed

    Fasola, Elena; Gazzola, Riccardo

    2016-11-01

    External female genitalia lose elasticity and volume with age. In the literature several techniques address the redundancy of the labia minora, but only few reports describe the augmentation of labia majora with fat grafting. At present, no studies describe the augmentation of the labia majora with hyaluronic acid. This study aims to present our technique of infiltration of hyaluronic acid filler, analyzing effectiveness, patient satisfaction, and complications. We retrospectively analyzed 54 patients affected by hypotrophy of the labia majora; they were treated with hyaluronic acid filler between November 2010 and December 2014. The Global Aesthetic Improvement Scale (GAIS) filled out by the doctor and the patients was used to evaluate the results 12 months after the infiltration. Complications were recorded. A total of 31 patients affected by mild to moderate labia majora hypotrophy were treated with 19 mg/mL HA filler; 23 patients affected by severe labia majora hypotrophy were treated with 21 mg/mL HA filler. Among the first group of patients, one underwent a second infiltration 6 months later with 19 mg/mL HA filler (maximum 1 mL). A significant improvement (P < .0001) in GAIS score was observed, both in the scores provided by the patients and by the doctor. A greater relative improvement was observed in patients affected by severe hypotrophy. No complications were recorded. Hyaluronic acid infiltration of the labia majora is able to provide a significant rejuvenation with a simple outpatient procedure. We achieved significant improvements with one infiltration in all cases. The treatment is repeatable, has virtually no complications and it is reversible. 4 Therapeutic. © 2016 The American Society for Aesthetic Plastic Surgery, Inc. Reprints and permission: journals.permissions@oup.com.

  16. Biomechanical Analysis of an S1 Pedicle Screw Salvage Technique via a Superior Articulating Process Entry Point.

    PubMed

    Lee, Yu-Po; Ihn, Hansel E; McGarry, Michelle H; Farhan, Saifal-Deen; Bhatia, Nitin; Lee, Thay Q

    2016-07-01

    Biomechanical, cadaveric study. To compare the fixation strength of a novel S1 pedicle screw insertion technique in a revision setting to a standard S1 pedicle screw and an L5 pedicle screw. Fusions to the sacrum remain a difficult clinical challenge. Very few salvage techniques exist when a nonunion occurs. The biomechanical integrity of three screw fixations, L5 pedicle screws, a standard S1 pedicle screw, and an S1 pedicle screw placed via a superior articulating process entry point (SAP S1), was characterized by performing pullout tests using cadaveric specimens including L5 and sacrum. SAP S1 constructs (735.5 ± 110.1 N/mm) were significantly stiffer than standard S1 (P = 0.005) and L5 (P = 0.02) constructs. There was no statistically significant difference between the L5 constructs and the standard S1 constructs for linear stiffness. There was no statistical difference between the three fixations for yield load, displacement at yield load, and energy absorbed to yield load.The ultimate pullout force for the SAP S1 was statistically higher than the standard S1 (1213.7 ± 579.6 vs. 478.6 ± 452.9 N; P = 0.004). Displacement at ultimate load was significantly greater for L5 screw fixation (3.3 ± 1.1 mm) compared to the other two constructs. Both the L5 (2277.4 ± 1873.3 N-mm) and SAP S1 (2628.2 ± 2054.4 N-mm) constructs had significantly greater energy absorbed to ultimate load than the standard S1 construct (811.7 ± 937.6 N-mm), but there was no statistical difference between the L5 and SAP S1 constructs. S1 pedicle screw fixation via an SAP entry point provides biomechanical advantages compared to screws placed via the standard S1 or L5 entry point and may be a viable option for revision of a failed L5-S1 fusion with a compromised standard S1 entry point. N/A.

  17. Node Augmentation Technique in Bayesian Network Evidence Analysis and Marshaling

    SciTech Connect

    Keselman, Dmitry; Tompkins, George H; Leishman, Deborah A

    2010-01-01

    Given a Bayesian network, sensitivity analysis is an important activity. This paper begins by describing a network augmentation technique which can simplifY the analysis. Next, we present two techniques which allow the user to determination the probability distribution of a hypothesis node under conditions of uncertain evidence; i.e. the state of an evidence node or nodes is described by a user specified probability distribution. Finally, we conclude with a discussion of three criteria for ranking evidence nodes based on their influence on a hypothesis node. All of these techniques have been used in conjunction with a commercial software package. A Bayesian network based on a directed acyclic graph (DAG) G is a graphical representation of a system of random variables that satisfies the following Markov property: any node (random variable) is independent of its non-descendants given the state of all its parents (Neapolitan, 2004). For simplicities sake, we consider only discrete variables with a finite number of states, though most of the conclusions may be generalized.

  18. The effect of different screw-tightening techniques on the strain generated on an internal-connection implant superstructure. Part 2: Models created with a splinted impression technique.

    PubMed

    Choi, Jung-Han

    2011-01-01

    This study aimed to evaluate the effect of different screw-tightening sequences, torques, and methods on the strains generated on an internal-connection implant (Astra Tech) superstructure with good fit. An edentulous mandibular master model and a metal framework directly connected to four parallel implants with a passive fit to each other were fabricated. Six stone casts were made from a dental stone master model by a splinted impression technique to represent a well-fitting situation with the metal framework. Strains generated by four screw-tightening sequences (1-2-3-4, 4-3-2-1, 2-4-3-1, and 2-3-1-4), two torques (10 and 20 Ncm), and two methods (one-step and two-step) were evaluated. In the two-step method, screws were tightened to the initial torque (10 Ncm) in a predetermined screw-tightening sequence and then to the final torque (20 Ncm) in the same sequence. Strains were recorded twice by three strain gauges attached to the framework (superior face midway between abutments). Deformation data were analyzed using multiple analysis of variance at a .05 level of statistical significance. In all stone casts, strains were produced by connection of the superstructure, regardless of screw-tightening sequence, torque, and method. No statistically significant differences in superstructure strains were found based on screw-tightening sequences (range, -409.8 to -413.8 μm/m), torques (-409.7 and -399.1 μm/m), or methods (-399.1 and -410.3 μm/m). Within the limitations of this in vitro study, screw-tightening sequence, torque, and method were not critical factors for the strain generated on a well-fitting internal-connection implant superstructure by the splinted impression technique. Further studies are needed to evaluate the effect of screw-tightening techniques on the preload stress in various different clinical situations.

  19. Four-Corner Arthrodesis: Description of Surgical Technique Using Headless Retrograde Crossed Screws.

    PubMed

    Mamede, João; Castro Adeodato, Sandro; Aquino Leal, Rafael

    2017-04-01

    Four-corner fusion has been shown to be a reliable option of treatment of wrist arthritis, but there is no consensus about which implant and surgical procedure should be used in the arthrodesis. The present study aimed to describe a surgical technique using 2 crossed screws as implants, inserted in a retrograde manner, and to demonstrate preliminary results of the use of the technique. A retrospective study was conducted using medical records and imaging tests (radiographs and computed tomography) of all 15 patients who underwent a standardized 4-corner fusion technique, between December 2011 and July 2015, in the Department of Hand Surgery of Instituto Nacional de Traumatologia e Ortopedia (INTO), Rio de Janeiro, Brazil. We collected data on the following variables: fusion rate, time to fusion, and percentage of patients who had any complications or needed another surgical procedure on the same wrist. All but one patient achieved fusion of arthrodesis. The average time to union was 5.54 months (SD = 3.84). Only the patient who developed nonunion of the 4-corner fusion required another surgery on the same wrist. The procedure described in this study demonstrated a low complication rate and high fusion rate, and can therefore be considered a reliable surgical technique for 4-corner fusion.

  20. Reduction and fixation of sacroiliac joint dislocation by the combined use of S1 pedicle screws and the galveston technique.

    PubMed

    Abumi, K; Saita, M; Iida, T; Kaneda, K

    2000-08-01

    This retrospective study was designed to analyze the results of the treatment with S1 pedicle screws and the Galveston technique of seven patients with sacroiliac dislocation. To evaluate the effectiveness of the combined use of S1 pedicle screws and the Galveston technique for the treatment of sacroiliac dislocation. Although several procedures for internal fixation of sacroiliac dislocation have been reported, there have been no reports discussing surgical treatment of sacroiliac dislocation by the combined use of S1 pedicle screws and the Galveston technique. Seven patients with sacroiliac dislocation were treated with pedicle screws of S1 and iliac rod according to the Galveston technique. In the seven patients, the dislocation was associated with vertical displacement of the sacroiliac joint and rotational deformity of the pelvic ring. They were classified into Type-C pelvic disruption according to the Tile's classification. Three patients with disruption of the symphysis pubis underwent additional fixation of the symphysis using a dynamic compression plate. The remaining four patients were treated by the posterior procedure alone. The vertical displacement was completely reduced in five patients, and the rotational deformity was completely corrected in four patients. The reduction was maintained at the time of the final follow-up evaluation. There were no perioperative complications with the exception of late infection in one patient. The combined use of S1 pedicle screws and the Galveston technique provided immediate stability and sufficient reduction for sacroiliac dislocation in seven patients in this study. This hybrid internal fixation procedure is useful for reduction and fixation of sacroiliac dislocation associated with the vertical and rotational instability of the pelvic ring.

  1. Biomechanical Comparison Between Bashti Bone Plug Technique and Biodegradable Screw for Fixation of Grafts in Ligament surgery

    PubMed Central

    Bashti, Kaveh; Tahmasebi, Mohammad N; Kaseb, Hasan; Farahmand, Farzam; Akbar, Mohammad; Mobini, Amir

    2015-01-01

    Background: Ligament reconstruction is a common procedure in orthopedic surgery. Although several popular techniques are currently in use, new methods are proposed for secure fixation of the tendon graft into the bone tunnel. Purposes: We sought to introduce our new technique of Bashti bone plug for fixation of soft tissue graft in anterior cruciate ligament (ACL) reconstruction and to compare its biomechanical features with conventional absorbable interference screw technique in a bovine model. Methods: Twenty pairs of bovine knees were harvested after death. Soft tissue was removed and the Achilles tendon was harvested to be used as an ACL graft. It was secured into the bone tunnel on the tibial side via two different methods: Bashti Bone Plug technique and conventional screw method. Biomechanical strength was measured using 200 N and 300 N cyclic loading on the graft. Pull out strength was also tested until the graft fails. Results: No graft failure was observed after 200 N and 300 N cyclic loading in either fixation methods. When testing for pull out failure, 21 tendons (53%) were torn and 19 tendons (48%) slipped out. No fixation failure occurred, which did not reveal a significant difference between the bone plug or interference screw group (P=0.11). The mean pull out force until failure of the graft was 496±66 N in the screw group and 503±67 N in the bone plug group (P=0.76). Conclusions: Our suggested fixation technique of Bashti bone plug is a native, cheap, and feasible method that provides comparable biomechanical strength with interference screw when soft tissue fixation was attempted in bovine model. PMID:25692166

  2. Biomechanical Comparison Between Bashti Bone Plug Technique and Biodegradable Screw for Fixation of Grafts in Ligament surgery.

    PubMed

    Bashti, Kaveh; Tahmasebi, Mohammad N; Kaseb, Hasan; Farahmand, Farzam; Akbar, Mohammad; Mobini, Amir

    2015-01-01

    Ligament reconstruction is a common procedure in orthopedic surgery. Although several popular techniques are currently in use, new methods are proposed for secure fixation of the tendon graft into the bone tunnel. We sought to introduce our new technique of Bashti bone plug for fixation of soft tissue graft in anterior cruciate ligament (ACL) reconstruction and to compare its biomechanical features with conventional absorbable interference screw technique in a bovine model. Twenty pairs of bovine knees were harvested after death. Soft tissue was removed and the Achilles tendon was harvested to be used as an ACL graft. It was secured into the bone tunnel on the tibial side via two different methods: Bashti Bone Plug technique and conventional screw method. Biomechanical strength was measured using 200 N and 300 N cyclic loading on the graft. Pull out strength was also tested until the graft fails. No graft failure was observed after 200 N and 300 N cyclic loading in either fixation methods. When testing for pull out failure, 21 tendons (53%) were torn and 19 tendons (48%) slipped out. No fixation failure occurred, which did not reveal a significant difference between the bone plug or interference screw group (P=0.11). The mean pull out force until failure of the graft was 496±66 N in the screw group and 503±67 N in the bone plug group (P=0.76). Our suggested fixation technique of Bashti bone plug is a native, cheap, and feasible method that provides comparable biomechanical strength with interference screw when soft tissue fixation was attempted in bovine model.

  3. Anterior-inferior tibiofibular ligament anatomical repair and augmentation versus trans-syndesmosis screw fixation for the syndesmotic instability in external-rotation type ankle fracture with posterior malleolus involvement: A prospective and comparative study.

    PubMed

    Zhan, Yu; Yan, Xiaoyu; Xia, Ronggang; Cheng, Tao; Luo, Congfeng

    2016-07-01

    Syndesmosis injury is common in external-rotation type ankle fractures (ERAF). Trans-syndesmosis screw fixation, the gold-standard treatment, is currently controversial for its complications and biomechanical disadvantages. The purpose of this study was to introduce a new method of anatomically repairing the anterior-inferior tibiofibular ligament (AITFL) and augmentation with anchor rope system to treat the syndesmotic instability in ERAF with posterior malleolus involvement and to compare its clinical outcomes with that of trans-syndesmosis screw fixation. 53 ERAFs with posterior malleolus involvement received surgery, and the syndesmosis was still unstable after fracture fixation. They were randomised into screw fixation group and AITFL anatomical repair with augmentation group. Reduction quality, syndesmosis diastasis recurrence, pain (VAS score), time back to work, Olerud-Molander ankle score and range of motion (ROM) of ankle were investigated. Olerud-Molander score in AITFL repair group and screw group was 90.4 and 85.8 at 12-month follow-up (P>0.05). Plantar flexion was 31.2° and 34.3° in repair and screw groups (P=0.04). Mal-reduction happened in 5 cases (19.2%) in screw group while 2 cases (7.4%) in repair group. Postoperative syndesmosis re-diastasis occurred in 3 cases in screw group while zero in repair group (P>0.05). Pain score was similar between the two groups (P>0.05). Overall complication rate and back to work time were 26.9% and 3.7% (P=0.04), 7.15 months and 5.26 months (P=0.02) in screw group and repair group, respectively. For syndesmotic instability in ERAF with posterior malleolus involvement, the method of AITFL anatomical repair and augmentation with anchor rope system had an equivalent functional outcome and reduction, earlier rehabilitation and less complication compared with screw fixation. It can be selected as an alternative. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. Cervical pedicle screw fixation in traumatic cervical subluxation after laminectomy using the pedicle axis view technique under fluoroscopy.

    PubMed

    Machino, Masaaki; Yukawa, Yasutsugu; Ito, Keigo; Nakashima, Hiroaki; Kanbara, Shunsuke; Morita, Daigo; Kato, Fumihiko

    2012-10-10

    Cervical pedicle screw (CPS) fixation has recently been performed in patients in need of cervical reconstruction. We report the case of a 50-year-old man who was operated for traumatic cervical vertebra subluxation using CPS fixation, in whom laminectomy had been performed in the past. We performed CPS fixation using the pedicle axis view technique under fluoroscopy. The four pedicle screws were accurately inserted within the pedicles without perforating the bone cortex of the pedicles. A navigation system is useful for cervical spine surgery because it enables a surgeon to perform relatively safe and accurate surgery during transpedicular screw fixation. However, attachment of the stereotactic reference arc to the spinous process is impossible, and the application of a navigation system is limited in cases in which laminectomy has been performed in the past. We have been using the pedicle axis view technique under fluoroscopy and have found that if we take care of the entry point accurately, we can safely insert the pedicle screw in cases with fewer landmarks.

  5. A testing technique allowing cyclic application of axial, bending, and torque loads to fracture plates to examine screw loosening.

    PubMed

    Szivek, J A; Yapp, R A

    1989-04-01

    Orthopaedic internal fracture fixation plates are subjected to combined axial, bending, and torsional loads in vivo which can cause screw loosening and implant failure. This paper outlines a relatively simple technique which allows controlled application of combined axial, bending, and torsional loading to examine the loosening rate of cortical screws used to attach these plates. Fiber reinforced polycarbonate rods with a tensile strength similar to that of cortical bone were cut at half their length to simulate fractured tibii. These were compression plated using a standardized technique and placed in a loading fixture. Joint loads at the knee determined from force plate analysis and statics were applied to a plated fixture during testing. The design of the fixture allowed adjustment of the proportion of bending and torsional loads applied to the test samples. It also allowed a reproducible means of applying a predetermined axial, bending, and torsional load. Screw loosening following cyclical loading was evaluated by measuring the amount of angular displacement required to retighten screws to a prescribed torque value. A torque wrench was modified to allow the measurement of these displacements.

  6. Proximal screws placement in intertrochanteric fractures treated with external fixation: comparison of two different techniques

    PubMed Central

    2011-01-01

    Background To compare two different techniques of proximal pin placement for the treatment of intertrochanteric fractures in elderly patients utilizing the Orthofix Pertrochanteric Fixator. Methods Seventy elderly high-risk patients with an average age of 81 years were treated surgically for intertrochanteric fracture, resulting from a low energy trauma. Patients were randomly divided in two groups regarding to the proximal pin placement technique. In Group A the proximal pins were inserted in a convergent way, while in Group B were inserted in parallel. Results All fractures healed uneventfully after a mean time of 98 days. The fixator was well accepted and no patient had significant difficulties while sitting or lying. The mean VAS score was 5.4 in group A and 5.7 in group B. At 12 months after surgery, in group A the average Harris Hip Score and the Palmer and Parker mobility score was 67 and 5.8, respectively. In group B, the average Harris Hip Score and the Palmer and Parker mobility score was 62 and 5.6, respectively. No statistically significant difference was found regarding the functional outcome. The mean radiographic exposure during pin insertion in Group A and Group B was 15 and 6 seconds, respectively. The difference between the two groups, regarding the radiographic exposure, was found to be significant. Conclusion Proximal screw placement in a parallel way is simple, with significant less radiation exposure and shorter intraoperative duration. In addition, fixation stability is equal compared to convergent pin placement. PMID:21939534

  7. Active and passive techniques for tiltrotor aeroelastic stability augmentation

    NASA Astrophysics Data System (ADS)

    Hathaway, Eric L.

    Tiltrotors are susceptible to whirl flutter, an aeroelastic instability characterized by a coupling of rotor-generated aerodynamic forces and elastic wing modes in high speed airplane-mode flight. The conventional approach to ensuring adequate whirl flutter stability will not scale easily to larger tiltrotor designs. This study constitutes an investigation of several alternatives for improving tiltrotor aerolastic stability. A whirl flutter stability analysis is developed that does not rely on more complex models to determine the variations in crucial input parameters with flight condition. Variation of blade flap and lag frequency, and pitch-flap, pitch-lag, and flap-lag couplings, are calculated from physical parameters, such as blade structural flap and lag stiffness distribution (inboard or outboard of pitch bearing), collective pitch, and precone. The analysis is used to perform a study of the influence of various design parameters on whirl flutter stability. While previous studies have investigated the individual influence of various design parameters, the present investigation uses formal optimization techniques to determine a unique combination of parameters that maximizes whirl flutter stability. The optimal designs require only modest changes in the key rotor and wing design parameters to significantly increase flutter speed. When constraints on design parameters are relaxed, optimized configurations are obtained that allow large values of kinematic pitch-flap (delta3) coupling without degrading aeroelastic stability. Larger values of delta3 may be desirable for advanced tiltrotor configurations. An investigation of active control of wing flaperons for stability augmentation is also conducted. Both stiff- and soft-inplane tiltrotor configurations are examined. Control systems that increase flutter speed and wing mode sub-critical damping are designed while observing realistic limits on flaperon deflection. The flaperon is shown to be particularly

  8. Architecture and Key Techniques of Augmented Reality Maintenance Guiding System for Civil Aircrafts

    NASA Astrophysics Data System (ADS)

    hong, Zhou; Wenhua, Lu

    2017-01-01

    Augmented reality technology is introduced into the maintenance related field for strengthened information in real-world scenarios through integration of virtual assistant maintenance information with real-world scenarios. This can lower the difficulty of maintenance, reduce maintenance errors, and improve the maintenance efficiency and quality of civil aviation crews. Architecture of augmented reality virtual maintenance guiding system is proposed on the basis of introducing the definition of augmented reality and analyzing the characteristics of augmented reality virtual maintenance. Key techniques involved, such as standardization and organization of maintenance data, 3D registration, modeling of maintenance guidance information and virtual maintenance man-machine interaction, are elaborated emphatically, and solutions are given.

  9. The Expanded Use of Auto-augmentation Techniques in Oncoplastic Breast Surgery.

    PubMed

    Losken, Albert; Hart, Alexandra M; Dutton, James Walter; Broecker, Justine S; Styblo, Toncred M; Carlson, Grant W

    2017-09-13

    Auto-augmentation techniques have been applied to oncoplastic reductions to assist with filling larger, more remote defects and women with smaller breasts. The purpose of this report is to describe the use of auto-augmentation techniques in OR and compare the results with traditional OR. We queried a prospectively maintained database of all women who underwent partial mastectomy and OR between 1994 and October 2015. The auto-augmentation techniques were defined as 1) extended primary nipple auto-augmentation pedicle, and 2) primary nipple pedicle and secondary auto-augmentation pedicle. Comparisons were made to a control oncoplastic group. There were a total of 333 patients, 222 patients (67.7%) without auto-augmentation and 111 patients (33%) with auto-augmentation. Fifty-one patients had extended auto-augmentation pedicle, and 60 patients with a secondary auto-augmentation pedicle. Biopsy weight was smallest in the extended pedicle group (136 grams) and largest in the regular oncoplastic group (235 grams, p=0.017). Superomedial was the most common extended pedicle and lateral being the most common location. Inferorolateral was the most common secondary pedicle for lateral and upper outer defects. There were no significant differences in the overall complication rate: 15.5% in the regular oncoplastic group, 19.6% in the extended pedicle group, and 20% in the secondary pedicle group. Auto-augmentation techniques have evolved to manage complex defects not amenable to standard oncoplastic reduction methods. They are often required for lateral defects especially in smaller breasts. Auto-augmentation can be done safely without increase risk of complications, broadening the indications for breast conservation therapy.

  10. Pedicle Screw Configuration for Thoracolumbar Burst Fracture Treatment: Short versus Long Posterior Fixation Constructs with and without Anterior Column Augmentation.

    PubMed

    Peters, Todd; Chinthakunta, Suresh Reddy; Hussain, Mir; Khalil, Saif

    2014-02-01

    An in-vitro study. The current study is aimed at investigating the differences in stability between short posterior fixation (SPF), hybrid posterior fixation (HPF), and long posterior fixation (LPF) with and without anterior column augmentation using calcium phosphate bone cement (CaP) for treating burst fractures (BFs). The ideal treatment for thoracolumbar BF is controversial regarding the use of short or LPF constructs. Seven human thoracolumbar spines (T9-L4) were tested on a six degree of freedom spine simulator in three physiologic planes, flexion-extension (FE), lateral bending (LB), and axial rotation (AR). Tested surgical constructs included the following: intact, injury (BF), SPF (T12-L2), HPF (T11-L2), LPF (T11-L3), SPF+CaP, HPF+CaP, LPF+CaP, and CaP alone (CaP). Range of motion (ROM) was recorded at T12-L2 in FE, LB, and AR. THE REDUCTION IN MEAN ROM TRENDED AS FOLLOWS: LPF>HPF>SPF. Only LPF constructs and HPF with anterior column augmentation significantly reduced mean ROM in FE and LB compared to the intact state. All instrumented constructs (SPF, HPF, and LPF) significantly reduced ROM in FE and LB compared to the injured condition. Furthermore, the instrumented constructs did not provide significant rotational stability. Injecting CaP provided minimal additional stability. For the injury created, LPF and HPF provided better stability than SPF with and without anterior column augmentation. Therefore, highly unstable fractures may require extended, long or hybrid fusion constructs for optimum stability.

  11. Patch-augmented rotator cuff repair: influence of the patch fixation technique on primary biomechanical stability.

    PubMed

    Jung, Christian; Spreiter, Gregor; Audigé, Laurent; Ferguson, Stephen J; Flury, Matthias

    2016-05-01

    There is an ongoing debate about the potential of patch augmentation to improve biomechanical stability and healing associated with rotator cuff repair. The biomechanical properties of three different patch-augmented rotator cuff repair techniques were assessed in vitro and compared with a standard repair. Dermal collagen patch augmentation may increase the primary stability and strength of the repaired tendon in vitro, depending on the technique used for patch application. Forty cadaveric sheep shoulders with dissected infraspinatus tendons were randomized into four groups (n = 10/group) for tendon repair using a knotless double-row suture anchor technique. A xenologous dermal extracellular matrix patch was used for augmentation in the three test groups using an "integrated", "cover", or "hybrid" technique. Tendons were preconditioned, cyclically loaded from 10 to 30 N at 1 Hz, and then loaded monotonically to failure. Biomechanical properties and the mode of failure were evaluated. Patch augmentation significantly increased the maximum load at failure by 61 % in the "cover" technique test group (225.8 N) and 51 % in the "hybrid" technique test group (211.4 N) compared with the non-augmented control group (140.2 N) (P ≤ 0.015). For the test group with "integrated" patch augmentation, the load at failure was 28 % lower (101.6 N) compared with the control group (P = 0.043). There was no significant difference in initial and linear stiffness among the four experimental groups. The most common mode of failure was tendon pullout. No anchor dislocation, patch disruption or knot breakage was observed. Additional patch augmentation with a collagen patch influences the biomechanical properties of a rotator cuff repair in a cadaveric sheep model. Primary repair stability can be significantly improved depending on the augmentation technique.

  12. Proximal Biceps Tenodesis: An Anatomic Study and Comparison of the Accuracy of Arthroscopic and Open Techniques Using Interference Screws.

    PubMed

    Kovack, Thomas J; Idoine, John D; Jacob, Paul B

    2014-02-01

    To (1) better define the anatomy of the proximal shoulder in relation to the long head of the biceps tendon, (2) compare the length-tension relationship of the biceps tendon in the native shoulder with that after arthroscopic and open tenodesis techniques using interference screws, and (3) provide surgical recommendations for both procedures based on study findings. Descriptive laboratory study. Twenty fresh-frozen cadaveric shoulders were dissected for analysis. Initial anatomic measurements involving the proximal long head of the biceps tendon (BT) were made, which included: the labral origin to the superior bicipital groove (LO-SBG), the total tendon length (TTL), the musculotendinous junction (MTJ) to the inferior pectoralis major tendon border, the MTJ to the superior pectoralis major tendon border, and the biceps tendon diameter (BTD) at 2 different tenodesis locations. These same measurements were made again after completing a simulated suprapectoral arthroscopic and open subpectoral tenodesis, both with interference screw fixation. Statistical comparisons were then made between the native anatomy and that after tenodesis, with the goal of assessing the accuracy of re-establishing the normal length-tension relationship of the long head of the BT after simulated arthroscopic suprapectoral and open subpectoral tenodesis with tenodesis screws. For all cadavers, the mean TTL was 104.1 mm. For the arthroscopic suprapectoral technique, the mean LO-SBG was 33.6 mm, and the mean tendon resection length was 12.8 mm in males and 5.0 mm in females. The mean BTD was 6.35 mm at the arthroscopic suprapectoral tenodesis site and 5.75 mm at the open subpectoral tenodesis site. Males were found to have statistically longer TTL and LO-SBG measurements (111.6 vs 96.5 mm [P = .027] and 37.2 vs 30.0 mm [P = .009], respectively). In the native shoulder, the mean distances from the MTJ to the superior and inferior borders of the pectoralis major tendon were 23.8 and 31.7 mm

  13. Posterior spinal fusion for adolescent idiopathic scoliosis using a convex pedicle screw technique: a novel concept of deformity correction.

    PubMed

    Tsirikos, A I; Mataliotakis, G; Bounakis, N

    2017-08-01

    We present the results of correcting a double or triple curve adolescent idiopathic scoliosis using a convex segmental pedicle screw technique. We reviewed 191 patients with a mean age at surgery of 15 years (11 to 23.3). Pedicle screws were placed at the convexity of each curve. Concave screws were inserted at one or two cephalad levels and two caudal levels. The mean operating time was 183 minutes (132 to 276) and the mean blood loss 0.22% of the total blood volume (0.08% to 0.4%). Multimodal monitoring remained stable throughout the operation. The mean hospital stay was 6.8 days (5 to 15). The mean post-operative follow-up was 5.8 years (2.5 to 9.5). There were no neurological complications, deep wound infection, obvious nonunion or need for revision surgery. Upper thoracic scoliosis was corrected by a mean 68.2% (38% to 48%, p < 0.001). Main thoracic scoliosis was corrected by a mean 71% (43.5% to 8.9%, p < 0.001). Lumbar scoliosis was corrected by a mean 72.3% (41% to 90%, p < 0.001). No patient lost more than 3° of correction at follow-up. The thoracic kyphosis improved by 13.1° (-21° to 49°, p < 0.001); the lumbar lordosis remained unchanged (p = 0.58). Coronal imbalance was corrected by a mean 98% (0% to 100%, p < 0.001). Sagittal imbalance was corrected by a mean 96% (20% to 100%, p < 0.001). The Scoliosis Research Society Outcomes Questionnaire score improved from a mean 3.6 to 4.6 (2.4 to 4, p < 0.001); patient satisfaction was a mean 4.9 (4.8 to 5). This technique carries low neurological and vascular risks because the screws are placed in the pedicles of the convex side of the curve, away from the spinal cord, cauda equina and the aorta. A low implant density (pedicle screw density 1.2, when a density of 2 represents placement of pedicle screws bilaterally at every instrumented segment) achieved satisfactory correction of the scoliosis, an improved thoracic kyphosis and normal global sagittal balance. Both patient satisfaction and functional

  14. Combined S-1 and S-2 sacral alar-iliac screws as a salvage technique for pelvic fixation after pseudarthrosis and lumbosacropelvic instability: combined S-1 and S-2 sacral alar-iliac screws as a salvage technique for pelvic fixation after pseudarthrosis and lumbosacropelvic instability: technical note.

    PubMed

    Mattei, Tobias A; Fassett, Daniel R

    2013-09-01

    Lumbosacropelvic pseudarthrosis after long spinal fusions for treatment of adult degenerative scoliosis remains a challenging condition. Moreover, although pelvic fixation with iliac screws is widely used in deformity surgery to provide a biomechanically strong distal anchor for long thoracolumbar constructs, there are very few options available after failed pelvic fixation with iliac screws. The authors conducted a retrospective review of the surgical charts and imaging findings of patients subjected to revision surgery for lumbosacropelvic pseudarthrosis from August 2011 to August 2012. This review identified 5 patients in whom a salvage technique combining both S-1 and S-2 sacral alar-iliac (SAI) screws had been performed. In this technical note, the authors present a detailed anatomical discussion and an appraisal of the sequential intraoperative steps of this new technique involving a combination of S-1 and S-2 SAI screws. The discussion is illustrated with a surgical case in which this technique was used to treat a patient with pseudarthrosis that had developed after fixation with classic iliac screws. In conclusion, although S-2 SAI screws have previously been reported as an interesting alternative to classic iliac wing screws, this report is the first on the use of combined S-1 and S-2 SAI screws for pelvic fixation as a salvage technique for lumbosacropelvic instability. According to the reported experience, this technique provides a biomechanically robust construct for definitive pelvic fixation during revision surgeries in the challenging scenarios of pseudarthrosis and instability of the lumbosacropelvic region.

  15. Significance of the Pars Interarticularis in the Cortical Bone Trajectory Screw Technique: An In Vivo Insertional Torque Study

    PubMed Central

    Iwatsuki, Koichi; Ohnishi, Yu-Ichiro; Ohkawa, Toshika; Yoshimine, Toshiki

    2016-01-01

    Study Design Retrospective study. Purpose Cortical bone trajectory (CBT), a more medial-to-lateral and shorter path than the traditional one for spinal fusion, is thought to be effective for severely degenerated vertebrae because screws are primarily stabilized at the posterior elements. We evaluated the efficacy of this approach through in vivo insertional torque measurement. Overview of Literature There has been only one prior in vivo study on CBT insertional torque. Methods Between January 2013 and April 2014, a total of 22 patients underwent posterior lumbar fusion using the CBT technique. The maximum insertional torque, which covers the radial strength needed for insertion, was measured for 113 screws, 8 of which were inserted for L5 spondylolysis. The insertional torque for cases with (n=8) and without (n=31) spondylolysis of L5 were compared using one-way analysis of variance (ANOVA). To evaluate vertebral degeneration, we classified 53 vertebrae without spondylolysis by lumbar radiography using semiquantitative methods; the insertional torque for the 105 screws used was compared on the basis of this classification. Additionally, differences in insertional torque among cases grouped by age, sex, and lumbar level were evaluated for these 105 screws using ANOVA and the Tukey test. Results The mean insertional torque was significantly lower for patients with spondylolysis than for those without spondylolysis (4.25 vs. 8.24 in-lb). There were no statistical differences in insertional torque according to vertebral grading or level. The only significant difference in insertional torque between age and sex groups was in men <75 years and women ≥75 years (10 vs. 5.5 in-lb). Conclusions Although CBT should be used with great caution in patient with lysis who are ≥75 years, it is well suited for dealing with severely degenerated vertebrae because the pars interarticularis plays a very important role in the implementation of this technique. PMID:27790318

  16. Novel Augmentation Technique for Patellar Tendon Repair Improves Strength and Decreases Gap Formation: A Cadaveric Study.

    PubMed

    Black, James C; Ricci, William M; Gardner, Michael J; McAndrew, Christopher M; Agarwalla, Avinesh; Wojahn, Robert D; Abar, Orchid; Tang, Simon Y

    2016-12-01

    Patellar tendon ruptures commonly are repaired using transosseous patellar drill tunnels with modified-Krackow sutures in the patellar tendon. This simple suture technique has been associated with failure rates and poor clinical outcomes in a modest proportion of patients. Failure of this repair technique can result from gap formation during loading or a single catastrophic event. Several augmentation techniques have been described to improve the integrity of the repair, but standardized biomechanical evaluation of repair strength among different techniques is lacking. The purpose of this study was to describe a novel figure-of-eight suture technique to augment traditional fixation and evaluate its biomechanical performance. We hypothesized that the augmentation technique would (1) reduce gap formation during cyclic loading and (2) increase the maximum load to failure. Ten pairs (two male, eight female) of fresh-frozen cadaveric knees free of overt disorders or patellar tendon damage were used (average donor age, 76 years; range, 65-87 years). For each pair, one specimen underwent the standard transosseous tunnel suture repair with a modified-Krackow suture technique and the second underwent the standard repair with our experimental augmentation method. Nine pairs were suitable for testing. Each specimen underwent cyclic loading while continuously measuring gap formation across the repair. At the completion of cyclic loading, load to failure testing was performed. A difference in gap formation and mean load to failure was seen in favor of the augmentation technique. At 250 cycles, a 68% increase in gap formation was seen for the control group (control: 5.96 ± 0.86 mm [95% CI, 5.30-6.62 mm]; augmentation: 3.55 ± 0.56 mm [95% CI, 3.12-3.98 mm]; p = 0.02). The mean load to failure was 13% greater in the augmentation group (control: 899.57 ± 96.94 N [95% CI, 825.06-974.09 N]; augmentation: 1030.70 ± 122.41 N [95% CI, 936.61-1124.79 N]; p = 0.01). This biomechanical

  17. The accuracy of the lateral vertebral notch-referred pedicle screw insertion technique in subaxial cervical spine: a human cadaver study.

    PubMed

    Luo, Jiaquan; Wu, Chunyang; Huang, Zhongren; Pan, Zhimin; Li, Zhiyun; Zhong, Junlong; Chen, Yiwei; Han, Zhimin; Cao, Kai

    2017-04-01

    This is a cadaver specimen study to confirm new pedicle screw (PS) entry point and trajectory for subaxial cervical PS insertion. To assess the accuracy of the lateral vertebral notch-referred PS insertion technique in subaxial cervical spine in cadaver cervical spine. Reported morphometric landmarks used to guide the surgeon in PS insertion show significant variability. In the previous study, we proposed a new technique (as called "notch-referred" technique) primarily based on coronal multiplane reconstruction images (CMRI) and cortical integrity after PS insertion in cadavers. However, the PS position in cadaveric cervical segment was not confirmed radiologically. Therefore, the difference between the pedicle trajectory and the PS trajectory using the notch-referred technique needs to be illuminated. Twelve cadaveric cervical spines were conducted with PS insertion using the lateral vertebral notch-referred technique. The guideline for entry point and trajectory for each vertebra was established based on the morphometric data from our previous study. After 3.5-mm diameter screw insertion, each vertebra was dissected and inspected for pedicle trajectory by CT scan. The pedicle trajectory and PS trajectory were measured and compared in axial plane. The perforation rate was assessed radiologically and was graded from ideal to unacceptable: Grade 0 = screw in pedicle; Grade I = perforation of pedicle wall less than one-fourth of the screw diameter; Grade II = perforation more than one-fourth of the screw diameter but less than one-second; Grade III = perforation more than one-second outside of the screw diameter. In addition, pedicle width between the acceptable and unacceptable screws was compared. A total of 120 pedicle screws were inserted. The perforation rate of pedicle screws was 78.3% in grade 0 (excellent PS position), 10.0% in grade I (good PS position), 8.3% in grade II (fair PS position), and 3.3% in grade III (poor PS position). The

  18. A Prospective Randomized Study Comparing the Interference Screw and Suture Anchor Techniques for Biceps Tenodesis.

    PubMed

    Park, Ji Soon; Kim, Sae Hoon; Jung, Ho Jin; Lee, Ye Hyun; Oh, Joo Han

    2017-02-01

    Several methods are used to perform biceps tenodesis in patients with superior labrum-biceps complex (SLBC) lesions accompanied by a rotator cuff tear. However, limited clinical data are available regarding the best technique in terms of clinical and anatomic outcomes. To compare the clinical and anatomic outcomes of the interference screw (IS) and suture anchor (SA) fixation techniques for biceps tenodesis performed along with arthroscopic rotator cuff repair. Randomized controlled trial; Level of evidence, 2. A total of 80 patients who underwent arthroscopic rotator cuff repair with SLBC lesions were prospectively enrolled and randomly divided according to the tenodesis method: the IS and SA groups. Functional outcomes were evaluated with the visual analog scale (VAS) for pain, American Shoulder and Elbow Surgeons (ASES) score, Simple Shoulder Test (SST), Constant score, Korean Shoulder Score (KSS), and long head of the biceps (LHB) score at least 2 years after surgery. The anatomic status of tenodesis was estimated using magnetic resonance imaging or ultrasonography, and the anatomic failure of tenodesis was determined when the biceps tendon was not traced in the intertubercular groove directly from the insertion site of the IS or SA. Thirty-three patients in the IS group and 34 in the SA group were monitored for more than 2 years. All postoperative functional scores improved significantly compared with the preoperative scores (all P < .001) and were not significantly different between the groups, including the LHB score (all P > .05). Nine anatomic failures of tenodesis were observed: 7 in the IS group and 2 in the SA group ( P = .083). In a multivariate analysis using logistic regression, IS fixation ( P = .003) and a higher (ie, more physically demanding) work level ( P = .022) were factors associated with the anatomic failure of tenodesis significantly. In patients with tenodesis failure, the LHB score ( P = .049) and the degree of Popeye deformity by the

  19. Training Distal Locking Screw Insertion Skills to Novice Trainees: A Comparison Between Fluoroscopic- and Electromagnetic-Guided Techniques.

    PubMed

    Leroux, Timothy; Khoshbin, Amir; Nousiainen, Markku T

    2015-10-01

    To compare the effect fluoroscopy or electromagnetic (EM) guidance has on the learning of locking screw insertion in tibial nails in surgical novices. A randomized, prospective, controlled trial was conducted involving 18 surgical trainees with no prior experience inserting locking screws in intramedullary nails. After a training session using fluoroscopy, participants underwent a pretest using fluoroscopic guidance. Participants were then randomized into either the fluoroscopy or EM group and were further trained using their respective technique. Post, retention, and transfer tests were conducted. Outcomes included task completion, drill attempts, screw changes, and radiation time. Intragroup comparisons revealed that the EM group used significantly less drill attempts during the post and retention tests compared with the pretest (P = 0.016 and P = 0.016, respectively). Intergroup comparisons revealed that the EM group was (1) more likely to complete the task during the retention test (P = 0.043) and (2) had significantly less radiation time during the post and retention tests (P = 0.002 and P = 0.003, respectively). Radiation time in the EM group during the transfer test increased to a level equal to what the fluoroscopy group used during the post and retention tests (P = 0.71 and P = 0.92, respectively). No other significant between-group differences occurred. EM guidance may be safely used to assist in the training of surgical novices in the skill of distal locking screw insertion. Not only does this technology significantly improve the ability to complete the task and decrease radiation use but also it does so without compromising skill acquisition. Therapeutic Level II. See Instructions for Authors for a complete description of levels of evidence.

  20. New entry point for C2 screw, in posterior C1-C2 fixation (Goel-Harm's technique) significantly reducing the possibility of vertebral artery injury.

    PubMed

    Patkar, Sushil Vasant

    2016-02-01

    To reduce the chance of vertebral artery injury in posterior C1 lateral mass and C2 pedicle/pars screw-rod fixation (Goel-Harms technique ). 49 patients, 30 males and 19 females, 12years - 82 years, underwent posterior C1-C2 fixation from February 2007 till June2013. A new entry point for the posterior C2 screw, 3mm below the midpoint of the C1-C2 joint which is directed medially and downwards into the C2 body , probably avoids the vertebral artery. As the screw now bypasses the pedicle/ pars , the chance of injuring the vertebral artery is probably reduced. No case of intra-operative vertebral artery injury. The new technique of C2 screw fixation allows rigid immobilization of the C1-C2 joint without significant risk of vertebral artery injury.

  1. The accuracy of computer-assisted pedicle screw placement in degenerative lumbrosacral spine using single-time, paired point registration alone technique combined with the surgeon's experience.

    PubMed

    Iampreechakul, Prasert; Chongchokdee, Chana; Tirakotai, Wuttipong

    2011-03-01

    Evaluate the accuracy of computer-assisted pedicle screw placement in patients with degenerative lumbrosacral spine using single-time, paired point registration alone technique in combination with the surgeon's experience. A computer-assisted pedicle screw insertion in lumbrosacral spine were performed in 62 consecutive patients (363 screws) using single-time, paired point registration without surface matching. After finding the entry point and trajectory of the pedicle under image guidance, the surgeon then inserted pedicle screws by his experience. Postoperative DynaCT scans were obtained and interpreted by two neuroradiologists. The Kappa statistic was used to measure the degree of interobserver agreement. The screw position was graded as follows: Grade A = entirely within the pedicle; B = medial or lateral pedicle wall breach less than 2 mm; C = medial or lateral pedicle wall breach equal to 2-4 mm; D = medial or lateral wall breach more than 4 mm. Clinical outcomes including a numeric pain score, neurologic symptoms, and complications were reviewed from all charts of patients. Additionally, the registration error, registration time, screwing time, and estimated blood loss were analyzed. A total of the 363 pedicle screws, the first neuroradiologist interpreted grade A in 95.6%, grade B in 4.1% and grade C in 0.3%, while the second neuroradiologist interpreted grade A in 95.3%, grade B in 3.6%, and grade C in 1.1%. There was no incidence of grade D in this present study. No neurologic or vascular injuries occurred from pedicle screw placement. The mean registration error was 1.54 +/- 1.28 (range, 0.9-2.5) mm with the mean time required for the registration process for each patient was 3.64 +/- 1.92 (range, 2-8) minutes. The mean screwing time for each patient was 20.29 +/- 9.44 (range, 13-40) minutes. The mean pain score improved from 6.45 +/- 1.74 points preoperatively to 3.04 +/- 0.82 points postoperatively. In the radiculopathy group, motor power gradually

  2. The Use of On Line Video Projection Techniques in Computer Augmented Lectures.

    ERIC Educational Resources Information Center

    Muller, M. T.; And Others

    A new technique called computer augmented lectures (CAL) now in use at the University of Texas at Austin is discussed in this report. The technique is described as involving the integration of on-line interactive time-sharing computer terminals and theater-size video projectors for large screen display, the goal being to promote student learning…

  3. Free Hand Insertion Technique of S2 Sacral Alar-Iliac Screws for Spino-Pelvic Fixation: Technical Note, Acadaveric Study

    PubMed Central

    Park, Jong-Hwa; Kim, Ki-Jeong; Jahng, Tae-Ahn

    2015-01-01

    A rigid spino-pelvic fixation to anchor long constructs is crucial to maintain the stability of long fusion in spinal deformity surgery. Besides obtaining immediate stability and proper biomechanical strength of constructs, the S2 alar-iliac (S2AI) screws have some more advantages. Four Korean fresh-frozen human cadavers were procured. Free hand S2AI screw placement is performed using anatomic landmarks. The starting point of the S2AI screw is located at the midpoint between the S1 and S2 foramen and 2 mm medial to the lateral sacral crest. Gearshift was advanced from the desired starting point toward the sacro-iliac joint directing approximately 20° angulation caudally in sagittal plane and 30° angulation horizontally in the coronal plane connecting the posterior superior iliac spine (PSIS). We made a S2AI screw trajectory through the cancellous channel using the gearshift. We measured caudal angle in the sagittal plane and horizontal angle in the coronal plane. A total of eight S2AI screws were inserted in four cadavers. All screws inserted into the iliac crest were evaluated by C-arm and naked eye examination by two spine surgeons. Among 8 S2AI screws, all screws were accurately placed (100%). The average caudal angle in the sagittal plane was 17.3±5.4°. The average horizontal angle in the coronal plane connecting the PSIS was 32.0±1.8°. The placement of S2AI screws using the free hand technique without any radiographic guidance appears to an acceptable method of insertion without more radiation or time consuming. PMID:26819698

  4. Horizontal Ridge Augmentation with Piezoelectric Hinge-Assisted Ridge Split Technique in the Atrophic Posterior Mandible

    PubMed Central

    Cha, Min-Sang; Lee, Ji-Hye; Lee, Sang-Woon; Cho, Lee-Ra; Huh, Yoon-Hyuk; Lee, You-Sun

    2014-01-01

    Onlay bone grafting, guided bone regeneration, and alveolar ridge split technique are considered reliable bone augmentation methods on the horizontally atrophic alveolar ridge. Among these techniques, alveolar ridge split procedures are technique-sensitive and difficult to perform in the posterior mandible. This case report describes successful implant placement with the use of piezoelectric hinge-assisted ridge split technique in an atrophic posterior mandible. PMID:27489822

  5. The use of a pedicle screw-cortical screw hybrid system for the surgical treatment of a patient with congenital multilevel spinal non-segmentation defect and spinal column deformity: a technical note.

    PubMed

    Ashayeri, Kimberly; Nasser, Rani; Nakhla, Jonathan; Yassari, Reza

    2016-11-01

    This technical note presents, to the authors' knowledge, the first reported case of a hybrid pedicle-cortical screw system for instrumented fusion in a patient with congenital vertebral column deformity. Cortical screws were navigated using stereotactic guidance to extend a prior non-segmented fusion mass, facilitating instrumentation in a circumstance with completely distorted anatomy. This technique provided a safe trajectory with excellent cortical purchase in an anatomically deformed spine. Cortical screw fixation may serve to be helpful in augmenting pedicle screw fixation and in circumstances in which the bone quality is suboptimal or the pedicles are compromised. Cortical screw fixation is a relatively new technology, but it may prove to be invaluable in providing an adjunct to pedicle screw constructs in anatomically distorted or osteoporotic spines.

  6. "NIMS technique" for minimally invasive spinal fixation using non-fenestrated pedicle screws: A technical note.

    PubMed

    Rajesh, Alugolu; Pelluru, Pavan Kumar; Kumar, Ashish

    2015-01-01

    Case series. To reduce the cost of minimally invasive spinal fixation. Minimally invasive spine (MIS) surgery is an upcoming modality of managing a multitude of spinal pathologies. However, in a resource-limited situations, using fenestrated screws (FSs) may prove very costly for patients with poor affordability. We here in describe the Nizam's Institute of Medical Sciences (NIMS) experience of using routine non-FSs (NFSs) for transpedicular fixation by the minimally invasive way to bridge the economic gap. A total of 7 patients underwent NFS-minimally invasive spine (MIS) surgery. Male to female distribution was 6:1. The average blood loss was 50 ml and the mean operating time was 2 and 1/2 h. All patients were mobilized the very next day after confirming the position of implants on X-ray/computed tomography. All 7 patients are doing well in follow-up with no complaints of a backache or fresh neurological deficits. There was no case with pedicle breach or screw pullout. The average cost of a single level fixation by FS and NFS was ₹1, 30,000/patient and ₹32,000/patient respectively ('2166 and '530, respectively). At the end of 1-year follow-up, we had two cases of screw cap loosening and with a displacement of the rod cranio-caudally in one case which was revised through the same incisions. Transpedicular fixation by using NFS for thoracolumbar spinal pathologies is a cost-effective extension of MIS surgery. This may extend the benefits to a lower socioeconomic group who cannot afford the cost of fenestrated screw (FS).

  7. Explosively driven hypervelocity launcher: Second-stage augmentation techniques

    NASA Technical Reports Server (NTRS)

    Baum, D. W.

    1973-01-01

    The results are described of a continuing study aimed at developing a two-stage explosively driven hypervelocity launcher capable of achieving projectile velocities between 15 and 20 km/sec. The testing and evaluation of a new cylindrical impact technique for collapsing the barrel of two-stage launcher are reported. Previous two-stage launchers have been limited in ultimate performance by incomplete barrel collapse behind the projectile. The cylindrical impact technique explosively collapses a steel tube concentric with and surrounding the barrel of the launcher. The impact of the tube on the barrel produces extremely high stresses which cause the barrel to collapse. The collapse rate can be adjusted by appropriate variation of the explosive charge and tubing parameters. Launcher experiments demonstrated that the technique did achieve complete barrel collapse and form a second-stage piston. However, jetting occurred in the barrel collapse process and was responsible for severe projectile damage.

  8. "Non-filling" procedures for lip augmentation: a systematic review of contemporary techniques and their outcomes.

    PubMed

    Moragas, Joan San Miguel; Vercruysse, Herman Junior; Mommaerts, Maurice Y

    2014-09-01

    Ideal lip augmentation techniques have good longevity, low complication rates, and optimal functional and aesthetic results. No systematic review is currently available regarding the efficacy of lip augmentation techniques. This review will focus only on non-filling procedures for lip augmentation (NFPLAs). Current databases Elsevier Science Direct, PubMed, HighWire Press, Springer Standard Collection, SAGE, DOAJ, Sweetswise, Free E-Journals, Ovid Lippincott Williams & Wilkins, Willey Online Library Journals and Cochrane Plus were scrutinized and relevant article reference sections were studied for additional publications. The search heading sequence used was ("Lip" or "Mouth" or "Perioral" or "Nasolabial") and ("Augmentation" or "Enhancement" or "Surgery" or "Lift" or "V-Y" or "Corner"). Exclusion criteria applied to 6436 initial keyword-search retrievals yielded 12 articles. Eight more articles were retrieved from reference sections, for a total of 18 papers assessed. Only one article made a direct comparison of efficacy between two surgical techniques for lip augmentation, and none directly compared complications associated with different NFPLAs. Although this systematic review revealed a lack of quality data in comparing the efficacy and complications among different NFPLAs, it is important to review and pool the existing studies to better suggest proper treatment to patients. Copyright © 2014 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.

  9. Techniques used by United Kingdom consultant plastic surgeons to select implant size for primary breast augmentation.

    PubMed

    Holmes, W J M; Timmons, M J; Kauser, S

    2015-10-01

    Techniques used to estimate implant size for primary breast augmentation have evolved since the 1970s. Currently no consensus exists on the optimal method to select implant size for primary breast augmentation. In 2013 we asked United Kingdom consultant plastic surgeons who were full members of BAPRAS or BAAPS what was their technique for implant size selection for primary aesthetic breast augmentation. We also asked what was the range of implant sizes they commonly used. The answers to question one were grouped into four categories: experience, measurements, pre-operative external sizers and intra-operative sizers. The response rate was 46% (164/358). Overall, 95% (153/159) of all respondents performed some form of pre-operative assessment, the others relied on "experience" only. The most common technique for pre-operative assessment was by external sizers (74%). Measurements were used by 57% of respondents and 3% used intra-operative sizers only. A combination of measurements and sizers was used by 34% of respondents. The most common measurements were breast base (68%), breast tissue compliance (19%), breast height (15%), and chest diameter (9%). The median implant size commonly used in primary breast augmentation was 300cc. Pre-operative external sizers are the most common technique used by UK consultant plastic surgeons to select implant size for primary breast augmentation. We discuss the above findings in relation to the evolution of pre-operative planning techniques for breast augmentation. Copyright © 2015 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.

  10. [Treatment of mid-distal humeral shaft fractures associated with radial nerve palsysis by minimally invasive screwed nails osteosynthesis technique].

    PubMed

    Zang, Wei; Liu, Yun-feng; Wu, Quan-min

    2009-07-01

    To investigate the surgical treatment of mid-distal humeral shaft fractures associated with radial nerve palsysis with minimal invasive screwed nails osteosynthesis technique. Thirty-six patients treated mid-distal humeral shaft fractures associated with radial nerve palsysis from January 2004 to January 2008. There were 28 males and 8 females whose age ranged from 20- to 58-years-old with an average of 36.5-years-old. Injury reasons: mechanical injury 18 cases, traffic injury 8 cases, accidents injury 10 cases, all cases were closed fracture. According to AO/ASIF classification, type A1 5 cases, type A2 7 cases, type B1 8 cases, type B2 7 cases, type B3 5 cases, type C3 4 cases. The small lateral incision was performed located to the fracture. After exploration of the radial nerve, the fractures were reduced. By acromion small lateral incision, the deltoid was separated. In the posterior macronodular slotted antegrade reamed bored with medullary cavity drill and selected a suitable screwed nail screwed into the medullary cavity distal. Along the slot, the locking pieces were inserted to complete the fixation. The postoperative complication, fracture healing time, radial nerve function recovery time, the motion of shoulder and elbow were recorded. The incision of all cases healed with stage I . The patients were followed up for 9-36 weeks with an average of 18.5 weeks. The X-ray examination showed fractures healing in 12-16 weeks (average of 15.6 weeks). Radial nerve function recovered fully at 12-36 weeks after operation (average of 17.8 weeks). Shoulder abduction is 150 degrees-170 degrees with an average of 160 degrees; elbow motion of activities was 130 degrees-140 degrees with an average of 135 degrees. The ASES method was used to assess the shoulder joint function, 20 cases gained the excellent result, 12 good and 4 poor. And according to HSS method, 36 cases of elbow joint function gained the excellent result. The surgical treatment of mid-distal humeral

  11. Transcrestal maxillary sinus augmentation: Summers' versus a piezoelectric technique--an experimental cadaver study.

    PubMed

    Kühl, S; Kirmeier, R; Platzer, S; Bianco, N; Jakse, N; Payer, M

    2016-01-01

    Sinus floor augmentation using transalveolar techniques is a successful and predictable procedure. The aim of the study was to compare the performance of conventional hand instruments using mallets and osteotomes with that of piezoelectric-hydrodynamic devices for maxillary sinus floor elevation. In 17 undamaged cadaver heads on randomly allocated sites, Schneiderian membrane elevation was carried out transcrestally using piezosurgery and a hydrodynamic device or by conventional hand instrumentation. After simulation of sinus augmentation by the use of a radiopaque impression material, a post-operative CT scan was carried out and volumes were determined. Statistic significant differences between the two methods were evaluated by nonparametric Mann-Whitney U-test with P < 0.05. A mean graft volume of 0.29 ± 0.18 cm(3) (0.07-0.60 cm(3)) was measured for the Summers' technique compared to 0.39 ± 0.32 cm(3) (0.05-1.04 cm(3)) for the Sinus Physiolift(®) technique. There is no statistically significant difference with regard to trauma to the Schneiderian membrane or augmented volume. Both techniques generate expedient augmentation volume in the posterior atrophic maxilla. The piezoelectric technique can be recommended as an alternative tool to graft the floor of human maxillary sinuses. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  12. "Owl" Technique for All-Arthroscopic Augmentation of a Massive or Large Rotator Cuff Tear With Extracellular Matrix Graft.

    PubMed

    Narvani, A Ali; Consigliere, Paolo; Polyzois, Ioannis; Sarkhel, Tanaya; Gupta, Rohit; Levy, Ofer

    2016-08-01

    Despite the vast improvement in techniques and technology for arthroscopic rotator cuff surgery, repairs of massive and large tears remain challenging because they are associated with significantly high failure rates. In recent years, patch augmentation has gained popularity as a technique to decrease these high failure rates. Arthroscopic patch augmentation of rotator cuff repair, however, is technically difficult. The purpose of this report is to describe a simple and reproducible technique for all-arthroscopic extracellular matrix graft augmentation. With this technique, which we refer to as the "owl" technique because the prepared extracellular augment resembles an owl, there are relatively few suture ends involved; therefore, augment introduction is straightforward with a reduced risk of suture ends becoming tangled. In addition, the way in which our augmentation is prepared helps to prevent it from becoming bunched up when being secured.

  13. Augmentation of the Nasal Dorsum Using the Multi-stripped Autologous Cartilage Technique (MACT).

    PubMed

    Liu, Liqiang; Bu, Zhaoyun; Fan, Jincai; Tian, Jia; Gan, Cheng; Yang, Zengjie; Jiao, Hu

    2017-08-03

    Nasal augmentation is a popular modern technique requested by many Asian people.There are two kinds of autologous cartilage used to augment the nose at present: carved as a monobloc or diced into pieces. Each approach has its pros and cons.We performed our surgical technique on a group of 28 patients. Twenty of these patients had had several rhinoplasties performed before referral to our hospital; 8 of these patients had undergone a primary rhinoplasty. bilateral conchal, nasal septum, or rib cartilage were harvested, deep temporal fascia or abdominal muscle fascia to be prepared for packing stripped cartilage were also removed at this time. The cartilage was placed on a plastic cutting board and cut into strips with a transverse section of 1 x 1 mm. Then these strips were packed and covered by fascia to form the grafts.The median follow-up was 23 months (range: 12 to 48 months). Twenty-two patients were satisfied with their augmented noses. Through examinations, biopsies, and MRIs, less resorption was observed with the Multi-stripped Autologous Cartilage Technique (MACT). Junctional step-offs, excessive prominence, and slanting grafts occurred in 3 patients; 2 of whom had revisions.Using multi-striped autologous cartilage grafts is an easier method to perform and could be another alternative technique for augmentative and reconstructive rhinoplasties.

  14. Triple-plane technique for breast augmentation: solving animation deformities.

    PubMed

    Bracaglia, Roberto; Tambasco, Damiano; Gentileschi, Stefano; D'Ettorre, Marco

    2013-08-01

    An unpleasant consequence of subpectoral implant placement is the occurrence of animation deformities during pectoralis muscle contraction. This study aimed to review the results achieved for 524 patients undergoing the triple-plane technique with respect to loss of animation deformities. The evaluation was performed by a group of three plastic surgeons according to the Spear grading system for breast distortion using a 4-point scale. Of the 524 patients evaluated, 351 (67 %) were rated as grade 1 (no distortion), 156 (29.77 %) as grade 2 (mild distortion), 17 (3 %) as grade 3 (moderate distortion), and 0 (0 %) as 4 (severe distortion).The excellent results achieved can be explained by the horizontal sectioning of the major pectoralis muscle at the areola level to the sternal margin. In fact, it determines that superior to sectioning of the muscle, its activity remains normal, with a low degree of dynamic deformities. On the contrary, inferiorly, at the muscular-aponeurotic plane level, no activity is detected, with no resultant animation deformities. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

  15. Lumbo-sacro-pelvic Fixation Using Iliac Screws for the Complex Lumbo-sacral Fractures.

    PubMed

    Rhee, Woo-Tack; You, Seung-Hoon; Jang, Yeon-Gyu; Lee, Sang-Youl

    2007-12-01

    Fractures of lumbo-sacral junction involving bilateral sacral wings are rare. Posterior lumbo-sacral fixation does not always provide with sufficient stability in such cases. Various augmentation techniques including divergent sacral ala screws, S2 pedicle screws and Galveston rods have been reported to improve lumbo-sacral stabilization. Galveston technique using iliac bones would be the best surgical approach especially in patients with bilateral comminuted sacral fractures. However, original Galveston surgery is technically demanding and bending rods into the appropriate alignment is time consuming. We present a patient with unstable lumbo-sacral junction fractures and comminuted U-shaped sacral fractures treated by lumbo-sacro-pelvic fixation using iliac screws and discuss about the advantages of the iliac screws over the rod system of Galveston technique.

  16. Treatment of dystrophic scoliosis in neurofibromatosis Type 1 with one-stage posterior pedicle screw technique.

    PubMed

    Wang, Zhenyu; Fu, Changfeng; Leng, Jiali; Qu, Zhigang; Xu, Feng; Liu, Yi

    2015-04-01

    Corrective surgery for dystrophic scoliosis in neurofibromatosis Type 1 (NF-1) is challenging. There are various surgical methods, all with unsatisfactory outcomes. The purpose of the study was to evaluate the clinical outcomes of the treatment of dystrophic scoliosis in NF-1 with one-stage posterior pedicle screw approach. This is a retrospective clinical study. Sixteen patients with dystrophic scoliosis in NF-1 underwent one-stage posterior surgery with pedicle screw system. We used preoperative and postoperative whole-spine radiographs to determine coronal and sagittal Cobb angles (curve correction); distance between apex vertebra and central sacral vertical line (DAC), pelvic obliquity, and shoulder tilt (coronal balance improvement); and sagittal vertical axis and pelvic tilt angle (sagittal balance improvement). We assessed the fusion rate using fusion segment computed tomography scan. Patients underwent surgery with or without osteotomy according to spinal flexibility. Fusion segment selection method of fusion segments selection which mean fusing from one or two levels proximal to upper end vertebra to one or two levels distal to the lower end vertebra (EV+1 or 2) or stable vertebrae fusion. There were no study-specific conflict of interest-associated biases. The average follow-up time was 40.9 months. Mean scoliosis and kyphosis improved from 83.2° to 27.6° and 58.5° to 26.8°, respectively; at the last follow-up, it was 30.4° and 27.4°, respectively. Mean DAC, pelvic obliquity, and shoulder tilt improved from 53.0 to 23.9, 8.1 to 4.9, and 9.8 to 7.5 mm, respectively. Sagittal vertical axis and pelvic tilt angle improved from -5.8 to 1.6 mm and 17.9° to -5.8°, respectively. During follow-up, mean coronal and sagittal correction losses were 2.8° and 0.7°, respectively. Two EV+1 or 2 patients had decompensation. No pseudoarthrosis was identified. The one-stage posterior pedicle screw approach is safe and effective in the treatment of dystrophic

  17. A Modified Dual-plane Technique Using the Serratus Anterior Fascia in Primary Breast Augmentation

    PubMed Central

    Hwang, Dong Yeon; Park, Sang Hoon

    2017-01-01

    Background: Breast augmentations are commonly performed aesthetic surgical procedures. As the breast is a changeable structure, the ideal location of an implant would be a plane that can adjust to the dynamic changes of the breast. We present a modified dual-plane technique for breast augmentation using the fascia for thin patients. Methods: Between June 2014 and June 2015, 27 patients with small breasts underwent breast augmentation using the modified dual-plane technique. The average age was 29.4 years (range, 20–41 y). The mean body mass index was 18.9 kg/m2 (range, 17.6–20.4 kg/m2). Results: The mean size of the implant was 288.9 ml (range, 255–360 ml) on the right side and 281.6 ml (range, 255–360 ml) on the left side. All the patients returned to daily-life activities within 1 week. There have been no complications during minimum follow-up periods of 18 months. The mean follow-up was 25.6 months (range, 18–36 mo). Conclusions: Visible, palpable implants and rippling after breast augmentation with implants are relatively common problems. Our modified dual-plane technique with the serratus anterior fascia can reduce visible rippling and yields a natural-looking breast, especially in thin patients. PMID:28280660

  18. A Novel Surgical Technique for Augmented Corticotomy-Assisted Orthodontics: Bone Grafting With Periosteum.

    PubMed

    Ma, Zhi-Gui; Yang, Chi; Xie, Qian-Yang; Xi, Qian-Yang; Ye, Zhou-Xi; Ye, Zhou-Xie; Zhang, Shan-Yong; Abdelrehem, Ahmed

    2016-01-01

    To introduce grafting fixed with the periosteum (dumpling technique) as an alternative surgical technique for augmented corticotomy-assisted orthodontics in the lower anterior region and evaluate the preliminary outcomes. Eleven patients (9 women, 2 men; mean age, 21.4 yr) with a thin alveolus or alveolar defect in the lower anterior region by clinical and radiographic examination underwent an augmented corticotomy using the new dumpling technique. Cone-beam computerized tomography was used to evaluate morphologic changes of the lower anterior ridge before treatment (T0) and 1 week (T1) and 6 months (T2) after the bone-augmentation procedure. Repeated-measures analysis of variance with Bonferroni multiple-comparison test was used to compare variables at each time point. No severe postsurgical complications occurred in any patient. The mean alveolar bone thickness of the labial plate increased from T0 to T1 (P < .001) and decreased from T1 to T2 (P < .001). However, compared with T0, there was still a significant increase in horizontal bone thickness at T2 (P < .05). The vertical alveolar bone level increased from T0 to T1 (P < .001) and was maintained from T1 to T2 (P > .05). No significant differences were found in root length of the lower anterior teeth at these 3 time points (P > .05). In this preliminary study, the dumpling technique for augmented corticotomy-assisted surgical orthodontics showed alveolar bone augmentation by increasing the vertical alveolar height and the horizontal bone thickness in the labial aspect of the anterior mandibular area. However, long-term follow-up is necessary. Copyright © 2016 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.

  19. Radiological Evaluation of the Initial Fixation between Cortical Bone Trajectory and Conventional Pedicle Screw Technique for Lumbar Degenerative Spondylolisthesis

    PubMed Central

    Iwatsuki, Koichi; Ohnishi, Yu-Ichiro; Yoshimine, Toshiki

    2016-01-01

    Study Design Retrospective study. Purpose To compare initial fixation using the cortical bone trajectory (CBT) technique versus conventional pedicle screws (PS) in radiographs of postsurgical lumbar degenerative spondylolisthesis. Overview of Literature Few reports have documented the holding strength of CBT technique for spondylolisthesis cases. Methods From October 2009 to June 2014, 21 cases of degenerative spondylolisthesis were surgically treated in our institution. Ten were treated with conventional PS technique and 11 of with CBT technique. Mean lumbar lordosis and percent slippage were evaluated preoperatively, immediately after surgery, and 6 months and 1 year postoperatively using radiographs. We also investigated percent loss of slip reduction. Results There were statistically significant differences between preoperative percent slippage and postoperative slippage in both PS and CBT procedures over 1 year, and both techniques showed good slip reduction. On the other hand, lumbar lordosis did not change significantly in either the PS or CBT groups over 1 year. Conclusions CBT technique showed similarly good initial fixation compared with the PS procedure in the treatment of lumbar degenerative spondylolisthesis. PMID:27114765

  20. A simple infrared-augmented digital photography technique for detection of pupillary abnormalities.

    PubMed

    Shazly, Tarek A; Bonhomme, G R

    2015-03-01

    The purpose of the study was to describe a simple infrared photography technique to aid in the diagnosis and documentation of pupillary abnormalities. An unmodified 12-megapixel "point and shoot" digital camera was used to obtain binocular still photos and videos under different light conditions with near-infrared illuminating frames. The near-infrared light of 850 nm allows the capture of clear pupil images in both dim and bright light conditions. It also allows easy visualization of the pupil despite pigmented irides by augmenting the contrast between the iris and the pupil. The photos and videos obtained illustrated a variety of pupillary abnormalities using the aforementioned technique. This infrared-augmented photography technique supplements medical education, and aids in the more rapid detection, diagnosis, and documentation of a wide spectrum of pupillary abnormalities. Its portability and ease of use with minimal training complements the education of trainees and facilitates the establishment of difficult diagnoses.

  1. A modified minimally invasive technique for intra-articular displaced calcaneal fractures fixed by transverse and axial screws.

    PubMed

    Kapil Mani, K C; Acharya, Parimal; Dirgha Raj, R C; Pangeni, Bandhu Ram; Sigdel, Arun; Marahatta, Suman Babu

    2017-05-13

    The management of displaced, intra-articular calcaneal fracture represents a surgical challenge to even an experienced orthopedic surgeon. Plate osteosynthesis using an extended lateral approach is complicated by soft tissue problems, while those treated by closed reduction and percutaneous pinning cannot address all the intra-articular fragments sufficiently. The objective of our study is to evaluate restoration of subtalar joint and long-term functional outcomes in intra-articular displaced calcaneal fractures treated with transverse subcondral screws through a small incision on lateral aspect of calcaneus and percutaneously placed axial screws through the calcaneal tuberosity. Forty-five intra-articular calcaneal fractures were managed with this minimally invasive technique. Calcaneal height, width, length, Bohler's angle, and Gissane angle were measured preoperatively and last follow-up visit. Functional outcomes were assessed on the basis of American Orthopedic Foot and Ankle Society (AOFAS) ankle/hind foot score. Preoperative calcaneal length, height, width, Bohler's angle, and Gissane angle were improved from 68.62 ± 2.64 to 72.44 ± 2.63 mm, 39.28 ± 2.72 to 32.37 ± 2.65 mm, 47.04 ± 2.56 to 49.55 ± 2.45 mm, 12.66° ± 2.86° to 26.93° ± 2.57°, 123.91° ± 3.13° to 96.06° ± 3.92°, respectively, after surgery with P value <0.001. There were 21 (46.7%) excellent, 17 (37.8%) good, 4 (8.8%) fair, and 3 (6.7%) poor outcomes based on AOFAS ankle/hindfoot scores. Time to unite the fracture was 11.06 ± 1.82 weeks (range 8-16 weeks), and all fractures were united without major complications. Minimally invasive technique through a small incision on lateral aspect of calcaneus gives a moderately good exposure for anatomical restoration of Sander's type II and III calcaneal fractures fixed with both transverse and axial screws under fluoroscopic guidance.

  2. Anterior single odontoid screw placement for type II odontoid fractures: our modified surgical technique and initial results in a cohort study of 15 patients

    PubMed Central

    Munakomi, Sunil; Tamrakar, Karuna; Chaudhary, Pramod Kumar; Bhattarai, Binod

    2016-01-01

    Objective: Anterior odontoid screw fixation for type II odontoid fracture is the ideal management option. However in the context of unavailability of an O-arm or neuro-navigation and poor images from the available C-arm may be an obstacle to ideal trajectory and placement of the odontoid screw. We herein detail  our surgical technique so as to ensure a correct trajectory and subsequent good fusion in Type II odontoid fractures. This may be advantageous  in clinical set ups lacking state of the art facilities.  Methods and Results: In this cohort study we included 15 consecutive patients who underwent anterior odontoid screw placement. We routinely dissect the longus colli to completely visualize the entire width of C3 body. We then perform a median C2-C3 disectomy followed by creating a gutter in the superior end of C3 body. We then guide the Kirchsner (K) wire purchasing adequate anterior cortex of C2. Rest of the procedure follows the similar steps as described for odontoid screw placement. We achieved 100% correct trajectory and screw placement in our study. There were no instances of screw break out, pull out or nonunion. There was one patient mortality following myocardial infarction in our study. Conclusion: Preoperative imaging details, proper patient positioning, meticulous dissection, thorough anatomical knowledge and few added surgical nuances are the cornerstones in ideal odontoid screw placement. This may be pivotal in managing  patients in developing nations having rudimentary neurosurgical set up. PMID:27990259

  3. A minimally invasive technique for percutaneous lumbar facet augmentation: Technical description of a novel device

    PubMed Central

    Smith, Zachary A.; Armin, Sean; Raphael, Dan; Khoo, Larry T.

    2011-01-01

    Background: We describe a new posterior dynamic stabilizing system that can be used to augment the mechanics of the degenerating lumbar segment. The mechanism of this system differs from other previously described surgical techniques that have been designed to augment lumbar biomechanics. The implant and technique we describe is an extension-limiting one, and it is designed to support and cushion the facet complex. Furthermore, it is inserted through an entirely percutaneous technique. The purpose of this technical note is to demonstrate a novel posterior surgical approach for the treatment of lumbar degenerative. Methods: This report describes a novel, percutaneously placed, posterior dynamic stabilization system as an alternative option to treat lumbar degenerative disk disease with and without lumbar spinal stenosis. The system does not require a midline soft-tissue dissection, nor subperiosteal dissection, and is a truly minimally invasive means for posterior augmentation of the functional facet complex. This system can be implanted as a stand-alone procedure or in conjunction with decompression procedures. Results: One-year clinical results in nine individual patients, all treated for degenerative disease of the lower lumbar spine, are presented. Conclusions: This novel technique allows for percutaneous posterior dynamic stabilization of the lumbar facet complex. The use of this procedure may allow a less invasive alternative to traditional approaches to the lumbar spine as well as an alternative to other newly developed posterior dynamic stabilization systems. PMID:22145084

  4. Applied anatomy of screw placement via the posterior arch of the atlas and anatomy-based refinements of the technique.

    PubMed

    Bodon, Gergely; Grimm, Andras; Hirt, Bernhard; Seifarth, Harald; Barsa, Pavel

    2016-10-01

    To present a method of posterior arch and lateral mass screw (PALMS) insertion and to prove its feasibility. Four formalin-fixed specimens and 40 macerated atlas vertebras were used to describe the relevant anatomy. The height of the posterior arch was measured on 42 consecutive patients using standard CT of the cervical spine. The operative technique and the special CT reconstructions used for preoperative planning are described. Eight patients underwent posterior fixation using this technique. We described the relevant anatomy and important anatomical landmarks of the posterior arch of the atlas. PALMS placement was modified according to these anatomical findings. Fifteen PALMSs were placed in eight patients using this technique without vascular or neural injury. It is feasible to place PALMS using the described technique. CT angiography is of crucial importance for preoperative planning using the described special reconstructions. The arch posterior to the lateral mass (APLM) is defined as the bone stock situated posterior to the lateral mass, respecting its convergence. The ideal entry point for a PALMS is on the APLM above the center of the converging lateral mass. A complete or incomplete ponticulus posticus and a retrotransverse foramen or groove can be used as an accessory landmark to refine the entry point.

  5. Use of the anatomic trajectory for thoracic pedicle screw salvage after failure/violation using the straight-forward technique: a biomechanical analysis.

    PubMed

    Lehman, Ronald A; Kuklo, Timothy R

    2003-09-15

    A biomechanical study of cadaver vertebrae to determine the feasibility of obtaining adequate thoracic pedicle screw fixation in a salvage situation. OBJECTIVE To investigate the ability to safely place a thoracic pedicle screw with adequate maximal insertional torque (MIT) using the anatomic trajectory (AT) (directed along the true anatomic axis of the pedicle) after purposeful failure/medial violation of the pedicle using the straight-forward trajectory (ST) (paralleling the vertebral endplate). Failure to place a pedicle screw at an intended segment of the thoracic spine may theoretically render the level uninstrumented, because pedicle hook placement may be unsafe and the transverse process may be fractured. An alternative pedicle screw insertion technique, if biomechanically sound in this situation, may present an excellent alternative for critical instrumentation levels. Fixed-head 5.0 mm stainless steel pedicle screws were placed using the ST and MIT was recorded after determination of bone mineral density (BMD) with dual-energy radiograph absorptiometry (DEXA) scanning. Purposeful screw malposition and critical pedicle wall failure were performed, followed by salvage placement of the screw using the AT. Insertional torque was recorded for each screw revolution with a digital torque wrench and MIT was again recorded to compare the MIT obtainable in the salvage situation. BMD for the vertebrae averaged 732 g/cm2 (620-884 g/cm2). The MIT for the straight-forward technique without pedicle violation was 2.61 +/- 0.19 (SE) inches per pound, whereas that of the salvage procedure after medial wall violation (AT) averaged 1.62 +/- 0.12 (SE) inches per pound. Therefore, the AT achieved 62% (P = 0.027) of the fixation strength (in terms of MIT) during salvage after failure/medial violation of the pedicle. MIT for both the ST* and AT trajectories correlated with both global BMD of the vertebrae (*P = 0.008; P = 0.004) and regional BMD of the vertebral body (*P = 0

  6. Assessment of the stress transmitted to dental implants connected to screw-retained bars using different casting techniques.

    PubMed

    Haselhuhn, Klaus; Marotti, Juliana; Tortamano, Pedro; Weiss, Claudia; Suleiman, Lubna; Wolfart, Stefan

    2014-12-01

    Passive fit of the prosthetic superstructure is important to avoid complications; however, evaluation of passive fit is not possible using conventional procedures. Thus, the aim of this study was to check and locate mechanical stress in bar restorations fabricated using two casting techniques. Fifteen patients received four implants in the interforaminal region of the mandible, and a bar was fabricated using either the cast-on abutment or lost-wax casting technique. The fit accuracy was checked according to the Sheffield's test criteria. Measurements were recorded on the master model with a gap-free, passive fit using foil strain gauges both before and after tightening the prosthetic screws. Data acquisition and processing was analyzed with computer software and submitted to statistical analysis (ANOVA). The greatest axial distortion was at position 42 with the cast-on abutment technique, with a mean distortion of 450 μm/m. The lowest axial distortion occurred at position 44 with the lost-wax casting technique, with a mean distortion of 100 μm/m. The minimal differences between the means of axial distortion do not indicate any significant differences between the techniques (P = 0.2076). Analysis of the sensor axial distortion in relation to the implant position produced a significant difference (P < 0.0001). Significantly higher measurements were recorded in the axial distortion analysis of the distal sensors of implants at the 34 and 44 regions than on the mesial positions at the 32 and 42 regions (P = 0.0481). The measuring technique recorded axial distortion in the implant-supported superstructures. Distortions were present at both casting techniques, with no significant difference between the sides.

  7. Odontoid plate fixation without C1-C2 arthrodesis: biomechanical testing of a novel surgical technique and comparison to the conventional screw fixation procedure.

    PubMed

    Platzer, Patrick; Eipeldauer, Stefan; Vécsei, Vilmos

    2010-08-01

    Odontoid plate fixation without C1-C2 arthrodesis appears to be a practicable option for the management of odontoid fractures that are not amenable for conventional screw fixation. The purpose of this study was to measure the mechanical stability of odontoid plate fixation using a specially designed plate construct, and to compare the results to those after conventional screw fixation. The second cervical vertebra was removed from twenty fresh human spinal columns. Stiffness and failure load of the intact odontoid were measured, and type II odontoid fractures were created. Afterward, the specimens were randomly assigned to one of the following four groups: Group I: plate-fixation; Group II: 2-AO-screw-fixation; Group III: 1-AO-screw-fixation; Group IV: Herbert-screw-fixation. In a second series, stiffness and failure load of the stabilized odontoid fractures were assessed for comparison and statistical analysis. Group I showed a significantly higher mean failure load than the other groups. The mean failure load of Group I after fixation of the odontoid fracture was 86% of the mean failure load of the intact odontoid. Comparing Groups II, III and IV, there was no significant difference regarding the failure load. In these three groups the mean failure load after odontoid fixation was approximately 50% of the mean failure load of the intact odontoid. Odontoid plate fixation as an alternative procedure in certain fracture patterns provided a significantly higher biomechanical stability than the technique of odontoid screw fixation. Using a specially designed plate construct, 86% of the original stability of the intact odontoid was restored. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

  8. Safety screw fixation technique in a case of coracoid base fracture with acromioclavicular dislocation and coracoid base cross-sectional size data from a computed axial tomography study.

    PubMed

    Kawasaki, Yoshiteru; Hirano, Tetsuya; Miyatake, Katsutoshi; Fujii, Koji; Takeda, Yoshitsugu

    2014-07-01

    Coracoid base fracture accompanied by acromioclavicular joint dislocation with intact coracoclavicular ligaments is a rare injury. Generally, an open reduction with screw fixation is the first treatment choice, as it protects the important structures around the coracoid process. This report presents a new technique of screw fixation for coracoid base fracture and provides anatomic information on cross-sectional size of the coracoid base obtained by computed tomography (CT). An axial image of the coracoid base was visualized over the neck of the scapula, and a guidewire was inserted into this circle under fluoroscopic guidance. The wire was inserted easily into the neck of scapula across the coracoid base fracture with imaging in only 1 plane. In addition, 25 measurements of the coracoid base were made in 25 subjects on axial CT images. Average length of the long and short axes at the thinnest part of the coracoid base was 13.9 ± 2.0 mm (range 10.6-17.0) and 10.5 ± 2.2 mm (6.6-15.1), respectively. This new screw fixation technique and measurement data on the coracoid base may be beneficial for safety screw fixation of coracoid base fracture.

  9. Vertical ridge augmentation using the modified shell technique--a case series.

    PubMed

    Stimmelmayr, Michael; Beuer, Florian; Schlee, Markus; Edelhoff, Daniel; Güth, Jan-Frederik

    2014-12-01

    Vertical defects of the alveolar crest often restrict the placement of implants. The outcome of vertical augmentation is unpredictable so we aimed to develop a technique that has predictable results. We used autogenous grafts trimmed to shells less than 1mm thick to rebuild the vertical dimensions of the alveolar ridge. The shells were fixed with microscrews and the vertical space between the shell and the residual bone was filled with autogenous particulate bone. Vertical dimensions before and after augmentation were measured and descriptive statistics calculated. A total of 17 patients (10 female, 7 male, mean (SD) age 46 (17) years) had 18 sites augmented (2 sites in one patient). In 2 cases the wound dehisced and healing was by secondary intention. The rest healed uneventfully. The mean (SD) vertical defect was 4.7 (1.4) mm and mean (SD) resorption during consolidation was 0.5 (0.7) mm. All 30 previously planned implants were placed, and none failed during the first year. Loading was monitored for a mean (SD) period of 14.6 (10.5) months. The technique showed promising results and could be an alternative to procedures that use extraoral donor sites. Copyright © 2014 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

  10. The nasal lift technique for augmentation of the maxillary ridge: technical note.

    PubMed

    Camargo, Igor Batista; Oliveira, David M; Fernandes, André Vajgel; Van Sickels, Joseph E

    2015-10-01

    Placement of dental implants in a severely resorbed anterior maxillary alveolar ridge is limited by the fact that implants may penetrate the nasal cavity. However, when the maxilla shows unusual anatomical changes, reconstruction with implants can be a challenge. Options to increase the bone in this region to permit placement of implants include: maxillary onlay bone graft, Le Fort I interpositional bone graft, and augmentation of the nasal floor, which is a procedure where only the piriform rim and the anterior nasal spine are exposed through an intraoral approach. In our case we modified this to what we call the nasal lift technique, which is a combination of turbinectomy followed by lifting of the anteroposterior nasal floor through a lateral window using autogenous bone or bone substitutes to augment the space. Copyright © 2015 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

  11. Graftless sinus augmentation technique with contextual placement of implants: a case report.

    PubMed

    Chipaila, Nicolae; Marini, Roberta; Sfasciotti, Gian Luca; Cielo, Alessandro; Bonanome, Laura; Monaco, Annalisa

    2014-12-17

    The positioning of implants in the jaw bones with contextual graftless lateral approach sinus lifting is finding an increasingly broad consensus in the literature. Since the 1970s, various clinical research projects have been conducted on applications of biological and synthetic biomaterials in bone regenerative surgery, both in sinus lift procedures and in cystic cavity filling after cystectomy or in bone defects in regenerative periodontal surgery. Currently, we are finding that there is an increasing trend of clinicians aiming to adopt graftless techniques, with satisfactory results in terms of implant survival in the long term. In our study, through a case report, we describe a variant of graftless sinus augmentation technique with contextual implant placement, emphasizing the role of the blood clot, combined with collagen sponges, as a natural scaffold and the osteogenic potential of the subantral membrane in guided bone regeneration, with reduced morbidity of the patient. To describe the surgical technique, the clinical case of a 38-year-old Caucasian woman with a lateral posterior edentulism was selected. The rehabilitation was solved by a graftless sinus augmentation technique with a contextual implant placement. For each implant, a resonance frequency analysis evaluation was reported as implant stability quotient values. The performance of the implant stability quotient values followed a gradual increase from time zero to the sixth month, as the clot was differentiated into osteoid tissue and then into bone tissue, due to the scaffold effect conferred by the equine collagen sponge. The stabilization phase took place between the fourth and the sixth month, according to the implant stability quotient values. Our graftless sinus augmentation technique seems to be very predictable thanks to the osteoconductive principles on which it is based, and in association with the proper management of peri-implant soft tissue, so as to increase the amount of keratinized

  12. Augmented reality-guided neurosurgery: accuracy and intraoperative application of an image projection technique.

    PubMed

    Besharati Tabrizi, Leila; Mahvash, Mehran

    2015-07-01

    An augmented reality system has been developed for image-guided neurosurgery to project images with regions of interest onto the patient's head, skull, or brain surface in real time. The aim of this study was to evaluate system accuracy and to perform the first intraoperative application. Images of segmented brain tumors in different localizations and sizes were created in 10 cases and were projected to a head phantom using a video projector. Registration was performed using 5 fiducial markers. After each registration, the distance of the 5 fiducial markers from the visualized tumor borders was measured on the virtual image and on the phantom. The difference was considered a projection error. Moreover, the image projection technique was intraoperatively applied in 5 patients and was compared with a standard navigation system. Augmented reality visualization of the tumors succeeded in all cases. The mean time for registration was 3.8 minutes (range 2-7 minutes). The mean projection error was 0.8 ± 0.25 mm. There were no significant differences in accuracy according to the localization and size of the tumor. Clinical feasibility and reliability of the augmented reality system could be proved intraoperatively in 5 patients (projection error 1.2 ± 0.54 mm). The augmented reality system is accurate and reliable for the intraoperative projection of images to the head, skull, and brain surface. The ergonomic advantage of this technique improves the planning of neurosurgical procedures and enables the surgeon to use direct visualization for image-guided neurosurgery.

  13. Accuracy of pedicle screw insertion in posterior scoliosis surgery: a comparison between intraoperative navigation and preoperative navigation techniques.

    PubMed

    Zhang, Wei; Takigawa, Tomoyuki; Wu, YongGang; Sugimoto, Yoshihisa; Tanaka, Masato; Ozaki, Toshifumi

    2017-06-01

    This study was conducted to compare the efficacy and accuracy of intraoperative navigation (O-arm or Arcadis navigation) and preoperative CT-based navigation in adolescent idiopathic scoliosis (AIS) surgery. Sixty-seven patients with scoliosis were grouped according to the method of navigation used in their fixation surgeries. A total of 492 pedicle screws were implanted in 27 patients using intraoperative navigation, and 626 screws were implanted in 40 patients using preoperative navigation. We analyzed the postoperative CT images for pedicle violations using the Gertzbein classification. There was no statistical difference in the accuracy of pedicle screw placement between two groups. However, in the apical region (the apex ± 2 vertebrae), the accuracy of safe pedicle screw placement (grades 0, 1) was significantly higher in the intraoperative navigation group than in the preoperative navigation group (94.8 vs 89.2%, respectively; P = 0.035). Intraoperative navigation significantly diminished medial perforation compared to preoperative navigation (P = 0.027), and the number of screws per vertebra that could be placed in the apical region was significantly higher in intraoperative navigation group (P < 0.001). In addition, the time required for the registration procedure and insertion of one pedicle screw was 11.3 ± 2.1 min in the preoperative group, but significantly decreased to 5.1 ± 1.1 min in the intraoperative group (P < 0.001). Both preoperative CT-based and intraoperative navigation systems provide sufficient accuracy and safety in pedicle screw insertion for AIS surgery. Intraoperative navigation systems facilitate pedicle screw insertion in the apical region and reduce registration time during AIS surgery which improves the efficacy and accuracy of pedicle screw insertion.

  14. Bone Replacement Materials and Techniques Used for Achieving Vertical Alveolar Bone Augmentation

    PubMed Central

    Sheikh, Zeeshan; Sima, Corneliu; Glogauer, Michael

    2015-01-01

    Alveolar bone augmentation in vertical dimension remains the holy grail of periodontal tissue engineering. Successful dental implant placement for restoration of edentulous sites depends on the quality and quantity of alveolar bone available in all spatial dimensions. There are several surgical techniques used alone or in combination with natural or synthetic graft materials to achieve vertical alveolar bone augmentation. While continuously improving surgical techniques combined with the use of auto- or allografts provide the most predictable clinical outcomes, their success often depends on the status of recipient tissues. The morbidity associated with donor sites for auto-grafts makes these techniques less appealing to both patients and clinicians. New developments in material sciences offer a range of synthetic replacements for natural grafts to address the shortcoming of a second surgical site and relatively high resorption rates. This narrative review focuses on existing techniques, natural tissues and synthetic biomaterials commonly used to achieve vertical bone height gain in order to successfully restore edentulous ridges with implant-supported prostheses.

  15. Shoulder balance after surgery in patients with Lenke Type 2 scoliosis corrected with the segmental pedicle screw technique.

    PubMed

    Li, Ming; Gu, Suxi; Ni, Jianqiang; Fang, Xiutong; Zhu, Xiaodong; Zhang, Zhiyu

    2009-03-01

    The authors evaluated the effectiveness of Lenke Type 2 criteria in scoliosis correction with the segmental pedicle screw (PS) technique, with emphasis on shoulder balance. Twenty-five consecutive patients with Lenke Type 2 scoliosis (structural double thoracic curves, sidebending Cobb angle > 25 degrees , or T2-5 kyphosis > 20 degrees ) who underwent segmental PS instrumentation were included in this study. At surgery, the patients were an average of 14.1 years of age, and the average duration of follow-up was 2.9 years. For radiological evaluation of the patients, preoperative, postoperative, and the latest available follow-up radiographs were used. The difference between right and left shoulder heights was determined to assess shoulder balance. All patients were treated with fusion of both the proximal and distal curves. The mean preoperative proximal thoracic curve of 43 degrees was corrected to 21 degrees postoperatively, a 51.2% correction. The preoperative lower thoracic curve of 61 degrees was corrected to 23 degrees , for a 62.3% correction. The preoperative shoulder height difference of -5.92 +/- 12.52 mm (range: -31 to +14 mm, negative designating a lower left shoulder) was improved to 1.52 +/- 8.12 mm. Postoperatively, no patient had significant or moderate shoulder imbalance, 4 patients had minimal shoulder imbalance, and 21 patients had balanced shoulders. Although Lenke Type 2 criteria were developed wth Cotrel-Dubousset instrumentation, they are successfully applied to determining thoracic fusion when segmental PS instrumentation is used.

  16. [Easy and reproducible technique to address tricuspid valve regurgitation with patch augmentation.

    PubMed

    Solinas, Marco; Bianchi, Giacomo; Glauber, Mattia

    2013-11-01

    We describe a patch augmentation of the anterior leaflet of the tricuspid valve to address tricuspid valve regurgitation due to leaflet retraction. The area of the anterior leaflet is measured using a tricuspid valve annuloplasty sizer; a glutaraldehyde-fixed autologous pericardial patch is trimmed with slight 5 mm oversize. The anterior leaflet is detached and the patch is sutured with three 5/0 running interlocked sutures, then an annuloplasty is performed with an undersized ring. This technique offers an easy and reproducible tool to address tricuspid regurgitation due to lack of leaflet coaptation.

  17. An effective visualization technique for depth perception in augmented reality-based surgical navigation.

    PubMed

    Choi, Hyunseok; Cho, Byunghyun; Masamune, Ken; Hashizume, Makoto; Hong, Jaesung

    2016-03-01

    Depth perception is a major issue in augmented reality (AR)-based surgical navigation. We propose an AR and virtual reality (VR) switchable visualization system with distance information, and evaluate its performance in a surgical navigation set-up. To improve depth perception, seamless switching from AR to VR was implemented. In addition, the minimum distance between the tip of the surgical tool and the nearest organ was provided in real time. To evaluate the proposed techniques, five physicians and 20 non-medical volunteers participated in experiments. Targeting error, time taken, and numbers of collisions were measured in simulation experiments. There was a statistically significant difference between a simple AR technique and the proposed technique. We confirmed that depth perception in AR could be improved by the proposed seamless switching between AR and VR, and providing an indication of the minimum distance also facilitated the surgical tasks. Copyright © 2015 John Wiley & Sons, Ltd.

  18. A Novel Technique for Immediate Loading Single Root Form Implants With an Interim CAD/CAM Milled Screw-Retained Crown.

    PubMed

    Proussaefs, Periklis

    2016-08-01

    A technique is described where an interim abutment and crown are fabricated in the laboratory by utilizing computer-aided design/computer-aided manufacturing (CAD/CAM) technology and placed the day of dental implant surgery. The design and contours of the interim crown are designed by the computer software to be identical to the contours of the tentatively designed definitive prosthesis. The interim crown satisfies esthetics immediately after dental implant surgery while allowing the tissue to heal and obtain contours similar to the contours of the definitive prosthesis. The interim crown can be either cement retained or screw retained. The presented technique describes fabrication of a screw-retentive interim crown. After osseointegration is confirmed, a definitive impression is made with a CAD/CAM impression coping. The definitive prosthesis is then fabricated.

  19. Percutaneous antegrade scaphoid screw placement: a feasibility and accuracy analysis of a novel electromagnetic navigation technique versus a standard fluoroscopic method.

    PubMed

    Hoffmann, M; Reinsch, O D; Petersen, J P; Schröder, M; Priemel, M; Spiro, A S; Rueger, J M; Yarar, S

    2015-03-01

    Central screw positioning in the scaphoid provides biomechanical advantages. A prospective randomized study of six fluoroscopically guided and six electromagnetically navigated screw (ENS) placements was performed on human cadavers. Accuracy of screw position was determined. Intraoperative fluoroscopy exposure times, readjustments of drilling directions, complete restarts and complications were documented. The ENS method provided a mean time benefit of 7.34 min compared with the standard method and the mean screw length ratio (SLR coronar: ENS 0.96 ± 0.04 mm, SFF: 0.92 ± 0.04 mm, P = 0.065; SLR sagittal: ENS 0.98 ± 0.02 mm, SFF: 0.91 ± 0.04 mm, P = 0.009) and the screw axis deviation angle (AD coronar: ENS 3.33 ± 2.34°, SFF: 10.33 ± 2.58°, P = 0.002; AD sagittal: ENS 2.83 ± 0.98°, SFF: 11.00 ± 6.16°, P = 0.002) were lower. Using the electromagnetic navigation procedure no drilling readjustments or restarts were required, no cortical breach occurred. Compared with the standard fluoroscopic technique, the ENS method used in this study showed higher accuracy, less complications, required less operation and radiation exposure time. Copyright © 2014 John Wiley & Sons, Ltd.

  20. Four lateral mass screw fixation techniques in lower cervical spine following laminectomy: a finite element analysis study of stress distribution.

    PubMed

    Song, Mingzhi; Zhang, Zhen; Lu, Ming; Zong, Junwei; Dong, Chao; Ma, Kai; Wang, Shouyu

    2014-08-09

    Lateral mass screw fixation (LSF) techniques have been widely used for reconstructing and stabilizing the cervical spine; however, complications may result depending on the choice of surgeon. There are only a few reports related to LSF applications, even though fracture fixation has become a severe complication. This study establishes the three-dimensional finite element model of the lower cervical spine, and compares the stress distribution of the four LSF techniques (Magerl, Roy-Camille, Anderson, and An), following laminectomy -- to explore the risks of rupture after fixation. CT scans were performed on a healthy adult female volunteer, and Digital imaging and communication in medicine (Dicom) data was obtained. Mimics 10.01, Geomagic Studio 12.0, Solidworks 2012, HyperMesh 10.1 and Abaqus 6.12 software programs were used to establish the intact model of the lower cervical spines (C3-C7), a postoperative model after laminectomy, and a reconstructive model after applying the LSF techniques. A compressive preload of 74 N combined with a pure moment of 1.8 Nm was applied to the intact and reconstructive model, simulating normal flexion, extension, lateral bending, and axial rotation. The stress distribution of the four LSF techniques was compared by analyzing the maximum von Mises stress. The three-dimensional finite element model of the intact C3-C7 vertebrae was successfully established. This model consists of 503,911 elements and 93,390 nodes. During flexion, extension, lateral bending, and axial rotation modes, the intact model's angular intersegmental range of motion was in good agreement with the results reported from the literature. The postoperative model after the three-segment laminectomy and the reconstructive model after applying the four LSF techniques were established based on the validated intact model. The stress distribution for the Magerl and Roy-Camille groups were more dispersive, and the maximum von Mises stress levels were lower than the other

  1. Four lateral mass screw fixation techniques in lower cervical spine following laminectomy: a finite element analysis study of stress distribution

    PubMed Central

    2014-01-01

    Background Lateral mass screw fixation (LSF) techniques have been widely used for reconstructing and stabilizing the cervical spine; however, complications may result depending on the choice of surgeon. There are only a few reports related to LSF applications, even though fracture fixation has become a severe complication. This study establishes the three-dimensional finite element model of the lower cervical spine, and compares the stress distribution of the four LSF techniques (Magerl, Roy-Camille, Anderson, and An), following laminectomy -- to explore the risks of rupture after fixation. Method CT scans were performed on a healthy adult female volunteer, and Digital imaging and communication in medicine (Dicom) data was obtained. Mimics 10.01, Geomagic Studio 12.0, Solidworks 2012, HyperMesh 10.1 and Abaqus 6.12 software programs were used to establish the intact model of the lower cervical spines (C3-C7), a postoperative model after laminectomy, and a reconstructive model after applying the LSF techniques. A compressive preload of 74 N combined with a pure moment of 1.8 Nm was applied to the intact and reconstructive model, simulating normal flexion, extension, lateral bending, and axial rotation. The stress distribution of the four LSF techniques was compared by analyzing the maximum von Mises stress. Result The three-dimensional finite element model of the intact C3-C7 vertebrae was successfully established. This model consists of 503,911 elements and 93,390 nodes. During flexion, extension, lateral bending, and axial rotation modes, the intact model’s angular intersegmental range of motion was in good agreement with the results reported from the literature. The postoperative model after the three-segment laminectomy and the reconstructive model after applying the four LSF techniques were established based on the validated intact model. The stress distribution for the Magerl and Roy-Camille groups were more dispersive, and the maximum von Mises stress

  2. Cough augmentation techniques for extubation or weaning critically ill patients from mechanical ventilation.

    PubMed

    Rose, Louise; Adhikari, Neill Kj; Leasa, David; Fergusson, Dean A; McKim, Douglas

    2017-01-11

    There are various reasons why weaning and extubation failure occur, but ineffective cough and secretion retention can play a significant role. Cough augmentation techniques, such as lung volume recruitment or manually- and mechanically-assisted cough, are used to prevent and manage respiratory complications associated with chronic conditions, particularly neuromuscular disease, and may improve short- and long-term outcomes for people with acute respiratory failure. However, the role of cough augmentation to facilitate extubation and prevent post-extubation respiratory failure is unclear. Our primary objective was to determine extubation success using cough augmentation techniques compared to no cough augmentation for critically-ill adults and children with acute respiratory failure admitted to a high-intensity care setting capable of managing mechanically-ventilated people (such as an intensive care unit, specialized weaning centre, respiratory intermediate care unit, or high-dependency unit).Secondary objectives were to determine the effect of cough augmentation techniques on reintubation, weaning success, mechanical ventilation and weaning duration, length of stay (high-intensity care setting and hospital), pneumonia, tracheostomy placement and tracheostomy decannulation, and mortality (high-intensity care setting, hospital, and after hospital discharge). We evaluated harms associated with use of cough augmentation techniques when applied via an artificial airway (or non-invasive mask once extubated/decannulated), including haemodynamic compromise, arrhythmias, pneumothorax, haemoptysis, and mucus plugging requiring airway change and the type of person (such as those with neuromuscular disorders or weakness and spinal cord injury) for whom these techniques may be efficacious. We searched the Cochrane Central Register of Controlled Trials (CENTRAL; Issue 4, 2016), MEDLINE (OvidSP) (1946 to April 2016), Embase (OvidSP) (1980 to April 2016), CINAHL (EBSCOhost) (1982

  3. Increasing pullout strength of suture anchors in osteoporotic bone using augmentation--a cadaver study.

    PubMed

    Braunstein, Volker; Ockert, Ben; Windolf, Markus; Sprecher, Christoph M; Mutschler, Wolf; Imhoff, Andreas; Postl, Lukas Karl Leo; Biberthaler, Peter; Kirchhoff, Chlodwig

    2015-03-01

    Rotator cuff tears are of increasing clinical impact in the physically active elderly patients. Recent research revealed, that a high percentage of these patients present with significant loss of bone mineral density at the insertion site of the rotator cuff, thereby compromising suture anchorage for operative repair. We therefore hypothesized that augmentation of suture anchors improves biomechanical properties in low bone quality. 28 osteoporotic humeral heads were included in this biomechanical study. Bone quality at the anchor insertion sites (group 1: posterior-medial; group 2: anterior-lateral) within the greater tuberosity was analyzed using HR-pQCT (voxel size: 82μm). Anchor positions of identical quality were then randomized to either conventional screw anchorage or polymethylmethacrylat augmented screw anchorage. All anchors were cyclically ramp-loaded until pullout. Pullout strength accounted for 226N in group I for conventional anchorage and for 332N in augmented technique. In group 2 (anterior-lateral) the pullout strength was 209N (conventional) and 304N (augmented). Pull-out strength of augmented screw anchors was significantly higher in both groups (p<0.05). Compared to conventional insertion techniques, the cement augmentation technique increases the pullout strength of suture anchors in low bone quality significantly. Cement augmentation could therefore be a helpful tool for improved suture anchor stability, especially in locations of low bone quality. Copyright © 2015 Elsevier Ltd. All rights reserved.

  4. Cough Augmentation Techniques in the Critically Ill: A Canadian National Survey.

    PubMed

    Rose, Louise; Adhikari, Neill K; Poon, Joseph; Leasa, David; McKim, Douglas A

    2016-10-01

    Critically ill mechanically ventilated patients experience impaired airway clearance due to ineffective cough and impaired secretion mobilization. Cough augmentation techniques, including mechanical insufflation-exsufflation (MI-E), manually assisted cough, and lung volume recruitment, improve cough efficiency. Our objective was to describe use, indications, contraindications, interfaces, settings, complications, and barriers to use across Canada. An e-mail survey was sent to nominated local survey champions in eligible Canadian units (ICUs, weaning centers, and intermediate care units) with 4 telephone/e-mail reminders. The survey response rate was 157 of 238 (66%); 78 of 157 units (50%) used cough augmentation, with 50 (64%) using MI-E, 53 (68%) using manually assisted cough, and 62 (79%) using lung volume recruitment. Secretion clearance was the most common indication (MI-E, 92%; manually assisted cough, 88%; lung volume recruitment, 76%), although the most common units (44%) used it <50% of the time. Use during weaning from invasive (MI-E, 21%; manually assisted cough, 39%; lung volume recruitment, 3%) and noninvasive ventilation (MI-E, 21%; manually assisted cough, 33%; lung volume recruitment, 21%) was infrequent. The most common diagnoses were neuromuscular disease (97%) and spinal cord injury (83%). Pneumothorax was the most frequently identified absolute contraindication for MI-E (93%) and lung volume recruitment (83%); rib fracture was most frequently identified for manually assisted cough (69%). MI-E mean inspiratory pressure was 31 cm H2O, and expiratory pressure was -32 cm H2O. Mucus plugging requiring tracheostomy inner change was the most frequent complication for MI-E (23%), chest pain for manually assisted cough (36%), and hypotension for lung volume recruitment (17%). The most commonly cited barriers were lack of expertise (70%), knowledge (65%), and resources (52%). We found moderate adoption of cough augmentation techniques, particularly for

  5. Soft tissue repair for tibialis anterior tendon ruptures using plate and screw fixation technique in combination with anterolateral thigh flaps transplantation.

    PubMed

    Mao, Haijun; Xu, Guanyue

    2015-09-17

    Traumatic ruptures of the tibialis anterior tendon are rare but can cause substantial functional deficiencies. This study aimed to evaluate the feasibility of a surgery for soft tissue repair of traumatic rupture of the tibialis anterior tendon by using a plate and screw fixation repair in combination with the free anterolateral thigh flaps transplantation. Eight consecutive patients with anterior tibialis tendon ruptures who visited orthopedics departments from February 2008 to February 2012 were included in our study. The ruptured tendon was reconstructed with plate and screw fixation technique, and the tissue defects were repaired with anterolateral thigh free flaps. The complications and American Orthopedic Foot and Ankle Society (AOFAS) ankle-hindfoot scores were evaluated. Postoperative manual strength test was performed using a 0 to 5 scale. All flaps survived without any complications. The average preoperative and postoperative AOFAS ankle-hindfoot scores of the patients were 51 and 95, respectively. Good ankle dorsiflexion strength against strong resistance was observed in eight ankles postoperatively (manual strength of one patient was 4/5, the others were 5/5), and a substantial improvement in strength was noted compared with the preoperative examination. Soft tissue repair for tibialis anterior tendon rupture using plate and screw fixation technique in combination with anterolateral thigh flaps transplantation is a feasible technique and yield satisfactory results.

  6. Comparison of Surgical Outcomes Between Short-Segment Open and Percutaneous Pedicle Screw Fixation Techniques for Thoracolumbar Fractures

    PubMed Central

    Fu, Zhiguo; Zhang, Xi; Shi, Yaohua; Dong, Qirong

    2016-01-01

    Background This study aimed to compare the surgical outcomes between open pedicle screw fixation (OPSF) and percutaneous pedicle screw fixation (PPSF) for the treatment of thoracolumbar fractures, which has received scant research attention to date. Material/Methods Eight-four patients with acute and subacute thoracolumbar fractures who were treated with SSPSF from January 2013 to June 2014 at the Changzhou Hospital of Traditional Chinese Medicine (Changzhou, China) were retrospectively reviewed. The patients were divided into 4 groups: the OPSF with 4 basic screws (OPSF-4) group, the OPSF with 4 basic and 2 additional screws (OPSF-6) group, the PPSF with 4 basic screws (PPSF-4) group, and the PPSF with 4 basic and 2 additional screws (PPSF-6) group. The intraoperative, immediate postoperative, and over 1-year follow-up outcomes were evaluated and compared among these groups. Results Blood loss in the PPSF-4 group and the PPSF-6 group was significantly less than in the OPSF-4 group and the OPSF-6 group (P<0.05). The OPSF-6 group exhibited significantly higher immediate postoperative correction percentage of anterior column height of fractured vertebra than the other 3 groups (P<0.05), and higher correction of sagittal regional Cobb angle and kyphotic angle of injured vertebra than in the PPSF-4 and -6 groups (P<0.05). In addition, there was no significant difference in the correction loss of percentage of anterior column height, and loss of sagittal Cobb angle and kyphotic angle of fractured vertebrae at final follow-up among the 4 groups (P>0.05). Conclusions OPSF with 6 screws had an advantage in the correction of injured vertebral height and kyphosis, and PPSF reduced the intraoperative blood loss of patients. PMID:27602557

  7. Anatomical evaluation of the groove for the vertebral artery in the axis vertebrae for atlanto-axial transarticular screw fixation technique.

    PubMed

    Kazan, S; Yildirim, F; Sindel, M; Tuncer, R

    2000-01-01

    Anatomical measurements were studied on 40 dry axis vertebrae to determine the suitability of the groove for the vertebral artery for atlanto-axial transarticular screw fixation technique. We measured 13 parameters including three angular and 10 linear dimensions related to the groove of the vertebral artery, pedicle, and pars interarticularis and evaluated 80 measurements for each parameter. All measurements were done after placing a Kischner guide wire through the pedicle. We found that differences between measurements on the left and right sides of each vertebra were nonsignificant. In spite of the variability in measurements such as height, width, and median angle of the pedicle, the decline angle for instrumentation, the depth of the groove for the vertebral artery, and the internal height of the pars interarticularis, all of these had good symmetry. However, there were statistically significant differences between the sides in measurements for both the width (P=0.05) and the angle (P<0.02) of the pedicle allowing instrumentation and they did not show good symmetry. The risk of vertebral artery injury was found to be 22.5% per specimen, or 16.25% per screw inserted because the internal height of the pars interarticularis at point of fixation was screws inserted because their values were technique would be extremely dangerous in 7.5% of specimens. In conclusion, the internal height of the pars interarticularis and the width of the pedicle for instrumentation should be evaluated together in thin CT sections preoperatively, because of the risk of vertebral artery injury in patients upon which atlanto-axial transarticular screw fixation is to be performed.

  8. Augmented Repair of Acute Achilles Tendon Rupture Using an Allograft Tendon Weaving Technique.

    PubMed

    Huang, Xiaowei; Huang, Gan; Ji, Ying; Ao, Rong guang; Yu, Baoqing; Zhu, Ya Long

    2015-01-01

    Achilles tendon rupture is a common injury, especially in those who are physically active. Although open surgery is a widely used option for the treatment of acute Achilles tendon rupture, the optimal treatment is still disputed. In our study, 59 patients with unilateral, closed, acute rupture of the Achilles tendon were treated by open surgery using an allograft weave to augment the repair. All the surgeries were performed within 1 to 4 days after injury. The mean American Orthopaedic Foot and Ankle Society ankle-hindfoot score was recorded as 91.20 (range 88 to 95), 95.34 (range 92 to 98), and 98.27 (range 97 to 99) at the 3-, 6-, and 12-month follow-up visit, respectively. At the final follow-up visit, the mean difference between the mid-calf circumference of the injured and uninjured legs was 0.19 (range -0.03 to 1.50) cm (p = .43). At the final follow-up visit, the mean difference between the vertical distances from the plantar surface of the heel to the ground for the injured and uninjured lower extremities was 0.44 (range -0.03 to 0.5) cm (p = .17). Augmented repair using the allograft tendon weaving technique provided satisfactory tendon strength and functional outcomes and a timely return to the patients' activities. Copyright © 2015 American College of Foot and Ankle Surgeons. Published by Elsevier Inc. All rights reserved.

  9. A comparison of augmentation techniques during in-tube evaporation of R-113

    SciTech Connect

    Reid, R.S. ); Pate, M.B. ); Bergles, A.E. )

    1991-05-01

    An experimental study was conducted to determine the potential of three techniques for augmenting in-tube evaporation of refrigerants: high-fin tubes, microfin tubes, and twisted tape inserts. Five tubes with internal fins and one smooth tube with a twisted-tape insert were tested. Additionally, experiments were performed with two reference smooth tubes having diameters similar to the maximum inside diameters of the finned tubes. All experiments involved evaporating Refrigerant 113 (R-113) by direct electrical heating of the tube wall. Local evaporation heat transfer coefficients were measured as a function of quality for a range of mass fluxes and heat fluxes. Enhancement factors were calculated by forming ratios of the heat transfer coefficient for the augmented tube and a smooth tube of the same maximum inside diameter. Mass fluxes, pressure levels, and qualities were fixed when enhancement factors were calculated. For the internally finned tubes the enhancement factors varied from 1.1 to 2.8. An internally finned tube having helical spiral angles of 16 deg produced the largest enhancement of heat transfer. The tube with the twisted-tape insert typically had an enhancement factor of about 1.5. Pressure gradient ratios and enhancement performance ratios are also presented.

  10. Engine Yaw Augmentation for Hybrid-Wing-Body Aircraft via Optimal Control Allocation Techniques

    NASA Technical Reports Server (NTRS)

    Taylor, Brian R.; Yoo, Seung Yeun

    2011-01-01

    Asymmetric engine thrust was implemented in a hybrid-wing-body non-linear simulation to reduce the amount of aerodynamic surface deflection required for yaw stability and control. Hybrid-wing-body aircraft are especially susceptible to yaw surface deflection due to their decreased bare airframe yaw stability resulting from the lack of a large vertical tail aft of the center of gravity. Reduced surface deflection, especially for trim during cruise flight, could reduce the fuel consumption of future aircraft. Designed as an add-on, optimal control allocation techniques were used to create a control law that tracks total thrust and yaw moment commands with an emphasis on not degrading the baseline system. Implementation of engine yaw augmentation is shown and feasibility is demonstrated in simulation with a potential drag reduction of 2 to 4 percent. Future flight tests are planned to demonstrate feasibility in a flight environment.

  11. Engine Yaw Augmentation for Hybrid-Wing-Body Aircraft via Optimal Control Allocation Techniques

    NASA Technical Reports Server (NTRS)

    Taylor, Brian R.; Yoo, Seung-Yeun

    2011-01-01

    Asymmetric engine thrust was implemented in a hybrid-wing-body non-linear simulation to reduce the amount of aerodynamic surface deflection required for yaw stability and control. Hybrid-wing-body aircraft are especially susceptible to yaw surface deflection due to their decreased bare airframe yaw stability resulting from the lack of a large vertical tail aft of the center of gravity. Reduced surface deflection, especially for trim during cruise flight, could reduce the fuel consumption of future aircraft. Designed as an add-on, optimal control allocation techniques were used to create a control law that tracks total thrust and yaw moment commands with an emphasis on not degrading the baseline system. Implementation of engine yaw augmentation is shown and feasibility is demonstrated in simulation with a potential drag reduction of 2 to 4 percent. Future flight tests are planned to demonstrate feasibility in a flight environment.

  12. Transpedicular vertebral body augmentation reinforced with pedicle screw fixation in fresh traumatic A2 and A3 lumbar fractures: comparison between two devices and two bone cements.

    PubMed

    Korovessis, Panagiotis; Vardakastanis, Konstantinos; Repantis, Thomas; Vitsas, Vasilios

    2014-07-01

    This retrospective study compares efficacy and safety of balloon kyphoplasty (BK) with calcium phosphate (Group A) versus KIVA implant with PMMA (Group B) reinforced with three vertebrae pedicle screw constructs for A2 and A3 single fresh non-osteoporotic lumbar (L1-L4) fractures in 38 consecutive age- and diagnosis-matched patient populations. Extracanal leakage of both low-viscosity PMMA and calcium phosphate (CP) as well as the following roentgenographic parameters: segmental kyphosis (SKA), anterior (AVBHr) and posterior (PVBHr) vertebral body height ratio, spinal canal encroachment (SCE) clearance, and functional outcome measures: VAS and SF-36, were recorded and compared between the two groups. All patients in both groups were followed for a minimum 26 (Group A) and 25 (Group B) months. Extracanal CP and PMMA leakage was observed in four (18 %) and three (15 %) vertebrae/patients of group A and B, respectively. Hybrid fixation improved AVBHr, SKA, SCE, but PVBHr only in group B. VAS and SF-36 improved postoperatively in the patients of both groups. Short-segment construct with the novel KIVA implant restored better than BK-fractured lumbar vertebral body, but this had no impact in functional outcome. Since there was no leakage difference between PMMA and calcium phosphate and no short-term adverse related to PMMA use were observed, we advice the use of PMMA in fresh traumatic lumbar fractures.

  13. Soft Tissue Augmentation Techniques in Implants Placed and Provisionalized Immediately: A Systematic Review

    PubMed Central

    Prados-Frutos, Juan Carlos; Manchón, Ángel; Rodríguez-Molinero, Jesús; Sammartino, Gilberto; Calvo Guirado, José Luis; Gómez-de Diego, Rafael

    2016-01-01

    The aim of this study was to evaluate the effectiveness of techniques for soft tissue augmentation in the placement of immediate implants with and without provisionalization and to assess the quality of the reports in the literature. Randomized clinical trials, prospective clinical trials, and case series were included in this review. Clinical questions were formulated and organised according to the PICOS strategy. An electronic search was performed in PubMed, Cochrane Central Register of Controlled Trials, Scopus, and ISI Web up until June 2016. Interexaminer agreement on eligibility (k = 0.842; p = 0.103) and quality (k = 0.933; p < 0.001) was high. Methodological approaches were assessed using criteria based on design related forms designed by the Dutch Cochrane Collaboration. Finally, 14 papers were identified. In two studies, the implant survival was 90%; for the rest of the studies it was 100%. All studies reported favourable aesthetic, biological, and radiographic outcomes. Surgical and biomechanical complications of this technique were not relevant. This technique effectively compensates for the expected loss of volume of the oral soft tissues and maintains high success rates with good aesthetic results over time. PMID:27517046

  14. Soft Tissue Augmentation Techniques in Implants Placed and Provisionalized Immediately: A Systematic Review.

    PubMed

    Rojo, Rosa; Prados-Frutos, Juan Carlos; Manchón, Ángel; Rodríguez-Molinero, Jesús; Sammartino, Gilberto; Calvo Guirado, José Luis; Gómez-de Diego, Rafael

    2016-01-01

    The aim of this study was to evaluate the effectiveness of techniques for soft tissue augmentation in the placement of immediate implants with and without provisionalization and to assess the quality of the reports in the literature. Randomized clinical trials, prospective clinical trials, and case series were included in this review. Clinical questions were formulated and organised according to the PICOS strategy. An electronic search was performed in PubMed, Cochrane Central Register of Controlled Trials, Scopus, and ISI Web up until June 2016. Interexaminer agreement on eligibility (k = 0.842; p = 0.103) and quality (k = 0.933; p < 0.001) was high. Methodological approaches were assessed using criteria based on design related forms designed by the Dutch Cochrane Collaboration. Finally, 14 papers were identified. In two studies, the implant survival was 90%; for the rest of the studies it was 100%. All studies reported favourable aesthetic, biological, and radiographic outcomes. Surgical and biomechanical complications of this technique were not relevant. This technique effectively compensates for the expected loss of volume of the oral soft tissues and maintains high success rates with good aesthetic results over time.

  15. Ridge augmentation with mineralized block allografts: clinical and histological evaluation of 8 cases treated with the 3-dimensional block technique.

    PubMed

    Jacotti, Michele; Wang, Hom-Lay; Fu, Jia-Hui; Zamboni, Giuseppe; Bernardello, Fabio

    2012-12-01

    Bone augmentation is frequently used to create sufficient bone volume for ideal implant placement. Severely resorbed ridges require extensive bone augmentation in the form of block allografts. A 3-dimensional graft technique has been developed to augment atrophic areas. This technique involves modifying the graft on a sterile prototype of the recipient site before the surgery. This article investigates the clinical and histological outcomes of ridge augmentation using this technique. Eight partially edentulous patients were recruited. Ridge augmentations were performed using block allografts, preadjusted, based on sterile prototypes of the recipient bed before the surgeries. After 8 months, 20 implants were inserted into the grafted sites. Eight bone cores were harvested for histological analysis. Highly vital and mineralized bone with lamellar organization was observed at the grafted sites. Having the ability to modify the allogeneic block grafts to fit the recipient sites before the surgery minimized the surgical time and risk of postoperative complications such as infection. In addition, the clinician could concentrate fully on achieving tension-free primary wound closure.

  16. A Novel Bone Marrow Stimulation Technique Augmented by Administration of Ultrapurified Alginate Gel Enhances Osteochondral Repair in a Rabbit Model

    PubMed Central

    Baba, Rikiya; Momma, Daisuke; Matsuoka, Masatake; Hontani, Kazutoshi; Elmorsy, Sameh; Endo, Kaori; Todoh, Masahiro; Tadano, Shigeru; Iwasaki, Norimasa

    2015-01-01

    Cartilage injuries are a common health problem resulting in the loss of daily activities. Bone marrow stimulation technique, one of the surgical techniques for the cartilage injuries, is characterized by technical simplicity and less invasiveness. However, it has been shown to result in fibrous or fibrocartilaginous repair with inferior long-term results. This study focused on using ultrapurified alginate gel (UPAL gel) as an adjuvant scaffold in combination with a bone marrow stimulation technique. The objective of this study was to assess the efficacy of a bone marrow stimulation technique augmented by UPAL gel in a rabbit osteochondral defect model. To achieve this goal, three experimental groups were prepared as follows: defects without intervention, defects treated with a bone marrow stimulation technique, and defects treated with a bone marrow stimulation technique augmented by UPAL gel. The macroscopic and histological findings of the defects augmented by UPAL gel improved significantly more than those of the others at 16 weeks postoperatively. The combination technique elicited hyaline-like cartilage repair, unlike bone marrow stimulation technique alone. This combination procedure has the potential of improving clinical outcomes after use of a bone marrow stimulation technique for articular cartilage injuries. PMID:26414601

  17. Percutaneous Facet Screw Fixation in the Treatment of Symptomatic Recurrent Lumbar Facet Joint Cyst: A New Technique

    SciTech Connect

    Amoretti, Nicolas Gallo, Giacomo Bertrand, Anne-Sophie; Bard, Robert L.; Kelekis, Alexis

    2016-01-15

    We present a case of percutaneous treatment of symptomatic recurrent lumbar facet joint cyst resistant to all medical treatments including facet joint steroid injection. Percutaneous transfacet fixation was then performed at L4–L5 level with a cannulated screw using CT and fluoroscopy guidance. The procedure time was 30 min. Using the visual analog scale (VAS), pain decreased from 9.5, preoperatively, to 0 after the procedure. At 6-month follow-up, an asymptomatic cystic recurrence was observed, which further reduced at the 1-year follow-up. Pain remained stable (VAS at 0) during all follow-ups. CT- and fluoroscopy-guided percutaneous cyst rupture associated with facet screw fixation could be an alternative to surgery in patients suffering from a symptomatic recurrent lumbar facet joint cyst.

  18. Pedicle Screw Instrumentation for Adolescent Idiopathic Scoliosis: The Insertion Technique, the Fusion Levels and Direct Vertebral Rotation

    PubMed Central

    2011-01-01

    The pedicle is a power nucleus of the vertebra and offers a secure grip of all 3 columns. Pedicle screw instrumentation has advantages of rigid fixation with improved three-dimensional (3D) correction and it is accepted as a reliable method with a high margin of safety. Accurate placement of the pedicle screws is important to reduce possible irreversible complications. Many methods of screw insertion have been reported. The author has been using the K-wire method coupled with the intraoperative single posteroanterior and lateral radiographs, which is the most safe, accurate and fast method. Identification of the curve patterns and determining the fusion levels are very important. The ideal classification of adolescent idiopathic scoliosis should address the all patterns, predict the extent of accurate fusion and have good inter/intraobserver reliability. My classification system matches with the ideal classification system, and it is simple and easy to learn; and my classification system has only 4 structural curve patterns and each curve has 2 types. Scoliosis is a 3D deformity; the coronal and sagittal curves can be corrected with rod rotation, and rotational deformity has to be corrected with direct vertebral rotation (DVR). Rod derotation and DVR are true methods of 3D deformity correction with shorter fusion and improved correction of both the fused and unfused curves, and this is accomplished using pedicle screw fixation. The direction of DVR is very important and it should be opposite to the direction of the rotational deformity of the vertebra. A rigid rod has to be used to prevent rod bend-out during the derotation and DVR. PMID:21629468

  19. [Pedicle screw-based systems for dynamic stabilization : An insight into the philosophy, technique, indications and success of these systems].

    PubMed

    Richolt, J; Rauschmann, M

    2010-06-01

    Pedicle screw-based dorsal dynamic systems for segmental stabilization of the lumbar spine are an addition to established surgical methods. They differ in terms of their kinetics as well as their materials. The long-term load on these systems is much higher than in spondylodesis systems, which can only successfully bear loads until bone fusion; cases of implant failure and screw loosening are not rare.Pedicle screw-based systems represent a therapeutic option when conservative treatment proves unsuccessful and fusion seems to be too early. Finding the correct indication versus that of established methods is complex given our limited knowledge to date; symptomatic segments with moderate degenerative changes in facet joints and disc height, as well as Modic 2-3 signs seem to be appropriate cases. The same is true of segments adjacent to planned fusions. Dynamic stabilization can be considered in the case of long fusion, cranial location in the lumbar spine and high likelihood of instability and deformity.

  20. Comparison of Lateral Window and Osteotome Techniques in Sinus Augmentation: Histological and Histomorphometric Evaluation

    PubMed Central

    Esfahanizadeh, N.; Rokn, A. R.; Paknejad, M.; Motahari, P.; Daneshparvar, H.; Shamshiri, AR.

    2012-01-01

    Objective: The aim of this study was to compare the lateral window and osteotome techniques for sinus lifting using histological and histomorphometric methods. Materials and Methods: In this clinical trial 10 patients (a total number of 14 sinus areas) who needed implant treatment in the atrophic posterior maxilla were enrolled. In all the cases the residual bone height between the sinus floor and the alveolar crest was less than 5 mm. Sinus augmentation was performed. The treatment modality for a given residual bone height was selected randomly and Bio-Oss was applied in all the cases as the graft material. After a healing period of about 10 months, in all the cases, the implants were placed and biopsies of alveolar crestal bone were obtained at the same time; biopsy specimens were evaluated using histological and histomorphometric methods. Fisher’s exact and Mann-Whitney U tests were used to compare distribution of variables in the two groups. Statistical significance was defined at P<0.05. Results: The new bone was located in direct contact with the biomaterial without any gaps. This viable bone consisted of lacunae containing osteocytes. Infiltration of inflammatory cells did not exhibit any significant differences between the two techniques. Foreign body reaction was not observed in any cases. Histomorphometric evaluations demonstrated that The mean values of the new bone in the lateral window and osteotome techniques were 30±6.0 and 25.2±5.2, respectively, with no significant differences between the two groups.. Moreover, the average quantity of residual biomaterial and connective tissue were similar for the two groups. Conclusion: The nature and the volume of the new bone in lateral window and osteotome techniques were the same. PMID:23119133

  1. Biomechanical performance of subpectoral biceps tenodesis: a comparison of interference screw fixation, cortical button fixation, and interference screw diameter.

    PubMed

    Sethi, Paul M; Rajaram, Arun; Beitzel, Knut; Hackett, Thomas R; Chowaniec, David M; Mazzocca, Augustus D

    2013-04-01

    Subpectoral biceps tenodesis with interference screw fixation allows reproducible positioning of the tendon to help maintain the length-tension relationship. The aim of our study was to evaluate the role of cortical button fixation in isolation or as an augment to interference screw fixation and to determine if the diameter of the interference screw affected fixation strength. Thirty-two cadaveric shoulders were dissected and randomized to 1 of 4 groups: (1) 7-mm interference screw and cortical button, (2) cortical button alone, (3) 7-mm interference screw, or (4) 8-mm interference screw. Testing was performed on a materials testing system with a 100-N load cycled at 1 Hz for 5000 cycles, followed by an axial load to failure test. Cyclic displacement, ultimate load to failure, and site of failure were recorded for each specimen. The mean ultimate failure loads were 7-mm interference screw with cortical button augmentation, 237.8 ± 120.4 N; cortical button alone, 99.4 ± 16.9 N; 7-mm interference screw, 275.5 ± 56 N; 8-mm interference screw, 277.1 ± 42.1 N. All specimens failed through tendon failure at the screw-tendon-bone interface. The biomechanical performance of subpectoral biceps tenodesis with interference screw fixation was not improved with cortical button augmentation. In addition, cortical button fixation alone yielded a significantly lower ultimate load to failure compared with interference screws. Finally, the biomechanical performance of smaller-diameter interference screws with matching bone tunnels was not affected by interference screw diameter. Copyright © 2013 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Mosby, Inc. All rights reserved.

  2. Horizontal Ridge Augmentation Before Placing Implants Using a Double-bone, Double Resorbable Membrane Technique: Two Clinical Cases.

    PubMed

    Castillo, Rodrigo

    2010-01-01

    Guided bone regeneration is a well established technique used for augmentation of deficient alveolar ridges. There is much evidence in the procedure. Multiple techniques have been introduced using various types of membranes and bone grating materials. However, efficacious regeneration requires both a high level of technical skills and a through understanding of major biological principles. This case report is presented to illustrate a reliable approach to successful management of two different alveolar defects.

  3. Less invasive lumbopelvic fixation technique using a percutaneous pedicle screw system for unstable pelvic ring fracture in a patient with severe multiple traumas.

    PubMed

    Yano, Sei; Aoki, Yasuchika; Watanabe, Atsuya; Nakajima, Takayuki; Takazawa, Makoto; Hirasawa, Hiroyuki; Takahashi, Kazuhisa; Nakagawa, Koichi; Nakajima, Arata; Takahashi, Hiroshi; Orita, Sumihisa; Eguchi, Yawara; Suzuki, Takane; Ohtori, Seiji

    2017-02-01

    Pelvic ring fractures are defined as life-threatening injuries that can be treated surgically with external or internal fixation. The authors report on an 81-year-old woman with an unstable pelvic fracture accompanying multiple traumas that was successfully treated with a less invasive procedure. The patient was injured in a traffic accident and sustained a total of 20 fractures, including pelvic ring, bilateral rib, and lumbar transverse processes fractures, and multiple fractures of both upper and lower extremities. The pelvic ring fracture was unstable with fractures of the bilateral sacrum with right sacroiliac disruption, right superior and inferior pubic rami, left superior pubic ramus, and ischium. During emergency surgery, bilateral external fixation was applied to the iliac crest to stabilize the pelvic ring. Second and third surgeries were performed 11 and 18 days after the first emergency surgery, respectively, to treat the multiple fractures. At the third surgery, the pelvic ring fracture was stabilized surgically using a less invasive posterior fixation technique. In this technique, 2 iliac screws were inserted on each side following an 8-cm midline posterior incision from the S-1 to S-3 spinous process, with the subcutaneous tissue detached from the fascia of the paraspinal muscles. The S-2 spinous process was removed and 2 rods were connected to bilateral iliac screws to stabilize the bilateral ilium in a switchback fashion. A crosslink device was applied to connect the 2 rods at the base of the S-2 spinous process. Following pelvic fixation, percutaneous pedicle screws were inserted into L-4 and L-5 vertebral bodies on both sides, and connected to the cranial rod connecting the bilateral iliac screws, thus completing the lumbopelvic fixation. The postoperative course was favorable with no postoperative complications. At the 10-month follow-up, bone union had been achieved at the superior ramus of the pubis, the patient did not complain of pain, and

  4. Accuracy of Percutaneous Pedicle Screw Insertion Technique with Conventional Dual Fluoroscopy Units and a Retrospective Comparative Study Based on Surgeon Experience.

    PubMed

    Nakahara, Masayuki; Yasuhara, Takao; Inoue, Takafumi; Takahashi, Yuichi; Kumamoto, Shinji; Hijikata, Yasukazu; Kusumegi, Akira; Sakamoto, Yushi; Ogawa, Koichi; Nishida, Kenki

    2016-06-01

    Study Design Retrospective comparative study. Objective To evaluate the accuracy of percutaneous pedicle screw (PPS) placement and intraoperative imaging time using dual fluoroscopy units and their differences between surgeons with more versus less experience. Methods One hundred sixty-one patients who underwent lumbar fusion surgery were divided into two groups, A (n = 74) and B (n = 87), based on the performing surgeon's experience. The accuracy of PPS placement and radiation time for PPS insertion were compared. PPSs were inserted with classic technique under the assistance of dual fluoroscopy units placed in two planes. The breach definition of PPS misplacement was based on postoperative computed tomography (grade I: no breach; grade II: <2 mm; grade III: ≤2 to <4 mm). Results Of 658 PPSs, only 21 screws were misplaced. The breach rates of groups A and B were 3.3% (grade II: 3.4%, grade III: 0%) and 3.1% (grade II: 2.6%, grade III: 0.6%; p = 0.91). One patient in grade III misplacement had a transient symptom of leg numbness. Median radiation exposure time during PPS insertion was 25 seconds and 51 seconds, respectively (p < 0.01). Conclusions Without using an expensive imaging support system, the classic technique of PPS insertion using dual fluoroscopy units in the lumbar and sacral spine is fairly accurate and provides good clinical outcomes, even among surgeons lacking experience.

  5. Enhancing screw stability in osteosynthesis with hydroxyapatite granules.

    PubMed

    Hasegawa, K; Yamamura, S; Dohmae, Y

    1998-01-01

    We employed hydroxyapatite (HA) granules to enhance screw fixation in revision surgery of failed osteosynthesis with a compression hip screw system in an 83-year-old woman. After reduction of the fracture, the fracture site with a large bone defect was filled with HA granules, and osteosynthesis was accomplished with a double cannulated lag screw and plate system. We feel that this HA granule augmentation method may also be suitable for osteosynthesis in other osteoporotic fractures.

  6. Arthroscopic Bankart repair and subscapularis augmentation: an alternative technique treating anterior shoulder instability with bone loss.

    PubMed

    Maiotti, Marco; Russo, Raffaele; Zanini, Antonio; Schröter, Steffen; Massoni, Carlo; Bianchedi, Diana

    2016-06-01

    This study presents the preliminary results of a new arthroscopic technique consisting of the association of 2 procedures, capsulolabral repair and subscapularis augmentation tenodesis, in the treatment of traumatic anterior shoulder instability with both glenoid bone loss and a Hill-Sachs lesion. Eighty-nine patients engaged in sports were enrolled in this retrospective case-series study with 2 to 5 years' follow-up. All patients underwent a computed tomography scan to assess the percentage of glenoid bone loss by the Pico method. A prior stabilization procedure had failed in 20 patients, who were then segregated into a different group. Visual analog scale (VAS), Rowe, and American Shoulder and Elbow Surgeons (ASES) scores were used to assess the results. Only 3 of 89 patients had a post-traumatic redislocation. The mean length of follow-up was 31.5 months (range, 25-60 months). The VAS, Rowe, and ASES scores showed significant improvements: The VAS score decreased from a mean of 3.1 to 0.5 (P = .0157), the Rowe score increased from 58.9 to 94.1 (P = .0215), and the ASES score increased from 68.5 to 95.5 (P = .0197). The mean deficit of external rotation was 6° with the arm at the side of the trunk, and the mean deficit was 3° with the arm in 90° of abduction. The described procedure is a reproducible and effective technique used to restore joint stability in patients engaged in sports who have incurred anterior recurrent shoulder dislocation associated with glenoid bone loss (<25%) and a Hill-Sachs lesion. Copyright © 2016 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.

  7. Time-of-flight camera technique for augmented reality in computer-assisted interventions

    NASA Astrophysics Data System (ADS)

    Mersmann, Sven; Müller, Michael; Seitel, Alexander; Arnegger, Florian; Tetzlaff, Ralf; Dinkel, Julien; Baumhauer, Matthias; Schmied, Bruno; Meinzer, Hans-Peter; Maier-Hein, Lena

    2011-03-01

    Augmented reality (AR) for enhancement of intra-operative images is gaining increasing interest in the field of navigated medical interventions. In this context, various imaging modalities such as ultrasound (US), C-Arm computed tomography (CT) and endoscopic images have been applied to acquire intra-operative information about the patient's anatomy. The aim of this paper was to evaluate the potential of the novel Time-of-Flight (ToF) camera technique as means for markerless intra-operative registration. For this purpose, ToF range data and corresponding CT images were acquired from a set of explanted non-transplantable human and porcine organs equipped with a set of marker that served as targets. Based on a rigid matching of the surfaces generated from the ToF images with the organ surfaces generated from the CT data, the targets extracted from the planning images were superimposed on the 2D ToF intensity images, and the target visualization error (TVE) was computed as quality measure. Color video data of the same organs were further used to assess the TVE of a previously proposed marker-based registration method. The ToF-based registration showed promising accuracy yielding a mean TVE of 2.5+/-1.1 mm compared to 0.7+/-0.4 mm with the marker-based approach. Furthermore, the target registration error (TRE) was assessed to determine the anisotropy in the localization error of ToF image data. The TRE was 8.9+/- 4.7 mm on average indicating a high localization error in the viewing direction of the camera. Nevertheless, the young ToF technique may become a valuable means for intra-operative surface acquisition. Future work should focus on the calibration of systematic distance errors.

  8. Efficacy and Safety of Augmenting the Preclose Technique with a Collagen-Based Closure Device for Percutaneous Endovascular Aneurysm Repair

    SciTech Connect

    Patel, Rafiuddin; Juszczak, Maciej T.; Bratby, Mark J.; Sideso, Ediri; Anthony, Susan; Tapping, Charles R.; Handa, Ashok; Darby, Christopher R.; Perkins, Jeremy; Uberoi, Raman

    2015-08-15

    PurposeTo report our experience of selectively augmenting the preclose technique for percutaneous endovascular aneurysm repair (p-EVAR) with an Angio-Seal device as a haemostatic adjunct in cases of significant bleeding after tensioning the sutures of the suture-mediated closure devices.Materials and MethodsProspectively collected data for p-EVAR patients at our institute were analysed. Outcomes included technical success and access site complications. A logistic regression model was used to analyse the effects of sheath size, CFA features and stent graft type on primary failure of the preclose technique necessitating augmentation and also on the development of complications.Resultsp-EVAR was attempted via 122 CFA access sites with a median sheath size of 18-French (range 12- to 28-French). Primary success of the preclose technique was 75.4 % (92/122). Angio-Seal augmentation was utilised as an adjunct to the preclose technique in 20.5 % (25/122). The overall p-EVAR success rate was 95.1 % (116/122). There was a statistically significant relationship (p = 0.0093) between depth of CFA and primary failure of preclose technique. CFA diameter, calcification, type of stent graft and sheath size did not have significant effects on primary preclose technique failure. Overall 4.9 % (6/122) required surgical conversion but otherwise there were no major complications.ConclusionAugmentation with an Angio-Seal device is a safe and effective adjunct to increase the success rate of the preclose technique in p-EVAR.

  9. Augmented reality in the surgery of cerebral arteriovenous malformations: technique assessment and considerations.

    PubMed

    Cabrilo, Ivan; Bijlenga, Philippe; Schaller, Karl

    2014-09-01

    Augmented reality technology has been used for intraoperative image guidance through the overlay of virtual images, from preoperative imaging studies, onto the real-world surgical field. Although setups based on augmented reality have been used for various neurosurgical pathologies, very few cases have been reported for the surgery of arteriovenous malformations (AVM). We present our experience with AVM surgery using a system designed for image injection of virtual images into the operating microscope's eyepiece, and discuss why augmented reality may be less appealing in this form of surgery. N = 5 patients underwent AVM resection assisted by augmented reality. Virtual three-dimensional models of patients' heads, skulls, AVM nidi, and feeder and drainage vessels were selectively segmented and injected into the microscope's eyepiece for intraoperative image guidance, and their usefulness was assessed in each case. Although the setup helped in performing tailored craniotomies, in guiding dissection and in localizing drainage veins, it did not provide the surgeon with useful information concerning feeder arteries, due to the complexity of AVM angioarchitecture. The difficulty in intraoperatively conveying useful information on feeder vessels may make augmented reality a less engaging tool in this form of surgery, and might explain its underrepresentation in the literature. Integrating an AVM's hemodynamic characteristics into the augmented rendering could make it more suited to AVM surgery.

  10. Surgical Navigation Technology Based on Augmented Reality and Integrated 3D Intraoperative Imaging

    PubMed Central

    Elmi-Terander, Adrian; Skulason, Halldor; Söderman, Michael; Racadio, John; Homan, Robert; Babic, Drazenko; van der Vaart, Nijs; Nachabe, Rami

    2016-01-01

    Study Design. A cadaveric laboratory study. Objective. The aim of this study was to assess the feasibility and accuracy of thoracic pedicle screw placement using augmented reality surgical navigation (ARSN). Summary of Background Data. Recent advances in spinal navigation have shown improved accuracy in lumbosacral pedicle screw placement but limited benefits in the thoracic spine. 3D intraoperative imaging and instrument navigation may allow improved accuracy in pedicle screw placement, without the use of x-ray fluoroscopy, and thus opens the route to image-guided minimally invasive therapy in the thoracic spine. Methods. ARSN encompasses a surgical table, a motorized flat detector C-arm with intraoperative 2D/3D capabilities, integrated optical cameras for augmented reality navigation, and noninvasive patient motion tracking. Two neurosurgeons placed 94 pedicle screws in the thoracic spine of four cadavers using ARSN on one side of the spine (47 screws) and free-hand technique on the contralateral side. X-ray fluoroscopy was not used for either technique. Four independent reviewers assessed the postoperative scans, using the Gertzbein grading. Morphometric measurements of the pedicles axial and sagittal widths and angles, as well as the vertebrae axial and sagittal rotations were performed to identify risk factors for breaches. Results. ARSN was feasible and superior to free-hand technique with respect to overall accuracy (85% vs. 64%, P < 0.05), specifically significant increases of perfectly placed screws (51% vs. 30%, P < 0.05) and reductions in breaches beyond 4 mm (2% vs. 25%, P < 0.05). All morphometric dimensions, except for vertebral body axial rotation, were risk factors for larger breaches when performed with the free-hand method. Conclusion. ARSN without fluoroscopy was feasible and demonstrated higher accuracy than free-hand technique for thoracic pedicle screw placement. Level of Evidence: N/A PMID:27513166

  11. Prophylactic augmentation of the proximal femur: an investigation of two techniques.

    PubMed

    Raas, Christoph; Hofmann-Fliri, Ladina; Hörmann, Romed; Schmoelz, Werner

    2016-03-01

    Osteoporotic hip fractures are an increasing problem in an ageing population. They result in high morbidity, mortality and high socioeconomic costs. For patients with poor bone quality, prophylactic augmentation of the proximal femur might be an option for fracture prevention. In two groups of paired human femora the potential of limited polymethyl-methacrylate (PMMA) augmentation (11-15 ml) in a V-shape pattern and the insertion of a proximal femur nail antirotation (PFNA) blade were investigated. The testing was carried out pair wise simulating the single leg stand. The untreated femur in each pair served as control. An axial load was applied until failure. Load displacement parameters and temperature increase during the augmentation process were recorded. In the PMMA group no significant difference was found between the augmented and non-augmented specimen concerning load to failure (p = 0.35) and energy to failure (p = 0.9). A median temperature increase of 9.5 °C was observed in the augmented specimen. A significant correlation was found between the amount of applied PMMA and the temperature increase (Cor. Coef. = 0.82, p = 0.042). In the PFNA group, a significant decrease of load to failure and a non-significant decrease of energy to failure were observed (p = 0.037 and p = 0.075). Limited V-shaped PMMA augmentation and PFNA blade insertion did not show any improvement in failure load or energy to failure. Volumes of up to 15 ml PMMA did not cause a critical surface temperature increase.

  12. Arthroscopic-Assisted Acromioclavicular Joint Reconstruction Using the TightRope Device With Allograft Augmentation: Surgical Technique

    PubMed Central

    Frank, Rachel M.; Trenhaile, Scott W.

    2015-01-01

    Surgical management of acromioclavicular (AC) joint separations remains challenging, especially in the revision setting. Most commonly, Rockwood type I and II injuries are managed nonoperatively whereas type IV, V, and VI injuries are managed with surgery. Type III separations are more controversial, with evidence supporting both nonoperative and operative treatment options. Multiple different arthroscopic techniques have been described; however, there is no current gold standard. AC joint reconstruction with the TightRope device (Arthrex, Naples, FL) with the patient in the lateral decubitus position is a method of restoring joint stability that allows for a minimally invasive, low-profile fixation construct using a single drill hole through the clavicle. Allograft augmentation of this fixation construct helps to eliminate the stress risers potentially created by this device while increasing overall repair construct stability. The purpose of this article is to describe the surgical technique for arthroscopic AC joint reconstruction using a TightRope device with allograft augmentation. PMID:26759765

  13. New Techniques for Augmenting Saliva Collection: Bacon Rules and Lozenge Drools

    PubMed Central

    Miočević, Olga; Warner, Melissa C.; Slowey, Paul D.; Shirtcliff, Elizabeth A.

    2015-01-01

    -matched control samples correlated significantly with concentrations from the lozenge and bacon conditions. Implications These results indicate that both the lozenge and smelling bacon improve saliva collection times and that neither technique interferes with salivary hormone concentrations. This study reveals new methods to augment saliva collection strategies. PMID:25773460

  14. Interventional techniques in managing persistent pain after vertebral augmentation procedures: a retrospective evaluation.

    PubMed

    Georgy, Bassem A

    2007-09-01

    Based on systematic reviews, it appears that at least 10% of patients may continue to suffer with residual or persistent pain after successful vertebral or sacral augmentation procedures. To report and evaluate the incidence and prevalence of different spinal injections in patients who received vertebroplasty, kyphoplasty, and sacroplasty procedures for both benign and malignant compression fractures. A retrospective case review. Retrospective review of all cases of vertebroplasty, sacroplasty, and kyphoplasty performed in a 12-month period in a single outpatient setting of interventional radiology was conducted. In a 12-month period starting from October 2005 to September 2006, 144 patients underwent cement augmentation procedures. Of the 144, 34 patients required a spinal injection procedure for residual or persistent pain within a 1-year period after the augmentation procedure. Twenty-four patients required epidural steroid injections, 6 patients required intercostal nerve blocks, 5 patients required trigger point injections, 5 patients required sacroiliac joint injections, and 1 patient required facet joint injections. Nine patients who required lumbar epidural steroid injections and all patients who required intercostal nerve blocks and had underwent a thoracic cement augmentation procedure. A small proportion of patients undergoing percutaneous cement augmentation for vertebral compression fractures or sacral insufficiency fractures potentially require spinal injections to treat residual pain after the procedure.

  15. The Delay Fill Technique: A Safer Approach to Combination Augmentation Mastopexy

    PubMed Central

    Patronella, Christopher K.; Mentz, Henry A.; Johnson-Alviza, Jaclyn

    2015-01-01

    Combining breast augmentation with mastopexy is a challenging procedure that has a relatively high revision rate in the literature. Some surgeons prefer a two-stage procedure to avoid the potential for skin flap or nipple–areolar complex necrosis that can occur with a one-stage procedure. The authors compared 101 patients who had subpectoral breast augmentation with immediate implant fill and mastopexy with 203 patients who had subpectoral breast augmentation with delayed (10–14 days) implant fill and mastopexy. They found the revision rate for immediate implant fill was 24%; in the delayed implant fill group, the revision rate was 10.3%. Patients had soft tissue-related complications in 16% of the immediate fill group and in 2% of the delayed fill group. Delaying implant fill in combined breast augmentation mastopexy significantly reduces the risk of soft tissue-related complications and revision procedures; the delay flap phenomenon is responsible for fewer wound-healing complications when implant fill is delayed during a combined augmentation mastopexy procedure. PMID:26528084

  16. Techniques and long-term outcomes of cotton-clipping and cotton-augmentation strategies for management of cerebral aneurysms.

    PubMed

    Safavi-Abbasi, Sam; Moron, Felix; Sun, Hai; Oppenlander, Mark E; Kalani, M Yashar S; Mulholland, Celene B; Zabramski, Joseph M; Nakaji, Peter; Spetzler, Robert F

    2016-09-01

    OBJECTIVE To address the challenges of microsurgically treating broad-based, frail, and otherwise complex aneurysms that are not amenable to direct clipping, alternative techniques have been developed. One such technique is to use cotton to augment clipping ("cotton-clipping" technique), which is also used to manage intraoperative aneurysm neck rupture, and another is to reinforce unclippable segments or remnants of aneurysm necks with cotton ("cotton-augmentation" technique). This study reviews the natural history of patients with aneurysms treated with cotton-clipping and cotton-augmentation techniques. METHODS The authors queried a database consisting of all patients with aneurysms treated at Barrow Neurological Institute in Phoenix, Arizona, between January 1, 2004, and December 31, 2014, to identify cases in which cotton-clipping or cotton-augmentation strategies had been used. Management was categorized as the cotton-clipping technique if cotton was used within the blades of the aneurysm clip and as the cotton-clipping technique if cotton was used to reinforce aneurysms or portions of the aneurysm that were unclippable due to the presence of perforators, atherosclerosis, or residual aneurysms. Data were reviewed to assess patient outcomes and annual rates of aneurysm recurrence or hemorrhage after the initial procedures were performed. RESULTS The authors identified 60 aneurysms treated with these techniques in 57 patients (18 patients with ruptured aneurysms and 39 patients with unruptured aneurysms) whose mean age was 53.1 years (median 55 years; range 24-72 years). Twenty-three aneurysms (11 cases of subarachnoid hemorrhage) were treated using cotton-clipping and 37 with cotton-augmentation techniques (7 cases of subarachnoid hemorrhage). In total, 18 patients presented with subarachnoid hemorrhage. The mean Glasgow Outcome Scale (GOS) score at the time of discharge was 4.4. At a mean follow-up of 60.9 ± 35.6 months (median 70 months; range 10-126 months

  17. A prospective study of breast dynamic morphological changes after dual-plane augmentation mammaplasty with 3D scanning technique.

    PubMed

    Ji, Kai; Luan, Jie; Liu, Chunjun; Mu, Dali; Mu, Lanhua; Xin, Minqiang; Sun, Jingjing; Yin, Shilu; Chen, Lin

    2014-01-01

    The dual-plane technique has been widely used in augmentation mammaplasty procedures. However, there are some concerns about aesthetic contour maintenance for long time after muscle releasing. This study aims to track and analyze breast dynamic morphological changes after dual-plane breast augmentation with three-dimensional (3D) scanning technique. Thirteen dual-plane anatomic implant augmentation patients underwent 3D scanning preoperatively (pre-OP) and postoperatively in four time points (1 month: post-1M, 3 months: post-3M, 6 months: post-6M and 12 months: post-12M). The linear distance, breast projection, nipple position, breast volume and breast surface area were measured and analyzed on the 3D models over time. Compared with post-12M, no significant differences were found in distances of nipple to midline, nipple to inframammary fold and sternal notch to the level of inframammary fold after 6 months in both straight-line distance and its projection on surface. The distances between sternal notch and nipple had no significant difference after post-1M. Breast volume changes had no significant difference after post-3M. The volume and area percentage of upper pole decreased while the lower pole's increased gradually. The surface showed no significant changes after post-1M. The changes of breast projection had no significance after post-1M either. The nipple moved 1.0±0.6 cm laterally (X axis), 0.6±0.7 cm upward( Y axis) and 2.3±1.1 cm anteriorly (Z axis) at post-12M, and the differences were not significant after post-1M. 3D scanning technique provides an objective and effective way to evaluate breast morphological changes after augmentation mammaplasty over time. Dual-plane augmentation optimizes breast shape especially in the lower pole and maintains stable aesthetic outcome during the 12 months follow-up. Most of the contour changes and the interadaptation with the implant have completed 6 months after operation. Therefore, 6 months could be chosen as a

  18. A Prospective Study of Breast Dynamic Morphological Changes after Dual-plane Augmentation Mammaplasty with 3D Scanning Technique

    PubMed Central

    Ji, Kai; Luan, Jie; Liu, Chunjun; Mu, Dali; Mu, Lanhua; Xin, Minqiang; Sun, Jingjing; Yin, Shilu; Chen, Lin

    2014-01-01

    Background The dual-plane technique has been widely used in augmentation mammaplasty procedures. However, there are some concerns about aesthetic contour maintenance for long time after muscle releasing. This study aims to track and analyze breast dynamic morphological changes after dual-plane breast augmentation with three-dimensional (3D) scanning technique. Methods Thirteen dual-plane anatomic implant augmentation patients underwent 3D scanning preoperatively (pre-OP) and postoperatively in four time points (1 month: post-1M, 3 months: post-3M, 6 months: post-6M and 12 months: post-12M). The linear distance, breast projection, nipple position, breast volume and breast surface area were measured and analyzed on the 3D models over time. Results Compared with post-12M, no significant differences were found in distances of nipple to midline, nipple to inframammary fold and sternal notch to the level of inframammary fold after 6 months in both straight-line distance and its projection on surface. The distances between sternal notch and nipple had no significant difference after post-1M. Breast volume changes had no significant difference after post-3M. The volume and area percentage of upper pole decreased while the lower pole’s increased gradually. The surface showed no significant changes after post-1M. The changes of breast projection had no significance after post-1M either. The nipple moved 1.0±0.6 cm laterally(X axis), 0.6±0.7 cm upward(Y axis) and 2.3±1.1 cm anteriorly (Z axis) at post-12M, and the differences were not significant after post-1M. Conclusions 3D scanning technique provides an objective and effective way to evaluate breast morphological changes after augmentation mammaplasty over time. Dual-plane augmentation optimizes breast shape especially in the lower pole and maintains stable aesthetic outcome during the 12 months follow-up. Most of the contour changes and the interadaptation with the implant have completed 6 months after operation

  19. Biomechanical Comparison of Inter-fragmentary Compression Pressures: Lag Screw versus Herbert Screw for Anterior Odontoid Screw Fixation.

    PubMed

    Park, Jin-Woo; Kim, Kyoung-Tae; Sung, Joo-Kyung; Park, Seong-Hyun; Seong, Ki-Woong; Cho, Dae-Chul

    2017-09-01

    The purpose of the present study was to compare inter-fragmentary compression pressures after fixation of a simulated type II odontoid fracture with the headless compression Herbert screw and a half threaded cannulated lag screw. We compared inter-fragmentary compression pressures between 40- and 45-mm long 4.5-mm Herbert screws (n=8 and n=9, respectively) and 40- and 45-mm long 4.0-mm cannulated lag screws (n=7 and n=10, respectively) after insertion into rigid polyurethane foam test blocks (Sawbones, Vashon, WA, USA). A washer load cell was placed between the two segments of test blocks to measure the compression force. Because the total length of each foam block was 42 mm, the 40-mm screws were embedded in the cancellous foam, while the 45-mm screws penetrated the denser cortical foam at the bottom. This enabled us to compare inter-fragmentary compression pressures as they are affected by the penetration of the apical dens tip by the screws. The mean compression pressures of the 40- and 45-mm long cannulated lag screws were 50.48±1.20 N and 53.88±1.02 N, respectively, which was not statistically significant (p=0.0551). The mean compression pressures of the 40-mm long Herbert screw was 52.82±2.17 N, and was not statistically significant compared with the 40-mm long cannulated lag screw (p=0.3679). However, 45-mm Herbert screw had significantly higher mean compression pressure (60.68±2.03 N) than both the 45-mm cannulated lag screw and the 40-mm Herbert screw (p=0.0049 and p=0.0246, respectively). Our results showed that inter-fragmentary compression pressures of the Herbert screw were significantly increased when the screw tip penetrated the opposite dens cortical foam. This can support the generally recommended surgical technique that, in order to facilitate maximal reduction of the fracture gap using anterior odontoid screws, it is essential to penetrate the apical dens tip with the screw.

  20. Prediction of Driver's Intention of Lane Change by Augmenting Sensor Information Using Machine Learning Techniques.

    PubMed

    Kim, Il-Hwan; Bong, Jae-Hwan; Park, Jooyoung; Park, Shinsuk

    2017-06-10

    Driver assistance systems have become a major safety feature of modern passenger vehicles. The advanced driver assistance system (ADAS) is one of the active safety systems to improve the vehicle control performance and, thus, the safety of the driver and the passengers. To use the ADAS for lane change control, rapid and correct detection of the driver's intention is essential. This study proposes a novel preprocessing algorithm for the ADAS to improve the accuracy in classifying the driver's intention for lane change by augmenting basic measurements from conventional on-board sensors. The information on the vehicle states and the road surface condition is augmented by using an artificial neural network (ANN) models, and the augmented information is fed to a support vector machine (SVM) to detect the driver's intention with high accuracy. The feasibility of the developed algorithm was tested through driving simulator experiments. The results show that the classification accuracy for the driver's intention can be improved by providing an SVM model with sufficient driving information augmented by using ANN models of vehicle dynamics.

  1. An in vitro biomechanical comparison of equine proximal interphalangeal joint arthrodesis techniques: an axial positioned dynamic compression plate and two abaxial transarticular cortical screws inserted in lag fashion versus three parallel transarticular cortical screws inserted in lag fashion.

    PubMed

    Sod, Gary A; Riggs, Laura M; Mitchell, Colin F; Hubert, Jeremy D; Martin, George S

    2010-01-01

    To compare in vitro monotonic biomechanical properties of an axial 3-hole, 4.5 mm narrow dynamic compression plate (DCP) using 5.5 mm cortical screws in conjunction with 2 abaxial transarticular 5.5 mm cortical screws inserted in lag fashion (DCP-TLS) with 3 parallel transarticular 5.5 mm cortical screws inserted in lag fashion (3-TLS) for the equine proximal interphalangeal (PIP) joint arthrodesis. Paired in vitro biomechanical testing of 2 methods of stabilizing cadaveric adult equine forelimb PIP joints. Cadaveric adult equine forelimbs (n=15 pairs). For each forelimb pair, 1 PIP joint was stabilized with an axial 3-hole narrow DCP (4.5 mm) using 5.5 mm cortical screws in conjunction with 2 abaxial transarticular 5.5 mm cortical screws inserted in lag fashion and 1 with 3 parallel transarticular 5.5 mm cortical screws inserted in lag fashion. Five matching pairs of constructs were tested in single cycle to failure under axial compression, 5 construct pairs were tested for cyclic fatigue under axial compression, and 5 construct pairs were tested in single cycle to failure under torsional loading. Mean values for each fixation method were compared using a paired t-test within each group with statistical significance set at P<.05. Mean yield load, yield stiffness, and failure load under axial compression and torsion, single cycle to failure, of the DCP-TLS fixation were significantly greater than those of the 3-TLS fixation. Mean cycles to failure in axial compression of the DCP-TLS fixation was significantly greater than that of the 3-TLS fixation. The DCP-TLS was superior to the 3-TLS in resisting the static overload forces and in resisting cyclic fatigue. The results of this in vitro study may provide information to aid in the selection of a treatment modality for arthrodesis of the equine PIP joint.

  2. Are S1 Screws a Useful Adjunct to Iliac Screws in Long Fusions to the Sacrum in Cerebral Palsy?

    PubMed

    Schoenleber, Scott J; Asghar, Jahangir; Bastrom, Tracey P; Shufflebarger, Harry L

    2016-01-01

    Multicenter prospective database review of patients with cerebral palsy (CP) and spinal deformity. To determine if the type of distal fixation is associated with improved correction of coronal deformity or pelvic obliquity (PO) at 2 years in long posterior fusions to the sacrum. Multiple techniques are utilized for distal fixation in patients with CP. Although there is emerging evidence that the augmentation of iliac screws with S1 screws may be beneficial, this remains controversial. A prospective, multicenter database was used to identify patients with CP who underwent long posterior fusions to the sacrum. Eighty-eight patients were included, 52 with iliac screws (I) and 36 with iliac and S1 screws (IS) for distal fixation. Preoperative, first erect, and 2-year follow-up radiographs and complications were analyzed. Statistical analysis was performed using ANOVA and repeated measures ANOVA with significance set at P < 0.05. Scoliosis was the primary deformity in greater than 90% of patients in both groups (P=0.84). Preoperative coronal deformity was similar (I = 83°, IS = 87°, P = 0.49), but correction was better with the use of S1 screws on the first erect radiograph and at 2 years (I = 35°, IS = 22°, P = 0.001), reflecting correction of 58% and 74% for iliac and iliac-S1 screws, respectively (P < 0.001). Preoperative PO was similar (I = 29°, IS = 30°, P = 0.71) and was noted to improve more in the iliac-S1 group by 2 years (I = 11°, IS = 5°, P = 0.004), representing correction of 60% and 77% for the iliac and iliac-S1 groups, respectively (P = 0.018). There was no difference in the rate of major (P = 0.27) or minor (P = 0.65) complications in either group. Bilateral S1 and iliac screws are associated with improved spinal deformity and PO correction at 2 years in the CP population. Two points of distal fixation, S1, and ilium should be considered for this population. 3.

  3. [Maxillary sinus floor augmentation using the transalveolar technique with simultaneous placement of dental implants: a 5-year clinical retrospective study].

    PubMed

    Lin, Shengxiao; Feng, Yuan; Xie, Juan; Song, Yingliang; Xie, Chao; Li, Dehua

    2014-03-01

    To evaluate the clinical and radiographic outcomes of placing dental implants in the posterior maxilla using the transalveolar technique. Between January 2005 and December 2009, a total of 94 cases, 55 males and 39 females, aged (46.9 ± 11.8) years, were consecutively enrolled in this study with maxillary sinus floor augmentation using the transalveolar technique. Radiographic evaluations were conducted on panoramic and periapical radiographs at each recall. The follow-up clinical examination included cumulative survival rate(CSR) of implants, peri-implant marginal bone loss (MBL) and the height of sinus floor augmentation and the endo-sinus bone gain (ESBG). Sinus membrane perforation was found in 4 cases.Finally 126 implants (90 cases) were placed. The perforation rate of this surgical procedure was 3.08% (4/130).Four implants lost during the healing time, the early success of implants was 96.80% (121/125). During a mean follow-up time of (34.4 ± 20.4) months, all the implants were successfully in function, with the cumulative survival rate after function loading of 100.00%. The mean MBL was (0.75 ± 0.51) mm during the healing time, and (0.48 ± 0.41) mm during the follow-up period. The mean residual bone height (RBH) was (7.27 ± 1.30) mm at the position of implants placement, the length of implant protruding into the sinus was (2.77 ± 1.15) mm, and the height of sinus floor augmentation was (4.52 ± 1.39) mm. At the loading time, the mean endo-sinus bone gain was (3.81 ± 1.60) mm. After the follow-up time of 34 months, the newly formed bone on the maxillary sinus floor underwent further remodeling with a median bone reduction value of 0.37 (0.10, 0.88) mm. Maxillary sinus floor augmentation using the transalveolar technique is a predictable treatment modality. The augmentation of the maxillary sinus floor using the transalveolar technique could lead to bone formation under the sinus. The newly formed bone showed slight absorbtion in the long term follow-up.

  4. Original technique for penile girth augmentation through porcine dermal acellular grafts: results in a 69-patient series.

    PubMed

    Alei, Giovanni; Letizia, Piero; Ricottilli, Francesco; Simone, Pierfranco; Alei, Lavinia; Massoni, Francesco; Ricci, Serafino

    2012-07-01

    Although different techniques for augmentation phalloplasty have been reported in the medical literature, this issue is still highly controversial, and none of the proposed procedures has been unanimously approved. The aim of this study is to describe an innovative surgical technique for penile girth augmentation with porcine dermal acellular grafts, through a small transverse incision at the penile base, along the penopubic junction. Between 2000 and 2009, 104 patients were referred to our institution for penile enhancement. After a preoperative psychosexual consultation and a general medical assessment, 69 patients were deemed suitable good candidates for surgery. The average penis circumference was measured at the mid-length of the penis and was 8.1 cm (5.4-10.7 cm) and 10.8 cm (6.5-15.8 cm) during flaccidity and erection, respectively. All patients received penile augmentation with porcine dermal acellular grafts. Results evaluation of an innovative technique for penile girth augmentation through exogenous porcine grafts and small penobubic incision. Postoperative measurements were performed at 6 and 12 months. At the 1-year follow-up, the average penis circumference was 11.3 cm (8.2-13.2 cm, 3.1 cm mean increase) during flaccidity and 13.2 cm (8.8-14.5 cm, 2.4 cm mean increase) during erection. No major complications occurred in the series. Minor complications were resolved with conservative treatment within 3 weeks. Sexual activity was resumed from 1 to 2 months after surgery. The psychosexual impact of the operation was beneficial in the majority of cases. Penile girth enlargement with acellular dermal matrix grafts has several advantages over augmentation with autogenous dermis-fat grafts: the elimination of donor site morbidity and a significantly shorter operation time. With this approach, through a short dorsal incision at the base of the penis, the scar is concealed in a crease covered by pubic hair and thus hardly visible. © 2012

  5. Effective Techniques for Augmenting Heat Transfer: An Application of Entropy Generation Minimization Principles.

    DTIC Science & Technology

    1980-12-01

    Twisted tape inserts ...... .................. 31 3.3 Helical tubes ........ ...................... . 34 3.4 Propeller inserts...friction (f) information on each of these flow geometries. 1-2 Twisted Tape Inserts The use of twisted tape inserts to auqment both laminar and turbulent...32- 10 -2.45 - 5.08 _ N 01 00 le0 Re. Fiq. 3.2. Augmentation entropy generation number for twisted tape inserts. 1 10 17 -~ 104 1.0 104 R%0 Fig. 3.3

  6. Subperiosteal Minimally Invasive Aesthetic Ridge Augmentation Technique (SMART): A New Standard for Bone Reconstruction of the Jaws.

    PubMed

    Lee, Ernesto A

    Traditional guided bone regeneration techniques include flap mobilization and placement of a bone graft, often with the use of space-maintaining devices and cell-occlusive membranes. This approach is associated with frequent complications that negatively affect the outcome of the augmentation and the peri-implant soft tissue esthetics. Although current tunneling techniques have focused on periodontal soft tissue applications, earlier publications described their use for horizontal augmentation of mandibular posterior edentulous ridges in full-denture patients. More recently, the use of recombinant human platelet-derived growth factor (rhPDGF-BB) was tested with different bone matrices to treat maxillary anterior edentulous spans. The present case series reports the use of a subperiosteal minimally invasive aesthetic ridge augmentation technique (SMART) to treat 60 single and multiple edentulous, dentate, and implant sites on 21 patients and five treatment categories with a follow-up period ranging from 4 to 30 months. The technique includes the use of a laparoscopic approach to deliver a growth factor/xenograft combination into a subperiosteal pouch. No flap elevation, cell-occlusive membranes, space-maintaining devices, or decortication procedures were used. The results from this case series demonstrated predictable and consistent bone regeneration. The average gain in ridge width for all treatment categories was 5.11 mm (SD 0.76 mm), which compares favorably with previously published reports. Morbidity and complication rates were consistently reduced as well. Human histology results show xenograft particles surrounded by newly formed bone. The role of the periosteum as a source of pluripotent cells in growth factor–mediated bone regeneration is discussed.

  7. Fixation Strength of Caudal Pedicle Screws after Posterior Lumbar Interbody Fusion with the Modified Cortical Bone Trajectory Screw Method

    PubMed Central

    Miwa, Toshitada; Yamashita, Tomoya; Kuroda, Yusuke; Ohwada, Tetsuo

    2016-01-01

    Study Design Clinical case series. Purpose In the posterior lumbar interbody fusion (PLIF) procedure in our institute, the cephalad screw trajectory follows a mediolateral and caudocephalad directed path according to the original cortical bone trajectory (CBT) method. However, the starting point of the caudal screw is at the medial border of the pedicle on an articular surface of the superior articular process, and the trajectory takes a mediolateral path parallel to the cephalad endplate. The incidence of caudal screw loosening after PLIF with this modified CBT screw method was investigated, and significant risk factors for caudal screw loosening were evaluated. Overview of Literature A biomechanical study of this modified caudal screw trajectory using the finite element method reported about a 20% increase in uniaxial yield pullout load compared with the traditional trajectory. However, there has been no clinical study concerning the fixation strength of this modified caudal screw trajectory. Methods The subjects were 193 consecutive patients who underwent single-level PLIF with modified CBT screw fixation. Caudal screw loosening was checked in computed tomography at 6 months after surgery, and screw loosening was defined as a radiolucency of 1 mm or more at the bone-screw interface. Results The incidence of caudal screw loosening after lumbosacral PLIF (46.2%) was significantly higher than that after floating PLIF (6.0%). No significant differences in sex, brand of the instruments, and diameter and length of the caudal screw were evident between patients with and without caudal screw loosening. Patients with caudal screw loosening were significantly older at the time of surgery than patients without caudal screw loosening. Conclusions Fixation strength of the caudal screw after floating PLIF with this modified CBT screw technique was sufficiently acceptable. Fixation strength after the lumbosacral procedure was not. PMID:27559442

  8. Surgical Technique for Laparoscopic Removal of a Magnetic Lower Esophageal Sphincter Augmentation Device.

    PubMed

    Stetler, Jamil L; Gill, Sujata; Patel, Ankit; Davis, S Scott; Lin, Edward

    2015-12-01

    Nissen fundoplication is the current gold standard for surgical management of gastroesophageal reflux disease; however, a magnetic antireflux device is now an alternative surgical procedure. The early literature shows good reflux control with minimal complications, and therefore placement of these devices is growing in popularity. As more of these devices are placed, there will be cases in which they will need to be removed. A laparoscopic method for removing the device is presented here. We present a case of a 42-year-old female with history of gastroesophageal reflux who underwent a laparoscopic placement of a magnetic lower esophageal sphincter augmentation device and repair of a small hiatal hernia. She had a complicated postoperative course before presenting to our institution with a 2-year history of persistent dysphagia and requesting the device be removed. Laparoscopic removal of the device was performed. After laparoscopic removal of the patient's magnetic lower esophageal sphincter augmentation device, she had subjective improvement in her dysphagia but is now being medically managed for gastroesophageal reflux and for delayed gastric emptying. Laparoscopic removal of magnetic lower esophageal sphincter augmentation devices will sometimes be necessary and may be challenging if the surgeon encounters significant scar tissue around the gastroesophageal junction. Postoperative complications are similar to those encountered with foregut surgeries and include postoperative delayed gastric emptying.

  9. Misplaced Cervical Screws Requiring Reoperation

    PubMed Central

    Peterson, Jeremy C.; Smith, Zachary A.; Hsu, Wellington K.; Fehlings, Michael G.; Hart, Robert A.; Hilibrand, Alan S.; Nassr, Ahmad; Rahman, Ra’Kerry K.; Tannoury, Chadi A.; Tannoury, Tony; Mroz, Thomas E.; Currier, Bradford L.; De Giacomo, Anthony F.; Fogelson, Jeremy L.; Jobse, Bruce C.; Massicotte, Eric M.; Riew, K. Daniel

    2017-01-01

    Study Design: A multicenter, retrospective case series. Objective: In the past several years, screw fixation of the cervical spine has become commonplace. For the most part, this is a safe, low-risk procedure. While rare, screw backout or misplaced screws can lead to morbidity and increased costs. We report our experiences with this uncommon complication. Methods: A multicenter, retrospective case series was undertaken at 23 institutions in the United States. Patients were included who underwent cervical spine surgery from January 1, 2005, to December 31, 2011, and had misplacement of screws requiring reoperation. Institutional review board approval was obtained at all participating institutions, and detailed records were sent to a central data center. Results: A total of 12 903 patients met the inclusion criteria and were analyzed. There were 11 instances of screw backout requiring reoperation, for an incidence of 0.085%. There were 7 posterior procedures. Importantly, there were no changes in the health-related quality-of-life metrics due to this complication. There were no new neurologic deficits; a patient most often presented with pain, and misplacement was diagnosed on plain X-ray or computed tomography scan. The most common location for screw backout was C6 (36%). Conclusions: This study represents the largest series to tabulate the incidence of misplacement of screws following cervical spine surgery, which led to revision procedures. The data suggest this is a rare event, despite the widespread use of cervical fixation. Patients suffering this complication can require revision, but do not usually suffer neurologic sequelae. These patients have increased cost of care. Meticulous technique and thorough knowledge of the relevant anatomy are the best means of preventing this complication. PMID:28451491

  10. Biceps tenodesis (long head): arthroscopic keyhole technique versus arthroscopic interference screw: a prospective comparative clinical and radiographic marker study.

    PubMed

    Kany, Jean; Guinand, Régis; Croutzet, Pierre; Amaravathi, Rajkumar; Sekaran, Padmanaban

    2016-01-01

    The long head biceps tenodesis (LHBT) is an alternative to tenotomy in order to prevent Popeye sign.Biomechanical studies showed that interference screw(IFS) was the strongest fixation but there might be complications and cost. What's more, the analyses of tenodesis failures are undervalued because they only take visible deformations of the arm into account. The purpose of this study was to compare a modified arthroscopic "keyhole" LHBT (modified @KH) with an arthroscopic IFS LHBT(@IFS) using an objective method. We hypothesized that modified @KH gave similar clinical outcomes as @IFS without its hassles or drawbacks. We present a 12-month prospective comparative study (modified @KH versus @IFS) performed by two experienced orthopedic surgeons. Modified @KH was performed on one hundred and nine patients versus @IFS that was performed on one hundred and two. A radiopaque marker was placed into the tendon. The review was conducted in the sixth month with clinical examination and plain standard X-ray to objectify the potential migration of the marker. Modified @KH showed 2.4 % visible deformity without any Popeye sign but 3.4 % radiographic metallic marker migrations. No complications were noted. @IFS showed 5.8 % visible deformity with 2.9 % Popeye sign and with 10.3 % radiographic metallic marker migrations;pain at tenodesis location was noted in 2 %. P value (0.13) indicates that there were no statistically significant differences. We confirm the hypothesis that the modified@KH gives clinical and radiographic outcomes at least similar to @IFS without any complications and cost. The establishment of the radiopaque marker allows us to know the exact number of failures.Level of evidence Consecutive prospective comparative clinical, Level II-1 studies.

  11. The Extended Direct Anterior Approach for Column Augmentation in the Deficient Pelvis: A Novel Surgical Technique, and Case Series Report.

    PubMed

    Spanyer, Jonathon M; Beaumont, Christopher M; Yerasimides, Jonathan G

    2017-02-01

    Anterior column deficiency of the pelvis may pose a serious threat to the stability of the acetabular component after total hip arthroplasty and, thus, jeopardize the overall success of the procedure. After Institutional Review Board approval, a retrospective review was undertaken to identify all patients undergoing revision total hip arthroplasty with anterior column augmentation through an extended direct anterior approach. Demographics and surgical details were collected, and subjects were followed for a 2-year minimum period to measure patient outcomes and to evaluate for the stability of construct fixation. A novel surgical procedure description was provided and supplemented with an illustrative case example. At 2 years post augmentation, patients had favorable functional outcomes with radiologic evidence of stable fixation. Proximal extension of the direct anterior approach to the hip can facilitate anterior column access and augmentation to improve stability of the hip reconstruction. This treatment may be an alternative to spanning constructs such as cup-cage constructs and custom implants, affording the potential for long-term biologic fixation. Further investigation into this technique is warranted. Copyright © 2016 Elsevier Inc. All rights reserved.

  12. Bone cement augmentation in the prevention of adjacent segment failure after multilevel adult deformity fusion.

    PubMed

    Lattig, Friederike

    2009-08-01

    Prospective case report series and detailed description of technique. To describe a surgical procedure designed to prevent fracture and cutting-through and pullout of screws in the adjacent segment after multilevel deformity correction in adults. Surgery of adult deformities has a high complication rate. One of the potential late complications is the development of fracture at the first mobile segment above a multilevel lumbar or thoracolumbar spinal fusion that necessitates further surgical intervention with extension of the instrumentation. Augmentation with bone cement of the last instrumented vertebra and the first mobile vertebra has the potential to prevent this pathology. Three patients with degenerative thoracolumbar kyphoscoliosis and 3 with adjacent segment failure after correction surgery were treated. Cannulated and perforated pedicle screws were placed in the uppermost-instrumented vertebra. A vertebroplasty tube was inserted from 1 side at the center of the first mobile vertebra. Under C-arm control, vertebroplasty was performed in both vertebrae. Intraoperatively, there were no cement-related complications. Follow-ups at 6 and 12 (+/-2) months revealed there was no loss of correction, fracture or screw loosening in the augmented vertebrae. Bone cement augmentation of the uppermost screws and the first mobile vertebra in multilevel adult deformity and revision surgery seems to be a safe and potentially effective method of preventing adjacent segment failure.

  13. Biomechanical comparison of lag screw versus self-drilling screw fixation of oblique metatarsal osteotomy.

    PubMed

    Rabenhorst, Brien M; Smith, Michael P; James, C Roger; Grimes, Jerry S

    2011-08-01

    Several fixation methods for a Weil metatarsal osteotomy have been proposed. Lag screw fixation has been described as the preferred fixation technique. The self-drilling screw has been introduced and can be used for fixation of the Weil osteotomy. The current study compared self-drilling screws with lag screw fixation. A Weil metatarsal osteotomy was performed on the second, third, and fourth metatarsals of five matched pairs of fresh frozen cadaver feet. The feet of each pair were randomly assigned ical to fixation with either a 2.0-mm cortical lag screw or a 2.0-mm self-drilling screw. The second metatarsals were stressed using cantilever bending. The third and fourth metatarsals were stressed under a shear force. Yield load, deformation at yield load, structural stiffness, and energy stored at yield load were recorded. There were no statistically significant differences (p < 0.05) noted. However, there was a trend toward greater biomechanical stability with the lag screw. There were no significant differences in the stability of fixation of the self-drilling screw and lag screw. There was a trend toward the lag screw fixation being more stable. The clinical significance of this trend is uncertain but suggests there is not a large difference between the two methods of fixation.

  14. A home-based intervention using augmentative and alternative communication (AAC) techniques in rural Kenya: what are the caregivers' experiences?

    PubMed

    Gona, J K; Newton, C R; Hartley, S; Bunning, K

    2014-01-01

    Caring for a child with complex communication needs associated with a developmental condition frequently adds stress to the caregiver. Furthermore, professional assistance is scarce in low-income rural settings. For such children speech is frequently unachievable. Augmentative and alternative communication provides options for supplementing or replacing speech with other techniques. The current study aimed to examine the experiences of caregivers in Kenya before and after a home-based intervention using augmentative and alternative communication techniques with children with complex communication needs. Caregivers were interviewed pre- and post-intervention. The interviews were digitally recorded, transcribed and translated into English. Content analysis was applied through the stages of text familiarization and topic organization. Emergent themes and their sub-themes were identified and labelled. Connections between themes were established and interpretations made. The procedure was completed by a second researcher independently. Conflicting ideas were jointly discussed until consensus was achieved. Four themes emerged from the data: communication process; struggle; normality; and supernatural power. Before intervention, the caregivers acknowledged their expertise in communications with the child, while also revealing their sense of isolation, burden and pain. Normality was present as a source of comparison and also an aspirational goal. Post-intervention more positive language was used to describe the child. There was an 'opening up' of communication that recognized the child's strengths and some social support systems were re-established. The power of the supernatural was recognized before and after intervention. Caring of a child with complex communication needs presents many challenges. A home-based intervention using augmentative and alternative communication techniques appears to have been a catalyst for some positive transformations in the caregivers

  15. Surgical Navigation Technology Based on Augmented Reality and Integrated 3D Intraoperative Imaging: A Spine Cadaveric Feasibility and Accuracy Study.

    PubMed

    Elmi-Terander, Adrian; Skulason, Halldor; Söderman, Michael; Racadio, John; Homan, Robert; Babic, Drazenko; van der Vaart, Nijs; Nachabe, Rami

    2016-11-01

    A cadaveric laboratory study. The aim of this study was to assess the feasibility and accuracy of thoracic pedicle screw placement using augmented reality surgical navigation (ARSN). Recent advances in spinal navigation have shown improved accuracy in lumbosacral pedicle screw placement but limited benefits in the thoracic spine. 3D intraoperative imaging and instrument navigation may allow improved accuracy in pedicle screw placement, without the use of x-ray fluoroscopy, and thus opens the route to image-guided minimally invasive therapy in the thoracic spine. ARSN encompasses a surgical table, a motorized flat detector C-arm with intraoperative 2D/3D capabilities, integrated optical cameras for augmented reality navigation, and noninvasive patient motion tracking. Two neurosurgeons placed 94 pedicle screws in the thoracic spine of four cadavers using ARSN on one side of the spine (47 screws) and free-hand technique on the contralateral side. X-ray fluoroscopy was not used for either technique. Four independent reviewers assessed the postoperative scans, using the Gertzbein grading. Morphometric measurements of the pedicles axial and sagittal widths and angles, as well as the vertebrae axial and sagittal rotations were performed to identify risk factors for breaches. ARSN was feasible and superior to free-hand technique with respect to overall accuracy (85% vs. 64%, P < 0.05), specifically significant increases of perfectly placed screws (51% vs. 30%, P < 0.05) and reductions in breaches beyond 4 mm (2% vs. 25%, P < 0.05). All morphometric dimensions, except for vertebral body axial rotation, were risk factors for larger breaches when performed with the free-hand method. ARSN without fluoroscopy was feasible and demonstrated higher accuracy than free-hand technique for thoracic pedicle screw placement. N/A.

  16. Cardiac Limited Ultrasound Examination Techniques to Augment the Bedside Cardiac Physical Examination.

    PubMed

    Kimura, Bruce J; Shaw, David J; Amundson, Stan A; Phan, James N; Blanchard, Daniel G; DeMaria, Anthony N

    2015-09-01

    The current practice of physical diagnosis is dependent on physician skills and biases, inductive reasoning, and time efficiency. Although the clinical utility of echocardiography is well known, few data exist on how to integrate 2-dimensional screening "quick-look" ultrasound applications into a novel, modernized cardiac physical examination. We discuss the evidence basis behind ultrasound "signs" pertinent to the cardiovascular system and elemental in synthesis of bedside diagnoses and propose the application of a brief cardiac limited ultrasound examination based on these signs. An ultrasound-augmented cardiac physical examination can be taught in traditional medical education and has the potential to improve bedside diagnosis and patient care.

  17. Fixed-angle screws vs standard screws in acetabular prosthesis fixation: a cadaveric biomechanical study.

    PubMed

    Hugate, Ronald R; Dickey, Ian D; Chen, Qingshan; Wood, Christina M; Sim, Franklin H; Rock, Michael G

    2009-08-01

    Secure fixation of acetabular components in total hip arthroplasty can be challenging. The purpose of this study was to perform biomechanical analysis of cup fixation strength using fixed-angle vs standard screw fixation. Multihole, porous-backed acetabular prostheses were implanted in both acetabuli of 8 cadaveric pelves using standard press-fit techniques. Fixed-angle screws were used on the left side, and standard cancellous screws were used in the right. The use of fixed-angle screws enhanced acetabular fixation substantially under subfailure cyclic loading conditions and load-to-failure. The triradiate screw configuration increases the bending moment required to fail the specimens as well. Fixed-angle screws may be useful for achieving rigid fixation of acetabular prostheses in challenging clinical scenarios.

  18. Single-screw Fixation of Adolescent Salter-II Proximal Humeral Fractures: Biomechanical Analysis of the "One Pass Door Lock" Technique.

    PubMed

    Miller, Mark Carl; Redman, Christopher N; Mistovich, R Justin; Muriuki, Muturi; Sangimino, Mark J

    2017-09-01

    Pin fixation of Salter-II proximal humeral fractures in adolescents approaching skeletal maturity has potential complications that can be avoided with single-screw fixation. However, the strength of screw fixation relative to parallel and diverging pin fixation is unknown. To compare the biomechanical fixation strength between these fixation modalities, we used synthetic composite humeri, and then compared these results in composite bone with cadaveric humeri specimens. Parallel pinning, divergent pinning, and single-screw fixation repairs were performed on synthetic composite humeri with simulated fractures. Six specimens of each type were tested in axial loading and other 6 were tested in torsion. Five pair of cadaveric humeri were tested with diverging pins and single screws for comparison. Single-screw fixation was statistically stronger than pin fixation in axial and torsional loading in both composite and actual bone. There was no statistical difference between composite and cadaveric bone specimens. Single-screw fixation can offer greater stability to adolescent Salter-II fractures than traditional pinning. Single-screw fixation should be considered as a viable alternative to percutaneous pin fixation in transitional patients with little expected remaining growth.

  19. The accuracy and the safety of individualized 3D printing screws insertion templates for cervical screw insertion.

    PubMed

    Deng, Ting; Jiang, Minghui; Lei, Qing; Cai, Lihong; Chen, Li

    2016-12-01

    Clinical trial for cervical screw insertion by using individualized 3-dimensional (3D) printing screw insertion templates device. The objective of this study is to evaluate the safety and accuracy of the individualized 3D printing screw insertion template in the cervical spine. Ten patients who underwent posterior cervical fusion surgery with cervical pedicle screws, laminar screws or lateral mass screws between December 2014 and December 2015 were involved in this study. The patients were examined by CT scan before operation. The individualized 3D printing templates were made with photosensitive resin by a 3D printing system to ensure the screw shafts entered the vertebral body without breaking the pedicle or lamina cortex. The templates were sterilized by a plasma sterilizer and used during the operation. The accuracy and the safety of the templates were evaluated by CT scans at the screw insertion levels after operation. The accuracy of this patient-specific template technique was demonstrated. Only one screw axis greatly deviated from the planned track and breached the cortex of the pedicle because the template was split by rough handling and then we inserted the screws under the fluoroscopy. The remaining screws were inserted in the track as preoperative design and the screw axis deviated by less than 2 mm. Vascular or neurologic complications or injuries did not happen. And no infection, broken nails, fracture of bone structure, or screw pullout occurred. This study verified the safety and the accuracy of the individualized 3D printing screw insertion templates in the cervical spine as a kind of intraoperative screw navigation. This individualized 3D printing screw insertion template was user-friendly, moderate cost, and enabled a radiation-free cervical screw insertion.

  20. Determining the efficacy of screw and washer fixation as a method for securing olecranon osteotomies used in the surgical management of intraarticular distal humerus fractures.

    PubMed

    Woods, Barrett I; Rosario, Bedda L; Siska, Peter A; Gruen, Gary S; Tarkin, Ivan S; Evans, Andrew R

    2015-01-01

    The purpose of this study was to critically evaluate the efficacy of single screw and washer fixation in comparison with other methods for securing olecranon osteotomies. The hypothesis is that screw and washer fixation is a safe and effective means of olecranon osteotomy fixation with fusion and complication rates similar to other methods of fixation. Retrospective review. Two Level I Urban Trauma Centers. Patients were treated within the last 20 years and received 1 of 4 types of fixation (screw and washer alone, screw and washer augmented with tension band, tension band alone, or plate and screws) after osteotomy. Open reduction and internal fixation of OTA/AO 13B/C distal humerus fractures with an olecranon osteotomy. The primary outcome measure was the presence of osteotomy union. Secondary outcome measures were olecranon nonunion, loss of articular reduction, and removal of hardware. Logistic regression was used to determine the associations between method of osteotomy fixation and removal of hardware or nonunion rates. Comorbidities were stratified using the Charlson comorbidity index. One hundred sixty patients met the inclusion criteria. Thirty-nine patients underwent screw fixation alone, 47 had tension band fixation, 16 had plate fixation, and 58 had tension band and screw fixation. Screw fixation demonstrated equal or better rates of union, maintenance of reduction, absence of infection, and implant removal compared with alternative fixation techniques. Higher Charlson scores were associated with higher rates of nonunion. Screw and washer fixation is a safe and effective means of securing an olecranon osteotomy. Charlson comorbidity score is one factor that may influence the development of nonunion after osteotomy. Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

  1. The incidence of secondary vertebral fracture of vertebral augmentation techniques versus conservative treatment for painful osteoporotic vertebral fractures: a systematic review and meta-analysis.

    PubMed

    Song, Dawei; Meng, Bin; Gan, Minfeng; Niu, Junjie; Li, Shiyan; Chen, Hao; Yuan, Chenxi; Yang, Huilin

    2015-08-01

    Percutaneous vertebroplasty (PVP) and balloon kyphoplasty (BKP) are minimally invasive and effective vertebral augmentation techniques for managing osteoporotic vertebral compression fractures (OVCFs). Recent meta-analyses have compared the incidence of secondary vertebral fractures between patients treated with vertebral augmentation techniques or conservative treatment; however, the inclusions were not thorough and rigorous enough, and the effects of each technique on the incidence of secondary vertebral fractures remain unclear. To perform an updated systematic review and meta-analysis of the studies with more rigorous inclusion criteria on the effects of vertebral augmentation techniques and conservative treatment for OVCF on the incidence of secondary vertebral fractures. PubMed, MEDLINE, EMBASE, SpringerLink, Web of Science, and the Cochrane Library database were searched for relevant original articles comparing the incidence of secondary vertebral fractures between vertebral augmentation techniques and conservative treatment for patients with OVCFs. Randomized controlled trials (RCTs) and prospective non-randomized controlled trials (NRCTs) were identified. The methodological qualities of the studies were evaluated, relevant data were extracted and recorded, and an appropriate meta-analysis was conducted. A total of 13 articles were included. The pooled results from included studies showed no statistically significant differences in the incidence of secondary vertebral fractures between patients treated with vertebral augmentation techniques and conservative treatment. Subgroup analysis comparing different study designs, durations of symptoms, follow-up times, races of patients, and techniques were conducted, and no significant differences in the incidence of secondary fractures were identified (P > 0.05). No obvious publication bias was detected by either Begg's test (P = 0.360 > 0.05) or Egger's test (P = 0.373 > 0.05). Despite current thinking in the

  2. Intraoperative stimulation of pedicle screws: a new method for verification of screw placement.

    PubMed

    Young, W F; Morledge, D E; Martin, W; Park, K B

    1995-12-01

    Pedicular fixation of the lumbosacral spine has become a popular procedure for improving fusion rates. Even in experienced hands, it can be associated with a significant rate of screw malpositioning and potential nerve root injury. In this report, we describe a technique for improving screw localization utilizing evoked electromyography responses from direct stimulation of pedicle instrumentation.

  3. Transarterial coil-augmented Onyx embolization for brain arteriovenous malformation. Technique and experience in 22 consecutive patients.

    PubMed

    Gao, Xu; Liang, Guobiao; Li, Zhiqing; Wang, Xiaogang; Yu, Chunyong; Cao, Peng; Chen, Jun; Li, Jingyuan

    2014-01-01

    Onyx has been widely adopted for the treatment of arteriovenous malformations (AVMs). However, its control demands operators accumulate a considerable learning curve. We describe our initial experience using a novel injection method for the embolization of AVMs. We retrospectively reviewed the data of all 22 patients with brain AVMs (12 men, 10 women; age range, 12-68 years; mean age, 43.2 years) treated by the transarterial coil-augmented Onyx injection technique. The size of the AVMs ranged from 25 mm to 70 mm (average 35.6 mm). The technical feasibility of the procedure, procedure-related complications, angiographic results, and clinical outcome were evaluated. In every case, endovascular treatment (EVT) was completed. A total of 31 sessions were performed, with a mean injection volume of 6.1 mL (range, 1.5-16.0 mL). An average of 96.7% (range 85%-100%) estimated size reduction was achieved, and 18 AVMs could be completely excluded by EVT alone. The results remained stable on follow-up angiograms. A procedural complication occurred in one patient, with permanent mild neurologic deficit. Our preliminary series demonstrated that the coil-augmented Onyx injection technique is a valuable adjunct achieving excellent nidal penetration and improving the safety of the procedure.

  4. Vertebroplasty with self-locking hexagonal metal implants shows comparable primary and secondary stiffness to PMMA cement augmentation techniques in a biomechanical vertebral compression fracture model

    PubMed Central

    Disch, A. C.; Huber, J. F.

    2010-01-01

    With the growing incidence of vertebral compression fractures in elderly patients having a fair overall health condition, minimal-invasive treatment techniques are getting in focus of surgical therapy. Cement augmentation is widely performed and its complications and mechanical limitations are well described. Implants avoiding the side effects of cement augmentation while reaching the same level of stability would be desirable. The primary and secondary stability of a new augmentation method with self-locking hexagonal metal implants were investigated and compared with the performance of established augmentation options. 18 fresh-frozen human spinal specimens (Th12–L2/L3–L5) were tested with pure moments of 7.5 Nm in a six-degree-of-freedom spine simulator to investigate primary and secondary stability of three augmentation techniques: (1) vertebroplasty, (2) PMMA filled cavity and (3) hexagonal metal implants. An increasing three-step cyclic loading model was included. Elastic displacement and height loss under loading did not show significant differences between the three test groups. Investigation of primary and secondary stability evenly demonstrated comparable results for all techniques indicating an insufficiency to stabilise the fracture with higher load cycles. The newly introduced method for augmentation with the metal implant Spine Pearls achieved comparable results to bone cement based techniques in a biomechanical in vitro study. Midterm and longterm reduction preservation and ingrowth of the implants have to be proven in further studies. PMID:20213299

  5. Surgeon's view of pedicle screw implantation for the monitoring neurophysiologist.

    PubMed

    Joglekar, Siddharth B; Mehbod, Amir A

    2012-12-01

    Pedicle screws have become the gold standard of spinal instrumentation over the past decade owing to their biomechanical superiority. Despite their advantages, pedicle screw instrumentation is potentially dangerous, and surgeons wish to improve accuracy of screw placement to avoid complications associated with screw misplacement. The anatomy of the pedicles is variable throughout the spine, and several landmarks and trajectories have been suggested to aid safe placement of pedicle screws in the spine. Several techniques such as x-ray and computed tomography scan imaging coupled with computer-aided navigation are available to improve accuracy of screw insertion. Intraoperative neuromonitoring with the help of triggered electromyographic recordings has evolved as an objective evidence of assessing pedicle breach and proximity of the screw to neural structures. While all imaging and electrophysiological modalities should be applied on an individualized basis, finally no adjunctive technique can fully replace the need for surgical expertise and experience.

  6. Accuracy of Pedicle Screw Placement in Scoliosis Surgery: A Comparison between Conventional Computed Tomography-Based and O-Arm-Based Navigation Techniques

    PubMed Central

    Akazawa, Tsutomu; Sakuma, Tsuyoshi; Koyama, Kayo; Nemoto, Tetsuharu; Nawata, Kento; Yamazaki, Atsuro; Minami, Shohei

    2014-01-01

    Study Design Retrospective study. Purpose We compared the accuracy of O-arm-based navigation with computed tomography (CT)-based navigation in scoliotic surgery. Overview of Literature No previous reports comparing the results of O-arm-based navigation with conventional CT-based navigation in scoliotic surgery have been published. Methods A total of 222 pedicle screws were implanted in 29 patients using CT-based navigation (group C) and 416 screws were implanted in 32 patients using O-arm-based navigation (group O). Postoperative CT was performed to assess the screw accuracy, using the established Neo classification (grade 0: no perforation, grade 1: perforation <2 mm, grade 2: perforation ≥2 and <4, and grade 3: perforation ≥4 mm). Results In group C, 188 (84.7%) of the 222 pedicle screw placements were categorized as grade 0, 23 (10.4%) were grade 1, 11 (5.0%) were grade 2, and 0 were grade 3. In group O, 351 (84.4%) of the 416 pedicle screw placements were categorized as grade 0, 52 (12.5%) were grade 1, 13 (3.1%) were grade 2, and 0 were grade 3. Statistical analysis showed no significant difference in the prevalence of grade 2.3 perforations between groups C and O. The time to position one screw, including registration, was 10.9±3.2 minutes in group C, but was significantly decreased to 5.4±1.1 minutes in group O. Conclusions O-arm-based navigation facilitates pedicle screw insertion as accurately as conventional CT-based navigation. The use of O-arm-based navigation successfully reduced the time, demonstrating advantages in the safety and accuracy of pedicle screw placement for scoliotic surgery. PMID:24967047

  7. Decisive factor in increase of loading at adjacent segments after lumbar fusion: operative technique, pedicle screws, or fusion itself: biomechanical analysis using finite element

    NASA Astrophysics Data System (ADS)

    Park, Joon-Hee; Kim, Ho-Joong; Kang, Kyoung-Tak; Kim, Ka-Yeon; Chun, Heoung-Jae; Moon, Seong-Hwan; Lee, Hwan-Mo

    2009-12-01

    The aim of this study is to investigate the change in biomechanical milieu following removal of pedicle screws or removal of spinous process with posterior ligament complex in instrumented single level lumbar arthrodesis. We developed and validated a finite element model (FEM) of the intact lumbar spine (L2-4). Four scenarios of L3-4 lumbar fusion were simulated: posterolateral fusion (PLF) at L3-4 using pedicle screw system with preservation of PLC (Pp WiP), L3-4 lumbar posterolateral fusion state after removal of pedicle screw system with preservation of PLC (Pp WoP), L3-4 using pedicle screw system without preservation PLC (Sp WiP), L3-4 lumbar posterolateral fusion state after removal of pedicle screw system without preservation of PLC (Sp WoP). For these models, we investigated the range of motion and maximal Von mises stress of disc in all segments under various moments. All fusion models demonstrated increase in range of motion at adjacent segments compared to the intact model.For the four fusion models, the WiP model s P had the largest increase in range of motion at each adjacent segment. This study demonstrated that removal of pedicle screw system and preservation of PLC after complete lumbar spinal fusion could reduce the stress of adjacent segments synergistically and might have beneficial effects in preventing ASD.

  8. Decisive factor in increase of loading at adjacent segments after lumbar fusion: operative technique, pedicle screws, or fusion itself: biomechanical analysis using finite element

    NASA Astrophysics Data System (ADS)

    Park, Joon-Hee; Kim, Ho-Joong; Kang, Kyoung-Tak; Kim, Ka-yeon; Chun, Heoung-Jae; Moon, Seong-Hwan; Lee, Hwan-Mo

    2010-03-01

    The aim of this study is to investigate the change in biomechanical milieu following removal of pedicle screws or removal of spinous process with posterior ligament complex in instrumented single level lumbar arthrodesis. We developed and validated a finite element model (FEM) of the intact lumbar spine (L2-4). Four scenarios of L3-4 lumbar fusion were simulated: posterolateral fusion (PLF) at L3-4 using pedicle screw system with preservation of PLC (Pp WiP), L3-4 lumbar posterolateral fusion state after removal of pedicle screw system with preservation of PLC (Pp WoP), L3-4 using pedicle screw system without preservation PLC (Sp WiP), L3-4 lumbar posterolateral fusion state after removal of pedicle screw system without preservation of PLC (Sp WoP). For these models, we investigated the range of motion and maximal Von mises stress of disc in all segments under various moments. All fusion models demonstrated increase in range of motion at adjacent segments compared to the intact model.For the four fusion models, the WiP model s P had the largest increase in range of motion at each adjacent segment. This study demonstrated that removal of pedicle screw system and preservation of PLC after complete lumbar spinal fusion could reduce the stress of adjacent segments synergistically and might have beneficial effects in preventing ASD.

  9. Initial strength of highpressed extrusion poly-L-lactide screw.

    PubMed

    Matsushita, T; Nakamura, K; Shiro, R; Takazawa, H; Tsuji, K; Kurokawa, T

    2000-01-01

    We developed a poly-L-lactide material strengthened by a highpressed extrusion technique. The bending strength of a rod made of that material is higher than that of the same size rods made of poly-L-lactide strengthened by drawing technique, which has been used in clinical cases. The purposes of this study were, first to clarify if the initial strength of extrusion-strengthened poly-L-lactide screws is higher than that of draw-strengthened poly-L-lactide screws, and, secondly to investigate the safe torque for driving the screws in clinical usage. In accordance with AO screw design, five kinds of screws were manufactured. In a pull-out test and a twisting test using a DYRACON blocks, the strength of the highpressed extrusion-strengthened poly-L-lactide material was also higher than that of the draw-strengthened poly-L-lactide material after milling into screws. In the simulation using minipig bones and the 4.5 mm psi cortical screws, when the thickness was below 0.5 mm, between 0.5 and 2 mm or over 3 mm, the break locations were in the cortical bone, the thread of the screw and the under head fillet respectively. In the simulation using minipig bones and the 4.0 mm psi cancellous screws, breakage occurred not on the screws but on the cancellous bone in all screws.

  10. Optically driven Archimedes micro-screws for micropump applications: multiple blade design

    NASA Astrophysics Data System (ADS)

    Baldeck, Patrice L.; Lin, Chih-Lang; Lin, Yu-Sheng; Lin, Chin-Te; Chung, Tien-Tung; Bouriau, Michel; Vitrant, Guy

    2011-10-01

    We study the rotation of photo-driven Archimedes screw with multiple blades. The micron-sized Archimedes screws are readily made by the two-photon polymerization technique. Free-floating screws that are trapped by optical tweezers align in the laser irradiation direction, and rotate spontaneously. In this study we demonstrate that the rotation speeds of two-blade-screws is twice the rotation speed of one-blade-screw. However, more complex 3-blade-screws rotate slower than 2-blade-screws due to their limited geometry resolution at this micron scale.

  11. Coracoid bone graft osteolysis after Latarjet procedure: A comparison study between two screws standard technique vs mini-plate fixation.

    PubMed

    Giacomo, Giovanni Di; Costantini, Alberto; de Gasperis, Nicola; De Vita, Andrea; Lin, Bernard K H; Francone, Marco; Beccaglia, Mario A Rojas; Mastantuono, Marco

    2013-01-01

    One of the reason for Latarjet procedure failure may be coracoid graft osteolysis. In this study, we aimed to understand if a better compression between the coracoid process and the glenoid, using a mini-plate fixation during the Latarjet procedure, could reduce the amount of coracoid graft osteolysis. A computed tomography scan analysis of 26 prospectively followed-up patients was conducted after modified Latarjet procedure using mini-plate fixation technique to determine both the location and the amount of coracoid graft osteolysis in them. We then compared our current results with results from that of our previous study without using mini-plate fixation to determine if there is any statistical significant difference in terms of corcacoid bone graft osteolysis between the two surgical techniques. The most relevant osteolysis was represented by the superficial part of the proximal coracoid, whereas the deep part of the proximal coracoid graft is least involved in osteolysis and has best bone healing. The current study showed a significant difference only for the deep part of the distal coracoid with our previous study (P < 0.01). To our knowledge, there are no studies in literature that show the causes of coracoid bone graft osteolysis after Latarjet procedure. Our study suggests that there is a significant difference only for the deep part of the distal coracoid in terms of osteolysis. At clinical examination, this difference did not correspond with any clinical findings. Level 4. Prospective case series, Treatment study.

  12. Enhanced Lighting Techniques and Augmented Reality to Improve Human Task Performance

    NASA Technical Reports Server (NTRS)

    Maida, James C.; Bowen, Charles K.; Pace, John W.

    2005-01-01

    One of the most versatile tools designed for use on the International Space Station (ISS) is the Special Purpose Dexterous Manipulator (SPDM) robot. Operators for this system are trained at NASA Johnson Space Center (JSC) using a robotic simulator, the Dexterous Manipulator Trainer (DMT), which performs most SPDM functions under normal static Earth gravitational forces. The SPDM is controlled from a standard Robotic Workstation. A key feature of the SPDM and DMT is the Force/Moment Accommodation (FMA) system, which limits the contact forces and moments acting on the robot components, on its payload, an Orbital Replaceable Unit (ORU), and on the receptacle for the ORU. The FMA system helps to automatically alleviate any binding of the ORU as it is inserted or withdrawn from a receptacle, but it is limited in its correction capability. A successful ORU insertion generally requires that the reference axes of the ORU and receptacle be aligned to within approximately 0.25 inch and 0.5 degree of nominal values. The only guides available for the operator to achieve these alignment tolerances are views from any available video cameras. No special registration markings are provided on the ORU or receptacle, so the operator must use their intrinsic features in the video display to perform the pre-insertion alignment task. Since optimum camera views may not be available, and dynamic orbital lighting conditions may limit viewing periods, long times are anticipated for performing some ORU insertion or extraction operations. This study explored the feasibility of using augmented reality (AR) to assist with SPDM operations. Geometric graphical symbols were overlaid on the end effector (EE) camera view to afford cues to assist the operator in attaining adequate pre-insertion ORU alignment.

  13. Iliosacral screw fixation of the unstable pelvic ring injuries.

    PubMed

    Rysavý, M; Pavelka, T; Khayarin, M; Dzupa, V

    2010-06-01

    controversial. Some authors in large trauma centres believe that ideally the initial treatment should be the final treatment. The advantage of urgent fixation is the use of this usually minimally invasive technique in the initial stabilisation of a hemodynamically unstable patient.The disadvantage is performance of the surgery under increased stress and time limit, which may lead to the acceptance of sub-optimal reduction. Very good team work of the orthopaedic surgeon, anaesthetist and other involved specialists (general surgeon, urologist) is necessary. Iliosacral screw fixation is a useful method of stabilizing unstable pelvic ring injuries. It is a difficult technique, with a steep learning curve. The surgeon must understand the complex and variable sacral anatomy. High quality fluoroscopic imaging is a must. Especially in vertically unstable injuries the sacroiliac screws need to be augmented by sound anterior fixation. Low rates of infection, wound healing problems and minimal blood loss are advantages of this method.

  14. Coracoid bone graft osteolysis after Latarjet procedure: A comparison study between two screws standard technique vs mini-plate fixation

    PubMed Central

    Giacomo, Giovanni Di; Costantini, Alberto; de Gasperis, Nicola; De Vita, Andrea; Lin, Bernard K. H.; Francone, Marco; Beccaglia, Mario A. Rojas; Mastantuono, Marco

    2013-01-01

    Aims: One of the reason for Latarjet procedure failure may be coracoid graft osteolysis. In this study, we aimed to understand if a better compression between the coracoid process and the glenoid, using a mini-plate fixation during the Latarjet procedure, could reduce the amount of coracoid graft osteolysis. Materials and Methods: A computed tomography scan analysis of 26 prospectively followed-up patients was conducted after modified Latarjet procedure using mini-plate fixation technique to determine both the location and the amount of coracoid graft osteolysis in them. We then compared our current results with results from that of our previous study without using mini-plate fixation to determine if there is any statistical significant difference in terms of corcacoid bone graft osteolysis between the two surgical techniques. Results: The most relevant osteolysis was represented by the superficial part of the proximal coracoid, whereas the deep part of the proximal coracoid graft is least involved in osteolysis and has best bone healing. The current study showed a significant difference only for the deep part of the distal coracoid with our previous study (P < 0.01). Discussion: To our knowledge, there are no studies in literature that show the causes of coracoid bone graft osteolysis after Latarjet procedure. Conclusion: Our study suggests that there is a significant difference only for the deep part of the distal coracoid in terms of osteolysis. At clinical examination, this difference did not correspond with any clinical findings. Level of Evidence: Level 4. Clinical Relevance: Prospective case series, Treatment study. PMID:23858288

  15. Screw insertion in osteoporotic bone: turn-of-the-nut and torque-based techniques provide similar resistance to bone plate slippage.

    PubMed

    Mears, Simon C; Langdale, Evan R; Belkoff, Stephen M

    2015-02-01

    To measure the resistance to plate slippage provided by a screw inserted to various torsional and rotational endpoints. A 7-hole, 3.5-mm narrow dynamic compression plate was affixed to an osteoporotic humeral shafts using screws inserted: (1) to 90 degrees after plate contact, (2) to 180 degrees after plate contact, (3) by the 1.4-N·m torque limit method, and (4) by the "2-fingers tight" method. The resistance of the plate to sliding against the bone was measured using a materials testing machine. We checked for an effect of screw insertion method on bone-plate slippage with a general linearized latent and mixed model, controlling for bone mineral density, sex, and specimen clustering. Significance was set at P < 0.05. The force required to slip the plate for 180 degrees of screw rotation was not significantly greater than that of the other insertion groups. Inserting screws 180 degrees after seating can be expected to yield plate contact to bone similar to that of the "2-fingers tight" standard.

  16. The use of extrapolation concepts to augment the Frequency Separation Technique

    NASA Astrophysics Data System (ADS)

    Alexiou, Spiros

    2015-03-01

    The Frequency Separation Technique (FST) is a general method formulated to improve the speed and/or accuracy of lineshape calculations, including strong overlapping collisions, as is the case for ion dynamics. It should be most useful when combined with ultrafast methods, that, however have significant difficulties when the impact regime is approached. These difficulties are addressed by the Frequency Separation Technique, in which the impact limit is correctly recovered. The present work examines the possibility of combining the Frequency Separation Technique with the addition of extrapolation to improve results and minimize errors resulting from the neglect of fast-slow coupling and thus obtain the exact result with a minimum of extra effort. To this end the adequacy of one such ultrafast method, the Frequency Fluctuation Method (FFM) for treating the nonimpact part is examined. It is found that although the FFM is unable to reproduce the nonimpact profile correctly, its coupling with the FST correctly reproduces the total profile.

  17. Fluorescence lifetime technique for surgical imaging, guidance and augmented reality (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Marcu, Laura

    2017-02-01

    The surgeon's limited ability to accurately delineate the tumor margin during surgical interventions is one key challenge in clinical management of cancer. New methods for guiding tumor resection decisions are needed. Numerous studies have shown that tissue autofluorescence properties have the potential to asses biochemical features associates with distinct pathologies in tissue and to distinguish various cancers from normal tissues. However, despite these promising reports, autofluorescence techniques were sparsely adopted in clinical settings. Moreover, when adopted they were primarily used for pre-operative diagnosis rather than guiding interventions. To address this need, we have researched and engineered instrumentation that utilizes label-free fluorescence lifetime contrast to characterize tissue biochemical features in vivo in patients and methodologies conducive to real-time (few seconds) diagnosis of tissue pathologies during surgical procedures. This presentation overviews clinically-compatible multispectral fluorescence lifetime imaging techniques developed in our laboratory and their ability to operate as stand-alone tools, integrated in a biopsy needle and in conjunction with the da Vinci surgical robot. We present pre-clinical and clinical studies in patients that demonstrate the potential of these techniques for intraoperative assessment of brain tumors and head and neck cancer. Current results demonstrate that intrinsic fluorescence signals can provide useful contrast for delineation distinct types of tissues including tumors intraoperatively. Challenges and solutions in the clinical implementation of these techniques are discussed.

  18. Surgical management of symptomatic os odontoideum with posterior screw fixation performed using the magerl and harms techniques with intraoperative 3-dimensional fluoroscopy-based navigation.

    PubMed

    Weng, Chong; Tian, Wei; Li, Zhi-Yu; Liu, Bo; Li, Qin; Wang, Yong-Qing; Sun, Yu-Zhen

    2012-10-01

    Retrospective case series. To evaluate the accuracy of screw fixation using intraoperative three-dimensional fluoroscopy-based navigation (ITFN) and to assess the clinical outcomes of this treatment regimen. The surgical management of symptomatic os odontoideum poses considerable difficulties due to the highly variable anatomy of the upper cervical spine and surrounding neurovascular structures. Various methods have been described for the treatment of symptomatic os odontoideum, all of which have limitations. Nineteen patients with symptomatic os odontoideum were investigated. Pain scores were assessed using the visual analogue scale. Myelopathy was assessed using the Nurick scale and Odom's criteria. Radiological imaging was carried out in all patients for diagnosis and to assess the atlantodens interval, space available for cord, and presence of intramedullary hyperintensity signals on T2-weighted images at the C1-C2 level. Posterior stabilization was performed for all patients by using ITFN. The mean Nurick score improved from 2.3 before surgery to 0.7 at the time of follow-up. The mean follow-up period was 34.7 months (range, 12-65 mo). According to Odom's criteria, outcomes were as follows: excellent, 47%; good, 37%; fair, 11%; and poor, 5%. All patients with preoperative neck pain had symptom relief or improvement, with all of these patients having more than 83.7% improvement in visual analogue scale scores. The mean preoperative space available for cord value of 9.3 mm improved to 17.7 mm. Solid fusion and reduction of atlantoaxial dislocation were achieved in every patient without screw failure. Sixty screws were placed in 19 patients. Two C2 polyaxial screws in 2 patients and 1 transarticular screw in 1 patient slightly penetrated the transverse foramen with no vascular injury and clinical sequelae. ITFN is a safe, accurate, and effective tool for screw placement in patients with symptomatic os odontoideum.

  19. Biomechanical comparison of 2 anterior cruciate ligament graft preparation techniques for tibial fixation: adjustable-length loop cortical button or interference screw.

    PubMed

    Mayr, Raul; Heinrichs, Christian Heinz; Eichinger, Martin; Coppola, Christian; Schmoelz, Werner; Attal, René

    2015-06-01

    Cortical button fixation at the femoral side and interference screws within the tibial bone tunnel are widely used for anterior cruciate ligament graft fixation. Using a bone socket instead of a full tunnel allows cortical button fixation on the tibial side as well. If adjustable-length loop cortical button devices are used for femoral and tibial fixation, the tendon graft has to be secured with sutures in a closed tendon loop. The increased distance of fixation points and potential slippage of the tendon strands at the securing sutures might lead to greater risk of postoperative graft elongation when compared with conventional graft preparation with tibial interference screw fixation. Compared with an anterior cruciate ligament graft with tibial adjustable-length loop cortical button fixation, a graft with tibial interference screw fixation will show less graft elongation during cyclic loading and lower ultimate failure loads. Controlled laboratory study. Grafts with tibial adjustable-length loop cortical button fixation and grafts with tibial interference screw fixation were biomechanically tested in calf tibiae (n = 10 per group). Femoral fixation was equivalent for both groups, using an adjustable-length loop cortical button. Specimens underwent cyclic loading followed by a load-to-failure test. Grafts with screw fixation showed significantly less initial elongation (cycles 1-5: 1.46 ± 0.26 mm), secondary elongation (cycles 6-1000: 1.87 ± 0.67 mm), and total elongation (cycles 1-1000: 3.33 ± 0.83 mm) in comparison with grafts with button fixation (2.47 ± 0.26, 3.56 ± 0.39, and 6.03 ± 0.61 mm, respectively) (P < .001). While pull-out stiffness was significantly higher for grafts with screw fixation (309.5 ± 33.2 vs 185.6 ± 16.4 N/mm) (P < .001), grafts with button fixation were able to withstand significantly higher ultimate failure loads (908 ± 74 vs 693 ± 119 N) (P < .001). Grafts with tibial adjustable-length loop cortical button fixation resulted

  20. Captive-rearing piping plovers: developing techniques to augment wild populations

    USGS Publications Warehouse

    Powell, A.N.; Cuthbert, F.J.; Wemmer, L.C.; Doolittle, A.

    1997-01-01

    Techniques for captive-rearing and releasing piping plovers (Charadrius melodus) were developed using a surrogate species, killdeer (Charadrius vociferus). We compared captive- and parent-reared killdeer, and parent-reared piping plovers and determined that growth and behavior were similar. After surrogate trials determined that captive-rearing was feasible, we used the same methods to raise piping plover chicks from salvaged eggs. For captive-reared chick of both species, survival to fledging was higher than and behaviors similar to parent-reared chicks in the wild. Rearing techniques were fine-tuned, and ten piping plover fledglings were released to the wild. Based on our results, we developed recommendations for captive-rearing piping plovers using salvaged eggs to enhance productivity of small populations.

  1. Captive-rearing piping plovers: Developing techniques to augment wild populations

    USGS Publications Warehouse

    Powell, A.N.; Cuthbert, F.J.; Wemmer, L.C.; Doolittle, A.W.; Feirer, S.T.

    1997-01-01

    Techniques for captive-rearing and releasing piping plovers (Charadrius melodus) were developed using a surrogate species, killdeer (Charadrius vociferus). We compared captive-and parent-reared killdeer, and parent-reared piping plovers and determined that growth and behavior were similar. After surrogate trials determined that captive-rearing was feasible, we used the same methods to raise piping plover chicks from salvaged eggs. For captive-reared chick of both species, survival to fledging was higher than and behaviors similar to parent-reared chicks in the wild. Rearing techniques were fine-tuned, and ten piping plover fledglings were released to the wild. Based on our results, we developed recommendations for captive-rearing piping plovers using salvaged eggs to enhance productivity of small populations. ?? 1997 Wiley-Liss, Inc.

  2. The use of computer vision techniques to augment home based sensorised environments.

    PubMed

    Uhríková, Zdenka; Nugent, Chris D; Hlavác, Václav

    2008-01-01

    Technology within the home environment is becoming widely accepted as a means to facilitate independent living. Nevertheless, practical issues of detecting different tasks between multiple persons within the same environment along with managing instances of uncertainty associated with recorded sensor data are two key challenges yet to be fully solved. This work presents details of how computer vision techniques can be used as both alternative and complementary means in the assessment of behaviour in home based sensorised environments. Within our work we assessed the ability of vision processing techniques in conjunction with sensor based data to deal with instances of multiple occupancy. Our Results indicate that the inclusion of the video data improved the overall process of task identification by detecting and recognizing multiple people in the environment using color based tracking algorithm.

  3. Two-stage closed sinus lift: a new surgical technique for maxillary sinus floor augmentation.

    PubMed

    Krasny, Kornel; Krasny, Marta; Kamiński, Artur

    2015-12-01

    Bone tissue atrophy may constitute a relative contraindication for implantation. The methods used in reconstruction of the alveolar ridge within the lateral section of the maxilla have been well known but not perfect. Presentation of the two-stage, closed sinus lift technique as well as efficacy evaluation of reconstruction of the alveolar ridge in the maxilla within its vertical dimension with the use of this technique. The total procedure was performed in 26 out of 28 patients qualified for the study. The height of the alveolar ridge at the site of the planned implantation was no <3 mm, the width of the ridge was no <5 mm. During the treatment stage 1 the sinus lift was performed for the first time. The created hollow was filled with allogeneic granulate. After 3-6 months stage 2 was performed consisting in another sinus lift with simultaneous implantation. The treatment was completed with prosthetic restoration after 6 months of osteointegration. In 24 out of 26 cases stage 1 was completed with the average ridge height of 7.2 mm. In stage 2, simultaneously with the second sinus lift, 26 implants were placed and no cases of sinusitis were found. In the follow-up period none of the implants were lost. The presented method is efficient and combines the benefits of the open technique-allowing treatment in cases of larger reduction of the vertical dimension and the closed technique-as it does not require opening of the maxillary sinus.

  4. The usefulness of electrical stimulation for assessing pedicle screw placements.

    PubMed

    Toleikis, J R; Skelly, J P; Carlvin, A O; Toleikis, S C; Bernard, T N; Burkus, J K; Burr, M E; Dorchak, J D; Goldman, M S; Walsh, T R

    2000-08-01

    The purpose of this study was to further establish the efficacy of pedicle screw stimulation as a monitoring technique to avoid nerve root injury during screw placement. The study population consisted of 662 patients in whom 3,409 pedicle screws were placed and tested by electrical stimulation. If stimulation resulted in a myogenic response at a stimulation intensity of 10 mA or less, the placement of the screw was inspected. Inspection was necessary for 3.9% of the screw placements in 15.4% of the study population. None of the patients in the study experienced any new postoperative neurologic deficits. These findings provide guidelines for the interpretation of stimulation data and support the use of this technique as an easy, inexpensive, and quick method to reliably assess screw placements and protecting neurological function.

  5. XEN-augmented Baerveldt: A New Surgical Technique for Refractory Glaucoma.

    PubMed

    D'Alessandro, Elisa; Guidotti, Jacopo M; Mansouri, Kaweh; Mermoud, André

    2017-02-01

    Glaucoma drainage devices have traditionally been reserved for patients with refractory glaucoma. However, these devices are prone to various sight-threatening complications. To prevent hypotony after placement of the Baerveldt tube, surgeons traditionally tie the tube with an absorbable suture until encapsulation occurs around the plate. We hypothesized that combining the XEN tube, placing it in the anterior chamber and connecting it to the Baerveldt tube posteriorly, outside the anterior chamber, would minimize 2 main potentially blinding complications: hypotony and corneal disease. To describe a new surgical technique for refractory glaucoma, combining both the Baerveldt and the XEN tubes in the same surgery. The Baerveldt implant was positioned in the superotemporal quadrant and sutured to the sclera. A scleral flap was executed extending from the anterior margin of the plate for the entire length of the tube to the limbus. The Baerveldt tube was correctly positioned by removing a deeper scleral flap. The XEN tube was then inserted ab externo and inserted into the Baerveldt tube's lumen. The newly formed double tube was then sutured and covered by the first scleral flap and usual suturing of the conjunctiva was performed. This technique is simple and potentially increases the safety of refractory glaucoma surgeries.

  6. "The missing LINX" for gastroesophageal reflux disease: Operative techniques video for the Linx magnetic sphincter augmentation procedure.

    PubMed

    Kuckelman, John P; Barron, Morgan R; Martin, Matthew J

    2017-05-01

    In 2012 the FDA approved a magnetic sphincter augmentation (MSA) device (LINX, Torax Medical, Inc) for placement around the lower esophageal sphincter as an alternative approach to fundoplication for gastroesophageal reflux disease (GERD). This is a relatively new procedure and there is not widespread familiarization with the standard indications and techniques of device placement. We present two operative videos to highlight the standard surgical technique and technical points needed for successful LINX placement. First will be placement in a standard indications setting of uncomplicated GERD with no hiatal hernia. Second will be placement with complicated anatomy due to alterations from prior gastric surgery and a hiatal hernia. Our experience has revealed that the LINX device can be placed safely in patients with normal or significantly altered anatomy but requires adherence to several key principles and technical points. This procedure offers a new option that is anatomically and physiologically unique compared to standard fundoplication, and that offers highly effective control of GERD with a less invasive approach. Published by Elsevier Inc.

  7. Modification of mandibular ridge splitting technique for horizontal augmentation of atrophic ridges

    PubMed Central

    Abu Tair, Jawad A.

    2014-01-01

    Purpose: A two stage approach of ridge splitting and lateral expansion in the mandible to achieve enough bone width for the purpose of dental implants is presented. Materials and Methods: A total of 13 consecutive patients with 16 long-span edentulous areas of the mandibular ridge were included in this study and 42 dental implants were inserted. Corticotomy of a rectangular buccal segment was carried out followed by 3 weeks of recovery; the mandibular ridge was stretched laterally, leaving the buccal periosteum attached to the lateralized segment. In this modification, there was no need for the use of grafted foreign materials to fill the defect and neither the use of barrier membranes, since it was treated practically as a fresh extraction site. To prevent the undesirable movement of the lateral plate, a small chip (2-3 mm in diameter) of bone spacer was properly fixed. The dental implants were placed 3-5 months later on. Results: Approximately, 86% of the expanded areas were successful in providing an adequate width to accommodate an implant. The average gain in width was 3.22 ± 0.97 mm. All intended implants were inserted. Prosthetic loading with fixed prosthesis was successfully implemented in all cases. Conclusion: This modified technique is a simple and short procedure with satisfactory results and minimal morbidity. Of note, this approach is devoid of foreign materials usage and has a low rate cost, therefore, should be employed more often. PMID:24987593

  8. Alveolar ridge augmentation by connective tissue grafting using a pouch method and modified connective tissue technique: A prospective study

    PubMed Central

    Agarwal, Ashish; Gupta, Narinder Dev

    2015-01-01

    Background: Localized alveolar ridge defect may create physiological and pathological problems. Developments in surgical techniques have made it simpler to change the configuration of a ridge to create a more aesthetic and more easily cleansable shape. The purpose of this study was to compare the efficacy of alveolar ridge augmentation using a subepithelial connective tissue graft in pouch and modified connective tissue graft technique. Materials and Methods: In this randomized, double blind, parallel and prospective study, 40 non-smoker individuals with 40 class III alveolar ridge defects in maxillary anterior were randomly divided in two groups. Group I received modified connective tissue graft, while group II were treated with subepithelial connective tissue graft in pouch technique. The defect size was measured in its horizontal and vertical dimension by utilizing a periodontal probe in a stone cast at base line, after 3 months, and 6 months post surgically. Analysis of variance and Bonferroni post-hoc test were used for statistical analysis. A two-tailed P < 0.05 was considered to be statistically significant. Results: Mean values in horizontal width after 6 months were 4.70 ± 0.87 mm, and 4.05 ± 0.89 mm for group I and II, respectively. Regarding vertical heights, obtained mean values were 4.75 ± 0.97 mm and 3.70 ± 0.92 mm for group I and group II, respectively. Conclusion: Within the limitations of this study, connective tissue graft proposed significantly more improvement as compare to connective tissue graft in pouch. PMID:26759591

  9. Application of an adaptive control grid interpolation technique to MR data set augmentation aimed at morphological vascular reconstruction

    NASA Astrophysics Data System (ADS)

    Frakes, David; Sinotte, Christopher M.; Conrad, Christopher P.; Healy, Timothy M.; Shiva, Sharma; Fogel, Mark A.; Monaco, Joseph W.; Smith, Mark J. T.; Yoganathan, Ajit P.

    2002-05-01

    The total cavopulmonary connection (TCPC) is a palliative surgical repair performed on children with a single ventricle (SV) physiology. Much of the power produced by the resultant single ventricle pump is consumed in the systemic circulation. Consequently the minimization of power loss in the TCPC is imperative for optimal surgical outcome. Toward this end we have developed a method of vascular morphology reconstruction based on adaptive control grid interpolation (ACGI) to function as a precursor to computational fluid dynamics (CFD) analysis aimed at quantifying power loss. Our technique combines positive aspects of optical flow-based and block-based motion estimation algorithms to accurately augment insufficiently dense Magnetic Resonance (MR) data sets with a minimal degree of computational complexity. The resulting enhanced data sets are used to reconstruct vascular geometries, and the subsequent reconstructions can then be used in conjunction with CFD simulations to offer th pressure and velocity information necessary to quantify power loss in the TCPC. Collectively these steps form a tool that transforms conventional MR data into more powerful information allowing surgical planning aimed at producing optimal TCPC configurations for successful surgical outcomes.

  10. Using Mitrofanoff's principle and Monti's technique as a surgical option for bladder augmentation with a continent stoma: a case report

    PubMed Central

    2011-01-01

    Introduction Hydronephrosis, reflux and renal failure are serious complications that occur in patients with neurogenic bladder associated with myelomeningocele. When the bladder compliance is lost, it is imperative to carry out surgery aimed at reducing bladder storage pressure. An ileocystoplasty, and for patients not suitable for intermittent catheterization, using the Mitrofanoff principle to form a continent stoma and the subsequent closure of the bladder neck, can be used. We report here, for the first time to the best of our knowledge, an association between two previously described techniques (the Mitrofanoff principle and the technique of Monti), that can solve the problem of a short appendix in obese patients. Case presentation A 33-year-old male Caucasian patient with myelomeningocele and neurogenic bladder developed low bladder compliance (4.0 mL/cm H2O) while still maintaining normal renal function. A bladder augmentation (ileocystoplasty) with continent derivation principle (Mitrofanoff) was performed. During surgery, we found that the patient's appendix was too short and was insufficient to reach the skin. We decided to make an association between the Mitrofanoff conduit and the ileal technique of Monti, through which we performed an anastomosis of the distal stump of the appendix to the bladder (with an antireflux valve). Later, the proximal stump of the appendix was anastomosed to an ileal segment of 2.0 cm that was open longitudinally and reconfigured transversally (Monti technique), modeled by a 12-Fr urethral catheter, and finally, the distal stump was sutured at the patient's navel. After the procedure, a suprapubic cystostomy (22 Fr) and a Foley catheter (10 Fr) through the continent conduit were left in place. The patient had recovered well and was discharged on the tenth day after surgery. He remained with the Foley catheter (through the conduit) for 21 days and cystostomy for 30 days. Six months after surgery he was continent with good

  11. Using Mitrofanoff's principle and Monti's technique as a surgical option for bladder augmentation with a continent stoma: a case report.

    PubMed

    Cassini, Marcelo F; Rodrigues, Antonio A; Tucci, Silvio; Cologna, Adauto J; Reis, Rodolfo B; Martins, Antonio Cp; Suaid, Haylton J

    2011-02-03

    Hydronephrosis, reflux and renal failure are serious complications that occur in patients with neurogenic bladder associated with myelomeningocele. When the bladder compliance is lost, it is imperative to carry out surgery aimed at reducing bladder storage pressure. An ileocystoplasty, and for patients not suitable for intermittent catheterization, using the Mitrofanoff principle to form a continent stoma and the subsequent closure of the bladder neck, can be used. We report here, for the first time to the best of our knowledge, an association between two previously described techniques (the Mitrofanoff principle and the technique of Monti), that can solve the problem of a short appendix in obese patients. A 33-year-old male Caucasian patient with myelomeningocele and neurogenic bladder developed low bladder compliance (4.0 mL/cm H2O) while still maintaining normal renal function. A bladder augmentation (ileocystoplasty) with continent derivation principle (Mitrofanoff) was performed. During surgery, we found that the patient's appendix was too short and was insufficient to reach the skin. We decided to make an association between the Mitrofanoff conduit and the ileal technique of Monti, through which we performed an anastomosis of the distal stump of the appendix to the bladder (with an antireflux valve). Later, the proximal stump of the appendix was anastomosed to an ileal segment of 2.0 cm that was open longitudinally and reconfigured transversally (Monti technique), modeled by a 12-Fr urethral catheter, and finally, the distal stump was sutured at the patient's navel.After the procedure, a suprapubic cystostomy (22 Fr) and a Foley catheter (10 Fr) through the continent conduit were left in place. The patient had recovered well and was discharged on the tenth day after surgery. He remained with the Foley catheter (through the conduit) for 21 days and cystostomy for 30 days. Six months after surgery he was continent with good bladder compliance without reflux and

  12. Midline Lumbar Fusion with Cortical Bone Trajectory Screw

    PubMed Central

    MIZUNO, Masaki; KURAISHI, Keita; UMEDA, Yasuyuki; SANO, Takanori; TSUJI, Masanori; SUZUKI, Hidenori

    2014-01-01

    A novel cortical bone trajectory (CBT) screw technique provides an alternative fixation technique for lumbar spine. Trajectory of CBT screw creates a caudo-cephalad path in sagittal plane and a medio-lateral path in axial plane, and engages cortical bone in the pedicle. The theoretical advantage is that it provides enhanced screw grip and interface strength. Midline lumbar fusion (MIDLF) is composed of posterior mid-line approach, microsurgical laminectomy, and CBT screw fixation. We adopted the MIDLF technique for lumbar spondylolisthesis. Advantages of this technique include that decompression and fusion are available in the same field, and it minimizes approach-related damages. To determine whether MIDLF with CBT screw is as effective as traditional approach and it is minimum invasive technique, we studied the clinical and radiological outcomes of MIDLF. Our results indicate that MIDLF is effective and minimum invasive technique. Evidence of effectiveness of MIDLF is that patients had good recovery score, and that CBT screw technique was safety in clinical and stable in radiological. MIDLF with CBT screw provides the surgeon with additional options for fixation. This technique is most likely to be useful for treating lumbar spondylolisthesis in combination with midline decompression and insertion of an interbody graft, such as the transforaminal lumbar interbody fusion or posterior lumbar interbody fusion techniques. PMID:25169139

  13. Improvement of Implant Placement after Bone Augmentation of Severely Resorbed Maxillary Sinuses with 'Tent-Pole' Grafting Technique in Combination with rhBMP-2.

    PubMed

    Zhang, Qiao; Zhang, Li Li; Yang, Yang; Lin, Yi Zhen; Miron, Richard J; Zhang, Yu Feng

    To study the clinical effect of short implant placement using osteotome sinus floor elevation technique and tent-pole grafting technique with recombinant human bone morphogenetic protein 2 (rhBMP-2) in severely resorbed maxillary area. Eleven patients with insufficient bone height in the posterior maxillary area were included. According to the native bone height and crown height space (CHS), the patients were divided into two groups: immediate placement of short implants with simultaneous bone augmentation (group A, 5 patients) and delayed dental implant placement (4 to 6 months) after bone augmentation. The rhBMP-2 was added into a deproteinised bovine bone mineral (DBBM) bone grafting material to shorten the treatment procedure and enhance the final effect of bone augmentation in both groups. Tent-pole grafting technique was applied for vertical bone augmentation in group B (6 patients). The success rate of the implants placed was 100% in both groups. In group A, the short implants treatment was successful, with a vertical gain of 1.5 to 6.4 mm in bone height after 4 to 6 months. In group B, the tent-pole grafting procedure in combination with DBBM and rhBMP-2 increased vertical bone height between 3.1 and 8.1 mm, an optimistic and adequate increase for implant placement. This bone increase was maintained following implant placement and final crown placement in the maxillary region (3.5 to 7.3 mm). The tent-pole grafting technique was a viable alternative choice to lateral sinus floor elevation in cases with excessive CHS. The application of rhBMP-2 with a shortened treatment time demonstrated positive outcomes in sinus floor augmentation procedures.

  14. Impact of screw configuration on the particle size distribution of granules produced by twin screw granulation.

    PubMed

    Vercruysse, J; Burggraeve, A; Fonteyne, M; Cappuyns, P; Delaet, U; Van Assche, I; De Beer, T; Remon, J P; Vervaet, C

    2015-02-01

    Twin screw granulation (TSG) has been reported by different research groups as an attractive technology for continuous wet granulation. However, in contrast to fluidized bed granulation, granules produced via this technique typically have a wide and multimodal particle size distribution (PSD), resulting in suboptimal flow properties. The aim of the current study was to evaluate the impact of granulator screw configuration on the PSD of granules produced by TSG. Experiments were performed using a 25 mm co-rotating twin screw granulator, being part of the ConsiGma™-25 system (a fully continuous from-powder-to-tablet manufacturing line from GEA Pharma Systems). Besides the screw elements conventionally used for TSG (conveying and kneading elements), alternative designs of screw elements (tooth-mixing-elements (TME), screw mixing elements (SME) and cutters) were investigated using an α-lactose monohydrate formulation granulated with distilled water. Granulation with only conveying elements resulted in wide and multimodal PSD. Using kneading elements, the width of the PSD could be partially narrowed and the liquid distribution was more homogeneous. However, still a significant fraction of oversized agglomerates was obtained. Implementing additional kneading elements or cutters in the final section of the screw configuration was not beneficial. Furthermore, granulation with only TME or SME had limited impact on the width of the PSD. Promising results were obtained by combining kneading elements with SME, as for these configurations the PSD was narrower and shifted to the size fractions suitable for tableting.

  15. Pedicle screw fixation combined with intermediate screw at the fracture level for treatment of thoracolumbar fractures

    PubMed Central

    Li, Kunpeng; Zhang, Wen; Liu, Dan; Xu, Hui; Geng, Wei; Luo, Dawei; Ma, Jinzhu

    2016-01-01

    .01; P = 0.06). Conclusions: The combined screw fixation technique was associated with better reduction of the fractured vertebrae, less correction loss in the follow-up, and lower implant failure rate. Given the lack of robust clinical evidence, these findings warrant verification in large prospective registries and randomized trials with long-term follow-up. PMID:27537586

  16. Accurate and Simple Screw Insertion Procedure With Patient-Specific Screw Guide Templates for Posterior C1-C2 Fixation.

    PubMed

    Sugawara, Taku; Higashiyama, Naoki; Kaneyama, Shuichi; Sumi, Masatoshi

    2017-03-15

    Prospective clinical trial of the screw insertion method for posterior C1-C2 fixation utilizing the patient-specific screw guide template technique. To evaluate the efficacy of this method for insertion of C1 lateral mass screws (LMS), C2 pedicle screws (PS), and C2 laminar screws (LS). Posterior C1LMS and C2PS fixation, also known as the Goel-Harms method, can achieve immediate rigid fixation and high fusion rate, but the screw insertion carries the risk of injury to neuronal and vascular structures. Dissection of venous plexus and C2 nerve root to confirm the insertion point of the C1LMS may also cause problems. We have developed an intraoperative screw guiding method using patient-specific laminar templates. Preoperative bone images of computed tomography (CT) were analyzed using three-dimensional (3D)/multiplanar imaging software to plan the trajectories of the screws. Plastic templates with screw guiding structures were created for each lamina using 3D design and printing technology. Three types of templates were made for precise multistep guidance, and all templates were specially designed to fit and lock on the lamina during the procedure. Surgery was performed using this patient-specific screw guide template system, and placement of the screws was postoperatively evaluated using CT. Twelve patients with C1-C2 instability were treated with a total of 48 screws (24 C1LMS, 20 C2PS, 4 C2LS). Intraoperatively, each template was found to exactly fit and lock on the lamina and screw insertion was completed successfully without dissection of the venous plexus and C2 nerve root. Postoperative CT showed no cortical violation by the screws, and mean deviation of the screws from the planned trajectories was 0.70 ± 0.42 mm. The multistep, patient-specific screw guide template system is useful for intraoperative screw navigation in posterior C1-C2 fixation. This simple and economical method can improve the accuracy of screw insertion, and reduce operation time and

  17. Three-dimensional comparison of alternative screw positions versus actual fixation of scaphoid fractures.

    PubMed

    Volk, Ido; Gal, Jonathan; Peleg, Eran; Almog, Gil; Luria, Shai

    2017-06-01

    The recommended technique for the fixation of a scaphoid waist fracture involves a headless compression screw placed in the proximal fragment center. This is usually accomplished by placing a longitudinal axis screw as visualized by fluoroscopy. The screw length has been shown to have a biomechanical advantage. An alternative to these options, which has been debated in the literature, is a screw placed perpendicular to the fracture plane and in its center. The perpendicular screw may have a biomechanical advantage despite the fact that it may be shorter. This study examined the differences in location and length in actual patients between a screw in the center of the proximal fragment with a longitudinal axis screw, and the actual fixating screw. These were then compared to a perpendicular axis screw. Pre- and post-operative CT scans of 10 patients with scaphoid waist fractures were evaluated using a 3D computer model. Comparisons were made between the length, location and angle of actual and virtual screw alternatives; namely, a screw along the central third of the proximal fragment (central screw axis) where the scaphoid longitudinal axis was calculated mathematically (longitudinal screw axis) and a screw placed at 90° to the fracture plane and in its center (perpendicular screw axis). The longitudinal axis screw was found to be significantly longer than the other axes (28.3mm). There was a significant difference between the perpendicular axis screw and the location and angle of the other screw axis, but it was only shorter than the longitudinal screw (23.6mm versus 25.5mm for the actual screw; ns.). A computed longitudinal axis screw is longer than a central or actual screw placed longitudinally by visual inspection by the surgeon. Although it needs to be placed using computer assisted (CAS) techniques, it may have the biomechanical advantages of a longer screw in a similar trajectory. The perpendicular screw was found to be significantly different in position

  18. A biomechanical comparison of facet screw fixation and pedicle screw fixation: effects of short-term and long-term repetitive cycling.

    PubMed

    Ferrara, Lisa A; Secor, Jessica L; Jin, Byung-Ho; Wakefield, Andrew; Inceoglu, Serkan; Benzel, Edward C

    2003-06-15

    A biomechanical study was conducted to assess the stabilization performance of transfacet pedicle screw fixation. To compare the biomechanical effects of short-term and long-term cyclic loading on lumbar motion segments instrumented with either a pedicle screw or a transfacet pedicle screw construct. Facet screw fixation is an alternative to pedicle screw fixation that permits the use of a minimally invasive strategy. It is not known whether facet screw fixation can provide stability equivalent to pedicle screw fixation during cyclical loading. Therefore, transfacet pedicle screw fixation and standard pedicle screw fixation techniques were compared biomechanically. Lumbar motion segments were tested under short-term and long-term cyclic loading conditions. For the short-term phase, specimens were tested intact for six cycles (to 400 N or 4 Nm) in compression, flexion, extension, lateral bending, and torsion. The specimens then were instrumented with bilateral semicircular interbody spacers and pedicle screw instrumentation or transfacet pedicle screws, and the testing sequence was repeated. For the long-term phase, 12 specimens were instrumented in a similar manner and loaded to 6 Nm of flexion bending for 180,000 cycles. For the short-term phase, both fixation systems had significantly greater stiffness and reduced range of motion, as compared with the intact state. No differences were observed between the fixation systems except in flexion, wherein transfacet pedicle screw specimens were significantly stiffer than traditional pedicle screw specimens. For the long-term phase, the stiffness and range of motion did not significantly increase or decrease over repetitive cycling of the instrumented specimens. Furthermore, no significant difference between the fixation systems was observed. The stability provided by both transfacet pedicle screw fixation and traditional pedicle screw fixation was not compromised after repetitive cycling. In this model, transfacet

  19. Development and Testing of X-Ray Imaging-Enhanced Poly-L-Lactide Bone Screws.

    PubMed

    Chang, Wei-Jen; Pan, Yu-Hwa; Tzeng, Jy-Jiunn; Wu, Ting-Lin; Fong, Tsorng-Harn; Feng, Sheng-Wei; Huang, Haw-Ming

    2015-01-01

    Nanosized iron oxide particles exhibit osteogenic and radiopaque properties. Thus, iron oxide (Fe3O4) nanoparticles were incorporated into a biodegradable polymer (poly-L-lactic acid, PLLA) to fabricate a composite bone screw. This multifunctional, 3D printable bone screw was detectable on X-ray examination. In this study, mechanical tests including three-point bending and ultimate tensile strength were conducted to evaluate the optimal ratio of iron oxide nanoparticles in the PLLA composite. Both injection molding and 3D printing techniques were used to fabricate the PLLA bone screws with and without the iron oxide nanoparticles. The fabricated screws were implanted into the femoral condyles of New Zealand White rabbits. Bone blocks containing the PLLA screws were resected 2 and 4 weeks after surgery. Histologic examination of the surrounding bone and the radiopacity of the iron-oxide-containing PLLA screws were evaluated. Our results indicated that addition of iron oxide nanoparticles at 30% significantly decreased the ultimate tensile stress properties of the PLLA screws. The screws with 20% iron oxide exhibited strong radiopacity compared to the screws fabricated without the iron oxide nanoparticles. Four weeks after surgery, the average bone volume of the iron oxide PLLA composite screws was significantly greater than that of PLLA screws without iron oxide. These findings suggested that biodegradable and X-ray detectable PLLA bone screws can be produced by incorporation of 20% iron oxide nanoparticles. Furthermore, these screws had significantly greater osteogenic capability than the PLLA screws without iron oxide.

  20. Development and Testing of X-Ray Imaging-Enhanced Poly-L-Lactide Bone Screws

    PubMed Central

    Tzeng, Jy-Jiunn; Wu, Ting-Lin; Fong, Tsorng-Harn; Feng, Sheng-Wei; Huang, Haw-Ming

    2015-01-01

    Nanosized iron oxide particles exhibit osteogenic and radiopaque properties. Thus, iron oxide (Fe3O4) nanoparticles were incorporated into a biodegradable polymer (poly-L-lactic acid, PLLA) to fabricate a composite bone screw. This multifunctional, 3D printable bone screw was detectable on X-ray examination. In this study, mechanical tests including three-point bending and ultimate tensile strength were conducted to evaluate the optimal ratio of iron oxide nanoparticles in the PLLA composite. Both injection molding and 3D printing techniques were used to fabricate the PLLA bone screws with and without the iron oxide nanoparticles. The fabricated screws were implanted into the femoral condyles of New Zealand White rabbits. Bone blocks containing the PLLA screws were resected 2 and 4 weeks after surgery. Histologic examination of the surrounding bone and the radiopacity of the iron-oxide-containing PLLA screws were evaluated. Our results indicated that addition of iron oxide nanoparticles at 30% significantly decreased the ultimate tensile stress properties of the PLLA screws. The screws with 20% iron oxide exhibited strong radiopacity compared to the screws fabricated without the iron oxide nanoparticles. Four weeks after surgery, the average bone volume of the iron oxide PLLA composite screws was significantly greater than that of PLLA screws without iron oxide. These findings suggested that biodegradable and X-ray detectable PLLA bone screws can be produced by incorporation of 20% iron oxide nanoparticles. Furthermore, these screws had significantly greater osteogenic capability than the PLLA screws without iron oxide. PMID:26466309

  1. Finite element analysis of osteosynthesis screw fixation in the bone stock: an appropriate method for automatic screw modelling.

    PubMed

    Wieding, Jan; Souffrant, Robert; Fritsche, Andreas; Mittelmeier, Wolfram; Bader, Rainer

    2012-01-01

    The use of finite element analysis (FEA) has grown to a more and more important method in the field of biomedical engineering and biomechanics. Although increased computational performance allows new ways to generate more complex biomechanical models, in the area of orthopaedic surgery, solid modelling of screws and drill holes represent a limitation of their use for individual cases and an increase of computational costs. To cope with these requirements, different methods for numerical screw modelling have therefore been investigated to improve its application diversity. Exemplarily, fixation was performed for stabilization of a large segmental femoral bone defect by an osteosynthesis plate. Three different numerical modelling techniques for implant fixation were used in this study, i.e. without screw modelling, screws as solid elements as well as screws as structural elements. The latter one offers the possibility to implement automatically generated screws with variable geometry on arbitrary FE models. Structural screws were parametrically generated by a Python script for the automatic generation in the FE-software Abaqus/CAE on both a tetrahedral and a hexahedral meshed femur. Accuracy of the FE models was confirmed by experimental testing using a composite femur with a segmental defect and an identical osteosynthesis plate for primary stabilisation with titanium screws. Both deflection of the femoral head and the gap alteration were measured with an optical measuring system with an accuracy of approximately 3 µm. For both screw modelling techniques a sufficient correlation of approximately 95% between numerical and experimental analysis was found. Furthermore, using structural elements for screw modelling the computational time could be reduced by 85% using hexahedral elements instead of tetrahedral elements for femur meshing. The automatically generated screw modelling offers a realistic simulation of the osteosynthesis fixation with screws in the adjacent

  2. Finite Element Analysis of Osteosynthesis Screw Fixation in the Bone Stock: An Appropriate Method for Automatic Screw Modelling

    PubMed Central

    Wieding, Jan; Souffrant, Robert; Fritsche, Andreas; Mittelmeier, Wolfram; Bader, Rainer

    2012-01-01

    The use of finite element analysis (FEA) has grown to a more and more important method in the field of biomedical engineering and biomechanics. Although increased computational performance allows new ways to generate more complex biomechanical models, in the area of orthopaedic surgery, solid modelling of screws and drill holes represent a limitation of their use for individual cases and an increase of computational costs. To cope with these requirements, different methods for numerical screw modelling have therefore been investigated to improve its application diversity. Exemplarily, fixation was performed for stabilization of a large segmental femoral bone defect by an osteosynthesis plate. Three different numerical modelling techniques for implant fixation were used in this study, i.e. without screw modelling, screws as solid elements as well as screws as structural elements. The latter one offers the possibility to implement automatically generated screws with variable geometry on arbitrary FE models. Structural screws were parametrically generated by a Python script for the automatic generation in the FE-software Abaqus/CAE on both a tetrahedral and a hexahedral meshed femur. Accuracy of the FE models was confirmed by experimental testing using a composite femur with a segmental defect and an identical osteosynthesis plate for primary stabilisation with titanium screws. Both deflection of the femoral head and the gap alteration were measured with an optical measuring system with an accuracy of approximately 3 µm. For both screw modelling techniques a sufficient correlation of approximately 95% between numerical and experimental analysis was found. Furthermore, using structural elements for screw modelling the computational time could be reduced by 85% using hexahedral elements instead of tetrahedral elements for femur meshing. The automatically generated screw modelling offers a realistic simulation of the osteosynthesis fixation with screws in the adjacent

  3. Ball Screw Actuator Including a Compliant Ball Screw Stop

    NASA Technical Reports Server (NTRS)

    Wingett, Paul T. (Inventor); Hanlon, Casey (Inventor)

    2015-01-01

    An actuator includes a ball nut, a ball screw, and a ball screw stop. The ball nut is adapted to receive an input torque and in response rotates and supplies a drive force. The ball screw extends through the ball nut and has a first end and a second end. The ball screw receives the drive force from the ball nut and in response selectively translates between a retract position and a extend position. The ball screw stop is mounted on the ball screw proximate the first end to translate therewith. The ball screw stop engages the ball nut when the ball screw is in the extend position, translates, with compliance, a predetermined distance toward the first end upon engaging the ball nut, and prevents further rotation of the ball screw upon translating the predetermined distance.

  4. Ball Screw Actuator Including a Compliant Ball Screw Stop

    NASA Technical Reports Server (NTRS)

    Wingett, Paul T. (Inventor); Hanlon, Casey (Inventor)

    2017-01-01

    An actuator includes a ball nut, a ball screw, and a ball screw stop. The ball nut is adapted to receive an input torque and in response rotates and supplies a drive force. The ball screw extends through the ball nut and has a first end and a second end. The ball screw receives the drive force from the ball nut and in response selectively translates between a retract position and a extend position. The ball screw stop is mounted on the ball screw proximate the first end to translate therewith. The ball screw stop engages the ball nut when the ball screw is in the extend position, translates, with compliance, a predetermined distance toward the first end upon engaging the ball nut, and prevents further rotation of the ball screw upon translating the predetermined distance.

  5. Subfascial gluteal augmentation.

    PubMed

    de la Peña, J Abel; Rubio, Omar V; Cano, Jacobo P; Cedillo, Mariana C; Garcés, Miriam T

    2006-07-01

    Developing the concept of gluteal augmentation through the past 17 years has been an academic adventure. During these years my coworkers and I have progressively improved surgical technique and devised an anatomical system for gluteal augmentation that includes an ideal implant design and templates to assist in evaluating patients in the preoperative period and to identify the most appropriate implant size.

  6. A minimally invasive surgical technique for augmented reconstruction of the lateral ankle ligaments with woven polyester tape.

    PubMed

    Jones, Alex P; Sidhom, Sameh; Sefton, Graham

    2007-01-01

    Although stabilization of the lateral ankle ligament complex (LALC) with augmented techniques is known to be successful, it is associated with a number of complications. We hypothesize that successful stabilization of LALC can be achieved with a woven polyester tape implant via a minimally invasive procedure, as an alternative to tenodesis. Four men with chronic instability of the ankle underwent a minimally invasive surgical stabilization of LALC with a woven polyester tape. This tape was passed through the distal fibula to the base of the fifth metatarsal and then back to the fibula once more before being tied. The foot was immobilized in a neutral position for 2 weeks. Partial weightbearing with a walking stick began on the same day, and physiotherapy began for 10 weeks. Evaluation was performed at a mean follow-up of 24.5 months postoperatively. Preoperatively, all patients had a chronically unstable index ankle both functionally and clinically. At a mean of 24.5 months postoperatively, functional stability for all patients was normal (Sefton grade 1). Subjective ankle performance grades were normal in all cases, and all patients felt the outcome was excellent. Objective measurement with clinical stress testing showed anterior drawer and inversion tests to be the same as the contralateral ankle in all patients. However, each displayed limited inversion of the ankle. No complications such as wound dehiscence, infection, pain, or nerve injury were observed after the procedure. All were able to return to their preinjury activity level within 3 months. Stabilization of LALC may be simply and successfully achieved with a woven polyester graft as an alternative to tenodesis.

  7. Pull-out strength of cemented solid versus fenestrated pedicle screws in osteoporotic vertebrae

    PubMed Central

    Leichtle, C. I.; Rothstock, S.; Happel, J.; Walter, F.; Shiozawa, T.; Leichtle, U. G.

    2016-01-01

    Objectives Cement augmentation of pedicle screws could be used to improve screw stability, especially in osteoporotic vertebrae. However, little is known concerning the influence of different screw types and amount of cement applied. Therefore, the aim of this biomechanical in vitro study was to evaluate the effect of cement augmentation on the screw pull-out force in osteoporotic vertebrae, comparing different pedicle screws (solid and fenestrated) and cement volumes (0 mL, 1 mL or 3 mL). Materials and Methods A total of 54 osteoporotic human cadaver thoracic and lumbar vertebrae were instrumented with pedicle screws (uncemented, solid cemented or fenestrated cemented) and augmented with high-viscosity PMMA cement (0 mL, 1 mL or 3 mL). The insertion torque and bone mineral density were determined. Radiographs and CT scans were undertaken to evaluate cement distribution and cement leakage. Pull-out testing was performed with a material testing machine to measure failure load and stiffness. The paired t-test was used to compare the two screws within each vertebra. Results Mean failure load was significantly greater for fenestrated cemented screws (+622 N; p ⩽ 0.001) and solid cemented screws (+460 N; p ⩽ 0.001) than for uncemented screws. There was no significant difference between the solid and fenestrated cemented screws (p = 0.5). In the lower thoracic vertebrae, 1 mL cement was enough to significantly increase failure load, while 3 mL led to further significant improvement in the upper thoracic, lower thoracic and lumbar regions. Conclusion Conventional, solid pedicle screws augmented with high-viscosity cement provided comparable screw stability in pull-out testing to that of sophisticated and more expensive fenestrated screws. In terms of cement volume, we recommend the use of at least 1 mL in the thoracic and 3 mL in the lumbar spine. Cite this article: C. I. Leichtle, A. Lorenz, S. Rothstock, J. Happel, F. Walter, T. Shiozawa, U. G. Leichtle. Pull

  8. Comparing Different Surgical Techniques for Addressing the Posterior Malleolus in Supination External Rotation Ankle Fractures and the Need for Syndesmotic Screw Fixation.

    PubMed

    Li, Mengnai; Collier, Rachel C; Hill, Brian W; Slinkard, Nathaniel; Ly, Thuan V

    Trimalleolar ankle fractures are unstable injuries with possible syndesmotic disruption. Recent data have described inherent morbidity associated with screw fixation of the syndesmosis, including the potential for malreduction, hardware irritation, and post-traumatic arthritis. The posterior malleolus is an important soft tissue attachment for the posterior inferior syndesmosis ligament. We hypothesized that fixation of a sizable posterior malleolar (PM) fracture in supination external rotation type IV (SER IV) ankle fractures would act to stabilize the syndesmosis and minimize or eliminate the need for trans-syndesmotic fixation. A retrospective review of trimalleolar ankle fractures surgically treated from October 2006 to April of 2011 was performed. A total of 143 trimalleolar ankle fractures were identified, and 97 were classified as SER IV. Of the 97 patients, 74 (76.3%) had a sizable PM fragment. Syndesmotic fixation was required in 7 of 34 (20%) and 27 of 40 (68%), respectively, when the PM was fixed versus not fixed (p = .0002). When the PM was indirectly reduced using an anterior to posterior screw, 7 of 15 patients (46.7%) required syndesmotic fixation compared with none of 19 patients when the PM fragment was fixated with direct posterior lateral plate fixation (p = .0012). Fixation of the PM fracture in SER IV ankle fractures can restore syndesmotic stability and, thus, lower the rate of syndesmotic fixation. We found that fixation of a sizable PM fragment in SER IV or equivalent injuries through posterolateral plating can eliminate the need for syndesmotic screw fixation. Copyright © 2017 American College of Foot and Ankle Surgeons. Published by Elsevier Inc. All rights reserved.

  9. [Craniofacial augmentation with porous polyethylene implants (Medpor: first clinical results].

    PubMed

    Gosau, M; Schiel, S; Draenert, G F; Ihrler, S; Mast, G; Ehrenfeld, M

    2006-05-01

    Porous polyethylene (Medpor) is an alloplastic material commonly used in craniofacial reconstruction. We report about our first clinical experiences with Medpor for facial augmentation procedures. We treated 27 patients between 2001 and 2005 (11 female, 16 male) with 48 Medpor-implants. The indications for application of porous polyethylene implants in our clinic were congenital malformations (15), post-traumatic defects (10), and reconstructions after tumor resection (2). The implants were used for nasal/paranasal augmentations (16), for zygomatico-orbital augmentations (18), and for augmentations of the chin and malar region (11). The procedures were performed in a standardized manner. We used prefabricated, self-contoured implants and fixed them subperiosteally with titanium osteosynthesis screws. All operations were performed under general anesthesia. We evaluated the aesthetic results and the ingrowth behavior clinically and histologically. We achieved good aesthetic results and the patients showed no signs of discomfort or rejection. Four patients required a second intervention. These revision surgeries included two cases of local infections and two for aesthetic contouring. The necessary reduction of the implants allowed the harvesting of tissue and implant samples for microscopy. Porous polyethylene implants showed a good fibrovascular integration without encapsulation under the light microscope. Giant cells were detected on the surface of the implants. Besides this there was evidence for resorption of the implant material. Fixation with titanium screws is very effective. No implant dislocation or implant fracture occurred. The implants showed high volume stability and were easily handled and contoured. It is not possible to visualize Medpor implants with current imaging techniques, because polyethylene shows no contrast.

  10. Reliability of threaded locking screws.

    PubMed

    Karaarslan, Ahmet Adnan; Karakaşlı, Ahmet; Karcı, Tolga; Aycan, Hakan; Sesli, Erhan

    2015-01-01

    A frequent problem for interlocking nailing that affects the treatment of the fracture is locking screw deformation. The aim of this study is to determine whether bending resistance is different between high, low, and unthreaded locking screws of interlocking femoral nails. Ninety screws were used in this experimental study, with 10 screws used in each of 9 groups. Three-point bending tests were performed on 6 groups of 5 mm screws (titanium, stainless steel, crossed with unthreaded, low threaded, and high threaded) and the same 3 thread types of 5.5 mm stainless steel screws in a 30-mm inner diameter steel tube, imitating the level of the lesser trochanter. An axial compressor was used to determine the yield points for permanent deformation in the locking screws by way of 3-point bending tests. The mean yield point value of the 3-point bending tests of 5-mm low threaded stainless steel locking screws was 2071 N, 53% less than that of unthreaded screws (3169 N). The mean yield point value of 5-mm high threaded stainless steel locking screws was 556 N, 272% less than that of low threaded screws (2071 N). To avoid locking screw deformation, high threaded screws must not be used as locking screws. In cases of unreliable patients, 5-mm low threaded screws should not be used in the nailing of comminuted or oblique femur shaft fractures. All 5-mm unthreaded screws and 5.5-mm low threaded stainless steel screws can be used safely in full weight-bearing conditions of unreliable patients.

  11. The use of pedicle-screw internal fixation for the operative treatment of spinal disorders.

    PubMed

    Gaines, R W

    2000-10-01

    Pedicle screws have dramatically improved the outcomes of spinal reconstruction requiring spinal fusion. Short-segment surgical treatments based on the use of pedicle screws for the treatment of neoplastic, developmental, congenital, traumatic, and degenerative conditions have been proved to be practical, safe, and effective. The Funnel Technique provides a straightforward, direct, and inexpensive way to very safely apply pedicle screws in the cervical, thoracic, or lumbar spine. Carefully applied pedicle-screw fixation does not produce severe or frequent complications. Pedicle-screw fixation can be effectively and safely used wherever a vertebral pedicle can accommodate a pedicle screw--that is, in the cervical, thoracic, or lumbar spine. Training in pedicle-screw application should be standard in orthopaedic training programs since pedicle-screw fixation represents the so-called gold standard of spinal internal fixation.

  12. Twin screw wet granulation: Binder delivery.

    PubMed

    Saleh, Mohammed F; Dhenge, Ranjit M; Cartwright, James J; Hounslow, Michael J; Salman, Agba D

    2015-06-20

    The effects of three ways of binder delivery into the twin screw granulator (TSG) on the residence time, torque, properties of granules (size, shape, strength) and binder distribution were studied. The binder distribution was visualised through the transparent barrel using high speed imaging as well as quantified using offline technique. Furthermore, the effect of binder delivery and the change of screw configuration (conveying elements only and conveying elements with kneading elements) on the surface velocity of granules across the screw channel were investigated using particle image velocimetry (PIV). The binder was delivered in three ways; all solid binder incorporated with powder mixture, 50% of solid binder mixed with powder mixture and 50% mixed with water, all the solid binder dissolved in water. Incorporation of all solid binder with powder mixture resulted in the relatively longer residence time and higher torque, narrower granule size distribution, more spherical granules, weaker big-sized granules, stronger small-sized granules and better binder distribution compared to that in other two ways. The surface velocity of granules showed variation from one screw to another as a result of uneven liquid distribution as well as shown a reduction while introducing the kneading elements into the screw configuration.

  13. Nylon screws make inexpensive coil forms

    NASA Technical Reports Server (NTRS)

    Aucoin, G.; Rosenthal, C.

    1978-01-01

    Standard nylon screws act as coil form copper wire laid down in spiral thread. Completed coil may be bonded to printed-circuit board. However, it is impossible to tune coil by adjusting spacing between windings, technique sometimes used with air-core coils.

  14. Nylon screws make inexpensive coil forms

    NASA Technical Reports Server (NTRS)

    Aucoin, G.; Rosenthal, C.

    1978-01-01

    Standard nylon screws act as coil form copper wire laid down in spiral thread. Completed coil may be bonded to printed-circuit board. However, it is impossible to tune coil by adjusting spacing between windings, technique sometimes used with air-core coils.

  15. Prediction of Driver’s Intention of Lane Change by Augmenting Sensor Information Using Machine Learning Techniques

    PubMed Central

    Kim, Il-Hwan; Bong, Jae-Hwan; Park, Jooyoung; Park, Shinsuk

    2017-01-01

    Driver assistance systems have become a major safety feature of modern passenger vehicles. The advanced driver assistance system (ADAS) is one of the active safety systems to improve the vehicle control performance and, thus, the safety of the driver and the passengers. To use the ADAS for lane change control, rapid and correct detection of the driver’s intention is essential. This study proposes a novel preprocessing algorithm for the ADAS to improve the accuracy in classifying the driver’s intention for lane change by augmenting basic measurements from conventional on-board sensors. The information on the vehicle states and the road surface condition is augmented by using an artificial neural network (ANN) models, and the augmented information is fed to a support vector machine (SVM) to detect the driver’s intention with high accuracy. The feasibility of the developed algorithm was tested through driving simulator experiments. The results show that the classification accuracy for the driver’s intention can be improved by providing an SVM model with sufficient driving information augmented by using ANN models of vehicle dynamics. PMID:28604582

  16. Helical screw viscometer

    NASA Astrophysics Data System (ADS)

    Aubert, J. H.; Chapman, R. N.; Kraynik, A. M.

    1983-06-01

    A helical screw viscometer for the measurement of the viscosity of Newtonian and nonNewtonian fluids is comprised of an elongated cylindrical container closed by end caps defining a circular cylindrical cavity within the container, a cylindrical rotor member having a helical screw or ribbon flight carried by the other periphery thereof rotatably carried within the cavity. The fluid to be measured is confined in the cavity filling the space between the rotor and the container wall. The rotor member is supported by axle members journaled in the end caps, one axle extending through one end cap and connectable to a drive source. A pair of longitudinally spaced ports are provided through the wall of the container in communication with the cavity and a differential pressure meter is connected between the ports for measuring the pressure drop caused by the rotation of the helical screw rotor acting on the confined fluid for computing viscosity.

  17. The automatic micrometer screw.

    PubMed

    Picker, K M

    2000-03-01

    A new analytical method - the automatic micrometer screw - has been established to measure the edge height of tablets. The equipment offers many advantages compared with other methods. The precision is slightly increased compared to the traditional micrometer screw and the measurement with a small punch and a linear voltage transducer. No longer any touch of the tablet is necessary and influences results. The method works automatically and continuously, no manual measurement of the tablets is necessary. Up to ten tablets can be analyzed at the same time because of a rotary table on which they are positioned. Thus the method is not personal intensive. By combining the results from the measurement of punch displacement which means tablet height in the die and the results of the measurement with the automatic micrometer screw which means tablet height outside the die, a convenient measurement for the decompression process is possible.

  18. Helical screw viscometer

    DOEpatents

    Aubert, J.H.; Chapman, R.N.; Kraynik, A.M.

    1983-06-30

    A helical screw viscometer for the measurement of the viscosity of Newtonian and non-Newtonian fluids comprising an elongated cylindrical container closed by end caps defining a circular cylindrical cavity within the container, a cylindrical rotor member having a helical screw or ribbon flight carried by the outer periphery thereof rotatably carried within the cavity whereby the fluid to be measured is confined in the cavity filling the space between the rotor and the container wall. The rotor member is supported by axle members journaled in the end caps, one axle extending through one end cap and connectable to a drive source. A pair of longitudinally spaced ports are provided through the wall of the container in communication with the cavity and a differential pressure meter is connected between the ports for measuring the pressure drop caused by the rotation of the helical screw rotor acting on the confined fluid for computing viscosity.

  19. Placement of thoracic transvertebral pedicle screws using 3D image guidance.

    PubMed

    Nottmeier, Eric W; Pirris, Stephen M

    2013-05-01

    Transvertebral pedicle screws have successfully been used in the treatment of high-grade L5-S1 spondylolisthesis. An advantage of transvertebral pedicle screws is the purchase of multiple cortical layers across 2 vertebrae, thereby increasing the stability of the construct. At the lumbosacral junction, transvertebral pedicle screws have been shown to be biomechanically superior to pedicle screws placed in the standard fashion. The use of transvertebral pedicle screws at spinal levels other than L5-S1 has not been reported in the literature. The authors describe their technique of transvertebral pedicle screw placement in the thoracic spine using 3D image guidance. Twelve patients undergoing cervicothoracic or thoracolumbar fusion had 41 thoracic transvertebral pedicle screws placed across 26 spinal levels using this technique. Indications for placement of thoracic transvertebral pedicle screws in earlier cases included osteoporosis and pedicle screw salvage. However, in subsequent cases screws were placed in patients undergoing multilevel thoracolumbar fusion without osteoporosis, particularly near the top of the construct. Image guidance in this study was accomplished using the Medtronic StealthStation S7 image guidance system used in conjunction with the O-arm. All patients were slated to undergo postoperative CT scanning at approximately 4-6 months for fusion assessment, which also allowed for grading of the transvertebral pedicle screws. No thoracic transvertebral pedicle screw placed in this study had to be replaced or repositioned after intraoperative review of the cone beam CT scans. Review of the postoperative CT scans revealed all transvertebral screws to be across the superior disc space with the tips in the superior vertebral body. Six pedicle screws were placed using the in-out-in technique in patients with narrow pedicles, leaving 35 screws that underwent breach analysis. No pedicle breach was noted in 34 of 35 screws. A Grade 1 (< 2 mm) medial breach

  20. Development of titanium fixation screw for hydroxyapatite osteosynthesis (APACERAM).

    PubMed

    Tanaka, Yoshihide

    2008-11-01

    Cranioplasty using custom-made HAP ceramic implants is a common procedure for skull defects. However, miniplate fixation using commercially available screws to stabilize the HAP flap is associated with several problems due to characteristic brittleness. The authors have thus developed a suitable screw for this procedure. Hydroxyapatite blocks (porosity, 40%; thickness, 5 mm) were prepared. Holes were created using a phi 1.4-mm drill. Five types of screw were evaluated for HAP condition after insertion, fixation strength on pull-out test, and fasten plate strength based on maximum torque. Based on this evaluation, the most effective screws were cylindrical style in shape, 4.8 mm in effective length, phi 1.6 mm in effective diameter, and 0.2 mm in edge height. A novel screw with high fixation potential for the miniplate technique was developed in this study.

  1. Screw-Retaining Allen Wrench

    NASA Technical Reports Server (NTRS)

    Granett, D.

    1985-01-01

    Steadying screws with fingers unnecessary. Crimp in uncompressed spring wire slightly protrudes from one facet of Allen wrench. Compressed spring retains Allen screw. Tool used with Allen-head screws in cramped spaces with little or no room for fingers to hold fastener while turned by wrench.

  2. Towards Pervasive Augmented Reality: Context-Awareness in Augmented Reality.

    PubMed

    Grubert, Jens; Langlotz, Tobias; Zollmann, Stefanie; Regenbrecht, Holger

    2017-06-01

    Augmented Reality is a technique that enables users to interact with their physical environment through the overlay of digital information. While being researched for decades, more recently, Augmented Reality moved out of the research labs and into the field. While most of the applications are used sporadically and for one particular task only, current and future scenarios will provide a continuous and multi-purpose user experience. Therefore, in this paper, we present the concept of Pervasive Augmented Reality, aiming to provide such an experience by sensing the user's current context and adapting the AR system based on the changing requirements and constraints. We present a taxonomy for Pervasive Augmented Reality and context-aware Augmented Reality, which classifies context sources and context targets relevant for implementing such a context-aware, continuous Augmented Reality experience. We further summarize existing approaches that contribute towards Pervasive Augmented Reality. Based our taxonomy and survey, we identify challenges for future research directions in Pervasive Augmented Reality.

  3. Biomechanical comparison of odontoid plate fixation versus odontoid screw fixation.

    PubMed

    Platzer, Patrick; Eipeldauer, Stefan; Leitgeb, Johannes; Aldrian, Silke; Vécsei, Vilmos

    2011-05-01

    Randomized controlled trial with statistically significant difference or statistically no significant difference (Level I). The purpose of this study was to measure the mechanical stability of odontoid plate fixation, using a specially designed plate construct and to compare the results with those after odontoid single-screw and double-screw fixation. Plate fixation of the odontoid process without C1-C2 is a possible option for the management of odontoid fractures that are not suitable for conventional screw fixation. Although earlier biomechanical works have evaluated the effectiveness of different odontoid screw fixation techniques, no study has quantified the mechanical stability of odontoid fixation by a plate device. The second cervical vertebra was removed from 15 fresh human spinal columns. The specimens were fixed to the experimental apparatus with the load cell at the articular surface of the odontoid process. In the first test series, stiffness and failure load of the intact odontoid were measured. Type II odontoid fractures were created by a 45 degree oblique extension loading at the articular surface of the odontoid process. Afterward, the specimens were randomly assigned to 1 of the following 3 groups: in group I (n=5), the fractures were stabilized, using a specially designed plate construct, in group II, the fractures were fixed, using two 3.5 mm cortical screws, and in group III, we used 1 regular 4.5 mm cortical screw. In the second test series, stiffness and failure load of the stabilized odontoid fractures were assessed for comparison and statistical analysis. Group I (plate device) showed a significantly higher mean failure load than group II and group III. The mean failure load of group I, after fixation of the odontoid fracture, was 84% of the mean failure load that was necessary to create a type II odontoid fracture initially. Comparing group II (double screw technique) and group III (single screw technique), there was no significant

  4. Ground Influence on a Model Airfoil with a Jet-Augmented Flap as Determined by Two Techniques

    NASA Technical Reports Server (NTRS)

    Turner, Thomas R.

    1961-01-01

    An investigation was made in the Langley 300-MPH 7- by 10-foot tunnel with a conventional ground-board setup and in the Langley tank no. 1 by using the tow carriage to move the model over a ground board to evaluate the simulation of flight conditions in ground influence with a conventional ground-board setup. The 12-percent-thick airfoil was unswept and untapered with an aspect ratio of 6.0 and had a 10 percent- chord jet-augmented flap. From this investigation it appears that the loss in lift of an airfoil with a jet-augmented flap in ground influence as determined in a wind tunnel with a conventional ground-board setup is considerably larger than would be obtained in free flight.

  5. Comparison of Broström technique, suture anchor repair, and tape augmentation for reconstruction of the anterior talofibular ligament.

    PubMed

    Schuh, R; Benca, E; Willegger, M; Hirtler, L; Zandieh, S; Holinka, J; Windhager, R

    2016-04-01

    Recently, tape augmentation for Broström repair has been introduced in order to improve the primary stability of the reconstructed anterior talofibular ligament (ATFL). The biomechanical effect of tape augmentation suture anchor (SA) repair is not known yet. The aim of the present study was to compare construct stability of the traditional Broström (TB) repair compared with a stand alone SA repair (SutureTak, Arthrex) and SA repair combined with tape augmentation (InternalBrace, Arthrex) internal brace (IB) of the ATFL. Eighteen fresh-frozen human anatomic lower leg specimens were randomly assigned to three different groups: TB group, SA group, and IB augmentation group. In vivo torsion conditions in ankle sprain were carried out quasi-statically (0.5°/s). Torque (Nm) required to resist as well as the rotary displacement (°) of the load frame was recorded. Intergroup differences for age, bone mineral density (BMD), angle at failure, and torque at failure were analysed using ANOVA. In the TB group, ATFL reconstruction failed at an angle of 24.1°, in the SA group failure occurred at 35.5°, and in the IB group it failed at 46.9° (p = 0.02). Torque at failure reached 5.7 Nm for the TB repair, 8.0 Nm for the SA repair, and 11.2 Nm for the IB group (p = 0.04). There was no correlation between angle at ATFL failure, torque at failure, and BMD for the SA or IB groups. The present biomechanical study reveals statistically superior performance in terms of angle at failure as well as failure torque for the IB group compared to the other reconstruction methods. BMD did not influence the construct stability in the SA repair groups.

  6. Standardised cement augmentation of the PFNA using a perforated blade: A new technique and preliminary clinical results. A prospective multicentre trial.

    PubMed

    Kammerlander, C; Gebhard, F; Meier, C; Lenich, A; Linhart, W; Clasbrummel, B; Neubauer-Gartzke, T; Garcia-Alonso, M; Pavelka, T; Blauth, M

    2011-12-01

    Pertrochanteric fractures are a rising major health-care problem in the elderly and their operative stabilisation techniques are still under discussion. Furthermore, complications like cut-out are reported to be high and implant failure often is associated with poor bone quality. The PFNA(®) with perforated blade offers a possibility for standardised cement augmentation using a polymethylmethacrylate (PMMA) cement which is injected through the perforated blade to enlarge the load-bearing surface and to diminish the stresses on the trabecular bone. The current prospective multicentre study was undertaken to evaluate the technical performance and the early clinical results of this new device. In nine European clinics, 59 patients (45 female, mean age 84.5 years) suffering from an osteoporotic pertrochanteric fracture (Arbeitsgemeinschaft für Osteosynthesefragen, AO-31) were treated with the augmented PFNA(®). Primary objectives were assessment of operative and postoperative complications, whereas activities of daily living, pain, mobility and radiologic parameters, such as cement distribution around the blade and the cortical thickness index, were secondary objectives. The mean follow-up time was 4 months where we observed callus healing in all cases. The surgical complication rate was 3.4% with no complication related to the cement augmentation. More than one-half of the patients reached their prefracture mobility level within the study period. A mean volume of 4.2ml of cement was injected. We did not find any cut-out, cut through, unexpected blade migration, implant loosening or implant breakage within the study period. Our findings lead us to conclude that the standardised cement augmentation using the perforated blade for pertrochanteric fracture fixation enhances the implant anchorage within the head-neck fragment and leads to good functional results.

  7. Optimising implant anchorage (augmentation) during fixation of osteoporotic fractures: is there a role for bone-graft substitutes?

    PubMed

    Larsson, Sune; Procter, Philip

    2011-09-01

    When stabilising a fracture the contact between the screw and the surrounding bone is crucial for mechanical strength. Through development of screws with new thread designs, as well as optimisation of other properties, improved screw purchase has been gained. Other alternatives to improve screw fixation in osteoporotic bone, as well as normal bone if needed, includes the use of various coatings on the screw that will induce a bonding between the implant surface and the bone implant, as well as application of drugs such as bisphosphonates locally in the screw hole to induce improved screw anchorage through their anticatabolic effect on the bone tissue. As failure of internal fixation of fractures in osteoporotic bone typically occurs through breakage of the bone that surrounds the implant, rather than the implant itself, an alternative strategy in osteoporotic bone can include augmentation of the bone around the screw. This is useful when screws alone are being used for fixation, as it will increase pull-out resistance, but also when conventional plates and screws are used. In angularly stable plate-screw systems, screw back-out is not a problem if the locking mechanism between the screws and the plate works. However, augmentation that will strengthen the bone around the screws can also be useful in conjunction with angle-stable plate-screw systems, as the augmentation will provide valuable support when subjected to loading that might cause cut-out. For many years conventional bone cement, polymethylmethacrylate (PMMA), has been used for augmentation, but due to side effects--including great difficulties if removal becomes necessary--the use of PMMA has never gained wide acceptance. With the introduction of bone substitutes, such as calcium phosphate cement, it has been shown that augmentation around screws can be achieved without the drawbacks seen with PMMA. When dealing with fixation of fractures in osteoporotic bone where screw stability might be inadequate, it

  8. [MRI in ACL reconstructive surgery with PDLLA bioabsorbable interference screws: evaluation of degradation and osteointegration processes of bioabsorbable screws].

    PubMed

    Macarini, Luca; Murrone, Mario; Marini, Stefania; Mocci, Andrea; Ettorre, Giovanni Carlo

    2004-01-01

    was present at the screw site within 1, 2 and 3 years from surgery respectively. Only in 4 cases was the process of osteointegration of the screw and bone plug complete 3 years after the operation, with consequent restoration of bone morphology. The use of bioabsorbable interference screws is a valuable alternative to synthetic metallic fixation implants as the absence of artefacts allows correct post-operative MR follow-up. MRI is the only technique able to visualize all the portions of the transplant and to evaluate the healing process. Bioabsorbable interference screws usually degrade within one year. However, full osteointegration requires a long time and may not be complete 3 years after surgery. The presence of cyst-like formations at the screw site has to be regarded as a normal feature of the screw degradation process. Therefore, the use of bioabsorbable interference screws is recommended as it enables MR follow-up of the knee after ACL reconstruction.

  9. Noninvasive method for retrieval of broken dental implant abutment screw

    PubMed Central

    Gooty, Jagadish Reddy; Palakuru, Sunil Kumar; Guntakalla, Vikram Reddy; Nera, Mahipal

    2014-01-01

    Dental implants made of titanium for replacement of missing teeth are widely used because of ease of technical procedure and high success rate, but are not free of complications and may fail. Fracturing of the prosthetic screw continues to be a problem in restorative practice and great challenge to remove the fractured screw conservatively. This case report describes and demonstrates the technique of using an ultrasonic scaler in the removal of the fracture screw fragment as a noninvasive method without damaging the hex of implants. PMID:24963261

  10. Biomechanical advantages of robot-assisted pedicle screw fixation in posterior lumbar interbody fusion compared with freehand technique in a prospective randomized controlled trial-perspective for patient-specific finite element analysis.

    PubMed

    Kim, Ho-Joong; Kang, Kyoung-Tak; Park, Sung-Cheol; Kwon, Oh-Hyo; Son, Juhyun; Chang, Bong-Soon; Lee, Choon-Ki; Yeom, Jin S; Lenke, Lawrence G

    2017-05-01

    There have been conflicting results on the surgical outcome of lumbar fusion surgery using two different techniques: robot-assisted pedicle screw fixation and conventional freehand technique. In addition, there have been no studies about the biomechanical issues between both techniques. This study aimed to investigate the biomechanical properties in terms of stress at adjacent segments using robot-assisted pedicle screw insertion technique (robot-assisted, minimally invasive posterior lumbar interbody fusion, Rom-PLIF) and freehand technique (conventional, freehand, open approach, posterior lumbar interbody fusion, Cop-PLIF) for instrumented lumbar fusion surgery. This is an additional post-hoc analysis for patient-specific finite element (FE) model. The sample is composed of patients with degenerative lumbar disease. Intradiscal pressure and facet contact force are the outcome measures. Patients were randomly assigned to undergo an instrumented PLIF procedure using a Rom-PLIF (37 patients) or a Cop-PLIF (41), respectively. Five patients in each group were selected using a simple random sampling method after operation, and 10 preoperative and postoperative lumbar spines were modeled from preoperative high-resolution computed tomography of 10 patients using the same method for a validated lumbar spine model. Under four pure moments of 7.5 Nm, the changes in intradiscal pressure and facet joint contact force at the proximal adjacent segment following fusion surgery were analyzed and compared with preoperative states. The representativeness of random samples was verified. Both groups showed significant increases in postoperative intradiscal pressure at the proximal adjacent segment under four moments, compared with the preoperative state. The Cop-PLIF models demonstrated significantly higher percent increments of intradiscal pressure at proximal adjacent segments under extension, lateral bending, and torsion moments than the Rom-PLIF models (p=.032, p=.008, and p

  11. A cone-beam CT based technique to augment the 3D virtual skull model with a detailed dental surface.

    PubMed

    Swennen, G R J; Mommaerts, M Y; Abeloos, J; De Clercq, C; Lamoral, P; Neyt, N; Casselman, J; Schutyser, F

    2009-01-01

    Cone-beam computed tomography (CBCT) is used for maxillofacial imaging. 3D virtual planning of orthognathic and facial orthomorphic surgery requires detailed visualisation of the interocclusal relationship. This study aimed to introduce and evaluate the use of a double CBCT scan procedure with a modified wax bite wafer to augment the 3D virtual skull model with a detailed dental surface. The impressions of the dental arches and the wax bite wafer were scanned for ten patient separately using a high resolution standardized CBCT scanning protocol. Surface-based rigid registration using ICP (iterative closest points) was used to fit the virtual models on the wax bite wafer. Automatic rigid point-based registration of the wax bite wafer on the patient scan was performed to implement the digital virtual dental arches into the patient's skull model. Probability error histograms showed errors of < or =0.22 mm (25% percentile), < or =0.44 mm (50% percentile) and < or =1.09 mm (90% percentile) for ICP surface matching. The mean registration error for automatic point-based rigid registration was 0.18+/-0.10 mm (range 0.13-0.26 mm). The results show the potential for a double CBCT scan procedure with a modified wax bite wafer to set-up a 3D virtual augmented model of the skull with detailed dental surface.

  12. Containment and contouring (CoCoon) technique: a biologically adequate approach to less invasive autogenous preimplant augmentation of bone.

    PubMed

    Gellrich, Nils-Claudius; Bormann, Kai-Hendrik; Tehranchian, Shahram; Kokemüller, Horst; Suarez-Cunqueiro, Maria Mercedes

    2013-12-01

    We have analysed retrospectively whether the less invasive zygomatic buttress graft is able to meet the dimensional and biological requirements of preimplant augmentation of bone. A total of 273 patients were treated by zygomatic buttress graft, of whom 42 (12 men and 30 women) met the criteria for inclusion. Intensity of pain was judged by a visual analogue score (VAS). Complications of grafting were evaluated, and dental implants were studied on clinical and radiographic examinations. The Schneiderian membrane was perforated in 13 cases (28%). The mean (SD) postoperative VAS was 3.1 (0.9) at the donor site. The mean (SD) follow-up after implant was 17(8) months. Two grafts were lost, one from initial dehiscence and later infection, and the other from infection. The mean (SD) marginal resorption of bone graft was 0.5 (0.7) mm. No implant was lost during the observation period. The zygomatic buttress graft meets the biological and dimensional requirements of augmentation of bone before implant that allows the dental implants to survive with satisfactory prosthetic rehabilitation. Copyright © 2012 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

  13. Chronic ankle pain and fibrosis successfully treated with a new noninvasive augmented soft tissue mobilization technique (ASTM): a case report.

    PubMed

    Melham, T J; Sevier, T L; Malnofski, M J; Wilson, J K; Helfst, R H

    1998-06-01

    This clinical case report demonstrates the clinical effectiveness of a new form of soft tissue mobilization in the treatment of excessive connective tissue fibrosis (scar tissue) around an athlete's injured ankle. The scar tissue was causing the athlete to have pain with activity, pain on palpation of the ankle, decreased range of motion, and loss of function. Surgery and several months of conventional physical therapy failed to alleviate the athlete's symptoms. As a final resort, augmented soft tissue mobilization (ASTM) was administered. ASTM is an alternative nonsurgical treatment modality that is being researched at Performance Dynamics (Muncip, IN). ASTM is a process that uses ergonomically designed instruments that assist therapists in the rapid localization and effective treatment of areas exhibiting excessive soft tissue fibrosis. This is followed by a stretching and strengthening program. Upon the completion of 6 wk of ASTM therapy, the athlete had no pain and had regained full range of motion and function. This case report is an example of how a noninvasive augmented form of soft tissue mobilization (ASTM) demonstrated impressive clinical results in treating a condition caused by connective tissue fibrosis.

  14. Isthmus-guided cortical bone trajectory for pedicle screw insertion.

    PubMed

    Iwatsuki, Koichi; Yoshimine, Toshiki; Ohnishi, Yu-ichiro; Ninomiya, Kosi; Ohkawa, Toshika

    2014-08-01

    Herein is described cortical bone trajectory (CBT), a new path for pedicle screw insertion for lumbar vertebral fusion. Because the points of insertion are under the end of the inferior articular process, and because the screws are inserted toward the lateral side, there is less soft tissue development than with the conventional technique; the CBT technique therefore enables less invasive surgery than the conventional technique. However, it has some drawbacks. For example, in the original CBT approach, the points of insertion are in the vicinity of the end of the inferior articular process. Because this joint has been destroyed in many patients who have indications for intervertebral fusion surgery, it is sometimes difficult to use it as a reference point for screw insertion location. With severe lateral slippage, the screw insertion site can become significantly dislocated sideways, with possible resultant damaging to the spinal canal and/or nerve root. The CBT technique here involved inserting the screws while keeping clear of the intervertebral foramen with the assistance of side view X-ray fluoroscopy and using the end of the inferior articular process and the isthmus as points of reference for screw location.

  15. NUT SCREW MECHANISMS

    DOEpatents

    Glass, J.A.F.

    1958-07-01

    A reactor control mechanism is described wherein the control is achieved by the partial or total withdrawal of the fissile material which is in the form of a fuel rod. The fuel rod is designed to be raised and lowered from the reactor core area by means of two concentric ball nut and screw assemblies that may telescope one within the other. These screw mechanisms are connected through a magnetic clutch to a speed reduction gear and an accurately controllable prime motive source. With the clutch energized, the fuel rod may be moved into the reactor core area, and fine adjustments may be made through the reduction gearing. However, in the event of a power failure or an emergency signal, the magnetic clutch will become deenergized, and the fuel rod will drop out of the core area by the force of gravity, thus shutting down the operation of the reactor.

  16. A capillary Archimedes' screw

    NASA Astrophysics Data System (ADS)

    Darbois Texier, Baptiste; Dorbolo, Stephane

    2014-11-01

    As used by Egyptians for irrigation and reported by Archimedes, a screw turning inside a hollow pipe can pull out a fluid againt gravity. At a centimetric scale, an analagous system can be found with a drop pending on a rotating spiral which is tilted toward the horizontal. The ascent of the drop to the top of the spiral is considered and a theoretical model based on geometrical considerations is proposed. The climb of the drop is limited by the fluid deposition on the screw at high capillary number and by a centrifugation phenomenon. We find out the range of fluid proprities and spiral characteristics for which an ascending motion of the drop is possible. Finally we discuss the efficiency of such system to extract a fluid from a bath at a centrimetric scale.

  17. Drill Free Screws: a new form of osteosynthesis screw.

    PubMed

    Heidemann, W; Gerlach, K L; Gröbel, K H; Köllner, H G

    1998-06-01

    Although the application of self-tapping and non self-tapping screws is virtually universal in cranio-maxillofacial surgery, the inevitable, time consuming procedure of drilling a pilot hole has some potential disadvantages, such as damage to nerves, tooth roots or tooth germs, thermal necrosis of the bone and drill bit breakage. Drill Free Screws (DFS) are a recently developed type of osteosynthesis screws, having a tip like a cork screw and specially formed cutting flutes which enable insertion of the screws without drilling. DFS 1.5 and 2 mm were inserted into discs of wood, polyvinylchloride (PVC) and porcine mandibular bone of varying thicknesses between 2 and 4 mm. The values of insertion torque and maximum torque were recorded using an electric torque tester. Thereafter, the screws were inserted with a fixed torque and uniaxial pull out tests were performed. In comparison with this, the same procedure was performed using 1.5 and 2 mm self-tapping titanium screws. Ten trials for each screw-material-combination were conducted to determine insertion torque, maximum torque and pull out analysis. The results showed that the holding power of DFS lay between 70 and 104% of the holding power of self-tapping titanium screws; only in PVC was the difference more than 15%.

  18. Low noise lead screw positioner

    NASA Technical Reports Server (NTRS)

    Perkins, Gerald S. (Inventor)

    1986-01-01

    A very precise and low noise lead screw positioner, for positioning a retroreflector in an interferometer is described. A gas source supplies inert pressurized gas, that flows through narrow holes into the clearance space between a nut and the lead screw. The pressurized gas keeps the nut out of contact with the screw. The gas flows axially along the clearance space, into the environment. The small amount of inert gas flowing into the environment minimizes pollution. By allowing such flow into the environment, no seals are required between the end of the nut and the screw.

  19. Reality-augmented virtual fluoroscopy for computer-assisted diaphyseal long bone fracture osteosynthesis: a novel technique and feasibility study results.

    PubMed

    Zheng, G; Dong, X; Gruetzner, P A

    2008-01-01

    In this paper, a novel technique to create a reality-augmented virtual fluoroscopy for computer-assisted diaphyseal long bone fracture osteosynthesis and feasibility study results are presented. With this novel technique, repositioning of bone fragments during closed fracture reduction and osteosynthesis can lead to image updates in the virtual imaging planes of all acquired images without any radiation. The technique is achieved with a two-stage method. After acquiring a few (normally two) calibrated fluoroscopic images and before fracture reduction, the first stage, data preparation, interactively identifies and segments the bone fragments from the background in each image. After that, the second stage, image updates, repositions the fragment projection on to each virtual imaging plane in real time during fracture reduction and osteosynthesis using an OpenGL-based texture warping. Combined with a photorealistic virtual implant model rendering technique, the present technique allows the control of a closed indirect fracture osteosynthesis in the real world through direct insight into the virtual world. The first clinical study results show the reduction in the X-ray radiation to the patient as well as to the surgical team, and the improved operative precision, guaranteeing more safety for the patient. Furthermore, based on the experiences gained from this clinical study, two technical enhancements are proposed. One focuses on eliminating the user interactions with automated identifications and segmentations of bone fragments. The other focuses on providing non-photorealistic implant visualization. Further experiments are performed to validate the effectiveness of the proposed enhancements.

  20. Role of rod diameter in comparison between only screws versus hooks and screws in posterior instrumentation of thoracic curve in idiopathic scoliosis.

    PubMed

    Lamartina, Claudio; Petruzzi, Maria; Macchia, Marcello; Stradiotti, Paola; Zerbi, Alberto

    2011-05-01

    Since the introduction of Cotrel-Dubousset instrumentation in 1984, the correction techniques in scoliosis surgery have changed from Harrington principles of concave distraction to segmental realignment to a variety of possibilities including the rod rotation manoeuvres, and to segmental approximation via cantilever methods. Additionally, pedicle screw utilization in lumbar curves enhanced correction and stabilization of various deformities, and various studies have strongly supported the clinical advantages of lumbar pedicle screws versus conventional hook instrumentation. Pedicle screw constructs have become increasingly popular in the treatment of patients with spinal deformity. When applied to adolescent idiopathic scoliosis patients, pedicle screw fixation has demonstrated increased corrective ability compared with traditional hook/hybrid instrumentation. In our study, we do a retrospective review of idiopathic scoliosis patients (King 2-Lenke 1 B/C) treated with a selective thoracic posterior fusion using an all-screw construct versus a hybrid (pedicle screws and hooks) construct and, compare the percentage of correction of the scoliotic curves obtained with screws alone and screws and hooks. Special attention was given to the rod diameter and correction technique. Our results show that the percentage of correction of idiopathic thoracic scoliosis is similar when treating the scoliosis with rods and screws alone or with rods, screws and hooks; therefore, we and the majority of authors in the literature do not consider the rod section. This can be an important parameter in the evaluation of the superiority of treatment with screws only or screws and hooks. In our study, even if not of statistical significance, the better thoracic curve correction obtained with the hybrid group should be ascribed to the fact that in this group mostly 6 mm rods were used.

  1. Long-term changes in graft height after maxillary sinus augmentation, onlay bone grafting, and combination of both techniques: a long-term retrospective cohort study.

    PubMed

    Schmitt, Christian; Karasholi, Tarek; Lutz, Rainer; Wiltfang, Jörg; Neukam, Friedrich-Wilhelm; Schlegel, Karl Andreas

    2014-02-01

    This investigation focused on long-term changes in graft height, implant survival rate, and peri-implant tissue conditions of dental implants placed in alveolar ridges after augmentation procedures with a follow-up of 10 years. We conducted a retrospective cohort study with prospective long-term follow-up of 25 patients with edentulous severe atrophic maxillary situations who received a vertical augmentation procedure with autologous bone prior to implant placement. The participants were divided into three groups according to whether they underwent sinus elevation, onlay grafting, or a combination of both techniques. After a four-month healing period, 127 implants were inserted in the corresponding regions. Following a six-month healing period, the participants underwent prosthodontic rehabilitation, incorporating a fixed or removable implant denture. The cohort was clinically and radiographically followed up 1, 5, and 10 years after augmentation. The following parameters were measured: radiographic vertical bone changes, implant loss, peri-implant pocket depth (PD), width of keratinized mucosa (KM), sulcus fluid flow rate (SFFR), and the radiographic distance between the implant shoulder and the first visible bone-to-implant contact (DIB). Seven implants were lost during the observation period, resulting in a cumulative 10-year survival rate of 94.48%. Significant bone loss occurred during the first 12 months, after which the resorption slowed down and bone height eventually stabilized. After 10 years, the total vertical bone loss was 27.51% after onlay grafting, 28.14% after sinus elevation, and 30.24% in the combination group, with no statistically significant between-group differences. Peri-implant follow-up examinations revealed a positive correlation between SFFR and PD, respectively, DIB, and a negative correlation between SFFR and KM. The treatment method does not seem to impact vertical bone loss following augmentation using autologous grafts. This

  2. Biomechanical analysis of forces sustained by iliac screws in spinal instrumentation for deformity treatment: preliminary results.

    PubMed

    Perrault, Frederique D; Aubin, Carl-Eric; Wang, Xiaoyu; Schwend, Richard M

    2012-01-01

    Iliac screws used in long instrumentation for deformity treatment are subject to large forces, which may sometimes lead to fixation failures (intra- and postoperatively). The objective of this study was to analyze the biomechanics of iliac screw fixations. The study was based on a patient-specific simulation of a neuromuscular scoliosis case with a long instrumentation to the pelvis. A multi body flexible model was created using a preoperative 3D reconstructed spine and pelvis. The side bending radiographs were used to personalize the mechanical properties. The instrumentation construct was modeled as rigid bodies and flexible beams connected by kinematic joints. Three instrumentation parameters were studied: the connector length, the inter rod connectors and the use of sacral screws. The simulations showed that the forces and torques at the iliac screws were lowered by 9% and 25% respectively by reducing the lateral connector length (from 20 to 10 mm). An inter rod connector did not significantly reduce the iliac screw loads. Sacral screws reduced the functional loads on the iliac screws, but hardware related problems may be shifted onto the sacral screws. Sacral screws in conjunction with inter rod connectors reduced the loads at iliac screws without overloading the sacral screws. The preliminary results showed that the forces at the iliac screws could be lowered through different instrumentation parameters. In the next step of the study, the model validation will be further completed and used to evaluate other instrumentation factors by means of an experimental design framework. The knowledge of loading biomechanics at the iliac screw fixation is important for finding solutions to reduce the risk of failure, such as improving preoperative planning, instrumentation techniques and iliac screw construct design.

  3. Accuracy of robot-assisted pedicle screw placement for adolescent idiopathic scoliosis in the pediatric population.

    PubMed

    Macke, Jeremy J; Woo, Raymund; Varich, Laura

    2016-06-01

    This is a retrospective review of pedicle screw placement in adolescent idiopathic scoliosis (AIS) patients under 18 years of age who underwent robot-assisted corrective surgery. Our primary objective was to characterize the accuracy of pedicle screw placement with evaluation by computed tomography (CT) after robot-assisted surgery in AIS patients. Screw malposition is the most frequent complication of pedicle screw placement and is more frequent in AIS. Given the potential for serious complications, the need for improved accuracy of screw placement has spurred multiple innovations including robot-assisted guidance devices. No studies to date have evaluated this robot-assisted technique using CT exclusively within the AIS population. Fifty patients were included in the study. All operative procedures were performed at a single institution by a single pediatric orthopedic surgeon. We evaluated the grade of screw breach, the direction of screw breach, and the positioning of the patient for preoperative scan (supine versus prone). Of 662 screws evaluated, 48 screws (7.2 %) demonstrated a breach of greater than 2 mm. With preoperative prone position CT scanning, only 2.4 % of screws were found to have this degree of breach. Medial malposition was found in 3 % of screws, a rate which decreased to 0 % with preoperative prone position scanning. Based on our results, we conclude that the proper use of image-guided robot-assisted surgery can improve the accuracy and safety of thoracic pedicle screw placement in patients with adolescent idiopathic scoliosis. This is the first study to evaluate the accuracy of pedicle screw placement using CT assessment in robot-assisted surgical correction of patients with AIS. In our study, the robot-assisted screw misplacement rate was lower than similarly constructed studies evaluating conventional (non-robot-assisted) procedures. If patients are preoperatively scanned in the prone position, the misplacement rate is further

  4. CT-based patient-specific simulation software for pedicle screw insertion.

    PubMed

    Klein, Shawn; Whyne, Cari M; Rush, Raphael; Ginsberg, Howard J

    2009-10-01

    Development of a 3-dimensional, patient-specific simulator for pedicle screw insertion. To allow the user to practice the insertion of pedicle screws into a 3-dimensional model of a patient-specific spine, and have both visual and quantitative feedback provided to the user. The goal is to better prepare surgeons to perform pedicle screw insertion surgery and help reduce the risk of pedicle screw misplacement. Pedicle screw insertion is particularly challenging to carry out on patients with abnormal spine morphology. Currently, preoperative planning for pedicle screw insertion is carried out using patient computed tomography and magnetic resonance imaging scans. In addition, once screws are inserted, there are no quantitative metrics against which to measure the results. The simulator was developed in the TCL scripting language as a graphical plug-in for the commercial visualization software AmiraDev 3.11. Surgical simulation uses a 3-dimensional model of patient's spine developed from the patient's computed tomography scan. Pedicle screw insertion can be practiced using pedicle screws of various sizes and analyzed in both 2-dimension and 3-dimension. Quantitative feedback is provided to the user in the form of anatomic lengths and angles, relative purchase of inserted screws, and a screw placement grading system. The software allows the user to adjust the translucency of a patient's spine to develop a better sense of the trajectories and depths involved with performing pedicle screw insertion on a patient. The simulator offers many helpful features to the surgeon with respect to complex cases and to the surgical trainee learning the basic technique of pedicle screw insertion. A study is currently underway to evaluate the efficacy of the simulator as a teaching tool for surgical trainees in placing pedicle screws. Future work will focus on the transfer of the software to a stand-alone platform.

  5. Human Augmentics: augmenting human evolution.

    PubMed

    Kenyon, Robert V; Leigh, Jason

    2011-01-01

    Human Augmentics (HA) refers to technologies for expanding the capabilities, and characteristics of humans. One can think of Human Augmentics as the driving force in the non-biological evolution of humans. HA devices will provide technology to compensate for human biological limitations either natural or acquired. The strengths of HA lie in its applicability to all humans. Its interoperability enables the formation of ecosystems whereby augmented humans can draw from other realms such as "the Cloud" and other augmented humans for strength. The exponential growth in new technologies portends such a system but must be designed for interaction through the use of open-standards and open-APIs for system development. We discuss the conditions needed for HA to flourish with an emphasis on devices that provide non-biological rehabilitation.

  6. Twin screw granulation - review of current progress.

    PubMed

    Thompson, M R

    2015-01-01

    Twin screw granulation (TSG) is a new process of interest to the pharmaceutical community that can continuously wet granulate powders, doing so at lower liquid concentrations and with better product consistency than found by a high shear batch mixer. A considerable body of research has evolved over the short time since this process was introduced but generally with little comparison of results. A certain degree of confidence has been developed through these studies related to how process variables and many attributes of machinery configuration will affect granulation but some major challenges still lay ahead related to scalability, variations in the processing regimes related to degree of channel fill and the impact of wetting and granulation of complex powder formulations. This review examines the current literature for wet granulation processes studied in twin screw extrusion machinery, summarizing the influences of operational and system parameters affecting granule properties as well as strives to provide some practical observations to newly interested users of the technique.

  7. Pilot-optimal augmentation synthesis

    NASA Technical Reports Server (NTRS)

    Schmidt, D. K.

    1978-01-01

    An augmentation synthesis method usable in the absence of quantitative handling qualities specifications, and yet explicitly including design objectives based on pilot-rating concepts, is presented. The algorithm involves the unique approach of simultaneously solving for the stability augmentation system (SAS) gains, pilot equalization and pilot rating prediction via optimal control techniques. Simultaneous solution is required in this case since the pilot model (gains, etc.) depends upon the augmented plant dynamics, and the augmentation is obviously not a priori known. Another special feature is the use of the pilot's objective function (from which the pilot model evolves) to design the SAS.

  8. Could the Topping-Off Technique Be the Preventive Strategy against Adjacent Segment Disease after Pedicle Screw-Based Fusion in Lumbar Degenerative Diseases? A Systematic Review

    PubMed Central

    Chou, Po-Hsin; Lin, Hsi-Hsien; An, Howard S.; Liu, Kang-Ying

    2017-01-01

    The “topping-off” technique is a new concept applying dynamic or less rigid fixation such as hybrid stabilization device (HSD) or interspinous process device (IPD) for the purpose of avoiding adjacent segment disease (ASD) proximal to the fusion construct. A systematic review of the literature was performed on the effect of topping-off techniques to prevent or decrease the occurrence of ASD after lumbar fusion surgery. We searched through major online databases, PubMed and MEDLINE, using key words related to “topping-off” technique. We reviewed the surgical results of “topping-off” techniques with either HSD or IPD, including the incidence of ASD at two proximal adjacent levels (index and supra-adjacent level) as compared to the fusion alone group. The results showed that the fusion alone group had statistically higher incidence of radiographic (52.6%) and symptomatic (11.6%) ASD at the index level as well as higher incidence (8.1%) of revision surgery. Besides, the HSD (10.5%) and fusion groups (24.7%) had statistically higher incidences of radiographic ASD at supra-adjacent level than the IPD (1%). The findings suggest that the “topping-off” technique may potentially decrease the occurrence of ASD at the proximal motion segments. However, higher quality prospective randomized trials are required prior to wide clinical application. PMID:28321409

  9. A novel approach to navigated implantation of S-2 alar iliac screws using inertial measurement units.

    PubMed

    Jost, Gregory F; Walti, Jonas; Mariani, Luigi; Cattin, Philippe

    2016-03-01

    The authors report on a novel method of intraoperative navigation with inertial measurement units (IMUs) for implantation of S-2 alar iliac (S2AI) screws in sacropelvic fixation of the human spine and its application in cadaveric specimens. Screw trajectories were planned on a multiplanar reconstruction of the preoperative CT scan. The pedicle finder and screwdriver were equipped with IMUs to guide the axial and sagittal tilt angles of the planned trajectory, and navigation software was developed. The entry points were chosen according to anatomical landmarks on the exposed spine. After referencing, the sagittal and axial orientation of the pedicle finder and screwdriver were wirelessly monitored on a computer screen and aligned with the preoperatively planned tilt angles to implant the S2AI screws. The technique was performed without any intraoperative imaging. Screw positions were analyzed on postoperative CT scans. Seventeen of 18 screws showed a good S2AI screw trajectory. Compared with the postoperatively measured tilt angles of the S2AI screws, the IMU readings on the screwdriver were within an axial plane deviation of 0° to 5° in 15 (83%) and 6° to 10° in 2 (11%) of the screws and within a sagittal plane deviation of 0° to 5° in 15 (83%) and 6° to 10° in 3 (17%) of the screws. IMU-based intraoperative navigation may facilitate accurate placement of S2AI screws.

  10. Roux-en-Y augmented gastric advancement: An alternative technique for concurrent esophageal and pyloric stenosis secondary to corrosive intake

    PubMed Central

    Waseem, Talat; Azim, Asad; Ashraf, Muhammad Hasham; Azim, Khawaja M

    2016-01-01

    Select group of patients with concurrent esophageal and gastric stricturing secondary to corrosive intake requires colonic or free jejunal transfer. These technically demanding reconstructions are associated with significant complications and have up to 18% ischemic conduit necrosis. Following corrosive intake, up to 30% of such patients have stricturing at the pyloro-duodenal canal area only and rest of the stomach is available for rather less complex and better perfused gastrointestinal reconstruction. Here we describe an alternative technique where we utilize stomach following distal gastric resection along with Roux-en-Y reconstruction instead of colonic or jejunal interposition. This neo-conduit is potentially superior in terms of perfusion, lower risk of gastro-esophageal anastomotic leakage and technical ease as opposed to colonic and jejunal counterparts. We have utilized the said technique in three patients with acceptable postoperative outcome. In addition this technique offers a feasible reconstruction plan in patients where colon is not available for reconstruction due to concomitant pathology. Utility of this technique may also merit consideration for gastroesophageal junction tumors. PMID:28070231

  11. The Use of Biofeedback to Augment the Acquisition of Skills in Performing Joint Mobilization Techniques among Physical Therapy Students

    ERIC Educational Resources Information Center

    Timmerberg, Jean Fitzpatrick

    2011-01-01

    Despite the frequent use of joint mobilizations and the available evidence of its effectiveness as a treatment for various musculoskeletal disorders, it is a technique that has been shown to have great variability within and between raters. This variability is believed to occur because of differences between therapists' ability to perceive…

  12. Augmenting a Microbial Selective Plugging Technique with Polymer Flooding to Increase the Efficiency of Oil Recovery - A Search for Synergy

    SciTech Connect

    Brown, Lewis R.; Vadie, A. Alex; Pittman Jr., Charles U.; Lynch, F. Leo

    2003-02-10

    The overall objective of this project was to improve the effectiveness of a microbial selective plugging technique of improving oil recovery through the use of polymer floods. More specifically, the intent was to increase the total amount of oil recovered and to reduce the cost per barrel of incremental oil.

  13. The Use of Biofeedback to Augment the Acquisition of Skills in Performing Joint Mobilization Techniques among Physical Therapy Students

    ERIC Educational Resources Information Center

    Timmerberg, Jean Fitzpatrick

    2011-01-01

    Despite the frequent use of joint mobilizations and the available evidence of its effectiveness as a treatment for various musculoskeletal disorders, it is a technique that has been shown to have great variability within and between raters. This variability is believed to occur because of differences between therapists' ability to perceive…

  14. Augmenting a Microbial Selective Plugging Technique with Polymer Flooding to Increase the Efficiency of Oil Recovery - A Search for Synergy

    SciTech Connect

    Brown, Lewis R.; Pittman Jr., Charles U.; Lynch, F. Leo; Vadie, A. Alex

    2003-02-10

    The overall objective of this project was to improve the effectiveness of a microbial selective plugging technique of improving oil recovery through the use of polymer floods. More specifically, the intent was to increase the total amount of oil recovered and to reduce the cost per barrel of incremental oil.

  15. Pediatric pedicle screw placement using intraoperative computed tomography and 3-dimensional image-guided navigation.

    PubMed

    Larson, A Noelle; Santos, Edward R G; Polly, David W; Ledonio, Charles G T; Sembrano, Jonathan N; Mielke, Cary H; Guidera, Kenneth J

    2012-02-01

    A retrospective cohort study reporting the use of intraoperative computed tomography (CT) and image-guided navigation system for the placement of pedicle screws in pediatric compared with adult patients. To evaluate the accuracy of open pedicle screw placement in pediatric patients using intraoperative CT and 3-dimensional (3D) image-guided navigation. Pedicle screws are widely used in children for the correction of spinal deformity. Navigation systems and intraoperative CT are now available as an adjunct to fluoroscopy and anatomic techniques for placing pedicle screws and verifying screw position. From 2007 to 2010, 984 pedicle screws were placed in a consecutive series cohort of 50 pediatric patients for spinal deformity correction with the use of intraoperative CT (O-arm, Medtronic, Inc, Louisville, CO) and a computerized navigation system (Stealth, Medtronic, Inc, Louisville, CO). The primary outcome measure for this study is redirection or removal of screw on the basis of the intraoperative CT imaging. During the study period, 1511 screws were placed in adult patients using the same image guidance system. A total of 984 pedicle screws were implanted using real-time navigation, with a mean of 20 screws per patient (range: 2-34). On the basis of intraoperative CT, 35 screws (3.6%) were revised (27 redirected and 8 removed), representing a 96.4% accuracy rate. No patients returned to the operating room because of screw malposition.Of the 1511 screws placed in adult patients, 28 (1.8%) were revised intraoperatively for malposition on CT imaging, for an overall 98.2% accuracy rate. Screw revision thus was more common in the pediatric population (P = 0.008). However, the pediatric screw accuracy rate is significantly higher than the findings from a recent meta-analysis of predominantly nonnavigated screws in children, reporting a 94.9% accuracy rate (P = 0.03). We report 96.4% accuracy in pediatric pedicle screw placement using intraoperative CT and a 3D navigation

  16. Laminar screw fixation in the subaxial cervical spine: A report on three cases

    PubMed Central

    Tanabe, Hironori; Aota, Yoichi; Saito, Tomoyuki

    2016-01-01

    Although laminar screw fixation is often used at the C2 and C7 levels, only few previous case reports have presented the use of laminar screws at the C3-C6 levels. Here, we report a novel fixation method involving the use of practical laminar screws in the subaxial spine. We used laminar screws in the subaxial cervical spine in two cases to prevent vertebral artery injury and in one case to minimize exposure of the lamina. This laminar screw technique was successful in all three cases with adequate spinal rigidity, which was achieved without complications. The use of laminar screws in the subaxial cervical spine is a useful option for posterior fusion of the cervical spine. PMID:27795952

  17. Two inhomogeneities of irregular shape with internal uniform stress fields interacting with a screw dislocation

    NASA Astrophysics Data System (ADS)

    Wang, Xu; Schiavone, Peter

    2016-07-01

    Using complex variable methods and conformal mapping techniques, we demonstrate rigorously that two inhomogeneities of irregular shape interacting with a screw dislocation can indeed maintain uniform internal stress distributions. Our analysis indicates that while the internal uniform stresses are independent of the existence of the screw dislocation, the shapes of the two inhomogeneities required to achieve this uniformity depend on the Burgers vector, the location of the screw dislocation, and the size of the inhomogeneities. In addition, we find that this uniformity of the internal stress field is achievable also when the two inhomogeneities interact with an arbitrary number of discrete screw dislocations in the matrix.

  18. Ridge augmentation with soft tissue procedures in aesthetic dentistry: first clinical results measured with a new kind of moire technique

    NASA Astrophysics Data System (ADS)

    Studer, Stephan P.; Bucher, Andreas; Mueller, Felix

    1993-09-01

    The oral health of the Swiss population was significantly improved by the successful prevention of dental caries and periodontitis. Along with the healthy dentition the demand for aesthetic dentistry is increasing. Removable partial dentures are becoming less accepted. Therefore, to substitute lost teeth by permanent fixed partial prosthesis (bridges), the often deformed alveolar ridge has to be operated, either to improve the aesthetic appearance or to make it possible to restore the missing teeth by a fixed cemented bridge. The aim of this paper is (1) to evaluate whether the moire technique is an appropriate and handy method, and (2) to validate the precision of the new method. The measuring system consisted of a moire projector with an integrated phase shift device and a moire viewer with a CCD video camera, connected to a frame grabber in a personal computer. a highly versatile software was allowed to control the system as well as to grab the moire images using the four-phase shift technique in order to compute the phase image of the actual object. The new technique was validated with one solid test object measured by a 3D coordination, high precision measuring machine.

  19. Pulmonary vein isolation supported by MRI-derived 3D-augmented biplane fluoroscopy: a feasibility study and a quantitative analysis of the accuracy of the technique.

    PubMed

    Bourier, Felix; Vukajlovic, Dejan; Brost, Alexander; Hornegger, Joachim; Strobel, Norbert; Kurzidim, Klaus

    2013-02-01

    Despite the advancement of technology in electroanatomic mapping systems (EAMS), fluoroscopy remains a necessary, basic imaging modality for electrophysiology procedures. We present a feasibility study of new software that enables 3D-augmented fluoroscopy in biplane catheterization laboratories for planning and guidance of pulmonary vein isolation (PVI). The computer-assisted overlay registration accuracy was assessed in a clinical setting using an automatic calculation of overlay projection geometry that was derived from hardware sensors in C-arms, detectors, and patient table. Consecutive patients (n = 89) underwent left atrium (LA) magnetic resonance imaging MRI scan prior to PVI. Ideal ablation lines encircling the ipsilateral pulmonary veins (PVs) at antral level were drawn onto the segmented LA surface. The 3D-model was superimposed onto biplane fluoroscopy and matched with angiographies of LA and PVs. Three-dimensional-overlay projection geometry was automatically calculated from C-arm, detectors, and table sensors. Accuracy of technique was assessed as alignment of MRI-derived 3D overlay and angiographic LA/PV anatomy. Integrity of registered overlay was quantified using landmark measurements. Alignment offsets were 1.3 ± 1.5 mm in left PV, 1.2 ± 1.5 mm in right PV, and 1.1 ± 1.4 mm in LA roof region. Bravais-Pearson correlation of the landmark measurements was r = 0.978 (s < 0.01), mean offset between landmark distance measurements was 1.4 ± 0.78 mm. Average time needed for overlay registration was 9.5 ± 3.5 seconds. MRI-derived 3D-augmented fluoroscopy demonstrated a high level of accuracy when compared with LA/PV angiography. The new system could be especially useful to guide procedures not supported by EAMS, such as cryotechnique PVI. © 2012 Wiley Periodicals, Inc.

  20. Excellent healing rates and patient satisfaction after arthroscopic repair of medium to large rotator cuff tears with a single-row technique augmented with bone marrow vents.

    PubMed

    Dierckman, Brian D; Ni, Jake J; Karzel, Ronald P; Getelman, Mark H

    2017-06-24

    This study evaluated the repair integrity and patient clinical outcomes following arthroscopic rotator cuff repair of medium to large rotator cuff tears using a single-row technique consisting of medially based, triple-loaded anchors augmented with bone marrow vents in the rotator cuff footprint lateral to the repair. This is a retrospective study of 52 patients (53 shoulders) comprising 36 males and 16 females with a median age of 62 (range 44-82) with more than 24-month follow-up, tears between 2 and 4 cm in the anterior-posterior dimension and utilizing triple-loaded anchors. Mann-Whitney test compared Western Ontario Rotator Cuff (WORC) outcome scores between patients with healed and re-torn cuff repairs. Multivariate logistic regression analysed association of variables with healing status and WORC score. Cuff integrity was assessed on MRI, read by a musculoskeletal fellowship-trained radiologist. Magnetic resonance imaging (MRI) demonstrated an intact repair in 48 of 53 shoulders (91%). The overall median WORC score was 95.7 (range 27.6-100.0). A significant difference in WORC scores were seen between patients with healed repairs 96.7 (range 56.7-100.0) compared with a re-tear 64.6 (27.6-73.8), p < 0.00056. Arthroscopic repair of medium to large rotator cuff tears using a triple-loaded single-row repair augmented with bone marrow vents resulted in a 91% healing rate by MRI and excellent patient reported clinical outcomes comparable to similar reported results in the literature. IV.

  1. Mini-Open Suture Bridge Repair with Porcine Dermal Patch Augmentation for Massive Rotator Cuff Tear: Surgical Technique and Preliminary Results

    PubMed Central

    Lee, Sung-Moon; Lee, Young-Kuk; Shin, Hong-Kwan

    2014-01-01

    Background The aim of this study was to describe the mini-open suture bridge technique with porcine dermal patch augmentation for massive rotator cuff tear and to assess preliminary clinical and radiological results. Methods Five patients with massive rotator cuff tear for which it was not possible to restore the anatomical footprint underwent mini-open suture bridge repair using a porcine dermal patch. The patients' average age was 53.4 years (range, 45 to 57 years), and the average duration of follow-up was 20.6 months (range, 14 to 26 months). Patients were evaluated with preoperative and postoperative outcome measures, including a visual analog scale (VAS) for pain, the University of California Los Angeles (UCLA) score, and the American Shoulder and Elbow Surgeons (ASES) score. The structural integrity of repaired rotator cuffs was assessed by magnetic resonance imaging 6 months postoperatively. Results The average VAS pain score, UCLA score, and ASES score improved from 6.8, 15.4, and 39.4 preoperatively to 0.8, 31.2, and 86.4 postoperatively (p = 0.041, 0.042, and 0.043, respectively). Magnetic resonance images obtained at an average of 8 months after surgery showed that four patients had intact repair integrity with graft incorporation. One patient had a re-tear with partial healing but still had a satisfactory clinical outcome. There was no intraoperative or postoperative complication in any patient. Conclusions Mini-open suture bridge repair with porcine dermal patch augmentation can be an option in young patients with high physical demands and massive rotator cuff tears for which it is not possible to restore the anatomical footprint. PMID:25177460

  2. Split spline screw

    NASA Technical Reports Server (NTRS)

    Vranish, John M. (Inventor)

    1993-01-01

    A split spline screw type payload fastener assembly, including three identical male and female type split spline sections, is discussed. The male spline sections are formed on the head of a male type spline driver. Each of the split male type spline sections has an outwardly projecting load baring segment including a convex upper surface which is adapted to engage a complementary concave surface of a female spline receptor in the form of a hollow bolt head. Additionally, the male spline section also includes a horizontal spline releasing segment and a spline tightening segment below each load bearing segment. The spline tightening segment consists of a vertical web of constant thickness. The web has at least one flat vertical wall surface which is designed to contact a generally flat vertically extending wall surface tab of the bolt head. Mutual interlocking and unlocking of the male and female splines results upon clockwise and counter clockwise turning of the driver element.

  3. Spline screw autochanger

    NASA Astrophysics Data System (ADS)

    Vranish, John M.

    1993-06-01

    A captured nut member is located within a tool interface assembly and being actuated by a spline screw member driven by a robot end effector. The nut member lowers and rises depending upon the directional rotation of the coupling assembly. The captured nut member further includes two winged segments which project outwardly in diametrically opposite directions so as to engage and disengage a clamping surface in the form of a chamfered notch respectively provided on the upper surface of a pair of parallel forwardly extending arm members of a bifurcated tool stowage holster which is adapted to hold and store a robotic tool including its end effector interface when not in use. A forward and backward motion of the robot end effector operates to insert and remove the tool from the holster.

  4. Carbon nanotube Archimedes screws.

    PubMed

    Oroszlány, László; Zólyomi, Viktor; Lambert, Colin J

    2010-12-28

    Recently, nanomechanical devices composed of a long stationary inner carbon nanotube and a shorter, slowly rotating outer tube have been fabricated. In this paper, we study the possibility of using such devices as nanoscale transducers of motion into electricity. When the outer tube is chiral, we show that such devices act like quantum Archimedes screws, which utilize mechanical energy to pump electrons between reservoirs. We calculate the pumped charge from one end of the inner tube to the other, driven by the rotation of a chiral outer nanotube. We show that the pumped charge can be greater than one electron per 360° rotation, and consequently, such a device operating with a rotational frequency of 10 MHz, for example, would deliver a current of ≈1 pAmp.

  5. The screw propeller

    NASA Astrophysics Data System (ADS)

    Larrabee, E. E.

    1980-07-01

    Marine and air screw propellers are considered in terms of theoretical hydrodynamics as developed by Joukowsky, Prandtl, and Betz. Attention is given to the flow around wings of finite span where spanwise flow exists and where lift and the bound vorticity must all go smoothly to zero at the wing tips. The concept of a trailing vortex sheet made up of infinitesimal line vortexes roughly aligned with the direction of flight is discussed in this regard. Also considered is induced velocity, which tends to convect the sheet downward at every stage in the roll-up process, the vortex theory of propellers and the Betz-Prandtl circulation distribution. The performance of the Gossamer Albatross and of a pedal-driven biplane called the Chrysalis are also discussed.

  6. Innovative approach in the development of computer assisted algorithm for spine pedicle screw placement.

    PubMed

    Solitro, Giovanni F; Amirouche, Farid

    2016-04-01

    Pedicle screws are typically used for fusion, percutaneous fixation, and means of gripping a spinal segment. The screws act as a rigid and stable anchor points to bridge and connect with a rod as part of a construct. The foundation of the fusion is directly related to the placement of these screws. Malposition of pedicle screws causes intraoperative complications such as pedicle fractures and dural lesions and is a contributing factor to fusion failure. Computer assisted spine surgery (CASS) and patient-specific drill templates were developed to reduce this failure rate, but the trajectory of the screws remains a decision driven by anatomical landmarks often not easily defined. Current data shows the need of a robust and reliable technique that prevents screw misplacement. Furthermore, there is a need to enhance screw insertion guides to overcome the distortion of anatomical landmarks, which is viewed as a limiting factor by current techniques. The objective of this study is to develop a method and mathematical lemmas that are fundamental to the development of computer algorithms for pedicle screw placement. Using the proposed methodology, we show how we can generate automated optimal safe screw insertion trajectories based on the identification of a set of intrinsic parameters. The results, obtained from the validation of the proposed method on two full thoracic segments, are similar to previous morphological studies. The simplicity of the method, being pedicle arch based, is applicable to vertebrae where landmarks are either not well defined, altered or distorted.

  7. Torsional stiffness after subtalar arthrodesis using second generation headless compression screws: Biomechanical comparison of 2-screw and 3-screw fixation.

    PubMed

    Riedl, Markus; Glisson, Richard R; Matsumoto, Takumi; Hofstaetter, Stefan G; Easley, Mark E

    2017-06-01

    Subtalar joint arthrodesis is a common operative treatment for symptomatic subtalar arthrosis. Because excessive relative motion between the talus and calcaneus can delay or prohibit fusion, fixation should be optimized, particularly in patients at risk for subtalar arthrodesis nonunion. Tapered, fully-threaded, variable pitch screws are gaining popularity for this application, but the mechanical properties of joints fixed with these screws have not been characterized completely. We quantified the torsion resistance of 2-screw and 3-screw subtalar joint fixation using this type of screw. Ten pairs of cadaveric subtalar joints were prepared for arthrodesis and fixed using Acutrak 2-7.5 screws. One specimen from each pair was fixed with two diverging posterior screws, and the contralateral joint was fixed using two posterior screws and a third screw directed through the anterior calcaneus into the talar neck. Internal and external torsional loads were applied and joint rotation and torsional stiffness were measured at two torque levels. Internal rotation was significantly less in specimens fixed with three screws. No difference was detectable between 2-screw and 3-screw fixation in external rotation or torsional stiffness in either rotation direction. Both 2-screw and 3-screw fixation exhibited torsion resistance surpassing that reported previously for subtalar joints fixed with two diverging conventional lag screws. Performance of the tapered, fully threaded, variable pitch screws exceeded that of conventional lag screws regardless of whether two or three screws were used. Additional resistance to internal rotation afforded by a third screw placed anteriorly may offer some advantage in patients at risk for nonunion. Copyright © 2017. Published by Elsevier Ltd.

  8. Virtual estimates of fastening strength for pedicle screw implantation procedures

    NASA Astrophysics Data System (ADS)

    Linte, Cristian A.; Camp, Jon J.; Augustine, Kurt E.; Huddleston, Paul M.; Robb, Richard A.; Holmes, David R.

    2014-03-01

    Traditional 2D images provide limited use for accurate planning of spine interventions, mainly due to the complex 3D anatomy of the spine and close proximity of nerve bundles and vascular structures that must be avoided during the procedure. Our previously developed clinician-friendly platform for spine surgery planning takes advantage of 3D pre-operative images, to enable oblique reformatting and 3D rendering of individual or multiple vertebrae, interactive templating, and placement of virtual pedicle implants. Here we extend the capabilities of the planning platform and demonstrate how the virtual templating approach not only assists with the selection of the optimal implant size and trajectory, but can also be augmented to provide surrogate estimates of the fastening strength of the implanted pedicle screws based on implant dimension and bone mineral density of the displaced bone substrate. According to the failure theories, each screw withstands a maximum holding power that is directly proportional to the screw diameter (D), the length of the in-bone segm,ent of the screw (L), and the density (i.e., bone mineral density) of the pedicle body. In this application, voxel intensity is used as a surrogate measure of the bone mineral density (BMD) of the pedicle body segment displaced by the screw. We conducted an initial assessment of the developed platform using retrospective pre- and post-operative clinical 3D CT data from four patients who underwent spine surgery, consisting of a total of 26 pedicle screws implanted in the lumbar spine. The Fastening Strength of the planned implants was directly assessed by estimating the intensity - area product across the pedicle volume displaced by the virtually implanted screw. For post-operative assessment, each vertebra was registered to its homologous counterpart in the pre-operative image using an intensity-based rigid registration followed by manual adjustment. Following registration, the Fastening Strength was computed

  9. An intermaxillary fixation screw traction wire: an aid for facial bone fracture repair.

    PubMed

    Kim, Myung-Good; Yoo, Roh-Eul; Chang, Hak; Kwon, Sung-Tack; Baek, Rong-Min; Minn, Kyung-Won

    2009-07-01

    We have devised a new technique to improve stabilization of fractured facial bone fractures (frontal sinus fractures, zygomatic fractures, mandibular condyle fractures) by intermaxillary fixation screw traction wires (stainless steel wires through intermaxillary fixation screws). A retrospective study evaluating intermaxillary fixation screw traction wires was performed. We have used this technique for 3 cases of frontal sinus fractures, 9 cases of zygomatic fractures, and 7 cases of mandibular condyle fractures. After dissection of a fractured site, a hole is drilled on the fractured bone where it does not interfere with positioning the plate across the fracture line. After an intermaxillary fixation screw is inserted, a stainless steel wire is tied through a hole in the screw head. By the aid of wire for traction, the displaced fractured bone is easily aligned to the proper position. Plates and screws are applied readily on the predetermined area. A retrospective study on 19 patients using intermaxillary fixation screw traction wires was performed. The diagnoses and associated complications of the cases were recorded. No associated complication as a result of using this technique was identified. The use of intermaxillary fixation screw traction wire enhances stabilization and visualization without possible risk for surrounding soft tissue injury using, a sharp traction device like a bone hook. An intermaxillary fixation screw traction wire is an useful aid for visualization and stabilization during facial bone fracture reduction, particularly where exposure is difficult such as in the condylar region of the mandible. And unlike a classic traction wire, the intermaxillary fixation screw traction wire has almost no risk of having it loosened from the screw.

  10. Anatomic Study of Anterior Transdiscal Axial Screw Fixation for Subaxial Cervical Spine Injuries.

    PubMed

    Ji, Wei; Zheng, Minghui; Qu, Dongbin; Zou, Lin; Chen, Yongquan; Chen, Jianting; Zhu, Qingan

    2016-08-01

    Anterior transdiscal axial screw (ATAS) fixation is an alternative or supplement to the plate and screw constructs for the upper cervical spine injury. However, no existing literatures clarified the anatomic feasibility of this technique for subaxial cervical spine. Therefore, the objective of this study was to evaluate the anatomical feasibility and to establish guidelines for the use of the ATAS fixation for the subaxial cervical spine injury.Fifty normal cervical spines had radiographs to determine the proposed screw trajectory (the screw length and insertion angle) and the interbody graft-related parameters (the disc height and depth, and the distance between anterior vertebral margin and the screw) for all levels of the subaxial cervical spine. Following screw insertion in 8 preserved human cadaver specimens, surgical simulation and dissection verified the feasibility and safety of the ATAS fixation.Radiographic measurements showed the mean axial screw length and cephalic incline angle of all levels were 41.2 mm and 25.2°, respectively. The suitable depth of the interbody graft was >11.7 mm (the distance between anterior vertebral margin and the screw), but <17.1 mm (disc depth). Except the axial screw length, increase in all the measurements was seen with level up to C5-C6 segment. Simulated procedure in the preserved specimens demonstrated that ATAS fixation could be successfully performed at C2-C3, C3-C4, C4-C5, and C5-C6 levels, but impossible at C6-C7 due to the obstacle of the sternum. All screws were placed accurately. None of the screws penetrated into the spinal canal and caused fractures determined by dissecting the specimens.The anterior transdiscal axial screw fixation, as an alternative or supplementary instrumentation for subaxial cervical spine injuries, is feasible and safe with meticulous surgical planning.

  11. Employment of synthetic patch with augmentation of the long head of the biceps tendon in irreparable lesions of the rotator cuff: our technique applied to 60 patients.

    PubMed

    Vitali, Matteo; Cusumano, Andrea; Pedretti, Alberto; Naim Rodriguez, Nadim; Fraschini, Gianfranco

    2015-03-01

    The aim of our study was to evaluate the effectiveness of both clinical and functional benefits after the surgical repair of the rotator cuff in irreparable lesions using a synthetic patch with augmentation of the long head of the biceps (LHB) tendon. This is a retrospective study analysis of a randomized series of 60 patients (45 women and 15 men; average age 66 y) who underwent open repair of irreparable rotator cuff tear with synthetic patch using LHB tendon augmentation between 1999 and 2008.The inclusion criteria were: patients painful symptomatology, presenting a deficit in elevation, who are not responsive to physiotherapy, irreparable tear size, minimum follow-up of 36 months after surgery, and active and motivated patients. We used a control group of 60 patients treated without employment of the synthetic patch and LHB tendon augmentation.Patients were evaluated preoperatively and after 36 months with a Visual Analog Scale (VAS) and the University of California, Los Angeles (UCLA) shoulder rating scale and by measuring elevation of the scapular plane and strength with a dynamometer. All the patients were assessed preoperatively also with plain radiographs (anteroposterior and axillary views), ultrasound, and NMRI of the shoulder. The VAS and UCLA scores were also obtained 3 months postoperatively. Tendon integrity was assessed after 1 year by NMRI. Statistical analysis was conducted by 1-way analysis of variance between groups of treatment, with Dunnett post hoc correction for multiple comparisons. P-values ≤ 0.05 were considered as statistically significant. This surgical technique consisted in a short deltoid splitting, irreparable lesion evaluation, and, after tenodesis, the proximal segment of the LHB tendon was sutured to the remaining cuff tendons to fill the gap of the corresponding lesion. To shield the repaired rotator cuff we inserted a synthetic patch. Satisfactory results were achieved in 52 of the patients treated with this procedure; after

  12. Mersiline mesh in premaxillary augmentation.

    PubMed

    Foda, Hossam M T

    2005-01-01

    Premaxillary retrusion may distort the aesthetic appearance of the columella, lip, and nasal tip. This defect is characteristically seen in, but not limited to, patients with cleft lip nasal deformity. This study investigated 60 patients presenting with premaxillary deficiencies in which Mersiline mesh was used to augment the premaxilla. All the cases had surgery using the external rhinoplasty technique. Two methods of augmentation with Mersiline mesh were used: the Mersiline roll technique, for the cases with central symmetric deficiencies, and the Mersiline packing technique, for the cases with asymmetric deficiencies. Premaxillary augmentation with Mersiline mesh proved to be simple technically, easy to perform, and not associated with any complications. Periodic follow-up evaluation for a mean period of 32 months (range, 12-98 months) showed that an adequate degree of premaxillary augmentation was maintained with no clinically detectable resorption of the mesh implant.

  13. Cement augmentation versus extended dorsal instrumentation in the treatment of osteoporotic vertebral fractures: a biomechanical comparison.

    PubMed

    Weiser, L; Dreimann, M; Huber, G; Sellenschloh, K; Püschel, K; Morlock, M M; Rueger, J M; Lehmann, W

    2016-08-01

    Loosening of pedicle screws is a major complication of posterior spinal stabilisation, especially in the osteoporotic spine. Our aim was to evaluate the effect of cement augmentation compared with extended dorsal instrumentation on the stability of posterior spinal fixation. A total of 12 osteoporotic human cadaveric spines (T11-L3) were randomised by bone mineral density into two groups and instrumented with pedicle screws: group I (SHORT) separated T12 or L2 and group II (EXTENDED) specimen consisting of T11/12 to L2/3. Screws were augmented with cement unilaterally in each vertebra. Fatigue testing was performed using a cranial-caudal sinusoidal, cyclic (1.0 Hz) load with stepwise increasing peak force. Augmentation showed no significant increase in the mean cycles to failure and fatigue force (SHORT p = 0.067; EXTENDED p = 0.239). Extending the instrumentation resulted in a significantly increased number of cycles to failure and a significantly higher fatigue force compared with the SHORT instrumentation (EXTENDED non-augmented + 76%, p < 0.001; EXTENDED augmented + 87%, p < 0.001). The stabilising effect of cement augmentation of pedicle screws might not be as beneficial as expected from biomechanical pull-out tests. Lengthening the dorsal instrumentation results in a much higher increase of stability during fatigue testing in the osteoporotic spine compared with cement augmentation. Cite this article: Bone Joint J 2016;98-B:1099-1105. ©2016 The British Editorial Society of Bone & Joint Surgery.

  14. Transarticular fixation with a bioabsorptive screw for cervical spondylolisthesis.

    PubMed

    Kim, Kyongsong; Isu, Toyohiko; Omura, Tomoko; Morimoto, Daijiro; Kobayashi, Shiro; Teramoto, Akira

    2014-01-01

    Patients with cervical instability and intramedullary signal intensity changes on preoperative magnetic resonance imaging scans may benefit from not only cervical decompression but also from fusion surgery. Transarticular screw (TAS) fixation is a useful technique for posterior fixation. We first report treating a patient with cervical spondylosis and instability by cervical laminoplasty with TAS fixation using a bioabsorptive screw. A 66-year-old woman who had undergone surgery for carcinoma of the tongue via the anterior approach experienced cervical myelopathy. Radiologic findings showed severe cervical canal stenosis with myelomalacia and spondylolisthesis at C4/C5 with instability. We performed laminoplasty of C3 to C7 and TAS fixation of C4/C5 using a bioabsorptive poly-L-lactide screw that contained hydroxyapatite. Her postoperative course was uneventful, and at 1 year after treatment we confirmed C4/C5 fusion. Our method has advantages over metal instrumentation. The treated area can be evaluated with the use of magnetic resonance imaging, and the space left after screw absorption is filled by newly formed bone. Because our screw contains hydroxyapatite, it is osteoconductive. This may increase the fusion rate and induce substitution with new bone. To our knowledge this is the first patient treated by cervical posterior TAS fixation via the use of a bioabsorptive screw. Our method is safe and economical and free of the complications elicited by the use of metal parts. TAS fixation with a bioabsorptive screw may be appropriate for one fixation in patients without severe instability. Copyright © 2014 Elsevier Inc. All rights reserved.

  15. Utilization of paraspinal muscles for triggered EMG during thoracic pedicle screw placement.

    PubMed

    Silverstein, Justin W; Mermelstein, Laurence E

    2010-03-01

    A novel intraoperative neurophysiological technique for testing the integrity of the pedicle during screw fixation for spinal deformity surgery is presented. The thoracic paraspinal muscles at the appropriate level are used as the electromyogram (EMG) pick-up for direct current stimulation of the thoracic pedicle screw at that level. This technique is shown to give reliable and reproducible results. This technique is found to produce more reliable data than the methods most commonly used at this time.

  16. What is the learning curve for robotic-assisted pedicle screw placement in spine surgery?

    PubMed

    Hu, Xiaobang; Lieberman, Isador H

    2014-06-01

    Some early studies with robotic-assisted pedicle screw implantation have suggested these systems increase accuracy of screw placement. However, the relationship between the success rate of screw placement and the learning curve of this new technique has not been evaluated. We determined whether, as a function of surgeon experience, (1) the success rate of robotic-assisted pedicle screw placement improved, (2) the frequency of conversion from robotic to manual screw placement decreased, and (3) the frequency of malpositioned screws decreased. Between June 2010 and August 2012, the senior surgeon (IHL) performed 174 posterior spinal procedures using pedicle screws, 162 of which were attempted with robotic assistance. The use of the robotic system was aborted in 12 of the 162 procedures due to technical issues (registration failure, software crash, etc). The robotic system was successfully used in the remaining 150 procedures. These were the first procedures performed with the robot by the senior surgeon, and in this study, we divided the early learning curve into five groups: Group 1 (Patients 1-30), Group 2 (Patients 31-60), Group 3 (Patients 61-90), Group 4 (Patients 91-120), and Group 5 (Patients 121-150). One hundred twelve patients (75%) had spinal deformity and 80 patients (53%) had previous spine surgery. The accuracy of screw placement in the groups was assessed based on intraoperative biplanar fluoroscopy and postoperative radiographs. The results from these five groups were compared to determine the effect on the learning curve. The numbers of attempted pedicle screw placements were 359, 312, 349, 359, and 320 in Groups 1 to 5, respectively. The rates of successfully placed screws using robotic guidance were 82%, 93%, 91%, 95%, and 93% in Groups 1 to 5. The rates of screws converted to manual placement were 17%, 7%, 8%, 4%, and 7%. Of the robotically placed screws, the screw malposition rates were 0.8%, 0.3%, 1.4%, 0.8%, and 0%. The rate of successfully

  17. Minimally invasive dynamic hip screw for fixation of hip fractures

    PubMed Central

    Ho, Michael; Garau, Giorgio; Walley, Gayle; Oliva, Francesco; Panni, Alfredo Schiavone; Longo, Umile Giuseppe

    2008-01-01

    We compared a minimally invasive surgical technique to the conventional (open approach) surgical technique used in fixation of hip fractures with the dynamic hip screw (DHS) device. Using a case-control design (44 cases and 44 controls), we tested the null hypothesis that there is no difference between the two techniques in the following outcome measures: duration of surgery, time to mobilisation and weight bearing postoperatively, length of hospital stay, mean difference of pre- and postoperative haemoglobin levels, position of the lag screw of the DHS device in the femoral head, and the tip–apex distance. The minimally invasive DHS technique had significantly shorter duration of surgery and length of hospital stay. There was also less blood loss in the minimally invasive DHS technique. The minimally invasive DHS technique produces better outcome measures in the operating time, length of hospital stay, and blood loss compared to the conventional approach while maintaining equal fixation stability. PMID:18478227

  18. Caudally Directed Inferior Facetal and Transfacetal Screws for C1-C2 and C1-2-3 Fixation.

    PubMed

    Goel, Atul

    2017-04-01

    An alternative caudally directed C2 inferior facetal screw is described. Such screw insertion can form the axial stabilization point in cases undergoing atlantoaxial lateral mass plate/rod and screw fixation and those undergoing C1-2 and C1-2-3 spinal fixation. The C2 screw courses from the medial point of the pedicle-laminar junction and travels caudally and laterally toward the C2-3 articulation. Deploying a longer screw that traverses in a transarticular fashion into the facetal mass of C3 vertebra, one can perform C1-2-3 stabilization. Sixteen patients underwent C2 inferior facetal or C2-3 transarticular screw in combination with a C1 screw for atlantoaxial fixation. Three of these patients with multilevel spinal instability underwent atlantoaxial and C2-3 fixation using the discussed technique. The technical issues, anatomic subtleties, and indication for use of the C2 inferior facetal screws are discussed. With an average follow-up of 9 months, all screws have successfully provided stability that resulted in arthrodesis of the treated spinal segments. A caudally directed C2 inferior facetal screw can enhance the armamentarium of the surgeon, provide an alternative to conventional techniques or a bailout option, and add to the safety of the procedure of atlantoaxial lateral mass fixation in anatomically challenged situations. Copyright © 2017 Elsevier Inc. All rights reserved.

  19. Long iliac screw fixation in a case of isthmic spondyloptosis.

    PubMed

    Vilela, Marcelo D; Braga, Bruno P; Pedrosa, Hugo A S

    2017-01-01

    We report the case of a patient with a spondyloptosis who presented with progressive deformity and worsening neurological deficits. The patient had two previous lumbosacral instrumented fusions. A salvage revision surgery was performed, in which long iliac screws along with anterior column support at L5-S1 were used to immobilize the lumbosacral junction. Two years after the procedure a solid fusion is seen along with marked neurological improvement. Pelvic fixation using long iliac screws is a very useful technique that can be employed when revision surgery for high-grade spondylolisthesis is needed.

  20. Range of motion, sacral screw and rod strain in long posterior spinal constructs: a biomechanical comparison between S2 alar iliac screws with traditional fixation strategies

    PubMed Central

    Field, Antony; Ferrara, Lisa A.; Freeman, Andrew L.; Phan, Kevin

    2016-01-01

    Background S1 screw failure and L5/S1 non-union are issues with long fusions to S1. Improved construct stiffness and S1 screw offloading can help avoid this. S2AI screws have shown to provide similar stiffness to iliac screws when added to L3–S1 constructs. We sought to examine and compare the biomechanical effects on an L2–S1 pedicle screw construct of adding S2AI screws, AxiaLIF, L5–S1 interbody support via transforaminal lumbar interbody fusion (TLIF), and to examine the effect of the addition of cross connectors to each of these constructs. Methods Two S1 screws and one rod with strain gauges (at L5/S1) were used in L2–S1 screw-rod constructs in 7 L1-pelvis specimens (two with low BMD). ROM, S1 screw and rod strain were assessed using a pure-moment flexibility testing protocol. Specimens were tested intact, and then in five instrumentation states consisting of: (I) Pedicle screws (PS) L2–S1; (II) PS + S2AI screws; (III) PS + TLIF L5/S1; (IV) PS + AxiaLIF L5/S1; (V) PS + S2AI + AxiaLIF L5/S1. The five instrumentation conditions were also tested with crosslinks at L2/3 and S1/2. Tests were conducted in flexion-extension, lateral bending and axial torsion with no compressive preload. Results S2A1 produces reduced S1 screw strain for flexion-extension, lateral bending and axial torsion, as well as reduced rod strain in lateral bending and axial torsion in comparison to AxiaLIF and interbody instrumentation, at the expense of increased rod flexion-extension strain. Cross-connectors may have a role in further reduction of S1 screw and rod strain. Conclusions From a biomechanical standpoint, the use of the S2AI technique is at least equivalent to traditional iliac screws, but offers lower prominence and ease of assembly compared to conventional sacroiliac stabilization. PMID:28097243

  1. Accuracy of Free Hand Pedicle Screw Installation in the Thoracic and Lumbar Spine by a Young Surgeon: An Analysis of the First Consecutive 306 Screws Using Computed Tomography

    PubMed Central

    Lee, Chang-Hyun; Kim, Yongjung J; Kim, Ki-Jeong; Jahng, Tae-Ahn; Kim, Hyun-Jib

    2014-01-01

    Study Design A retrospective cross-sectional study. Purpose The purpose of this study is to evaluate the accuracy and safety of free-hand pedicle screw insertion performed by a young surgeon. Overview of Literature Few articles exist regarding the safety of the free-hand technique without inspection by an experienced spine surgeon. Methods The index surgeon has performed spinal surgery for 2 years by himself. He performed fluoroscopy-assisted pedicle screw installation for his first year. Since then, he has used the free-hand technique. We retrospectively reviewed the records of all consecutive patients undergoing pedicle screw installation using the free-hand technique without fluoroscopy in the thoracic or lumbar spine by the index surgeon. Incidence and extent of cortical breach by misplaced pedicle screw was determined by a review of postoperative computed tomography (CT) images. Results A total of 36 patients received 306 free-hand placed pedicle screws in the thoracic or lumbar spine. A total of 12 screws (3.9%) were identified as breaching the pedicle in 9 patients. Upper thoracic spine was the most frequent location of screw breach (10.8%). Lateral breach (2.3%) was more frequent than any other direction. Screw breach on the right side (9 patients) was more common than that on the left side (3 patients) (p<0.01). Conclusions An analysis by CT scan shows that young spine surgeons who have trained under the supervision of an experienced surgeon can safely place free-hand pedicle screws with an acceptable breach rate through repetitive confirmatory steps. PMID:24967036

  2. [Management of Odontoid Fractures with Compression Screw and Anterior Transarticular Screw Fixation in Elderly Patients].

    PubMed

    Kočiš, J; Kelbl, M; Veselý, R; Kočiš, T

    2017-01-01

    more reliable, owing to the fears of a failure of osteosynthesis by anterior approach. The most frequent cause of a failure is the pulling out of the screw through the anterior wall of dens axis base in patients with osteoporosis. Concurrently, the anterior approach is regarded as more considerate. The ATS fixation increases stability compared to isolated compression osteosynthesis, which makes it possible to manage the dens axis fractures by a more considerate anterior approach. CONCLUSIONS The ATS is a method that increases stability of compression osteosynthesis in managing dens axis in elderly patients. Key words: dens axis, upper cervical spine fracture, elderly, triple screw technique, anterior transarticular C1/2 stabilization.

  3. [Flexor hallucis tendon transfer combined with an interference screw reconstruction for chronic Achilles tendon rupture of Kuwada IV].

    PubMed

    Du, Jun-feng; Zhu, Yang-yi

    2015-05-01

    To explore the clinical effect of interference screw and flexor hallucis longus tendon as augmentation material in repair of chronic Achilles tendon rupture. From September 2010 to June 2012,26 patients with chronic Achilles tendon rupture were treated, including 18 males and 8 females with an average age of 44.2 years old (20 to 66 years old). All patients were unilateral damage. MRI showed the Achilles tendon.ends' distance was 6.0 to 9.0 cm. The postoperative complications were observed. The curative effect was assessed by American Orthopedic Foot and Ankle Society and Leppilahti score. All the 26 patients were followed up for 18 to 68 months (means 30.4 months). No neurological injury and infection of incision occurred, all patients were stage I incision healing. The shape and function of the ankle were recovered well. The average AOFAS score increased from 52.27±12.30 preoperatively to 90.92±6.36 postoperatively. Leppilahti Achilles Tendon Repair score increased from 34.23±12.86 preoperatively to 90.00±5.10 postoperatively. The flexor hallucis tendon transfer with an interference screw technique for repairing the chronic Achilles tendon rupture of type IV of Kuwada had advantages of simple operation, quick recovery, firm tendon fixation, and less complications.

  4. Augmentation of proximal femoral nail in unstable trochanteric fractures

    PubMed Central

    Gadegone, Wasudeo M.; Shivashankar, Bhaskaran; Lokhande, Vijayanad; Salphale, Yogesh

    2017-01-01

    Introduction: Biomechanically proximal femoral nail (PFN) is a better choice of implant, still it is associated with screw breakage, cut out of screw through femoral head, Z effect, reverse Z effect, and lateral migration of screws. The purpose of this study is to evaluate the results of augmented PFN in terms of prevention of postoperative complications and failure rates in unstable trochanteric fractures. Material and methods: We carried out a prospective study of 82 cases with unstable trochanteric femoral fractures from April 2010 to December 2015. Forty-two females and 40 males in the age group between 58 and 81 years were included in this study. There were 45 cases of AO 31 A2 (2.2, 2.3) and 37 cases of AO 31 A3 (3.1, 3.2, 3.3). Fractures were fixed by PFN with augmentation by an additional screw from trochanter to inferior quadrant of femoral head or cerclage wire to strengthen the lateral trochanteric wall. Results: The bone healing is observed in all the cases in the mean period of 14.2 weeks. Nine patients developed complications, including lateral migration of neck screws (n = 5), Z effect (n = 1), infection (n = 2), and breakage of distal interlocking bolt in one case. Removal of screws was required in five cases. Patients were followed up for a mean of 8.4 months. At the end of follow-up the Salvati and Wilson hip function was 32 (out of 40) in 88% of patients. Conclusion: The stabilization of lateral trochanteric wall with additional screw or cerclage wire increases the stability of construct. PMID:28186871

  5. Cement augmentation of implants--no general cure in osteoporotic fracture treatment. A biomechanical study on non-displaced femoral neck fractures.

    PubMed

    Hofmann-Fliri, Ladina; Nicolino, Tomas I; Barla, Jorge; Gueorguiev, Boyko; Richards, R Geoff; Blauth, Michael; Windolf, Markus

    2016-02-01

    Femoral neck fractures in the elderly are a common problem in orthopedics. Augmentation of screw fixation with bone cement can provide better stability of implants and lower the risk of secondary displacement. This study aimed to investigate whether cement augmentation of three cannulated screws in non-displaced femoral neck fractures could increase implant fixation. A femoral neck fracture was simulated in six paired human cadaveric femora and stabilized with three 7.3 mm cannulated screws. Pairs were divided into two groups: conventional instrumentation versus additional cement augmentation of screw tips with 2 ml TraumacemV+ each. Biomechanical testing was performed by applying cyclic axial load until failure. Failure cycles, axial head displacement, screw angle changes, telescoping and screw cut-out were evaluated. Failure (15 mm actuator displacement) occurred in the augmented group at 12,500 cycles (± 2,480) compared to 15,625 cycles (± 4,215) in the non-augmented group (p = 0.041). When comparing 3 mm vertical displacement of the head no significant difference (p = 0.72) was detected between the survival curves of the two groups. At 8,500 load-cycles (early onset failure) the augmented group demonstrated a change in screw angle of 2.85° (± 0.84) compared to 1.15° (± 0.93) in the non-augmented group (p = 0.013). The results showed no biomechanical advantage with respect to secondary displacement following augmentation of three cannulated screws in a non-displaced femoral neck fracture. Consequently, the indication for cement augmentation to enhance implant anchorage in osteoporotic bone has to be considered carefully taking into account fracture type, implant selection and biomechanical surrounding. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

  6. Effect of surface coating on the screw loosening of dental abutment screws

    NASA Astrophysics Data System (ADS)

    Park, Chan-Ik; Choe, Han-Cheol; Chung, Chae-Heon

    2004-12-01

    Regardless of the type of performed restoration, in most cases, a screw connection is employed between the abutment and implant. For this reason, implant screw loosening has remained a problem in restorative practices. The purpose of this study was to compare the surface of coated/plated screws with titanium and gold alloy screws and to evaluate the physical properties of coated/plated material after scratch tests via FE-SEM (field emission scanning electron microscopy) investigation. GoldTite, titanium screws provided by 3i (Implant Innovation, USA) and TorqTite, titanium screws by Steri-Oss (Nobel Biocare, USA) and gold screws and titanium screws by AVANA (Osstem Implant, Korea) were selected for this study. The surface, crest, and root of the abutment screws were observed by FE-SEM. A micro-diamond needle was also prepared for the scratch test. Each abutment screw was fixed, and a scratch on the surface of the head region was made at constant load and thereafter the fine trace was observed with FE-SEM. The surface of GoldTite was smoother than that of other screws and it also had abundant ductility and malleability compared with titanium and gold screws. The scratch tests also revealed that teflon particles were exfoliated easily in the screw coated with teflon. The titanium screw had rough surface and low ductility. The clinical use of gold-plated screws is recommended as a means of preventing screw loosening.

  7. Surgical outcomes of temporary short-segment instrumentation without augmentation for thoracolumbar burst fractures.

    PubMed

    Aono, Hiroyuki; Tobimatsu, Hidekazu; Ariga, Kenta; Kuroda, Masayuki; Nagamoto, Yukitaka; Takenaka, Shota; Furuya, Masayuki; Iwasaki, Motoki

    2016-06-01

    Short-segment posterior spinal instrumentation for thoracolumbar burst fracture provides superior correction of kyphosis by an indirect reduction technique, but it has a high failure rate. We investigated the clinical and radiological results of temporary short-segment pedicle screw fixation without augmentation performed for thoracolumbar burst fractures with the goal of avoiding treatment failure by waiting to see if anterior reconstruction was necessary. We studied 27 consecutive patients with thoracolumbar burst fracture who underwent short-segment posterior instrumentation using ligamentotaxis with Schanz screws and without augmentation. Implants were removed approximately 1 year after surgery. Neurological function, kyphotic deformity, canal compromise, fracture severity, and back pain were evaluated prospectively. After surgery, all patients with neurological deficit had improvement equivalent to at least 1 grade on the American Spinal Injury Association impairment scale and had fracture union. Kyphotic deformity was reduced significantly, and maintenance of the reduced vertebra was successful even without vertebroplasty, regardless of load-sharing classification. Therefore, no patients required additional anterior reconstruction. Postoperative correction loss occurred because of disc degeneration, especially after implant removal. Ten patients had increasing back pain, and there are some correlations between the progression of kyphosis and back pain aggravation. Temporary short-segment fixation without augmentation yielded satisfactory results in reduction and maintenance of fractured vertebrae, and maintenance was independent of load-sharing classification. Kyphotic change was caused by loss of disc height mostly after implant removal. Such change might have been inevitable because adjacent endplates can be injured during the original spinal trauma. Kyphotic change after implant removal may thus be a limitation of this surgical procedure. Copyright © 2016

  8. Association between bicortical screw fixation at upper instrumented vertebra and risk for upper instrumented vertebra fracture.

    PubMed

    Park, Young-Seop; Hyun, Seung-Jae; Choi, Ho Yong; Kim, Ki-Jeong; Jahng, Tae-Ahn

    2017-03-03

    OBJECTIVE The aim of this study was to investigate the risk of upper instrumented vertebra (UIV) fractures associated with UIV screw fixation (unicortical vs bicortical) and polymethylmethacrylate (PMMA) augmentation after adult spinal deformity surgery. METHODS A single-center, single-surgeon consecutive series of adult patients who underwent lumbar fusion for ≥ 4 levels (that is, the lower instrumented vertebra at the sacrum or pelvis and the UIV of the thoracolumbar spine [T9-L2]) were retrospectively reviewed. Age, sex, follow-up duration, sagittal UIV angle immediately postoperatively including several balance-related parameters (lumbar lordosis [LL], pelvic incidence, and sagittal vertical axis), bone mineral density, UIV screw fixation type, UIV PMMA augmentation, and UIV fracture were evaluated. Patients were divided into 3 groups: Group U, 15 patients with unicortical screw fixation at the UIV; Group P, 16 with bicortical screw fixation and PMMA augmentation at the UIV; and Group B, 21 with bicortical screw fixation without PMMA augmentation at the UIV. RESULTS The mean number of levels fused was 6.5 ± 2.5, 7.5 ± 2.5, and 6.5 ± 2.5; the median age was 50 ± 29, 72 ± 6, and 59 ± 24 years; and the mean follow-up was 31.5 ± 23.5, 13 ± 6, and 24 ± 17.5 months in Groups U, P, and B, respectively (p > 0.05). There were no significant differences in balance-related parameters (LL, sagittal vertical axis, pelvic incidence-LL, and so on) among the groups. UIV fracture rates in Groups U (0%), P (31.3%), and B (42.9%) increased in sequence by group (p = 0.006). UIV bicortical screw fixation increased the risk for UIV fracture (OR 5.39; p = 0.02). CONCLUSIONS Bicortical screw fixation at the UIV is a major risk factor for early UIV compression fracture, regardless of whether a thoracolumbosacral orthosis is used. To reduce the proximal junctional failure, unicortical screw fixation at the UIV is essential in adult spinal deformity correction surgery.

  9. Vascularized bone grafting fixed by biodegradable magnesium screw for treating osteonecrosis of the femoral head.

    PubMed

    Zhao, Dewei; Huang, Shibo; Lu, Faqiang; Wang, Benjie; Yang, Lei; Qin, Ling; Yang, Ke; Li, Yangde; Li, Weirong; Wang, Wei; Tian, Simiao; Zhang, Xiuzhi; Gao, Wenbin; Wang, Zongpu; Zhang, Yu; Xie, Xinhui; Wang, Jiali; Li, Junlei

    2016-03-01

    Hip-preserving surgery with vascularized bone graft implantation has been widely practiced in treating osteonecrosis of the femoral head (ONFH). However, the current approach presents a drawback, in which the implanted bone graft without screw fixation may slip or exhibit a certain degree of displacement postoperatively. This study was designed to investigate the application potential of biodegradable magnesium (Mg) screws for the fixation of vascularized bone graft in ONFH patients. Forty-eight patients were randomly divided into two groups: the Mg screw group (vascularized bone grafting fixed by Mg screws) and the control group (vascularized bone grafting without fixation). During 12 month follow-up period after surgery, treatment outcomes in patients were assessed by multiple imaging techniques including x-ray and computed tomography (CT) scanning as well as functional recovery Harris hip score (HHS). The temporal changes in serum levels of Mg, Ca, and P as well as in vivo degradation rate of Mg screws were determined. The absence of potential adverse effects induced by degradation products from Mg screws on surrounding bone tissue was validated via CT imaging analysis. HHS was significantly improved in the Mg screw group when compared to the control group. X-ray imaging analysis showed that the screw shape did not show significant alteration due to the diameter of Mg screws measured with approximate 25% reduction within 12 months post-surgically. The postoperative serum levels of Ca, Mg, and P, which are relevant for liver and kidney function, were all within normal physiological range in all patients of both groups. The use of biodegradable Mg screws may provide a promising bone graft-screw fixation route in treating ONFH and present considerable potential for orthopedic applications.

  10. Three-dimensional Fluoroscopy-based Navigation for the Pedicle Screw Placement in Patients with Primary Invasive Spinal Tumors

    PubMed Central

    Jin, Bo; Su, Yi-Bing; Zhao, Ji-Zong

    2016-01-01

    Background: Although pedicle screw placement (PSP) is a well-established technique for spine surgery, the treatment of patients with primary invasive spinal tumor (PIST) has high surgical risks secondary to destroyed pedicles. Intraoperative three-dimensional fluoroscopy-based navigation (ITFN) system permits safe and accurate instrumentation of the spine with the advantage of obtaining intraoperative real-time three-dimensional images and automatic registration. The aim of this study is to evaluate the feasibility and accuracy of PSP using ITFN system for patients afflicted with PIST in the thoracic spine. Methods: Fifty-one patients diagnosed with PISTs were retrospectively analyzed, and 157 pedicles screws were implanted in 23 patients using the free-hand technique (free-hand group) and 197 pedicle screws were implanted in 28 patients using the ITFN system (ITFN group). Modified classification of Gertzbein and Robbins was used to evaluate the accuracy of PSP, and McCormick classification was applied for assessment of neurological function. Demographic data and factors affecting accuracy of screw insertion were compared using independent t-test while comparison of accuracy of screw insertion between the two groups was analyzed with Chi-square test. Results: Of 51 patients, 39 demonstrated improved neurological status and the other 12 patients reported that symptoms remained the same. In the free-hand group, 145 screws (92.4%) were Grade I, 9 screws (5.7%) were Grade II, and 3 screws (1.9%) were Grade III. In the ITFN group, 192 screws (97.4%) were Grade I, 5 screws (2.6%) were Grade II, and no Grade III screw was detected. Statistical analysis showed that the accuracies of pedicle screws in the two groups are significantly different (χ2 = 4.981, P = 0.026). Conclusions: The treatments of PISTs include total tumor resection and reconstruction of spine stability. The ITFN system provides a high accuracy of pedicle screw placement. PMID:27779161

  11. Anatomic considerations of costotransverse screw placement in the thoracic spine.

    PubMed

    Xu, R; Ebraheim, N A; Ou, Y; Skie, M; Yeasting, R A

    2000-04-01

    Numerous techniques have been reported to restore spinal stability and to correct spinal deformities, including rods with wires/hooks, and rods or plates with pedicular screws. It was thought that posterior fixation of the thoracic spine through the costotransverse joint may be another alternative. Nine cadavers were obtained for study of screw fixation of the costotransverse joint for posterior thoracic instrumentation. The entrance point for screw insertion was designed to be at the posterior center of the clubbed extremity of the transverse process. From this point, a 3-mm drill bit was used to create the screw path penetrating the costotransverse joint and the ventral cortex of the rib. Under direct visualization of the costotransverse joint, the drill bit was directed parallel to the sagittal plane and toward the upper portion of the rib. Measurements included the screw path length and sagittal angulation. Also, the distance between the superior borders of the transverse process and the tubercle of the rib and the anatomic relationship of the drill bit exit to the intercostal vessels and nerves were evaluated. The maximum length of the screw path was found at T1 (19.7 mm), whereas the minimum length was noted at T4-T5 (13.9 mm). This value decreased gradually from T1 to T4-T5, and slightly increased to T10. The larger sagittal angles of the screw path were found at the levels of T1-T4 (78-86 degrees ), whereas the smaller were noted at the levels below T5 (53-61 degrees ). The mean distance between the superior borders of the transverse process and the tubercle of the rib was smaller at T1-T5 (0.2-0.4 mm), and significantly increased to T8 (5. 1 mm), and then slightly decreased to T10. The variation of this parameter was remarkable. All of the exit points for the drill bit were located in the upper half of the rib, and away from the intercostal vessels. The ideal screw orientation is parallel to the sagittal plane, and angled 80-90 degrees relative to the

  12. Screw depth sounding in proximal humerus fractures to avoid iatrogenic intra-articular penetration.

    PubMed

    Bengard, Matthew J; Gardner, Michael J

    2011-10-01

    Unstable and displaced proximal humerus fractures remain a treatment challenge. The use of locked plates has improved construct stability, but complication rates remain high. Biomechanical studies have emphasized the importance of anchoring screws in the subchondral bone of the humeral head to improve implant stability. However, the spherical shape of the proximal humerus and the limited tactile sensation of its soft cancellous bone make determining accurate screw length difficult, and reported rates of intraoperative screw penetration are high. Iatrogenic screw penetration, even if recognized and corrected before leaving the operating room, may lead to late failure. We present a simple technique of quickly and safely determining screw length using a blunt-tipped Kirschner wire and instruments found in basic orthopaedic sets.

  13. Preoperative CT planning of screw length in arthroscopic Latarjet.

    PubMed

    Hardy, Alexandre; Gerometta, Antoine; Granger, Benjamin; Massein, Audrey; Casabianca, Laurent; Pascal-Moussellard, Hugues; Loriaut, Philippe

    2016-08-25

    The Latarjet procedure has shown its efficiency for the treatment of anterior shoulder dislocation. The success of this technique depends on the correct positioning and fusion of the bone block. The length of the screws that fix the bone block can be a problem. They can increase the risk of non-union if too short or be the cause of nerve lesion or soft tissue discomfort if too long. Suprascapular nerve injuries have been reported during shoulder stabilisation surgery up to 6 % of the case. Bone block non-union depending on the series is found around 20 % of the cases. The purpose of this study was to evaluate the efficiency of this CT preoperative planning to predict optimal screws length. The clinical importance of this study lies in the observation that it is the first study to evaluate the efficiency of CT planning to predict screw length. Inclusion criteria were patients with chronic anterior instability of the shoulder with an ISIS superior to 4. Exclusion criteria were patients with multidirectional instability or any previous surgery on this shoulder. Thirty patients were included prospectively, 11 of them went threw a CT planning, before their arthroscopic Latarjet. Optimal length of both screws was calculated, adding the size of the coracoid at 5 and 15 mm from the tip to the glenoid. Thirty-two-mm screws were used for patients without planning. On a post-operative CT scan with 3D reconstruction, the distance between the screw tip and the posterior cortex was measured. A one-sample Wilcoxon test was used to compare the distance from the tip of the screw to an acceptable positioning of ±2 mm from the posterior cortex. In the group without planning, screw 1 tended to differ from the acceptable positioning: mean 3.44 mm ± 3.13, med 2.9 mm, q1; q3 [0.6; 4.75] p = 0.1118, and screw 2 differed significantly from the acceptable position: mean 4.83 mm ± 4.11, med 3.7 mm, q1; q3 [1.7; 5.45] p = 0.0045. In the group with planning, position of

  14. Effect of different inner core diameters on structural strength of cannulated pedicle screws under various lumbar spine movements.

    PubMed

    Chang, Chia-Ming; Lai, Yu-Shu; Cheng, Cheng-Kung

    2017-08-15

    Currently, cannulated pedicle screws have been widely used in minimal invasive or navigation techniques. However, the stress distribution and the strength of different core diameters of cannulated screw are not clear. This study aimed to investigate the mechanical strength of cannulated screws with different inner core diameter under various lumbar spine movements using finite element analysis. The results showed that the von-Mises stress of a cannulated screw was larger than that of a solid screw in all loading conditions, especially above 2 mm in cannulated core diameter. In lateral bending, extension, and flexion, the maximum von-Mises stress was found approximate to the proximal thread for all types of screws. In rotation condition, the maximum von-Mises stress was located at the middle of the screw. Additionally, the difference in stiffness of instrumented levels was not significant among four screws under the same loading condition. Cannulated screws could provide enough stability for the vertebral body fusion comparing to solid screws. The diameter of cannulated core is suggested not to exceed 2.0 mm.

  15. Craniofacial vertical bone augmentation: a comparison between 3D printed monolithic monetite blocks and autologous onlay grafts in the rabbit.

    PubMed

    Tamimi, Faleh; Torres, Jesus; Gbureck, Uwe; Lopez-Cabarcos, Enrique; Bassett, David C; Alkhraisat, Mohammad H; Barralet, Jake E

    2009-10-01

    Onlay autografting is amongst the most predictable techniques for craniofacial vertical bone augmentation, however, complications related to donor site surgery are common and synthetic alternatives to onlay autografts are desirable. Recent studies have shown that the acidic calcium phosphates, brushite and monetite, are osteoconductive, osteoinductive and resorb faster in vivo than hydroxyapatite. Moreover, they can be 3D printed allowing precise host bone-implant conformation. The objectives of this study were to confirm that craniofacial screw fixation of 3D printed monetite blocks was possible and to compare the resulting vertical bone augmentation with autograft. 3D printed monolithic monetite onlay implants were fixed with osteosynthesis screws on the calvarial bone surface of New Zealand rabbits. After 8 weeks, integration between the implant and the calvarial bone surface was observed in all cases. Histomorphometry revealed that 42% of the monetite was resorbed and that the new bone formed within the implant occupied 43% of its volume, sufficient for immediate dental implant placement. Bone tissue within the autologous onlay occupied 60% of the volume. We observed that patterns of regeneration within the implants differed throughout the material and propose that this was due to the anatomy and blood supply pattern in the region. Rapid prototyped monetite being resorbable osteoconductive and osteoinductive would appear to be a promising biomaterial for many bone regeneration strategies.

  16. Accuracy Assessment of Using Rapid Prototyping Drill Templates for Atlantoaxial Screw Placement: A Cadaver Study

    PubMed Central

    Guo, Shuai; Lu, Teng; Hu, Qiaolong; Yang, Baohui; He, Xijing

    2016-01-01

    Purpose. To preliminarily evaluate the feasibility and accuracy of using rapid prototyping drill templates (RPDTs) for C1 lateral mass screw (C1-LMS) and C2 pedicle screw (C2-PS) placement. Methods. 23 formalin-fixed craniocervical cadaver specimens were randomly divided into two groups. In the conventional method group, intraoperative fluoroscopy was used to assist the screw placement. In the RPDT navigation group, specific RPDTs were constructed for each specimen and were used intraoperatively for screw placement navigation. The screw position, the operating time, and the fluoroscopy time for each screw placement were compared between the 2 groups. Results. Compared with the conventional method, the RPDT technique significantly increased the placement accuracy of the C2-PS (p < 0.05). In the axial plane, using RPDTs also significantly increased C1-LMS placement accuracy (p < 0.05). In the sagittal plane, although using RPDTs had a very high accuracy rate (100%) in C1-LMS placement, it was not statistically significant compared with the conventional method (p > 0.05). Moreover, the RPDT technique significantly decreased the operating and fluoroscopy times. Conclusion. Using RPDTs significantly increases the accuracy of C1-LMS and C2-PS placement while decreasing the screw placement time and the radiation exposure. Due to these advantages, this approach is worth promoting for use in the Harms technique. PMID:28004004

  17. Accuracy Assessment of Using Rapid Prototyping Drill Templates for Atlantoaxial Screw Placement: A Cadaver Study.

    PubMed

    Guo, Shuai; Lu, Teng; Hu, Qiaolong; Yang, Baohui; He, Xijing; Li, Haopeng

    2016-01-01

    Purpose. To preliminarily evaluate the feasibility and accuracy of using rapid prototyping drill templates (RPDTs) for C1 lateral mass screw (C1-LMS) and C2 pedicle screw (C2-PS) placement. Methods. 23 formalin-fixed craniocervical cadaver specimens were randomly divided into two groups. In the conventional method group, intraoperative fluoroscopy was used to assist the screw placement. In the RPDT navigation group, specific RPDTs were constructed for each specimen and were used intraoperatively for screw placement navigation. The screw position, the operating time, and the fluoroscopy time for each screw placement were compared between the 2 groups. Results. Compared with the conventional method, the RPDT technique significantly increased the placement accuracy of the C2-PS (p < 0.05). In the axial plane, using RPDTs also significantly increased C1-LMS placement accuracy (p < 0.05). In the sagittal plane, although using RPDTs had a very high accuracy rate (100%) in C1-LMS placement, it was not statistically significant compared with the conventional method (p > 0.05). Moreover, the RPDT technique significantly decreased the operating and fluoroscopy times. Conclusion. Using RPDTs significantly increases the accuracy of C1-LMS and C2-PS placement while decreasing the screw placement time and the radiation exposure. Due to these advantages, this approach is worth promoting for use in the Harms technique.

  18. The surgical learning curve and accuracy of minimally invasive lumbar pedicle screw placement using CT based computer-assisted navigation plus continuous electromyography monitoring – a retrospective review of 627 screws in 150 patients

    PubMed Central

    McMillen, Jason

    2014-01-01

    Objective This study retrospectively assessed the accuracy of placement of lumbar pedicle screws placed by a single surgeon using a minimally-invasive, intra-operative CT-based computer navigated technique in combination with continuous electromyography (EMG) monitoring. The rates of incorrectly positioned screws were reviewed in the context of the surgeon's experience and learning curve. Methods Data was retrospectively reviewed from all consecutive minimally invasive lumbar fusions performed by the primary author over a period of over 4 years from April 2008 until October 2012. All cases that had utilized computer-assisted intra-operative CT-based image guidance and continuous EMG monitoring to guide percutaneous pedicle screw placement were analysed for the rates of malposition of the pedicle screws. Pedicle screw malposition was defined as having occurred if the screw trajectory was adjusted intraoperatively due to positive EMG responses, or due to breach of the pedicle cortex by more than 2mm on intraoperative CT imaging performed at the end of the instrumentation procedure. Further analysis of the data was undertaken to determine if the rates of malposition changed with the surgeon's experience with the technique. Results Six hundred and twenty-seven pedicle screws were placed in one hundred and fifty patients. The overall rate of intraoperative malposition and subsequent adjustment of pedicle screw placement was 3.8% (24 of 627 screws). Screw malposition was detected by intraoperative CT imaging. Warning of potential screw misplacement was provided by use of the EMG monitoring. With increased experience with the technique, rates of intraoperative pedicle screw malposition were found to decrease from 5.1% of screws in the first fifty patients, to 2.0% in the last 50 patients. Only one screw was suboptimally placed at the end of surgery, which did not result in a neurological deficit. Conclusion The use of CT-based computer-assisted navigation in combination

  19. A review of ligament augmentation with the InternalBrace™: the surgical principle is described for the lateral ankle ligament and ACL repair in particular, and a comprehensive review of other surgical applications and techniques is presented.

    PubMed

    Mackay, Gordon M; Blyth, Mark J G; Anthony, Iain; Hopper, Graeme P; Ribbans, William J

    2015-05-01

    This article reviews the surgical decision-making considerations when preparing to undertake an anatomic ligament repair with augmentation using the InternalBrace™. Lateral ankle ligament stabilization of the Broström variety and ACL repair in particular are used to illustrate its application. The InternalBrace™ supports early mobilization of the repaired ligament and allows the natural tissues to progressively strengthen. The principle established by this experience has resulted in its successful application to other distal extremity ligaments including the deltoid, spring, and syndesmosis complex. Knee ligament augmentation with the InternalBrace™ has been successfully applied to all knee ligaments including anterior cruciate ligament (ACL), posterior cruciate ligament (PCL), medial collateral ligament (MCL), lateral collateral ligament (LCL), anterolateral ligament (ALL), and patellofemoral ligament (PFL). The surgical technique and early results will be reviewed including multi-ligament presentations. Upper limb experience with acromioclavicular (AC) joint augmentation and ulnar collateral ligament (UCL) repair of the elbow with the InternalBrace™ will also be discussed. This article points to a change in orthopaedic practice positioning reconstruction as a salvage procedure that has additional surgical morbidity and should be indicated only if the tissues fail to heal adequately after augmentation and repair.

  20. Short-term healing following the use of calcium sulfate as a grafting material for sinus augmentation: a clinical report.

    PubMed

    Pecora, G E; De Leonardis, D; Della Rocca, C; Cornelini, R; Cortesini, C

    1998-01-01

    Because of the frequent lack of bone in the posterior maxilla, sinus augmentation has become a commonly practiced treatment modality. Many different materials have been used for augmenting the sinus, and the ideal graft is yet to be found. The present article reports the results of sinuses grafted with calcium sulfate in 2 patients. Bone biopsies were harvested 9 months after the augmentation procedure. In the first patient, 3 titanium threaded-cylinder implants were placed in the grafted area after 9 months, while in the second, 1 acid-etched, screw-shaped titanium implant was placed simultaneously with the graft. Light microscopic evaluation revealed new bone formation with ongoing remodeling and progressive lamellar maturation in the specimens. No remnants of the alloplastic material were detectable in any section, either within the bone or in the medullary tissue. When reevaluated at the uncovering procedure, the implants were radiographically and clinically judged to be osseointegrated. These observations suggest that, when used in the appropriate form and with the proper technique, calcium sulfate is a promising graft material for sinus augmentation, producing adequate quantity and quality of new bone for implant placement.

  1. Strategies and Challenges in Simultaneous Augmentation Mastopexy.

    PubMed

    Spring, Michelle A; Hartmann, Emily C; Stevens, W Grant

    2015-10-01

    Simultaneous breast augmentation and mastopexy is a common procedure often considered to be one of the most difficult cosmetic breast surgeries. One-stage augmentation mastopexy was initially described more than 50 years ago. The challenge lies in the fact that the surgery has multiple opposing goals: to increasing the volume of a breast, enhance the shape, and simultaneously decrease the skin envelope. Successful outcomes in augmentation can be expected with proper planning, technique, and patient education. This article focuses on common indications for simultaneous augmentation mastopexy, techniques for safe and effective combined procedures, challenges of the procedure, and potential complications. Copyright © 2015 Elsevier Inc. All rights reserved.

  2. Metallurgical examination of gun barrel screws

    SciTech Connect

    Bird, E.L.; Clift, T.L.

    1996-06-01

    The examination was conducted to determine the extent of degradation that had occurred after a series of firings; these screws prevent live rounds of ammunition from being loaded into the firing chamber. One concern is that if the screw tip fails and a live round is accidentally loaded into the chamber, a live round could be fired. Another concern is that if the blunt end of the screw begins to degrade by cracking, pieces could become small projectiles during firing. All screws used in firing 100 rounds or more exhibited some degree degradation, which progressively worsened as the number of rounds fired increased. (SEM, metallography, x-ray analysis, and microhardness were used.) Presence of cracks in these screws after 100 fired rounds is a serious concern that warrants the discontinued use of these screws. The screw could be improved by selecting an alloy more resistant to thermal and chemical degradation.

  3. Cancellous Screws Are Biomechanically Superior to Cortical Screws in Metaphyseal Bone.

    PubMed

    Wang, Tim; Boone, Christopher; Behn, Anthony W; Ledesma, Justin B; Bishop, Julius A

    2016-09-01

    Cancellous screws are designed to optimize fixation in metaphyseal bone environments; however, certain clinical situations may require the substitution of cortical screws for use in cancellous bone, such as anatomic constraints, fragment size, or available instrumentation. This study compares the biomechanical properties of commercially available cortical and cancellous screw designs in a synthetic model representing various bone densities. Commercially available, fully threaded, 4.0-mm outer-diameter cortical and cancellous screws were tested in terms of pullout strength and maximum insertion torque in standard-density and osteoporotic cancellous bone models. Pullout strength and maximum insertion torque were both found to be greater for cancellous screws than cortical screws in all synthetic densities tested. The magnitude of difference in pullout strength between cortical and cancellous screws increased with decreasing synthetic bone density. Screw displacement prior to failure and total energy absorbed during pullout strength testing were also significantly greater for cancellous screws in osteoporotic models. Stiffness was greater for cancellous screws in standard and osteoporotic models. Cancellous screws have biomechanical advantages over cortical screws when used in metaphyseal bone, implying the ability to both achieve greater compression and resist displacement at the screw-plate interface. Surgeons should preferentially use cancellous over cortical screws in metaphyseal environments where cortical bone is insufficient for fixation. [Orthopedics.2016; 39(5):e828-e832.]. Copyright 2016, SLACK Incorporated.

  4. Management of hangman's fracture with percutaneous transpedicular screw fixation.

    PubMed

    Wu, Yao-Sen; Lin, Yan; Zhang, Xiao-Lei; Tian, Nai-Feng; Sun, Liao-Jun; Xu, Hua-Zi; Chi, Yong-Long; Pan, Zhi-Jun

    2013-01-01

    This study describes a percutaneous technique for C2 transpedicular screw fixation and evaluates its safety and efficacy in the treatment of patients with hangman's fracture. Ten patients with hangman's fracture were treated by percutaneous C2 transpedicular screw fixation. There are six males and four females, who were, based on the classification of Levine and Edwards, sorted as follows: type I fracture, three cases; type II, five cases; type IIa, two cases. The causes of injury were road traffic accident in six patients and falling injury in four patients. Other associated lesions included rib fractures (7 patients), head injuries (4 patients), and fractures of extremities (6 patients). The new technique was performed successfully in all cases. The average operation time was 98 min (range 60-130 min) and the estimated blood loss was 25 ml (range 15-40 ml). No complications such as vascular or neural structures injuries were found intraoperatively. Postoperative CT scans demonstrated that 17 (85 %) of 20 screws were placed satisfactorily, and 3 (15 %) screws showed perforations of the pedicle wall (<2 mm). These patients were asymptomatic and no further intervention was required postoperatively. After 8-25 months follow-up (mean 15.3 months), solid fusion was demonstrated by computed tomography. All cases got well-sagittal alignment and no angulation or dislocation was found at the segment of C2-C3. There was no loss of fixation. Clinical examination showed a full range of motion in the neck in all patients. The fluoroscopically assisted percutaneous C2 transpedicular screw fixation method is a technically feasible and minimally invasive technique for hangman's fracture.

  5. Safety and Efficacy of Power-Assisted Pedicle Tract Preparation and Screw Placement.

    PubMed

    Seehausen, Derek A; Skaggs, David L; Andras, Lindsay M; Javidan, Yashar

    2015-03-01

    Retrospective review of 1 surgeon's posterior spinal fusion cases. To assess the safety and efficacy of using power tools versus using manual tools to create pedicle tracts and place pedicle screws. This is the first study to report on the safety and efficacy of pedicle tract creation and pedicle screw placement using power tools. The study included 442 cases and 6412 pedicle screws. The manual tool cohort included 159 cases (1,870 screws, January 1, 2004 to June 30, 2007). The power tool cohort included 283 cases (4,542 screws, January 1, 2008 to August 29, 2012). Patient charts and radiographs were reviewed. The researchers recorded the number of screws placed and their positions. Screws were classified as failed if the patient returned to surgery for revision or removal of the screw. Operating and fluoroscopy times were analyzed by cohort overall and for diagnosis-specific subsets. The incidence of injury resulting from pedicle screw placement was 0.00% (0 of 1,870) with the manual method and 0.02% (1 of 4,542) with power (p = .5211). One screw, placed with power, was assumed to have caused a minor hemothorax, which was successfully treated with a chest tube. There were no neurologic or vascular injuries or other complications attributable to a pedicle screw in either group. Screws placed with power were removed or revised because of problems attributable to the pedicle screw one-sixth as often as those placed using manual tools: 2 of 1,410 (0.14%) versus 8 of 948 (0.84%) (p = .024). Fluoroscopy times in the power cohort were two-thirds as long as those in the manual cohort (p < .001). Operating times were not significantly different (p = .109). The use of power tools to create pedicle tracts and place pedicle screws was associated with shorter fluoroscopy times and a lower revision rate compared with using manual tools. Both techniques posed similar low risks of injury to the patient. Copyright © 2015 Scoliosis Research Society. Published by Elsevier Inc. All

  6. Odontoid screw placement using Isocentric 3-dimensional C-arm fluoroscopy.

    PubMed

    Summers, Lori E; Kouri, Joshua G; Yang, Mu; Patrick Jacob, R

    2008-02-01

    We describe the use of isocentric 3-dimensional fluoroscopy to place odontoid screws in 9 patients. We wanted to show the benefits of using isocentric 3-dimensional fluroscopy in odontoid screw placement. Odontoid screw fixation for treatment of type II odontoid fractures has gained popularity since its introduction in the early 1980s. During the last several years, a multitude of new techniques have improved the ease of odontoid screw placement, including biplanar fluoroscopy, cannulated screw systems, and beveled bedside-fixed retractor systems. The use of isocentric C-arm fluoroscopy can improve the ease and facilitate placement of odontoid screws. Nine patients, ranging in ages from 30 to 89 years, presented with type II odontoid fractures. All fractures were either nondisplaced or minimally displaced (<4 mm) and occurred as a result of acute trauma. No patient had evidence of transverse atlantal ligament disruption. Isocentric 3-dimensional fluoroscopy, in conjunction with image-guided navigational software, was used to place 1 or 2 odontoid screws in each patient. Three-dimensional images were acquired intraoperatively, which were then reconstructed and uploaded to the navigational workstation. Screw trajectory was planned and performed with the use of tracked instruments. Successful screw placement, as judged by intraoperative computerized tomography, was attained in all 9 patients. Isocentric 3-dimensional fluoroscopy, in conjunction with an image-guided navigational software system, obviates the need for cumbersome biplanar fluoroscopy, allows for intraoperative image acquisition after surgical exposure, reduces intraoperative registration time, reduces both surgeon and patient radiation exposure, and allows immediate computerized tomographic imaging in the operating room to verify screw position.

  7. History of gluteal augmentation.

    PubMed

    de la Peña, J Abel; Rubio, Omar V; Cano, Jacobo P; Cedillo, Mariana C; Garcés, Miriam T

    2006-07-01

    The concept of female beauty has changed throughout time, but the form and size of the breasts and gluteal region have remained constant as symbols of maximum femininity. Sculptures and prints show us feminine figures that are voluminous and reflect human history's interest in fertility. The early years of gluteal augmentation saw few published reports that described the procedure technique, follow-up, or possible complications. But developments continued as surgeons began experimenting with different anatomical planes for implant placement. The most important goal in plastic surgery is meeting a patient's expectations. It is important for the surgeon to thoroughly explain to patients what can realistically be achieved with a procedure.

  8. Accuracy and complications of transpedicular C2 screw placement without the use of spinal navigation.

    PubMed

    Mueller, Christian-Andreas; Roesseler, Lukas; Podlogar, Martin; Kovacs, Attlila; Kristof, Rudolf Andreas

    2010-05-01

    The objective of the study was to describe the technique, accuracy of placement and complications of transpedicular C2 screw fixation without spinal navigation. Patients treated by C2 pedicle screw fixations were identified from the surgical log book of the department. Clinical data were extracted retrospectively from the patients' charts. Pedicle screw placement accuracy was assessed on postoperative CT scans according to Gertzbein and Robbins (GRGr). A total of 27 patients were included in the study. The mean age of the patients was 56 +/- 22.0 years; 51.9% of them were female. As much as 17 patients suffered from trauma, 5 of degenerative disease, 3 of inflammations and 2 of metastatic disease. A total of 47 C2 transpedicular screw fixations were performed. The canulated screws were inserted under visual control following the preparation of the superior surface of the isthmus and of the medial surface of the pedicles of the C2. Intraoperative fluoroscopy was additionally used. The postoperative CT findings showed in 55.3% GRGr 1, in 27.7% GRGr 2, in 10.6% GRGr 3, and in 6.3% GRGr 4 pedicle screw insertion accuracy. Screw insertions GRGr 5 were not observed. Screw malpositioning (i.e., GRGr 3 and 4) was significantly associated with thin (<5 mm) pedicle diameters and with surgery for C2 fractures. In the three patients with screw insertions GRGr 4, postoperative angiographies were performed to exclude vertebral artery affections. In one of these three cases, the screw caused a clinically asymptomatic vertebral artery compression. Hardware failures did not occur. In one patient, postoperative pneumonia resulted in the death of the patient. Careful patient selection and surgical technique is necessary to avoid vertebral artery injury in C2 pedicle screw fixation without spinal navigation. A slight opening of the vertebral artery canal (Gertzbein and Robbins grade < or =3) does not seem to put the artery at risk. However, the high rate of misplaced screws when

  9. Usability Engineering: Domain Analysis Activities for Augmented Reality Systems

    DTIC Science & Technology

    2002-01-01

    This paper discusses our usability engineering process for the Battlefield Augmented Reality System (BARS). Usability engineering is a structured...management principals and techniques, formal and semiformal evaluation techniques, and computerized tools. BARS is an outdoor augmented reality system...originally developed the process in the context of virtual reality applications, but in this work we are adapting the procedures to an augmented

  10. Developing a New Medical Augmented Reality System.

    DTIC Science & Technology

    1996-05-01

    Augmented reality is a technique for combining supplementary imagery such that it appears as part of the scene and can be used for guidance, training...and locational aids. In the medical domain, augmented reality can be used to combine medical imagery to the physician’s view of a patient to help...the physician establish a direct relation between the imagery and the patient. This project report will examine medical augmented reality systems for

  11. Augmentation cystoplasty in neurogenic bladder

    PubMed Central

    Kocjancic, Ervin; Demirdağ, Çetin

    2016-01-01

    The aim of this review is to update the indications, contraindications, technique, complications, and the tissue engineering approaches of augmentation cystoplasty (AC) in patients with neurogenic bladder. PubMed/MEDLINE was searched for the keywords "augmentation cystoplasty," "neurogenic bladder," and "bladder augmentation." Additional relevant literature was determined by examining the reference lists of articles identified through the search. The update review of of the indications, contraindications, technique, outcome, complications, and tissue engineering approaches of AC in patients with neurogenic bladder is presented. Although some important progress has been made in tissue engineering AC, conventional AC still has an important role in the surgical treatment of refractory neurogenic lower urinary tract dysfunction. PMID:27617312

  12. Helical screw expander evaluation project

    NASA Technical Reports Server (NTRS)

    Mckay, R.

    1982-01-01

    A one MW helical rotary screw expander power system for electric power generation from geothermal brine was evaluated. The technology explored in the testing is simple, potentially very efficient, and ideally suited to wellhead installations in moderate to high enthalpy, liquid dominated field. A functional one MW geothermal electric power plant that featured a helical screw expander was produced and then tested with a demonstrated average performance of approximately 45% machine efficiency over a wide range of test conditions in noncondensing, operation on two-phase geothermal fluids. The Project also produced a computer equipped data system, an instrumentation and control van, and a 1000 kW variable load bank, all integrated into a test array designed for operation at a variety of remote test sites. Data are presented for the Utah testing and for the noncondensing phases of the testing in Mexico. Test time logged was 437 hours during the Utah tests and 1101 hours during the Mexico tests.

  13. Helical screw expander evaluation project

    NASA Astrophysics Data System (ADS)

    McKay, R.

    1982-03-01

    A one MW helical rotary screw expander power system for electric power generation from geothermal brine was evaluated. The technology explored in the testing is simple, potentially very efficient, and ideally suited to wellhead installations in moderate to high enthalpy, liquid dominated field. A functional one MW geothermal electric power plant that featured a helical screw expander was produced and then tested with a demonstrated average performance of approximately 45% machine efficiency over a wide range of test conditions in noncondensing, operation on two-phase geothermal fluids. The Project also produced a computer equipped data system, an instrumentation and control van, and a 1000 kW variable load bank, all integrated into a test array designed for operation at a variety of remote test sites. Data are presented for the Utah testing and for the noncondensing phases of the testing in Mexico. Test time logged was 437 hours during the Utah tests and 1101 hours during the Mexico tests.

  14. Screw-fed pump system

    DOEpatents

    Sprouse, Kenneth M

    2014-11-25

    A pump system includes a pump that includes a first belt and a second belt that are spaced apart from each other to provide generally straight sides of a passage there between. There is an inlet at one end of the passage and an outlet at an opposite end of the passage, with a passage length that extends between the inlet and the outlet. The passage defines a gap distance in a width direction between the straight sides at the passage inlet. A hopper includes an interior space that terminates at a mouth at the passage inlet. At least one screw is located within the interior space of the hopper and includes a screw diameter in the width direction that is less than or equal to the gap distance.

  15. Risks to the Superior Gluteal Neurovascular Bundle During Iliosacral and Transsacral Screw Fixation: A Computed Tomogram Arteriography (CTA) Study.

    PubMed

    Collinge, Cory; Maslow, Jed

    2017-07-31

    Iliosacral (IS) and transsacral (TS) screws are popular techniques to repair complicated injuries to the pelvis. The anatomy of the superior gluteal neurovasculature (SG NV bundle) is well described as running along the posterior ilium, providing innervation and perfusion to important abductor muscles. The method of pelvis fixation least likely to injure the SG NV bundle is unknown. Twenty uninjured patients with a contrasted computed tomogram of the pelvis and lower extremities (CTA) were evaluated. Starting points for an S1 IS screw, and S1 and S2 TS screws were estimated on the "ghost" lateral CTA image for those pelvi with safe corridors (>9mm diameter). The distance from the projected screw to the SG artery was measured. A distance of <3.65mm (half of a 7.3mm screw's diameter) was considered likely for NV bundle injury. Of forty pelvi CTA's (single sides), 10 pelvi (25%) were determined to be inappropriate for a S1 TS screw. The average distances from the screw starting point and the artery were 25.3mm (±9.2) for S1 IS, 12.4mm (±9.0) for S1 TS, and 23.5mm (±10.7) for S2 TS screws, respectively. Ten S1 TS screws (25%) and no S1 IS or S2 TS screws were projected to have caused injury to the SG NV bundle (P<0.001). Inserting S1 IS and S2 TS screws put the SG NV anatomy at significantly less risk than S1 TS screws. This information may aid in choosing the "best" fixation option for patients with pelvic ring trauma requiring surgery. Therapeutic level III.

  16. Screw-retained crown restorations of single implants: A step-by-step clinical guide

    PubMed Central

    Assaf, Mohammad; Gharbyeh, Alaa’ Z. Abu

    2014-01-01

    This paper shows the clinical steps for preparing a screw-retained crown for the restoration of a single implant. Impression-taking using open-tray technique and delivery of the crown is presented in a step-by-step manner elucidated by detailed photographs. Furthermore, the advantages and disadvantages of screw-retained crowns are discussed in comparison with the cemented restorations. PMID:25512742

  17. Horizontal ridge expansion and implant placement using screws: a report of two cases

    PubMed Central

    Kim, Young-Kyun

    2014-01-01

    Implants are typically placed after performing ridge expansion by inserting screws of gradually increasing thickness and good clinical outcomes are often obtained. We placed 11 implants in 6 patients, and one implant failed during osseointegration but it was replaced immediately after removal and successful prosthetic treatments were completed. During these surgeries, buccal cortical plate complete fractures do not occur. Inserting screws for ridge expansion is a successful and predictable technique for implant placement in narrow alveolar bone. PMID:25368836

  18. Validity of computed tomography in predicting scaphoid screw prominence: a cadaveric study.

    PubMed

    Griffis, Clare E; Olsen, Cara; Nesti, Leon; Gould, C Frank; Frew, Michael; McKay, Patricia

    2017-04-01

    Studies of hardware protrusion into joint spaces following fracture fixation have been performed to address whether or not there is discrepancy between the actual and radiographic appearance of screw prominence. The purpose of our study was to prove that, with respect to the scaphoid, prominence as visualized on CT scan is real and not a result of metal artifact. Forty-two cadaveric wrists were separated into four allotted groups with 21 control specimens and 21 study specimens. All specimens were radiographically screened to exclude those with inherent carpal abnormalities. Acutrak® headless compression screws were placed into all specimens using an open dorsal approach. Cartilage was removed from screw insertion site at the convex surface of the scaphoid proximal pole. Control specimens had 0 mm screw head prominence. The studied specimens had 1, 2, and 3 mm head prominence measured with a digital caliper. Computed tomography, with direct sagittal acquisition and metal suppression technique, was then performed on all specimens following screw placement. Two staff radiologists blinded to the study groups interpreted the images. Results revealed that only one of 21 control specimens was interpreted as prominent. Comparatively, in the studied groups, 90% were accurately interpreted as prominent. CT provides an accurate assessment of scaphoid screw head prominence. When a screw appears prominent on CT scan, it is likely to be truly prominent without contribution from metallic artifact.

  19. Mechanical Comparison of Headless Screw Fixation and Locking Plate Fixation for Talar Neck Fractures.

    PubMed

    Karakasli, Ahmet; Hapa, Onur; Erduran, Mehmet; Dincer, Cemal; Cecen, Berivan; Havitcioglu, Hasan

    2015-01-01

    For talar neck fractures, open reduction and internal fixation have been thought to facilitate revascularization and prevent osteonecrosis. Newer screw systems allow for placement of cannulated headless screws, which provide compression by virtue of a variable pitch thread. The present study compared the biomechanical fixation strength of cannulated headless variable-pitch screw fixation and locking plate fixation. A reproducible talar neck fracture was created in 14 fresh cadaver talar necks. Talar head fixation was then performed using 2 cannulated headless variable-pitch 4-mm/5-mm diameter (4/5) screws (Acutrak; Acumed, Hillsboro, OR) and locking plate fixation. Headless variable-pitch screw fixation had lower failure displacement than did locking plate fixation. No statistically significant differences were found in failure stiffness, yield stiffness (p = .655), yield load (p = .142), or ultimate load between the 2 fixation techniques. Cannulated headless variable-pitch screw fixation resulted in better failure displacement than locking plate fixation in a cadaveric talus model and could be considered a viable option for talus fracture fixation. Headless, fully threaded, variable-pitch screw fixation has inherent advantages compared with locking plate fixation, because it might cause less damage to the articular surface and can compress the fracture for improved reduction. Additionally, plate fixation can increase the risk of avascular necrosis owing to the wider incision and dissection of soft tissues.

  20. The effect of screw insertion torque on tendons fixed with spiked washers.

    PubMed

    Beynnon, B D; Meriam, C M; Ryder, S H; Fleming, B C; Johnson, R J

    1998-01-01

    The long-term success of a hamstring tendon graft depends not only on the type of device that is used for fixation but also on the mechanical interlocking of the soft tissue between the fixation device and bone. The purpose of this study was to evaluate the effect of screw insertion torque on the structural properties of soft tissue fixed to bone with a spiked metal washer. Two bovine tendons, one similar in size to a human semitendinosus tendon and the other similar in size to a human gracilis tendon, were secured to a bovine femur using a figure-of-8 technique with screws and metal spiked washers. A single load to failure was applied at 25 mm/sec. A significant positive linear correlation was observed between fixation screw insertion torque magnitude and the ultimate failure load value. An increase in the fixation screw insertion torque produced an increase in the ultimate failure load value. Similarly, there was a significant positive linear correlation between fixation screw insertion torque magnitude and the average maximum linear load value. No relationship was detected between screw insertion torque magnitude and the linear stiffness values of the tendon-fixation construct, indicating that a reproducible model was used. This study demonstrates that screw insertion torque is an important variable that controls the initial strength of soft tissue fixation to bone.