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Sample records for iliac screw fixation

  1. A 10-year follow-up of transpedicular screw fixation and intervertebral autogenous posterior iliac crest bone graft or intervertebral B-Twin system in failed back surgery syndrome

    PubMed Central

    Cincu, Rafael; Lorente, Francisco de Asis; Gomez, Joaquin; Eiras, Jose; Agrawal, Amit

    2015-01-01

    Background: The spine surgeons have been combining anterior and posterolateral fusion (circumferential fusion) as the final solution to treat spinal disorders and many have been using it to treat failed back surgery syndrome (FBSS). In present study, we analyzed and compared the clinical and radiological outcomes in patients with transpedicular screw fixation and intervertebral autogenous posterior iliac crest bone graft or in patients with transpedicular screw fixation and intervertebral B-Twin system for FBSS with a follow-up period of 10 years after the surgery. Materials and Methods: This study was a retrospective case study performed on 55 patients with FBSS. Clinical and radiological changes were compared between the two groups of patients on the basis of improvement of back pain, radicular pain, and work capacity. Outcome was measured in terms of Oswestry Low Back Pain Disability Index, and the changes in pain and function were documented every year from before surgery until 2012. We analyzed the evolution of 55 cases of FBSS those underwent segmental circumferential posterior fusions from June 2001 to February 2003, operated by a single surgeon and followed up during 10 years until February 2012. The patients were divided into 2 groups: In 25 patients, posterolateral fusions with Legacy™ (Medtronic, Inc. NYSE: MDT) screws and intersomatic autogenous posterior iliac crest bone graft was performed, and, in 30 patients, posterolateral fusions with the same screws and intersomatic fusion B-Twin (Biomet Spain Orthopaedics, S.L.) system was performed. In all cases, we used posterior lumbar interbody fusion (PLIF)/transforaminal lumbar interbody fusion (TLIF) approach for intervertebral graft, and the artrodesis was supplemented at intertransverse level with Autologus Growth Factor (AGF-MBA INCORPORADO, S.A.). The outcome was measured in terms of Oswestry Low Back Pain Disability Index, and the changes in pain and function were documented every year and compared from before surgery to the final follow-up visit. Preoperative and postoperative scores were available for all patients. Results: The average age of these patients was comparable in both groups (mean age 42.6 versus 50.2 years). The average follow-up period was 200.6 months in the first group (screws and intersomatic bone) and 184.4 months in the second group (screws and B-Twin). In the autologus bone graft group, the CT scan and Rx study revealed loss of height of intervertebral space between 25% and 45% of 24 h postoperative height of intervertebral operated disc, and the patients continued to lose the height until 20 months after the surgery. In the B Twin group, the CT scan and Rx study revealed a loss of height of the intervertebral level of 8-12% over a period of 9 months follow-up, followed by stability. A total of 31 patients (55%) had improved Oswestry Low Back Pain Disability Index >40% of the total possible points, although this did not reflect in PSI or return to work rate. Conclusions: The patients with rigid fixation do well in terms of correction of lumbar lordosis, but they do not do well in terms of recurrence of pain. Furthermore, they need some kind of intervention to control pain after the first year after surgery. In patients in whom bone graft is used, although they do not maintain and sustain the lumbar lordosis in the long term, they have less recurrence of pain with less chances of intervention for pain control. PMID:25972934

  2. 21 CFR 872.4880 - Intraosseous fixation screw or wire.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Intraosseous fixation screw or wire. 872.4880... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Surgical Devices § 872.4880 Intraosseous fixation screw or wire. (a) Identification. An intraosseous fixation screw or wire is a metal device intended to be...

  3. 21 CFR 872.4880 - Intraosseous fixation screw or wire.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Intraosseous fixation screw or wire. 872.4880... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Surgical Devices § 872.4880 Intraosseous fixation screw or wire. (a) Identification. An intraosseous fixation screw or wire is a metal device intended to be...

  4. Lumbosacral fixation using sacroiliac buttress screws: a modification to the Jackson technique with intrasacral rods

    PubMed Central

    2014-01-01

    Background The use of intrasacral rods has been previously reported for posterior lumbosacral fixation. However, problems associated with this technique include poor stability of the rod in the sacrum, difficulty in contouring the rod to fit the lateral sacral mass, and the complicated assembly procedure for the rod and pedicle screws in the thoracolumbar segments after insertion of the rod into the sacrum. Methods We used a screw with a polyaxial head instead of an intrasacral rod, which was inserted into the lateral sacral mass and assembled to the rod connected cephalad to pedicle screws. The dorsal side of the screw was stabilized by the sacral subchondral bone at the sacroiliac joint with iliac buttress coverage, and the tip of the screw was anchored by the sacral cortex. Results Three different cases were used to illustrate lumbosacral fixation using intrasacral screws as an anchor for the spinal instrumentation. Effective resistance of flexural bending moment and fusion were achieved in these patients at the lumbosacral level. Conclusions An intrasacral screw can be stabilized by subchondral bone with iliac buttress coverage at the dorsal and ventral sacral cortex. Posterior spinal fusion with this screw technique enables easier assembly of the instrumentation and presents better stabilization than that provided by the previously reported intrasacral rod technique for correction and fusion of thoracolumbar kyphoscoliosis. PMID:25050132

  5. Posterior Spinal Reconstruction with Pedicle Screws, Multiple Iliac Screws and Wisconsin Spinal Wires in a Patient with Neurofibromatosis Scoliosis: A Case Report

    PubMed Central

    Kim, Woong-Beom; Park, Young-Seop; Park, Jong-Hwa

    2015-01-01

    A 54-year-old female with neurofibromatosis type 1 presented with progressing truncal shift owing to spinal deformity. On plain radiograph, the Cobb angle was 54 degree in coronal plane. Radiological examinations showed severe dystrophic change with dysplastic pedicles, bony scalloping, neural foraminal widening from dural ectasia. The patient underwent deformity correction and reconstruction surgery from the T9 to the pelvis using multiple iliac screws and Wisconsin interspinous segmental instrumentation by wiring due to maximize fixation points. The postoperative course was uneventful. One-year follow-up radiographs showed a successful curve correction with solid fusion. We report a case of pedicle dysplasia and dystrophic change treated by posterior segmental spinal instrumentation and fusion with help of multiple iliac screws and modified Wisconsin interspinous segmental wiring. PMID:26512279

  6. Axial loading cross screw fixation for the Austin bunionectomy.

    PubMed

    Rigby, Ryan B; Fallat, Lawrence M; Kish, John P

    2011-01-01

    The Austin procedure has become a common method of osteotomy for the correction of hallux abductovalgus when indicated. The V-type configuration is intrinsically stable but not without complications. One complication encountered is rotation and/or displacement of the capital fragment. We present the use of an axial loading screw in conjunction with a dorsally placed compression screw. The benefit to this technique lies in the orientation of the axial loading screw, because it is directed to resist the ground reactive forces while also providing a second point of fixation in a crossing screw design. In a head-to-head biomechanical comparison, we tested single dorsal screw fixation versus double screw fixation, including both the dorsal and the axial loading screws in 10 metatarsal Sawbones(®) (Pacific Research Laboratories Inc, Vashon, WA). Five metatarsals received single dorsal screw fixation and five received the dorsal screw and the additional axial loading screw. The metatarsals were analyzed on an Instron compression device for comparison; 100% of the single screw fixation osteotomies failed with compression at an average peak load of 205 N. Four of five axial loading double screw fixation osteotomies did not fail. This finding suggests that the addition of an axial loading screw providing cross screw orientation significantly increases the stability of the Austin osteotomy, ultimately decreasing the likelihood of displacement encountered in the surgical repair of hallux abductovalgus. PMID:21621434

  7. Strength comparison of allogenic bone screws, bioabsorbable screws, and stainless steel screw fixation.

    PubMed

    Rano, James A; Savoy-Moore, Ruth T; Fallat, Lawrence M

    2002-01-01

    Allogenic bone screws are new to the fixation market and have yet to be tested against current fixation materials. An in vitro comparison of the same sizes of stainless steel, bioabsorbable, and allogenic bone screws was undertaken to assess screw resistance to the forces of bending, pullout, and shear. Using aluminum plates to support the screws, forces up to 1000 Newtons were applied to six to eight samples of each type of screw. During each test, stainless steel screws withstood the maximum force that could be exerted by the testing apparatus without failing (bending, 113.9 +/- 11.8 N mean +/- SE; pullout 999.1 +/- 33.7 N; and shear, 997.5 +/- 108.8 N). In each test, compared to bioabsorbable screws, allogenic bone screws failed faster (pullout, allogenic: 12.4 +/- 1.1 seconds vs. bioabsorbable, 120.6 +/- 13.8 seconds; p = .001; bending, allogenic: 53.4 +/- 4.8 seconds vs. bioabsorbable, 201.9 +/- 11.1 seconds; p = .001; shear, allogenic 13.5 +/- 1.4 seconds vs. bioabsorbable, 43.8 +/- 0.9 seconds; p = .001) under equivalent (pullout: bioabsorbable, 385.0 +/- 18.4 N vs. allogenic, 401.0 +/- 35.9 N; p = .001) or lower (bending, allogenic: 4.7 +/- 0.2 N vs. bioabsorbable, 11.0 +/- 0.9 N; p = .675; shear, allogenic: 312.1 +/- 15.5 N vs. bioabsorbable 680.9 +/- 8.5 N; p = .001) loads, and in a highly variable fashion. Overall, the bioabsorbable screws withstood the forces of bending, pullout, and shear better than the allogenic screws, and stainless steel screws outperformed both bioabsorbable and allogenic screws. Despite these results, allogenic screws could still be useful in compliant patients who would benefit from their osteoconductive properties. PMID:11858609

  8. 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. PMID:18639433

  9. Late-Onset Screw Migration into Iliac Vessels 21 years after Hip Arthrodesis

    PubMed Central

    Hirai, Taishi; Inaba, Yutaka; Kobayashi, Naomi; Takakagawa, Shu; Yukizawa, Yohei; Ike, Hiroyuki; Saito, Tomoyuki

    2014-01-01

    Iatrogenic injuries to the vascular system are a rare but serious complication of hip surgery. We report a case of an 83-year-old man who presented with intrapelvic migration of a screw into the space between the external iliac artery and vein 21 years after hip arthrodesis. The patient was treated with laparotomy, and the damaged artery was excised and sutured. This is the first case of a late vascular complication secondary to screw migration after hip arthrodesis. PMID:25336996

  10. Screw Versus Plate Fixation for Chevron Osteotomy: A Retrospective Study.

    PubMed

    Andrews, Boyd J; Fallat, Lawrence M; Kish, John P

    2016-01-01

    The chevron osteotomy is a popular procedure used for the correction of moderate hallux abducto valgus deformity. Fixation is typically accomplished with Kirschner wires or bone screws; however, in cystic or osteoporotic bone, these could be inadequate, resulting in displacement of the capital fragment. We propose using a locking plate and interfragmental screw for fixation of the chevron osteotomy that could reduce the healing time and decrease the incidence of displacement. We performed a retrospective cohort study for chevron osteotomies on 75 feet (73 patients). The control groups underwent fixation with 1 screw in 30 feet (40%) and 2 screws in 30 feet (40%). A total of 15 feet (20%) were included in the locking plate and interfragmental screw group. The patients were followed up until bone healing was achieved at a median of 7 (range 6 to 14) weeks. Our hypothesis was that those treated with the locking plate and interfragmental screw would have a faster healing time and fewer incidents of capital fragment displacement compared with the 1- or 2-screw groups. The corresponding mean intervals to healing for the 1-screw group was 7.71 ± 1.28 (range 6 to 10) weeks, for the 2-screw group was 7.27 ± 1.57 (range 6 to 14) weeks, and for the locking plate and interfragmental screw group was 7.01 ± 1.00 (range 6 to 9) weeks. One case of capital fragment displacement occurred in the single screw group and one in the 2-screw group. No displacement occurred in the locking plate and interfragmental screw group. Neither finding was statistically significant. However, we believe the locking plate and interfragmental screw could be a viable option in patients with osteoporotic and cystic bone changes for correction of hallux abducto valgus. PMID:26277241

  11. Intra-operative screw trimming in direct screw fixation of the odontoid process fracture--technical note.

    PubMed

    Hasegawa, T; Yamano, K; Hamada, Y; Miyamori, T

    1992-01-01

    For a satisfactory direct screw fixation of fractures of the odontoid process it is necessary to use a screw of the proper total length and thread length, but such an optimal ready-made screw is not always available. The authors describe a technique of intra-operative screw trimming using a high-speed diamond drill. This adjustment is easily and quickly performed. It enables the screw to act as a compression screw, which facilitates fusion of the fractured surfaces. PMID:1595397

  12. Mechanical comparison of cortical screw fixation versus locking plate fixation in first metatarsal base osteotomy.

    PubMed

    Smith, Kevin; Lidtke, Roy H; Oliver, Noah G; Maker, Jared M

    2014-01-01

    The oblique closing base wedge osteotomy has been used for surgical treatment of moderate to severe hallux valgus deformities with an intermetatarsal angle typically greater than 15°. Several postoperative complications have been identified that relate to failure of the fixation construct used to fixate the osteotomy, especially when that construct has been subjected to a vertical load. We performed a mechanical analysis comparing 2 constructs used to fixate oblique osteotomies of the first metatarsal using composite first metatarsals. An oblique base osteotomy was uniformly performed on 40 composite first metatarsals. Of the 40 specimens, 20 were fixated with a locking plate construct and 18 with a cortical screw construct, consisting of an anchor and compression screw (2 specimens from the latter group were excluded because of hinge fracture). Each specimen was loaded in a materials testing machine to measure the maximum load at construct failure when a vertical force was applied to the plantar aspect of the metatarsal head. The mean load to failure for the locking plate construct was significantly greater than the cortical screw construct (190.0 ± 70 N versus 110.3 ± 20.3 N, p < .001). Our study results have demonstrated that the locking plate construct was able to withstand a significantly greater vertical load before failure than was the 2-cortical screw construct in oblique osteotomies performed at the base of composite first metatarsals. PMID:24954919

  13. 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. PMID:24907127

  14. Screw fixation of dermal regeneration template for scalp reconstruction.

    PubMed

    Orseck, Michael J; Trujillo, Manny G; Ritter, Edmond F

    2012-05-01

    Despite many advances in reconstructive techniques, the full-thickness scalp defect remains a difficult problem for the reconstructive surgeon. Patient and disease-specific factors occasionally make reconstruction with a dermal regeneration template (DRT) an attractive option when other methods are less advised. Although the applicability of dermal regeneration templates has been well elucidated, the method of DRT immobilization has not been standardized. Given the difficulty of adherence and subsequent infiltration of host cells into the DRT from the underlying bone due to seroma, hematoma, or shearing forces, we propose a screw and bolster system for DRT immobilization. We present a series of 13 patients with full-thickness scalp loss who underwent reconstruction with DRT and a subsequent split-thickness skin graft. All 13 patients were treated with the screw-bolster method of DRT fixation before a vacuum-assisted closure dressing. The average surface area of the defect was 96 cm. The mean time interval between the application of DRT and skin graft was 28 days. At a mean of 9-month follow-up, all patients achieved a well-vascularized neodermis, and progressed to complete, stable wound healing following application of a split-thickness skin graft. We propose that a screw-bolster system of fixation is a safe and effective method of immobilizing DRT in full-thickness scalp defects. PMID:22531400

  15. Comparison of Pedicle Screw Loosening Mechanisms and the Effect on Fixation Strength.

    PubMed

    Mehmanparast, Hedayeh; Petit, Yvan; Mac-Thiong, Jean-Marc

    2015-12-01

    Screw loosening is a common complication in spinal fixation using pedicle screws which may lead to loss of correction and revision surgery. The mechanisms of pedicle screw loosening are not well understood. The purpose of this study was to compare the pedicle screw pullout force and stiffness subsequent or not to multidirectional cyclic bending load (toggling). Pedicle screws inserted into porcine lumbar vertebrae underwent toggling in craniocaudal (CC), mediolateral (ML) directions, and no toggling (NT) before pullout. This study suggests that toggling and in particular CC toggling should be included in biomechanical evaluation of pedicle screw fixation strength. PMID:26502116

  16. Evaluation of Occipitocervical Arthrodesis Rates with Screw-based Fixation and Osteoinductive Fusion Adjuncts.

    PubMed

    Stone, Jeremy G; Panczykowski, David M; Tempel, Zachary J; Tormenti, Matthew; Kanter, Adam S; Okonkwo, David O

    2015-09-01

    Occipitocervical (OC) instability may be associated with neurologic impairment and even death. There is a paucity of research on the rate of arthrodesis utilizing modern screw-based constructs coupled with adjuvant osteoinductive agents. We reviewed our experience with OC constructs and compared the fusion rate, functional outcome, and rate of adverse events between recombinant human bone morphogenetic protein (BMP)-2, autologous iliac crest bone graft (ICBG), a combination of BMP and ICBG, and local bone autograft alone. We performed a retrospective cohort analysis of all adult admissions for operative treatment of OC instability utilizing segmental screw-based constructs for OC arthrodesis between January 2003 and September 2012. Data concerning demographic characteristics, diagnostic and procedural details, radiographic pathology, and clinical course were abstracted from medical records. The primary end point was evidence of stable fixation and osseous union on either dynamic lateral radiographs or computed tomography (CT) imaging at most recent follow-up. Secondary end points included functional outcome as determined by Nurick scale and Neck disability index (NDI) at???1year postoperation, as well as perioperative morbidity and mortality at 30 days and 3 months. During the study period, 94 patients (mean age: 62?±?18 years) underwent OC fixation with segmental screw-based constructs. The four fusion adjunct cohorts analyzed included local autograft alone (32%), ICBG (41%), BMP (14%), or a combination of ICBG and BMP (14%). Notably, demineralized bone matrix was also used in 61% of cases overall, but its use did not differ significantly among the four cohorts (p?=?0.28). Median radiographic follow-up was 6 months postoperatively (range: 1.5-54 months). Clinical outcomes were assessed at a median postoperative follow-up of 45 months (range: 12-87 months). Overall, radiographic evidence of arthrodesis was present in 83% of patients assessed and was not significantly different between adjunct cohorts (local autograft 92%, ICBG 77%, BMP 88%, and combination of ICBG and BMP 83%; p?=?0.79). This finding persisted despite adjustment for age, pathology, number of levels instrumented, and attendant procedures. Importantly, neither the presence of arthrodesis nor fusion adjunct was significantly associated with functional outcome in both univariate and adjusted regression models. Additionally, perioperative adverse events occurred in 23% of cases and did not vary significantly in incidence or severity between fusion adjunct cohorts. We present a large series of patients treated for OC instability with rigid fixation utilizing modern segmental screw-based constructs. The use of adjuvant osteoinductive agents (BMP, ICBG, or a combination) produced equivalent rates of arthrodesis, functional outcome, and adverse events compared with use of local autograft alone. PMID:26171793

  17. Four quadrant parallel peripheral screw fixation for displaced femoral neck fractures in elderly patients

    PubMed Central

    Satish, Bhava RJ; Ranganadham, Atmakuri V; Ramalingam, Karruppasamy; Tripathy, Sujit Kumar

    2013-01-01

    Background: The treatment options for displaced femoral neck fracture in elderly are screw fixation, hemiarthroplasty and total hip arthroplasty based primarily on age of the patient. The issues in screw fixation are ideal patient selection, optimal number of screws, optimal screw configuration and positioning inside the head and neck of femur. The problems of screw fixation may be loss of fixation, joint penetration, avascular necrosis of femoral head, nonunion, prolonged rehabilitation period and the need for second surgery in failed cases. We hereby present results of a modified screw fixation technique in femoral neck fractures in patients ?50 years of age. Materials and Methods: Patients ?50 years of age (range 50-73 years) who sustained displaced femoral neck fracture and fulfilled the inclusion criteria were enrolled in this prospective study. They were treated with closed reduction under image intensifier control and cannulated cancellous screw fixation. Accurate anatomical reduction was not aimed and a cross sectional contact area of >75% without varus was accepted as good reduction. Four screws were positioned in four quadrants of femoral head and neck, as parallel and as peripheral as possible. Radiological and functional results were evaluated periodically. Sixty four patients who could complete a minimum followup of two years were analyzed. Results: Radiologically, all fractures healed after mean duration of 10 weeks (range 8-12 weeks). There was no avascular necrosis. Nonanatomical healing was observed in 45 cases (70%). All patients except one had excellent functional outcome and could do cross-legged sitting and squatting. Chondrolysis with progressive head resorption was seen in one case, which was converted to total hip arthroplasty. Conclusion: Closed reduction and cannulated cancellous screw fixation gives satisfactory functional results in large group of elderly patients. The four quadrant parallel peripheral (FQPP) screw fixation technique gives good stability, allows controlled collapse, avoids fixation failure and achieves predictable bone healing in displaced femoral neck fracture in patients ?50 years of age. PMID:23682180

  18. Pedicle Screw Fixation Study in Immature Porcine Spines to Improve Pullout Resistance during Animal Testing

    PubMed Central

    Le Cann, Sophie; Cachon, Thibaut; Viguier, Eric; Miladi, Lotfi; Odent, Thierry; Rossi, Jean-Marie; Chabrand, Patrick

    2015-01-01

    The porcine model is frequently used during development and validation of new spinal devices, because of its likeness to the human spine. These spinal devices are frequently composed of pedicle screws with a reputation for stable fixation but which can suffer pullouts during preclinical implantation on young animals, leading to high morbidity. With a view to identifying the best choices to optimize pedicle screw fixation in the porcine model, this study evaluates ex vivo the impact of weight (age) of the animal, the level of the vertebrae (lumbar or thoracic) and the type of screw anchorage (mono- or bi-cortical) on pedicle screw pullouts. Among the 80 pig vertebrae (90- and 140-day-old) tested in this study, the average screw pullout forces ranged between 419.9N and 1341.2N. In addition, statistical differences were found between test groups, pointing out the influence of the three parameters stated above. We found that the the more caudally the screws are positioned (lumbar level), the greater their pullout resistance is, moreover, screw stability increases with the age, and finally, the screws implanted with a mono-cortical anchorage sustained lower pullout forces than those implanted with a bi-cortical anchorage. We conclude that the best anchorage can be obtained with older animals, using a lumbar fixation and long screws traversing the vertebra and inducing bi-cortical anchorage. In very young animals, pedicle screw fixations need to be bi-cortical and more numerous to prevent pullout. PMID:26451947

  19. 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

    OBJECT 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. METHODS 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. RESULTS Both patients' symptoms improved after the operation, and there was no evidence of cage subsidence or screw loosening at the 4-month follow-up. CONCLUSIONS The indirect technique of bone cement augmentation via the disc space for percutaneous screw fixation could be an easy, safe, and economical method. PMID:26360145

  20. Endosseous Fixation Device for Lapidus Arthrodesis: Technique, Early Experience, and Comparison With Crossed Screw Fixation.

    PubMed

    Zelent, Marek E; Neese, David J; Peterson, Paul H

    2015-01-01

    First metatarsal cuneiform joint arthrodesis has been commonly used since the early 1900s for definitive treatment of a variety of conditions involving the medial column of the foot. Early applications of this procedure resulted in a relatively high rate of complications, including malunion and nonunion. We retrospectively examined a novel method of fixation involving an endosseous implant with a nonporous, rough exterior surface and compared it with the traditional crossed screw fixation, considered the standard of care for the procedure. Twenty-one feet in 19 patients served as the control group with crossed screws, and 18 feet in 17 patients served as the trial group using the study device. Null hypothesis testing was used to compare the outcomes parameters between the comparative groups. Postoperatively, the patients were allowed to walk in a prefabricated, removable, below-the-knee cast boot at a mean of 48.3 ± 8.2 days in the control group and 24.4 ± 9.7 days in the trial group. These differences were highly significant (p < .0001). Postoperatively, the patients were allowed to walk in a stiff-soled shoe at a mean of 65.2 ± 8.4 days in the control group and 49.7 ± 19.2 days in the trial group. These differences were also statistically significant (p = .0020). The patients in the control group required revision surgery in 7 of 21 procedures (33%), with 2 patients developing nonunion (9.5%). Only 1 patient in the trial group required revision surgery (5.8%), and no patient developed nonunion. From these results, we believe that the endosseous trial implant is a reliable option for fixation of the first metatarsal cuneiform arthrodesis procedure and might allow for earlier weightbearing with fewer postoperative complications. PMID:26364702

  1. Surgical Strategies to Improve Fixation in the Osteoporotic Spine: The Effects of Tapping, Cement Augmentation, and Screw Trajectory

    PubMed Central

    Kuhns, Craig A.; Reiter, Michael; Pfeiffer, Ferris; Choma, Theodore J.

    2013-01-01

    Study Design?Biomechanical study of pedicle screw fixation in osteoporotic bone. Objective?To investigate whether it is better to tap or not tap osteoporotic bone prior to placing a cement-augmented pedicle screw. Methods?Initially, we evaluated load to failure of screws placed in cancellous bone blocks with or without prior tapping as well as after varying the depths of tapping prior to screw insertion. Then we evaluated load to failure of screws placed in bone block models with a straight-ahead screw trajectory as well as with screws having a 23-degree cephalad trajectory (toward the end plate). These techniques were tested with nonaugmented (NA) screws as well as with bioactive cement (BioC) augmentation prior to screw insertion. Results?In the NA group, pretapping decreased fixation strength in a dose-dependent fashion. In the BioC group, the tapped screws had significantly greater loads to failure (p?screw orientation, the screws oriented at 23 degrees cephalad had a significantly higher failure force than their respective counterparts at 0 degrees (p?screw fixation is often inadequate in the osteoporotic spine, but this study suggests tapping prior to cement augmentation will substantially improve fixation when compared with not tapping. Angulating screws more cephalad also seems to enhance aging spine fixation. PMID:24494181

  2. Surgical strategies to improve fixation in the osteoporotic spine: the effects of tapping, cement augmentation, and screw trajectory.

    PubMed

    Kuhns, Craig A; Reiter, Michael; Pfeiffer, Ferris; Choma, Theodore J

    2014-02-01

    Study Design?Biomechanical study of pedicle screw fixation in osteoporotic bone. Objective?To investigate whether it is better to tap or not tap osteoporotic bone prior to placing a cement-augmented pedicle screw. Methods?Initially, we evaluated load to failure of screws placed in cancellous bone blocks with or without prior tapping as well as after varying the depths of tapping prior to screw insertion. Then we evaluated load to failure of screws placed in bone block models with a straight-ahead screw trajectory as well as with screws having a 23-degree cephalad trajectory (toward the end plate). These techniques were tested with nonaugmented (NA) screws as well as with bioactive cement (BioC) augmentation prior to screw insertion. Results?In the NA group, pretapping decreased fixation strength in a dose-dependent fashion. In the BioC group, the tapped screws had significantly greater loads to failure (p?screw orientation, the screws oriented at 23 degrees cephalad had a significantly higher failure force than their respective counterparts at 0 degrees (p?screw fixation is often inadequate in the osteoporotic spine, but this study suggests tapping prior to cement augmentation will substantially improve fixation when compared with not tapping. Angulating screws more cephalad also seems to enhance aging spine fixation. PMID:24494181

  3. Screw fixation of medial malleolar fractures: a cadaveric biomechanical study challenging the current AO philosophy.

    PubMed

    Parker, L; Garlick, N; McCarthy, I; Grechenig, S; Grechenig, W; Smitham, P

    2013-12-01

    The AO Foundation advocates the use of partially threaded lag screws in the fixation of fractures of the medial malleolus. However, their threads often bypass the radiodense physeal scar of the distal tibia, possibly failing to obtain more secure purchase and better compression of the fracture. We therefore hypothesised that the partially threaded screws commonly used to fix a medial malleolar fracture often provide suboptimal compression as a result of bypassing the physeal scar, and proposed that better compression of the fracture may be achieved with shorter partially threaded screws or fully threaded screws whose threads engage the physeal scar. We analysed compression at the fracture site in human cadaver medial malleoli treated with either 30 mm or 45 mm long partially threaded screws or 45 mm fully threaded screws. The median compression at the fracture site achieved with 30 mm partially threaded screws (0.95 kg/cm(2) (interquartile range (IQR) 0.8 to 1.2) and 45 mm fully threaded screws (1.0 kg/cm(2) (IQR 0.7 to 2.8)) was significantly higher than that achieved with 45 mm partially threaded screws (0.6 kg/cm(2) (IQR 0.2 to 0.9)) (p = 0.04 and p < 0.001, respectively). The fully threaded screws and the 30mm partially threaded screws were seen to engage the physeal scar under an image intensifier in each case. The results support the use of 30 mm partially threaded or 45 mm fully threaded screws that engage the physeal scar rather than longer partially threaded screws that do not. A 45 mm fully threaded screw may in practice offer additional benefit over 30 mm partially threaded screws in increasing the thread count in the denser paraphyseal region. PMID:24293597

  4. Neurocentral synchondrosis fracture in immature spines associated with pedicle screw type fixation devices.

    PubMed

    Sairyo, K; Scifert, J; Goel, V K; Grosland, N; Grobler, L J

    1998-04-01

    The purpose of this study is to clarify the weak point in immature lumbar vertebrae associated with pedicle screw instrumentation. Ten immature thoracic and lumbar vertebrae were collected from calf spines. After installation of 6- and 7-mm-diameter pedicle screws into the pedicles of each specimen, pullout force was applied to the screw using the uniaxial MTS system until failure. Tightening torque during installation was measured. From the load-displacement curve, failure load was calculated and failure site was confirmed by radiographs. Inner pedicle diameters were measured after the pullout test, and percent fills of the pedicle screw were calculated. Mean tightening torque was 1.4 or 2.1 (Nm), mean failure load was 852.5 or 1,015.0 (N), and mean percent fill was 81.4 or 93.5% for 6- or 7-mm screws, respectively. Tightening torque and percent fill in 7-mm screws were significantly (p < 0.01) greater than that in 6-mm screws; however, failure load showed no significant difference (p = 0.10) between the two screw groups. Failure by screw pullout occurred at the screw-bone interface or through the neurocentral synchondrosis (NS). NS fractures were observed in 20% of 6-mm screws, 60% of 7-mm screws, and 40% overall, whereas interface failures occurred in 80% of 6-mm screws, 40% of 7-mm screws, and 60% overall. In NS fracture group, tightening torque (p < 0.05) and percent fill (p < 0.01) were significantly greater than in the interface failure group. The results led us to conclude that the mechanism of the NS fracture is unclear. However, NS fracture could be one of the conceivable complications associated with pedicle screw fixation in the immature spine. PMID:9588471

  5. Clinical Use of 3D Printing Guide Plate in Posterior Lumbar Pedicle Screw Fixation

    PubMed Central

    Chen, Hongliang; Wu, Dongying; Yang, Huilin; Guo, Kaijin

    2015-01-01

    Background This study aimed to evaluate the clinical efficacy of use of a 3D printing guide plate in posterior lumbar pedicle screw fixation. Material/Methods We enrolled 43 patients receiving posterior lumbar pedicle screw fixation. The experimental group underwent 3D printing guide plate-assisted posterior lumbar pedicle screw fixation, while the control group underwent traditional x-ray-assisted posterior lumbar pedicle screw fixation. After surgery, CT scanning was done to evaluate the accuracy of screw placement according to the Richter standard. Results All patients were followed up for 1 month. The mean time of placement for each screw and the amount of hemorrhage was 4.9±2.1 min and 8.0±11.1 mL in the experimental group while 6.5±2.2 min and 59.9±13.0 mL in the control group, respectively, with significant differences (p<0.05). The fluoroscopy times of each screw placement was 0.5±0.4 in the experimental group, which was significantly lower than that in the control group 1.2±0.7 (p<0.05). The excellent and good screw placement rate was 100% in the experimental group and 98.4% in the control group, without any statistical difference (P>0.05). No obvious complications were reported in either group. Conclusions Compared with the traditional treatment methods, the intra-operative application of 3D printing guide plate can shorten the operation time and reduce the amount of hemorrhage. It can also reduce the fluoroscopy times compared with the traditional fluoroscopy, which cannot improve the accuracy rate of screw placement. PMID:26681388

  6. Clinical Use of 3D Printing Guide Plate in Posterior Lumbar Pedicle Screw Fixation.

    PubMed

    Chen, Hongliang; Wu, Dongying; Yang, Huilin; Guo, Kaijin

    2015-01-01

    BACKGROUND This study aimed to evaluate the clinical efficacy of use of a 3D printing guide plate in posterior lumbar pedicle screw fixation. MATERIAL AND METHODS We enrolled 43 patients receiving posterior lumbar pedicle screw fixation. The experimental group underwent 3D printing guide plate-assisted posterior lumbar pedicle screw fixation, while the control group underwent traditional x-ray-assisted posterior lumbar pedicle screw fixation. After surgery, CT scanning was done to evaluate the accuracy of screw placement according to the Richter standard. RESULTS All patients were followed up for 1 month. The mean time of placement for each screw and the amount of hemorrhage was 4.9±2.1 min and 8.0±11.1 mL in the experimental group while 6.5±2.2 min and 59.9±13.0 mL in the control group, respectively, with significant differences (p<0.05). The fluoroscopy times of each screw placement was 0.5±0.4 in the experimental group, which was significantly lower than that in the control group 1.2±0.7 (p<0.05). The excellent and good screw placement rate was 100% in the experimental group and 98.4% in the control group, without any statistical difference (P>0.05). No obvious complications were reported in either group. CONCLUSIONS Compared with the traditional treatment methods, the intra-operative application of 3D printing guide plate can shorten the operation time and reduce the amount of hemorrhage. It can also reduce the fluoroscopy times compared with the traditional fluoroscopy, which cannot improve the accuracy rate of screw placement. PMID:26681388

  7. Cortical and Standard Trajectory Pedicle Screw Fixation Techniques in Stabilizing Multisegment Lumbar Spine with Low Grade Spondylolisthesis

    PubMed Central

    ?nceo?lu, Serkan

    2015-01-01

    Background Cortical screw (CS) fixation has been recently proposed as an alternative to the standard pedicle screw (PS) fixation technique. Biomechanical studies involving individual screw pullout and single level motion segment stabilization showed comparable performance of both techniques. However, whether this new fixation technique can be applied to the stabilization of multilevel lumbar segments with significant destabilization has been unclear. Purpose To compare stability of CS fixation to the traditional PS fixation in an unstable 3 level spondylolisthesis model. Study Design This is a biomechanical study comparing cortical trajectory pedicle screw fixation to traditional trajectory pedicle screw fixation in an unstable cadaveric model using nondestructive flexibility test. Methods Eight fresh frozen cadaveric lumbar spines (T12- S1) were obtained. After intact baseline testing, a 3-level lowgrade spondylolisthesis was simulated at the L1-4. Each specimen was instrumented with the PS and CS fixation systems. Standard nondestructive flexibility test was performed. Range of motion at each level was compared between the constructs during flexion-extension, lateral bending, and axial rotation. Results The destabilization model significantly increased the ROM in all planes (P<0.05). Both fixation techniques provided significant reduction in the ROM (P<0.05). There was no significant difference in ROM between the PS and CS groups in any of planes (P>0.05). Conclusions Cortical trajectory pedicle screw fixation provided stabilization to multilevel lumbar segment with low-grade spondylolisthesis comparable to the standard trajectory pedicle screw construct. PMID:26484009

  8. Fully Threaded Versus Partially Threaded Screws: Determining Shear in Cancellous Bone Fixation.

    PubMed

    Downey, Michael W; Kosmopoulos, Victor; Carpenter, Brian B

    2015-01-01

    Many researchers have studied and compared various forms of intraosseous fixation. No studies have examined the effects of shear through stiffness and failure strength of a fully threaded versus a partially threaded screw. Our hypothesis was that the fully threaded lag screw technique would provide greater shear strength and resistance. Thirty-six synthetic sawbone blocks were used to test screw fixation. In group 1 (n = 9), 2 blocks were fixed together using a fully threaded 4.0-mm stainless steel cancellous bone screw and the lag technique. In group 2 (n = 8), 2 blocks were fixed together using the standard manufacturer-recommended method for inserting 4.0-mm partially threaded stainless steel cancellous bone screws. The constructs were then mechanically tested. Shear was applied by compressing each construct at an axial displacement rate of 0.5 mm/s until failure. The fully threaded screw had a significantly greater (p = .026) initial stiffness (106.4 ± 15.8 N/mm) than the partially threaded screw (80.1 ± 27.5 N/mm). The yield load and displacement for the fully threaded group (429.4 ± 11.7 N and 7.2 ± 0.35 mm) were 64% and 67% greater than those for the partially threaded screw group (261.4 ± 26.1 N and 4.3 ± 1.03 mm), respectively. The results of the present study have demonstrated the importance of a full-thread construct to prevent shear and to decrease strain at the fracture. The confirmation of our hypothesis questions the future need and use of partially threaded screws for cancellous bone fixation. PMID:26210079

  9. Comparison of migration behavior between single and dual lag screw implants for intertrochanteric fracture fixation

    PubMed Central

    Kouvidis, George K; Sommers, Mark B; Giannoudis, Peter V; Katonis, Pavlos G; Bottlang, Michael

    2009-01-01

    Background Lag screw cut-out failure following fixation of unstable intertrochanteric fractures in osteoporotic bone remains an unsolved challenge. This study tested if resistance to cut-out failure can be improved by using a dual lag screw implant in place of a single lag screw implant. Migration behavior and cut-out resistance of a single and a dual lag screw implant were comparatively evaluated in surrogate specimens using an established laboratory model of hip screw cut-out failure. Methods Five dual lag screw implants (Endovis, Citieffe) and five single lag screw implants (DHS, Synthes) were tested in the Hip Implant Performance Simulator (HIPS) of the Legacy Biomechanics Laboratory. This model simulated osteoporotic bone, an unstable fracture, and biaxial rocking motion representative of hip loading during normal gait. All constructs were loaded up to 20,000 cycles of 1.45 kN peak magnitude under biaxial rocking motion. The migration kinematics was continuously monitored with 6-degrees of freedom motion tracking system and the number of cycles to implant cut-out was recorded. Results The dual lag screw implant exhibited significantly less migration and sustained more loading cycles in comparison to the DHS single lag screw. All DHS constructs failed before 20,000 cycles, on average at 6,638 ± 2,837 cycles either by cut-out or permanent screw bending. At failure, DHS constructs exhibited 10.8 ± 2.3° varus collapse and 15.5 ± 9.5° rotation around the lag screw axis. Four out of five dual screws constructs sustained 20,000 loading cycles. One dual screw specimens sustained cut-out by medial migration of the distal screw after 10,054 cycles. At test end, varus collapse and neck rotation in dual screws implants advanced to 3.7 ± 1.7° and 1.6 ± 1.0°, respectively. Conclusion The single and double lag screw implants demonstrated a significantly different migration resistance in surrogate specimens under gait loading simulation with the HIPS model. In this model, the double screw construct provided significantly greater resistance against varus collapse and neck rotation in comparison to a standard DHS lag screw implant. PMID:19450283

  10. Percutaneous pedicle screw fixation for an unstable thoracic spine fracture after a traumatic degloving injury.

    PubMed

    Celano, Emma Christine; Baum, Griffin R; Gelbard, Rondi B; Ahmad, Faiz U

    2015-01-01

    Unstable spinal fractures require urgent surgical intervention to relieve compression of the spinal cord, correct spinal deformity, stabilise the spine and prevent further neurological injury. We report the case of a young man with a thoracic chance fracture in the setting of a devastating degloving injury, whose fracture was stabilised using minimally invasive, percutaneous pedicle screw fixation. We discuss the advantages of using a minimally invasive technique for spinal fixation and its role in the treatment of complicated, multisystem trauma patients. PMID:26646146

  11. Biomechanical evaluation of four different posterior screw and rod fixation techniques for the treatment of the odontoid fractures

    PubMed Central

    Li, Lei; Liu, Wen-Fei; Jiang, Hong-Kun; Li, Yun-Peng

    2015-01-01

    Problems that screw cannot be inserted may occur in screw-rod fixation techniques such as Harms technique. We compared the biomechanical stability imparted to the C-2 vertebrae by four designed posterior screw and rod fixation techniques for the management of odontoid fractures. A three-dimensional finite element model of the odontoid fracture was established by subtracting several unit structures from the normal model from a healthy male volunteer. 4 different fixation techniques, shown as follows: ? C-1 lateral mass and C-2 pedicle screw fixation (Harms technique); ? C-1 lateral mass and unilateral C-2 pedicle screw fixation combined with ipsilateral laminar screw fixation; ? Unilateral C-1lateral mass combined with ipsilateral C-1 posterior arch, and C-2 pedicle screw fixation; and ? Unilateral C1 lateral mass screw connected with bilateral C2 pedicle screw fixation was performed on the odontoid fracture model. The model was validated for axial rotation, flexion, extension, lateral bending, and tension for 1.5 Nm. Changes in motion in flexion-extension, lateral bending, and axial rotation were calculated. The finite element model of the odontoid fracture was established in this paper. All of the four screw-rod techniques significantly decreased motion in flexion-extension, lateral bending, and axial rotation, as compared with the destabilized odontoid fracture complex (P<0.05). There was no statistically significant difference in stability among the four screw techniques. We concluded that the first three fixation techniques are recommended to be used as surgical intervention for odontoid fracture, while the last can be used as supplementary for the former three methods. PMID:26309508

  12. A video guided solution for screw insertion in orthopedic plate fixation

    NASA Astrophysics Data System (ADS)

    Magaraggia, J.; Kleinszig, G.; Graumann, R.; Angelopoulou, E.; Hornegger, J.

    2013-03-01

    In orthopedic and trauma surgery, metallic plates are used for reduction and fixation of bone fractures. In clinical practice, the intra-operative planning for screw fixation is usually based on fluoroscopic images. Screw fixation is then performed on a free-hand basis. As such, multiple attempts may be required in order to achieve an optimal positioning of the fixing screws. To help the physician insert the screws in accordance to the planned position, we propose a method for screw insertion guidance. Our approach uses a small video camera, rigidly placed on the drill, and a set of small markers that are rigidly fixed on a variable angle drill sleeve. In order to investigate the achievable accuracy of our setup, we simulate the estimation of the drill bit position under two different marker arrangements, planar and 3D, and different noise levels. Furthermore, we motivate our choices for marker design and position given the limited space available for marker positioning, the requirement for accurate position estimation of the drill bit and the illumination changes that could affect the surgical site. We also describe our proposed marker detection and tracking pipeline. Our simulation results let us conclude that we can achieve an accuracy of 1° and 1mm in the estimation of angular orientation and tip position of the drill bit respectively, provided that we have accurate marker detection.

  13. Chitosan-coated Stainless Steel Screws for Fixation in Contaminated Fractures

    PubMed Central

    Greene, Alex H.; Bumgardner, Joel D.; Yang, Yunzhi; Moseley, Jon

    2008-01-01

    Stainless steel screws and other internal fixation devices are used routinely to stabilize bacteria-contaminated bone fractures from multiple injury mechanisms. In this preliminary study, we hypothesize that a chitosan coating either unloaded or loaded with an antibiotic, gentamicin, could lessen or prevent these devices from becoming an initial nidus for infection. The questions investigated for this hypothesis were: (1) how much of the sterilized coating remains on the screw with simulated functional use; (2) is the unloaded or loaded chitosan coating bacteriostatic and biocompatible; and (3) what amount and rate does an antibiotic elute from the coating? In this study, the gentamicin eluted from the coating at a detectable level during 72 to 96 hours. The coating was retained at the 90% level in simulated bone screw fixation and the unloaded and loaded chitosan coatings had encouraging in vitro biocompatibility with fibroblasts and stem cells and were bacteriostatic against at least one strain of Staphylococcus aureus. The use of an antibiotic-loaded chitosan coating on stainless steel bone screws and internal fixation devices in contaminated bone fracture fixation may be considered after optimization of antibiotic loading and elution and more expanded in vitro and in vivo investigations with other organisms and antibiotics. PMID:18443893

  14. Intraoperative Vertebral Artery Angiography to Guide C1-2 Transarticular Screw Fixation in a Patient with Athetoid Cerebral Palsy

    PubMed Central

    Chung, Jong Chul; Park, Ki Seok; Ha, Ho Gyun

    2012-01-01

    We present a case of an athetoid cerebral palsy with quadriparesis caused by kyphotic deformity of the cervical spine, severe spinal stenosis at the cervicomedullary junction, and atlantoaxial instability. The patient improved after the first surgery, which included a C1 total laminectomy and C-arm guided righ side unilateral C1-2 transarticular screw fixation. C1-2 fixation was not performed on the other side because of an aberrant and dominant vertebral artery (VA). Eight months after the first operation, the patient required revision surgery for persistent neck pain and screw malposition. We used intraoperative VA angiography with simultaneous fluoroscopy for precise image guidance during bilateral C1-2 transarticular screw fixation. Intraoperative VA angiography allowed the accurate insertion of screws, and can therefore be used to avoid VA injury during C1-2 transarticular screw fixation in comorbid patients with atlantoaxial deformities. PMID:22639719

  15. Endovascular Treatment of a Vertebral Artery Pseudoaneurysm Following Posterior C1-C2 Transarticular Screw Fixation

    SciTech Connect

    Mendez, Jose C. Gonzalez-Llanos, Francisco

    2005-01-15

    We present a case of vertebral artery pseudoaneurysm after a posterior C1-C2 transarticular screw fixation procedure that was effectively treated with endovascular coil occlusion. Vertebral artery pseudoaneurysm complicating posterior C1-C2 transarticular fixation is extremely rare, with only one previous case having been reported previously. Endovascular occlusion is better achieved in the subacute phase of the pseudoaneurysm, when the wall of the pseudoaneurysm has matured and stabilized. Further follow-up angiographies are mandatory in order to confirm that there is no recurrence of the lesion.

  16. [Troublesome radiologic changes after reconstructive fixation of the anterior cruciate ligament with resorbable interference screws].

    PubMed

    Loubignac, F; Lecuire, F; Rubini, J; Basso, M

    1998-03-01

    The authors report worrisome radiological changes which were noted after implantation of absorbable interference screws in ligamentoplasty at the knee joint. Seventeen screws were implanted between September 1995 and July 1996, in eleven patients (average age 27) who were operated upon for chronic anterior knee instability. They underwent a modified Kenneth Jones procedure using autografts with absorbable interference screws (Acufex in 2 cases and Bio-interférix in 9 cases). Significant enlargement of bone tunnels and bony sclerosis of their edges were noted in every patient, but without any modification in the positioning of the graft. No clinical instability was observed in any of the patients, with one to two years follow-up. Publications on this topic are scarce except for one author who reported enlargement of bone tunnels after using bone-patellar tendon-bone allografts. Resorption of absorbable screws probably induces a marked inflammatory reaction, with radiological changes reminiscent of those sometimes observed after tendon allografts. Although the radiological changes reported here may not affect the graft fixation, the authors have reverted to using metallic interference screws. PMID:9586250

  17. Pelvic Fixation in Adult and Pediatric Spine Surgery: Historical Perspective, Indications, and Techniques: AAOS Exhibit Selection.

    PubMed

    Jain, Amit; Hassanzadeh, Hamid; Strike, Sophia A; Menga, Emmanuel N; Sponseller, Paul D; Kebaish, Khaled M

    2015-09-16

    Achieving solid osseous fusion across the lumbosacral junction has historically been, and continues to be, a challenge in spine surgery. Robust pelvic fixation plays an integral role in achieving this goal. The goals of this review are to describe the history of and indications for spinopelvic fixation, examine conventional spinopelvic fixation techniques, and review the newer S2-alar-iliac technique and its outcomes in adult and pediatric patients with spinal deformity. Since the introduction of Harrington rods in the 1960s, spinal instrumentation has evolved substantially. Indications for spinopelvic fixation as a means to achieve lumbosacral arthrodesis include a long arthrodesis (five or more vertebral levels) or use of three-column osteotomies in the lower thoracic or lumbar spine, surgical treatment of high-grade spondylolisthesis, and correction of lumbar deformity and pelvic obliquity. A variety of techniques have been described over the years, including Galveston iliac rods, Jackson intrasacral rods, the Kostuik transiliac bar, iliac screws, and S2-alar-iliac screws. Modern iliac screws and S2-alar-iliac screws are associated with relatively low rates of pseudarthrosis. S2-alar-iliac screws have the advantages of less implant prominence and inline placement with proximal spinal anchors. Collectively, these techniques provide powerful methods for obtaining control of the pelvis in facilitating lumbosacral arthrodesis. PMID:26378268

  18. Minimally Invasive Mini Open Split-Muscular Percutaneous Pedicle Screw Fixation of the Thoracolumbar Spine

    PubMed Central

    Uluta?, Murat; Seçer, Mehmet; Çelik, Suat Erol

    2015-01-01

    We prospectively assessed the feasibility and safety of a new percutaneous pedicle screw (PPS) fixation technique for instrumentation of the thoracic and lumbar spine in this study. All patients were operated in the prone position under general anesthesia. A 6 to 8 cm midline skin incision was made and wide subcutaneous dissection was performed. The paravertebral muscles were first dissected subperiosteally into the midline incision of the fascia for lumbar microdiscectomy with transforaminal lumbar interbody fusion cage implantation. After the secondary paramedian incisions on the fascia, the PPSs were inserted via cleavage of the multifidus muscles directly into the pedicles under fluoroscopy visualization. A total of 35 patients underwent surgery with this new surgical technique. The control group for operative time, blood loss and analgesic usage consisted of 35 randomly selected cases from our department. The control group underwent surgery via conventional pedicle screw instrumentation with paramedian fusion. All patients in the minimal invasive surgery series were ambulatory with minimal pain on the first postoperative day. The operation time and blood loss and the postoperative analgesic consumption were significantly less with this new technique. In conclusion, the minimal invasive mini open split-muscular percutaneous pedicle screw fixation technique is safe and feasible. It can be performed via a short midline skin incision and can also be combined with interbody fusion, causing minimal pain without severe muscle damage. PMID:25874062

  19. Radiostrontium clearance and bone formation in response to simulated internal screw fixation

    SciTech Connect

    Daum, W.J.; Simmons, D.J.; Fenster, R.; Shively, R.A.

    1987-06-01

    Changes in radiostrontium clearance (SrC) and bone formation (tetracycline labeling) were observed in the femurs of skeletally mature dogs following the various operative steps involved in bone screw fixation. Drilling, but not periosteal stripping, produced a small but statistically significant increase in SrC and endosteal bone formation in the distal third of the bone. Strontium clearance values equivalent to those produced by drilling alone were recorded after screw fixation at low or high torque (5 versus 20 inch pounds), as well as by the insertion of loosely fitting stainless steel implants. Bone formation (equals the percentage tetracycline-labeled trabecular bone surfaces) was increased by 30% when SrC values exceeded 3.5 ml/100 g bone/min, and the relationship was linear when SrC values ranged between 1.0 and 7.0 ml/100 g bone/min. The changes in SrC and bone formation one-week after bone screw application are primarily those associated with a response to local trauma caused by drilling.

  20. Percutaneous Screw Fixation of Crescent Fracture-Dislocation of the Sacroiliac Joint.

    PubMed

    Shui, Xiaolong; Ying, Xiaozhou; Mao, Chuanwan; Feng, Yongzeng; Chen, Linwei; Kong, Jianzhong; Guo, Xiaoshan; Wang, Gang

    2015-11-01

    Crescent fracture-dislocation of the sacroiliac joint (CFDSIJ) is a type of lateral compression pelvic injury associated with instability. Open reduction and internal fixation is a traditional treatment of CFDSIJ. However, a minimally invasive method has never been reported. The purpose of this study was to assess the outcome of closed reduction and percutaneous fixation for different types of CFDSIJ and present their clinical outcome. The authors reviewed 117 patients diagnosed with CFDSIJ between July 2003 and July 2013. Closed reduction and percutaneous fixation was performed in 73 patients. Treatment selection was based on Day's fracture classification. For type I fractures, fixation perpendicular to the fracture line were performed. For type II fractures, crossed fixation was performed. For type III fractures, fixation was performed with iliosacral screws. Forty-four patients were treated by open reduction and plate fixation. Demographics, fracture pattern distribution, blood loss, incision lengths, revision surgeries, radiological results, and functional scores were compared. All 117 patients were followed for more than 6 months (mean, 14 months [range, 6-24 months]). Blood loss, extensive exposure, duration of posterior ring surgery, duration of hospital stay, and infection rates were lower in the closed group (P<.01). Patients in the closed group achieved better functional performance (P<.01). There were no significant differences in reduction quality (P=.32), revision surgery rates (P=.27), and iatrogenic neurologic injuries (P=.2) between the 2 groups. The authors' results indicate that closed reduction and percutaneous fixation is a safe and effective surgical method for CFDSIJ. [Orthopedics. 2015; 38(11):e976-e982.]. PMID:26558677

  1. Delayed Union of a Sacral Fracture: Percutaneous Navigated Autologous Cancellous Bone Grafting and Screw Fixation

    SciTech Connect

    Huegli, R. W. Messmer, P.; Jacob, A. L.; Regazzoni, P.; Styger, S.; Gross, T.

    2003-09-15

    Delayed or non-union of a sacral fracture is a serious clinical condition that may include chronic pain, sitting discomfort, gait disturbances, neurological problems, and inability to work. It is also a difficult reconstruction problem. Late correction of the deformity is technically more demanding than the primary treatment of acute pelvic injuries. Open reduction, internal fixation (ORIF), excision of scar tissue, and bone grafting often in a multi-step approach are considered to be the treatment of choice in delayed unions of the pelvic ring. This procedure implies the risk of neurological and vascular injuries, infection, repeated failure of union, incomplete correction of the deformity, and incomplete pain relief as the most important complications. We report a new approach for minimally invasive treatment of a delayed union of the sacrum without vertical displacement. A patient who suffered a Malgaigne fracture (Tile C1.3) was initially treated with closed reduction and percutaneous screw fixation (CRPF) of the posterior pelvic ring under CT navigation and plating of the anterior pelvic ring. Three months after surgery he presented with increasing hip pain caused by a delayed union of the sacral fracture. The lesion was successfully treated percutaneously in a single step procedure using CT navigation for drilling of the delayed union, autologous bone grafting, and screw fixation.

  2. Is cross-screw fixation superior to plate for radial neck fractures?

    PubMed

    Li, S L; Lu, Y; Wang, M Y

    2015-06-01

    This study compares the outcomes of two methods of fixation of displaced fractures of the radial neck. The 58 patients with a mean age of 38.5 years (18 to 56), were treated in a non randomised study with screws (n = 29) or a plate and screws (n = 29) according to the surgeon's preference. The patients were reviewed at one year. Radiographs and functional evaluations were carried out up to one year post-operatively, using the Broberg and Morrey functional evaluation score, range of movement, and assessment of complications. The mean functional scores did not differ significantly between groups (90 (55 to 100) vs 84; 50 to 100, p = 0.09), but the mean range of forearm rotation in screw group was significantly better than in the plate group (152°; 110° to 170° vs 134°; 80° to 170°, p = 0.001). Although not statistically significant, the screw group had a lower incidence of heterotopic ossification than the plate group (n = 1) than the plated group (n = 3) and the pathology was graded as less severe. PMID:26033065

  3. Morphometry of the cervical vertebral pedicles as a guide for transpedicular screw fixation.

    PubMed

    Kayalioglu, Gulgun; Erturk, Mete; Varol, Tuncay; Cezayirli, Enis

    2007-03-01

    Anatomical measurements of the cervical pedicle in a large series of human cervical vertebrae from 48 individuals were obtained to reduce the incidence and severity of complications caused by transpedicular screw placement. The greatest pedicle length was at C-3 and the greatest pedicle width was at C-6. Pedicle width and lateral mass thickness gradually increased from C-3 to C-6. Pedicle height and interpedicular distance increased from C-3 to C-5, and decreased slightly at C-6. The lateral mass-pedicle length was greatest at C-4. The present study found right-left differences for the pedicle-spinous process distance at C-6 (p < 0.05). Pedicle width and height were smaller than those reported in earlier studies, especially at C-3 and C-4, whereas the increasing pedicle widths at C-5 and C-6 were appropriate for pedicle screw fixation. PMID:17384491

  4. Experimental and Numerical Analysis of Screw Fixation in Anterior Cruciate Ligament Reconstruction

    NASA Astrophysics Data System (ADS)

    Chizari, Mahmoud; Wang, Bin; Snow, Martyn; Barrett, Mel

    2008-09-01

    This paper reports the results of an experimental and finite element analysis of tibial screw fixation in anterior cruciate ligament (ACL) reconstruction. The mechanical properties of the bone and tendon graft are obtained from experiments using porcine bone and bovine tendon. The results of the numerical study are compared with those from mechanical testing. Analysis shows that the model may be used to establish the optimum placement of the tunnel in anterior cruciate ligament reconstruction by predicting mechanical parameters such as stress, strain and displacement at regions in the tunnel wall.

  5. Balancing rigidity and safety of pedicle screw fixation via a novel expansion mechanism in a severely osteoporotic model.

    PubMed

    Shea, Thomas M; Doulgeris, James J; Gonzalez-Blohm, Sabrina A; Lee, William E; Aghayev, Kamran; Vrionis, Frank D

    2015-01-01

    Many successful attempts to increase pullout strength of pedicle screws in osteoporotic bone have been accompanied with an increased risk of catastrophic damage to the patient. To avoid this, a single-armed expansive pedicle screw was designed to increase fixation strength while controlling postfailure damage away from the nerves surrounding the pedicle. The screw was then subsequently tested in two severely osteoporotic models: one representing trabecular bone (with and without the presence of polymethylmethacrylate) and the other representing a combination of trabecular and cortical bone. Maximum pullout strength, stiffness, energy to failure, energy to removal, and size of the resulting block damage were statistically compared among conditions. While expandable pedicle screws produced maximum pullout forces less than or comparable to standard screws, they required a higher amount of energy to be fully removed from both models. Furthermore, damage to the cortical layer in the composite test blocks was smaller in all measured directions for tests involving expandable pedicle screws than those involving standard pedicle screws. This indicates that while initial fixation may not differ in the presence of cortical bone, the expandable pedicle screw offers an increased level of postfailure stability and safety to patients awaiting revision surgery. PMID:25705655

  6. Changes in the computed tomography (pixel) value of mandibular ramus bone and fixation screws after sagittal split ramus osteotomy.

    PubMed

    Ueki, K; Moroi, A; Iguchi, R; Kosaka, A; Ikawa, H; Yoshizawa, K

    2015-11-01

    The purpose of this retrospective study was to evaluate the changes in computed tomography (CT) values of ramus bone and screws after sagittal split ramus osteotomy (SSRO) setback surgery. The subjects were 64 patients (128 sides) who underwent bilateral SSRO setback surgery. They were divided into six groups according to the fixation plate type used and the use or not of self-setting ?-tricalcium phosphate (Biopex): group 1: titanium plate and screws; group 2: titanium plate and screws with Biopex; group 3: poly-l-lactic acid (PLLA) plate and screws; group 4: PLLA plate and screws with Biopex; group 5: uncalcined and unsintered hydroxyapatite particles and poly-l-lactic acid (uHA/PLLA) plate and screws; group 6: PLLA/uHA plate and screws with Biopex. CT values (pixel values) of the lateral cortex, medial cortex, osteotomy site, and screws were measured preoperatively, immediately after surgery, and 1 year postoperatively using horizontal CT images at the mandibular foramen taken parallel to the Frankfort horizontal plane. There were significant differences in the time-course change of pixel values for the lateral cortex (P<0.0001) and the osteotomy site (P<0.0001) among the six groups. This study suggests that the fixation plate type and use of bone alternative material may affect bone quality during the process of bone healing after SSRO. PMID:26139563

  7. Balancing Rigidity and Safety of Pedicle Screw Fixation via a Novel Expansion Mechanism in a Severely Osteoporotic Model

    PubMed Central

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

    2015-01-01

    Many successful attempts to increase pullout strength of pedicle screws in osteoporotic bone have been accompanied with an increased risk of catastrophic damage to the patient. To avoid this, a single-armed expansive pedicle screw was designed to increase fixation strength while controlling postfailure damage away from the nerves surrounding the pedicle. The screw was then subsequently tested in two severely osteoporotic models: one representing trabecular bone (with and without the presence of polymethylmethacrylate) and the other representing a combination of trabecular and cortical bone. Maximum pullout strength, stiffness, energy to failure, energy to removal, and size of the resulting block damage were statistically compared among conditions. While expandable pedicle screws produced maximum pullout forces less than or comparable to standard screws, they required a higher amount of energy to be fully removed from both models. Furthermore, damage to the cortical layer in the composite test blocks was smaller in all measured directions for tests involving expandable pedicle screws than those involving standard pedicle screws. This indicates that while initial fixation may not differ in the presence of cortical bone, the expandable pedicle screw offers an increased level of postfailure stability and safety to patients awaiting revision surgery. PMID:25705655

  8. Bioabsorbable plates and screws fixation in mandible fractures: clinical retrospective research during a 10-year period.

    PubMed

    Rha, Eun Young; Paik, Hyewon; Byeon, Jun Hee

    2015-04-01

    We present the basic guidelines for the safe fixation of a mandible fracture using a bioabsorbable system with less strength than the metallic system based on our 10 years of experience.We conducted a retrospective review of 75 patients who had undergone fixation using a bioabsorbable system for a mandible fracture. We analyzed the method of fixation and the size and thickness of the plates and screws that were selected depending on the mandible's fracture site.Minor complications including intraoral wound disruptions and infections occurred in 12 (16%) patients, and 2 (2.7%) patients among 10 patients who presented with infections had nonunion; therefore, they underwent replacement of the absorbable system with the titanium system. Bone resorption that was caused by the absorbable plate occurred in 12 (16%) patients.The bioabsorbable system also may be able to replace the metallic system in the fixation of comminuted mandible fractures if further research on the development of the system is supported. PMID:25551864

  9. Intraoperative Computed Tomography Navigation for Transpedicular Screw Fixation to Treat Unstable Thoracic and Lumbar Spine Fractures

    PubMed Central

    Lee, Ching-Yu; Wu, Meng-Huang; Li, Yen-Yao; Cheng, Chin-Chang; Hsu, Chu-Hsiang; Huang, Tsung-Jen; Hsu, Robert Wen-Wei

    2015-01-01

    Abstract Transpedicular screw (TPS) fixation in unstable thoracic and lumbar (TL) spine fractures remains technically difficult because of destroyed anatomical landmarks, unstable gross segments, and discrepancies in anatomic orientation using conventional anatomic landmarks, fluoroscopic guidance, or computed tomography (CT)-based navigation. In this study, we evaluated the safety and accuracy of TPS placement under intraoperative computed tomography (iCT) navigation in managing unstable TL spine fractures. From 2010 to 2013, we retrospectively reviewed the Spine Operation Registry records of patients who underwent posterior instrumented fusion to treat unstable TL spine fractures via the iCT navigation system. An unstable spine fracture was identified as AO/Magerl classification type B or type C. In all, 316 screws in 37 patients with unstable TL spine fractures were evaluated and involved 7 thoracic, 23 thoracolumbar junctional, and 7 lumbar fractures. The accuracy of TPS positioning in the pedicle without breach was 98% (310/316). The average number of iCT scans per patient was 2.1 (range 2–3). The average total radiation dose to patients was 15.8?mSv; the dose per single level exposure was 2.7?mSv. The TPS intraoperative revision rate was 0.6% (2/316) and no neurovascular sequela was observed. TPS fixation using the iCT navigation system obtained a 98% accuracy in stabilizing unstable TL spine fractures. A malplaced TPS could be revised during real-time confirmation of the TPS position, and no secondary operation was required to revise malplaced screws. The iCT navigation system provides accurate and safe management of unstable TL spine fractures. In addition, operating room personnel, including surgeons and nurses, did not need to wear heavy lead aprons as they were not exposed to radiation. PMID:25997042

  10. Odontoid balloon kyphoplasty associated with screw fixation for Type II fracture in 2 elderly patients.

    PubMed

    Terreaux, Luc; Loubersac, Thomas; Hamel, Olivier; Bord, Eric; Robert, Roger; Buffenoir, Kevin

    2015-03-01

    Anterior screw fixation is a well-recognized technique that is used to stabilize Type IIB fractures of the odontoid process in the elderly. However, advanced age and osteoporosis are 2 risk factors for pseudarthrosis. Kyphoplasty has been described in the treatment of lytic lesions in C-2. The authors decided to combine these 2 techniques in the treatment of unstable fractures of the odontoid. Two approximately 90-year-old patients were treated for this type of fracture. Instability was demonstrated on dynamic radiography in one patient, and the fracture was seen on static radiography in the other. Clinical parameters, pain, range of motion, 36-Item Short Form Health Survey (SF-36) score (for the first patient), and radiological examinations (CT scans and dynamic radiographs) were studied both before and after surgery. After inflating the balloon both above and below the fracture line, the authors applied a high-viscosity polymethylmethacrylate cement. Some minor leakage of cement was noted in both cases but proved to be harmless. The screws were correctly positioned. The clinical result was excellent, both in terms of pain relief and in the fact that there was no reduction in the SF-36 score. The range of motion remained the same. A follow-up CT scan obtained 1 year later in one of the patients showed no evidence of change in the materials used, and the dynamic radiographs showed no instability. This combination of kyphoplasty and anterior screw fixation of the odontoid seems to be an interesting technique in osteoporotic Type IIB fractures of the odontoid process in the elderly, with good results both clinically and radiologically. PMID:25555053

  11. Superior fixation of pegged trabecular metal over screw-fixed pegged porous titanium fiber mesh

    PubMed Central

    2011-01-01

    Background and purpose Lasting stability of cementless implants depends on osseointegration into the implant surface, and long-term implant fixation can be predicted using radiostereometric analysis (RSA) with short-term follow-up. We hypothesized that there would be improved fixation of high-porosity trabecular metal (TM) tibial components compared to low-porosity titanium pegged porous fiber-metal (Ti) polyethylene metal backings. Methods In a prospective, parallel-group, randomized unblinded clinical trial, we compared cementless tibial components in patients aged 70 years and younger with osteoarthritis. The pre-study sample size calculation was 22 patients per group. 25 TM tibial components were fixed press-fit by 2 hexagonal pegs (TM group) and 25 Ti tibial components were fixed press-fit and by 4 supplemental screws (Ti group). Stereo radiographs for evaluation of absolute component migration (primary effect size) and single-direction absolute component migration (secondary effect size) were obtained within the first postoperative week and at 6 weeks, 6 months, 1 year, and 2 years. American Knee Society score was used for clinical assessment preoperatively, and at 1 and 2 years. Results There were no intraoperative complications, and no postoperative infections or revisions. All patients had improved function and regained full extension. All tibial components migrated initially. Most migration of the TM components (n = 24) occurred within the first 3 months after surgery whereas migration of the Ti components (n = 22) appeared to stabilize first after 1 year. The TM components migrated less than the Ti components at 1 year (p = 0.01) and 2 years (p = 0.004). Interpretation We conclude that the mechanical fixation of TM tibial components is superior to that of screw-fixed Ti tibial components. We expect long-term implant survival to be better with the TM tibial component. PMID:21434781

  12. Iliac Crest Avulsion Fracture in a Young Sprinter

    PubMed Central

    Casabianca, L.; Rousseau, R.; Loriaut, P.; Massein, A.; Mirouse, G.; Gerometta, A.; Khiami, F.

    2015-01-01

    Avulsion fracture of the iliac crest is an uncommon pathology. It usually occurs in teenagers during sport activities, more common in boys. We report a case of 16-year-old male competitive sprinter, who had an avulsion of a part of the iliac crest and the anterior-superior iliac spine during a competition. The traumatism occurred during the period of acceleration phase out of the blocks which corresponds to the maximum traction phase on the tendons. Then a total loss of function of the lower limb appears forcing him to stop the run. X-ray and CT scan confirmed the rare diagnosis of avulsion of the quasitotality of the iliac crest apophysis, corresponding to Salter 2 fracture. We performed an open reduction and internal fixation with two screws, allowing a return to sport after 3 months and his personal best record in the 100 meters at the 6th postoperative month. PMID:26421205

  13. Percutaneous Cement-Augmented Screws Fixation in the Fractures of the Aging Spine: Is It the Solution?

    PubMed Central

    Pesenti, Sébastien; Peltier, Emilie; Adetchessi, Tarek; Dufour, Henry; Fuentes, Stéphane

    2014-01-01

    Introduction. Management of elderly patients with thoracolumbar fractures is still challenging due to frequent osteoporosis and risk of screws pull-out. The aim of this study was to evaluate results of a percutaneous-only procedure to treat these fragile patients using cement-augmented screws. Methods. 12 patients diagnosed with a thoracolumbar fracture associated with an important loss of bone stock were included in this prospective study. Surgical procedure included systematically a percutaneous osteosynthesis using cemented fenestrated screws. When necessary, additional anterior support was performed using a kyphoplasty procedure. Clinical and radiographic evaluations were performed using CT scan. Results. On the whole series, 15 fractures were diagnosed and 96 cemented screws were inserted. The difference between the pre- and postoperative vertebral kyphosis was statistically significant (12.9° versus 4.4°, P = 0.0006). No extrapedicular screw was reported and one patient was diagnosed with a cement-related pulmonary embolism. During follow-up period, no infectious complications, implant failures, or pull-out screws were noticed. Discussion. Aging spine is becoming an increasing public health issue. Management of these patients requires specific attention due to the augmented risk of complications. Using percutaneous-only screws fixation with cemented screw provides satisfactory results. A rigorous technique is mandatory in order to achieve best outcomes. PMID:24696858

  14. Pyoderma Gangrenosum Mimicking an Infected Wound following Dynamic Hip Screw Fixation

    PubMed Central

    Nizamoglu, Metin

    2015-01-01

    Pyoderma gangrenosum (PG) is an inflammatory ulcerative neutrophilic dermatosis that can occur following skin trauma. The correct diagnosis is not often made immediately as the condition can mimic an infective appearance. This leads to delays in the appropriate management of high dose steroids. Although debridement can offer aid in resolving lesions, this is contraindicated in the acute phase as this can cause acceleration of the pathogenic process. Biopsy of the lesion does not offer a definitive diagnosis; therefore suspicion must be maintained as the diagnosis is ultimately a clinical one. Any postoperative pustular ulcerative lesion not improving despite antibiotic therapy that also yields negative bacteriological and fungal studies should lead to consideration of this diagnosis. We document the first case of PG developing following intertrochanteric femur fracture fixation using dynamic hip screw. PMID:26380139

  15. Use of a Percutaneous Pointed Reduction Clamp Before Screw Fixation to Prevent Gapping of a Fifth Metatarsal Base Fracture: A Technique Tip.

    PubMed

    Tan, Eric W; Cata, Ezequiel; Schon, Lew C

    2016-01-01

    Intramedullary screw fixation has become widely accepted as the standard of care for operative treatment of Jones fractures, allowing not only accelerated rehabilitation but also reduction of the risk of repeat fracture. The unique anatomy of the fifth metatarsal-mainly its inherent lateral curvature-makes fixation technically challenging. In general, surgical fixation should be performed with the largest screw possible, in both diameter and length, which will provide the strongest possible construct. However, an increased screw length and width have been associated with complications, including lateral gapping and distraction of the fracture site and malreduction of the fracture. The use of a pointed reduction clamp is a simple, yet effective, method of preventing iatrogenic displacement and gapping at the fracture site during placement of an intramedullary screw. Percutaneous reduction and stabilization of the fracture using this technique could help limit the complications associated with large screw fixation of Jones fractures. PMID:26188626

  16. Straight, semi-anatomic and anatomic TMJ implants: the influence of condylar geometry and bone fixation screws.

    PubMed

    Ramos, A; Completo, A; Relvas, C; Mesnard, M; Simões, J A

    2011-07-01

    A 3D finite element model of in vitro intact and implanted mandibles with different temporomandibular joints (TMJ) was analyzed. Three TMJ implant geometries were assessed. The displacements, stress and strain fields on the condyle were obtained for both simulated cases. Strains were also assessed near the screws that fixate the implant to the mandible. The geometry of the mandible was obtained through 3D digitalization of a synthetic model. The TMJ implants studied were modelled considering a commercial implant which was also used to create semi-anatomic and anatomic implants that were analyzed and to assess the influence of the geometry. Numerical finite element models were built and the implants were positioned by an experienced orofacial surgeon. All implants were fixed by four screws which were placed in the same position on the mandible. The boundary conditions were simulated considering the support on the incisive tooth, the loads of the five most important muscular forces and a 5mm mouth aperture. This study indicates that the deformation on the intact mandible was similar when an anatomic implant was considered in the implanted mandible. However, the anatomic geometry presented some problems concerning the implant integrity due to geometric variations. The geometry of TMJ implant also played a role relatively to the screws structural integration and bone fixation. The geometry of TMJ implant defines the necessary number of screws and position in the mandible fixation. PMID:20801667

  17. Analysis of the Stress and Displacement Distribution of Inferior Tibiofibular Syndesmosis Injuries Repaired with Screw Fixation: A Finite Element Study

    PubMed Central

    Liu, Qinghua; Zhang, Kun; Zhuang, Yan; Li, Zhong; Yu, Bin; Pei, Guoxian

    2013-01-01

    Background Studies of syndesmosis injuries have concentrated on cadaver models. However, they are unable to obtain exact data regarding the stress and displacement distribution of various tissues, and it is difficult to compare models. We investigated the biomechanical effects of inferior tibiofibular syndesmosis injuries (ITSIs) and screw fixation on the ankle using the finite element (FE) method. Methodology/Principal Findings A three-dimensional model of a healthy ankle complex was developed using computed tomography (CT) images. We established models of an ITSI and of screw fixation at the plane 2.5 cm above and parallel to the tibiotalar joint surface of the injured syndesmosis. Simulated loads were applied under three conditions: neutral position with single-foot standing and internal and external rotation of the ankle. ITSI reduced contact forces between the talus and fibula, helped periarticular ankle ligaments withstand more load-resisting movement, and increased the magnitude of displacement at the lower extreme of the tibia and fibula. ITSI fixation with a syndesmotic screw reduced contact forces in all joints, decreased the magnitude of displacement at the lower extreme of the tibia and fibula, and increased crural interosseous membrane stress. Conclusions/significance Severe syndesmosis injuries cause stress and displacement distribution of the ankle to change multidirectional ankle instability and should be treated by internal fixation. Though the transverse syndesmotic screw effectively stabilizes syndesmotic diastasis, it also changes stress distribution around the ankle and decreases the joint's range of motion (ROM). Therefore, fixation should not be performed for a long period of time because it is not physiologically suitable for the ankle joint. PMID:24312464

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

    PubMed

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

    2016-01-01

    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. PMID:25944146

  19. Treatment of neuromuscular scoliosis with posterior-only pedicle screw fixation

    PubMed Central

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

    2008-01-01

    Background To determine whether posterior-only approach using pedicle screws in neuromuscular scoliosis population adequately addresses the correction of scoliosis and maintains the correction over time. Methods Between 2003 and 2006, 26 consecutive patients (7 cerebral palsy, 10 Duchenne muscular dystrophy, 5 spinal muscular atrophy and 4 others) with neuromuscular scoliosis underwent posterior pedicle screw fixation for the deformity. Preoperative, immediate postoperative and final follow-up Cobb's angle and pelvic obliquity were analyzed on radiographs. The average age of the patients was 17.5 years (range, 8–44 years) and the average follow-up was 25 months (18–52 months). Results Average Cobb's angle was 78.53° before surgery, 30.70° after surgery (60.9% correction), and 33.06° at final follow-up (57.9% correction) showing significant correction (p < 0.0001). There were 9 patients with curves more than 90° showed an average pre-operative, post operative and final follow up Cobb's angle 105.67°, 52.33° (50.47% correction) and 53.33° (49.53% correction) respectively and 17 patients with curve less than 90° showed average per operative, post operative and final follow up Cobb's angle 64.18, 19.24(70% correction) and 21.41(66.64 correction); which suggests statistically no significant difference in both groups (p = 0.1284). 7 patients underwent Posterior vertebral column resection due to the presence of a rigid curve. The average spinal-pelvic obliquity was 16.27° before surgery, 8.96° after surgery, and 9.27° at final follow-up exhibited significant correction (p < 0.0001). There was 1 poliomyelitis patient who had power grade 3 in lower limbs pre-operatively, developed grade 2 power post-operatively and gradually improved to the pre-operative stage. There was 1 case of deep wound infection and no case of pseud-arthrosis, instrument failures or mortality. Conclusion Results indicate that in patients with neuromuscular scoliosis, acceptable amounts of curve correction can be achieved and maintained with posterior-only pedicle screw instrumentation without anterior release procedure. PMID:18544164

  20. Assessment of compression and strength of divergent screws mounted on miniplates for fixation of mandibular fractures: an in vitro experimental study.

    PubMed

    Jafarian, M; Pourdanesh, F; Esmaeelinejad, M; Dehghani, N; Aghdashi, F; Tabrizi, R

    2015-09-01

    An efficient band of tension is critical for the adequate fixation of mandibular fractures, so fixation devices that compress are helpful. We aimed to evaluate the possibility of creating compression using screws inserted divergently into miniplates placed in the tension zone of mandibular fractures and record the effects on the strength of fixation. For this in vitro experimental study we prepared 20 sheep hemimandibles. After angle fractures had been created, the specimens were divided into standard and study groups (n=10 in each). In the standard group the tension zones were fixed in the standard manner with 4-hole miniplates and 4 parallel screws. Those in the study group were fixed as for the standard group but with 4×45° divergent screws. The differences in the gap in the fracture line before and after fixation were measured as indicators of compression. The strength of fixation was also assessed with a universal testing machine in vitro. The amount of compression was significant only in the study group (p<0.001), and there was no difference in the strength of fixation between the two groups (p=0.7). We conclude that divergent drilling and insertion of screws creates more horizontal force when miniplates are used, and results in reduction in the size of the probable gap in the fracture line. Insertion of divergent screws in miniplates may create compression between fractured segments without jeopardising the strength of fixation. PMID:25921364

  1. When Planning Screw Fracture Fixation Why the 5.5?mm Screw is the Goldilocks Screw. An Observational Computer Tomographic Study of Fifth Metatarsal Bone Anatomy in a Sample of Patients

    PubMed Central

    Iselin, Lukas D.; Ramawat, Sunil; Hanratty, Brian; Klammer, Georg; Stavrou, Peter

    2015-01-01

    Abstract We wanted to verify our clinical experience that the 5.5?mm screw was ideal in the majority of fifth metatarsal fracture fixation. The size of a screw is important for the successful surgical treatment of these fractures in order to obtain the maximal stability while reducing the risk for iatrogenic fracture. A sample of patients undergoing computer tomographic imaging of the foot for investigation other than fifth metatarsal pathology were recruited. The parameters of the fifth metatarsal bone anatomy were measured. These parameters of the 5.5?mm screw were correlated with this data. The upper parameter (the diameter of the threads) was 5.5 and the lower parameter (the diameter of the shank) was 4.0?mm. Twenty seven patients were recruited. The proximal third internal diameter ranged from 3.6 to 7.0?mm with a mean of 5.0?mm. 93% of the metatarsals could easily accommodate the 5.5?mm screw. Two of the metatarsals had an internal diameter of < 4?mm (7%). It is our belief that the 5.5?mm screw may be used safely in the majority of patients with fifth metatarsal fractures. PMID:25950685

  2. When Planning Screw Fracture Fixation Why the 5.5?mm Screw is the Goldilocks Screw. An Observational Computer Tomographic Study of Fifth Metatarsal Bone Anatomy in a Sample of Patients.

    PubMed

    Iselin, Lukas D; Ramawat, Sunil; Hanratty, Brian; Klammer, Georg; Stavrou, Peter

    2015-05-01

    We wanted to verify our clinical experience that the 5.5?mm screw was ideal in the majority of fifth metatarsal fracture fixation. The size of a screw is important for the successful surgical treatment of these fractures in order to obtain the maximal stability while reducing the risk for iatrogenic fracture.A sample of patients undergoing computer tomographic imaging of the foot for investigation other than fifth metatarsal pathology were recruited. The parameters of the fifth metatarsal bone anatomy were measured.These parameters of the 5.5?mm screw were correlated with this data. The upper parameter (the diameter of the threads) was 5.5 and the lower parameter (the diameter of the shank) was 4.0?mm.Twenty seven patients were recruited.The proximal third internal diameter ranged from 3.6 to 7.0?mm with a mean of 5.0?mm. 93% of the metatarsals could easily accommodate the 5.5?mm screw. Two of the metatarsals had an internal diameter of < 4?mm (7%).It is our belief that the 5.5?mm screw may be used safely in the majority of patients with fifth metatarsal fractures. PMID:25950685

  3. CT-based morphometric analysis of C1 laminar dimensions: C1 translaminar screw fixation is a feasible technique for salvage of atlantoaxial fusions

    PubMed Central

    Yew, Andrew; Lu, Derek; Lu, Daniel C.

    2015-01-01

    Background: Translaminar screw fixation has become an alternative in the fixation of the axial and subaxial cervical spine. We report utilization of this approach in the atlas as a salvage technique for atlantoaxial stabilization when C1 lateral mass screws are precluded. To assess the feasibility of translaminar fixation at the atlas, we have characterized the dimensions of the C1 lamina in the general adult population using computed tomography (CT)-based morphometry. Methods: A 46-year-old male with symptomatic atlantoaxial instability secondary to os odontoideum underwent bilateral C1 and C2 translaminar screw/rod fixation as C1 lateral mass fixation was precluded by an anomalous vertebral artery. The follow-up evaluation 2½ years postoperatively revealed an asymptomatic patient without recurrent neck/shoulder pain or clinical signs of instability. To better assess the feasibility of utilizing this approach in the general population, we retrospectively analyzed 502 consecutive cervical CT scans performed over a 3-month period in patients aged over 18 years at a single institution. Measurements of C1 bicortical diameter, bilateral laminar length, height, and angulation were performed. Laminar and screw dimensions were compared to assess instrumentation feasibility. Results: Review of CT imaging found that 75.9% of C1 lamina had a sufficient bicortical diameter, and 63.7% of C1 lamina had sufficient height to accept bilateral translaminar screw placement. Conclusions: CT-based measurement of atlas morphology in the general population revealed that a majority of C1 lamina had sufficient dimensions to accept translaminar screw placement. Although these screws appear to be a feasible alternative when lateral mass screws are precluded, further research is required to determine if they provide comparable fixation strength versus traditional instrumentation methods. PMID:26005585

  4. Analysis of stress induced by screws in the vertebral fixation system

    PubMed Central

    Fakhouri, Sarah Fakher; Shimano, Marcos Massao; de Araújo, Cleudmar Amaral; Defino, Helton Luiz Aparecido; Shimano, Antônio Carlos

    2014-01-01

    Objective: To compare, using photoelasticity, internal stress produced by USS II type screw with 5.2 and 6.2 mm external diameters, when submitted to three different pullout strengths. Methods: Two photoelastic models were especially made. The simulation was performed using loads of 1.8, 2.4 e 3.3 kgf.The fringe orders were evaluated around the screws. In all the models analyzed the shear stress were calculated. Results: Independently of the applied load, the smaller screw showed higher values of shear stress. Conclusion: According to the analysis performed, we observed that the place of highest stress was in the first thread of the lead, close to the head of the screws. Experimental study. PMID:24644414

  5. Posterior occipito-axial fixation applied C2 laminar screws for pediatric atlantoaxial instability caused by Down syndrome: Report of 2 cases

    PubMed Central

    Kuroki, Hiroshi; Kubo, Shinichiro; Hamanaka, Hideaki; Chosa, Etsuo

    2012-01-01

    Background Upper cervical spine instability is one of the most critical orthopedic problems in patients with Down syndrome. However, arthrodesis of the upper cervical spine in these patients can be very difficult to achieve and has a high complication rate because of mental retardation and accompanying various medical conditions of the vital organs. Even now, surgeries in such patients, especially pediatric cases, are challenging and the optimal operative procedure remains unsettled. The purpose of this study was to report 2 cases of pediatric atlantoaxial instability due to Down syndrome in which posterior occipito-axial fixation with C2 laminar screws was performed. Methods Case 1 was a girl aged 6 years 10 months who had atlantoaxial rotatory fixation with os odontoideum. Atlantoaxial rotatory fixation was incompletely reduced by halo traction, and it was not maintained without halo-ring and -vest fixation. Posterior occipito-axial fixation with bilateral C2 laminar screws was then performed. Case 2 was a boy aged 10 years 7 months who had atlantoaxial subluxation with os odontoideum. He also had incomplete quadriplegia, so he could neither walk nor have a meal by himself. Posterior occipito-axial fixation with right C2 pedicle and left C2 laminar screws was then carried out. Results In case 1 bone union was obtained at 3 months after surgery and the patient's symptoms were resolved. In case 2 bone union was obtained at 3 months after surgery and the paralysis was improved. Conclusions/level of evidence In cases of atlantoaxial instability due to Down syndrome, symptomatic patients often present between ages 5 and 15 years and mental retardation interferes with postoperative cervical immobilization. C2 laminar screws can be safely applied for the pediatric axis and biomechanically accomplished rigid fixation. The C2 laminar screw is one of the most useful options to achieve stability of the pediatric atlantoaxial complex without the risk of vertebral artery injuries (level IV case series). PMID:25694894

  6. Transpedicular fixation of the lumbar and lumbosacral spine with screws. Application of the Diapason system.

    PubMed

    Yanase, M; Sakou, T; Taketomi, E; Yone, K

    1995-04-01

    Forty-six patients with the Diapason transpedicular screw system for lumbar and lumbosacral fusions were analysed clinically. No implant breakage was observed, but one rod migrated. Additional sacral screws different in the length of the threaded portion are necessary in this system. Metallosis was noted in a few cases, but posed no significant clinical problems. This system, which is simple in structure, easy to use, and applicable to magnetic resonance scanning after surgery, is considered to be a useful instrumentation. PMID:7609979

  7. All-Arthroscopic Suprapectoral Long Head of Biceps Tendon Tenodesis With Interference Screw–Like Tendon Fixation After Modified Lasso-Loop Stitch Tendon Securing

    PubMed Central

    Patzer, Thilo; Kircher, Jörn; Krauspe, Ruediger

    2012-01-01

    Arthroscopic suprapectoral techniques for tenodesis of the long head of the biceps tendon (LHB) are appropriate for the treatment of proximal biceps lesions. Several types of techniques and fixation devices have been described and evaluated in biomechanical studies regarding primary stability. In this technical note, we describe an all-arthroscopic suprapectoral technique using the 6.25-mm Bio-SwiveLock device (Arthrex, Naples, FL) for an interference screw–like bony fixation after having armed the tendon with a lasso-loop stitch. Both the interference screw fixation and securing of the lasso-loop tendon have been well described and approved in biomechanical tests concerning the primary stability. One advantage of this technique performed from the glenohumeral space, in addition to the strong and secure fixation with ingrowth of the tendon in a bony canal, is the avoidance of touching the soft tissue above the bicipital groove, which results in a smooth fitting of the tendon into its natural canal and therefore avoids mechanical irritation of the stump at the rotator interval. In conclusion, the all-arthroscopic suprapectoral LHB tenodesis performed from the glenohumeral space with the modified lasso-loop stitch for securing of the tendon and the 6.25-mm Bio-SwiveLock suture anchor for interference screw–like bony tendon fixation is an appropriate technique for the treatment of LHB-associated lesions. PMID:23766976

  8. [Mechanical principle and clinical application of the combined spinal rod-plate and transpedicular screws fixation system].

    PubMed

    Zhang, G H

    1989-12-01

    Twenty-one patients with unstable burst fractures of the lower thoracic and lumbar spine were treated with a combined spinal rod-plate and transpedicular screws (CSRP-TPS) fixation system. This system is a new device for disorders of the lower thoracic and lumbar spine. In treatment of spinal fractures, it provided three-column axial distraction and stabilized the injured vertebra in a lordotic position-this maximized the reduction and indirectly achieved a neurologic decompression by ligamentotaxis. This "indirect" neurologic decompression was more successful in cases treated early after injury as the spinal canal area (measured by pre- and postoperative CT) increased 35% in cases treated within one week after injury; 25% in cases treated 7-14 days after injury; and there was little improvement in cases treated more than two weeks following injury. All patients had a minimum follow-up of 12 months. There were no infections, iatrogenic neurologic deficits or instrumentation failures. The CSRP-TPS system gave more improved results over conventional Harrington and segmental spinal instrumentation systems and only required fixation and fusion of three vertebral levels. PMID:2636110

  9. Evaluation of implant loosening following segmental pedicle screw fixation in adolescent idiopathic scoliosis: a 2 year follow-up with low-dose CT

    PubMed Central

    2014-01-01

    Background The long term radiological status of screw fixation following scoliosis surgery with all pedicle screw construct is not previously studied. Aim To evaluate the incidence of loosening (implant failure) evaluated with low-dose CT two years following scoliosis surgery. Study design Retrospective study. Methods 81 consecutive patients with adolescent idiopathic scoliosis (AIS), aged 18?±?3 years at 2 years follow-up (83% were female), subjected for scoliosis corrective surgery with all pedicle screw construct (total of 1666 screws) has been examined with plain radiography and with low dose CT 6 weeks and 2 years postoperatively. Results In 26 out of 81 (32%) patients there were signs of loosening of one or more screws, a maximum 3 screws. 47 out of 1666 (2.8%) screws showed evidence of loosening. Preoperative Cobb angle was 56° among patients with loosening compared with 53° among patients with no evidence of loosening (P?=?0.288). In males there were signs of loosening in 8 out of 14 (57%) and in females 18 out of 67 (27%), (P?=?0.027). Among cases with loosening, 14% had suboptimal screw placement at the first postoperative CT compared with 11% among patients with no evidence of loosening (P?=?0.254). One patient with a loosened L4 screw had neurological deficit and subjected for revision of the construct. Out of 26 patients with evidence of loosening, 5 patients reported minor pain or discomfort, 1 patient had a minor proximal junctional kyphosis of about 15° and 3 patients showed evidence of pull-out of 3–5 mm at the upper end of the construct but no clinical complaint. With plain radiography loosening could be observed only in 11 out of 26 cases, 5 were in the lumbar region. Conclusions In a consecutive series of 81 cases with AIS who had underwent scoliosis surgery, one third showed, 2 years after the intervention, minor screw loosening. Males were more prone to develop screw loosening. In CT system that enables low-dose protocol, CT is recommended for the evaluation of evidence of screw loosening. PMID:25177357

  10. Screw locking elements: a means to modify the flexibility of osteoporotic fracture fixation with DCPs without compromising system strength or stability.

    PubMed

    Yánez, A; Cuadrado, A; Carta, J A; Garcés, G

    2012-07-01

    This paper analyses whether it is possible to use dynamic compression plates (DCPs) and screw locking elements (SLEs) to vary the flexibility of osteoporotic fracture fixation without compromising the strength and stability of the construct. Compression, torsion and four-point bending static strength tests were conducted. Cyclic load tests of up to 10,000 load cycles were also carried out to determine stiffness performance. Four fixation systems were mounted onto polyurethane bone models. Group 1 consists of the DCP and six cortical screws. Group 2, idem, but with the addition of two SLEs. Group 3, idem, but with the addition of six SLEs. Group 4 used the locking compression plate (LCP) and locking screws. The results indicated no significant difference (p>0.05) in the strength of groups 2-4. It was also observed that the torsional stiffness of group 3 (0.30 Nm/°) was higher than that of group 2 (0.23 Nm/°) and similar to that of group 4 (0.28 Nm/°). Compression stiffness of group 4 (124 N/mm) was higher than that of group 2 (102 N/mm), but lower than that of group 3 (150 N/mm). No notable differences were observed for structural bending stiffness. It is concluded that by using the DCP with SLEs it is possible to modify the stiffness of the fixation construct for the repair of osteoporotic fractures and, in this way, facilitate the conditions suitable on secondary bone healing. PMID:21982962

  11. CT Morphometric Analysis to Determine the Anatomical Basis for the Use of Transpedicular Screws during Reconstruction and Fixations of Anterior Cervical Vertebrae

    PubMed Central

    Chen, Chun; Ruan, Dike; Wu, Changfu; Wu, Weidong; Sun, Peidong; Zhang, Yuanzhi; Wu, Jigong; Lu, Sheng; Ouyang, Jun

    2013-01-01

    Background Accurate placement of pedicle screw during Anterior Transpedicular Screw fixation (ATPS) in cervical spine depends on accurate anatomical knowledge of the vertebrae. However, little is known of the morphometric characteristics of cervical vertebrae in Chinese population. Methods Three-dimensional reconstructions of CT images were performed for 80 cases. The anatomic data and screw fixation parameters for ATPS fixation were measured using the Mimics software. Findings The overall mean OPW, OPH and PAL ranged from 5.81 to 7.49 mm, 7.77 to 8.69 mm, and 33.40 to 31.13 mm separately, and SPA was 93.54 to 109.36 degrees from C3 to C6, 104.99 degrees at C7, whereas, 49.00 to 32.26 degrees from C4 to C7, 46.79 degrees at C3 (TPA). Dl/rSIP had an increasing trend away from upper endplate with mean value from 1.87 to 5.83 mm. Dl/rTIP was located at the lateral portion of the anterior cortex of vertebrae for C3 to C5 and ipsilateral for C6 to C7 with mean value from ?2.70 to ?3.00 mm, and 0.17 to 3.18 mm. The entrance points for pedicular screw insertion for C3 to C5 and C6 to C7 were recommended ?2??3 mm and 0–4 mm from the median sagittal plane, respectively, 1–4 mm and 5–6 mm from the upper endplate, with TPA being 46.79–49.00 degrees and 40.89–32.26 degrees, respectively, and SPA being 93.54–106.69 degrees and 109.36–104.99 degrees, respectively. The pedicle screw insertion diameter was recommended 3.5 mm (C3 and C4), 4.0 mm (C5 to C7), and the pedicle axial length was 21–24 mm for C3 to C7 for both genders. However, the ATPS insertion in C3 should be individualized given its relatively small anatomical dimensions. Conclusions The data provided a morphometric basis for the ATPS fixation technique in lower cervical fixation. It will help in preoperative planning and execution of this surgery. PMID:24349038

  12. Segmental correction of adolescent idiopathic scoliosis by all-screw fixation method in adolescents and young adults. minimum 5 years follow-up with SF-36 questionnaire

    PubMed Central

    2012-01-01

    Background In our institution, the fixation technique in treating idiopathic scoliosis was shifted from hybrid fixation to the all-screw method beginning in 2000. We conducted this study to assess the intermediate -term outcome of all-screw method in treating adolescent idiopathic scoliosis (AIS). Methods Forty-nine consecutive patients were retrospectively included with minimum of 5-year follow-up (mean, 6.1; range, 5.1-7.3 years). The average age of surgery was 18.5 ± 5.0 years. We assessed radiographic measurements at preoperative (Preop), postoperative (PO) and final follow-up (FFU) period. Curve correction rate, correction loss rate, complications, accuracy of pedicle screws and SF-36 scores were analyzed. Results The average major curve was corrected from 58.0 ± 13.0° Preop to 16.0 ± 9.0° PO(p < 0.0001), and increased to 18.4 ± 8.6°(p = 0.12) FFU. This revealed a 72.7% correction rate and a correction loss of 2.4° (3.92%). The thoracic kyphosis decreased little at FFU (22 ± 12° to 20 ± 6°, (p = 0.25)). Apical vertebral rotation decreased from 2.1 ± 0.8 PreOP to 0.8 ± 0.8 at FFU (Nash-Moe grading, p < 0.01). Among total 831 pedicle screws, 56 (6.7%) were found to be malpositioned. Compared with 2069 age-matched Taiwanese, SF-36 scores showed inferior result in 2 variables: physical function and role physical. Conclusion Follow-up more than 5 years, the authors suggest that all-screw method is an efficient and safe method. PMID:22340624

  13. Limited Unilateral Decompression and Pedicle Screw Fixation with Fusion for Lumbar Spinal Stenosis with Unilateral Radiculopathy: A Retrospective Analysis of 25 Cases

    PubMed Central

    Zhang, Li; Miao, Hai-xiong; Wang, Yong; Chen, An-fu; Zhang, Tao

    2015-01-01

    Objective Lumbar spinal stenosis is conventionally treated with surgical decompression. However, bilateral decompression and laminectomy is more invasive and may not be necessary for lumbar stenosis patients with unilateral radiculopathy. We aimed to report the outcomes of unilateral laminectomy and bilateral pedicle screw fixation with fusion for patients with lumbar spinal stenosis and unilateral radiculopathy. Methods Patients with lumbar spinal stenosis with unilateral lower extremity radiculopathy who received limited unilateral decompression and bilateral pedicle screw fixation were included and evaluated using visual analog scale (VAS) pain and the Oswestry Disability Index (ODI) scores preoperatively and at follow-up visits. Ligamentum flavum thickness of the involved segments was measured on axial magnetic resonance images. Results Twenty-five patients were included. The mean preoperative VAS score was 6.6±1.6 and 4.6±3.1 for leg and back pain, respectively. Ligamentum flavum thickness was comparable between the symptomatic and asymptomatic side (p=0.554). The mean follow-up duration was 29.2 months. The pain in the symptomatic side lower extremity (VAS score, 1.32±1.2) and the back (VAS score, 1.75±1.73) significantly improved (p=0.000 vs. baseline for both). The ODI improved significantly postoperatively (6.60±6.5; p=0.000 vs. baseline). Significant improvement in VAS pain and ODI scores were observed in patients receiving single or multi-segment decompression fusion with fixation (p<0.01). Conclusion Limited laminectomy and unilateral spinal decompression followed by bilateral pedicle screw fixation with fusion achieves satisfactory outcomes in patients with spinal stenosis and unilateral radiculopathy. This procedure is less damaging to structures that are important for maintaining posterior stability of the spine. PMID:26279816

  14. Minimally Invasive Sinus Tarsi Approach With Cannulated Screw Fixation Combined With Vacuum-Assisted Closure for Treatment of Severe Open Calcaneal Fractures With Medial Wounds.

    PubMed

    Zhang, Taiyuan; Yan, Yan; Xie, Xinmin; Mu, Weidong

    2016-01-01

    The aim of our prospective study was to investigate the clinical results and advantages of a minimally invasive sinus tarsi approach with cannulated screw fixation combined with vacuum-assisted closure for the treatment of severe open calcaneal fractures with medial wounds. A total of 31 patients (32 feet) with open calcaneal fractures who were admitted to our hospital from January 2008 to May 2013 were selected for the study and randomly divided into 2 groups: the cannulated screw group (n = 16 patients, 16 feet) and the plate group (n = 15 patients, 16 feet). The Böhler and Gissane angles were compared before and after surgery. The clinical results were evaluated using according to the American Orthopaedic Foot and Ankle Society ankle-hindfoot scale and the rate of infection. The follow-up duration for all patients ranged from 10 to 36 (mean 24) months. No statistically significant differences were found in the radiologic indicators, incidence of early postoperative complications, or American Orthopaedic Foot and Ankle Society ankle-hindfoot scores (p > .05) between the 2 groups. However, a statistically significant difference was seen in the duration of hospitalization (p < .05) between the 2 groups. A minimally invasive sinus tarsi approach with cannulated screw fixation combined with vacuum-assisted closure is an effective method for the treatment of severe open calcaneal fractures with medial wounds. It provides good reduction and requires fewer days of hospitalization. PMID:26372552

  15. The cause of 2S Diapason screw breakage after internal lumbar fixation: studies of the mechanical and material properties of the implant.

    PubMed

    Kolasa, P; Grabarczyk, J; Depczyk, T

    2002-08-30

    In the years 1994-99, unstable fractures of the lumbar spine were surgically treated with interbody fixation in the Department of Neurosurgery at the Nicholas Copernicus Voivodeship Specialized Hospital in ?ód?, using stabilizers manufactured by various companies. Complications in the form of stabilizer breakage were observed in 1 case out of 22. The aim of the present study was to ascertain the reason why the Stryker 2S Diapason screws broke. Tests performed to measure the material and mechanical properties of the implant did not show any signs of material fatigue, nor were any material defects discovered. However, a scanning microscope investigation confirmed the hypothesis that the material had crumbled due to overload. This discovery led to the decision that screws would be mounted in the bodies of the vertebrae in a manner decreasing implant load. PMID:17679886

  16. Anterior subcutaneous internal fixation for treatment of unstable pelvic fractures

    PubMed Central

    2014-01-01

    Background Fractures of the pelvic ring including disruption of the posterior elements in high-energy trauma have both high morbidity and mortality rates. For some injury pattern part of the initial resuscitation includes either external fixation or plate fixation to close the pelvic ring and decrease blood loss. In certain situations – especially when associated with abdominal trauma and the need to perform laparotomies – both techniques may put the patient at risk of either pintract or deep plate infections. We describe an operative approach to percutaneously close and stabilize the pelvic ring using spinal implants as an internal fixator and report the results in a small series of patients treated with this technique during the resuscitation phase. Findings Four patients were treated by subcutaneous placement of an internal fixator. Screw fixation was carried out by minimally invasive placement of two supra-acetabular iliac screws. Afterwards, a subcutaneous transfixation rod was inserted and attached to the screws after reduction of the pelvic ring. All patients were allowed to fully weight-bear. No losses of reduction or deep infections occurred. Fracture healing was uneventful in all cases. Conclusion Minimally invasive fixation is an alternative technique to stabilize the pelvic ring. The clinical results illustrate that this technique is able to achieve good results in terms of maintenance of reduction the pelvic ring. Also, abdominal surgeries no longer put the patient at risk of infected pins or plates. PMID:24606833

  17. Unilateral C1 Lateral Mass and C2 Pedicle Screw Fixation for Atlantoaxial Instability in Rheumatoid Arthritis Patients: Comparison with the Bilateral Method

    PubMed Central

    Paik, Seung-Chull; Bak, Koang Hum; Ryu, Jeil; Choi, Kyu-Sun

    2015-01-01

    Objective Bilateral C1 lateral mass and C2 pedicle screw fixation (C1LM-C2P) is an ideal technique for correcting atlantoaxial instability (AAI). However, the inevitable situation of vertebral artery injury or unfavorable bone structure may necessitate the use of unilateral C1LM-C2P. This study compares the fusion rates of the C1 lateral mass and C2 pedicle screw in the unilateral and bilateral methods. Methods Over five years, C1LM-C2P was performed in 25 patients with AAI in our institute. Preoperative studies including cervical X-ray, three-dimensional computed tomography (CT), CT angiogram, and magnetic resonance imaging were performed. To evaluate bony fusion, measurements of the atlanto-dental interval (ADI) and CT scans were performed in the preoperative period, immediate postoperative period, and postoperatively at 1, 3, 6, and 12 months. Results Unilateral C1LM-C2P was performed in 11 patients (44%). The need to perform unilateral C1LM-C2P was due to anomalous course of the vertebral artery in eight patients (73%) and severe degenerative arthritis in three patients (27%). The mean ADI in the bilateral group was 2.09 mm in the immediate postoperative period and 1.75 mm in 12-months postoperatively. The mean ADI in the unilateral group was 1.82 mm in the immediate postoperative period and 1.91 mm in 12-months postoperatively. Comparison of ADI measurements showed no significant differences in either group (p=0.893), and the fusion rate was 100% in both groups. Conclusion Although bilateral C1LM-C2P is effective for AAI from a biomechanical perspective, unilateral screw fixation is a useful alternative in patients with anatomical variations. PMID:26180616

  18. Bilateral C1–C2 Transarticular Screw and C1 Laminar Hook Fixation and Bone Graft Fusion for Reducible Atlantoaxial Dislocation: A Seven-Year Analysis of Outcome

    PubMed Central

    Guo, Xiang; Ni, Bin; Xie, Ning; Lu, Xuhua; Guo, Qunfeng; Lu, Ming

    2014-01-01

    Background Bilateral C1-2 transarticular screw and C1 laminar hook fixation was developed on the basis of transarticular screws fixation. The modified technique has showed a better biomechanical stability than established techniques in previous study. However, long-term (minimum follow-up 7 years) outcomes of patients with reducible atlantoaxial dislocation who underwent this modified fixation technique have not still been reported. Methods A retrospective study was conducted to evaluate the outcome of 36 patients who underwent this modified technique. Myelopathy was assessed using the Ranawat myelopathy score and Myelopathy Disability Index. Pain scores were assessed using Visual Analogue Scale. Radiological imaging was assessed and the following data were extracted: the atlantodental intervals, the space available for cord, presence of spinal cord signal change on T2 weighted image, C1–C2 angle, C2–C7 angle and fusion rates. Findings All patients achieved a minimum seven-year follow up. 95% patients with neck and suboccipital pain improved after surgery; in their Visual Analogue pain scores, there was a greater than 50% improvement in their VAS scores with a drop of 5 points on the VAS (P<0.05). 92% of patients improved in the Ranawat myelopathy grade; the Myelopathy Disability Index assessment showed a preoperative mean score of 35.62 with postoperative mean 12.75(P<0.05). There was not any significant atlantoaxial instability at each follow-up time. The space available for cord increased in all patients. Postoperative sagittal kyphosis of the subaxial spine was not observed. After six months after surgery, bone grafts of all patients were fused. No complications related to surgery were found in the period of follow-up. Conclusions The long-term outcomes of this case series demonstrate that under the condition of thorough preoperative preparations, bilateral C1–C2 transarticular screw and C1 laminar hook fixation and bone graft fusion is a reliable posterior atlantoaxial fusion technique for reducible atlantoaxial dislocation. PMID:24498163

  19. Theoretical assessment of an intramedullary condylar component versus screw fixation for the condylar component of a hemiarthroplasty alloplastic TMJ replacement system.

    PubMed

    Ramos, A; Mesnard, M; Relvas, C; Completo, A; Simões, J A

    2014-03-01

    Virtual design gives flexibility to explore constructive solutions or structures. It enables analysis that would often be impossible even if expensive real prototypes were available. Simulations using finite element models allow access to the stress and strain tensor or to the deformation tensor within an implant or a tissue which is impossible experimentally, even in vitro. This study is based on two numerical models of temporomandibular joint (TMJ) implants, comparing two bone-implant connections: an external connection performed with surgical screws (commercial model) and an internal connection carried out by penetration into the intramedullary space. The finite element models were constructed based on a cadaveric mandible and considering the five principal muscles in action. Strain distributions into the surrounding bone tissue are analysed and in both models they show significant differences at the external surface of the mandible in displacements. However, while the intramedullary fixation increases strains in the cancellous tissue, the study shows that strain distribution is mainly influenced by the number and distribution of screws in commercial solution. PMID:23684530

  20. Minimally Invasive Unilateral vs. Bilateral Pedicle Screw Fixation and Lumbar Interbody Fusion in Treatment of Multi-Segment Lumbar Degenerative Disorders

    PubMed Central

    Liu, Xiaoyang; Li, Guangrun; Wang, Jiefeng; Zhang, Heqing

    2015-01-01

    Background The choice for instrumentation with minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) in treatment of degenerative lumbar disorders (DLD) remains controversial. The goal of this study was to investigate clinical outcomes in consecutive patients with multi-segment DLD treated with unilateral pedicle screw (UPS) vs. bilateral pedicle screw (BPS) instrumented TLIF. Material/Methods Eighty-four consecutive patients who had multi-level MIS-TLIF were retrospectively reviewed. All data were collected to compare the clinical outcomes between the 2 groups. Results Both groups showed similar clinical function scores in VAS and ODI. The two groups differed significantly in operative time (P<0.001), blood loss (P<0.001), and fusion rate (P=0.043), respectively. Conclusions This study demonstrated similar clinical outcomes between UPS fixation and BPS procedure after MIS-TLIF for multi-level DLD. Moreover, UPS technique was superior in operative time and blood loss, but represented lower fusion rate than the BPS construct did. PMID:26603050

  1. Minimally Invasive Unilateral vs. Bilateral Pedicle Screw Fixation and Lumbar Interbody Fusion in Treatment of Multi-Segment Lumbar Degenerative Disorders.

    PubMed

    Liu, Xiaoyang; Li, Guangrun; Wang, Jiefeng; Zhang, Heqing

    2015-01-01

    BACKGROUND The choice for instrumentation with minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) in treatment of degenerative lumbar disorders (DLD) remains controversial. The goal of this study was to investigate clinical outcomes in consecutive patients with multi-segment DLD treated with unilateral pedicle screw (UPS) vs. bilateral pedicle screw (BPS) instrumented TLIF. MATERIAL AND METHODS Eighty-four consecutive patients who had multi-level MIS-TLIF were retrospectively reviewed. All data were collected to compare the clinical outcomes between the 2 groups. RESULTS Both groups showed similar clinical function scores in VAS and ODI. The two groups differed significantly in operative time (P<0.001), blood loss (P<0.001), and fusion rate (P=0.043), respectively. CONCLUSIONS This study demonstrated similar clinical outcomes between UPS fixation and BPS procedure after MIS-TLIF for multi-level DLD. Moreover, UPS technique was superior in operative time and blood loss, but represented lower fusion rate than the BPS construct did. PMID:26603050

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

    PubMed Central

    Peters, Todd; Hussain, Mir; Khalil, Saif

    2014-01-01

    Study Design An in-vitro study. Purpose 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). Overview of Literature The ideal treatment for thoracolumbar BF is controversial regarding the use of short or LPF constructs. Methods 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. Results 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. Conclusions 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. PMID:24596603

  3. One-stage partial vertebrectomy, titanium mesh implantation and pedicle screw fixation in the treatment of thoracolumbar burst fractures through a posterior approach

    PubMed Central

    Liu, Yueju; Li, Guangbin; Dong, Tianhua; Zhang, Yingze; Li, Heng

    2014-01-01

    OBJECTIVE: To analyze the clinical results of a partial vertebrectomy with titanium mesh implantation and pedicle screw fixation using a posterior approach to reconstruct the spine in the treatment of thoracolumbar burst fractures. METHOD: From January 2006 to August 2008, 20 patients with severe thoracolumbar fractures were treated.For vertebral bodies associated with one injured intervertebral disk, subtotal vertebrectomy surgery and single-segment fusion were performed. For vertebral bodies with two injured adjacent intervertebral disks, partial vertebrectomy surgery and two-segment fusion were performed. RESULTS: All 20 patients were followed up for 12 to 24 months (average of 18 months). There were no complications such as wound infections, hemopneumothorax or abdominal infections in any of the patients. The neurological status of all of the patients was improved by at least one American Spinal Injury Association grade by the last follow-up. The anterior vertebral body height was an average of 50.77% before surgery, 88.51% after surgery and 87.86% at the last follow up; the sagittal Cobb angle was improved, on average, from 26.15° to 5.39° and was 5.90° at the last follow up. The percentage of spinal stenosis was improved, on average, from 26.07% to 4.93%° and was 6.15% at the last follow up. There were significant differences in the anterior vertebral body height pre- and post-surgery and in the sagittal Cobb angle and the percentage of spinal stenosis (p<0) in all patients. CONCLUSIONS: This surgical procedure is simple and can accomplish decompression, reduction, fixation and fusion of the spine in one stage. This approach could be widely used in orthopedics. PMID:25627991

  4. 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. PMID:23982115

  5. Fixation using alternative implants for the treatment of hip fractures (FAITH): design and rationale for a multi-centre randomized trial comparing sliding hip screws and cancellous screws on revision surgery rates and quality of life in the treatment of femoral neck fractures

    PubMed Central

    2014-01-01

    Background Hip fractures are a common type of fragility fracture that afflict 293,000 Americans (over 5,000 per week) and 35,000 Canadians (over 670 per week) annually. Despite the large population impact the optimal fixation technique for low energy femoral neck fractures remains controversial. The primary objective of the FAITH study is to assess the impact of cancellous screw fixation versus sliding hip screws on rates of revision surgery at 24 months in individuals with femoral neck fractures. The secondary objective is to determine the impact on health-related quality of life, functional outcomes, health state utilities, fracture healing, mortality and fracture-related adverse events. Methods/Design FAITH is a multi-centre, multi-national randomized controlled trial utilizing minimization to determine patient allocation. Surgeons in North America, Europe, Australia, and Asia will recruit a total of at least 1,000 patients with low-energy femoral neck fractures. Using central randomization, patients will be allocated to receive surgical treatment with cancellous screws or a sliding hip screw. Patient outcomes will be assessed at one week (baseline), 10 weeks, 6, 12, 18, and 24 months post initial fixation. We will independently adjudicate revision surgery and complications within 24 months of the initial fixation. Outcome analysis will be performed using a Cox proportional hazards model and likelihood ratio test. Discussion This study represents major international efforts to definitively resolve the treatment of low-energy femoral neck fractures. This trial will not only change current Orthopaedic practice, but will also set a benchmark for the conduct of future Orthopaedic trials. Trial registration The FAITH trial is registered at ClinicalTrials.gov (Identifier NCT00761813). PMID:24965132

  6. Removal of broken pedicle screws. Technical note.

    PubMed

    Miyamoto, K; Shimizu, K; Kouda, K; Hosoe, H

    2001-07-01

    The authors describe a simple, new method for removing broken pedicle screws. Under microscopic visualization a straight, narrow slot is etched in the broken surface of the pedicle screw by using a power drill with a 2-mm diamond burr. A minus screwdriver is then inserted into the slot, and the broken screw is rotated and removed. There is no need to enlarge the screw hole around the broken screw or to use any special devices. The authors succeeded in removing broken screws in two cases, and there were no complications. This method allows preservation of both the pedicle and the screw hole. Consequently, it is possible to insert new pedicle screws into the same hole without losing the strength and stability of pedicle screw fixation. The authors recommend this simple and new method for removal of broken pedicle screws. PMID:11453420

  7. Direct repair of defects in lumbar spondylolysis with a new pedicle screw hook fixation: clinical, functional and Ct-assessed study

    PubMed Central

    Troussel, Serge

    2007-01-01

    Spondylolysis is a common entity, a minority of people affected by this disease need medical care, and only a few require surgery. Reconstruction of the pars interarticularis is an interesting alternative to segmental fusion; this technique has the advantage of preserving segmental motion. Most authors report good results for young patients without intervertebral disk or facet degenerative changes. Moreover Louis also showed good to excellent results with his technique carried out among people who presented a satisfactory disk height (equal to two thirds of normal height). This could extend the number of patients for whom pars interarticularis repair could be proposed. In this study, the limit of reconstruction was set at grade 3of the Pfirrmann’s classification. The fixation of the isthmus was done with a new kind of pedicle screw hook system. This stable and strong device is easy to use, allows an anatomic pars interarticularis reconstruction of spondylolysis and avoids a postoperative bracing. Twenty-three patients were assessed in this study, the mean age at operation was 34 (range 16–52 years) and the average follow-up was for 59 months (range 6–113 months). Eight patients showed moderate degenerative disk disease before the surgery and 12 patients had a grade 1 spondylolisthesis. The visual analogical scale, the Oswestry disability index (ODI) and the modified Prolo score were used for assessment of pain and clinical outcome before and after surgery. The results were from “excellent” to “good” for twenty patients (87%) and “fair” for three of them (13%). The consolidation of the isthmus was assessed at the end of the study (CT-scan); the fusion rate was observed in 91%. Among patients aged less than 30 years results are from “good”, to “excellent” in all cases and consolidation was always observed. All of them showed normal disc signal before the surgery. In the group aged more than 30 years, the results varied from “good” to “excellent’ in 73% and fusion of the defect was discovered in 82% of cases. Eight of them (73%) had moderate disk signal modification before the surgery. All people with fair results displayed moderate disk degeneration signs at MRI before surgery; but two of those three patients had a failure of defect consolidation too and it is also associated with poor results by several authors. No complication was found in this series. According to the good results reported by Louis and upto the current finding, the authors believe that pars interarticularis repair can be carried out on patients with moderate degenerative disk disease; the stage 3 of Pfirrmann’s classification seems a good limit. The Bone and joint research (B.J.R. system) is readily usable by any surgeon using pedicle screw systems and having a short learning curve. No device failure has been observed in this series. PMID:17520298

  8. Screw Press 

    E-print Network

    Unknown

    2011-08-17

    that sorghum meal extruded at low feed moisture and high screw speeds developed high expansion and resulted in sorghum extrudates with low bulk densities. They concluded that sorghum could be used in blends with other cereals and/or legumes to produce snacks... variables such as mass flow, water injection, barrel temperature, screw configuration, screw speed, feed rate, and feed material affect physical properties of extrudates (Ryu and Ng 2001). In addition, physical features of raw materials...

  9. Total hip arthroplasty with acetabular fixation: an unexpected complication.

    PubMed

    Khoriati, Al-Achraf

    2014-04-01

    The incidence of vascular injuries associated with total hip arthroplasty (THA) is low. However, several vascular structures are at risk of injury within the pelvis. These include the external iliac, femoral, and obturator vessels. Both reaming of the acetabulum and drilling of the acetabular screw holes may place these structures at risk. If left untreated, injuries to these vessels may be associated with severe morbidity and mortality. In this report, an acute vascular complication that had an unusual presentation is highlighted. A 72-year-old woman presented to the emergency department following a road traffic accident in which she sustained a combined fracture of the right acetabulum and femoral head. Her treatment involved a combination of THA and pelvic open reduction and internal fixation. The immediate perioperative recovery period was uncomplicated. However, the patient developed a deep venous thrombus in her right calf 7 days after surgery. Further investigation revealed a second thrombus, occluding the right common femoral vein. Surgical exploration revealed that a screw placed during the initial surgery was pressing against the vessel and occluding it. The discrepancy in incidence between the development of deep venous thrombosis and vascular compression or injury means that the association between the 2 events is unlikely to be made. The author highlights this unusual presentation to improve early recognition and prompt management of similar cases. The importance of adequate preoperative planning and intraoperative imaging with a C-arm is also stressed. PMID:24762850

  10. Iliac Crest Herniation Secondary to Autogenous Bone Grafting Found on Osteopathic Examination.

    PubMed

    Ou, Christine J; Sternfeld, William C; Stausmire, Julie M

    2015-08-01

    Surgical repair of difficult or nonunion fractures is frequently performed with autogenous bone grafts, most commonly from the iliac crest. Complications from this procedure may include vessel injury, nerve injury, pelvic instability, bowel herniation, and ileus. The authors report a case of iliac crest herniation in a patient presenting with a small-bowel obstruction 2 years after anterior iliac crest graft harvest for an open reduction and internal fixation repair of a right humeral shaft fracture. An emergency operation revealed that the right colon had herniated through an opening in the right iliac crest. The appendix had adhered to new osseous bone formed postoperatively, requiring an appendectomy. The hernia defect was successfully repaired with polypropylene mesh. A high index of suspicion for graft site herniation is needed for patients with a history of iliac crest bone grafting who present with symptoms of abdominal pain, flank or hip pain, ileus, or small-bowel obstruction. PMID:26214826

  11. Predicting cancellous bone failure during screw insertion.

    PubMed

    Reynolds, Karen J; Cleek, Tammy M; Mohtar, Aaron A; Hearn, Trevor C

    2013-04-01

    Internal fixation of fractures often requires the tightening of bone screws to stabilise fragments. Inadequate application of torque can leave the fracture unstable, while over-tightening results in the stripping of the thread and loss of fixation. The optimal amount of screw torque is specific to each application and in practice is difficult to attain due to the wide variability in bone properties including bone density. The aim of the research presented in this paper is to investigate the relationships between motor torque and screw compression during powered screw insertion, and to evaluate whether the torque during insertion can be used to predict the ultimate failure torque of the bone. A custom test rig was designed and built for bone screw experiments. By inserting cancellous bone screws into synthetic, ovine and human bone specimens, it was established that variations related to bone density could be automatically detected through the effects of the bone on the rotational characteristics of the screw. The torque measured during screw insertion was found to be directly related to bone density and can be used, on its own, as a good predictor of ultimate failure torque of the bone. PMID:23466167

  12. Loosening torque of Universal Abutment screws after cyclic loading: influence of tightening technique and screw coating

    PubMed Central

    Regalin, Alexandre; Bhering, Claudia Lopes Brilhante; Alessandretti, Rodrigo; Spazzin, Aloisio Oro

    2015-01-01

    PURPOSE The purpose of this study was to evaluate the influence of tightening technique and the screw coating on the loosening torque of screws used for Universal Abutment fixation after cyclic loading. MATERIALS AND METHODS Forty implants (Titamax Ti Cortical, HE, Neodent) (n=10) were submerged in acrylic resin and four tightening techniques for Universal Abutment fixation were evaluated: A - torque with 32 Ncm (control); B - torque with 32 Ncm holding the torque meter for 20 seconds; C - torque with 32 Ncm and retorque after 10 minutes; D - torque (32 Ncm) holding the torque meter for 20 seconds and retorque after 10 minutes as initially. Samples were divided into subgroups according to the screw used: conventional titanium screw or diamond like carbon-coated (DLC) screw. Metallic crowns were fabricated for each abutment. Samples were submitted to cyclic loading at 106 cycles and 130 N of force. Data were analyzed by two-way ANOVA and Tukey's test (5%). RESULTS The tightening technique did not show significant influence on the loosening torque of screws (P=.509). Conventional titanium screws showed significant higher loosening torque values than DLC (P=.000). CONCLUSION The use of conventional titanium screw is more important than the tightening techniques employed in this study to provide long-term stability to Universal Abutment screws. PMID:26576253

  13. Osteotomy of the Anterior Superior Iliac Spine as an Adjunct to Improve Access and Visualization Through the Lateral Window.

    PubMed

    Sagi, H Claude; Bolhofner, Brett

    2015-08-01

    The lateral "window" has previously been described as part of the ilioinguinal and anterior intrapelvic approaches for gaining access to the anterior aspect of the sacroiliac joint, the internal iliac fossa, and upper portion of the anterior column for reduction and placement of fixation. Surgical exposure of this window typically involves release of the external oblique muscle from the iliac crest and elevation of the iliacus muscle from the internal iliac fossa. This exposure is limited by the residual attachment of the external oblique muscle and inguinal ligament to the anterior superior iliac spine, particularly in patients with a large abdomen or in fractures that involve the anterior wall of the acetabulum and pubic root region. Herein, we describe the addition of an osteotomy of the anterior superior iliac spine for improved medial mobilization of the abdominal wall musculature to allow better visualization and access to the internal iliac fossa and anterior aspect of the sacroiliac joint. PMID:25932529

  14. Spontaneous Iliac Vein Rupture

    PubMed Central

    Kim, Dae Hwan; Park, Hyung Sub; Lee, Taeseung

    2015-01-01

    Spontaneous iliac vein rupture (SIVR) is a rare entity, which usually occurs without a precipitating factor, but can be a life-threatening emergency often requiring an emergency operation. This is a case report of SIVR in a 62-year-old female who presented to the emergency room with left leg swelling. Workup with contrast-enhanced computed tomography revealed a left leg deep vein thrombosis with May-Thurner syndrome and a hematoma in the pelvic cavity without definite evidence of arterial bleeding. She was managed conservatively without surgical intervention, and also underwent inferior vena cava filter insertion and subsequent anticoagulation therapy for pulmonary thromboembolism. This case shows that SIVR can be successfully managed with close monitoring and conservative management, and anticoagulation may be safely applied despite the patient presenting with venous bleeding. PMID:26217647

  15. Solid and hollow pedicle screws affect the electrical resistance: A potential source of error with stimulus-evoked electromyography

    PubMed Central

    Wang, Hongwei; Liao, Xinhua; Ma, Xianguang; Li, Changqing; Han, Jianda; Zhou, Yue

    2013-01-01

    Background: Although stimulus evoked electromyography (EMG) is commonly used to confirm the accuracy of pedicle screw placement. There are no studies to differentiate between solid screws and hollow screws to the electrical resistance of pedicle screws. We speculate that the electrical resistance of the solid and hollow pedicle screws may be different and then a potential source of error with stimulus-evoked EMG may happen. Materials and Methods: Resistance measurements were obtained from 12 pedicle screw varieties (6 screws of each manufacturer) across the screw shank based on known constant current and measured voltage. The voltage was measured 5 times at each site. Results: Resistance of all solid screws ranged from 0.084 ? to 0.151 ? (mean =0.118 ± 0.024 ?) and hollow screws ranged from 0.148 ? to 0.402 ? (mean = 0.285 ± 0.081 ?). There was a significant difference of resistance between the solid screws and hollow screws (P < 0.05). The screw with the largest diameter no matter solid screws or hollow screws had lower resistance than screws with other diameters. No matter in solid screws group or hollow screws group, there were significant differences (P < 0.05) between the 5.0 mm screws and 6.0 mm screws, 6.0 mm screws and 7.0 mm screws, 5.0 mm screws and 7.0 mm screws, 4.5 mm screws and 5.5 mm screws, 5.5 mm screws and 6.5 mm screws, 4.5 mm screws and 6.5 mm screws. The resistance of hollow screws was much larger than the solid screws in the same diameter group (P < 0.05). Conclusions: Hollow pedicle screws have the potential for high electrical resistance compared to the solid pedicle screws and therefore may affect the EMG response during stimulus-evoked EMG testing in pedicle screw fixation especially in minimally invasive percutaneous pedical screw fixation surgery. PMID:23960278

  16. Comparison of the pull-out forces of bioabsorbable polylactide/glycolide screws (Biosorb and Lactosorb) and tacks: a study on the stability of fixation in human cadaver parietal bones.

    PubMed

    Tiainen, Johanna; Leinonen, Sanna; Ilomäki, Jouko; Suokas, Esa; Törmälä, Pertti; Waris, Timo; Ashammakhi, Nureddin

    2002-07-01

    The aim of this study was to compare the pull-out forces of bioabsorbable polylactide/glycolide (PLGA) tacks and screws in human cadaver parietal bones. Parietal bone pieces (c. 6 cm x 20 cm) were collected from five human male cadavers (age range: 47-75 years). Forty-nine BioSorbPDX (self-reinforced [SR] PLGA 80/20) tacks (1.5-mm diameter, 4.0-mm length), 47 BioSorbPDX (SR-PLGA 80/20) screws (1.5-mm diameter, 4.0-mm length), and 46 LactoSorb (PLGA 82/18) screws (1.5-mm diameter, 4.0-mm length) were applied. The tacks were applied to drill holes using a special applicator gun (no tapping or tightening). The screws were applied to drill holes in the traditional way using tapping and tightening with a screwdriver. A tensile testing machine was used. All the implants were tested thus: the head of the implant was held by an aluminum jig, and the jig was pulled with wire until implant failure. The testing pull speed was 10 mm/min. Means and SDs were calculated, and the data were analyzed using ANOVA. The pull-out force of the tacks was 115.9 +/- 8.3 N, that of Lactosorb screws was 112.9 +/- 12.1 N, and that of Biosorb screws was 110.4 +/- 8.9 N (statistically insignificant difference between the three groups). The most common reason for failure in the case of tacks was barb breakage (55.1%); it was thread breakage in the case of BioSorb screws (66%) and stem split in the case of Lactosorb screws (56%). Tacks seem to have a similar, perhaps even a little better, holding power to cranial bone as screws and can hence be recommended for clinical application, as the procedure saves time and, consequently, costs. PMID:12140419

  17. Surgical screw segmentation for mobile C-arm CT devices

    NASA Astrophysics Data System (ADS)

    Görres, Joseph; Brehler, Michael; Franke, Jochen; Wolf, Ivo; Vetter, Sven Y.; Grützner, Paul A.; Meinzer, Hans-Peter; Nabers, Diana

    2014-03-01

    Calcaneal fractures are commonly treated by open reduction and internal fixation. An anatomical reconstruction of involved joints is mandatory to prevent cartilage damage and premature arthritis. In order to avoid intraarticular screw placements, the use of mobile C-arm CT devices is required. However, for analyzing the screw placement in detail, a time-consuming human-computer interaction is necessary to navigate through 3D images and therefore to view a single screw in detail. Established interaction procedures of repeatedly positioning and rotating sectional planes are inconvenient and impede the intraoperative assessment of the screw positioning. To simplify the interaction with 3D images, we propose an automatic screw segmentation that allows for an immediate selection of relevant sectional planes. Our algorithm consists of three major steps. At first, cylindrical characteristics are determined from local gradient structures with the help of RANSAC. In a second step, a DBScan clustering algorithm is applied to group similar cylinder characteristics. Each detected cluster represents a screw, whose determined location is then refined by a cylinder-to-image registration in a third step. Our evaluation with 309 screws in 50 images shows robust and precise results. The algorithm detected 98% (303) of the screws correctly. Thirteen clusters led to falsely identified screws. The mean distance error for the screw tip was 0.8 +/- 0.8 mm and for the screw head 1.2 +/- 1 mm. The mean orientation error was 1.4 +/- 1.2 degrees.

  18. 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

  19. Bioabsorbable expansion bolt fixation in anterior cruciate ligament reconstruction.

    PubMed

    Piltz, S; Steinbauer, T; Meyer, L; Plitz, W; Andress, H J; Lob, G

    2004-01-01

    The current study evaluated initial fixation strength of a bioabsorbable expansion bolt compared with interference screw fixation in anterior cruciate ligament reconstruction using a bone-patellar tendon-bone graft. Thirty calf tibial plateaus with adjacent patella and extensor ligaments were used. Bioabsorbable poly-L-lactide interference screws were used for graft fixation in Group I, titanium screws in Group II, and bioabsorbable poly-DL-lactide expansion bolts were used in Group III. The mean force-to-failure (+/- standard deviation) in the three groups was 487 +/- 205 N, 713 +/- 218 N, and 594 +/- 224 N, respectively. The differences between Groups I and II were significant. No statistical differences were found regarding stiffness. Graft damage was significantly less in Group III compared with screw fixation. The fixation concept of an expansion bolt shows similar fixation strength and less graft damage compared with the established interference screw fixation. Because of the total absence of torque forces in contrast to bioabsorbable screws, the risk of implant breakage is minimized. PMID:15043122

  20. Pedicle screw placement in the lumbar spine: effect of trajectory and screw design on acute biomechanical purchase.

    PubMed

    Wray, Steven; Mimran, Ronnie; Vadapalli, Sasidhar; Shetye, Snehal S; McGilvray, Kirk C; Puttlitz, Christian M

    2015-05-01

    OBJECT Low bone mineral density in patients undergoing lumbar spinal surgery with screws is an especially difficult challenge because poor bone quality can severely compromise the maximum achievable purchase of the screws. A relatively new technique, the cortical bone screw trajectory, utilizes a medialized trajectory in the caudocephalad direction to engage a greater amount of cortical bone within the pars interarticularis and pedicle. The objectives of this cadaveric biomechanical study were to 1) evaluate a cortical screw system and compare its mechanical performance to the traditional pedicle screw system; 2) determine differences in bone quality associated with the cortical screw trajectory versus the normal pedicle screw insertion technique; 3) determine the cortical wall breach rate with both the cortical and traditional screw trajectories; and 4) determine the performance of the traditional screw in the cortical screw trajectory. METHODS Fourteen fresh frozen human lumbar spine sections (L1-5) were used in this study (mean age 57 ± 19 years). The experimental plan involved drilling and tapping screw holes for 2 trajectories under navigation (a traditional pedicle screw and a cortical screw) in both high-and low-quality vertebrae, measuring the bone quality associated with these trajectories, placing screws in the trajectories, and evaluating the competence of the screw purchase via 2 mechanical tests (pullout and toggle). The 3 experimental variants were 1) traditional pedicle screws placed in the traditional pedicle screw trajectory, 2) traditional pedicle screws placed in the cortical screw trajectory, and 3) cortical screws placed in the cortical screw trajectory. RESULTS A statistically significant increase in bone quality was observed for the cortical trajectories with a cortical screw (42%; p < 0.001) and traditional pedicle screw (48%; p < 0.001) when compared to the traditional trajectory with a traditional pedicle screw within the high-quality bone group. These significant differences were also found in the lowquality bone cohort. All mechanical parameter comparisons (screw type and trajectory) between high-quality and lowquality samples were significant (p < 0.01), and these data were all linearly correlated (r ? 0.65) to bone mineral density. Not all mechanical parameters determined from pullout and toggle testing were statistically significant between the 3 screw/trajectory combinations. The incidence of cortical wall breach with the cortical or traditional pedicle screw trajectories was not significantly different. CONCLUSIONS The data demonstrated that the cortical trajectory provides denser bone that allows for utilization of smaller screws to obtain mechanical purchase that is equivalent to long pedicle screws placed in traditional pedicle screw trajectories for both normal- and low-quality bone. Overall, this biomechanical study in cadavers provides evidence that the cortical screw trajectory represents a good option to obtain fixation for the lumbar spine with low-quality bone. PMID:25679236

  1. Role of the compression screw in the dynamic hip-screw system: A finite-element study.

    PubMed

    Chang, Chih-Wei; Chen, Yen-Nien; Li, Chun-Ting; Peng, Yao-Te; Chang, Chih-Han

    2015-12-01

    The dynamic hip-screw (DHS) system is a common implant for fixation of proximal femur fractures. During assembly, it has been recommended to remove the compression screw after initial compression has been obtained; however, related complications had been reported. So far, the role of compression screw in the reconstructed stability of hip fractures as well as the mechanical strength of the DHS system has rarely been mentioned. This study investigated the function of this screw in the DHS system during fracture healing. Based on the FE method, six numerical models of proximal femur were employed to analyze the mechanical response of a DHS implant with various fracture types and different fixation strategies (with or without a compression screw). The displacement of the femur head and peak von Mises stress were selected as indices of the stability of a fractured femur stabilized by a DHS device and of the risk of implant failure, respectively. Our results showed that a retained compression screw increased reconstructed structural stiffness, reducing the displacement of the femur head. This screw also helped to lessen mechanical failure of side plate by reducing the peak von Mises stress around the connection between the barrel and side plate. Both findings were evident in the proximal femur fracture involving the intertrochanteric part, and even more obvious in the setting of bony defects. Thus, we recommend the maintenance of compression screw in the DHS system while treating the intertrochanteric fracture, particularly in cases with bony defects. PMID:26521645

  2. Pullout performance comparison of pedicle screws based on cement application and design parameters.

    PubMed

    Tolunay, Tolga; Ba?gül, Cemile; Demir, Teyfik; Yaman, Mesut E; Arslan, Arslan K

    2015-11-01

    Pedicle screws are the main fixation devices for certain surgeries. Pedicle screw loosening is a common problem especially for osteoporotic incidents. Cannulated screws with cement augmentation are widely used for that kind of cases. Dual lead dual cored pedicle screw has already given promising pullout values without augmentation. This study concentrates on the usage of dual lead dual core with cement augmentation as an alternative to cannulated and standard pedicle screws with cement augmentation. Five groups (dual lead dual core, normal pedicle screw and cannulated pedicle screw with augmentation, normal pedicle screw, dual lead dual cored pedicle screw) were designed for this study. Healthy bovine vertebrae and synthetic polyurethane foams (grade 20) were used as embedding test medium. Test samples were prepared in accordance with surgical guidelines and ASTM F543 standard testing protocols. Pullout tests were conducted with Instron 3300 testing frame. Load versus displacement values were recorded and maximum pullout loads were stated. The dual lead dual cored pedicle screw with poly-methyl methacrylate augmentation exhibited the highest pullout values, while dual lead dual cored pedicle screw demonstrated similar pullout strength as cannulated pedicle screw and normal pedicle screw with poly-methyl methacrylate augmentation. The dual lead dual cored pedicle screw with poly-methyl methacrylate augmentation can be used for osteoporotic and/or severe osteoporotic patients according to its promising results on animal cadaver and synthetic foams. PMID:26503840

  3. Treatment of fractures of the condylar head with resorbable pins or titanium screws: an experimental study.

    PubMed

    Schneider, Matthias; Loukota, Richard; Kuchta, Anne; Stadlinger, Bernd; Jung, Roland; Speckl, Katrin; Schmiedekampf, Robert; Eckelt, Uwe

    2013-07-01

    We aimed to compare in vivo the stability of fixation of condylar fractures in sheep using sonic bone welding and standard titanium screws. We assessed stability of the osteosynthesis and maintenance of the height of the mandibular ramus. Height decreased slightly in both groups compared with the opposite side. The volume of the condyle increased considerably in both groups mainly because callus had formed. The results showed no significant disadvantages for pin fixation compared with osteosynthesis using titanium screws. PMID:22901526

  4. Lateral Mass Fixation in the Subaxial Cervical Spine.

    PubMed

    Kurd, Mark F; Millhouse, Paul W; Schroeder, Gregory D; Kepler, Christopher K; Vaccaro, Alexander R

    2015-08-01

    The use of lateral mass screws and rods in the subaxial spine has become the standard method of fixation for posterior cervical spine fusions. Multiple techniques have been described for the placement of lateral mass screws, including the Magerl, the Anderson, and the An techniques. While these techniques are all slightly different, the overall goal is to obtain solid bony fixation while avoiding the neurovascular structures. The use of lateral mass screws has been shown to be a safe and effective technique for achieving a posterior cervical fusion. PMID:26049972

  5. A Biomechanical Comparison of Three Different Posterior Fixation Constructs Used for C6–C7 Cervical Spine Immobilization: A Finite Element Study

    PubMed Central

    HONG, Jae Taek; QASIM, Muhammad; ESPINOZA ORÍAS, Alejandro A.; NATARAJAN, Raghu N.; AN, Howard S.

    2014-01-01

    The intralaminar screw construct has been recently introduced in C6–C7 fixation. The aim of the study is to compare the stability afforded by three different C7 posterior fixation techniques using a three-dimensional finite element model of a C6–C7 cervical spine motion segment. Finite element models representing three different cervical anchor types (C7 intralaminar screw, C7 lateral mass screw, and C7 pedicle screw) were developed. Range of motion (ROM) and maximum von Mises stresses in the vertebra for the three screw techniques were compared under pure moments in flexion, extension, lateral bending, and axial rotation. ROM for pedicle screw construct was less than the lateral mass screw construct and intralaminar screw construct in the three principal directions. The maximum von Misses stress was observed in the C7 vertebra around the pedicle in all the three screw constructs. Maximum von Mises stress in pedicle screw construct was less than the lateral mass screw construct and intralaminar screw construct in all loading modes. This study demonstrated that the pedicle screw fixation is the strongest instrumentation method for C6–C7 fixation. Pedicle screw fixation resulted in least stresses around the C7 pedicle-vertebral body complex. However, if pedicle fixation is not favorable, the laminar screw can be a better option compared to the lateral mass screw because the stress around the pedicle-vertebral body complex and ROM predicted for laminar screw construct was smaller than those of lateral mass screw construct. PMID:24418790

  6. Computer-assisted screw insertion for cervical disorders in rheumatoid arthritis

    PubMed Central

    Shono, Yasuhiro; Nakamura, Isao; Hirabayashi, Hiroki; Kamimura, Mikio; Ebara, Sohei; Kato, Hiroyuki

    2006-01-01

    To reconstruct highly destructed unstable rheumatoid arthritis (RA) cervical lesions, the authors have been using C1/2 transarticular and cervical pedicle screw fixations. Pedicle screw fixation and C1/2 transarticular screw fixation are biomechanically superior to other fixation techniques for RA patients. However, due to severe spinal deformity and small anatomical size of the vertebra, including the lateral mass and pedicle, in the most RA cervical lesions, these screw fixation procedures are technically demanding and pose the potential risk of neurovascular injuries. The purpose of this study was to evaluate the accuracy and safety of cervical pedicle screw insertion to the deformed, fragile, and small RA spine lesions using computer-assisted image-guidance systems. A frameless, stereotactic image-guidance system that is CT-based, and optoelectronic was used for correct screw placement. A total of 21 patients (16 females, 5 males) with cervical disorders due to RA were surgically treated using the image-guidance system. Postoperative computerized tomography and plane X-ray was used to determine the accuracy of the screw placement. Neural and vascular complications associated with screw insertion and postoperative neural recovery were evaluated. Postoperative radiological evaluations revealed that only 1 (2.1%; C4) of 48 screws inserted into the cervical pedicle had perforated the vertebral artery canal more than 25% (critical breach). However, no neurovascular complications were observed. According to Ranawat’s classification, 9 patients remained the same, and 12 patients showed improvement. Instrumentation failure, loss of reduction, or nonunion was not observed at the final follow-up (average 49.5 months; range 24–96 months). In this study, the authors demonstrated that image-guidance systems could be applied safely to the cervical lesions caused by RA. Image-guidance systems are useful tools in preoperative planning and in transarticular or transpedicular screw placement in the cervical spine of RA patients. PMID:17024400

  7. A Biomechanical Comparison of Three 1.5-mm Plate and Screw Configurations and a Single 2.0-mm Plate for Internal Fixation of a Mandibular Condylar Fracture

    PubMed Central

    Aquilina, Peter; Parr, William C.H.; Chamoli, Uphar; Wroe, Stephen; Clausen, Philip

    2014-01-01

    The most stable pattern of internal fixation for mandibular condyle fractures is an area of ongoing discussion. This study investigates the stability of three patterns of plate fixation using readily available, commercially pure titanium implants. Finite element models of a simulated mandibular condyle fracture were constructed. The completed models were heterogeneous in bone material properties, contained approximately 1.2 million elements and incorporated simulated jaw adducting musculature. Models were run assuming linear elasticity and isotropic material properties for bone. No human subjects were involved in this investigation. The stability of the simulated condylar fracture reduced with the different implant configurations, and the von Mises stresses of a 1.5-mm X-shaped plate, a 1.5-mm rectangular plate, and a 1.5-mm square plate (all Synthes (Synthes GmbH, Zuchwil, Switzerland) were compared. The 1.5-mm X plate was the most stable of the three 1.5-mm profile plate configurations examined and had comparable mechanical performance to a single 2.0-mm straight four-hole plate. This study does not support the use of rectangular or square plate patterns in the open reduction and internal fixation of mandibular condyle fractures. It does provide some support for the use of a 1.5-mm X plate to reduce condylar fractures in selected clinical cases. PMID:25136411

  8. Stability of unicortical locked fixation versus bicortical non-locked fixation for forearm fractures.

    PubMed

    Pater, Timothy J; Grindel, Steve I; Schmeling, Gregory J; Wang, Mei

    2014-01-01

    Locking plate fixation is being widely applied for fixation of forearm fractures and has many potential advantages, such as fixed angle fixation and improved construct stability, especially in osteoporotic bone. Biomechanical data comparing locking devices to commonly used Low Contact Dynamic Compression (LCDCP) plates for the fixation of forearm fractures has been lacking. The purpose of this study was to compare the fixation stability of a 3.5-mm unicortical locked plate with bicortical non-locked LCDCP plates. Six matched pairs of fresh frozen cadaveric forearms were randomly assigned to unicortical locked and bicortical unlocked groups. Non-destructive four-point bending and torsional test was performed on the ulna and radius separately, using a servohydraulic testing system to obtain construct stiffness of the intact specimens and specimens after osteotomy and plating. The specimens were then loaded to failure to test the fixation strength. The locked unicortical fixation showed significantly higher bending stiffness than the unlocked bicortical fixation, but with significantly lower stiffness and strength in torsion. Fixation strength was comparable between the two groups under bending, but significantly greater in the bicortical non-locked group under torsion. Findings from this study suggest that postoperative rehabilitation protocols may need modification to limit torsional loading in the early stage when using locked unicortical fixation. The study also points out the potential advantage of a hybrid fixation that combines locked unicortical and unlocked bicortical screws. PMID:26273524

  9. Iliac Artery Stent Placement Relieves Claudication in Patients with Iliac and Superficial Femoral Artery Lesions

    SciTech Connect

    Ichihashi, Shigeo Higashiura, Wataru; Itoh, Hirofumi; Sakaguchi, Shoji; Kichikawa, Kimihiko

    2013-06-15

    Purpose. To evaluate the efficacy of iliac artery stent placement for relief of claudication in patients with both iliac and superficial femoral artery (SFA) lesions. Methods. Stent placement for only iliac artery occlusive disease was performed in 94 limbs (74 patients) with both iliac and SFA occlusive disease on the same limb. All procedures were performed because intermittent claudication did not improve after continuation of antiplatelet medication therapy and home-based exercise for 3 months. Rutherford classification was 2 in 20 limbs and 3 in 74 limbs. Patients with critical limb ischemia were excluded. Median duration of follow-up was 40 months. Primary patency rates of the iliac stent, clinical improvement rates, and risk factors for requiring additional SFA procedures were evaluated. Results. Primary patency rates of the iliac stent at 1, 3, 5, and 7 years were 97, 93, 79, and 79 %, respectively. The initial clinical improvement rate was 87 %. Continued clinical improvement rates at 1, 3, 5, and 7 years were 87, 81, 69, and 66 %, respectively. SFA Trans-Atlantic Inter-Society Consensus (TASC) II C/D lesion was a significant risk factor for requiring additional SFA procedures. Conclusion. Intermittent claudication was relieved by iliac stent placement in most patients with both iliac and SFA lesions. Thus, the indications for treatment of the SFA intended for claudicants should be evaluated after treatment of the iliac lesion.

  10. Biomechanical testing of implant free wedge shaped bone block fixation for bone patellar tendon bone anterior cruciate ligament reconstruction in a bovine model

    PubMed Central

    2010-01-01

    Background The use of an interference fit wedged bone plug to provide fixation in the tibial tunnel when using bone-patellar tendon-bone autograft for anterior cruciate ligament reconstruction offers many theoretic advantages including the potential to offer a more economical and biological alternative to screw fixation. This technique has not been subjected to biomechanical testing. We hypothesised that a wedged bone plug fixation technique provides equivalent tensile load to failure as titanium interference screw fixation. Methods In a controlled laboratory setting, anterior cruciate ligament reconstruction was performed in 36 bovine knees using bone-patella-bone autograft. In 20 knees tibial fixation relied upon a standard cuboid bone block and interference screw. In eight knees a wedge shaped bone block with an 11 mm by 10 mm base without a screw was used. In a further eight knees a similar wedge with a 13 mm by 10 mm base was used. Each specimen used a standard 10 mm tibial tunnel. The reconstructions were tested biomechanically in a physiological environment using an Instron machine to compare ultimate failure loads and modes of failure. Results Statistical analysis revealed no significant difference between wedge fixation and screw fixation (p = 0.16), or between individual groups (interference screw versus 11 mm versus 13 mm wedge fixation) (P = 0.35). Conclusions Tibial tunnel fixation using an impacted wedge shaped bone block in anterior cruciate ligament reconstruction has comparable ultimate tensile strength to titanium interference screw fixation. PMID:20813059

  11. Cortical Bone Trajectory for Lumbar Pedicle Screw Placement: A Review of Published Reports.

    PubMed

    Phan, Kevin; Hogan, Jarred; Maharaj, Monish; Mobbs, Ralph J

    2015-08-01

    There have been a number of developments in screw design and implantation techniques over recent years, including proposal of an alternative trajectory for screw fixation aimed at increasing purchase of pedicle screws in higher density bone. Cortical bone trajectory (CBT) screw insertion follows a lateral path in the transverse plane and caudocephalad path in the sagittal plane. This technique has been advocated because it is reportedly less invasive, improves screw-bone purchase and reduces neurovascular injury; however, these claims have not been supported by robust clinical evidence. The available evidence was therefore reviewed to assess the relative merits of CBT and highlight areas for further research. To this end, a search of relevant published studies reporting biomechanical, morphometric or clinical outcomes after use of CBT screws in patients with spinal pathologies was performed via six electronic databases. PMID:26311095

  12. A case of an additional right external iliac vein surrounding the right external iliac artery and lacking the right common iliac vein.

    PubMed

    Hayashi, Shogo; Naito, Munekazu; Yakura, Tomiko; Kumazaki, Toshimasa; Itoh, Masahiro; Nakano, Takashi

    2016-01-01

    A case of an additional right external iliac vein lacking a right common iliac vein was found in an 84-year-old female cadaver during a dissection course at Aichi Medical University in 2014. The findings are reported and discussed from the embryological and clinical viewpoints. The right and left iliac venous systems were macroscopically observed with attention to the homonymous arteries and the inferior vena cava. In this cadaver, a preaortic external iliac vein originated from a right external iliac vein and drained directly into the inferior vena cava. The preaortic and right external iliac veins surrounded the right external iliac artery. In addition, the right internal iliac vein drained into the left common iliac vein, and the right obturator vein drained into the right external iliac vein. Our findings suggested that normal external iliac veins developed from the ventral limb of the iliac venous system in this case. Our case has clinical importance for surgical complications such as hemorrhages in pelvic operations, phlebography, and especially central venous cauterization of the right femoral vein. PMID:25715700

  13. 21 CFR 888.3030 - Single/multiple component metallic bone fixation appliances and accessories.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ..., such as screws and nails, or bolts, nuts, and washers. These devices are used for fixation of fractures..., supracondylar, or condylar fractures of the femur; for fusion of a joint; or for surgical procedures...

  14. 21 CFR 888.3030 - Single/multiple component metallic bone fixation appliances and accessories.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ..., such as screws and nails, or bolts, nuts, and washers. These devices are used for fixation of fractures..., supracondylar, or condylar fractures of the femur; for fusion of a joint; or for surgical procedures...

  15. 21 CFR 888.3030 - Single/multiple component metallic bone fixation appliances and accessories.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ..., such as screws and nails, or bolts, nuts, and washers. These devices are used for fixation of fractures..., supracondylar, or condylar fractures of the femur; for fusion of a joint; or for surgical procedures...

  16. 21 CFR 888.3030 - Single/multiple component metallic bone fixation appliances and accessories.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ..., such as screws and nails, or bolts, nuts, and washers. These devices are used for fixation of fractures..., supracondylar, or condylar fractures of the femur; for fusion of a joint; or for surgical procedures...

  17. 21 CFR 888.3030 - Single/multiple component metallic bone fixation appliances and accessories.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ..., such as screws and nails, or bolts, nuts, and washers. These devices are used for fixation of fractures..., supracondylar, or condylar fractures of the femur; for fusion of a joint; or for surgical procedures...

  18. 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.

  19. Effect of different radial hole designs on pullout and structural strength of cannulated pedicle screws.

    PubMed

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

    2015-08-01

    Cannulated pedicle screws are designed for bone cement injection to enhance fixation strength in severely osteoporotic spines. However, the screws commonly fracture during insertion. This study aims to evaluate how different positions/designs of radial holes may affect the pullout and structural strength of cannulated pedicle screws using finite element analysis. Three different screw hole designs were evaluated under torsion and bending conditions. The pullout strength for each screw was determined by axial pullout failure testing. The results showed that when the Von Mises stress reached the yield stress of titanium alloy the screw with four radial holes required a greater torque or bending moment than the nine and twelve hole screws. In the pullout test, the strength and stiffness of each screw with cement augmentation showed no significant differences, but the screw with four radial holes had a greater average pullout strength, which probably resulted from the significantly greater mean maximum lengths of cement augmentation. Superior biomechanical responses, with lower stress around the radial holes and greater pullout strength, represented by cannulated pedicle screw with four radial holes may worth recommending for clinical application. PMID:26054806

  20. Biomechanical Analysis of the Fixation System for T-Shaped Acetabular Fracture

    PubMed Central

    Fan, Yanping; Lei, Jianyin; Zhu, Feng; Li, Zhiqiang; Chen, Weiyi; Liu, Ximing

    2015-01-01

    This study aims to evaluate the biomechanical mechanism of fixation systems in the most frequent T-shaped acetabular fracture using finite element method. The treatment of acetabular fractures was based on extensive clinical experience. Three commonly accepted rigid fixation methods (double column reconstruction plates (P × 2), anterior column plate combined with posterior column screws (P + PS), and anterior column plate combined with quadrilateral area screws (P + QS)) were chosen for evaluation. On the basis of the finite element model, the biomechanics of these fixation systems were assessed through effective stiffness levels, stress distributions, force transfers, and displacements along the fracture lines. All three fixation systems can be used to obtain effective functional outcomes. The third fixation system (P + QS) was the optimal method for T-shaped acetabular fracture. This fixation system may reduce many of the risks and limitations associated with other fixation systems. PMID:26495030

  1. Tibial Fixation Properties of a Continuous-Loop ACL Hamstring Graft Construct with Suspensory Fixation in Porcine Bone.

    PubMed

    Smith, Patrick A; DeBerardino, Thomas M

    2015-12-01

    The aim of this article is to compare tibial fixation strength of suspensory fixation for a quadrupled semitendinosus continuous loop all-inside anterior cruciate ligament (ACL) construct versus a doubled semitendinosus and gracilis graft fixated with an interference screw. Biomechanical testing was conducted using human hamstring allografts and porcine tibias. Constructs were cycled from 50 to 250?N for 500 cycles followed by a pull to failure. The average load to failure of tibial suspensory fixation of the all-inside continuous loop construct (1,012 N) was statistically different compared with the tibial interference screw group (612 N) (p?screw construct (1.9 mm). For both the groups, approximately half the overall cyclic displacement occurred with the first cycle. Tibial side suspensory fixation of a novel all-inside continuous loop hamstring graft provided suitable strength for tibial fixation for ACL reconstruction. The continuous loop construct had a significantly higher load to failure compared with the use of an interference screw, and cyclic loading was comparable. Use of hamstring soft tissue grafts is very common for ACL reconstruction. An all-inside ACL reconstruction is based on a continuous loop construct utilizing a single semitendinosus graft that is quadrupled employing suspensory fixation on both the femoral and tibial side. Suspensory fixation on the femoral side been previously reported, but this is the first report of strength of this method of suspensory fixation on the tibia. PMID:25347056

  2. Is Polymethyl Methacrylate a Viable Option for Salvaging Lateral Mass Screw Failure in the Subaxial Cervical Spine?

    PubMed Central

    Gallizzi, Michael A.; Kuhns, Craig A.; Jenkins, Tyler J.; Pfeiffer, Ferris M.

    2014-01-01

    Study Design?Biomechanical analysis of lateral mass screw pullout strength. Objective?We compare the pullout strength of our bone cement–revised lateral mass screw with the standard lateral mass screw. Methods?In cadaveric cervical spines, we simulated lateral mass screw “cutouts” unilaterally from C3 to C7. We salvaged fixation in the cutout side with polymethyl methacrylate (PMMA) or Cortoss cement (Orthovita, Malvern, Pennsylvania, United States), allowed the cement to harden, and then drilled and placed lateral mass screws back into the cement-augmented lateral masses. On the contralateral side, we placed standard lateral mass screws into the native, or normal lateral, masses and then compared pullout strength of the cement-augmented side to the standard lateral mass screw. For pullout testing, each augmentation group was fixed to a servohydraulic load frame and a specially designed pullout fixture was attached to each lateral mass screw head. Results?Quick-mix PMMA-salvaged lateral mass screws required greater force to fail when compared with native lateral mass screws. Cortoss cement and PMMA standard-mix cement-augmented screws demonstrated less strength of fixation when compared with control-side lateral mass screws. Attempts at a second round of cement salvage of the same lateral masses led to more variations in load to failure, but quick-mix PMMA again demonstrated greater load to failure when compared with the nonaugmented control lateral mass screws. Conclusion?Quick-mix PMMA cement revision equips the spinal surgeon with a much needed salvage option for a failed lateral mass screw in the subaxial cervical spine. PMID:25649421

  3. Is polymethyl methacrylate a viable option for salvaging lateral mass screw failure in the subaxial cervical spine?

    PubMed

    Gallizzi, Michael A; Kuhns, Craig A; Jenkins, Tyler J; Pfeiffer, Ferris M

    2015-02-01

    Study Design?Biomechanical analysis of lateral mass screw pullout strength. Objective?We compare the pullout strength of our bone cement-revised lateral mass screw with the standard lateral mass screw. Methods?In cadaveric cervical spines, we simulated lateral mass screw "cutouts" unilaterally from C3 to C7. We salvaged fixation in the cutout side with polymethyl methacrylate (PMMA) or Cortoss cement (Orthovita, Malvern, Pennsylvania, United States), allowed the cement to harden, and then drilled and placed lateral mass screws back into the cement-augmented lateral masses. On the contralateral side, we placed standard lateral mass screws into the native, or normal lateral, masses and then compared pullout strength of the cement-augmented side to the standard lateral mass screw. For pullout testing, each augmentation group was fixed to a servohydraulic load frame and a specially designed pullout fixture was attached to each lateral mass screw head. Results?Quick-mix PMMA-salvaged lateral mass screws required greater force to fail when compared with native lateral mass screws. Cortoss cement and PMMA standard-mix cement-augmented screws demonstrated less strength of fixation when compared with control-side lateral mass screws. Attempts at a second round of cement salvage of the same lateral masses led to more variations in load to failure, but quick-mix PMMA again demonstrated greater load to failure when compared with the nonaugmented control lateral mass screws. Conclusion?Quick-mix PMMA cement revision equips the spinal surgeon with a much needed salvage option for a failed lateral mass screw in the subaxial cervical spine. PMID:25649421

  4. Strontium-impregnated bioabsorbable composite for osteoporotic fracture fixation.

    PubMed

    Wu, Chang-Chin; Kuo, Chih-Lin; Fan, Fang-Yu; Yang, Kai-Chiang

    2015-10-01

    Osteoporosis impairs the bone-healing process as well as bone fracture fixation. The intervention of osteoporosis is considered to be one part of bone fracture treatment. Thus, orthopedic fixators impregnated with antiosteoporosis regimens will improve fracture fixation in osteoporotic bone. In this study, the strontium (Sr) and calcium phosphate ceramic (CPC) were mixed first and then mixed with poly(?-caprolactone) (PCL) to fabricate a bioactive and bioabsorbable bone fixators. The prepared Sr-CPC/PCL screws were implanted into the distal femur of ovariectomized rabbits. The results showed that Sr-CPC/PCL composite had the appropriate mechanical properties, good biocompatibility, and radio-opacity. The Sr addition created a porous structure and accelerated the degradation of bone screws, but the degradation products did not acidify the surrounding environment. For osteoporotic animals, favorable osteointegration around the Sr-CPC/PCL screws was found, and the total porosity of trabecular bone was decreased under the inspections of micro-computerized tomography. Compared with PCL or CPC/PCL screw, animals which received Sr-CPC/PCL were found to have better results in terms of trabecular number, thickness, and separation. This study reveals that the Sr-impregnated bone fixator improves osseointegration in osteoporotic animals. Sr-CPC/PCL composite is a good candidate material for osteofixation in osteoporotic patients. PMID:25847487

  5. Rotordynamics of Twin-Screw Pumps 

    E-print Network

    Aboel Hassan Muhammed, Ameen

    2013-02-26

    Twin-screw pumps are positive displacement machines. Two meshing screws connected by timing gears convey the fluid trapped in the screw chambers axially from suction to discharge and force it out against the back pressure. Because of the screw...

  6. A new alternative to expandable pedicle screws: Expandable poly-ether-ether-ketone shell.

    PubMed

    Demir, Teyfik

    2015-05-01

    Screw pullout is a very common problem in the fixation of sacrum with pedicle screws. The principal cause of this problem is that the cyclic micro motions in the fixation of sacrum are higher than the other regions of the vertebrae that limit the osteo-integration between bone and screw. In addition to that, the bone quality is very poor at sacrum region. This study investigated a possible solution to the pullout problem without the expandable screws' handicaps. Newly designed poly-ether-ether-ketone expandable shell and classical pedicle screws were biomechanically compared. Torsion test, pullout tests, fatigue tests, flexion/extension moment test, axial gripping capacity tests and torsional gripping capacity tests were conducted in accordance with ASTM F543, F1798 and F1717. Standard polyurethane foam and calf vertebrae were used as embedding medium for pullout tests. Classical pedicle screw pullout load on polyurethane foam was 564.8?N compared to the failure load for calf vertebrae's 1264?N. Under the same test conditions, expandable poly-ether-ether-ketone shell system's pullout loads from polyurethane foam and calf vertebrae were 1196.3 and 1890?N, respectively. The pullout values for expandable poly-ether-ether-ketone shell were 33% and 53% higher than classical pedicle screw on polyurethane foam and calf vertebrae, respectively. The expandable poly-ether-ether-ketone shell exhibited endurance on its 90% of yield load. Contrary to poly-ether-ether-ketone shell, classical pedicle screw exhibited endurance on 70% of its yield load. Expandable poly-ether-ether-ketone shell exhibited much higher pullout performance than classical pedicle screw. Fatigue performance of expandable poly-ether-ether-ketone shell is also higher than classical pedicle screw due to damping the micro motion capacity of the poly-ether-ether-ketone. Expandable poly-ether-ether-ketone shell is a safe alternative to all other expandable pedicle screw systems on mechanical perspective. PMID:25991716

  7. 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.

  8. Complications of Rigid Internal Fixation

    PubMed Central

    Campbell, Chris A.; Lin, Kant Y.

    2009-01-01

    Over the past 20 years, there have been many advances in the development of bone fixation systems used in the practice of craniomaxillofacial surgery. As surgical practices have evolved, the complications of each technologic advance have changed accordingly. Interfragmentary instability of interosseous wiring has been replaced by the risk of exposure, infection, and palpability of plate and screw fixation systems. The improved rigidity of plate fixation requires anatomic alignment of fracture fragments. Failure to obtain proper alignment has led to the phenomenon known as “open internal fixation” of fracture fragments without proper reduction. The size of the plates has decreased to minimize palpability and exposure. However limitations in their application have been encountered due to the physiologic forces of the muscles of mastication and bone healing. In the pediatric population, the long-standing presence of plates in the cranial vault resulted in reports of transcranial migration and growth restriction. These findings led to the development of resorbable plating systems, which are associated with self-limited plate palpability and soft tissue inflammatory reactions. Any rigid system including these produces growth restriction in varying amounts. In this discussion, we review the reported complication rates of miniplating and microplating systems as well as absorptive plating systems in elective and traumatic craniofacial surgery. PMID:22110796

  9. Pullout strength of anterior spinal instrumentation: a product comparison of seven screws in calf vertebral bodies

    PubMed Central

    Wahl, Dieter; Wild, Alexander; Krauspe, Rüdiger; Schneider, Erich; Linke, Berend

    2007-01-01

    A lot of new implant devices for spine surgery are coming onto the market, in which vertebral screws play a fundamental role. The new screws developed for surgery of spine deformities have to be compared to established systems. A biomechanical in vitro study was designed to assess the bone–screw interface fixation strength of seven different screws used for correction of scoliosis in spine surgery. The objectives of the current study were twofold: (1) to evaluate the initial strength at the bone–screw interface of newly developed vertebral screws (Universal Spine System II) compared to established systems (product comparison) and (2) to evaluate the influence of screw design, screw diameter, screw length and bone mineral density on pullout strength. Fifty-six calf vertebral bodies were instrumented with seven different screws (USS II anterior 8.0 mm, USS II posterior 6.2 mm, KASS 6.25 mm, USS II anterior 6.2 mm, USS II posterior 5.2 mm, USS 6.0 mm, USS 5.0 mm). Bone mineral density (BMD) was determined by quantitative computed tomography (QCT). Failure in axial pullout was tested using a displacement-controlled universal test machine. USS II anterior 8.0 mm showed higher pullout strength than all other screws. The difference constituted a tendency (P = 0.108) when compared to USS II posterior 6.2 mm (+19%) and was significant in comparison to the other screws (+30 to +55%, P < 0.002). USS II posterior 6.2 mm showed significantly higher pullout strength than USS 5.0 mm (+30%, P = 0.014). The other screws did not differ significantly in pullout strength. Pullout strength correlated significantly with BMD (P = 0.0015) and vertebral body width/screw length (P < 0.001). The newly developed screws for spine surgery (USS II) show higher pullout strength when compared to established systems. Screw design had no significant influence on pullout force in vertebral body screws, but outer diameter of the screw, screw length and BMD are good predictors of pullout resistance. PMID:17273838

  10. Hydroxylapatite-coated Diapason screws: first clinical report.

    PubMed

    Lapresle, P; Missenard, G

    1995-01-01

    We report our preliminary experience with 27 patients who underwent surgery for posterior spinal arthrodesis using the hydroxylapatite-coated Diapason screws. Each of the patients was considered to have a condition that was mechanically risky from the surgical standpoint. The results were good for patients with lytic spondylolisthesis and were excellent for patients with osteoporosis, but were generally less successful for patients requiring "long lever arm" fixations and those with degenerative scoliosis. PMID:7787345

  11. Comparison and prediction of pullout strength of conical and cylindrical pedicle screws within synthetic bone

    PubMed Central

    Tsai, Wen-Chi; Chen, Po-Quang; Lu, Tung-Wu; Wu, Shing-Sheng; Shih, Kao-Shang; Lin, Shang-Chih

    2009-01-01

    Background This study was designed to derive the theoretical formulae to predict the pullout strength of pedicle screws with an inconstant outer and/or inner diameter distribution (conical screws). For the transpedicular fixation, one of the failure modes is the screw loosening from the vertebral bone. Hence, various kinds of pedicle screws have been evaluated to measure the pullout strength using synthetic and cadaveric bone as specimens. In the literature, the Chapman's formula has been widely proposed to predict the pullout strength of screws with constant outer and inner diameters (cylindrical screws). Methods This study formulated the pullout strength of the conical and cylindrical screws as the functions of material, screw, and surgery factors. The predicted pullout strength of each screw was compared to the experimentally measured data. Synthetic bones were used to standardize the material properties of the specimen and provide observation of the loosening mechanism of the bone/screw construct. Results The predicted data from the new formulae were better correlated with the mean pullout strength of both the cylindrical and conical screws within an average error of 5.0% and R2 = 0.93. On the other hand, the average error and R2 value of the literature formula were as high as -32.3% and -0.26, respectively. Conclusion The pullout strength of the pedicle screws was the functions of bone strength, screw design, and pilot hole. The close correlation between the measured and predicted pullout strength validated the value of the new formulae, so as avoid repeating experimental tests. PMID:19402917

  12. Parallel analysis of finite element model controlled trial and retrospective case control study on percutaneous internal fixation for vertical sacral fractures

    PubMed Central

    2013-01-01

    Background Although percutaneous posterior-ring tension-band metallic plate and percutaneous iliosacral screws are used to fix unstable posterior pelvic ring fractures, the biomechanical stability and compatibility of both internal fixation techniques for the treatment of Denis I, II and III type vertical sacral fractures remain unclear. Methods Using CT and MR images of the second generation of Chinese Digitized Human “male No. 23”, two groups of finite element models were developed for Denis I, II and III type vertical sacral fractures with ipsilateral superior and inferior pubic ramus fractures treated with either a percutaneous metallic plate or a percutaneous screw. Accordingly, two groups of clinical cases that were fixed using the above-mentioned two internal fixation techniques were retrospectively evaluated to compare postoperative effect and function. Parallel analysis was performed with a finite element model controlled trial and a case control study. Results The difference of the postoperative Majeed standards and outcome rates between two case groups was no statistically significant (P?>?0.05). Accordingly, the high values of the maximum displacements/stresses of the plate-fixation model group approximated those of the screw-fixation model group. However, further simulation of Denis I, II and III type fractures in each group of models found that the biomechanics of the plate-fixation models became increasingly stable and compatible, whereas the biomechanics of the screw-fixation models maintained tiny fluctuations. When treating Denis III fractures, the biomechanical effects of the pelvic ring of the plate-fixation model were better than the screw-fixation model. Conclusions Percutaneous plate and screw fixations are both appropriate for the treatment of Denis I and II type vertical sacral fractures; whereas percutaneous plate fixation appears be superior to percutaneous screw fixation for Denis III type vertical sacral fracture. Biomechanical evidence of finite element evaluations combined with clinical evidence will contribute to our ability to distinguish between indications that require plate or screw fixation for vertical sacral fractures. PMID:23879618

  13. Management of fracture-dislocation of the lower cervical spine with the cervical pedicle screw system

    PubMed Central

    Zhou, Feng; Zou, Jun; Gan, Minfeng; Zhu, Ruofu; Yang, Huilin

    2010-01-01

    INTRODUCTION Usually, cervical pedicle screw fixation has been considered too risky for neurovascular structures. The purpose of this study was to investigate the method and efficacy of the cervical pedicle screw system for fracture-dislocation of the cervical spine because of its rigid fixation. PATIENTS AND METHODS A prospective study was conducted involving 48 patients with cervical spine fracture-dislocation who underwent cervical pedicle screw fixation surgery between January 2003 and January 2007. All patients had various degrees of cord injury, and they were classified according to the American Spinal Cord Injury Association (ASIA) Impairment Scale: 18 cases were grade A, 15 grade B, 10 grade C, and 5 grade D. RESULTS Six months after the operation, all patients had achieved solid bony fusion and stable fixation of the related segments. Thirty patients with incomplete spinal cord injury improved their ASIA Impairment Scale classification by 1 to 2 grades after the operation. Eighteen patients with complete spinal cord injury had no improvement in neural function. However, nerve root symptoms such as pain and numbness were alleviated to some extent. CONCLUSIONS The cervical pedicle screw system is an effective and reliable method for the restoration of cervical stability. Sufficient pre-operative imaging studies of the pedicles and strict screw insertion technique should be emphasised. PMID:20487593

  14. Early Results from Posterior Cervical Fusion with a Screw-Rod System

    PubMed Central

    Kim, Sang Hyun; Shin, Dong Ah; Yi, Seung; Yoon, Do Heum; Kim, Keung Nyun

    2007-01-01

    Purpose We performed 65 cases of posterior fusion surgery for cervical and/or high thoracic lesions using a polyaxial screw-rod system. Patients and Methods A total of 486 screws were implanted in 65 patients. Results Fixation of the screws was carried out over an average of 2.9 spinal segments. Upon evaluation by postoperative CT scans, twelve (2.5%) screws had suboptimal trajectories but two of these revealed radiculopathy in one patient and required screw repositioning. No vascular sequelae resulted. There has been no segmental motion in any of the cases to date. As for other complications, there was one case of dural tearing and two cases of lateral mass fractures. There were no infections or other wound healing problems or hardware failures. No patients had neurological deterioration after surgery. There were statistically significant improvements in the mean Neck Disability Index (NDI) scores and Visual Analogue Scale (VAS) scores in the preoperative and late postoperative follow-up evaluations. Although further studies are required to establish the long-term results of fusion rates and clinical outcomes. Conclusion We cautiously suggest that the posterior polyaxial screw-rod system can be safely used as a primary or additional fusion method in this risky region. The successful and safe use of this method is dependent on a precise preoperative surgical plan and tactics for ensuring safe screw fixation. PMID:17594152

  15. Axial compression generated by cortical and cancellous lag screws in the equine distal phalanx.

    PubMed

    Johnson, K A; Smith, F W

    2003-09-01

    Lag screw fixation using single 4.5 mm cortical bone screws is a recommended technique for repair of mid-sagittal plane fractures of the distal phalanx in adult horses. However, implant infection and technical difficulties in obtaining adequate interfragmentary compression have made this surgical procedure somewhat controversial. We hypothesized that use of larger diameter screws would result in increased axial compression and improved stability of this fracture. Paired distal phalanges from the forelimbs of 10 adult horses were collected at necropsy and divided in half in the midsagittal plane. Using a randomized block study design, four types of bone screws (4.5 mm cortical, 5.5 mm cortical, 6.5 mm cancellous pre-tapped, and 6.5 mm cancellous non-tapped) were inserted to a depth of 15 mm. During screw insertion, the axial force generated under the screw head was measured with a load washer containing a piezoelectric force transducer, while torque of insertion was recorded with a torsional testing machine. The 6.5mm screw inserted after pre-tapping generated significantly greater axial force (2781 N) than the 4.5 mm (1522 N), 5.5 mm (2073 N) or 6.5 mm non-tapped (2295 N) screws. The relationship between maximal applied torque and axial force generated was linear for each screw type. Each unit of torque applied during insertion of cortical screws resulted in a greater increase in axial compression, as compared to cancellous screws. These data suggest that use of larger diameter screws would result in improved interfragmentary compression of distal phalangeal fractures. PMID:12902180

  16. Finite Element Analysis of a New Pedicle Screw-Plate System for Minimally Invasive Transforaminal Lumbar Interbody Fusion

    PubMed Central

    Zhou, Yue; Li, Changqing; Liu, Huan

    2015-01-01

    Purpose Minimally invasive transforaminal lumbar interbody fusion (MI-TLIF) is increasingly popular for the surgical treatment of degenerative lumbar disc diseases. The constructs intended for segmental stability are varied in MI-TLIF. We adopted finite element (FE) analysis to compare the stability after different construct fixations using interbody cage with posterior pedicle screw-rod or pedicle screw-plate instrumentation system. Methods A L3–S1 FE model was modified to simulate decompression and fusion at L4–L5 segment. Fixation modes included unilateral plate (UP), unilateral rod (UR), bilateral plate (BP), bilateral rod (BR) and UP+UR fixation. The inferior surface of the S1 vertebra remained immobilized throughout the load simulation, and a bending moment of 7.5 Nm with 400N pre-load was applied on the L3 vertebra to recreate flexion, extension, lateral bending, and axial rotation. Range of motion (ROM) and Von Mises stress were evaluated for intact and instrumentation models in all loading planes. Results All reconstructive conditions displayed decreased motion at L4–L5. The pedicle screw-plate system offered equal ROM to pedicle screw-rod system in unilateral or bilateral fixation modes respectively. Pedicle screw stresses for plate system were 2.2 times greater than those for rod system in left lateral bending under unilateral fixation. Stresses for plate were 3.1 times greater than those for rod in right axial rotation under bilateral fixation. Stresses on intervertebral graft for plate system were similar to rod system in unilateral and bilateral fixation modes respectively. Increased ROM and posterior instrumentation stresses were observed in all loading modes with unilateral fixation compared with bilateral fixation in both systems. Conclusions Transforaminal lumbar interbody fusion augmentation with pedicle screw-plate system fixation increases fusion construct stability equally to the pedicle screw-rod system. Increased posterior instrumentation stresses are observed in all loading modes with plate fixation, and bilateral fixation could reduce stress concentration. PMID:26649749

  17. Dynamic-locking-screw (DLS)–leads to less secondary screw perforations in proximal humerus fractures

    PubMed Central

    2014-01-01

    Background Loss of reduction and screw perforation causes high failure rates in the treatment of proximal humerus fractures. The purpose of the present study was to evaluate the early postoperative complications using modern Dynamic Locking Screws (DLS 3.7) for plating of proximal humerus fractures. Methods Between 03/2009 and 12/2010, 64 patients with acute proximal humerus fractures were treated by angular stable plate fixation using DLSs in a limited multi-centre study. Follow-up examinations were performed three, six, twelve and twenty-four weeks postoperatively and any complications were carefully collected. Results 56 of 64 patients were examined at the six-month follow-up. Complications were observed in 12 patients (22%). In five cases (9%), a perforation of the DLS 3.7 occurred. Conclusions Despite the use of modern DLS 3.7, the early complications after plating of proximal humerus fractures remain high. The potential advantage of the DLS 3.7 regarding secondary screw perforation has to be confirmed by future randomized controlled trials. PMID:24894637

  18. In vitro and in vivo studies on the degradation of high-purity Mg (99.99wt.%) screw with femoral intracondylar fractured rabbit model.

    PubMed

    Han, Pei; Cheng, Pengfei; Zhang, Shaoxiang; Zhao, Changli; Ni, Jiahua; Zhang, Yuanzhuang; Zhong, Wanrun; Hou, Peng; Zhang, Xiaonong; Zheng, Yufeng; Chai, Yimin

    2015-09-01

    High-purity magnesium (HP Mg) takes advantage in no alloying toxic elements and slower degradation rate in lack of second phases and micro-galvanic corrosion. In this study, as rolled HP Mg was fabricated into screws and went through in vitro immersion tests, cytotoxicity test and bioactive analysis. The HP Mg screws performed uniform corrosion behavior in vitro, and its extraction promoted cell viability, bone alkaline phosphatase (ALP) activity, and mRNA expression of osteogenic differentiation related gene, i.e. ALP, osteopontin (OPN) and RUNX2 of human bone marrow mesenchymal stem cells (hBMSCs). Then HP Mg screws were implanted in vivo as load-bearing implant to fix bone fracture and subsequently gross observation, range of motion (ROM), X-ray scanning, qualitative micro-computed tomography (?CT) analysis, histological analysis, bending-force test and SEM morphology of retrieved screws were performed respectively at 4, 8, 16 and 24 weeks. As a result, the retrieved HP Mg screws in fixation of rabbit femoral intracondylar fracture showed uniform degradation morphology and enough bending force. However, part of PLLA screws was broken in bolt, although its screw thread was still intact. Good osseointegration was revealed surrounding HP Mg screws and increased bone volume and bone mineral density were detected at fracture gap, indicating the rigid fixation and enhanced fracture healing process provided by HP Mg screws. Consequently, the HP Mg showed great potential as internal fixation devices in intra-articular fracture operation. PMID:26117658

  19. A New Mini-External Fixator for Treating Hallux Valgus: A Preclinical, Biomechanical Study.

    PubMed

    Erdil, Mehmet; Ceylan, Hasan Huseyin; Polat, Gokhan; Kara, Deniz; Bozdag, Ergun; Sunbuloglu, Emin

    2016-01-01

    Proximal metatarsal osteotomy is the most effective technique for correcting hallux valgus deformities, especially in metatarsus primus varus. However, these surgeries are technically demanding and prone to complications, such as nonunion, implant failure, and unexpected extension of the osteotomy to the tarsometatarsal joint. In a preclinical study, we evaluated the biomechanical properties of the fixator and compared it with compression screws for treating hallux valgus with a proximal metatarsal osteotomy. Of 18 metatarsal composite bone models proximally osteotomized, 9 were fixed with a headless compression screw and 9 with the mini-external fixator. A dorsal angulation of 10° and displacement of 10 mm were defined as the failure threshold values. Construct stiffness and the amount of interfragmentary angulation were calculated at various load cycles. All screw models failed before completing 1000 load cycles. In the fixator group, only 2 of 9 models (22.2%) failed before 1000 cycles, both between the 600th and 700th load cycles. The stability of fixation differed significantly between the groups (p < .001). The stability provided by the mini-external fixator was superior to that of compression screw fixation. Additional testing of the fixator is indicated. PMID:26190777

  20. 49 CFR 572.199 - Pelvis iliac.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... accelerometer as specified in 49 CFR 572.200(d), and iliac wing load cell SA572-S66, mounted as shown in sheet 2... procedure. (1) Soak the dummy assembly (180-0000) in a test environment as specified in 49 CFR 572.200(j... pelvis impactor is specified in 49 CFR 572.200(c). (8) The dummy is positioned with respect to...

  1. 49 CFR 572.199 - Pelvis iliac.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... specified in 49 CFR 572.200(d), and iliac wing load cell SA572-S66, mounted as shown in sheet 2 of 5 of... the dummy assembly (180-0000) in a test environment as specified in 49 CFR 572.200(j). (2) Seat the... impactor is specified in 49 CFR 572.200(c). (8) The dummy is positioned with respect to the impactor...

  2. 49 CFR 572.199 - Pelvis iliac.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... accelerometer as specified in 49 CFR 572.200(d), and iliac wing load cell SA572-S66, mounted as shown in sheet 2... procedure. (1) Soak the dummy assembly (180-0000) in a test environment as specified in 49 CFR 572.200(j... pelvis impactor is specified in 49 CFR 572.200(c). (8) The dummy is positioned with respect to...

  3. 49 CFR 572.199 - Pelvis iliac.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... specified in 49 CFR 572.200(d), and iliac wing load cell SA572-S66, mounted as shown in sheet 2 of 5 of... the dummy assembly (180-0000) in a test environment as specified in 49 CFR 572.200(j). (2) Seat the... impactor is specified in 49 CFR 572.200(c). (8) The dummy is positioned with respect to the impactor...

  4. 49 CFR 572.199 - Pelvis iliac.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... specified in 49 CFR 572.200(d), and iliac wing load cell SA572-S66, mounted as shown in sheet 2 of 5 of... the dummy assembly (180-0000) in a test environment as specified in 49 CFR 572.200(j). (2) Seat the... impactor is specified in 49 CFR 572.200(c). (8) The dummy is positioned with respect to the impactor...

  5. A Novel Fixation System for Acetabular Quadrilateral Plate Fracture: A Comparative Biomechanical Study

    PubMed Central

    Zha, Guo-Chun; Sun, Jun-Ying; Dong, Sheng-Jie; Zhang, Wen; Luo, Zong-Ping

    2015-01-01

    This study aims to assess the biomechanical properties of a novel fixation system (named AFRIF) and to compare it with other five different fixation techniques for quadrilateral plate fractures. This in vitro biomechanical experiment has shown that the multidirectional titanium fixation (MTF) and pelvic brim long screws fixation (PBSF) provided the strongest fixation for quadrilateral plate fracture; the better biomechanical performance of the AFRIF compared with the T-shaped plate fixation (TPF), L-shaped plate fixation (LPF), and H-shaped plate fixation (HPF); AFRIF gives reasonable stability of treatment for quadrilateral plate fracture and may offer a better solution for comminuted quadrilateral plate fractures or free floating medial wall fracture and be reliable in preventing protrusion of femoral head. PMID:25802849

  6. The use of silk-based devices for fracture fixation

    NASA Astrophysics Data System (ADS)

    Perrone, Gabriel S.; Leisk, Gary G.; Lo, Tim J.; Moreau, Jodie E.; Haas, Dylan S.; Papenburg, Bernke J.; Golden, Ethan B.; Partlow, Benjamin P.; Fox, Sharon E.; Ibrahim, Ahmed M. S.; Lin, Samuel J.; Kaplan, David L.

    2014-03-01

    Metallic fixation systems are currently the gold standard for fracture fixation but have problems including stress shielding, palpability and temperature sensitivity. Recently, resorbable systems have gained interest because they avoid removal and may improve bone remodelling due to the lack of stress shielding. However, their use is limited to paediatric craniofacial procedures mainly due to the laborious implantation requirements. Here we prepare and characterize a new family of resorbable screws prepared from silk fibroin for craniofacial fracture repair. In vivo assessment in rat femurs shows the screws to be self-tapping, remain fixed in the bone for 4 and 8 weeks, exhibit biocompatibility and promote bone remodelling. The silk-based devices compare favourably with current poly-lactic-co-glycolic acid fixation systems, however, silk-based devices offer numerous advantages including ease of implantation, conformal fit to the repair site, sterilization by autoclaving and minimal inflammatory response.

  7. Early Experience with Biodegradable Fixation of Pediatric Mandibular Fractures.

    PubMed

    Mazeed, Ahmed Salah; Shoeib, Mohammed Abdel-Raheem; Saied, Samia Mohammed Ahmed; Elsherbiny, Ahmed

    2015-09-01

    This clinical study aims to evaluate the stability and efficiency of biodegradable self-reinforced poly-l/dl-lactide (SR-PLDLA) plates and screws for fixation of pediatric mandibular fractures. The study included 12 patients (3-12 years old) with 14 mandibular fractures. They were treated by open reduction and internal fixation by SR-PLDLA plates and screws. Maxillomandibular fixation was maintained for 1?week postoperatively. Clinical follow-up was performed at 1?week, 6 weeks, 3 months, and 12 months postoperatively. Radiographs were done at 1?week, 3 months, and 12 months postoperatively to observe any displacement and fracture healing. All fractures healed both clinically and radiologically. No serious complications were reported in the patients. Normal occlusion was achieved in all cases. Biodegradable osteofixation of mandibular fractures offers a valuable clinical solution for pediatric patients getting the benefit of avoiding secondary surgery to remove plates, decreasing the hospital stay, further painful procedures, and psychological impact. PMID:26269728

  8. Lagged Syndesmotic Fixation: Our Clinical Experience.

    PubMed

    Kwaadu, Kwasi Yiadom; Fleming, Justin James; Salmon, Trudy

    2015-01-01

    Ankle fractures are very common, and although algorithms are in place for osseous management, consensus has not been reached regarding treatment of associated ligamentous injuries. Although tibiofibular syndesmotic stabilization can be done using different forms of fixation, the biomedical literature has long emphasized the risk of long-term restriction of ankle mobility with the use of lagged transfixation. However, when reduction cannot be maintained with positional fixation, we found that lagging the syndesmotic screw helped to maintain the reduction without causing functional restriction. In this report, we describe our experience with patients who had undergone lagged tibiofibular transfixation and were available for short- to intermediate-term follow-up to assess ankle function. A total of 31 patients (32.63% of 95 consecutive patients) were available at a mean of 34.87 (range 18 to 52) months to complete the American Orthopedic Foot and Ankle Society ankle-hindfoot questionnaire. The mean score was 88.38 (range 42 to 100) points at a mean follow-up interval of 34.87 (range 18 to 52) months. Of 31 patients, 19 had an AOFAS score of 90 points, 9 an AOFAS score of 80 to 89 points, 2 an AOFAS score of 60 to 69 points, and 1 an AOFAS score of <60 points. Because all syndesmotic screws were placed using the lag technique, unrestricted motion compared with the uninjured limb was used as the endpoint. All subjects had unrestricted motion compared with the uninjured limb, refuting the assertion that lagged syndesmotic screw fixation confers more restriction in ankle kinematics than positional syndesmotic fixation. PMID:25736445

  9. Unusual mode of failure of intertrochanteric femur fracture fixation.

    PubMed

    Roy, Kunal; Nemade, Pradip; Aggarwal, Rishi; Patil, Nirmal

    2015-01-01

    The dynamic hip screw fixation is a commonly used modality of treatment for intertrochanteric femur (ITF) fractures. Various modes of failure in an operated case of ITF fracture have been described. The most frequent mode of failure is screw cut-out through the head. Occurrence of mechanical failure is rare and usually involves the shaft of the plate. We describe an unusual case with failure at the barrel of the plate and hip screw. A middle-aged man with a previously operated ITF fracture presented with pain in the same hip. Radiographs revealed non-union of the fracture with an implant failure. Revision surgery was performed during which a unique mode of implant failure was found to have occurred. The barrel of the plate had broken resulting in a bent Richard's screw. This case underlines the importance of high stress failure in non-union as opposed to high cycle, low stress failure, which is more frequently seen. PMID:26564119

  10. Strength analysis of clavicle fracture fixation devices and fixation techniques using finite element analysis with musculoskeletal force input.

    PubMed

    Marie, Cronskär

    2015-08-01

    In the cases, when clavicle fractures are treated with a fixation plate, opinions are divided about the best position of the plate, type of plate and type of screw units. Results from biomechanical studies of clavicle fixation devices are contradictory, probably partly because of simplified and varying load cases used in different studies. The anatomy of the shoulder region is complex, which makes it difficult and expensive to perform realistic experimental tests; hence, reliable simulation is an important complement to experimental tests. In this study, a method for finite element simulations of stresses in the clavicle plate and bone is used, in which muscle and ligament force data are imported from a multibody musculoskeletal model. The stress distribution in two different commercial plates, superior and anterior plating position and fixation including using a lag screw in the fracture gap or not, was compared. Looking at the clavicle fixation from a mechanical point of view, the results indicate that it is a major benefit to use a lag screw to fixate the fracture. The anterior plating position resulted in lower stresses in the plate, and the anatomically shaped plate is more stress resistant and stable than a regular reconstruction plate. PMID:25850983

  11. 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.

  12. Low noise lead screw positioner

    NASA Astrophysics Data System (ADS)

    Perkins, Gerald S.

    1986-05-01

    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.

  13. Tibial Tunnel Cyst Formation after Anterior Cruciate Ligament Reconstruction Using a Non-Bioabsorbable Interference Screw

    PubMed Central

    Joshi, Yogesh V.; Phaltankar, Padmanabh M.; Charalambous, Charalambos P.

    2015-01-01

    Tibial cyst formation following the use of bioabsorbable interference screws in anterior cruciate ligament (ACL) reconstruction is well-described; however, cyst formation after the use of metallic interference screws is not well-documented. We describe a case of osteolytic lesion of the proximal tibia presenting to us 20 years after ACL reconstruction using an autologous bone-tendon-bone graft. The original graft fixation technique was interference fixation with a metal screw in the tibial and femoral tunnels. A two-stage revision reconstruction of the ACL was undertaken with curettage and bone grafting of the tibial lesion in the first stage and reconstruction using a four-strand hamstring tendon in the second stage. The patient recovered satisfactorily with complete healing of the cyst and returned to pre-injury level of activities. We have reviewed case reports and case series that describe the aetiology of intra-osseous cyst formation following ACL reconstruction. PMID:26673117

  14. A Pitfall in Fixation of Distal Humeral Fractures with Pre-Contoured Locking Compression Plate

    PubMed Central

    Jayakumar, Prakash; Ring, David

    2015-01-01

    Anatomically precontoured locking plates are intended to facilitate the fixation of articular fractures and particularly those associated with osteoporosis. Fractures of the distal humerus are relatively uncommon injuries where operative intervention can be exceptionally challenging. The distal humeral trochlea provides a very narrow anatomical window through which to pass a fixed-angle locking screw, which must also avoid the olecranon, coronoid, and radial fossae. We describe 3 patients (ages 27, 49, and 73 years) with a bicolumnar fracture of the distal humerus where very short distal locking screws were used. Intra-articular screw placement was avoided but loss of fixation occurred in two patients and a third was treated with a prolonged period of immobilization. We postulate that fixed-angle screw trajectories may make it difficult for the surgeon to place screws of adequate length in this anatomically confined region, and may lead to insufficient distal fixation. Surgical tactics should include placement of as many screws as possible into the distal fragment, as long as possible and that each screw passes through a plate without necessarily locking in. PMID:26110181

  15. A Pitfall in Fixation of Distal Humeral Fractures with Pre-Contoured Locking Compression Plate.

    PubMed

    Jayakumar, Prakash; Ring, David

    2015-04-01

    Anatomically precontoured locking plates are intended to facilitate the fixation of articular fractures and particularly those associated with osteoporosis. Fractures of the distal humerus are relatively uncommon injuries where operative intervention can be exceptionally challenging. The distal humeral trochlea provides a very narrow anatomical window through which to pass a fixed-angle locking screw, which must also avoid the olecranon, coronoid, and radial fossae. We describe 3 patients (ages 27, 49, and 73 years) with a bicolumnar fracture of the distal humerus where very short distal locking screws were used. Intra-articular screw placement was avoided but loss of fixation occurred in two patients and a third was treated with a prolonged period of immobilization. We postulate that fixed-angle screw trajectories may make it difficult for the surgeon to place screws of adequate length in this anatomically confined region, and may lead to insufficient distal fixation. Surgical tactics should include placement of as many screws as possible into the distal fragment, as long as possible and that each screw passes through a plate without necessarily locking in. PMID:26110181

  16. Anterior and posterior fixation for delayed treatment of posterior atlantoaxial dislocation without fracture.

    PubMed

    Yu, Hai Ming; Malhotra, Karan; Butler, Joseph S; Wu, Shi Qiang

    2015-01-01

    Posterior atlantoaxial dislocation (PAAD) without fracture of the odontoid process is a rare injury. Authors have variously reported closed or open reduction, followed by either anterior or posterior fixation, but there is no consensus on best treatment. We present a particularly unstable case of PAAD. Open reduction through a retropharyngeal approach with odontoidectomy was required for reduction. Anterior fixation with transarticular lag screws was required prior to posterior fixation with pedicle screws. Despite non-compliance with postoperative immobilisation, imaging at 20-month follow-up confirmed solid fusion. The patient is pain-free with a good range of movement of the neck and has returned to a manual job. Our case had a greater degree of instability than was previously reported, which necessitated 360° fixation. This is the first reported case of this treatment strategy, which provided a very stable fixation allowing fusion despite early movement and without causing undue stiffness. PMID:26516249

  17. Fixation strength of a novel bioabsorbable expansion bolt for patellar tendon bone graft fixation: an experimental study in calf tibial bone.

    PubMed

    Piltz, Stefan; Strunk, Patrick; Meyer, Ludger; Plitz, Wolfgang; Lob, Guenter

    2004-09-01

    This biomechanical study compares the initial fixation strength of a novel bioabsorbable two-shell expansion bolt (EB) with that of a well-established interference-screw technique in bone-patellar tendon-bone (BPTB) reconstruction in a calf model. Thirty tibia plateaus (age 5-6 months) were assigned to three groups: In groups I and II, trapezoidal bone plugs of BPTB grafts were fixed with bioabsorbable poly-L-lactide interference screws (8 x 23 mm) or titanium interference screws (8 x 25 mm) respectively. In group III, semicircular grafts were fixed using bioabsorbable poly-D, L-lactide expansion bolts (5.8/8.7 x 10 x 35 mm). The tensile axis was parallel to the bone tunnel, and the construction was loaded until failure applying a displacement rate of 1 mm per second. In group II the mean ultimate loads to failure (713 N+/-218 N) were found to be significantly higher than those of groups I (487 N+/-205 N) and III (510 N+/-133 N). Measurement of stiffness showed 45 N/mm+/-13.3 in group I, 58 N/mm+/-17.4 in group II and 46 N/mm+/-6.9 in group III, and did not demonstrate significant differences. We found a correlation between insertion torque and wedge insertion force and ultimate loads to failure in all groups (r=0.53 in group I, r =0.54 in group II, and r =0.57 in group III). Cross-section planes of bone tunnel increased by 51%, 30% and 31% respectively, following insertion of screws or expansion of bolts (p<0.05). We conclude that ACL graft fixation by means of the presented expansion bolt demonstrates a fixation strength similar to the established bioabsorbable screw fixation, and is a reasonable alternative fixation method, especially since some of the specific pitfalls of screw fixation can be avoided. PMID:15042285

  18. Screw/stud removal tool

    NASA Technical Reports Server (NTRS)

    Daniels, K.; Herrick, D. E.; Rothermel, L.

    1980-01-01

    Tool removes stubborn panheaded screws or studs where conventional tools would be either too weak or inconvenient to use. Screws with damaged heads or slots can also be removed this way. Tool can be worked with one hand and easily fits limited-access and blind areas. It can be made in various sizes to fit different screwheads.

  19. Comparison of Hallux Interphalangeal Joint Arthrodesis Fixation Techniques: A Retrospective Multicenter Study.

    PubMed

    Thorud, Jakob C; Jolley, Tyler; Shibuya, Naohiro; Lew, Eric; Britt, Matthew; Butterfield, Ted; Boike, Alan; Hardy, Mark; Brancheau, Steven P; Motley, Travis; Jupiter, Daniel C

    2016-01-01

    Few studies have investigated the complications that occur after hallux interphalangeal joint arthrodesis. The present study evaluated complications in 152 patients aged 18 to 80 years from 2005 to 2012 from 4 different academic institutions after hallux interphalangeal joint arthrodesis. Overall, 65.8% of the patients had ?1 complication. Infections occurred in 16.5%, dehiscence in 12.5%, and reoperations in 27.0%. The clinical nonunion rate was ?17.8%, and the radiographic nonunion rate was ?13.8%. After logistic regression analysis, only the study site and peripheral neuropathy were associated with having ?1 complication (p < .01 and p < .05, respectively). Single screw fixation compared with other fixation did not have a statistically significant influence on the postoperative complications. However, when fixation was expanded to 4 categories, single screw fixation had lower infection and reoperation rates than either crossed Kirschner wires or other fixation category but not compared with crossed screws on multivariate logistic regression analysis. Although additional studies are warranted, the findings from the present study might aid in both the prognosis of complications and the support of the use of a single screw over crossed Kirchner wire fixation in hallux interphalangeal joint arthrodesis. PMID:25960055

  20. An Innovative Universal Screw Removal Instrument

    PubMed Central

    Elmada?, Mehmet; Uzer, Gökçer; Acar, Mehmet Ali

    2015-01-01

    Objective To present the clinical benefits of an instrument designed to facilitate removal of polyaxial screws during revision surgery. Methods All polyaxial screws can be removed without additional materials or a large amount of debridement using our newly designed instrument. Forty-two screws were removed from five patients without any complications using this instrument. Results We removed the cap screws and rods from the 42 polyaxial screws in five patients and made them monoaxial using the new screw removal apparatus. The screws and rods were removed quickly in a minimally invasive way with no complications. No damage to the pedicle or surrounding soft tissue occurred during screw removal. No neurogenic changes developed during revision surgery after changing the screws. Conclusion This newly designed screw removal instrument was used safely and effectively to remove all polyaxial and monoaxial pedicle screws. PMID:25883660

  1. Concentric double cables fixation as an alternative suspension method for the endoscopic forehead lift.

    PubMed

    Massoud, Karim S; Aboelatta, Yasser Abdallah

    2015-06-01

    Fixation of the elevated eyebrow is an important final step in endoscopic forehead lifting. One of the most common methods of fixation includes temporal fasciae sutures for the tail of the eyebrow, and mini-screws for the body of the eyebrow. The concentric cables fixation is an alternative method for elevation of both the tail and the body of the eyebrow. This technique is compared to temporal fasciae suture and mini-screws fixation. Thirty-one patients were included in this study. They were divided into two groups; group I included patients who underwent fixation using fascia sutures and mini-screws, while group II patients underwent concentric cables suspension. Traditional screw and suture technique elevated the eyebrow tail by 7.2, 6.7, 6.3, and 6.0 mm, while the concentric cables resulted in 7.6, 6.8, 6.5, and 6.3 mm elevation at 1, 3, 6, and 12 months postoperatively, respectively. The mean values of brow body elevation were 6.8, 6.4, 6.2, and 5.9 mm for group I, while the mean values of group II were 6, 5.4, 4.8, and 4.7 mm. The concentric cables technique showed a fewer complications rate compared to traditional fixation. The concentric cables fixation offers an alternative inexpensive method to suspend the tail, and to a lesser extent the body, of both eyebrows simultaneously with long-term stability. A fewer complications rate was documented compared to traditional temporal fasciae sutures and mini-screws fixation. PMID:25272310

  2. The Effects of Spinopelvic Parameters and Paraspinal Muscle Degeneration on S1 Screw Loosening

    PubMed Central

    Kim, Jin-Bum; Lee, Young-Seok; Nam, Taek-Kyun; Park, Yong-Sook; Kim, Young-Baeg

    2015-01-01

    Objective To investigate risk factors for S1 screw loosening after lumbosacral fusion, including spinopelvic parameters and paraspinal muscles. Methods We studied with 156 patients with degenerative lumbar disease who underwent lumbosacral interbody fusion and pedicle screw fixation including the level of L5-S1 between 2005 and 2012. The patients were divided into loosening and non-loosening groups. Screw loosening was defined as a halo sign larger than 1 mm around a screw. We checked cross sectional area of paraspinal muscles, mean signal intensity of the muscles on T2 weight MRI as a degree of fatty degeneration, spinopelvic parameters, bone mineral density, number of fusion level, and the characteristic of S1 screw. Results Twenty seven patients showed S1 screw loosening, which is 24.4% of total. The mean duration for S1 screw loosening was 7.3±4.1 months after surgery. Statistically significant risk factors were increased age, poor BMD, 3 or more fusion levels (p<0.05). Among spinopelvic parameters, a high pelvic incidence (p<0.01), a greater difference between pelvic incidence and lumbar lordotic angle preoperatively (p<0.01) and postoperatively (p<0.05). Smaller cross-sectional area and high T2 signal intensity in both multifidus and erector spinae muscles were also significant muscular risk factors (p<0.05). Small converging angle (p<0.001) and short intraosseous length (p<0.05) of S1 screw were significant screw related risk factors (p<0.05). Conclusion In addition to well known risk factors, spinopelvic parameters and the degeneration of paraspinal muscles also showed significant effects on the S1 screw loosening. PMID:26587190

  3. In-vitro development of a temporal abutment screw to protect osseointegration in immediate loaded implants

    PubMed Central

    2015-01-01

    PURPOSE In this study, a temporal abutment fixation screw, designed to fracture in a controlled way upon application of an occlusal force sufficient to produce critical micromotion was developed. The purpose of the screw was to protect the osseointegration of immediate loaded single implants. MATERIALS AND METHODS Seven different screw prototypes were examined by fixing titanium abutments to 112 Mozo-Grau external hexagon implants (MG Osseous®; Mozo-Grau, S.A., Valladolid, Spain). Fracture strength was tested at 30° in two subgroups per screw: one under dynamic loading and the other without prior dynamic loading. Dynamic loading was performed in a single-axis chewing simulator using 150,000 load cycles at 50 N. After normal distribution of obtained data was verified by Kolmogorov-Smirnov test, fracture resistance between samples submitted and not submitted to dynamic loading was compared by the use of Student's t-test. Comparison of fracture resistance among different screw designs was performed by the use of one-way analysis of variance. Confidence interval was set at 95%. RESULTS Fractures occurred in all screws, allowing easy retrieval. Screw Prototypes 2, 5 and 6 failed during dynamic loading and exhibited statistically significant differences from the other prototypes. CONCLUSION Prototypes 2, 5 and 6 may offer a useful protective mechanism during occlusal overload in immediate loaded implants. PMID:25932315

  4. 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.

  5. The Endovascular Management of Iliac Artery Aneurysms

    SciTech Connect

    Stroumpouli, Evangelia; Nassef, Ahmed; Loosemore, Tom; Thompson, Matt; Morgan, Robert; Belli, Anna-Maria

    2007-11-15

    Background: Isolated aneurysms of the iliac arteries are uncommon. Previously treated by conventional surgery, there is increasing use of endografts to treat these lesions. Purpose: The purpose of this study was to assess the efficacy, safety, and durability of the stent-grafts for treatment of iliac artery aneurysms (IAAs). The results of endografting for isolated IAAs over a 10-year period were analyzed retrospectively. The treatment methods differed depending on the anatomic location of the aneurysms. Twenty-one patients (1 woman, 20 men) underwent endovascular stent-graft repair, with one procedure carried out under emergency conditions after acute rupture. The mean aneurysm diameter was 4.6 cm.Results:The procedural technical success was 100%. There was zero 30-day mortality. Follow-up was by interval CT scans. At a mean follow-up of 51.2 months, the stent-graft patency rate was 100%. Reintervention was performed in four patients (19%): one patient (4.7%) with a type I endoleak and three patients (14.3%) with type II endoleaks.Conclusion:We conclude that endovascular repair of isolated IAAs is a safe, minimally invasive technique with low morbidity rates. Follow-up results up to 10 years suggest that this approach is durable and should be regarded as a first treatment option for appropriate candidates.

  6. 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

  7. Posterior iliac offset: description of a new radiological measurement of sacroiliac joint instability.

    PubMed

    Tonne, B M; Kempton, L B; Lack, W D; Karunakar, M A

    2014-11-01

    The purpose of this study was to describe the radiological characteristics of a previously unreported finding: posterior iliac offset at the sacroiliac joint and to assess its association with pelvic instability as measured by initial displacement and early implant loosening or failure. Radiographs from 42 consecutive patients with a mean age of 42 years (18 to 77; 38 men, four women) and mean follow-up of 38 months (3 to 96) with Anteroposterior Compression II injuries, were retrospectively reviewed. Standardised measurements were recorded for the extent of any diastasis of the pubic symphysis, widening of the sacroiliac joint, static vertical ramus offset and a novel measurement (posterior offset of the ilium at the sacroiliac joint identified on axial CT scan). Pelvic fractures with posterior iliac offset exhibited greater levels of initial displacement of the anterior pelvis (anterior sacroiliac widening, pubic symphysis diastasis and static vertical ramus offset, p < 0.001,0.034 and 0.028, respectively). Pelvic fractures with posterior ilium offset also demonstrated higher rates of implant loosening regardless of fixation method (p = 0.05). Posterior offset of the ilium was found to be a reliable and reproducible measurement with substantial inter-observer agreement (kappa = 0.70). Posterior offset of the ilium on axial CT scan is associated with greater levels of initial pelvic displacement and early implant loosening. PMID:25371470

  8. Planning screw insertion trajectory in lumbar spinal fusion using pre-operative CT images.

    PubMed

    Daemi, N; Ahmadian, A; Mirbagheri, A; Ahmadian, A H; Saberi, H; Amidi, F; Alirezaie, J

    2015-08-01

    Spinal fusion permanently connects two or more vertebrae in spine to improve stability, correct a deformity or reduce pain by immobilizing the vertebrae through pedicle screw fixation. Pedicle screws should be inserted very carefully to prevent possible irrecoverable damages to the spinal cord. Surgeons use CT/fluoroscopic images to find how to insert the screws safely. However, there is still human error, as determining precise trajectory in 3D space is difficult because of asymmetric structure of pedicle. In this study we attempt to propose a shape based method to help the surgeons to find the more accurate and safe path for screw insertion that minimizes the risk or invasiveness of the surgery using pre-operative CT images. We extracted two features for insertion paths from CT images, named "safety margin" and "pedicular screw fixation strength". By using weighted k-means different paths were clustered and compared with each other. Results of comparison between those paths obtained from surgeon's pre-operative planning, intra operative and the proposed method proves a great improvement on the rate of success in reaching a suitable insertion trajectory by using our method. It is observed that the risk of damage in intra operative stage can be potentially high and it can be reduced considerably by using the proposed planning approach. PMID:26737081

  9. Technical tips: dualplate fixation technique for comminuted proximal humerus fractures.

    PubMed

    Choi, Sungwook; Kang, Hyunseong; Bang, Hyeongsig

    2014-08-01

    The authors report dualplate fixation technique for providing stable fixation in comminuted proximal humerus fractures. This technique has been used for proximal humerus fractures with metaphyseal comminution and provides excellent anatomical reduction and neck shaft angle (NSA). The recently locking plate is clinically more widely used due to its small size, low rigidity, high elasticity, and biomechanical properties such as fixed initial angle and rotational stability. However, in severely comminuted complex type proximal metaphyseal humerus fractures, the use of locking plate alone does not provide stable fixation, leading to complications such as varus collapse, anterior-posterior angulation, screw cutout, nonunion, malunion, and metal failure. Therefore, a more robust and enhanced fixation method, the dual plating technique using the locking compression plate (Proximal Humeral Internal Locking System and Variable Angle Locking Compression Plate) was developed. PMID:24813097

  10. Open reduction and internal fixation of radial head fractures.

    PubMed

    Iacobellis, C; Visentin, A; Aldegheri, R

    2012-05-01

    This study examines 32 patients operated for radial head fractures, mean age 48.7 years (range 26-76 years), Mason type II in 25 cases and Mason type III with 3 main fragments in 7 cases. Fractures were surgically reduced and fixed with Herbert's (12 cases) or Osteomed (20 cases) cannulated screws. The latter have a head that is <1 mm high and are only threaded distally. Both types of screw provide compression across the fracture. In Mason type II cases, the mean MEPS score was 98.4 and the DASH score 6.8. In Mason type III cases, MEPS was 99.3 and DASH 9.5. We believe that fixation can be carried out with screws alone, which are less invasive, and that the screw heads should preferably be completely buried, to avoid stiffness in prono-supination. In addition, suturing of the annular ligament and the joint capsule is made easier by the reduced invasiveness of screws. Screw treatment is effective in non-comminuted fractures of the radial head. PMID:22447441

  11. 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 justification" of intraoperative neuromonitoring"... is the perception that the safety and efficacy of pedicle screw fixation are enhanced..." (Resnick et al. 2005b). However in summarizing a massive (over 1000 papers taken from the National Library of Medicine), contemporary, literature review spanning nearly a decade (1996 to 2003), this invited panel (Resnick et al. 2005b) recognized that the evidence-based documents contributing to the parts related to pedicle screw fixation and neuromonitoring were "... full of potential sources of error ..." and lacked appropriate, randomized, prospective studies for formulating rigid standards and guidelines. Nevertheless, current trends support the routine use and clinical utility of these neuromonitoring techniques. In particular free-run and triggered EMG have been well recognized in numerous publications for improving both the accuracy and safety of pedicle screw implantation. Currently, treatment with pedicle screw instrumentation routinely involves all levels of the spine - lumbosacral, thoracic, and cervical. Significant historical events, various neuromonitoring modalities, intraoperative alarm criteria, clinical efficacy, current trends, and caveats related to pedicle screw stimulation along the entire vertebral column will be reviewed. PMID:22808751

  12. 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

  13. Vertebral body compression fracture after percutaneous pedicle screw removal in a young man.

    PubMed

    Cappuccio, M; De Iure, F; Amendola, L; Martucci, A

    2015-12-01

    Hazards and potential complications associated with pedicle screw insertions have been reported. In contrast, complications due to implant removal are rarely described. An unreported case of acute vertebral body compression fracture following pedicle screw removal in a young man occurred during an episode of forceful coughing. Spinal implants need to be removed in cases of complications, pain or tissue irritation, and removal is mandatory when fixation involves L2 or the lower segments. Complications associated with spinal implant removal are rare but possible, and patients must be informed of this potential risk. PMID:25417175

  14. Percutaneous Endoluminal Bypass of Iliac Aneurysms with a Covered Stent

    SciTech Connect

    Ruebben, Alexander; Tettoni, Serena; Muratore, Pierluigi; Rossato, Dennis; Savio, Daniele; Rabbia, Claudio

    1998-07-15

    To evaluate the feasibility of percutaneous treatment of iliac aneurysms, a covered stent was inserted in nine men suffering from common iliac artery aneurysms (six cases), external iliac aneurysms (one case), or pseudoaneurysms (two cases). Placement of the stent was successful in all patients. In one patient, an endoprosthesis thrombosed after 15 days, but was successfully treated by thrombolysis and additional stent placement. At the follow-up examinations (mean period 22 months) all stent-grafts had remained patent. No late leakage or stenosis was observed.

  15. Benefit and accuracy of intraoperative 3D-imaging after pedicle screw placement: a prospective study in stabilizing thoracolumbar fractures

    PubMed Central

    Mittlmeier, Thomas; Gierer, Philip; Harms, Christoph; Gradl, Georg

    2009-01-01

    Internal fixation is the established dorsal standard procedure for the treatment of thoracolumbar fractures. The main problem of the procedure is the false positioning of the pedicle screws. The exact determination of pedicle screws has up to now only been possible through postoperative computed tomography. This study was intended to clarify the diagnostic value of intraoperative 3D scans after pedicle screw implantation in thoracolumbar spine surgery. The direct intraoperative consequences of the 3D scans are reported and the results of the 3D scans are compared with the postoperative computed tomography images. Intraoperative 3D scans were prospectively carried out from June 2006 to October 2008 on 95 patients with fractures of the thoracolumbar spine that have been treated with internal fixation. Screws positions were categorised intraoperatively, screws in relevant malposition were repositioned immediately. A computed tomography of the involved spinal section was carried out postoperatively for all patients. The positions of the pedicle screws were determined and compared in the axial reconstructions of both procedures. Four hundred and fourteen pedicles with enclosed screws were evaluated by the 3D scans. The time needed for carrying out the 3D scan amounts to an average of 8.2 min. Eleven screws (2.7%) in ten patients were primarily intraoperatively repositioned on the basis of the 3D scan evaluation. Two of 95 patients had to have false positions of the screws revised secondarily following evaluation of the computed tomographies. The secondary postoperative revision rate of the patients amounts to 2.1%. In relation to the number of screws, this is a revision rate of 0.5%. The postoperative computed tomographies showed 323 pedicles without cortical penetration by the screws (78.0%). Ninety-one screws penetrated the pedicle wall (22%). It was possible to postoperatively compare the position classifications of 406 pedicle screws. The CT showed 378 correct screw positions, while 28 screws were positioned falsely. On the basis of the 3D scans, 376 of 378 correct positions were correctly assessed. Twenty-one of 28 false positions could be correctly classified. The sensitivity of all 3D scans reached 91.3% and the specificity 98.2%. The position of 97.8% of the pedicle screws was correctly recognised by the intraoperative 3D scan. Nine screws were classified falsely (2.2%). The comparison of the classification results showed significantly higher error findings by the 3D scan in the spinal section T1–10 (P = 0.014). The image quality of the 3D scan correlates significantly with the width of the scanned pedicle, with the body mass index, the scanned spinal section and the extent of the fixation assembly. 3D scans showed a high accuracy in predicting pedicle screw position. Primary false placement of screws and primary neurovascular damage cannot be avoided. But intraoperative evaluation of the 3D scans resulted in a primary revision rate of 2.7% of the pedicle screws and we could lower the secondary revision rate to 0.5%. PMID:19513764

  16. Benefit and accuracy of intraoperative 3D-imaging after pedicle screw placement: a prospective study in stabilizing thoracolumbar fractures.

    PubMed

    Beck, Markus; Mittlmeier, Thomas; Gierer, Philip; Harms, Christoph; Gradl, Georg

    2009-10-01

    Internal fixation is the established dorsal standard procedure for the treatment of thoracolumbar fractures. The main problem of the procedure is the false positioning of the pedicle screws. The exact determination of pedicle screws has up to now only been possible through postoperative computed tomography. This study was intended to clarify the diagnostic value of intraoperative 3D scans after pedicle screw implantation in thoracolumbar spine surgery. The direct intraoperative consequences of the 3D scans are reported and the results of the 3D scans are compared with the postoperative computed tomography images. Intraoperative 3D scans were prospectively carried out from June 2006 to October 2008 on 95 patients with fractures of the thoracolumbar spine that have been treated with internal fixation. Screws positions were categorised intraoperatively, screws in relevant malposition were repositioned immediately. A computed tomography of the involved spinal section was carried out postoperatively for all patients. The positions of the pedicle screws were determined and compared in the axial reconstructions of both procedures. Four hundred and fourteen pedicles with enclosed screws were evaluated by the 3D scans. The time needed for carrying out the 3D scan amounts to an average of 8.2 min. Eleven screws (2.7%) in ten patients were primarily intraoperatively repositioned on the basis of the 3D scan evaluation. Two of 95 patients had to have false positions of the screws revised secondarily following evaluation of the computed tomographies. The secondary postoperative revision rate of the patients amounts to 2.1%. In relation to the number of screws, this is a revision rate of 0.5%. The postoperative computed tomographies showed 323 pedicles without cortical penetration by the screws (78.0%). Ninety-one screws penetrated the pedicle wall (22%). It was possible to postoperatively compare the position classifications of 406 pedicle screws. The CT showed 378 correct screw positions, while 28 screws were positioned falsely. On the basis of the 3D scans, 376 of 378 correct positions were correctly assessed. Twenty-one of 28 false positions could be correctly classified. The sensitivity of all 3D scans reached 91.3% and the specificity 98.2%. The position of 97.8% of the pedicle screws was correctly recognised by the intraoperative 3D scan. Nine screws were classified falsely (2.2%). The comparison of the classification results showed significantly higher error findings by the 3D scan in the spinal section T1-10 (P = 0.014). The image quality of the 3D scan correlates significantly with the width of the scanned pedicle, with the body mass index, the scanned spinal section and the extent of the fixation assembly. 3D scans showed a high accuracy in predicting pedicle screw position. Primary false placement of screws and primary neurovascular damage cannot be avoided. But intraoperative evaluation of the 3D scans resulted in a primary revision rate of 2.7% of the pedicle screws and we could lower the secondary revision rate to 0.5%. PMID:19513764

  17. Treatment of Palatal Fractures by Osteosynthesis with 2.0-mm Locking Plates as External Fixator

    PubMed Central

    Cienfuegos, Ricardo; Sierra, Eduardo; Ortiz, Benjamin; Fernández, Gerardo

    2010-01-01

    Treatment options for palatal fractures range from orthodontic braces, acrylic bars, and arch bars for maxillomandibular fixation to internal fixation, with plates and screws placed under the palate mucosa and periosteum, together with pyriform aperture or alveolar plating plus buttress reconstruction. Forty-five patients, ages 4 to 56, were treated using medium- or high-profile locking plates placed over the palatal mucosa as an external fixator for palatal fractures, together with treatment for other associated facial fractures. In open fractures, plates were placed after approximating the edges of the mucosal wounds. Plates and screws for palate fixation were removed at 12 weeks, when computed tomography scans provided evidence of fracture healing. All palatal fractures healed by 12 weeks, with no cases of mucosal necrosis, bone exposure, fistulae, or infections. This approach achieves adequate stability, reduces the risk of bone and mucosal necrosis, and promotes healing of mucosal wounds in case of open fractures. PMID:22132261

  18. Polypyrrole coating on poly-(lactide/glycolide)-?-tricalcium phosphate screws enhances new bone formation in rabbits.

    PubMed

    Zhao, Ming-Dong; Björninen, Miina; Cao, Lu; Wang, Hui-Ren; Pelto, Jani; Li, Xiang-Qian; Hyttinen, Jari; Jiang, Yun-Qi; Kellomäki, Minna; Miettinen, Susanna; Sándor, George K; Seppänen, Riitta; Haimi, Suvi; Dong, Jian

    2015-01-01

    Polypyrrole (PPy) has gained interest as an implant material due to its multifunctional properties and its high compatibility with several cell and tissue types. For the first time, the biocompatibility and osteointegration of PPy coating, incorporated with chondroitin sulfate (CS), were studied in vivo by implanting PPy-coated bioabsorbable bone fixation composite screws of poly-(lactide/glycolide) copolymer (PLGA) and ?-tricalcium phosphate (TCP) into New Zealand white rabbits. Uncoated bioabsorbable polymer composite screws and commercially available stainless steel cortical screws were used as reference implants. The rabbits were euthanized 12 and 26 weeks after the implantation. The systemic effects were evaluated from food and water consumption, body weight, body temperature, clinical signs, blood samples, internal organ weights, and histological examination. Local effects were studied from bone tissue and surrounding soft tissue histology. New bone formation was evaluated by micro-computed tomography, tetracycline labeling and torsion tests. Torsion tests were performed in order to capture the peak value of the torsion force during the course of the screw's loosening. The coated screws induced significantly more bone formation than the uncoated screws. In addition, none of the implants induced any systemic or local toxicity. The results suggest that PPy is biocompatible with bone tissue and is a potential coating for enhancing osteointegration in orthopedic implants. PMID:26610717

  19. Fixation of basicervical and related fractures

    PubMed Central

    2009-01-01

    We prospectively studied 42 patients in order to identify a group of proximal femoral fractures having liability for axial and rotational instability, and to present results of their fixation using the dynamic hip screw (DHS) with derotation screw (DRS). At 12 months postoperatively, patients were functionally evaluated and the radiological outcome was analysed. All fractures united within an average period of 11.5 weeks. The mean sliding distance was 5.5 mm and mean shortening of the limbs was 2 mm. According to the criteria of Kyle et al. (J Bone Joint Surg [Am] 61-A:216–221), 39 patients obtained excellent results, two good and one fair. We conclude that the AO types B2.1, A1.1, A2.1, A2.2 and A2.3 have a common instability denominator and therefore should be treated alike. The sliding component of the DHS allows solid fixation of the two major fragments in two planes and the DRS in the third plane. PMID:19475407

  20. Comparison of Biomechanical Characteristics and Pelvic Ring Stability Using Different Fixation Methods to Treat Pubic Symphysis Diastasis: A Finite Element Study.

    PubMed

    Yao, Feng; He, Yu; Qian, Hebu; Zhou, Dongsheng; Li, Qinghu

    2015-12-01

    The intention of this study was to compare the biomechanical characteristics using 5 internal fixation methods used clinically to stabilize a pubic symphysis diastasis (PSD, Tile type B1).A 3-dimensional finite element model of PSD was simulated using 5 implants, including single superior plate (Single-Plate), superior and anterior plate (Dual-Plate), single cannulated screw (Single-Screw), crossed dual cannulated screws (Cross-Screw), and parallel dual cannulated screws (Para-Screw). Three loads were distributed in all models, including dual-leg standing, single-leg stance, and rotation. To evaluate the biomechanical properties, the construct stiffness, the stress distribution, and the von Misses stress were recorded and analyzed. To evaluate pelvic ring stability, the micromotion of the pubic symphysis and iliosacral joint was analyzed.Disruption of pubic symphysis dramatically decreased the pelvic ring stability. Cross-screw and Para-Screw showed higher stiffness than other methods. All implants endured the maximum von Misses stress under single-leg stance. For Plate-Screw system, the maximum stress occurred at a place where it strides over pubic symphysis and adjacent Plate-Screw interface. The single implant and Para-Screw had a tendency to fail. Para-Screw showed the best fixation effect under dual-leg conditions. Cross-screw showed superior antishearing force capacity under single-leg stance. Dual-Plate provided maximum antihorizontal rotation. Para-Screw provided the maximum stabilization for the posterior pelvic ring.This study showed the biomechanical advantages of dual-implant for PSD only from the finite element view. The Para-Screw provided high construct stiffness under 3 load conditions. The single implant and Para-Screw had a tendency to fail. The better anterior and posterior pelvic stabilization were obtained by the dual-implant fixation than other methods. Therefore, the Cross-Screw and Dual-Plate fixation methods should be preferred in the treatment of pubic symphysis from the finite element view. PMID:26656353

  1. Mechanical testing of a device for subcutaneous internal anterior pelvic ring fixation versus external pelvic ring fixation

    PubMed Central

    2014-01-01

    Background Although useful in the emergency treatment of pelvic ring injuries, external fixation is associated with pin tract infections, the patient’s limited mobility and a restricted surgical accessibility to the lower abdomen. In this study, the mechanical stability of a subcutaneous internal anterior fixation (SIAF) system is investigated. Methods A standard external fixation and a SIAF system were tested on pairs of Polyoxymethylene testing cylinders using a universal testing machine. Each specimen was subjected to a total of 2000 consecutive cyclic loadings at 1 Hz with sinusoidal lateral compression/distraction (+/?50 N) and torque (+/? 0.5 Nm) loading alternating every 200 cycles. Translational and rotational stiffness were determined at 100, 300, 500, 700 and 900 cycles. Results There was no significant difference in translational stiffness between the SIAF and the standard external fixation when compared at 500 (p?=?.089), 700 (p?=?.081), and 900 (p?=?.266) cycles. Rotational stiffness observed for the SIAF was about 50 percent higher than the standard external fixation at 300 (p?=?.005), 500 (p?=?.020), and 900 (p?=?.005) cycles. No loosening or failure of the rod-pin/rod-screw interfaces was seen. Conclusions In comparison with the standard external fixation system, the tested device for subcutaneous internal anterior fixation (SIAF) in vitro has similar translational and superior rotational stiffness. PMID:24684828

  2. An Articulating Tool for Endoscopic Screw Delivery

    E-print Network

    Petrzelka, Joseph Edward

    This paper describes the development of an articulating endoscopic screw driver that can be used to place screws in osteosynthetic plates during thoracoscopic surgery. The device is small enough to be used with a 12 mm ...

  3. Biomechanical evaluation of a new cross-pin technique for the fixation of different sized bone-patellar tendon-bone grafts.

    PubMed

    Zantop, Thore; Welbers, Barbara; Weimann, Andre; Rümmler, Markus; Hedderich, Jürgen; Musahl, Volker; Petersen, Wolf

    2004-11-01

    To overcome the disadvantages of interference-screw fixation of bone-patellar tendon-bone (BPTB) grafts, new fixation techniques for anterior cruciate ligament (ACL) grafts using biodegradable pins have been developed. The hypothesis of the present study was that cross-pin fixation techniques provide a primary stability that is comparable to that of interference screws. A biomechanical in vitro study was discussed. Human BPTB grafts of 8, 9 and 10 mm diameter were fixed in bovine knees with biodegradable cross pins (diameter: 2.0, 2.7 or 3.2 mm) or biodegradable interference screws. Stiffness and ultimate load were evaluated. For 9 and 10 mm BPTB grafts, no statistically significant difference in maximum load and stiffness was found between the four fixation techniques tested. For 8 mm bone blocks the maximum load of the 3.2 mm pins (274.2 N) was significantly lower than for the 2.0 mm pins (479.8 N) and the interference screws (504.0 N). Predominant failure mode in this group was bone-block fracture. Thicker grafts (9 and 10 mm) fixed with the 2.0 mm pins predominantly failed by implant fracture. Femoral fixation of 8, 9 and 10 mm BPTB grafts using cross pins leads to biomechanical properties that are comparable to biodegradable interference screws when tested by a single-cycle load to failure. Cross pins provide a rigid fixation for 9 and 10 mm BPTB grafts. PMID:15221210

  4. Modified fixation of acrylic cranioplasty in the setting of titanium allergy.

    PubMed

    Sinkin, Jeremy C; Loftin, Sara; Baker, Stephen B

    2015-01-01

    Cranioplasty can be performed using a number of materials ranging from autologous tissue to metallic or acrylic alloplastic implants. In this report, we present a unique case of revision cranioplasty in a patient with titanium allergy using a prefabricated, custom-made polymethylmethacrylate implant and a modified fixation technique without plates or screws. PMID:25565231

  5. Surgical Treatment of Calcaneal Avulsion Fracture in Elderly Patients Using Cannulated Cancellous Screws and Titanium Wire.

    PubMed

    Miyamura, Satoshi; Ota, Haruka; Okamoto, Michio; Namba, Jiro; Yamamoto, Koji

    2016-01-01

    Avulsion fractures of the calcaneus are relatively uncommon and are seen most frequently in elderly or osteoporotic patients. A surgical method that avoids displacement of the avulsed fragment after fixation has not been developed. We report the cases of 3 patients (a 73-year-old male, an 85-year-old male, and an 81-year-old female) treated by open reduction and internal fixation using titanium wire and cannulated cancellous screws. The posterior approach was used by way of a vertical midline incision. The fracture was fixed with 2 screws, and then a titanium wire was passed through the holes of the cannulated screws. A small incision on the lateral side of planter was added for the exit and return of the wire. The wire knot was bent inside the proximal Achilles tendon bursa in 2 patients and was directed to the plantar side in 1 to avoid irritation. Bony union was achieved without repeat displacement of the fragment in all 3 patients. Normal ankle function was restored, and the patients recovered the activities of daily living almost to the original level. Although an additional plantar incision is required, this surgical technique provides strong internal fixation. PMID:26440932

  6. Air-Lubricated Lead Screw

    NASA Technical Reports Server (NTRS)

    Perkins, G. S.

    1983-01-01

    Air lubricated lead screw and nut carefully machined to have closely matched closely fitting threads. Compressed air injected into two plenums encircle nut and flow through orifices to lubricate mating threads. Originally developed to position precisely interferometer retroreflector for airborne measurement of solar infrared radiation, device now has positioning accuracy of 0.25 micron.

  7. In vitro biomechanical evaluation of four fixation techniques for distractive–flexion injury stage 3 of the cervical spine

    PubMed Central

    Henriques, Thomas; Cunningham, Bryan W.; Mcafee, Paul C.

    2015-01-01

    Purpose Anterior plate fixation has been reported to provide satisfactory results in cervical spine distractive flexion (DF) injuries stages 1 and 2, but will result in a substantial failure rate in more unstable stage 3 and above. The aim of this investigation was to determine the biomechanical properties of different fixation techniques in a DF-3 injury model where all structures responsible for the posterior tension band mechanism are torn. Methods The multidirectional three-dimensional stiffness of the subaxial cervical spine was measured in eight cadaveric specimens with a simulated DF-3 injury at C5–C6, stabilized with four different fixation techniques: anterior plate alone, anterior plate combined with posterior wire, transarticular facet screws, and a pedicle screw–rod construct, respectively. Results The anterior plate alone did not improve stability compared to the intact spine condition, thus allowing considerable range of motion around all three cardinal axes (p > 0.05). The anterior plate combined with posterior wire technique improved flexion–extension stiffness (p = 0.023), but not in axial rotation and lateral bending. When the anterior plate was combined with transarticular facet screws or with a pedicle screws–rod instrumentation, the stability improved in flexion–extension, lateral bending, and in axial rotation (p < 0.05). Conclusions These findings imply that the use of anterior fixation alone is insufficient for fixation of the highly unstable DF-3 injury. In these situations, the use of anterior fixation combined with a competent posterior tension band reconstruction (e.g. transarticular screws or a posterior pedicle screws–rod device) improves segmental stability. PMID:25742755

  8. Clinical Features and Endovascular Management of Iliac Artery Fibromuscular Dysplasia

    PubMed Central

    Ketha, Siva S.; Bjarnason, Haraldur; Oderich, Gustavo S.; Misra, Sanjay

    2014-01-01

    Purpose To identify the spectrum of clinical presentation of iliac artery fibromuscular dysplasia (FMD) and to evaluate the outcomes of endovascular management of iliac FMD for claudication. Methods and materials All patients in our institution with a diagnosis of FMD between January 1980 and December 2010 were identified. 14 patients were found to have FMD of the iliac arteries. Associated risk factors included hypertension (79%), hyperlipidemia (64%), smoking history (36%), coronary artery disease (21%), diabetes (0 %), and obesity (36%). Results Eight (57%) patients were incidentally found to have iliac FMD on imaging. 6 (43%) patients had life style limiting claudication involving one or both extremities. All 6 patients were reported as mild peripheral arterial disease (PAD) based on ankle brachial index (ABI) measurements (0.7 to 0.9). These six patients underwent 10 endovascular procedures for claudication including angioplasty (n=8) and self-expanding stent placement (n=2). Mean symptom free survival was 56.3 months. Conclusion Iliac FMD may be found incidentally or may present with disabling claudication that is amenable to endovascular treatment. PMID:24768236

  9. Pedicle screw piercer with warning device - A technique to increase accuracy of pedicle screw placement

    PubMed Central

    Bin, Lin; Yong, He; Yang, Xu; Bi, Zhang; Mo, Sha; Zhi-Min, Guo

    2014-01-01

    Background: Pedicle screw fixation has achieved significant popularity amongst spinal surgeons for both single and multilevel spinal fusion. Suboptimal placements of pedicle screws may lead to neurological and vascular complications. There have been many advances in techniques available for navigating through the pedicle; however, these techniques are not without drawbacks. The purpose of this study was to investigate the efficacy and feasibility of the pedicle piercer with warning device. Materials and Methods: Eight normal adult thoracolumbar specimens from cadavers consisting of 80 vertebras (T8–L5) were selected and randomly allocated into four groups. Each group contained 20 vertebra. Group 1 was tested for maximum pressure of the piercer within the vertebrae (F1). Group 2 was tested for maximum pressure of the warning piercer penetrating front cortex of the vertebral body (F2). Group 3 was tested for the maximum pressure of piercer penetrating vertebral body endplate (F3) and pedicle notch (F41, F42). Group 4 was tested for maximum pressure of the piercer penetrating the vertebral lateral cortex (F6), the medial and lateral cortex of pedicle (F51, F52). In the second experiment of this study, 4 normal adult specimens consisting of 40 vertebra and 80 pedicles were used for testing the alarm effects of pedicle piercer. The following indicators were adopted for the tests including true positive/negative, false positive/negative, sensitivity, specificity, availability, Youden index, and diagnostic efficiency. SPSS 16.0 was used for statistical analysis. Results: There were statistically significant differences between F1, and F2, F3, F41, F42, F51, F52 respectively (P < 0.05). F1 = 8.970 ± 0.2698, F3 = 13.055 ± 0.6718. We found that the threshold value of piercer warning was from 9.6 to 12.3 Kgf. Sensitivity was 92.31%, specificity was 95.12%, usability was 87.45%, Youden index was 87.43% and diagnostic efficiency was 92.5% respectively. Conclusion: Warning piercer is a safe, simple, sensitive device for detecting pedicle breach during regular pedicle screw placement surgery. PMID:25404764

  10. 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.

  11. 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

  12. Designs and techniques that improve the pullout strength of pedicle screws in osteoporotic vertebrae: current status.

    PubMed

    Shea, Thomas M; Laun, Jake; Gonzalez-Blohm, Sabrina A; Doulgeris, James J; Lee, William E; Aghayev, Kamran; 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

  13. [Bone fixation of tumor endoprostheses with cast-on spherules of a cobalt-base alloy].

    PubMed

    Gottsauner-Wolf, F; Plenk, H

    1987-06-01

    Special tumor endoprostheses manufactured from cobalt-base alloy with cast-on globules upon the intramedullary shaft and two paracortical flanges for screw fixation can be stabilized at the ends of long bones without using bone cement. Three such implants, retrieved in clinically stable condition after 3 months (proximal tibia), 5 months (distal humerus), and 13 months (distal femur), were investigated microscopically: new bone was found immediately adjacent to the porous surface structures and the fixation screws in many areas. The contribution of bone fragments originating from the preparation of the implant bed to this bone reaction was extremely slight. On the other hand, fibrous tissue layers and a foreign body reaction were found on the remaining surfaces, which may have been related to the compatibility of the implant material and must therefore be regarded as detrimental for the long-term prognosis concerning the fixation of such implants. PMID:3627796

  14. Are allogenic or xenogenic screws and plates a reasonable alternative to alloplastic material for osteosynthesis--a histomorphological analysis in a dynamic system.

    PubMed

    Jacobsen, C; Obwegeser, J A

    2010-12-01

    Despite invention of titanium and resorbable screws and plates, still, one of the main challenges in bone fixation is the search for an ideal osteosynthetic material. Biomechanical properties, biocompatibility, and also cost effectiveness and clinical practicability are factors for the selection of a particular material. A promising alternative seems to be screws and plates made of bone. Recently, xenogenic bone pins and screws have been invented for use in joint surgery. In this study, screws made of allogenic sheep and xenogenic human bone were analyzed in a vital and dynamic sheep-model and compared to conventional titanium screws over a standard period of bone healing of 56 days with a constant applied extrusion force. Biomechanical analysis and histomorphological evaluation were performed. After 56 days of insertion xenogenic screws made of human bone showed significantly larger distance of extrusion of on average 173.8 ?m compared to allogenic screws made of sheep bone of on average 27.8 and 29.95 ?m of the titanium control group. Severe resorption processes with connective tissue interposition were found in the histomorphological analysis of the xenogenic screws in contrast to new bone formation and centripetal vascularization of the allogenic bone screw, as well as in processes of incorporation of the titanium control group. The study showed allogenic cortical bone screws as a substantial alternative to titanium screws with good biomechanical properties. In contrast to other reports a different result was shown for the xenogenic bone screws. They showed insufficient holding strength with confirmative histomorphological signs of degradation and insufficient osseointegration. Before common clinical use of xenogenic osteosynthetic material, further evaluation should be performed. PMID:20813368

  15. 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.

  16. 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.

  17. 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.

  18. Hot Topics in Biomechanics: Hip Fracture Fixation.

    PubMed

    Olson, Steven A; Schemitsch, Geoffrey; Morwood, Michael; Schemitsch, Emil; Russell, Thomas A; Latta, Loren L

    2015-12-01

    Geriatric hip fractures continue to increase in frequency as the population ages, and intertrochanteric femur fractures are a significant part of these injuries. Plate fixation for intertrochanteric fractures of the proximal femur has been in use for many years, and application of the sliding hip screw has also been a mainstay of treatment. Recent data suggest there may be a benefit to using implants that add rotational stability to the proximal intertrochanteric fragment. Although preliminary data are promising, there is need for improved investigation to demonstrate the benefit of these new implant designs. In this era of increasing emphasis on cost, quality, and value, better data are needed to help clinicians determine the best therapy for their patients. PMID:26584258

  19. Treatment of Nonunion of Scaphoid Waist with Ni-Ti Shape-Memory Alloy Connector and Iliac Bone Graft

    NASA Astrophysics Data System (ADS)

    Cao, Lie-Hu; Xu, Shuo-Gui; Wu, Ya-Le; Zhang, Chun-Cai

    2011-07-01

    After fracture, the unique anatomy and blood supply of the scaphoid itself predisposes to nonunion. Scaphoid nonunion presents a formidable challenge to surgeons because of the difficulties for fixation, and the high failure rate after treatment. The Ni-Ti shape-memory alloy can provide compressive stress at the nonunion site, which is the key point for bone healing. Hence, we designed a shape-memory bone connector named arched shape-memory connector (ASC). We conducted a retrospective study looking at the union rate and complications and correlating the outcome of treatment with this device. The study reviewed a cohort of six consecutive patients presenting with scaphoid waist nonunion, who were treated with ASC and iliac cancellous bone grafting at our center from August 2002 to December 2007. The patients with nonunion achieved a 100% union rate. All the patients who achieved union had good pain relief and improved function. Our study demonstrates that scaphoid waist nonunions can be successfully treated by ASC and iliac bone grafting.

  20. Chopart arthrodesis with graft bone from the iliac crest after a traumatic subamputation of the forefoot: surgical technique

    PubMed Central

    Cianforlini, Marco; Marinelli, Mario; Ponzio, Isabella; de Palma, Luigi

    2014-01-01

    We present a 49-year-old man with a traumatic subamputation of the forefoot, associated with lacerated wound in correspondence of the dorsal surface of the right foot, with injuries of tendinous, ligamentous and vascular structures and with the loss of talus head. The patient underwent salvage arthrodesis of the talonavicular and calcanealcuboid joints with graft bone harvested from the iliac crest. The patient was re-evaluated during a clinical and radiographic follow-up. The arthrodesis was consolidated in ?3 months. There were no infectious problems and the patient has resumed normal work activities. At a sixth month follow-up, the patient had returned to work and remained pain free while walking. Early anatomic reduction, stable fixation and ligament reconstruction are essential for a good outcome. Primary arthrodesis is a viable option for severe midfoot fracture dislocations, because it facilitates rehabilitation and functional recovery and obviates the need for a secondary arthrodesis should arthritis arise. PMID:24876372

  1. Sharp Recanalization for Chronic Left Iliac Vein Occlusion

    SciTech Connect

    Ito, Nobutake Isfort, Peter; Penzkofer, Tobias; Grommes, Jochen; Greiner, Andreas; Mahnken, Andreas

    2012-08-15

    Endovascular treatment has emerged as a first-line treatment for venous occlusions, but is sometimes challenging with conventional approaches. This article describes a helpful technique using a Roesch-Uchida needle to cross a chronic occlusion of the iliac vein when conventional techniques have failed.

  2. Bilateral iliac arterial thrombosis in an alpaca (Vicugna pacos) cria

    PubMed Central

    Schaeffer, Joshua W.; Middleton, John R.; Bozynski, Chantelle C.; Shaw, Daniel P.

    2012-01-01

    A 3-month-old male alpaca was presented for acute onset of non-weight-bearing left hind limb lameness. Antemortem diagnostics revealed a mass to the right of the urinary bladder and no blood flow in the left femoral artery. Necropsy revealed bilateral iliac arterial thrombi and an abscess near the urinary bladder. PMID:23450866

  3. Endovascular Stent-Grafting for Infected Iliac Artery Pseudoaneurysms

    SciTech Connect

    Sanada, Junichiro Matsui, Osamu; Arakawa, Fumitaka; Tawara, Mari; Endo, Tamao; Ito, Hiroshi; Ushijima, Satoshi; Endo, Masamitsu; Ikeda, Masahiro; Miyazu, Katsuyuki

    2005-01-15

    We report two cases of acutely infected pseudoaneurysms of the iliac arteries, successfully treated with endovascular stent-grafting. Two patients underwent stent-graft treatment for erosive rupture of the iliac artery caused by surrounding infection. The first case is that of a 61-year-old man who had undergone Miles' operation for an advanced rectal cancer. Postoperatively, he developed intrapelvic abscess formation, from which methicillin-resistant Staphylococcus aureus was cultured, followed by rupture of the right external iliac artery. The second case is that of a 60-year-old man who had a pseudoaneurysm of the left common iliac artery, which was contiguous with a left psoas muscle abscess, from which Streptococcus agalactiae was cultured. Both patients were successfully treated with only a stent-graft and antibiotic therapy, and remained symptom-free 12 months and 10 months later. Although endovascular stent-grafting should not be considered standard therapy for infected aneurysms, our cases suggest that it can result in repair of infected aneurysms even in the uncontrolled active stage.

  4. Percutaneous Endovascular Treatment of Chronic Iliac Artery Occlusion

    SciTech Connect

    Carnevale, F. C. De Blas, Mariano; Merino, Santiago; Egana, Jose M.; Caldas, Jose G.M.P.

    2004-09-15

    Purpose: To evaluate the clinical and radiological long-term results of recanalization of chronic occluded iliac arteries with balloon angioplasty and stent placement.Methods: Sixty-nine occluded iliac arteries (mean length 8.1 cm; range 4-16 cm) in 67 patients were treated by percutaneous transluminal angioplasty and stent placement. Evaluations included clinical assesment according to Fontaine stages, Doppler examinations with ankle-brachial index (ABI) and bilateral lower extremity arteriograms. Wallstent and Cragg vascular stents were inserted for iliac artery recanalization under local anesthesia. Follow-up lasted 1-83 months (mean 29.5 months).Results: Technical success rate was 97.1% (67 of 69). The mean ABI increased from 0.46 to 0.85 within 30 days after treatment and was 0.83 at the most recent follow-up. Mean hospitalization time was 2 days and major complications included arterial thrombosis (3%), arterial rupture (3%) and distal embolization (1%). During follow-up 6% stenosis and 9% thrombosis of the stents were observed. Clinical improvement occurred in 92% of patients. Primary and secondary patency rates were 75% and 95%, respectively.Conclusion: The long-term patency rates and clinical benefits suggest that percutaneous endovascular revascularization with metallic stents is a safe and effective treatment for patients with chronic iliac artery occlusion.

  5. First Metatarsalphalangeal Joint Arthrodesis: A Retrospective Comparison of Two Methods of Fixation

    PubMed Central

    Rashid, M.A; Parnell, M; Khan, W.S; Khan, A

    2015-01-01

    First metatarsalphalangeal joint arthrodesis is a well established and successful treatment; however there still remains controversy over the best choice of construct. We performed a retrospective study of patients undergoing first metatarsalphalangeal fusion over eighteen months (n=52) using either dorsal non-locking plate with additional compression lag screw fixation or dorsal non-locking plate alone. We found when assessing clinical criteria, patients with dorsal non-locking plates and additional compression lag screw fixation had a significantly higher rate of fusion (100% vs 77.8%), significantly higher rate of fusion within the first two months (55.6% vs 83.3%), significantly earlier time to fusion (52.2 days vs 75.6 days), and significantly lower rate of non-union (0% vs 22.2%). When blindly assessing radiographic criteria, the patients treated with the plate and compression screw had a significantly higher rate of fusion and lower rate of non-union (0% vs 33%). There was no statistically significant difference between the frequencies of complications in the groups. We believe that the interfragmentary compression is a crucial factor in achieving good union rates and recommend the use of non-locking pre-contoured plating with additional interfragmentary compression screw as the fixation method of choice for these procedures. PMID:26587065

  6. Assessment of sagittal split ramus osteotomy rigid internal fixation techniques using a finite element method.

    PubMed

    Albougha, S; Darwich, K; Darwich, M A; Albogha, M H

    2015-07-01

    In this study, finite element analysis (FEA) was used to evaluate nine rigid internal fixation techniques for sagittal split ramus osteotomy. To achieve this, a computed tomography (CT) scan of a healthy patient was obtained and used to generate the geometry of a half-mandible. The geometries of bicortical screws, miniplates, and monocortical screws were designed and combined with the mandible in nine models simulating various techniques. Four models used bicortical screws in various arrangements and four used miniplates of various designs. One model represented a hybrid technique. A load of 500 N was applied to the posterior teeth and FEA was applied. The most stable techniques were the hybrid technique and a single straight miniplate, presenting the least displacement among all models. Bicortical screws, while presenting reasonable stability, showed high strain areas near the anterior ramus ridge, superoposterior to the screws, implying a risk of bone fracture in this area. On the other hand, the T-shaped and double Y-shaped miniplates were associated with high von Mises stresses that would impair their rigidity, especially where angles appeared in their designs. We recommend the use of a single straight miniplate because it provides sufficient stable fixation with minimal risks or disadvantages. PMID:25766461

  7. Assessment of the RIVET fixation system for cranioplasty using the pull-out technique.

    PubMed

    Sakamoto, Yoshiaki; Minabe, Toshiharu; Kato, Tatsuya; Kishi, Kazuo

    2015-03-01

    Cranioplasty using custom-made hydroxyapatite (HAP) ceramic implants is a common procedure to repair skull defects. However, commercially available titanium screws are only minimally stabilized due to characteristic brittleness. We developed the RIVET technique which involves fixing a bioabsorbable plate atop a HAP block using bioabsorbable screws extending beyond both layers, and evaluated fixation strength using the pull-out test and microtomography. Three experimental conditions were compared: a non-RIVET group, RIVET group, and dry skull control group. Pull-out strength significantly differed across groups (non-RIVET group, 1.33 ± 1.21 kgf; RIVET group, 4.46 ± 0.84 kgf; and control group, 6.99 ± 1.14 kgf, P < 0.01). Microtomography of the dry skull control group revealed thread grooves fitted to the screws. The non-RIVET and RIVET groups presented fewer thread grooves than the control group, and the screws did not fit perfectly to the HAP block. However, fixation in the RIVET group was more stable, as the rivet was firmly lodged into the implant. In conclusion, by melting and creating the rivet, pull-out strength can be increased and rigid stabilization of HAP can be obtained. This technique uses commercially available absorbable plate and screws, and thus can be used widely in clinical applications involving HAP blocks with different porosities and thicknesses. PMID:25555895

  8. [The triangular iliac hyperostosis -- the sacro-iliac bony stress phenomenon. 1st part (terminology, definition, morphology) (author's transl)].

    PubMed

    Dihlmann, W

    1976-01-01

    The first part of this article concerning the trianular iliac hyperostosis -- the former so-called osteitis condensans ilii -- deals with the proposed terminology. Tomographs of 40 patients were available. The x-ray morphology and the histology (2 necropsies) are described. PMID:130311

  9. Negative pressure wound therapy and external fixation device: a simple way to seal the dressing.

    PubMed

    Bulla, Antonio; Farace, Francesco; Uzel, André-Pierre; Casoli, Vincent

    2014-07-01

    Negative pressure therapy is widely applied to treat lower limb trauma. However, sealing a negative pressure dressing in the presence of an external fixation device may be difficult and time consuming. Therefore, screws, pins, wires, etc, may preclude the vacuum, preventing the plastic drape to perfectly adhere to the foam. To maintain the vacuum, we tried to prevent air leaking around the screws putting bone wax at the junction between the pins and the plastic drape. This solution, in our hands, avoids air leakage and helps maintain vacuum in a fast and inexpensive way. PMID:24296597

  10. Degradation behaviour of LAE442-based plate-screw-systems in an in vitro bone model.

    PubMed

    Wolters, Leonie; Besdo, Silke; Angrisani, Nina; Wriggers, Peter; Hering, Britta; Seitz, Jan-Marten; Reifenrath, Janin

    2015-04-01

    The use of absorbable implant materials for fixation after bone fracture helps to avoid a second surgery for implant removal and the risks and costs involved. Magnesium (Mg) is well known as a potential metallic material for degradable implants. The aim of the present in vitro study was to evaluate if degradable LAE442-based magnesium plate-screw-systems are suitable candidates for osteosynthesis implants in load-bearing bones. The corrosion behaviour was tested concerning the influence of different surface treatments, coatings and screw torques. Steel plates and screws of the same size served as control. Plates without special treatment screwed on up to a specified torque of 15cNm or 7cNm, NaOH treated plates (15cNm), magnesium fluoride coated plates (15cNm) and steel plates as control (15cNm) were examined in pH-buffered, temperature-controlled SBF solution for two weeks. The experimental results indicate that the LAE442 plates and screws coated with magnesium fluoride revealed a lower hydrogen evolution in SBF solution as well as a lower weight loss and volume decrease in ?-computed tomography (?CT). The nanoindentation and SEM/EDX measurements at several plate areas showed no significant differences. Summarized, the different screw torques did not affect the corrosion behaviour differently. Also the NaOH treatment seemed to have no essential influence on the degradation kinetics. The plates coated with magnesium fluoride showed a decreased corrosion rate. Hence, it is recommended to consider this coating for the next in vivo study. PMID:25686954

  11. Comparison of open versus percutaneous pedicle screw insertion in a sheep model

    PubMed Central

    Ushmaev, A.; Ruecker, A.; Nuechtern, J.; Grossterlinden, L.; Begemann, P. G.; Baeumer, T.; Rueger, J. M.; Briem, D.

    2008-01-01

    Minimally invasive surgery has become more and more important for the treatment of traumatic spine fractures. Besides, some clinical studies, objective data regarding the possible lower damage to the surrounding tissue of the spine is still missing. Here we report a sheep model where we compared a percutaneous versus an open approach for dorsal instrumentation with pedicle screws to the spine. Twelve skeletally mature sheep underwent bilateral pedicle screw fixation at the L4–L6 level. Forty-eight pedicle screws were bilaterally inserted into the pedicles and connected with rods using either an open dorsal standard or a percutaneous approach. Operation time, blood flow, compartment pressure, radiation time, loss of blood, laboratory findings and EMG were evaluated to objectify possible advantages for the percutaneous operation technique. Loss of blood and the distribution of CK-MM as a marker for muscle damage were significantly lower in the percutaneous group. However, radiation time was significantly longer in the percutaneous group. Other parameters like compartment pressure, blood flow and also measurement of the EMG at different time points did not reveal significant differences. Based on the results we found in the present study, percutaneous screw insertion can bring moderate advantages but it should be noted that essential functional deficits to the muscle could not be detected. PMID:18389291

  12. The development and evaluation of individualized templates to assist transoral C2 articular mass or transpedicular screw placement in TARP-IV procedures: adult cadaver specimen study

    PubMed Central

    Li, Xue-Shi; Wu, Zeng-Hui; Xia, Hong; Ma, Xiang-Yang; Ai, Fu-Zhi; Zhang, Kai; Wang, Jian-Hua; Mai, Xiao-Hong; Yin, Qing-Shui

    2014-01-01

    OBJECTIVES: The transoral atlantoaxial reduction plate system treats irreducible atlantoaxial dislocation from transoral atlantoaxial reduction plate-I to transoral atlantoaxial reduction plate-III. However, this system has demonstrated problems associated with screw loosening, atlantoaxial fixation and concealed or manifest neurovascular injuries. This study sought to design a set of individualized templates to improve the accuracy of anterior C2 screw placement in the transoral atlantoaxial reduction plate-IV procedure. METHODS: A set of individualized templates was designed according to thin-slice computed tomography data obtained from 10 human cadavers. The templates contained cubic modules and drill guides to facilitate transoral atlantoaxial reduction plate positioning and anterior C2 screw placement. We performed 2 stages of cadaveric experiments with 2 cadavers in stage one and 8 in stage two. Finally, guided C2 screw placement was evaluated by reading postoperative computed tomography images and comparing the planned and inserted screw trajectories. RESULTS: There were two cortical breaching screws in stage one and three in stage two, but only the cortical breaching screws in stage one were ranked critical. In stage two, the planned entry points and the transverse angles of the anterior C2 screws could be simulated, whereas the declination angles could not be simulated due to intraoperative blockage of the drill bit and screwdriver by the upper teeth. CONCLUSIONS: It was feasible to use individualized templates to guide transoral C2 screw placement. Thus, these drill templates combined with transoral atlantoaxial reduction plate-IV, may improve the accuracy of transoral C2 screw placement and reduce related neurovascular complications. PMID:25518033

  13. Aneurysm-osteoarthritis syndrome with visceral and iliac artery aneurysms

    PubMed Central

    van der Linde, Denise; Verhagen, Hence J. M.; Moelker, Adriaan; van de Laar, Ingrid M. B. H.; Van Herzeele, Isabelle; De Backer, Julie; Dietz, Harry C.; Roos-Hesselink, Jolien W.

    2014-01-01

    Objective Aneurysms-osteoarthritis syndrome (AOS), caused by SMAD3 mutations, is a recently described autosomal-dominant syndrome characterized by arterial aneurysms, tortuosity, and aortic dissections in combination with osteoarthritis. Our objective was to evaluate the AOS-related vascular consequences in the visceral and iliac arteries and raise awareness for this aggressive syndrome among vascular specialists. Methods All AOS patients were monitored regularly according to our clinical AOS protocol. The study included those with one or more visceral aneurysms or tortuosity, or both. Clinical and surgical data were obtained from record abstraction. Results The study included 17 AOS patients (47% men) aged 47 ± 13 years. A total of 73 aneurysms were encountered, of which 46 were located in the abdomen. The common iliac artery was most commonly affected (37%), followed by the superior mesenteric artery (15%), celiac trunk (11%), and splenic artery (9%). Rapid aneurysm growth ?1 year was found in three arteries (gastric, hepatic, and vertebral artery). Furthermore, arterial tortuosity was noted in 94% of patients. Four patients underwent six elective (endo) vascular interventions for aneurysms in the iliac, hepatic, gastric, or splenic artery, without major perioperative or postoperative complications. Conclusions AOS predisposes patients to widespread visceral and iliac artery aneurysms and extreme arterial tortuosity. Early elective aneurysm repair should be considered because the risk of aneurysm rupture is estimated to be very high and elective (endo) vascular interventions were not complicated by fragility of arterial tissue. Given the aggressive behavior of AOS, it is of utmost importance that vascular specialists are aware of this new syndrome. PMID:22975338

  14. Emergency Endovascular 'Bridge' Treatment for Iliac-Enteric Fistula

    SciTech Connect

    Franchin, Marco; Tozzi, Matteo; Piffaretti, Gabriele; Carrafiello, Gianpaolo; Castelli, Patrizio

    2011-10-15

    Aortic aneurysm has been reported to be the dominant cause of primary iliac-enteric fistula (IEF) in >70% of cases [1]; other less common causes of primary IEF include peptic ulcer, primary aortitis, pancreatic pseudocyst, or neoplastic erosion into an adjacent artery [2, 3]. We describe an unusual case of IEF managed with a staged approach using an endovascular stent-graft as a 'bridge' in the emergency setting to optimize the next elective definitive excision of the lesion.

  15. Fluorescence in iliac artery wall of rabbit induced by AIPc

    NASA Astrophysics Data System (ADS)

    Corbani, Elaine A.; Rodrigues, Katia C.; Hage, Raduan; Silveira, Landulfo, Jr.; Cardoso, Maria A. G.; Zangaro, Renato A.; Pacheco, Marcos T. T.

    2000-11-01

    The aim of this work was to verify the Al-Phthalocyanine (AlPc) absorption in iliac artery wall of a rabbit, through transadventitial fluorescence measurement. Two Norfolk male rabbits, weighing 3.5 kg were used. The iliac artery was dissected and isolated. The artery was then clamped in two points with simple ligatures spaced 1.5 cm. The experiment was made in three phases, with acquisition of several fluorescence spectra in different points of the iliac artery. Firstly was measured the pre and post clamping transadventitial fluorescence without the presence of the photosensitizer. On the second phase, the AlPc, 2.5 (mu) M in 50 (mu) L solution, was injected locally into the clamped region and fluorescence spectra were collected in t=0 minutes and t=15 minutes. Finally, 30 minutes from the beginning of the experiment the clamping was removed, the blood flow restarted into the artery, and the fluorescence spectra was collected in t=5 minutes and t=10 minutes. The excitation was made using an Argon Laser (Stabilite 2017-Spectra Physics), operating in 488nm with 7mW optical power measured at the distal fiber tip. A unique peak, centered in 682nm, identifies the AlPc presence on the analyzed tissue.

  16. Biomechanics of four techniques for fixation of the four-part humeral head fracture

    PubMed Central

    da Graça, Elpídio; Okubo, Rodrigo; Shimano, Antônio Carlos; Mazzer, Nilton; Barbieri, Cláudio Henrique

    2013-01-01

    OBJECTIVE: To carry out a biomechanical study of four techniques for fixation of four-part humeral head fractures. METHODS: The fracture was reproduced in 40 plastic humeri, divided into groups of ten according to the fixation technique, each one employing different fixation resources, in different configurations. The humeral models were mounted on an aluminum scapula, with leather straps simulating the rotator cuff tendons, and submitted to bending and torsion tests in a universal testing machine, using relative stiffness as an evaluation parameter. Assemblies with intact humeri were analyzed for comparison. RESULTS: The biomechanical behavior of the fixation techniques varied within a wide range, where the assemblies including the DCP plate and the 4.5mm diameter screws were significantly more rigid than the assemblies with the Kirschner wires and the 3.5mm diameter screws. CONCLUSION: The four fixation techniques were able to bear loads compatible with the physiological demand, but those with higher relative stiffness should be preferred for clinical application. Laboratory investigation . PMID:24453641

  17. Screw-released roller brake

    NASA Technical Reports Server (NTRS)

    Vranish, John M. (Inventor)

    1999-01-01

    A screw-released roller brake including an input drive assembly, an output drive assembly, a plurality of locking sprags, a mechanical tripper nut for unlocking the sprags, and a casing therefor. The sprags consist of three dimensional (3-D) sprag members having pairs of contact surface regions which engage respective pairs of contact surface regions included in angular grooves or slots formed in the casing and the output drive assembly. The sprags operate to lock the output drive assembly to the casing to prevent rotation thereof in an idle mode of operation. In a drive mode of operation, the tripper is either self actuated or motor driven and is translated linearly up and down against a spline and at the limit of its travel rotates the sprags which unlock while coupling the input drive assembly to the output drive assembly so as to impart a turning motion thereto in either a clockwise or counterclockwise direction.

  18. Improving carbon fixation pathways

    SciTech Connect

    Ducat, DC; Silver, PA

    2012-08-01

    A recent resurgence in basic and applied research on photosynthesis has been driven in part by recognition that fulfilling future food and energy requirements will necessitate improvements in crop carbon-fixation efficiencies. Photosynthesis in traditional terrestrial crops is being reexamined in light of molecular strategies employed by photosynthetic microbes to enhance the activity of the Calvin cycle. Synthetic biology is well-situated to provide original approaches for compartmentalizing and enhancing photosynthetic reactions in a species independent manner. Furthermore, the elucidation of alternative carbon-fixation routes distinct from the Calvin cycle raises possibilities that novel pathways and organisms can be utilized to fix atmospheric carbon dioxide into useful materials.

  19. The application of Diapason spinal fixator device: a comparison with the Steffee VSP plate.

    PubMed

    Izawa, K; Yonenobu, K; Kawatsu, N; Hirotsuji, M; Wada, E; Hosono, N

    1995-01-01

    Twenty-five consecutive patients who had a variety of lumbar disorders and who underwent lumbar spinal fusion using the Diapason fixator were followed for a mean period of 20 months. The operations included 16 posterior lumbar interbody fusion (PLIF), 7 posterolateral fusion (PLF), and 2 combined PLIF and PLF (PLIF/PLF). As a control group, 38 patients undergoing PLIF using a Steffee VSP plate (VSP) were followed for a mean period of 24 months. There were no significant differences between the two groups regarding the operation time, blood loss, and improvement of preoperative symptoms. However, incidence of incomplete bony union and radiolucent zone around the screws were higher in the Diapason group than in the VSP group. Our study suggests that there was a possibility of insufficient rigidity of screw-rod fixation in the Diapason system. PMID:7787342

  20. Adynamic ileus as a complication of iliac bone removal: report of two cases.

    PubMed

    James, J D; Geist, E T; Gross, B D

    1981-04-01

    This report described two cases of postoperative adynamic ileus after iliac bone autografts. The etiology, treatment, and differentiation of this problem from mechanical obstruction are discussed. PMID:7009811

  1. Endovascular Therapeutic Options for Isolated Iliac Aneurysms with a Working Classification

    SciTech Connect

    Fahrni, Markus; Lachat, Mario M; Wildermuth, Simon; Pfammatter, Thomas

    2003-09-15

    The purpose of this paper is to demonstrate a variety of stent-grafting and embolization techniques and describe a new classification for endovascular treatment of isolated iliac artery aneurysms. A total of 19 patients were treated for isolated iliac aneurysms. Depending on the proximal iliac neck and the uni-/bilaterality of common iliac artery aneurysms (CIAA's) the patient may be treated by a tube (Type Ia) or a bifurcated stent-graft (Type Ib) in addition to internal iliac artery embolization. Neck anatomy is also critical in determining therapeutical options for internal iliac artery aneurysms (IIAA's). These are tube stent-grafting plus internal iliac branch embolization (Type IIa), coiling of afferent and efferent internal iliac vessels (Type IIb) and IIAA packing (Type IIc). The average length of stay for these procedures was 3.8 days. During the mean follow-up of 20.9 months, aneurysm size remained unchanged in all but 4 patients. Reinterventions were necessary in option Type Ib (3/8 pat.) and Type Ia (1/7 pat.) due to extender stent-graft migration (n = 2) or reperfusion leaks (n 2). We conclude that Iliac artery aneurysms may be successfully and safely treated by a tailored approach using embolization or a combination of embolization and stent-grafting. Long-term CT imaging follow-up is necessary, particularly in patients treated with bifurcated stent-grafts (Type Ib)

  2. Proximal interphalangeal arthrodesis in the horse. A retrospective study and a modified screw technique.

    PubMed

    Caron, J P; Fretz, P B; Bailey, J V; Barber, S M

    1990-01-01

    Arthrodesis of the proximal interphalangeal joint was used to treat lameness resulting from osteoarthrosis and for closed subluxation in 35 horses. Six horses had bilateral arthrodeses. Several conventional internal fixation techniques and a three converging screw method were used. Criteria for success included the horse performing its previous or intended athletic activity and the owner being satisfied with the outcome. Using these criteria, a successful outcome was obtained in 65% of the 26 animals in which adequate follow-up was available. A successful outcome was observed in four of six horses with bilateral arthrodeses. The internal fixation technique used did not influence the success rate, and the duration of postoperative casting was similar in successful and unsuccessful cases. The success rate of proximal interphalangeal arthrodeses was 46% in the fore limbs and 83% in the hind limbs. Complications included infection, cast ulcers, bone or implant failure, implant loosening, and laminitis. PMID:2349775

  3. Update: Biological Nitrogen Fixation.

    ERIC Educational Resources Information Center

    Wiseman, Alan; And Others

    1985-01-01

    Updates knowledge on nitrogen fixation, indicating that investigation of free-living nitrogen-fixing organisms is proving useful in understanding bacterial partners and is expected to lead to development of more effective symbioses. Specific areas considered include biochemistry/genetics, synthesis control, proteins and enzymes, symbiotic systems,…

  4. The Fixation of Nitrogen.

    ERIC Educational Resources Information Center

    Andrew, S. P. S.

    1978-01-01

    Discusses the fixation of atmospheric nitrogen in the form of ammonia as one of the foundations of modern chemical industry. The article describes ammonia production and synthesis, purifying the hydrogen-nitrogen mix, nitric acid production, and its commericial plant. (HM)

  5. Semi-Empirical Screw Compressor Chiller Model 

    E-print Network

    Nelson, I. C.; Culp, C.; Graves, R. D.

    2008-01-01

    A screw chiller model which is based on a first principles, semi-empirical analysis that describes the system performance based on observations of the thermodynamic processes is developed. This model is a modified method to empirically derive...

  6. Extraction strength of cannulated cancellous bone screws.

    PubMed

    Hearn, T C; Schatzker, J; Wolfson, N

    1993-01-01

    The purpose of this study was to determine whether the alterations in the relative dimensions of thread and core diameter that accompany cannulation of cancellous bone screws affect their holding strength. The screws were inserted in bovine femoral cancellous bone and mounted in the load train of a materials testing system. They were then extracted under servo-hydraulic displacement control. The tests were repeated in synthetic cancellous material. From the corresponding load-displacement histories, the maximum force values attained were determined as the screws' holding strengths. The results of tests from 17 matched pairs of bovine femora, and of 15 tests of each screw in synthetic material, were recorded. No significant differences in extraction strength between 7.0-mm cannulated and 6.5-mm standard cancellous bone screws were found. Based on tests in the bovine femur and synthetic cancellous material, this study showed that the extraction strength of cancellous bone screws is not altered by the changes in thread-to-core ratio accommodating cannulation. PMID:8459298

  7. Ball Screw Actuator Including a Stop with an Integral Guide

    NASA Technical Reports Server (NTRS)

    Wingett, Paul T. (Inventor); Perek, John (Inventor); Geck, Kellan (Inventor)

    2015-01-01

    An actuator includes a housing assembly, a ball nut, a ball screw, and a ball screw stop. The ball nut is rotationally mounted in the housing assembly, is adapted to receive an input torque, and is configured, upon receipt thereof, to rotate and supply a drive force. The ball screw is mounted within the housing assembly and extends through the ball nut. The ball screw has a first end and a second end, and is coupled to receive the drive force from the ball nut. The ball screw is configured, upon receipt of the drive force, to selectively translate between a stow position and a deploy position. The ball screw stop is mounted on the ball screw to translate therewith and is configured to at selectively engage the housing assembly while the ball screw is translating, and engage the ball nut when the ball screw is in the deploy position.

  8. Novel posterior fixation keratoprosthesis

    NASA Astrophysics Data System (ADS)

    Lacombe, Emmanuel

    1992-08-01

    The keratoprosthesis is the last solution for corneally blind patients that cannot benefit from corneal transplants. Keratoprostheses that have been designed to be affixed anteriorly usually necessitate multi-step surgical procedures and are continuously subjected to the extrusion forces generated by the positive intraocular pressure; therefore, clinical results in patients prove inconsistent. We proposed a novel keratoprosthesis concept that utilizes posterior corneal fixation which `a priori' minimizes the risk of aqueous leakage and expulsion. This prosthesis is implanted in a single procedure thereby reducing the number of surgical complications normally associated with anterior fixation devices. In addition, its novel design makes this keratoprosthesis implantable in phakic eyes. With an average follow-up of 13 months (range 3 to 25 months), our results on 21 cases are encouraging. Half of the keratoprostheses were implanted in severe burn cases, with the remainder in cases of pseudo- pemphigus. Good visual results and cosmetic appearance were obtained in 14 of 21 eyes.

  9. CARBON DIOXIDE FIXATION.

    SciTech Connect

    FUJITA,E.

    2000-01-12

    Solar carbon dioxide fixation offers the possibility of a renewable source of chemicals and fuels in the future. Its realization rests on future advances in the efficiency of solar energy collection and development of suitable catalysts for CO{sub 2} conversion. Recent achievements in the efficiency of solar energy conversion and in catalysis suggest that this approach holds a great deal of promise for contributing to future needs for fuels and chemicals.

  10. Iliac artery occlusion with "oxbow lake" formation following stent deployment in a tortuous external iliac artery during EVAR: a case report.

    PubMed

    Culverwell, Adam D; Kent, Patrick; Puppala, Sapna

    2011-10-01

    In this case report, we describe a complication that we term the "oxbow lake" deformity. This phenomenon occurs when a tortuous elongated external iliac artery segment is artificially straightened by an iliac stent resulting in kinking and compression of a redundant loop with lumen compromise. We describe the anatomy, corrective treatment, and outcome. This occurrence is potentially foreseeable with tortuous vascular anatomy and recognition can allow appropriate management planning avoiding complications for the patient. PMID:21788283

  11. Placement of C1 Pedicle Screws Using Minimal Exposure: Radiographic, Clinical, and Literature Validation

    PubMed Central

    Storey, Christopher M.; Nixon, Menarvia K.C.; Haydel, Justin; Nanda, Anil; Sin, Anthony

    2015-01-01

    Background Traditional C1-2 fixation involves placement of C1 lateral mass screws. Evolving techniques have led to the placement of C1 pedicle screws to avoid exposure of the C1-C2 joint capsule. Our minimal dissection technique utilizes anatomical landmarks with isolated exposure of C2 and the inferior posterior arch of C1. We evaluate this procedure clinically and radiographically through a technical report. Methods Consecutive cases of cranial-vertebral junction surgery were reviewed for one fellowship trained spinal surgeon from 2008-2014. Information regarding sex, age, indication for surgery, private or public hospital, intra-operative complications, post-operative neurological deterioration, death, and failure of fusion was extracted. Measurement of pre-operative axial and sagittal CT scans were performed for C1 pedicle width and C1 posterior arch height respectively. Results 64 patients underwent posterior cranio-vertebral junction fixation surgery. 40 of these patients underwent occipital-cervical fusion procedures. 7/9 (77.8%) C1 instrumentation cases were from trauma with the remaining two (22.2%) from oncologic lesions. The average blood loss among isolated C1-C2 fixation was 160cc. 1/9 patients (11.1%) suffered pedicle breech requiring sub-laminar wiring at the C1 level. On radiographic measurement, the average height of the C1 posterior arch was noted at 4.3mm (range 3.8mm to 5.7mm). The average width of the C1 pedicle measured at 5.3mm (range 2.8 to 8.7mm). The patient with C1 pedicle screw failure had a pedicle width of 2.78mm on pre-operative axial CT imaging. Conclusion Our study directly adds to the literature with level four evidence supporting a minimal dissection of C1 arch in the placement of C1 pedicle screws with both radiographic and clinical validation. Clinical Relevance Justification of this technique avoids C2 nerve root manipulation or sacrifice, reduces bleeding associated with the venous plexus, and leaves the third segment of the vertebral artery unexplored. Pre-operative review of imaging is critical in the placement of C1-C2 instrumentation. PMID:26484006

  12. Iliac vein compression syndrome: Clinical, imaging and pathologic findings.

    PubMed

    Brinegar, Katelyn N; Sheth, Rahul A; Khademhosseini, Ali; Bautista, Jemianne; Oklu, Rahmi

    2015-11-28

    May-Thurner syndrome (MTS) is the pathologic compression of the left common iliac vein by the right common iliac artery, resulting in left lower extremity pain, swelling, and deep venous thrombosis. Though this syndrome was first described in 1851, there are currently no standardized criteria to establish the diagnosis of MTS. Since MTS is treated by a wide array of specialties, including interventional radiology, vascular surgery, cardiology, and vascular medicine, the need for an established diagnostic criterion is imperative in order to reduce misdiagnosis and inappropriate treatment. Although MTS has historically been diagnosed by the presence of pathologic features, the use of dynamic imaging techniques has led to a more radiologic based diagnosis. Thus, imaging plays an integral part in screening patients for MTS, and the utility of a wide array of imaging modalities has been evaluated. Here, we summarize the historical aspects of the clinical features of this syndrome. We then provide a comprehensive assessment of the literature on the efficacy of imaging tools available to diagnose MTS. Lastly, we provide clinical pearls and recommendations to aid physicians in diagnosing the syndrome through the use of provocative measures. PMID:26644823

  13. Iliac vein compression syndrome: Clinical, imaging and pathologic findings

    PubMed Central

    Brinegar, Katelyn N; Sheth, Rahul A; Khademhosseini, Ali; Bautista, Jemianne; Oklu, Rahmi

    2015-01-01

    May-Thurner syndrome (MTS) is the pathologic compression of the left common iliac vein by the right common iliac artery, resulting in left lower extremity pain, swelling, and deep venous thrombosis. Though this syndrome was first described in 1851, there are currently no standardized criteria to establish the diagnosis of MTS. Since MTS is treated by a wide array of specialties, including interventional radiology, vascular surgery, cardiology, and vascular medicine, the need for an established diagnostic criterion is imperative in order to reduce misdiagnosis and inappropriate treatment. Although MTS has historically been diagnosed by the presence of pathologic features, the use of dynamic imaging techniques has led to a more radiologic based diagnosis. Thus, imaging plays an integral part in screening patients for MTS, and the utility of a wide array of imaging modalities has been evaluated. Here, we summarize the historical aspects of the clinical features of this syndrome. We then provide a comprehensive assessment of the literature on the efficacy of imaging tools available to diagnose MTS. Lastly, we provide clinical pearls and recommendations to aid physicians in diagnosing the syndrome through the use of provocative measures. PMID:26644823

  14. Temperature calculation for extruder screws with internal heat pipes

    NASA Astrophysics Data System (ADS)

    Lakemeyer, C.; Schöppner, V.

    2014-05-01

    One possibility of directly influencing the temperature profile in an extruder is by tempering the screw. This method is currently used in double-screw extrusion and in certain specialized applications in the field of single-screw extrusion. Significant possibilities of influencing the temperature have been shown, for example, while processing PVC on counterrotating double-screw extruders [1]. However, until now, it has not been possible to theoretically model this effect. This paper will thus introduce a mathematical model which describes the effect of internal screw tempering on the temperature gradient of the material in the extruder, allowing processes using tempered screws to be better designed and dimensioned.

  15. Basic study for ultrasound-based navigation for pedicle screw insertion using transmission and backscattered methods.

    PubMed

    Chen, Ziqiang; Wu, Bing; Zhai, Xiao; Bai, Yushu; Zhu, Xiaodong; Luo, Beier; Chen, Xiao; Li, Chao; Yang, Mingyuan; Xu, Kailiang; Liu, Chengcheng; Wang, Chuanfeng; Zhao, Yingchuan; Wei, Xianzhao; Chen, Kai; Yang, Wu; Ta, Dean; Li, Ming

    2015-01-01

    The purpose of this study was to understand the acoustic properties of human vertebral cancellous bone and to study the feasibility of ultrasound-based navigation for posterior pedicle screw fixation in spinal fusion surgery. Fourteen human vertebral specimens were disarticulated from seven un-embalmed cadavers (four males, three females, 73.14 ± 9.87 years, two specimens from each cadaver). Seven specimens were used to measure the transmission, including tests of attenuation and phase velocity, while the other seven specimens were used for backscattered measurements to inspect the depth of penetration and A-Mode signals. Five pairs of unfocused broadband ultrasonic transducers were used for the detection, with center frequencies of 0.5 MHz, 1 MHz, 1.5 MHz, 2.25 MHz, and 3.5 MHz. As a result, good and stable results were documented. With increased frequency, the attenuation increased (P<0.05), stability of the speed of sound improved (P<0.05), and penetration distance decreased (P>0.05). At about 0.6 cm away from the cortical bone, warning signals were easily observed from the backscattered measurements. In conclusion, the ultrasonic system proved to be an effective, moveable, and real-time imaging navigation system. However, how ultrasonic navigation will benefit pedicle screw insertion in spinal surgery needs to be determined. Therefore, ultrasound-guided pedicle screw implantation is theoretically effective and promising. PMID:25861053

  16. 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. PMID:25869451

  17. Kissing iliac artery stent technique for salvage of a total occlusion of a jailed common iliac artery.

    PubMed

    Ishizuka, Shuichi; Habara, Maoto; Nasu, Kenya

    2014-03-01

    A 70-year-old female was admitted to our hospital due to claudication of the left leg. The patient was diagnosed with peripheral artery disease and received endovascular therapy (EVT) with a stent implanted in the right common iliac artery (CIA) at another hospital 3 months earlier. The left CIA was jailed by the stent. We performed EVT for the chronic total occlusion (CTO) of the jailed left CIA. A kissing-stent strategy was selected because the strut could not be fully opened. The wire was crossed through the stent strut, since passing the wire outside of the stent was problematic. A balloon was dilated at the stent strut and further inserted while dilated in order to create a space between the implanted stent and opposite aorta wall. Finally, a wire was successfully crossed outside of the stent in this space. A balloon-expandable stent was implanted at the aorta to left CIA in order to perform the kissing-stent technique. Additionally, a self-expandable stent was deployed at the left external iliac artery. To facilitate kissing-stent technique for a jailed CIA CTO lesion, inserting the balloon while inflated at the bifurcation was useful to create space for advancing the guidewire along the stent. PMID:24610512

  18. Outcome of intertrochanteric fractures treated by intramedullary nail with two integrated lag screws: A study in Asian population

    PubMed Central

    Kim, Jong-Won; Kim, Tae-Young; Ha, Yong-Chan; Lee, Young-Kyun; Koo, Kyung-Hoi

    2015-01-01

    Background: The incidence of intertrochanteric fracture has increased during recent years as life expectancy has also increased. Currently, orthopedic surgeons use various fixation methods for intertrochanteric fractures like, intramedullary (IM) nailing or dynamic hip screws and plates. The intramedullary (IM) nail with two integrated lag screws has been used recently in intertrochanteric fractures to overcome Z-affect phenomenon. However, no study is available in an Asian population. This prospective study was undertaken to document the clinical and radiologic outcomes of the IM nail with two integrated lag screws and its limitations in Asian patients. Materials and Methods: Osteosynthesis was performed using InterTAN nail in 100 patients with an intertrochanteric fractures followed up for at least 1 year after surgery. We evaluated the recovery rates to prefracture status, time to bony union and the incidence of complications. Results: Seventy four patients were available for at least 1 year followup examinations. Forty-five patients (60.8%) recovered prefracture status. Mean time to bony union was 18.3 ± 8.6 weeks. Intraoperative technical problems related to an unavoidable superior positioning of the lag screw occurred in five cases. Postoperative complications requiring reoperation occurred in three patients; two cases of varus collapse with cut out and one case of periprosthetic fracture. Conclusions: The IM nail with two integrated lag screws showed favorable outcomes in Asian patients with an intertrochanteric fracture even though several complications that were not previously reported with this nail were found. The proper selection of patients and careful insertion of two lag screws should be mandatory in Asian patients. PMID:26229165

  19. Screw expander for light duty diesel engines

    NASA Technical Reports Server (NTRS)

    1983-01-01

    Preliminary selection and sizing of a positive displacement screw compressor-expander subsystem for a light-duty adiabatic diesel engine; development of a mathematical model to describe overall efficiencies for the screw compressor and expander; simulation of operation to establish overall efficiency for a range of design parameters and at given engine operating points; simulation to establish potential net power output at light-duty diesel operating points; analytical determination of mass moments of inertia for the rotors and inertia of the compressor-expander subsystem; and preparation of engineering layout drawings of the compressor and expander are discussed. As a result of this work, it was concluded that the screw compressor and expander designed for light-duty diesel engine applications are viable alternatives to turbo-compound systems, with acceptable efficiencies for both units, and only a moderate effect on the transient response.

  20. Low energy high pressure miniature screw valve

    DOEpatents

    Fischer, Gary J. (Sandia Park, NM); Spletzer, Barry L. (Albuquerque, NM)

    2006-12-12

    A low energy high pressure screw valve having a valve body having an upper portion and a lower portion, said lower portion of said valve body defining an inlet flow passage and an outlet flow passage traversing said valve body to a valve seat, said upper portion of said valve body defining a cavity at said valve seat, a diaphragm restricting flow between said upper portion of said valve body and said lower portion, said diaphragm capable of engaging said valve seat to restrict fluid communication between said inlet passage and said outlet passage, a plunger within said cavity supporting said diaphragm, said plunger being capable of engaging said diaphragm with said valve seat at said inlet and outlet fluid passages, said plunger being in point contact with a drive screw having threads engaged with opposing threads within said upper portion of said valve body such engagement allowing motion of said drive screw within said valve body.

  1. 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 ?-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. PMID:25562758

  2. Displaced avulsion fractures of the posterior cruciate ligament: Treated by stellate steel plate fixation

    PubMed Central

    Li, Lijun; Tian, Wei

    2015-01-01

    Background: The open reduction with internal fixation is an effective approach for treatment of avulsion fracture of posterior cruciate ligament. The previously used internal fixation materials including hollow screws, absorbable screw, tension bands and sutures have great defects such as insufficient fixation strength, susceptibility to re-fracture, etc. Stellate steel plate is novel material for internal fixation which has unique gear-like structure design. We used stellate steel plate for treatment of displaced avulsion fractures of posterior cruciate ligament in this study. Materials and Methods: 14 patients (9 men, 5 women; aged, 19–35 years; mean age, 28 years) with displaced avulsion fractures of the tibial insertion of the posterior cruciate ligament were retrospectively analyzed between June 2009 and June 2011. The mean duration from injury to the operation was 8.3 days (range 6–15 days). All the patients were treated with open reduction and internal fixation of a stellate steel plate (DePuy, Raynham, MA 02767, USA). The Lysholm-Tegner knee function score criteria were used to analyze results. Results: The mean followup was 24.6 months (range 18–32 months). After 6 months, all the fractures healed and knee joint activity was normal, with no knee stiffness or instability. The Lysholm-Tegner scores were 97.1 ± 1.7 points at the final followup. Conclusion: Owing to its unique gear structure, the stellate steel plate design can effectively fix an avulsion fracture block and it is a simple operation with short postoperative rehabilitation time and firm fixation. PMID:26015605

  3. Nitrogen fixation apparatus

    DOEpatents

    Chen, Hao-Lin (Walnut Creek, CA)

    1984-01-01

    A method and apparatus for achieving nitrogen fixation includes a volumetric electric discharge chamber. The volumetric discharge chamber provides an even distribution of an electron beam, and enables the chamber to be maintained at a controlled energy to pressure (E/p) ratio. An E/p ratio of from 5 to 15 kV/atm of O.sub.2 /cm promotes the formation of vibrationally excited N.sub.2. Atomic oxygen interacts with vibrationally excited N.sub.2 at a much quicker rate than unexcited N.sub.2, greatly improving the rate at which NO is formed.

  4. May-Thurner syndrome: High output cardiac failure as a result of iatrogenic iliac fistula

    PubMed Central

    Singh, Shantanu; Singh, Shivank; Jyothimallika, Juthika; Lynch, Teresa J

    2015-01-01

    May-Thurner syndrome (MTS) also termed iliocaval compression or Cockett-Thomas syndrome is a common, although rarely diagnosed, condition in which the patient has an anatomical variant wherein the right common iliac artery overlies and compresses the left common iliac vein against the fifth lumbar spine resulting in increased risk of iliofemoral deep venous thrombosis. This variant has been shown to be present in over 23% of the population but most go undetected. We present a patient with MTS who developed high output cardiac failure due to an iatrogenic iliac fistula. The patient underwent an extensive workup for a left to right shunt including MRI and arterial duplex in the vascular lab. He was ultimately found to have a 2.1 cm left common iliac artery aneurysm and history of common iliac stent. We took the patient to the operating room for aortogram with placement of an endovascular plug of the left internal iliac artery and aorto-bi-iliac stent graft placement with CO2 and IV contrast. Subsequently the patient underwent successful stent placement in the area that was compressed followed by 6 mo of anticoagulation with warfarin. The flow from the fistula decreased significantly. PMID:25789305

  5. Anatomical study of anterior column screw tunnels through virtual three-dimensional models of the pelvis.

    PubMed

    Chen, Hua; Tang, Peifu; Yao, Yimin; She, Fei; Wang, Yan

    2015-01-01

    We created 66 male and 74 female virtual three-dimensional models of the pelvis based on computed tomography data from 140 patients. Virtual cylindrical bolts (VCBs) were placed in the anterior column (AC), which was then resliced serially along the bolt's long axis. AC screw tunnel mainly comprises two long, narrow triangular prisms [zone III (acetabular fossa) and zone V (obturator foramen)]--forming the III/V angle--linked by a larger, shorter cylinder [zone IV (acetabular notch)]. VCBs' mean length and maximum diameter were 111.13 ± 7.33 and 7.37 ± 1.90 mm, respectively. The models' anatomical zone lengths were similar between the sexes. Zone V's narrowest diameters and the III/V angles were significantly different. VCBs >6.5 mm were accommodated in 65 of 66 male models and 31 of 74 female models. VCBs >5.0 and <6.5 mm were accommodated in one male and 30 female models. Eleven female models accommodated only VCBs >3.5 and <5.0 mm. However, to 13 female pelvic models with maximum VCB accommodation of <5 mm for the anterior column, the maximum diameter of the VCBs was 8.23 ± 1.22 mm in medial passage and 10.3 ± 1.91 mm in lateral passage, respectively. Percutaneous fixation of the AC with screws is a safe technique, even though in Chinese female patients. The narrowest diameters in zone V and the III/V angles are the key factors for application of AC screws. Female patients with a smaller interosseous space at zone V and a large III/V angle can accommodate segmental passage screws. PMID:24413847

  6. Feasibility of C2 Vertebra Screws Placement in Patient With Occipitalization of Atlas

    PubMed Central

    Ji, Wei; Liu, Xiang; Huang, Wenhan; Huang, Zucheng; Li, Xueshi; Chen, Jianting; Wu, Zenghui; Zhu, Qingan

    2015-01-01

    Abstract Occipitalization of atlas (OA) is a congenital disease with the possibility of anomalous bony anatomies and the C2 pedicle screw insertion is technically challenging. However, there are no existing literatures clarified the dimensions and angulations of the C2 pedicles, lamina and lateral masses for screw insertion in patients with OA. Therefore, the aim of this study was to assess the morphometric features of C2 for screw placement in OA to guide the use of surgical screws. Measurements of the OA patients on the computer tomography (CT) images including lamina angle, length and thickness, pedicle angle, length and thickness, and lateral mass thickness and length of the axis vertebra. The OA patients data were compared with age and gender matched cohort of randomly selected patients in a control group without OA. The picture archiving and communication system was used for all patients who had received cervical CT scanning between January 2001 and January 2015. Measurements were performed independently by 2 experienced observers who reviewed the CT scans and recorded the patients with OA. Statistical analysis was performed at a level of significance P?screw is a more viable option in comparison with pedicle screw for C2 fixation in OA. Nevertheless, the suitability should be fully assessed prior to surgery. PMID:26376390

  7. Endovascular Repair of a Primary Iliac-Cecal Fistula Presenting with Gastrointestinal Hemorrhage

    SciTech Connect

    Whittaker, Charlotte Sara Ananthakrishnan, Ganapathy; DeNunzio, Mario Cosimo; Quarmby, John Winston; Bungay, Peter Mark

    2008-07-15

    We report a case of an arterio-enteric fistula between an external iliac artery aneurysm and otherwise healthy cecum, presenting with torrential hemorrhage per rectum in an 85-year-old patient. Whilst fistulization to the aorta and common iliac arteries has been reported, to our knowledge no previous cases of primary fistulization between an external iliac aneurysm and normal cecum have been. Successful endovascular exclusion of the aneurysm was undertaken with a Wallgraft covered stent and the patient remains well at 1 year.

  8. Tangential View and Intraoperative Three-Dimensional Fluoroscopy for the Detection of Screw-Misplacements in Volar Plating of Distal Radius Fractures

    PubMed Central

    Rausch, Sascha; Marintschev, Ivan; Graul, Isabel; Wilharm, Arne; Klos, Kajetan; Hofmann, Gunther O.; Florian Gras, Marc

    2015-01-01

    Background: Volar locking plate fixation has become the gold standard in the treatment of unstable distal radius fractures. Juxta-articular screws should be placed as close as possible to the subchondral zone, in an optimized length to buttress the articular surface and address the contralateral cortical bone. On the other hand, intra-articular screw misplacements will promote osteoarthritis, while the penetration of the contralateral bone surface may result in tendon irritations and ruptures. The intraoperative control of fracture reduction and implant positioning is limited in the common postero-anterior and true lateral two-dimensional (2D)-fluoroscopic views. Therefore, additional 2D-fluoroscopic views in different projections and intraoperative three-dimensional (3D) fluoroscopy were recently reported. Nevertheless, their utility has issued controversies. Objectives: The following questions should be answered in this study; 1) Are the additional tangential view and the intraoperative 3D fluoroscopy useful in the clinical routine to detect persistent fracture dislocations and screw misplacements, to prevent revision surgery? 2) Which is the most dangerous plate hole for screw misplacement? Patients and Methods: A total of 48 patients (36 females and 13 males) with 49 unstable distal radius fractures (22 x 23 A; 2 x 23 B, and 25 x 23 C) were treated with a 2.4 mm variable angle LCP Two-Column volar distal radius plate (Synthes GmbH, Oberdorf, Switzerland) during a 10-month period. After final fixation, according to the manufactures' technique guide and control of implant placement in the two common perpendicular 2D-fluoroscopic images (postero-anterior and true lateral), an additional tangential view and intraoperative 3D fluoroscopic scan were performed to control the anatomic fracture reduction and screw placements. Intraoperative revision rates due to screw misplacements (intra-articular or overlength) were evaluated. Additionally, the number of surgeons, time and radiation-exposure, for each step of the operating procedure, were recorded. Results: In the standard 2D-fluoroscopic views (postero-anterior and true lateral projection), 22 screw misplacements of 232 inserted screws were not detected. Based on the additional tangential view, 12 screws were exchanged, followed by further 10 screws after performing the 3D fluoroscopic scan. The most lateral screw position had the highest risk for screw misplacement (accounting for 45.5% of all exchanged screws). The mean number of images for the tangential view was 3 ± 2.5 images. The mean surgical time was extended by 10.02 ± 3.82 minutes for the 3D fluoroscopic scan. An additional radiation exposure of 4.4 ± 4.5seconds, with a dose area product of 39.2 ± 14.5 cGy/cm2 were necessary for the tangential view and 54.4 ± 20.9 seconds with a dose area product of 2.1 ± 2.2 cGy/cm2, for the 3D fluoroscopic scan. Conclusions: We recommend the additional 2D-fluoroscopic tangential view for detection of screw misplacements caused by overlength, with penetration on the dorsal cortical surface of the distal radius, predominantly observed for the most lateral screw position. The use of intraoperative 3D fluoroscopy did not become accepted in our clinical routine, due to the technical demanding and time consuming procedure, with a limited image quality so far. PMID:26101762

  9. Eighth international congress on nitrogen fixation

    SciTech Connect

    Not Available

    1990-01-01

    This volume contains the proceedings of the Eighth International Congress on Nitrogen Fixation held May 20--26, 1990 in Knoxville, Tennessee. The volume contains abstracts of individual presentations. Sessions were entitled Recent Advances in the Chemistry of Nitrogen Fixation, Plant-microbe Interactions, Limiting Factors of Nitrogen Fixation, Nitrogen Fixation and the Environment, Bacterial Systems, Nitrogen Fixation in Agriculture and Industry, Plant Function, and Nitrogen Fixation and Evolution.

  10. [Fracture of implant abutment screws and removal of a remaining screw piece].

    PubMed

    van den Broeke, S M; de Baat, C

    2008-07-01

    Fracture of the implant abutment screws is a complication which can render an implant useless. The prevalence of abutment screw fracture does not exceed 2.5% after 10 years. Causes are loosening of implant abutment screw, too few, too short or too narrow implants, implants not inserted perpendicular to the occlusal plane, improper suprastructure, too long free-ending parts of the suprastructure, improper occlusion concept, premature occlusal contacts, parafunctions, inadequate skills of the dentist, and fabrication failures. Methods of removing a fractured implant abutment screw piece are, among others, the use of a self-made screwdriver and the use of a service set available for the specific implant system. PMID:18686561

  11. Computation of Flow in Screw Compressors

    NASA Astrophysics Data System (ADS)

    Kalitzin, Georgi; Cai, Xiaodan; Reba, Ramons; Medic, Gorazd

    2015-08-01

    A CFD model enabling accurate and computationally affordable simulation of unsteady flow in screw compressors has been developed. This paper focuses on computational aspects, including real-gas CFD using hybrid structured/unstructured moving grids, and specifics of grid generation for moving rotors and their communication with the discharge plenum.

  12. 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.

  13. Improvements to the single screw extruder

    NASA Technical Reports Server (NTRS)

    Hiemenz, C.; Ziegmann, G.; Franzkoch, B.; Hoffmanns, W.; Michaeli, W.

    1977-01-01

    The extrusion on a single screw extruder is examined. The process is divided into several steps: the dosage of the materials to be conveyed; the modification of the shape of the feeding opening which influences the feeding process and consequently the throughput of the extruder; optimizing the shape of the feeding zone to meet the specific material requirements; and plasticizing and homogenizing.

  14. A biological screw in a beetle's leg.

    PubMed

    van de Kamp, Thomas; Vagovi?, Patrik; Baumbach, Tilo; Riedel, Alexander

    2011-07-01

    The coxa-trochanteral joints on the legs of the weevil Trigonopterus oblongus (Pascoe) work as a biological screw-and-nut system. The apical portions of the coxae closely resemble nuts with well-defined inner threads covering 345°. The corresponding trochanters have perfectly compatible external spiral threads of 410°. PMID:21719669

  15. Computer simulation of screw dislocation in aluminum

    NASA Technical Reports Server (NTRS)

    Esterling, D. M.

    1976-01-01

    The atomic structure in a 110 screw dislocation core for aluminum is obtained by computer simulation. The lattice statics technique is employed since it entails no artificially imposed elastic boundary around the defect. The interatomic potential has no adjustable parameters and was derived from pseudopotential theory. The resulting atomic displacements were allowed to relax in all three dimensions.

  16. Surgical rib fixation - technical aspects.

    PubMed

    Marasco, Silvana; Saxena, Pankaj

    2015-05-01

    Surgical rib fixation (SRF) for severe rib fracture injuries is increasingly becoming an accepted treatment modality. There is now adequate evidence in randomised controlled trials that rib fixation in flail chest patients reduces ventilator times, intensive care stay and costs of treatment in ventilator dependent patients [1-3]. Despite this, rib fixation has not become standard of care for these patients and remains a treatment modality practised by few centres, usually those with large trauma loads who see high volumes of severe rib fracture injury patients. The purpose of this article is to outline the available prostheses, indications, operative planning and techniques of rib fixation. Surgical approaches to rib fractures in anterior, lateral and posterior positions are described as are the use of currently available cortical and medullary fixation prostheses. PMID:25624272

  17. 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

  18. Biomechanical Evaluation of Interfragmentary Compression At Tibia Plateau Fractures In Vitro Using Different Fixation Techniques

    PubMed Central

    Kojima, K.; Gueorguiev, B.; Seva, G.; Stoffel, K.; de Oliveira, R. Garcia; Eberli, U.; Nicolino, T.; Lenz, M.

    2015-01-01

    Abstract Reliable osteosynthesis of intraarticular fractures depends on lasting interfragmentary compression. Its amount differs in the applied fixation method. The interfragmentary compression of cancellous and cortical lag screws and angle stable locking plates was quantified in an osteoporotic and non-osteoporotic synthetic human bone model. A split fracture of the lateral tibia plateau (AO/OTA type 41-B1.1) was mimicked by an osteotomy in right adult synthetic human tibiae with hard or soft cancellous bone. Specimens were fixed with either two 6.5?mm cancellous, four 3.5?mm cortical lag screws, or 3.5?mm LCP proximal lateral tibia plate preliminary compresed by a reduction clamp (n?=?5 per group). A pressure sensor film was used to register the interfragmentary compression. One-way analysis of variance (ANOVA) with Bonferroni post hoc correction was performed for statistical analysis (p?screws provided a compression of 1.69?±?0.65?MPa in non-osteoporotic bone, being not significantly different to the osteoporotic bone group (1.43?±?0.47?MPa, P?=?1.0). Two 6.5?mm cancellous lag screws showed a significantly higher compression in non-osteoporotic (2.1?±?0.59?MPa) compared to osteoporotic (0.77?±?0.21?MPa, P?screws are especially suited for non-osteoporotic bone, whereas four 3.5?mm cortical screws exhibited comparable compression in both bone qualities. PMID:25569643

  19. Modified Stent-Assisted Coil Embolization Technique to Treat an Internal Iliac Artery Aneurysm

    SciTech Connect

    Chowdhury, M. M.; Northeast, A.; Lintott, P.; Liong, W.-C.; Warakaulle, D. R.

    2010-10-15

    Stent-assisted coil embolization is a well-described technique for the treatment of wide-necked intracranial aneurysms. We describe a modification of this technique used successfully to occlude a wide-necked internal iliac artery aneurysm.

  20. Successful Endovascular Treatment of Iliac Vein Compression (May-Thurner) Syndrome in a Pediatric Patient

    SciTech Connect

    Oguzkurt, Levent Tercan, Fahri; Sener, Mesut

    2006-06-15

    A 10-year-old boy presented to our clinic with left lower extremity swelling present for 1 year with deterioration of symptoms during the prior month. Laboratory investigation for deep vein thrombosis was negative. Venography and computed tomography scan of the pelvis showed compression of the left common iliac vein by the right common iliac artery. A diagnosis of iliac vein compression syndrome was made. After venography, endovascular treatment was planned. The stenosis did not respond to balloon dilatation and a 12 mm Wallstent was placed with successful outcome. The patient's symptoms improved but did not resolve completely, probably due to a chronically occluded left superficial femoral vein that did not respond to endovascular recanalization. To the best of our knowledge, this is the first case of successful endovascular treatment of iliac vein compression syndrome with stent placement in a pediatric patient.

  1. Endoluminal embolization of bilateral atherosclerotic common iliac aneurysms with fibrin tissue glue (Beriplast)

    SciTech Connect

    Beese, Richard C.; Tomlinson, Mark A.; Buckenham, Timothy M.

    2000-05-15

    The standard surgical approach to nonleaking iliac aneurysms found at repair of a leaking abdominal aortic aneurysm is to minimize the operative risk by repairing the abdominal aorta only. This means that the bypassed iliac aneurysms may have to be repaired later. As this population of patients are usually elderly with coexisting medical problems, interventional radiology is being used to embolize these aneurysms, thus avoiding the morbidity and mortality associated with further general anesthesia and surgery. Various materials and stents have been reported to be effective in the treatment of iliac aneurysms. We report the successful use of endoluminal fibrin tissue glue (Beriplast) to treat two large iliac aneurysms in a patient who had had a previous abdominal aortic aneurysm repair. We discuss the technique involved and the reasons why we used tissue glue in this patient.

  2. Applying Cross-Pin System in Both Femoral and Tibial Fixation in Anterior Cruciate Ligament Reconstruction Using Hamstring Tendons

    PubMed Central

    Qi, Wei; Liu, Yujie; Xue, Jing; Li, Haifeng; Wang, Junliang; Qu, Feng

    2015-01-01

    Use of the RigidFix Cross Pin System (DePuy Mitek, Raynham, MA) is a popular technique for femoral fixation of grafts in anterior cruciate ligament reconstruction (ACLR). However, tibial fixation is still limited to the use of interference screws and post fixation, and few surgeons apply the femoral RigidFix system in tibial fixation. Meanwhile, tunnel enlargement is still a problem that affects the outcome of ACLR with hamstring grafts. We have used the femoral RigidFix system in femoral and tibial fixation. The rod top of the guide frame should be placed under the level of the subchondral bone at the proximal end of the tibial tunnel to ensure that the pins will not be inserted into the joint. The pins are inserted through the center of the lateral tibia. Using our technique, the fixation points of the femur and tibia are close to the anterior cruciate ligament insertions, and full contact of the graft with the tunnel wall can be accomplished. On the basis of our preliminary observations and investigation, we are optimistic about the prospect of performing ACLR using the RigidFix system in femoral and tibial fixation. PMID:26697293

  3. External iliac artery thrombosis after common iliac artery balloon occlusion during cesarean hysterectomy for placenta accreta in cervico-isthmic pregnancy.

    PubMed

    Matsueda, Sayaka; Hidaka, Nobuhiro; Kondo, Yukiko; Fujiwara, Arisa; Fukushima, Kotaro; Kato, Kiyoko

    2015-11-01

    Although the role of interventional radiology in the field of obstetrical hemorrhage has been widely reported upon recently, the rate of procedure-related complications has not been fully determined. We present the case of a patient who developed an external iliac artery thrombosis, a rarely reported complication associated with prophylactic common iliac artery balloon occlusion (CIABO). After CIABO, we found that the dorsalis pedis artery of the right foot was weak and the foot was cold, despite the fact that the patient had no complaints. Computed tomography demonstrated a linear thrombus in the right external iliac artery. We managed the patient conservatively using a heparin drip without the need for thromboembolectomy. Our experience suggests that it is important to consider the risk of thrombosis formation after CIABO. Physical examination post-procedure is key to identifying this complication early. PMID:26223441

  4. [Tensile strength studies of self-cutting titanium osteosynthesis screws].

    PubMed

    Honke, W; Neumayer, B; Russ, A

    1992-12-01

    The tapping screws of the Medicon Osteosynthese System applied in the jaw and facial area were checked for their mechanical sturdiness. Screwing tests with bones and aluminium were carried out. The minimum fracture moment, the moment transferrable by the screw slot and the required moment for a tight seat of the Osteosynthese plate on the bone surface were calculated. The screws and plates are of titanium alloy TiA16V4 (US standard) for implantats. In a sample taken at random of test screws the fracture moments were measured and examined. All the screws support considerable loads and the fracture moments are almost 20% higher that the minimum fracture moment for TiA16V4 screws specified in DIN 267, part 18. PMID:1286145

  5. Iatrogenic Iliac Artery Rupture: Emergency Management by Longer Stent-Graft on a Shorter Balloon

    SciTech Connect

    Trehan, Vijay; Nigam, Arima; Ramakrishnan, S.

    2007-02-15

    Rupture of an iliac artery during percutaneous transluminal coronary angioplasty is a rare but potentially devastating complication. We report a case of iatrogenic external iliac artery rupture that was successfully treated by temporary balloon occlusion followed by endovascular stent graft placement in an unusual manner. Limited availability of the hardware necessitated the use of a longer bare stent graft mounted on a relatively shorter balloon.

  6. Anatomic Feasibility of Posterior Cervical Pedicle Screw Placement in Children: Computerized Tomographic Analysis of Children Under 10 Years Old

    PubMed Central

    Lee, HoJin; Kim, Il Sup; Kim, Moon Suk; Sung, Jae Hoon; Lee, Sang Won

    2014-01-01

    Objective To evaluate the anatomical feasibility of 3.5 mm screw into the cervical spine in the pediatric population and to establish useful guidelines for their placement. Methods A total of 37 cervical spine computerized tomography scans (24 boys and 13 girls) were included in this study. All patients were younger than 10 years of age at the time of evaluation for the period of 2007-2011. Results For the C1 screw placement, entry point height (EPH) was the most restrictive factor (47.3% patients were larger than 3.5 mm). All C2 lamina had a height larger than 3.5 mm and 68.8% (51/74) of C2 lamina had a width thicker than 3.5 mm. For C2 pedicle width, 55.4% (41/74) of cases were larger than 3.5 mm, while 58.1% (43/74) of pedicle heights were larger than 3.5 mm. For pedicle width of subaxial spine, 75.7% (C3), 73% (C4), 82.4% (C5), 89.2% (C6), and 98.1% (C7, 1/54) were greater than 3.5 mm. Mean lamina width of subaxial cervical spine was 3.1 (C3), 2.7 (C4), 2.9 (C5), 3.8 (C6), and 4.0 mm (C7), respectively. Only 34.6% (127/370) of subaxial (C3-7) lamina thickness were greater than 3.5 mm. Mean length of lateral mass for the lateral mass screw placement was 9.28 (C3), 9.08 (C4), 8.81 (C5), 8.98 (C6), and 10.38 mm (C7). Conclusion C1 lateral mass fixation could be limited by the morphometrics of lateral mass height. C2 trans-lamina approach is preferable to C2 pedicle screw fixation. In subaxial spines, pedicle screw placement was preferable to trans-lamina screw placement, except at C7. PMID:25628806

  7. Iso-osmotic bowel preparation improves the accuracy of iliac artery colour flow duplex examination.

    PubMed

    Whiteley, M S; Fox, A D; Harris, R A; Horrocks, M

    1995-11-01

    Colour flow duplex ultrasonography is currently the non-invasive method of choice for investigating the iliac arteries. However it is only 84-92% sensitive in the best hands when compared with biplanar angiography. Bowel gas and faeces overlying the iliac arteries obscure the vessels and prevent a good ultrasound image. We have previously shown that preparation of the bowel with an iso-osmotic bowel preparation (Klean Prep) improves the clarity of duplex image of the iliac arteries. This is caused by a volume effect which flushes out gas and faeces, leaving a fluid-filled bowel transparent to ultrasound. The aim of this study was to investigate whether this enhanced image increased the diagnostic accuracy of duplex examination. We performed iliac duplex examinations on 56 patients with clinically suspected iliac artery disease, initially with the normal preparation of starving the patients for 12 h and subsequently after preparation by Klean Prep. The results from each investigation were compared with the gold standard of biplanar intra-arterial digital substraction angiography. The use of iso-osmotic bowel preparation (Klean Prep) significantly improved the accuracy of iliac duplex ultrasonography over preparation by 12 h starvation, when compared with biplanar angiography. PMID:8544154

  8. Endovascular Treatment of Ruptured Iliac Aneurysm Previously Treated by Endovascular Means

    SciTech Connect

    Dalainas, Ilias Nano, Giovanni; Stegher, Silvia; Bianchi, Paolo; Malacrida, Giovanni; Tealdi, Domenico G.

    2008-03-15

    A patient with a ruptured iliac aneurysm was admitted to the Emergency Department in hypovolemic shock. He had previously undergone surgical treatment for an infrarenal abdominal aortic aneurysm, which was managed with a terminal-terminal Dacron tube graft. Subsequently, he developed two iliac aneurysms, which were treated endovascularly with two wall-grafts in the right and one wall-graft in the left iliac arteries. He suffered chronic renal failure and arterial hypertension. Contrast-enhanced computed tomography showed rupture of the right iliac aneurysm and dislocation of the two wall-grafts. He was treated in an emergency situation with the implantation of an iliac endograft that bridged the two wall-grafts, which resulted in hemostasis and stabilization of his condition. Five days later, in an elective surgical situation, he was treated with the implantation of an aorto-uni-iliac endograft combined with a femoral-femoral bypass. He was discharged 5 days later in good condition. At the 4 year follow-up visit, the endoprosthesis remained in place with no evidence of an endoleak. In conclusion, overlapping of endografts should be avoided, if possible. Strict surveillance of the endovascularly treated patient remains mandatory.

  9. Analysis of Rotor Contact for Screw Compressor

    NASA Astrophysics Data System (ADS)

    Kameya, Hirotaka; Aoki, Masakazu; Nozawa, Shigekazu

    A reliability evaluation of meshing rotor surfaces needs contact theory on a micro size area. We propose a method to evaluate whether a screw compressor rotor has enough contact fatigue strength. The method is based on analyses of three dimensional curvatures and the Hertz contact pressure. At a contact point one of the principal curvatures directs the rotor's sealing line and this is calculated as the gap distribution. Another perpendicular curvature is calculated with an approximate arc to the rotor profile. As the contact point is an inflection point, the contact condition is first calculated on each side and then composed. Using our method we found the rotors of a typical screw compressor have enough strength. This is because the rotor contact pressure is calculated to be 0.57 times of a contact fatigue strength of their material.

  10. Analysis of Modeling Parameters on Threaded Screws.

    SciTech Connect

    Vigil, Miquela S.; Brake, Matthew Robert; Vangoethem, Douglas

    2015-06-01

    Assembled mechanical systems often contain a large number of bolted connections. These bolted connections (joints) are integral aspects of the load path for structural dynamics, and, consequently, are paramount for calculating a structure's stiffness and energy dissipation prop- erties. However, analysts have not found the optimal method to model appropriately these bolted joints. The complexity of the screw geometry cause issues when generating a mesh of the model. This paper will explore different approaches to model a screw-substrate connec- tion. Model parameters such as mesh continuity, node alignment, wedge angles, and thread to body element size ratios are examined. The results of this study will give analysts a better understanding of the influences of these parameters and will aide in finding the optimal method to model bolted connections.

  11. Molecular Biology of Nitrogen Fixation

    ERIC Educational Resources Information Center

    Shanmugam, K. T.; Valentine, Raymond C.

    1975-01-01

    Reports that as a result of our increasing knowledge of the molecular biology of nitrogen fixation it might eventually be possible to increase the biological production of nitrogenous fertilizer from atmospheric nitrogen. (GS)

  12. Evaluation of Bone Fixation Implants 

    E-print Network

    Perkins, Luke 1990-

    2012-12-10

    This research investigates the effects of the human body on the mechanical, chemical, and morphological properties of the surface of internal fixation devices. Stainless steel and titanium devices that had failed were provided from the Shandong...

  13. Autologous Hamstring Anterior Cruciate Ligament Graft Failure Using the Anteromedial Portal Technique With Suspensory Femoral Fixation

    PubMed Central

    Galdi, Balazs; Reyes, Allan; Brabston, Eugene W.; Levine, William N.

    2015-01-01

    Background: The anteromedial portal technique for drilling of the femoral tunnel during anterior cruciate ligament (ACL) reconstruction has been advocated by many surgeons as allowing improved access to the anatomical footprint. Furthermore, suspensory fixation of soft tissue grafts has become popularized because of complications associated with cross-pin fixation. Concerns regarding the use of both have recently arisen. Purpose: To raise awareness of the increased risk of graft failure when using the anteromedial portal technique with suspensory femoral fixation during ACL reconstruction. Study Design: Cohort study; Level of evidence, 3. Methods: From November 1998 to August 2012, a total of 465 primary ACL reconstructions were performed using quadrupled hamstring autograft tendons, with drilling of the femoral tunnel performed via the transtibial portal. Graft fixation on the femur was achieved with cross-pin fixation, while interference screw fixation was used on the tibia. From September 2012 to October 2013, there were 69 reconstructions performed through an anteromedial portal. While there was no change in graft choice, a change was made to using suspensory femoral fixation. No other surgical or postoperative rehabilitation changes were made. Results: During the 14-year period in which ACL reconstructions were performed via the transtibial portal and with cross-pin fixation, 2 graft failures (0.4% failure rate) were reported. After switching to the anteromedial portal with suspensory fixation, 7 graft failures (10.1% failure rate) were reported over a 13-month period. These were 5 male and 2 female patients, with a mean age of 18.8 years—all elite athletes. The same surgical technique was used in all patients, and all patients had at least an 8 mm–diameter graft. Patients were cleared to return to sport at an average of 8.4 months postoperatively, after completing functional performance tests. Of the 7 patients, 6 sustained a rerupture of the graft within 2 weeks of returning to full competition. The final patient sustained a rerupture 10 months after being cleared to play. Conclusion: Compared with the transtibial technique with cross-pin graft fixation, there is an increased risk of graft failure when performing autologous hamstring ACL reconstructions using the anteromedial portal technique with cortical suspensory fixation. PMID:26535370

  14. Screw-wire osteo-traction: an adjunctive or alternative method of anatomical reduction of multisegment midfacial fractures? A description of technique and prospective study of 40 patients.

    PubMed

    O'Regan, Barry; Devine, Maria; Bhopal, Sats

    2013-12-01

    Stable anatomical fracture reduction and segment control before miniplate fixation can be difficult to achieve in comminuted midfacial fractures. Fracture mobilization and reduction methods include Gillies elevation, malar hook, and Dingman elevators. No single method is used universally. Disadvantages include imprecise segment alignment and poor segment stability/control. We have employed screw-wire osteo-traction (SWOT) to address this problem. A literature review revealed two published reports. The aims were to evaluate the SWOT technique effectiveness as a fracture reduction method and to examine rates of revision fixation and plate removal. We recruited 40 consecutive patients requiring open reduction and internal fixation of multisegment midfacial fractures (2009-2012) and employed miniplate osteosynthesis in all patients. SWOT was used as a default reduction method in all patients. The rates of successful fracture reduction achieved by SWOT alone or in combination and of revision fixation and plate removal, were used as outcome indices of the reduction method effectiveness. The SWOT technique achieved satisfactory anatomical reduction in 27/40 patients when used alone. Other reduction methods were also used in 13/40 patients. No patient required revision fixation and three patients required late plate removal. SWOT can be used across the midface fracture pattern in conjunction with other methods or as a sole reduction method before miniplate fixation. PMID:24436763

  15. Feasibility of purely endoscopic intramedullary fixation of mandibular condyle fractures.

    PubMed

    Frake, Paul C; Goodman, Joseph F; Joshi, Arjun S

    2015-01-01

    The investigators of this study hypothesized that fractures of the mandibular condyle can be repaired using short-segment intramedullary implants and purely endoscopic surgical technique, using a basic science, human cadaver model in an academic center. Endoscopic instrumentation was used through a transoral mucosal incision to place intramedullary implants of 2 cm in length into osteotomized mandibular condyles. The surgical maneuvers that required to insert these implants, including condyle positioning, reaming, implant insertion, and seating of the mandibular ramus, are described herein. Primary outcome was considered as successful completion of the procedure. Ten cadaveric mandibular condyles were successfully repaired with rigid intramedullary internal fixation without the use of external incisions. Both insertion of a peg-type implant and screwing a threaded implant into the condylar head were possible. The inferior portion of the implant remained exposed, and the ramus of the mandible was manipulated into position on the implant using retraction at the sigmoid notch. The results of this study suggest that purely endoscopic repair of fractures of the mandibular condyle is possible by using short-segment intramedullary titanium implants and a transoral endoscopic approach without the need for facial incisions or punctures. The biomechanical advantages of these intramedullary implants, including improved strength and resistance to mechanical failure compared with miniplates, have been recently established. The combination of improved implant design and purely endoscopic technique may allow for improved fixation and reduced surgical- and implant-related morbidity in the treatment of condylar fractures. PMID:25534058

  16. Compression of the Inferior Vena Cava by the Right Iliac Artery: A Rare Variant of May-Thurner Syndrome

    SciTech Connect

    Fretz, V.; Binkert, C. A.

    2010-10-15

    May-Thurner syndrome is known as compression of the left common iliac vein by the right common iliac artery. We describe a case of an atypical compression of the inferior vena cava by the right common iliac artery secondary to a high aortic bifurcation. Despite an extensive collateral network, there was a significant venous gradient between the iliac veins and the inferior vena cava above the compression. After stenting the venous pressure gradient disappeared. Follow-up 4 months later revealed a good clinical response with a patent stent.

  17. Dual load path ball screw with rod end swivel

    NASA Technical Reports Server (NTRS)

    Wngett, Paul (Inventor)

    2002-01-01

    A dual drive ball has a ball screw shaft coupled at one end to a gear train and coupled at the other end to a ball screw nut. The ball screw shaft and ball screw nut are connected through complementary helical grooves filled with ball bearing balls. The outer surface of the ball screw nut is plined and can be driven by a second gear train. An output tube is coupled at one end to the ball screw nut and at its opposite end has a connector portion with a groove on its inner surface. A rod end has a coupling member for coupling to a surface to be actuated and a shaft portion with a groobe on its outer surface. This shaft portion is received with in the outputtube portion and the corresponding grooves are coupled through the use of a plurality of ball bearing balls.

  18. The history of internal fixation of proximal femur fractures Ernst Pohl-the genius behind.

    PubMed

    Bartoní?ek, Jan; Rammelt, Stefan

    2014-11-01

    The most frequently used implants for internal fixation of proximal femoral fractures are currently the dynamic hip screw and the intramedullary hip nail. However, little has been written about one of the pioneers in this field, a German genius, the designer Ernst Pohl (1876-1962). Without his involvement the concepts of intramedullary nailing coined by Gerhard Küntscher, Richard Maatz and other surgeons could hardly have been implemented. Through his achievements Pohl has rightly merited his pre-eminent position in the history of bone surgery. This article outlines the extraordinary contribution of Ernst Pohl to the development of skeletal surgery and radiology, as well as other medical disciplines. PMID:24687268

  19. Screws, Propellers and Fans Based on a Mobius Strip

    NASA Technical Reports Server (NTRS)

    Seiner, John M.; Backley, Floyd D.; Gilinsky, Mikhail

    1998-01-01

    A Mobius strip concept is intended for improving the working efficiency of propellers and screws. Applications involve cooling, boat propellers, mixing in appliance, blenders, and helicopters. Several Mobius shaped screws for the average size kitchen mixers have been made and tested. The tests have shown that the mixer with the Mobius shaped screw pair is most efficient, and saves more than 30% of the electric power by comparison with the standard. The created video film about these tests illustrates efficiency of Mobius shaped screws.

  20. 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

  1. 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

  2. Flexor tendon repair after rupture caused by volar plate fixation of the distal radius.

    PubMed

    Rubensson, Carin C; Ydreborg, Karin; Boren, Linda; Karlander, Lars-Erik

    2015-04-01

    Volar plate fixation of unstable fractures of the distal radius is preferred by a majority of surgeons today. One known complication is the rupture of flexor tendons. The aim of this paper is to present flexor tendon ruptures after volar plate fixation analysing the clinical outcome after tendon surgery, aetiology, and methods of prevention. Seventeen consecutive ruptures in 14 patients were included. The incidence was 1.4%. Three patients declined tendon surgery. Eleven patients were treated with a free tendon graft. Only two patients showed excellent results regarding mobility in the thumb and/or fingers. Analysis of radiographs demonstrated sub-optimal placement of plate or screws in all cases. Rupture of a flexor tendon is a serious complication where the functional outcome after surgical reconstruction is uncertain. Early removal of the plate when the placement is sub-optimal or when local volar tenderness appears would probably prevent many ruptures. PMID:25162925

  3. Is Internal Iliac Artery Embolization Essential Prior to Endovascular Repair of Aortoiliac Aneurysms?

    SciTech Connect

    Bharwani, N. Raja, J.; Choke, E.; Belli, A. M.; Thompson, M. M.; Morgan, R. A.; Munneke, G.

    2008-05-15

    Patients who undergo endovascular repair of aorto-iliac aneurysms (EVAR) require internal iliac artery (IIA) embolization (IIAE) to prevent type II endoleaks after extending the endografts into the external iliac artery. However, IIAE may not be possible in some patients due to technical factors or adverse anatomy. The aim of this study was to assess retrospectively whether patients with aorto-iliac aneurysms who fail IIAE have an increase in type II endoleak after EVAR compared with similar patients who undergo successful embolization. We retrospectively analyzed the records of 148 patients who underwent EVAR from December 1997 to June 2005. Sixty-one patients had aorto-iliac aneurysms which required IIAE before EVAR. Fifty patients had successful IIAE and 11 patients had unsuccessful IIAE prior to EVAR. The clinical and imaging follow-up was reviewed before and after EVAR. The endoleak rate of the embolized group was compared with that of the group in whom embolization failed. After a mean follow-up of 19.7 months in the study group and 25 months in the control group, there were no statistically significant differences in outcome measures between the two groups. Specifically, there were no type II endoleaks related to the IIA in patients where IIAE had failed. We conclude that failure to embolize the IIA prior to EVAR should not necessarily preclude patients from treatment. In patients where there is difficulty in achieving coil embolization, it is recommended that EVAR should proceed, as clinical sequelae are unlikely.

  4. What Is the Relevance of the Tip-Apex Distance as a Predictor of Lag Screw Cut-Out?

    PubMed Central

    Goffin, Jérôme M.; Jenkins, Paul J.; Ramaesh, Rishikesan; Pankaj, Pankaj; Simpson, A. Hamish

    2013-01-01

    Using a simple mathematical formulation, the relationship between the position of the lag screw tip (relevant to both intramedullary and extramedullary devices) and the concept of tip-apex distance (TAD) was derived. TAD is widely used in operating theaters as a surgical guideline in relation to the fixation of trochanteric fractures, and in clinical studies as a predictor of lag screw cut-out. In order to visualize better this concept, the locus of points having the same TAD was plotted and the dependence of TAD on the location of the lag screw tip was also reported. It was shown that TAD should be adjusted for the size of the femoral head (a variable which varies a lot according to the sex of the patient) while no correlation was found between TAD and bone morphometry indices obtained from micro-CT data (BV/TV and Tb.Th). Therefore, these results seem to suggest that TAD lacks mechanical justification and that predictors which are based on mechanical properties, such as bone density, should be investigated further. PMID:24015184

  5. Multiobjective Optimization Design of Spinal Pedicle Screws Using Neural Networks and Genetic Algorithm: Mathematical Models and Mechanical Validation

    PubMed Central

    Amaritsakul, Yongyut; Chao, Ching-Kong

    2013-01-01

    Short-segment instrumentation for spine fractures is threatened by relatively high failure rates. Failure of the spinal pedicle screws including breakage and loosening may jeopardize the fixation integrity and lead to treatment failure. Two important design objectives, bending strength and pullout strength, may conflict with each other and warrant a multiobjective optimization study. In the present study using the three-dimensional finite element (FE) analytical results based on an L25 orthogonal array, bending and pullout objective functions were developed by an artificial neural network (ANN) algorithm, and the trade-off solutions known as Pareto optima were explored by a genetic algorithm (GA). The results showed that the knee solutions of the Pareto fronts with both high bending and pullout strength ranged from 92% to 94% of their maxima, respectively. In mechanical validation, the results of mathematical analyses were closely related to those of experimental tests with a correlation coefficient of ?0.91 for bending and 0.93 for pullout (P < 0.01 for both). The optimal design had significantly higher fatigue life (P < 0.01) and comparable pullout strength as compared with commercial screws. Multiobjective optimization study of spinal pedicle screws using the hybrid of ANN and GA could achieve an ideal with high bending and pullout performances simultaneously. PMID:23983810

  6. Single screw interrupted thread positive displacement mechanism

    NASA Astrophysics Data System (ADS)

    Boblitt, Wayne W.

    1992-07-01

    A single screw positive displacement compressor mechanism employing shallow gate rotor tooth penetration of the main rotor for purposes of reducing internal leakage and consequent compressor inefficiencies is presented. The invention is provided with an interrupted main rotor thread for purposes of insuring multiple gate rotor teeth meshing with the drive portion of the main rotor thread, thereby reducing gate rotor tooth flank loads in the compressor section of the device. Provision is also made for main rotor thread baffling between the main rotor chamber section and the mechanism inlet.

  7. Magnesium Alloys as a Biomaterial for Degradable Craniofacial Screws

    PubMed Central

    Henderson, Sarah E.; Verdelis, Konstantinos; Maiti, Spandan; Pal, Siladitya; Chung, William L.; Chou, Da-Tren; Kumta, Prashant N.; Almarza, Alejandro J.

    2014-01-01

    Recently, magnesium (Mg) alloys have received significant attention as a potential biomaterial for degradable implants, and this study was directed at evaluating the suitability of Mg for craniofacial bone screws. The objective was to implant screws fabricated from commercially available Mg-alloys (pure Mg and AZ31) in-vivo in a rabbit mandible. First, Mg-alloy screws were compared to stainless steel screws in an in-vitro pull-out test and determined to have a similar holding strength (~40N). A finite element model of the screw was created using the pull-out test data, and the model can be used for future Mg-alloy screw design. Then, Mg-alloy screws were implanted for 4, 8, and 12 weeks, with two controls of an osteotomy site (hole) with no implant and a stainless steel screw implanted for 12 weeks. MicroCT (computed tomography) was used to assess bone remodeling and Mg-alloy degradation, both visually and qualitatively through volume fraction measurements for all time points. Histologic analysis was also completed for the Mg-alloys at 12 weeks. The results showed that craniofacial bone remodeling occurred around both Mg-alloy screw types. Pure Mg had a different degradation profile than AZ31, however bone growth occurred around both screw types. The degradation rate of both Mg-alloy screw types in the bone marrow space and the muscle were faster than in the cortical bone space at 12 weeks. Furthermore, it was shown that by alloying Mg, the degradation profile could be changed. These results indicate the promise of using Mg-alloys for craniofacial applications. PMID:24384125

  8. Endovascular Repair of a Ruptured Mycotic Aneurysm of the Common Iliac Artery

    SciTech Connect

    Mofidi, R. Bhat, R.; Nagy, J.; Griffiths, G. D.; Chakraverty, S.

    2007-09-15

    This report describes the case of a ruptured mycotic aneurysm of the left common iliac artery, successfully treated with endovascular stent-grafting. A 64-year-old woman underwent diagnostic coronary angiography complicated by an infected hematoma of the left groin. Seven days later, she developed methicillin-resistant Staphylococcus aureus septicemia and CT scan evidence of perivascular inflammation around the left common iliac artery. This was followed by rupture of a mycotic aneurysm of the left common iliac artery. The lesion was successfully treated with a stent-graft and prolonged antibiotic therapy, and the patient remains free of infection 10 months later. Accumulating evidence suggests that endovascular repair can be used safely for the repair of ruptured infected aneurysms.

  9. Investigation of the optimal collagen fibre orientation in human iliac arteries.

    PubMed

    Qi, Nan; Gao, Hao; Ogden, Raymond W; Hill, Nicholas A; Holzapfel, Gerhard A; Han, Hai-Chao; Luo, Xiaoyu

    2015-12-01

    The distribution of collagen fibres plays a significant role in the mechanical behaviour of artery walls. Experimental data show that in most artery wall layers there are two (or more) in-plane symmetrically disposed families of fibres. However, a recent investigation revealed that some artery wall layers have only one preferred fibre direction, notably in the medial layer of human common iliac arteries. This paper aims to provide a possible explanation for this intriguing phenomenon. An invariant-based constitutive model is utilized to characterize the mechanical behaviour of tissues. We then use three different hypotheses to determine the 'optimal fibre angle' in an iliac artery model. All three hypotheses lead to the same result that the optimal fibre angle in the medial layer of the iliac artery is close to the circumferential direction. The axial pre-stretch, in particular, is found to play an essential role in determining the optimal fibre angle. PMID:26195342

  10. Quality Improvement Guidelines for Endovascular Treatment of Iliac Artery Occlusive Disease

    SciTech Connect

    Tsetis, Dimitrios Uberoi, Raman

    2008-03-15

    Endovascular therapy is the treatment of choice for type A and the preferred treatment for type B lesions. In selective patients, this type of treatment can be applied in type C and even type D lesions. Ipsilateral femoral, contralateral femoral, and brachial approach and both the intraluminal and subintimal space can be used for successful recanalization. The application of stents has improved the immediate hemodynamic and probably long-term clinical results of iliac percutaneous transluminal angioplasty. However, the superiority of primary or direct stenting over selective stenting has not been proven yet. The choice of stent type depends on lesion morphology and location but otherwise there is insufficient evidence to support the use of a particular stent design. There is insufficient evidence to justify routine use of covered stents. All patients should receive antiaggregant therapy following endovascular recanalization of iliac arteries. There is no consensus regarding prophylaxis with antibiotics in iliac recanalization procedures.

  11. Internal fixation treatments for intertrochanteric fracture: a systematic review and meta-analysis of randomized evidence

    PubMed Central

    Yu, Jiajie; Zhang, Chao; Li, Ling; Kwong, Joey S. W.; Xue, Li; Zeng, Xiantao; Tang, Li; Li, Youping; Sun, Xin

    2015-01-01

    The relative effects of internal fixation strategies for intertrochanteric fracture after operation remain uncertain. We conducted a systematic review and meta-analysis of randomized controlled trials (RCTs) to address this important issue. We searched PubMed, EMBASE and CENTRAL for RCTs that compared different internal fixation implants in patients with intertrochanteric fracture at 6-month follow-up or longer. We ultimately included 43 trials enrolling 6911 patients; most trials were small in sample sizes and events. Their risk of bias was generally unclear due to insufficient reporting. Because of these, no statistically significant differences were present from most of the comparisons across all the outcomes, and no definitive conclusions can be made. However, a number of trials compared two commonly used internal fixation strategies, gamma nail (GN) and sliding hip screw (SHS). There is good evidence suggesting that, compared to SHS, GN may increase the risk of cut out (OR?=?1.87, 95% CI, 1.08 to 3.21), re-operation (OR?=?1.61, 95% CI, 1.02 to 2.53), intra-operative (OR?=?3.14, 95% CI, 1.34 to 7.35) and later fractures (OR?=?3.67, 95% CI, 1.37 to 9.83). Future randomized trials or observational studies that are carefully designed and conducted are warranted to establish the effects of alternative internal fixation strategies for intertrochanteric fracture. PMID:26657600

  12. Arthroscopically assisted percutaneous fixation and bone grafting of a glenoid fossa fracture nonunion.

    PubMed

    Sears, Benjamin W; Lazarus, Mark D

    2012-08-01

    Arthroscopy is commonly used for evaluating intra-articular fracture patterns and assessing postfixation reduction; however, the use of arthroscopy for the definitive treatment of articular fracture nonunion has not been reported. This article describes a case of symptomatic glenoid fossa fracture nonunion that was successfully treated with arthroscopically assisted percutaneous screw fixation and bone grafting. A 48-year-old laborer sustained a glenoid fossa fracture following a fall from a height. An initial period of nonoperative management was attempted; however, the patient reported continued shoulder pain during his rehabilitation course. Imaging 5 months after injury showed no osseous union at the fracture. Using an arthroscopically assisted technique, percutaneous fixation and bone grafting of the nonunion with cancellous allograft was performed. Postoperatively, the patient progressed through a structured therapy program, and his pain improved. A computed tomography scan 4 months postoperatively showed osseous union at the fracture site. To the authors' knowledge, this is the first report in the literature of definitive arthroscopically assisted bone grafting and percutaneous fixation of a diarthrodial joint nonunion. Advantages of arthroscopic fixation of glenoid fossa fracture nonunion include avoiding potential axillary nerve injury and preserving the native subscapularis insertion, which may be important if subsequent procedures require access to the anterior access to the joint. PMID:22868621

  13. Asymmetric Posterior Thoracolumbar Fixation following a Posterolateral Transpedicular Approach for Unilateral Vertebral Disease

    PubMed Central

    YILMAZ, Murat; KARAKASLI, Ahmet; KALEMCI, Orhan; KIZMAZOGLU, Ceren; YUKSEL, Zafer K.; ARDA, Nuri M.; YUCESOY, Kemal

    The present study aimed to evaluate the clinical outcomes of patients who underwent asymmetrical posterior screw fixation for the treatment of unilateral posterior vertebral pathological entities. The study included 21 patients with a spinal tumor who underwent asymmetrical posterior spinal fusion surgery between April 2009 and March 2012. The American Spinal Injury Association (ASIA) motor score visual analog scale (VAS) score were used as the outcome measure at admission and follow-up. Among the 21 patients, 12 were male and 9 were female, and mean age was 50.71 (range, 24–78) years. Mean follow-up was 16.04 (range, 4–47) months. Postoperatively, neurological findings did not deteriorate in any of the patients. Among the ASIA grade C and D patients, eight (38%) of them exhibited clinical stability or recovery to ASIA E, whereas none of the ASIA B patients scores changed postoperatively. Perioperative complications were noted in six patients (28%). Spinal stability and fusion were achieved in 18 (85%) patients. The surgical asymmetrical fixation technique described reduced the duration of surgery, and the patients required less dissection of paraspinal muscles than bilateral symmetrical fixation. Asymmetrical fixation provides good stabilization for unilateral thoracolumbar vertebral pathological entities, and facilitates rapid rehabilitation of such patients, who are often elderly with comorbidities. PMID:25797773

  14. Molybdenum Trafficking for Nitrogen Fixation

    PubMed Central

    Hernandez, Jose A.; George, Simon J.; Rubio, Luis M.

    2009-01-01

    The molybdenum nitrogenase is responsible for most biological nitrogen fixation, a prokaryotic metabolic process that determines the global biogeochemical cycles of nitrogen and carbon. Here we describe the trafficking of molybdenum for nitrogen fixation in the model diazotrophic bacterium Azotobacter vinelandii. The genes and proteins involved in molybdenum uptake, homeostasis, storage, regulation, and nitrogenase cofactor biosynthesis are reviewed. Molybdenum biochemistry in A. vinelandii reveals unexpected mechanisms and a new role for iron-sulfur clusters in the sequestration and delivery of molybdenum. PMID:19772354

  15. NCI-Frederick PHL - Fixatives and Solutions

    Cancer.gov

    Services Price List Courier Services & Shipment Procedures Scheduling Contact Information Related Links Establishing an Account PHL Forms Staff Publications PHL Portal Fixatives and Solutions Routine fixatives: 10% Neutral Buffered Formalin (NBF) 37

  16. Missing nitrogen fixation in the Benguela region

    NASA Astrophysics Data System (ADS)

    Wasmund, Norbert; Struck, Ulrich; Hansen, Anja; Flohr, Anita; Nausch, Günther; Grüttmüller, Annett; Voss, Maren

    2015-12-01

    Opposing opinions on the importance of nitrogen fixation in the northern Benguela upwelling region provoked us to investigate the magnitude of nitrogen fixation in front of northern Namibia and southern Angola. Measurements of nitrogen fixation rates using the 15N method at 66 stations during seven cruises from 2008 to 2014 showed that, in general, the 15N content in the biomass did not increase after tracer incubation with 15N2, indicating that no nitrogen fixation occurred. Correspondingly, the filamentous nitrogen-fixing cyanobacterium Trichodesmium was almost not present. The abundant picocyanobacteria did obviously not perform nitrogen fixation to a significant degree. The artificial improvement of conditions for nitrogen fixation in mesocosm experiments, including phosphate and iron additions and a warmer temperature, failed to induce nitrogen fixation. A plausible explanation of these findings is a lack of conditioned cells for nitrogen fixation in the Benguela region.

  17. The management of large bilateral internal iliac artery aneurysms using the T-Stat Colon Oximeter.

    PubMed

    Lee, Eugene S; Dawson, David L

    2010-01-01

    Internal iliac artery (IIA) aneurysms are rare and the repair of these aneurysms is associated with high risk of morbidity and mortality. Bilateral IIA aneurysms add an increased concern for ischemic complications. A case is presented where the use of a Food and Drug Administration-approved device, the T-Stat Colon Oximeter, allowed additional information for the safe and successful hybrid exclusion of bilateral large IIA aneurysms. A staged approach with the use of Amplatzer plugs, Powerlink device, Zenith iliac plug, and a femoral-femoral bypass allowed successful exclusion of the IIA aneurysms. The immediate and 18-month follow-up of the IIA aneurysms are reported. PMID:19762207

  18. Left External Iliac and Common Femoral Artery Occlusion Following Blunt Abdominal Trauma without Associated Bone Injury

    PubMed Central

    Byun, Chun Sung; Park, Il Hwan; Do, Hye-jin; Bae, Keum Seok; Oh, Joong Hwan

    2015-01-01

    Blunt abdominal trauma may cause peripheral vascular injuries. However, blunt abdominal trauma rarely results in injuries to the external iliac and common femoral arteries, which often stem from regional bone fractures. Here, we present the case of a patient who had experienced trauma in the lower abdominal and groin area three months before presenting to the hospital, but these injuries did not involve bone fractures and had been managed conservatively. The patient came to the hospital because of left lower leg claudication that gradually became severe. Computed tomography angiography confirmed total occlusion of the external iliac and common femoral arteries. The patient underwent femorofemoral bypass grafting and was discharged uneventfully. PMID:26078931

  19. Aberrant Ovarian Collateral Originating from External Iliac Artery During Uterine Artery Embolization

    SciTech Connect

    Kwon, Joon Ho; Kim, Man Deuk Lee, Kwang-hun; Lee, Myungsu; Lee, Mu Sook; Won, Jong Yun; Park, Sung Il; Lee, Do Yun

    2013-02-15

    We report a case of a 35-year-old woman who underwent uterine artery embolization (UAE) for symptomatic multiple uterine fibroids with collateral aberrant right ovarian artery that originated from the right external iliac artery. We believe that this is the first reported case in the literature of this collateral uterine flow by the right ovarian artery originated from the right external iliac artery. We briefly present the details of the case and review the literature on variations of ovarian artery origin that might be encountered during UAE.

  20. Standard of Practice for the Interventional Management of Isolated Iliac Artery Aneurysms

    SciTech Connect

    Uberoi, Raman; Tsetis, Dimitrios; Shrivastava, Vivek; Morgan, Robert; Belli, Anna-Maria

    2011-02-15

    Isolated iliac artery aneurysms are uncommon, comprising less than 2% of all abdominal aneurysmal disease. Although they have a fairly innocuous natural history, when they have attained a large size they carry a significant risk of rupture. Rupture is associated with significant morbidity and mortality. Therefore, an early diagnosis and treatment are crucial. Over the last decade, interventional treatment options have become established alternatives to open surgical repair. These guidelines aim to review the pathogenesis, natural history, and presentation of isolated iliac artery aneurysms including a description of imaging and interventional treatment strategies.

  1. Periodic Stresses in Gyroscopic Bodies, with Applications to Air Screws

    NASA Technical Reports Server (NTRS)

    Zahm, A F

    1918-01-01

    Report discusses periodic stresses in gyroscopic bodies with applications to air screws caused by particle mass. Report concludes that all modern air screws obey the laws found for plane groups of particles. In particular the two-bladers exert on the shaft a rhythmic gyroscopic torque; the multibladers a steady one; both easily calculable for any given conditions of motion and mass distribution.

  2. COMPOSITES AND MANUFACTURED PRODUCTS SCREW-HOLDING CAPACITY OF

    E-print Network

    , and ness, bending stiffness and strength), wood species (pine vs. sweetgum) had an millworkmarkets/32 between its components. For maximum joints or constructions at complete water- inch (18 ram). The product nificantly alter the screw-holding capac- els were cut for bending modulus of elas- (screw or nail

  3. Introduction High-shear wet granulation by twin screw extrusion

    E-print Network

    Thompson, Michael

    1 Introduction High-shear wet granulation by twin screw extrusion machinery is an emerging and compaction16,17 . Wet granulation in a twin screw extruder is particularly useful with many screwdesign1,11,12 ,machinetype2 ,auxiliaryequipmentcon- figuration11 , and feeding strategies of all

  4. 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. PMID:25402966

  5. A Robot-Assisted Surgical System Using a Force-Image Control Method for Pedicle Screw Insertion

    PubMed Central

    Tian, Wei; Han, Xiaoguang; Liu, Bo; Liu, Yajun; Hu, Ying; Han, Xiao; Xu, Yunfeng; Fan, Mingxing; Jin, Haiyang

    2014-01-01

    Objective To introduce a robot-assisted surgical system for spinal posterior fixation that can automatically recognize the drilling state and stop potential cortical penetration with force and image information and to further evaluate the accuracy and safety of the robot for sheep vertebra pedicle screw placement. Methods The Robotic Spinal Surgery System (RSSS) was composed of an optical tracking system, a navigation and planning system, and a surgical robot equipped with a 6-DOF force/torque sensor. The robot used the image message and force signals to sense the different operation states and to prevent potential cortical penetration in the pedicle screw insertion operation. To evaluate the accuracy and safety of the RSSS, 32 screw insertions were conducted. Furthermore, six trajectories were deliberately planned incorrectly to explore whether the robot could recognize the different drilling states and immediately prevent cortical penetration. Results All 32 pedicle screws were placed in the pedicle without any broken pedicle walls. Compared with the preoperative planning, the average deviations of the entry points in the axial and sagittal views were 0.50±0.33 and 0.65±0.40 mm, and the average deviations of the angles in the axial and sagittal views were 1.9±0.82° and 1.48±1.2°. The robot successfully recognized the different drilling states and prevented potential cortical penetration. In the deliberately incorrectly planned trajectory experiments, the robot successfully prevented the cortical penetration. Conclusion These results verified the RSSS’s accuracy and safety, which supported its potential use for the spinal surgery. PMID:24466043

  6. Surgical anatomy of the common iliac veins during para-aortic and pelvic lymphadenectomy for gynecologic cancer

    PubMed Central

    Tate, Shinichi; Nishikimi, Kyoko; Shozu, Makio

    2014-01-01

    Objective Compression of the left common iliac vein between the right common iliac artery and the vertebrae is known to be associated with the occurrence of left iliofemoral deep vein thrombosis (DVT). In this study, we described the variability in vascular anatomy of the common iliac veins and evaluated the relationship between the degree of iliac vein compression and the presence of DVT using the data from surgeries for gynecologic cancer. Methods The anatomical variations and the degrees of iliac vein compression were determined in 119 patients who underwent systematic para-aortic and pelvic lymphadenectomy during surgery for primary gynecologic cancer. Their medical records were reviewed with respect to patient-, disease-, and surgery-related data. Results The degrees of common iliac vein compression were classified into three grades: grade A (n=28, 23.5%), with a calculated percentage of 0%-25% compression; grade B (n=47, 39.5%), with a calculated percentage of 26%-50% compression; and grade C (n=44, 37%), with a calculated percentage of more than 50% compression. Seven patients (5.9%) had common iliac veins with anomalous anatomies; three were divided into small caliber vessels, two with a flattened structure, and two had double inferior vena cavae. The presence of DVT was associated with the elevated D-dimer levels but not with the degree of iliac vein compression in this series. Conclusion Although severe compression of the common iliac veins was frequently observed, the degree of compression might not be associated with DVT in surgical patients with gynecologic cancer. Anomalous anatomies of common iliac veins should be considered during systematic para-aortic and pelvic lymphadenectomy in the gynecologic cancer patients. PMID:24459583

  7. Tissue fixation and the effect of molecular fixatives on downstream staining procedures

    PubMed Central

    Howat, William J.; Wilson, Beverley A.

    2014-01-01

    It is impossible to underplay the importance of fixation in histopathology. Whether the scientist is interested in the extraction of information on lipids, proteins, RNA or DNA, fixation is critical to this extraction. This review aims to give a brief overview of the current “state of play” in fixation and focus on the effect fixation, and particularly the effect of the newer brand of “molecular fixatives” have on morphology, histochemistry, immunohistochemistry and RNA/DNA analysis. A methodology incorporating the creation of a fixation tissue microarray for the study of the effect of fixation on histochemistry is detailed. PMID:24561827

  8. Binocular Fixation Disparity in Single Word Displays

    ERIC Educational Resources Information Center

    Paterson, Kevin B.; Jordan, Timothy R.; Kurtev, Stoyan

    2009-01-01

    It has been claimed that the recognition of words displayed in isolation is affected by the precise location at which they are fixated. However, this putative role for fixation location has yet to be reconciled with the finding from reading research that binocular fixations are often misaligned and, therefore, more than 1 location in a word is…

  9. 21 CFR 886.1290 - Fixation device.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Fixation device. 886.1290 Section 886.1290 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1290 Fixation device. (a) Identification. A fixation device is an AC-powered device intended for...

  10. Weakly Supervised Human Fixations Prediction.

    PubMed

    Zhang, Luming; Li, Xuelong; Nie, Liqiang; Yang, Yi; Xia, Yingjie

    2016-01-01

    Automatically predicting human eye fixations is a useful technique that can facilitate many multimedia applications, e.g., image retrieval, action recognition, and photo retargeting. Conventional approaches are frustrated by two drawbacks. First, psychophysical experiments show that an object-level interpretation of scenes influences eye movements significantly. Most of the existing saliency models rely on object detectors, and therefore, only a few prespecified categories can be discovered. Second, the relative displacement of objects influences their saliency remarkably, but current models cannot describe them explicitly. To solve these problems, this paper proposes weakly supervised fixations prediction, which leverages image labels to improve accuracy of human fixations prediction. The proposed model hierarchically discovers objects as well as their spatial configurations. Starting from the raw image pixels, we sample superpixels in an image, thereby seamless object descriptors termed object-level graphlets (oGLs) are generated by random walking on the superpixel mosaic. Then, a manifold embedding algorithm is proposed to encode image labels into oGLs, and the response map of each prespecified object is computed accordingly. On the basis of the object-level response map, we propose spatial-level graphlets (sGLs) to model the relative positions among objects. Afterward, eye tracking data is employed to integrate these sGLs for predicting human eye fixations. Thorough experiment results demonstrate the advantage of the proposed method over the state-of-the-art. PMID:26168451

  11. Transit Fixatives: An Innovative Study

    PubMed Central

    A, Ravi Prakash; G, Sreenath; JK, Sonia Bai; NDVN, Shyam

    2015-01-01

    Background: Universally accepted fixative is 10% formalin which has been used for preserving the tissues and their architecture. In certain conditions, formalin might not be readily available for immediate fixation. We here by explore more economical, eco-friendly and easily available solutions that can be used as transit media/ transporting media for tissue specimens. Materials and Methods: The study included commonly available solutions like Spirit, Saline, Betadine solution, Hydrogen peroxide (H2O2), Local anesthesia (L.A), Rose water, Coconut oil, Coconut water, Ice cold water, Honey and Milk while keeping formalin as control. The fresh tissue sample was cut into multiple bits and placed in different containers for a period of 8 hours before transferring to formalin solution. Conclusion: Transit fixatives are very important in certain situations where formalin is not readily available. These fixatives can be used to fix the tissues for a period of at least 8 hours without causing any damage or distortion before they are fixed in formalin solution. PMID:25954725

  12. Lateral Movement of Screw Dislocations During Homoepitaxial Growth and Devices Yielded Therefrom Free of the Detrimental Effects of Screw Dislocations

    NASA Technical Reports Server (NTRS)

    Neudeck, Philip G. (Inventor); Powell, J. Anthony (Inventor)

    2004-01-01

    The present invention is related to a method that enables and improves wide bandgap homoepitaxial layers to be grown on axis single crystal substrates, particularly SiC. The lateral positions of the screw dislocations in epitaxial layers are predetermined instead of random, which allows devices to be reproducibly patterned to avoid performance degrading crystal defects normally created by screw dislocations.

  13. Effect of DDGS, Moisture Content, and Screw Speed on the Physical Properties of Extrudates in Single Screw Extrusion

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Three isocaloric (3.5 kcal/g) ingredient blends containing 20, 30, and 40% (wb) DDGS along with soy flour, corn flour, fish meal, mineral and vitamin mix, with the net protein adjusted to 28% (wb) for all blends, were extruded in a single screw laboratory-scale extruder at screw speeds of 100, 130, ...

  14. Options for acetabular fixation surfaces.

    PubMed

    Klika, Alison K; Murray, Trevor G; Darwiche, Hussein; Barsoum, Wael K

    2007-01-01

    Aseptic loosening is the most common cause for revision total hip arthroplasty (THA). Due to poor long-term results with cemented acetabular components, cementless implants that rely on biologic fixation became popular in the United States for both primary and revision procedures in the early 1980s. Cementless acetabular components used in THA have been reported to have superior radiographic performance compared with cemented fixation, although the optimal method of acetabular fixation remains controversial. Cementless acetabular components require initial implant stability to allow for bone ingrowth and remodeling into the acetabular shell, providing long-term durability of the prosthesis. Many improved implant materials are available to facilitate bone growth and remodeling, including the 3 most common surface treatments; fibermesh, sintered beads, and plasma spray coatings. Recently added to these are porous metal surfaces, which have increased porosity and optimal pore sizes when compared with titanium fibermesh. The most studied of these materials is the titanium fibermesh fixation surface, which has demonstrated a mechanical failure rate of 1% at 10 to 15 years. This technology utilizes the diffusion bonding process to attach fiber metal pads to a titanium substrate using heat and pressure. The sintered bead fixation surface offers a porous coating of various sizes of spherical beads, achieved by the sintering process, and has been shown to provide long-term fixation. While there are less long-term published data regarding the titanium plasma spray surface, its early results have provided evidence of its durability, even in the face of significant osteolysis. The most recently added alternative fixation surface is porous tantalum metal, which offers potentially greater bone ingrowth and bone graft incorporation due to its high porosity (80%) and low modulus of elasticity (3 MPa). Porous tantalum implants have shown early favorable clinical results and have been reported to have excellent bone graft incorporation of the acetabular component based on serial radiograph data at a minimum 1-year follow-up. Tritanium is a porous metal, which has emerged as a promising new surface technology for acetabular shells. While no clinical data are yet available, basic science research has demonstrated enhanced bone ingrowth and mechanical strength. PMID:19023943

  15. A New "Trapdoor technique" for Fixation of Displaced Greater Tuberosity Fractures of the Shoulder.

    PubMed

    McLaughlin-Symon, Iain; Kenyon, Peter; Morgan, Barnes; Ravenscroft, Matt

    2015-12-01

    Isolated greater tuberosity fractures of the proximal humerus are frequently displaced posteriorly and superiorly by the pull of the rotator cuff. This displacement can lead to a decline in function if left untreated. Traditionally these fractures have been treated surgically using screw fixation. On occasions this metalwork can remain prominent and potentially cause impingement. We present a new surgical "trapdoor" technique for fixation of isolated greater tuberosity fractures which can avoid these problems and be utilised either open or arthroscopically. Following reduction of the isolated greater tuberosity fragment, two double loaded metal screw in anchors are placed through stab incisions in the rotator cuff at the bone-tendon interface and secured into the humeral head. A suture from each of the anchors is tied together to secure the tuberosity fragment proximally and a suture-less anchor is inserted distal to the fracture site forming an inverted triangle. The remaining sutures are placed through the suture-less anchor and tensioned independently. As the sutures are tied and snugged tight, the distal aspect of the fracture reduces, thus closing the "trapdoor." This is a newly described versatile technique that can be used regardless of the size and comminution of the tuberosity fragment and can be performed either open or arthroscopically. It avoids the problems of metalwork prominence and irritation and the use of the suture-less anchor allows independent tensioning of the sutures to ensure adequate fracture reduction. PMID:26578824

  16. Understanding Nitrogen Fixation

    SciTech Connect

    Paul J. Chirik

    2012-05-25

    The purpose of our program is to explore fundamental chemistry relevant to the discovery of energy efficient methods for the conversion of atmospheric nitrogen (N{sub 2}) into more value-added nitrogen-containing organic molecules. Such transformations are key for domestic energy security and the reduction of fossil fuel dependencies. With DOE support, we have synthesized families of zirconium and hafnium dinitrogen complexes with elongated and activated N-N bonds that exhibit rich N{sub 2} functionalization chemistry. Having elucidated new methods for N-H bond formation from dihydrogen, C-H bonds and Broensted acids, we have since turned our attention to N-C bond construction. These reactions are particularly important for the synthesis of amines, heterocycles and hydrazines with a range of applications in the fine and commodity chemicals industries and as fuels. One recent highlight was the discovery of a new N{sub 2} cleavage reaction upon addition of carbon monoxide which resulted in the synthesis of an important fertilizer, oxamide, from the diatomics with the two strongest bonds in chemistry. Nitrogen-carbon bonds form the backbone of many important organic molecules, especially those used in the fertilizer and pharamaceutical industries. During the past year, we have continued our work in the synthesis of hydrazines of various substitution patterns, many of which are important precursors for heterocycles. In most instances, the direct functionalization of N{sub 2} offers a more efficient synthetic route than traditional organic methods. In addition, we have also discovered a unique CO-induced N{sub 2} bond cleavage reaction that simultaneously cleaves the N-N bond of the metal dinitrogen compound and assembles new C-C bond and two new N-C bonds. Treatment of the CO-functionalized core with weak Broensted acids liberated oxamide, H{sub 2}NC(O)C(O)NH{sub 2}, an important slow release fertilizer that is of interest to replace urea in many applications. The synthesis of ammonia, NH{sub 3}, from its elements, H{sub 2} and N{sub 2}, via the venerable Haber-Bosch process is one of the most significant technological achievements of the past century. Our research program seeks to discover new transition metal reagents and catalysts to disrupt the strong N {triple_bond} N bond in N{sub 2} and create new, fundamental chemical linkages for the construction of molecules with application as fuels, fertilizers and fine chemicals. With DOE support, our group has discovered a mild method for ammonia synthesis in solution as well as new methods for the construction of nitrogen-carbon bonds directly from N{sub 2}. Ideally these achievements will evolve into more efficient nitrogen fixation schemes that circumvent the high energy demands of industrial ammonia synthesis. Industrially, atmospheric nitrogen enters the synthetic cycle by the well-established Haber-Bosch process whereby N{sub 2} is hydrogenated to ammonia at high temperature and pressure. The commercialization of this reaction represents one of the greatest technological achievements of the 20th century as Haber-Bosch ammonia is responsible for supporting approximately 50% of the world's population and serves as the source of half of the nitrogen in the human body. The extreme reaction conditions required for an economical process have significant energy consequences, consuming 1% of the world's energy supply mostly in the form of pollution-intensive coal. Moreover, industrial H{sub 2} synthesis via the water gas shift reaction and the steam reforming of methane is fossil fuel intensive and produces CO{sub 2} as a byproduct. New synthetic methods that promote this thermodynamically favored transformation ({Delta}G{sup o} = -4.1 kcal/mol) under milder conditions or completely obviate it are therefore desirable. Most nitrogen-containing organic molecules are derived from ammonia (and hence rely on the Haber-Bosch and H{sub 2} synthesis processes) and direct synthesis from atmospheric nitrogen could, in principle, be more energy-efficient. This is particularly attractive giv

  17. The Effect of Iliac Crest Autograft on the Outcome of Fusion in the Setting of Degenerative Spondylolisthesis

    PubMed Central

    Radcliff, Kristen; Hwang, Raymond; Hilibrand, Alan; Smith, Harvey E.; Gruskay, Jordan; Lurie, Jon D.; Zhao, Wenyan; Albert, Todd; Weinstein, James

    2012-01-01

    Background: There is considerable controversy about the long-term morbidity associated with the use of posterior autologous iliac crest bone graft for lumbar spine fusion procedures compared with the use of bone-graft substitutes. The hypothesis of this study was that there is no long-term difference in outcome for patients who had posterior lumbar fusion with or without iliac crest autograft. Methods: The study population includes patients enrolled in the degenerative spondylolisthesis cohort of the Spine Patient Outcomes Research Trial who underwent lumbar spinal fusion. Patients were divided according to whether they had or had not received posterior autologous iliac crest bone graft. Results: There were 108 patients who had fusion with iliac crest autograft and 246 who had fusion without iliac crest autograft. There were no baseline differences between groups in demographic characteristics, comorbidities, or baseline clinical scores. At baseline, the group that received iliac crest bone graft had an increased percentage of patients who had multilevel fusions (32% versus 21%; p = 0.033) and L5-S1 surgery (37% versus 26%; p = 0.031) compared with the group without iliac crest autograft. Operative time was higher in the iliac crest bone-graft group (233.4 versus 200.9 minutes; p < 0.001), and there was a trend toward increased blood loss (686.9 versus 582.3; p = 0.057). There were no significant differences in postoperative complications, including infection or reoperation rates, between the groups. On the basis of the numbers available, no significant differences were detected between the groups treated with or without iliac crest bone graft with regard to the scores on Short Form-36, Oswestry Disability Index, Stenosis Bothersomeness Index, and Low Back Pain Bothersomeness Scale or the percent of patient satisfaction with symptoms averaged over the study period. Conclusions: The outcome scores associated with the use of posterior iliac crest bone graft for lumbar spinal fusion were not significantly lower than those after fusion without iliac crest autograft. Conversely, iliac crest bone-grafting was not associated with an increase in the complication rates or rates of reoperation. On the basis of these results, surgeons may choose to use iliac crest bone graft on a case-by-case basis for lumbar spinal fusion. Level of Evidence: Therapeutic Level II. See Instructions for Authors for a complete description of levels of evidence. PMID:22878599

  18. British Society of Interventional Radiology Iliac Artery Angioplasty-Stent Registry III.

    PubMed

    Uberoi, Raman; Milburn, Simon; Moss, Jon; Gaines, Peter

    2009-09-01

    The objective of this study was to audit current practice in iliac artery intervention in the United Kingdom. In 2001 the British Society of Interventional Radiology Iliac Artery Angioplasty-Stent (BIAS) III registry provided the first national database for iliac intervention. It recommended that data collection needed to continue in order to facilitate the dissemination of comparative data to individual units. BIAS III was designed to continue this work and has a simplified data set with an online submission form. Interventionalists were invited to complete a 3-page tick sheet for all iliac angioplasties and stents. Questions covered risk factors, procedural data, and outcome. Data for 2233 patients were submitted from 37 institutions over a 43-month period. Consultants performed 80% of the procedures, 62% of which were for claudication. Fifty-four percent of lesions were treated with stents and 25% of patients underwent bilateral intervention, resulting in a residual stenosis of <50% in 98%. Ninety-seven percent of procedures had no limb complication and there was a 98% inpatient survival rate. In conclusion, these figures provide an essential benchmark for both audit and patient information. National databases need to be expanded across the range of interventional procedures, and their collection made simple and, preferably, online. PMID:19644643

  19. Primary Stenting for Complex Atherosclerotic Plaques in Aortic and Iliac Stenoses

    SciTech Connect

    Onal, Baran; Ilgit, Erhan T.; Yuecel, Cem; Ozbek, Erdal; Vural, Murat; Akpek, Sergin

    1998-09-15

    Purpose: To evaluate the efficacy of primary stenting for complex atherosclerotic plaques in aortic and iliac stenoses that are not amenable to balloon angioplasty alone. Methods: Nineteen patients with complex atherosclerotic plaques were treated with a Palmaz stent (n= 19), Wallstent (n= 1), Strecker stent (n= 1), or Memotherm stent (n= 1). A total of 22 stenoses presenting with complex plaque morphology including ulcerated plaques, ulcerated plaques with focal aneurysms, plaques with heavy calcification, severely eccentric plaques, plaques with overhanging edge, and plaques with spontaneous dissection were stented. The lesions were in the aorta (n= 1), common iliac artery (n= 19), or external iliac artery (n= 2). Results: Immediate angiography after stent placement revealed restoration of patency of the stented segment. Focal aneurysms and ulcerated areas were occluded in the follow-up angiographies obtained 4-12 weeks after the procedure. In one case with poor distal runoff and multiple complex lesions of the iliac artery, subacute occlusion occurred. Clinical and angiographic follow-up (3-46 months) revealed patency of all other stented segments. Conclusion: Primary stenting is an effective and reliable approach for complex plaques in stenoses. Patency of the arterial segment with a smooth lumen can be created without the risk of acute complications such as distal embolization, dissection, or occlusion.

  20. Behçet's disease with aneurysm of internal iliac artery and percutaneous treatment†

    PubMed Central

    Memeto?lu, Mehmet Erdem; Kalkan, As?m

    2012-01-01

    Behçet's disease (BD), described in 1937 by Hulusi Behçet, is a multisystemic inflammatory disorder. In this paper, we report a large pseudoaneurysm of the internal iliac artery in a patient who had BD, and was admitted to emergency service complaining of leg pain and the percutaneous treatment of the pathology which followed. PMID:22159243

  1. Using ILIAC to Systematically Plan and Implement a Library Information Literacy Assessment Program for Freshman Classes

    ERIC Educational Resources Information Center

    Gustavson, Amy

    2012-01-01

    In order to prepare for the 2013 SACS reaffirmation, the Joyner Library instruction librarians developed a systematic assessment program using Oakleaf's Information Literacy Instruction Assessment Cycle (ILIAC) to plan for instruction, assess student learning and improve future student learning by reviewing data and enacting changes. The paper…

  2. Investigation of the optimal collagen fibre orientation in human iliac arteries

    E-print Network

    Luo, Xiaoyu

    Investigation of the optimal collagen fibre orientation in human iliac arteries Nan Qia , Hao Gaoa of collagen fibres plays a significant role in the mechanical behaviour of artery walls. Experimental data show that in most artery wall layers there are two (or more) in-plane symmetrically disposed families

  3. Endovascular Treatment of the Internal Iliac Artery in Peripheral Arterial Disease

    SciTech Connect

    Huetink, K. Steijling, J.J.F.; Mali, W.P.T.M.

    2008-03-15

    In patients with peripheral arterial disease not much is known about the relationship between the localization of the pain and the localization of arterial occlusions in the iliac arteries. Occlusions high in the iliac arteries are assumed to be able to induce pain in the buttocks and upper leg as well as pain in the calves. Several case reports show that the symptoms of arteriosclerotic lesions in the internal iliac artery are often atypical and not easy to diagnose. In this report, 3 patients with internal iliac artery occlusions who were treated with percutaneous transluminal angioplasty (PTA) are described. One patient had isolated pain in the buttock region. In the other 2 patients the initial pain was focused on the buttock region with extension to the calves during exercise. After PTA, 2 patients were free of symptoms, while in the other patient the symptoms improved but did not disappear. Future research should clarify the relation between certain arterial occlusions and the location of the pain.

  4. Isolated Spontaneous Dissection of the Common Iliac Artery: Percutaneous Stent Placement in Two Patients

    SciTech Connect

    Kwak, Hyo-Sung; Han, Young-Min Chung, Gyung-Ho; Yu, Hee Chul; Jeong, Yeon-Jun

    2006-10-15

    Isolated spontaneous dissection of the common iliac artery (CIA) is a rare entity. Two patients with this condition were successfully treated by percutaneous stent placement. We emphasize the feasibility of nonsurgical management by percutaneous stent placement for isolated spontaneous dissection of the CIA.

  5. Dietary and mechanically induced rabbit iliac-femoral atherosclerotic lesions: a chemical and morphologic evaluation.

    PubMed

    Bocan, T M; Mueller, S B; Uhlendorf, P D; Ferguson, E; Newton, R S

    1991-06-01

    The effect of combining chronic endothelial injury and intermittent meal feeding of a high and low cholesterol, coconut oil, peanut oil diet on plama lipid and lipoprotein content and on the formation of atherosclerotic lesions within the iliac-femoral artery of rabbits was studied. Alternate feeding of a 1 or 0.1% cholesterol, 3% coconut oil, 3% peanut oil diet for 3 to 14 weeks resulted in a 4- to 11-fold increase in plasma cholesterol with 59 to 79% of the plasma cholesterol eluting in a molecular weight fraction comparable to human low density lipoproteins (LDL). In the iliac-femoral artery, an atherosclerotic intimal lesion with an average cross-sectional area of 0.452 mm2 was present in 98% of the animals. The lesion was typically eccentric in location and contained both superficial- and deep-intimal lipid-filled monocyte-macrophages, extracellular lipid, smooth muscle cells, and extracellular connective tissue matrix. The relative percent lipid composition of the iliac-femoral lesion was 62% cholesteryl ester, 21% free cholesterol, and 17% phospholipid. Thus, we conclude that the combination of meal feeding a cholesterol/fat diet, dietary regimen and chronic mild endothelial injury in the rabbit results in (1) a diet-induced hypercholesterolemia in which LDL appear to be the predominant lipoprotein; and (2) a lesion within the iliac-femoral artery comparable in histologic and chemical composition to a human fatty streak. PMID:2060606

  6. British Society of Interventional Radiology Iliac Artery Angioplasty-Stent Registry III

    SciTech Connect

    Uberoi, Raman Milburn, Simon; Moss, Jon

    2009-09-15

    The objective of this study was to audit current practice in iliac artery intervention in the United Kingdom. In 2001 the British Society of Interventional Radiology Iliac Artery Angioplasty-Stent (BIAS) III registry provided the first national database for iliac intervention. It recommended that data collection needed to continue in order to facilitate the dissemination of comparative data to individual units. BIAS III was designed to continue this work and has a simplified data set with an online submission form. Interventionalists were invited to complete a 3-page tick sheet for all iliac angioplasties and stents. Questions covered risk factors, procedural data, and outcome. Data for 2233 patients were submitted from 37 institutions over a 43-month period. Consultants performed 80% of the procedures, 62% of which were for claudication. Fifty-four percent of lesions were treated with stents and 25% of patients underwent bilateral intervention, resulting in a residual stenosis of <50% in 98%. Ninety-seven percent of procedures had no limb complication and there was a 98% inpatient survival rate. In conclusion, these figures provide an essential benchmark for both audit and patient information. National databases need to be expanded across the range of interventional procedures, and their collection made simple and, preferably, online.

  7. Avulsion fracture of anterior inferior iliac spine complicated by hypertrophic malunion causing femoroacetabular impingement: Case report

    PubMed Central

    Alhaneedi, Ghalib Ahmed; Abdullah, Abdullah Saad A.; Ghouri, Syed Imran; Abuodeh, Yousef; Al Dosari, Mohammed M. Al Ateeq

    2015-01-01

    Introduction Avulsion fractures of the anterior inferior iliac spine are uncommon and such injuries are caused by the sudden forceful contraction of the straight head of rectus femoris muscle while the hip is hyperextended and the knee is flexed. Case presentation This case report describes the condition of 17 year old male footballer who complained of pain in the right groin for duration of 2 years after being involved in forceful sport activity. Detailed history, clinical examination, X-rays and CT scan revealed hypertrophic malunion of avulsion fracture of anterior inferior iliac spine causing an extra-articular type of femoroacetabular impingement. The patient was surgically treated when conservative management was unsuccessful. Discussion This is the first case of hypertrophic malunion of avulsion fracture of anterior inferior iliac spine with femoroacetabular impingement that has been recognized in Qatar. The patient was surgically treated in order to relieve symptoms and avoid osteoarthritis. Conclusion Malunited avulsion fracture of anterior inferior iliac spine can cause extra-articular femoroacetabular impingement. PMID:25974258

  8. Impella 5.0 support in severe peripheral vascular disease via iliac artery approach.

    PubMed

    Kumpati, Ganesh S; Tandar, Anwar; Patel, Amit; Badger, Rodney S; Bull, David A

    2012-01-01

    Impella has been reported to provide hemodynamic support in cardiogenic shock patients, acute myocardial infarction, and high-risk percutaneous coronary intervention. We are reporting the case of using iliac artery cut down for Impella 5.0 in a high-risk percutaneous coronary intervention for a patient with severe ischemic cardiomyopathy who was not a surgical candidate. PMID:23274874

  9. SCREW COMPRESSOR CHARACTERISTICS FOR HELIUM REFRIGERATION SYSTEMS

    SciTech Connect

    Ganni, Venkatarao; Knudsen, Peter; Creel, Jonathan; Arenius, Dana; Casagrande, Fabio; Howell, Matt

    2008-03-01

    The oil injected screw compressors have practically replaced all other types of compressors in modern helium refrigeration systems due to their large displacement capacity, minimal vibration, reliability and capability of handling helium's high heat of compression.At the present state of compressor system designs for helium systems, typically two-thirds of the lost input power is due to the compression system. Therefore it is important to understand the isothermal and volumetric efficiencies of these machines to help properly design these compression systems to match the refrigeration process. This presentation summarizes separate tests that have been conducted on Sullair compressors at the Superconducting Super-Collider Laboratory (SSCL) in 1993, Howden compressors at Jefferson Lab (JLab) in 2006 and Howden compressors at the Spallation Neutron Source (SNS) in 2006. This work is part of an ongoing study at JLab to understand the theoretical basis for these efficiencies and their loss

  10. Parametric Analysis of Orthopedic Screws in Relation to Bone Density

    PubMed Central

    Zanetti, Elisabetta M; Salaorno, Massimiliano; Grasso, Giovanni; Audenino, Alberto L

    2009-01-01

    A global study of geometry and material properties of orthopedic screws was performed, considering not only the effect of each single factor (screw pitch, number of threads, fillet angle, etc.) but also their interactions with respect to bone density. The stress patterns resulting from different screw geometries and bone densities were analyzed using finite element techniques, taking into account different levels of osseointegration between the screw and the bone. These numerical models where validated through experimental pull-out tests, where a pull out force of 120 N produced localized failure of the last thread (stresses above 0.42 MPa). The results of the numerical simulations were then summarised using a multi-factorial parametric analysis. This demonstrated the great relevance of the interaction between bone density and screw pitch, showing that the optimal screw pitch can vary by more than 25% for different densities (0.35 g/cm3 and 0.47 g/cm3, respectively). The parameters calculated by means of the multi-factorial analysis allow the pull out force to be estimated for different osseointegration levels, different screw geometries and material properties, and for different bone densities. The final objective is to determine the best choice of implant for each individual patient. PMID:19587807

  11. Economics of water injected air screw compressor systems

    NASA Astrophysics Data System (ADS)

    Venu Madhav, K.; Kova?evi?, A.

    2015-08-01

    There is a growing need for compressed air free of entrained oil to be used in industry. In many cases it can be supplied by oil flooded screw compressors with multi stage filtration systems, or by oil free screw compressors. However, if water injected screw compressors can be made to operate reliably, they could be more efficient and therefore cheaper to operate. Unfortunately, to date, such machines have proved to be insufficiently reliable and not cost effective. This paper describes an investigation carried out to determine the current limitations of water injected screw compressor systems and how these could be overcome in the 15-315 kW power range and delivery pressures of 6-10 bar. Modern rotor profiles and approach to sealing and cooling allow reasonably inexpensive air end design. The prototype of the water injected screw compressor air system was built and tested for performance and reliability. The water injected compressor system was compared with the oil injected and oil free compressor systems of the equivalent size including the economic analysis based on the lifecycle costs. Based on the obtained results, it was concluded that water injected screw compressor systems could be designed to deliver clean air free of oil contamination with a better user value proposition than the oil injected or oil free screw compressor systems over the considered range of operations.

  12. Comparison of Expansive Pedicle Screw and Polymethylmethacrylate-Augmented Pedicle Screw in Osteoporotic Sheep Lumbar Vertebrae: Biomechanical and Interfacial Evaluations

    PubMed Central

    Zhang, Bo; Xie, Qing-yun; Wang, Cai-ru; Liu, Jin-biao; Liao, Dong-fa; Jiang, Kai; Lei, Wei; Pan, Xian-ming

    2013-01-01

    Background It was reported that expansive pedicle screw (EPS) and polymethylmethacrylate-augmented pedicle screw (PMMA-PS) could be used to increase screw stability in osteoporosis. However, there are no studies comparing the two kinds of screws in vivo. Thus, we aimed to compare biomechanical and interfacial performances of EPS and PMMA-PS in osteoporotic sheep spine. Methodology/Principal Findings After successful induction of osteoporotic sheep, lumbar vertebrae in each sheep were randomly divided into three groups. The conventional pedicle screw (CPS) was inserted directly into vertebrae in CPS group; PMMA was injected prior to insertion of CPS in PMMA-PS group; and the EPS was inserted in EPS group. Sheep were killed and biomechanical tests, micro-CT analysis and histological observation were performed at both 6 and 12 weeks post-operation. At 6-week and 12-week, screw stabilities in EPS and PMMA-PS groups were significantly higher than that in CPS group, but there were no significant differences between EPS and PMMA-PS groups at two study periods. The screw stability in EPS group at 12-week was significantly higher than that at 6-week. The bone trabeculae around the expanding anterior part of EPS were more and denser than that in CPS group at 6-week and 12-week. PMMA was found without any degradation and absorption forming non-biological “screw-PMMA-bone” interface in PMMA-PS group, however, more and more bone trabeculae surrounded anterior part of EPS improving local bone quality and formed biological “screw-bone” interface. Conclusions/Significance EPS can markedly enhance screw stability with a similar effect to the traditional method of screw augmentation with PMMA in initial surgery in osteoporosis. EPS can form better biological interface between screw and bone than PMMA-PS. In addition, EPS have no risk of thermal injury, leakage and compression caused by PMMA. We propose EPS has a great application potential in augmentation of screw stability in osteoporosis in clinic. PMID:24086381

  13. Treatment of a Common Iliac Aneurysm by Endovascular Exclusion Using the Amplatzer Vascular Plug and Femorofemoral Crossover Graft

    SciTech Connect

    Coupe, Nicholas J. Ling, Lynn; Cowling, Mark G.; Asquith, John R.; Hopkinson, Gregory B.

    2009-07-15

    We report our initial experience using the Amplatzer Vascular Plug II (AVP2) in the treatment of a left common iliac aneurysm. Following investigation by computerized tomographic angiography and catheter angiography, a 79-year-old man was found to have a markedly tortuous iliac system, with a left common iliac artery aneurysm that measured 48 mm in maximal diameter. Due to the patient's age and comorbidities the surgical opinion was that conventional open repair was not suitable. However, due to the tortuous nature of the aneurysm and iliac vessels, standard endovascular repair, using either a bifurcated or an aorto-uni-iliac stent graft, was also not possible. A combined approach was used by embolizing the ipsilateral internal iliac artery using coils and excluding the aneurysm using two AVP2 occlusion devices, followed by femorofemoral crossover grafting. Total aneurysm occlusion was achieved using this method and this allowed the patient to have a much less invasive surgical procedure than with conventional open repair of common iliac aneurysms, thus avoiding potential comorbidity and mortality.

  14. Percutaneous fixation with Kirschner wires versus volar locking plate fixation in adults with dorsally displaced fracture of distal radius: randomised controlled trial

    PubMed Central

    Achten, Juul; Parsons, Nick R; Rangan, Amar; Griffin, Damian; Tubeuf, Sandy; Lamb, Sarah E

    2014-01-01

    Objectives To compare the clinical effectiveness of Kirschner wire fixation with locking plate fixation for patients with a dorsally displaced fracture of the distal radius. Design A multicentre two arm parallel group assessor blind randomised controlled trial with 1:1 treatment allocation. Setting 18 trauma centres in the United Kingdom. Participants 461 adults with a dorsally displaced fracture of the distal radius within 3 cm of the radiocarpal joint that required surgical fixation. Patients were excluded if the surgeon thought that the surface of the wrist joint was so badly displaced it required open reduction. Interventions Kirschner wire fixation: wires are passed through the skin over the dorsal aspect of the distal radius and into the bone to hold the fracture in the correct anatomical position. Locking plate fixation: a locking plate is applied through an incision over the volar (palm) aspect of the wrist and secured to the bone with fixed angle locking screws. Main outcome measures Primary outcome measure: validated patient rated wrist evaluation (PRWE). This rates wrist function in two (equally weighted) sections concerning the patient’s experience of pain and disability to give a score out of 100. Secondary outcomes: disabilities of arm, shoulder, and hand (DASH) score, the EuroQol (EQ-5D), and complications related to the surgery. Results The baseline characteristics of the two groups were well balanced, and over 90% of patients completed follow-up. The wrist function of both groups of patients improved by 12 months. There was no clinically relevant difference in the patient rated wrist score at three, six, or 12 months (difference in favour of the plate group was ?1.3, 95% confidence interval ?4.5 to 1.8; P=0.40). Nor was there a clinically relevant difference in health related quality of life or the number of complications in each group. Conclusions Contrary to the existing literature, and against the rapidly increasing use of locking plate fixation, this trial found no difference in functional outcome in patients with dorsally displaced fractures of the distal radius treated with Kirschner wires or volar locking plates. Kirschner wire fixation, however, is cheaper and quicker to perform. Trial registration Current Controlled Trials ISCRTN 31379280. UKCRN 8956. PMID:25096595

  15. Mechanical Thrombectomy of Iliac Vein Thrombosis in a Pig Model Using the Rotarex and Aspirex Catheters

    SciTech Connect

    Minko, P. Bücker, A.

    2013-06-08

    PurposeTo investigate the efficacy and safety of mechanical thrombectomy for iliac vein thrombosis using Rotarex and Aspirex catheters in a pig model.Materials and MethodsIliac vein thrombosis was induced in six pigs by means of an occlusion-balloon catheter and thrombin injection. The presence of thrombi was verified by digital subtraction angiography (DSA) and computed tomography (CT). Thrombectomy was performed using 6F and 8F Rotarex and 6F, 8F, and 10F Aspirex catheters (Straub Medical AG, Wangs, Switzerland). After intervention, DSA and CT were repeated to evaluate the efficacy of mechanical thrombectomy and to exclude local complications. In addition, pulmonary CT was performed to rule out pulmonary embolism. Finally, all pigs were killed, and iliac veins were dissected to perform macroscopic and histological examination.ResultsThrombus induction was successfully achieved in all animals as verified by DSA and CT. Subsequent thrombectomy lead to incomplete recanalization of the iliac veins with residual thrombi in all cases. However, the use of the 6F and 8F Rotarex catheters caused vessel perforation and retroperitoneal hemorrhage in all cases. Application of the Aspirex device caused one small transmural perforation in a vessel treated with a 10F Aspirex catheter, and this was only seen microscopically. Pulmonary embolism was detected in one animal treated with the Rotarex catheters, whereas no pulmonary emboli were seen in animals treated with the Aspirex catheters.ConclusionThe Aspirex catheter allowed subtotal and safe recanalization of iliac vein thrombosis. In contrast, the use of the Rotarex catheter caused macroscopically obvious vessel perforations in all cases.

  16. Large Diameter Limbs for Dilated Common Iliac Arteries in Endovascular Aneurysm Repair. Is It Safe?

    SciTech Connect

    Malagari, Katerina Brountzos, Elias; Gougoulakis, Alexandros; Papathanasiou, Matilda; Alexopoulou, Efthymia; Mastorakou, Renata; Kelekis, Dimitris

    2004-09-15

    In this prospective study we examined whether dilated common iliac arteries (CIAs) can provide a safe distal seal in endovascular aneurysm repair (EVAR) with the use of bifurcated stent grafts with large diameter limbs. Sixteen patients with 26 dilated CIAs with a diameter of {>=}6 mm who were offered EVAR using stent grafts with large diameter limbs were included in the study (Group A). Forty-two patients who also underwent EVAR without iliac dilatation, matched for age, sex and surgical risk were used for comparison (controls-Group B). In group A mean CIA diameter was 18.2 mm (16-28) and mean abdominal aortic aneurysm (AAA) diameter was 6.87 {+-} 1.05 cm; mean age was 77.2 {+-} 4.8 yrs (67-81). Mean follow-up was 33.6 months (2.8 yrs). CIA diameter changes and development of endoleaks were assessed by CT angiography (CTA). Overall iliac dilatation was present in 16/58 of our patients (27.6%). In 10 patients dilatation was bilateral (17.3%). Partial or complete flow to the internal iliac artery (IIA) territories was preserved in all patients post-EVAR. On follow-up, stable caliber of the dilated CIAs was observed in 21 patients (84%), enlargement of 1mm in 3 (16%), and failure of the distal attachment in 1 (6.2%). Compared to the control group there was no statistical significance in the incidence of complications. Dilated common iliac arteries provide a safe distal seal in patients who have undergone EVAR, thus obviating the need for additional endovascular procedures and sparing flow in the IIA vascular bed.

  17. Intersection of screw dislocations in fcc crystals during torsional deformation

    NASA Astrophysics Data System (ADS)

    Myshlyaev, M. M.

    2012-03-01

    Dislocation reactions, including dislocation intersections during various processes in crystals, play an important and often crucial role. This is most pronounced during plastic deformation of crystalline solids, which attracts particular interest from researchers. Intersection of screw dislocations in fcc crystals during their deformation by uniaxial tension and compression was studied by A. Cottrell [1]. It was shown that the intersection of similar screw dislocations moving toward each other results in the formation of interstitial thresholds on them; in the case of intersection of opposite screw dislocations, vacancy thresholds are formed on them.

  18. External fixation in the elderly.

    PubMed

    Andruszkow, Hagen; Pfeifer, Roman; Horst, Klemens; Hildebrand, Frank; Pape, Hans-Christoph

    2015-09-01

    Orthopaedic trauma is an increasingly common problem in geriatric patients. As demands of daily life and recreational activities are increasing in these patients, surgeons need to be able to manage geriatric fractures to achieve good functional results. Reduced bone quality in the elderly presents a considerable challenge and may preclude the use of established surgical stabilisation techniques that are performed in younger trauma patients. Furthermore, pre-existing medical conditions and considerable comorbidities in the elderly could complicate standard surgical procedures that younger patients would be offered. In this respect, application of external fixators represents a validated, minimally-invasive treatment opportunity. This review article summarises the use of external fixation in geriatric trauma patients for wrist fractures, proximal femoral fractures, pelvic fractures, and ankle fractures. Modern modifications, like pin coating with hydroxyapatite, and aspects of pin care will be discussed. PMID:26458299

  19. Direct sonographic-guided superior gluteal artery access for treatment of a previously treated expanding internal iliac artery aneurysm.

    PubMed

    Herskowitz, Michael M; Walsh, James; Jacobs, David T

    2014-01-01

    Isolated internal iliac artery aneurysms are relatively uncommon compared with all aortoiliac aneurysms. Transcatheter treatment with coil embolization is an attractive noninvasive alternative to surgical resection. However, if the aneurysm is insufficiently treated with only proximal coil embolization without concurrent embolization of distal runoff vessels, there is a risk of aneurysm expansion from retrograde collateral flow. We present a case of previously treated internal iliac aneurysm that underwent late rapid expansion. Due to occlusion of the internal iliac artery, direct sonographic-guided puncture of the superior gluteal artery was made in order to access the aneurysm. We believe this is the first reported case of such treatment. PMID:23642921

  20. Vibration analysis of three-screw pumps under pressure loads and rotor contact forces

    NASA Astrophysics Data System (ADS)

    Li, Wanyou; Lu, Hanfeng; Zhang, Yue; Zhu, Chuan; Lu, Xiqun; Shuai, Zhijun

    2016-01-01

    Two main vibration sources in three-screw pumps, the fluid exciting force and the screw contact force, are studied to provide the basis for vibration control in this paper. A fluid exciting force model and a screw contact model are proposed to calculate these forces. An experimental test is carried out to obtain the vibration response of a three-screw pump. A calibrated finite element model of the three-screw pump is used to verify the vibration response under the fluid exciting force and the screw contact force obtained from the proposed models. The results show that the screw contact force is more dominant than the fluid exciting force.

  1. Fixation strategies for retinal immunohistochemistry.

    PubMed

    Stradleigh, Tyler W; Ishida, Andrew T

    2015-09-01

    Immunohistochemical and ex vivo anatomical studies have provided many glimpses of the variety, distribution, and signaling components of vertebrate retinal neurons. The beauty of numerous images published to date, and the qualitative and quantitative information they provide, indicate that these approaches are fundamentally useful. However, obtaining these images entailed tissue handling and exposure to chemical solutions that differ from normal extracellular fluid in composition, temperature, and osmolarity. Because the differences are large enough to alter intercellular and intracellular signaling in neurons, and because retinae are susceptible to crush, shear, and fray, it is natural to wonder if immunohistochemical and anatomical methods disturb or damage the cells they are designed to examine. Tissue fixation is typically incorporated to guard against this damage and is therefore critically important to the quality and significance of the harvested data. Here, we describe mechanisms of fixation; advantages and disadvantages of using formaldehyde and glutaraldehyde as fixatives during immunohistochemistry; and modifications of widely used protocols that have recently been found to improve cell shape preservation and immunostaining patterns, especially in proximal retinal neurons. PMID:25892361

  2. 21. NBS SUIT LAB. THREE GLOVES, HELMET, AND SCREW DRIVER ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    21. NBS SUIT LAB. THREE GLOVES, HELMET, AND SCREW DRIVER TORQUE WRENCH FOR ASSEMBLY AND REPAIR OF BOTH. - Marshall Space Flight Center, Neutral Buoyancy Simulator Facility, Rideout Road, Huntsville, Madison County, AL

  3. 21 CFR 888.3070 - Pedicle screw spinal system.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...SERVICES (CONTINUED) MEDICAL DEVICES ORTHOPEDIC DEVICES Prosthetic Devices § 888.3070 Pedicle screw spinal system. ...22Cr-13Ni-5Mn stainless steel, Ti-6Al-4V, and unalloyed titanium, that allow the surgeon to build an implant...

  4. 21 CFR 888.3070 - Pedicle screw spinal system.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...SERVICES (CONTINUED) MEDICAL DEVICES ORTHOPEDIC DEVICES Prosthetic Devices § 888.3070 Pedicle screw spinal system. ...22Cr-13Ni-5Mn stainless steel, Ti-6Al-4V, and unalloyed titanium, that allow the surgeon to build an implant...

  5. 21 CFR 888.3070 - Pedicle screw spinal system.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...SERVICES (CONTINUED) MEDICAL DEVICES ORTHOPEDIC DEVICES Prosthetic Devices § 888.3070 Pedicle screw spinal system. ...22Cr-13Ni-5Mn stainless steel, Ti-6Al-4V, and unalloyed titanium, that allow the surgeon to build an implant...

  6. 21 CFR 888.3070 - Pedicle screw spinal system.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...SERVICES (CONTINUED) MEDICAL DEVICES ORTHOPEDIC DEVICES Prosthetic Devices § 888.3070 Pedicle screw spinal system. ...22Cr-13Ni-5Mn stainless steel, Ti-6Al-4V, and unalloyed titanium, that allow the surgeon to build an implant...

  7. Screw pumps cost effective for heavy crude operations

    SciTech Connect

    Brennan, J.R. )

    1992-12-21

    This paper reports that in petroleum production, screw pumps fulfill the requirements for pumping crude oil with an API gravity of 20[degrees] or less (0.93 sp gr or greater). In many cases, these pumps provide more efficiency than centrifugal and reciprocating pumps. Heavy crude oils typically have viscosities at pumping temperatures in excess of 500 SSU (100 cSt). While screw pumps can handle viscosities ranging from fractional centistokes to millions of centistokes, the normal range for crude oil, from cost and efficiency viewpoints, is above 100 SSU (20 cSt). Bitumens can also be handled by screw pumps. Invented in 1922, rotary, positive-displacement multiple-screw pumps have been used for pumping fuel for burning, lubricating oil, fluid power, process feed, food, chemicals, synthetic-fiber slurries, general transfer, and many other applications.

  8. Embolization for Acute Small-Bowel Bleeding from the Collateral Artery of the Superior Mesenteric Left Deep Circumflex Iliac Artery Associated with Narrowing of the Bilateral Common External Iliac Arteries

    SciTech Connect

    Shimohira, Masashi Ogino, Hiroyuki; Sasaki, Shigeru; Nishikawa, Hiroko; Shibamoto, Yuta

    2009-03-15

    We present a case of acute small-bowel bleeding from the collateral artery of the superior mesenteric-left deep circumflex iliac artery that was successfully managed by transarterial coil embolization.

  9. GLUTARALDEHYDE FIXATION OF ISOLATED EUCARYOTIC NUCLEI

    E-print Network

    Olins, Ada L.

    sealed under nitrogen . The glutaraldehyde solution was stored at 4 °C and, after opening, was transferred to screw-cap culture tubes, gassed with nitrogen, and kept at 4 °C for periods of up to several

  10. Overcoming fixation with repeated memory suppression.

    PubMed

    Angello, Genna; Storm, Benjamin C; Smith, Steven M

    2015-01-01

    Fixation (blocks to memories or ideas) can be alleviated not only by encouraging productive work towards a solution, but, as the present experiments show, by reducing counterproductive work. Two experiments examined relief from fixation in a word-fragment completion task. Blockers, orthographically similar negative primes (e.g., ANALOGY), blocked solutions to word fragments (e.g., A_L_ _GY) in both experiments. After priming, but before the fragment completion test, participants repeatedly suppressed half of the blockers using the Think/No-Think paradigm, which results in memory inhibition. Inhibiting blockers did not alleviate fixation in Experiment 1 when conscious recollection of negative primes was not encouraged on the fragment completion test. In Experiment 2, however, when participants were encouraged to remember negative primes at fragment completion, relief from fixation was observed. Repeated suppression may nullify fixation effects, and promote creative thinking, particularly when fixation is caused by conscious recollection of counterproductive information. PMID:24575886

  11. Fixational eye movements and binocular vision

    PubMed Central

    Otero-Millan, Jorge; Macknik, Stephen L.; Martinez-Conde, Susana

    2014-01-01

    During attempted visual fixation, small involuntary eye movements–called fixational eye movements–continuously change of our gaze’s position. Disagreement between the left and right eye positions during such motions can produce diplopia (double vision). Thus, the ability to properly coordinate the two eyes during gaze fixation is critical for stable perception. For the last 50 years, researchers have studied the binocular characteristics of fixational eye movements. Here we review classical and recent studies on the binocular coordination (i.e., degree of conjugacy) of each fixational eye movement type: microsaccades, drift and tremor, and its perceptual contribution to increasing or reducing binocular disparity. We also discuss how amblyopia and other visual pathologies affect the binocular coordination of fixational eye movements. PMID:25071480

  12. Early postoperative failure of a new intramedullary fixation device for midshaft clavicle fractures.

    PubMed

    Wilson, David J; Weaver, DeWayne L; Balog, Todd P; Arrington, Edward D

    2013-11-01

    The Sonoma CRx device (Sonoma Orthopedic Products, Santa Rosa, California) is a recently introduced intramedullary device with a flexible shaft that becomes rigid once actuated to allow deployment within the sigmoidal contour of the clavicular shaft. Medial intramedullary cortical purchase is obtained by grippers and lateral purchase through a locking bicortical buttressing screw. This article describes 2 cases of early hardware failure using this device. In both cases, early postoperative radiographs demonstrate adequate initial fracture reduction and implant position. Both patients sustained repeat injuries, one under low physiologic load and the other after returning to mixed martial arts 4 months postoperatively. Implant failure was noted after reinjury in both cases. Complete healing and full return to function was documented for both patients at 2 years. Proper patient selection and counseling regarding the limitations of this intramedullary fixation device are important. Biomechanical comparison of this implant to plate fixation under physiologic loads of combined axial compression and torsion may shed light on differences in fixation stability. PMID:24200452

  13. Screw Instability and Blandford-Znajek Mechanism

    E-print Network

    Li-Xin Li

    2000-01-25

    When magnetic field lines thread a rotating black hole's horizon and connect with remote astrophysical loads, the rotational energy of the black hole can be extracted through the Blandford-Znajek mechanism. Due to the rotation of the black hole, the magnetic field lines are twisted and toroidal components are generated. So poloidal electric currents are induced and the black hole's rotational energy is transported to the astrophysical loads through Poynting flux. The Blandford-Znajek mechanism has been considered to be a possible process for powering extragalactic jets. In this paper we show that due to the screw instability of magnetic field, the toroidal components of the magnetic field, and thus the poloidal currents, cannot exceed the limits given by the Kruskal-Shafranov criterion. This significantly lowers the power of the Blandford-Znajek mechanism when the loads are far from the black hole. So the Blandford-Znajek mechanism can only work efficiently within the neighborhood of the black hole. The implications of the results for the scenario of extragalactic jets powered by the Blandford-Znajek mechanism are discussed.

  14. Helical Screw Expander Evaluation Project. Final report

    SciTech Connect

    McKay, R.

    1982-03-01

    A functional 1-MW geothermal electric power plant that featured a helical screw expander was produced and then tested in Utah in 1978 to 1979 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. Additional testing was performed in Mexico in 1980 under a cooperative test program using the same test array, and machine efficiency was measured at 62% maximum with the rotors partially coated with scale, compared with approximately 54% maximum in Utah with uncoated rotors, confirming the importance of scale deposits within the machine on performance. 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.

  15. External fixation in contemporary fracture management

    PubMed Central

    McCoy, G F; Orr, J F; Templeton, J

    1987-01-01

    Important advances have been made within the last two decades in the field of fracture management. The development of the AO internal fixation system and the advances in cast bracing techniques are but two of the improvements worthy of mention. It is, however, in the field of external fixation of fractures that the greatest advances have been made. This paper traces the history of external fixation up to the present day and discusses, with examples, the application of external fixation in the management of complex limb fractures. ImagesFig 3Fig 4Fig 5Fig 6Fig 7Fig 8Fig 9 PMID:3328364

  16. Investigation of an 11mm diameter twin screw granulator: Screw element performance and in-line monitoring via image analysis.

    PubMed

    Sayin, Ridade; Martinez-Marcos, Laura; Osorio, Juan G; Cruise, Paul; Jones, Ian; Halbert, Gavin W; Lamprou, Dimitrios A; Litster, James D

    2015-12-30

    As twin screw granulation (TSG) provides one with many screw element options, characterization of each screw element is crucial in optimizing the screw configuration in order to obtain desired granule attributes. In this study, the performance of two different screw elements - distributive feed screws and kneading elements - was studied in an 11mm TSG at different liquid-to-solid (L/S) ratios. The kneading element configuration was found to break large granules more efficiently, leading to narrower granule size distributions. While pharmaceutical industry shifts toward continuous manufacturing, inline monitoring and process control are gaining importance. Granules from an 11mm TSG were analysed using the Eyecon™, a real-time high speed direct imaging system, which has been used to capture accurate particle size distribution and particle count. The size parameters and particle count were then assessed in terms of their ability to be a suitable control measure using the Shewhart control charts. d10 and particle count were found to be good indicators of the change in L/S ratio. However, d50 and d90 did not reflect the change, due to their inherent variability even when the process is at steady state. PMID:26385406

  17. Do Fixation Cues Ensure Fixation Accuracy in Split-Fovea Studies of Word Recognition?

    ERIC Educational Resources Information Center

    Jordan, Timothy R.; Paterson, Kevin B.; Kurtev, Stoyan; Xu, Mengyun

    2009-01-01

    Many studies have claimed that hemispheric processing is split precisely at the foveal midline and so place great emphasis on the precise location at which words are fixated. These claims are based on experiments in which a variety of fixation procedures were used to ensure fixation accuracy but the effectiveness of these procedures is unclear. We…

  18. Ruptured Internal Iliac Artery Aneurysm: Staged Emergency Endovascular Treatment in the Interventional Radiology Suite

    SciTech Connect

    Kelckhoven, Bas-Jeroen van Bruijninckx, Boy M. A.; Knippenberg, Bob; Overhagen, Hans van

    2007-07-15

    Ruptured aneurysms of the internal iliac artery (IIA) are rare and challenging to treat surgically. Due to their anatomic location they are difficult to operate on and perioperative morbidity is high. An endovascular approach can be helpful. We recently treated a patient with a ruptured IIA aneurysm in the interventional radiology suite with embolization of the side-branch of the IIA and placement of a covered stent in the ipsilateral common and external iliac arteries. A suitable stent-graft was not available initially and had to be brought in from elsewhere. An angioplasty balloon was temporarily placed across the ostium of the IIA to obtain hemostasis. Two hours later, the procedure was finished by placing the stent-graft.

  19. Mandibular reconstruction using free vascularized iliac crest grafts and dental implants

    PubMed Central

    MOLDOVAN, IULIU; JUNCAR, MIHAI; DINU, CRISTIAN; ONISOR-GLIGOR, FLORIN; ROTAR, HORATIU; BRAN, SIMION; BACIUT, GRIGORE

    2015-01-01

    Background and aim The mandible is frequently affected by tumor masses present in the oral cavity and is included in the tumor ablation procedure, with major functional and esthetic consequences for the patient. A method of high current interest in mandibular reconstruction is based on the use of free vascularized iliac crest grafts, followed by reconstruction using dental implants. Methods This study presents the case of four patients benefiting from this treatment method, and monitors the treatment stages and their clinical evolution after mandibular reconstruction and dental implant placement. Results The postoperative evolution of the patients was favorable, with the integration of the iliac crest grafts and dental implants. After prosthetic loading, the masticatory as well as the esthetic function of the patients was restored to a standard close to the initial one. Conclusions This mandibular reconstruction method proved to be effective, with a high degree of reliability and a significant improvement of the patients’ quality of life.

  20. Nitrogen fixation method and apparatus

    DOEpatents

    Chen, H.L.

    1983-08-16

    A method and apparatus for achieving nitrogen fixation includes a volumetric electric discharge chamber. The volumetric discharge chamber provides an even distribution of an electron beam, and enables the chamber to be maintained at a controlled energy to pressure (E/p) ratio. An E/p ratio of from 5 to 15 kV/atm of O[sub 2]/cm promotes the formation of vibrationally excited N[sub 2]. Atomic oxygen interacts with vibrationally excited N[sub 2] at a much quicker rate than unexcited N[sub 2], greatly improving the rate at which NO is formed. 1 fig.

  1. Nitrogen fixation method and apparatus

    DOEpatents

    Chen, Hao-Lin (Walnut Creek, CA)

    1983-01-01

    A method and apparatus for achieving nitrogen fixation includes a volumetric electric discharge chamber. The volumetric discharge chamber provides an even distribution of an electron beam, and enables the chamber to be maintained at a controlled energy to pressure (E/p) ratio. An E/p ratio of from 5 to 15 kV/atm of O.sub.2 /cm promotes the formation of vibrationally excited N.sub.2. Atomic oxygen interacts with vibrationally excited N.sub.2 at a much quicker rate than unexcited N.sub.2, greatly improving the rate at which NO is formed.

  2. Internal Iliac Artery Aneurysm Embolization with Fibrin Sealant: A Simple and Effective Solution

    SciTech Connect

    Brountzos, Elias N.; Malagari, Katerina; Papathanasiou, Mathildi A.; Gougoulakis, Alexandros; Kelekis, Dimitrios A.

    2003-02-15

    Endovascular treatment of internal iliac artery (IIA) aneurysms is an attractive alternative to surgical management, because the former is associated with less morbidity and mortality.Embolization with coils or exclusion of the IIA orifice with stent -grafts are the preferred techniques. Although uncommon, technical failures occur with reported aneurysm rupture. Two patients with IIA aneurysms are reported here, where we describe successful occlusion of their IIA aneurysms with the use of fibrin sealant, after initial failure of coil embolization.

  3. Preclinical Feasibility of a Technology Framework for MRI-guided Iliac Angioplasty

    PubMed Central

    Rube, Martin A.; Fernandez-Gutierrez, Fabiola; Cox, Benjamin F.; Holbrook, Andrew B.; Houston, J. Graeme; White, Richard D.; McLeod, Helen; Fatahi, Mahsa; Melzer, Andreas

    2015-01-01

    Purpose Interventional MRI has significant potential for image guidance of iliac angioplasty and related vascular procedures. A technology framework with in-room image display, control, communication and MRI-guided intervention techniques was designed and tested for its potential to provide safe, fast and efficient MRI-guided angioplasty of the iliac arteries. Methods A 1.5T MRI scanner was adapted for interactive imaging during endovascular procedures using new or modified interventional devices such as guidewires and catheters. A perfused vascular phantom was used for testing. Pre-, intra- and post-procedural visualization and measurement of vascular morphology and flow was implemented. A detailed analysis of X-Ray fluoroscopic angiography workflow was conducted and applied. Two interventional radiologists and one physician in training performed 39 procedures. All procedures were timed and analyzed. Results MRI-guided iliac angioplasty procedures were successfully performed with progressive adaptation of techniques and workflow. The workflow, setup and protocol enabled a reduction in table time for a dedicated MRI-guided procedure to 6 min 33 s with a mean procedure time of 9 min 2 s, comparable to the mean procedure time of 8 min 42 s for the standard X-Ray guided procedure. Conclusions MRI-guided iliac vascular interventions were found to be feasible and practical using this framework and optimized workflow. In particular the real-time flow analysis was found to be helpful for pre- and post-interventional assessments. Design optimization of the catheters and in vivo experiments are required before clinical evaluation. PMID:25102933

  4. Endovascular treatment of an iliac artery rupture caused by invasive Salmonella spondylodiscitis.

    PubMed

    Kur?un, Ebru; Turunç, Tuba; Ozkan, U?ur; Demiro?lu, Yusuf Ziya

    2014-01-01

    The rate of non-typhoid Salmonella infections has increased remarkably in recent years. Endovascular system infection is one of the most serious forms of extraintestinal Salmonella infection. The abdominal aorta is frequently involved, while bone and joint involvement are rarely seen. We present a rare case of successful endovascular treatment of a left iliac artery rupture and pseudoaneurysm both occurring due to the direct invasion of lumbar spondylodiscitis caused by Salmonella typhimurium. PMID:25230272

  5. Iliac crest autograft versus alternative constructs for anterior cervical spine surgery: Pros, cons, and costs

    PubMed Central

    Epstein, Nancy E.

    2012-01-01

    Background: Grafting choices available for performing anterior cervical diskectomy/fusion (ACDF) procedures have become a major concern for spinal surgeons, and their institutions. The “gold standard”, iliac crest autograft, may still be the best and least expensive grafting option; it deserves to be reassessed along with the pros, cons, and costs for alternative grafts/spacers. Methods: Although single or multilevel ACDF have utilized iliac crest autograft for decades, the implant industry now offers multiple alternative grafting and spacer devices; (allografts, cages, polyether-etherketone (PEEK) amongst others). While most studies have focused on fusion rates and clinical outcomes following ACDF, few have analyzed the “value-added” of these various constructs (e.g. safety/efficacy, risks/complications, costs). Results: The majority of studies document 95%-100% fusion rates when iliac crest autograft is utilized to perform single level ACDF (X-ray or CT confirmed at 6-12 postoperative months). Although many allograft studies similarly quote 90%-100% fusion rates (X-ray alone confirmed at 6-12 postoperative months), a recent “post hoc analysis of data from a prospective multicenter trial” (Riew KD et. al., CSRS Abstract Dec. 2011; unpublished) revealed a much higher delayed fusion rate using allografts at one year 55.7%, 2 years 87%, and four years 92%. Conclusion: Iliac crest autograft utilized for single or multilevel ACDF is associated with the highest fusion, lowest complication rates, and significantly lower costs compared with allograft, cages, PEEK, or other grafts. As spinal surgeons and institutions become more cost conscious, we will have to account for the “value added” of these increasingly expensive graft constructs. PMID:22905321

  6. Abdominal Aortic Aneurysm with a Dilated Common Iliac Artery: Treatment Using a Handmade Bifurcated Stent-Graft with a Wide Iliac Limb End

    SciTech Connect

    Miyayama, Shiro; Matsui, Osamu; Akakura, Yukari; Yamamoto, Toru; Nishida, Hiroto; Yoneda, Kenji; Kawai, Keiichi; Murakami, Shinya

    2003-11-15

    The purpose of this study was to evaluate the usefulness of a bifurcated stent-graft with a wide iliac limb end (WILE) in the treatment of abdominal aortic aneurysm (AAA) with a dilated common iliac artery (CIA) to avoid occlusion of the internaliliac artery (IIA). The WILE, covered with an expanded polytetrafluoroethylene graft which was constructed of large diameter stents according to the individual CIA diameter, was connected to a two-piece bifurcated stent-graft covering a polyester graft. The WILE was placed in eight dilated CIAs of six patients. All but one WILE fitted the dilated CIA well. One did not fit, and coil embolization of the leak was needed. All eight IIA derived from the dilated CIA avoided occlusion. Perigraft leak due to other causes was identified in another two patients. Limb kinking was observed in two patients. Our stent is useful in the treatment of AAA with dilated CIA to avoid occlusion of the IIA, and may extend the indication of endoluminal repair of AAA.

  7. 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

  8. Comparative study on stress distribution around internal tapered connection implants according to fit of cement- and screw-retained prostheses

    PubMed Central

    Lee, Mi-Young; Heo, Seong-Joo; Park, Eun-Jin

    2013-01-01

    PURPOSE The aim of this study was to compare the passivity of implant superstructures by assessing the strain development around the internal tapered connection implants with strain gauges. MATERIALS AND METHODS A polyurethane resin block in which two implants were embedded served as a measurement model. Two groups of implant restorations utilized cement-retained design and internal surface of the first group was adjusted until premature contact between the restoration and the abutment completely disappeared. In the second group, only nodules detectable to the naked eye were removed. The third group employed screw-retained design and specimens were generated by computer-aided design/computer-aided manufacturing system (n=10). Four strain gauges were fixed on the measurement model mesially and distally to the implants. The strains developed in each strain gauge were recorded during fixation of specimens. To compare the difference among groups, repeated measures 2-factor analysis was performed at a level of significance of ?=.05. RESULTS The absolute strain values were measured to analyze the magnitude of strain. The mean absolute strain value ranged from 29.53 to 412.94 µm/m at the different strain gauge locations. According to the result of overall comparison, the cement-retained prosthesis groups exhibited significant difference. No significant difference was detected between milled screw-retained prostheses group and cement-retained prosthesis groups. CONCLUSION Within the limitations of the study, it was concluded that the cement-retained designs do not always exhibit lower levels of stress than screw-retained designs. The internal adjustment of a cement-retained implant restoration is essential to achieve passive fit. PMID:24049573

  9. Fracture repair of the distal portion of the radius by use of a condylar screw implant in an adult horse.

    PubMed

    Rodgerson, D H; Wilson, D A; Kramer, J

    2001-06-15

    An 8-year-old American Quarter Horse gelding was evaluated because of an open fracture involving the left radius. The horse had fallen during training and became immediately non-weight-bearing in the left forelimb. On initial evaluation, the horse was unable to bear weight on that limb; radiography revealed a long oblique fracture of the distal metaphysis of the radius with minimal displacement of the fracture fragments. Because of the configuration of the fracture, we recommended surgical intervention with internal fixation. A condylar screw implant and 4.5-mm broad dynamic compression plate were applied to the medial and dorsolateral aspects of the radius, respectively. The horse recovered in a sling and full-limb bandage. Six months after discharge, the horse was reevaluated because of a grade 4/5 lameness in the same limb. Palpation revealed signs of severe pain over the distomedial aspect of the radius. Radiography of the left radius revealed severe osteolysis beneath the distal aspect of the condylar screw implant. Surgical removal of the medial plate was performed. Sixteen months after the initial fracture repair, the horse had returned to light training without signs of lameness. Removal of the dorsal plate may be indicated if this horse is to return to aggressive training or becomes lame in the left forelimb. PMID:11417743

  10. Absent Right Side Iliac Arterial System, an Intraoperative Surprise during Live Related Recipient Renal Transplantation

    PubMed Central

    Radhakrishnan, Vijay; Kumar, Rana; George, Datson; Abraham, G. P.

    2015-01-01

    Introduction. Renal transplantation has become the standard of care for patients with end stage renal disease. We present a rare case of an absent right sided iliac arterial system encountered during recipient renal transplantation. The presence of such vascular anomaly intraoperatively can present a technically challenging situation to the surgeon. Case Presentation. During a routine renal transplantation of a 34-year-old man, we encountered a complete absence of right side iliac arterial system and a prominent branch arising from left hemipelvis and coursing to the right lower limb and the urinary bladder. The artery to the bladder was divided and anastomosed end to end to the donor renal artery. Intraoperatively the renal perfusion and the urine output were good. A posttransplant magnetic resonance angiogram done six weeks later revealed good vascular supply to the kidney and the lower limb. Conclusion. Absent iliac artery on one or both sides is a rare phenomenon. The presence of it during an unanticipated renal transplant surgery can pose a significant technical challenge to the surgeons. We advocate routine assessment of pelvic vasculature before recipient renal transplant surgery so as to avoid a difficult situation like this. PMID:26347845

  11. Arterial wall lymphangiogenesis is increased in the human iliac atherosclerotic arteries: involvement of CCR7 receptor.

    PubMed

    Grzegorek, Irmina; Drozdz, Katarzyna; Chmielewska, Magdalena; Gomulkiewicz, Agnieszka; Jablonska, Karolina; Piotrowska, Aleksandra; Karczewski, Maciej; Janczak, Dariusz; Podhorska-Okolow, Marzena; Dziegiel, Piotr; Szuba, Andrzej

    2014-12-01

    Twenty-six iliac artery segments were divided in two groups: atherosclerotic (A) and nonatherosclerotic (NA). Expression of LYVE-1, VEGF-C, VEGF-D, and CCR7 receptor were studied with immunohistochemistry (IHC) and Western blot (WB). IHC was performed on 26 samples of iliac arteries obtained from deceased 19 organ donors. The samples were divided into an atherosclerotic group (A) [subjects with history of cardiovascular disease (hypertension, ischemic heart disease) or/and diabetes] (n=16), and a nonatherosclerotic group (NA) [subjects without any known cardiovascular diseases or cardiovascular risk factors] (n=10). WB was performed on 19 iliac artery segments obtained from two groups, based on clinical data: an atherosclerotic group (A) [patients with atherosclerosis, who underwent surgery for lower limb ischemia] (n=10), and a nonatherosclerotic group (NA) [deceased organ donors without cardiovascular diseases/risk factors (n=9)]. Expression of LYVE-1, VEGF-C, VEGF-D, and CCR-7 was increased in atherosclerotic arteries. Positive correlations between LYVE-1 and VEGF-C expression in the intima-media complex assessed by IHC: (r=0.54; p=0.005) and WB: (r=0.47; p=0.005) were found. Positive correlations between expression of CCR-7 and other markers were observed. Lymphangiogenesis is enhanced within the atherosclerotic arterial wall. Our results confirm lymphatic system activation with increased lymphangiogenesis and lymphocyte/macrophage trafficking in atherosclerosis. PMID:25318003

  12. Contrast-enhanced harmonic ultrasonography of medial iliac lymph nodes in healthy dogs.

    PubMed

    Gaschen, Lorrie; Angelette, Nik; Stout, Rhett

    2010-01-01

    Herein, we describe the normal contrast-enhanced harmonic, color, and power Doppler ultrasonographic characteristics of the medial iliac lymph nodes in healthy dogs. Contrast-enhanced harmonic ultrasonography of the medial iliac lymph nodes was performed on 14 healthy dogs after intravenous administration of the lipoprotein-bound inert gas-filled microbubble contrast media Definity. Time-pixel intensity curves were generated for 1-min postinjection. Quantification of these curves was performed using Philips QLab software. Non-contrast-enhanced power and color Doppler examinations were performed in each node to assess vascular patterns subjectively. Normal lymph nodes exhibited a mean contrast wash-in phase beginning at 6.3 s from the time of injection with mean peak pixel intensity at 12.1s. Angioarchitecture was best visualized with contrast-enhanced harmonic ultrasound compared with power and color Doppler. Normal lymph nodes in dogs have a central artery with a centrifugal and uniform branching pattern. Contrast-enhanced harmonic ultrasonography is a noninvasive examination that demonstrates improved visibility of the intranodal architecture of healthy medial iliac lymph nodes in dogs compared with conventional, non-contrast-enhanced Doppler methods that may have future clinical applications. PMID:21158236

  13. The Effect of Endovascular Revascularization of Common Iliac Artery Occlusions on Erectile Function

    SciTech Connect

    Gur, Serkan; Ozkan, Ugur; Onder, Hakan; Tekbas, Gueven; Oguzkurt, Levent

    2013-02-15

    To determine the incidence of erectile dysfunction in patients with common iliac artery (CIA) occlusive disease and the effect of revascularization on erectile function using the sexual health inventory for males (SHIM) questionnaire. All patients (35 men; mean age 57 {+-} 5 years; range 42-67 years) were asked to recall their sexual function before and 1 month after iliac recanalization. Univariate and multivariate analyses were performed to determine variables effecting improvement of impotence. The incidence of impotence in patients with CIA occlusion was 74% (26 of 35) preoperatively. Overall 16 (46%) of 35 patients reported improved erectile function after iliac recanalization. The rate of improvement of impotence was 61.5% (16 of 26 impotent patients). Sixteen patients (46%), including seven with normal erectile function before the procedure, had no change. Three patients (8%) reported deterioration of their sexual function, two of whom (6%) had normal erectile function before the procedure. The median SHIM score increased from 14 (range 4-25) before the procedure to 20 (range 1-25) after the procedure (P = 0.005). The type of recanalization, the age of the patients, and the length of occlusion were related to erectile function improvement in univariate analysis. However, these factors were not independent factors for improvement of erectile dysfunction in multivariate analysis (P > 0.05). Endovascular recanalization of CIA occlusions clearly improves sexual function. More than half of the patients with erectile dysfunction who underwent endovascular recanalization of the CIA experienced improvement.

  14. COMPLEMENT FIXATION IN DISEASED TISSUES

    PubMed Central

    Burkholder, Peter M.

    1961-01-01

    An immunohistologic complement fixation test has been used in an effort to detect immune complexes in sections of kidney from rats injected with rabbit anti-rat kidney serum and in sections of biopsied kidneys from four humans with membranous glomerulonephritis. Sections of the rat and human kidneys were treated with fluorescein-conjugated anti-rabbit globulin or antihuman globulin respectively. Adjacent sections in each case were incubated first with fresh guinea pig serum and then in a second step were treated with fluorescein-conjugated antibodies against fixed guinea pig complement to detect sites of fixation of the complement. It was demonstrated that the sites of rabbit globulin in glomerular capillary walls of the rat kidneys and the sites of localized human globulin in thickened glomerular capillary walls and swollen glomerular endothelial cells of the human kidneys were the same sites in which guinea pig complement was fixed in vitro. It was concluded from these studies that rabbit nephrotoxic antibodies localize in rat glomeruli in complement-fixing antigen-antibody complexes. Furthermore, it was concluded that the deposits of human globulin in the glomeruli of the human kidneys behaved like antibody globulin in complement-fixing antigen-antibody complexes. The significance of demonstrating complement-fixing immune complexes in certain diseased tissues is discussed in regard to determination of the causative role of allergic reactions in disease. PMID:19867205

  15. Eighth international congress on nitrogen fixation. Final program

    SciTech Connect

    Not Available

    1990-12-31

    This volume contains the proceedings of the Eighth International Congress on Nitrogen Fixation held May 20--26, 1990 in Knoxville, Tennessee. The volume contains abstracts of individual presentations. Sessions were entitled Recent Advances in the Chemistry of Nitrogen Fixation, Plant-microbe Interactions, Limiting Factors of Nitrogen Fixation, Nitrogen Fixation and the Environment, Bacterial Systems, Nitrogen Fixation in Agriculture and Industry, Plant Function, and Nitrogen Fixation and Evolution.

  16. INVESTIGATION Population Growth Enhances the Mean Fixation

    E-print Network

    Waxman, David

    INVESTIGATION Population Growth Enhances the Mean Fixation Time of Neutral Mutations of population genetics states that a new mutation, at an unlinked neutral locus in a randomly mating diploid population, has a mean time of fixation of 4Ne generations, where Ne is the effective population size

  17. 21 CFR 886.1290 - Fixation device.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Fixation device. 886.1290 Section 886.1290 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1290 Fixation device. (a) Identification. A...

  18. 21 CFR 886.1290 - Fixation device.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Fixation device. 886.1290 Section 886.1290 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1290 Fixation device. (a) Identification. A...

  19. Whole Animal Perfusion Fixation for Rodents

    PubMed Central

    Gage, Gregory J.; Kipke, Daryl R.; Shain, William

    2012-01-01

    The goal of fixation is to rapidly and uniformly preserve tissue in a life-like state. While placing tissue directly in fixative works well for small pieces of tissue, larger specimens like the intact brain pose a problem for immersion fixation because the fixative does not reach all regions of the tissue at the same rate 5,7. Often, changes in response to hypoxia begin before the tissue can be preserved 12. The advantage of directly perfusing fixative through the circulatory system is that the chemical can quickly reach every corner of the organism using the natural vascular network. In order to utilize the circulatory system most effectively, care must be taken to match physiological pressures 3. It is important to note that physiological pressures are dependent on the species used. Techniques for perfusion fixation vary depending on the tissue to be fixed and how the tissue will be processed following fixation. In this video, we describe a low-cost, rapid, controlled and uniform fixation procedure using 4% paraformaldehyde perfused via the vascular system: through the heart of the rat to obtain the best possible preservation of the brain for immunohistochemistry. The main advantage of this technique (vs. gravity-fed systems) is that the circulatory system is utilized most effectively. PMID:22871843

  20. Biochemical Approaches to Improved Nitrogen Fixation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Improving symbiotic nitrogen fixation by legumes has emerged again as an important topic on the world scene due to the energy crisis and lack of access to nitrogen fertilizer in developing countries. We have taken a biochemical genomics approach to improving symbiotic nitrogen fixation in legumes. L...

  1. UK Fixation of Distal Tibia Fractures (UK FixDT): protocol for a randomised controlled trial of ‘locking’ plate fixation versus intramedullary nail fixation in the treatment of adult patients with a displaced fracture of the distal tibia

    PubMed Central

    Achten, Juul; Parsons, Nicholas R; McGuinness, Katie R; Petrou, Stavros; Lamb, Sarah E; Costa, Matthew L

    2015-01-01

    Introduction The treatment of displaced, extra-articular fractures of the distal tibia remains controversial. These injuries are difficult to manage due to limited soft tissue cover, poor vascularity of the area and proximity to the ankle joint. Surgical treatment options are expanding and include locked intramedullary nails, plate and screw fixation and external fixator systems. The nail and plate options are most commonly used in the UK, but controversy exists over which treatment is most clinically and cost-effective. In this multicentre randomised controlled trial we aim to assess ratings of disability 6?months postinjury in patients who have sustained a distal tibia fracture treated with either an intramedullary nail or plate and locking screw fixation. Methods and analysis Adult patients presenting at trial centres with an acute fracture of the distal tibia will be considered for inclusion. A total of 320 patients will provide 90% power to detect a difference of 8 points in Disability Rating Index (DRI) score at 6?months at the 5% level. The randomisation sequence is stratified by trial centre and age, and administered via web-based service with 1:1 treatment allocation. Baseline demographic and pre-injury functional data and radiographs will be collected using the DRI, Olerud and Molander, and EuroQol EQ-5D questionnaire. Clinical assessment, early complications and radiographs will be recorded at 6–8?weeks. Functional outcome, health-related quality of life and resource use will be collected at 3, 6 and 12?months postoperatively. The main analysis will investigate differences in DRI 6?months postsurgery, between the two treatment groups, on an intention-to-treat basis. Tests will be two-sided and considered to provide evidence for a significant difference if p values are <0.05. Ethics and dissemination NRES Committee West-Midlands, 6/11/2012 (ref:12/WM/0340). The results of the trial will be disseminated via peer-reviewed publications and presentations at relevant conferences. Trial registration number ISRCTN99771224. PMID:26384729

  2. Numerical simulation of a twin screw expander for performance prediction

    NASA Astrophysics Data System (ADS)

    Papes, Iva; Degroote, Joris; Vierendeels, Jan

    2015-08-01

    With the increasing use of twin screw expanders in waste heat recovery applications, the performance prediction of these machines plays an important role. This paper presents a mathematical model for calculating the performance of a twin screw expander. From the mass and energy conservation laws, differential equations are derived which are then solved together with the appropriate Equation of State in the instantaneous control volumes. Different flow processes that occur inside the screw expander such as filling (accompanied by a substantial pressure loss) and leakage flows through the clearances are accounted for in the model. The mathematical model employs all geometrical parameters such as chamber volume, suction and leakage areas. With R245fa as working fluid, the Aungier Redlich-Kwong Equation of State has been used in order to include real gas effects. To calculate the mass flow rates through the leakage paths formed inside the screw expander, flow coefficients are considered as constant and they are derived from 3D Computational Fluid Dynamic calculations at given working conditions and applied to all other working conditions. The outcome of the mathematical model is the P-V indicator diagram which is compared to CFD results of the same twin screw expander. Since CFD calculations require significant computational time, developed mathematical model can be used for the faster performance prediction.

  3. 21 CFR 888.3050 - Spinal interlaminal fixation orthosis.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...Prosthetic Devices § 888.3050 Spinal interlaminal fixation orthosis. (a) Identification. A spinal interlaminal fixation orthosis...spondylolisthesis (a dislocation of the spinal column), and lower back syndrome....

  4. 21 CFR 888.3050 - Spinal interlaminal fixation orthosis.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...Prosthetic Devices § 888.3050 Spinal interlaminal fixation orthosis. (a) Identification. A spinal interlaminal fixation orthosis...spondylolisthesis (a dislocation of the spinal column), and lower back syndrome....

  5. SEM and fractography analysis of screw thread loosening in dental implants.

    PubMed

    Scarano, A; Quaranta, M; Traini, T; Piattelli, M; Piattelli, A

    2007-01-01

    Biological and technical failures of implants have already been reported. Mechanical factors are certainly of importance in implant failures, even if their exact nature has not yet been established. The abutment screw fracture or loosening represents a rare, but quite unpleasant failure. The aim of the present research is an analysis and structural examination of screw thread or abutment loosening compared with screw threads or abutment without loosening. The loosening of screw threads was compared to screw thread without loosening of three different implant systems; Branemark (Nobel Biocare, Gothenburg, Sweden), T.B.R. implant systems (Benax, Ancona, Italy) and Restore (Lifecore Biomedical, Chaska, Minnesota, USA). In this study broken screws were excluded. A total of 16 screw thread loosenings were observed (Group I) (4 Branemark, 4 T.B.R and 5 Restore), 10 screw threads without loosening were removed (Group II), and 6 screw threads as received by the manufacturer (unused) (Group III) were used as control (2 Branemark, 2 T.B.R and 2 Restore). The loosened abutment screws were retrieved and analyzed under SEM. Many alterations and deformations were present in concavities and convexities of screw threads in group I. No macroscopic alterations or deformations were observed in groups II and III. A statistical difference of the presence of microcracks were observed between screw threads with an abutment loosening and screw threads without an abutment loosening. PMID:17897496

  6. Magnetic Resonance Angiography of Nonferromagnetic Iliac Artery Stents and Stent-Grafts: A Comparative Study in Sheep

    SciTech Connect

    Schuermann, Karl; Vorwerk, Dierk; Buecker, Arno; Neuerburg, Joerg; Grosskortenhaus, Stefanie; Haage, Patrick; Piroth, Werner; Hunter, David W.; Guenther, Rolf W.

    1999-09-15

    Purpose: To compare nonferromagnetic iliac artery prostheses in their suitability for patency monitoring with magnetic resonance angiography (MRA) using conventional angiography as a reference. Methods: In experiment 1, three Memotherm stents were inserted into the iliac arteries of each of six sheep: two 'tandem' stents on one side and a single stent on the other side. In experiment 2, four prostheses (normal and low-porosity Corvita stent-grafts, Memotherm, ZA-stent) were inserted in each of 11 sheep. Patency was monitored before and 1, 3, and 6 months after insertion with 3D phase-contrast and two 2D time-of-flight sequences (TOF-1: TR/TE = 18/6.9, TOF-2: 13/2.5) with and without contrast at 1.5 T. On 206 coronal MIP images (72 pre-, 134 post-stenting), three readers analyzed 824 iliac segments (206 x 4) for patency and artifacts. Results: There was no difference in the number of artifacts between tandem and single iliac Memotherm stents. The ZA-stent induced significantly fewer artifacts than the other prostheses (p < 0.00001). With MRA, patency of the ZA-stent was correctly diagnosed in 88% of cases, which was almost comparable to nonstented iliac segments (95%), patency of the Memotherm stent in 59%, and of the Corvita stent-grafts in 57% and 55%. The TOF-2 sequence with contrast yielded the best images. Conclusion: MRA compatibility of nonferromagnetic prostheses depends strongly on the design of the device. MRA may be used to monitor the patency of iliac ZA-stents, whereas iliac Memotherm stents and Corvita stent-grafts appear to be less suited for follow-up with MRA.

  7. Efficiency study of oil cooling of a screw compressor

    SciTech Connect

    Tree, D.R.; McKellar, M.G.

    1989-04-01

    One of the major goals of all compressor manufacturers is to build as efficient a compressor as possible. Over the last several years improvements to the design of screw compressors has made them efficiently competitive with other types of compressors, especially at large loads. The primary purpose of this research is to investigate four different methods of cooling a 250 horsepower compressor and determine their effects on the efficiency of the compressor. Two conventional methods, liquid injection and thermosyphon cooling, and two new methods, V-PLUS and Fresco oil injection, are investigated. The screw compressor used in the tests was a VRS-500 screw compressor made by the Vilter Manufacturing Corporation. 6 figs.

  8. Mild coal gasification screw pyrolyzer development and design

    SciTech Connect

    Camp, D.W.

    1990-08-01

    Our objective is to produce information and design recommendations needed for the development of an efficient continuous process for the mild gasification of caking bituminous coals. We have focused on the development of an externally heated pyrolyzer in which the sticky, reacting coal is conveyed by one or more screws. We have taken a multifaceted approach to forwarding the development of the externally-heated screw pyrolyzer. Small scale process experiments on a 38-mm single screw pyrolyzer have been a major part of our effort. Engineering analyses aimed at producing design and scaleup equations have also been important. Process design recommendations follow from these. We critically review our experimental data and experience, and information from the literature and equipment manufactures for the purpose of making qualitative recommendations for improving practical pyrolyzer design and operation. Benchscale experiments are used to supply needed data and test some preliminary concepts. 6 refs., 4 figs., 1 tab.

  9. Open reduction and internal fixation aided by intraoperative 3-dimensional imaging improved the articular reduction in 72 displaced acetabular fractures.

    PubMed

    Eckardt, Henrik; Lind, Dennis; Toendevold, Erik

    2015-12-01

    Background and purpose - During acetabular fracture surgery, the acetabular roof is difficult to visualize with 2-dimensional fluoroscopic views. We assessed whether intraoperative 3-dimensional (3D) imaging can aid the surgeon to achieve better articular reduction and improve implant fixation. Patients and methods - We operated on 72 acetabular fractures using intraoperative 3D imaging and compared the operative results, duration of surgery, and complications with those for 42 consecutive acetabular fracture operations conducted using conventional fluoroscopic imaging. Postoperative reduction was evaluated on reconstructed coronal and sagittal images of the acetabulum. Results - The fracture severity and patient characteristics were similar in the 2 groups. In the 3D group, 46 of 72 patients (0.6) had a perfect result after open reduction and internal fixation, and in the control group, 17 of 42 (0.4) had a perfect result. The mean difference in postoperative articular incongruity was 0.5 mm (95% CI: 0.4-0.7). In 29 of 72 operations, the intraoperative 3D scans led to intraoperative correction of the reduction and an improved result. The duration of surgery and infection rate were similar in the 2 groups. Interpretation - Intraoperative 3D imaging, which is not time-consuming, allowed the surgeon to correct malreductions and screw placement in 29 of 72 operations, leading to better articular reduction and more precise screw placement than in operations where conventional fluoroscopic imaging was used to control the reduction. PMID:26012545

  10. 29 CFR 1926.305 - Jacks-lever and ratchet, screw, and hydraulic.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...Jacks-lever and ratchet, screw, and hydraulic. 1926.305 Section 1926.305...Jacks—lever and ratchet, screw, and hydraulic. (a) General requirements. ...otherwise secured at once. (ii) Hydraulic jacks exposed to freezing...

  11. Performance Evaluation and CFD Simulation of Multiphase Twin-Screw Pumps 

    E-print Network

    Patil, Abhay

    2013-05-16

    work focuses on the experimental and numerical analysis of twin-screw pumps for different operating conditions. Experimental evaluation aims to understand steady state and transient behavior of twin-screw pumps. Detailed steady state evaluation helped...

  12. Biodegradation of Inion fast-absorbing biodegradable plates and screws.

    PubMed

    Losken, H Wolfgang; van Aalst, John A; Mooney, Mark P; Godfrey, Virginia L; Burt, Tripti; Teotia, Sumeet; Dean, Shay B; Moss, Jonathan R; Rahbar, Reza

    2008-05-01

    Biodegradable plates and screws are recommended for use in surgery of the craniofacial skeleton of children. To be effective and not interfere with growth of the child's skull, the plates must biodegrade sufficiently to release the holding power of the plate and screw within 1 year. It is also essential that excessive foreign body reaction and cyst formation does not occur when the plates and screws biodegrade. The purpose of this experimental study was to evaluate the rate of biodegradation of Inion CPS Baby biodegradable plates and screws under different clinical circumstances in the rabbit craniofacial skeleton and evaluate their efficacy for use in pediatric craniofacial surgery. Foreign body reaction would be evaluated. Inion baby plates and screws were tested in a rabbit model. Plates were applied to the frontal bone, over a bony defect of the parietal bone, to a nasal bone fracture, and inserted in the subcutaneous space over the occipital bone in thirty 6-week-old rabbits. Six rabbits were euthanized at 9, 12, 15, and 18 months' postoperative time point and examined for residual plates and screws. Bone from each surgical site was excised, fixed by immersion in 10% neutral-buffered formalin, decalcified in Immunocal solution, and examined by 7-microm paraffin sections stained with hematoxylin and eosin. At 9 months, the plates and screws had effectively biodegraded and no longer had holding power on the bones. Fragmentation of the implant material was noted. Residual implant material was still present on gross and histologic examination in rabbits at 9, 12, 15, and 18 months. Residue of a screw was still palpable in 1 rabbit at 18 months. There was no evidence of cyst formation in any of the examined specimens. Macrophages and giant cells were present in most of the specimens at 9, 12, 15, and 18 months. Findings from the current study revealed a relative short resorption time (9 mo) and normal inflammatory sequelae in an adult rabbit model. These findings suggest that these plates may be used safely in fixing the pediatric craniofacial skeleton. PMID:18520394

  13. Optical conductivity of semiconductor crystals with a screw dislocation

    NASA Astrophysics Data System (ADS)

    Taira, Hisao; Shima, Hiroyuki

    2014-01-01

    We study ac electronic transport in semiconductor crystals with a screw dislocation. The screw dislocation in the crystal results in an effective potential field that has a pronounced effect on the quantum mechanical electronic transport of the system. Alternating current conductivity at a frequency around 100 GHz has been calculated, showing upward shift in the peak position with increasing the Fermi energy. The result is in contrast to the persistency in the peak position observed in a dislocation-free crystal penetrated by magnetic flux, despite the apparent similarity between the two crystalline systems.

  14. Torsional stability of interference screws derived from bovine bone - a biomechanical study

    PubMed Central

    2010-01-01

    Background In the present biomechanical study, the torsional stability of different interference screws, made of bovine bone, was tested. Interference screws derived from bovine bone are a possible biological alternative to conventional metallic or bioabsorbable polymer interference screws. Methods In the first part of the study we compared the torsional stability of self-made 8 mm Interference screws (BC) and a commercial 8 mm interference screw (Tutofix®). Furthermore, we compared the torsional strength of BC screws with different diameters. For screwing in, a hexagon head and an octagon head were tested. Maximum breaking torques in polymethyl methacrylate resin were recorded by means of an electronic torque screw driver. In the second part of the study the tibial part of a bone-patellar tendon-bone graft was fixed in porcine test specimens using an 8 mm BC screw and the maximum insertion torques were recorded. Each interference screw type was tested 5 times. Results There was no statistically significant difference between the different 8 mm interference screws (p = 0.121). Pairwise comparisons did not reveal statistically significant differences, either. It was demonstrated for the BC screws, that a larger screw diameter significantly leads to higher torsional stability (p = 9.779 × 10-5). Pairwise comparisons showed a significantly lower torsional stability for the 7 mm BC screw than for the 8 mm BC screw (p = 0.0079) and the 9 mm BC screw (p = 0.0079). Statistically significant differences between the 8 mm and the 9 mm BC screw could not be found (p = 0.15). During screwing into the tibial graft channel of the porcine specimens, insertion torques between 0.5 Nm and 3.2 Nm were recorded. In one case the hexagon head of a BC screw broke off during the last turn. Conclusions The BC screws show comparable torsional stability to Tutofix® interference screws. As expected the torsional strength of the screws increases significantly with the diameter. The safety and in vivo performance of products derived from xenogeneic bone should be the focus of further investigations. PMID:20433761

  15. Effect of cement washout on loosening of abutment screws and vice versa in screw- and cement- retained implant-supported dental prosthesis

    PubMed Central

    Kim, Seok-Gyu; Son, Mee-Kyoung

    2015-01-01

    PURPOSE The purpose of this study was to examine the abutment screw stability of screw- and cement-retained implant-supported dental prosthesis (SCP) after simulated cement washout as well as the stability of SCP cements after complete loosening of abutment screws. MATERIALS AND METHODS Thirty-six titanium CAD/CAM-made implant prostheses were fabricated on two implants placed in the resin models. Each prosthesis is a two-unit SCP: one screw-retained and the other cemented. After evaluating the passive fit of each prosthesis, all implant prostheses were randomly divided into 3 groups: screwed and cemented SCP (Control), screwed and noncemented SCP (Group 1), unscrewed and cemented SCP (Group 2). Each prosthesis in Control and Group 1 was screwed and/or cemented, and the preloading reverse torque value (RTV) was evaluated. SCP in Group 2 was screwed and cemented, and then unscrewed (RTV=0) after the cement was set. After cyclic loading was applied, the postloading RTV was measured. RTV loss and decementation ratios were calculated for statistical analysis. RESULTS There was no significant difference in RTV loss ratio between Control and Group 1 (P=.16). No decemented prosthesis was found among Control and Group 2. CONCLUSION Within the limits of this in vitro study, the stabilities of SCP abutment screws and cement were not significantly changed after simulated cement washout or screw loosening. PMID:26140172

  16. Distal Humerus Fractures: Open Reduction Internal Fixation.

    PubMed

    Mighell, Mark A; Stephens, Brent; Stone, Geoffrey P; Cottrell, Benjamin J

    2015-11-01

    Distal humerus fractures are challenging injuries for the upper extremity surgeon. However, recent techniques in open reduction internal fixation have been powerful tools in getting positive outcomes. To get such results, the surgeon must be aware of how to properly use these techniques in their respective practices. The method of fixation depends on the fracture, taking the degree of comminution and the restoration of the columns and articular surface into account. This article helps surgeons understand the concepts behind open reduction internal fixation of the distal humerus and makes them aware of pitfalls that may lead to negative results. PMID:26498548

  17. Delayed massive hemorrhage due to external iliac artery pseudo-aneurysm and uretero-iliac artery fistula following robotic radical cystectomy and intracorporeal Studer pouch reconstruction: Endovascular management of an unusual complication

    PubMed Central

    Atmaca, Ali Fuat; Canda, Abdullah Erdem; Gumus, Mehmet; Asil, Erem; Balbay, Mevlana Derya

    2013-01-01

    We report a very unusual complication of uretero-iliac artery fistula that developed following robotic radical cystectomy (RARC), bilateral extended pelvic lymph node dissection and intracorporeal Studer pouch reconstruction. Our patient was a 54-year-old male who was admitted 1 month after undergoing robotic surgery due to intermittently occurring massive transurethral bleeding necessitating blood transfusion that stopped by itself. Angiography showed a right external iliac artery pseudo-aneurysm and a fistula tract between the pseudo-aneurysm and Wallace type ureteral anostomosis that was successfully treated by an angiographic endovascular stent insertion at this level. Uretero-iliac artery fistula might occur following RARC, bilateral extended pelvic lymph node dissection and intracorporeal Studer pouch reconstruction leading to intermittently massive transurethral bleeding. Angiography and stenting are important for diagnosis and successful treatment of this rare entity. PMID:24069106

  18. MECHANICS OF THE TAPER INTEGRATED SCREWED-IN (TIS) ABUTMENTS USED IN DENTAL IMPLANTS

    E-print Network

    Müftü, Sinan

    1 MECHANICS OF THE TAPER INTEGRATED SCREWED-IN (TIS) ABUTMENTS USED IN DENTAL IMPLANTS by Dinçer. Keywords: Dental implants; Taper lock; Morse taper; Conical interference fit; Tapered screw; Screw mechanics; Loosening torque, Tightening torque #12;3 INTRODUCTION A dental implant system serves

  19. Neural correlates of fixation duration in natural reading: Evidence from fixation-related fMRI.

    PubMed

    Henderson, John M; Choi, Wonil; Luke, Steven G; Desai, Rutvik H

    2015-10-01

    A key assumption of current theories of natural reading is that fixation duration reflects underlying attentional, language, and cognitive processes associated with text comprehension. The neurocognitive correlates of this relationship are currently unknown. To investigate this relationship, we compared neural activation associated with fixation duration in passage reading and a pseudo-reading control condition. The results showed that fixation duration was associated with activation in oculomotor and language areas during text reading. Fixation duration during pseudo-reading, on the other hand, showed greater involvement of frontal control regions, suggesting flexibility and task dependency of the eye movement network. Consistent with current models, these results provide support for the hypothesis that fixation duration in reading reflects attentional engagement and language processing. The results also demonstrate that fixation-related fMRI provides a method for investigating the neurocognitive bases of natural reading. PMID:26151101

  20. Percutaneous closure of pseudoaneurysm of common iliac artery with amplatzer duct occluder II.

    PubMed

    Vijayalakshmi, I B; Agrawal, Navin; Narasimhan, Chitra; Kavya, Mallikarjun; Bagi, Vitthal; Manjunath, C N

    2014-01-01

    Seven-year-old boy presented with pain in right lower limb and abdomen after a fall from a bullock cart. He was referred for management of pseudoaneurysm of the right common iliac artery. After CT angiogram, the vascular surgeon opined that child was not suitable for surgical patch or graft or endovascular stenting as there was no landing zone for the stent. Hence the child was treated with transcatheter closure with two Amplatzer duct occluder II (ADO II). On follow-up the symptoms and bruit disappeared. To the best of our knowledge this is the first case of pseudoaneurysm, treated with ADO II. PMID:23852803

  1. Successful Recanalization of a Longstanding Right Common Iliac Artery Occlusion with a Radiofrequency Guidewire

    SciTech Connect

    Tapping, C. R.; Uri, I. F.; Dixon, S.; Bratby, M. J.; Anthony, S.; Uberoi, R.

    2012-10-15

    We describe a case of successful recanalization of a longstanding right common iliac occlusion with a radiofrequency (RF) guidewire. The patient had been symptomatic with claudication for 3 years, and a preliminary attempt to cross the lesion using conventional techniques proved unsuccessful. Using low and medium intensity RF pulses and a PowerWire, a tract through the occlusion was established, which allowed subsequent stenting with an excellent angiographic result and a good immediate clinical response. We propose this as a useful technique in the peripheral arterial system for occlusive lesions not amenable to traditional recanalization techniques.

  2. Internal Iliac Artery Stenosis: Diagnosis and How to Manage it in 2015

    PubMed Central

    Mahé, Guillaume; Kaladji, Adrien; Le Faucheur, Alexis; Jaquinandi, Vincent

    2015-01-01

    Lower extremity arterial disease (LEAD) is a highly prevalent disease affecting 202 million people worldwide. Internal iliac artery stenosis (IIAS) is one of the localization of LEAD. This diagnosis is often neglected when a patient has a proximal walking pain since most physicians evoke a pseudoclaudication. Surprisingly, IIAS management is reported neither in the Trans-Atlantic Inter-Society Consensus II nor in the report of the American College Foundation/American Heart Association guidelines. The aims of this review are to present the current knowledge about the disease, how should it be managed in 2015 and what are the future research trends. PMID:26664904

  3. Internal Iliac Artery Stenosis: Diagnosis and How to Manage it in 2015.

    PubMed

    Mahé, Guillaume; Kaladji, Adrien; Le Faucheur, Alexis; Jaquinandi, Vincent

    2015-01-01

    Lower extremity arterial disease (LEAD) is a highly prevalent disease affecting 202 million people worldwide. Internal iliac artery stenosis (IIAS) is one of the localization of LEAD. This diagnosis is often neglected when a patient has a proximal walking pain since most physicians evoke a pseudoclaudication. Surprisingly, IIAS management is reported neither in the Trans-Atlantic Inter-Society Consensus II nor in the report of the American College Foundation/American Heart Association guidelines. The aims of this review are to present the current knowledge about the disease, how should it be managed in 2015 and what are the future research trends. PMID:26664904

  4. Percutaneous Transosseous Embolization of Internal Iliac Artery Aneurysm Type II Endoleak: Report of Two Cases

    SciTech Connect

    Gemmete, Joseph J. Arabi, Mohammad; Cwikiel, Wojciech B.

    2011-02-15

    This report describes two cases of successful treatment of an internal iliac artery aneurysm (IIAA) type II endoleak utilizing a percutaneous transosseous access that could not be treated using an endovascular or standard percutaneous approach. A direct percutaneous approach through bone was chosen to avoid vital structures and the surrounding bowel. The procedure was successful and required minimal fluoroscopy time compared with other treatment options. We believe this procedure is an alternative to some of the more complex and technically challenging means of treating this lesion.

  5. Graft necrosis occurred after iliac crest reconstruction after mandibular segmental resection of ameloblastoma.

    PubMed

    Bulut, Emel; Bekçio?lu, Burak; Ba?, Burcu; Özden, Bora; Çelebi, Nükhet; Çelenk, Peruze; Külünk, ?afak

    2013-03-01

    Ameloblastoma is an uncommon benign odontogenic neoplasm of the maxillofacial region constituting less than 1% of tumors of the oral cavity. Ameloblastomas have been categorized broadly into 3 biologic variants: cystic (unicystic), solid, and peripheral. Unicystic ameloblastoma is a rare and less aggressive variant of ameloblastoma. The aim of this report is to describe a case of cystic ameloblastoma treated with segmental resection and iliac graft reconstruction. The possible reasons of graft failure seen in our patient at the early stage of the healing were also discussed. PMID:23524824

  6. Deep Circumflex Iliac Artery-Related Hemoperitoneum Formation After Surgical Drain Placement: Successful Transcatheter Embolization

    SciTech Connect

    Park, Sang Woo; Chang, Seong-Hwan Yun, Ik Jin; Lee, Hae Won

    2010-04-15

    A 53-year-old woman with liver cirrhosis and hepatocellular carcinoma underwent living donor liver transplantation. After transplantation, her hemoglobin and hematocrit levels decreased to 6.3 g/dl and 18.5%, respectively, during the course of 3 days. A contrast-enhanced abdominal computed axial tomography (CAT) scan showed a hemoperitoneum in the right perihepatic space with no evidence of abdominal wall hematoma or pseudoaneurysm formation. An angiogram of the deep circumflex iliac artery (DCIA) showed extravasation of contrast media along the surgical drain, which had been inserted during the transplantation procedure. Transcatheter embolization of the branches of the DCIA was successfully performed using N-butyl cyanoacrylate.

  7. Sudden cardiac arrest immediately after stent graft deployment during treatment of iliac aneurysm with iliocaval fistula.

    PubMed

    Akamatsu, Daijirou; Sato, Akira; Goto, Hitoshi; Ohta, Hideki; Hashimoto, Munetaka; Shimizu, Takuya; Tsuchida, Ken; Ohuchi, Noriaki

    2014-05-01

    An 84-year-old woman with heaviness of the right lower extremity had an iliocaval fistula related to a right internal iliac aneurysm. Immediately after deployment of an endovascular device, cardiac arrest occurred because of severely decreased sympathetic activity. After surgery, the patient recovered well and has been followed up with exclusion of the arteriovenous fistula and resolution of the type II endoleak. Endovascular treatment for large arteriovenous fistulas induces rapid closure of the fistula together with restoration of blood supply to the lower extremity. Markedly deactivated sympathetic nerve traffic could result in a critical hemodynamic status in association with endograft deployment. PMID:24184464

  8. Cellulose and the twofold screw axis: Modeling and experimental arguments

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Crystallography indicates that molecules in crystalline cellulose either have 2-fold screw-axis (21) symmetry or closely approximate it, leading to short distances between H4 and H1' across the glycosidic linkage. Therefore, modeling studies of cellobiose often show elevated energies for 21 structur...

  9. INTERIOR VIEW OF JAMES HARRIS CUTTING SCREW THREADS INTO THE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    INTERIOR VIEW OF JAMES HARRIS CUTTING SCREW THREADS INTO THE INTERIOR OF FITTINGS ON ONE IN A BANK OF TAPPING MACHINES, EACH OPERATED BY THE SAME WORKER SIMULTANEOUSLY BUT TIMED TO REQUIRE WORKER ACTION AT INTERVALS THAT DO NOT INTERFERE WITH THE OTHER MACHINES. - Stockham Pipe & Fittings Company, Tapping Room, 4000 Tenth Avenue North, Birmingham, Jefferson County, AL

  10. Granulation of increasingly hydrophobic formulations using a twin screw granulator.

    PubMed

    Yu, Shen; Reynolds, Gavin K; Huang, Zhenyu; de Matas, Marcel; Salman, Agba D

    2014-11-20

    The application of twin screw granulation in the pharmaceutical industry has generated increasing interest due to its suitability for continuous processing. However, an understanding of the impact of formulation properties such as hydrophobicity on intermediate and finished product quality has not yet been established. Hence, the current work investigated the granulation behaviour of three formulations containing increasing amounts of hydrophobic components using a Consigma™-1 twin screw granulator. Process conditions including powder feed rate, liquid to solid ratio, granulation liquid composition and screw configuration were also evaluated. The size of the wet granules was measured in order to enable exploration of granulation behaviour in isolation without confounding effects from downstream processes such as drying. The experimental observations indicated that the granulation process was not sensitive to the powder feed rate. The hydrophobicity led to heterogeneous liquid distribution and hence a relatively large proportion of un-wetted particles. Increasing numbers of kneading elements led to high shear and prolonged residence time, which acted to enhance the distribution of liquid and feeding materials. The bimodal size distributions considered to be characteristic of twin screw granulation were primarily ascribed to the breakage of relatively large granules by the kneading elements. PMID:25124058

  11. ORIGINAL PAPER Twin-Screw Extrusion Processing of Distillers Dried

    E-print Network

    ORIGINAL PAPER Twin-Screw Extrusion Processing of Distillers Dried Grains with Solubles (DDGS)-Based Yellow Perch (Perca flavescens) Feeds Ferouz Y. Ayadi & Kurt A. Rosentrater & Kasiviswanathan with limited availabilities of fish meal for fish feed, has created the need for alternative protein sources

  12. Screw dislocation in zirconium: An ab initio study

    NASA Astrophysics Data System (ADS)

    Clouet, Emmanuel

    2012-10-01

    Plasticity in zirconium is controlled by 1/3<12¯10> screw dislocations gliding in the prism planes of the hexagonal close-packed structure. This prismatic and not basal glide is observed for a given set of transition metals like zirconium and is known to be related to the number of valence electrons in the d band. We use ab initio calculations based on the density functional theory to study the core structure of screw dislocations in zirconium. Dislocations are found to dissociate in the prism plane in two partial dislocations, each with a pure screw character. Ab initio calculations also show that the dissociation in the basal plane is unstable. We calculate then the Peierls barrier for a screw dislocation gliding in the prism plane and obtain a small barrier. The Peierls stress deduced from this barrier is lower than 21 MPa, which is in agreement with experimental data. The ability of an empirical potential relying on the embedded atom method (EAM) to model dislocations in zirconium is also tested against these ab initio calculations.

  13. 21 CFR 888.3070 - Pedicle screw spinal system.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... immobilization and stabilization of spinal segments in skeletally mature patients as an adjunct to fusion in the...; spinal tumor; and failed previous fusion (pseudarthrosis). These pedicle screw spinal systems must comply... with significant mechanical instability or deformity requiring fusion with instrumentation....

  14. 21 CFR 888.3070 - Pedicle screw spinal system.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... immobilization and stabilization of spinal segments in skeletally mature patients as an adjunct to fusion in the...; spinal tumor; and failed previous fusion (pseudarthrosis). These pedicle screw spinal systems must comply... with significant mechanical instability or deformity requiring fusion with instrumentation....

  15. 21 CFR 888.3070 - Pedicle screw spinal system.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... immobilization and stabilization of spinal segments in skeletally mature patients as an adjunct to fusion in the...; spinal tumor; and failed previous fusion (pseudarthrosis). These pedicle screw spinal systems must comply... with significant mechanical instability or deformity requiring fusion with instrumentation....

  16. 21 CFR 888.3070 - Pedicle screw spinal system.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... immobilization and stabilization of spinal segments in skeletally mature patients as an adjunct to fusion in the...; spinal tumor; and failed previous fusion (pseudarthrosis). These pedicle screw spinal systems must comply... with significant mechanical instability or deformity requiring fusion with instrumentation....

  17. 21 CFR 888.3070 - Pedicle screw spinal system.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... immobilization and stabilization of spinal segments in skeletally mature patients as an adjunct to fusion in the...; spinal tumor; and failed previous fusion (pseudarthrosis). These pedicle screw spinal systems must comply... with significant mechanical instability or deformity requiring fusion with instrumentation....

  18. Stability of two-fold screw axis structures for cellulose

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Diffraction crystallography indicates that most forms of crystalline cellulose have two-fold screw axis symmetry. Even if exact symmetry is absent, the degree of pseudo symmetry is very high. On the other hand, this symmetry leads to short contacts between H4 and H1' across the glycosidic linkage....

  19. Mechanistic models of oceanic nitrogen fixation

    E-print Network

    Monteiro, Fanny

    2009-01-01

    Oceanic nitrogen fixation and biogeochemical interactions between the nitrogen, phosphorus and iron cycles have important implications for the control of primary production and carbon storage in the ocean. The biological ...

  20. ORIGINAL ARTICLE Sulfur oxidizers dominate carbon fixation

    E-print Network

    Hansell, Dennis

    ORIGINAL ARTICLE Sulfur oxidizers dominate carbon fixation at a biogeochemical hot spot in the dark clade of marine gamma-proteobacterial sulfur oxidizers (GSOs) are distributed throughout proteins for sulfur oxidation (adenosine phosphosulfate reductase, sox (sulfur oxidizing system

  1. A simple and inexpensive external fixator.

    PubMed

    Noor, M A

    1988-11-01

    A simple and inexpensive external fixator has been designed. It is constructed of galvanized iron pipe and mild steel bolts and nuts. It can easily be manufactured in a hospital workshop with a minimum of tools. PMID:3267638

  2. An examination of fixation in brainstorming 

    E-print Network

    Kohn, Nicholas William

    2009-05-15

    Shortcomings....................................................... 5 ttempts to Eliminate Brainstorming Deficits...............................16 Use of Stimuli and Analogies When Problem Solving.................. 21 Fixation in Individual Problem Solving... in Brainstorming.......................................... Productivity Deficit........................................109 Temporal Findings......................................... 110 Incubation Effects..........................................111...

  3. Methanotrophy Induces Nitrogen Fixation in Boreal Mosses

    NASA Astrophysics Data System (ADS)

    Tiirola, M. A.

    2014-12-01

    Many methanotrophic bacterial groups fix nitrogen in laboratory conditions. Furthermore, nitrogen (N) is a limiting nutrient in many environments where methane concentrations are highest. Despite these facts, methane-induced N fixation has previously been overlooked, possibly due to methodological problems. To study the possible link between methanotrophy and diazotrophy in terrestrial and aquatic habitats, we measured the co-occurrence of these two processes in boreal forest, peatland and stream mosses using a stable isotope labeling approach (15 N2 and 13 CH4 double labeling) and sequencing of the nifH gene marker. N fixation associated with forest mosses was dependent on the annual N deposition, whereas methane stimulate N fixation neither in high (>3 kg N ha -1 yr -1) nor low deposition areas, which was in accordance with the nifH gene sequencing showing that forest mosses (Pleurozium schreberi and Hylocomium splendens ) carried mainly cyanobacterial N fixers. On the other extreme, in stream mosses (Fontinalis sp.) methane was actively oxidized throughout the year, whereas N fixation showed seasonal fluctuation. The co-occurrence of the two processes in single cell level was proven by co-localizing both N and methane-carbon fixation with the secondary ion mass spectrometry (SIMS) approach. Methanotrophy and diazotrophy was also studied in peatlands of different primary successional stages in the land-uplift coast of Bothnian Bay, in the Siikajoki chronosequence, where N accumulation rates in peat profiles indicate significant N fixation. Based on experimental evidence it was counted that methane-induced N fixation explained over one-third of the new N input in the younger peatland successional stages, where the highest N fixation rates and highest methane oxidation activities co-occurred in the water-submerged Sphagnum moss vegetation. The linkage between methanotrophic carbon cycling and N fixation may therefore constitute an important mechanism in the rapid accumulation of N during the primary succession of peatlands. It is still an open issue whether methanotrophy induces N fixation directly or by enhancing phototrophic or heterotrophic N fixation.

  4. Fixational eye movements predict visual sensitivity.

    PubMed

    Scholes, Chris; McGraw, Paul V; Nyström, Marcus; Roach, Neil W

    2015-10-22

    During steady fixation, observers make small fixational saccades at a rate of around 1-2 per second. Presentation of a visual stimulus triggers a biphasic modulation in fixational saccade rate-an initial inhibition followed by a period of elevated rate and a subsequent return to baseline. Here we show that, during passive viewing, this rate signature is highly sensitive to small changes in stimulus contrast. By training a linear support vector machine to classify trials in which a stimulus is either present or absent, we directly compared the contrast sensitivity of fixational eye movements with individuals' psychophysical judgements. Classification accuracy closely matched psychophysical performance, and predicted individuals' threshold estimates with less bias and overall error than those obtained using specific features of the signature. Performance of the classifier was robust to changes in the training set (novel subjects and/or contrasts) and good prediction accuracy was obtained with a practicable number of trials. Our results indicate a tight coupling between the sensitivity of visual perceptual judgements and fixational eye control mechanisms. This raises the possibility that fixational saccades could provide a novel and objective means of estimating visual contrast sensitivity without the need for observers to make any explicit judgement. PMID:26468244

  5. Covering the Screw-Access Holes of Implant Restorations in the Esthetic Zone: A Clinical Report

    PubMed Central

    Saboury, Abolfazl; Gooya, Ali

    2014-01-01

    Screw-retained implant restorations have an advantage of predictable retention as well as retrievability, and obviate the risk of excessive sub-gingival cement commonly associated with cement retained implant restorations. Screw-retained restorations generally have screw access holes, which can compromise esthetics and weaken the porcelain around the holes. The purpose of this study is to describe the use of a separate overcasting crown design to cover the screw access hole of implant screw-retained prosthesis for improved esthetics. PMID:25628703

  6. Spontaneous ruptured dissection of the right common iliac artery in a patient with classic Ehlers-Danlos syndrome phenotype.

    PubMed

    Gaines, Rick; Tinkle, Brad T; Halandras, Pegge M; Al-Nouri, Omar; Crisostomo, Paul; Cho, Jae S

    2015-04-01

    Unlike vascular Ehlers-Danlos syndrome (EDS), classic EDS is rarely associated with vascular manifestation. We report the case of a 39-year-old man who presented with acute abdominal pain. At the time of presentation, the patient was in hypovolemic shock, and computed tomography angiogram demonstrated common iliac artery dissection with rupture. He underwent an attempted endovascular repair that was converted to an open repair of a ruptured right common iliac artery dissection. Subsequent genetic testing revealed a substitution of arginine for cysteine in type I collagen, COL1A1 exon 14 c.934C>T mutation, consistent with a rare variant of classic EDS. PMID:25597651

  7. The general theory of blade screws including propellers, fans, helicopter screws, helicoidal pumps, turbo-motors, and different kinds of helicoidal blades

    NASA Technical Reports Server (NTRS)

    De Bothezat, George

    1920-01-01

    Report presents a theory which gives a complete picture and an exact quantitative analysis of the whole phenomenon of the working of blade screws, but also unites in a continuous whole the entire scale of states of work conceivable for a blade screw. Chapter 1 is devoted to the establishment of the system of fundamental equations relating to the blade screw. Chapter 2 contains the general discussion of the 16 states of work which may establish themselves for a blade screw. The existence of the vortex ring state and the whirling phenomenon are established. All the fundamental functions which enter the blade-screw theory are submitted to a general analytical discussion. The general outline of the curve of the specific function is examined. Two limited cases of the work of the screw, the screw with a zero constructive pitch and the screw with an infinite constructive pitch, are pointed out. Chapter 3 is devoted to the study of the propulsive screw or propeller. (author)

  8. Arthroscopic Reduction and Internal Fixation for Fracture of the Lateral Process of the Talus

    PubMed Central

    Funasaki, Hiroki; Hayashi, Hiroteru; Sugiyama, Hajime; Marumo, Keishi

    2015-01-01

    Fractures of the lateral process of the talus (LPT) are relatively rare. We describe arthroscopic reduction and internal fixation for a type I fracture of the LPT according to the Hawkins classification. Preoperative computed tomography is necessary to evaluate the type and displacement of the LPT fracture because this type of fracture is often overlooked on a plain radiograph. The ankle is approached through a standard medial portal as the working portal and an anterolateral portal as the viewing portal. A 2.7-mm-diameter 30° arthroscope is used. Hematoma and soft tissues around the talus are cleared with a motorized shaver, and the anterior and lateral aspects of the talar process are visualized. Fracture reduction is obtained by pushing the lateral fragment of the lateral process medially and is fixed temporally with a 1.1-mm guidewire from the medial portal under both arthroscopy and fluoroscopy. A headless compression screw is inserted through the guidewire. Arthroscopic reduction and internal fixation for a type I LPT fracture can be easily accomplished, and return to daily and sports activities can be achieved in a relatively short time. PMID:25973380

  9. Analysis of Mandibular Test Specimens Used to Assess a Bone Fixation System.

    PubMed

    Baccarin, Leandro Stocco; Casarin, Renato Correa Viana; Lopes-da-Silva, Jorge Vicente; Passeri, Luis Augusto

    2015-09-01

    The aim of this study was to assess through biomechanical testing if different synthetic materials used to fabricate test specimens have a different biomechanical behavior in comparison with other materials when simulating in vitro load resistance of a fixation method established for sagittal split ramus osteotomy (SSRO). Thirty synthetic and standardized human hemimandible replicas with SSRO were divided into three groups of 10 samples each. Group A-ABS plastic; Group B-polyamide; and Group C-polyurethane. These were fixated with three bicortical position screws (16?mm in length, 2.0-mm system) in an inverted l pattern using perforation guide and 5-mm advancement. Each sample was submitted to linear vertical load, and load strength values were recorded at 1, 3, 5, 7, and 10?mm of displacement. The means and standard deviation were compared using the analysis of variance (p?

  10. Cost of external fixation vs external fixation then nailing in bone infection

    PubMed Central

    Emara, Khaled Mohamed; Diab, Ramy Ahmed; Ghafar, Khaled Abd EL

    2015-01-01

    AIM: To study the cost benefit of external fixation vs external fixation then nailing in treatment of bone infection by segment transfer. METHODS: Out of 71 patients with infected nonunion tibia treated between 2003 and 2006, 50 patients fitted the inclusion criteria (26 patients were treated by external fixation only, and 24 patients were treated by external fixation early removal after segment transfer and replacement by internal fixation). Cost of inpatient treatment, total cost of inpatient and outpatient treatment till full healing, and the weeks of absence from school or work were calculated and compared between both groups. RESULTS: The cost of hospital stay and surgery in the group of external fixation only was 22.6 ± 3.3 while the cost of hospital stay and surgery in the group of early external fixation removal and replacement by intramedullary nail was 26.0 ± 3.2. The difference was statistically significant regarding the cost of hospital stay and surgery in favor of the group of external fixation only. The total cost of medical care (surgery, hospital stay, treatment outside the hospital including medications, dressing, physical therapy, outpatient laboratory work, etc.) in group of external fixation only was 63.3 ± 15.1, and total absence from work was 38.6 ± 6.6 wk. While the group of early removal of external fixation and replacement by IM nail, total cost of medical care was 38.3 ± 6.4 and total absence from work or school was 22.7 ± 4.1. The difference was statistically significant regarding the total cost and absence from work in favor of the group of early removal and replacement by IM nail. CONCLUSION: Early removal of external fixation and replacement by intramedullary nail in treatment of infected nonunion showed more cost effectiveness. Orthopaedic society needs to show the cost effectiveness of different procedures to the community, insurance, and health authorities. PMID:25621219

  11. Percutaneous Treatment of Iliac Aneurysms and Pseudoaneurysms with Cragg Endopro System 1 Stent-Grafts

    SciTech Connect

    Gasparini, Daniele; Lovaria, Andrea; Saccheri, Silvia; Nicolini, Antonio; Favini, Giorgio; Inglese, Luigi; Giorgetti, Pier Luigi; Basadonna, Pier Tommaso

    1997-09-15

    Purpose: To evaluate the feasibility and short-term follow-up results of treating iliac aneurysms by the Cragg Endopro System 1 stent-graft. Methods: Nine lesions (two pseudoaneurysms and seven atherosclerotic aneurysms) were treated in eight patients by percutaneous implantation of a total of 10 stent-grafts. The procedure was followed by anticoagulation with heparin for 6 days, then antiplatelet therapy. Follow-up was by color Doppler ultrasound scan at 2 days and 3 months after the procedure for all patients, and by venous digital subtraction angiography and/or angio-CT up to 12 months later for four patients. Results: Initial clinical success rate was 100% and there were two minor complications. In one case the delivery system was faulty resulting in failure to deploy the stent-graft. An additional device had to be used. At 3-12 months all prostheses were patent but one patient (12.5%) had a minimal pergraft leak. Conclusion: Percutaneous stent-grafting with this device is a safe and efficacious treatment of iliac artery aneurysms.

  12. Endovascular Therapy for Fibromuscular Dysplasia of the Bilateral External Iliac Arteries Visualized with Optical Coherence Tomography

    PubMed Central

    Niizeki, Takeshi; Ishino, Mitsunori; Kitahara, Tatsuro; Yamauchi, So; Ikeno, Eiichiro; Kubota, Isao

    2015-01-01

    Patient: Female, 60 Final Diagnosis: Fibromuscular dysplasia of the bilateral external iliac arteries Symptoms: Intermittent claudication of the bilateral legs Medication: — Clinical Procedure: Endovascular therapy Specialty: Cardiology Objective: Rare disease Background: Fibromuscular dysplasia (FMD) is a non-inflammatory, non-atherosclerotic, degenerative vascular disease that most frequently affects renal and carotid arteries in women aged 30–50 years, and rarely complicating arteries of the lower limbs. Case Report: A 60-year-old woman was admitted with intermittent claudication of both legs. We performed pelvic and bilateral lower-extremities angiography, which revealed that the bilateral external iliac arteries (EIAs) had the ‘string of beads’ appearance with a diagnosis of FMD. Endovascular therapy (EVT) was performed for the bilateral EIAs. Optical coherence tomography (OCT) images showed thickening and thinning of the middle layer, while three-dimensional OCT images showed a ‘haustra coli’-like appearance. After successful balloon angioplasty, claudication completely disappeared. Conclusions: We report a rare case of EVT successfully performed for FMD of the bilateral EIAs. Our findings suggest that OCT may provide unique diagnostic clues in FMD patients. PMID:25819398

  13. Single and Tandem Stents in Sheep Iliac Arteries: Is There a Difference in Patency?

    SciTech Connect

    Schuermann, Karl; Vorwerk, Dierk; Buecker, Arno; Grosskortenhaus, Stefanie; Guenther, Rolf W.

    1998-09-15

    Purpose: To compare patency and neointima formation of single and tandem arterial stents. Methods: In each of six sheep, two Memotherm nitinol stents (tandem stents) were inserted into the external iliac artery on one side and a single stent into the artery on the opposite side. The size of the iliac lumen was assessed in the proximal, middle, and distal segments of the stents by intravascular ultrasound (IVUS) before, immediately after, and 1 month after implantation when the sheep were killed. Neointimal thickness was determined in the proximal, middle, and distal segments of each stent by light microscopy. Results: All stents remained patent. There was no significant difference in lumen and neointimal thickness between single and tandem stents. Cranial tandem stents showed a significantly wider lumen and smaller neointimal thickness than caudal tandem stents. In the proximal and distal segments, the lumen of the stents was significantly smaller and the neointimal thickness greater than in the middle segment; differences in neointimal thickness were significant only between the proximal and the middle segment. Conclusion: In an experimental setting, tandem stents did not interfere with one another with regard to patency and neointima formation when compared with a single contralateral stent. Neointimal thickening after stent insertion seems to be inversely related to the original arterial diameter.

  14. [Puerperal sepsis in the 19th century and Trendlenburg's ligature of the internal iliacal vein].

    PubMed

    Hach, W

    2007-05-01

    With the establishment of institutions for child delivery in city hospitals and with incorporation of routine autopsy into the field of activity of assistants at birth, childbed fever spread epidemically and was fatal in most cases. Nearly every third woman in childbed died of puerperal sepsis in the Hôtel Dieu in Paris and in the Erste Wiener Gebärklinik in Vienna. The tragic fate of obstetrician Ignaz Semmelweis began here, he recognized disease transmission from pus and body parts by physicians during the process of delivery. At the end of the 19(th) century puerperal sepsis occurred less frequently, its course was nevertheless equally dramatic. Pathophysiologically a septic thrombophlebitis of the ovarian vein was seen as the primary cause of the pyaemia. Yet, the ligature of the vessel did not alter the deadly course of the disease. Based on sections Trendlenburg realized that the internal iliacal vein plays a much greater role in protracted pyaemia. Thereupon he performed a ligature of this vessel. The long course of a complicated infection took a good turn with this operation. Trendlenburg's ligature and resection of the ovarian and internal iliacal vein were usually combined with hysterectomy. In the following decades this great operation of seriously ill women in childbed found agreement as well as rejection. Most interventions did not save the lives of the patients. Before antibiotic therapy was introduced, physicians were almost helpless against puerperal pyaemia. PMID:17479174

  15. One Year Experience of Iliac Bifurcated Device for Aortoiliac Aneurysm in a Korean Single Center

    PubMed Central

    Kim, Moon Hwan; Park, Keun-Myoung; Jeon, Yong Sun; Cho, Soon Gu; Hong, Kee Chun; Shin, Woo Young; Choe, Yun-Mee; Shin, Seok-Hwan; Kim, Kyung Rae

    2015-01-01

    One of the predominant methods for preserving the internal iliac artery (IIA) in aortoiliac aneurysms is to use an iliac bifurcated device (IBD). However, there are a few limitations to the use of IBD in Korea. Our study aims to present the technical aspects of these devices, and to provide a mid-term analysis of IBD. Since 2013, 4 IBDs were used in 4 patients, with a mean follow-up of 14 months (range, 6–22 months). A 100% technical success rate was achieved without mortality and morbidity in our cases. The mean procedural time was 176 min (range, 145–240 min), and the mean contrast dose used was 184 mL (range, 135–220 mL). Type I or III endoleaks and postoperative expansion of the aneurysms weren't observed. Our cases demonstrates that IBD is a relatively safe repair method of aortoiliac aneurysms with preservation of the IIAs. However, a longer follow-up is needed to review the midterm results. PMID:26719840

  16. Assessment of a Polyester-Covered Nitinol Stent in the Canine Aorta and Iliac Arteries

    SciTech Connect

    Castaneda, Flavio; Ball-Kell, Susan M.; Young, Kate; Li Ruizong

    2000-09-15

    Purpose: To evaluate the patency and healing characteristics of a woven polyester fabric-covered stent in the canine model.Methods: Twenty-four self-expanding covered stents were placed in the infrarenal aorta and bilateral common iliac arteries of eight dogs and evaluated at 1 (n = 2), 3 (n = 2), and 6 (n = 4) months. Stent assessment was done using angiography prior to euthanasia, and light and scanning electron microscopy.Results: Angiographically, just prior to euthanasia, 8 of 8 aortic and 14 of 16 iliac endovascular covered stents were patent. Histologically, the stented regions showed complete endothelialization 6 months after graft implantation. A neointima had formed inside the stented vessel regions resulting in complete encasement of the fabric-covered stent by 3 months after graft implantation. Medial compression with smooth muscle cell atrophy was present in all stented regions. Explanted stent wires, examined by scanning electron microscopy, showed pitting but no cracks or breakage.Conclusion: The covered stent demonstrated predictable healing and is effective in preventing stenosis in vessels 10.0 mm or greater in diameter but does not completely preclude stenosis in vessels 6.0 mm or less in diameter.

  17. Gout in the spine and sacri-iliac joints: radiological manifestations

    SciTech Connect

    Jajic, I.

    1982-06-01

    It is well known that deposits of urates in soft tissues occur commonly in gout, particularly in para-articular areas and in articular cartilages of the limbs. Involvement of the spine and sacro-iliac joints by such deposits, however, has been regarded as being relatively unusual and has attracted little attention in the literature. As we were impressed by the frequency of episodes of acute back pain in our patients with gouty arthritis, established definitely on clinical and biochemical grounds, we undertook a radiological investigation of the spine and sacro-iliac joints in a series of 54 subjects. It was suspected that their episodes of pain were clinical manifestations of gout, and 12 of the group had suffered one or more attacks. Of these 12 subjects, eight were found to have radiological abnormalities. In six subjects, evidence of sacro-iliitis was demonstrated, which is comparable to the report of Resnick and Reinke (8), and in two patients vertebral lesions corresponded to those described by Jaffe (5). Hyperostotic spondylosis was present in no fewer than 29 of the series. Although lacking histological confirmation of the lesions demonstrated radiologically, we believe that our suspicions have been confirmed.

  18. Bifurcated Endograft (Excluder) in the Treatment of Isolated Iliac Artery Aneurysm: Preliminary Report

    SciTech Connect

    Zander, Tobias Baldi, Sebastian; Rabellino, Martin; Kirsch, David; Llorens, Rafael; Zerolo, Ignacio; Qian, Zhong; Maynar, Manuel

    2009-09-15

    The aim of this study was to evaluate the effectiveness of endovascular repair in the treatment of isolated iliac artery aneurysm (IAA) using Excluder bifurcated endograft. Eight consecutive patients with IAA were treated during a period of 45 months using Excluder bifurcated endograft. Two patients presented with isolated IAA rupture and were treated emergently, whereas the other six patients underwent elective treatment. All aneurysms lacked sufficient proximal necks and therefore were not suitable for tubular-shaped endograft. Follow-up imaging was performed at 1 week, at every 3 months during the first year, semiannually until 2 years, and annually afterward using angio-computed axial tomography and plain films. Technical success was achieved in all patients. No mortality was seen despite two patients having IAA rupture. Follow-up (12 to 60 months) was done in all but one patient. During this period, complications were observed in three patients. One patient developed sexual impotence at 3-month follow up; one patient presented unilateral gluteal claudication after the procedure, which resolved at 3 months; and one patient developed a graft porosity-related endoleak, which was successfully managed with placement of an additional ipsilateral iliac extension. Endovascular treatment of isolated IAA using bifurcated endograft is safe and can be an alternative to surgical treatment. The benefits from decreased morbidity and mortality of endoluminal treatment of isolated IAA using bifurcated endograft outweigh the minor complications associated with this technique, which are mostly related to occlusion of hypogastric arteries.

  19. System for Image-Processing-Based Inspection of a Screw Hole on a Molded Plastic Frame

    NASA Astrophysics Data System (ADS)

    Satoh, Hironobu; Takeda, Fumiaki

    A screw hole is incorrectly molded if the pin on the mold is broken when the plastic is molded by injection molding. Sampling inspection is carried out manually to identify the incorrectly molded screw hole. In the sampling inspection, the incorrectly molded screw hole on the molded plastic frame is rarely overlooked. Therefore, the development of a system for the high-precision identification of the incorrectly molded screw hole is required. The purpose of this study is to develop a screw-hole inspection system that distinguishes between a correctly molded screw hole and an incorrectly molded one. In this paper, a screw-hole inspection system is proposed. There is a need to capture clearly the screw hole on an uneven plastic frame and therefore, a multi-camera system is used. The proposed system consists of several Web cameras with the individual adjustable focus. Moreover, the inspection of the screw holes is performed using an inspection algorithm that is developed for a multi-camera system. When 2548 correctly molded screw holes and 2940 incorrectly molded screw holes were inspected by the proposed system, the inspection success rate was 100.0%. Finally, we have verified its effectiveness by performing an experiment.

  20. A custom-made sealing screw cap for a closed, hollow obturator.

    PubMed

    Nishigawa, Goro; Maruo, Yukinori; Jin, Keiji; Oki, Kazuhiro; Minagi, Shogo

    2007-09-01

    This paper describes a closed, hollow obturator with a nondetachable screw cap to seal the access hole that also allows cleaning of the inside of the bulb. A small screw cap was fabricated from a cobalt-chromium alloy. This screw was screwed to the access hole prepared at the top of the hollow obturator and when removed allows the inside of the obturator to be cleaned through the access hole. At the end of the screw, a preformed cobalt-chromium wire was attached that works as the safety retention mechanism of the screw. This ensures the screw in not aspirated or swallowed if it becomes unscrewed and falls from the prosthesis during wear in the patient's mouth. This device enables the patient to clean the inside of the closed obturator at home. PMID:17912099

  1. Comminuted olecranon fracture fixation with pre-contoured plate: Comparison of composite and cadaver bones

    PubMed Central

    Hamilton Jr, David A; Reilly, Danielle; Wipf, Felix; Kamineni, Srinath

    2015-01-01

    AIM: To determine whether use of a precontoured olecranon plate provides adequate fixation to withstand supraphysiologic force in a comminuted olecranon fracture model. METHODS: Five samples of fourth generation composite bones and five samples of fresh frozen human cadaveric left ulnae were utilized for this study. The cadaveric specimens underwent dual-energy X-ray absorptiometry (DEXA) scanning to quantify the bone quality. The composite and cadaveric bones were prepared by creating a comminuted olecranon fracture and fixed with a pre-contoured olecranon plate with locking screws. Construct stiffness and failure load were measured by subjecting specimens to cantilever bending moments until failure. Fracture site motion was measured with differential variable resistance transducer spanning the fracture. Statistical analysis was performed with two-tailed Mann-Whitney-U test with Monte Carlo Exact test. RESULTS: There was a significant difference in fixation stiffness and strength between the composite bones and human cadaver bones. Failure modes differed in cadaveric and composite specimens. The load to failure for the composite bones (n = 5) and human cadaver bones (n = 5) specimens were 10.67 nm (range 9.40-11.91 nm) and 13.05 nm (range 12.59-15.38 nm) respectively. This difference was statistically significant (P ? 0.007, 97% power). Median stiffness for composite bones and human cadaver bones specimens were 5.69 nm/mm (range 4.69-6.80 nm/mm) and 7.55 nm/mm (range 6.31-7.72 nm/mm). There was a significant difference for stiffness (P ? 0.033, 79% power) between composite bones and cadaveric bones. No correlation was found between the DEXA results and stiffness. All cadaveric specimens withstood the physiologic load anticipated postoperatively. Catastrophic failure occurred in all composite specimens. All failures resulted from composite bone failure at the distal screw site and not hardware failure. There were no catastrophic fracture failures in the cadaveric specimens. Failure of 4/5 cadaveric specimens was defined when a fracture gap of 2 mm was observed, but 1/5 cadaveric specimens failed due to a failure of the triceps mechanism. All failures occurred at forces greater than that expected in postoperative period prior to healing. CONCLUSION: The pre-contoured olecranon plate provides adequate fixation to withstand physiologic force in a composite bone and cadaveric comminuted olecranon fracture model. PMID:26495247

  2. Image-guided percutaneous internal fixation of sacral fracture.

    PubMed

    Kinon, Merritt D; Desai, Rupen; Loriaux, Daniel; Houten, John K

    2016-01-01

    Percutaneous iliosacral screw placement is a technically challenging procedure with a significant complication profile for misplaced screws. The use of stereotactic image guidance has been shown to provide superior accuracy in the placement of spinal instrumentation. Here, the authors describe a novel application of O-arm technology (Medtronic Sofamor Danek, Memphis, TN, USA) to help safely place iliosacral screws for the treatment of a traumatic sacral fracture. PMID:26433323

  3. [Visual fixation features after treatment of exudative age macular degeneration].

    PubMed

    Surguch, V K; Surnina, Z V; Sizova, M V

    2011-01-01

    Changes of visual fixation in patients with choroidal neovascularitation (CNV) associated with age macular degeneration (AMD) after bevacizumab are studied. 45 patients (45 eyes) with active CNV treated with intravitreal bevacizumab were enrolled into the study. Visual fixation was studied before and 3-6 months after treatment using original method that included fundus foto and fluorescein angiography. Fixation relative to fovea and lesion was evaluated. Foveal fixation beyond lesion was found in 9%, foveal fixation within lesion--in 47%, extrafoveal fixation beyond lesion--in 18%, extrafoveal fixation within lesion--in 26% of patients. Changes of fixation localization after treatment was found in 24% patients. Examination of visual fixation may be useful for prognosis of anti-VEGF treatment efficacy in patients with CNV. PMID:21721271

  4. Efficiency study of oil cooling of a screw compressor

    SciTech Connect

    Tree, D.R.; McKellar, M.G. . Ray W. Herrick Labs.); Fresco, A. )

    1990-01-01

    One of the major goals of all compressor manufacturers is to design and build as efficient a compressor as possible. In a screw compressor it appears that the way the compressor is cooled can have an effect on the compressor's efficiency. This paper presents experimental data on three different screw compressor cooling methods: Liquid Refrigerant Injection Cooling System; Thermosyphon Cooling System; and Oil Injection System. All tests were conducted on a hot gas bypass system using refrigerant R-22. The data taken shows that the Oil Injection System is slightly better than the other two. These tests should be repeated with a higher oil flow rate and ammonia as the working fluid. 10 figs.

  5. Structure of screw dislocation core in Ta at high pressure

    SciTech Connect

    Wang, Shaofeng Jiang, Na; Wang, Rui; Zhou, Ying

    2014-03-07

    The core structure and Peierls stress of the 1/2 ?111?(110) screw dislocation in Ta have been investigated theoretically using the modified Peierls–Nabarro theory that takes into account the discreteness effect of crystal. The lattice constants, the elastic properties, and the generalized-stacking-fault energy(?-surface) under the different pressures have been calculated from the electron density functional theory. The core structure of dislocation is determined by the modified Peierls equation, and the Peierls stress is evaluated from the dislocation energy that varies periodically as dislocation moves. The results show the core width and Peierls stress in Ta are weakly dependent of the pressure up to 100?GPa when the length and stress are measured separately by the Burgers vector b and shear modulus ?. This indicates that core structure is approximately scaling invariant for the screw dislocation in Ta. The scaled plasticity of Ta changes little in high pressure environment.

  6. Detecting thrust bearing failure within a screw compressor

    SciTech Connect

    Pallaver, C.

    1994-05-01

    A 3 1/2 mile ring of over 1000 superconducting magnets are needed to focus and drive the world`s highest energy particle smasher. 24 Refrigerators supply liquid helium to the magnets; 34 high pressure oil flooded screw compressors supply 285 psig helium gas to the refrigerators. The 400 h.p. screws are reliable machines that use 45 gallons of oil per minute to seal and lubricate the rotors, lubricate the bearings, and remove the heat of compression. These machines are spaced out in seven buildings over four miles. A minimum of 28 machines must be operating at all times. A contingent of operators start, stop, and monitor any machine from a distant control room. The 34 compressors have an average of 32,000 hours; 9 machines have over 40,000 hours; the highest is 55,000 hours.

  7. Structure of screw dislocation core in Ta at high pressure

    NASA Astrophysics Data System (ADS)

    Wang, Shaofeng; Jiang, Na; Wang, Rui; Zhou, Ying

    2014-03-01

    The core structure and Peierls stress of the 1/2?111?{110} screw dislocation in Ta have been investigated theoretically using the modified Peierls-Nabarro theory that takes into account the discreteness effect of crystal. The lattice constants, the elastic properties, and the generalized-stacking-fault energy(?-surface) under the different pressures have been calculated from the electron density functional theory. The core structure of dislocation is determined by the modified Peierls equation, and the Peierls stress is evaluated from the dislocation energy that varies periodically as dislocation moves. The results show the core width and Peierls stress in Ta are weakly dependent of the pressure up to 100 GPa when the length and stress are measured separately by the Burgers vector b and shear modulus ?. This indicates that core structure is approximately scaling invariant for the screw dislocation in Ta. The scaled plasticity of Ta changes little in high pressure environment.

  8. The effects of screw number and length on two methods of tension band plating.

    PubMed

    Haug, R H

    1993-02-01

    Bovine ribs were used to evaluate the effects that screw length and number have on two types of tension bands. Five trials each were done with one, two, three, or four screws per segment, using screws 4, 8, 12, or 16 mm in length and 2-mm adaptation plates or 2-mm mini-dynamic compression plates. The fractured ribs were subjected to increasing weights until failure. With the 2-mm adaptation plate, screw length played no role in the amount of weight resisted. Increasing the number of screws per segment increased the weight resisted to up to three screws per segment, after which no additional benefit was realized (P < .001). For the 2-mm mini-dynamic compression plate, increasing screw length increased the weight resisted up to three screws per segment, after which length had no effect (P < .001). Increasing the number of screws per segment increased the weight resisted up to three screws per segment, after which no additional benefit was realized (P < .001). PMID:8426255

  9. Wet-gas compression in twin-screw multiphase pumps 

    E-print Network

    Chan, Evan

    2009-05-15

    IN TWIN-SCREW MULTIPHASE PUMPS A Thesis by EVAN CHAN Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE December 2006 Major... of MASTER OF SCIENCE Approved by: Chair of Committee, Stuart L. Scott Committee Members, Daulat Mamora Charles Glover Head of Department, Stephen Holditch December 2006 Major Subject: Petroleum Engineering iii ABSTRACT...

  10. Supersonic self-similar screw-pinch plasma implosions

    SciTech Connect

    Venkatesan, R.C.

    1992-01-01

    Self-similar solutions are obtained for supersonic compression of a plasma containing an axial current and an entrained axial magnetic field (screw-pinch). The solutions presented here represent a screw-pinch plasma with diffuse current profile. Four separate plasma implosion modes are identified. The solutions representing the implosion modes differ qualitatively from Z-pinch and [Theta]-pinch schemes. They comprise of plasma annulus implosion, converging transverse MHD shock, propagation of fast magnetosonic waves towards the axis (weak discontinuities) and collapse of a hollow plasma liner. These modes are chosen on the basis of their ability to achieve magnetic field cumulation during the course of implosion. Analytic expressions describing asymptotic behavior of the hydromagnetic profiles are obtained for each of the four implosion modes. Numerical examples for selected boundary conditions, representing realistic plasma parameters for the purpose of ultra-high magnetic field generation, are presented for each of the four implosion modes. A special case representing the exponential implosion of a screw-pinch plasma has also been analyzed. It has been found that specifying an exponential dependence to the temporal contribution of the hydromagnetic variables, results in a more constrained solution space. This comparison is made with the case described above which has a power law type temporal contribution. Owing to the immense possible applications associated with plasma pinches, the time independent profiles of the hydromagnetic variables have been utilized in order to arrive at an estimate for the practical utility of the theoretical model. More specifically, the time dependent profiles of the hydromagnetic variables, and a piston condition for an external laser driven have been obtained. Numerical examples have also been provided for two cases representing screw-pinch plasma implosions occurring for realistic experimental parameters.

  11. Continuous expression of slurry in a screw press

    SciTech Connect

    Shirato, M.; Hayashi, N.; Iwata, M.; Murase, T.; Ogawa, Y.

    1985-01-01

    An approximate method is described for predicting the steadystate performance of a screw press for the continuous expression of a slurry, with the worm channel being modified as the path between two flat plates. Screw expression of a slurry involves two mechanisms of dewatering which, for a batch operation, can be analyzed by the variable-pressure, variable-rate theory of filtration and by consolidation theory. By assuming that the expression consists of a succession of batch processes, basic equations are derived for the relationship between the dehydration rate, the feed rate, and the expression pressure distribution in a constant-pitch, straighttaper screw press. The thickness of the filter cake in the worm channel and the flow distribution in the consolidated cake are calculated for a given pressure distribution and feed rate, and the solids concentration and rate of discharge of the cake are estimated. The critical speed of rotation of the worm, at which the slurry becomes highly deliquored, is strongly influenced by the external diameter and helical angle of the worm. The theoretical results are in good agreement with experimental data for clay slurries with a concentration of 0.31-0.46 in the feed.

  12. Modelling of the Heating Process in a Thermal Screw

    NASA Astrophysics Data System (ADS)

    Zhang, Xuan; Veje, Christian T.; Lassen, Benny; Willatzen, Morten

    2012-11-01

    The procedure of separating efficiently dry-stuff (proteins), fat, and water is an important process in the handling of waste products from industrial and commercial meat manufactures. One of the sub-processes in a separation facility is a thermal screw where the raw material (after proper mincing) is heated in order to melt fat, coagulate protein, and free water. This process is very energy consuming and the efficiency of the product is highly dependent on accurate temperature control of the process. A key quality parameter is the time that the product is maintained at temperatures within a certain threshold. A detailed mathematical model for the heating process in the thermal screw is developed and analysed. The model is formulated as a set of partial differential equations including the latent heat for the melting process of the fat and the boiling of water, respectively. The product is modelled by three components; water, fat and dry-stuff (bones and proteins). The melting of the fat component is captured as a plateau in the product temperature. The model effectively captures the product outlet temperature and the energy consumed. Depending on raw material composition, "soft" or "dry", the model outlines the heat injection and screw speeds necessary to obtain optimal output quality.

  13. Endovascular Aortic Aneurysm Repair with the Talent Stent-Graft: Outcomes in Patients with Large Iliac Arteries

    SciTech Connect

    England, Andrew; Butterfield, John S.; McCollum, Charles N.; Ashleigh, Raymond J.

    2008-07-15

    The purpose of this study is to report outcomes following endovascular aneurysm repair (EVAR) of abdominal aortic aneurysm (AAA) in patients with ectatic common iliac arteries (CIAs). Of 117 AAA patients treated by EVAR between 1998 and 2005, 87 (74%) had CIAs diameters <18 mm and 30 (26%) patients had one or more CIA diameters >18 but <25 mm. All patients were treated with Talent stent-grafts, 114 bifurcated and 3 AUI devices. Departmental databases and patient records were reviewed to assess outcomes. Technical success, iliac-related outcome, and iliac-related reintervention (IRSI) were analyzed. Patients with EVAR extending into the external iliac artery were excluded. Median (range) follow-up for the study group was 24 (1-84) months. Initial technical success was 98% for CIAs <18 mm and 100% for CIAs {>=}18 mm (p = 0.551). There were three distal type I endoleaks (two in the ectatic group) and six iliac limb occlusions (one in an ectatic patient); there were no statistically significant differences between groups (p = 0.4). There were nine IRSIs (three stent-graft extensions, six femorofemoral crossover grafts); three of these patients had one or both CIAs {>=}18 mm (p = 0.232). One-year freedom from IRSI was 92% {+-} 3% and 84% {+-} 9% for the <18-mm and {>=}18-mm CIA groups, respectively (p = 0.232). We conclude that the treatment of AAA by EVAR in patients with CIAs 18-24 mm appears to be safe and effective, however, it may be associated with more frequent reinterventions.

  14. Wire-free fixation of jaw fractures.

    PubMed

    Cousin, G C S

    2009-10-01

    Stainless steel wire is often used in the management of jaw fractures to provide intraoperative or postoperative intermaxillary fixation (IMF). Wiring of the jaws is time-consuming, a second procedure is needed to remove it, and needlestick injuries occur during placement. We report on 151 consecutive patients who had wire-free fixation of jaw fractures, and outline the value of a system of plastic anchorage points applied to individual teeth in both jaws that allows for wire-free IMF when they are linked by elastics (Rapid IMF, Synthes, PA, USA). A total of 150 successive patients had wire-free fixation of 146 mandibular and 5 maxillary fractures. Ninety-eight were hand-held in occlusion, and 52 were treated using Rapid IMF. There were few complications. PMID:19608310

  15. Late Thromboembolic Complication from a Palmaz Stent in the Common Iliac Artery

    SciTech Connect

    Stoeckelhuber, Beate M.; Szeimies, Ulrike; Spengel, Florentin A.; Kueffer, Georg

    1996-05-15

    A 56-year-old smoker presented with rest pain in his left leg and hyperfibrinogenemia. He was found to have a high-grade stenosing thrombus in a Palmaz stent which had been placed 4 years ago across a stenosing ulcerating plaque in the left common iliac artery. Systemic thrombolysis was successful but the patient refused long-term anticoagulation. He presented 2 months later with recurrent stent thrombosis and an embolus to the tibioperoneal trunk. Systemic lysis was successfully performed for the stent reobstruction but the distal embolic occlusion responded neither to systemic nor to local thrombolysis. This case suggests that patients with vascular stents and hyperfibrinogenemia and/or nicotine abuse should be considered candidates for long-term anticoagulation.

  16. Estimating the Radiation Dose to the Fetus in Prophylactic Internal Iliac Artery Balloon Occlusion: Three Cases

    PubMed Central

    Kai, Kentaro; Hamada, Tomohiro; Yuge, Akitoshi; Kiyosue, Hiro; Nishida, Yoshihiro; Nasu, Kaei; Narahara, Hisashi

    2015-01-01

    Background. Although radiation exposure is of great concern to expecting patients, little information is available on the fetal radiation dose associated with prophylactic internal iliac artery balloon occlusion (IIABO). Here we estimated the fetal radiation dose associated with prophylactic IIABO in Caesarean section (CS). Cases. We report our experience with the IIABO procedure in three consecutive patients with suspected placenta previa/accreta. Fetal radiation dose measurements were conducted prior to each CS by using an anthropomorphic phantom. Based on the simulated value, we calculated the fetal radiation dose as the absorbed dose. We found that the fetal radiation doses ranged from 12.88 to 31.6?mGy. The fetal radiation dose during the prophylactic IIABOs did not exceed 50?mGy. Conclusion. The IIABO procedure could result in a very small increase in the risk of harmful effects to the fetus. PMID:26180648

  17. Successful endovascular treatment for high take off aorto-iliac occlusive disease.

    PubMed

    Nomura, Akihiro; Nagashima, Michio; Tomoi, Yusuke; Tosaka, Atsushi; Soga, Yoshimitsu

    2015-01-01

    A 73-year-old man with a history of intermittent claudication for the previous six years visited our hospital. His ankle-brachial index (ABI) was very low on both sides, and computed tomography (CT) indicated bilateral aorto-iliac occlusive disease (AIOD). As he refused to undergo open surgery, endovascular treatment (EVT) was administered. After the first and second EVT sessions, the intermittent claudication improved completely. In addition, the ABI normalized (right: 1.01, left: 0.99), and CT demonstrated full expansion of the stents. His post-EVT course was uneventful for 18 months. The use of EVT to treat AIOD is technically feasible and may serve as a potential treatment option for patients with an inoperable condition. PMID:25876573

  18. MRSA-Infected External Iliac Artery Pseudoaneurysm Treated with Endovascular Stenting

    SciTech Connect

    Clarke, M.G.; Thomas, H.G. Chester, J.F.

    2005-04-15

    A 48-year-old woman with severe juvenile-onset rheumatoid arthritis presented with a bleeding cutaneous sinus distal to her right total hip replacement scar. Methicillin resistant Staphylococcus aureus (MRSA) was isolated on culture. She had previously undergone bilateral total hip and knee replacements at aged 23 and six years later had the right knee prosthesis removed for infection, with subsequent osteomyelitis of the femoral shaft and right total hip prosthesis disruption. Peripheral arteriography was performed in view of persistent bleeding from the sinus, which revealed a 6 cm false aneurysm filling from and compressing the right external iliac artery (EIA). A PTFE-covered, balloon expandable JOSTENT was deployed in the right EIA, successfully excluding the false aneurysm and preventing further bleeding from the sinus. No graft infection was reported at 12 months. This case illustrates the potential use of endovascular stent-grafting in the treatment of an infected pseudoaneurysm.

  19. Iatrogenic left common iliac artery and vein perforation during lumbar discectomy: a fatal case.

    PubMed

    Busardò, Francesco Paolo; Frati, Paola; Carbone, Iacopo; Pugnetti, Paola; Fineschi, Vittorio

    2015-01-01

    Iatrogenic vascular injury during lumbar disk surgery, although rare, is a serious complication, and when it does occur, can be sudden and life-threatening. The risk of injury to the pelvic vessels intra-operatively can be explained by the close proximity of the retroperitoneal vessels to the vertebral column therefore causing injury to the anterior longitudinal ligament, which can give access to the retroperitoneal space. If signs of circulatory instability are noted during lumbar disk surgery, early diagnosis of vascular injury and urgent transperitoneal surgery or emergency stenting can save the patient's life. Here, is presented the case of a 52-year-old man who underwent an elective lumbar discectomy for a rightward disk herniation in the L4-L5 intervertebral space and died 12h after the operation for a hemorrhagic shock due to a severe intra-abdominal hemorrhage following iatrogenic left common iliac artery and vein perforation during lumbar discectomy. PMID:25467198

  20. Iliac Artery Aneurysm Repair with Preservation of a Single Ectopic Pelvic Kidney

    PubMed Central

    Sarralde, Aurelio; Perez-Negueruela, Carolina

    2015-01-01

    An ultrasonographic study in a 60-year-old man incidentally detected an iliac artery aneurysm that gave rise to the renal artery of a single ectopic pelvic kidney. Renal-preservation solution could not be used during surgery, because the unclamped renal vein would have enabled the solution to enter the systemic circulation. Therefore, cold saline solution was infused through the renal ostium, and the kidney was maintained under cold saline immersion. We performed aortoiliac bypass and then implanted the renal artery into the bypass graft. Postoperatively, the patient's serum creatinine level increased; after one year, his renal function was normal. We discuss our use of cold saline solution for renal preservation. PMID:25873802

  1. Large aortic pseudoaneurysm and subsequent spondylodiscitis as a complication of endovascular treatment of iliac arteries.

    PubMed

    Faccenna, Federico; Alunno, Alessia; Castiglione, Anna; Carnevalini, Martina; Venosi, Salvatore; Gossetti, Bruno

    2013-10-01

    Both aortic pseudoaneurysm following endovascular aortoiliac reconstruction and spondylodiscitis subsequent to endograft infections are rare complications. We present a case of aortic false aneurysm following iliac arteries treatment complicated by spondylodiscitis after its endovascular repair. In this patient, a huge aortic pseudoaneurysm was diagnosed and treated in an emergency setting a few days after the procedure. A left aortomonoiliac endograft was placed and a femoro-femoral crossover bypass was performed. Afterward, the patient developed a stent graft infection and a lumbar spondylodiscitis. The patient was managed with a conservative treatment and, after 4 years, he continues to live. Analyzing this case, we would like to point out the following aspects: any procedure, although well established and technically simple, can cause life-threatening complications; hematomas resulting from endovascular exclusion of large pseudoaneurysms could be drained, to prevent bacterial infections. PMID:23564532

  2. Review of pelvic collateral pathways in aorto-iliac occlusive disease: demonstration by CT angiography.

    PubMed

    Akinwande, Olaguoke; Ahmad, Aamir; Ahmad, Shakeeb; Coldwell, Douglas

    2015-04-01

    The pelvic collateral system is a robust network of communicating vessels that provide the functional reserve to withstand chronic aorto-iliac occlusive disease. For establishment of collateral circulation, the afferent vessel must originate proximal to the occlusion and anastomose with vessel/s distal to the occlusion. These collateral pathways can be classified as viscero-systemic, systemic-systemic, and visceral-visceral. CT angiography (CTA) is often the initial modality for evaluating patients with atherosclerotic vascular disease, because it is non-invasive and has been shown to be comparable to conventional angiography. Most collateral pathways are well demonstrated on CTA, which therefore is a useful tool for preoperative planning and regional interventional procedures. PMID:24622738

  3. Impact of Stent Design on In-Stent Stenosis in a Rabbit Iliac Artery Model

    SciTech Connect

    Sommer, C. M. Grenacher, L.; Stampfl, U.; Arnegger, F. U.; Rehnitz, C.; Thierjung, H.; Stampfl, S.; Berger, I.; Richter, G. M.; Kauczor, H. U.; Radeleff, B. A.

    2010-06-15

    The purpose of this study was to evaluate the impact of stent design on in-stent stenosis in rabbit iliac arteries. Four different types of stent were implanted in rabbit iliac arteries, being different in stent design (crown or wave) and strut thickness (50 or 100 {mu}m). Ten stents of each type were implanted. Each animal received one crown and one wave stent with the same strut thickness. Follow-up was either 12 weeks (n = 10 rabbits) or 24 weeks (n = 10 rabbits). Primary study end points were angiographic and microscopic in-stent stenosis. Secondary study end points were vessel injury, vascular inflammation, and stent endothelialization. Average stent diameter, relative stent overdilation, average and minimal luminal diameter, and relative average and maximum luminal loss were not significantly different. However, a trend to higher relative stent overdilation was recognized in crown stents compared to wave stents. A trend toward higher average and minimal luminal diameter and lower relative average and maximum luminal loss was recognized in crown stents compared to wave stents with a strut thickness of 100 {mu}m. Neointimal height, relative luminal area stenosis, injury score, inflammation score, and endothelialization score were not significantly different. However, a trend toward higher neointimal height was recognized in crown stents compared to wave stents with a strut thickness of 50 {mu}m and a follow-up of 24 weeks. In conclusion, in this study, crown stents seem to trigger neointima. However, the optimized radial force might equalize the theoretically higher tendency for restenosis in crown stents. In this context, also more favorable positive remodeling in crown stents could be important.

  4. How Safe is Bilateral Internal Iliac Artery Embolization Prior to EVAR?

    SciTech Connect

    Bratby, M. J. Munneke, G. M.; Belli, A.-M.; Loosemore, T. M.; Loftus, I.; Thompson, M. M.; Morgan, R. A.

    2008-03-15

    Purpose. To assess the outcomes of patients after bilateral internal iliac artery (IIA) embolization prior to endovascular aneurysm repair (EVAR). Methods. Thirty-nine patients (age range 55-88 years, mean 72.5 years; 2 women) underwent IIA embolization/occlusion before EVAR. There were 28 patients with aorto-biiliac aneurysms and 6 with bilateral common iliac artery (CIA) aneurysms. Five patients with unilateral CIA aneurysms had previous surgical ligation of the contralateral IIA or inadvertent covering by the stent-graft of the contralateral IIA origin. Outcomes were assessed by clinical follow-up. Results. Severe ischemic complications were limited to spinal cord ischemia in 1 patient (3%) who developed paraparesis following EVAR. No other severe ischemic complications such as buttock necrosis, or bowel or bladder ischemia, occurred. Buttock and/or thigh claudication occurred in 12 patients (31%) and persisted beyond 1 year in 3 patients (9%). Sexual dysfunction occurred in 2 patients (5%). Patients who underwent simultaneous embolization had a 25% (3/12) ischemic complication rate versus 41% (11/27) in those with sequential embolization (p = 0.48). Embolization limited to the main trunk of the IIA resulted in a significantly reduced ischemic complication rate of 16% (3/19) versus 55% (11/20) of patients who had a more distal embolization of the IIA (p = 0.019, Fisher's exact test). Conclusion. Severe complications after bilateral IIA embolization are uncommon. Although buttock/thigh claudication occurs in around 30% of patients soon after the procedure, this resolves in the majority after 1 year. There is no obvious benefit for sequential versus simultaneous IIA embolization in our series. Occlusion of the proximal IIA trunk is associated with reduced complications compared with occlusion of the distal IIA.

  5. Predictors of Reintervention After Endovascular Repair of Isolated Iliac Artery Aneurysm

    SciTech Connect

    Zayed, Hany A. Attia, Rizwan; Modarai, Bijan; Clough, Rachel E.; Bell, Rachel E.; Carrell, Tom; Sabharwal, Tarun; Reidy, John; Taylor, Peter R.

    2011-02-15

    The objective of this study was to identify factors predicting the need for reintervention after endovascular repair of isolated iliac artery aneurysm (IIAA). We reviewed prospectively collected database records of all patients who underwent endovascular repair of IIAA between 1999 and 2008. Detailed assessment of the aneurysms was performed using computed tomography angiography (CTA). Follow-up protocol included CTA at 3 months. If this showed no complication, then annual duplex scan was arranged. Multivariate analysis and analysis of patient survival and freedom from reintervention were performed using Kaplan-Meier life tables. Forty IIAAs (median diameter 44 mm) in 38 patients were treated (all men; median age 75 years), and median follow-up was 27 months. Endovascular repair of IIAA was required in 14 of 40 aneurysms (35%). The rate of type I endoleak was significantly higher with proximal landing zone (PLZ) diameter >30 mm in the aorta or >24 mm in the common iliac artery or distal landing zone (DLZ) diameter >24 mm (P = 0.03, 0.03, and 0.0014, respectively). Reintervention rate (RR) increased significantly with increased diameter or decreased length of PLZ; increased DLZ diameter; and endovascular IIAA repair (P = 0.005, 0.005, 0.02, and 0.02 respectively); however, RR was not significantly affected by length of PLZ or DLZ. Freedom-from-reintervention was 97, 93, and 86% at 12, 24, and 108 months. There was no in-hospital or aneurysm-related mortality. Endovascular IIAA repair is a safe treatment option. Proper patient selection is essential to decrease the RR.

  6. Endovascular Tubular Stent-Graft Placement for Isolated Iliac Artery Aneurysms

    SciTech Connect

    Okada, Takuya Yamaguchi, Masato; Kitagawa, Atsushi; Kawasaki, Ryota; Nomura, Yoshikatsu; Okita, Yutaka; Sugimura, Kazuro; Sugimoto, Koji

    2012-02-15

    Purpose: To evaluate the safety, efficacy, and mid-term outcomes of endovascular tubular stent-graft placement for repair of isolated iliac artery aneurysms (IAAs). Materials and Methods: Between January 2002 and March 2010, 20 patients (7 women and 13 men; mean age 74 years) underwent endovascular repair of 22 isolated IAAs. Two patients underwent endovascular repair for bilateral aneurysms. Ten para-anastomotic aneurysms (45%) developed after open abdominal aortic aneurysm (AAA) repair with an aorto-iliac graft, and 12 were true aneurysms (55%). Eleven straight and 11 tapered stent-grafts were placed. Contrast-enhanced computed tomography (CT) was performed to detect complications and evaluate aneurysmal shrinkage at week 1, 3, 6, and 12 months and once every year thereafter. Non-contrast-enhanced CT was performed in seven patients with chronic kidney disease. Results: All procedures were successful, without serious complications, during the mean (range) follow-up period of 746 days (47-2651). Type II endoleak not requiring treatment was noted in one patient. The mean (SD) diameters of the true and para-anastomotic aneurysms significantly (p < 0.05) decreased from 42.0 (9.3) to 36.9 (13.6) mm and from 40.1 (13.0) to 33.6 (15.8) mm, respectively; the mean (SD) shrinkage rates were 15.1% (20.2%) and 18.9% (22.4%), respectively. The primary patency rate was 100%, and no secondary interventions were required. Four patients (21%) developed transient buttock claudication, and one patient (5%) developed colorectal ischaemia, which was treated conservatively. Conclusion: Endovascular tubular stent-graft placement for the repair of isolated IAAs is safe and efficacious. Tapered stent-grafts of various sizes are required for accurate placement.

  7. Endovascular Treatment of Anastomotic Pseudoaneurysms after Aorto-iliac Surgical Reconstruction

    SciTech Connect

    Lagana, Domenico Carrafiello, Gianpaolo; Mangini, Monica Recaldini, Chiara; Lumia, Domenico; Cuffari, Salvatore; Caronno, Roberto; Castelli, Patrizio; Fugazzola, Carlo

    2007-11-15

    Purpose. To assess the effectiveness of endovascular treatment of anastomotic pseudoaneurysms (APAs) following aorto-iliac surgical reconstruction. Materials. We retrospectively evaluated 21 men who, between July 2000 and March 2006, were observed with 30 APAs, 13 to the proximal anastomosis and 17 to the distal anastomosis. The patients had had previous aorto-iliac reconstructive surgery with a bypass due to aneurysm (15/21) or obstructive disease (6/21). The following devices were used: 12 bifurcated endoprostheses, 2 aorto-monoiliac, 4 aortic extenders, 1 stent-graft leg, and 2 covered stents. Follow-up was performed with CT angiography at 1, 3, and 6 months after the procedure and yearly thereafter. Results. Immediate technical success was 100%. No periprocedural complications occurred. Four patients died during follow-up from causes not related to APA, and 1 (treated for prosthetic-enteric fistula) from sepsis 3 months after the procedure. During a mean follow-up of 19.7 months (range 1-72 months), 2 of 21 occlusions of stent-graft legs occurred 3 and 24 months after the procedure (treated with thrombolysis and percutaneous transluminal angioplasty and femorofemoral bypass, respectively) and 1 type I endoleak. Primary clinical success rate was 81% and secondary clinical success was 91%. Conclusion. Endovascular treatment is a valid alternative to open surgery and can be proposed as the treatment of choice for APAs, especially in patients who are a high surgical risk. Further studies with larger series and longer follow-up are necessary to confirm the long-term effectiveness of this approach.

  8. Balloon-Assisted Occlusion of the Internal Iliac Arteries in Patients with Placenta Accreta/Percreta

    SciTech Connect

    Bodner, Leonard J.; Nosher, John L. Gribbin, Christopher; Siegel, Randall L.; Beale, Stephanie; Scorza, William

    2006-06-15

    Background. Placenta accreta/percreta is a leading cause of third trimester hemorrhage and postpartum maternal death. The current treatment for third trimester hemorrhage due to placenta accreta/percreta is cesarean hysterectomy, which may be complicated by large volume blood loss. Purpose. To determine what role, if any, prophylactic temporary balloon occlusion and transcatheter embolization of the anterior division of the internal iliac arteries plays in the management of patients with placenta accreta/percreta. Methods. The records of 28 consecutive patients with a diagnosis of placenta accreta/percreta were retrospectively reviewed. Patients were divided into two groups. Six patients underwent prophylactic temporary balloon occlusion, followed by cesarean section, transcatheter embolization of the anterior division of the internal iliac arteries and cesarean hysterectomy (n = 5) or uterine curettage (n = 1). Twenty-two patients underwent cesarean hysterectomy without endovascular intervention. The following parameters were compared in the two groups: patient age, gravidity, parity, gestational age at delivery, days in the intensive care unit after delivery, total hospital days, volume of transfused blood products, volume of fluid replacement intraoperatively, operating room time, estimated blood loss, and postoperative morbidity and mortality. Results. Patients in the embolization group had more frequent episodes of third trimester bleeding requiring admission and bedrest prior to delivery (16.7 days vs. 2.9 days), resulting in significantly more hospitalization time in the embolization group (23 days vs. 8.8 days) and delivery at an earlier gestational age than in those in the surgical group (32.5 weeks). There was no statistical difference in mean estimated blood loss, volume of replaced blood products, fluid replacement needs, operating room time or postoperative recovery time. Conclusion. Our findings do not support the contention that in patients with placenta accreta/percreta, prophylactic temporary balloon occlusion and embolization prior to hysterectomy diminishes intraoperative blood loss.

  9. Common Iliac Artery Thrombosis following Pelvic Surgery Resulting in Kidney Allograft Failure Successfully Treated by Percutaneous Transluminal Angioplasty with Balloon-Expandable Covered Stent

    PubMed Central

    Golla, Maheswara S.; Acharjee, Subasit; Jaber, Bertrand L.; Garcia, Lawrence A.

    2015-01-01

    We report the case of a 66-year-old woman who developed acute kidney allograft failure due to thrombotic occlusion of the common iliac artery after hysterectomy requiring emergent allograft rescue. She underwent percutaneous transluminal angioplasty with endovascular balloon expandable covered stent graft placement in the right common iliac artery. Although there are a handful of case reports of acute limb ischemia secondary to acute common iliac artery thrombosis, this is the first case reported in the literature resulting in successful kidney allograft rescue following pelvic surgery. PMID:26355669

  10. 21 CFR 888.3020 - Intramedullary fixation rod.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...SERVICES (CONTINUED) MEDICAL DEVICES ORTHOPEDIC DEVICES Prosthetic Devices § 888.3020 Intramedullary fixation rod. ...An intramedullary fixation rod is a device intended to be implanted that consists of a rod made of alloys such as...

  11. 21 CFR 888.3020 - Intramedullary fixation rod.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...SERVICES (CONTINUED) MEDICAL DEVICES ORTHOPEDIC DEVICES Prosthetic Devices § 888.3020 Intramedullary fixation rod. ...An intramedullary fixation rod is a device intended to be implanted that consists of a rod made of alloys such as...

  12. THE CONUNDRUM OF MARINE N2 FIXATION CLAIRE MAHAFFEY

    E-print Network

    Capone, Douglas G.

    -sea partitioning of CO2 on climate time-scales. The question remains: does the importance of marine N2 fixation estimates of N2 fixation, largely of the planktonic cyanobacte- rium, Trichodesmium, can account for only

  13. Between Linguistic Attention and Gaze Fixations in Multimodal Conversational Interfaces

    E-print Network

    Between Linguistic Attention and Gaze Fixations in Multimodal Conversational Interfaces Rui Fang attention in multimodal conversational interfaces. To address this issue, we conducted a preliminary Linguistic Attention, Gaze Fixation, Multimodal Conversational Interfaces 1. INTRODUCTION In human machine

  14. 21 CFR 888.3060 - Spinal intervertebral body fixation orthosis.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...SERVICES (CONTINUED) MEDICAL DEVICES ORTHOPEDIC DEVICES Prosthetic Devices § 888.3060 Spinal intervertebral body fixation...fixation orthosis is a device intended to be implanted made of titanium. It consists of various vertebral plates that are...

  15. 21 CFR 888.3060 - Spinal intervertebral body fixation orthosis.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...SERVICES (CONTINUED) MEDICAL DEVICES ORTHOPEDIC DEVICES Prosthetic Devices § 888.3060 Spinal intervertebral body fixation...fixation orthosis is a device intended to be implanted made of titanium. It consists of various vertebral plates that are...

  16. 21 CFR 888.3060 - Spinal intervertebral body fixation orthosis.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...SERVICES (CONTINUED) MEDICAL DEVICES ORTHOPEDIC DEVICES Prosthetic Devices § 888.3060 Spinal intervertebral body fixation...fixation orthosis is a device intended to be implanted made of titanium. It consists of various vertebral plates that are...

  17. 21 CFR 888.3060 - Spinal intervertebral body fixation orthosis.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...SERVICES (CONTINUED) MEDICAL DEVICES ORTHOPEDIC DEVICES Prosthetic Devices § 888.3060 Spinal intervertebral body fixation...fixation orthosis is a device intended to be implanted made of titanium. It consists of various vertebral plates that are...

  18. Minimally Invasive Option Using Percutaneous Pedicle Screw for Instability of Metastasis Involving Thoracolumbar and Lumbar Spine : A Case Series in a Single Center

    PubMed Central

    Park, Ho-Young; Park, Se-Jun; Kim, Eun-Sang; Lee, Chong-Suh; Eoh, Whan

    2015-01-01

    Objective To report a minimally invasive treatment option using percutaneous pedicle screw fixation with adjuvant treatment for metastatic thoraco-lumbar and lumbar spinal tumors. Methods This is a retrospective study of charts of patients with spinal metastases. All were older than 18 years of age and were considered to have more than 3 months of life expectancy. The patients had single or two level lesions, and compression fracture or impending fracture. Exclusion criterion was metastasis showing severe epidural compression with definite neurological symptoms. Usually spinal segments from one level above to below pathology were stabilized. Visual analog scale (VAS) score for pain assessment and Frankel scale for neurological deficit were used, while pre- and post-operative performance status was evaluated using the Eastern Cooperative Oncology Group (ECOG). Results Twelve patients (nine men, three women; median age 54.29 years) underwent surgery. All patients presented with back pain with/without radicular pain. There were no early complications and perioperative mortalities. Following surgery, a significant difference between average pre- and post-operative VAS scores was found (p=0.003). Overall, 91.8% of patients (11/12) experienced improvement in their ECOG score post-operatively. The mean ambulation time was 196.9 days [95% confidence interval (CI), 86.2-307.6 days; median, 97 days]. During follow-up, nine patients died and the mean overall survival time in enrolled twelve patients was 249.9 days (95% CI, 145.3-354.4 days; median, 176 days). Conclusion Minimally invasive treatment using percutaneous pedicle screw fixation with adjuvant treatment is a good alternative treatment option for potential instability of the thoraco-lumbar and lumbar spinal metastasis. PMID:25733990

  19. Fabrication of a screw-retained restoration avoiding the facial access hole: A clinical report.

    PubMed

    Garcia-Gazaui, Sabrina; Razzoog, Michael; Sierraalta, Marianella; Saglik, Berna

    2015-11-01

    Dental implant restorations may be either screw-retained or cemented onto an abutment. While each method has its advantages and disadvantages, cemented restorations are commonly used in the maxillary arch, usually because of esthetic concerns. Available bone in the anterior maxilla dictates the placement of the implant, which may result in a facially positioned screw-access opening. Still, a growing volume of literature states that periimplant soft tissues respond more favorably to screw-retained crowns than cement-retained crowns. This clinical report outlines a treatment with a new method of fabricating a custom abutment-crown combination for a screw-retained restoration. The technique allows the channel for the screw to be placed at an angle other than parallel to the implant body. In this case, the practitioner may choose either a screw-retained or cement-retained implant restoration, where previously only a cemented restoration was possible. PMID:26344192

  20. Imaging screw dislocations at atomic resolution by aberration-corrected electron optical sectioning

    PubMed Central

    Yang, H.; Lozano, J. G.; Pennycook, T. J.; Jones, L.; Hirsch, P. B.; Nellist, P. D.

    2015-01-01

    Screw dislocations play an important role in materials' mechanical, electrical and optical properties. However, imaging the atomic displacements in screw dislocations remains challenging. Although advanced electron microscopy techniques have allowed atomic-scale characterization of edge dislocations from the conventional end-on view, for screw dislocations, the atoms are predominantly displaced parallel to the dislocation line, and therefore the screw displacements are parallel to the electron beam and become invisible when viewed end-on. Here we show that screw displacements can be imaged directly with the dislocation lying in a plane transverse to the electron beam by optical sectioning using annular dark field imaging in a scanning transmission electron microscope. Applying this technique to a mixed [a+c] dislocation in GaN allows direct imaging of a screw dissociation with a 1.65-nm dissociation distance, thereby demonstrating a new method for characterizing dislocation core structures. PMID:26041257

  1. Research on energy conversion mechanism of a screw centrifugal pump under the water

    NASA Astrophysics Data System (ADS)

    Quan, H.; Li, R. N.; Su, Q. M.; Han, W.; Cheng, X. R.; Shen, Z. J.

    2013-12-01

    In order to research screw centrifugal pump impeller power capability and energy conversion mechanism, we used Navier-Stokes equation and standard k-? equation turbulence model on the basis of the Euler equations to carry out screw centrifugal pump internal flow numerical simulation. This was explored by simulating specific design conditions; the medium is water, variation of speed and pressure of flow filed under the action of the impeller, and the screw centrifugal impeller shroud line and wheel line segment take monitoring sites. The monitoring points are between dynamic head and static head change to analyze the energy conversion capability along the impeller corners of screw centrifugal pump. The results show that the energy of fluid of the screw centrifugal pump is provided by spiral segment, the spiral segment in front of the impeller has played a multi-level role, it has significant reference value to research the energy conversion mechanism of screw centrifugal pump under solid-liquid two phase.

  2. Single-Dose Local Simvastatin Injection Improves Implant Fixation via Increased Angiogenesis and Bone Formation in an Ovariectomized Rat Model

    PubMed Central

    Tan, Jie; Yang, Ning; Fu, Xin; Cui, Yueyi; Guo, Qi; Ma, Teng; Yin, Xiaoxue; Leng, Huijie; Song, Chunli

    2015-01-01

    Background Statins have been reported to promote bone formation. However, taken orally, their bioavailability is low to the bones. Implant therapies require a local repair response, topical application of osteoinductive agents, or biomaterials that promote implant fixation. Material/Methods The present study evaluated the effect of a single local injection of simvastatin on screw fixation in an ovariectomized rat model of osteoporosis. Results Dual-energy X-ray absorptiometry, micro-computed tomography, histology, and biomechanical tests revealed that 5 and 10 mg simvastatin significantly improved bone mineral density by 18.2% and 22.4%, respectively (P<0.05); increased bone volume fraction by 51.0% and 57.9%, trabecular thickness by 16.4% and 18.9%, trabeculae number by 112.0% and 107.1%, and percentage of osseointegration by 115.7% and 126.3%; and decreased trabeculae separation by 34.1% and 36.6%, respectively (all P<0.01). Bone mineral apposition rate was significantly increased (P<0.01). Furthermore, implant fixation was significantly increased (P<0.05), and bone morphogenetic protein 2 (BMP2) expression was markedly increased. Local injection of a single dose of simvastatin also promoted angiogenesis. Vessel number, volume, thickness, surface area, and vascular volume per tissue volume were significantly increased (all P<0.01). Vascular endothelial growth factor (VEGF), VEGF receptor-2, von Willebrand factor, and platelet endothelial cell adhesion molecule-1 expression were enhanced. Conclusions A single local injection of simvastatin significantly increased bone formation, promoted osseointegration, and enhanced implant fixation in ovariectomized rats. The underlying mechanism appears to involve enhanced BMP2 expression and angiogenesis in the target bone. PMID:25982481

  3. Comparison of femoral fixation methods for anterior cruciate ligament reconstruction with patellar tendon graft: a mechanical analysis in porcine knees.

    PubMed

    Milano, Giuseppe; Mulas, Pier Damiano; Ziranu, Fabio; Deriu, Laura; Fabbriciani, Carlo

    2007-06-01

    The aim of the present study was to evaluate the structural properties of femur-patellar tendon graft complex in anterior cruciate ligament (ACL) reconstruction using different femoral fixation devices. Type of study is biomechanical testing. An ACL reconstruction was performed on 40 cadaver porcine knees, using patellar tendon (PT) graft. Specimens were divided into four groups according to the femoral fixation: interference absorbable screw (Group A), metallic setscrew (Group B), absorbable pins (Group C), and a combination of metallic setscrew and pin (Group D). Other ten knees were used as controls. On each sample, a cyclic loading test, then a load-to-failure test were performed. Elongation after 1,000 loading cycles, ultimate failure load, yield load, stiffness, deformation at the yield point, and mode of failure were recorded. Kruskal-Wallis test and Tukey test were used to compare the differences between groups. The lowest mean elongation after 1,000 load cycles was observed for Group B (1.7 +/- 1.4 mm) and D (1.2 +/- 0.3 mm). Ultimate failure load of Group D (1,021.8 +/- 199.4 N) was comparable with that of normal ACL (1,091.2 +/- 193.3 N) and PT graft (1,140.6 +/- 285.7 N). All other groups were lower than the controls. For mean stiffness, all the groups, excepting for Group D (172.8 +/- 40.4 N/mm), were significantly lower than PT control group (216 +/- 78.4 N/mm). Mode of failure was graft pullout for Groups A and B, distal pin breakage for Group C, and midsubstance graft rupture in 80% of the cases for Group D. Only combined compression and suspension fixation did not show significantly different structural properties in comparison with normal ACL and PT graft. Furthermore, it showed no risk of graft pullout or hardware breakdown in comparison with other fixation devices. PMID:17295042

  4. 21 CFR 888.3060 - Spinal intervertebral body fixation orthosis.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Spinal intervertebral body fixation orthosis. 888.3060 Section 888.3060 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN... body fixation orthosis. (a) Identification. A spinal intervertebral body fixation orthosis is a...

  5. 21 CFR 888.3060 - Spinal intervertebral body fixation orthosis.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Spinal intervertebral body fixation orthosis. 888.3060 Section 888.3060 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN... body fixation orthosis. (a) Identification. A spinal intervertebral body fixation orthosis is a...

  6. 21 CFR 888.3060 - Spinal intervertebral body fixation orthosis.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Spinal intervertebral body fixation orthosis. 888.3060 Section 888.3060 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN... body fixation orthosis. (a) Identification. A spinal intervertebral body fixation orthosis is a...

  7. 21 CFR 888.3060 - Spinal intervertebral body fixation orthosis.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Spinal intervertebral body fixation orthosis. 888.3060 Section 888.3060 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN... body fixation orthosis. (a) Identification. A spinal intervertebral body fixation orthosis is a...

  8. 21 CFR 888.3060 - Spinal intervertebral body fixation orthosis.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Spinal intervertebral body fixation orthosis. 888.3060 Section 888.3060 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN... body fixation orthosis. (a) Identification. A spinal intervertebral body fixation orthosis is a...

  9. 21 CFR 868.5770 - Tracheal tube fixation device.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... (CONTINUED) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5770 Tracheal tube fixation device. (a) Identification. A tracheal tube fixation device is a device used to hold a tracheal tube in... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Tracheal tube fixation device. 868.5770...

  10. 21 CFR 868.5770 - Tracheal tube fixation device.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... (CONTINUED) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5770 Tracheal tube fixation device. (a) Identification. A tracheal tube fixation device is a device used to hold a tracheal tube in... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Tracheal tube fixation device. 868.5770...

  11. FLOODING STRESS Dinitrogen Fixation by Winter Chickpea Across Scales in

    E-print Network

    van Kessel, Chris

    FLOODING STRESS Dinitrogen Fixation by Winter Chickpea Across Scales in Waterlogged Soil a single tillage management system, however, considerable variation in N2 fixation by Keywords chickpea fixation by rain-fed chickpea (Cicer arietinum L.) at the field- and micro-scales (0.15 m spacing) after

  12. Unfixing Design Fixation: From Cause to Computer Simulation

    ERIC Educational Resources Information Center

    Dong, Andy; Sarkar, Somwrita

    2011-01-01

    This paper argues that design fixation, in part, entails fixation at the level of meta-representation, the representation of the relation between a representation and its reference. In this paper, we present a mathematical model that mimics the idea of how fixation can occur at the meta-representation level. In this model, new abstract concepts…

  13. Trichodesmium and nitrogen fixation in the Kuroshio

    NASA Astrophysics Data System (ADS)

    Shiozaki, T.; Takeda, S.; Itoh, S.; Kodama, T.; Liu, X.; Hashihama, F.; Furuya, K.

    2015-07-01

    Nitrogen fixation in the Kuroshio influences nitrogen balance in the North Pacific Ocean. The genus Trichodesmium is recognized as a major diazotroph in the Kuroshio. Although its abundance is higher in the Kuroshio than in adjacent waters, the reason for this difference remains unclear. The present study investigated the abundance of Trichodesmium spp. and nitrogen fixation together with concentrations of dissolved iron and phosphate, whose availabilities potentially control diazotrophy, in the Kuroshio and its marginal seas. We performed the observations near the Miyako Islands, which form part of the Ryukyu Islands, situated along the Kuroshio, since satellite analysis suggested that material transport could occur from the islands to the Kuroshio. Trichodesmium spp. bloomed (> 20 000 filaments L-1) near the Miyako Islands, and the abundance was high in the Kuroshio and the Kuroshio bifurcation region of the East China Sea, but was low in the Philippine Sea. The abundance of Trichodesmium spp. was significantly correlated with the total nitrogen fixation activity. The surface concentrations of dissolved iron (0.19-0.89 nM) and phosphate (< 3-36 nM) were similar for all of the study areas, indicating that the nutrient distribution could not explain the spatial differences in Trichodesmium spp. abundance and nitrogen fixation. We used a numerical model to simulate the transportation of water around the Ryukyu Islands to the Kuroshio. Our results indicate that Trichodesmium growing around the islands situated along the Kuroshio is potentially important for determining diazotrophy in this region.

  14. Treating Somatic Fixation: A Biopsychosocial Approach

    PubMed Central

    McDaniel, Susan H.; Campbell, Thomas; Seaburn, David

    1991-01-01

    Somatic fixation occurs when the patient or physician focuses exclusively on the biomedical aspects of a complex illness. Individual, family, and cultural factors promote the expression of emotional experience through physical symptoms. The physician or treatment team establishes a collaborative relationship with the patient and family, integrating biomedical and psychosocial evaluations and respecting the patient's defenses. PMID:21228995

  15. Biological nitrogen fixation in Louisiana sugarcane

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Nitrogen (N) is a major input for sugarcane with crops in Louisiana receiving between 90 and 180 kg/ha with the cost of N increasing 75% in the last decade. Biological N fixation (BNF) may be a viable alternative to fertilizer N. The process relies on endophytic bacteria (bacteria that live among th...

  16. 21 CFR 886.1290 - Fixation device.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...device intended for use as a fixation target for the patient during ophthalmological examination. The patient directs his or her gaze so that the visual image of the object falls on the fovea centralis (the center of the macular retina of the eye.)...

  17. 21 CFR 886.1290 - Fixation device.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...device intended for use as a fixation target for the patient during ophthalmological examination. The patient directs his or her gaze so that the visual image of the object falls on the fovea centralis (the center of the macular retina of the eye.)...

  18. 21 CFR 886.1290 - Fixation device.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...device intended for use as a fixation target for the patient during ophthalmological examination. The patient directs his or her gaze so that the visual image of the object falls on the fovea centralis (the center of the macular retina of the eye.)...

  19. 21 CFR 886.1290 - Fixation device.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...device intended for use as a fixation target for the patient during ophthalmological examination. The patient directs his or her gaze so that the visual image of the object falls on the fovea centralis (the center of the macular retina of the eye.)...

  20. 21 CFR 886.1290 - Fixation device.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...device intended for use as a fixation target for the patient during ophthalmological examination. The patient directs his or her gaze so that the visual image of the object falls on the fovea centralis (the center of the macular retina of the eye.)...