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Sample records for screw augmentation techniques

  1. 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

  2. Assessment of different screw augmentation techniques and screw designs in osteoporotic spines

    PubMed Central

    Chavanne, A.; Spitaler, R.; Kropik, K.; Aigner, N.; Ogon, M.; Redl, H.

    2008-01-01

    This is an experimental study on human cadaver spines. The objective of this study is to compare the pullout forces between three screw augmentation methods and two different screw designs. Surgical interventions of patients with osteoporosis increase following the epidemiological development. Biomechanically the pedicle provides the strongest screw fixation in healthy bone, whereas in osteoporosis all areas of the vertebra are affected by the disease. This explains the high screw failure rates in those patients. Therefore PMMA augmentation of screws is often mandatory. This study involved investigation of the pullout forces of augmented transpedicular screws in five human lumbar spines (L1–L4). Each spine was treated with four different methods: non-augmented unperforated (solid) screw, perforated screw with vertebroplasty augmentation, solid screw with vertebroplasty augmentation and solid screw with balloon kyphoplasty augmentation. Screws were augmented with Polymethylmethacrylate (PMMA). The pullout forces were measured for each treatment with an Instron testing device. The bone mineral density was measured for each vertebra with Micro-CT. The statistical analysis was performed with a two-sided independent student t test. Forty screws (10 per group and level) were inserted. The vertebroplasty-augmented screws showed a significant higher pullout force (mean 918.5 N, P = 0.001) than control (mean 51 N), the balloon kyphoplasty group did not improve the pullout force significantly (mean 781 N, P > 0.05). However, leakage occurred in some cases treated with perforated screws. All spines showed osteoporosis on Micro-CT. Vertebroplasty-augmented screws, augmentation of perforated screws and balloon kyphoplasty augmented screws show higher pullout resistance than non-augmented screws. Significant higher pullout forces were only reached in the vertebroplasty augmented vertebra. The perforated screw design led to epidural leakage due to the position of the

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

    PubMed

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

    2016-09-01

    Cement augmentation of pedicle screws biomechanically increases screw purchase in the bone. However, clinical complications may occur. The pros and cons of the technique are discussed from different clinical perspectives. PMID:27514827

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

    PubMed

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

    2016-07-01

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

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

    PubMed

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

    2016-07-01

    OBJECTIVE Loosening and pullout of pedicle screws are well-known problems in pedicle screw fixation surgery. Augmentation of pedicle screws with bone cement, first described as early as 1975, increases the pedicle-screw interface and pullout force in osteoporotic vertebrae. The aim of the present study was to identify cement leakage and pulmonary embolism rates in a large prospective single-center series of pedicle screw augmentations. METHODS All patients who underwent cement-augmented pedicle screw placement between May 2006 and October 2010 at the authors' institution were included in this prospective cohort study. Perivertebral cement leakage and pulmonary cement embolism were evaluated with a CT scan of the area of operation and with a radiograph of the chest, respectively. RESULTS A total of 98 patients underwent placement of cement-augmented pedicle screws; 474 augmented screws were inserted in 237 vertebrae. No symptomatic perivertebral cement leakage or symptomatic pulmonary cement embolism was observed, but asymptomatic perivertebral cement leakage was seen in 88 patients (93.6%) and in 165 augmented vertebrae (73.3%). Cement leakage most often occurred in the perivertebral venous system. Clinically asymptomatic pulmonary cement embolism was found in 4 patients (4.1%). CONCLUSIONS Perivertebral cement leakage often occurs in pedicle screw augmentation, but in most cases, it is clinically asymptomatic. Cement augmentation should be performed under continuous fluoroscopy to avoid high-volume leakage. Alternative strategies, such as use of expandable screws, should be examined in more detail for patients at high risk of screw loosening. PMID:26943258

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

    PubMed Central

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

    2015-01-01

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

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

    PubMed

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

    2015-01-01

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

  8. Hydroxyapatite composite resin cement augmentation of pedicle screw fixation.

    PubMed

    Turner, Alexander W L; Gillies, R Mark; Svehla, Martin J; Saito, Masanobu; Walsh, William R

    2003-01-01

    Pedicle screw stability is poor in osteopenic vertebrae attributable, in part, to low screw-bone interface strength. The current authors examined cement augmentation using a low curing temperature hydroxyapatite and bis-phenol-A glycidol methacrylate-based composite resin. This cement may stiffen the screw-bone interface and reduce the harmful effects associated with polymethylmethacrylate regarding temperature and toxic monomer. Thirty-five lumbar vertebrae from human cadavers were instrumented with pedicle screws, with one pedicle previously injected with cement and the other as the control. Caudocephalad toggling of +/- 1 mm for 1600 cycles was applied to the pedicle screws, and the resulting forces supported by the implant-bone interface were captured by a load cell. A curve was constructed from the peak caudal load for each cycle and three mechanical measures parameterized this curve: (1) initial load; (2) rate of load decay during the first 400 cycles; and (3) final load. The initial load increased by 16% as a result of cement augmentation, the final load increased by 65%, and the rate of load decay decreased by 59%. Cement augmentation of pedicle screws increased the stiffness and stability of the screw-bone interface. PMID:12579026

  9. True anteroposterior view pedicle screw insertion technique

    PubMed Central

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

    2016-01-01

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

  10. 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

  11. Polymethylmethacrylate-augmented screw fixation for stabilization in metastatic spinal tumors. Technical note.

    PubMed

    Jang, Jee Soo; Lee, Sang Ho; Rhee, Chang Hun; Lee, Seung Hoon

    2002-01-01

    Screw fixation augmented with polymethylmethacrylate (PMMA) or some other biocompatible bone cement has been used in patients with osteoporosis requiring spinal fusion. No clinical studies have been conducted on PMMA-augmented screw fixation for stabilization of the vertebral column in patients with metastatic spinal tumors. The purpose of this study was to determine whether screw fixation augmented with PMMA might be suitable in patients treated for multilevel metastatic spinal tumors. Ten patients with metastatic spinal tumors involving multiple vertebral levels underwent stabilization procedures in which PMMA was used to augment screw fixation after decompression of the spinal cord. Within 15 days, partial or complete relief from pain was obtained in all patients postoperatively. Two of four patients in whom neurological deficits caused them to be nonambulatory before surgery were able to ambulate postoperatively. Neither collapse of the injected vertebral bodies nor failure of the screw fixation was observed during the mean follow-up period of 6.7 months. Screw fixation augmented with PMMA may offer stronger stabilization and facilitate the instrumentation across short segments in the treatment of multilevel metastatic spinal tumors. PMID:11795702

  12. Augmentation of screw fixation with injectable calcium sulfate bone cement in ovariectomized rats.

    PubMed

    Yu, Xiao-Wei; Xie, Xin-Hui; Yu, Zhi-Feng; Tang, Ting-Ting

    2009-04-01

    The objective of this study was to determine the effect of augmenting screw fixation with an injectable calcium sulfate cement (CSC) in the osteoporotic bone of ovariectomized rats. The influence of the calcium sulfate (CS) on bone remodeling and screw anchorage in osteoporotic cancellous bone was systematically investigated using histomorphometric and biomechanical analyses. The femoral condyles of 55 Sprague-Dawley ovariectomized rats were implanted with screw augmented with CS, while the contralateral limb received a nonaugmented screw. At time intervals of 2, 4, 8, 12, and 16 weeks, 11 rats were euthanized. Six pair-matched samples were used for histological analysis, while five pair-matched samples were preserved for biomechanical testing. Histomorphometric data showed that CS augmented screws activated cancellous bone formation, evidenced by a statistically higher (p < 0.05) percentage of osteoid surface at 2, 4, and 8 weeks and a higher rate of bone mineral apposition at 12 weeks compared with nonaugmented screws. The amount of the bone-screw contact at 2, 8, and 12 weeks and of bone ingrowth on the threads at 4 and 8 weeks was greater in the CS group than in the nonaugmented group (p < 0.05), although these parameters increased concomitantly with time for both groups. The CS was resorbed completely at 8 weeks without stimulating fibrous encapsulation on the screw surface. Also, the cement significantly increased the screw pull-out force and the energy to failure at 2, 4, 8, and 12 weeks after implantation, when compared with the control group (p < 0.05). These results imply that augmentation of screw fixation with CS may have the potential to decrease the risk of implant failure in osteoporotic bone.

  13. 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

  14. Stability of anterior vertebral body screws after kyphoplasty augmentation. An experimental study to compare anterior vertebral body screw fixation in soft and cured kyphoplasty cement.

    PubMed

    Linhardt, O; Lüring, C; Matussek, J; Hamberger, C; Herold, T; Plitz, W; Grifka, J

    2006-10-01

    The goal of this cadaver study was to compare the stability of anterior vertebral body screws after implantation in soft or cured kyphoplasty cement. Anterior vertebral body screws were inserted in a total of 30 thoracolumbar vertebrae of ten different human specimens: ten screws were implanted in non-augmented vertebrae (group 1), ten screws were placed in soft cement (group 2), and ten screws were placed in cured cement (group 3). The screws were then tested for biomechanical axial pullout resistance. Mean axial pullout strength was 192 N (range: 10-430 N) in group 1, 364 N (range: 65-875 N) in group 2, and 271 N (range: 35-625 N) in group 3. The paired Student's t-test demonstrated a significant difference between pullout strength of groups 1 and 2 (p= 0.0475). No significant difference was seen between pullout strength of groups 1 and 3 (p= 0.2646) and between groups 2 and 3 (p= 0.3863). We achieved a 1.9 times higher pullout strength with kyphoplasty augmentation of osteoporotic vertebrae compared with the pullout strength of non-augmented vertebrae. Implantation of anterior vertebral body screws in cured cement is a satisfactory method. With this method we found a 1.4 times higher pullout strength than non-augmented vertebrae.

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

    PubMed Central

    Akbar, Saleem; Dhar, Shabir A.

    2008-01-01

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

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

    PubMed

    Afzal, Suhail; Akbar, Saleem; Dhar, Shabir A

    2008-03-01

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

  17. Sacroiliac screw fixation: A mini review of surgical technique

    PubMed Central

    Alvis-Miranda, Hernando Raphael; Farid-Escorcia, Hector; Alcalá-Cerra, Gabriel; Castellar-Leones, Sandra Milena; Moscote-Salazar, Luis Rafael

    2014-01-01

    The sacral percutaneous fixation has many advantages but can be associated with a significant exposure to X-ray radiation. Currently, sacroiliac screw fixation represents the only minimally invasive technique to stabilize the posterior pelvic ring. It is a technique that should be used by experienced surgeons. We present a practical review of important aspects of this technique. PMID:25336831

  18. Biomechanical analysis of different types of pedicle screw augmentation: a cadaveric and synthetic bone sample study of instrumented vertebral specimens.

    PubMed

    Chao, Kuo-Hua; Lai, Yu-Shu; Chen, Wen-Chuan; Chang, Chia-Ming; McClean, Colin J; Fan, Chang-Yuan; Chang, Chia-Hao; Lin, Leou-Chyr; Cheng, Cheng-Kung

    2013-10-01

    This study aims to determine the pull-out strength, stiffness and failure pull-out energy of cement-augmented, cannulated-fenestrated pedicle screws in an osteoporotic cadaveric thoracolumbar model, and to determine, using synthetic bone samples, the extraction torques of screws pre-filled with cement and those with cement injected through perforations. Radiographs and bone mineral density measurements from 32 fresh thoracolumbar vertebrae were used to define specimen quality. Axial pull-out strength of screws was determined through mechanical testing. Mechanical pull-out strength, stiffness and energy-to-failure ratio were recorded for cement-augmented and non-cement-augmented screws. Synthetic bone simulating a human spinal bone with severe osteoporosis was used to measure the maximum extraction torque. The pull-out strength and stiffness-to-failure ratio of cement pre-filled and cement-injected screws were significantly higher than the non-cement-augmented control group. However, the cement pre-filled and cement-injected groups did not differ significantly across these values (p=0.07). The cement pre-filled group had the highest failure pull-out energy, approximately 2.8 times greater than that of the cement-injected (p<0.001), and approximately 11.5 times greater than that of the control groups (p<0.001). In the axial pull-out test, the cement-injected group had a greater maximum extraction torque than the cement pre-filled group, but was statistically insignificant (p=0.17). The initial fixation strength of cannulated screws pre-filled with cement is similar to that of cannulated screws injected with cement through perforations. This comparable strength, along with the heightened pull-out energy and reduced extraction torque, indicates that pedicle screws pre-filled with cement are superior for bone fixation over pedicle screws injected with cement. PMID:23669371

  19. Percutaneous iliosacral screw placement using image guided techniques.

    PubMed

    Tonetti, J; Carrat, L; Lavalleé, S; Pittet, L; Merloz, P; Chirossel, J P

    1998-09-01

    A computer assisted technique of iliosacral screw placement that is applicable to unstable pelvic ring fractures is proposed. The goals are to operate noninvasively with a percutaneous procedure to decrease the complications of surgical exposure and to provide greater accuracy in locating the close neurovascular structures. Preoperative computed tomographic images of the pelvis are provided and a computed tomography three-dimensional model is built. In this model, the optimal trajectories for the drilling are planned. An ultrasound based registration is performed intraoperatively. This registration is the most original part of this work. After performing the passive drilling guidance step, the surgeon places the screws. The accuracy of the ultrasound based registration is checked by comparison with a standard surface based registration at the end of the test experiment. Each screw position is verified by a computed tomographic examination. Four human anatomic specimen pelves were tested with three screw insertions for each pelvis (12 screws). All of the screws were considered to be placed correctly. The method is safe and encourages the start of clinical application. PMID:9755769

  20. The treatment of metastasis to the femoral neck using percutaneous hollow perforated screws with cement augmentation.

    PubMed

    Kang, H G; Roh, Y W; Kim, H S

    2009-08-01

    We have developed a hollow perforated cannulated screw. One or more of these was implanted percutaneously in 11 patients with an osteolytic metastasis in the femoral neck and multiple metastases elsewhere. They were supplemented by one or two additional standard 6.5 mm cannulated screws in nine patients. Polymethylmethacrylate bone cement was injected through the screw into the neck of the femur using small syringes, as in vertebroplasty. The mean amount of cement injected was 23.2 ml (17 to 30). Radiotherapy was started on the fourth post-operative day and chemotherapy, on average, was resumed a day later. Good structural stability and satisfactory relief from pain were achieved in all the patients. This technique may be useful in the palliation of metastases in the femoral neck. PMID:19651838

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

  2. 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

  3. In vitro biomechanical study of pedicle screw pull-out strength based on different screw path preparation techniques

    PubMed Central

    Moldavsky, Mark; Salloum, Kanaan; Bucklen, Brandon; Khalil, Saif; Mehta, Jwalant S

    2016-01-01

    Background: Poor screw-to-bone fixation is a clinical problem that can lead to screw loosening. Under-tapping (UT) the pedicle screw has been evaluated biomechanically in the past. The objective of the study was to determine if pedicle preparation with a sequential tapping technique will alter the screw-to-bone fixation strength using a stress relaxation testing loading protocol. Materials and Methods: Three thoracolumbar calf spines were instrumented with pedicle screws that were either probed, UT, standard-tapped (ST), or sequential tapped to prepare the pedicle screw track and a stress relaxation protocol was used to determine pull-out strength. The maximum torque required for pedicle screw insertion and pull-out strength was reported. A one-way ANOVA and Tukeys post-hoc test were used to determine statistical significance. Results: The pedicle screw insertion torques for the probed, UT, ST and sequentially tapped (SQT) techniques were 5.09 (±1.08) Nm, 5.39 (±1.61) Nm, 2.93 (±0.43) Nm, and 3.54 (±0.67) Nm, respectively. There is a significant difference between probed compared to ST (P ≤ 0.05), as well as UT compared to both ST and SQT (P ≤ 0.05). The pull-out strength for pedicle screws for the probed, UT, ST and SQT techniques was 2443 (±782) N, 2353(±918) N, 2474 (±521) N, and 2146 (±582) N, respectively, with no significant difference (P ≥ 0.05) between techniques. Conclusions: The ST technique resulted in the highest pull-out strength while the SQT technique resulted in the lowest. However, there was no significant difference in the pull-out strength for the various preparation techniques and there was no correlation between insertion torque and pull-out strength. This suggests that other factors such as bone density may have a greater influence on pull-out strength. PMID:27053808

  4. Revision characteristics of cement-augmented, cannulated-fenestrated pedicle screws in the osteoporotic vertebral body: a biomechanical in vitro investigation. Technical note.

    PubMed

    Blattert, Thomas R; Glasmacher, Stefan; Riesner, Hans-Joachim; Josten, Christoph

    2009-07-01

    In generalized osteoporosis, instrumentation with cement-augmented pedicle screws is an amplification of the therapeutic spectrum. Early clinical results are promising for both solid and cannulated screws; however, there are concerns regarding the revision characteristics of these screws, especially for the cannulated-fenestrated type with its continuous cement interconnection from the core of the screw to surrounding bone tissue. In a human cadaver model, bone mineral density (BMD) was assessed radiographically. Spinal levels T9-L4 were instrumented left unilaterally, transpedicularly by using cannulated-fenestrated pedicle screws with the dimensions 6.5 x 45 mm. Polymethylmethacrylate cement (1.5 ml) was injected through the screws into each vertebra. After polymerization of the cement, the extraction torque was recorded. For both implantation and explantation of the screws, a fluoroscope was used to guarantee correct screw and cement positioning and to observe possible co-movements-that is, any movement of the cement mass within the vertebral body upon removal of the screw. For comparison, the extraction torque of same-dimension pedicle screws was recorded in a nonosteoporotic, non-cement-augmented instrumentation. The BMD was 0.60 g/cm2, a level that corresponds to a severe grade of osteoporosis. For removal of the screws, the median and mean extraction torques were 34 and 49 +/- 44 Ncm, respectively. No co-movements of the cement mass occurred within the vertebral body. In the nonosteoporotic control, BMD was 1.38 g/cm2. The median and mean extraction torques were 123 and 124 +/- 12 Ncm, respectively. Thus, the revision characteristics of cement-augmented, cannulated-fenestrated pedicle screws are not problematic, even in cases of severe osteoporosis. The winglike cement interconnection between the screw core and surrounding bone tissue is fragile enough to break off in the event of an extraction torque and to release the screw. There is no proof to support

  5. Cortical screw support in femoral neck fractures. A radiographic analysis of 87 fractures with a new mensuration technique.

    PubMed

    Lindequist, S

    1993-06-01

    In 87 femoral neck fractures, operated on with 2 von Bahr screws and followed for up to 2 years, the positions of the fixating screws were determined with a new mensuration technique which compensates for the variations in hip rotation in routine radiographs. The union rate of the fractures was related to the position of the screws. A posterior placement of the proximal screw and an inferior placement of the distal screw in both the femoral head and neck improved the outcome substantially.

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

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

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

  7. Percutaneous Pedicle Screw Fixation with Polymethylmethacrylate Augmentation for the Treatment of Thoracolumbar Intravertebral Pseudoarthrosis Associated with Kummell's Osteonecrosis.

    PubMed

    Kim, Hyeun-Sung; Heo, Dong-Hwa

    2016-01-01

    Purpose. The purpose of our study is to evaluate the therapeutic efficacy of short-segment percutaneous pedicle screw fixation with polymethylmethacrylate (PMMA) augmentation for the treatment of osteoporotic thoracolumbar compression fracture with osteonecrosis. Methods. Osteoporotic thoracolumbar compression fractures with avascular necrosis were treated by short-segment PPF with PMMA augmentation. Eighteen were followed up for more than 2 years. The kyphotic angle, compression ratio, visual analog scale (VAS) score for back pain, and the Oswestry Disability Index (ODI) were analyzed. In addition, radiologic and clinical parameters of PPF group were compared with percutaneous vertebroplasty (PVP) group. Results. Vertebral height and kyphotic angle of the compressed vertebral bodies were significantly corrected after the operation (P < 0.05). Further, restored vertebral height was maintained during the 2 or more years of postoperative follow-up. Compared to the PVP group the postoperative compression ratio and kyphotic angle were significantly lower in the PPF group (P < 0.05). The postoperative ODI and VAS of the PVP group were significantly higher than the PPF (P < 0.05). Conclusions. According to our results, short-segment PPF with PMMA augmentation may be an effective minimally invasive treatment for osteoporosis in cases of osteoporotic vertebral compression fractures with Kummell's osteonecrosis. PMID:27595101

  8. Percutaneous Pedicle Screw Fixation with Polymethylmethacrylate Augmentation for the Treatment of Thoracolumbar Intravertebral Pseudoarthrosis Associated with Kummell's Osteonecrosis

    PubMed Central

    2016-01-01

    Purpose. The purpose of our study is to evaluate the therapeutic efficacy of short-segment percutaneous pedicle screw fixation with polymethylmethacrylate (PMMA) augmentation for the treatment of osteoporotic thoracolumbar compression fracture with osteonecrosis. Methods. Osteoporotic thoracolumbar compression fractures with avascular necrosis were treated by short-segment PPF with PMMA augmentation. Eighteen were followed up for more than 2 years. The kyphotic angle, compression ratio, visual analog scale (VAS) score for back pain, and the Oswestry Disability Index (ODI) were analyzed. In addition, radiologic and clinical parameters of PPF group were compared with percutaneous vertebroplasty (PVP) group. Results. Vertebral height and kyphotic angle of the compressed vertebral bodies were significantly corrected after the operation (P < 0.05). Further, restored vertebral height was maintained during the 2 or more years of postoperative follow-up. Compared to the PVP group the postoperative compression ratio and kyphotic angle were significantly lower in the PPF group (P < 0.05). The postoperative ODI and VAS of the PVP group were significantly higher than the PPF (P < 0.05). Conclusions. According to our results, short-segment PPF with PMMA augmentation may be an effective minimally invasive treatment for osteoporosis in cases of osteoporotic vertebral compression fractures with Kummell's osteonecrosis.

  9. Percutaneous Pedicle Screw Fixation with Polymethylmethacrylate Augmentation for the Treatment of Thoracolumbar Intravertebral Pseudoarthrosis Associated with Kummell's Osteonecrosis

    PubMed Central

    2016-01-01

    Purpose. The purpose of our study is to evaluate the therapeutic efficacy of short-segment percutaneous pedicle screw fixation with polymethylmethacrylate (PMMA) augmentation for the treatment of osteoporotic thoracolumbar compression fracture with osteonecrosis. Methods. Osteoporotic thoracolumbar compression fractures with avascular necrosis were treated by short-segment PPF with PMMA augmentation. Eighteen were followed up for more than 2 years. The kyphotic angle, compression ratio, visual analog scale (VAS) score for back pain, and the Oswestry Disability Index (ODI) were analyzed. In addition, radiologic and clinical parameters of PPF group were compared with percutaneous vertebroplasty (PVP) group. Results. Vertebral height and kyphotic angle of the compressed vertebral bodies were significantly corrected after the operation (P < 0.05). Further, restored vertebral height was maintained during the 2 or more years of postoperative follow-up. Compared to the PVP group the postoperative compression ratio and kyphotic angle were significantly lower in the PPF group (P < 0.05). The postoperative ODI and VAS of the PVP group were significantly higher than the PPF (P < 0.05). Conclusions. According to our results, short-segment PPF with PMMA augmentation may be an effective minimally invasive treatment for osteoporosis in cases of osteoporotic vertebral compression fractures with Kummell's osteonecrosis. PMID:27595101

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

    PubMed Central

    Modi, Hitesh N.; Fernandez, Harry; Yang, Jae Hyuk; Song, Hae-Ryong

    2008-01-01

    It is a retrospective analytic study of 1,009 transpedicular screws (689 thoracic and 320 lumbosacral), inserted with free-hand technique in neuromuscular scoliosis using postoperative CT scan. The aim of paper was to determine the accuracy and safety of transpedicular screw placement with free-hand technique in neuromuscular scoliosis and to compare the accuracy at different levels in such population. All studies regarding accuracy and safety of pedicle screw in scoliosis represent idiopathic scoliosis using various techniques such as free-hand, navigation, image intensifier, etc., for screw insertion. Anatomies of vertebrae and pedicle are distorted in scoliosis, hence accurate and safe placement of pedicle screw is prerequisite for surgery. Between 2004 and 2006, 37 consecutive patients, average age 20 years (9–44 years), of neuromuscular scoliosis were operated with posterior pedicle screw fixation using free-hand technique. Accuracy of pedicle screws was studied on postoperative CT scan. Placement up to 2 mm medial side and 4 mm lateral side was considered within-safe zone. Of the 1,009 screws, 273 screws were displaced medially, laterally or on the anterior side showing that 73% screws (68% in thoracic and 82.5% in lumbar spine) were accurately placed within pedicle. Considering the safe zone, 93.3% (942/1009, 92.4% in thoracic and 95.3% in lumbar spine) of the screws were within the safe zone. Comparing accuracy according to severity of curve, accuracy was 75% in group 1 (curve <90°) and 69% in group 2 (curve >90°) with a safety of 94.8 and 91.2%, respectively (P = 0.35). Comparing the accuracy at different thoracic levels, it showed 67, 64 and 72% accuracy in upper, middle and lower thoracic levels with safety of 96.6, 89.2 and 93.1%, respectively, exhibiting no statistical significant difference (P = 0.17). Pedicle screw placement in neuromuscular scoliosis with free-hand technique is accurate and safe as other conditions. PMID:18830636

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

    PubMed Central

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

    2015-01-01

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

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

    PubMed

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

    2012-08-01

    In this paper, Positron Emission Particle Tracking (PEPT) techniques are utilised to track the trajectory of single particles through the mixing and conveying zones of a Twin Screw Granulator (TSG). A TSG consisting of conveying zones and mixing zones is used in this study. The mixing zones are arranged with kneading discs at an angle of 30°, 60° or 90°. Experiments were carried out using different mixing configurations with various screw speed and total mass flow rate. The PEPT data obtained were then utilised to obtain the residence time distribution (RTD) and the Peclet number in an attempt to gain some insight into the mixing of the process. The fill level of the granulator was also estimated to study the mechanism of granulation. As might be expected, it was shown that the residence time of the granulation process increases with decreasing screw speed. It also increases with increasing angle of the arrangement of kneading blocks in the mixing zones, but will decreases when powder feed rate is increased. The fill level of the mixing zone in particular increases when the screw speed decreases or when powder feed rate increases. Furthermore, the fill level of the granulator will increase when the mixing zone configuration changes from 30° to 90°. It is shown that the granulator is never fully filled, even using 90° mixer elements implying limited compaction which may explain why the granules produced are porous compared with those from a high shear mixer. Interestingly, the RTD analysis reveals that the extent of axial mixing in the mixing zone of the granulator does not change significantly for different configurations and process conditions. There is evidence of a tail in the RTD which implies some material hold up and channelling. PMID:22561951

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

    PubMed

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

    2016-02-01

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

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

    PubMed

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

    2014-05-01

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

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

    PubMed Central

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

    2015-01-01

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

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

    PubMed Central

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

    2015-01-01

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

  17. 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: ① C-1 lateral mass and C-2 pedicle screw fixation (Harms technique); ② C-1 lateral mass and unilateral C-2 pedicle screw fixation combined with ipsilateral laminar screw fixation; ③ Unilateral C-1lateral mass combined with ipsilateral C-1 posterior arch, and C-2 pedicle screw fixation; and ④ 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

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

    PubMed Central

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

    2014-01-01

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

  19. Gluteal tendon repair augmented with a synthetic ligament: surgical technique and a case series.

    PubMed

    Bucher, Thomas A; Darcy, Peter; Ebert, Jay R; Smith, Anne; Janes, Greg

    2014-01-01

    We describe an augmented surgical repair technique for gluteus minimus and medius tears, along with a supportive case series. A consecutive series of 22 patients presenting with clinical and radiological findings consistent with hip abductor tears, who had undergone failed prior conservative treatments, were prospectively recruited. Patients underwent open bursectomy, Y-iliotibial release, debridement of the diseased tendon, decortication of the trochanteric foot-plate and reattachment augmented with a LARS ligament through a trans-osseous tunnel, together with suture anchors. All patients were assessed pre- and postoperatively to 12 months with the Oxford Hip Score (OHS), the Short-Form Health Survey (SF-36) and a Visual Analogue Pain Scale (VAS), while a satisfaction scale was employed at 12 months. A statistically significant improvement (p<0.05) was observed for all patient reported outcome measures, while all patients were at least 'satisfied' with the procedure at 12 months. One patient reported some lateral hip discomfort at 10 months, and removal of the LARS interference screw provided immediate relief. One patient had a urological catheter-related complication. With no other complications and no clinical failures of the repair, we believe the technique to be safe and reliable, whilst reducing the incidence of re-tears as reported in the existing literature. PMID:24186680

  20. Computer-vision-based registration techniques for augmented reality

    NASA Astrophysics Data System (ADS)

    Hoff, William A.; Nguyen, Khoi; Lyon, Torsten

    1996-10-01

    Augmented reality is a term used to describe systems in which computer-generated information is superimposed on top of the real world; for example, through the use of a see- through head-mounted display. A human user of such a system could still see and interact with the real world, but have valuable additional information, such as descriptions of important features or instructions for performing physical tasks, superimposed on the world. For example, the computer could identify and overlay them with graphic outlines, labels, and schematics. The graphics are registered to the real-world objects and appear to be 'painted' onto those objects. Augmented reality systems can be used to make productivity aids for tasks such as inspection, manufacturing, and navigation. One of the most critical requirements for augmented reality is to recognize and locate real-world objects with respect to the person's head. Accurate registration is necessary in order to overlay graphics accurately on top of the real-world objects. At the Colorado School of Mines, we have developed a prototype augmented reality system that uses head-mounted cameras and computer vision techniques to accurately register the head to the scene. The current system locates and tracks a set of pre-placed passive fiducial targets placed on the real-world objects. The system computes the pose of the objects and displays graphics overlays using a see-through head-mounted display. This paper describes the architecture of the system and outlines the computer vision techniques used.

  1. Biomechanical Comparison of Pedicle Screw Augmented with Different Volumes of Polymethylmethacrylate in Osteoporotic and Severely Osteoporotic Synthetic Bone Blocks in Primary Implantation: An Experimental Study

    PubMed Central

    Liu, Da; Zhang, Xiao-jun; Liao, Dong-fa; Zhou, Jiang-jun; Li, Zhi-qiang; Zhang, Bo; Wang, Cai-ru; Lei, Wei; Kang, Xia; Zheng, Wei

    2016-01-01

    This study was designed to compare screw stabilities augmented with different volumes of PMMA and analyze relationship between screw stability and volume of PMMA and optimum volume of PMMA in different bone condition. Osteoporotic and severely osteoporotic synthetic bone blocks were divided into groups A0-A5 and B0-B5, respectively. Different volumes of PMMA were injected in groups A0 to A5 and B0 to B5. Axial pullout tests were performed and Fmax was measured. Fmax in groups A1-A5 were all significantly higher than group A0. Except between groups A1 and A2, A3 and A4, and A4 and A5, there were significant differences on Fmax between any other two groups. Fmax in groups B1-B5 were all significantly higher than group B0. Except between groups B1 and B2, B2 and B3, and B4 and B5, there were significant differences on Fmax between any other two groups. There was significantly positive correlation between Fmax and volume of PMMA in osteoporotic and severely osteoporotic blocks. PMMA can significantly enhance pedicle screw stability in osteoporosis and severe osteoporosis. There were positive correlations between screw stability and volume of PMMA. In this study, injection of 3 mL and 4 mL PMMA was preferred in osteoporotic and severely osteoporotic blocks, respectively. PMID:26885525

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

    PubMed

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

    2016-01-01

    Limited retrievability is a major disadvantage of cement-retained implant restorations. Despite great progress in locating the abutment screw within crowns, the existing techniques are based on prior data or prefabricated devices and require significant work. This study introduces a new procedure for fabricating a guide template to drill a screw access hole using a double-step superimposition technique that incorporates intraoral optical scanning, cone beam computed tomography, and dental design software. The double-step superimposition technique with computer-aided design/computer-assisted manufacturing technology can enhance the convenience and accuracy of drilling the screw-access hole. PMID:27479352

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

    PubMed Central

    İnceoğlu, 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

  4. Flight experience with a remotely augmented vehicle flight test technique

    NASA Technical Reports Server (NTRS)

    Petersen, K. L.

    1981-01-01

    A flight technique which uses the remotely augmented vehicle (RAV) concept is developed to flight test advanced control law concepts. The design, development and flight test validation of a RAV system mechanized on a digital fly-by-wire aircraft are described, and future applications are discussed. Flight experiments investigate complete inner loop, low sample rate, and adaptive control system mechanisms. The technique, which utilizes a ground-based FORTRAN programmable digital computer and up and down telemetry links is found to provide the flexibility necessary to effectively investigate alternate control law mechanisms in flight.

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

    PubMed

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

    2016-06-01

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

  6. A laboratory investigation to assess the influence of cement augmentation of screw and plate fixation in a simulation of distal femoral fracture of osteoporotic and non-osteoporotic bone.

    PubMed

    Wähnert, D; Lange, J H; Schulze, M; Gehweiler, D; Kösters, C; Raschke, M J

    2013-10-01

    The augmentation of fixation with bone cement is increasingly being used in the treatment of severe osteoporotic fractures. We investigated the influence of bone quality on the mechanics of augmentation of plate fixation in a distal femoral fracture model (AO 33 A3 type). Eight osteoporotic and eight non-osteoporotic femoral models were randomly assigned to either an augmented or a non-augmented group. Fixation was performed using a locking compression plate. In the augmented group additionally 1 ml of bone cement was injected into the screw hole before insertion of the screw. Biomechanical testing was performed in axial sinusoidal loading. Augmentation significantly reduced the cut-out distance in the osteoporotic models by about 67% (non-augmented mean 0.30 mm (sd 0.08) vs augmented 0.13 mm (sd 0.06); p = 0.017). There was no statistical reduction in this distance following augmentation in the non-osteoporotic models (non-augmented mean 0.15 mm (sd 0.02) vs augmented 0.15 mm (sd 0.07); p = 0.915). In the osteoporotic models, augmentation significantly increased stability (p = 0.017). PMID:24078541

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

    PubMed Central

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

    2016-01-01

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

  8. 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

  9. Biomechanical Evaluation of Two Arthroscopic Biceps Tenodesis Techniques: Proximal Interference Screw and Modified Percutaneous Intra-Articular Transtendon.

    PubMed

    Hartigan, David E; Beran, Matthew C; Fleischli, James E; D'Alessandro, Donald F; Zheng, Naiquan Nigel

    2016-01-01

    The percutaneous intra-articular transtendon (PITT) technique has recently been shown to have results comparable to those of more accepted techniques. Its mode of failure was secondary to the suture pulling through the tendon substance. A modification was made whereby the tendon is locked within the suture configuration in an attempt to avoid pullout. We compared this new technique with a well-accepted technique of all-arthroscopic interference screw. In each of 8 pairs of cadaveric shoulders (mean age, 55 years; range, 51-59 years), one shoulder was randomized to be treated with either modified PITT or interference screw (Biceptor; Smith & Nephew) biceps tenodesis, and the other shoulder was treated with the other technique. The tendons were preloaded at 10 N and then cycled at 0 to 50 N for 100 cycles at 1 Hz. Load to failure was calculated at a rate of 1.0 mm per second until peak load was observed. Mean (SD) ultimate load to failure was 157 (41) N for the modified PITT technique and 107 (29) N for the interference screw technique (P = .003). In 7 of 8 specimens, the interference screw technique failed at the junction of the tendon, the screw, and the bone interface. In 7 of 8 specimens, the PITT technique failed by the tendon slipping through the suture or pulling through transverse ligament/rotator interval tissue. Study results showed the modified PITT technique was a biomechanically superior construct. PMID:27552463

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

    PubMed

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

    2016-03-01

    Although conventional C1 laminectomy is the gold standard for decompression at the atlas, it provides little space for the bone graft to fuse. The fusion area can be extended cranially up to the occipital bone, but it requires sacrificing the function of the craniocervical junction. To date, no reports have focused on surgical techniques for successful decompression and fusion without disruption of the posterior C1 arch while providing enough room for the bone graft to fuse. This study introduces a new technique for C1-C2 fusion and C1 double-door laminoplasty in patients with C1-C2 instability, canal stenosis, and cervical spondylotic myelopathy. A 66-year-old man who had undergone C1-C2 fusion at a local clinic 2 years earlier visited our hospital due to progressive myelopathy. A preoperative computed tomography (CT) scan showed the tip of the odontoid process, extending into the spinal canal. On the axial view of T2-weighted magnetic resonance images, the tip of the odontoid process significantly compressed the spinal cord on the left side. The atlantodental interval was 7 mm on radiography; however, C1-C2 instability was not evident on flexion-extension X-rays due to the previous screw fixation. The patient underwent C1-C2 decompression and fusion surgery with our new surgical technique. The segmental screws were repositioned at C1 and C2, and we performed C1 double-door laminoplasty augmented with an allograft spacer and a titanium miniplate. A marked reduction was seen at postoperative radiograph and CT scan. Neurologic symptoms were relieved dramatically after surgery without any discomfort. No complications were noted. We introduced a new surgical technique that allows bone grafting, decompression, and fusion to be performed without disruption of the posterior C1 arch in the event of C1-C2 canal stenosis combined with instability. This technique may be indicated for other conditions that cause instability and stenosis at the C1-C2 area. PMID:26689563

  11. 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

  12. An Arthroscopic Technique for Long Head of Biceps Tenodesis With Double Knotless Screw

    PubMed Central

    Su, Wei-Ren; Ling, Florence Y.; Hong, Chih-Kai; Chang, Chih-Hsun; Chung, Kai-Chen; Jou, I-Ming

    2015-01-01

    Tenodesis of the long head of the biceps (LHB) is a frequently performed procedure during shoulder arthroscopy for the treatment of degenerative, traumatic, or inflammatory lesions of the LHB tendon. Arthroscopic techniques for LHB tenodesis using knotless screw techniques offer the advantage of circumventing the need for arthroscopic knot tying. In 2012 Song and Williams described a novel tenodesis technique that does not require any knot-tying procedures by using a knotless anchor. However, a single-anchor configuration may not offer adequate stabilization of the LHB tendon. Therefore we propose a modified method that uses a double knotless anchor that offers advantages over the single knotless anchor, such as an increase in the contact area between the tendon and bone to facilitate tendon-to-bone healing and strengthening of the tenodesis construct. PMID:26759780

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

    SciTech Connect

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

    2010-01-01

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

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

    PubMed

    McRory, M Eric; Cagna, David R

    2014-06-01

    This article presents an intraoral technique for fabricating single screw-retained implant-supported interim crowns immediately after surgical implant placement in extraction sites. The technique may be used with any implant system that provides a provisional abutment or an open-tray impression coping that can be modified for use as a provisional abutment. PMID:24461941

  15. A Fluoroscopy-Free Technique for Percutaneous Screw Positioning During Arthroscopic Treatment of Depression Tibial Plateau Fractures.

    PubMed

    Thaunat, Mathieu; Camelo Barbosa, Nuno; Tuteja, Sanesh; Jan, Nicolas; Fayard, Jean Marie; Sonnery-Cottet, Bertrand

    2016-06-01

    This article aims to describe a simple and reliable technique that helps in positioning the cannulated percutaneous screws during fixation of depression-type tibial plateau fractures. After fracture reduction under arthroscopic control, an outside-in anterior cruciate ligament femoral guide is introduced through the tibial cortical metaphyseal window and positioned under endoscopic control just underneath the elevated fragment. When proper height is achieved, a guide pin is drilled from lateral to medial through the sleeve, 1 to 2 cm distal to the articular surface of the depressed fragment. The cannulated screw can then be introduced under endoscopic control, without fluoroscopic assistance, just under the previously elevated joint surface. This technique ensures optimal placement of the cannulated screw in the middle of the bony tunnel to obtain optimal subchondral bone support during fixation of the depressed tibial plateau fracture. PMID:27656370

  16. Technique and nuances of an S-2 alar iliac screw for lumbosacral fixation in patients with transitional and normal anatomy.

    PubMed

    Ohya, Junichi; Vogel, Todd D; Dhall, Sanjay S; Berven, Sigurd; Mummaneni, Praveen V

    2016-07-01

    S-2 alar iliac (S2AI) screw fixation has recently been recognized as a useful technique for pelvic fixation. The authors demonstrate two cases where S2AI fixation was indicated: one case was a sacral insufficiency fracture following a long-segment fusion in a patient with a transitional S-1 vertebra; the other case involved pseudarthrosis following lumbosacral fixation. S2AI screws offer rigid fixation, low profile, and allow easy connection to the lumbosacral rod. The authors describe and demonstrate the surgical technique and nuances for the S2AI screw in a case with transitional S-1 anatomy and in a case with normal S-1 anatomy. The video can be found here: https://youtu.be/Sj21lk13_aw . PMID:27364429

  17. Percutaneous Transpedicular Interbody Fusion Technique in Percutaneous Pedicle Screw Stabilization for Pseudoarthrosis Following Pyogenic Spondylitis.

    PubMed

    Ikuta, Ko; Masuda, Keigo; Yonekura, Yutaka; Kitamura, Takahiro; Senba, Hideyuki; Shidahara, Satoshi

    2016-04-01

    This report introduces a percutaneous transpedicular interbody fusion (PTPIF) technique in posterior stabilization using percutaneous pedicle screws (PPSs). An 81-year-old man presented with pseudoarthrosis following pyogenic spondylitis 15 months before. Although no relapse of infection was found, he complained of obstinate low back pain and mild neurological symptoms. Radiological evaluations showed a pseudoarthrosis following pyogenic spondylitis at T11-12. Posterior stabilization using PPSs from Th9 to L2 and concomitant PTPIF using autologous iliac bone graft at T11-12 were performed. Low back pain and neurological symptoms were immediately improved after surgery. A solid interbody fusion at T11-12 was completed 9 months after surgery. The patient had no restriction of daily activity and could play golf at one year after surgery. PTPIF might be a useful option for perform segmental fusion in posterior stabilization using PPSs. PMID:27114777

  18. Interference screw fixation and short harvest using flexor digitorum longus (FDL) transfer for posterior tibial tendon dysfunction: a technique.

    PubMed

    Bussewitz, Bradly W; Hyer, Christopher F

    2010-01-01

    Posterior tibial tendon dysfunction is a common clinical entity treated by foot and ankle specialists, and numerous surgical treatments are available to the modern foot and ankle surgeon. Fixation methods are constantly evolving as new products are developed and new uses for existing products are attempted. Interference screw fixation is the gold standard fixation for tendon autograft and allograft in orthopedic sports medicine. The technique that we describe in this article uses a less extensive harvest of the flexor digitorum longus tendon and a sound fixation method using an interference screw positioned in the tarsal navicular. PMID:20797592

  19. Transpalatal screw traction: a simple technique for the management of sagittal fractures of the maxilla and palate.

    PubMed

    Ma, D; Guo, X; Yao, H; Chen, J

    2014-12-01

    Sagittal fractures of the maxilla and palate are uncommon in clinical practice. Current methods for the management of such fractures have advantages and limitations. The authors present the simple and practical technique of bilateral transpalatal screw traction to manage this fracture type.

  20. A Technique Elucidating the Retrieval of an Adhered Cover Screw in a Dental Implant – A Case Report

    PubMed Central

    Bhuvaneswarri, J.; Chandrasekaran, S.C.

    2013-01-01

    Dental implants have become one of the most popular and rapidly growing techniques for replacing missing teeth. While their predictability, functionality, and durability make them an attractive option for patients and clinicians alike, complications can arise at any stage from patient assessment to maintenance of therapy. Failure of dental implants not only occurs due to biological factors, like unsuccessful osseointegration or peri-implantitis but may also occur due to technical complications like, failures of implant-supported restorations relating those from the implant components, and those relating to the prosthesis. Technical problems related to implant components include abutment screw fractures and cover screw fractures. In this case report we have elucidated an adhered cover screw in an implant. PMID:24392429

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

    PubMed Central

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

    2015-01-01

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

  2. Techniques for augmentation of exogenous DNA uptake by ovine spermatozoa.

    PubMed

    Hoseini Pajooh, K; Tajik, P; Karimipoor, M; Behdani, M

    2016-01-01

    Sperm mediated gene transfer can be an inexpensive and simple method in animal transgenesis; however its efficiency is poor, mainly due to the spermatozoa's lesser uptake of exogenous DNA. In the present study, the effects of lipofection and other augmentation techniques, such as sperm freezing and spermatozoa treatment with triton X100 and DMSO, on exogenous DNA uptake by sheep spermatozoa and motility of sperms with plasmid uptake were evaluated. In the first experiment, ram sperms were incubated with a complex of rhodamine labeled plasmid (p-EGFP) and Lipofectamine 2000(TM). In the second, spermatozoa were treated with Triton X-100(TM) or DMSO or were frozen without cryoprotectant. The results indicated that there was no significant difference (P<0.05) in the transfection rates and in the uptake intensity of lipofected sperms with 300 and 600 ng of plasmid in comparison with control group, i.e. transfected without lipofectamine. Furthermore, lipofection could not improve sperm motility during true plasmid uptake. Almost all of triton X100 treated and frozen-thawed spermatozoa had absorbed foreign DNA, though all were immotile. In spermatozoa treated with 0.1% DMSO, plasmid absorption rate (69.40%) was significantly higher (P<0.05) than untreated spermatozoa (57.80%), but sperm motility was not significantly different from control group. In conclusion, lipofectamine(®) 2000 could neither improve transfection rate, nor support motility in transfected sperms. The methods inducing membrane disruption like, freeze-thaw and triton X100 treatment, can be used in ICSI-sperm mediated gene transfer without the need for sperm selection, provided that they cause no damage to sperm nucleus. PMID:27656225

  3. Techniques for augmentation of exogenous DNA uptake by ovine spermatozoa

    PubMed Central

    Hoseini Pajooh, K.; Tajik, P.; Karimipoor, M.; Behdani, M.

    2016-01-01

    Sperm mediated gene transfer can be an inexpensive and simple method in animal transgenesis; however its efficiency is poor, mainly due to the spermatozoa’s lesser uptake of exogenous DNA. In the present study, the effects of lipofection and other augmentation techniques, such as sperm freezing and spermatozoa treatment with triton X100 and DMSO, on exogenous DNA uptake by sheep spermatozoa and motility of sperms with plasmid uptake were evaluated. In the first experiment, ram sperms were incubated with a complex of rhodamine labeled plasmid (p-EGFP) and Lipofectamine 2000TM. In the second, spermatozoa were treated with Triton X-100TM or DMSO or were frozen without cryoprotectant. The results indicated that there was no significant difference (P<0.05) in the transfection rates and in the uptake intensity of lipofected sperms with 300 and 600 ng of plasmid in comparison with control group, i.e. transfected without lipofectamine. Furthermore, lipofection could not improve sperm motility during true plasmid uptake. Almost all of triton X100 treated and frozen-thawed spermatozoa had absorbed foreign DNA, though all were immotile. In spermatozoa treated with 0.1% DMSO, plasmid absorption rate (69.40%) was significantly higher (P<0.05) than untreated spermatozoa (57.80%), but sperm motility was not significantly different from control group. In conclusion, lipofectamine® 2000 could neither improve transfection rate, nor support motility in transfected sperms. The methods inducing membrane disruption like, freeze-thaw and triton X100 treatment, can be used in ICSI-sperm mediated gene transfer without the need for sperm selection, provided that they cause no damage to sperm nucleus. PMID:27656225

  4. Techniques for augmentation of exogenous DNA uptake by ovine spermatozoa

    PubMed Central

    Hoseini Pajooh, K.; Tajik, P.; Karimipoor, M.; Behdani, M.

    2016-01-01

    Sperm mediated gene transfer can be an inexpensive and simple method in animal transgenesis; however its efficiency is poor, mainly due to the spermatozoa’s lesser uptake of exogenous DNA. In the present study, the effects of lipofection and other augmentation techniques, such as sperm freezing and spermatozoa treatment with triton X100 and DMSO, on exogenous DNA uptake by sheep spermatozoa and motility of sperms with plasmid uptake were evaluated. In the first experiment, ram sperms were incubated with a complex of rhodamine labeled plasmid (p-EGFP) and Lipofectamine 2000TM. In the second, spermatozoa were treated with Triton X-100TM or DMSO or were frozen without cryoprotectant. The results indicated that there was no significant difference (P<0.05) in the transfection rates and in the uptake intensity of lipofected sperms with 300 and 600 ng of plasmid in comparison with control group, i.e. transfected without lipofectamine. Furthermore, lipofection could not improve sperm motility during true plasmid uptake. Almost all of triton X100 treated and frozen-thawed spermatozoa had absorbed foreign DNA, though all were immotile. In spermatozoa treated with 0.1% DMSO, plasmid absorption rate (69.40%) was significantly higher (P<0.05) than untreated spermatozoa (57.80%), but sperm motility was not significantly different from control group. In conclusion, lipofectamine® 2000 could neither improve transfection rate, nor support motility in transfected sperms. The methods inducing membrane disruption like, freeze-thaw and triton X100 treatment, can be used in ICSI-sperm mediated gene transfer without the need for sperm selection, provided that they cause no damage to sperm nucleus.

  5. Detecting Syntactic Ambiguity: Three Augmented Transition Network Techniques.

    ERIC Educational Resources Information Center

    Herman, L. Russell, Jr.

    When a grammar is expressed in augmented transition network (ATN) form, the problem of detecting syntactic ambuguity reduces to finding all possible paths through the ATNs. Each successfully terminating path through the ATN generates an acceptable parsing of the input string. Two ATN forms, minimal-node and pseudo-tree, are described along with…

  6. Comparison between percutaneous fluoroscopic-guided and conventional open pedicle screw placement techniques for the thoracic spine: a safety evaluation in human cadavers.

    PubMed

    Kwan, M K; Chiu, C K; Lee, C K; Chan, C Y W

    2015-11-01

    Percutaneous placement of pedicle screws is a well-established technique, however, no studies have compared percutaneous and open placement of screws in the thoracic spine. The aim of this cadaveric study was to compare the accuracy and safety of these techniques at the thoracic spinal level. A total of 288 screws were inserted in 16 (eight cadavers, 144 screws in percutaneous and eight cadavers, 144 screws in open). Pedicle perforations and fractures were documented subsequent to wide laminectomy followed by skeletalisation of the vertebrae. The perforations were classified as grade 0: no perforation, grade 1: < 2 mm perforation, grade 2: 2 mm to 4 mm perforation and grade 3: > 4 mm perforation. In the percutaneous group, the perforation rate was 11.1% with 15 (10.4%) grade 1 and one (0.7%) grade 2 perforations. In the open group, the perforation rate was 8.3% (12 screws) and all were grade 1. This difference was not significant (p = 0.45). There were 19 (13.2%) pedicle fractures in the percutaneous group and 21 (14.6%) in the open group (p = 0.73). In summary, the safety of percutaneous fluoroscopy-guided pedicle screw placement in the thoracic spine between T4 and T12 is similar to that of the conventional open technique.

  7. A new technique for retaining double crowns on implants via custom-positioned vertical screws.

    PubMed

    Frisch, Eberhard; Ziebolz, Dirk; Ratka-Krüger, Petra; Rinke, Sven

    2014-01-01

    This report describes the use of custom-positioned vertical screws (CVS) to attach primary telescopic crowns to implant abutments. In a private practice setting, 37 patients with 40 double crown-retained implant overdentures (IODs) with a clearance fit (Marburg double crowns) were followed. All primary crowns on the 120 implant abutments were retained using CVS. After a mean followup period of 3.55 ± 1.37 years (range: 1.5 to 6.3 years), one abutment screwloosening incident was reported (incidence: 0.08%). No loosening of any of the screw-retained primary crowns occurred. CVS may represent a viable fixation concept for IODs.

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

    PubMed Central

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

    2016-01-01

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

  9. A technique for indirect fabrication of an implant-supported, screw-retained, fixed provisional restoration in the esthetic zone.

    PubMed

    Lin, Wei-Shao; Ercoli, Carlo

    2009-12-01

    This article describes an alternative technique for the fabrication of an implant-supported, screw-retained, fixed provisional restoration in the esthetic zone. After an implant-level impression is made with a polyether impression material, the provisional restoration is fabricated indirectly. This technique is easy, saves time, and has economic advantages, while maintaining color stability and esthetic properties for the provisional restoration. It may be contraindicated for severely misaligned implants that require extensive reduction of the implant temporary abutments and denture teeth laminates.

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

    PubMed Central

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

    2014-01-01

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

  11. Injectable Filler Techniques for Facial Rejuvenation, Volumization, and Augmentation.

    PubMed

    Bass, Lawrence S

    2015-11-01

    Multiple fillers are available: various hyaluronic acid products, calcium hydroxylapatite, and a few others that are biocompatible with good duration and a variety of mechanical properties allowing intradermal, subdermal, and supraperiosteal injection. Facial features can be reshaped with great control using these fillers. Aging changes, including facial volume loss, can be well-corrected. These treatments have become a mainstay of rejuvenation in the early facial aging patient. Injection technique is critical to obtaining excellent results. Threading, fanning, cross-hatching, bleb, and pillar techniques must be mastered. Technical execution can only measure up to, but not exceed, the quality of the aesthetic analysis.

  12. Improving IRT Parameter Estimates with Small Sample Sizes: Evaluating the Efficacy of a New Data Augmentation Technique

    ERIC Educational Resources Information Center

    Foley, Brett Patrick

    2010-01-01

    The 3PL model is a flexible and widely used tool in assessment. However, it suffers from limitations due to its need for large sample sizes. This study introduces and evaluates the efficacy of a new sample size augmentation technique called Duplicate, Erase, and Replace (DupER) Augmentation through a simulation study. Data are augmented using…

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

    PubMed

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

    2015-12-01

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

  14. Arthroscopic technique for patch augmentation of rotator cuff repairs.

    PubMed

    Labbé, Marc R

    2006-10-01

    The patient is placed in the lateral position, and an arthroscopic cuff repair is performed according to standard techniques. The line of repair is usually in the shape of a "T" or an "L." The repair is viewed through the lateral portal, with fluid inflow through the scope. Mattress sutures are placed in the anterior and posterior portions of the cuff, with respect to the line of repair, just medial to the most medial point of the tear. The sutures are placed in accordance with margin convergence suture passing methods. Next, 2 double-stranded suture anchors are placed into the lateral aspect of the greater tuberosity, which can be used to secure the anterior and posterior portions of the rotator cuff as well as the patch. The cuff sutures are tied first; then, the patch is addressed. The graft is sized by placement of a ruled probe or similar device into the subacromial space. The length of each side of the "rectangle" is measured to obtain the dimensions of the patch. The patch is then cut to fit the measurements. If the patch material is elastic, a slightly smaller than measured graft is cut to provide tension on the repair. The arthroscope is then moved to the posterior portal, and a large (8 mm) cannula, with a dam, is placed into the lateral portal. All sutures are brought out of the lateral cannula, and corresponding ends of each suture are held together in a clamp. The sutures are placed in their respective orientations once outside the cannula (e.g., anterior-medial, anterior-lateral), covering all 4 quadrants. Care is taken to ensure that the sutures have no twists and are not wrapped around one another. The sutures are passed through the graft, in mattress fashion, with a free needle, in their respective corners and clamped again. The graft is then grasped with a small locking grasper on its medial edge and is passed through the cannula into the subacromial space. The clamps holding the sutures are then gently pulled to remove the slack. A smaller (5 mm

  15. Biplane double-supported screw fixation (F-technique): a method of screw fixation at osteoporotic fractures of the femoral neck.

    PubMed

    Filipov, Orlin

    2011-10-01

    The present work introduces a method of screw fixation of femoral neck fractures in the presence of osteoporosis, according to an original concept of the establishment of two supporting points for the implants and their biplane positioning in the femoral neck and head. The provision of two steady supporting points for the implants and the highly increased (obtuse) angle at which they are positioned allow the body weight to be transferred successfully from the head fragment onto the diaphysis, thanks to the strength of the screws, with the patient's bone quality being of least importance. The position of the screws allows them to slide under stress with a minimal risk of displacement. The method was developed in search of a solution for those patients for whom primary arthroplasty is contraindicated. The method has been analysed in relation to biomechanics and statics. For the first time, a new function is applied to a screw fixation-the implant is presented as a simple beam with an overhanging end.

  16. 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

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

    PubMed Central

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

    2016-01-01

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

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

    PubMed Central

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

    2011-01-01

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

  19. Soft tissue augmentation in skin of color: market growth, available fillers, and successful techniques.

    PubMed

    Burgess, Cheryl M

    2007-01-01

    In recent years, people of color have become an increasingly important market force for the cosmetics industry. Product lines have been expanded to accommodate a broader spectrum of skin colors and marketing strategies have been specialized in order to target specific ethnic populations. In addition, it is predicted that people with pigmented skin will eventually comprise a majority of the domestic and international population during the 21st century. Not surprisingly, people of color are increasingly seeking out products and procedures to fight the effects of aging, including an increase in surgical and nonsurgical cosmetic procedures. Among nonsurgical procedures, soft tissue augmentation has experienced dramatic growth. Today, clinicians are performing more and more of these procedures in people of color. As a result of these shifts in the cosmetics industry, clinicians performing soft tissue augmentation require increased expertise in the treatment of ethnic skin. This article reviews the important differences that exist between the appearance of the aging faces of Caucasians and people of color. In addition, soft tissue augmentation strategies and injection techniques that are specific to skin of color are discussed.

  20. Stereotactic atlantoaxial transarticular screw fixation.

    PubMed

    Laherty, R W; Kahler, R J; Walker, D G; Tomlinson, F H

    2005-01-01

    Atlantoaxial stabilisation can be performed using a variety of surgical techniques. Developments in spinal instrumentation and stereotactic technology have been incorporated into these procedures. We have recently adopted frameless stereotaxy to assist in such operations. A retrospective study of patients treated by the authors and using frameless stereotaxy from 2001 to 2002 was performed. Each patient underwent pre-operative fine-cut CT in the position of fixation. Using these images, screw trajectory was planned. Stereotaxis and fluoroscopy was utilised during fixation. A post-operative CT was performed. There were nine patients. Bilateral screw placement was achieved in eight. In the remaining case stereotactic planning predicted the single screw fixation. There were no post-operative complications. Post-operative CT showed screw placement corresponding to the planned trajectory in all 17 screws. Stabilisation was achieved in all. Stereotactic atlantoaxial screw fixation is an accessible, safe and accurate method for the management of C1-2 instability. PMID:15639416

  1. Comparison of the Mechanical Characteristics of a Universal Small Biplane Plating Technique Without Compression Screw and Single Anatomic Plate With Compression Screw.

    PubMed

    Dayton, Paul; Ferguson, Joe; Hatch, Daniel; Santrock, Robert; Scanlan, Sean; Smith, Bret

    2016-01-01

    To better understand the mechanical characteristics of biplane locked plating in small bone fixation, the present study compared the stability under cyclic cantilever loading of a 2-plate locked biplane (BPP) construct without interfragmentary compression with that of a single-plate locked construct with an additional interfragmentary screw (SPS) using surrogate bone models simulating Lapidus arthrodesis. In static ultimate plantar bending, the BPP construct failed at significantly greater load than did the SPS construct (556.2 ± 37.1 N versus 241.6 ± 6.3 N, p = .007). For cyclic failure testing in plantar bending at a 180-N starting load, the BPP construct failed at a significantly greater number of cycles (158,322 ± 50,609 versus 13,718 ± 10,471 cycles) and failure load (242.5 ± 25.0 N versus 180.0 ± 0.0 N) than the SPS construct (p = .002). For cyclic failure testing in plantar bending at a 120-N starting load, the results were not significantly different between the BPP and SPS constructs for the number of cycles (207,646 ± 45,253 versus 159,334 ± 69,430) or failure load (205.0 ± 22.4 N versus 185.0 ± 33.5 N; p = .300). For cyclic testing with 90° offset loading (i.e., medial to lateral bending) at a 120-N starting load, all 5 BPP constructs (tension side) and 2 of the 5 SPS constructs reached 250,000 cycles without failure. Overall, the present study found the BPP construct to have superior or equivalent stability in multiplanar orientations of force application in both static and fatigue testing. Thus, the concept of biplane locked plating, using 2 low profile plates and unicortical screw insertion, shows promise in small bone fixation, because it provides consistent stability in multiplanar orientations, making it universally adaptable to many clinical situations.

  2. The tower technique and vertical supraperiosteal depot technique: novel vertical injection techniques for volume-efficient subcutaneous tissue support and volumetric augmentation.

    PubMed

    Sattler, Gerhard

    2012-08-01

    A 55-year-old Caucasian female with a past history of face-lifting surgery presented with early signs of soft tissue elastosis, volumetric deficiency in the periocular region, the nasolabial folds, the lips, and the lower face. Hyaluronic acid (HA) filler injections were performed with two novel vertical injection techniques that support and tense the subcutaneous connective tissue--the Tower Technique (TT) and the Vertical Supraperiosteal Depot Technique (VSDT). Vertical injection techniques are a volume-efficient means of delivering excellent, long-lasting results and patient satisfaction with minimal recovery time and are appropriate for volumetric augmentation even in patients who have subdermal fibrosis due to previous facial surgery.

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

    PubMed

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

    2016-01-01

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

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

    PubMed Central

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

    2016-01-01

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

  5. 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.

  6. Augmentation vs Nonaugmentation Techniques for Open Repairs of Achilles Tendon Ruptures with Early Functional Treatment: A Prospective Randomized Study.

    PubMed

    Tezeren, Gündüz; Kuru, Ilhami

    2006-01-01

    A prospective randomized study was conducted in order to compare augmentation technique versus nonaugmentation technique, followed by early functional postoperative treatment, for operative repair of Achilles tendon ruptures. Twenty-four consecutive patients were assigned to two groups. Group I included 12 patients treated with Lindholm augmentation technique, whereas group II included 12 patients treated with modified Kessler end-to-end repair. Thereafter, these patients had postoperative management with a below-knee-cast for three weeks. The physioteraphy was initiated immediately after the cast was removed. Full weight bearing was allowed after five weeks postoperatively in the both groups. Two patients had reruptures in group II, whereas group I had prolonged operative time significantly. The patients with reruptures underwent reoperations and at the most final follow-up, it was observed that they could not resume to sporting activities. The other objective and subjective results were similar between two groups. Because of quite high rerupture rate in the group of patients treated with nonaugmentation technique, we favor functional postoperative treatment with early ankle movement in the patients treated with augmentation technique for the management of acute rupture of the Achilles tendon. Key PointsA prospective randomized study was conducted in order to compare augmentation technique versus nonaugmentation technique, followed by early functional postoperative treatment, for operative repair of Achilles tendon ruptures.Group I included 12 patients treated with Lindholm augmentation technique, whereas group II included 12 patients treated with modified Kessler end-to-end repair.Functional postoperative treatment with early ankle movement in the patients treated with augmentation for the management of acute rupture of the Achilles tendon is recommended.

  7. Augmentation vs Nonaugmentation Techniques for Open Repairs of Achilles Tendon Ruptures with Early Functional Treatment: A Prospective Randomized Study

    PubMed Central

    Tezeren, Gündüz; Kuru, Ilhami

    2006-01-01

    A prospective randomized study was conducted in order to compare augmentation technique versus nonaugmentation technique, followed by early functional postoperative treatment, for operative repair of Achilles tendon ruptures. Twenty-four consecutive patients were assigned to two groups. Group I included 12 patients treated with Lindholm augmentation technique, whereas group II included 12 patients treated with modified Kessler end-to-end repair. Thereafter, these patients had postoperative management with a below-knee-cast for three weeks. The physioteraphy was initiated immediately after the cast was removed. Full weight bearing was allowed after five weeks postoperatively in the both groups. Two patients had reruptures in group II, whereas group I had prolonged operative time significantly. The patients with reruptures underwent reoperations and at the most final follow-up, it was observed that they could not resume to sporting activities. The other objective and subjective results were similar between two groups. Because of quite high rerupture rate in the group of patients treated with nonaugmentation technique, we favor functional postoperative treatment with early ankle movement in the patients treated with augmentation technique for the management of acute rupture of the Achilles tendon. Key Points A prospective randomized study was conducted in order to compare augmentation technique versus nonaugmentation technique, followed by early functional postoperative treatment, for operative repair of Achilles tendon ruptures. Group I included 12 patients treated with Lindholm augmentation technique, whereas group II included 12 patients treated with modified Kessler end-to-end repair. Functional postoperative treatment with early ankle movement in the patients treated with augmentation for the management of acute rupture of the Achilles tendon is recommended. PMID:24357956

  8. Knee Extensor Mechanism Repairs: Standard Suture Repair and Novel Augmentation Technique.

    PubMed

    Meyer, Zachary; Ricci, William M

    2016-08-01

    Patellar and quadriceps tendon ruptures are relatively common injuries. Rupture of the knee extensor mechanism may occur because of a forceful eccentric contraction of the quadriceps against a resisted flexed knee, though atraumatic cases have also been described. Patients at higher than normal risk for knee extensor mechanism rupture include those with systemic co-morbidities, fluoroquinolone use, and chronic tendinopathy. Early operative treatment and mobilization of acute extensor mechanism ruptures has proven effective, and numerous techniques have been described. A 46-year-old male on anastrozole therapy simultaneously ruptured his left patellar and right quadriceps tendons during a deadlift attempt. Diagnosis was by history and physical examination. Repair of both injuries was performed 5 days after injury. Described within and shown in the accompanying video is a standard technique for primary repair using Krackow stitches through the ruptured tendon that are passed through patellar bone tunnels and tied over a bone bridge. The finer points of this technique are emphasized. Also included is a technique to augment the standard repair with a figure-of-8 stitch passed through additional oblique patellar bone tunnels. The mechanical advantage of the adjuvant figure-of-8 stitch provides additional compression, which nicely reapproximates the tendon edges. PMID:27441933

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

    NASA Technical Reports Server (NTRS)

    Taylor, Brian R.; Yoo, Seung Yeun

    2011-01-01

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

  10. Combined Percutaneous Iliosacral Screw Fixation With Sacroplasty Using Resorbable Calcium Phosphate Cement for Osteoporotic Pelvic Fractures Requiring Surgery.

    PubMed

    Collinge, Cory A; Crist, Brett D

    2016-06-01

    Osteoporotic sacral fractures, including acute and chronic insufficiency fractures, are increasing in frequency and present a number of management problem. Many of these patients are treated nonoperatively with relative immobility (eg, bedrest, wheelchair, or weight-bearing restrictions) and analgesics, which likely make the osteoporotic component worse. Surgery in this patient population may be desirable in some cases with the goals of improving mobility, relieving pain, and healing in an aligned position while minimizing deformity progression. However, internal fixation of the osteoporotic pelvis can be difficult. Large unicortical lag screws are the workhorse of posterior pelvic fixation, and yet fixation in cancellous bone corridors of an osteoporotic sacrum seems unlikely to achieve optimal fixation. As a result, the operative management and clinical results of these difficult injuries may not be uniformly successful. The authors present a technique for treating osteoporotic patients with a sacral fracture when operative treatment is indicated using percutaneous screw fixation combined with screw augmentation using a resorbable calcium phosphate bone substitute or "cement." The guide wire for a 7.3-mm or other large cannulated lag screw is fully inserted along the desired bony sacral corridor as is standard. The lag screw is then inserted over the wire to the depth where cement is desired. The guide wire is removed, and the aqueous calcium phosphate is injected through the screw's cannulation. For acute fractures, cement was applied to the areas distant to the fracture; whereas in insufficiency fractures, the cement was inserted along most of the screw path. The guide wire then can be reinserted and the lag screw fully inserted. The rationale for using these 2 modalities is their synergistic effect: the cannulated screw provides typical screw fixation and also a conduit for cement application. The cement augments the lag screw's purchase in osteoporotic bone

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

    PubMed

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

    2016-01-01

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

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

    PubMed Central

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

    2016-01-01

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

  13. An injectable cementing screw for fixation in osteoporotic bone.

    PubMed

    McKoy, B E; An, Y H

    2000-01-01

    With the aging population, osteoporosis and osteoporotic fractures are becoming more prevalent. Adequate screw fixation in this type of bone is difficult. Screws are often cemented in bone to help obtain purchase. However, current cementing techniques do not ensure implant stability. Here we present a new cannulated screw with side ports that can be injected with polymethylmethacylate (PMMA) for fixation in osteoporotic bone. We compared the ultimate holding power of this cannulated screw injected with PMMA to a solid screw with the same dimensions secured with PMMA by the standard technique. Both screws were placed into embalmed and fresh frozen lumbar vertebral bodies and pulled out using a mechanical testing system. The cannulated screw had a 278% greater holding power compared to the standard screw (p < 0.006). The cannulated screw provided a significant increase in holding power in osteoporotic bone. This novel screw is promising for fixation in osteoporotic bone and warrants clinical evaluation.

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

    PubMed Central

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

    2012-01-01

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

  15. Tips of the trade #38. The Herbert screw in closed reduction and internal fixation of the Jones fracture.

    PubMed

    Traina, S M; McElhinney, J P

    1991-08-01

    A technique of using a cannulated Herbert screw is presented for addressing the troublesome Jones fracture. This closed intramedullary fixation technique allows early healing without many of the screw head problems encountered in the more traditional AO screw techniques.

  16. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2011-03-01

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

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

    SciTech Connect

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

    2015-08-15

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

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

    PubMed Central

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

    2015-01-01

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

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

    PubMed Central

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

    2015-01-01

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

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

    PubMed Central

    Frank, Rachel M.; Trenhaile, Scott W.

    2015-01-01

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

  2. Lip augmentation.

    PubMed

    Byrne, Patrick J; Hilger, Peter A

    2004-02-01

    Lip augmentation has become increasingly popular in recent years as a reflection of cultural trends emphasizing youth and beauty. Techniques to enhance the appearance of the lips have evolved with advances in biotechnology. An understanding of lip anatomy and aesthetics forms the basis for successful results. We outline the pertinent anatomy and aesthetics of the preoperative evaluation. A summary of various filler materials available is provided. Augmentation options include both injectable and open surgical techniques. The procedures and materials currently favored by the authors are described in greater detail.

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

    PubMed

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

    2016-06-01

    Study Design Retrospective comparative study. Objective To evaluate the accuracy of percutaneous pedicle screw (PPS) placement and intraoperative imaging time using dual fluoroscopy units and their differences between surgeons with more versus less experience. Methods One hundred sixty-one patients who underwent lumbar fusion surgery were divided into two groups, A (n = 74) and B (n = 87), based on the performing surgeon's experience. The accuracy of PPS placement and radiation time for PPS insertion were compared. PPSs were inserted with classic technique under the assistance of dual fluoroscopy units placed in two planes. The breach definition of PPS misplacement was based on postoperative computed tomography (grade I: no breach; grade II: <2 mm; grade III: ≤2 to <4 mm). Results Of 658 PPSs, only 21 screws were misplaced. The breach rates of groups A and B were 3.3% (grade II: 3.4%, grade III: 0%) and 3.1% (grade II: 2.6%, grade III: 0.6%; p = 0.91). One patient in grade III misplacement had a transient symptom of leg numbness. Median radiation exposure time during PPS insertion was 25 seconds and 51 seconds, respectively (p < 0.01). Conclusions Without using an expensive imaging support system, the classic technique of PPS insertion using dual fluoroscopy units in the lumbar and sacral spine is fairly accurate and provides good clinical outcomes, even among surgeons lacking experience. PMID:27190733

  4. Augmentation cheiloplasty.

    PubMed

    Ho, L C

    1994-06-01

    A technique of augmentation cheiloplasty with prior correction of a thin vermillion is described. Preserving and accentuating the natural contours of the lips is emphasised in vermillion correction and volume expansion with fat cell grafts. Thin vermillion correction, lip volume expansion and the state of fat cell grafts are reviewed.

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

    PubMed Central

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

    2016-01-01

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

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

    PubMed

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

    2015-09-01

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

  7. Recombinant human bone morphogenetic protein 2 in lateral ridge augmentation.

    PubMed

    Mehanna, Robert; Koo, Samuel; Kim, David M

    2013-01-01

    This case report describes the augmentation of severe lateral ridge defects in the maxilla and mandible using recombinant human bone morphogenetic protein 2 (rhBMP-2) on an absorbable collagen sponge (ACS). The surgical technique used tenting screws and a membrane to maintain space for the ACS. After 7 months of healing, the ridge width increased from 1 to 2 mm to 6 to 9 mm, thus allowing successful placement of dental implants. De novo bone formation through use of the surgical technique for space maintenance of rhBMP-2/ACS was demonstrated without the need for additional particulate bone grafting. PMID:23342352

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

    PubMed

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

    2014-01-01

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

  9. 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 Central

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

    2013-01-01

    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

  10. 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.

  11. Surgical treatment of the osteoporotic spine with bone cement-injectable cannulated pedicle screw fixation: technical description and preliminary application in 43 patients

    PubMed Central

    Dai, Fei; Liu, Yaoyao; Zhang, Fei; Sun, Dong; Luo, Fei; Zhang, Zehua; Xu, Jianzhong

    2015-01-01

    OBJECTIVES: To describe a new approach for the application of polymethylmethacrylate augmentation of bone cement-injectable cannulated pedicle screws. METHODS: Between June 2010 and February 2013, 43 patients with degenerative spinal disease and osteoporosis (T-score <-2.5) underwent lumbar fusion using cement-injectable cannulated pedicle screws. Clinical outcomes were evaluated using a Visual Analog Scale and the Oswestry Disability Index. Patients were given radiographic follow-up examinations after 3, 6, and 12 months and once per year thereafter. RESULTS: All patients were followed for a mean of 15.7±5.6 months (range, 6 to 35 months). The Visual Analog Scale and Oswestry Disability Index scores showed a significant reduction in back pain (p = 0.018) and an improvement in lower extremity function (p = 0.025) in patients who underwent lumbar fusion using the novel screw. Intraoperative cement leakage occurred in four patients, but no neurological complications were observed. Radiological observation indicated no loosening or pulling out of the novel screw, and bone fusion was excellent. CONCLUSIONS: The described polymethylmethacrylate augmentation technique using bone cement-injectable cannulated pedicle screws can reduce pain and improve spinal dysfunction in osteoporotic patients undergoing osteoporotic spine surgery. PMID:25789520

  12. Antibacterial effects of the povidone-iodine vacuum impregnation technique in expanded polytetrafluoroethylene augmentation rhinoplasty.

    PubMed

    Lee, Jung Min; Lee, Joong Seob; Kim, Dong-Kyu; Lee, Jun Ho; Park, Hae Sang; Lee, Ho Jun; Bae, Sung Hee; Jang, Ji Su; Lee, Jae Jun; Park, Chan Hum

    2016-06-01

    Expanded polytetrafluoroethylene (e-PTFE) is a popular graft material for augmentation rhinoplasty. Gore-Tex and Surgiform are two types of e-PTFE; Surgiform has thicker fibrils and is more compact than Gore-Tex. We conducted an ex vivo study to evaluate the ability of povidone-iodine (PVP-I) vacuum pretreatment to prevent infection with these two types of e-PTFE. Gore-Tex and Surgiform specimens were cut into 2-mm(3) pieces, which were separated into two groups. One group for each e-PTFE was disinfected with vacuum PVP-I impregnation and the other group was not disinfected. Using the pieces of implant material, swabs were obtained from the nasal cavities of 20 healthy adults, and the specimens were incubated on agar plates and viewed by scanning electron microscopy (SEM). We found that PVP-I treatment significantly reduced the bacterial colony counts in both the Gore-Tex and Surgiform groups. In the SEM images, bacterial colonies were observed both inside and outside the untreated Gore-Tex; on the untreated Surgiform, they were found primarily on the surface. Few bacteria were detected in the PVP-I-treated Gore-Tex and Surgiform groups. Our findings suggest that PVP-I pretreatment can reduce the risk of infection associated with e-PTFE. PMID:27304448

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

    NASA Astrophysics Data System (ADS)

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

    2010-03-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2009-12-01

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

  15. 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

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

    NASA Technical Reports Server (NTRS)

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

    2005-01-01

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

  17. Pedicle screw placement with O-arm and stealth navigation.

    PubMed

    Patil, Suresh; Lindley, Emily M; Burger, Evalina L; Yoshihara, Hiroyuki; Patel, Vikas V

    2012-01-16

    Various navigation systems are available to aid pedicle screw placement. The O-arm replaces the need for fluoroscopy and generates a 3-dimensional volumetric dataset that can be viewed as transverse, coronal, and sagittal images of the spine, similar to computed tomography (CT) scanning. The dataset can be downloaded to the Stealth system (Medtronic Navigation, Louisville, Colorado) for real-time intraoperative navigation.The main objectives of the current study were to assess (1) accuracy of pedicle screw placement using the O-arm/Stealth system, and (2) time for draping, positioning of the O-arm, and screw placement. Of 188 screws (25 patients), 116 had adequate images for analysis. The average time for O-arm draping was 3.5 minutes. Initial O-arm positioning was 6.1 minutes, and final positioning was 4.9 minutes. Mean time for screw placement, including O-arm draping and positioning and array attachment, was 8.1 minutes per screw. Mean time for screw placement alone was 5.9 minutes per screw. Screw placements on final O-arm images were on average 3.14 mm deeper than on the snapshot navigation images. Three screws (2.6%) breached the medial cortex, and 3 screws (2.6%) were misaligned and did not follow the pilot hole trajectory.The use of the O-arm/Stealth system was associated with a low rate of pedicle screw misalignment. The time to place screws was less than previously reported with CT navigation, but longer than conventional techniques. It is important to be aware of the potential discrepancy between snapshot navigation images and actual screw placement on final O-arm images. Our findings suggest that final screw positions may be deeper than awl positions appear on navigation images.

  18. Chin augmentation.

    PubMed

    Choe, K S; Stucki-McCormick, S U

    2000-01-01

    The primary goal of facial aesthetic surgery is to restore, enhance, and rejuvenate the aging face to a more youthful appearance, achieving balance and harmony. The mental area must be addressed in order to have a complete synthesis of the face. The concept of augmenting the mental area with implants has evolved so significantly that it now stands by itself as an important procedure. Various autogenous implants for chin augmentation have been in use for over 100 years but have complications. The advent of synthetic materials has given rise to various types of alloplastic implants: Gore-Tex, Medpor, Supramid, Silastic, and Mersilene. No one implant is perfect for every face. This article overviews several alloplastic implants--their advantages, disadvantages, and complications, in addition to the different techniques of preparing and delivering the implants.

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

    PubMed Central

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

    2013-01-01

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

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

    PubMed

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

    2008-01-01

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

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

    USGS Publications Warehouse

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

    1997-01-01

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

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

    USGS Publications Warehouse

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

    1997-01-01

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

  3. ArteFill permanent injectable for soft tissue augmentation: I. Mechanism of action and injection techniques.

    PubMed

    Lemperle, Gottfried; Knapp, Terry R; Sadick, Neil S; Lemperle, Stefan M

    2010-06-01

    After more than 25 years of research and development, in October 2006 ArteFill became the first and only permanent injectable wrinkle filler to receive FDA approval. ArteFill is a third-generation polymeric microsphere-based filler, following its predecessor Artecoll, which was marketed outside the United States between 1994 and 2006. ArteFill is approved for the correction of nasolabial folds and has been used in over 15,000 patients since its U.S. market introduction in February 2007. No serious side effects have been reported to date according to the FDA's MAUDE reporting database. ArteFill consists of polymethylmethacrylate (PMMA) microspheres (20% by volume), 30-50 microm in diameter, suspended in 3.5% bovine collagen solution (80% by volume) and 0.3% lidocaine. The collagen carrier is absorbed within 1 month after injection and completely replaced by the patient's own connective tissue within 3 months. Each cc of ArteFill contains approximately six million microspheres and histological studies have shown that long-term wrinkle correction consists of 80% of the patient's own connective tissue and 20% microspheres. The standard injection technique is subdermal tunneling that delivers a strand of ArteFill at the dermal-subdermal junction. This strand beneath a wrinkle or fold acts like a support structure that protects against further wrinkling and allows the diminished thickness of the dermis to recover to its original thickness.

  4. 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

  5. Bilateral Pedicle and Crossed Translaminar Screws in C2.

    PubMed

    Mendelsohn, Daniel; Dea, Nicolas; Lee, Robert; Boyd, Michael C

    2015-10-01

    Multiple techniques exist for the fixation of C2, including axial pedicle screws and bilateral translaminar screws. We describe a novel method of incorporating both the translaminar and pedicle screws within C2 to improve fixation to the subaxial spine in patients requiring posterior cervical instrumentation for deformity correction or instability. We report three cases of patients with cervical spinal instability, who underwent cervical spine instrumentation for stabilization and/or deformity correction. Bilateral C2 pedicle screws were inserted, followed by bilateral crossed laminar screws. The instrumentation method successfully achieved fixation in all three patients. There were no immediate postoperative complications, and hardware positioning was satisfactory. Instrumenting C2 with translaminar and pedicle screws is technically feasible, and it may improve fixation to the subaxial spine in patients with poor bone quality or severe subaxial deformity, which require a stronger instrumentation construct.

  6. Impact of screw configuration on the particle size distribution of granules produced by twin screw granulation.

    PubMed

    Vercruysse, J; Burggraeve, A; Fonteyne, M; Cappuyns, P; Delaet, U; Van Assche, I; De Beer, T; Remon, J P; Vervaet, C

    2015-02-01

    Twin screw granulation (TSG) has been reported by different research groups as an attractive technology for continuous wet granulation. However, in contrast to fluidized bed granulation, granules produced via this technique typically have a wide and multimodal particle size distribution (PSD), resulting in suboptimal flow properties. The aim of the current study was to evaluate the impact of granulator screw configuration on the PSD of granules produced by TSG. Experiments were performed using a 25 mm co-rotating twin screw granulator, being part of the ConsiGma™-25 system (a fully continuous from-powder-to-tablet manufacturing line from GEA Pharma Systems). Besides the screw elements conventionally used for TSG (conveying and kneading elements), alternative designs of screw elements (tooth-mixing-elements (TME), screw mixing elements (SME) and cutters) were investigated using an α-lactose monohydrate formulation granulated with distilled water. Granulation with only conveying elements resulted in wide and multimodal PSD. Using kneading elements, the width of the PSD could be partially narrowed and the liquid distribution was more homogeneous. However, still a significant fraction of oversized agglomerates was obtained. Implementing additional kneading elements or cutters in the final section of the screw configuration was not beneficial. Furthermore, granulation with only TME or SME had limited impact on the width of the PSD. Promising results were obtained by combining kneading elements with SME, as for these configurations the PSD was narrower and shifted to the size fractions suitable for tableting. PMID:25562758

  7. Impact of screw configuration on the particle size distribution of granules produced by twin screw granulation.

    PubMed

    Vercruysse, J; Burggraeve, A; Fonteyne, M; Cappuyns, P; Delaet, U; Van Assche, I; De Beer, T; Remon, J P; Vervaet, C

    2015-02-01

    Twin screw granulation (TSG) has been reported by different research groups as an attractive technology for continuous wet granulation. However, in contrast to fluidized bed granulation, granules produced via this technique typically have a wide and multimodal particle size distribution (PSD), resulting in suboptimal flow properties. The aim of the current study was to evaluate the impact of granulator screw configuration on the PSD of granules produced by TSG. Experiments were performed using a 25 mm co-rotating twin screw granulator, being part of the ConsiGma™-25 system (a fully continuous from-powder-to-tablet manufacturing line from GEA Pharma Systems). Besides the screw elements conventionally used for TSG (conveying and kneading elements), alternative designs of screw elements (tooth-mixing-elements (TME), screw mixing elements (SME) and cutters) were investigated using an α-lactose monohydrate formulation granulated with distilled water. Granulation with only conveying elements resulted in wide and multimodal PSD. Using kneading elements, the width of the PSD could be partially narrowed and the liquid distribution was more homogeneous. However, still a significant fraction of oversized agglomerates was obtained. Implementing additional kneading elements or cutters in the final section of the screw configuration was not beneficial. Furthermore, granulation with only TME or SME had limited impact on the width of the PSD. Promising results were obtained by combining kneading elements with SME, as for these configurations the PSD was narrower and shifted to the size fractions suitable for tableting.

  8. Development and Testing of X-Ray Imaging-Enhanced Poly-L-Lactide Bone Screws.

    PubMed

    Chang, Wei-Jen; Pan, Yu-Hwa; Tzeng, Jy-Jiunn; Wu, Ting-Lin; Fong, Tsorng-Harn; Feng, Sheng-Wei; Huang, Haw-Ming

    2015-01-01

    Nanosized iron oxide particles exhibit osteogenic and radiopaque properties. Thus, iron oxide (Fe3O4) nanoparticles were incorporated into a biodegradable polymer (poly-L-lactic acid, PLLA) to fabricate a composite bone screw. This multifunctional, 3D printable bone screw was detectable on X-ray examination. In this study, mechanical tests including three-point bending and ultimate tensile strength were conducted to evaluate the optimal ratio of iron oxide nanoparticles in the PLLA composite. Both injection molding and 3D printing techniques were used to fabricate the PLLA bone screws with and without the iron oxide nanoparticles. The fabricated screws were implanted into the femoral condyles of New Zealand White rabbits. Bone blocks containing the PLLA screws were resected 2 and 4 weeks after surgery. Histologic examination of the surrounding bone and the radiopacity of the iron-oxide-containing PLLA screws were evaluated. Our results indicated that addition of iron oxide nanoparticles at 30% significantly decreased the ultimate tensile stress properties of the PLLA screws. The screws with 20% iron oxide exhibited strong radiopacity compared to the screws fabricated without the iron oxide nanoparticles. Four weeks after surgery, the average bone volume of the iron oxide PLLA composite screws was significantly greater than that of PLLA screws without iron oxide. These findings suggested that biodegradable and X-ray detectable PLLA bone screws can be produced by incorporation of 20% iron oxide nanoparticles. Furthermore, these screws had significantly greater osteogenic capability than the PLLA screws without iron oxide. PMID:26466309

  9. 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

  10. 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.

  11. Finite element analysis of osteosynthesis screw fixation in the bone stock: an appropriate method for automatic screw modelling.

    PubMed

    Wieding, Jan; Souffrant, Robert; Fritsche, Andreas; Mittelmeier, Wolfram; Bader, Rainer

    2012-01-01

    The use of finite element analysis (FEA) has grown to a more and more important method in the field of biomedical engineering and biomechanics. Although increased computational performance allows new ways to generate more complex biomechanical models, in the area of orthopaedic surgery, solid modelling of screws and drill holes represent a limitation of their use for individual cases and an increase of computational costs. To cope with these requirements, different methods for numerical screw modelling have therefore been investigated to improve its application diversity. Exemplarily, fixation was performed for stabilization of a large segmental femoral bone defect by an osteosynthesis plate. Three different numerical modelling techniques for implant fixation were used in this study, i.e. without screw modelling, screws as solid elements as well as screws as structural elements. The latter one offers the possibility to implement automatically generated screws with variable geometry on arbitrary FE models. Structural screws were parametrically generated by a Python script for the automatic generation in the FE-software Abaqus/CAE on both a tetrahedral and a hexahedral meshed femur. Accuracy of the FE models was confirmed by experimental testing using a composite femur with a segmental defect and an identical osteosynthesis plate for primary stabilisation with titanium screws. Both deflection of the femoral head and the gap alteration were measured with an optical measuring system with an accuracy of approximately 3 µm. For both screw modelling techniques a sufficient correlation of approximately 95% between numerical and experimental analysis was found. Furthermore, using structural elements for screw modelling the computational time could be reduced by 85% using hexahedral elements instead of tetrahedral elements for femur meshing. The automatically generated screw modelling offers a realistic simulation of the osteosynthesis fixation with screws in the adjacent

  12. Finite Element Analysis of Osteosynthesis Screw Fixation in the Bone Stock: An Appropriate Method for Automatic Screw Modelling

    PubMed Central

    Wieding, Jan; Souffrant, Robert; Fritsche, Andreas; Mittelmeier, Wolfram; Bader, Rainer

    2012-01-01

    The use of finite element analysis (FEA) has grown to a more and more important method in the field of biomedical engineering and biomechanics. Although increased computational performance allows new ways to generate more complex biomechanical models, in the area of orthopaedic surgery, solid modelling of screws and drill holes represent a limitation of their use for individual cases and an increase of computational costs. To cope with these requirements, different methods for numerical screw modelling have therefore been investigated to improve its application diversity. Exemplarily, fixation was performed for stabilization of a large segmental femoral bone defect by an osteosynthesis plate. Three different numerical modelling techniques for implant fixation were used in this study, i.e. without screw modelling, screws as solid elements as well as screws as structural elements. The latter one offers the possibility to implement automatically generated screws with variable geometry on arbitrary FE models. Structural screws were parametrically generated by a Python script for the automatic generation in the FE-software Abaqus/CAE on both a tetrahedral and a hexahedral meshed femur. Accuracy of the FE models was confirmed by experimental testing using a composite femur with a segmental defect and an identical osteosynthesis plate for primary stabilisation with titanium screws. Both deflection of the femoral head and the gap alteration were measured with an optical measuring system with an accuracy of approximately 3 µm. For both screw modelling techniques a sufficient correlation of approximately 95% between numerical and experimental analysis was found. Furthermore, using structural elements for screw modelling the computational time could be reduced by 85% using hexahedral elements instead of tetrahedral elements for femur meshing. The automatically generated screw modelling offers a realistic simulation of the osteosynthesis fixation with screws in the adjacent

  13. Pull-out strength of cemented solid versus fenestrated pedicle screws in osteoporotic vertebrae

    PubMed Central

    Leichtle, C. I.; Rothstock, S.; Happel, J.; Walter, F.; Shiozawa, T.; Leichtle, U. G.

    2016-01-01

    Objectives Cement augmentation of pedicle screws could be used to improve screw stability, especially in osteoporotic vertebrae. However, little is known concerning the influence of different screw types and amount of cement applied. Therefore, the aim of this biomechanical in vitro study was to evaluate the effect of cement augmentation on the screw pull-out force in osteoporotic vertebrae, comparing different pedicle screws (solid and fenestrated) and cement volumes (0 mL, 1 mL or 3 mL). Materials and Methods A total of 54 osteoporotic human cadaver thoracic and lumbar vertebrae were instrumented with pedicle screws (uncemented, solid cemented or fenestrated cemented) and augmented with high-viscosity PMMA cement (0 mL, 1 mL or 3 mL). The insertion torque and bone mineral density were determined. Radiographs and CT scans were undertaken to evaluate cement distribution and cement leakage. Pull-out testing was performed with a material testing machine to measure failure load and stiffness. The paired t-test was used to compare the two screws within each vertebra. Results Mean failure load was significantly greater for fenestrated cemented screws (+622 N; p ⩽ 0.001) and solid cemented screws (+460 N; p ⩽ 0.001) than for uncemented screws. There was no significant difference between the solid and fenestrated cemented screws (p = 0.5). In the lower thoracic vertebrae, 1 mL cement was enough to significantly increase failure load, while 3 mL led to further significant improvement in the upper thoracic, lower thoracic and lumbar regions. Conclusion Conventional, solid pedicle screws augmented with high-viscosity cement provided comparable screw stability in pull-out testing to that of sophisticated and more expensive fenestrated screws. In terms of cement volume, we recommend the use of at least 1 mL in the thoracic and 3 mL in the lumbar spine. Cite this article: C. I. Leichtle, A. Lorenz, S. Rothstock, J. Happel, F. Walter, T. Shiozawa, U. G. Leichtle. Pull

  14. Cannulated screw with solid core insert: stronger than cannulated screws.

    PubMed

    Dundon, John M; Gould, Gregory C; Herbenick, Michael A; Hamilton, J Adam

    2014-09-01

    We conducted a study to determine if there is a significant difference in ultimate load, yield strength, and fatigue strength between solid core screws and cannulated screws and if a solid core insert placed inside a cannulated screw would have biomechanical effects similar to those of a solid core screw. Five screw designs were tested: Synthes 4.5-mm solid core and 4.5-mm cannulated and our prototype 4.0-mm solid core, 4.0-mm cannulated, and 4.0-mm cannulated with solid core insert. Biomechanical testing with 3-point bending was used to determine ultimate load, yield strength, and cycles to failure for 6 screws of each design. Ultimate load, yield strength, and cycles to failure were significantly (P < .05) lower in the Synthes 4.5-mm cannulated screws than in the Synthes solid core screws and significantly lower in the prototype cannulated screws than in the prototype solid core screws (P < .05) and prototype cannulated screws with solid core inserts (P < .05). There was no significant difference (P > .05) in ultimate load, yield strength, or cycles to failure between the prototype cannulated screws with solid core inserts and the prototype solid core screws.

  15. A technique for in vitro fit assessment of multi-unit screw-retained implant restorations: Application of a triple-scan protocol

    PubMed Central

    Karl, Matthias; Wichmann, Manfred; Matta, Ragai E

    2012-01-01

    Recent advances in industrial non-contact scanners offer unprecedented opportunities for quality assessment of dental restorations. The majority of investigations published to date are limited to local two-dimensional results. A triple-scan protocol for virtual fit assessment of multi-unit screw-retained implant restorations is presented in this technical report. The advantages for application in biomechanical research include detailed three-dimensional information on internal component congruence in implant superstructures to be used in mathematical models. PMID:22924063

  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. 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.

  18. Extra-articular extraosseous migration of a bioabsorbable femoral interference screw after ACL reconstruction.

    PubMed

    Sharma, Vivek; Curtis, Christine; Micheli, Lyle

    2008-10-01

    Anterior cruciate ligament (ACL) reconstruction is quite commonly used to treat anterior knee instability. Surgeon preference and patient functional goals determine graft selection and graft fixation techniques. Interference screws are considered a safe and effective device for graft fixation in surgical ACL reconstruction. Poly-L-lactide acid (PLLA) bioabsorbable interference screws are becoming increasingly popular in ACL reconstruction surgery. There are several reasons why they may be more advantageous than metallic screws, including reduced graft laceration during insertion, ease of performance of revision procedures, avoidance of graft injury encountered with aperture fixation using metallic screws, and fewer artifacts on magnetic resonance images (MRI). Few studies describe complications associated with PLLA bioabsorbable screws, particularly extra-articular screw migration. This article presents a case of an extra-articular extraosseous migration of the femoral bioabsorbable interference screw. This case further demonstrates the problem of the femoral bioabsorbable interference screw.

  19. 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.

  20. Quantitative Anatomy of C7 Vertebra in Southern Chinese for Insertion of Lateral Mass Screws and Pedicle Screws

    PubMed Central

    Chan, Chi Hin; Wong, Kam Kwong; Wong, Wing Cheung

    2016-01-01

    Study Design Retrospective study. Purpose To analyze the quantitative anatomy of C7 vertebra for insertion of lateral mass screws and pedicle screws in Southern Chinese patients. Overview of Literature C7 lateral mass is smaller when compared to other subaxial cervical levels, which limits the length of lateral mass screws that can be used. Some studies have suggested pedicle screws for better fixation. But, this option is limited by the narrow pedicle width. Methods We have obtained computed tomography (CT) cervical spine data in 0.625 mm slices from our radiology department. The patients were adults. CTs were from May to August, 2015. The lateral mass screw length was measured using Margerl's technique and pedicle width and pedicle screw trajectory were determined in three-dimensional reformated images. Results CT scans of cervical spines of 94 patients were obtained and 188 lateral masses and pedicles of C7 vertebrae were measured. The mean lateral mass screw length was 13.2 mm (standard deviation [SD] 1.6 mm), mean outer pedicle width was 5.9 mm (SD 1.0 mm) and mean pedicle screw trajectory was 29.4 degrees (SD 3.6 degrees). Most (91.0%) of the pedicles had an outer diameter ≥4.5 mm. Conclusions The mean lateral mass screw length was longer when compared with other similar studies, while the mean outer pedicle width was narrower. Nearly 10% of the pedicles were unable to accommodate 3.5 mm screws. These findings favor the use of lateral mass screws to provide a safe and stable fixation for C7 vertebrae in Southern Chinese patients, while the final choice of fixation method should only be confirmed after careful preoperative planning with CT scan. PMID:27559451

  1. A cone-beam CT based technique to augment the 3D virtual skull model with a detailed dental surface.

    PubMed

    Swennen, G R J; Mommaerts, M Y; Abeloos, J; De Clercq, C; Lamoral, P; Neyt, N; Casselman, J; Schutyser, F

    2009-01-01

    Cone-beam computed tomography (CBCT) is used for maxillofacial imaging. 3D virtual planning of orthognathic and facial orthomorphic surgery requires detailed visualisation of the interocclusal relationship. This study aimed to introduce and evaluate the use of a double CBCT scan procedure with a modified wax bite wafer to augment the 3D virtual skull model with a detailed dental surface. The impressions of the dental arches and the wax bite wafer were scanned for ten patient separately using a high resolution standardized CBCT scanning protocol. Surface-based rigid registration using ICP (iterative closest points) was used to fit the virtual models on the wax bite wafer. Automatic rigid point-based registration of the wax bite wafer on the patient scan was performed to implement the digital virtual dental arches into the patient's skull model. Probability error histograms showed errors of < or =0.22 mm (25% percentile), < or =0.44 mm (50% percentile) and < or =1.09 mm (90% percentile) for ICP surface matching. The mean registration error for automatic point-based rigid registration was 0.18+/-0.10 mm (range 0.13-0.26 mm). The results show the potential for a double CBCT scan procedure with a modified wax bite wafer to set-up a 3D virtual augmented model of the skull with detailed dental surface.

  2. Comparison of the bending performance of solid and cannulated spinal pedicle screws using finite element analyses and biomechanical tests.

    PubMed

    Shih, Kao-Shang; Hsu, Ching-Chi; Hou, Sheng-Mou; Yu, Shan-Chuen; Liaw, Chen-Kun

    2015-09-01

    Spinal pedicle screw fixations have been used extensively to treat fracture, tumor, infection, or degeneration of the spine. Cannulated spinal pedicle screws with bone cement augmentation might be a useful method to ameliorate screw loosening. However, cannulated spinal pedicle screws might also increase the risk of screw breakage. Thus, the purpose of this study was to investigate the bending performance of different spinal pedicle screws with either solid design or cannulated design. Three-dimensional finite element models, which consisted of the spinal pedicle screw and the screw's hosting material, were first constructed. Next, monotonic and cyclic cantilever bending tests were both applied to validate the results of the finite element analyses. Finally, both the numerical and experimental approaches were evaluated and compared. The results indicated that the cylindrical spinal pedicle screws with a cannulated design had significantly poorer bending performance. In addition, conical spinal pedicle screws maintained the original bending performance, whether they were solid or of cannulated design. This study may provide useful recommendations to orthopedic surgeons before surgery, and it may also provide design rationales to biomechanical engineers during the development of spinal pedicle screws. PMID:26208430

  3. Noninvasive method for retrieval of broken dental implant abutment screw

    PubMed Central

    Gooty, Jagadish Reddy; Palakuru, Sunil Kumar; Guntakalla, Vikram Reddy; Nera, Mahipal

    2014-01-01

    Dental implants made of titanium for replacement of missing teeth are widely used because of ease of technical procedure and high success rate, but are not free of complications and may fail. Fracturing of the prosthetic screw continues to be a problem in restorative practice and great challenge to remove the fractured screw conservatively. This case report describes and demonstrates the technique of using an ultrasonic scaler in the removal of the fracture screw fragment as a noninvasive method without damaging the hex of implants. PMID:24963261

  4. NUT SCREW MECHANISMS

    DOEpatents

    Glass, J.A.F.

    1958-07-01

    A reactor control mechanism is described wherein the control is achieved by the partial or total withdrawal of the fissile material which is in the form of a fuel rod. The fuel rod is designed to be raised and lowered from the reactor core area by means of two concentric ball nut and screw assemblies that may telescope one within the other. These screw mechanisms are connected through a magnetic clutch to a speed reduction gear and an accurately controllable prime motive source. With the clutch energized, the fuel rod may be moved into the reactor core area, and fine adjustments may be made through the reduction gearing. However, in the event of a power failure or an emergency signal, the magnetic clutch will become deenergized, and the fuel rod will drop out of the core area by the force of gravity, thus shutting down the operation of the reactor.

  5. The management of bone loss in revision total knee arthroplasty: rebuild, reinforce, and augment.

    PubMed

    Sculco, P K; Abdel, M P; Hanssen, A D; Lewallen, D G

    2016-01-01

    The treatment of bone loss in revision total knee arthroplasty has evolved over the past decade. While the management of small to moderate sized defects has demonstrated good results with a variety of traditional techniques (cement and screws, small metal augments, impaction bone grafting or modular stems), the treatment of severe defects continues to be problematic. The use of a structural allograft has declined in recent years due to an increased failure rate with long-term follow-up and with the introduction of highly porous metal augments that emphasise biological metaphyseal fixation. Recently published mid-term results on the use of tantalum cones in patients with severe bone loss has reaffirmed the success of this treatment strategy. PMID:26733657

  6. 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.

  7. Vertebroplasty and kyphoplasty--a systematic review of cement augmentation techniques for osteoporotic vertebral compression fractures compared to standard medical therapy.

    PubMed

    Robinson, Yohan; Olerud, Claes

    2012-05-01

    After more than two decades the treatment effect of cement augmentation of osteoporotic vertebral compression fractures (VCF) has now been questioned by two blinded randomised placebo-controlled trials. Thus many practitioners are uncertain on the recommendation for cement augmentation techniques in elderly patients with osteoporotic VCF. This systematic review analyses randomised controlled trials on vertebroplasty and kyphoplasty to provide an overview on the current evidence. From an electronic database research 8 studies could be identified meeting our inclusion criteria of osteoporotic VCF in elderly (age>60 years), treatment with vertebroplasty or kyphoplasty, controlled with placebo or standard medical therapy, quality of life, function, or pain as primary parameter, and randomisation. Only two studies were properly blinded using a sham-operation as control. The other studies were using a non-surgical treatment control group. Further possible bias may be caused by manufacturer involvement in financing of three published RCT. There is level Ib evidence that vertebroplasty is no better than placebo, which is conflicting with the available level IIb evidence that there is a positive short-term effect of cement augmentation compared to standard medical therapy with regard to QoL, function and pain. Kyphoplasty is not superior to vertebroplasty with regard to pain, but with regard to VCF reduction (evidence level IIb). Kyphoplasty is probably not cost-effective (evidence level IIb), and vertebroplasty has not more than short-term cost-effectiveness (evidence level IV). Vertebroplasty and kyphoplasty cannot be recommended as standard treatment for osteoporotic VCF. Ongoing sham-controlled trials may provide further evidence in this regard.

  8. Pilot-optimal augmentation synthesis

    NASA Technical Reports Server (NTRS)

    Schmidt, D. K.

    1978-01-01

    An augmentation synthesis method usable in the absence of quantitative handling qualities specifications, and yet explicitly including design objectives based on pilot-rating concepts, is presented. The algorithm involves the unique approach of simultaneously solving for the stability augmentation system (SAS) gains, pilot equalization and pilot rating prediction via optimal control techniques. Simultaneous solution is required in this case since the pilot model (gains, etc.) depends upon the augmented plant dynamics, and the augmentation is obviously not a priori known. Another special feature is the use of the pilot's objective function (from which the pilot model evolves) to design the SAS.

  9. Accuracy of robot-assisted pedicle screw placement for adolescent idiopathic scoliosis in the pediatric population.

    PubMed

    Macke, Jeremy J; Woo, Raymund; Varich, Laura

    2016-06-01

    This is a retrospective review of pedicle screw placement in adolescent idiopathic scoliosis (AIS) patients under 18 years of age who underwent robot-assisted corrective surgery. Our primary objective was to characterize the accuracy of pedicle screw placement with evaluation by computed tomography (CT) after robot-assisted surgery in AIS patients. Screw malposition is the most frequent complication of pedicle screw placement and is more frequent in AIS. Given the potential for serious complications, the need for improved accuracy of screw placement has spurred multiple innovations including robot-assisted guidance devices. No studies to date have evaluated this robot-assisted technique using CT exclusively within the AIS population. Fifty patients were included in the study. All operative procedures were performed at a single institution by a single pediatric orthopedic surgeon. We evaluated the grade of screw breach, the direction of screw breach, and the positioning of the patient for preoperative scan (supine versus prone). Of 662 screws evaluated, 48 screws (7.2 %) demonstrated a breach of greater than 2 mm. With preoperative prone position CT scanning, only 2.4 % of screws were found to have this degree of breach. Medial malposition was found in 3 % of screws, a rate which decreased to 0 % with preoperative prone position scanning. Based on our results, we conclude that the proper use of image-guided robot-assisted surgery can improve the accuracy and safety of thoracic pedicle screw placement in patients with adolescent idiopathic scoliosis. This is the first study to evaluate the accuracy of pedicle screw placement using CT assessment in robot-assisted surgical correction of patients with AIS. In our study, the robot-assisted screw misplacement rate was lower than similarly constructed studies evaluating conventional (non-robot-assisted) procedures. If patients are preoperatively scanned in the prone position, the misplacement rate is further

  10. Biomechanical Evaluation of Plate Versus Lag Screw Only Fixation of Distal Fibula Fractures.

    PubMed

    Misaghi, Amirhossein; Doan, Josh; Bastrom, Tracey; Pennock, Andrew T

    2015-01-01

    Traditional fixation of unstable Orthopaedic Trauma Association type B/C ankle fractures consists of a lag screw and a lateral or posterolateral neutralization plate. Several studies have demonstrated the clinical success of lag screw only fixation; however, to date no biomechanical comparison of the different constructs has been performed. The purpose of the present study was to evaluate the biomechanical strength of these different constructs. Osteotomies were created in 40 Sawbones(®) distal fibulas and reduced using 1 bicortical 3.5-mm stainless steel lag screw, 2 bicortical 3.5-mm lag screws, 3 bicortical 3.5-mm lag screws, or a single 3.5-mm lag screw coupled with a stainless steel neutralization plate with 3 proximal cortical and 3 distal cancellous screws. The constructs were tested to determine the stiffness in lateral bending and rotation and failure torque. No significant differences in lateral bending or rotational stiffness were detected between the osteotomies fixed with 3 lag screws and a plate. Constructs fixed with 1 lag screw were weaker for both lateral bending and rotational stiffness. Osteotomies fixed with 2 lag screws were weaker in lateral bending only. No significant differences were found in the failure torque. Compared with lag screw only fixation, plate fixation requires larger incisions and increased costs and is more likely to require follow-up surgery. Despite the published clinical success of treating simple Orthopaedic Trauma Association B/C fractures with lag screw only fixation, many surgeons still have concerns about stability. For noncomminuted, long oblique distal fibula fractures, lag screw only fixation techniques offer construct stiffness similar to that of traditional plate and lag screw fixation. PMID:25990534

  11. Biomechanical Evaluation of Plate Versus Lag Screw Only Fixation of Distal Fibula Fractures.

    PubMed

    Misaghi, Amirhossein; Doan, Josh; Bastrom, Tracey; Pennock, Andrew T

    2015-01-01

    Traditional fixation of unstable Orthopaedic Trauma Association type B/C ankle fractures consists of a lag screw and a lateral or posterolateral neutralization plate. Several studies have demonstrated the clinical success of lag screw only fixation; however, to date no biomechanical comparison of the different constructs has been performed. The purpose of the present study was to evaluate the biomechanical strength of these different constructs. Osteotomies were created in 40 Sawbones(®) distal fibulas and reduced using 1 bicortical 3.5-mm stainless steel lag screw, 2 bicortical 3.5-mm lag screws, 3 bicortical 3.5-mm lag screws, or a single 3.5-mm lag screw coupled with a stainless steel neutralization plate with 3 proximal cortical and 3 distal cancellous screws. The constructs were tested to determine the stiffness in lateral bending and rotation and failure torque. No significant differences in lateral bending or rotational stiffness were detected between the osteotomies fixed with 3 lag screws and a plate. Constructs fixed with 1 lag screw were weaker for both lateral bending and rotational stiffness. Osteotomies fixed with 2 lag screws were weaker in lateral bending only. No significant differences were found in the failure torque. Compared with lag screw only fixation, plate fixation requires larger incisions and increased costs and is more likely to require follow-up surgery. Despite the published clinical success of treating simple Orthopaedic Trauma Association B/C fractures with lag screw only fixation, many surgeons still have concerns about stability. For noncomminuted, long oblique distal fibula fractures, lag screw only fixation techniques offer construct stiffness similar to that of traditional plate and lag screw fixation.

  12. 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.

  13. 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.

  14. Translational mini-screw implant research.

    PubMed

    Rossouw, Emile

    2014-09-01

    It is important to thoroughly test new materials as well as techniques when these innovations are to be utilized in the human clinical situation. Translational research fills this important niche. The purpose of translational research is to establish the continuity of evidence from the laboratory to the clinic and in so-doing, provide evidence that the material is functioning appropriately and that the process in the human will be successful. This concept applies to the mini-screw implant; which, has been very successfully introduced into the orthodontic armamentarium over the last decade for application as a temporary anchorage device. The examples of translational research that will be illustrated in this paper have paved the way to ensure that clinicians have evidence to confidently utilize mini-screw implants in orthodontic practice. Needless to say, more studies are needed to ensure a safe, effective and efficient manner to practice orthodontics.

  15. Augmenting a Microbial Selective Plugging Technique with Polymer Flooding to Increase the Efficiency of Oil Recovery - A Search for Synergy

    SciTech Connect

    Brown, Lewis R.; Pittman Jr., Charles U.; Lynch, F. Leo; Vadie, A. Alex

    2003-02-10

    The overall objective of this project was to improve the effectiveness of a microbial selective plugging technique of improving oil recovery through the use of polymer floods. More specifically, the intent was to increase the total amount of oil recovered and to reduce the cost per barrel of incremental oil.

  16. The Use of Biofeedback to Augment the Acquisition of Skills in Performing Joint Mobilization Techniques among Physical Therapy Students

    ERIC Educational Resources Information Center

    Timmerberg, Jean Fitzpatrick

    2011-01-01

    Despite the frequent use of joint mobilizations and the available evidence of its effectiveness as a treatment for various musculoskeletal disorders, it is a technique that has been shown to have great variability within and between raters. This variability is believed to occur because of differences between therapists' ability to perceive…

  17. Ridge augmentation with soft tissue procedures in aesthetic dentistry: first clinical results measured with a new kind of moire technique

    NASA Astrophysics Data System (ADS)

    Studer, Stephan P.; Bucher, Andreas; Mueller, Felix

    1993-09-01

    The oral health of the Swiss population was significantly improved by the successful prevention of dental caries and periodontitis. Along with the healthy dentition the demand for aesthetic dentistry is increasing. Removable partial dentures are becoming less accepted. Therefore, to substitute lost teeth by permanent fixed partial prosthesis (bridges), the often deformed alveolar ridge has to be operated, either to improve the aesthetic appearance or to make it possible to restore the missing teeth by a fixed cemented bridge. The aim of this paper is (1) to evaluate whether the moire technique is an appropriate and handy method, and (2) to validate the precision of the new method. The measuring system consisted of a moire projector with an integrated phase shift device and a moire viewer with a CCD video camera, connected to a frame grabber in a personal computer. a highly versatile software was allowed to control the system as well as to grab the moire images using the four-phase shift technique in order to compute the phase image of the actual object. The new technique was validated with one solid test object measured by a 3D coordination, high precision measuring machine.

  18. Robot-assisted Anterior Odontoid Screw Fixation: A Case Report.

    PubMed

    Tian, Wei; Wang, Han; Liu, Ya-Jun

    2016-08-01

    Anterior odontoid screw fixation has been proved to be effective but technically challenging because the difficult approach is associated with high risks of screw malposition and damage to surrounding vital structures. Navigation techniques are therefore increasingly being used to improve safety and accuracy. However, no robot-assisted odontoid screw fixation has yet been reported. We here report a 61-year-old woman with a type II dens fracture on whom anterior odontoid screw fixation was performed under the guidance of a newly developed robotic system (TiRobot, co-designed by Beijing Jishuitan Hospital and TINAVI Medical Technologies). One odontoid screw was safely and accurately placed, the calculated deviation between the planned and actual positions being 0.9 mm. No intraoperative complications were identified and the patient was discharged on Day 5. Follow-up studies after 2 weeks showed good clinical and radiological results. We believe this is the first reported case of robot-assisted anterior odontoid screw fixation. We consider that complicated procedures can become feasible, safe and accurate using TiRobot systems.

  19. Robot-assisted Anterior Odontoid Screw Fixation: A Case Report.

    PubMed

    Tian, Wei; Wang, Han; Liu, Ya-Jun

    2016-08-01

    Anterior odontoid screw fixation has been proved to be effective but technically challenging because the difficult approach is associated with high risks of screw malposition and damage to surrounding vital structures. Navigation techniques are therefore increasingly being used to improve safety and accuracy. However, no robot-assisted odontoid screw fixation has yet been reported. We here report a 61-year-old woman with a type II dens fracture on whom anterior odontoid screw fixation was performed under the guidance of a newly developed robotic system (TiRobot, co-designed by Beijing Jishuitan Hospital and TINAVI Medical Technologies). One odontoid screw was safely and accurately placed, the calculated deviation between the planned and actual positions being 0.9 mm. No intraoperative complications were identified and the patient was discharged on Day 5. Follow-up studies after 2 weeks showed good clinical and radiological results. We believe this is the first reported case of robot-assisted anterior odontoid screw fixation. We consider that complicated procedures can become feasible, safe and accurate using TiRobot systems. PMID:27627725

  20. Transforaminal lumbar interbody fusion using unilateral pedicle screws and a translaminar screw

    PubMed Central

    Lee, Sandra; Vaidya, Rahul

    2008-01-01

    Lumbar spinal fusion is advancing with minimally invasive techniques, bone graft alternatives, and new implants. This has resulted in significant reductions of operative time, duration of hospitalization, and higher success in fusion rates. However, costs have increased as many new technologies are expensive. This study was carried out to investigate the clinical outcomes and fusion rates of a low implant load construct of unilateral pedicle screws and a translaminar screw in transforaminal lumbar interbody fusion (TLIF) which reduced the cost of the posterior implants by almost 50%. Nineteen consecutive patients who underwent single level TLIF with this construct were included in the study. Sixteen patients had a TLIF allograft interbody spacer placed, while in three a polyetheretherketone (PEEK) cage was used. Follow-up ranged from 15 to 54 months with a mean of 32 months. A clinical and radiographic evaluation was carried out preoperatively and at multiple time points following surgery. An overall improvement in Oswestry scores and visual analogue scales for leg and back pain (VAS) was observed. Three patients underwent revision surgery due to recurrence of back pain. All patients showed radiographic evidence of fusion from 9 to 26 months (mean 19) following surgery. This study suggests that unilateral pedicle screws and a contralateral translaminar screw are a cheaper and viable option for single level lumbar fusion. PMID:19015896

  1. 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.

  2. Carbon nanotube Archimedes screws.

    PubMed

    Oroszlány, László; Zólyomi, Viktor; Lambert, Colin J

    2010-12-28

    Recently, nanomechanical devices composed of a long stationary inner carbon nanotube and a shorter, slowly rotating outer tube have been fabricated. In this paper, we study the possibility of using such devices as nanoscale transducers of motion into electricity. When the outer tube is chiral, we show that such devices act like quantum Archimedes screws, which utilize mechanical energy to pump electrons between reservoirs. We calculate the pumped charge from one end of the inner tube to the other, driven by the rotation of a chiral outer nanotube. We show that the pumped charge can be greater than one electron per 360° rotation, and consequently, such a device operating with a rotational frequency of 10 MHz, for example, would deliver a current of ≈1 pAmp.

  3. Augmentation cystoplasty in neurogenic bladder

    PubMed Central

    Kocjancic, Ervin; Demirdağ, Çetin

    2016-01-01

    The aim of this review is to update the indications, contraindications, technique, complications, and the tissue engineering approaches of augmentation cystoplasty (AC) in patients with neurogenic bladder. PubMed/MEDLINE was searched for the keywords "augmentation cystoplasty," "neurogenic bladder," and "bladder augmentation." Additional relevant literature was determined by examining the reference lists of articles identified through the search. The update review of of the indications, contraindications, technique, outcome, complications, and tissue engineering approaches of AC in patients with neurogenic bladder is presented. Although some important progress has been made in tissue engineering AC, conventional AC still has an important role in the surgical treatment of refractory neurogenic lower urinary tract dysfunction.

  4. Laminar screw fixation in the subaxial cervical spine: A report on three cases

    PubMed Central

    Tanabe, Hironori; Aota, Yoichi; Saito, Tomoyuki

    2016-01-01

    Although laminar screw fixation is often used at the C2 and C7 levels, only few previous case reports have presented the use of laminar screws at the C3-C6 levels. Here, we report a novel fixation method involving the use of practical laminar screws in the subaxial spine. We used laminar screws in the subaxial cervical spine in two cases to prevent vertebral artery injury and in one case to minimize exposure of the lamina. This laminar screw technique was successful in all three cases with adequate spinal rigidity, which was achieved without complications. The use of laminar screws in the subaxial cervical spine is a useful option for posterior fusion of the cervical spine. PMID:27795952

  5. 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

  6. Innovative approach in the development of computer assisted algorithm for spine pedicle screw placement.

    PubMed

    Solitro, Giovanni F; Amirouche, Farid

    2016-04-01

    Pedicle screws are typically used for fusion, percutaneous fixation, and means of gripping a spinal segment. The screws act as a rigid and stable anchor points to bridge and connect with a rod as part of a construct. The foundation of the fusion is directly related to the placement of these screws. Malposition of pedicle screws causes intraoperative complications such as pedicle fractures and dural lesions and is a contributing factor to fusion failure. Computer assisted spine surgery (CASS) and patient-specific drill templates were developed to reduce this failure rate, but the trajectory of the screws remains a decision driven by anatomical landmarks often not easily defined. Current data shows the need of a robust and reliable technique that prevents screw misplacement. Furthermore, there is a need to enhance screw insertion guides to overcome the distortion of anatomical landmarks, which is viewed as a limiting factor by current techniques. The objective of this study is to develop a method and mathematical lemmas that are fundamental to the development of computer algorithms for pedicle screw placement. Using the proposed methodology, we show how we can generate automated optimal safe screw insertion trajectories based on the identification of a set of intrinsic parameters. The results, obtained from the validation of the proposed method on two full thoracic segments, are similar to previous morphological studies. The simplicity of the method, being pedicle arch based, is applicable to vertebrae where landmarks are either not well defined, altered or distorted. PMID:26922675

  7. Virtual estimates of fastening strength for pedicle screw implantation procedures

    NASA Astrophysics Data System (ADS)

    Linte, Cristian A.; Camp, Jon J.; Augustine, Kurt E.; Huddleston, Paul M.; Robb, Richard A.; Holmes, David R.

    2014-03-01

    Traditional 2D images provide limited use for accurate planning of spine interventions, mainly due to the complex 3D anatomy of the spine and close proximity of nerve bundles and vascular structures that must be avoided during the procedure. Our previously developed clinician-friendly platform for spine surgery planning takes advantage of 3D pre-operative images, to enable oblique reformatting and 3D rendering of individual or multiple vertebrae, interactive templating, and placement of virtual pedicle implants. Here we extend the capabilities of the planning platform and demonstrate how the virtual templating approach not only assists with the selection of the optimal implant size and trajectory, but can also be augmented to provide surrogate estimates of the fastening strength of the implanted pedicle screws based on implant dimension and bone mineral density of the displaced bone substrate. According to the failure theories, each screw withstands a maximum holding power that is directly proportional to the screw diameter (D), the length of the in-bone segm,ent of the screw (L), and the density (i.e., bone mineral density) of the pedicle body. In this application, voxel intensity is used as a surrogate measure of the bone mineral density (BMD) of the pedicle body segment displaced by the screw. We conducted an initial assessment of the developed platform using retrospective pre- and post-operative clinical 3D CT data from four patients who underwent spine surgery, consisting of a total of 26 pedicle screws implanted in the lumbar spine. The Fastening Strength of the planned implants was directly assessed by estimating the intensity - area product across the pedicle volume displaced by the virtually implanted screw. For post-operative assessment, each vertebra was registered to its homologous counterpart in the pre-operative image using an intensity-based rigid registration followed by manual adjustment. Following registration, the Fastening Strength was computed

  8. Transgluteal posterior column screw stabilization for fractures of the acetabulum: a technical trick.

    PubMed

    Connelly, Camille L; Archdeacon, Michael T

    2012-10-01

    The traditional exposure of high posterior column or transverse acetabular fractures can pose a challenge for lag screw stabilization. The authors describe an adjunctive percutaneous transgluteal lag screw technique for the internal fixation of the high posterior column. In the senior author's experience, this technique has been helpful to achieve the optimal trajectory for a stable perpendicular lag screw to maintain an anatomical reduction. In our experience, this technique has been used in conjunction with the standard Kocher-Langenbeck exposure and posterior column plating techniques.

  9. Interference screw position and hamstring graft location for anterior cruciate ligament reconstruction.

    PubMed

    Simonian, P T; Sussmann, P S; Baldini, T H; Crockett, H C; Wickiewicz, T L

    1998-01-01

    Anterior cruciate ligament reconstruction with hamstring tendon graft and interference screw fixation has recently been considered. Concerns for the use of interference screws with soft tissue grafts include damage to the graft during screw insertion, decreased fixation strength, and a decrease in the bone-tendon contact area for healing within the tunnel when the screw is placed in an eccentric position. This last concern could be addressed by placing the interference screw centrally between the four limbs of the hamstring graft. The purpose of this study was to determine the mode of failure, the pullout force, and graft slippage before graft fixation failure of hamstring tendons fixed with an interference screw positioned eccentrically in relation to the hamstring tendons verses an interference screw positioned centrally between the four graft limbs. The semitendinosus and gracilis tendons were harvested from six, fresh cadaveric specimens. Each tendon was divided into two segments of equal length. Both the semitendinosus and gracilis tendon segments were looped to form four strands. The specimens were then fixed with a bioabsorbable interference screw in the two different positions and pulled from a standardized polyurethane foam. All tendons in both groups failed by pulling out from between the interference screw and tunnel, regardless of the screw position. No tendon was cut by the screw in either group. There was no significant difference between the forces required to produce specific amounts of graft slippage between the two fixation techniques tested. There was no significant difference between the average total slippage at maximum pullout, 11.8 mm for the screw placed in the eccentric position and 13.7 mm for the screw placed in the central position. The maximum pullout force averaged 265.3 N for the screw placed in the eccentric position, and 244.7 N for the screw placed in the central position; these values were not significantly different. Placement of

  10. “Ride-on” technique and other simple and logical solutions to counter most common complications of silicone implants in augmentation rhinoplasty

    PubMed Central

    Agrawal, Kapil S.; Bachhav, Manoj V.; Naik, Charudatta S.; Gupta, Shikha; Sarda, Anup V.; Desai, Vyoma

    2015-01-01

    Augmentation rhinoplasty can be carried out using a wide range of materials including autologous bone and/or cartilage as well as alloplasts. Use of biologic bone and cartilage grafts results in lower infection rates, but they are associated with long-term resorption and donor-site morbidity. Alloplastic materials, in particular silicone, have been associated in literature with extrusion, necrosis of the tip, mobility and deviation or displacement of the implant, immobile nasal tip and infection. However, they have the advantages of being readily available and easy to reshape with no requirement for harvesting autografts. Aim: To overcome these problems associated with silicone implants for which the authors have devised a novel technique, the “rideon technique”. Materials and Methods: The present study was carried out on 11 patients over a period of 4 years. The authors have devised a simple technique to fix the silicone implant and retain it in place. Restricting the implant to only dorsum avoided common complications related to the silicone implant. Results: The authors have used this technique in 11 patients with encouraging results. Follow-up ranged from 12 months to 36 months during which patients were assessed for implant mobility, implant extrusion and tip necrosis. There was no incidence of above mentioned complications in these patients. Conclusion: The “rideon technique” provides excellent stability to silicone implants and restricting the implant only to dorsum not only eliminates chances of tip necrosis and thus implant extrusion but also maintains natural shape, feel and mobility of the tip. PMID:26424982

  11. Combining of small fragment screws and large fragment plates for open reduction and internal fixation of periprosthetic humeral fractures.

    PubMed

    Seybold, Dominik; Citak, Mustafa; Königshausen, Matthias; Gessmann, Jan; Schildhauer, Thomas A

    2011-10-01

    Operative treatment of periprosthetic humeral fractures in elderly patients with osteoporotic bone requires a stable fixations technique. The combination of 3.5 cortical screws with washers in a 4.5 Arbeitsgemeinschaft für Osteosynthesefragen, Limited-contact dynamic compression plate or Locking plate, allows a stable periprosthetic fixation with the small 3.5 screws and 4.5 screws above and below the prosthesis, respectively. This combination is a cost-effective technique to treat periprosthetic humeral fractures.

  12. Anatomic Study of Anterior Transdiscal Axial Screw Fixation for Subaxial Cervical Spine Injuries

    PubMed Central

    Ji, Wei; Zheng, Minghui; Qu, Dongbin; Zou, Lin; Chen, Yongquan; Chen, Jianting; Zhu, Qingan

    2016-01-01

    Abstract Anterior transdiscal axial screw (ATAS) fixation is an alternative or supplement to the plate and screw constructs for the upper cervical spine injury. However, no existing literatures clarified the anatomic feasibility of this technique for subaxial cervical spine. Therefore, the objective of this study was to evaluate the anatomical feasibility and to establish guidelines for the use of the ATAS fixation for the subaxial cervical spine injury. Fifty normal cervical spines had radiographs to determine the proposed screw trajectory (the screw length and insertion angle) and the interbody graft-related parameters (the disc height and depth, and the distance between anterior vertebral margin and the screw) for all levels of the subaxial cervical spine. Following screw insertion in 8 preserved human cadaver specimens, surgical simulation and dissection verified the feasibility and safety of the ATAS fixation. Radiographic measurements showed the mean axial screw length and cephalic incline angle of all levels were 41.2 mm and 25.2°, respectively. The suitable depth of the interbody graft was >11.7 mm (the distance between anterior vertebral margin and the screw), but <17.1 mm (disc depth). Except the axial screw length, increase in all the measurements was seen with level up to C5–C6 segment. Simulated procedure in the preserved specimens demonstrated that ATAS fixation could be successfully performed at C2–C3, C3–C4, C4–C5, and C5–C6 levels, but impossible at C6–C7 due to the obstacle of the sternum. All screws were placed accurately. None of the screws penetrated into the spinal canal and caused fractures determined by dissecting the specimens. The anterior transdiscal axial screw fixation, as an alternative or supplementary instrumentation for subaxial cervical spine injuries, is feasible and safe with meticulous surgical planning. PMID:27495016

  13. Cement augmentation of the acetabulum for revision total hip arthroplasty for infection.

    PubMed

    Rogers, Benedict A; Kuchinad, R; Garbedian, S; Backstein, D; Gross, A E; Safir, O A

    2015-02-01

    Antibiotic-loaded cement spacers in first-stage revision hip arthroplasty for infection are associated with a high dislocation and fracture rate. This technical note describes a novel surgical technique, utilizing screws and cement, improving acetabular coverage and reducing the risk of mechanical failure. Fifteen infected hip prostheses underwent removal, cement acetabular augmentation and insertion of a femoral cement spacer. Eleven hips had successful infection eradication and subsequently underwent a second stage revision procedure a mean duration of 15 weeks (9-48) after the first stage. No dislocations or fractures of the cement spacers were observed. This technique affords the potential to reduce the duration of time cement spacers remaining in situ, provides enhanced mechanical stability and improved antibiotic elution through cement-on-cement articulation.

  14. Simultaneous Use of Both Bilateral Intralaminar and Pedicle Screws for C2 Stabilization.

    PubMed

    Tarukado, Kiyoshi; Tono, Osamu; Doi, Toshio

    2015-10-01

    Four patients underwent stabilization surgery using both bilateral C2 pedicle screw (PS) and intralaminar screw (LS). Neural and vascular injury resulting from incorrect screw placement was assessed using computed tomography (CT). The evaluation of bone union was assessed by lateral flexion-extension X-ray films and CT. The symptoms were improved in all patients. There were no intraoperative complications. Furthermore, there were no cases of neurological worsening or vascular injury from incorrect screw placement. Failure of instrumentation or screw loosening during the follow-up period did not occur in any of the patients. All cases had accomplished bone union at the final follow-up. Theoretically, the stabilization technique using both bilateral C2 PS and LS at the same time can provide more stability than any other single technique. Simultaneous use of both bilateral C2 PS and LS is potentially a good choice for surgical repair. PMID:26435800

  15. Enhancement of pedicle screw stability using calcium phosphate cement in osteoporotic vertebrae: in vivo biomechanical study.

    PubMed

    Taniwaki, Yoshimichi; Takemasa, Ryuichi; Tani, Toshikazu; Mizobuchi, Hiroo; Yamamoto, Hiroshi

    2003-01-01

    We conducted an experimental study using female beagles with and without ovariectomy-induced osteoporosis to determine the effect of calcium phosphate cement (CPC) on the mechanical stability of inserted pedicle screws. A drill hole was created from the base of the transverse process to the vertebral body; CPC was injected into the hole, and then a screw was inserted into the same hole. In the presence of osteoporosis evidenced by dual X-ray absorptiometry, the stability of the inserted screw augmented by CPC against pull-out and cephalocaudal forces were significantly greater by 28% and 54% at 1 week after operation, 48% and 71% at 2 weeks, and 56% and 68% at 4 weeks compared with those without CPC. The pull-out strength increased progressively with time after surgery, probably reflecting new-bone growth from the surrounding cancellous bone, which was in direct contact with the CPC, as shown in the histologic study. At each time point the cephalocaudal rigidity was similar and the pull-out strength greater than that for the screws inserted without CPC in nonporotic dogs. These findings suggest that CPC augments the stability of the inserted pedicle screws and increases the stiffness of fixed osteoporotic motion segments using instrumentation. PMID:12768486

  16. Cement augmentation of implants--no general cure in osteoporotic fracture treatment. A biomechanical study on non-displaced femoral neck fractures.

    PubMed

    Hofmann-Fliri, Ladina; Nicolino, Tomas I; Barla, Jorge; Gueorguiev, Boyko; Richards, R Geoff; Blauth, Michael; Windolf, Markus

    2016-02-01

    Femoral neck fractures in the elderly are a common problem in orthopedics. Augmentation of screw fixation with bone cement can provide better stability of implants and lower the risk of secondary displacement. This study aimed to investigate whether cement augmentation of three cannulated screws in non-displaced femoral neck fractures could increase implant fixation. A femoral neck fracture was simulated in six paired human cadaveric femora and stabilized with three 7.3 mm cannulated screws. Pairs were divided into two groups: conventional instrumentation versus additional cement augmentation of screw tips with 2 ml TraumacemV+ each. Biomechanical testing was performed by applying cyclic axial load until failure. Failure cycles, axial head displacement, screw angle changes, telescoping and screw cut-out were evaluated. Failure (15 mm actuator displacement) occurred in the augmented group at 12,500 cycles (± 2,480) compared to 15,625 cycles (± 4,215) in the non-augmented group (p = 0.041). When comparing 3 mm vertical displacement of the head no significant difference (p = 0.72) was detected between the survival curves of the two groups. At 8,500 load-cycles (early onset failure) the augmented group demonstrated a change in screw angle of 2.85° (± 0.84) compared to 1.15° (± 0.93) in the non-augmented group (p = 0.013). The results showed no biomechanical advantage with respect to secondary displacement following augmentation of three cannulated screws in a non-displaced femoral neck fracture. Consequently, the indication for cement augmentation to enhance implant anchorage in osteoporotic bone has to be considered carefully taking into account fracture type, implant selection and biomechanical surrounding. PMID:26177609

  17. Role of oxygen at screw dislocations in GaN.

    PubMed

    Arslan, I; Browning, N D

    2003-10-17

    Here we report the first direct atomic scale experimental observations of oxygen segregation to screw dislocations in GaN using correlated techniques in the scanning transmission electron microscope. The amount of oxygen present in each of the three distinct types of screw dislocation core is found to depend on the evolution and structure of the core, and thus gives rise to a varying concentration of localized states in the band gap. Contrary to previous theoretical predictions, the substitution of oxygen for nitrogen is observed to extend over many monolayers for the open core dislocation. PMID:14611410

  18. Comparison of two-transsacral-screw fixation versus triangular osteosynthesis for transforaminal sacral fractures.

    PubMed

    Min, Kyong S; Zamorano, David P; Wahba, George M; Garcia, Ivan; Bhatia, Nitin; Lee, Thay Q

    2014-09-01

    Transforaminal pelvic fractures are high-energy injuries that are translationally and rotationally unstable. This study compared the biomechanical stability of triangular osteosynthesis vs 2-transsacral-screw fixation in the repair of a transforaminal pelvic fracture model. A transforaminal fracture model was created in 10 cadaveric lumbopelvic specimens. Five of the specimens were stabilized with triangular osteosynthesis, which consisted of unilateral L5-to-ilium lumbopelvic fixation and ipsilateral iliosacral screw fixation. The remaining 5 were stabilized with a 2-transsacral-screw fixation technique that consisted of 2 transsacral screws inserted across S1. All specimens were loaded cyclically and then loaded to failure. Translation and rotation were measured using the MicroScribe 3D digitizing system (Revware Inc, Raleigh, North Carolina). The 2-transsacral-screw group showed significantly greater stiffness than the triangular osteosynthesis group (2-transsacral-screw group, 248.7 N/mm [standard deviation, 73.9]; triangular osteosynthesis group, 125.0 N/mm [standard deviation, 66.9]; P=.02); however, ultimate load and rotational stiffness were not statistically significant. Compared with triangular osteosynthesis fixation, the use of 2 transsacral screws provides a comparable biomechanical stability profile in both translation and rotation. This newly revised 2-transsacral-screw construct offers the traumatologist an alternative method of repair for vertical shear fractures that provides biplanar stability. It also offers the advantage of percutaneous placement in either the prone or supine position.

  19. Metacarpophalangeal and interphalangeal joint arthrodesis: a comparative study between tension band and compression screw fixation.

    PubMed

    Breyer, J M; Vergara, P; Parra, L; Sotelo, P; Bifani, A; Andrade, F

    2015-05-01

    A retrospective, comparative cohort study was performed of metacarpophalangeal or proximal interphalangeal joint arthrodesis with either tension band (n = 28) or compression (Acutrak Mini) screw (n = 29) methods. We compared rate of union, healing time, complications, and re-operation rate. Union was achieved in 26/28 (92.8%) of the tension band group (9.4 weeks) and 24/28 (85.7%) of the compression screw group (9.8 weeks). Only 28 patients in the screw group were assessed for union as one patient in the screw group sustained a fracture at the time of insertion and was converted to tension band fixation. The complication rate was 8/28 (28.6%) in the tension band group and 8/29 (27.6%) in the compression screw group. Re-operation rate was 9/28 (32.1%) in the tension band group and 1/29 (3.6%) in the compression screw group. Our findings indicate that bone healing, healing time, and complications are similar in both groups. The tension band technique had a significantly higher re-operation rate (hardware removal), but was the technique for salvage following failure of the screw technique.

  20. 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

  1. Lumbosacral fixation using the diagonal S2 screw for long fusion in degenerative lumbar deformity: technical note involving 13 cases.

    PubMed

    Park, Ye-Soo; Kim, Hong-Sik; Baek, Seung-Wook; Lee, Sang-Hyun

    2013-09-01

    Placing instrumentation into the ilium has been shown to increase the biomechanical stability and the fusion rates, but it has some disadvantages. The diagonal S2 screw technique is an attractive surgical procedure for degenerative lumbar deformity. Between 2008 and 2010, we carried out long fusion across the lumbosacral junction in 13 patients with a degenerative lumbar deformity using the diagonal S2 screws. In 12 of these 13 patients, the lumbosacral fusion was graded as solid fusion with obvious bridging bone (92%). One patient had a rod dislodge at one S2 screw and breakage of one S1 screw and underwent revision nine months postoperatively. So, we present alternative method of lumbopelvic fixation for long fusion in degenerative lumbar deformity using diagonal S2 screw instead of iliac screw.

  2. Cancellous Screws Are Biomechanically Superior to Cortical Screws in Metaphyseal Bone.

    PubMed

    Wang, Tim; Boone, Christopher; Behn, Anthony W; Ledesma, Justin B; Bishop, Julius A

    2016-09-01

    Cancellous screws are designed to optimize fixation in metaphyseal bone environments; however, certain clinical situations may require the substitution of cortical screws for use in cancellous bone, such as anatomic constraints, fragment size, or available instrumentation. This study compares the biomechanical properties of commercially available cortical and cancellous screw designs in a synthetic model representing various bone densities. Commercially available, fully threaded, 4.0-mm outer-diameter cortical and cancellous screws were tested in terms of pullout strength and maximum insertion torque in standard-density and osteoporotic cancellous bone models. Pullout strength and maximum insertion torque were both found to be greater for cancellous screws than cortical screws in all synthetic densities tested. The magnitude of difference in pullout strength between cortical and cancellous screws increased with decreasing synthetic bone density. Screw displacement prior to failure and total energy absorbed during pullout strength testing were also significantly greater for cancellous screws in osteoporotic models. Stiffness was greater for cancellous screws in standard and osteoporotic models. Cancellous screws have biomechanical advantages over cortical screws when used in metaphyseal bone, implying the ability to both achieve greater compression and resist displacement at the screw-plate interface. Surgeons should preferentially use cancellous over cortical screws in metaphyseal environments where cortical bone is insufficient for fixation. [Orthopedics.2016; 39(5):e828-e832.].

  3. Biomechanical and finite element analyses of bone cement-Injectable cannulated pedicle screw fixation in osteoporotic bone.

    PubMed

    Liu, Yaoyao; Xu, Jianzhong; Sun, Dong; Luo, Fei; Zhang, Zehua; Dai, Fei

    2016-07-01

    The objectives of this study were to investigate the safety and biomechanical stability of a polymethylmethacrylate (PMMA)-augmented bone cement-injectable cannulated pedicle screw (CICPS) in cancellous bone model, and to analyze the stress distribution at the screw-cement-bone interface. The OMEGA cannulated pedicle screw (OPS) and conventional pedicle screw (CPS) were used as control groups. Safety of the CICPS was evaluated by the static bending and bending fatigue tests. Biomechanical stability was analyzed by the maximum axial pullout strength and maximum torque tests. Stress distribution at the screw-cement-bone interface was analyzed by the finite element (FE) method. The CICPS and CPS produced statistically similar values for bending stiffness, bending structural stiffness, and bending yield moment. The maximum pullout force was 53.47 ± 8.65 N in CPS group, compared to 130.82 ± 7.32 N and 175.45 ± 43.01 N in the PMMA-augmented OPS and CICPS groups, respectively (p < 0.05). The CICPS had a significantly greater torque than the OPS and CPS. The FE model did not reveal excessive stress at the screw-cement-bone interface in the CICPS group. In conclusion, PMMA-augmentation with CICPS may be a potentially useful method to increase the stability of pedicle screws in patients with osteoporosis. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 960-967, 2016. PMID:25976272

  4. Augmentation cystoplasty in neurogenic bladder.

    PubMed

    Çetinel, Bülent; Kocjancic, Ervin; Demirdağ, Çetin

    2016-09-01

    The aim of this review is to update the indications, contraindications, technique, complications, and the tissue engineering approaches of augmentation cystoplasty (AC) in patients with neurogenic bladder. PubMed/MEDLINE was searched for the keywords "augmentation cystoplasty," "neurogenic bladder," and "bladder augmentation." Additional relevant literature was determined by examining the reference lists of articles identified through the search. The update review of of the indications, contraindications, technique, outcome, complications, and tissue engineering approaches of AC in patients with neurogenic bladder is presented. Although some important progress has been made in tissue engineering AC, conventional AC still has an important role in the surgical treatment of refractory neurogenic lower urinary tract dysfunction. PMID:27617312

  5. Augmentation cystoplasty in neurogenic bladder

    PubMed Central

    Kocjancic, Ervin; Demirdağ, Çetin

    2016-01-01

    The aim of this review is to update the indications, contraindications, technique, complications, and the tissue engineering approaches of augmentation cystoplasty (AC) in patients with neurogenic bladder. PubMed/MEDLINE was searched for the keywords "augmentation cystoplasty," "neurogenic bladder," and "bladder augmentation." Additional relevant literature was determined by examining the reference lists of articles identified through the search. The update review of of the indications, contraindications, technique, outcome, complications, and tissue engineering approaches of AC in patients with neurogenic bladder is presented. Although some important progress has been made in tissue engineering AC, conventional AC still has an important role in the surgical treatment of refractory neurogenic lower urinary tract dysfunction. PMID:27617312

  6. Comparison of open and percutaneous lumbar pedicle screw revision rate using 3-D image guidance and intraoperative CT.

    PubMed

    Santos, Edward Rainier G; Sembrano, Jonathan N; Yson, Sharon C; Polly, David W

    2015-02-01

    Complications arising from a malpositioned screw can be both devastating and costly. The incidence of neurologic injury secondary to a malpositioned screw is reported to be as high as 7% to 12%. The advancement of image-guided technology has allowed surgeons to place screws more accurately and confirm correct placement prior to leaving the operating room. Only a small number of studies have examined image-guided pedicle screw accuracy in terms of intraoperative revision and reoperation rates. The purpose of this study was to determine the intraoperative revision and return to surgery rates for navigated lumbar pedicle screws and to compare navigated open and percutaneous techniques. The authors reviewed 199 cases of 3-dimensional image-guided lumbar pedicle screw instrumentation from November 2006 to December 2011. Screw or K-wire removal, repositioning, or eventual abandonment of insertion were noted. Chi-square test was used to determine statistical significance in rates between the 2 groups (alpha=0.05). The authors also noted return to surgery secondary to complications from a malpositioned screw. The overall intraoperative revision rate of navigated lumbar pedicle screws was 4.6%. There were significantly more revisions in the percutaneously inserted screws (7.5%) than with the open technique (2.7%) (P=.0004). If K-wire revisions are excluded, there was no statistically significant difference in intraoperative revision rates between the percutaneous and open groups (2.1% vs 2.7%, respectively) (P=.0004). No patients underwent reoperation for a malpositioned screw. This technology has virtually eliminated the need for reoperation for screw malposition. It may suggest a more cost-effective way of preventing neurovascular injuries and revision surgeries.

  7. Hydroxyapatite and fluorapatite coatings on dental screws: effects of blast coating process and biological response.

    PubMed

    Dunne, Conor F; Twomey, Barry; Kelly, Ciara; Simpson, Jeremy C; Stanton, Kenneth T

    2015-01-01

    This paper describes the deposition of hydroxyapatite (HA) and fluorapatite (FA) onto titanium dental screws using a novel ambient temperature coating technique named CoBlast. The process utilises a coating medium and a blast medium sprayed simultaneously at the substrate surface. The blast medium was a sintered apatite (sHA) and two particles sizes (<106 and <180 µm) were used to assess their influence on the coating process. The influence of the coating process on the coating composition, coating adhesion, screw morphology and screw microstructure was examined. XRD analysis revealed the coating crystallinity was the same as the original HA and FA feedstock powders. Examining the screw's morphology, the threads of the CoBlasted screws exhibited rounding compared to the unmodified screw. This is due to the abrasive nature of the CoBlast process. The degree of rounding was more significant for the screws blasted with the 180 µm sHA than the 106 µm sHA. The blast media particle size significantly influences the surface roughness of both the substrate and coating and the microstructure of the substrate. The screws did not exhibit any loss of coating after insertion into a model bone material, indicating that the coating was strongly adhered to the substrate. There was no statistically significant difference in cell attachment and cell morphology on the unmodified substrates compared to the coated substrates. In conclusion, the CoBlast process can be used to deposit HA and FA onto complex geometries such as dental screws. The choice of blast medium particle size influences the screws morphology. The coating process does not negatively impact on the cell attachment and morphology in vitro.

  8. Screw-fed pump system

    SciTech Connect

    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.

  9. 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.

  10. Stress concentrations in screw threads

    NASA Technical Reports Server (NTRS)

    Ohara, G. P.

    1980-01-01

    The concept of stress concentration in screw threads was defined using the sheer transfer rate as the fundamental quantity. The stress concentration is plotted for a fixed geometry. The Heywood equation was used to generate the basic plots and NASTRAN was used to extend the analysis to the case both where flanks of an individual thread tooth are in contact. The case where a finite axial stress is superimposed is discussed.

  11. 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

  12. Screw-retained crown restorations of single implants: A step-by-step clinical guide

    PubMed Central

    Assaf, Mohammad; Gharbyeh, Alaa’ Z. Abu

    2014-01-01

    This paper shows the clinical steps for preparing a screw-retained crown for the restoration of a single implant. Impression-taking using open-tray technique and delivery of the crown is presented in a step-by-step manner elucidated by detailed photographs. Furthermore, the advantages and disadvantages of screw-retained crowns are discussed in comparison with the cemented restorations. PMID:25512742

  13. Biomechanical effects of plate area and locking screw on medial open tibial osteotomy.

    PubMed

    Luo, Chu-An; Lin, Shang-Chih; Hwa, Su-Yang; Chen, Chun-Ming; Tseng, Ching-Shiow

    2015-01-01

    Medial open high tibial osteotomy (HTO) has been used to treat osteoarthritis of the medial compartment of the knee. However, weaker plate strength, unstable plate/screw junction and improper surgery technique are highly related to the HTO outcomes. Two π-shape plates were designed and eight variations (two supporting area × four locking stiffness) were compared by finite-element method. The computed tomography-based tibia was reconstructed and both wedge micromotion and implant stresses were chosen as the comparison indices. The construct was subjected to surgical and physiological loads. The medial-posterior region is the most loaded region and the load through the posterior leg is about four times that through the anterior leg. This indicates that the two-leg design can form a force-couple mechanism to effectively reduce the implant stresses. The use of locking screws significantly decrease the screw and hole stresses. However, the extending plate reduces the stresses of screws and holes above the wedge but makes the distal screws and holes much stressed. Wedge micromotion is affected by extending plate rather than locking screw. Three factors contribute to effective stabilisation of unstable HTO wedge: (1) intimate tibia-plate contact at medial-posterior regions, (2) sufficient rigidity at plate-screw junctions and (3) effective moment-balancing design at distal tibia-plate interfaces.

  14. Mechanical Comparison of Headless Screw Fixation and Locking Plate Fixation for Talar Neck Fractures.

    PubMed

    Karakasli, Ahmet; Hapa, Onur; Erduran, Mehmet; Dincer, Cemal; Cecen, Berivan; Havitcioglu, Hasan

    2015-01-01

    For talar neck fractures, open reduction and internal fixation have been thought to facilitate revascularization and prevent osteonecrosis. Newer screw systems allow for placement of cannulated headless screws, which provide compression by virtue of a variable pitch thread. The present study compared the biomechanical fixation strength of cannulated headless variable-pitch screw fixation and locking plate fixation. A reproducible talar neck fracture was created in 14 fresh cadaver talar necks. Talar head fixation was then performed using 2 cannulated headless variable-pitch 4-mm/5-mm diameter (4/5) screws (Acutrak; Acumed, Hillsboro, OR) and locking plate fixation. Headless variable-pitch screw fixation had lower failure displacement than did locking plate fixation. No statistically significant differences were found in failure stiffness, yield stiffness (p = .655), yield load (p = .142), or ultimate load between the 2 fixation techniques. Cannulated headless variable-pitch screw fixation resulted in better failure displacement than locking plate fixation in a cadaveric talus model and could be considered a viable option for talus fracture fixation. Headless, fully threaded, variable-pitch screw fixation has inherent advantages compared with locking plate fixation, because it might cause less damage to the articular surface and can compress the fracture for improved reduction. Additionally, plate fixation can increase the risk of avascular necrosis owing to the wider incision and dissection of soft tissues.

  15. Early clinical results with cortically based pedicle screw trajectory for fusion of the degenerative lumbar spine.

    PubMed

    Glennie, R Andrew; Dea, Nicolas; Kwon, Brian K; Street, John T

    2015-06-01

    This study reviews the outcomes and revision rates of degenerative lumbar fusion surgery using cortical trajectory pedicle screws in lieu of traditional pedicle screw instrumentation. Pedicle screw fixation can be a challenge in patients with low bone mineral density. Wide posterior approaches to the lumbar spine exposing lateral to the facet joints and onto transverse processes causes an additional degree of muscular damage and blood loss not present with a simple laminectomy. A cortical bone trajectory pedicle screw has been proposed as an alternative to prevent screw pullout and decrease the morbidity associated with the wide posterior approach to the spine. We present a series of eight consecutive patients using a cortical bone trajectory instead of traditional pedicle screw fixation for degenerative conditions of the lumbar spine. A retrospective review of our institutional registry data identified eight patients who had cortical screws placed with the assistance of O-arm Stealth navigation (Medtronic Sofamor Danek, Memphis, TN, USA) from 2010-2013. We analyzed the need for revision, the maintenance of reduction and the incidence of screw pullout or breakage. Our review demonstrated that two of eight patients were revised at an average of 12months. The reasons for these revisions were pseudarthrosis and caudal adjacent segment failure. All patients who were revised had frank screw loosening. We present early clinical results of a new technique that has been shown to have a better fixation profile in laboratory testing. Our less than favorable early clinical results should be interpreted with caution and highlight important technical issues which should be considered.

  16. Minimally Invasive Lumbar Pedicle Screw Fixation Using Cortical Bone Trajectory – A Prospective Cohort Study on Postoperative Pain Outcomes

    PubMed Central

    Deb, Sayantan; Pham, Lan; Singh, Harminder

    2016-01-01

    Objective: Our study aims to evaluate the clinical outcomes of cortical screws in regards to postoperative pain. Background: Pedicle screw fixation is the current mainstay technique for posterior spinal fusion. Over the past decade, a new technique called cortical screw fixation has been developed, which allows for medialized screw placement through stronger cortical bone. There have been several studies that showed either biomechanical equivalence or superiority of cortical screws. However, there is currently only a single study in the literature looking at clinical outcomes of cortical screw fixation in patients who have had no prior spine surgery. Methods: We prospectively looked at the senior author’s patients who underwent cortical versus pedicle lumbar screw fixation surgeries between 2013 and 2015 for lumbar degenerative disease. Eighteen patients underwent cortical screw fixation, and 15 patients underwent traditional pedicle screw fixation. We looked at immediate postoperative pain, changes in short-term pain (six to 12 weeks post-surgery), and changes in long-term pain (six to eight months). All pain outcomes were measured using a visual analog scale ranging from 1 to 10. Mann-Whitney or Kruskal-Wallis tests were used to measure continuous data, and the Fisher Exact test was used to measure categorical data as appropriate. Results: Our results showed that the cortical screw cohort showed a trend towards having less peak postoperative pain (p = 0.09). The average postoperative pain was similar between the two cohorts (p = 0.93). There was also no difference in pain six to 12 weeks after surgery (p = 0.8). However, at six to eight months, the cortical screw cohort had worse pain compared to the pedicle screw cohort (p = 0.02). Conclusions: The cortical screw patients showed a trend towards less peak pain in the short-term (one to three days post-surgery) and more pain in the long-term (six to eight months post-surgery) compared to pedicle screw patients

  17. Minimally Invasive Lumbar Pedicle Screw Fixation Using Cortical Bone Trajectory – A Prospective Cohort Study on Postoperative Pain Outcomes

    PubMed Central

    Deb, Sayantan; Pham, Lan; Singh, Harminder

    2016-01-01

    Objective: Our study aims to evaluate the clinical outcomes of cortical screws in regards to postoperative pain. Background: Pedicle screw fixation is the current mainstay technique for posterior spinal fusion. Over the past decade, a new technique called cortical screw fixation has been developed, which allows for medialized screw placement through stronger cortical bone. There have been several studies that showed either biomechanical equivalence or superiority of cortical screws. However, there is currently only a single study in the literature looking at clinical outcomes of cortical screw fixation in patients who have had no prior spine surgery. Methods: We prospectively looked at the senior author’s patients who underwent cortical versus pedicle lumbar screw fixation surgeries between 2013 and 2015 for lumbar degenerative disease. Eighteen patients underwent cortical screw fixation, and 15 patients underwent traditional pedicle screw fixation. We looked at immediate postoperative pain, changes in short-term pain (six to 12 weeks post-surgery), and changes in long-term pain (six to eight months). All pain outcomes were measured using a visual analog scale ranging from 1 to 10. Mann-Whitney or Kruskal-Wallis tests were used to measure continuous data, and the Fisher Exact test was used to measure categorical data as appropriate. Results: Our results showed that the cortical screw cohort showed a trend towards having less peak postoperative pain (p = 0.09). The average postoperative pain was similar between the two cohorts (p = 0.93). There was also no difference in pain six to 12 weeks after surgery (p = 0.8). However, at six to eight months, the cortical screw cohort had worse pain compared to the pedicle screw cohort (p = 0.02). Conclusions: The cortical screw patients showed a trend towards less peak pain in the short-term (one to three days post-surgery) and more pain in the long-term (six to eight months post-surgery) compared to pedicle screw patients

  18. Twin-Screw Extruders in Ceramic Extrusion

    NASA Astrophysics Data System (ADS)

    Wiedmann, Werner; Hölzel, Maria

    The machines mainly used for compounding plastics, chemicals and food are co-rotating, closely intermeshing twin-screw extruders. Some 30 000 such extruders are in use worldwide, about 1/3 are ZSKs from Coperion Werner & Pfleiderer, Stuttgart. In the chemical industry more and more batch mixers are being replaced by continuous twin-screw kneaders.

  19. Visualization and understanding of the granulation liquid mixing and distribution during continuous twin screw granulation using NIR chemical imaging.

    PubMed

    Vercruysse, Jurgen; Toiviainen, Maunu; Fonteyne, Margot; Helkimo, Niko; Ketolainen, Jarkko; Juuti, Mikko; Delaet, Urbain; Van Assche, Ivo; Remon, Jean Paul; Vervaet, Chris; De Beer, Thomas

    2014-04-01

    Over the last decade, there has been increased interest in the application of twin screw granulation as a continuous wet granulation technique for pharmaceutical drug formulations. However, the mixing of granulation liquid and powder material during the short residence time inside the screw chamber and the atypical particle size distribution (PSD) of granules produced by twin screw granulation is not yet fully understood. Therefore, this study aims at visualizing the granulation liquid mixing and distribution during continuous twin screw granulation using NIR chemical imaging. In first instance, the residence time of material inside the barrel was investigated as function of screw speed and moisture content followed by the visualization of the granulation liquid distribution as function of different formulation and process parameters (liquid feed rate, liquid addition method, screw configuration, moisture content and barrel filling degree). The link between moisture uniformity and granule size distributions was also studied. For residence time analysis, increased screw speed and lower moisture content resulted to a shorter mean residence time and narrower residence time distribution. Besides, the distribution of granulation liquid was more homogenous at higher moisture content and with more kneading zones on the granulator screws. After optimization of the screw configuration, a two-level full factorial experimental design was performed to evaluate the influence of moisture content, screw speed and powder feed rate on the mixing efficiency of the powder and liquid phase. From these results, it was concluded that only increasing the moisture content significantly improved the granulation liquid distribution. This study demonstrates that NIR chemical imaging is a fast and adequate measurement tool for allowing process visualization and hence for providing better process understanding of a continuous twin screw granulation system.

  20. Combining of small fragment screws and large fragment plates for open reduction and internal fixation of periprosthetic humeral fractures

    PubMed Central

    Seybold, Dominik; Citak, Mustafa; Königshausen, Matthias; Gessmann, Jan; Schildhauer, Thomas A.

    2011-01-01

    Operative treatment of periprosthetic humeral fractures in elderly patients with osteoporotic bone requires a stable fixations technique. The combination of 3.5 cortical screws with washers in a 4.5 Arbeitsgemeinschaft für Osteosynthesefragen, Limited-contact dynamic compression plate or Locking plate, allows a stable periprosthetic fixation with the small 3.5 screws and 4.5 screws above and below the prosthesis, respectively. This combination is a cost-effective technique to treat periprosthetic humeral fractures. PMID:22223961

  1. Safe Removal of a Broken Abutment Screw with Customized Drill Guide and Rotary Instrument: A Clinical Report.

    PubMed

    Yoon, Joon-Ho; Lee, Heeje; Kim, Man-Yong

    2016-02-01

    This clinical report introduces a method for safe retrieval of a broken implant abutment screw. A reverse-tapping rotary instrument has been introduced in the market and is widely used to retrieve broken screws; however, it is difficult to use the rotary instrument unless an access hole for engagement of the rotary instrument is positioned directly on the center of the top of the broken screw remnant. Poor visibility is another limitation to make an access hole. To keep the position of the rotary instrument at the center of the broken screw, a customized drill guide was fabricated, modifying an implant impression coping with self-cured acrylic resin, all easily found in daily practice. The broken screw was easily removed, not damaging the internal threads of the implant. This technique could be applied to most implant systems when a specific removal kit for each implant system is not prepared.

  2. Optical screw-wrench for interlocking 2PP-microstructures

    NASA Astrophysics Data System (ADS)

    Köhler, J.; Zyla, G.; Ksouri, S. I.; Esen, C.; Ostendorf, A.

    2016-03-01

    Two-photon polymerization (2PP) has emerged as a powerful platform for processing three-dimensional microstructures with high resolution. Furthermore, by adding nanoparticles of different materials to the photopolymer the microstructures can be functionalized, e.g. magnetic or electric properties can be adjusted. However, to combine different functions within one microstructure or to manufacture complex microsystems, assembling techniques for multiple 2PP written building blocks are required. In this paper a qualitative approach for assembling microstructures utilizing optical forces is presented. Therefore, screw and nut shaped microstructures are produced by 2PP-technique and screwed together using a holographic optical tweezer (HOT). The interlocking structures are trapped and rotated into each other to cause connection. In this paper the used parameters and possible designs of the interlocking connection are discussed. These findings provide not only the assembling of building blocks to complex microstructures, rather different functionalized 2PP-microstructures can be combined by simply screwing them together with the use of optical forces.

  3. 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.

  4. Comparison of Achilles tendon repair techniques in a sheep model using a cross-linked acellular porcine dermal patch and platelet-rich plasma fibrin matrix for augmentation.

    PubMed

    Sarrafian, Tiffany L; Wang, Hali; Hackett, Eileen S; Yao, Jian Q; Shih, Mei-Shu; Ramsay, Heather L; Turner, A Simon

    2010-01-01

    The primary goal of this study was to evaluate a cross-linked acellular porcine dermal patch (APD), as well as platelet-rich plasma fibrin matrix (PRPFM), for repair of acute Achilles tendon rupture in a sheep model. The 2 surgically transected tendon ends were reapproximated in groups 1 and 2, whereas a gap was left between the tendon ends in group 3. APD was used to reinforce the repair in group 2, and autologous PRPFM was used to fill the gap, which was also reinforced with APD, in group 3. All sheep were humanely euthanized at 24 weeks after the repair, and biomechanical and histological testing were performed. Tensile strength testing showed a statistically significant difference in elongation between the operated limb and the unoperated contralateral limb in groups 1 and 3, but not in group 2. All operated tendons appeared healed with no apparent fibrosis under light and polarized microscopy. In group 1, all surgical separation sites were identifiable, and healing occurred via increasing tendon thickness. In group 2, healing occurred with new tendon fibers across the separation, without increasing tendon thickness in 2 out of 6 animals. Group 3 showed complete bridging of the gap, with no change in tendon thickness in 2 out of 6 animals. In groups 2 and 3, peripheral integration of the APD to tendon fibers was observed. These findings support the use of APD, alone or with PRPFM, to augment Achilles tendon repair in a sheep model.

  5. Vertical-Screw-Auger Conveyer Feeder

    NASA Technical Reports Server (NTRS)

    Walton, Otis (Inventor); Vollmer, Hubert J. (Inventor)

    2016-01-01

    A conical feeder is attached to a vertically conveying screw auger. The feeder is equipped with scoops and rotated from the surface to force-feed regolith the auger. Additional scoops are possible by adding a cylindrical section above the conical funnel section. Such then allows the unit to collect material from swaths larger in diameter than the enclosing casing pipe of the screw auger. A third element includes a flexible screw auger. All three can be used in combination in microgravity and zero atmosphere environments to drill and recover a wide area of subsurface regolith and entrained volatiles through a single access point on the surface.

  6. Reinforcement of osteosynthesis screws with brushite cement.

    PubMed

    Van Landuyt, P; Peter, B; Beluze, L; Lemaître, J

    1999-08-01

    The fixation of osteosynthesis screws remains a severe problem for fracture repair among osteoporotic patients. Polymethyl-methacrylate (PMMA) is routinely used to improve screw fixation, but this material has well-known drawbacks such as monomer toxicity, exothermic polymerization, and nonresorbability. Calcium phosphate cements have been developed for several years. Among these new bone substitution materials, brushite cements have the advantage of being injectable and resorbable. The aim of this study is to assess the reinforcement of osteosynthesis screws with brushite cement. Polyurethane foams, whose density is close to that of cancellous bone, were used as bone model. A hole was tapped in a foam sample, then brushite cement was injected. Trabecular osteosynthesis screws were inserted. After 24 h of aging in water, the stripping force was measured by a pull-out test. Screws (4.0 and 6.5 mm diameter) and two foam densities (0.14 and 0.28 g/cm3) were compared. Cements with varying solid/liquid ratios and xanthan contents were used in order to obtain the best screw reinforcement. During the pull-out test, the stripping force first increases to a maximum, then drops to a steady-state value until complete screw extraction. Both maximum force and plateau value increase drastically in the presence of cement. The highest stripping force is observed for 6.5-mm screws reinforced with cement in low-density foams. In this case, the stripping force is multiplied by 3.3 in the presence of cement. In a second experiment, cements with solid/liquid ratio ranging from 2.0 to 3.5 g/mL were used with 6.5-mm diameter screws. In some compositions, xanthan was added to improve injectability. The best results were obtained with 2.5 g/mL cement containing xanthan and with 3.0 g/mL cements without xanthan. A 0.9-kN maximal stripping force was observed with nonreinforced screws, while 1.9 kN was reached with reinforced screws. These first results are very promising regarding screw

  7. Fluoroscopy-guided pedicle screw accuracy with a mini-open approach: a tomographic evaluation of 470 screws in 125 patients

    PubMed Central

    Soriano-Sánchez, José Antonio; Gutiérrez-Partida, Carlos Francisco; Ramírez-Barrios, Luis Rodolfo; Ortíz-Leyva, Ramses Uriel; Rodríguez-García, Manuel; Sánchez-Escandón, Oscar

    2015-01-01

    Background Transpedicular screws are currently placed with open free hand and minimally invasive techniques assisted with either fluoroscopy or navigation. Screw placement accuracy had been investigated with several methods reaching accuracy rates from 71.9% to 98.8%. The objective of this study was to assess the accuracy and safety for 2-D fluoroscopy-guided screw placement assisted with electrophysiological monitoring and the inter-observer agreement for the breach classification. Methods A retrospective review was performed on 125 consecutive patients who underwent minimally invasive transforaminal lumbar interbody fusion and transpedicular screws placement between the levels of T-12 and S-1. Screw accuracy was evaluated using a postoperative computed tomography by three independent observers. Pedicle breach was documented when there was a violation in any direction of the pedicle. Inter-observer agreement was assessed with the Kappa coefficient. Results A total of 470 transpedicular screws were evaluated between the levels of T-12 and S-1. In 57 patients the instrumentation was bilateral and in 68 unilateral. A substantial degree of agreement was found between the observers AB (κ=0.769) and A-C (κ=0.784) and almost perfect agreement between observers B-C (κ=0.928). There were a total of 427.33 (90.92%) screws without breach, 39.33 (8.37%) minor breach pedicles and 3.33 (0.71%) major breach pedicles. The pedicle breach rate was 9.08% Trajectory pedicle breach percentages were as follows: minor medial pedicle breach 4.68%, minor lateral pedicle breach 3.47%, minor inferior pedicle breach 0.22%, and major medial breach 0.70%. No intraoperative instrumentation-related or postoperative clinical complications were encountered and no surgical revision was needed. Conclusions Our study demonstrated a high accuracy (90.2%) for 2-D fluoroscopy-guided pedicle screw using electromonitoring. Only 0.71% of the 470 screws had a major breach. Knowing the radiological spine

  8. Effect of Off-Axis Screw Insertion, Insertion Torque, and Plate Contouring on Locked Screw Strength

    PubMed Central

    Gallagher, Bethany; Silva, Matthew J.; Ricci, William M.

    2015-01-01

    Objectives This study quantifies the effects of insertion torque, off-axis screw angulation, and plate contouring on the strength of locking plate constructs. Methods Groups of locking screws (n = 6–11 screws) were inserted at 50%, 100%, 150%, and 200% of the manufacturer-recommended torque (3.2 Nm) into locking compression plates at various angles: orthogonal (control), 5-degree angle off-axis, and 10-degree angle off-axis. Screws were loaded to failure by a transverse force (parallel to the plate) either in the same (“+”) or opposite direction (“−”) of the initial screw angulation. Separately, locking plates were bent to 5 and 10-degree angles, with the bend apex at a screw hole. Locking screws inserted orthogonally into the apex hole at 100% torque were loaded to failure. Results Orthogonal insertion resulted in the highest average load to failure, 2577 ± 141 N (range, 2413–2778 N), whereas any off-axis insertion significantly weakened constructs (165–1285 N, at 100% torque) (P < 0.05). For “+” loading, torque beyond 100% did not increase strength, but 50% torque reduced screw strength (P < 0.05). Loading in the “−” direction consistently resulted in higher strengths than “+” loading (P < 0.05). Plate contouring of 5-degree angle did not significantly change screw strength compared with straight plates but contouring of 10-degree angle significantly reduced load to failure (P < 0.05). Conclusions To maximize the screw plate interface strength, locking screws should be inserted without cross-threading. The mechanical stability of locked screws is significantly compromised by loose insertion, off-axis insertion, or severe distortion of the locking mechanism. PMID:24343255

  9. Augmented assessment as a means to augmented reality.

    PubMed

    Bergeron, Bryan

    2006-01-01

    Rigorous scientific assessment of educational technologies typically lags behind the availability of the technologies by years because of the lack of validated instruments and benchmarks. Even when the appropriate assessment instruments are available, they may not be applied because of time and monetary constraints. Work in augmented reality, instrumented mannequins, serious gaming, and similar promising educational technologies that haven't undergone timely, rigorous evaluation, highlights the need for assessment methodologies that address the limitations of traditional approaches. The most promising augmented assessment solutions incorporate elements of rapid prototyping used in the software industry, simulation-based assessment techniques modeled after methods used in bioinformatics, and object-oriented analysis methods borrowed from object oriented programming. PMID:16404012

  10. Dermal fillers for facial soft tissue augmentation.

    PubMed

    Dastoor, Sarosh F; Misch, Carl E; Wang, Hom-Lay

    2007-01-01

    Nowadays, patients are demanding not only enhancement to their dental (micro) esthetics, but also their overall facial (macro) esthetics. Soft tissue augmentation via dermal filling agents may be used to correct facial defects such as wrinkles caused by age, gravity, and trauma; thin lips; asymmetrical facial appearances; buccal fold depressions; and others. This article will review the pathogenesis of facial wrinkles, history, techniques, materials, complications, and clinical controversies regarding dermal fillers for soft tissue augmentation.

  11. Equating of Augmented Subscores

    ERIC Educational Resources Information Center

    Sinharay, Sandip; Haberman, Shelby J.

    2011-01-01

    Recently, there has been an increasing level of interest in subscores for their potential diagnostic value. Haberman (2008b) suggested reporting an augmented subscore that is a linear combination of a subscore and the total score. Sinharay and Haberman (2008) and Sinharay (2010) showed that augmented subscores often lead to more accurate…

  12. Confronting an Augmented Reality

    ERIC Educational Resources Information Center

    Munnerley, Danny; Bacon, Matt; Wilson, Anna; Steele, James; Hedberg, John; Fitzgerald, Robert

    2012-01-01

    How can educators make use of augmented reality technologies and practices to enhance learning and why would we want to embrace such technologies anyway? How can an augmented reality help a learner confront, interpret and ultimately comprehend reality itself ? In this article, we seek to initiate a discussion that focuses on these questions, and…

  13. Malar and submalar augmentation.

    PubMed

    Binder, William J; Azizzadeh, Babak

    2008-02-01

    Over the past four decades, revolutionary improvements in the design and manufacture of facial implants have broadened the application of midface augmentation. The contemporary practice of facial rejuvenation reflects a 20-year culmination of rapid advances made in the understanding and treatment of midface aging. This article highlights the practice of malar and submalar augmentation: when and how it should be used.

  14. Bio-Augmentation of Cupriavidus sp. CY-1 into 2,4-D Contaminated Soil: Microbial Community Analysis by Culture Dependent and Independent Techniques

    PubMed Central

    Chang, Young-Cheol; Reddy, M. Venkateswar; Umemoto, Honoka; Sato, Yuki; Kang, Mi-Hye; Yajima, Yuka; Kikuchi, Shintaro

    2015-01-01

    In the present study, a 2,4-dichlorophenoxyacetic acid (2,4-D) degrading bacterial strain CY-1 was isolated from the forest soil. Based on physiological, biochemical and 16S rRNA gene sequence analysis it was identified as Cupriavidus sp. CY-1. Further 2,4-D degradation experiments at different concentrations (200 to 800 mg l-1) were carried out using CY-1. Effect of NaCl and KNO3 on 2,4-D degradation was also evaluated. Degradation of 2,4-D and the metabolites produced during degradation process were analyzed using high pressure liquid chromatography (HPLC) and GC-MS respectively. The amount of chloride ions produced during the 2,4-D degradation were analyzed by Ion chromatography (IC) and it is stoichiometric with 2,4-D dechlorination. Furthermore two different types of soils collected from two different sources were used for 2,4-D degradation studies. The isolated strain CY-1 was bio-augmented into 2,4-D contaminated soils to analyze its degradation ability. Culture independent methods like denaturing gradient gel electrophoresis (DGGE) and terminal restriction fragment length polymorphism (T-RFLP), and culture dependent methods like colony forming units (CFU) and most probable number (MPN) were used to analyze the survivability of strain CY-1 in contaminated soil. Results of T-RFLP were coincident with the DGGE analysis. From the DGGE, T-RFLP, MPN and HPLC results it was concluded that strain CY-1 effectively degraded 2,4-D without disturbing the ecosystem of soil indigenous microorganisms. PMID:26710231

  15. Bio-Augmentation of Cupriavidus sp. CY-1 into 2,4-D Contaminated Soil: Microbial Community Analysis by Culture Dependent and Independent Techniques.

    PubMed

    Chang, Young-Cheol; Reddy, M Venkateswar; Umemoto, Honoka; Sato, Yuki; Kang, Mi-Hye; Yajima, Yuka; Kikuchi, Shintaro

    2015-01-01

    In the present study, a 2,4-dichlorophenoxyacetic acid (2,4-D) degrading bacterial strain CY-1 was isolated from the forest soil. Based on physiological, biochemical and 16S rRNA gene sequence analysis it was identified as Cupriavidus sp. CY-1. Further 2,4-D degradation experiments at different concentrations (200 to 800 mg l(-1)) were carried out using CY-1. Effect of NaCl and KNO3 on 2,4-D degradation was also evaluated. Degradation of 2,4-D and the metabolites produced during degradation process were analyzed using high pressure liquid chromatography (HPLC) and GC-MS respectively. The amount of chloride ions produced during the 2,4-D degradation were analyzed by Ion chromatography (IC) and it is stoichiometric with 2,4-D dechlorination. Furthermore two different types of soils collected from two different sources were used for 2,4-D degradation studies. The isolated strain CY-1 was bio-augmented into 2,4-D contaminated soils to analyze its degradation ability. Culture independent methods like denaturing gradient gel electrophoresis (DGGE) and terminal restriction fragment length polymorphism (T-RFLP), and culture dependent methods like colony forming units (CFU) and most probable number (MPN) were used to analyze the survivability of strain CY-1 in contaminated soil. Results of T-RFLP were coincident with the DGGE analysis. From the DGGE, T-RFLP, MPN and HPLC results it was concluded that strain CY-1 effectively degraded 2,4-D without disturbing the ecosystem of soil indigenous microorganisms. PMID:26710231

  16. Minimally invasive transforaminal lumbar interbody fusion with percutaneous navigated guidewireless lumbosacral pedicle screw fixation.

    PubMed

    Chen, Kevin S; Park, Paul

    2016-07-01

    This video details the minimally invasive approach for treatment of a symptomatic Grade II lytic spondylolisthesis with high-grade foraminal stenosis. In this procedure, the use of a navigated, guidewireless technique for percutaneous pedicle screw placement at the lumbosacral junction is highlighted following initial decompression and transforaminal interbody fusion. Key steps of the procedure are delineated that include positioning, exposure, technique for interbody fusion, intraoperative image acquisition, and use of a concise 2-step process for navigated screw placement without using guidewires. The video can be found here: https://youtu.be/2u6H4Pc_8To . PMID:27364422

  17. Additional Drive Circuitry for Piezoelectric Screw Motors

    NASA Technical Reports Server (NTRS)

    Smythe, Robert; Palmer, Dean; Gursel, Yekta; Reder, Leonard; Savedra, Raymond

    2004-01-01

    Modules of additional drive circuitry have been developed to enhance the functionality of a family of commercially available positioning motors (Picomotor . or equivalent) that provide linear motion controllable, in principle, to within increments .30 nm. A motor of this type includes a piezoelectric actuator that turns a screw. Unlike traditional piezoelectrically actuated mechanisms, a motor of this type does not rely on the piezoelectric transducer to hold position: the screw does not turn except when the drive signal is applied to the actuator.

  18. Screw dislocation driven growth of nanomaterials.

    PubMed

    Meng, Fei; Morin, Stephen A; Forticaux, Audrey; Jin, Song

    2013-07-16

    identify the evidence of dislocations. The dislocation-driven growth mechanism not only can unify the various explanations behind a wide variety of exotic nanoscale morphologies but also allows the rational design of catalyst-free solution-phase syntheses that could enable the scalable and low cost production of nanomaterials necessary for large scale applications, such as solar and thermoelectric energy conversions, energy storage, and nanocomposites. In this Account, we discuss the fundamental theories of the screw dislocation driven growth of various nanostructures including one-dimensional nanowires and nanotubes, two-dimensional nanoplates, and three-dimensional hierarchical tree-like nanostructures. We then introduce the transmission electron microscopy (TEM) techniques to structurally characterize the dislocation-driven nanomaterials for future searching and identifying purposes. We summarize the guidelines for rationally designing the dislocation-driven growth and discuss specific examples to illustrate how to implement the guidelines. By highlighting our recent discoveries in the last five years, we show that dislocation growth is a general and versatile mechanism that can be used to grow a variety of nanomaterials via distinct reaction chemistry and synthetic methods. These discoveries are complemented by selected examples of anisotropic crystal growth from other researchers. The fundamental investigation and development of dislocation-driven growth of nanomaterials will create a new dimension to the rational design and synthesis of increasingly complex nanomaterials.

  19. Ridge augmentation with soft tissue procedures in aesthetic dentistry: pre- and postoperative volume measurements with a new kind of moire technique

    NASA Astrophysics Data System (ADS)

    Studer, Stephan P.; Mueller, Ernst; Bucher, Alfred

    1993-09-01

    The aim of this paper was to measure the volume differences of operated alveolar ridge defects before and until 3 months post-surgically. Ten patients with ten localized alveolar ridge defects were operated on. Five alveolar ridge defects were corrected by using the full thickness onlay graft technique and the other five defects were operated by the subepithelial connective tissue graft technique. A strict standardized operation protocol was followed and all alveolar ridge defects were operated on by the same dental surgeon. Before as well as 1, 2, and 3 months after surgery the corrected defect was photographed and an impression was made by using an A-silicon material to produce a gypsum-cast model. The form of all these cast models was then measured using the moire technique. The three months result of ten cases shows that the form of the operated alveolar ridge defects, which were corrected by the subepithelial connective tissue graft technique are more stable compared to those which were operated on by the full thickness onlay graft technique. Localized alveolar ridge defects using the latter method does not show a form stability after 3 months post-surgically.

  20. Magnetohydrodynamic Augmented Propulsion Experiment

    NASA Technical Reports Server (NTRS)

    Litchford, Ron J.; Cole, John; Lineberry, John; Chapman, Jim; Schmidt, Harold; Cook, Stephen (Technical Monitor)

    2002-01-01

    A fundamental obstacle to routine space access is the specific energy limitations associated with chemical fuels. In the case of vertical take-off, the high thrust needed for vertical liftoff and acceleration to orbit translates into power levels in the 10 GW range. Furthermore, useful payload mass fractions are possible only if the exhaust particle energy (i.e., exhaust velocity) is much greater than that available with traditional chemical propulsion. The electronic binding energy released by the best chemical reactions (e.g., LOX/LH2 for example, is less than 2 eV per product molecule (approx. 1.8 eV per H2O molecule), which translates into particle velocities less than 5 km/s. Useful payload fractions, however, will require exhaust velocities exceeding 15 km/s (i.e., particle energies greater than 20 eV). As an added challenge, the envisioned hypothetical RLV (reusable launch vehicle) should accomplish these amazing performance feats while providing relatively low acceleration levels to orbit (2-3g maximum). From such fundamental considerations, it is painfully obvious that planned and current RLV solutions based on chemical fuels alone represent only a temporary solution and can only result in minor gains, at best. What is truly needed is a revolutionary approach that will dramatically reduce the amount of fuel and size of the launch vehicle. This implies the need for new compact high-power energy sources as well as advanced accelerator technologies for increasing engine exhaust velocity. Electromagnetic acceleration techniques are of immense interest since they can be used to circumvent the thermal limits associated with conventional propulsion systems. This paper describes the Magnetohydrodynamic Augmented Propulsion Experiment (MAPX) being undertaken at NASA Marshall Space Flight Center (MSFC). In this experiment, a 1-MW arc heater is being used as a feeder for a 1-MW magnetohydrodynamic (MHD) accelerator. The purpose of the experiment is to demonstrate

  1. A Simple and Reliable Method of Narrowing Genioplasty Using Biodegradable Screws.

    PubMed

    Lee, Tae Sung

    2016-01-01

    The T-osteotomy technique is widely performed to improve lower face aesthetics. During this narrowing genioplasty procedure, metal fixtures are required to rigidly fix the bone segments. Specifically, the use of biodegradable osteofixations has become a viable surgical option as more patients now have the desire to surreptitiously undergo aesthetic surgery. The present report describes a narrowing genioplasty procedure with the use of biodegradable screws only. When the T-osteotomy technique was performed to narrow the chin, the bone segments were first temporarily fixed with a 4-hole titanium plate and screws. Later during the operation, the plate and screws were replaced with 4 biodegradable screws with bicortical fixation. Completion of bone healing can be confirmed by follow-up radiographs taken 6 months after the surgery. Despite increasing demand for the use of absorbable materials in aesthetic surgeries, biodegradable fixation systems have not been widely used for aesthetic surgeries due to a perception of high cost, inconvenient manipulation, prolonged operative time, and suspicions on long-term stability. Our novel method of using only biodegradable screws allows such limitations to be easily overcome by surgeons.

  2. The effect of hydroxyapatite coated screw in the lateral fragility fractures of the femur. A prospective randomized clinical study.

    PubMed

    Pesce, V; Maccagnano, G; Vicenti, G; Notarnicola, A; Moretti, L; Tafuri, S; Vanni, D; Salini, V; Moretti, B

    2014-01-01

    Due to a growing numbers of lateral fragility fractures of the femur and their high social costs the need to work out an effective strategy in order to find a better solution for these patients is warranted. From January 2010 to July 2011, we carried out a prospective randomized clinical study comparing the results of patients with femoral lateral fractures treated by nail and cephalic hydroxyapatite coated screws (study group including 27 patients) compared to the patients with the same fractures treated with nail and head standard screws (control group including 27 patients). We defined the two parts of the femoral neck as ROI 1 (under the head screw) and ROI 2 (above the femoral screw) on the AP view. The bone density of the two areas was calculated using DEXA at T0 (1st day post-surgery), at T1 (40th day post-surgery), at T2 (3 months later), at T3 (1 year later). The clinical-radiography evaluations were based on the Harris Hip Score (HHS), ADL test and x-ray views of the hip. As far as the bone mineral density average of ROI 1 and ROI 2 is concerned, we found a significant statistical increase at T1 and T3 in the study group, while it was not significant in the control group. We could account for this data through the higher mechanical stability of hydroxyapatite coated screws than standard screws. In fact, this material was responsible for improved implant osteointegration. Thanks to a 1 year follow-up we were able to demonstrate the implant utility associated with augmentation and the importance of densitometry exams such as easily repeatable and low cost diagnostics to prevent the onset of complications linked to screw loosening.

  3. 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.

  4. Insertion Profiles of 4 Headless Compression Screws

    PubMed Central

    Hart, Adam; Harvey, Edward J.; Lefebvre, Louis-Philippe; Barthelat, Francois; Rabiei, Reza; Martineau, Paul A.

    2013-01-01

    Purpose In practice, the surgeon must rely on screw position (insertion depth) and tactile feedback from the screwdriver (insertion torque) to gauge compression. In this study, we identified the relationship between interfragmentary compression and these 2 factors. Methods The Acutrak Standard, Acutrak Mini, Synthes 3.0, and Herbert-Whipple implants were tested using a polyurethane foam scaphoid model. A specialized testing jig simultaneously measured compression force, insertion torque, and insertion depth at half-screw-turn intervals until failure occurred. Results The peak compression occurs at an insertion depth of −3.1 mm, −2.8 mm, 0.9 mm, and 1.5 mm for the Acutrak Mini, Acutrak Standard, Herbert-Whipple, and Synthes screws respectively (insertion depth is positive when the screw is proud above the bone and negative when buried). The compression and insertion torque at a depth of −2 mm were found to be 113 ± 18 N and 0.348 ± 0.052 Nm for the Acutrak Standard, 104 ± 15 N and 0.175 ± 0.008 Nm for the Acutrak Mini, 78 ± 9 N and 0.245 ± 0.006 Nm for the Herbert-Whipple, and 67 ± 2N, 0.233 ± 0.010 Nm for the Synthes headless compression screws. Conclusions All 4 screws generated a sizable amount of compression (> 60 N) over a wide range of insertion depths. The compression at the commonly recommended insertion depth of −2 mm was not significantly different between screws; thus, implant selection should not be based on compression profile alone. Conically shaped screws (Acutrak) generated their peak compression when they were fully buried in the foam whereas the shanked screws (Synthes and Herbert-Whipple) reached peak compression before they were fully inserted. Because insertion torque correlated poorly with compression, surgeons should avoid using tactile judgment of torque as a proxy for compression. Clinical relevance Knowledge of the insertion profile may improve our understanding of the implants, provide a better basis for comparing screws

  5. Augmented reality: a review.

    PubMed

    Berryman, Donna R

    2012-01-01

    Augmented reality is a technology that overlays digital information on objects or places in the real world for the purpose of enhancing the user experience. It is not virtual reality, that is, the technology that creates a totally digital or computer created environment. Augmented reality, with its ability to combine reality and digital information, is being studied and implemented in medicine, marketing, museums, fashion, and numerous other areas. This article presents an overview of augmented reality, discussing what it is, how it works, its current implementations, and its potential impact on libraries.

  6. Augmented reality: a review.

    PubMed

    Berryman, Donna R

    2012-01-01

    Augmented reality is a technology that overlays digital information on objects or places in the real world for the purpose of enhancing the user experience. It is not virtual reality, that is, the technology that creates a totally digital or computer created environment. Augmented reality, with its ability to combine reality and digital information, is being studied and implemented in medicine, marketing, museums, fashion, and numerous other areas. This article presents an overview of augmented reality, discussing what it is, how it works, its current implementations, and its potential impact on libraries. PMID:22559183

  7. CAD/CAM-fabricated template for locating implant abutment screws in cement-retained anatomic zirconia restorations.

    PubMed

    Lee, Du-Hyeong

    2015-09-01

    Currently, appropriate access to the abutment screw within cement-retained implant restorations is determined using labor-intensive techniques. The introduction of computer-aided design/computer-aided manufacture technology has facilitated a digitized fabrication process to yield a template that can enhance the accuracy of drilling a screw channel. This article describes the method used to create these guide templates by using advanced dental design programs and machining.

  8. Linking granulation performance with residence time and granulation liquid distributions in twin-screw granulation: An experimental investigation.

    PubMed

    Kumar, Ashish; Alakarjula, Maija; Vanhoorne, Valérie; Toiviainen, Maunu; De Leersnyder, Fien; Vercruysse, Jurgen; Juuti, Mikko; Ketolainen, Jarkko; Vervaet, Chris; Remon, Jean Paul; Gernaey, Krist V; De Beer, Thomas; Nopens, Ingmar

    2016-07-30

    Twin-screw granulation is a promising wet granulation technique for the continuous manufacturing of pharmaceutical solid dosage forms. A twin screw granulator displays a short residence time. Thus, the solid-liquid mixing must be achieved quickly by appropriate arrangement of transport and kneading elements in the granulator screw allowing the production of granules with a size distribution appropriate for tableting. The distribution of residence time and granulation liquid is governed by the field conditions (such as location and length of mixing zones) in the twin-screw granulator, thus contain interesting information on granulation time, mixing and resulting sub-processes such as wetting, aggregation and breakage. In this study, the impact of process (feed rate, screw speed and liquid-to-solid ratio) and equipment parameters (number of kneading discs and stagger angle) on the residence time (distribution), the granulation liquid-powder mixing and the resulting granule size distributions during twin-screw granulation were investigated. Residence time and axial mixing data was extracted from tracer maps and the solid-liquid mixing was quantified from moisture maps, obtained by monitoring the granules at the granulator outlet using near infra-red chemical imaging (NIR-CI). The granule size distribution was measured using the sieving method. An increasing screw speed dominantly reduced the mean residence time. Interaction of material throughput with the screw speed and with the number of kneading discs led to most variation in the studied responses including residence time and mixing capacity. At a high screw speed, granulation yield improved due to high axial mixing. However, increasing material throughput quickly lowers the yield due to insufficient mixing of liquid and powder. Moreover, increasing liquid-to-solid ratio resulted in more oversized granules, and the fraction of oversized granules further increased at higher throughput. Although an increasing number

  9. Linking granulation performance with residence time and granulation liquid distributions in twin-screw granulation: An experimental investigation.

    PubMed

    Kumar, Ashish; Alakarjula, Maija; Vanhoorne, Valérie; Toiviainen, Maunu; De Leersnyder, Fien; Vercruysse, Jurgen; Juuti, Mikko; Ketolainen, Jarkko; Vervaet, Chris; Remon, Jean Paul; Gernaey, Krist V; De Beer, Thomas; Nopens, Ingmar

    2016-07-30

    Twin-screw granulation is a promising wet granulation technique for the continuous manufacturing of pharmaceutical solid dosage forms. A twin screw granulator displays a short residence time. Thus, the solid-liquid mixing must be achieved quickly by appropriate arrangement of transport and kneading elements in the granulator screw allowing the production of granules with a size distribution appropriate for tableting. The distribution of residence time and granulation liquid is governed by the field conditions (such as location and length of mixing zones) in the twin-screw granulator, thus contain interesting information on granulation time, mixing and resulting sub-processes such as wetting, aggregation and breakage. In this study, the impact of process (feed rate, screw speed and liquid-to-solid ratio) and equipment parameters (number of kneading discs and stagger angle) on the residence time (distribution), the granulation liquid-powder mixing and the resulting granule size distributions during twin-screw granulation were investigated. Residence time and axial mixing data was extracted from tracer maps and the solid-liquid mixing was quantified from moisture maps, obtained by monitoring the granules at the granulator outlet using near infra-red chemical imaging (NIR-CI). The granule size distribution was measured using the sieving method. An increasing screw speed dominantly reduced the mean residence time. Interaction of material throughput with the screw speed and with the number of kneading discs led to most variation in the studied responses including residence time and mixing capacity. At a high screw speed, granulation yield improved due to high axial mixing. However, increasing material throughput quickly lowers the yield due to insufficient mixing of liquid and powder. Moreover, increasing liquid-to-solid ratio resulted in more oversized granules, and the fraction of oversized granules further increased at higher throughput. Although an increasing number

  10. Control of Pedicle Screw Placement with an Electrical Conductivity Measurement Device: Initial Evaluation in the Thoracic and Lumbar Spine

    PubMed Central

    Schomacher, Markus

    2016-01-01

    Aim. Transpedicular screw fixation is widely used in spinal surgery. But the insertion of pedicle screws can sometimes be challenging because of the variability in pedicle size and the proximity of nerve roots. Methods. We detected intraoperatively the sensitivity for iatrogenic pedicel perforation with a hand-held electronic conductivity measurement device (ECD) that measures electrical conductivity of tissue-medium surrounding the instrument tip. ECD was used to guide the placement of 84 pedicle screws in 15 patients undergoing surgery for tumor or degenerative spinal disease at various spinal levels from T8 to L5. Additionally a CT-scan controlled screw positioning postoperatively. Results. The placement was “correct” (no mediocaudal pedicle wall penetration) for 78 of 84 (92,8%) screws, “suboptimal but acceptable” (0–2 mm penetration) for 4 of 84 (4,8%) screws, and “misplaced” (penetration > 2 mm) for 2 of 84 (2,4%) screws. Conclusion. Although this study was not designed to compare electronic conductivity technique to other guidance methods, such as fluoroscopy or navigation, a convincing “proof of concept” for ECD use in spinal instrumentation could be demonstrated. Advantages include easy handling without time-consuming setup and reduced X-ray exposure. However, further investigations are necessary to evaluate i.a. the economic aspects for this single-use developed instrument. PMID:27699203

  11. Control of Pedicle Screw Placement with an Electrical Conductivity Measurement Device: Initial Evaluation in the Thoracic and Lumbar Spine

    PubMed Central

    Schomacher, Markus

    2016-01-01

    Aim. Transpedicular screw fixation is widely used in spinal surgery. But the insertion of pedicle screws can sometimes be challenging because of the variability in pedicle size and the proximity of nerve roots. Methods. We detected intraoperatively the sensitivity for iatrogenic pedicel perforation with a hand-held electronic conductivity measurement device (ECD) that measures electrical conductivity of tissue-medium surrounding the instrument tip. ECD was used to guide the placement of 84 pedicle screws in 15 patients undergoing surgery for tumor or degenerative spinal disease at various spinal levels from T8 to L5. Additionally a CT-scan controlled screw positioning postoperatively. Results. The placement was “correct” (no mediocaudal pedicle wall penetration) for 78 of 84 (92,8%) screws, “suboptimal but acceptable” (0–2 mm penetration) for 4 of 84 (4,8%) screws, and “misplaced” (penetration > 2 mm) for 2 of 84 (2,4%) screws. Conclusion. Although this study was not designed to compare electronic conductivity technique to other guidance methods, such as fluoroscopy or navigation, a convincing “proof of concept” for ECD use in spinal instrumentation could be demonstrated. Advantages include easy handling without time-consuming setup and reduced X-ray exposure. However, further investigations are necessary to evaluate i.a. the economic aspects for this single-use developed instrument.

  12. Implant Augmentation: Adding Bone Cement to Improve the Treatment of Osteoporotic Distal Femur Fractures

    PubMed Central

    Wähnert, Dirk; Hofmann-Fliri, Ladina; Richards, R. Geoff; Gueorguiev, Boyko; Raschke, Michael J.; Windolf, Markus

    2014-01-01

    Abstract The increasing problems in the field of osteoporotic fracture fixation results in specialized implants as well as new operation methods, for example, implant augmentation with bone cement. The aim of this study was to determine the biomechanical impact of augmentation in the treatment of osteoporotic distal femur fractures. Seven pairs of osteoporotic fresh frozen distal femora were randomly assigned to either an augmented or nonaugmented group. In both groups, an Orthopaedic Trauma Association 33 A3 fractures was fixed using the locking compression plate distal femur and cannulated and perforated screws. In the augmented group, additionally, 1 mL of polymethylmethacrylate cement was injected through the screw. Prior to mechanical testing, bone mineral density (BMD) and local bone strength were determined. Mechanical testing was performed by cyclic axial loading (100 N to 750 N + 0.05N/cycle) using a servo-hydraulic testing machine. As a result, the BMD as well as the axial stiffness did not significantly differ between the groups. The number of cycles to failure was significantly higher in the augmented group with the BMD as a significant covariate. In conclusion, cement augmentation can significantly improve implant anchorage in plating of osteoporotic distal femur fractures. PMID:25415673

  13. Clival Screw Placement in Patient with atlas assimilation: A CT-based feasibility study.

    PubMed

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

    2016-01-01

    Clival screw and plate fixation technique is an alternative or supplement to the occipitocervical instrumentation. However, no report has clarified the applied anatomy of clivus in patients with atlas assimilation (C1A), especially for clival screw fixation. Therefore, we measured the parameters of clival lengths, widths, putative screw lengths, clival-cervical angel and foramen magnum diameters on CT images in a cohort of 81 C1A patients and patients without C1A. The clivus showed a rectangular shape in 96.3% (78/81) of C1A patients, and a normal-like triangle shape in 3.7% (3/81) of C1A patients. The intracranial clival length decreased 13% (37 mm) in C1A patients, the extracranial clival length 14.8% (24.1 mm), the clival-cervical angle 6.2% (122.3°) and the superior screw length 11.3% (14.1 mm), the sagittal diameter of foramen magnum 16% (28.0 mm), respectively. There was no significant difference in the widest or narrowest clival width, or the middle screw length, or the transverse diameter of foramen magnum between groups. The inferior clivus was feasible for an average 9.7-mm-length screw placement in C1A patients, while not in patients without C1A. The present study characterizes clivus of C1A patients with an unnormal-like rectangular shape, and confirmes a screw placement at the inferior clivus. PMID:27539005

  14. Clival Screw Placement in Patient with atlas assimilation: A CT-based feasibility study

    PubMed Central

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

    2016-01-01

    Clival screw and plate fixation technique is an alternative or supplement to the occipitocervical instrumentation. However, no report has clarified the applied anatomy of clivus in patients with atlas assimilation (C1A), especially for clival screw fixation. Therefore, we measured the parameters of clival lengths, widths, putative screw lengths, clival-cervical angel and foramen magnum diameters on CT images in a cohort of 81 C1A patients and patients without C1A. The clivus showed a rectangular shape in 96.3% (78/81) of C1A patients, and a normal-like triangle shape in 3.7% (3/81) of C1A patients. The intracranial clival length decreased 13% (37 mm) in C1A patients, the extracranial clival length 14.8% (24.1 mm), the clival-cervical angle 6.2% (122.3°) and the superior screw length 11.3% (14.1 mm), the sagittal diameter of foramen magnum 16% (28.0 mm), respectively. There was no significant difference in the widest or narrowest clival width, or the middle screw length, or the transverse diameter of foramen magnum between groups. The inferior clivus was feasible for an average 9.7-mm-length screw placement in C1A patients, while not in patients without C1A. The present study characterizes clivus of C1A patients with an unnormal-like rectangular shape, and confirmes a screw placement at the inferior clivus. PMID:27539005

  15. RMS active damping augmentation

    NASA Technical Reports Server (NTRS)

    Gilbert, Michael G.; Scott, Michael A.; Demeo, Martha E.

    1992-01-01

    The topics are presented in viewgraph form and include: RMS active damping augmentation; potential space station assembly benefits to CSI; LaRC/JSC bridge program; control law design process; draper RMS simulator; MIMO acceleration control laws improve damping; potential load reduction benefit; DRS modified to model distributed accelerations; accelerometer location; Space Shuttle aft cockpit simulator; simulated shuttle video displays; SES test goals and objectives; and SES modifications to support RMS active damping augmentation.

  16. Minimal inframammary incision for breast augmentation

    PubMed Central

    Fanous, Nabil; Tawilé, Caroline; Brousseau, Valérie J

    2008-01-01

    The inframammary approach in breast augmentation, still the most popular technique among plastic surgeons, has always been hampered by the undesirable appearance of its scar. The present paper describes a modified approach to inframammary augmentation with saline-filled prostheses. This approach uses a very short incision, thus resulting in a much less noticeable scar. The surgical technique is easy to learn, simple to execute, does not necessitate any special equipment and gives consistent results. Decreasing the scar length to an absolute minimum ensures higher patient and surgeon satisfaction. PMID:19554159

  17. Comparison of arthroscopic anterior cruciate ligament reconstruction by bone-patellar tendon-bone graft with or without using interferential screw in general population.

    PubMed

    Arifeen, K N; Chowdhury, A Z; Sakeb, N; Joarder, A I; Salek, A K; Selimullah, A M

    2015-01-01

    Rupture of the Anterior Cruciate Ligament (ACL) is common, resulting reduced quality of life, increasing the meniscal injury risk, knee instability and early degenerative joint disease. Bone-Patellar Tendon-Bone (BPTB) became the gold standard surgery where conservative management failed. Adding interferential screw provides rigid fixation which is important for early accelerated rehabilitation program in athletes but we have carried out this prospective interventional study in Bangabandhu Sheikh Mujib Medical University (BSMMU) and our private settings from January 2007 to December 2011 to assess whether interferential screws provide any clinical and functional advantage in general population. Sixty six male patients of 21-40 years age, with ACL deficient knees were reconstructed with BPTB graft where 40 cases were augmented by interferential screws and 26 cases without and followed up for minimum 2 years. The clinical and functional outcome (by Lysholm Knee Scoring), post-operative knee stability (by clinical tests) and complications were assessed and recorded. There was significant (p<0.05, paired 't' test) improvement of knee function (limp, walking, stair climbing, squatting, thigh atrophy) in both groups but no significant difference between them (p>0.05, chi squared test) regarding clinical, functional outcome and knee stability. The complications were insignificant (p>0.05, chi squared test) in both groups but there were few cases of screw related complications with augmentation and pronounced anterior knee laxity without it. So, ACL reconstruction by BPTB grafts with or without augmentation results consistent and comparable outcome in general population. PMID:25725669

  18. Freehand Thoracic Pedicle Screw Placement: Review of Existing Strategies and a Step-by-Step Guide Using Uniform Landmarks for All Levels

    PubMed Central

    Baaj, Ali A

    2016-01-01

    Pedicle screw fixation in the thoracic spine presents certain challenges due to the critical regional neurovascular anatomy as well as the narrow pedicular corridor that typically exists. With increased awareness of the dangers of intraoperative radiation, the ability to place pedicle screws with anatomic landmarks alone is paramount. In this study, we reviewed the literature from 1990 to 2015 for studies that included freehand pedicle screw placement in the thoracic spine with special emphasis on entry points and the trajectories of the screws. We excluded studies that used fluoroscopy guidance, navigation techniques, cadaveric and biomechanical articles, case reports, and experimental studies on animals. The search retrieved 40 articles, and after careful selection, seven articles were analyzed. Over 8,000 screws were placed in the different studies. The mean accuracy for placement of the thoracic screws was 93.3%. However, there is little consensus between studies in entry points, sagittal, and axial trajectories of the screws. We complete this review by presenting our step-by-step technique for the placement of freehand pedicle screws in the thoracic spine. PMID:27014535

  19. Freehand Thoracic Pedicle Screw Placement: Review of Existing Strategies and a Step-by-Step Guide Using Uniform Landmarks for All Levels.

    PubMed

    Avila, Mauricio J; Baaj, Ali A

    2016-01-01

    Pedicle screw fixation in the thoracic spine presents certain challenges due to the critical regional neurovascular anatomy as well as the narrow pedicular corridor that typically exists. With increased awareness of the dangers of intraoperative radiation, the ability to place pedicle screws with anatomic landmarks alone is paramount. In this study, we reviewed the literature from 1990 to 2015 for studies that included freehand pedicle screw placement in the thoracic spine with special emphasis on entry points and the trajectories of the screws. We excluded studies that used fluoroscopy guidance, navigation techniques, cadaveric and biomechanical articles, case reports, and experimental studies on animals. The search retrieved 40 articles, and after careful selection, seven articles were analyzed. Over 8,000 screws were placed in the different studies. The mean accuracy for placement of the thoracic screws was 93.3%. However, there is little consensus between studies in entry points, sagittal, and axial trajectories of the screws. We complete this review by presenting our step-by-step technique for the placement of freehand pedicle screws in the thoracic spine. PMID:27014535

  20. C2 nerve dysfunction associated with C1 lateral mass screw fixation.

    PubMed

    Huang, Da-geng; Hao, Ding-jun; Li, Guang-lin; Guo, Hao; Zhang, Yu-chen; He, Bao-rong

    2014-11-01

    The C1 lateral mass screw technique is widely used for atlantoaxial fixation. However, C2 nerve dysfunction may occur as a complication of this procedure, compromising the quality of life of affected patients. This is a review of the topic of C2 nerve dysfunction associated with C1 lateral mass screw fixation and related research developments. The C2 nerve root is located in the space bordered superiorly by the posterior arch of C1 , inferiorly by the C2 lamina, anteriorly by the lateral atlantoaxial joint capsule, and posteriorly by the anterior edge of the ligamentum flavum. Some surgeons suggest cutting the C2 nerve root during C1 lateral mass screw placement, whereas others prefer to preserve it. The incidence, clinical manifestations, causes, management, and prevention of C2 nerve dysfunction associated with C(1) lateral mass screw fixation are reviewed. Sacrifice of the C2 nerve root carries a high risk of postoperative numbness, whereas postoperative nerve dysfunction can occur when it has been preserved. Many surgeons have been working hard on minimizing the risk of postoperative C2 nerve dysfunction associated with C1 lateral mass screw fixation. PMID:25430709

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

    PubMed

    Joshi, Yogesh V; Bhaskar, Deepu; Phaltankar, Padmanabh M; Charalambous, Charalambos P

    2015-12-01

    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

  2. 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.

  3. Low energy high pressure miniature screw valve

    DOEpatents

    Fischer, Gary J.; Spletzer, Barry L.

    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.

  4. Metal-ceramic screw-retained implant fixed partial denture with intraoral luted framework to improve passive fit.

    PubMed

    Baig, Mirza Rustum; Gunaseelan, Rajan

    2012-04-01

    Passive fit of a long-span screw-retained implant prosthesis is an important criteria for the success of the restoration. This article describes a technique for fabricating a ceramometal implant fixed dental prosthesis (FDP) for a long-span partially edentulous situation by altering the conventional screw-retained design. The possibility of a passive fit is maximized by intraoral luting of the cast frame to milled abutments, and the potential framework distortion during fabrication is compensated to a major extent. Retrievability is ensured by screw retention of the prosthesis to the implants. Compared with conventional porcelain fused to metal screw-retained FDP, this prosthesis is relatively inexpensive to fabricate. PMID:20932151

  5. Primary Breast Augmentation with Fat Grafting.

    PubMed

    Coleman, Sydney R; Saboeiro, Alesia P

    2015-07-01

    The controversy over fat grafting to the breasts has now been settled. In 2009, the American Society of Plastic Surgeons Fat Graft Task Force stated that "Fat grafting may be considered for breast augmentation and correction of defects associated with medical conditions and previous breast surgeries; however, results are dependent on technique and surgeon expertise." This article discusses the history, indications, planning, complications, and present technique of fat grafting to the breast using the Coleman technique.

  6. Augmenting computer networks

    NASA Technical Reports Server (NTRS)

    Bokhari, S. H.; Raza, A. D.

    1984-01-01

    Three methods of augmenting computer networks by adding at most one link per processor are discussed: (1) A tree of N nodes may be augmented such that the resulting graph has diameter no greater than 4log sub 2((N+2)/3)-2. Thi O(N(3)) algorithm can be applied to any spanning tree of a connected graph to reduce the diameter of that graph to O(log N); (2) Given a binary tree T and a chain C of N nodes each, C may be augmented to produce C so that T is a subgraph of C. This algorithm is O(N) and may be used to produce augmented chains or rings that have diameter no greater than 2log sub 2((N+2)/3) and are planar; (3) Any rectangular two-dimensional 4 (8) nearest neighbor array of size N = 2(k) may be augmented so that it can emulate a single step shuffle-exchange network of size N/2 in 3(t) time steps.

  7. Screw dislocation in functionally graded magnetoelectroelastic solids

    NASA Astrophysics Data System (ADS)

    Wang, Yi-Ze; Kuna, Meinhard

    2014-02-01

    A screw dislocation in a functionally graded magnetoelectroelastic material is investigated. The material properties exponentially changing along both x and y directions are considered and the mechanical-electric-magnetic coupling is discussed. Closed-form expressions for the mechanical, electric and magnetic components are derived using the general stress function method. The solutions can be applied as a fundamental result and reduced into the classic and piezoelectric cases. The study puts forth a direct way for screw dislocation analysis in inhomogeneous structures with multifield coupling.

  8. Spline-Screw Multiple-Rotation Mechanism

    NASA Technical Reports Server (NTRS)

    Vranish, John M.

    1994-01-01

    Mechanism functions like combined robotic gripper and nut runner. Spline-screw multiple-rotation mechanism related to spline-screw payload-fastening system described in (GSC-13454). Incorporated as subsystem in alternative version of system. Mechanism functions like combination of robotic gripper and nut runner; provides both secure grip and rotary actuation of other parts of system. Used in system in which no need to make or break electrical connections to payload during robotic installation or removal of payload. More complicated version needed to make and break electrical connections. Mechanism mounted in payload.

  9. Maxillary anterior ridge augmentation with recombinant human bone morphogenetic protein 2.

    PubMed

    Edmunds, Ryan K; Mealey, Brian L; Mills, Michael P; Thoma, Daniel S; Schoolfield, John; Cochran, David L; Mellonig, Jim

    2014-01-01

    No human studies exist on the use of recombinant human bone morphogenetic protein 2 (rhBMP-2) on an absorbable collagen sponge (ACS) as a sole graft material for lateral ridge augmentation in large ridge defect sites. This series evaluates the treatment outcome of maxillary anterior lateral ridge augmentation with rhBMP-2/ACS. Twenty patients were treated with rhBMP-2/ACS and fixation screws for space maintenance. Cone beam volumetric tomography measurements were used to determine gain in ridge width, and a bone core biopsy was obtained. The mean horizontal ridge gain was 1.2 mm across sites, and every site gained width. PMID:25006772

  10. Cyclic pull-out strength of hamstring tendon graft fixation with soft tissue interference screws. Influence of screw length.

    PubMed

    Stadelmaier, D M; Lowe, W R; Ilahi, O A; Noble, P C; Kohl, H W

    1999-01-01

    Blunt-threaded interference screws used for fixation of hamstring tendons in anterior cruciate ligament reconstructions provide aperture fixation and may provide a biomechanically more stable graft than a graft fixed further from the articular surface. It is unknown if soft tissue fixation strength using interference screws is affected by screw length. We compared the cyclic and time-zero pull-out forces of 7 x 25 mm and 7 x 40 mm blunt-threaded metal interference screws for hamstring graft tibial fixation in eight paired human cadaveric specimens. A four-stranded autologous hamstring tendon graft was secured by a blunt-threaded interference screw into a proximal tibial tunnel with a diameter corresponding to the graft width. Eight grafts were secured with a 25-mm length screw while the other eight paired grafts were secured with a 40-mm length screw. During cyclic testing, slippage of the graft occurred as the force of pull became greater with each cycle until the graft-screw complex ultimately failed. All grafts failed at the fixation site, with the tendon being pulled past the screw. There were no measurable differences in the mean cyclic failure strength, pull-out strength, or stiffness between the two sizes of screws. Although use of the longer screw would make removal technically easier should revision surgery be necessary, it did not provide stronger fixation strength than the shorter, standard screw as had been postulated. PMID:10569365

  11. The effect of screw pullout rate on screw purchase in synthetic cancellous bone.

    PubMed

    Zdero, Rad; Schemitsch, Emil H

    2009-02-01

    Clinically, orthopaedic fracture fixation constructs are mounted using screws inserted into cancellous bone, while biomechanical studies are increasingly using commercially available synthetic bones. The goal of this study was to examine the effect of screw pullout rate on cancellous bone screw purchase strength in synthetic cancellous bone. Sixty synthetic cancellous bone cubes (40x40x40 mm(3)) each had one orthopaedic cancellous bone screw (major diameter=6.5 mm) inserted to a depth of 30 mm. Screws were extracted to obtain outcome measures of failure force, failure shear stress, failure energy, failure displacement, resistance force, and removal energy. The ten test groups (n=6 cubes per group) had screws extracted at pullout rates of 1 mmmin, 2.5 mmmin, 5 mmmin, 7.5 mmmin, 10 mmmin, 20 mmmin, 30 mmmin, 40 mmmin, 50 mmmin, and 60 mmmin. The aggregate average results for failure force, failure stress, failure energy, failure displacement, resistance force, and postfailure removal energy for combined pullout rates were, respectively, 984.8+/-63.9 N, 3.5+/-0.2 MPa, 298.3+/-41.7 J, 0.53+/-0.08 mm, 453.8+/-19.6 N, and 5420.1+/-489.7 J. Most statistical differences (40 of 47) involved either the 5 mmmin or the 60 mmmin rates being compared to other rates. Failure force, failure stress, and resistance force increased and were highly linearly correlated with pullout rate (R(2)=0.78, 0.76, and 0.74, respectively). Failure energy, failure displacement, and removal energy were relatively unchanged over the pullout range tested, yielding low correlation coefficients (R(2)<0.05). Failure force, failure stress, and resistance force were affected by bone screw pullout rate in synthetic cancellous bone, while failure energy, failure displacement, and removal energy remained unchanged. This is the first study to perform an extensive investigation of cancellous bone screw pullout rate in synthetic cancellous bone.

  12. 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.

  13. Soft tissue augmentation.

    PubMed

    Hirsch, Ranella J; Cohen, Joel L

    2006-09-01

    Recent additions to the soft tissue augmentation armamentarium have greatly increased the dermatologic surgeon's choices in optimizing facial contouring and the treatment of acne scars. In this article, we review the science of fillers and look at the future of dermal fillers.

  14. Augmented Reality Binoculars.

    PubMed

    Oskiper, Taragay; Sizintsev, Mikhail; Branzoi, Vlad; Samarasekera, Supun; Kumar, Rakesh

    2015-05-01

    In this paper we present an augmented reality binocular system to allow long range high precision augmentation of live telescopic imagery with aerial and terrain based synthetic objects, vehicles, people and effects. The inserted objects must appear stable in the display and must not jitter and drift as the user pans around and examines the scene with the binoculars. The design of the system is based on using two different cameras with wide field of view and narrow field of view lenses enclosed in a binocular shaped shell. Using the wide field of view gives us context and enables us to recover the 3D location and orientation of the binoculars much more robustly, whereas the narrow field of view is used for the actual augmentation as well as to increase precision in tracking. We present our navigation algorithm that uses the two cameras in combination with an inertial measurement unit and global positioning system in an extended Kalman filter and provides jitter free, robust and real-time pose estimation for precise augmentation. We have demonstrated successful use of our system as part of information sharing example as well as a live simulated training system for observer training, in which fixed and rotary wing aircrafts, ground vehicles, and weapon effects are combined with real world scenes. PMID:26357208

  15. Augmentative & Alternative Communication

    ERIC Educational Resources Information Center

    Murphy, Patti

    2007-01-01

    There is no definitive recipe for augmentative and alternative communication (AAC) success, but its universal ingredients can be found at home. The main ones are: (1) Understanding that all children need to express themselves, however outgoing or shy they may be; (2) Willingness to embrace the technology that may help your child regardless of your…

  16. Augmented thermal bus

    NASA Technical Reports Server (NTRS)

    Schrage, Dean S. (Inventor)

    1993-01-01

    The present invention is directed to an augmented thermal bus. In the present design a plurity of thermo-electric heat pumps are used to couple a source plate to a sink plate. Each heat pump is individually controlled by a model based controller. The controller coordinates the heat pump to maintain isothermality in the source.

  17. Augmented Thermal Bus

    NASA Technical Reports Server (NTRS)

    Schrage, Dean S. (Inventor)

    1996-01-01

    The present invention is directed to an augmented thermal bus. In the present design a plurality of thermo-electric heat pumps are used to couple a source plate to a sink plate. Each heat pump is individually controlled by a model based controller. The controller coordinates the heat pumps to maintain isothermality in the source.

  18. 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.

  19. Flap-augmented shrouds for aerogenerators

    NASA Technical Reports Server (NTRS)

    Seginer, A.

    1976-01-01

    Axisymmetrical shrouds for windmills are augmented by ring-shaped 'flaps' and their performance is studied experimentally. The concept of the shroud as an annular 'wing' is justified, leading to the conclusion that high-lift techniques should be used in shroud design, and that high-lift devices, such as flaps, would increase the power output of the windmill. It is shown experimentally that the ideal power output of a flap-augmented shrouded turbine can be more than 4 times the power of unshrouded turbines of the same diameter.

  20. Pedicle screw-based posterior dynamic stabilizers for degenerative spine: in vitro biomechanical testing and clinical outcomes.

    PubMed

    Chamoli, Uphar; Diwan, Ashish D; Tsafnat, Naomi

    2014-09-01

    Dynamic stabilization in a degenerate symptomatic spine may be advantageous compared with conventional fusion procedures, as it helps preserve motion and minimizes redistribution of loads at instrumented and adjacent segments. This article presents a systematic review of biomechanical and clinical evidence available on some of the pedicle screw based posterior dynamic stabilization (PDS) devices. Using Medline, Embase, and Scopus online databases, we identified four pedicle-screw-PDS devices for which both, biomechanical testing and clinical follow-up data are available: Graf artificial ligaments, Isobar TTL, Polyetheretherketone rods, and Dynesys. The current state-of-the-art of pedicle-screw-PDS devices is far from achieving its desired biomechanical efficacy, which has resulted in a weak support for the posited clinical benefits. Although pedicle-screw-PDS devices are useful in salvaging a moderately degenerate functionally suboptimal disc, for severe disc degeneration cases fusion is still the preferred choice. We conclude that a pedicle-screw-PDS device should aim at restoring load sharing amongst spinal elements while preserving the qualitative and quantitative nature of spinal motion, especially minimize posterior shift of the helical axis of motion. More precise and objective assessment techniques need to be standardized for in vivo evaluation of intervertebral motion and load sharing amongst spinal elements across different pedicle-screw-PDS devices.

  1. Pull-out strength of screws from polymethylmethacrylate cement.

    PubMed

    Motzkin, N E; Chao, E Y; An, K N; Wikenheiser, M A; Lewallen, D G

    1994-03-01

    We aimed to determine the optimal method of inserting a screw into polymethylmethacrylate (PMMA) cement to enhance fixation. We performed six groups of ten axial pull-out tests with two sizes of screw (3.5 and 4.5 mm AO cortical) and three methods of insertion. Screws were placed into 'fluid' PMMA, into 'solid' PMMA by drilling and tapping, or into 'curing' PMMA with quarter-revolution turns every 30 seconds until the PMMA had hardened. After full hardening, we measured the maximum load to failure for each screw-PMMA construct. We found no significant difference in the pull-out strengths between screw sizes or between screws placed in fluid or solid PMMA. Screws placed in curing PMMA were significantly weaker: the relative strengths of solid, fluid and curing groups were 100%, 97% and 71%, respectively. We recommend the use of either solid or fluid insertion according to the circumstances and the preference of the surgeon. PMID:8113302

  2. Technique for code augmentation. Memorandum report

    SciTech Connect

    Fickie, K.D.; Grosh, J.

    1987-10-01

    A simple method for calling pre-existing computer codes from inside another program is described. Three applications drawn from the field of interior ballistics are included as examples. Two of the cases are optimization problems and the other is a simple search for a constraint condition. More elaborate applications in the area of computer-aided design are discussed.

  3. Effectiveness of interference screw fixation in ulnar collateral ligament reconstruction.

    PubMed

    Nissen, Carl W

    2008-07-01

    Ulnar collateral ligament disruptions of the elbow are increasingly common for athletes involved in overhead sports. One newer reconstructive technique combines the use of a biotenodesis screw for ulnar fixation with the docking procedure for humeral fixation referred to as the DANE procedure. Biomechanical evaluations have determined that the combined procedure has properties similar to previous methods, but few comparative clinical studies have been performed. The current study compares the DANE procedure to a traditional method of ulnar collateral ligament reconstruction with a medium range follow-up. Twelve ulnar collateral ligament reconstructions were observed for a minimum of 21 months. Six reconstructions were performed using bone tunnels on the ulna. The other 6 used a biotenodesis interference screw on the ulna. Both groups used the docking procedure on the humerus. Identical rehabilitation phases were followed by both groups. Attention was paid not only to the time to return to play and the level able to be returned to but also to interoperative differences, including tourniquet time. We concluded that the DANE reconstruction is an appropriate and effective method. Results are similar to those achieved with a traditional reconstructive method. The study also demonstrates that tourniquet time and, therefore, operative time is less for the DANE procedure.

  4. Foam granulation: new developments in pharmaceutical solid oral dosage forms using twin screw extrusion machinery.

    PubMed

    Thompson, M R; Weatherley, S; Pukadyil, R N; Sheskey, P J

    2012-07-01

    This paper investigates foam granulation in a twin screw extruder as a new continuous wet granulation technique for pharmaceutical powder drug formulations. Foamed aqueous binder has a reportedly lower soak-to-spread ratio than drop or spray liquid addition in batch granulation. This work demonstrates a twin screw extruder configuration for foam granulation and subsequently compares the new approach against liquid injection in the granulation of α-lactose monohydrate with a methylcellulose binder. Trials were conducted at high powder output rates (20-40 kg/h) and high screw speeds (220-320 RPM) with two screw configurations. Process stability improved with the new technique allowing granulation with less binder. The extruded mass maintained a low exit temperature, being insensitive to operating conditions unlike the liquid injection approach, where temperatures rose significantly as flow rate increased. The particle size distribution by foam granulation reflected a more uniformly wetted mass with larger granule growth noted even for conditions where dry powder exited by liquid injection. Other factors were found similar between the two binder delivery methods such as consumed mechanical energy, as well as fracture strength and compressibility of produced granules.

  5. Augmentation mammaplasty using implants: a review.

    PubMed

    Takayanagi, Susumu

    2012-09-01

    One of the techniques for augmentation mammaplasty is the procedure using implants. Even though this technique has been used for many years, there are still several controversial issues to be discussed and overcome for patient safety. In this review article, capsular contracture, leak or rupture of the implants, possible systemic disease, relation with breast cancer, and recent problems with Poly Implant Prothese implants are described and discussed. PMID:23094237

  6. Augmentation Mammaplasty Using Implants: A Review

    PubMed Central

    2012-01-01

    One of the techniques for augmentation mammaplasty is the procedure using implants. Even though this technique has been used for many years, there are still several controversial issues to be discussed and overcome for patient safety. In this review article, capsular contracture, leak or rupture of the implants, possible systemic disease, relation with breast cancer, and recent problems with Poly Implant Prothese implants are described and discussed. PMID:23094237

  7. The transareolar incision for breast augmentation revisited.

    PubMed

    Kompatscher, Peter; Schuler, Christine; Beer, Gertrude M

    2004-01-01

    Of the various possible incisions for breast augmentation, the transareolar access has gained only limited popularity. The potential side effects of this incision are said to be altered nipple sensation, impaired lactation, an increased rate of infections with capsular fibrosis, well visible scar formation with hypopigmentation, and the need for an additional access in case a breast ptosis correction should prove necessary at a later date. The purpose of this retrospective study was to judge advantages and limitations of transareolar breast augmentation, and to verify whether the reluctant attitude toward this surgical approach is justified. A sample of 18 patients with a transareolar, retropectoral breast augmentation was selected for a retrospective evaluation. The suitability of the technique in general was examined together with early postoperative complications, sensory changes, and late complications on the basis of an evaluation system for cosmetic surgical results. The study showed that only women with an areolar diameter of 3.5 cm or more without pronounced breast ptosis were suitable for the transareolar access. No early infections were noted. The rate of capsular fibrosis was 11%. Two years after breast augmentation, 16 women (89%) judged their breast sensation to be normal, but objective assessment showed that mean pressure and vibration sensation were moderately compromised in all parts of the breast. The scars were of good quality, with very little hypopigmentation. With appropriate patient selection, respecting the advantages and limitations, the transareolar incision has its definite place among the different incisions for breast augmentation. PMID:15164231

  8. Simple Implant Augmentation Rhinoplasty.

    PubMed

    Nguyen, Anh H; Bartlett, Erica L; Kania, Katarzyna; Bae, Sang Mo

    2015-11-01

    Augmentation rhinoplasty among Asian patients is often performed to improve the height of the nasal dorsum. As the use of autogenous tissues poses certain limitations, alloplastic materials are a viable alternative with a long history of use in Asia. The superiority of one implant prosthesis over another for augmentation rhinoplasty is a matter of debate, with each material representing varying strengths and weaknesses, indications for use, and precautions to consider in nasal implant placement. An implant prosthesis should be used on a case-by-case basis. Augmentation rhinoplasty requires the consideration of specific anatomical preoperative factors, including the external nose, nasal length, nasofrontal angle, humps, and facial proportions. It is equally important to consider several operative guidelines to appropriately shape implants to minimize the occurrence of adverse effects and postoperative complications. The most common postoperative complications include infection, nasal height change, movement of implant prosthesis, and silicone implant protrusion. In addition, the surgeon should consider the current standards of Asian beauty aesthetics to better understand the patient's desired outcome. PMID:26648804

  9. The applicability of PEEK-based abutment screws.

    PubMed

    Schwitalla, Andreas Dominik; Abou-Emara, Mohamed; Zimmermann, Tycho; Spintig, Tobias; Beuer, Florian; Lackmann, Justus; Müller, Wolf-Dieter

    2016-10-01

    The high-performance polymer PEEK (poly-ether-ether-ketone) is more and more being used in the field of dentistry, mainly for removable and fixed prostheses. In cases of screw-retained implant-supported reconstructions of PEEK, an abutment screw made of PEEK might be advantageous over a conventional metal screw due to its similar elasticity. Also in case of abutment screw fracture, a screw of PEEK could be removed more easily. M1.6-abutment screws of four different PEEK compounds were subjected to tensile tests to set their maximum tensile strengths in relation to an equivalent stress of 186MPa, which is aused by a tightening torque of 15Ncm. Two screw types were manufactured via injection molding and contained 15% short carbon fibers (sCF-15) and 40% (sCF-40), respectively. Two screw types were manufactured via milling and contained 20% TiO2 powder (TiO2-20) and >50% parallel orientated, continuous carbon fibers (cCF-50). A conventional abutments screw of Ti6Al4V (Ti; CAMLOG(®) abutment screw, CAMLOG, Wimsheim, Germany) served as control. The maximum tensile strength was 76.08±5.50MPa for TiO2-20, 152.67±15.83MPa for sCF-15, 157.29±20.11MPa for sCF-40 and 191.69±36.33MPa for cCF-50. The maximum tensile strength of the Ti-screws amounted 1196.29±21.4MPa. The results of the TiO2-20 and the Ti screws were significantly different from the results of the other samples, respectively. For the manufacturing of PEEK abutment screws, PEEK reinforced by >50% continuous carbon fibers would be the material of choice. PMID:27434650

  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. Augmented reality for underground pipe inspection and maintenance

    NASA Astrophysics Data System (ADS)

    Lawson, Shaun W.; Pretlove, John R. G.

    1998-12-01

    The University of Surrey is engaged in developing augmented reality systems and teleoperation techniques for enhanced visual analysis and task performance in hostile environments. One particular current project in the UK is addressing the development of stereo vision systems, augmented reality, image processing techniques and specialist robotic vehicles which may be used for the future examination and maintenance of underground sewage pipes. This paper describes the components of the stereo vision and augmented reality system and illustrates some preliminary results of the use of the stereo robotic system mounted on a mobile laboratory vehicle and calibrated using a pin-hole camera model.

  12. Augmentation of tendon-to-bone healing.

    PubMed

    Atesok, Kivanc; Fu, Freddie H; Wolf, Megan R; Ochi, Mitsuo; Jazrawi, Laith M; Doral, M Nedim; Lubowitz, James H; Rodeo, Scott A

    2014-03-19

    Tendon-to-bone healing is vital to the ultimate success of the various surgical procedures performed to repair injured tendons. Achieving tendon-to-bone healing that is functionally and biologically similar to native anatomy can be challenging because of the limited regeneration capacity of the tendon-bone interface. Orthopaedic basic-science research strategies aiming to augment tendon-to-bone healing include the use of osteoinductive growth factors, platelet-rich plasma, gene therapy, enveloping the grafts with periosteum, osteoconductive materials, cell-based therapies, biodegradable scaffolds, and biomimetic patches. Low-intensity pulsed ultrasound and extracorporeal shockwave treatment may affect tendon-to-bone healing by means of mechanical forces that stimulate biological cascades at the insertion site. Application of various loading methods and immobilization times influence the stress forces acting on the recently repaired tendon-to-bone attachment, which eventually may change the biological dynamics of the interface. Other approaches, such as the use of coated sutures and interference screws, aim to deliver biological factors while achieving mechanical stability by means of various fixators. Controlled Level-I human trials are required to confirm the promising results from in vitro or animal research studies elucidating the mechanisms underlying tendon-to-bone healing and to translate these results into clinical practice.

  13. Cortical screw trajectory for instrumentation and fusion in the setting of osteopathic compression fracture allows for percutaneous kyphoplasty for adjacent level compression fractures.

    PubMed

    Pacione, Donato; Kim, Irene; Wilson, Taylor A; Frempong-Boadu, Anthony

    2015-05-01

    Spinal fixation in the osteoporotic patient can be challenging due to the poor trabecular bone quality of the vertebral body. Patients with osteoporotic vertebral body compression fractures are at risk for future compression fractures at adjacent levels, especially after cement augmentation. The purpose of this technical report is to describe the utilization of a cortical screw trajectory along with kyphoplasty for a patient with an osteoporotic compression fracture as well as degenerative spinal disease. This trajectory allows for the possibility of percutaneous pedicle access in the event of future compression fractures. Our patient underwent a decompressive laminectomy and kyphoplasty at the level of an osteoporotic compression fracture. The fracture was stabilized with cortical screw instrumentation and fusion at a level above and a level below the fracture. Subsequently the patient developed an adjacent level fracture within the fusion construct. Due to the utilization of a cortical screw trajectory for the initial fusion, the traditional pedicle trajectory was still accessible. As a result, the new fracture was treated with a percutaneous kyphoplasty through a standard pedicle trajectory. In conclusion, the use of a cortical screw trajectory for stabilization of osteoporotic compression fractures provides for a stronger bone screw interface and avoids osteoporotic trabecular vertebral body bone. At the same time this trajectory allows for future percutaneous pedicular access in the event that the patient suffers future compression fractures.

  14. Cortical bone screw fixation in ionically modified apatite cements.

    PubMed

    Barralet, J E; Duncan, C O; Dover, M S; Bassett, D C; Nishikawa, H; Monaghan, A; Gbureck, U

    2005-05-01

    Hydroxyapatite cements are used in reconstruction of the face; usually in well-defined cavities where the cement can be stabilized without the need for internal fixation. A hydroxyapatite cement that could enable screw fixation and some loading therefore has considerable potential in maxillofacial reconstruction. It has been demonstrated recently that water demand of calcium phosphate cements can be reduced by ionically modifying the liquid component. This study investigated the capacity of an ionically modified precompacted apatite cement to retain self-tapping cortical bone screws. Screw pullout forces were determined in the direction of the screw long axis and perpendicular to it, using cortical bone and polymethylmethacrylate cement as a control. In bending pullout tests, measured forces to remove screws from ionically modified precompacted cement were insignificantly different from cortical bone. However, pullout forces of bone screws from hydroxyapatite cement decreased with aging time in vitro.

  15. Fracture fixation with two locking screws versus three non-locking screws

    PubMed Central

    Grawe, B.; Le, T.; Williamson, S.; Archdeacon, A.; Zardiackas, L.

    2012-01-01

    Objectives We aimed to further evaluate the biomechanical characteristics of two locking screws versus three standard bicortical screws in synthetic models of normal and osteoporotic bone. Methods Synthetic tubular bone models representing normal bone density and osteoporotic bone density were used. Artificial fracture gaps of 1 cm were created in each specimen before fixation with one of two constructs: 1) two locking screws using a five-hole locking compression plate (LCP) plate; or 2) three non-locking screws with a seven-hole LCP plate across each side of the fracture gap. The stiffness, maximum displacement, mode of failure and number of cycles to failure were recorded under progressive cyclic torsional and eccentric axial loading. Results Locking plates in normal bone survived 10% fewer cycles to failure during cyclic axial loading, but there was no significant difference in maximum displacement or failure load. Locking plates in osteoporotic bone showed less displacement (p = 0.02), but no significant difference in number of cycles to failure or failure load during cyclic axial loading (p = 0.46 and p = 0.25, respectively). Locking plates in normal bone had lower stiffness and torque during torsion testing (both p = 0.03), but there was no significant difference in rotation (angular displacement) (p = 0.84). Locking plates in osteoporotic bone showed lower torque and rotation (p = 0.008), but there was no significant difference in stiffness during torsion testing (p = 0.69). Conclusions The mechanical performance of locking plate constructs, using only two screws, is comparable to three non-locking screw constructs in osteoporotic bone. Normal bone loaded with either an axial or torsional moment showed slightly better performance with the non-locking construct. PMID:23610681

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

    PubMed Central

    Ulutaş, 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

  17. Minimally invasive mini open split-muscular percutaneous pedicle screw fixation of the thoracolumbar spine.

    PubMed

    Ulutaş, Murat; Seçer, Mehmet; Çelik, Suat Erol

    2015-03-01

    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

  18. Mutually Augmented Cognition

    NASA Astrophysics Data System (ADS)

    Friesdorf, Florian; Pangercic, Dejan; Bubb, Heiner; Beetz, Michael

    In mac, an ergonomic dialog-system and algorithms will be developed that enable human experts and companions to be integrated into knowledge gathering and decision making processes of highly complex cognitive systems (e.g. Assistive Household as manifested further in the paper). In this event we propose to join algorithms and methodologies coming from Ergonomics and Artificial Intelligence that: a) make cognitive systems more congenial for non-expert humans, b) facilitate their comprehension by utilizing a high-level expandable control code for human experts and c) augment representation of such cognitive system into “deep representation” obtained through an interaction with human companions.

  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. Use of polymethylmethacrylate to enhance screw fixation in bone.

    PubMed

    Cameron, H U; Jacob, R; Macnab, I; Pilliar, R M

    1975-07-01

    Pull-out testing of screws inserted into cement and bone under various conditions showed that the cement-screw complex was significantly stronger when the screw was placed in soft cement and the cement was allowed to polymerize without further manipulation. When screw fixation in osteoporotic bone was reinforced with cement, the bone was the weakest component in the system. Fixation under these conditions should be enhanced by increasing the area of contact between the cement and bone. By cooling the cement to prolong its working time, it could be injected with a syringe in such a way that maximum endosteal and periosteal contact was provided. PMID:1150708

  1. Vertebroplasty plus short segment pedicle screw fixation in a burst fracture model in cadaveric spines.

    PubMed

    Grossbach, Andrew J; Viljoen, Stephanus V; Hitchon, Patrick W; DeVries Watson, Nicole A; Grosland, Nicole M; Torner, James

    2015-05-01

    The current project investigates the role of vertebroplasty in supplementing short segment (SS) posterior instrumentation, only one level above and below a fracture. In the treatment of thoracolumbar burst fractures, long segment (LS) posterior instrumentation two levels above and below the fracture level has been used. In our study, burst fractures were produced at L1 in eight fresh frozen human cadaveric spines. The spines were then tested in three conditions: 1) intact, 2) after LS (T11-L3), 3) SS (T12-L2) instrumentation with pedicle screws and rods, and 4) short segment instrumentation plus cement augmentation of the fracture level (SSC). LS instrumentation was found to significantly reduce the motion at the instrumented level (T12-L2) as well as the levels immediately adjacent in flexion, extension and lateral bending. Similarly, SSC augmentation was found to significantly reduce the motion compared to intact at T12-L2 but still maintained the adjacent level motion. However, SS instrumentation alone did not significantly reduce the motion at T12-L2 except for left lateral bending. While LS instrumentation remains the most stable construct, SS instrumentation augmented with vertebroplasty at the fracture level increases rigidity in flexion, extension and right lateral bending beyond SS instrumentation alone. PMID:25769251

  2. Arthroscopic posterior cruciate ligament reconstruction using four-strand hamstring tendon graft and interference screws.

    PubMed

    Pinczewski, L A; Thuresson, P; Otto, D; Nyquist, F

    1997-10-01

    We describe an arthroscopic technique for reconstruction of the posterior cruciate ligament (PCL) using a four-strand hamstring tendon graft. The femoral tunnel is drilled via the anterolateral portal and the tibial tunnel through the skin incision from the graft harvest. The graft is pulled through the tunnels with pullout sutures and fastened with interference screws. The results to date are good and the procedure can often be performed as day surgery. PMID:9343661

  3. Percutaneous Vertebral Body Augmentation: An Updated Review

    PubMed Central

    Omidi-Kashani, Farzad

    2014-01-01

    There are many medical conditions like osteoporosis, tumor, or osteonecrosis that weaken the structural strength of the vertebral body and prone it to fracture. Percutaneous vertebral augmentation that is usually applied by polymethylmethacrylate is a relatively safe, effective, and long lasting procedure commonly performed in these situations. In this paper, we updated a review of biomechanics, indications, contraindications, surgical techniques, complications, and overall prognosis of these minimally invasive spinal procedures. PMID:25379561

  4. 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

  5. Expanded polytetrafluoroethylene augmentation of the lower face.

    PubMed

    Sherris, D A; Larrabee, W F

    1996-05-01

    Most options for rejuvenation of the lower face use soft-tissue fillers that augment the appropriate sites. Each of these options has associated risks and benefits. The U.S. Food and Drug Administration recently approved the use of expanded polytetrafluoroethylene (E-PTFE) as a soft-tissue filler in the face. From January 1991 through December 1993, the authors used E-PTFE soft-tissue patches for lower facial augmentation in 41 patients at 115 implant sites. Postsurgical follow-up has ranged from 2.5 to 4.5 years; during this time, complications have occurred in 4 patients. One implant had to be removed because of a seroma (1 patient), 4 implants required further secondary augmentation (2 patients), and 1 implant required revision because of malposition (1 patient). There have been no cases of implant infection, extrusion, long-term inflammation, or capsule formation. In this article, the authors review the technical aspects of E-PTFE use and discuss issues relating to the long-term efficacy of this new option for soft-tissue augmentation. The technique is also compared with other options for rejuvenation of the lower face. PMID:8628100

  6. 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

  7. Posterior spinal fusion using pedicle screws.

    PubMed

    Athanasakopoulos, Michael; Mavrogenis, Andreas F; Triantafyllopoulos, George; Koufos, Spiros; Pneumaticos, Spiros G

    2013-07-01

    Few clinical studies have reported polyetheretherketone (PEEK) rod pedicle screw spinal instrumentation systems (CD-Horizon Legacy PEEK rods; Medtronic, Minneapolis, Minnesota). This article describes a clinical series of 52 patients who underwent posterior spinal fusion using the PEEK Rod System between 2007 and 2010. Of the 52 patients, 25 had degenerative disk disease, 10 had lateral recess stenosis, 6 had degenerative spondylolisthesis, 6 had lumbar spine vertebral fracture, 4 had combined lateral recess stenosis and degenerative spondylolisthesis, and 1 had an L5 giant cell tumor. Ten patients had 1-segment fusion, 29 had 2-segment fusion, and 13 had 3-segment fusion. Mean follow-up was 3 years (range, 1.5-4 years); no patient was lost to follow-up. Clinical evaluation was performed using the Oswestry Disability Index and a low back and leg visual analog pain scale. Imaging evaluation of fusion was performed with standard and dynamic radiographs. Complications were recorded. Mean Oswestry Disability Index scores improved from 76% preoperatively (range, 52%-90%) to 48% at 6 weeks postoperatively, and to 34%, 28%, and 30% at 3, 6, and 12 months postoperatively, respectively. Mean low back and leg pain improved from 8 and 9 points preoperatively, respectively, to 6 and 5 points immediately postoperatively, respectively, and to 2 points each thereafter. Imaging union of the arthrodesis was observed in 50 (96%) patients by 1-year follow-up. Two patients sustained screw breakage: 1 had painful loss of sagittal alignment of the lumbar spine and underwent revision spinal surgery with pedicle screws and titanium rods and the other had superficial wound infection and was treated with wound dressing changes and antibiotics for 6 weeks. No adjacent segment degeneration was observed in any patient until the time of this writing. PMID:23823055

  8. Cement augmentation in vertebral burst fractures.

    PubMed

    Zaryanov, Anton V; Park, Daniel K; Khalil, Jad G; Baker, Kevin C; Fischgrund, Jeffrey S

    2014-01-01

    As a result of axial compression, traumatic vertebral burst fractures disrupt the anterior column, leading to segmental instability and cord compression. In situations with diminished anterior column support, pedicle screw fixation alone may lead to delayed kyphosis, nonunion, and hardware failure. Vertebroplasty and kyphoplasty (balloon-assisted vertebroplasty) have been used in an effort to provide anterior column support in traumatic burst fractures. Cited advantages are providing immediate stability, improving pain, and reducing hardware malfunction. When used in isolation or in combination with posterior instrumentation, these techniques theoretically allow for improved fracture reduction and maintenance of spinal alignment while avoiding the complications and morbidity of anterior approaches. Complications associated with cement use (leakage, systemic effects) are similar to those seen in the treatment of osteoporotic compression fractures; however, extreme caution must be used in fractures with a disrupted posterior wall.

  9. Injection of coal by screw feed

    NASA Technical Reports Server (NTRS)

    Fisher, R.

    1977-01-01

    The use of the screw feeder for injecting solids through a 20 to 30 psi barrier is common practice in the cement making industry. An analytical extrapolation of that design, accounting for pressure holding characteristics of a column of solids, shows that coal can be fed to zones at several hundred psi with minimal or no loss of gas. A series of curves showing the calculated pressure gradient through a moving column of solids is presented. Mean particle size, solids velocity, and column length are parameters. Further study of this system to evaluate practicality is recommended.

  10. Serious complication of cement augmentation for damaged pilot hole.

    PubMed

    Jung, Moon Young; Shin, Dong Ah; Hahn, In Bo; Kim, Tae Gon; Huh, Ryoong; Chung, Sang Sup

    2010-05-01

    Polymethl methacrylate (PMMA) screw reinforcement is frequently used in osteoporotic bone as well as in damaged pilot holes. However, PMMA use can be dangerous, since the amount of applied cement is uncontrolled. A 47-year-old male with traumatic cervical spondylolisthesis at C6-7 underwent anterior cervical plate fixation. During repeated drilling and tapping for false trajectory correction, a pilot hole was damaged. Although it was an unconventional method, PMMA augmentation was tried. However, PMMA was accidentally injected to the cervical spinal cord owing to lack of fluoroscopic guidance. The PMMA was surgically removed after corpectomy and durotomy. The patient had left side hemiparesis (Grade 2/5) immediately post operation. The patient improved spontaneously (Grade 4/5) except for 4th and 5th digit extension. Here, we report a rare complication of PMMA extrusion in the spinal cord during a damaged pilot hole injection, which has not previously been described. PMID:20376906

  11. Pyriform Aperture Augmentation as An Adjunct to Rhinoplasty.

    PubMed

    Yaremchuk, Michael J; Vibhakar, Dev

    2016-01-01

    Skeletal deficiency in the central midface impacts nasal aesthetics. This lack of lower face projection can be corrected by alloplastic augmentation of the pyriform aperture. Creating convexity in the deficient midface will make the nose seem less prominent. Augmentation of the pyriform aperture is, therefore, often a useful adjunct during the rhinoplasty procedure. Augmenting the skeleton in this area can alter the projection of the nasal base, the nasolabial angle, and the vertical plane of the lip. The implant design and surgical techniques described here are extensions of others' previous efforts to improve paranasal aesthetics. PMID:26616706

  12. Augmented reality system

    NASA Astrophysics Data System (ADS)

    Lin, Chien-Liang; Su, Yu-Zheng; Hung, Min-Wei; Huang, Kuo-Cheng

    2010-08-01

    In recent years, Augmented Reality (AR)[1][2][3] is very popular in universities and research organizations. The AR technology has been widely used in Virtual Reality (VR) fields, such as sophisticated weapons, flight vehicle development, data model visualization, virtual training, entertainment and arts. AR has characteristics to enhance the display output as a real environment with specific user interactive functions or specific object recognitions. It can be use in medical treatment, anatomy training, precision instrument casting, warplane guidance, engineering and distance robot control. AR has a lot of vantages than VR. This system developed combines sensors, software and imaging algorithms to make users feel real, actual and existing. Imaging algorithms include gray level method, image binarization method, and white balance method in order to make accurate image recognition and overcome the effects of light.

  13. NASA Communications Augmentation network

    NASA Astrophysics Data System (ADS)

    Omidyar, Guy C.; Butler, Thomas E.; Laios, Straton C.

    1990-09-01

    The NASA Communications (Nascom) Division of the Mission Operations and Data Systems Directorate (MO&DSD) is to undertake a major initiative to develop the Nascom Augmentation (NAUG) network to achieve its long-range service objectives for operational data transport to support the Space Station Freedom Program, the Earth Observing System (EOS), and other projects. The NAUG is the Nascom ground communications network being developed to accommodate the operational traffic of the mid-1990s and beyond. The NAUG network development will be based on the Open Systems Interconnection Reference Model (OSI-RM). This paper describes the NAUG network architecture, subsystems, topology, and services; addresses issues of internetworking the Nascom network with other elements of the Space Station Information System (SSIS); discusses the operations environment. This paper also notes the areas of related research and presents the current conception of how the network will provide broadband services in 1998.

  14. Magnetohydrodynamic Augmented Propulsion Experiment

    NASA Technical Reports Server (NTRS)

    Litchford, Ron J.

    2008-01-01

    Over the past several years, efforts have been under way to design and develop an operationally flexible research facility for investigating the use of cross-field MHD accelerators as a potential thrust augmentation device for thermal propulsion systems. The baseline configuration for this high-power experimental facility utilizes a 1.5-MWe multi-gas arc-heater as a thermal driver for a 2-MWe MHD accelerator, which resides in a large-bore 2-tesla electromagnet. A preliminary design study using NaK seeded nitrogen as the working fluid led to an externally diagonalized segmented MHD channel configuration based on an expendable heat-sink design concept. The current status report includes a review of engineering/design work and performance optimization analyses and summarizes component hardware fabrication and development efforts, preliminary testing results, and recent progress toward full-up assembly and testing

  15. NAESA Augmentation Pilot Project

    NASA Technical Reports Server (NTRS)

    Hoover, John J.

    1998-01-01

    This project was one project within the Native American Earth and Space Academy (NAESA). NAESA is a national initiative comprised of several organizations that support programs which focus on 1) enhancing the technological, scientific and pedagogical skills of K-14 teachers who instruct Native Americans, 2) enhancing the understanding and applications of science, technology, and engineering of college-bound Native Americans and teaching them general college "survival skills" (e.g., test taking, time management, study habits), 3) enhancing the scientific and pedagogical skills of the faculty of tribally-controllcd colleges and community colleges with large Native American enrollments, and 4) strengthening the critical relationships between students, their parents, tribal elders, and their communities. This Augmentation Pilot Project focused on the areas of community-school alliances and intemet technology use in teaching and learning and daily living addressing five major objectives.

  16. Augmented kinematic feedback system

    NASA Astrophysics Data System (ADS)

    Andert, Ed P., Jr.; Archipley-Smith, Donna K.

    1994-07-01

    This paper discusses a real-time augmented kinematic feedback system which can be used as a diagnosis tool for individuals with motor disabilities. The system captures and analyzes movement via color targets attached to an individual and then feeds back information about movement kinematics. This target tracking approach has a high potential for achieving a real- time kinematic assessment capability. The approach recognizes distinct moving colored targets using video data. Multiple colored targets are attached to an individual at strategic locations and then target movement is tracked using a video data acquisition system. The ability to track and assess movement in real-time allows researchers and practitioners to better study and potentially treat various motor disabilities. Recent research has suggested that kinematic feedback can enhance motor recovery of disabled individuals. This approach addresses the need for a real-time measure of human movement and discusses using kinematic feedback to enhance disability recovery.

  17. Augmented Virtual Reality Laboratory

    NASA Technical Reports Server (NTRS)

    Tully-Hanson, Benjamin

    2015-01-01

    Real time motion tracking hardware has for the most part been cost prohibitive for research to regularly take place until recently. With the release of the Microsoft Kinect in November 2010, researchers now have access to a device that for a few hundred dollars is capable of providing redgreenblue (RGB), depth, and skeleton data. It is also capable of tracking multiple people in real time. For its original intended purposes, i.e. gaming, being used with the Xbox 360 and eventually Xbox One, it performs quite well. However, researchers soon found that although the sensor is versatile, it has limitations in real world applications. I was brought aboard this summer by William Little in the Augmented Virtual Reality (AVR) Lab at Kennedy Space Center to find solutions to these limitations.

  18. 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.

  19. Bone impregnated hip screw in femoral neck fracture: Clinicoradiological results

    PubMed Central

    Sundar Raj, PK; Nuuman, Jiju A; Pattathil, Amish Sunder

    2015-01-01

    Background: Femoral neck fractures are treated either by internal fixation or arthroplasty. Usually, cannulated cancellous screws are used for osteosynthesis of fracture neck of femur. The bone impregnated hip screw (BIHS) is an alternative implant, where osteosyntehsis is required in femoral neck fracture. Materials and Methods: The BIHS is a hollow screw with thread diameter 8.3 mm, shank diameter 6.5 mm and wall thickness 2.2 mm and holes in the shaft of the screw with diameter 2 mm, placed in a staggered fashion. Biomechanical and animal experimental studies were done. Clinical study was done in two phases: Phase 1 in a group of volunteers, only with BIHS was used in a pilot study and phase 2 comparative study was done in a group with AO cannulated screws and the other group treated with BIHS. Results: In the phase 1 study, out of 15 patients, only one patient had delayed union. In phase 2, there were 78 patients, 44 patients in BIHS showed early union, compared to the rest 34 cases of AO cannulated screws Out of 44 patients with BIHS, 41 patients had an excellent outcome, 2 had nonunions and one implant breakage was noted. Conclusions: Bone impregnated hip screw has shown to provide early solid union since it incorporates the biomechanical principles and also increases the osteogenic potential and hence, found superior to conventional cannulated cancellous screw. PMID:26015608

  20. Clinical results of autologous bone augmentation harvested from the mandibular ramus prior to implant placement. An analysis of 104 cases

    PubMed Central

    Sakkas, Andreas; Ioannis, Konstantinidis; Winter, Karsten; Schramm, Alexander; Wilde, Frank

    2016-01-01

    Background: The aim of this study was the evaluation of the clinical success and complication rates associated with autologous bone grafts harvested from the mandibular ramus for alveolar ridge augmentation and the identification of possible risk factors for graft failure. Methods: In a consecutive retrospective study 86 patients could be included. In these patients a total of 104 bone grafts from the mandibular ramus were harvested for alveolar ridge augmentation. Medical history, age of patient, smoking status, periodontal status and complications were recorded. The need for bone grafting was defined by the impossibility of installing dental implants of adequate length or diameter to fulfill prosthetic requirements, or for aesthetic reasons. The surgical outcome was evaluated concerning complications at the donor or at the recipient site, risk factors associated with the complications and graft survival. All patients were treated using a two-stage technique. In the first operation bone blocks harvested from the retromolar region were placed as lateral or vertical onlay grafts using augmentation templates and were fixed with titanium osteosynthesis screws after exposure of the deficient alveolar ridge. After a healing period of 3–5 months computed tomography scans were performed followed by virtual implant planning and the implants were inserted using guided dental implantation. Results: 97 of the 104 onlay bone grafts were successful. In only 7 patients a graft failure occurred after a postsurgical complication. No long-term nerve damage occurred. Postoperative nerve disturbances were reported by 11 patients and had temporary character only. After the healing period between 4 to 5 months, 155 implants were placed (39 in the maxilla, 116 in the mandible). A final rehabilitation with dental implants was possible in 82 of the 86 patients. Except the 7 graft failures, all recorded complications were minor complications which could be easily treated successfully

  1. Ball Screw Actuator Including an Axial Soft Stop

    NASA Technical Reports Server (NTRS)

    Wingett, Paul T. (Inventor); Forrest, Steven Talbert (Inventor); Abel, Steve (Inventor); Woessner, George (Inventor); Hanlon, Casey (Inventor)

    2016-01-01

    An actuator includes an actuator housing, a ball screw, and an axial soft stop assembly. The ball screw extends through the actuator housing and has a first end and a second end. The ball screw is coupled to receive a drive force and is configured, upon receipt of the drive force, to selectively move in a retract direction and an extend direction. The axial soft stop assembly is disposed within the actuator housing. The axial soft stop assembly is configured to be selectively engaged by the ball screw and, upon being engaged thereby, to translate, with compliance, a predetermined distance in the extend direction, and to prevent further movement of the ball screw upon translating the predetermined distance.

  2. A simple model of throughput calculation for single screw

    NASA Astrophysics Data System (ADS)

    Béreaux, Yves; Charmeau, Jean-Yves; Moguedet, Maël

    2007-04-01

    To be able to predict the throughput of a single-screw extruder or the metering time of an injection moulding machine for a given screw geometry, set of processing conditions and polymeric material is important both for practical and designing purposes. Our simple model show that the screw geometry is the most important parameter, followed by polymer rheology and processing conditions. Melting properties and length seem to intervene to a lesser extent. The calculations hinges on the idea of viewing the entire screw as a pump, conveying a solid and a molten fraction. The evolution of the solid fraction is the essence of the plastication process, but under particular circumstances, its influence on the throughput is nil. This allows us to get a very good estimate on the throughput and pressure development along the screw. Our calculations are compared to different sets of experiments available from the literature. We have consistent agreement both in throughput and pressure with published data.

  3. Effect of screw access hole preparation on fracture load of implant-supported zirconia-based crowns: an in vitro study.

    PubMed

    Mokhtarpour, Hadi; Eftekhar Ashtiani, Reza; Mahshid, Minoo; Tabatabaian, Farhad; Alikhasi, Marzieh

    2016-01-01

    Background. Fracture load of implant-supported restorations is an important factor in clinical success. This study evaluated the effect of two techniques for screw access hole preparation on the fracture load of cement-screw-retained implant-supported zirconia-based crowns. Methods. Thirty similar cement-screw-retained implant-supported zirconia-based maxillary central incisor crowns were evaluated in three groups of 10. Group NH: with no screw access holes for the control; Group HBS: with screw access holes prepared with a machine before zirconia sintering; Group HAS: with screw access holes prepared manually after zirconia sintering. In group HBS, the access holes were virtually designed and prepared by a computer-assisted design/computer-assisted manufacturing system. In group HAS, the access holes were manually prepared after zirconia sintering using a diamond bur. The dimensions of the screw access holes were equal in both groups. The crowns were cemented onto same-size abutments and were then subjected to thermocycling. The fracture load values of the crowns were measured using a universal testing machine. Data were analyzed with ANOVA and Tukey test (P < 0.05). Results. The mean fracture load value for the group NH was 888.37 ± 228.92 N, which was the highest among the groups, with a significant difference (P < 0.0001). The fracture load values were 610.48 ± 125.02 N and 496.74 ± 104.10 Nin the HBS and HAS groups, respectively, with no significant differences (P = 0.44). Conclusion. Both techniques used for preparation of screw access holes in implant-supported zirconia-based crowns decreased the fracture load. PMID:27651885

  4. Effect of screw access hole preparation on fracture load of implant-supported zirconia-based crowns: an in vitro study.

    PubMed

    Mokhtarpour, Hadi; Eftekhar Ashtiani, Reza; Mahshid, Minoo; Tabatabaian, Farhad; Alikhasi, Marzieh

    2016-01-01

    Background. Fracture load of implant-supported restorations is an important factor in clinical success. This study evaluated the effect of two techniques for screw access hole preparation on the fracture load of cement-screw-retained implant-supported zirconia-based crowns. Methods. Thirty similar cement-screw-retained implant-supported zirconia-based maxillary central incisor crowns were evaluated in three groups of 10. Group NH: with no screw access holes for the control; Group HBS: with screw access holes prepared with a machine before zirconia sintering; Group HAS: with screw access holes prepared manually after zirconia sintering. In group HBS, the access holes were virtually designed and prepared by a computer-assisted design/computer-assisted manufacturing system. In group HAS, the access holes were manually prepared after zirconia sintering using a diamond bur. The dimensions of the screw access holes were equal in both groups. The crowns were cemented onto same-size abutments and were then subjected to thermocycling. The fracture load values of the crowns were measured using a universal testing machine. Data were analyzed with ANOVA and Tukey test (P < 0.05). Results. The mean fracture load value for the group NH was 888.37 ± 228.92 N, which was the highest among the groups, with a significant difference (P < 0.0001). The fracture load values were 610.48 ± 125.02 N and 496.74 ± 104.10 Nin the HBS and HAS groups, respectively, with no significant differences (P = 0.44). Conclusion. Both techniques used for preparation of screw access holes in implant-supported zirconia-based crowns decreased the fracture load.

  5. Effect of screw access hole preparation on fracture load of implant-supported zirconia-based crowns: an in vitro study

    PubMed Central

    Mokhtarpour, Hadi; Eftekhar Ashtiani, Reza; Mahshid, Minoo; Tabatabaian, Farhad; Alikhasi, Marzieh

    2016-01-01

    Background. Fracture load of implant-supported restorations is an important factor in clinical success. This study evaluated the effect of two techniques for screw access hole preparation on the fracture load of cement-screw-retained implant-supported zirconia-based crowns. Methods. Thirty similar cement-screw-retained implant-supported zirconia-based maxillary central incisor crowns were evaluated in three groups of 10. Group NH: with no screw access holes for the control; Group HBS: with screw access holes prepared with a machine before zirconia sintering; Group HAS: with screw access holes prepared manually after zirconia sintering. In group HBS, the access holes were virtually designed and prepared by a computer-assisted design/computer-assisted manufacturing system. In group HAS, the access holes were manually prepared after zirconia sintering using a diamond bur. The dimensions of the screw access holes were equal in both groups. The crowns were cemented onto same-size abutments and were then subjected to thermocycling. The fracture load values of the crowns were measured using a universal testing machine. Data were analyzed with ANOVA and Tukey test (P < 0.05). Results. The mean fracture load value for the group NH was 888.37 ± 228.92 N, which was the highest among the groups, with a significant difference (P < 0.0001). The fracture load values were 610.48 ± 125.02 N and 496.74 ± 104.10 Nin the HBS and HAS groups, respectively, with no significant differences (P = 0.44). Conclusion. Both techniques used for preparation of screw access holes in implant-supported zirconia-based crowns decreased the fracture load.

  6. Effect of screw access hole preparation on fracture load of implant-supported zirconia-based crowns: an in vitro study

    PubMed Central

    Mokhtarpour, Hadi; Eftekhar Ashtiani, Reza; Mahshid, Minoo; Tabatabaian, Farhad; Alikhasi, Marzieh

    2016-01-01

    Background. Fracture load of implant-supported restorations is an important factor in clinical success. This study evaluated the effect of two techniques for screw access hole preparation on the fracture load of cement-screw-retained implant-supported zirconia-based crowns. Methods. Thirty similar cement-screw-retained implant-supported zirconia-based maxillary central incisor crowns were evaluated in three groups of 10. Group NH: with no screw access holes for the control; Group HBS: with screw access holes prepared with a machine before zirconia sintering; Group HAS: with screw access holes prepared manually after zirconia sintering. In group HBS, the access holes were virtually designed and prepared by a computer-assisted design/computer-assisted manufacturing system. In group HAS, the access holes were manually prepared after zirconia sintering using a diamond bur. The dimensions of the screw access holes were equal in both groups. The crowns were cemented onto same-size abutments and were then subjected to thermocycling. The fracture load values of the crowns were measured using a universal testing machine. Data were analyzed with ANOVA and Tukey test (P < 0.05). Results. The mean fracture load value for the group NH was 888.37 ± 228.92 N, which was the highest among the groups, with a significant difference (P < 0.0001). The fracture load values were 610.48 ± 125.02 N and 496.74 ± 104.10 Nin the HBS and HAS groups, respectively, with no significant differences (P = 0.44). Conclusion. Both techniques used for preparation of screw access holes in implant-supported zirconia-based crowns decreased the fracture load. PMID:27651885

  7. Augmented Reality Comes to Physics

    ERIC Educational Resources Information Center

    Buesing, Mark; Cook, Michael

    2013-01-01

    Augmented reality (AR) is a technology used on computing devices where processor-generated graphics are rendered over real objects to enhance the sensory experience in real time. In other words, what you are really seeing is augmented by the computer. Many AR games already exist for systems such as Kinect and Nintendo 3DS and mobile apps, such as…

  8. Multiple impacted urethral metallic needles and screws (foreign bodies) associated with polyembolokoilamania.

    PubMed

    Singh, Iqbal; Pal, Ajay Kumar; Gautam, Lokesh

    2015-04-01

    This study aims to present the challenges faced in the management of multiple impacted foreign bodies, needles, and screws from the penile and bulbar urethra. A young man presented with complaint of a hard perineal swelling and passage of metallic nails per urethra. Pelvic radiograph revealed multiple foreign bodies (nails) in the penile and bulbar urethra. Successful cystoscopic removal of 11 foreign bodies comprising four large metallic screws and seven nail-like large sewing needles was done in two sessions. The most prevalent motivation for self-insertion of urethral foreign bodies is autoerotism/psychological impairment. Appropriate surgical technique guided by physical examination/ imaging with endoscopic removal is often successful, depending on the object's physical attributes and morphology while minimizing urothelial trauma and preserving voiding and erectile function. Follow-up cystourethroscopy is important for diagnosing any complications and urothelial injuries.

  9. Arthroscopic Treatment for Shoulder Instability with Glenoid Bone Loss Using Distal Tibia Allograft Augmentation - Short Term Results

    PubMed Central

    Wong, Ivan; Amar, Eyal; Coady, Catherine M.; Dilman, Daryl B.; Smith, Ben

    2016-01-01

    Objectives: Background: The results of arthroscopic anterior labral (Bankart) repair have been shown to have high failure rate in patients with significant glenoid bone loss. Several reconstruction procedures using bone graft have been described to overcome the bone loss, including autogenous coracoid transfer to the anterior glenoid (Latarjet procedure) as well as iliac crest autograft and tibial allografts. In recent years, trends toward minimally invasive shoulder surgery along with improvements in technology and technique have led surgeons to expand the application of arthroscopic treatment. Purpose: This study aims to perform a retrospective analysis of prospectively collected data to evaluate the clinical and radiological follow up of patient who underwent anatomic glenoid reconstruction using distal tibia allograft for the treatment of shoulder instability with glenoid bone loss at 1-year post operation time point. Methods: Between December 2011 and January 2015, 55 patients underwent arthroscopic stabilization of the shoulder by means of capsule-labral reattachment to glenoid ream and bony augmentation of glenoid bone loss with distal tibial allograft for recurrent instability of the shoulder. Preoperative and postoperative evaluation included general assessment by the western Ontario shoulder instability index (WOSI) questionnaire, preoperative and postoperative radiographs and CT scans. Results: Fifty-five patients have been evaluated with mean age of 29.73 years at time of the index operation. There were 40 males (mean age of 29.66) and 15 female (mean age of 29.93). Minimum follow up time was 12 months. The following adverse effects were recorded: none suffered from recurrent dislocation, 2 patients suffered from bone resorption but without overt instability, 1 patient had malunion due to screw fracture, none of the patients had nonunion. The mean pre-operative WOSI score was 36.54 and the mean postoperative WOSI score was 61.0. Conclusion: Arthroscopic

  10. Augmented Likelihood Image Reconstruction.

    PubMed

    Stille, Maik; Kleine, Matthias; Hägele, Julian; Barkhausen, Jörg; Buzug, Thorsten M

    2016-01-01

    The presence of high-density objects remains an open problem in medical CT imaging. Data of projections passing through objects of high density, such as metal implants, are dominated by noise and are highly affected by beam hardening and scatter. Reconstructed images become less diagnostically conclusive because of pronounced artifacts that manifest as dark and bright streaks. A new reconstruction algorithm is proposed with the aim to reduce these artifacts by incorporating information about shape and known attenuation coefficients of a metal implant. Image reconstruction is considered as a variational optimization problem. The afore-mentioned prior knowledge is introduced in terms of equality constraints. An augmented Lagrangian approach is adapted in order to minimize the associated log-likelihood function for transmission CT. During iterations, temporally appearing artifacts are reduced with a bilateral filter and new projection values are calculated, which are used later on for the reconstruction. A detailed evaluation in cooperation with radiologists is performed on software and hardware phantoms, as well as on clinically relevant patient data of subjects with various metal implants. Results show that the proposed reconstruction algorithm is able to outperform contemporary metal artifact reduction methods such as normalized metal artifact reduction.

  11. Control Augmented Structural Synthesis

    NASA Technical Reports Server (NTRS)

    Lust, Robert V.; Schmit, Lucien A.

    1988-01-01

    A methodology for control augmented structural synthesis is proposed for a class of structures which can be modeled as an assemblage of frame and/or truss elements. It is assumed that both the plant (structure) and the active control system dynamics can be adequately represented with a linear model. The structural sizing variables, active control system feedback gains and nonstructural lumped masses are treated simultaneously as independent design variables. Design constraints are imposed on static and dynamic displacements, static stresses, actuator forces and natural frequencies to ensure acceptable system behavior. Multiple static and dynamic loading conditions are considered. Side constraints imposed on the design variables protect against the generation of unrealizable designs. While the proposed approach is fundamentally more general, here the methodology is developed and demonstrated for the case where: (1) the dynamic loading is harmonic and thus the steady state response is of primary interest; (2) direct output feedback is used for the control system model; and (3) the actuators and sensors are collocated.

  12. Structural consequences of railgun augmentation

    SciTech Connect

    Wellman, G.W.; Schuler, K.W.

    1988-01-01

    An augmented railgun can provide the same driving force on a projectile at a lower plasma arc current and thus less potential erosion and barrel damage as an unaugmented railgun. However, there are structural consequences to railgun augmentation which must be overcome before the advantages of lower plasma arc currents can be realized. To investigate these consequences, a bolted V-block supporting structure is considered with two cores; unaugmented (a single pair of conducting rails), and augmented (conducting rails augmented by a second tandem set of conductors). The mechanical load on the cores consist of the static bolt preload, the plasma pressure behind the projectile, and the magnetic pressure induced by currents flowing in the rails or augmenting conductors. Assuming no current diffusion into the conductors, the magnetic pressure distribution on the conductors is determined by solving the two-dimensional magnetostatic field equations using an analogy with heat transfer. These loads are then used in a dynamic finite element structural model. The maximum rail current is found at which the unaugmented railgun can be repetitively fired without detrimental gaps forming at the bore. For the augmented railgun, at the same projectile acceleration, large permanent deformations can occur. Thus successful implementation of rail gun augmentation will require improvement of the supporting structure.

  13. Structural consequences of railgun augmentation

    SciTech Connect

    Wellman, G.W.; Schuler, K.W. . Applied Mechanics Div. III)

    1989-01-01

    An augmented railgun can provide the same driving force on a projectile at a lower plasma arc current and thus less potential erosion and barrel damage as an unaugmented railgun. However, there are structural consequences to railgun augmentation which must be overcome before the advantages of lower plasma arc currents can be realized. To investigate these consequences, a bolted V-block supporting structure is considered with two cores; unaugmented (a single pair of conducting rails), and augmented (conducting rails augmented by a second tandem set of conductors). The mechanical load on the cores consist of the static bolt preload, the plasma pressure behind the projectile, and the magnetic pressure induced by currents flowing in the rails or augmenting conductors. Assuming no current diffusion into the conductors, the magnetic pressure distribution on the conductors is determined by solving the two dimensional magnetostatic field equations using an analogy with heat transfer. These loads are then used in a dynamic finite element structural model. The maximum rail current is found at which the unaugmented railgun can be repetitively fired without detrimental gaps forming at the bore. For the augmented railgun, at the same projectile acceleration, large permanent deformations can occur. Thus successful implementation of rail gun augmentation will require improvement of the supporting structure.

  14. Technique of Open Reduction and Internal Fixation of Comminuted Proximal Humerus Fractures With Allograft Femoral Head Metaphyseal Reconstruction.

    PubMed

    Parada, Stephen A; Makani, Amun; Stadecker, Monica J; Warner, Jon J P

    2015-10-01

    Proximal humerus fractures are common injuries that can require operative treatment. Different operative techniques are available, but the hallmark of fixation for 3- and 4-part fractures is a locking-plate-and-screw construct. Despite advances in this technology, obtaining anatomical reduction and fracture union can be difficult, and complications (eg, need for revision) are not uncommon. These issues can be addressed by augmenting the fixation with an endosteally placed fibular allograft. Although biomechanical and clinical results have been good, the technique can lead to difficulties in future revision to arthroplasty, a common consequence of failed open reduction and internal fixation. The technique described, an alternative to placing a long endosteal bone graft, uses a trapezoidal, individually sized pedestal of allograft femoral head to facilitate the reduction and healing of the humeral head and tuberosity fragments in a displaced 3- or 4-part fracture of the proximal humerus. It can be easily incorporated with any plate-and-screw construct and does not necessitate placing more than 1 cm of bone into the humeral intramedullary canal, limiting the negative effects on any future revision to arthroplasty.

  15. Management of a fractured implant abutment screw: a clinical report.

    PubMed

    Canpolat, Ceyhun; Ozkurt-Kayahan, Zeynep; Kazazoğlu, Ender

    2014-07-01

    In an abutment screw fracture, it is generally a challenge for the clinician to remove fractured fragments. In some cases, the screw cannot be removed, and alternative solutions should be considered. This clinical report describes the replacement of a ball attachment with a fractured screw, which was impossible to retrieve, with a cast dowel with ball attachment. The patient who presented to the Department of Prosthodontics, Yeditepe University, Faculty of Dentistry was a 65-year-old woman, wearing a mandibular complete denture supported by two implants for 4 years. She complained about the loss of retention of the denture because of the fractured abutment screw, and it was found that another dentist had previously tried to retrieve the fractured screw with no success. It was decided to construct a cast dowel with ball attachment to improve retention without sacrificing the implant. The interior of the implant and the fractured screw were machined with a rotating instrument. An impression was taken with a metal strip and silicone-based materials. In the laboratory, a stone die was generated from the impression, and a custom-made cast dowel with ball attachment was constructed. It was then cemented with glass ionomer cement and connected to the denture with the direct method. The alternative procedure described in this clinical report was successful for the removal of the fractured abutment screw and use of the existing denture.

  16. Cortical bone trajectory screws for the middle-upper thorax

    PubMed Central

    Sheng, Sun-Ren; Chen, Jiao-Xiang; Chen, Wei; Xue, En-Xing; Wang, Xiang-Yang; Zhu, Qing-An

    2016-01-01

    Abstract To quantify the reference data concerning the morphometrics of the middle-upper thorax to guide the placement of cortical bone trajectory (CBT) screws. Eighty patients were studied on computed tomography (CT) scans. The reference anatomical parameters were measured. Next, 20 cadaveric specimens were implanted with CBT screws based on CT measurements. These specimens were then judged directly from the cadaveric vertebrae and X-ray. The maximum length of the trajectory, the maximum diameter, and the cephaled angle exhibited a slight increase trend while the transverse and sagittal angles of the pedicle tended to decrease from T3 to T8. We recommend that the width of CBT screw for middle-upper thoracic spine is 5.0 mm, the length is 25 to 35 mm. The cadaveric anatomical study revealed that 5/240 screws penetrated in the medial or lateral areas, 5/240 screws penetrated in the superior or inferior pedicle wall, and 2/240 screws did not fit into the superior endplate of the pedicle. The CBT screws are safe for the middle-upper thorax. This study provides a theoretical basis for clinical surgery. PMID:27583893

  17. Augmented Reality Comes to Physics

    NASA Astrophysics Data System (ADS)

    Buesing, Mark; Cook, Michael

    2013-04-01

    Augmented reality (AR) is a technology used on computing devices where processor-generated graphics are rendered over real objects to enhance the sensory experience in real time. In other words, what you are really seeing is augmented by the computer. Many AR games already exist for systems such as Kinect and Nintendo 3DS and mobile apps, such as Tagwhat and Star Chart (a must for astronomy class). The yellow line marking first downs in a televised football game2 and the enhanced puck that makes televised hockey easier to follow3 both use augmented reality to do the job.

  18. 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

  19. Spline-locking screw fastening strategy

    NASA Technical Reports Server (NTRS)

    Vranish, John M.

    1992-01-01

    A fastener was developed by NASA Goddard for efficiently performing assembly, maintenance, and equipment replacement functions in space using either robotics or astronaut means. This fastener, the 'Spline Locking Screw' (SLS) would also have significant commercial value in advanced space manufacturing. Commercial (or DoD) products could be manufactured in such a way that their prime subassemblies would be assembled using SLS fasteners. This would permit machines and robots to disconnect and replace these modules/parts with ease, greatly reducing life cycle costs of the products and greatly enhancing the quality, timeliness, and consistency of repairs, upgrades, and remanufacturing. The operation of the basic SLS fastener is detailed, including hardware and test results. Its extension into a comprehensive fastening strategy for NASA use in space is also outlined. Following this, the discussion turns toward potential commercial and government applications and the potential market significance of same.

  20. Spline-Locking Screw Fastening Strategy (SLSFS)

    NASA Technical Reports Server (NTRS)

    Vranish, John M.

    1991-01-01

    A fastener was developed by NASA Goddard for efficiently performing assembly, maintenance, and equipment replacement functions in space using either robotic or astronaut means. This fastener, the 'Spline Locking Screw' (SLS) would also have significant commercial value in advanced manufacturing. Commercial (or DoD) products could be manufactured in such a way that their prime subassemblies would be assembled using SLS fasteners. This would permit machines and robots to disconnect and replace these modules/parts with ease, greatly reducing life cycle costs of the products and greatly enhancing the quality, timeliness, and consistency of repairs, upgrades, and remanufacturing. The operation of the basic SLS fastener is detailed, including hardware and test results. Its extension into a comprehensive fastening strategy for NASA use in space is also outlined. Following this, the discussion turns toward potential commercial and government applications and the potential market significance of same.

  1. Spline-Screw Payload-Fastening System

    NASA Technical Reports Server (NTRS)

    Vranish, John M.

    1994-01-01

    Payload handed off securely between robot and vehicle or structure. Spline-screw payload-fastening system includes mating female and male connector mechanisms. Clockwise (or counter-clockwise) rotation of splined male driver on robotic end effector causes connection between robot and payload to tighten (or loosen) and simultaneously causes connection between payload and structure to loosen (or tighten). Includes mechanisms like those described in "Tool-Changing Mechanism for Robot" (GSC-13435) and "Self-Aligning Mechanical and Electrical Coupling" (GSC-13430). Designed for use in outer space, also useful on Earth in applications needed for secure handling and secure mounting of equipment modules during storage, transport, and/or operation. Particularly useful in machine or robotic applications.

  2. A comparative study of fixation techniques for type II fractures of the odontoid process.

    PubMed

    Graziano, G; Jaggers, C; Lee, M; Lynch, W

    1993-12-01

    Primary screw fixation of a Type II odontoid fracture or non-union is an attractive alternative to posterior atlanto-axial arthrodesis in that normal cervical motion can be maintained. Eight cervical cadaver spines, ranging in age from 17-90 years, were used for study. Type II fractures of the dens were created using an osteotome. Simulated fractures were fixed using one or two 3.5-mm bone screws. After testing each screw fixation technique, the screws were removed and a posterior C1-C2 brooks sublaminar wiring was performed using four 18-gauge wires with wooden blocks to simulate bone graft. No significant differences were found between bending and torsional stiffnesses for the one-screw and two-screw specimens. No significant differences were found between one- and two-screw fixation when compared with primary C1-C2 wiring in torsion. One- or two-screw fixation was as stiff as primary C1-C2 wiring in bending. One or two screws offers similar stability for fixation for a dens fracture. One- and two-screw fixation is at least as stiff as primary C1-C2 wiring in torsion and one- or two-screw fixation is stiffer than primary C1-C2 wiring in bending. PMID:8303437

  3. Implant augmentation: adding bone cement to improve the treatment of osteoporotic distal femur fractures: a biomechanical study using human cadaver bones.

    PubMed

    Wähnert, Dirk; Hofmann-Fliri, Ladina; Richards, R Geoff; Gueorguiev, Boyko; Raschke, Michael J; Windolf, Markus

    2014-11-01

    The increasing problems in the field of osteoporotic fracture fixation results in specialized implants as well as new operation methods, for example, implant augmentation with bone cement. The aim of this study was to determine the biomechanical impact of augmentation in the treatment of osteoporotic distal femur fractures.Seven pairs of osteoporotic fresh frozen distal femora were randomly assigned to either an augmented or nonaugmented group. In both groups, an Orthopaedic Trauma Association 33 A3 fractures was fixed using the locking compression plate distal femur and cannulated and perforated screws. In the augmented group, additionally, 1 mL of polymethylmethacrylate cement was injected through the screw. Prior to mechanical testing, bone mineral density (BMD) and local bone strength were determined. Mechanical testing was performed by cyclic axial loading (100 N to 750 N + 0.05N/cycle) using a servo-hydraulic testing machine.As a result, the BMD as well as the axial stiffness did not significantly differ between the groups. The number of cycles to failure was significantly higher in the augmented group with the BMD as a significant covariate.In conclusion, cement augmentation can significantly improve implant anchorage in plating of osteoporotic distal femur fractures. PMID:25415673

  4. Implant augmentation: adding bone cement to improve the treatment of osteoporotic distal femur fractures: a biomechanical study using human cadaver bones.

    PubMed

    Wähnert, Dirk; Hofmann-Fliri, Ladina; Richards, R Geoff; Gueorguiev, Boyko; Raschke, Michael J; Windolf, Markus

    2014-11-01

    The increasing problems in the field of osteoporotic fracture fixation results in specialized implants as well as new operation methods, for example, implant augmentation with bone cement. The aim of this study was to determine the biomechanical impact of augmentation in the treatment of osteoporotic distal femur fractures.Seven pairs of osteoporotic fresh frozen distal femora were randomly assigned to either an augmented or nonaugmented group. In both groups, an Orthopaedic Trauma Association 33 A3 fractures was fixed using the locking compression plate distal femur and cannulated and perforated screws. In the augmented group, additionally, 1 mL of polymethylmethacrylate cement was injected through the screw. Prior to mechanical testing, bone mineral density (BMD) and local bone strength were determined. Mechanical testing was performed by cyclic axial loading (100 N to 750 N + 0.05N/cycle) using a servo-hydraulic testing machine.As a result, the BMD as well as the axial stiffness did not significantly differ between the groups. The number of cycles to failure was significantly higher in the augmented group with the BMD as a significant covariate.In conclusion, cement augmentation can significantly improve implant anchorage in plating of osteoporotic distal femur fractures.

  5. Augmented Classical Least Squares Multivariate Spectral Analysis

    DOEpatents

    Haaland, David M.; Melgaard, David K.

    2005-01-11

    A method of multivariate spectral analysis, termed augmented classical least squares (ACLS), provides an improved CLS calibration model when unmodeled sources of spectral variation are contained in a calibration sample set. The ACLS methods use information derived from component or spectral residuals during the CLS calibration to provide an improved calibration-augmented CLS model. The ACLS methods are based on CLS so that they retain the qualitative benefits of CLS, yet they have the flexibility of PLS and other hybrid techniques in that they can define a prediction model even with unmodeled sources of spectral variation that are not explicitly included in the calibration model. The unmodeled sources of spectral variation may be unknown constituents, constituents with unknown concentrations, nonlinear responses, non-uniform and correlated errors, or other sources of spectral variation that are present in the calibration sample spectra. Also, since the various ACLS methods are based on CLS, they can incorporate the new prediction-augmented CLS (PACLS) method of updating the prediction model for new sources of spectral variation contained in the prediction sample set without having to return to the calibration process. The ACLS methods can also be applied to alternating least squares models. The ACLS methods can be applied to all types of multivariate data.

  6. Augmented Classical Least Squares Multivariate Spectral Analysis

    DOEpatents

    Haaland, David M.; Melgaard, David K.

    2005-07-26

    A method of multivariate spectral analysis, termed augmented classical least squares (ACLS), provides an improved CLS calibration model when unmodeled sources of spectral variation are contained in a calibration sample set. The ACLS methods use information derived from component or spectral residuals during the CLS calibration to provide an improved calibration-augmented CLS model. The ACLS methods are based on CLS so that they retain the qualitative benefits of CLS, yet they have the flexibility of PLS and other hybrid techniques in that they can define a prediction model even with unmodeled sources of spectral variation that are not explicitly included in the calibration model. The unmodeled sources of spectral variation may be unknown constituents, constituents with unknown concentrations, nonlinear responses, non-uniform and correlated errors, or other sources of spectral variation that are present in the calibration sample spectra. Also, since the various ACLS methods are based on CLS, they can incorporate the new prediction-augmented CLS (PACLS) method of updating the prediction model for new sources of spectral variation contained in the prediction sample set without having to return to the calibration process. The ACLS methods can also be applied to alternating least squares models. The ACLS methods can be applied to all types of multivariate data.

  7. Augmented classical least squares multivariate spectral analysis

    DOEpatents

    Haaland, David M.; Melgaard, David K.

    2004-02-03

    A method of multivariate spectral analysis, termed augmented classical least squares (ACLS), provides an improved CLS calibration model when unmodeled sources of spectral variation are contained in a calibration sample set. The ACLS methods use information derived from component or spectral residuals during the CLS calibration to provide an improved calibration-augmented CLS model. The ACLS methods are based on CLS so that they retain the qualitative benefits of CLS, yet they have the flexibility of PLS and other hybrid techniques in that they can define a prediction model even with unmodeled sources of spectral variation that are not explicitly included in the calibration model. The unmodeled sources of spectral variation may be unknown constituents, constituents with unknown concentrations, nonlinear responses, non-uniform and correlated errors, or other sources of spectral variation that are present in the calibration sample spectra. Also, since the various ACLS methods are based on CLS, they can incorporate the new prediction-augmented CLS (PACLS) method of updating the prediction model for new sources of spectral variation contained in the prediction sample set without having to return to the calibration process. The ACLS methods can also be applied to alternating least squares models. The ACLS methods can be applied to all types of multivariate data.

  8. Augmented amputations of the lower extremity.

    PubMed

    Mohler, D G; Kessler, J I; Earp, B E

    2000-02-01

    Ten patients who had amputations of a lower extremity for high-grade sarcomas underwent bone augmentation with either allograft or autograft between 1988 and 1996. There were eight transfemoral amputations and two transtibial amputations. The transferred segments consisted of one proximal tibia and six distal tibia autografts, two allografts, one autograft talar dome and first metatarsal, and one with a patellar cap of a supracondylar amputation. The average length of followup was 54 months. There were no nonunions of any of the grafts. There were three wound problems requiring additional operations. One autograft resorbed, and one autograft had a late infection. There was one local recurrence. Augmentation to provide length resulted in a 42% increase in bone length in those performed purely for length. All patients were able to use standard prostheses. Functional outcome was appropriate to the amputation level. Half of the patients avoided more proximal levels of amputation because of the ability to augment the osteotomy. The use of nonvascularized structural autografts or allografts is a simple procedure that can produce a superior residual limb in patients undergoing amputation. Its use should be considered in patients for whom traditional amputation techniques will result in poor function, difficulty in fitting a prosthesis, or greater than necessary anatomic loss. PMID:10693566

  9. 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.

  10. Effects of Lateral Mass Screw Rod Fixation to the Stability of Cervical Spine after Laminectomy

    NASA Astrophysics Data System (ADS)

    Rosli, Ruwaida; Kashani, Jamal; Kadir, Mohammed Rafiq Abdul

    There are many cases of injury in the cervical spine due to degenerative disorder, trauma or instability. This condition may produce pressure on the spinal cord or on the nerve coming from the spine. The aim of this study was, to analyze the stabilization of the cervical spine after undergoing laminectomy via computational simulation. For that purpose, a three-dimensional finite element (FE) model for the multilevel cervical spine segment (C1-C7) was developed using computed tomography (CT) data. There are various decompression techniques that can be applied to overcome the injury. Usually, decompression procedures will create an unstable spine. Therefore, in these situations, the spine is often surgically restabilized by using fusion and instrumentation. In this study, a lateral mass screw-rod fixation was created to stabilize the cervical spine after laminectomy. Material properties of the titanium alloy were assigned on the implants. The requirements moments and boundary conditions were applied on simulated implanted bone. Result showed that the bone without implant has a higher flexion and extension angle in comparison to the bone with implant under applied 1Nm moment. The bone without implant has maximum stress distribution at the vertebrae and ligaments. However, the bone with implant has maximum stress distribution at the screws and rods. Overall, the lateral mass screw-rod fixation provides stability to the cervical spine after undergoing laminectomy.

  11. Soft tissue augmentation using Restylane.

    PubMed

    Biesman, Brian

    2004-05-01

    Soft tissue augmentation plays an important role in facial rejuvenation. To accomplish this goal, numerous materials have been used. Hyaluronic acids represent the latest family of products to become available in the United States. This article provides an introduction to the proper use of Restylane, the first hyaluronic acid product to be approved by the United States Food and Drug Administration for soft tissue augmentation.

  12. Screw-Home Movement of the Tibiofemoral Joint during Normal Gait: Three-Dimensional Analysis

    PubMed Central

    Kim, Ha Yong; Yang, Dae Suk; Jeung, Sang Wook; Choi, Han Gyeol; Choy, Won Sik

    2015-01-01

    Background The purpose of this study was to evaluate the screw-home movement at the tibiofemoral joint during normal gait by utilizing the 3-dimensional motion capture technique. Methods Fifteen young males and fifteen young females (total 60 knee joints) who had no history of musculoskeletal disease or a particular gait problem were included in this study. Two more markers were attached to the subject in addition to the Helen-Hayes marker set. Thus, two virtual planes, femoral coronal plane (Pf) and tibial coronal plane (Pt), were created by Skeletal Builder software. This study measured the 3-dimensional knee joint movement in the sagittal, coronal, and transverse planes of these two virtual planes (Pf and Pt) during normal gait. Results With respect to kinematics and kinetics, both males and females showed normal adult gait patterns, and the mean difference in the temporal gait parameters was not statistically significant (p > 0.05). In the transverse plane, the screw-home movement occurred as expected during the pre-swing phase and the late-swing phase at an angle of about 17°. However, the tibia rotated externally with respect to the femur, rather than internally, while the knee joint started to flex during the loading response (paradoxical screw-home movement), and the angle was 6°. Conclusions Paradoxical screw-home movement may be an important mechanism that provides stability to the knee joint during the remaining stance phase. Obtaining the kinematic values of the knee joint during gait can be useful in diagnosing and treating the pathological knee joints. PMID:26330951

  13. Twin Screw Extruders as Continuous Mixers for Thermal Processing: a Technical and Historical Perspective.

    PubMed

    Martin, Charlie

    2016-02-01

    Developed approximately 100 years ago for natural rubber/plastics applications, processes via twin screw extrusion (TSE) now generate some of the most cutting-edge drug delivery systems available. After 25 or so years of usage in pharmaceutical environments, it has become evident why TSE processing offers significant advantages as compared to other manufacturing techniques. The well-characterized nature of the TSE process lends itself to ease of scale-up and process optimization while also affording the benefits of continuous manufacturing. Interestingly, the evolution of twin screw extrusion for pharmaceutical products has followed a similar path as previously trodden by plastics processing pioneers. Almost every plastic has been processed at some stage in the manufacturing train on a twin screw extruder, which is utilized to mix materials together to impart desired properties into a final part. The evolution of processing via TSEs since the early/mid 1900s is recounted for plastics and also for pharmaceuticals from the late 1980s until today. The similarities are apparent. The basic theory and development of continuous mixing via corotating and counterrotating TSEs for plastics and drug is also described. The similarities between plastics and pharmaceutical applications are striking. The superior mixing characteristics inherent with a TSE have allowed this device to dominate other continuous mixers and spurred intensive development efforts and experimentation that spawned highly engineered formulations for the commodity and high-tech plastic products we use every day. Today, twin screw extrusion is a battle hardened, well-proven, manufacturing process that has been validated in 24-h/day industrial settings. The same thing is happening today with new extrusion technologies being applied to advanced drug delivery systems to facilitate commodity, targeted, and alternative delivery systems. It seems that the "extrusion evolution" will continue for wide

  14. 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.

  15. Twin Screw Extruders as Continuous Mixers for Thermal Processing: a Technical and Historical Perspective.

    PubMed

    Martin, Charlie

    2016-02-01

    Developed approximately 100 years ago for natural rubber/plastics applications, processes via twin screw extrusion (TSE) now generate some of the most cutting-edge drug delivery systems available. After 25 or so years of usage in pharmaceutical environments, it has become evident why TSE processing offers significant advantages as compared to other manufacturing techniques. The well-characterized nature of the TSE process lends itself to ease of scale-up and process optimization while also affording the benefits of continuous manufacturing. Interestingly, the evolution of twin screw extrusion for pharmaceutical products has followed a similar path as previously trodden by plastics processing pioneers. Almost every plastic has been processed at some stage in the manufacturing train on a twin screw extruder, which is utilized to mix materials together to impart desired properties into a final part. The evolution of processing via TSEs since the early/mid 1900s is recounted for plastics and also for pharmaceuticals from the late 1980s until today. The similarities are apparent. The basic theory and development of continuous mixing via corotating and counterrotating TSEs for plastics and drug is also described. The similarities between plastics and pharmaceutical applications are striking. The superior mixing characteristics inherent with a TSE have allowed this device to dominate other continuous mixers and spurred intensive development efforts and experimentation that spawned highly engineered formulations for the commodity and high-tech plastic products we use every day. Today, twin screw extrusion is a battle hardened, well-proven, manufacturing process that has been validated in 24-h/day industrial settings. The same thing is happening today with new extrusion technologies being applied to advanced drug delivery systems to facilitate commodity, targeted, and alternative delivery systems. It seems that the "extrusion evolution" will continue for wide

  16. 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

  17. Adhesive-backed terminal board eliminates mounting screws

    NASA Technical Reports Server (NTRS)

    1965-01-01

    Low-profile terminal board is used in dense electronic circuits where mounting and working space is limited. The board has a thin layer of pressure-sensitive adhesive backing which eliminates the need for mounting screws.

  18. Posterior Fixation Techniques in the Subaxial Cervical Spine

    PubMed Central

    Ghori, Ahmer; Makanji, Heeren; Cha, Thomas

    2015-01-01

    This article reviews the historical context, indications, techniques, and complications of four posterior fixation techniques to stabilize the subaxial cervical spine. Specifically, posterior wiring, laminar screw fixation, lateral mass fixation, and pedicle screw fixation are among the common methods of operative fixation of the subaxial cervical spine. While wiring and laminar screw fixation are now rarely used, both lateral mass and pedicle screw fixation are technically challenging and present the risk of significant complications if performed incorrectly. With a sound understanding of anatomy and rigorous preoperative evaluation of bony structures, both lateral mass and pedicle screw fixation provide a safe and reliable method for subaxial cervical spine fixation. PMID:26594602

  19. Bending strength and holding power of tibial locking screws.

    PubMed

    Lin, J; Lin, S J; Chiang, H; Hou, S M

    2001-04-01

    The bending strength and holding power of two types of specially designed tibial locking devices, a both-ends-threaded screw and an unthreaded bolt, were studied and compared with four types of commercially available tibial interlocking screws: Synthes, Howmedica, Richards, and Osteo AG. To test bending strength, the devices were inserted into a high molecular weight polyethylene tube and loaded at their midpoint by a materials testing machine to simulate a three point bending test. Single loading yielding strength and cyclic loading fatigue life were measured. To test holding power, the devices were inserted into tubes made of polyurethane foam, and their tips were loaded axially to measure pushout strength. The devices were tested with two different densities of foam materials and two different sizes of pilot holes. Insertion torque and stripping torque of the screws were measured first. Pushout tests were performed with each screw inserted with a tightness equal to 60% of its stripping torque. Test results showed that the yielding strength and the fatigue life were related closely to the inner diameter of the screws. The stripping torque predicted the pushout strength more reliably than did the insertion torque. All tested devices showed greater holding power in the foam with the higher density and with the smaller pilot holes. The both-ends-threaded screw had the highest pushout strength and a satisfactory fatigue strength. The unthreaded bolt had the highest fatigue strength but only fair holding power. Clinical studies of the use of these two types of locking devices are worthwhile.

  20. Augmentation of the transverse acetabular ligament in canine caudoventral hip luxation.

    PubMed

    Venzin, C; Montavon, P M

    2007-01-01

    Open surgical fixation was performed on four hip joints in three dogs who were suffering from caudoventral hip luxations for which closed reduction had previously failed. Stabilization of the joint was achieved with a ventral coxofemoral approach, which augmented the function of the transverse acetabular ligament using a sling implant through a bone tunnel (n = 1), a sling implant around two pelvic screws (n = 1), or an internal fixator plate (n = 2). Transverse acetabular ligament augmentation resulted in successful joint stabilization in all cases, and should be considered for the surgical reduction of caudoventral hip luxations in dogs. The use of an internal fixator plate, while preserving soft-tissue blood supply and resulting in minimal to no long-term arthritic changes, may provide an optimal outcome. PMID:18038012

  1. Biomechanical Evaluation of Supplemental Percutaneous Lumbo-Sacro-iliac Screws For Spino-pelvic Fixation Following Total Sacrectomy

    PubMed Central

    Le, Vu H.; Heckmann, Nathanael; Jain, Nickul; Wang, Lawrence; Turner, Alexander W. L.; Lee, Thay Q.; Bederman, S. Samuel

    2015-01-01

    Study Design This is a cadaveric biomechanical study evaluating the biomechanical properties of a novel spino-pelvic fixation technique with percutaneous lumbo-sacro-iliac (LSI) screws in an unstable total sacrectomy model. Objective To compare standard posterior dual rod spino-pelvic fixation alone with dual rod fixation supplemented with LSI screw fixation. Summary of Background Data Primary or metastatic tumors of the sacrum requiring a total sacrectomy can result in spino-pelvic instability if inadequate fixation is achieved. Many fixation techniques have been proposed to address this instability. However, to date, an optimal fixation technique has not been established. Methods Ten fresh-frozen cadaveric spino-pelvic specimens were randomized according to bone mineral density (BMD) to either posterior rod fixation (control group) or posterior rod fixation with supplemental LSI screws (LSI group). Following fixation, a total sacrectomy of each specimen was performed. Specimens where then potted and axially loaded in a caudal direction. Stiffness, yield load, energy absorbed at yield load, ultimate load, and energy absorbed at ultimate load were computed. A students t-test was used for statistical analysis with significance set at p<0.05. Results The average age and BMD were not significantly different between the control and LSI groups (age, p=0.255; BMD, p=0.810). After normalizing for BMD, there were no significant differences detected for any of the biomechanical parameters measured between the two fixation techniques: stiffness (p=0.857), yield load (p=0.219), energy at yield load (p=0.293), ultimate load (p=0.407), and energy at ultimate load (p=0.773). However, both fixation techniques were able to withstand physiological loads. Conclusions Our study did not demonstrate any biomechanical advantage for supplemental LSI screw fixation in our axial loading model. However, given the theoretical advantage of this percutaneous technique, further studies are

  2. An Indirect Method to Measure Abutment Screw Preload: A Pilot Study Based on Micro-CT Scanning.

    PubMed

    Rezende, Carlos Eduardo E; Griggs, Jason Alan; Duan, Yuanyuan; Mushashe, Amanda M; Nolasco, Gisele Maria Correr; Borges, Ana Flávia Sanches; Rubo, José Henrique

    2015-01-01

    This study aimed to measure the preload in different implant platform geometries based on micro-CT images. External hexagon (EH) implants and Morse Tapered (MT) implants (n=5) were used for the preload measurement. The abutment screws were scanned in micro-CT to obtain their virtual models, which were used to record their initial length. The abutments were screwed on the implant with a 20 Ncm torque and the set composed by implant, abutment screw and abutment were taken to the micro-CT scanner to obtain virtual slices of the specimens. These slices allowed the measurement of screw lengths after torque application and based on the screw elongation. Preload values were calculated using the Hooke's Law. The preloads of both groups were compared by independent t-test. Removal torque of each specimen was recorded. To evaluate the accuracy of the micro-CT technique, three rods with known lengths were scanned and the length of their virtual model was measured and compared with the original length. One rod was scanned four times to evaluate the measuring method variation. There was no difference between groups for preload (EH = 461.6 N and MT = 477.4 N), but the EH group showed higher removal torque values (13.8 ± 4.7 against 8.2 ± 3.6 N cm for MT group). The micro-CT technique showed a variability of 0.053% and repeatability showed an error of 0.23 to 0.28%. Within the limitations of this study, there was no difference between external hexagon and Morse taper for preload. The method using micro-CT may be considered for preload calculation.

  3. Dorsal Augmentation in Rhinoplasty: A Survey and Review.

    PubMed

    Malone, Melanie; Pearlman, Steven

    2015-06-01

    Understanding the nuanced practices and grafting options of dorsal augmentation will improve outcomes and results in rhinoplasty. To better understand the practices of dorsal augmentation among our colleagues. To review the current literature regarding the indications, safety profiles, and outcomes of different materials used in dorsal augmentation. A PubMed search was performed to capture current articles containing reviews or large series regarding the safety and efficacy of various grafting materials used for dorsal augmentation. Of the many options available, autologous cartilage grafts maintain widespread use for dorsal augmentation and other techniques in rhinoplasty. Homologous cartilage grafts, namely irradiated rib, are a preferred alternative. Irradiated costal cartilage has been shown to have low complication rates and is unique in its abundance of supply, particularly in the revision rhinoplasty. Alloplastic implants, particularly silicone, are prevalent in Asian countries where they are a popular first-line choice. ePTFE has a favorable complication profile in primary rhinoplasty; however, caution is recommended when using ePTFE in revision cases. Porous polyethylene has a higher risk of associated complications than the other alloplastic implants listed, and therefore should be considered thoughtfully. Although cartilage is often the preferred graft for dorsal augmentation, there are many other autogenous, homologous, and alloplastic materials that have been shown to be safe and effective choices when applied in the proper setting. PMID:26126225

  4. Increasing pedicle screw anchoring in the osteoporotic spine by cement injection through the implant. Technical note and report of three cases.

    PubMed

    Fransen, Patrick

    2007-09-01

    Instrumented spinal fusion in patients with osteoporosis is challenging because of the poor bone quality and is complicated by an elevated risk of delayed hardware failure. The author treated two patients presenting with severe osteoporosis, spinal stenosis, and degenerative spondylolisthesis. He performed decompressive laminectomy, posterolateral fusion, and pedicle screw (PS) fixation involving screws with side openings that allow cement to be injected through the implant. The cement injection was conducted under fluoroscopic control without complications. Although this technique needs validation in a larger population of patients, the author believes that the injection of cement through these PSs can be performed safely in carefully selected patients. This technique creates not only a vertebroplasty-like effect that strengthens the vertebral body but also provides the additional stability afforded by the immediate anchoring of the screw, which may allow a shorter-length construct, save mobile segments, and finally reduce the risk of hardware failure. PMID:17877276

  5. Bayesian Alternation during Tactile Augmentation

    PubMed Central

    Goeke, Caspar M.; Planera, Serena; Finger, Holger; König, Peter

    2016-01-01

    A large number of studies suggest that the integration of multisensory signals by humans is well-described by Bayesian principles. However, there are very few reports about cue combination between a native and an augmented sense. In particular, we asked the question whether adult participants are able to integrate an augmented sensory cue with existing native sensory information. Hence for the purpose of this study, we build a tactile augmentation device. Consequently, we compared different hypotheses of how untrained adult participants combine information from a native and an augmented sense. In a two-interval forced choice (2 IFC) task, while subjects were blindfolded and seated on a rotating platform, our sensory augmentation device translated information on whole body yaw rotation to tactile stimulation. Three conditions were realized: tactile stimulation only (augmented condition), rotation only (native condition), and both augmented and native information (bimodal condition). Participants had to choose one out of two consecutive rotations with higher angular rotation. For the analysis, we fitted the participants' responses with a probit model and calculated the just notable difference (JND). Then, we compared several models for predicting bimodal from unimodal responses. An objective Bayesian alternation model yielded a better prediction (χred2 = 1.67) than the Bayesian integration model (χred2 = 4.34). Slightly higher accuracy showed a non-Bayesian winner takes all (WTA) model (χred2 = 1.64), which either used only native or only augmented values per subject for prediction. However, the performance of the Bayesian alternation model could be substantially improved (χred2 = 1.09) utilizing subjective weights obtained by a questionnaire. As a result, the subjective Bayesian alternation model predicted bimodal performance most accurately among all tested models. These results suggest that information from augmented and existing sensory modalities in

  6. Prediction of Deformity Correction by Pedicle Screw Instrumentation in Thoracolumbar Scoliosis Surgery

    NASA Astrophysics Data System (ADS)

    Kiriyama, Yoshimori; Yamazaki, Nobutoshi; Nagura, Takeo; Matsumoto, Morio; Chiba, Kazuhiro; Toyama, Yoshiaki

    In segmental pedicle screw instrumentation, the relationship between the combinations of pedicle screw placements and the degree of deformity correction was investigated with a three-dimensional rigid body and spring model. The virtual thoracolumbar scoliosis (Cobb’s angle of 47 deg.) was corrected using six different combinations of pedicle-screw placements. As a result, better correction in the axial rotation was obtained with the pedicle screws placed at or close to the apical vertebra than with the screws placed close to the end vertebrae, while the correction in the frontal plane was better with the screws close to the end vertebrae than with those close to the apical vertebra. Additionally, two screws placed in the convex side above and below the apical vertebra provided better correction than two screws placed in the concave side. Effective deformity corrections of scoliosis were obtained with the proper combinations of pedicle screw placements.

  7. 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 11 mm 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 11 mm 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.

  8. 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 11 mm 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 11 mm 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

  9. 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.

  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.

  11. Metal artifacts from titanium and steel screws in CT, 1.5T and 3T MR images of the tibial Pilon: a quantitative assessment in 3D

    PubMed Central

    Radzi, Shairah; Cowin, Gary; Robinson, Mark; Pratap, Jit; Volp, Andrew; Schuetz, Michael A.

    2014-01-01

    Radiographs are commonly used to assess articular reduction of the distal tibia (pilon) fractures postoperatively, but may reveal malreductions inaccurately. While magnetic resonance imaging (MRI) and computed tomography (CT) are potential three-dimensional (3D) alternatives they generate metal-related artifacts. This study aims to quantify the artifact size from orthopaedic screws using CT, 1.5T and 3T MRI data. Three screws were inserted into one intact human cadaver ankle specimen proximal to and along the distal articular surface, then CT, 1.5T and 3T MRI scanned. Four types of screws were investigated: titanium alloy (TA), stainless steel (SS) (Ø =3.5 mm), cannulated TA (CTA) and cannulated SS (CSS) (Ø =4.0 mm, Ø empty core =2.6 mm). 3D artifact models were reconstructed using adaptive thresholding. The artifact size was measured by calculating the perpendicular distance from the central screw axis to the boundary of the artifact in four anatomical directions with respect to the distal tibia. The artifact sizes (in the order of TA, SS, CTA and CSS) from CT were 2.0, 2.6, 1.6 and 2.0 mm; from 1.5T MRI they were 3.7, 10.9, 2.9, and 9 mm; and 3T MRI they were 4.4, 15.3, 3.8, and 11.6 mm respectively. Therefore, CT can be used as long as the screws are at a safe distance of about 2 mm from the articular surface. MRI can be used if the screws are at least 3 mm away from the articular surface except for SS and CSS. Artifacts from steel screws were too large thus obstructed the pilon from being visualised in MRI. Significant differences (P<0.05) were found in the size of artifacts between all imaging modalities, screw types and material types, except 1.5T versus 3T MRI for the SS screws (P=0.063). CTA screws near the joint surface can improve postoperative assessment in CT and MRI. MRI presents a favourable non-ionising alternative when using titanium hardware. Since these factors may influence the quality of postoperative assessment, potential improvements in

  12. Metal artifacts from titanium and steel screws in CT, 1.5T and 3T MR images of the tibial Pilon: a quantitative assessment in 3D.

    PubMed

    Radzi, Shairah; Cowin, Gary; Robinson, Mark; Pratap, Jit; Volp, Andrew; Schuetz, Michael A; Schmutz, Beat

    2014-06-01

    Radiographs are commonly used to assess articular reduction of the distal tibia (pilon) fractures postoperatively, but may reveal malreductions inaccurately. While magnetic resonance imaging (MRI) and computed tomography (CT) are potential three-dimensional (3D) alternatives they generate metal-related artifacts. This study aims to quantify the artifact size from orthopaedic screws using CT, 1.5T and 3T MRI data. Three screws were inserted into one intact human cadaver ankle specimen proximal to and along the distal articular surface, then CT, 1.5T and 3T MRI scanned. Four types of screws were investigated: titanium alloy (TA), stainless steel (SS) (Ø =3.5 mm), cannulated TA (CTA) and cannulated SS (CSS) (Ø =4.0 mm, Ø empty core =2.6 mm). 3D artifact models were reconstructed using adaptive thresholding. The artifact size was measured by calculating the perpendicular distance from the central screw axis to the boundary of the artifact in four anatomical directions with respect to the distal tibia. The artifact sizes (in the order of TA, SS, CTA and CSS) from CT were 2.0, 2.6, 1.6 and 2.0 mm; from 1.5T MRI they were 3.7, 10.9, 2.9, and 9 mm; and 3T MRI they were 4.4, 15.3, 3.8, and 11.6 mm respectively. Therefore, CT can be used as long as the screws are at a safe distance of about 2 mm from the articular surface. MRI can be used if the screws are at least 3 mm away from the articular surface except for SS and CSS. Artifacts from steel screws were too large thus obstructed the pilon from being visualised in MRI. Significant differences (P<0.05) were found in the size of artifacts between all imaging modalities, screw types and material types, except 1.5T versus 3T MRI for the SS screws (P=0.063). CTA screws near the joint surface can improve postoperative assessment in CT and MRI. MRI presents a favourable non-ionising alternative when using titanium hardware. Since these factors may influence the quality of postoperative assessment, potential improvements in

  13. Biomechanical evaluation of lumbar pedicle screws in spondylolytic vertebrae: comparison of fixation strength between the traditional trajectory and a cortical bone trajectory.

    PubMed

    Matsukawa, Keitaro; Yato, Yoshiyuki; Imabayashi, Hideaki; Hosogane, Naobumi; Asazuma, Takashi; Chiba, Kazuhiro

    2016-06-01

    OBJECTIVE In the management of isthmic spondylolisthesis, the pedicle screw system is widely accepted surgical strategy; however, there are few reports on the biomechanical behavior of pedicle screws in spondylolytic vertebrae. The purpose of the present study was to compare fixation strength between pedicle screws inserted through the traditional trajectory (TT) and those inserted through a cortical bone trajectory (CBT) in spondylolytic vertebrae by computational simulation. METHODS Finite element models of spondylolytic and normal vertebrae were created from CT scans of 17 patients with adult isthmic spondylolisthesis (mean age 54.6 years, 10 men and 7 women). Each vertebral model was implanted with pedicle screws using TT and CBT techniques and compared between two groups. First, fixation strength of a single screw was evaluated by measuring axial pullout strength. Next, vertebral fixation strength of a paired-screw construct was examined by applying forces simulating flexion, extension, lateral bending, and axial rotation to vertebrae. RESULTS Fixation strengths of TT screws showed a nonsignificant difference between the spondylolytic and the normal vertebrae (p = 0.31-0.81). Fixation strength of CBT screws in the spondylolytic vertebrae demonstrated a statistically significant decrease in pullout strength (21.4%, p < 0.01), flexion (44.1%, p < 0.01), extension (40.9%, p < 0.01), lateral bending (38.3%, p < 0.01), and axial rotation (28.1%, p < 0.05) compared with those in the normal vertebrae. In the spondylolytic vertebrae, no statistically significant difference was observed for pullout strength between TT and CBT (p = 0.90); however, the CBT construct showed lower vertebral fixation strength in flexion (39.0%, p < 0.01), extension (35.6%, p < 0.01), lateral bending (50.7%, p < 0.01), and axial rotation (59.3%, p < 0.01) compared with the TT construct. CONCLUSIONS CBT screws are less optimal for stabilizing the spondylolytic vertebra due to their lower

  14. Transforming Polar Research with Google Glass Augmented Reality (Invited)

    NASA Astrophysics Data System (ADS)

    Ruthkoski, T.

    2013-12-01

    Augmented reality is a new technology with the potential to accelerate the advancement of science, particularly in geophysical research. Augmented reality is defined as a live, direct or indirect, view of a physical, real-world environment whose elements are augmented (or supplemented) by computer-generated sensory input such as sound, video, graphics or GPS data. When paired with advanced computing techniques on cloud resources, augmented reality has the potential to improve data collection techniques, visualizations, as well as in-situ analysis for many areas of research. Google is currently a pioneer of augmented reality technology and has released beta versions of their wearable computing device, Google Glass, to a select number of developers and beta testers. This community of 'Glass Explorers' is the vehicle from which Google shapes the future of their augmented reality device. Example applications of Google Glass in geophysical research range from use as a data gathering interface in harsh climates to an on-site visualization and analysis tool. Early participation in the shaping of the Google Glass device is an opportunity for researchers to tailor this new technology to their specific needs. The purpose of this presentation is to provide geophysical researchers with a hands-on first look at Google Glass and its potential as a scientific tool. Attendees will be given an overview of the technical specifications as well as a live demonstration of the device. Potential applications to geophysical research in polar regions will be the primary focus. The presentation will conclude with an open call to participate, during which attendees may indicate interest in developing projects that integrate Google Glass into their research. Application Mockup: Penguin Counter Google Glass Augmented Reality Device

  15. Transforming Polar Research with Google Glass Augmented Reality (Invited)

    NASA Astrophysics Data System (ADS)

    Ramachandran, R.; McEniry, M.; Maskey, M.

    2011-12-01

    Augmented reality is a new technology with the potential to accelerate the advancement of science, particularly in geophysical research. Augmented reality is defined as a live, direct or indirect, view of a physical, real-world environment whose elements are augmented (or supplemented) by computer-generated sensory input such as sound, video, graphics or GPS data. When paired with advanced computing techniques on cloud resources, augmented reality has the potential to improve data collection techniques, visualizations, as well as in-situ analysis for many areas of research. Google is currently a pioneer of augmented reality technology and has released beta versions of their wearable computing device, Google Glass, to a select number of developers and beta testers. This community of 'Glass Explorers' is the vehicle from which Google shapes the future of their augmented reality device. Example applications of Google Glass in geophysical research range from use as a data gathering interface in harsh climates to an on-site visualization and analysis tool. Early participation in the shaping of the Google Glass device is an opportunity for researchers to tailor this new technology to their specific needs. The purpose of this presentation is to provide geophysical researchers with a hands-on first look at Google Glass and its potential as a scientific tool. Attendees will be given an overview of the technical specifications as well as a live demonstration of the device. Potential applications to geophysical research in polar regions will be the primary focus. The presentation will conclude with an open call to participate, during which attendees may indicate interest in developing projects that integrate Google Glass into their research. Application Mockup: Penguin Counter Google Glass Augmented Reality Device

  16. Augmented Reality Tower Technology Assessment

    NASA Technical Reports Server (NTRS)

    Reisman, Ronald J.; Brown, David M.

    2009-01-01

    Augmented Reality technology may help improve Air Traffic Control Tower efficiency and safety during low-visibility conditions. This paper presents the assessments of five off-duty controllers who shadow-controlled' with an augmented reality prototype in their own facility. Initial studies indicated unanimous agreement that this technology is potentially beneficial, though the prototype used in the study was not adequate for operational use. Some controllers agreed that augmented reality technology improved situational awareness, had potential to benefit clearance, control, and coordination tasks and duties and could be very useful for acquiring aircraft and weather information, particularly aircraft location, heading, and identification. The strongest objections to the prototype used in this study were directed at aircraft registration errors, unacceptable optical transparency, insufficient display performance in sunlight, inadequate representation of the static environment and insufficient symbology.

  17. Biological Augmentation of Rotator Cuff Tendon Repair

    PubMed Central

    Kovacevic, David

    2008-01-01

    A histologically normal insertion site does not regenerate following rotator cuff tendon-to-bone repair, which is likely due to abnormal or insufficient gene expression and/or cell differentiation at the repair site. Techniques to manipulate the biologic events following tendon repair may improve healing. We used a sheep infraspinatus repair model to evaluate the effect of osteoinductive growth factors and BMP-12 on tendon-to-bone healing. Magnetic resonance imaging and histology showed increased formation of new bone and fibrocartilage at the healing tendon attachment site in the treated animals, and biomechanical testing showed improved load-to-failure. Other techniques with potential to augment repair site biology include use of platelets isolated from autologous blood to deliver growth factors to a tendon repair site. Modalities that improve local vascularity, such as pulsed ultrasound, have the potential to augment rotator cuff healing. Important information about the biology of tendon healing can also be gained from studies of substances that inhibit healing, such as nicotine and antiinflammatory medications. Future approaches may include the use of stem cells and transcription factors to induce formation of the native tendon-bone insertion site after rotator cuff repair surgery. PMID:18264850

  18. Augmentation-related brain plasticity.

    PubMed

    Di Pino, Giovanni; Maravita, Angelo; Zollo, Loredana; Guglielmelli, Eugenio; Di Lazzaro, Vincenzo

    2014-01-01

    Today, the anthropomorphism of the tools and the development of neural interfaces require reconsidering the concept of human-tools interaction in the framework of human augmentation. This review analyses the plastic process that the brain undergoes when it comes into contact with augmenting artificial sensors and effectors and, on the other hand, the changes that the use of external augmenting devices produces in the brain. Hitherto, few studies investigated the neural correlates of augmentation, but clues on it can be borrowed from logically-related paradigms: sensorimotor training, cognitive enhancement, cross-modal plasticity, sensorimotor functional substitution, use and embodiment of tools. Augmentation modifies function and structure of a number of areas, i.e., primary sensory cortices shape their receptive fields to become sensitive to novel inputs. Motor areas adapt the neuroprosthesis representation firing-rate to refine kinematics. As for normal motor outputs, the learning process recruits motor and premotor cortices and the acquisition of proficiency decreases attentional recruitment, focuses the activity on sensorimotor areas and increases the basal ganglia drive on the cortex. Augmentation deeply relies on the frontoparietal network. In particular, premotor cortex is involved in learning the control of an external effector and owns the tool motor representation, while the intraparietal sulcus extracts its visual features. In these areas, multisensory integration neurons enlarge their receptive fields to embody supernumerary limbs. For operating an anthropomorphic neuroprosthesis, the mirror system is required to understand the meaning of the action, the cerebellum for the formation of its internal model and the insula for its interoception. In conclusion, anthropomorphic sensorized devices can provide the critical sensory afferences to evolve the exploitation of tools through their embodiment, reshaping the body representation and the sense of the self

  19. Augmentation-related brain plasticity

    PubMed Central

    Di Pino, Giovanni; Maravita, Angelo; Zollo, Loredana; Guglielmelli, Eugenio; Di Lazzaro, Vincenzo

    2014-01-01

    Today, the anthropomorphism of the tools and the development of neural interfaces require reconsidering the concept of human-tools interaction in the framework of human augmentation. This review analyses the plastic process that the brain undergoes when it comes into contact with augmenting artificial sensors and effectors and, on the other hand, the changes that the use of external augmenting devices produces in the brain. Hitherto, few studies investigated the neural correlates of augmentation, but clues on it can be borrowed from logically-related paradigms: sensorimotor training, cognitive enhancement, cross-modal plasticity, sensorimotor functional substitution, use and embodiment of tools. Augmentation modifies function and structure of a number of areas, i.e., primary sensory cortices shape their receptive fields to become sensitive to novel inputs. Motor areas adapt the neuroprosthesis representation firing-rate to refine kinematics. As for normal motor outputs, the learning process recruits motor and premotor cortices and the acquisition of proficiency decreases attentional recruitment, focuses the activity on sensorimotor areas and increases the basal ganglia drive on the cortex. Augmentation deeply relies on the frontoparietal network. In particular, premotor cortex is involved in learning the control of an external effector and owns the tool motor representation, while the intraparietal sulcus extracts its visual features. In these areas, multisensory integration neurons enlarge their receptive fields to embody supernumerary limbs. For operating an anthropomorphic neuroprosthesis, the mirror system is required to understand the meaning of the action, the cerebellum for the formation of its internal model and the insula for its interoception. In conclusion, anthropomorphic sensorized devices can provide the critical sensory afferences to evolve the exploitation of tools through their embodiment, reshaping the body representation and the sense of the self

  20. Augmentation-related brain plasticity.

    PubMed

    Di Pino, Giovanni; Maravita, Angelo; Zollo, Loredana; Guglielmelli, Eugenio; Di Lazzaro, Vincenzo

    2014-01-01

    Today, the anthropomorphism of the tools and the development of neural interfaces require reconsidering the concept of human-tools interaction in the framework of human augmentation. This review analyses the plastic process that the brain undergoes when it comes into contact with augmenting artificial sensors and effectors and, on the other hand, the changes that the use of external augmenting devices produces in the brain. Hitherto, few studies investigated the neural correlates of augmentation, but clues on it can be borrowed from logically-related paradigms: sensorimotor training, cognitive enhancement, cross-modal plasticity, sensorimotor functional substitution, use and embodiment of tools. Augmentation modifies function and structure of a number of areas, i.e., primary sensory cortices shape their receptive fields to become sensitive to novel inputs. Motor areas adapt the neuroprosthesis representation firing-rate to refine kinematics. As for normal motor outputs, the learning process recruits motor and premotor cortices and the acquisition of proficiency decreases attentional recruitment, focuses the activity on sensorimotor areas and increases the basal ganglia drive on the cortex. Augmentation deeply relies on the frontoparietal network. In particular, premotor cortex is involved in learning the control of an external effector and owns the tool motor representation, while the intraparietal sulcus extracts its visual features. In these areas, multisensory integration neurons enlarge their receptive fields to embody supernumerary limbs. For operating an anthropomorphic neuroprosthesis, the mirror system is required to understand the meaning of the action, the cerebellum for the formation of its internal model and the insula for its interoception. In conclusion, anthropomorphic sensorized devices can provide the critical sensory afferences to evolve the exploitation of tools through their embodiment, reshaping the body representation and the sense of the self.

  1. A New Orthodontic Appliance with a Mini Screw for Upper Molar Distalization

    PubMed Central

    2016-01-01

    The aim of this study is to present a new upper molar distalization appliance called Cise distalizer designed as intraoral device supported with orthodontic mini screw for upper permanent molar distalization. The new appliance consists of eight main components. In order to understand the optimum force level, the appliance under static loading is tested by using strain gage measurement techniques. Results show that one of the open coils produces approximately 300 gr distalization force. Cise distalizer can provide totally 600 gr distalization force. This range of force level is enough for distalization of upper first and second molar teeth. PMID:27528796

  2. A New Electromagnetic Navigation System for Pedicle Screws Placement: A Human Cadaver Study at the Lumbar Spine

    PubMed Central

    Hahn, Patrick; Oezdemir, Semih; Komp, Martin; Giannakopoulos, Athanasios; Heikenfeld, Roderich; Kasch, Richard; Merk, Harry; Godolias, Georgios; Ruetten, Sebastian

    2015-01-01

    Introduction Technical developments for improving the safety and accuracy of pedicle screw placement play an increasingly important role in spine surgery. In addition to the standard techniques of free-hand placement and fluoroscopic navigation, the rate of complications is reduced by 3D fluoroscopy, cone-beam CT, intraoperative CT/MRI, and various other navigation techniques. Another important aspect that should be emphasized is the reduction of intraoperative radiation exposure for personnel and patient. The aim of this study was to investigate the accuracy of a new navigation system for the spine based on an electromagnetic field. Material and Method Twenty pedicle screws were placed in the lumbar spine of human cadavers using EMF navigation. Navigation was based on data from a preoperative thin-slice CT scan. The cadavers were positioned on a special field generator and the system was matched using a patient tracker on the spinous process. Navigation was conducted using especially developed instruments that can be tracked in the electromagnetic field. Another thin-slice CT scan was made postoperatively to assess the result. The evaluation included the position of the screws in the direction of trajectory and any injury to the surrounding cortical bone. The results were classified in 5 groups: grade 1: ideal screw position in the center of the pedicle with no cortical bone injury; grade 2: acceptable screw position, cortical bone injury with cortical penetration ≤ 2 mm; grade 3: cortical bone injury with cortical penetration 2,1-4 mm, grad 4: cortical bone injury with cortical penetration 4,1-6 mm, grade 5: cortical bone injury with cortical penetration >6 mm. Results The initial evaluation of the system showed good accuracy for the lumbar spine (65% grade 1, 20% grade 2, 15% grade 3, 0% grade 4, 0% grade 5). A comparison of the initial results with other navigation techniques in literature (CT navigation, 2D fluoroscopic navigation) shows that the accuracy of

  3. Superconducting augmented rail gun (SARG)

    SciTech Connect

    Homan, C.G.; Cummings, C.E.; Fowler, C.M.

    1986-11-01

    Superconducting augmentation consists of a superconducting coil operating in the persistent mode closely coupled magnetically with a normally conducting rail gun. A theoretical investigation of the effect of this system on a rail gun has shown that two benefits occur. Projectile velocities and launch efficiencies increase significantly depending on the magnetic coupling between the rail and augmentation circuits. Previous work evaluated an idealized system by neglecting energy dissipation effects. In this paper, the authors extend the analysis to include the neglected terms and show improved actual launch efficiencies for the SARG configuration. In this paper, the authors discuss details of projectile design in depth and present preliminary results of rail gun performance.

  4. Evaluation of the Effect of Fixation Angle between Polyaxial Pedicle Screw Head and Rod on the Failure of Screw-Rod Connection.

    PubMed

    Çetin, Engin; Özkaya, Mustafa; Güler, Ümit Özgür; Acaroğlu, Emre; Demir, Teyfik

    2015-01-01

    Introduction. Polyaxial screws had been only tested according to the ASTM standards (when they were perpendicularly positioned to the rod). In this study, effects of the pedicle screws angled fixation to the rod on the mechanical properties of fixation were investigated. Materials and Method. 30 vertically fixed screws and 30 screws fixed with angle were used in the study. Screws were used in three different diameters which were 6.5 mm, 7.0 mm, and 7.5 mm, in equal numbers. Axial pull-out and flexion moment tests were performed. Test results compared with each other using appropriate statistical methods. Results. In pull-out test, vertically fixed screws, in 6.5 mm and 7.0 mm diameter, had significantly higher maximum load values than angled fixed screws with the same diameters (P < 0.01). Additionally, vertically fixed screws, in all diameters, had significantly greater stiffness according to corresponding size fixed with angle (P < 0.005). Conclusion. Fixing the pedicle screw to the rod with angle significantly decreased the pull-out stiffness in all diameters. Similarly, pedicle screw instrumentation fixed with angle decreased the minimum sagittal angle between the rod and the screw in all diameters for flexion moment test but the differences were not significant.

  5. Evaluation of the Effect of Fixation Angle between Polyaxial Pedicle Screw Head and Rod on the Failure of Screw-Rod Connection

    PubMed Central

    Çetin, Engin; Özkaya, Mustafa; Güler, Ümit Özgür; Acaroğlu, Emre

    2015-01-01

    Introduction. Polyaxial screws had been only tested according to the ASTM standards (when they were perpendicularly positioned to the rod). In this study, effects of the pedicle screws angled fixation to the rod on the mechanical properties of fixation were investigated. Materials and Method. 30 vertically fixed screws and 30 screws fixed with angle were used in the study. Screws were used in three different diameters which were 6.5 mm, 7.0 mm, and 7.5 mm, in equal numbers. Axial pull-out and flexion moment tests were performed. Test results compared with each other using appropriate statistical methods. Results. In pull-out test, vertically fixed screws, in 6.5 mm and 7.0 mm diameter, had significantly higher maximum load values than angled fixed screws with the same diameters (P < 0.01). Additionally, vertically fixed screws, in all diameters, had significantly greater stiffness according to corresponding size fixed with angle (P < 0.005). Conclusion. Fixing the pedicle screw to the rod with angle significantly decreased the pull-out stiffness in all diameters. Similarly, pedicle screw instrumentation fixed with angle decreased the minimum sagittal angle between the rod and the screw in all diameters for flexion moment test but the differences were not significant. PMID:27019578

  6. Bibliography of US patents on augmentation of convective heat and mass transfer-II

    SciTech Connect

    Webb, R.L.; Bergles, A.E.; Junkhan, G.H.

    1983-12-01

    Patents are an important source of information on the potential commercialization of augmented heat transfer technology. This report presents a bibliography of US patents pertinent to that technology. The total number of patents cited is 454. They are presented in three separate lists: by patent number, alphabetically by first inventor, and by augmentation technique (with secondary arrangement according to mode of heat transfer).

  7. Aortic homograft for pulmonary artery augmentation in single lung transplantation.

    PubMed

    Rueda, Pablo; Morales, Jose; Guzman, Enrique; Tellez, Jose L; Niebla, Benito A; Avalos, Alejandro; Patiño, Hilda

    2005-06-01

    We present a case of unilateral lung transplantation in which a segment of the donor's descending aorta was used as a homograft for pulmonary artery augmentation in the donor lung. This technique can be used when the donor's lung artery has been cut at the base of the hilum during the harvesting procedure.

  8. Transaxillary endoscopic silicone gel breast augmentation.

    PubMed

    Strock, Louis L

    2010-09-01

    Following the return of silicone gel breast implants to the US market in 2006, augmentation with these implants has become increasingly popular. Surgeons have an array of refined techniques from which to choose when performing these procedures, many of which offer the advantage of reduced or less-obvious postoperative scarring. For obvious reasons, many patients are requesting placement of the implants through incisions that are removed from the breast area (and thereby hidden). The challenge of these approaches is to provide a level of technical control that matches what is afforded with the traditional inframammary approach. The addition of endoscopic assistance has provided a level of tissue visualization and technical control not previously possible with the transaxillary approach, with results that rival those of an inframammary procedure. In this article, the author presents his current operative technique, which has allowed for the routine placement of silicone gel breast implants through a transaxillary incision using endoscopic assistance.

  9. Intermaxillary fixation screws versus Erich arch bars in mandibular fractures: A comparative study and review of literature

    PubMed Central

    Qureshi, Ahtesham Ahmad; Reddy, Umesh K.; Warad, N. M.; Badal, Sheeraz; Jamadar, Amjad Ali; Qurishi, Nilofar

    2016-01-01

    Objective: Various techniques have been employed from time to time to achieve maxillomamdibular fixation. Although arch bars provide an effective and versatile means of maxillomandibular fixation, their use is not without shortcomings. However the introduction of intermaxillary fixation screws (IMF) has eliminated many of these issues of arch bars. The aim of the present study was to compare the advantages and disadvantages of intermaxillary fixation screws over the Erich arch bars in mandibular fractures. Materials and Methods: Sixty dentulous patients who reported to Department of Oral and Maxillofacial Surgery, Al-Ameen Dental College and Hospital, Bijapur with mandibular fractures and required intermaxillary fixation as a part of treatment plan followd by open reduction and internal fixation under GA were selected and randomly divided into 2 groups of 30 patients each that is Group A and Group B. Group A included patients who received intermaxillary fixation with Erich arch bars. Group B includes patients who received intermaxillary fixation with IMF Screws. The parameters compared in both the groups included, surgical time taken, gloves perforation, post-operative occlusion, IMF stability, oral hygiene, patient acceptance and comfort and non-vitality characteristics. Results: The average surgical time taken and gloves perforations were more in Group A,the patient acceptance and oral hygiene was better in Group B, there was not much statistically significant difference in postoperative occlusion and IMF stability in both groups. Accidental root perforation was the only limitation of IMF screws. Conclusion: Intermaxillary fixation with IMF screws is more efficacious compared to Erich arch bars in the treatment of mandibular fractures. PMID:27563602

  10. 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.

  11. Distal Locking Screws for Intramedullary Nailing of Tibial Fractures.

    PubMed

    Agathangelidis, Filon; Petsatodis, Georgios; Kirkos, John; Papadopoulos, Pericles; Karataglis, Dimitrios; Christodoulou, Anastasios

    2016-01-01

    Recently introduced tibial intramedullary nails allow a number of distal screws to be used to reduce the incidence of malalignment and loss of fixation of distal metaphyseal fractures. However, the number of screws and the type of screw configuration to be used remains obscure. This biomechanical study was performed to address this question. Thirty-six Expert tibial nails (Synthes, Oberdorf, Switzerland) were introduced in composite bone models. The models were divided into 4 groups with different distal locking configurations ranging from 2 to 4 screws. A 7-mm gap osteotomy was performed 72 mm from the tibial plafond to simulate a 42-C3 unstable distal tibial fracture. Each group was divided in 3 subgroups and underwent nondestructive biomechanical testing in axial compression, coronal bending, and axial torsion. The passive construct stiffness was measured and statistically analyzed with one-way analysis of variance. Although some differences were noted between the stiffness of each group, these were not statistically significant in compression (P=.105), bending (P=.801), external rotation (P=.246), and internal rotation (P=.370). This in vitro study showed that, when using the Expert tibial nail for unstable distal tibial fractures, the classic configuration of 2 parallel distal screws could provide the necessary stability under partial weight-bearing conditions. PMID:26840700

  12. Endovascular aortic injury repair after thoracic pedicle screw placement.

    PubMed

    Pesenti, S; Bartoli, M A; Blondel, B; Peltier, E; Adetchessi, T; Fuentes, S

    2014-09-01

    Our objective was to describe the management and prevention of thoracic aortic injuries caused by a malposition of pedicle screws in corrective surgery of major spine deformities. Positioning pedicle screws in thoracic vertebras by posterior approach exposes to the risk of injury of the elements placed ahead of the thoracic spine, as the descending thoracic aorta. This complication can result in a cataclysmic bleeding, needing urgent vascular care, but it can also be totally asymptomatic, resulting in the long run in a pseudoaneurysm, justifying the systematic removal of the hardware. We report the case of a 76-year-old woman who underwent spinal correction surgery for thoraco-lumbar degenerative kypho-scoliosis. Immediately after the surgery, a thoracic aortic injury caused by the left T7 pedicle screw was diagnosed. The patient underwent a two-step surgery. The first step was realized by vascular surgeons and aimed to secure the aortic wall by short endovascular aortic grafting. During the second step, spine surgeons removed the responsible screw by posterior approach. The patient was discharged in a rehabilitation center 7 days after the second surgery. When such a complication occurs, a co-management by vascular and spine surgeons is necessary to avoid major complications. Endovascular management of this kind of vascular injuries permits to avoid an open surgery that have a great rate of morbi-mortality in frail patients. Nowadays, technologies exist to prevent this kind of event and may improve the security when positioning pedicle screws. PMID:25023930

  13. A Biomechanical Comparison of Intralaminar C7 Screw Constructs with and without Offset Connector Used for C6-7 Cervical Spine Immobilization : A Finite Element Study

    PubMed Central

    Qasim, Muhammad; Natarajan, Raghu N.; An, Howard S.

    2013-01-01

    Objective The offset connector can allow medial and lateral variability and facilitate intralaminar screw incorporation into the construct. The aim of this study was to compare the biomechanical characteristics of C7 intralaminar screw constructs with and without offset connector using a three dimensional finite element model of a C6-7 cervical spine segment. Methods Finite element models representing C7 intralaminar screw constructs with and without the offset connector were developed. Range of motion (ROM) and maximum von Mises stresses in the vertebra for the two techniques were compared under pure moments in flexion, extension, lateral bending and axial rotation. Results ROM for intralaminar screw construct with offset connector was less than the construct without the offset connector in the three principal directions. The maximum von Misses stress was observed in the C7 vertebra around the pedicle in both constructs. Maximum von Mises stress in the construct without offset connector was found to be 12-30% higher than the corresponding stresses in the construct with offset connector in the three principal directions. Conclusion This study demonstrated that the intralaminar screw fixation with offset connector is better than the construct without offset connector in terms of biomechanical stability. Construct with the offset connector reduces the ROM of C6-7 segment more significantly compared to the construct without the offset connector and causes lower stresses around the C7 pedicle-vertebral body complex. PMID:24003366

  14. Results of cement augmentation and curettage in aneurysmal bone cyst of spine

    PubMed Central

    Basu, Saumyajit; Patel, Dharmesh R; Dhakal, Gaurav; Sarangi, T

    2016-01-01

    Aneurysmal bone cyst (ABC) is a vascular tumor of the spine. Management of spinal ABC still remains controversial because of its location, vascular nature and incidence of recurrence. In this manuscript, we hereby describe two cases of ABC spine treated by curettage, vertebral cement augmentation for control of bleeding and internal stabilization with two years followup. To the best of our knowledge, this is the first case report in the literature describing the role of cement augmentation in spinal ABC in controlling vascular bleeding in curettage of ABC of spine. Case 1: A 22 year old male patient presented with chronic back pain. On radiological investigation, there were multiple, osteolytic septite lesions at L3 vertebral body without neural compression or instability. Percutaneous transpedicular biopsy of L3 from involved pedicle was done. This was followed by cement augmentation through the uninvolved pedicle. Next, transpedicular complete curettage was done through involved pedicle. Case 2: A 15-year-old female presented with nonradiating back pain and progressive myelopathy. On radiological investigation, there was an osteolytic lesion at D9. At surgery, decompression, pedicle screw-rod fixation and posterolateral fusion from D7 to D11 was done. At D9 level, through normal pedicle cement augmentation was added to provide anterior column support and to control the expected bleeding following curettage. Transpedicular complete curettage was done through the involved pedicle with controlled bleeding at the surgical field. Cement augmentation was providing controlled bleeding at surgical field during curettage, internal stabilization and control of pain. On 2 years followup, pain was relieved and there was a stable spinal segment with well filled cement without any sign of recurrence in computed tomography scan. In selected cases of spinal ABC with single vertebral, single pedicle involvement; cement augmentation of vertebra through normal pedicle has an

  15. Results of cement augmentation and curettage in aneurysmal bone cyst of spine.

    PubMed

    Basu, Saumyajit; Patel, Dharmesh R; Dhakal, Gaurav; Sarangi, T

    2016-01-01

    Aneurysmal bone cyst (ABC) is a vascular tumor of the spine. Management of spinal ABC still remains controversial because of its location, vascular nature and incidence of recurrence. In this manuscript, we hereby describe two cases of ABC spine treated by curettage, vertebral cement augmentation for control of bleeding and internal stabilization with two years followup. To the best of our knowledge, this is the first case report in the literature describing the role of cement augmentation in spinal ABC in controlling vascular bleeding in curettage of ABC of spine. Case 1: A 22 year old male patient presented with chronic back pain. On radiological investigation, there were multiple, osteolytic septite lesions at L3 vertebral body without neural compression or instability. Percutaneous transpedicular biopsy of L3 from involved pedicle was done. This was followed by cement augmentation through the uninvolved pedicle. Next, transpedicular complete curettage was done through involved pedicle. Case 2: A 15-year-old female presented with nonradiating back pain and progressive myelopathy. On radiological investigation, there was an osteolytic lesion at D9. At surgery, decompression, pedicle screw-rod fixation and posterolateral fusion from D7 to D11 was done. At D9 level, through normal pedicle cement augmentation was added to provide anterior column support and to control the expected bleeding following curettage. Transpedicular complete curettage was done through the involved pedicle with controlled bleeding at the surgical field. Cement augmentation was providing controlled bleeding at surgical field during curettage, internal stabilization and control of pain. On 2 years followup, pain was relieved and there was a stable spinal segment with well filled cement without any sign of recurrence in computed tomography scan. In selected cases of spinal ABC with single vertebral, single pedicle involvement; cement augmentation of vertebra through normal pedicle has an

  16. Effects of lag screw design and lubrication on sliding in trochanteric nails.

    PubMed

    Kummer, Frederick J

    2010-01-01

    This study compared the sliding characteristics of three lag screw designs used with trochanteric nails and determined the effects of lubrication on sliding. They were tested by an established method to measure initiation and ease of lag screw sliding. These tests were then repeated with calf serum lubrication. There were significant differences (p < 0.05) between the loads required to initiate lag screw sliding that appeared to be related to design. Screw sliding was similar for all three designs; however, the presence of lag screw locking slots affected sliding in that region. Lubrication did not affect either parameter. Lag screw design aspects, such as diameter and, particularly, surface finish, affect sliding. Due to the small contact area between the lag screw and nail creating high interface stresses, lubrication had no effect on lag screw sliding.

  17. 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.

  18. Optically driven Archimedes micro-screws for micropump application.

    PubMed

    Lin, Chih-Lang; Vitrant, Guy; Bouriau, Michel; Casalegno, Roger; Baldeck, Patrice L

    2011-04-25

    Archimedes micro-screws have been fabricated by three-dimensional two-photon polymerization using a Nd:YAG Q-switched microchip laser at 532nm. Due to their small sizes they can be easily manipulated, and made to rotate using low power optical tweezers. Rotation rates up to 40 Hz are obtained with a laser power of 200 mW, i.e. 0.2 Hz/mW. A photo-driven micropump action in a microfluidic channel is demonstrated with a non-optimized flow rate of 6 pL/min. The optofluidic properties of such type of Archimedes micro-screws are quantitatively described by the conservation of momentum that occurs when the laser photons are reflected on the helical micro-screw surface.

  19. C2 Pedicle Screw Placement: A Novel Teaching Aid

    PubMed Central

    Moisi, Marc; Chapman, Jens; Oskouian, Rod J; Tubbs, R. Shane

    2016-01-01

    The C2 pedicle screw is more biomechanically stable and provides patients with increased postoperative range of motion in comparison to other methods of C2 fixation. However, as a result of the proximity of the C2 pedicle to the transverse foramen, there is a considerable risk of intraoperative morbidity due to vertebral artery injury laterally or vertebral canal breach medially. Other than the use of cadavers for the demonstration and practice of C2 pedicle screw placement, there are currently few other readily available teaching aids for the training of residents and fellows. Herein, we describe a simple and cost effective modality for the demonstration, evaluation, and practice of C2 pedicle screw placement in a laboratory setting. PMID:27433409

  20. CMM probe compensation methods for measuring complex screw surface

    NASA Astrophysics Data System (ADS)

    Zhao, Qiancheng; Yang, Tianlong; Yin, Xiyun

    2013-01-01

    At present, probe compensation is the key problem in measuring geometric parameters of complex screw surface with CMM due to its complicated 3D shape, aiming at this problem, some new measurement methods are proposed based on geometric feature models, expressing the screw surface and its offset surface separately. Supposing the parameter lead of a screw surface is known, it's realized by scanning one single profile to complete probe compensation and calculate out all parameters, and the probe compensation is done by two improved methods, named as modified cross product and offset surface virtual measurement respectively, the theory and detailed process of which are discussed in this paper. After performing systematic experiments of profile scan, probe compensation and error evaluation, results show that the new measurement methods provide higher precision, stability and realizability.

  1. Accuracy of Percutaneous Lumbosacral Pedicle Screw Placement Using the Oblique Fluoroscopic View Based on Computed Tomography Evaluations

    PubMed Central

    Sato, Koji; Kanemura, Tokumi; Iwase, Toshiki; Togawa, Daisuke; Matsuyama, Yukihiro

    2016-01-01

    Study Design Retrospective. Purpose This study aims to investigate the accuracy of the oblique fluoroscopic view, based on preoperative computed tomography (CT) images for accurate placement of lumbosacral percutaneous pedicle screws (PPS). Overview of Literature Although PPS misplacement has been reported as one of the main complications in minimally invasive spine surgery, there is no comparative data on the misplacement rate among different fluoroscopic techniques, or comparing such techniques with open procedures. Methods We retrospectively selected 230 consecutive patients who underwent posterior spinal fusion with a pedicle screw construct for degenerative lumbar disease, and divided them into 3 groups, those who had undergone: minimally invasive percutaneous procedure using biplane (lateral and anterior-posterior views using a single C-arm) fluoroscope views (group M-1), minimally invasive percutaneous procedure using the oblique fluoroscopic view based on preoperative CT (group M-2), and conventional open procedure using a lateral fluoroscopic view (group O: controls). The relative position of the screw to the pedicle was graded for the pedicle breach as no breach, <2 mm, 2–4 mm, or >4 mm. Inaccuracy was calculated and assessed according to the spinal level, direction and neurological deficit. Inter-group radiation exposure was estimated using fluoroscopy time. Results Inaccuracy involved an incline toward L5, causing medial or lateral perforation of pedicles in group M-1, but it was distributed relatively equally throughout multiple levels in groups M-2 and controls. The mean fluoroscopy time/case ranged from 1.6 to 3.9 minutes. Conclusions Minimally invasive lumbosacral PPS placement using the conventional fluoroscopic technique carries an increased risk of inaccurate screw placement and resultant neurological deficits, compared with that of the open procedure. Inaccuracy tended to be distributed between medial and lateral perforations of the L5 pedicle

  2. Vertical Alveolar Ridge Augmentation by Distraction Osteogenesis

    PubMed Central

    Kumar, N. Nanda; Ravindran, C.

    2015-01-01

    Introduction Compromised alveolar ridge in vertical and horizontal dimension is a common finding in patients visiting practitioners for dental prosthesis. Various treatment modalities are available for correction of deficient ridges among which alveolar distraction osteogenesis is one. Aim To study the efficacy of alveolar distraction osteogenesis in augmentation of alveolar ridges deficient in vertical dimension. Materials and Methods Ten patients aged 16 to 46 years with deficient alveolar ridge underwent ridge augmentation in 11 alveolar segments using the distraction osteogenesis method. For each patient a custom made distraction device was fabricated. The device was indigenously manufactured with SS-316 (ISO 3506). Results The vertical bone gain reached more than 10mm without the use of bone transplantation. Certain complications like incorrect vector of distraction, paresthesia, pain and loss of transport segment were encountered during the course of the study. Conclusion Alveolar vertical distraction osteogenesis is a reliable and predictable technique for both hard and soft tissue genesis. Implant placement is feasible with primary stability in neogenerated bone at the level of the distracted areas. PMID:26816991

  3. Soft tissue augmentation with ArteFill.

    PubMed

    Hilinski, John M; Cohen, Steven R

    2009-05-01

    ArteFill is a novel, third-generation polymethylmethacrylate (PMMA) injectable filler with unique properties. When compared with predecessor materials, ArteFill demonstrates improved biocompatibility as a result of more uniform PMMA microsphere size and shape. This translates into less adverse events after placement. ArteFill can provide a permanent volume enhancement by stimulation of fibroblasts that encapsulate nonabsorbable microspheres with collagen deposition. Currently, ArteFill is FDA approved for permanent augmentation of moderately deep nasolabial folds. It is also commonly used off-label for augmentation of other skin creases and regional areas of volume deficiency, such as the tear trough-malar and marionette line-prejowl sulcus regions. The key to success with ArteFill is a conservative approach with avoidance of overcorrection. Proper technique includes deep dermal to subcutaneous placement with full correction achieved gradually over several treatments. Complications are mostly limited to nodule formation, which is easily managed in most cases with conservative intervention.

  4. Prospects for Optogenetic Augmentation of Brain Function

    PubMed Central

    Jarvis, Sarah; Schultz, Simon R.

    2015-01-01

    The ability to optically control neural activity opens up possibilities for the restoration of normal function following neurological disorders. The temporal precision, spatial resolution, and neuronal specificity that optogenetics offers is unequalled by other available methods, so will it be suitable for not only restoring but also extending brain function? As the first demonstrations of optically “implanted” novel memories emerge, we examine the suitability of optogenetics as a technique for extending neural function. While optogenetics is an effective tool for altering neural activity, the largest impediment for optogenetics in neural augmentation is our systems level understanding of brain function. Furthermore, a number of clinical limitations currently remain as substantial hurdles for the applications proposed. While neurotechnologies for treating brain disorders and interfacing with prosthetics have advanced rapidly in the past few years, partially addressing some of these critical problems, optogenetics is not yet suitable for use in humans. Instead we conclude that for the immediate future, optogenetics is the neurological equivalent of the 3D printer: its flexibility providing an ideal tool for testing and prototyping solutions for treating brain disorders and augmenting brain function. PMID:26635547

  5. Biomechanical and Histological Evaluation of Roughened Surface Titanium Screws Fabricated by Electron Beam Melting

    PubMed Central

    Yang, Jun; Cai, Hong; Lv, Jia; Zhang, Ke; Leng, Huijie; Wang, Zhiguo; Liu, Zhongjun

    2014-01-01

    Background Various fabrication methods are used to improve the stability and osseointegration of screws within the host bone. The aim of this study was to investigate whether roughened surface titanium screws fabricated by electron beam melting can provide better stability and osseointegration as compared with smooth titanium screws in sheep cervical vertebrae. Methods Roughened surface titanium screws, fabricated by electron beam melting, and conventional smooth surface titanium screws were implanted into sheep for 6 or 12 weeks (groups A and B, respectively). Bone ingrowth and implant stability were assessed with three-dimensional imaging and reconstruction, as well as histological and biomechanical tests. Results No screws in either group showed signs of loosening. Fibrous tissue formation could be seen around the screws at 6 weeks, which was replaced with bone at 12 weeks. Bone volume/total volume, bone surface area/bone volume, and the trabecular number were significantly higher for a define region of interest surrounding the roughened screws than that surrounding the smooth screws at 12 weeks. Indeed, for roughened screws, trabecular number was significantly higher at 12 weeks than at 6 weeks. On mechanical testing, the maximum pullout strength was significantly higher at 12 weeks than at 6 weeks, as expected; however, no significant differences were found between smooth and roughened screws at either time point. The maximum torque to extract the roughened screws was higher than that required for the smooth screws. Conclusions Electron beam melting is a simple and effective method for producing a roughened surface on titanium screws. After 12 weeks, roughened titanium screws demonstrated a high degree of osseointegration and increased torsional resistance to extraction over smooth titanium screws. PMID:24788866

  6. 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

  7. Angled Screw Channel: An Alternative to Cemented Single-Implant Restorations--Three Clinical Examples.

    PubMed

    Gjelvold, Björn; Sohrabi, Majid Melvin; Chrcanovic, Bruno Ramos

    2016-01-01

    This article presents three cases of single labially tilted implants restored with screw-retained single crowns. Individualized abutments with an angled screw channel were used to avoid an unesthetic vestibular access channel. This individualized abutment allows the dentist and dental technician to use the screw-retained restorations where a cemented reconstruction would otherwise have been needed. PMID:26757334

  8. Fracture resistance of abutment screws made of titanium, polyetheretherketone, and carbon fiber-reinforced polyetheretherketone.

    PubMed

    Neumann, Eduardo Aloisio Fleck; Villar, Cristina Cunha; França, Fabiana Mantovani Gomes

    2014-01-01

    Fractured abutment screws may be replaced; however, sometimes, the screw cannot be removed and the entire implant must be surgically removed and replaced. The aim of this study was to compare the fracture resistance of abutment retention screws made of titanium, polyetheretherketone (PEEK) and 30% carbon fiber-reinforced PEEK, using an external hexagonal implant/UCLA-type abutment interface assembly. UCLA-type abutments were fixed to implants using titanium screws (Group 1), polyetheretherketone (PEEK) screws (Group 2), and 30% carbon fiber-reinforced PEEK screws (Group 3). The assemblies were placed on a stainless steel holding apparatus to allow for loading at 45o off-axis, in a universal testing machine. A 200 N load (static load) was applied at the central point of the abutment extremity, at a crosshead speed of 5 mm/minute, until failure. Data was analyzed by ANOVA and Tukey's range test. The titanium screws had higher fracture resistance, compared with PEEK and 30% carbon fiber-reinforced PEEK screws (p < 0.05). In contrast, no statistically significant difference was observed between the fracture resistance of the PEEK and the 30% carbon fiber-reinforced PEEK screws (p> 0.05). Finally, visual analysis of the fractions revealed that 100% of them occurred at the neck of the abutment screw, suggesting that this is the weakest point of this unit. PEEK abutment screws have lower fracture resistance, in comparison with titanium abutment screws. PMID:25098826

  9. [How to choose and deliver orthodontic mini-screws: important notions].

    PubMed

    Steve, Marc; Racy, Emmanuel; Kerbrat, Jean-Baptiste

    2015-12-01

    Orthodontic mini-screws are developing more and more because they make orthodontics easier and broaden its applications. This exponential development has arrived at a well defined mini-screw and a codified installation procedure. The aim of this article is to provide the conceptual elements of mini-screws in order to allow their safe use in orthodontic offices. PMID:26655416

  10. Posterior cervical spine arthrodesis with laminar screws: a report of two cases.

    PubMed

    Nakanishi, Kazuo; Tanaka, Masato; Sugimoto, Yoshihisa; Ozaki, Toshifumi

    2007-04-01

    We performed fixation using laminar screws in 2 patients in whom lateral mass screws, pedicle screws or transarticular screws could not be inserted. One was a 56-year-old woman who had anterior atlantoaxial subluxation (AAS). When a guide wire was inserted using an imaging guide, the hole bled massively. We thought the re-insertion of a guide wire or screw would thus increase the risk of vascular injury, so we used laminar screws. The other case was an 18-year-old man who had a hangman fracture. Preoperative magnetic resonance angiography showed occlusion of the left vertebral artery. A laminar screw was inserted into the patent side (i.e., the right side of C2). Cervical pedicle screws are the most biomechanically stable screws. However, their use carries a high risk of neurovascular complications during screw insertion, because the cervical pedicle is small and is adjacent laterally to the vertebral artery, medially to the spinal cord, and vertically to the nerve roots. Lateral mass screws are also reported to involve a risk of neurovascular injuries. The laminar screw method was thus thought to be useful, since arterial injuries could thus be avoided and it could also be used as a salvage modality for the previous misinsertion. PMID:17471313

  11. [Augmented anterior cruciate ligament replacement with the Kennedy-LAD (ligament augmentation device)--long term outcome].

    PubMed

    Riel, K A

    1998-01-01

    The ligament augmentation device (Kennedy-LAD) is used to protect tendon grafts during the posttransplantation decrease in strength in anterior cruciate ligament (acl) reconstructions. The augmentation with the LAD is based on the concept of load sharing. Since 1983 we used the LAD in acl-reconstructions in 856 patients. In 63 cases we had to treat complications like infection (8), recurrent effusions (21), arthrofibrosis (34). The overall results are good with respect to stability, regain of strength and sports activity. In 73 cases resurgery was necessary because of synovitis (7), LAD-rupture due to re-injury (9), fatigue-rupture of the LAD (22), meniscal tears (35), 2.7 +/- 2.3 years (range: 2 months to 10 years) after LAD implantation. Modern techniques in acl reconstruction lead to comparable results without synthetic augmentation. Therefore, we now recommend the use of a LAD only in cases of repeated acl replacement with week tendon grafts, to avoid an allograft.

  12. Real-Time Estimation of Ball-Screw Thermal Elongation Based upon Temperature Distribution of Ball-Screw

    NASA Astrophysics Data System (ADS)

    Kodera, Takehiko; Yokoyama, Kazuhiro; Miyaguchi, Kazuo; Nagai, Yutaka; Suzuki, Takamasa; Masuda, Masami; Yazawa, Takanori

    The optical telemeter system has been developed, which converts the temperature of rotating spindle to the digital data and carries the digital data from LED on the rotating side toward PD on the stationary side by the optical data transmission. Based upon the temperature distribution of hollow ball-screw obtained by the telemeter system, the thermal elongation of the ball-screw is estimated as the one-dimensional thermal elongation. Estimation accuracy, which is the difference between the estimated thermal elongation and the measured thermal elongation, is -3.1∼+3.2µ m for the thermal elongation of 50-60µ m over the length of 935.5mm of the ball-screw.

  13. Complications of soft tissue augmentation.

    PubMed

    Hirsch, Ranella J; Stier, Meghan

    2008-09-01

    The wide variety of dermal fillers presently available has revolutionized treatment options for patients seeking a refreshed appearance. Soft tissue fillers include both bovine and human collagens, the hyaluronans, calcium hydroxyapatite, poly-L-lactic acid, and synthetic polymers. However, soft tissue augmentation is never risk-free, and as these procedures have increased in prevalence, complications have been more frequently reported. This article describes a range of complications resulting from dermal filler injections, reviews key case studies, and discusses possible treatment options for adverse effects. While biodegradable fillers offer the least risk for the patient, location, allergic reactions, granulomas, necrosis, and infection are all serious complications that must be considered before performing soft tissue augmentation with any approved dermal filler.

  14. Effective Augmentation of Complex Networks

    PubMed Central

    Wang, Jinjian; Yu, Xinghuo; Stone, Lewi

    2016-01-01

    Networks science plays an enormous role in many aspects of modern society from distributing electrical power across nations to spreading information and social networking amongst global populations. While modern networks constantly change in size, few studies have sought methods for the difficult task of optimising this growth. Here we study theoretical requirements for augmenting networks by adding source or sink nodes, without requiring additional driver-nodes to accommodate the change i.e., conserving structural controllability. Our “effective augmentation” algorithm takes advantage of clusters intrinsic to the network topology, and permits rapidly and efficient augmentation of a large number of nodes in one time-step. “Effective augmentation” is shown to work successfully on a wide range of model and real networks. The method has numerous applications (e.g. study of biological, social, power and technological networks) and potentially of significant practical and economic value. PMID:27165120

  15. Effective Augmentation of Complex Networks

    NASA Astrophysics Data System (ADS)

    Wang, Jinjian; Yu, Xinghuo; Stone, Lewi

    2016-05-01

    Networks science plays an enormous role in many aspects of modern society from distributing electrical power across nations to spreading information and social networking amongst global populations. While modern networks constantly change in size, few studies have sought methods for the difficult task of optimising this growth. Here we study theoretical requirements for augmenting networks by adding source or sink nodes, without requiring additional driver-nodes to accommodate the change i.e., conserving structural controllability. Our “effective augmentation” algorithm takes advantage of clusters intrinsic to the network topology, and permits rapidly and efficient augmentation of a large number of nodes in one time-step. “Effective augmentation” is shown to work successfully on a wide range of model and real networks. The method has numerous applications (e.g. study of biological, social, power and technological networks) and potentially of significant practical and economic value.

  16. Augmented reality building operations tool

    SciTech Connect

    Brackney, Larry J.

    2014-09-09

    A method (700) for providing an augmented reality operations tool to a mobile client (642) positioned in a building (604). The method (700) includes, with a server (660), receiving (720) from the client (642) an augmented reality request for building system equipment (612) managed by an energy management system (EMS) (620). The method (700) includes transmitting (740) a data request for the equipment (612) to the EMS (620) and receiving (750) building management data (634) for the equipment (612). The method (700) includes generating (760) an overlay (656) with an object created based on the building management data (634), which may be sensor data, diagnostic procedures, or the like. The overlay (656) is configured for concurrent display on a display screen (652) of the client (642) with a real-time image of the building equipment (612). The method (700) includes transmitting (770) the overlay (656) to the client (642).

  17. Stress and temperature dependence of screw dislocation mobility in {alpha}-Fe by molecular dynamics

    SciTech Connect

    Gilbert, M. R.

    2011-11-01

    The low-temperature plastic yield of {alpha}-Fe single crystals is known to display a strong temperature dependence and to be controlled by the thermally activated motion of screw dislocations. In this paper, we present molecular dynamics simulations of (1/2)<111>{l_brace}112{r_brace} screw dislocation motion as a function of temperature and stress in order to extract mobility relations that describe the general dynamic behavior of screw dislocations in pure {alpha}-Fe. We find two dynamic regimes in the stress-velocity space governed by different mechanisms of motion. Consistent with experimental evidence, at low stresses and temperatures, the dislocations move by thermally activated nucleation and propagation of kink pairs. Then, at a critical stress, a temperature-dependent transition to a viscous linear regime is observed. Critical output from the simulations, such as threshold stresses and the stress dependence of the kink activation energy, are compared to experimental data and other atomistic works with generally very good agreement. Contrary to some experimental interpretations, we find that glide on {l_brace}112{r_brace} planes is only apparent, as slip always occurs by elementary kink-pair nucleation/propagation events on {l_brace}110{r_brace} planes. Additionally, a dislocation core transformation from compact to dissociated has been identified above room temperature, although its impact on the general mobility is seen to be limited. This and other observations expose the limitations of inferring or presuming dynamic behavior on the basis of only static calculations. We discuss the relevance and applicability of our results and provide a closed-form functional mobility law suitable for mesoscale computational techniques.

  18. TDRSS Augmentation System for Satellites

    NASA Technical Reports Server (NTRS)

    Heckler, Gregory W.; Gramling, Cheryl; Valdez, Jennifer; Baldwin, Philip

    2016-01-01

    In 2015, NASA Goddard Space Flight Center (GSFC) reinvigorated the development of the TDRSS Augmentation Service for Satellites (TASS). TASS is a global, space-based, communications and navigation service for users of Global Navigation Satellite Systems(GNSS) and the Tracking and Data Relay Satellite System (TDRSS). TASS leverages the existing TDRSS to provide an S-band beacon radio navigation and messaging source to users at orbital altitudes 1400 km and below.

  19. Media-Augmented Exercise Machines

    NASA Astrophysics Data System (ADS)

    Krueger, T.

    2002-01-01

    Cardio-vascular exercise has been used to mitigate the muscle and cardiac atrophy associated with adaptation to micro-gravity environments. Several hours per day may be required. In confined spaces and long duration missions this kind of exercise is inevitably repetitive and rapidly becomes uninteresting. At the same time, there are pressures to accomplish as much as possible given the cost- per-hour for humans occupying orbiting or interplanetary. Media augmentation provides a the means to overlap activities in time by supplementing the exercise with social, recreational, training or collaborative activities and thereby reducing time pressures. In addition, the machine functions as an interface to a wide range of digital environments allowing for spatial variety in an otherwise confined environment. We hypothesize that the adoption of media augmented exercise machines will have a positive effect on psycho-social well-being on long duration missions. By organizing and supplementing exercise machines, data acquisition hardware, computers and displays into an interacting system this proposal increases functionality with limited additional mass. This paper reviews preliminary work on a project to augment exercise equipment in a manner that addresses these issues and at the same time opens possibilities for additional benefits. A testbed augmented exercise machine uses a specialty built cycle trainer as both input to a virtual environment and as an output device from it using spatialized sound, and visual displays, vibration transducers and variable resistance. The resulting interactivity increases a sense of engagement in the exercise, provides a rich experience of the digital environments. Activities in the virtual environment and accompanying physiological and psychological indicators may be correlated to track and evaluate the health of the crew.

  20. Augment railgun and sequential discharge

    NASA Astrophysics Data System (ADS)

    Kobayashi, K.

    1993-01-01

    Proprietary R&D efforts toward the creation of tactical weapon systems-applicable railguns are presented. Attention is given to measures taken for projectile velocity maximization and sequential-discharge operation, and to an augmenting railgun which has demonstrated a 66-percent efficiency improvement over the two-rail baseline railgun system. This device is characterized by strong interaction between capacitor bank submodules during sequential discharge.

  1. Measuring patient outcomes in breast augmentation: introducing the BREAST-Q Augmentation module.

    PubMed

    Pusic, Andrea L; Reavey, Patrick L; Klassen, Anne F; Scott, Amie; McCarthy, Colleen; Cano, Stefan J

    2009-01-01

    The Breast-Q Augmentation module is a new and unique questionnaire for measuring patient-reported outcomes following breast augmentation. It has undergone a rigorous development and validation process and is currently the only questionnaire for breast augmentation that meets international and federal standards for questionnaire development. The Breast-Q Augmentation module covers a comprehensive set of concerns of breast augmentation patients, including satisfaction with breasts and impact on quality of life. With its excellent psychometric properties, the Breast-Q Augmentation module can provide clinicians and researchers with a wealth of essential data to improve the field of breast augmentation from the perspectives of both surgeons and patients.

  2. Adaptive backstepping sliding mode control of flexible ball screw drives with time-varying parametric uncertainties and disturbances.

    PubMed

    Dong, Liang; Tang, Wen Cheng

    2014-01-01

    This paper presents a method to model and design servo controllers for flexible ball screw drives with dynamic variations. A mathematical model describing the structural flexibility of the ball screw drive containing time-varying uncertainties and disturbances with unknown bounds is proposed. A mode-compensating adaptive backstepping sliding mode controller is designed to suppress the vibration. The time-varying uncertainties and disturbances represented in finite-term Fourier series can be estimated by updating the Fourier coefficients through function approximation technique. Adaptive laws are obtained from Lyapunov approach to guarantee the convergence and stability of the closed loop system. The simulation results indicate that the tracking accuracy is improved considerably with the proposed scheme when the time-varying parametric uncertainties and disturbances exist.

  3. Rotational Stability of Scaphoid Osteosyntheses: An In Vitro Comparison of Small Fragment Cannulated Screws to Novel Bone Screw Sets

    PubMed Central

    Erhart, Jochen; Unger, Ewald; Schefzig, Philip; Varga, Peter; Trulson, Inga; Gormasz, Anna; Trulson, Alexander; Reschl, Martin; Hagmann, Michael; Vecsei, Vilmos; Mayr, Winfried

    2016-01-01

    Background The current standard of care for operative repair of scaphoid fractures involves reduction and internal fixation with a single headless compression screw. However, a compression screw in isolation does not necessarily control rotational stability at a fracture or nonunion site. The single screw provides rotational control through friction and bone interdigitation from compression at the fracture site. We hypothesize that osteosyntheses with novel bone screw sets (BSS) equipped with anti-rotational elements provide improved rotational stability. Methods Stability of osteosynthesis under increasing cyclic torsional loading was investigated on osteotomized cadaveric scaphoids. Two novel prototype BSS, oblique type (BSS-obl.) and longitudinal type (BSS-long.) were compared to three conventional screws: Acutrak2®mini, HCS®3.0 and Twinfix®. Biomechanical tests were performed on scaphoids from single donors in paired comparison and analyzed by balanced incomplete random block design. Loading was increased by 50 mNm increments with 1,000 cycles per torque level and repeated until a rotational clearance of 10°. Primary outcome measure was the number of cycles to 10° clearance, secondary outcome measure was the maximum rotational clearance for each torque level. Findings BSS-obl. performed significantly better than Acutrak2®mini and HCS® (p = 0.015, p<0.0001). BSS-long. performed significantly better than HCS® (p = 0.010). No significant difference in performance between BSS-obl. and BSS-long. (p = 0.361), between BSS obl. and Twinfix® (p = 0.50) and BSS long. and Twinfix® (p = 0.667) was detected. Within the torque range up to 200 mNm, four of 21 (19%) BSS-long. and four of 21 (19%) BSS-obl. preparations showed early failure. The same loading led to early failure in four (29%) Twinfix®, seven (50%) Acutrak2®mini and 10 (71%) HCS® of 14 screw samples, respectively. Conclusions For both BSS and to a lesser extent for Twinfix® (as dual-component screw

  4. Augmented Shock Wave Severance of Materials

    NASA Technical Reports Server (NTRS)

    Bement, Laurence J.; Schimmel, Morry L.

    1995-01-01

    This paper describes a new approach for severing or weakening a variety of materials. The technique employs embedding explosive cords into parallel grooves that are cut into a surface of a material. The cords are initiated simultaneously to produce shock waves that progress toward the centerline between the cords and the lower surface of the material. Intersecting incident and reflected waves augment at the centerline to fail or weaken the material in tension. No harmful debris is produced on the opposite side of the material from the explosive cords. The primary focus of the effort described in this paper was to fracture the F-16 aircraft trilaminate canopy. Also, complete severance was achieved in 2024-T4 aluminum plate stock. Possible applications are through canopy egress and crew module severance from military aircraft and separation of rocket vehicle stages and payloads. This approach offers important advantages over explosive methods currently in use.

  5. 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

  6. Ultraprecision Positioning by Preload Change of Lead Screws

    NASA Astrophysics Data System (ADS)

    Nakashima, Katuhiro; Tamaru, Yuuma; Takafuji, Kazuki

    Ultraprecision positioning is examined for a fine feed system utilizing the elastic deformation of lead screws accompanying the change in the preload in a double nut. The nonlinear deformation due to Hertzian contact of the ball screw can be ignored within a feed of 1μm under an dequate initial preload. No effect of table load on nanometer-order displacement is observed in the range from 10 to 50 kg. The table displacement obtained under an increase in the preload coincides well with the result under a decrease in the preload. Feed control with preload change based on a one-to-one correspondence of preload change and displacement is effective for avoiding the hysterisis phenomenon of the piezoelectric acturator adopted as a deformable spacing part in a double nut. In addition, the preload can be used as a measure to detect the table displacement in place of a position sensor which sometimes shows unreliability owing to unstable performance in the nanometer region. The minimum step feed deduced from preload change is 1nm for a sliding screw and 5nm for a ball screw.

  7. 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

  8. Dynamics of discrete screw dislocations on glide directions

    NASA Astrophysics Data System (ADS)

    Alicandro, R.; De Luca, L.; Garroni, A.; Ponsiglione, M.

    2016-07-01

    We consider a simple discrete model for screw dislocations in crystals. Using a variational discrete scheme we study the motion of a configuration of dislocations toward low energy configurations. We deduce an effective fully overdamped dynamics that follows the maximal dissipation criterion introduced in Cermelli and Gurtin (1999) and predicts motion along the glide directions of the crystal.

  9. 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....

  10. 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...

  11. 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... stabilization of spinal segments in the thoracic, lumbar, and sacral spine as an adjunct to fusion in...

  12. 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... stabilization of spinal segments in the thoracic, lumbar, and sacral spine as an adjunct to fusion in...

  13. 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... stabilization of spinal segments in the thoracic, lumbar, and sacral spine as an adjunct to fusion in...

  14. 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... stabilization of spinal segments in the thoracic, lumbar, and sacral spine as an adjunct to fusion in...

  15. 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... stabilization of spinal segments in the thoracic, lumbar, and sacral spine as an adjunct to fusion in...

  16. Tibiofibular screw fixation for syndesmotic ruptures: a biomechanical analysis.

    PubMed

    Stein, G; Eichler, C; Ettmann, L; Koebke, J; Müller, L P; Thelen, U; Skouras, E

    2012-09-01

    The mechanisms of injuries to the tibiofibular syndesmosis include isolated rupture and rupture in combination with ankle fractures. Current concepts of surgical treatment are fixation using bioabsorbable screws, syndesmotic stapling, syndesmotic hooks, and the widely used screw fixation. Postoperative care utilises passive motion of the ankle joint either with or without axial weight-bearing. The aim of our investigation was to quantify the motion of the mortise during axial load. Therefore, photoelastic tests, on the one hand, and biomechanical tests of cadaveric specimens, on the other, using axial loads of up to 2,000 N were used. Our photoelastic investigations showed force distribution through the screw into the cranial and caudal parts of the distal fibula. Biomechanical testing showed a progressive dehiscence in both ruptured and fixated specimens up to 2.89 (ruptured) and 2.42 mm (despite screw). Our findings strongly suggest a concept of partial weight-bearing at most to support regeneration of scar tissue and to prevent the appearance of instability in the ankle joint. PMID:22415030

  17. 39. VIEW OF VESSEL STERNON IN DRYDOCK. NOTE TWIN SCREWS ...

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

    39. VIEW OF VESSEL STERN-ON IN DRYDOCK. NOTE TWIN SCREWS AND RUDDER. GENTLEMEN IN VIEW UNKNOWN Original 5'x5' photograph taken by Robert S. Douglas in 1966 - Pilot Schooner "Alabama", Moored in harbor at Vineyard Haven, Vineyard Haven, Dukes County, MA

  18. A Case of Implant Failure in Partial Wrist Fusion Applying Magnesium-Based Headless Bone Screws

    PubMed Central

    Emmerich, Judith

    2016-01-01

    This article presents a case of implant failure resulting in mechanical instability of a scaphotrapezotrapezoideal arthrodesis using magnesium-based headless bone screws. During revision surgery osteolysis surrounding the screws was observed as well as degraded screw threads already in existence at 6 weeks after implantation. The supposed osseous integration attributed to magnesium-based screws could not be reproduced in this particular case. Thus, it can be reasoned that the use of magnesium-based screws for partial wrist arthrodesis cannot be encouraged, at least not in dual use. PMID:27800201

  19. Use of computational fluid dynamics simulations for design of a pretreatment screw conveyor reactor.

    PubMed

    Berson, R Eric; Hanley, Thomas R

    2005-01-01

    Computational fluid dynamics simulations were employed to compare performance of various designs of a pretreatment screw conveyor reactor. The reactor consisted of a vertical screw used to create cross flow between the upward conveying solids and the downward flow of acid. Simulations were performed with the original screw design and a modified design in which the upper flights of the screw were removed. Results of the simulations show visually that the modified design provided favorable plug flow behavior within the reactor. Pressure drop across the length of the reactor without the upper screws in place was predicted by the simulations to be 5 vs 40 kPa for the original design.

  20. Understanding of edge and screw dislocations in nanostructures by modeling and simulations

    NASA Astrophysics Data System (ADS)

    Dontsova, Evgeniya

    The role of the extended dislocation defects in nanostructures only recently began to be explored. In bulk materials, dislocations are modeled only away from their cores within the framework of the continuum mechanics. It is known that applying continuum modeling in the core region leads to divergences. In nanostructures, the core region dominates and new investigation methods are needed. This work contributes to the fundamental understanding of the role of dislocations in important carbon and zinc oxide nanostructures, by using atomistic investigation methods. In quasi-zero-dimensional structures, thesis describes the first attempt to rationalize dislocation processes in carbon nano-onions. Experiments show that carbon nano-onions exhibit an unusual dislocation dynamics with unexpected attraction of outer edge dislocation towards the core. Atomistic calculations combined with rigorous energy analysis attribute this behavior to an unusual inward driving force on the outer edge dislocation associated with a reduction in the number of dangling bonds. Moving on to quasi-one-dimensional nanostructures, we study the stability of screw-dislocated zinc oxide structures in the wurtzite phase with a symmetry-adapted molecular dynamics methodology, which introduces a significant simplification in the simulation domain size by accounting for the helical symmetry explicitly. The goal is to provide the theoretical support for a universal screw-dislocation-driven growth mechanism suggested by recent experiments. Moreover, the effects of axial screw dislocations on the electronic properties in helical zinc oxide nanowires and nanotubes are explored. We demonstrate significant screw-dislocation-induced band gap modifications that originate in the highly distorted cores. Finally, using the same objective technique, we investigate the stability against torsional deformations of quasi-one-dimensional graphene nanoribbons with bare, F-, and OH-saturated armchair edges. The prevalence

  1. Computer navigation versus fluoroscopy-guided navigation for thoracic pedicle screw placement: a meta-analysis.

    PubMed

    Meng, Xiao-Tong; Guan, Xiao-Fei; Zhang, Hai-Long; He, Shi-Sheng

    2016-07-01

    Although application of intraoperative computer navigation technique had been integrated into placement of pedicle screws (PSs) in thoracic fusion for years, its security and practicability remain controversial. The aim of this study is to evaluate the accuracy, the operative time consumption, the amount of intraoperative blood loss, time of pedicle insertion and the incidence of complications of thoracic pedicle screw placement in patients with thoracic diseases such as scoliosis and kyphosis. Pubmed, Web of Knowledge, and Google scholar were searched to identify comparative studies of thoracic pedicle screw placement between intraoperative computer navigation and fluoroscopy-guided navigation. Outcomes of malposition rate, operative time consumption, insertion time, intraoperative blood loss, and the incidence of complications are evaluated. Fourteen articles including 1723 patients and 9019 PSs were identified matching inclusion criteria. The malposition rate was lower (RR: 0.33, 95 % CI: 0.28-0.38, P < 0.01) in computer navigation group than that in fluoroscopy-guided navigation group; the operative time was significantly longer [weighted mean difference (WMD) = 23.66, 95 % CI: 14.74-32.57, P < 0.01] in computer navigation group than that in fluoroscopy-guided navigation group. The time of insertion was shorter (WMD = -1.88, 95 % CI: -2.25- -1.52, P < 0.01) in computer navigation group than that in fluoroscopy-guided navigation group. The incidence of complications was lower (RR = 0. 23, 95 % CI: 0.12-0.46, P < 0.01) in computer navigation group than that in the other group. The intraoperative blood loss was fewer (WMD = -167.49, 95 % CI: -266.39- -68.58, P < 0.01) in computer navigation group than that in the other. In conclusion, the meta-analysis of thoracic pedicle screw placement studies clearly demonstrated lower malposition rate, less intraoperative blood loss, and fewer complications when using computer

  2. Computer navigation versus fluoroscopy-guided navigation for thoracic pedicle screw placement: a meta-analysis.

    PubMed

    Meng, Xiao-Tong; Guan, Xiao-Fei; Zhang, Hai-Long; He, Shi-Sheng

    2016-07-01

    Although application of intraoperative computer navigation technique had been integrated into placement of pedicle screws (PSs) in thoracic fusion for years, its security and practicability remain controversial. The aim of this study is to evaluate the accuracy, the operative time consumption, the amount of intraoperative blood loss, time of pedicle insertion and the incidence of complications of thoracic pedicle screw placement in patients with thoracic diseases such as scoliosis and kyphosis. Pubmed, Web of Knowledge, and Google scholar were searched to identify comparative studies of thoracic pedicle screw placement between intraoperative computer navigation and fluoroscopy-guided navigation. Outcomes of malposition rate, operative time consumption, insertion time, intraoperative blood loss, and the incidence of complications are evaluated. Fourteen articles including 1723 patients and 9019 PSs were identified matching inclusion criteria. The malposition rate was lower (RR: 0.33, 95 % CI: 0.28-0.38, P < 0.01) in computer navigation group than that in fluoroscopy-guided navigation group; the operative time was significantly longer [weighted mean difference (WMD) = 23.66, 95 % CI: 14.74-32.57, P < 0.01] in computer navigation group than that in fluoroscopy-guided navigation group. The time of insertion was shorter (WMD = -1.88, 95 % CI: -2.25- -1.52, P < 0.01) in computer navigation group than that in fluoroscopy-guided navigation group. The incidence of complications was lower (RR = 0. 23, 95 % CI: 0.12-0.46, P < 0.01) in computer navigation group than that in the other group. The intraoperative blood loss was fewer (WMD = -167.49, 95 % CI: -266.39- -68.58, P < 0.01) in computer navigation group than that in the other. In conclusion, the meta-analysis of thoracic pedicle screw placement studies clearly demonstrated lower malposition rate, less intraoperative blood loss, and fewer complications when using computer

  3. 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)

  4. Bioresorbable screws reinforced with phosphate glass fibre: manufacturing and mechanical property characterisation.

    PubMed

    Felfel, R M; Ahmed, I; Parsons, A J; Rudd, C D

    2013-01-01

    Use of bioresorbable screws could eliminate disadvantages associated with metals such as removal operations, corrosion, MRI interference and stress shielding. Mechanical properties of bioresorbable polymers alone are insufficient for load bearing applications application as screws. Thus, reinforcement is necessary to try and match or surpass the mechanical properties of cortical bone. Phosphate based glass fibres were used to reinforce polylactic acid (PLA) in order to produce unidirectionally aligned (UD) and unidirectionally plus randomly distributed (UD/RM) composite screws (P40 UD and P40 UD/RM). The maximum flexural and push-out properties for the composite screws (P40 UD and P40 UD/RM) increased by almost 100% in comparison with the PLA screws. While the pull-out strength and stiffness of the headless composite screws were ∼80% (strength) and ∼130% (stiffness) higher than for PLA, those with heads exhibited properties lower than those for PLA alone as a result of failure at the heads. An increase in the maximum shear load and stiffness for the composite screws (∼30% and ∼40%) in comparison to the PLA screws was also seen. Maximum torque for the PLA screws was ∼1000 mN m, while that for the composite screws were slightly lower. The SEM micrographs for P40 UD and P40 UD/RM screws revealed small gaps around the fibres, which were suggested to be due to buckling of the UD fibres during the manufacturing process.

  5. Bioresorbable screws reinforced with phosphate glass fibre: manufacturing and mechanical property characterisation.

    PubMed

    Felfel, R M; Ahmed, I; Parsons, A J; Rudd, C D

    2013-01-01

    Use of bioresorbable screws could eliminate disadvantages associated with metals such as removal operations, corrosion, MRI interference and stress shielding. Mechanical properties of bioresorbable polymers alone are insufficient for load bearing applications application as screws. Thus, reinforcement is necessary to try and match or surpass the mechanical properties of cortical bone. Phosphate based glass fibres were used to reinforce polylactic acid (PLA) in order to produce unidirectionally aligned (UD) and unidirectionally plus randomly distributed (UD/RM) composite screws (P40 UD and P40 UD/RM). The maximum flexural and push-out properties for the composite screws (P40 UD and P40 UD/RM) increased by almost 100% in comparison with the PLA screws. While the pull-out strength and stiffness of the headless composite screws were ∼80% (strength) and ∼130% (stiffness) higher than for PLA, those with heads exhibited properties lower than those for PLA alone as a result of failure at the heads. An increase in the maximum shear load and stiffness for the composite screws (∼30% and ∼40%) in comparison to the PLA screws was also seen. Maximum torque for the PLA screws was ∼1000 mN m, while that for the composite screws were slightly lower. The SEM micrographs for P40 UD and P40 UD/RM screws revealed small gaps around the fibres, which were suggested to be due to buckling of the UD fibres during the manufacturing process. PMID:23122715

  6. Posterior Wall Blowout During Anterior Cruciate Ligament Reconstruction: Suspensory Cortical Fixation With a Screw and Washer Post.

    PubMed

    Mitchell, Justin J; Chahla, Jorge; Dean, Chase S; Menge, Travis J; Vap, Alexander R; Cram, Tyler R; LaPrade, Robert F

    2016-06-01

    Posterior wall blowout can be a devastating intraoperative complication in anterior cruciate ligament reconstruction. This loss of osseous containment can cause difficulty with graft fixation and can potentially lead to early graft failure if unrecognized and left untreated. If cortical blowout occurs despite careful planning and proper surgical technique, a thorough knowledge of the local anatomy and surgical salvage options is paramount to ensure positive patient outcomes. This article highlights our preferred salvage technique using suspensory cortical fixation with a screw and washer construct. PMID:27656377

  7. Scar due to skin incision for screw fixation through the transbuccal approach after sagittal split ramus osteotomy.

    PubMed

    Muto, Toshitaka

    2012-05-01

    Most rigid fixation techniques after sagittal split ramus osteotomies of the mandible involve the transbuccal approach. A skin incision in the cheek carries with it possible undesirable sequelae, such as noticeable scarring. The aim of this study was to investigate whether there is scarring in the face after this technique. For screw insertion, a 5-mm stab incision was performed on 40 Japanese patients (20 men and 20 women) with class III occlusion. After surgery, gross examination (via the naked eyes) of the skin incision was performed monthly for 1 year by the same oral surgeon. In all cases, the skin incision had disappeared by 1 year after the surgery. PMID:22627425

  8. Do abnormal hemipelvic bone stresses contribute to loosening and migration of screw-threaded cups?

    PubMed

    Learmonth, I D; Spirakis, A

    1994-03-01

    Excellent long-term results have been reported with the Charnley low-friction arthroplasty. Failure of the cemented acetabular component has been identified as a problem in the longer term, while cemented hip replacements in active young patients have exhibited a disconcerting incidence of early clinical or radiological failure. This resulted in the development of the cementless arthroplasty. Bone responds favourably to an optimal stress window and reacts dynamically to metal implants that have a greatly differing modulus of elasticity. This study represents a comparative qualitative analysis of the peri-acetabular hemipelvic stresses after loading two cementless (press-fit and screw-threaded) acetabular components inserted into identical bone models. A simplified model of the artificial hip joint was constructed and the very sensitive stress analysis technique of holographic interferometry was used for the investigation. Peri-acetabular stress concentrations were noted with the screw-threaded cup. This may predispose to bone resorption and it is suggested that these could be implicated in the migration of these cups described in published reports.

  9. The solution growth of copper nanowires and nanotubes is driven by screw dislocations.

    PubMed

    Meng, Fei; Jin, Song

    2012-01-11

    Copper (Cu) nanowires (NWs) are inexpensive conducting nanomaterials intensively explored for transparent conducting electrodes and other applications. However, the mechanism for solution growth of Cu NWs remains elusive so far. Here we show that the one-dimensional anisotropic growth of Cu NWs and nanotubes (NTs) in solution is driven by axial screw dislocations. All three types of evidence for dislocation-driven growth have been conclusively observed using transmission electron microscopy (TEM) techniques: rigorous two-beam TEM analysis that conclusively characterizes the dislocations in the NWs to be pure screw dislocations along <110> direction, twist contour analysis that confirms the presence of Eshelby twist associated with the dislocation, and the observation of spontaneously formed hollow NTs. The reduction-oxidation (redox) electrochemical reaction forming the Cu NWs presents new chemistry for controlling supersaturation to promote dislocation-driven NW growth. Using this understanding to intentionally manipulate the supersaturation, we have further improved the NW growth by using a continuous flow reactor to yield longer Cu NWs under much milder chemical conditions. The rational synthesis of Cu NWs with control over size and geometry will facilitate their applications. PMID:22142310

  10. Removal of a femoral intramedullary nail with impacted nail end cap using a broken screw extraction set: a case report and literature review.

    PubMed

    Tadros, Ayman M A; Elhelw, Amin M; Eldehi, Mahmoud; Al-Shaeel, Rashed Ahmed

    2015-01-01

    We report the technique we used in extraction of a femoral intramedullary nail with impacted nail cap. The extraction was done using a damaged screw extraction device and a bone hook, with no additional bone or soft tissue damage. This technique has not been reported before in the literature. We also review the cases reported for difficult nail extractions due to impacted nail end caps.

  11. Webizing mobile augmented reality content

    NASA Astrophysics Data System (ADS)

    Ahn, Sangchul; Ko, Heedong; Yoo, Byounghyun

    2014-01-01

    This paper presents a content structure for building mobile augmented reality (AR) applications in HTML5 to achieve a clean separation of the mobile AR content and the application logic for scaling as on the Web. We propose that the content structure contains the physical world as well as virtual assets for mobile AR applications as document object model (DOM) elements and that their behaviour and user interactions are controlled through DOM events by representing objects and places with a uniform resource identifier. Our content structure enables mobile AR applications to be seamlessly developed as normal HTML documents under the current Web eco-system.

  12. Full mouth implant rehabilitation of a patient with ectodermal dysplasia after orthognathic surgery, sinus and ridge augmentation: a clinical report

    PubMed Central

    Bayat, Mohammad; Khobyari, Mohammad Mohsen; Dalband, Mohsen

    2011-01-01

    An 18-year-old male presented severe hypodontia due to hypohidrotic ectodermal dysplasia was treated with Le Fort I maxillary osteotomy with simultaneous sinus floor augmentation using the mixture of cortical autogenous bone graft harvested from iliac crest and organic Bio-Oss to position the maxilla in a right occlusal plane with respect to the mandible, and to construct adequate bone volume at posterior maxilla allowing proper implant placement. Due to the poor bone quality at other sites, ridge augmentation with onlay graft was done to construct adequate bone volume allowing proper implant placement, using tissue harvested from the iliac bone. Seven implants were placed in the maxilla and 7 implants were inserted in the mandible and screw-retained metal ceramic FPDs were fabricated. The two year follow up data showed that dental implants should be considered as a good treatment modality for patients with ectodermal dysplasia. PMID:21814619

  13. Bibliography on augmentation of convective heat and mass transfer-II

    SciTech Connect

    Bergles, A.E.; Nirmalan, V.; Junkhan, G.H.; Webb, R.L.

    1983-12-01

    Heat transfer augmentation has developed into a major specialty area in heat transfer research and development. This report presents and updated bibliography of world literature on augmentation. The literature is classified into passive augmentation techniques, which require no external power, and active techniques, which do require external power. The fifteen techniques are grouped in terms of their applications to the various modes of heat transfer. Mass transfer is included for completeness. Key words are included with each citation for technique/mode identification. The total number of publications cited is 3045, including 135 surveys of various techniques and 86 papers on performance evaluation of passive techniques. Patents are not included, as they are the subject of a separate bibliographic report.

  14. Minimally Invasive Transforaminal Lumbar Interbody Fusion with Unilateral Pedicle Screw Fixation: Comparison between Primary and Revision Surgery

    PubMed Central

    Kang, Moo Sung; Kim, Kyung Hyun; Kuh, Sung Uk; Chin, Dong Kyu; Kim, Keun Su; Cho, Yong Eun

    2014-01-01

    Minimally invasive surgery with a transforaminal lumbar interbody fusion (MIS TLIF) is an important minimally invasive fusion technique for the lumbar spine. Lumbar spine reoperation is challenging and is thought to have greater complication risks. The purpose of this study was to compare MIS TLIF with unilateral screw fixation perioperative results between primary and revision surgeries. This was a prospective study that included 46 patients who underwent MIS TLIF with unilateral pedicle screw. The patients were divided into two groups, primary and revision MIS TLIF, to compare perioperative results and complications. The two groups were similar in age, sex, and level of operation, and were not significantly different in the length of follow-up or clinical results. Although dural tears were more common with the revision group (primary 1; revision 4), operation time, blood loss, total perioperative complication, and fusion rates were not significantly different between the two groups. Both groups showed substantial improvements in VAS and ODI scores one year after surgical treatment. Revision MIS TLIF performed by an experienced surgeon does not necessarily increase the risk of perioperative complication compared with primary surgery. MIS TLIF with unilateral pedicle screw fixation is a valuable option for revision lumbar surgery. PMID:24949483

  15. Augmented microscopy with near-infrared fluorescence detection

    NASA Astrophysics Data System (ADS)

    Watson, Jeffrey R.; Martirosyan, Nikolay; Skoch, Jesse; Lemole, G. Michael; Anton, Rein; Romanowski, Marek

    2015-03-01

    Near-infrared (NIR) fluorescence has become a frequently used intraoperative technique for image-guided surgical interventions. In procedures such as cerebral angiography, surgeons use the optical surgical microscope for the color view of the surgical field, and then switch to an electronic display for the NIR fluorescence images. However, the lack of stereoscopic, real-time, and on-site coregistration adds time and uncertainty to image-guided surgical procedures. To address these limitations, we developed the augmented microscope, whereby the electronically processed NIR fluorescence image is overlaid with the anatomical optical image in real-time within the optical path of the microscope. In vitro, the augmented microscope can detect and display indocyanine green (ICG) concentrations down to 94.5 nM, overlaid with the anatomical color image. We prepared polyacrylamide tissue phantoms with embedded polystyrene beads, yielding scattering properties similar to brain matter. In this model, 194 μM solution of ICG was detectable up to depths of 5 mm. ICG angiography was then performed in anesthetized rats. A dynamic process of ICG distribution in the vascular system overlaid with anatomical color images was observed and recorded. In summary, the augmented microscope demonstrates NIR fluorescence detection with superior real-time coregistration displayed within the ocular of the stereomicroscope. In comparison to other techniques, the augmented microscope retains full stereoscopic vision and optical controls including magnification and focus, camera capture, and multiuser access. Augmented microscopy may find application in surgeries where the use of traditional microscopes can be enhanced by contrast agents and image guided delivery of therapeutics, including oncology, neurosurgery, and ophthalmology.

  16. Augmented reality in medical education?

    PubMed

    Kamphuis, Carolien; Barsom, Esther; Schijven, Marlies; Christoph, Noor

    2014-09-01

    Learning in the medical domain is to a large extent workplace learning and involves mastery of complex skills that require performance up to professional standards in the work environment. Since training in this real-life context is not always possible for reasons of safety, costs, or didactics, alternative ways are needed to achieve clinical excellence. Educational technology and more specifically augmented reality (AR) has the potential to offer a highly realistic situated learning experience supportive of complex medical learning and transfer. AR is a technology that adds virtual content to the physical real world, thereby augmenting the perception of reality. Three examples of dedicated AR learning environments for the medical domain are described. Five types of research questions are identified that may guide empirical research into the effects of these learning environments. Up to now, empirical research mainly appears to focus on the development, usability and initial implementation of AR for learning. Limited review results reflect the motivational value of AR, its potential for training psychomotor skills and the capacity to visualize the invisible, possibly leading to enhanced conceptual understanding of complex causality.

  17. Augmented reality in medical education?

    PubMed

    Kamphuis, Carolien; Barsom, Esther; Schijven, Marlies; Christoph, Noor

    2014-09-01

    Learning in the medical domain is to a large extent workplace learning and involves mastery of complex skills that require performance up to professional standards in the work environment. Since training in this real-life context is not always possible for reasons of safety, costs, or didactics, alternative ways are needed to achieve clinical excellence. Educational technology and more specifically augmented reality (AR) has the potential to offer a highly realistic situated learning experience supportive of complex medical learning and transfer. AR is a technology that adds virtual content to the physical real world, thereby augmenting the perception of reality. Three examples of dedicated AR learning environments for the medical domain are described. Five types of research questions are identified that may guide empirical research into the effects of these learning environments. Up to now, empirical research mainly appears to focus on the development, usability and initial implementation of AR for learning. Limited review results reflect the motivational value of AR, its potential for training psychomotor skills and the capacity to visualize the invisible, possibly leading to enhanced conceptual understanding of complex causality. PMID:24464832

  18. PRP Augmentation for ACL Reconstruction.

    PubMed

    Andriolo, Luca; Di Matteo, Berardo; Kon, Elizaveta; Filardo, Giuseppe; Venieri, Giulia; Marcacci, Maurilio

    2015-01-01

    Current research is investigating new methods to enhance tissue healing to speed up recovery time and decrease the risk of failure in Anterior Cruciate Ligament (ACL) reconstructive surgery. Biological augmentation is one of the most exploited strategies, in particular the application of Platelet Rich Plasma (PRP). Aim of the present paper is to systematically review all the preclinical and clinical papers dealing with the application of PRP as a biological enhancer during ACL reconstructive surgery. Thirty-two studies were included in the present review. The analysis of the preclinical evidence revealed that PRP was able to improve the healing potential of the tendinous graft both in terms of histological and biomechanical performance. Looking at the available clinical evidence, results were not univocal. PRP administration proved to be a safe procedure and there were some evidences that it could favor the donor site healing in case of ACL reconstruction with patellar tendon graft and positively contribute to graft maturation over time, whereas the majority of the papers did not show beneficial effects in terms of bony tunnels/graft area integration. Furthermore, PRP augmentation did not provide superior functional results at short term evaluation. PMID:26064903

  19. Direct Repair without Augmentation of Patellar Tendon Avulsion following TKA

    PubMed Central

    Kumar, Nishikant; Yadav, Chandrashekhar; Kumar, Ashok

    2015-01-01

    Complications involving the extensor mechanism after TKA are potentially disastrous. We are reporting a case of patellar tendon rupture from tibial tuberosity following total knee arthroplasty. We managed it by direct repair with fiberwire using Krackow suture technique without augmentation. Our long term result has been very encouraging. Our method is a safe and better method of management of patellar tendon avulsion following TKA when it happens without any tissue loss. PMID:25632362

  20. Volume Augmentation in the Lower Eyelid and Cheek Areas.

    PubMed

    Yim, Hyung Woo; Nguyen, Anh H; Kim, Yong Kyu

    2015-08-01

    Many East Asians experience lower eyelid bulging and discoloration, and this is seen even in young individuals. The condition is caused by an undergrowth of the maxilla and not by aging. In this condition, the orbit appears small and the infraorbital rim is hypoplastic. This inevitably causes a depressed, tired, and sad appearance. Here, the authors present techniques of volume augmentation in the lower eyelid and cheek areas to rejuvenate the midface in Asians. PMID:26306085

  1. Cervical anterior transpedicular screw fixation (ATPS)—Part II. Accuracy of manual insertion and pull-out strength of ATPS

    PubMed Central

    Acosta, Frank; Tauber, Mark; Fox, Michael; Martin, Hudelmaier; Forstner, Rosmarie; Augat, Peter; Penzkofer, Rainer; Pirich, Christian; Kässmann, H.; Resch, Herbert; Hitzl, Wolfgang

    2008-01-01

    Reconstruction after multilevel decompression of the cervical spine, especially in the weakened osteoporotic, neoplastic or infectious spine often requires circumferential stabilization and fusion. To avoid the additional posterior surgery in these cases while increasing rigidity of anterior-only screw-plate constructs, the authors introduce the concept of anterior transpedicular screw (ATPS) fixation. We demonstrated its morphological feasibility as well as its indications in a previous study in Part I of our project. Consequently, the objectives of the current study were to assess the ex vivo accuracy of placing ATPS into the cervical vertebra as well as the biomechanical performance of ATPS in comparison to traditional vertebral body screws (VBS) in terms of pull-out strength (POS). Twenty-three ATPS were inserted alternately to two screws into the pedicles and vertebral bodies, respectively, of six cadaveric specimens from C3–T1. For insertion of ATPS, a manual fluoroscopically assisted technique was used. Pre- and post insertional CT-scans were used to assess accuracy of ATPS insertion in the axial and sagittal planes. A newly designed grading system and accuracy score were used to delineate accuracy of ATPS insertion. Following insertion of screws, 23 ATPS and 22 VBS were subjected to pull-out testing (POT). The bone mineral density (BMD) of each specimen was assessed prior to POT. Statistical analysis showed that the incidence of correctly placed screws and non-critical pedicles breaches in axial plane was 78.3%, and 95.7% in sagittal plane. Hence, according to our definition of “critical” pedicle breach that exposes neurovascular structures at risk, 21.7% (n = 5) of all ATPS inserted showed a critical pedicle breach in axial plane. Notably, no critical pedicle perforation occurred at the C6 to T1 levels. Pull-out testing of ATPS and VBS revealed that pull-out resistance of ATPS was 2.5-fold that of VBS. Mean POS of 23 ATPS with a mean BMD of 0.566

  2. Flexible augmented reality architecture applied to environmental management

    NASA Astrophysics Data System (ADS)

    Correia, Nuno M. R.; Romao, Teresa; Santos, Carlos; Trabuco, Adelaide; Santos, Rossana; Romero, Luis; Danado, Jose; Dias, Eduardo; Camara, Antonio; Nobre, Edmundo

    2003-05-01

    Environmental management often requires in loco observation of the area under analysis. Augmented Reality (AR) technologies allow real time superimposition of synthetic objects on real images, providing augmented knowledge about the surrounding world. Users of an AR system can visualize the real surrounding world together with additional data generated in real time in a contextual way. The work reported in this paper was done in the scope of ANTS (Augmented Environments) project. ANTS is an AR project that explores the development of an augmented reality technological infrastructure for environmental management. This paper presents the architecture and the most relevant modules of ANTS. The system"s architecture follows the client-server model and is based on several independent, but functionally interdependent modules. It has a flexible design, which allows the transfer of some modules to and from the client side, according to the available processing capacities of the client device and the application"s requirements. It combines several techniques to identify the user"s position and orientation allowing the system to adapt to the particular characteristics of each environment. The determination of the data associated to a certain location involves the use of both a 3D Model of the location and the multimedia geo-referenced database.

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

    PubMed

    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.

  4. Weber C ankle fractures: a retrospective audit of screw number, size, complications, and retrieval rates.

    PubMed

    Walker, Logan; Willis, Nigel

    2015-01-01

    Tibiofibular transfixation of Weber C injuries using a diastasis screw is the current method of fixation. However, controversy remains regarding the screw size and number, number of cortices engaged, and the interval to screw removal. The present study reviewed the current practice in the Wellington Region. A retrospective audit of patients with documented Weber C injuries in the Capital & Coast District Health Board from June 2012 to December 2013 was performed. The clinical medical records and radiographs were reviewed, and the patient demographics, surgeon details, screw number, size, cortices engaged, screw removal period, and documented complications were recorded. A total of 36 operations were documented, of which 27 (75%) cases also required fibula plating. Of the 36 cases, 25 (69.44%) used a single diastasis screw, 33 (91.67%) used 4.5-mm screws, and 18 (50%) engaged 3 cortices. Surgical practice did not vary with the experience level. Of the 36 patients, 29 (80.56%) underwent routine screw removal at a median of 20 (25th to 75th quartile range 16 to 22) weeks. Also, 9 (25%) cases of screw fracture occurred, with a median documented interval to fracture of 18 (25th to 75th quartile range 15 to 20) weeks. The surgical management of Weber C injuries is consistent with current practice. The routine removal of diastasis screws by 20 weeks postoperatively was not different from the documented interval of screw removal when screw fractures had occurred. The timing of screw removal needs to be weighed against the fracture risk, patient symptoms, and the risk of secondary procedure complications.

  5. Augmented Reality: A Brand New Challenge for the Assessment and Treatment of Psychological Disorders

    PubMed Central

    Chicchi Giglioli, Irene Alice; Pallavicini, Federica; Pedroli, Elisa; Serino, Silvia; Riva, Giuseppe

    2015-01-01

    Augmented Reality is a new technological system that allows introducing virtual contents in the real world in order to run in the same representation and, in real time, enhancing the user's sensory perception of reality. From another point of view, Augmented Reality can be defined as a set of techniques and tools that add information to the physical reality. To date, Augmented Reality has been used in many fields, such as medicine, entertainment, maintenance, architecture, education, and cognitive and motor rehabilitation but very few studies and applications of AR exist in clinical psychology. In the treatment of psychological disorders, Augmented Reality has given preliminary evidence to be a useful tool due to its adaptability to the patient needs and therapeutic purposes and interactivity. Another relevant factor is the quality of the user's experience in the Augmented Reality system determined from emotional engagement and sense of presence. This experience could increase the AR ecological validity in the treatment of psychological disorders. This paper reviews the recent studies on the use of Augmented Reality in the evaluation and treatment of psychological disorders, focusing on current uses of this technology and on the specific features that delineate Augmented Reality a new technique useful for psychology. PMID:26339283

  6. Augmented Reality: A Brand New Challenge for the Assessment and Treatment of Psychological Disorders.

    PubMed

    Chicchi Giglioli, Irene Alice; Pallavicini, Federica; Pedroli, Elisa; Serino, Silvia; Riva, Giuseppe

    2015-01-01

    Augmented Reality is a new technological system that allows introducing virtual contents in the real world in order to run in the same representation and, in real time, enhancing the user's sensory perception of reality. From another point of view, Augmented Reality can be defined as a set of techniques and tools that add information to the physical reality. To date, Augmented Reality has been used in many fields, such as medicine, entertainment, maintenance, architecture, education, and cognitive and motor rehabilitation but very few studies and applications of AR exist in clinical psychology. In the treatment of psychological disorders, Augmented Reality has given preliminary evidence to be a useful tool due to its adaptability to the patient needs and therapeutic purposes and interactivity. Another relevant factor is the quality of the user's experience in the Augmented Reality system determined from emotional engagement and sense of presence. This experience could increase the AR ecological validity in the treatment of psychological disorders. This paper reviews the recent studies on the use of Augmented Reality in the evaluation and treatment of psychological disorders, focusing on current uses of this technology and on the specific features that delineate Augmented Reality a new technique useful for psychology.

  7. Augmented Reality: A Brand New Challenge for the Assessment and Treatment of Psychological Disorders.

    PubMed

    Chicchi Giglioli, Irene Alice; Pallavicini, Federica; Pedroli, Elisa; Serino, Silvia; Riva, Giuseppe

    2015-01-01

    Augmented Reality is a new technological system that allows introducing virtual contents in the real world in order to run in the same representation and, in real time, enhancing the user's sensory perception of reality. From another point of view, Augmented Reality can be defined as a set of techniques and tools that add information to the physical reality. To date, Augmented Reality has been used in many fields, such as medicine, entertainment, maintenance, architecture, education, and cognitive and motor rehabilitation but very few studies and applications of AR exist in clinical psychology. In the treatment of psychological disorders, Augmented Reality has given preliminary evidence to be a useful tool due to its adaptability to the patient needs and therapeutic purposes and interactivity. Another relevant factor is the quality of the user's experience in the Augmented Reality system determined from emotional engagement and sense of presence. This experience could increase the AR ecological validity in the treatment of psychological disorders. This paper reviews the recent studies on the use of Augmented Reality in the evaluation and treatment of psychological disorders, focusing on current uses of this technology and on the specific features that delineate Augmented Reality a new technique useful for psychology. PMID:26339283

  8. 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.

  9. Release of elements from retrieved maxillofacial plates and screws.

    PubMed

    Bertoldi, C; Pradelli, J M; Consolo, U; Zaffe, D

    2005-09-01

    Vitallium appliances and surrounding tissues were investigated to evaluate the release and accumulation of elements. Four microplates, sixteen screws and surrounding tissues were removed from three patients presenting inflammation 4 to 6 years after surgery and were submitted to SEM and X-ray microprobe analysis. Histology was performed on paraffin or PMMA sections of tissues.A continuous release of elements from metallic appliances into soft tissues was observed. Cobalt, chromium, and nickel were detected in soft and boney tissues in close proximity to the appliance. Aluminium, as a component of screw coatings, accumulated in soft tissues, and a remarkable amount of aluminium was detected in the dense lamella of lamellar bone. The results suggest that coatings containing aluminium should be avoided and the time these appliances are allowed to remain in patients should be shortened. Further studies on element release and the fate of aluminium in bone are warranted.

  10. Analysis of Eyring-Powell Fluid in Helical Screw Rheometer

    PubMed Central

    Siddiqui, A. M.; Haroon, T.; Zeb, M.

    2014-01-01

    This paper aims to study the flow of an incompressible, isothermal Eyring-Powell fluid in a helical screw rheometer. The complicated geometry of the helical screw rheometer is simplified by “unwrapping or flattening” the channel, lands, and the outside rotating barrel, assuming the width of the channel is larger as compared to the depth. The developed second order nonlinear differential equations are solved by using Adomian decomposition method. Analytical expressions are obtained for the velocity profiles, shear stresses, shear at wall, force exerted on fluid, volume flow rates, and average velocity. The effect of non-Newtonian parameters, pressure gradients, and flight angle on the velocity profiles is noticed with the help of graphical representation. The observation confirmed the vital role of involved parameters during the extrusion process. PMID:24707194

  11. Delayed perforation of the aorta by a thoracic pedicle screw.

    PubMed

    Wegener, Bernd; Birkenmaier, Christof; Fottner, Andreas; Jansson, Volkmar; Dürr, Hans Roland

    2008-09-01

    Pedicle screw instrumentation has become increasingly popular during the past 20 years and a vast selection of products is available on the market. With rising implantation rates, reports about specific complications also have increased. The main reason for these complications is the fact that the course of the pedicle and in turn the positioning of the pedicle screw cannot be adequately controlled visually. Based on the anatomy of the surrounding structures, complications caused by malpositioning can be divided into three main groups: mechanical, neurological and vascular. Beyond mechanical limitations of spinal motion, nerve injury can lead to neurological problems while injuries to vascular structures usually cause hemorrhage. These typical problems in general become apparent intraoperatively or in the immediate postoperative course. We report on a rare delayed complication and analyze the factors that led to it. In addition, we outline our treatment strategy. The goal has to be to avoid such problems in the future by using suitable navigational aids. PMID:18622634

  12. Intramedullary screw fixation of proximal fifth metatarsal fractures in athletes

    PubMed Central

    Massada, Marta Maria Teixeira de Oliveira; Pereira, Manuel Alexandre Negrais Pinho Gonçalves; de Sousa, Ricardo Jorge Gomes; Costa, Paulo Guimarães; Massada, José Leandro da Rocha

    2012-01-01

    Objective The purpose of this study was to review the short- and long-term clinical and radiological results of intramedullary compression screw fixation of proximal fifth metatarsal fractures in athletes. Methods Eleven male and six female active patients with fifth metatarsal zone II and zone III fractures fixed with a 4.5-mm cannulated compression screw were evaluated by chart review, review of radiographs, and clinical evaluation. Fifteen of the patients were high-level athletes (soccer: n=11; basketball: n=1; track and field: n=3) and two were recreational-level athletes. Mean follow-up from surgery to evaluation was 54 (38-70) months. Results Mean time to healing as shown on radiographs and mean time to return to full activity after surgery were 7.3 and 7.5 weeks, respectively. All patients were able to return to their previous levels of activity. There were no reports of union delay, nonunion or refracture to date. Conclusion In our patients, cannulated screw fixation of proximal fifth metatarsal fractures was a reliable procedure with low morbidity associated that provided athletes a quick return to activity. Level of Evidence I, Case Series. PMID:24453614

  13. 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.

  14. Outpatient percutaneous screw fixation of the acute Jones fracture.

    PubMed

    Mindrebo, N; Shelbourne, K D; Van Meter, C D; Rettig, A C

    1993-01-01

    Nine patients (8 men and 1 woman, ranging in age from 17 to 22 years) who sustained a Jones fracture were treated with percutaneous intramedullary screw fixation as outpatients. All of the patients were varsity athletes. Seven were Division I scholarship athletes. Beginning at 7 to 10 days after surgery, all patients were allowed weightbearing as tolerated with a CAM walker. Stationary bicycling, swimming, and Stairmaster were allowed at 2 to 3 weeks. The average return to running was 5.5 weeks (range, 3 to 10). The average return to full competition was 8.5 weeks (range, 7 to 12). No perioperative or postoperative complications occurred. Average followup was 2.5 years. All fractures attained clinical and radiographic union. We believe that outpatient percutaneous intramedullary screw fixation of the acute Jones fracture is a reasonable alternative for those active patients who would have difficulty with a non-weightbearing cast and crutches or who desire an expeditious return to activities. Time restraints are particularly critical for in-season or preseason athletes. With the outpatient screw fixation method, our patient population had predictable healing, and they returned to full sports participation within 12 weeks.

  15. Bioremediation: When is augmentation needed?

    SciTech Connect

    Forsyth, J.V.; Tsao, Y.M.; Bleam, R.D.

    1995-12-31

    Each contaminated site exhibits different characteristics and requires a site-specific remediation plan. The decontamination of a hazardous materials site is a complex procedure involving systematic, step-by-step problem solving. Assessing the conditions necessary to optimize the efficiency of microbial systems in degrading environmental pollutants and the economics required is essential in selecting and implementing cost-effective biotreatment. This assessment requires a good understanding of the microorganisms themselves. A firm grasp of the conditions under which the appropriate mixed culture system can be established and maintained to achieve the desired biodegradation tasks is necessary. The final component, and perhaps the most critical, is the translation of the scientific data into cost-effective full-scale cleanup processes. Augmentation with proven contaminant-degrading microorganisms leads to a higher degree of confidence in remediation success, and for certain sites has been shown to save time and money over alternative approaches.

  16. LOFT Augmented Operator Capability Program

    SciTech Connect

    Hollenbeck, D.A.; Krantz, E.A.; Hunt, G.L.; Meyer, O.R.

    1980-01-01

    The outline of the LOFT Augmented Operator Capability Program is presented. This program utilizes the LOFT (Loss-of-Fluid Test) reactor facility which is located at the Idaho National Engineering Laboratory and the LOFT operational transient experiment series as a test bed for methods of enhancing the reactor operator's capability for safer operation. The design of an Operational Diagnotics and Display System is presented which was backfit to the existing data acquisition computers. Basic color-graphic displays of the process schematic and trend type are presented. In addition, displays were developed and are presented which represent safety state vector information. A task analysis method was applied to LOFT reactor operating procedures to test its usefulness in defining the operator's information needs and workload.

  17. CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROPERTIES: Shielding Effect and Emission Criterion of a Screw Dislocation Near an Interfacial Crisscross Crack

    NASA Astrophysics Data System (ADS)

    Song, Hao-Peng; Fang, Qi-Hong; Liu, You-Wen

    2010-04-01

    Shielding effect and emission criterion of a screw dislocation near an interfacial crisscross crack are dealt with in this paper. Utilizing the conformal mapping technique, the closed-form solutions are derived for complex potentials and stress fields due to a screw dislocation located near the interfacial crisscross crack. The stress intensity factor on the crack tips and the critical stress intensity factor for dislocation emission are also calculated. The influence of the orientation of the dislocation and the morphology of the crisscross crack as well as the material elastic dissimilarity on the shielding effect and the emission criterion is discussed in detail. The results show that positive screw dislocations can reduce the stress intensity factor of the interfacial crisscross crack tip (shielding effect). The shielding effect increases with the increase of the shear modulus of the lower half-plane, but it decreases with the increase of the dislocation azimuth angle and the distance between the dislocation and the crack tip. The critical loads at infinity for dislocation emission increases with the increase of emission angle and the vertical length of the crisscross crack, and the most probable angle for screw dislocation emission is zero. The present solutions contain previous results as special cases.

  18. Sensory Augmentation for the Blind

    PubMed Central

    Kärcher, Silke M.; Fenzlaff, Sandra; Hartmann, Daniela; Nagel, Saskia K.; König, Peter

    2012-01-01

    Common navigational aids used by blind travelers during large-scale navigation divert attention away from important cues of the immediate environment (i.e., approaching vehicles). Sensory augmentation devices, relying on principles similar to those at work in sensory substitution, can potentially bypass the bottleneck of attention through sub-cognitive implementation of a set of rules coupling motor actions with sensory stimulation. We provide a late blind subject with a vibrotactile belt that continually signals the direction of magnetic north. The subject completed a set of behavioral tests before and after an extended training period. The tests were complemented by questionnaires and interviews. This newly supplied information improved performance on different time scales. In a pointing task we demonstrate an instant improvement of performance based on the signal provided by the device. Furthermore, the signal was helpful in relevant daily tasks, often complicated for the blind, such as keeping a direction over longer distances or taking shortcuts in familiar environments. A homing task with an additional attentional load demonstrated a significant improvement after training. The subject found the directional information highly expedient for the adjustment of his inner maps of familiar environments and describes an increase in his feeling of security when exploring unfamiliar environments with the belt. The results give evidence for a firm integration of the newly supplied signals into the behavior of this late blind subject with better navigational performance and more courageous behavior in unfamiliar environments. Most importantly, the complementary information provided by the belt lead to a positive emotional impact with enhanced feeling of security. The present experimental approach demonstrates the positive potential of sensory augmentation devices for the help of handicapped people. PMID:22403535

  19. Tomographic analysis for C2 screw placement in rheumatoid arthritis patients

    PubMed Central

    Astolfi, Rodrigo Schroll; Tachibana, Wilson Tadao; Letaif, Olavo Biraghi; Cristante, Alexandre Fogaça; Oliveira, Reginaldo Perilo; de Barros Filho, Tarcísio Eloy Pessoa

    2012-01-01

    Objective A morphological analysis of the bone structure of C2 in patients with rheumatoid arthritis in order to enhance the security of the stabilization procedures for this vertebra. Methods We retrospectively analyzed 20 CT scans of the cervical spine performed in patients with rheumatoid arthritis; the following parameters were measured: spinolaminar angle, thickness and length of C2 lamina. Results The mean values are: 5.92mm and 5.87mm for thickness of right and left laminae retrospectively, 27.75mm for right lamina length and 27.94mm for left lamina length, and 44.7º for spinolaminar angle. Conclusion The values obtained are consistent with studies in normal subjects published by other groups, with no apparent need for change in the screw placement technique. Level of Evidence IV, Case Series. PMID:24453603

  20. Trans-sacral screw fixation in the treatment of high dyplastic developmental spondylolisthesis

    PubMed Central

    Landi, Alessandro; Marotta, Nicola; Mancarella, Cristina; Tarantino, Roberto; Delfini, Roberto

    2013-01-01

    We describe the case of a 67-year-old woman with L5-S1 ontogenetic spondylolisthesis treated with pedicle fixation associated with interbody arthrodesis performed with S1-L5 trans-sacral screwing according to the technique of Bartolozzi. The procedure was followed by a wide decompressive laminectomy. The patient had a progressive improvement of the symptoms which gradually disappeared in 12 mo. The radiograph at 6 and 12 mo showed complete fusion system. The choice of treatment in L5-S1 ontogenetic spondylolithesis is related to a correct clinical and diagnostic planning (X-ray, computer tomography magnetic resonance imaging, Measurement). In particular, the severity index and the square of unstable zone, and the standard measurements already described in the literature, are important to understand and to plane the correct surgical strategy, that require, in most of the times, fusion and interbody artrodesis. PMID:24303480

  1. Trans-sacral screw fixation in the treatment of high dyplastic developmental spondylolisthesis.

    PubMed

    Landi, Alessandro; Marotta, Nicola; Mancarella, Cristina; Tarantino, Roberto; Delfini, Roberto

    2013-06-16

    We describe the case of a 67-year-old woman with L5-S1 ontogenetic spondylolisthesis treated with pedicle fixation associated with interbody arthrodesis performed with S1-L5 trans-sacral screwing according to the technique of Bartolozzi. The procedure was followed by a wide decompressive laminectomy. The patient had a progressive improvement of the symptoms which gradually disappeared in 12 mo. The radiograph at 6 and 12 mo showed complete fusion system. The choice of treatment in L5-S1 ontogenetic spondylolithesis is related to a correct clinical and diagnostic planning (X-ray, computer tomography magnetic resonance imaging, Measurement). In particular, the severity index and the square of unstable zone, and the standard measurements already described in the literature, are important to understand and to plane the correct surgical strategy, that require, in most of the times, fusion and interbody artrodesis.

  2. Flashback Detection Sensor for Hydrogen Augmented Natural Gas Combustion

    SciTech Connect

    Thornton, J.D.; Chorpening, B.T.; Sidwell, T.; Strakey, P.A.; Huckaby, E.D.; Benson, K.J.

    2007-05-01

    The use of hydrogen augmented fuel is being investigated by various researchers as a method to extend the lean operating limit, and potentially reduce thermal NOx formation in natural gas fired lean premixed (LPM) combustion systems. The resulting increase in flame speed during hydrogen augmentation, however, increases the propensity for flashback in LPM systems. Real-time in-situ monitoring of flashback is important for the development of control strategies for use of hydrogen augmented fuel in state-of-the-art combustion systems, and for the development of advanced hydrogen combustion systems. The National Energy Technology Laboratory (NETL) and Woodward Industrial Controls are developing a combustion control and diagnostics sensor (CCADS), which has already been demonstrated as a useful sensor for in-situ monitoring of natural gas combustion, including detection of important combustion events such as flashback and lean blowoff. Since CCADS is a flame ionization sensor technique, the low ion concentration produced in pure hydrogen combustion raises concerns of whether CCADS can be used to monitor flashback in hydrogen augmented combustion. This paper discusses CCADS tests conducted at 0.2-0.6 MPa (2-6 atm), demonstrating flashback detection with fuel compositions up to 80% hydrogen (by volume) mixed with natural gas. NETL’s Simulation Validation (SimVal) combustor offers full optical access to pressurized combustion during these tests. The CCADS data and high-speed video show the reaction zone moves upstream into the nozzle as the hydrogen fuel concentration increases, as is expected with the increased flame speed of the mixture. The CCADS data and video also demonstrate the opportunity for using CCADS to provide the necessary in-situ monitor to control flashback and lean blowoff in hydrogen augmented combustion applications.

  3. Augmented Reality for Close Quarters Combat

    ScienceCinema

    None

    2016-07-12

    Sandia National Laboratories has developed a state-of-the-art augmented reality training system for close-quarters combat (CQB). This system uses a wearable augmented reality system to place the user in a real environment while engaging enemy combatants in virtual space (Boston Dynamics DI-Guy). Umbra modeling and simulation environment is used to integrate and control the AR system.

  4. Status report of RMS active damping augmentation

    NASA Technical Reports Server (NTRS)

    Gilbert, Mike; Demeo, Martha E.

    1993-01-01

    A status report of Remote Manipulator System (RMS) active damping augmentation is presented. Topics covered include: active damping augmentation; benefits of RMS ADA; simulated payload definition; sensor and actuator definition; ADA control law design; Shuttle Engineering Simulator (SES) real-time simulation; and astronaut evaluation.

  5. From Augmentation Media to Meme Media.

    ERIC Educational Resources Information Center

    Tanaka, Yuzuru

    Computers as meta media are now evolving from augmentation media vehicles to meme media vehicles. While an augmentation media system provides a seamlessly integrated environment of various tools and documents, meme media system provides further functions to edit and distribute tools and documents. Documents and tools on meme media can easily…

  6. Enhancing Education through Mobile Augmented Reality

    ERIC Educational Resources Information Center

    Joan, D. R. Robert

    2015-01-01

    In this article, the author has discussed about the Mobile Augmented Reality and enhancing education through it. The aim of the present study was to give some general information about mobile augmented reality which helps to boost education. Purpose of the current study reveals the mobile networks which are used in the institution campus as well…

  7. Embedding Augmentative Communication within Early Childhood Classrooms.

    ERIC Educational Resources Information Center

    DiCarlo, Cynthia; Banajee, Meher; Stricklin, Sarintha Buras

    2000-01-01

    This article first describes various augmentative communication systems including sign language, picture symbols, and voice output communication devices. It then explains ways to embed augmentative communication within four types of early childhood classroom activities: (1) special or planned activities, (2) meal time, (3) circle time, and (4)…

  8. Age grouping to optimize augmentation success.

    PubMed

    Gordon, Robert W

    2010-05-01

    This article has described the different age groups that present for noninvasive injectable lip and perioral augmentation, as well as the breakdown of 3 subgroups that present within the 4 general age groups. With the fundamental understanding of these presenting groups and subgroups, the practicing augmenter will be able to better treatment plan and educate the patient on realistic and optimal aesthetic outcomes.

  9. Nonsteady-Flow Thrust Augmenting Ejectors

    NASA Technical Reports Server (NTRS)

    Foa, J. V.

    1979-01-01

    Ejector augmenters in which the transfer of mechanical energy from the primary to the secondary flow takes place through the work of interface pressure forces are investigated. Nonsteady flow processes are analyzed from the standpoint of energy transfer efficiency and a comparison of a rotary jet augmenter to an ejector is presented.

  10. Augmented Reality for Close Quarters Combat

    SciTech Connect

    2013-09-20

    Sandia National Laboratories has developed a state-of-the-art augmented reality training system for close-quarters combat (CQB). This system uses a wearable augmented reality system to place the user in a real environment while engaging enemy combatants in virtual space (Boston Dynamics DI-Guy). Umbra modeling and simulation environment is used to integrate and control the AR system.

  11. Rabbit maxillary sinus augmentation model with simultaneous implant placement: differential responses to the graft materials

    PubMed Central

    Kim, Young-Sung; Kim, Su-Hwan; Kim, Kyoung-Hwa; Jhin, Min-Ju; Kim, Won-Kyung; Lee, Young-Kyoo; Seol, Yang-Jo

    2012-01-01

    Purpose This study was performed to establish an experimental rabbit model for single-stage maxillary sinus augmentation with simultaneous implant placement. Methods Twelve mature New Zealand white rabbits were used for the experiments. The rabbit maxillary sinuses were divided into 3 groups according to sinus augmentation materials: blood clot (BC), autogenous bone (AB), and bovine-derived hydroxyapatite (BHA). Small titanium implants were simultaneously placed in the animals during the sinus augmentation procedure. The rabbits were sacrificed 4 and 8 weeks after surgery and were observed histologically. Histomorphometric analyses using image analysis software were also performed to evaluate the parameters related to bone regeneration and implant-bone integration. Results The BC group showed an evident collapse of the sinus membrane and limited new bone formation around the original sinus floor at 4 and 8 weeks. In the AB group, the sinus membrane was well retained above the implant apex, and new bone formation was significant at both examination periods. The BHA group also showed retention of the elevated sinus membrane above the screw apex and evident new bone formation at both points in time. The total area of the mineral component (TMA) in the area of interest and the bone-to-implant contact did not show any significant differences among all the groups. In the AB group, the TMA had significantly decreased from 4 to 8 weeks. Conclusions Within the limits of this study, the rabbit sinus model showed satisfactory results in the comparison of different grafting conditions in single-stage sinus floor elevation with simultaneous implant placement. We found that the rabbit model was useful for maxillary sinus augmentation with simultaneous implant placement. PMID:23346463

  12. Thoracic Aortic Stent-Graft Placement for Safe Removal of a Malpositioned Pedicle Screw

    SciTech Connect

    Hu Hongtao; Shin, Ji Hoon Hwang, Jae-Yeon; Cho, Young Jun; Ko, Gi-Young; Yoon, Hyun-Ki

    2010-10-15

    We describe a case of percutaneous placement of a thoracic aortic stent-graft for safe removal of a malpositioned pedicle screw in a 52-year-old man. The patient had undergone posterior thoracic spinal instrumentation for pyogenic spondylitis and spinal deformity 8 months previously. Follow-up CT images showed a malpositioned pedicle screw which was abutting the thoracic aorta at the T5 level. After percutaneous stent-graft placement, the malpositioned pedicle screw was safely and successfully removed.

  13. A Novel Blasted and Grooved Low Profile Pedicle Screw Able to Resist High Compression Bending Loads

    PubMed Central

    Kim, Young-Sung; Choi, Hong-June; Kim, Kyung-Hyun; Park, Jeong-Yoon; Jeong, Hyun-Yong; Chin, Dong-Kyu; Kim, Keun-Su; Yoon, Young-Sul; Lee, Yoon-Chul; Cho, Yong-Eun

    2012-01-01

    Objective Polyaxial pedicle screws are a safe, useful adjunct to transpedicular fixation. However, the large screw head size can cause soft tissue irritation, high rod positioning, and facet joint injury. However, the mechanical resistance provided by small and low profile pedicle screws is very limited. We therefore developed a novel, low profile pedicle screw using grooving and blasting treatment that is able to resist a high compression bending load. Methods We evaluated the compression bending force to displacement and yield loads for seven different screw head types that differed with regard to their groove intervals and whether or not they had been blasted. Results The rank order of screw types that had the greatest compression bending force to displacement was as follows: (1) universal polyaxial, (2) low polyaxial with 0.1mm grooves and blasting, (3) low polyaxial with blasting, (4) low polyaxial with 0.15mm grooves and blasting, (5) low polyaxial with 0.05mm grooves and blasting, (6) low polyaxial with 0.05mm grooves, (7) and low polyaxial. Low polyaxial screws with 0.1mm grooves and blasting had the maximum yield load and highest compression bending force to displacement of all seven polyaxial screw head systems evaluated. Conclusion Blasting and grooving treatment of pedicle screw heads resulted in screw heads with a high yield load and compression bending force relative to displacement because of increased friction. Low polyaxial pedicle screws with 0.1 mm grooves treated by blasting have mechanical characteristics similar to those of universal polyaxial pedicle screws. PMID:25983790

  14. Irradiated homologous costal cartilage for augmentation rhinoplasty

    SciTech Connect

    Lefkovits, G. )

    1990-10-01

    Although the ideal reconstructive material for augmentation rhinoplasty continues to challenge plastic surgeons, there exists no report in the literature that confines the use of irradiated homologous costal cartilage, first reported by Dingman and Grabb in 1961, to dorsal nasal augmentation. The purpose of this paper is to present a retrospective analysis of the author's experience using irradiated homologous costal cartilage in augmentation rhinoplasty. Twenty-seven dorsal nasal augmentations were performed in 24 patients between 16 and 49 years of age with a follow-up ranging from 1 to 27 months. Good-to-excellent results were achieved in 83.3% (20 of 24). Poor results requiring revision were found in 16.7% (4 of 24). Complication rates included 7.4% infection (2 of 27) and 14.8% warping (4 of 27). The resorption rate was zero. These results compare favorably with other forms of nasal augmentation. Advantages and disadvantages of irradiated homologous costal cartilage are discussed.

  15. Performance of a self-augmented railgun

    NASA Astrophysics Data System (ADS)

    Burton, Rodney L.; Witherspoon, F. D.; Goldstein, Shyke A.

    1991-10-01

    The accelerating force of a railgun can be increased by augmenting the self-induced magnetic field created by the armature current. Augmentation fields can be produced by external current coils or, as is done here, by shorting the railgun muzzle, and using the gun rails as the augmentation coil. Experimental results are presented for a 3.6-m railgun operated in this self-augmented mode, and effective inductance gradients are achieved which are as much as 9.3 times that of the unaugmented gun. A circuit model is presented which explains features of the measured shunt current and voltage. It is concluded that self-augmentation is an effective way to reduce ohmic heating in the armature of a railgun.

  16. Experimental Reality: Principles for the Design of Augmented Environments

    NASA Astrophysics Data System (ADS)

    Lahlou, Saadi

    The Laboratory of Design for Cognition at EDF R&D (LDC) is a living laboratory, which we created to develop Augmented Environment (AE) for collaborative work, more specifically “cognitive work” (white collars, engineers, office workers). It is a corporate laboratory in a large industry, where natural activity of real users is observed in a continuous manner in various spaces (project space, meeting room, lounge, etc.) The RAO room, an augmented meeting room, is used daily for “normal” meetings; it is also the “mother room” of all augmented meeting rooms in the company, where new systems, services, and devices are tested. The LDC has gathered a unique set of data on the use of AE, and developed various observation and design techniques, described in this chapter. LDC uses novel techniques of digital ethnography, some of which were invented there (SubCam, offsat) and some of which were developed elsewhere and adapted (360° video, WebDiver, etc.). At LDC, some new theories have also been developed to explain behavior and guide innovation: cognitive attractors, experimental reality, and the triple-determination framework.

  17. Biomechanical Evaluation of Pedicle Screw-Based Dynamic Stabilization Devices for the Lumbar Spine: A Systematic Review

    PubMed Central

    Ponnappan, Ravi K.; Song, Jason; Vaccaro, Alexander R.

    2008-01-01

    Study Design This study is a systematic review of published biomechanical studies involving pedicle screw-based posterior dynamic stabilization devices (PDS) with a special focus on kinematics and load transmission through the functional spine unit (FSU). Methods A literature search was performed via the PubMed online database from 1990 to 2008 using the following key words: “biomechanics,” “lumbar dynamic stabilization,” “Graf system,” “Dynesys,” and “posterior dynamic implant.” Citations were limited to papers describing biomechanics of pedicle screw-based PDS devices currently available for clinical use. Studies describing clinical experience, radiology, and in vivo testing were excluded from the review. Parameters measured included kinematics of the FSU (range of motion (ROM), neutral zone (NZ), and location of the center of rotation) and load transmission through the disk, facets, and instrumentation. Results A total of 27 publications were found that concerned the biomechanical evaluation of lumbar pedicle screw-based dynamic stabilization instrumentation. Nine in vitro experimental studies and 4 finite element analyses satisfied the inclusion criteria. The Dynesys implant was the most investigated pedicle screw-based PDS system. In vitro cadaveric studies mainly focused on kinematics comparing ROM of intact versus instrumented spines whereas finite element analyses allowed analysis of load transmission at the instrumented and adjacent levels. Conclusion Biomechanical studies demonstrate that pedicle screw-based PDS devices limit intervertebral motion while unloading the intervertebral disk. The implant design and the surgical technique have a significant impact on the biomechanical behavior of the instrumented spinal segment. The posterior placement of such devices results in non-physiologic intervertebral kinematics with a posterior shift of the axis of rotation. Biomechanical studies suggest that the difference at the adjacent level

  18. A new material (single crystal sapphire screw) for internal fixation of the mandibular ramus.

    PubMed

    Iizuka, T; Fujimoto, H; Ono, T

    1987-02-01

    A new single crystal sapphire bone screw which has favourable properties such as chemical stability, mechanical strength and biocompatibility, was applied for rigid internal fixation of the sagittal split osteotomies in 86 cases since 1982. Radiographic findings supported the excellent biocompatibility of the material; there was no noticeable bone loss around the screw and the excellent bone adaptation to the threaded portion was observed. The screws can mechanically support the split mandibular rami until bone union occurs. Complications due to the screw were not encountered in follow-up periods of 0.5-3.5 years.

  19. 100 Consecutive Cases of Degenerative Lumbar Conditions Using a Non-Threaded Locking Screw System With a 90-Degree Locking Cap

    PubMed Central

    Cunningham, Bryan W.; Tortolani, P. Justin; Fedder, Ira L.; Sefter, John C.; Davis, Charles

    2009-01-01

    Background This prospective study analyzes the perioperative outcomes and long-term fusion success of 100 consecutive lumbar degenerative cases. The cases were managed using a non-threaded locking screw system, in conjunction with polyetheretherketone (PEEK) cages, for posterior lumbar interbody fusion (PLIF) procedures. These 100 cases were compared to another prospective study treating patients with the same inclusion and exclusion criteria using conventional plate-based pedicle screw spinal instrumentation augmented with carbon fiber interbody cages. Methods A total of 167 operative levels were treated in 100 patients (51 single-level, 39 two-level and 10 three-level cases). Eleven cases were revisions and 67 patients received interbody fusion cages. Patients had an average of 22.8 ± 4.0 months followup. Results: There was one instrumentation failure but no significant subsidence at the interbody fusion level. The disc space height was restored as part of the surgical procedure at the interbody cage levels: from 7.5 ± 2.3 mm preoperative to 9.0 ± 2.1 mm postoperative. There were 2 cases of pseudarthrosis (2 / 100 = 2%). The average operative time for 1-level cases was 111 ± 25 minutes; for 2-level cases it was 132.4 ± 21.8 minutes; and for 3-level cases it was 162.6 ± 33 minutes. Blood loss averaged 800 ± 473 cc for 1-level cases, 1055 ± 408 cc for 2 levels, and 1155 ± 714 cc for 3 levels. The length of stay was similar between the 3 groups (4.4 ± 1.2 days for single-level cases, 4.7 ± 1.1 for 2 levels, and 5.0 ± 1.1 for 3 levels; P > .05). There were 3 incidental durotomies, and 4 other patients developed infections postoperatively that required reoperation. Conclusion The disc and foraminal heights can be restored and maintained with a unilateral cage and pedicle screw construct. Unilateral transforaminal lumbar interbody fusion using a PEEK cage combined with a non-threaded locking pedicle screw and rod system results in similar fusion rates to

  20. Phase diversity and polarization augmented techniques for active imaging

    NASA Astrophysics Data System (ADS)

    Johnson, Peter M.

    A firm understanding of the space environment is necessary to defend US access to space-based systems. Conventional imaging systems have been developed to gather information on space-based objects, but they are incapable of imaging objects in the earth's shadow. In order close this gap in imaging-system coverage, an active-illumination based approach must be used. To facilitate this, a multi-frame active phase diversity imaging (APDI) algorithm is derived and demonstrated for the statistics of coherent light. In addition to conventional focal-plane and diversity-plane data, a statistical description for the pupil plane intensity distribution is formed and included in the derivation. The algorithm is implemented and characterized using a Monte Carlo approach. Analysis shows that the algorithm is robust, that the effect of system configuration on optimal algorithm parameters is minimal, that the algorithm is insensitive to detection noise for SNR ≥ 7, and that it performs well for SNRs as low as 2. Furthermore, it's shown that introduction of pupil-plane data on average results in a 60% better image reconstruction from dynamically aberrated data than is obtained using only focal-plane and diversity-plane data. Both an Expectation-Maximization algorithm and a lensless-APDI approach are presented for generating imagery directly from pupil-plane polarization measurements. Shortfalls of these methods and areas worthy of further consideration are identified. The use of pupil-plane polarization state measurements in place of pupil-plane intensity measurements in the APDI algorithm is explored. A framework for including polarization measurements into the APDI algorithm is demonstrated, and an initial statistical model and results are presented. Under the developed implementation, introduction of the polarization data doesn't result in better performance. Areas that may result in better reconstructions are discussed.

  1. Spacecraft 3D Augmented Reality Mobile App

    NASA Technical Reports Server (NTRS)

    Hussey, Kevin J.; Doronila, Paul R.; Kumanchik, Brian E.; Chan, Evan G.; Ellison, Douglas J.; Boeck, Andrea; Moore, Justin M.

    2013-01-01

    The Spacecraft 3D application allows users to learn about and interact with iconic NASA missions in a new and immersive way using common mobile devices. Using Augmented Reality (AR) techniques to project 3D renditions of the mission spacecraft into real-world surroundings, users can interact with and learn about Curiosity, GRAIL, Cassini, and Voyager. Additional updates on future missions, animations, and information will be ongoing. Using a printed AR Target and camera on a mobile device, users can get up close with these robotic explorers, see how some move, and learn about these engineering feats, which are used to expand knowledge and understanding about space. The software receives input from the mobile device's camera to recognize the presence of an AR marker in the camera's field of view. It then displays a 3D rendition of the selected spacecraft in the user's physical surroundings, on the mobile device's screen, while it tracks the device's movement in relation to the physical position of the spacecraft's 3D image on the AR marker.

  2. Use of a continuous twin screw granulation and drying system during formulation development and process optimization.

    PubMed

    Vercruysse, J; Peeters, E; Fonteyne, M; Cappuyns, P; Delaet, U; Van Assche, I; De Beer, T; Remon, J P; Vervaet, C

    2015-01-01

    Since small scale is key for successful introduction of continuous techniques in the pharmaceutical industry to allow its use during formulation development and process optimization, it is essential to determine whether the product quality is similar when small quantities of materials are processed compared to the continuous processing of larger quantities. Therefore, the aim of this study was to investigate whether material processed in a single cell of the six-segmented fluid bed dryer of the ConsiGma™-25 system (a continuous twin screw granulation and drying system introduced by GEA Pharma Systems, Collette™, Wommelgem, Belgium) is predictive of granule and tablet quality during full-scale manufacturing when all drying cells are filled. Furthermore, the performance of the ConsiGma™-1 system (a mobile laboratory unit) was evaluated and compared to the ConsiGma™-25 system. A premix of two active ingredients, powdered cellulose, maize starch, pregelatinized starch and sodium starch glycolate was granulated with distilled water. After drying and milling (1000 μm, 800 rpm), granules were blended with magnesium stearate and compressed using a Modul™ P tablet press (tablet weight: 430 mg, main compression force: 12 kN). Single cell experiments using the ConsiGma™-25 system and ConsiGma™-1 system were performed in triplicate. Additionally, a 1h continuous run using the ConsiGma™-25 system was executed. Process outcomes (torque, barrel wall temperature, product temperature during drying) and granule (residual moisture content, particle size distribution, bulk and tapped density, hausner ratio, friability) as well as tablet (hardness, friability, disintegration time and dissolution) quality attributes were evaluated. By performing a 1h continuous run, it was detected that a stabilization period was needed for torque and barrel wall temperature due to initial layering of the screws and the screw chamber walls with material. Consequently, slightly deviating

  3. Use of a continuous twin screw granulation and drying system during formulation development and process optimization.

    PubMed

    Vercruysse, J; Peeters, E; Fonteyne, M; Cappuyns, P; Delaet, U; Van Assche, I; De Beer, T; Remon, J P; Vervaet, C

    2015-01-01

    Since small scale is key for successful introduction of continuous techniques in the pharmaceutical industry to allow its use during formulation development and process optimization, it is essential to determine whether the product quality is similar when small quantities of materials are processed compared to the continuous processing of larger quantities. Therefore, the aim of this study was to investigate whether material processed in a single cell of the six-segmented fluid bed dryer of the ConsiGma™-25 system (a continuous twin screw granulation and drying system introduced by GEA Pharma Systems, Collette™, Wommelgem, Belgium) is predictive of granule and tablet quality during full-scale manufacturing when all drying cells are filled. Furthermore, the performance of the ConsiGma™-1 system (a mobile laboratory unit) was evaluated and compared to the ConsiGma™-25 system. A premix of two active ingredients, powdered cellulose, maize starch, pregelatinized starch and sodium starch glycolate was granulated with distilled water. After drying and milling (1000 μm, 800 rpm), granules were blended with magnesium stearate and compressed using a Modul™ P tablet press (tablet weight: 430 mg, main compression force: 12 kN). Single cell experiments using the ConsiGma™-25 system and ConsiGma™-1 system were performed in triplicate. Additionally, a 1h continuous run using the ConsiGma™-25 system was executed. Process outcomes (torque, barrel wall temperature, product temperature during drying) and granule (residual moisture content, particle size distribution, bulk and tapped density, hausner ratio, friability) as well as tablet (hardness, friability, disintegration time and dissolution) quality attributes were evaluated. By performing a 1h continuous run, it was detected that a stabilization period was needed for torque and barrel wall temperature due to initial layering of the screws and the screw chamber walls with material. Consequently, slightly deviating

  4. Wireless Augmented Reality Prototype (WARP)

    NASA Technical Reports Server (NTRS)

    Devereaux, A. S.

    1999-01-01

    Initiated in January, 1997, under NASA's Office of Life and Microgravity Sciences and Applications, the Wireless Augmented Reality Prototype (WARP) is a means to leverage recent advances in communications, displays, imaging sensors, biosensors, voice recognition and microelectronics to develop a hands-free, tetherless system capable of real-time personal display and control of computer system resources. Using WARP, an astronaut may efficiently operate and monitor any computer-controllable activity inside or outside the vehicle or station. The WARP concept is a lightweight, unobtrusive heads-up display with a wireless wearable control unit. Connectivity to the external system is achieved through a high-rate radio link from the WARP personal unit to a base station unit installed into any system PC. The radio link has been specially engineered to operate within the high- interference, high-multipath environment of a space shuttle or space station module. Through this virtual terminal, the astronaut will be able to view and manipulate imagery, text or video, using voice commands to control the terminal operations. WARP's hands-free access to computer-based instruction texts, diagrams and checklists replaces juggling manuals and clipboards, and tetherless computer system access allows free motion throughout a cabin while monitoring and operating equipment.

  5. Augmented reality: past, present, future

    NASA Astrophysics Data System (ADS)

    Inzerillo, Laura

    2013-03-01

    A great opportunity has permitted to carry out a cultural, historical, architectural and social research with great impact factor on the international cultural interest. We are talking about the realization of a museum whose the main theme is the visit and the discovery of a monument of great prestige: the monumental building the "Steri" in Palermo. The museum is divided into sub themes including the one above all, that has aroused the international interest so much that it has been presented the instance to include the museum in the cultural heritage of UNESCO. It is the realization of a museum path that regards the cells of the Inquisition, which are located just inside of some buildings of the monumental building. The project, as a whole, is faced, in a total view, between the various competences implicated: historic, chemic, architectonic, topographic, drawing, representation, virtual communication, informatics. The birth of the museum will be a sum of the results of all these disciplines involved. Methodology, implementation, fruition, virtual museum, goals, 2D graphic restitution, effects on the cultural heritage and landscape environmental, augmented reality, Surveying 2D and 3D, hi-touch screen, Photogrammetric survey, Photographic survey, representation, drawing 3D and more than this has been dealt with this research.

  6. Augmented reality in surgical procedures

    NASA Astrophysics Data System (ADS)

    Samset, E.; Schmalstieg, D.; Vander Sloten, J.; Freudenthal, A.; Declerck, J.; Casciaro, S.; Rideng, Ø.; Gersak, B.

    2008-02-01

    Minimally invasive therapy (MIT) is one of the most important trends in modern medicine. It includes a wide range of therapies in videoscopic surgery and interventional radiology and is performed through small incisions. It reduces hospital stay-time by allowing faster recovery and offers substantially improved cost-effectiveness for the hospital and the society. However, the introduction of MIT has also led to new problems. The manipulation of structures within the body through small incisions reduces dexterity and tactile feedback. It requires a different approach than conventional surgical procedures, since eye-hand co-ordination is not based on direct vision, but more predominantly on image guidance via endoscopes or radiological imaging modalities. ARIS*ER is a multidisciplinary consortium developing a new generation of decision support tools for MIT by augmenting visual and sensorial feedback. We will present tools based on novel concepts in visualization, robotics and haptics providing tailored solutions for a range of clinical applications. Examples from radio-frequency ablation of liver-tumors, laparoscopic liver surgery and minimally invasive cardiac surgery will be presented. Demonstrators were developed with the aim to provide a seamless workflow for the clinical user conducting image-guided therapy.

  7. Postauricular fascia in augmentation rhinoplasty.

    PubMed

    Guerra, Aldo Benjamin

    2014-06-01

    Ten rhinoplasty operations performed using postauricular fascia for the purpose of augmenting the radix and dorsum of the nose were analyzed retrospectively. All the operations were performed over a 1-year period, between 2005 and 2006. The fascia of the postauricular area has been used as a source of pliable soft-tissue grafts in primary and revision rhinoplasty. It may be easily accessed using a single sulcus incision that also enables harvesting of ear cartilage grafts. Deficiency in the radix is an overlooked abnormality seen in many patients undergoing primary as well as revision rhinoplasty after aggressive hump removal. Recent trends in rhinoplasty have been to avoid the overly reduced nasal skeleton and to create a more balanced nasal surgery result. This article presents the use of the postauricular fascia as a radix graft that has been found to be simple to carry out, reliable, and long lasting. In addition, the fascia graft is useful in the camouflage of various nasal deformities in the dorsum and sidewalls. The average patient follow-up for the study was 24 months.

  8. Ionospheric Challenges for GNSS Based Augmentation Systems

    NASA Astrophysics Data System (ADS)

    Doherty, P.; Valladares, C. E.

    2007-12-01

    The ionosphere is a highly dynamic physical phenomenon that presents a variable source of error for Global Navigation Satellite System (GNSS) signals and GNSS based operational systems. The Federal Aviation Administration's (FAA) Wide-Area Augmentation System (WAAS) was designed to enhance the GNSS standard positioning service by providing additional accuracy, availability and integrity that is sufficient for use in commercial aviation. It is the first of a number of planned regional Satellite Based Augmentation Systems (SBAS). Other systems in development include the European EGNOS system, the MSAS system in Japan and the GAGAN system in India. In addition, the South American countries are investigating the feasibility of operating an SBAS system in this region. Much of the WAAS ionospheric research and development focused on defining and mitigating ionospheric challenges characteristic of the mid-latitude regions, where the ionosphere is well studied and relatively quiescent. The EGNOS and MSAS systems will primarily operate under a similarly quiescent mid-latitude ionosphere. SBAS system development in South America, India and other low-latitude regions, however, will have to contend with much more extreme conditions. These conditions include strong spatial and temporal gradients, plasma depletions and scintillation. All of these conditions have a potential to limit SBAS performance in the low latitude regions. This presentation will review the effects that the ionosphere has on the mid-latitude WAAS system. It will present the techniques that are used to mitigate ionospheric disturbances induced on the system during severe geomagnetic activity and it will quantify the effect that this activity has on system performance. The presentation will then present data from the South American Low-latitude Ionospheric Sensor Network (LISN) that can be used to infer the ionospheric effects on SBAS performance in the most challenging low-latitude ionospheric environment

  9. Augmented robotic device for EVA hand manoeuvres

    NASA Astrophysics Data System (ADS)

    Matheson, Eloise; Brooker, Graham

    2012-12-01

    During extravehicular activities (EVAs), pressurised space suits can lead to difficulties in performing hand manoeuvres and fatigue. This is often the cause of EVAs being terminated early, or taking longer to complete. Assistive robotic gloves can be used to augment the natural motion of a human hand, meaning work can be carried out more efficiently with less stress to the astronaut. Lightweight and low profile solutions must be found in order for the assistive robotic glove to be easily integrated with a space suit pressure garment. Pneumatic muscle actuators combined with force sensors are one such solution. These actuators are extremely light, yet can output high forces using pressurised gases as the actuation drive. Their movement is omnidirectional, so when combined with a flexible exoskeleton that itself provides a degree of freedom of movement, individual fingers can be controlled during flexion and extension. This setup allows actuators and other hardware to be stored remotely on the user's body, resulting in the least possible mass being supported by the hand. Two prototype gloves have been developed at the University of Sydney; prototype I using a fibreglass exoskeleton to provide flexion force, and prototype II using torsion springs to achieve the same result. The gloves have been designed to increase the ease of human movements, rather than to add unnatural ability to the hand. A state space control algorithm has been developed to ensure that human initiated movements are recognised, and calibration methods have been implemented to accommodate the different characteristics of each wearer's hands. For this calibration technique, it was necessary to take into account the natural tremors of the human hand which may have otherwise initiated unexpected control signals. Prototype I was able to actuate the user's hand in 1 degree of freedom (DOF) from full flexion to partial extension, and prototype II actuated a user's finger in 2 DOF with forces achieved

  10. Augmentation of femoral neck fracture fixation with an injectable calcium-phosphate bone mineral cement.

    PubMed

    Stankewich, C J; Swiontkowski, M F; Tencer, A F; Yetkinler, D N; Poser, R D

    1996-09-01

    The first goal of this study was to determine if augmentation with an injectable, in situ setting, calcium-phosphate cement that is capable of being remodeled and was designed to mimic bone mineral significantly improved the strength and stiffness of fixation in a cadaveric femoral neck fracture model. The second goal was to determine if greater increases in fixation strength were achieved as the bone density of the specimen decreased. Sixteen pairs of fresh cadaveric human femora with a mean age of 70.9 years (SD = 17.2 years) were utilized. The bone density of the femoral neck was measured with dual-energy x-ray absorptiometry. The femoral head was impacted vertically with the femoral shaft fixed in 12 degrees of adduction using a materials testing machine to create a fully displaced fracture. Following fracture, 30% inferior comminution was created in each specimen. One randomly chosen femur from each pair underwent anatomic reduction and fixation with three cannulated cancellous bone screws, 7 mm in diameter, in an inverted triangle configuration. The contralateral femur underwent the same fixation augmented with calcium-phosphate cement. Specimens were preconditioned followed by 1.000 cycles to one body weight (611.6 N) at 0.5 Hz to simulate single-limb stance loading. The stiffness in the first cycle was observed to be significantly greater in cement-augmented specimens compared with unaugmented controls (p < 0.05). After cycling, each specimen was loaded at 10 mm/min until complete displacement of the fracture surface and failure of fixation occurred. Specimens augmented with bone mineral cement failed at a mean of 4,573 N (SD = 1,243 N); this was significantly greater (p < 0.01) than the mean for controls (3,092 N, SD = 1,258 N). The relative improvement in fixation strength (augmented/control x 100%) was not inversely correlated to femoral neck bone density (p = 0.25, R2 = 0.09), was weakly correlated to the volume of cement injected (p = 0.07, R2 = 0

  11. 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.

  12. 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

  13. Comparison of success rates of orthodontic mini-screws by the insertion method

    PubMed Central

    Kim, Jung Suk; Choi, Seong Hwan; Cha, Sang Kwon; Kim, Jang Han; Lee, Hwa Jin; Yeom, Sang Seon

    2012-01-01

    Objective The aim of this study was to compare the success rates of the manual and motor-driven mini-screw insertion methods according to age, gender, length of mini-screws, and insertion sites. Methods We retrospectively reviewed 429 orthodontic mini-screw placements in 286 patients (102 in men and 327 in women) between 2005 and 2010 at private practice. Age, gender, mini-screw length, and insertion site were cross-tabulated against the insertion methods. The Cochran-Mantel-Haenszel test was performed to compare the success rates of the 2 insertion methods. Results The motor-driven method was used for 228 mini-screws and the manual method for the remaining 201 mini-screws. The success rates were similar in both men and women irrespective of the insertion method used. With respect to mini-screw length, no difference in success rates was found between motor and hand drivers for the 6-mm-long mini-screws (68.1% and 69.5% with the engine driver and hand driver, respectively). However, the 8-mm-long mini-screws exhibited significantly higher success rates (90.4%, p < 0.01) than did the 6-mm-long mini-screws when placed with the engine driver. The overall success rate was also significantly higher in the maxilla (p < 0.05) when the engine driver was used. Success rates were similar among all age groups regardless of the insertion method used. Conclusions Taken together, the motor-driven insertion method can be helpful to get a higher success rate of orthodontic mini-screw placement. PMID:23173117

  14. Augmented reality-assisted skull base surgery.

    PubMed

    Cabrilo, I; Sarrafzadeh, A; Bijlenga, P; Landis, B N; Schaller, K

    2014-12-01

    Neuronavigation is widely considered as a valuable tool during skull base surgery. Advances in neuronavigation technology, with the integration of augmented reality, present advantages over traditional point-based neuronavigation. However, this development has not yet made its way into routine surgical practice, possibly due to a lack of acquaintance with these systems. In this report, we illustrate the usefulness and easy application of augmented reality-based neuronavigation through a case example of a patient with a clivus chordoma. We also demonstrate how augmented reality can help throughout all phases of a skull base procedure, from the verification of neuronavigation accuracy to intraoperative image-guidance.

  15. Aesthetic recovery of alveolar atrophy following autogenous onlay bone grafting using interconnected porous hydroxyapatite ceramics (IP-CHA) and resorbable poly-L-lactic/polyglycolic acid screws: case report

    PubMed Central

    2014-01-01

    Background Onlay bone grafting techniques have some problems related to the limited volume of autogenous grafted bone and need for surgery to remove bone fixing screws. Here, we report a case of horizontal alveolar ridge atrophy following resection of a maxillary bone cyst, in which autogenous onlay bone grafting with interconnected porous hydroxyapatite ceramics (IP-CHA) and bioresorbable poly-L-lactic/polyglycolic acid (PLLA-PGA) screws was utilized. Case presentation A 51-year-old man had aesthetic complications related to alveolar atrophy following maxillary bone cyst extraction. We performed onlay grafting for aesthetic alveolar bone recovery using IP-CHA to provide adequate horizontal bone volume and PLLA-PGA screws for bone fixing to avoid later damage to host bone during surgical removal. During the operation, an autogenous cortical bone block was collected from the ramus mandibular and fixed to the alveolar ridge with PLLA-PGA screws, then the gap between the bone block and recipient bone was filled with a granular type of IP-CHA. Post-surgery orthopantomograph and CT scan findings showed no abnormal resorption of the grafted bone, and increased radiopacity, which indicated new bone formation in the area implanted with IP-CHA. Conclusion Our results show that IP-CHA and resorbable PLLA-PGA screws are useful materials for autogenous onlay bone grafting. PMID:24889647

  16. A new scale-up approach for dispersive mixing in twin-screw compounding

    NASA Astrophysics Data System (ADS)

    Fukuda, Graeme; Bigio, David I.; Andersen, Paul; Wetzel, Mark

    2015-05-01

    Scale-up rules in polymer processing are critical in ensuring consistency in product quality and properties when transitioning from low volume laboratory mixing processes to high volume industrial compounding. The scale-up approach investigated in this study evaluates the processes with respect to dispersive mixing. Demand of polymer composites with solid additives, such as carbon microfibers and nanotubes, has become increasingly popular. Dispersive mixing breaks down particles that agglomerate, which is paramount in processing composites because solid additives tend to collect and clump. The amount of stress imparted on the material governs the degree of dispersive mixing. A methodology has been developed to characterize the Residence Stress Distribution (RSD) within a twin-screw extruder in real time through the use of polymeric stress beads. Through this technique, certain mixing scale-up rules can be analyzed. The following research investigated two different scale-up rules. The industry standard for mixing scale-up takes the ratio of outer diameters cubed to convert the volumetric flow rate from the smaller process to a flow rate appropriate in the larger machine. This procedure then resolves both operating conditions since shear rate remains constant. The second rule studied is based on percent drag flow, or the fraction of pumping potential, for different elements along the screw configuration. The percent drag flow rule aims to bring greater focus to operating conditions when scaling-up with respect to dispersive mixing. Through the use of the RSD methodology and a Design of Experiment (DOE) approach, rigorous statistical analysis was used to determine the validity between the scale-up rules of argument.

  17. A pilot study comparing screw-shaped implants. Surface analysis and histologic evaluation of bone healing.

    PubMed

    Lucchini, J P; Aurelle, J L; Therin, M; Donath, K; Becker, W

    1996-12-01

    The purpose of this study was to compare surface treatment and bone formation adjacent to 2 screw shaped implants of similar design manufactured by two different companies. The test implants were manufactured by SERF (Decines, France), while the controls were manufactured by Nobelpharma (Goteborg, Sweden). The surface of 3 standard 3.75 mm test and 3 standard 3.75 mm control implants were investigated by means of scanning electron microscopy (SEM), X-ray micro-analysis, electron spectroscopy for chemical analysis (ESCA) and surface topography analysis. There was a microscopic difference on the thread design (SEM). Test threads were flat at the edge, while controls appeared rounded at the edge of the threads. Tests and controls were made of commercially pure titanium, with a regular topography. Results of ESCA indicated that the carbon peak for SERF implants was slightly higher than for the Brånemark implants. 5 test and 5 control implants were installed into the epiphyseal head of the femur of 2 ewes using a standardized surgical technique. In order to stain the bone for histologic analysis, oxytetracycline injections were given 17 and 8 days before the animals were sacrificed. The animals were sacrificed 12 weeks after implant placement. Histomorphometric analysis indicated that there was an average bone to implant contact orf 68% for the test implants and 61% for the controls. There were no statistical differences between tests and controls. The preliminary results of this pilot study indicated that early bone healing for the 2 screw shaped implants investigated were similar.

  18. Long-term effects of vertical bone augmentation: a systematic review

    PubMed Central

    Keestra, Johan Anton Jochum; Barry, Obada; de Jong, Lianne; Wahl, Gerhard

    2016-01-01

    ABSTRACT Extraction, periodontitis, or trauma can cause a reduction on the alveolar ridge. This could result in an insufficient alveolar bone width and height. Different techniques of vertical bone augmentation are described in literature. However, nowadays there is not enough evidence against lateral augmentation procedures to verify if these techniques are stable over a long period of time. Objective This review analyses the different techniques that are used to vertically augment the bone and evaluate if these techniques are stable over a long period of time. Material and Methods The MEDLINE-PubMed database was searched from its earliest records until December 22, 2014. The following search term was used: Alveolar Ridge augmentation [MESH]. Several journals were hand searched and some authors were contacted for additional information. The primary outcome measure that was analyzed was marginal bone level change around dental implants in the augmented sites, and the secondary outcomes were survival and success rates of dental implants placed in the augmented sites. Results The search yielded 203 abstracts. Ultimately, 90 articles were selected, describing 51 studies meeting the eligibility criteria. The marginal bone level change for the inlay technique and vertical guided bone regeneration are in agreement with the success criteria. Alveolar distraction showed more marginal bone level change after the first year of loading, and for the inlay technique very few studies were available. Conclusions Based on the available data in the current existing studies with a follow-up period of at least 4 to 5 years, one can summarize that there seems to be a trend that the onlay technique, alveolar distraction, and vertical guided bone regeneration are stable for at least 4 to 5 years. PMID:27008252

  19. Pedicle Screw-Based Posterior Dynamic Stabilization: Literature Review

    PubMed Central

    Sengupta, Dilip K.; Herkowitz, Harry N.

    2012-01-01

    Posterior dynamic stabilization (PDS) indicates motion preservation devices that are aimed for surgical treatment of activity related mechanical low back pain. A large number of such devices have been introduced during the last 2 decades, without biomechanical design rationale, or clinical evidence of efficacy to address back pain. Implant failure is the commonest complication, which has resulted in withdrawal of some of the PDS devices from the market. In this paper the authors presented the current understanding of clinical instability of lumbar motions segment, proposed a classification, and described the clinical experience of the pedicle screw-based posterior dynamic stabilization devices. PMID:23227349

  20. [Observations on optimizing the mechanical properties of osteosynthesis screws].

    PubMed

    Zitter, H

    1988-06-01

    According to two agreeing standards, the mechanical requirements for bone screws consist of a minimum breaking torque and of the minimum angle of rotation to failure of 180 degrees. Apparently it has been overlooked that these requirements admit austenitic steels with a very low yield strength, which reach the required torque at fracture only by the work-hardening brought about during the torsion test. As a high yield strength is a prerequisite of a stable fixation, a formulation is proposed which guarantees not only a high elastic torque but also an adequate work of deformation in the plastic state as an insurance against embrittlement. PMID:3407018