Sample records for iliac screw fixation

  1. Free-hand placement of iliac screws for spinopelvic fixation based on anatomical landmarks: technical note

    PubMed Central

    Fridley, Jared; Fahim, Daniel; Navarro, Jovany; Wolinsky, JP

    2014-01-01

    Background The placement of iliac screws is a biomechanically sound method for the stabilization of long multi-segment lumbar constructs. Traditional techniques for the placement of iliac screws often involve either substantial iliac muscle dissection for visualization of screw trajectory based on bony landmarks, or alternatively the use of intra-operative imaging to visualize these landmarks and guide screw placement. We describe an alternative free-hand method of iliac screw placement, one that needs neither significant muscle dissection nor intra-operative imaging. Methods We performed this technique in 10 consecutive patients. Patient demographics, spinal pathology, post-operative complications, and screw hardware characteristics are described. Results We have successfully used this technique for the placement 20 iliac screws based on anatomic landmarks in 10 consecutive patients. There were no cortical breeches of the ileum and no penetrations into the acetabulum on post-operative imaging. There were no instances of hardware failure. Two patients developed deep vein thromboses after surgery, 1 had a pulmonary embolism. Conclusions Based on our limited experience to date, free-hand placement of iliac screws is both easy to perform and safe for the patient. Further study and validation using this technique is warranted. PMID:25694933

  2. Use of fluoroscopy to evaluate iliac screw position.

    PubMed

    Orchowski, Joseph R; Polly, David W; Kuklo, Timothy R; Klemme, William R; Schroeder, Teresa M

    2006-03-01

    Iliac screw fixation is often used for long fusions to the sacropelvis. Maximum iliac screw purchase is obtained both by placing the screws within 1.5 cm of the greater sciatic notch and by extending them anterior to the axis of rotation in flexion-extension. Screw insertion is "blinded" or dependent on tactile feedback, and hence extreme care is necessary to avoid incorrect placement and damage to vital neurovascular structures in the pelvis and sciatic notch. Long screws may violate the hip joint while medial placement may injure the lumbosacral plexus and the nearby vessels. To explore the best intraoperative fluoroscopic method of determining optimal iliac screw placement, we used a synthetic pelvis model to investigate screw placement conditions: (1) optimal anatomic placement, (2) violation of the sciatic notch, (3) hip joint violation, (4) medial wall violation, and (5) lateral wall violation. Each condition was examined utilizing fluoroscopy with posteroanterior, inlet, outlet, lateral, iliac oblique, and obturator oblique Judet views to simulate operative conditions. These views were obtained to evaluate critical malposition of iliac screws. We found that, for a sciatic notch violation, the obturator oblique view best demonstrated the cortical breech, while for a hip joint violation, the inlet and outlet views were best. For a medial wall violation, the iliac oblique view best showed the violation. For a lateral wall violation, we were unable to demonstrate the cortical breech using these fluoroscopic views. Fluoroscopy is an effective method to determine sciatic notch, hip joint, and medial wall violations after iliac screw placement; however, it is not effective in identifying a lateral wall violation. PMID:16610381

  3. Radiographic study of iliac screw passages

    PubMed Central

    2014-01-01

    Background The optimal iliac screw path was determined to provide references for lumbosacral-pelvic reconstruction. Methods Radiographic data of 100 patients with normal pelvis were selected for this study. Four paths were designed. Paths A, B, and C were from the starting point of the crossing point of the chiotic line and posterior iliac crest (CLIC, located at 24.0 mm above the posterior superior iliac spine) to the upper edge of the acetabulum, anterior inferior iliac spine, and acetabulum center, respectively. Path D was from the starting point of the posterior superior iliac spine to the anterior inferior iliac spine. The lengths of the different paths of screw passage and bone plate thicknesses of two narrow places were measured and analyzed. Results Paths A, B, and D were approximately equal in length, but the thickness of the iliac plate in path A was significantly thicker than those in paths B and D. No significant difference was found between the iliac thickness of paths A and C, but the passage length of path A was significantly longer than that of path C. Conclusion Path A had the longest passage length and thickest iliac plate and could accommodate the relatively longest and thickest iliac screw. Thus, path A was the optimal iliac screw passage. PMID:24885171

  4. The unstable iliac fracture: a biomechanical evaluation of internal fixation.

    PubMed

    Simonian, P T; Routt, M L; Harrington, R M; Tencer, A F

    1997-09-01

    Neither plating nor lag screw fixation of a displaced iliac wing fracture as part of an unstable pelvic ring disruption has been studied biomechanically. The purpose of this study was to compare the stability of various combinations of fixation, specifically contrasting lag screws placed between the tables of the ilium with plating in different locations across the fracture line. Various combinations of these fixation implants were evaluated for an unstable iliac fracture. A longitudinal iliac fracture was created in each of six hemi-pelvic specimens prior to testing. Compressive force, up to 500 N or to the magnitude necessary to displace the fracture 2 mm, was applied to the fracture line through the hemi-pelvis for each of the plate and lag screw combinations tested. There was no statistical difference between any of the implants or combinations tested. A single 3.5-mm reconstruction (cephalad) plate placed along the cephalad internal aspect of the iliac crest provided the least stability allowing 2 mm of displacement with a mean load of 80 N. The two combinations of fixation that required the greatest loads for 2 mm of displacement were a single 3.5-mm lag (cephalad) screw inserted into the iliac crest between the tables of the ilium coupled with either a 3.5-mm reconstruction (brim) plate placed along the internal aspect of the inferior iliac fossa at the pelvic brim (239 N) or a 4.5-mm lag (brim) screw between the inner and outer tables at the inferior aspect of the fracture just above the greater sciatic notch (225 N). PMID:9509089

  5. Lateral mass screw fixation in children

    PubMed Central

    Proctor, Mark; Hresko, Timothy

    2010-01-01

    Purpose The safety and feasibility of posterior screw fixation of the cervical spine in children has not been well documented in the orthopedic literature. We performed a retrospective review of our experience using posterior cervical screw fixation in children. Methods The medical records and radiologic records of 36 children at a mean age of 10 years (range 3–16 years) were reviewed. Diagnoses included: ten instability, 11 deformity, seven trauma, five tumor, and three congenital abnormalities. Operative reports and postoperative computed tomography (CT) scans were reviewed to determine the technical feasibility of screw placement, any screw-related complications, and to assess for correct screw position. In this series, there were no neurologic complications, no vertebral artery injuries, and no screw-related complications. Results Thirty patients (141 screws) had screws evaluated postoperatively and were shown to be completely contained on postoperative CT scans. There were no revisions due to screw failure or dislodgement. There were no vascular or neurologic complications. Conclusions Posterior screw fixation in the pediatric population may be done safely and greatly enhances fixation strength for a variety of disorders requiring instrumentation and fusion. PMID:21629379

  6. The lateral fixation screw in implant dentistry.

    PubMed

    Sethi, A; Sochor, P

    2000-03-01

    This clinical report presents a means of retaining implant supported superstructures using lateral fixation screws (Novadent). 244 lateral fixation screws have been used for the retention of a variety of restorations including single teeth, short span and full arch bridgework as well as overdenture bars. Over a period of observation of 4 years, the authors have found the restorations to have effective retention, ease of retrievability, good aesthetics and occlusal contours. PMID:11307389

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

    PubMed Central

    2014-01-01

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

  8. Morphometry of iliac anchorage for transiliac screws: a cadaver and CT study of the Eastern population

    Microsoft Academic Search

    Xiguang Tian; Jiazhen Li; Weichao Sheng; Dongbin Qu; Jun Ouyang; Dachuan Xu; Shenghua Chen; Zihai Ding

    2010-01-01

    Objectives  To describe the morphometry of iliac columns for transiliac screw and to testify the conformity among the anatomic measurement,\\u000a two-dimensional (2D) and three-dimensional (3D) computed tomography.\\u000a \\u000a \\u000a \\u000a \\u000a Methods  We evaluated the length, inner width, and angle of three screw trajectories starting at the iliac tubercle, posterior superior\\u000a iliac spine, and posterior inferior iliac spine toward the anterior inferior iliac spine. Measurements were

  9. Translaminar screw fixation in the subaxial pediatric cervical spine.

    PubMed

    Jea, Andrew; Johnson, Keyne K; Whitehead, William E; Luerssen, Thomas G

    2008-12-01

    The use of spinal instrumentation to stabilize the occipitocervical junction in pediatric patients has increased and evolved in recent years. Wiring techniques have now given way to screw-rod or screw-plate techniques with or without postoperative external immobilization. Although C-2 translaminar screws have been used in these constructs, subaxial translaminar screws have not, to date, been described in either the pediatric or adult patient populations. The authors describe the feasibility of translaminar screw placement in the C-3 lamina. Rigid fixation with translaminar screws offers an alternative to subaxial fixation with lateral mass screws, allowing for formation of biomechanically sound spinal constructs and minimizing potential neurovascular morbidity. Their use requires careful analysis of preoperative imaging studies, intact posterior elements, and avoidance of violation of the inner laminar wall. PMID:19035682

  10. Lumbosacral Fixation Using the Diagonal S2 Screw for Long Fusion in Degenerative Lumbar Deformity: Technical Note Involving 13 Cases

    PubMed Central

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

    2013-01-01

    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. PMID:24009909

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

    PubMed

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

    2014-07-01

    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

  12. Effect of screw placement on fixation in the humeral head.

    PubMed

    Liew, A S; Johnson, J A; Patterson, S D; King, G J; Chess, D G

    2000-01-01

    The objectives of this study were (1) to determine the most advantageous screw locations within the humeral head when plate and screw fixation is to be used and (2) to determine the effect of positioning the screw tip abutting the subchondral bone. Ten paired humeral heads were harvested with a monoplanar cut through the anatomic neck. Through use of a standardized template, 7 holes were drilled and tapped in each specimen for insertion of 6.5-mm fully threaded cancellous screws perpendicular to the plane of the cut. Paired specimens were randomized into 2 groups, one with the screw purchase in central cancellous bone and the other with the screw purchase up to the subchondral bone. Each screw was pulled out axially at a displacement rate of 10 mm/min through use of a servohydraulic testing machine. The length of thread purchase, position within the head, and screw pullout load to failure were recorded. The normalized pullout force to failure was calculated by dividing absolute pullout force to failure by length of screw purchase. Data were analyzed by means of a 2-way repeated measures analysis of variance and post hoc Student-Newman-Keuls test. The central position had a significantly higher absolute pullout force to failure than all other sites (P < .05). By virtue of the humeral head shape, the central position also had a significantly greater length of screw purchase than all other positions (P < .05). The central position had a significantly higher relative pullout force to failure than all other positions (P < .05). Subchondral bone abutment positioning improved both the absolute and the relative pullout forces to failure (P < .05). When screws and plates are used in open reduction and internal fixation of a proximal humerus fracture, a major mode of failure is loss of fixation within the humeral head. On the basis of this study, optimal screw purchase with respect to bone fixation can be achieved by including screws located in the center of the humeral head in the subchondral abutment position. To minimize screw fixation failure, the anterosuperior position should be avoided. The pattern of distribution of the relative pullout force as measured in this study is consistent with previous observational studies of patterns of trabecular density within the humeral head. PMID:11075327

  13. Allograft interference screw fixation in meniscus transplantation

    Microsoft Academic Search

    Jack Farr; R. Michael Meneghini; Brian J. Cole

    2004-01-01

    Allograft meniscus transplantation is indicated to restore proper knee biomechanics and prevent subsequent articular degeneration in patients with a meniscus-deficient knee. A variety of techniques for fixation of meniscal transplants exist, with some techniques using soft-tissue fixation of the meniscal horns and others using bony fixation. The authors present a technique of meniscus transplantation using a tibial slot with allograft

  14. Atlantoaxial fixation using the polyaxial screw–rod system

    PubMed Central

    Vyskocil, Tomas; Sebesta, Petr; Kryl, Jan

    2006-01-01

    The aim of this study is to evaluate the first results of the atlantoaxial fixation using polyaxial screw–rod system. Twenty-eight patients followed-up 12–29 months (average 17.1 months) were included in this study. The average age was 59.5 years (range 23–89 years). The atlantoaxial fusion was employed in 20 patients for an acute injury to the upper cervical spine, in 1 patient with rheumatoid arthritis for atlantoaxial vertical instability, in 1 patient for C1–C2 osteoarthritis, in 2 patients for malunion of the fractured dens. Temporary fixation was applied in two patients for type III displaced fractures of the dens and in two patients for the atlantoaxial rotatory dislocation. Retrospectively, we evaluated operative time, intraoperative bleeding and the interval of X-ray exposure. The resulting condition was subjectively evaluated by patients. We evaluated also the placement, direction and length of the screws. Fusion or stability in the temporary fixation was evaluated on radiographs taken at 3, 6, 12 weeks and 6 and 12 months after the surgery. As concerns complications, intraoperatively we monitored injury of the nerve structures and the vertebral artery. Monitoring of postoperative complications was focused on delayed healing of the wound, breaking or loosening of screws and development of malunion. Operative time ranged from 35 to 155 min, (average 83 min). Intraoperative blood loss ranged from 50 to 1,500 ml (average 540 ml). The image intensifier was used for a period of 24 s to 2 min 36 s (average 1 min 6 s). Within the postoperative evaluation, four patients complained of paresthesia in the region innervated by the greater occipital nerve. A total of 56 screws were inserted into C1, their length ranged from 26 to 34 mm (average, 30.8 mm). All screws were positioned correctly in the C1 lateral mass. Another 56 screws were inserted into C2. Their length ranged from 28 to 36 mm (average 31.4 mm). Three screws were malpositioned: one screw perforated the spinal canal and two screws protruded into the vertebral artery canal. C1–C2 stability was achieved in all patients 12 weeks after the surgery. No clinically manifested injury of the vertebral artery or nerve structures was observed in any of these cases. As for postoperative complications, we recorded wound dehiscence in one patient. The Harms C1–C2 fixation is a very effective method of stabilizing the atlantoaxial complex. The possibility of a temporary fixation without damage to the atlantoaxial joints and of reduction after the screws and rods had been inserted is quite unique. PMID:17051397

  15. 2D-fluoroscopic navigated percutaneous screw fixation of pelvic ring injuries - a case series

    Microsoft Academic Search

    Florian Gras; Ivan Marintschev; Arne Wilharm; Kajetan Klos; Thomas Mückley; Gunther O Hofmann

    2010-01-01

    BACKGROUND: Screw fixation of pelvic ring fractures is a common, but demanding procedure and navigation techniques were introduced to increase the precision of screw placement. The purpose of this case series was the evaluation of screw misplacement rate and functional outcome of percutaneous screw fixation of pelvic ring disruptions using a 2D navigation system. METHODS: Between August 2004 and December

  16. Transpedicular screw fixation in the thoracic and lumbar spine with a novel cannulated polyaxial screw system

    PubMed Central

    Weise, Lutz; Suess, Olaf; Picht, Thomas; Kombos, Theodoros

    2008-01-01

    Objective: Transpedicular screws are commonly and successfully used for posterior fixation in spinal instability, but their insertion remains challenging. Even using navigation techniques, there is a misplacement rate of up to 11%. The aim of this study was to assess the accuracy of a novel pedicle screw system. Methods: Thoracic and lumbar fusions were performed on 67 consecutive patients for tumor, trauma, degenerative disease or infection. A total of 326 pedicular screws were placed using a novel wire-guided, cannulated, polyaxial screw system (XIA Precision®, Stryker). The accuracy of placement was assessed postoperatively by CT scan, and the patients were followed-up clinically for a mean of 16 months. Results: The total medio-caudal pedicle wall perforation rate was 9.2% (30/326). In 19 of these 30 cases a cortical breakthrough of less than 2 mm occurred. The misplacement rate (defined as a perforation of 2 mm or more) was 3.37% (11/326). Three of these 11 screws needed surgical revision due to neurological symptoms or CSF leakage. There have been no screw breakages or dislocations over the follow up-period. Conclusion: We conclude that the use of this cannulated screw system for the placement of pedicle screws in the thoracic and lumbar spine is accurate and safe. The advantages of this technique include easy handling without a time-consuming set up. Considering the incidence of long-term screw breakage, further investigation with a longer follow-up period is necessary. PMID:22915906

  17. Iliac Bars Lever Reduction and Fixation System Used in the Treatment of Spondylolisthesis

    PubMed Central

    Shen, Yong; Yang, Dalong; Zhang, Guochuan; Song, Chaohui; Cao, Junming

    2008-01-01

    Background The purpose of the current study was to use the Iliac Bars Lever Reduction and Fixation System (IBLRFS) for Grades 1 and 2 spondylolytic spondylolisthesis, evaluate its stability and reductive efficacy, and examine the complications. Methods Between April 2005 and August 2006, 44 patients with Grades 1 and 2 spondylolytic spondylolisthesis were treated surgically: 21 patients underwent posterior Iliac Bars Lever Reduction and Fixation (IBRLFS), 23 patients were treated with traditional stabilization and reduction systems (SRS). The follow-up periods ranged from 1 to 2 years (mean, 1 year and 2 months). The clinical outcome, fusion rate, average percentile degree of displacement, displacement angle, sacral inclination, ratio of intervertebral height, and complications were evaluated. Operating time, blood loss, and duration of hospital stay were compared. Results There were no statistically significant differences between the 2 groups in blood loss, recovery rate, and radiographic results. However, there were statistically significant differences in operating time (P < .05), duration of hospital stay (P < .05). There were no cases of nonunion in the two groups. In the IBLRFS group, preoperatively, the average percentile degree of displacement, displacement angle, sacral inclination, and ratio of intervertebral height were 23.48% ± 5.36%, 2.2° ± 1.1°, 29.4° ± 6.5°, and 0.68 ± 0.21, respectively. Postoperatively, the respective measurements were 6.47% ± 1.49%, 10.3° ± 3.3°, 42.6° ± 8.1°, and 0.85 ± 0.12. No patients experienced major complications. In the SRS group, preoperatively, the average percentile degree of displacement, displacement angle, sacral inclination, and ratio of intervertebral height were 21.78% ± 5.16%, 2.3° ± 1.0°, 26.4° ± 8.5°, and 0.62 ± 0.25, respectively. Postoperatively, the respective measurements were 6.34% ± 2.01%, 9.8° ± 2.1°, 44.1° ± 7.6°, and 0.79 ± 0.23. One patient experienced a badly placed screw in the right pedicle of lumbar 4. Conclusions This kind of new fixation system (IBLRFS) was shown to be useful in the treatment of spondylolisthesis, and its use was associated with minimal complications after 14 months of mean follow-up. Level of Evidence Therapeutic, case studies (level 4).

  18. Bioabsorbable Interference Screws for Graft Fixation in Anterior Cruciate Ligament Reconstruction

    Microsoft Academic Search

    David A. McGuire; F. Alan Barber; Burton F. Elrod; Lonnie E. Paulos

    1999-01-01

    Summary: The central one third of the patellar tendon autograft is popular because the bone-tendon-bone (BTB) construct provides several graft fixation options, robust graft incorporation, and a mechanically sufficient substitute. Interference screw fixation is one method used to secure the graft. Bioabsorbable interference screws may offer advantages over metal interference screws. Bioabsorbable screws are made from poly L-lactic acid (PLLA)

  19. The influence of screw geometry on hamstring tendon interference fit fixation.

    PubMed

    Weiler, A; Hoffmann, R F; Siepe, C J; Kolbeck, S F; Südkamp, N P

    2000-01-01

    We used a standardized model of calf tibial bone to investigate the influence of screw diameter and length on interference fit fixation of a three-stranded semitendinosus tendon graft for anterior cruciate ligament reconstruction. Biodegradable poly-(L-lactide) interference screws with a diameter of 7, 8, and 9 mm and a length of 23 and 28 mm were used. We examined results in three groups of 10 specimens each: group 1, screw diameter equaled graft diameter and screw length was 23 mm; group 2, screw diameter equaled graft diameter plus 1 mm and screw length was 23 mm; group 3, screw diameter equaled graft diameter and screw length was 28 mm. The mean pull-out forces in groups 1, 2, and 3 were 367.2+/-78 N, 479.1+/-111.1 N, and 537.4+/-139.1 N, respectively. The force data from groups 2 and 3 were significantly higher than those from group 1. These results indicate that screw geometry has a significant influence on hamstring tendon interference fit fixation. Increasing screw length improves fixation strength more than oversizing the screw diameter. This is important, especially for increasing tibial fixation strength because the tibial graft fixation site has been considered to be the weak link of such a reconstruction. PMID:10843127

  20. Refracture of Proximal Fifth Metatarsal (Jones) Fracture After Intramedullary Screw Fixation in Athletes

    Microsoft Academic Search

    Rick W. Wright; David A. Fischer; Robert A. Shively; Robert S. Heidt; Gordon W. Nuber

    2000-01-01

    This study details six instances of refracture of clinically and radiographically healed fractures of the base of the fifth metatarsal after intramedullary screw fixation. Four professional football players, one college basketball player, and one recreational athlete underwent intramedullary screw fixation of fifth metatarsal fractures. The athletes were released to full activities an average of 8.5 weeks (range, 5.5 to 12)

  1. Tibial Fixation of Bone-Patellar Tendon-Bone Grafts in Anterior Cruciate Ligament ReconstructionA Cadaveric Study of Bovine Bone Screw and Biodegradable Interference Screw

    Microsoft Academic Search

    Naiquan Zheng; Chad T. Price; Peter A. Indelicato; Bo Gao

    2008-01-01

    Background: The use of interference screw fixation for bone-patellar tendon-bone grafts in anterior cruciate ligament fixation is well established. No previous study has compared bovine bone screws and biodegradable interference screws or demonstrated their efficacy for requirements associated with early rehabilitation.Hypothesis: There is no difference in tension loss and pull-out strength between bovine bone screws and biodegradable interference screws.Study Design:

  2. 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 bone stock and can be used for further investigations. PMID:22470474

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

    PubMed Central

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

    2013-01-01

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

  4. Transforaminal lumbar interbody fusion using unilateral pedicle screw fixation plus contralateral translaminar facet screw fixation in lumbar degenerative diseases

    PubMed Central

    Liu, Fubing; Jiang, Chun; Cao, Yuanwu; Jiang, Xiaoxing; Feng, Zhenzhou

    2014-01-01

    Background: Transforaminal lumbar interbody fusion (TLIF) has been used in lumbar degenerative diseases. Some researchers have applied unilateral fixation in TLIF to reduce operational trauma without compromising the clinical outcome, but it is always suspected biomechanically unstable. The supplementary contralateral translaminar facet screw (cTLFS) seemed to be able to overcome the inherent drawbacks of unilateral pedicle screw (uPS) fixation theoretically. This study evaluates the safety, feasibility and efficacy of TLIF using uPS with cTLFS fixation in the treatment of lumbar degenerative diseases (LDD). Materials and Methods: 50 patients (29 male) underwent the aforementioned surgical technique for their LDD between December 2009 and April 2012. The results were evaluated based on visual analogue scale (VAS) of the leg and back, Japanese Orthopedic Association (JOA) score and Oswestry Disability Index (ODI) were recorded. The radiographic examinations in form of X-ray, computed tomography (CT) or magnetic resonance imaging was done preoperatively and 1 week, 3 months, 6 months, 12 months and 24 months postoperatively. The student t-test was used for comparison between the preoperative values and postoperative counterparts. P < 0.05 was considered to be statistically significant. Results: Among 50 patients, 22 received one level fusion and 28 two level's, with corresponding operation time and estimated blood loss being approximately 90 min, 150 ml and 120 min, 200 ml, respectively. No severe complications happened perioperatively. The mean VAS (back, leg) scores dropped from (7.6, 7.5) preoperatively to (2.1, 0.6) at 12 months’ followup, ODI from 49.1 preoperatively to 5.6 and JOA score raised from 10.6 preoperatively to 28.5, all P < 0.001, suggesting of good clinical outcome. From the three-dimensional reconstructed CT, 62 out of 70 segments displayed solid fusion with fusion rate of 88.6% at 12 months postoperatively. Conclusions: TLIF using uPS fixation plus cTLFS fixation is a safe, feasible and effective technique in the treatment of one or two level lumbar degenerative diseases short termly. PMID:25143640

  5. Treatment of Unstable Thoracolumbar Fractures through Short Segment Pedicle Screw Fixation Techniques Using Pedicle Fixation at the Level of the Fracture: A Finite Element Analysis

    PubMed Central

    Li, Changqing; Zhou, Yue; Wang, Hongwei; Liu, Jun; Xiang, Liangbi

    2014-01-01

    Objective To compare the von Mises stresses of the internal fixation devices among different short segment pedicle screw fixation techniques to treat thoracic 12 vertebral fractures, especially the mono-segment pedicle screw fixation and intermediate unilateral pedicle screw fixation techniques. Methods Finite element methods were utilised to investigate the biomechanical comparison of the four posterior short segment pedicle screw fixation techniques (S4+2: traditional short-segment 4 pedicle screw fixation [SPSF]; M4+2: mono-segment pedicle screw fixation; I6+2: intermediate bilateral pedicle screw fixation; and I5+2: intermediate unilateral pedicle screw fixation). Results The range of motion (ROM) in flexion, axial rotation, and lateral bending was the smallest in the I6+2 fixation model, followed by the I5+2 and S4+2 fixation models, but lateral bending was the largest in the M4+2 fixation model. The maximal stress of the upper pedicle screw is larger than the lower pedicle screw in S4+2 and M4+2. The largest maximal von Mises stress was observed in the upper pedicle screw in the S4+2 and M4+2 fixation models and in the lower pedicle screw in the I6+2 and I5+2 fixation models. The values of the largest maximal von Mises stress of the pedicle screws and rods during all states of motion were 263.1 MPa and 304.5 MPa in the S4+2 fixation model, 291.6 MPa and 340.5 MPa in the M4+2 fixation model, 182.9 MPa and 263.2 MPa in the I6+2 fixation model, and 269.3 MPa and 383.7 MPa in the I5+2 fixation model, respectively. Comparing the stress between different spinal loadings, the maximal von Mises stress of the implants were observed in flexion in all implanted models. Conclusion Additional bilateral pedicle screws at the level of the fracture to SPSF may result in a stiffer construct and less von Mises stress for pedicle screws and rods. The largest maximal von Mises stress of the pedicle screws during all states of motion were observed in the mono-segment pedicle screw fixation technique. PMID:24914815

  6. Mechanical evaluation of a soft tissue interference screw in free tendon anterior cruciate ligament graft fixation.

    PubMed

    Nagarkatti, D G; McKeon, B P; Donahue, B S; Fulkerson, J P

    2001-01-01

    In this study of bioabsorbable screw fixation of free tendon grafts used in anterior cruciate ligament reconstruction, we performed load-to-failure and cyclic loading of tendon fixation in porcine bone. Bone density measurements from dual photon absorptometry scans were obtained to correlate bone density with fixation failure. The average density of porcine bone (1.42 g/cm2) was similar to that of young human bone (1.30 g/cm2) and significantly higher than that of elderly human cadaveric bone specimens (0.30 g/cm2). Cyclic loading was performed on free tendon grafts fixed with a bioabsorbable screw alone and on grafts fixed with a bioabsorbable screw and an anchor (polylactic acid ball or cortical bone disk). Stiffness of fixation increased substantially with the addition of a cortical bone disk anchor or polylactic acid ball compared with the interference screw alone. Tensile fixation strength of central quadriceps free tendon and hamstring tendon grafts were significantly superior in porcine bone of density similar to young human bone than in elderly human cadaveric bone. The bioabsorbable interference screw yielded loads at failure comparable with traditional bone-tendon-bone and hamstring tendon fixation when controlled for bone density. The addition of a cortical bone disk anchor provided the most optimal fixation of free tendon with the bioabsorbable screw and reduced slippage with cyclic loading to a very low level. PMID:11206259

  7. Progressive slip after removal of screw fixation in slipped capital femoral epiphysis: two case reports

    PubMed Central

    2012-01-01

    Introduction In slipped capital femoral epiphysis the femoral neck displaces relative to the head due to weakening of the epiphysis. Early recognition and adequate surgical fixation is essential for a good functional outcome. The fixation should be secured until the closure of the epiphysis to prevent further slippage. A slipped capital femoral epiphysis should not be confused with a femoral neck fracture. Case presentation Case 1 concerns a 15-year-old boy with an adequate initial screw fixation of his slipped capital femoral epiphysis. Unfortunately, it was thought that the epiphysis had healed and the screw was removed after 11 weeks. This caused new instability with a progressive slip of the femoral epiphysis and subsequently re-fixation and a subtrochanteric correction osteotomy was obligatory. Case 2 concerns a 13-year-old girl with persistent hip pain after screw fixation for slipped capital femoral epiphysis. The screw was removed as lysis was seen around the screw on the hip X-ray. This operation created a new unstable situation and the slip progressed resulting in poor hip function. A correction osteotomy with re-screw fixation was performed with a good functional result. Conclusion A slipped epiphysis of the hip is not considered ‘healed’ after a few months. Given the risk of progression of the slip the fixation material cannot be removed before closure of the growth plate. PMID:23181447

  8. The Surgical Management of Traumatic Lower Cervical Spondylolisthesis with Posterior Percutaneous Pedicle Screw Fixation

    PubMed Central

    Luo, Peng; Ni, Wen-Fei; Wu, Yao-Sen; Wu, Ai-Min; Wang, Xiang-Yang; Xu, Hua-Zi

    2015-01-01

    We reported a technical report of traumatic lower cervical spondylolisthesisca used by bilateral pedicle fracture, without neurological compression. The patient was treated with the minimally invasive technique of percutaneous pedicle screw fixation. Fracture healing and normal cervical motion were confirmed by plain films and physical examinations on the 18-monthpostoperatively. The technique of percutaneous pedicle screw fixation might be an alternative strategy for the treatment of traumatic lower cervical spondylolisthesis with pedicle fracture.

  9. Calcium phosphate cement augmentation of cancellous bone screws can compensate for the absence of cortical fixation

    E-print Network

    Guerraoui, Rachid

    Calcium phosphate cement augmentation of cancellous bone screws can compensate for the absence Keywords: Screw fixation Pullout force Calcium phosphate cement Osteoporotic bone a b s t r a c with cement. Previous studies have shown that bone augmentation with Calcium Phosphate (CaP) cement

  10. Anterior transarticular screw fixation as a conventional operation for rigid stabilization

    PubMed Central

    Sasaki, Manabu; Matsumoto, Katsumi; Tsuruzono, Koichiro; Yoshimura, Kazuhiro; Shibano, Katsuhiko; Yonenobu, Kazuo

    2014-01-01

    Background: Anterior transarticular screw (ATS) fixation is a useful surgical option for atlantoaxial (AA) stabilization. This report presents a revised ATS method for AA fusion. Methods: A 79-year-old male presented with AA instability attributed both to an old odontoid fracture and severe degeneration of the lateral atlantoaxial joints (LAAJs). ATS fixation was performed through the conventional anterior cervical approach. The longest screw trajectories were planned preoperatively using multiplanar reconstruction computed tomography (CT) scans, with entry points of the screws situated at the midpoint on the inferior border of the axial body. The surgical exposure was limited to opening at the entry points alone. Our retractor of choice was the Cusco speculum; it sufficiently secured space for utilizing the required instruments for screw placement while offering sufficient protection of soft tissues. Cannulated full-threaded bicortical screws stabilized the LAAJs. Screw insertion required a significant amount of coronal angulation up to the superior articular process of the atlas under open-mouth and lateral fluoroscopy image guidance. After ATS fixation, bone grafting was performed between the posterior laminae of the axis and the atlas through a conventional posterior approach. Results: Bony fusion between the atlas and the axis was confirmed radiographically. Arthrodesis of the LAAJs occurred despite no bone grafting. Conclusions: Rigid fixation of the LAAJs was obtained by our ATS technique, indicating that it is an alternative method for AA fixation when posterior rigid internal fixation is not applicable. PMID:25593774

  11. Inferolateral Entry Point for C2 Pedicle Screw Fixation in High Cervical Lesions

    PubMed Central

    Lee, Kwang Ho; Lee, Chul Hee; Hwang, Soo Hyun; Park, In Sung; Jung, Jin Myung

    2011-01-01

    Objective The purpose of this retrospective study was to evaluate the efficacy and safety of atlantoaxial stabilization using a new entry point for C2 pedicle screw fixation. Methods Data were collected from 44 patients undergoing posterior C1 lateral mass screw and C2 screw fixation. The 20 cases were approached by the Harms entry point, 21 by the inferolateral point, and three by pars screw. The new inferolateral entry point of the C2 pedicle was located about 3-5 mm medial to the lateral border of the C2 lateral mass and 5-7 mm superior to the inferior border of the C2-3 facet joint. The screw was inserted at an angle 30° to 45° toward the midline in the transverse plane and 40° to 50° cephalad in the sagittal plane. Patients received followed-up with clinical examinations, radiographs and/or CT scans. Results There were 28 males and 16 females. No neurological deterioration or vertebral artery injuries were observed. Five cases showed malpositioned screws (2.84%), with four of the screws showing cortical breaches of the transverse foramen. There were no clinical consequences for these five patients. One screw in the C1 lateral mass had a medial cortical breach. None of the screws were malpositioned in patients treated using the new entry point. There was a significant relationship between two group (p=0.036). Conclusion Posterior C1-2 screw fixation can be performed safely using the new inferolateral entry point for C2 pedicle screw fixation for the treatment of high cervical lesions. PMID:22200017

  12. Cannulated Screw Fixation of Jones FracturesA Clinical and Biomechanical Study

    Microsoft Academic Search

    Keri Reese; Alan Litsky; Christopher Kaeding; Angela Pedroza; Nilesh Shah

    2004-01-01

    Background: Traditional nonsurgical treatment of Jones fractures has high rates of delayed union, nonunion, and refracture. Internal fixation has become the treatment of choice in athletes and active patients.Purpose: The purpose of this study was (1) to review the short- and long-term clinical results of cannulated screw fixation of Jones fractures and (2) to perform a biomechanical evaluation of fatigue

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

    PubMed Central

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

    2013-01-01

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

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

    PubMed

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

    2014-02-01

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

  15. Polyaxial locking and compression screws improve construct stiffness of acetabular cup fixation: a biomechanical study.

    PubMed

    Milne, Lachlan P; Kop, Alan M; Kuster, Markus S

    2014-05-01

    Bone ingrowth into uncemented acetabular components requires intimate cup-bone contact and rigid fixation, which can be difficult to achieve in revision hip arthroplasty. This study compares polyaxial compression locking screws with non-locked and cancellous screw constructs for acetabular cup fixation. An acetabular cup modified with screw holes to provide both compression and angular stability was implanted into a bone substitute. Coronal lever out, axial torsion and push-out tests were performed with an Instron testing machine, measuring load versus displacement. Polyaxial locking compression screws significantly improved construct stiffness compared with non-locked or cancellous screws. This increased construct stiffness will likely reduce interfacial micromotion. Further research is required to determine whether this will improve bone ingrowth in vivo and reduce cup failure. PMID:24360790

  16. Use of an aiming device in posterior atlantoaxial transarticular screw fixation. Technical note.

    PubMed

    Neo, Masasi; Matsushita, Mutsumi; Yasuda, Tadashi; Sakamoto, Takeshi; Nakamura, Takashi

    2002-07-01

    Posterior atlantoaxial transarticular screw fixation is an excellent procedure associated with high fusion rates. There is, however, the potential risk of vertebral artery (VA) injury. The authors designed a special aiming device that allows a cannulated screw to be inserted accurately in the most posterior part of the C1-2 joint via the most posterior and medial part of the isthmus of C-2; this screw pathway most safely avoids VA injury. The instruments include an aiming device and a flexible screw-inserting system. The tip of the aiming device is placed on the ridge of the C-2 isthmus just posterior to the atlantoaxial joint. The guide wire should then pass 1 mm below the device tip. The system consists of flexible guide wires, a drill, a tap, and a screwdriver, and the screw is inserted easily via a posterior approach in which the patient's back is not obstructive. Ten patients with atlantoaxial subluxation or osteoarthritis underwent surgery in which the device was used. In all cases, the screws were inserted safely without causing VA injury, although preoperative computerized tomography (CT) reconstructions revealed a high-risk high-riding unilateral VA in three patients. Postoperative CT reconstructions demonstrated that all screws but one were inserted as planned, and successfully cleared the vertebral groove. In conclusion, this newly designed device is practical and useful for the accurate insertion of screws, thus avoiding VA injury during atlantoaxial transarticular screw fixation. PMID:12120635

  17. Combined anterior interbody fusion and posterior pedicle screw fixation in patients with degenerative lumbar disc disease

    Microsoft Academic Search

    M. A. El Masry; W. S. Badawy; P. Rajendran; D Chan

    2004-01-01

    We reviewed 47 consecutive patients with degenerative lumbar disc disease. All patients were treated by anterior interbody fusion using an autogenous iliac bone graft in combination with posterior pedicle fixation but without a posterior fusion. There were 32 men and 15 women with a mean age of 44 (range 23–56) years. One third ( n=15) of the patients had previous

  18. Anatomical measurement and finite element study on screw channel parameter in percutaneous fixation of canulated screw for symphyseolysis.

    PubMed

    Yu, Kehe; Hong, Jianjun; Sun, Yuefei; Shi, Chengdi; Guo, Xiaoshan; Zhou, Dongsheng

    2015-03-01

    To provide anatomical basement for symphyseolysis treatment with percutaneous fixation of canulated screw, through anatomical measurement on pubic symphysis and the surrounding tissues, and conduct the finite element studies on screw channel parameters. 20 cases of normal pelvic specimens from embalmed adult cadavers were taken to measure the anatomical parameter of bony remark of pubic symphysis and the space between spermatic cord (round ligament of the uterus) and pubic tubercle. Anatomical measurement results showed that the narrowest diameter of the superior ramus of pubis was 9.127 ± 1.189 mm, distance between two pubic tubercles was 55.656 ± 3.780 mm, thickness of the upper pubic symphysis was 10.510 ± 0.814 mm, and distance between upper and lower pubic symphysis was 40.872 ± 1.211 mm; the distance between round ligament of the uterus and pubic tubercle was 4.408 ± 0.304 mm, and the distance between spermatic cord and pubic tubercle was 5.196 ± 0.251 mm. The angle between canulated screw guide pin and horizontal plane was 8.342 ± 2.152°, the one between guide pin and coronal plane was 5.236 ± 1.612°, and the distance from entry point to the outer edge of pubic tubercle was 10.023 ± 1.245 mm, which was measured by Mimics software. Percutaneous surgery at horizontal position was simulated on cadaver. And the screw was correctly placed in postoperative imaging examination. According to the anatomical data and finite element studies of screw channel parameter in percutaneous fixation of canulated screw for symphyseolysis, the method can improve the accuracy of screw placement and reduce complications. PMID:25388836

  19. Interfragmentary screw fixation of the zygomatic arch in complex midface and zygomaticomaxillary fractures.

    PubMed

    Ribeiro Ribeiro, André Luis; de Souza Rodrigues, Tânia Maria; de Melo Alves-Junior, Sérgio; de Jesus Viana Pinheiro, João

    2015-03-01

    Zygomatic arch reduction and fixation is a key point in the treatment of complex midface and zygomaticomaxillary fractures. High-impact frontal trauma can cause posterior displacement of zygomatic bone, with a sagittal fracture of the root of the zygomatic arch extending posteriorly to the glenoid fossa. Miniplate and screw fixation of this fracture requires a large detachment of soft tissue, thus being technically more difficult for proper fixation and increasing the risk of soft tissue damage. This report describes an operative approach for fixation of this type of fracture using an adaptation of the lag screw technique. After the initial reduction of zygomatic bone, the proximal segment of the zygomatic arch containing the sagittal fracture is anatomically reduced and a 2.0-mm titanium screw is placed with an inferior inclination of 10° to 15° into the mastoid cells of the temporal bone, thus avoiding intracranial screw placement. This technique showed excellent results in reduction and long-term stability. It facilitates the surgical procedure, decreases the risk of soft tissue damage, and can lower costs compared with conventional miniplate and screw fixation. PMID:25544298

  20. Cervical anterior transpedicular screw fixation. Part I: Study on morphological feasibility, indications, and technical prerequisites

    Microsoft Academic Search

    Heiko Koller; Axel Hempfing; Frank Acosta; Michael Fox; Armin Scheiter; Mark Tauber; Ulrich Holz; Herbert Resch; Wolfgang Hitzl

    2008-01-01

    Multilevel cervical spine procedures can challenge the stability of current anterior cervical screw-and-plate systems, particularly\\u000a in cases of severe three-column subaxial cervical spine injuries and multilevel plated reconstructions in osteoporotic bone.\\u000a Supplemental posterior instrumentation is therefore recommended to increase primary construct rigidity and diminish early\\u000a failure rates. The increasing number of successfully performed posterior cervical pedicle screw fixations have enabled

  1. Spinal pedicle finder for transpedicular screw fixation--design and early clinical result.

    PubMed

    Wu, S S; Liang, P L; Pai, W M; Au, M K; Lin, L C

    1990-12-01

    Spinal transpedicular fixation has gained widespread popularity in the past 5 years. In biomechanical studies, the deeply-inserted transpedicular screws withstood the largest number of cycles in the cephalad-caudad and medial-lateral direction before failure. However, in clinical practice, the risk of screw placement which is too far medially or too far laterally do exist. The optimization of increasing screw depth to avoid complication is of significant clinical importance. A Spinal Pedicle Finder (S.P.F) has been designed for transpedicular screws and a prototype has been completed. It is composed of an I-shaped body with a pair of front rails and a pair of rear rails. The front rail comprises two positioning arms that fit against the laminal bony crest, and the rear rail comprises two guiding bases that provide the transpedicular pin inserted with a specific angle. Both positioning arms and both guiding bases can be adjusted synchronously, and the specific angle over the guiding bases can be pre-set preoperatively according to the angle of pedicle axis. To date, in 7 cases (5 fracture and 2 spondylolisthesis) transpedicular screw fixation has been applied by aid of the S.P.F. Two-level fixation was applied in a fracture group and three-level fixation was applied in a spondylolisthesis group. The position of the transpedicular screw has been checked by CT scan postoperatively. A total of 32 transpedicular screws were inserted and all were in the pedicle and vertebral body except in one instances. One transpedicular screw was malpositioned on one side, partially lateral to the pedicle. However, this malposition did not cause any neurologic problem, such as dural tear, nerve root injury or other. Clinical experience has demonstrated its efficacy and safety. PMID:2101447

  2. Antegrade-retrograde opposing lag screws for internal fixation of simple displaced talar neck fractures.

    PubMed

    Abdelkafy, Ashraf; Imam, Mohamed Abdelnabi; Sokkar, Sherif; Hirschmann, Michael

    2015-01-01

    The talar neck is deviated medially with reference to the long axis of the body of the talus. In addition, it deviates plantarward. The talar neck fracture line is sometimes observed to be oriented obliquely (not perpendicular to the long axis of the talar neck). This occurs when the medially deviated talar neck strikes the horizontally oriented anterior lower tibial edge. Internal fixation of a simple displaced talar neck fracture usually requires 2 lag screws. Because the fracture line is obliquely oriented, a better method for positioning the screws perpendicular to the fracture line is to place them in a reversed direction to provide maximum interfragmentary compression at the fracture site, which could increase the likelihood of absolute stability with subsequent improvement in the incidence of fracture union and a reduction of complications, such as avascular necrosis of the body of the talus. Two lag screws are used, with the first inserted from posteriorly to anteriorly (perpendicular to the fracture line) using a medial approach after medial malleolar chevron osteotomy. The second screw is inserted from anteriorly to posteriorly (perpendicular to the fracture line) using an anterolateral approach. Both screw heads should be countersunk. A series of 8 patients underwent this form of internal fixation for talar neck fracture repair, with satisfactory functional outcomes. In conclusion, the use of antegrade-retrograde opposing lag screws is a reasonable method of internal fixation for simple displaced talar neck fractures. PMID:25459087

  3. Percutaneous screw fixation of a vertebral pedicle fracture under CT-guidance: a new technique.

    PubMed

    Amoretti, Nicolas; Marcy, Pierre-Yves; Hauger, Olivier; Browaeys, Patrick; Amoretti, Marie-eve; Hoxorka, Istvan; Boileau, Pascal

    2012-03-01

    We report on a new minimally invasive technique for the vertebral pedicle fracture after placement of a prosthetic disc. This intervention is an adaptation of CT-guided sacroiliac and acetabular fracture screw fixation. This type of procedure enables the perfect placement and measurement of the screw, as well as an extremely small incision under local anesthesia. CT guided Transpedicular fixation could be a useful strategy in the treatment of future cases involving poorly healing pedicle fractures causing persistent symptoms. This intervention confirms the range of capacities of CT scan-controlled interventions in terms of precision, safety, speed, minimal invasiveness, rapid return to everyday activity and consequently, economical management. PMID:21353413

  4. The sustentaculum tali screw fixation for the treatment of Sanders type II calcaneal fracture: A finite element analysis

    PubMed Central

    Pang, Qing-Jiang; Yu, Xiao; Guo, Zong-Hui

    2014-01-01

    Objective: In the surgery of calcaneal fracture, whether the sustentaculum tali screw should always be placed is widely controversial. The aim of this study was to explore the necessity and function of the sustentaculum tali screw placement for the treatment of Sanders type II calcaneal fracture. Methods: The finite element analysis was used in this study. After the establishment of the finite element model of Sanders type II calcaneal fracture, the two internal fixation simulations were designed. In one model, the AO calcaneal plate was simulated on the lateral side of the calcanues with 7 screws being fixated at different position of the plate. In the other model, the calcaneus was fixated with the same AO calcaneal plate together with an additional screw being infiltrated into the sustentaculum tali. The two models were simulated under the same loading and the displacement of the fracture line and the stress distribution in the two models were calculated respectively. Results: The maximum principal stress focused on the cortical bone of sustentaculum tali in both the models under the same loading. The displacement of the fracture line, the maximum principal stress of calcaneus and internal fixation system in the model with sustentaculum screw fixation were smaller than that in the model without sustentaculum screw fixation. The stress in the model with sustentaculum screw fixation was more dispersed. Conclusions: The placement of sustentaculum tali screw is essential for fixation of type II calcaneal fracture to achieve the biomechanical stability. PMID:25225534

  5. Use of resorbable screws for autogenous onlay block graft fixation: a histological analysis in rabbits.

    PubMed

    Klüppel, Leandro Eduardo; Stabile, Glaykon Alex Vitti; Antonini, Fernando; Nascimento, Frederico Felipe; de Moraes, Marcio; Mazzonetto, Renato

    2015-02-01

    The aim of the present in vivo study is to histologically evaluate and compare the use of resorbable screws based on poly(L-co-D,L lactide) 70:30 for fixation of autogenous bone grafts in rabbit tibiae. As control group, titanium (Ti-6Al-4V Grade V) screws were used. For this purpose, 15 white New Zealand male rabbits, aged 6 months and weighing between 3.8 and 4.5 kg, were used. From each animal, 2 total-thickness bone grafts were removed from the cranial vault: one was stabilized with a resorbable screw while the other was stabilized with a metallic one. Animals were divided into 3 groups, according to the sacrifice period: 3, 8, and 16 weeks postoperatively. After histological processing, cuts were stained with hematoxylin and eosin and submitted for descriptive histological analysis under light microscopy. It was found that the fixation system based on the polymer showed a histological behavior similar to metallic screws. For both groups, the bone graft was incorporated, with the presence of bone formation between the graft and receptor site. In none of the groups were undesirable inflammatory responses or foreign body reactions observed. Based on histological findings and on this experimental model, it is possible to conclude that the internal fixation system based on the poly(L-co-D,L lactide) 70:30 polymer is effective for fixation of autogenous bone grafts, with results that are comparable to the titanium fixation system. PMID:23414521

  6. [Biomechanical properties of bioabsorbable cannulated screws for surgical fixation of dislocated epiphysiolysis capitis femoris].

    PubMed

    Kröber, M W; Rovinsky, D; Lotz, J; Carstens, C; Otsuka, N Y

    2002-06-01

    Bioabsorbable materials are well suited for fixation of slipped capital femoral epiphysis (SCFE) as they are resorbable, compatible with magnetic resonance imaging, and well tolerated by the pediatric population. We compared cannulated 4.5-mm bioabsorbable screws made of self-reinforced polylevolactic acid (SR-PLLA) to cannulated 4.5-mm steel and titanium screws for their resistance to shear stress and ability to generate compression in a polyurethane foam model of SCFE fixation. The maximum shear stress resisted by the three screw types was similar (SR-PLLA 371 +/- 146, steel 442 +/- 43, titanium 470 +/- 91 MPa, NS). The maximum compression generated by both the SR-PLLA screw (68.5 +/- 3.3 N) and the steel screw (63.3 +/- 5.9 N) was greater than that for the titanium screw (3.0 +/- 1.4 N, p < 0.05). These data suggest that cannulated SR-PLLA screws have sufficient biomechanical strength to be used in the treatment of SCFE. PMID:12149928

  7. Cannulated screw and hexapodal fixator reconstruction for compound upper tibial fractures

    PubMed Central

    Uzun, Metin; Bilen, Fikri Erkal; Eralp, Levent

    2014-01-01

    Objectives: The aim of the treatment of tibial plateau fractures is to obtain a pain-free and fully functional knee with closed reduction, percutaneous cannulated screw fixation and hexapodal external fixator reconstruction for high energy compound upper tibial fractures. Methods: Patients with comminuted tibial plateau fractures underwent closed reduction, percutaneous fixation with cannulated screws, and reconstruction with hexapodal external fixator. The follow-up period was 24 months. Results: The clinical and radiological results were good or excellent. The average knee flexion was 125°. Conclusion: Our results are successful in the initial stage, however, it should be pointed out that during the long term follow-up osteoarthritis may develop leading to worsening of the condition. Level of Evidence IV, Case Series. PMID:24644420

  8. Lateral fixation of AO type-B2 ankle fractures: the Acutrak plus compression screw technique

    Microsoft Academic Search

    Yih-Shiunn Lee; Tzu-Liang Hsu; Chien-Rae Huang; Shih-Hao Chen

    2010-01-01

    The Acutrak plus compression screw (APCS) (Acumed Inc., Beaverton, OR, USA) is an intramedullary implant which can achieve\\u000a stable fixation with minimum soft tissue dissection. The characteristics of the APCS include fully-threaded length, headless,\\u000a cannulated, and variable thread pitch. Twenty-three patients with AO type-B2 ankle fractures treated with lateral fixation\\u000a by an APCS were retrospectively reviewed. Evaluation of postoperative roentgenograms

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

    PubMed

    Hananouchi, Takehito

    2015-04-01

    Femoroplasty is theoretically a prophylactic surgical procedure for femoral neck fracture. Although bone cement is generally used for augmentation, its distribution cannot be easily controlled. This study investigated whether a bioactive screw is feasible for femoroplasty as an alternative augmentation material. A mechanical test was done to compare the strength of four types of augmentation bioactive screw (Superfixsorb), two bioinert cements, or no intervention in a composite femoral bone. The peak load to fracture under simulated falling was compared among the four groups. The mean peak load to failure in the bioactive screw group (2667 N) was significantly higher than that in the intact group (2391 N) (p=0.028), comparable to that in the Simplex P cement group (2864 N) (p=0.11), and significantly lower than that of the cranioplastic cement group (3022 N) (p=0.006). The strength of a composite femur with the bioactive screw was higher than that of an intact bone and comparable to one cement augmentation. Thus, this bioactive screw can be potentially used as augmentation material for femoroplasty. PMID:25581740

  10. Computed tomography-guided percutaneous facet screw fixation in the lumbar spine. Technical note.

    PubMed

    Kang, Ho Yeong; Lee, Sang-Ho; Jeon, Sang Hyeop; Shin, Song-Woo

    2007-07-01

    The authors describe a new minimally invasive technique for posterior supplementation using percutaneous translaminar facet screw (TFS) fixation with computed tomography (CT) guidance. Oblique axial images were used to determine facet screw fixation sites. After the induction of local anesthesia and conscious sedation, a guide pin was inserted and guided with a laser mounted on the CT gantry. Cannulated TFSs were placed via a percutaneous approach. From December 2002 to August 2003, 18 patients underwent CT-guided TFS. In 17 of these patients this procedure was supplementary to anterior lumbar interbody fusion, which had been performed several days earlier; in the remaining patient, CT-guided TFS fixation was undertaken as the primary therapy. Twelve patients had painful degenerative disc disease or unstable degenerative spondylolisthesis, three had infections, and three had deformities. All screws were inserted accurately and there were no complications. This new minimally invasive surgical technique may offer an alternative to pedicle screw fixation as a method of posterior supplementation. PMID:17633496

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

    PubMed Central

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

    2012-01-01

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

  12. 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

    2014-01-15

    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. PMID:24436361

  13. Posterior interbody fusion using a diagonal cage with unilateral transpedicular screw fixation for lumbar stenosis.

    PubMed

    Zhao, Jian; Zhang, Feng; Chen, Xiaoqing; Yao, Yu

    2011-03-01

    Few reports have described the combined use of unilateral pedicle screw fixation and interbody fusion for lumbar stenosis. We retrospectively reviewed 79 patients with lumbar stenosis. The rationale and effectiveness of unilateral pedicle screw fixation were studied from biomechanical and clinical perspectives, aiming to reduce stiffness of the implant. All patients were operated with posterior interbody fusion using a diagonal cage in combination with unilateral transpedicular screw fixation and had reached the 3-year follow-up interval after operation. The mean operating time was 115 minutes (range=95-150 min) and the mean estimated blood loss was 150 mL (range=100-200 mL). The mean duration of hospital stay was 10 days (range=7-15 days). Clinical outcomes were assessed prior to surgery and reassessed at intervals using Denis' pain and work scales. Fusion status was determined from X-rays and CT scans. At the final follow-up, the clinical results were satisfactory and patients showed significantly improved scores (p<0.01) either on the pain or the work scale. Successful fusion was achieved in all patients. There were no new postoperative radiculopathies, or instances of malpositioned or fractured hardware. Posterior interbody fusion using a diagonal cage with unilateral transpedicular fixation is an effective treatment for decompressive surgery for lumbar stenosis. PMID:21237659

  14. Mid-Term Results of Computer-Assisted Cervical Pedicle Screw Fixation

    PubMed Central

    Uehara, Masashi; Mukaiyama, Keijiro; Kuraishi, Shugo; Shimizu, Masayuki; Ikegami, Shota; Futatsugi, Toshimasa; Ogihara, Nobuhide; Hashidate, Hiroyuki; Hirabayashi, Hiroki; Kato, Hiroyuki

    2014-01-01

    Study Design A retrospective study. Purpose The present study aimed to evaluate mid-term results of cervical pedicle screw (CPS) fixation for cervical instability. Overview of Literature CPS fixation has widely used in the treatment of cervical spinal instability from various causes; however, there are few reports on mid-term surgical results of CPS fixation. Methods Record of 19 patients who underwent cervical and/or upper thoracic (C2-T1) pedicle screw fixation for cervical instability was reviewed. The mean observation period was 90.2 months. Evaluated items included Japanese Orthopaedic Association (JOA) score and C2-7 lordotic angle before surgery and at 5 years after surgery. Postoperative computerized tomography was used to determine the accuracy of screw placement. Visual analog scale (VAS) for neck pain and radiological evidence of adjacent segment degeneration (ASD) at the 5-year follow-up were also evaluated. Results Mean JOA score was significantly improved from 9.0 points before surgery to 12.8 at 5 years after surgery (p=0.001). The C2-7 lordotic angle of the neutral position improved from 6.4° to 7.8° at 5 years after surgery, but this was not significant. The major perforation rate was 5.0%. There were no clinically significant complications such as vertebral artery injury, spinal cord injury, or nerve root injury caused by any screw perforation. Mean VAS for neck pain was 49.4 at 5 years after surgery. The rate of ASD was 21.1%. Conclusions Our mid-term results showed that CPS fixation was useful for treating cervical instability. Severe complications were prevented with the assistance of a computed tomography-based navigation system. PMID:25558318

  15. Evaluation of a new approach for modelling the screw-bone interface in a locking plate fixation: a corroboration study.

    PubMed

    Moazen, Mehran; Mak, Jonathan H; Jones, Alison C; Jin, Zhongmin; Wilcox, Ruth K; Tsiridis, Eleftherios

    2013-07-01

    Computational modelling of the screw-bone interface in fracture fixation constructs is challenging. While incorporating screw threads would be a more realistic representation of the physics, this approach can be computationally expensive. Several studies have instead suppressed the threads and modelled the screw shaft with fixed conditions assumed at the screw-bone interface. This study assessed the sensitivity of the computational results to modelling approaches at the screw-bone interface. A new approach for modelling this interface was proposed, and it was tested on two locking screw designs in a diaphyseal bridge plating configuration. Computational models of locked plating and far cortical locking constructs were generated and compared to in vitro models described in prior literature to corroborate the outcomes. The new approach led to closer agreement between the computational and the experimental stiffness data, while the fixed approach led to overestimation of the stiffness predictions. Using the new approach, the pattern of load distribution and the magnitude of the axial forces, experienced by each screw, were compared between the locked plating and far cortical locking constructs. The computational models suggested that under more severe loading conditions, far cortical locking screws might be under higher risk of screw pull-out than the locking screws. The proposed approach for modelling the screw-bone interface can be applied to any fixation involved application of screws. PMID:23636756

  16. A Comparison of Functional Outcomes After Metallic and Bioabsorbable Interference Screw Fixations in Arthroscopic ACL Reconstructions

    PubMed Central

    Rai, Deepak K; Kannampilly, Antony J

    2014-01-01

    Introduction: Anterior Cruciate Ligament (ACL) is as one of the most frequently injured ligaments in the modern contact sports scenario. Graft fixations can be achieved during anterior cruciate ligament (ACL) reconstructions by using either bioabsorbable screws or metal screws. The objective of this study was to compare the functional outcomes after bioabsorbable and metallic interference screw fixations in arthroscopic anterior cruciate ligament reconstructions done by using hamstring grafts. Materials and Methods: This was a prospective, randomized study. Patients in Group 1 received bioabsorbable interference screws and patients in Group 2 received metallic interference screws. Arthroscopic assisted, anterior cruciate ligament reconstructions with the use of hamstring grafts which were fixed proximally with endobuttons and distally with bioabsorbable or metallic interference screws, were undertaken. Progress in functional outcomes was assessed by using Mann Whitney U- test. Functional outcomes in the two groups were compared by using independent t-test. Observation and Results: In each group, there were statistically significant improvements in functional outcomes over successive follow-ups, which were seen on basis on Mann-Whitney U-test. The comparison of functional outcomes between the two groups, done by using independent t-test, showed no statistically significant differences between the two groups at 3 months, 6 months and 1 year of follow-up. p-value <0.05 was considered to be significant in our study. Conclusion: In our prospective study of comparison of functional outcomes between bioabsorbable and metallic interference screws in arthroscopic anterior cruciate ligament reconstuctions, which were evaluated by using Tegner activity scale and Lysholm knee scoring scale for a period of 1 year, no statistically significant difference was found. However, further authentication is required by doing long term studies. PMID:24959468

  17. Screw fixation diameter for fifth metatarsal jones fracture: a cadaveric study.

    PubMed

    Scott, Ryan T; Hyer, Christopher F; DeMill, Shyler L

    2015-01-01

    The fifth metatarsal Jones fracture is a well-documented injury occurring at the proximal diaphyseal-metaphyseal junction. Conservative versus surgical intervention has been discussed in published studies for the management of Jones fractures. Solid intramedullary fixation relies on accurate matching of the screw diameter to the intraosseous diameter. The purpose of the present cadaveric study was to determine the average intraosseous diameter of the proximal fifth metatarsal as it relates to screw size selection for Jones fracture stabilization. Twenty fresh-frozen cadaver legs were used for examination. The fifth metatarsal was completely dissected. A transverse osteotomy was performed from laterally to medially along the midline of the metatarsal. A digital caliper was used to measure the diameter of the medullary canal of the fifth metatarsal. The measurement was taken at the narrowest portion of the medullary canal just distal to the proximal metaphysis. The mean dorsal to plantar diameter of the fifth metatarsal was 6.475 ± 1.54 (range 4 to 12) mm and the mean medial to lateral diameter was 4.6 ± 0.85 (range 3 to 6) mm. Intramedullary screw fixation has shown beneficial results in the treatment protocol of fifth metatarsal Jones fractures. Our study has demonstrated that a 4.5-mm cannulated screw is the narrowest diameter screw that can be used in the average fifth metatarsal and still obtain adequate intraosseous purchase. When selecting the appropriate screw, the surgeon must be comfortable selecting the largest screw that will achieve the maximal interface with the dense cortical bone in both the medial to lateral and dorsal to plantar plane. PMID:25624041

  18. A new technique for lag screw placement in the dynamic hip screw fixation of intertrochanteric fractures: decreasing radiation time dramatically

    PubMed Central

    Sheng, Wei-Chao; Li, Jia-Zhen; Chen, Sheng-Hua

    2008-01-01

    The goal of this study was to confirm the decrease in radiation time required for a new technique to place dynamic hip screws (DHS) in intertrochanteric fractures. Seventy-six patients were treated with DHS by either the new technique (NT) or the conventional technique (CT). The width of femoral shaft, the length of the hip screw to be implanted into the injured side, and the distance between the tip of the greater trochanter and the entry point of the guide wire were measured at the uninjured side on the anteroposterior pelvic radiograph preoperatively, and the actual width of the injured femoral shaft was measured intra-operatively. Finally, the entry point and the length of hip screw were obtained through an equation. Mean radiation time of the NT patients (24.57?±?7.80 s) was significantly shorter than the CT patients (54.2?±?18.26 s) (P??fixation. PMID:18265981

  19. Comparison between Bilateral C2 Pedicle Screwing and Unilateral C2 Pedicle Screwing, Combined with Contralateral C2 Laminar Screwing, for Atlantoaxial Posterior Fixation

    PubMed Central

    Hongo, Michio; Kobayashi, Takashi; Suzuki, Tetsuya; Abe, Eiji; Shimada, Yoichi

    2014-01-01

    Study Design A retrospective study. Purpose To compare clinical and radiological outcomes between bilateral C2 pedicle screwing (C2PS) and unilateral C2PS, combined with contralateral C2 laminar screwing (LS), for posterior atlantoaxial fixation. Overview of Literature Posterior fixation with C1 lateral mass screwing (C1LMS) and C2PS (C1LMS-C2PS method) is an accepted procedure for rigid atlantoaxial stabilization. However, conventional bilateral C2PS is not always allowed in this method due to anatomical variations of C2 pedicles and/or asymmetry of the vertebral artery. Although unilateral C2PS plus contralateral LS (C2PS+LS) is an alternative in such cases, the efficacy of this procedure has not been evaluated in controlled studies (i.e., with bilateral C2PS as a control). Methods Clinical and radiological records of patients who underwent the C1LMS-C2PS method, using unilateral C2PS+LS (n=9), and those treated using conventional bilateral C2PS (n=10) were compared, with a minimum two years follow-up. Results Postoperative complications related to the unilateral C2PS+LS technique included one case of spontaneous spinous process fracture of C2. A C1 anterior arch fracture occurred after a fall in one patient, who underwent bilateral C2PS and C1 laminectomy. No significant differences were seen between the groups in reduction of neck pain after surgery or improvement of neurological status, as evaluated using the Japanese Orthopaedic Association score. A delayed union occurred in one patient each of the groups, with the final fusion rate being 100% in both groups. Conclusions Clinical and radiological outcomes of unilateral C2PS+LS were comparable with those of the bilateral C2PS fixation technique for the C1LMS-C2PS method. PMID:25558320

  20. Transpedicular screw fixation for type II Hangman’s fracture: a motion preserving procedure

    PubMed Central

    ElMiligui, Yasser; Emran, Ihab

    2010-01-01

    Opinions have varied regarding the optimal treatment of an unstable Hangman’s fracture. C2 pedicle screw instrumentation is a biomechanically strong fixation which although done through a simple posterior approach, is a technically demanding procedure. This prospective, non-randomized multicentre study included 15 consecutive patients with displaced type II traumatic spondylolisthesis of the axis. There were nine males and six females with a mean age of 37 years at surgery. The cause of injury was a road traffic accident in 11 patients and a fall from height in 4 patients. All patients had a single stage reduction and direct transpedicular screw fixation through the C2 pedicles. During follow-up, clinical evaluation and plain X-rays were performed at each visit; at 6-month follow-up, additional dynamic lateral flexion/extension views and a CT scan were performed. The average follow-up period was 32 months (range 25–56 months). At final follow-up, all patients were asymptomatic and regained a good functional outcome with no limitation of range of motion; all the patients showed solid union with no implant failure. There were no neurological complications. At 6-month follow-up, CT evaluation showed fusion in all patients and an adequate position of 28 screws. Two pedicle screws (6.6%) showed minimal (defined as <2 mm) intrusion; one into the spinal canal and the other into the vertebral foreamen. Transpedicular screw fixation through the C2 pedicles is a safe and effective method in treating type II traumatic spondylolisthesis of the axis resulting in good clinical and radiological outcomes. Adequate reduction was achieved and motion segments were preserved with its use. PMID:20401619

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

    Microsoft Academic Search

    Alex H. Greene; Joel D. Bumgardner; Yunzhi Yang; Jon Moseley; Warren O. Haggard

    2008-01-01

    Stainless steel screws and other internal fixation devices are used routinely to stabilize bacteria-contaminated bone fractures\\u000a from multiple injury mechanisms. In this preliminary study, we hypothesize that a chitosan coating either unloaded or loaded\\u000a with an antibiotic, gentamicin, could lessen or prevent these devices from becoming an initial nidus for infection. The questions\\u000a investigated for this hypothesis were: (1) how

  2. Single screw fixation in stable and unstable slipped upper femoral epiphysis.

    PubMed

    Mulgrew, Emma; Wells-Cole, Simon; Ali, Farhan; Joshy, Suraj; Siddique, Irfan; Zenios, Michalis

    2011-05-01

    The aim of this single centre retrospective study was to assess the outcome of patients after the fixation of slipped upper femoral epiphysis (SUFE) using a single cannulated screw. Thirty-eight slips, 28 stable and 10 unstable were treated with single in-situ screw fixation. The minimum follow-up was 1 year. The overall adverse outcome in terms of avascular necrosis (AVN), chondrolysis and revision surgery for slip progression was 18%, which was considered satisfactory. Slip progression of more than 10° was higher in the unstable when compared with the stable group but not statistically significant. Two out of the nine satisfactorily fixed unstable slips required revision surgery as opposed to none in the stable group. The incidence of AVN in the unstable group was 20%. There were no cases of AVN in the stable group. The adverse outcome in terms of AVN, chondrolysis and revision surgery for slip progression was significantly higher in the unstable group. In our study, results of single screw fixation for SUFE were found to be satisfactory as shown by earlier studies with the unstable SUFEs as expected having a poorer outcome when compared with the stable SUFEs. PMID:21386718

  3. Tibial Inlay Press-fit Fixation Versus Interference Screw in Posterior Cruciate Ligament Reconstruction

    PubMed Central

    Ettinger, Max; Büermann, Sarah; Calliess, Tilman; Omar, Mohamed; Krettek, Christian; Hurschler, Christof; Jagodzinski, Michael; Petri, Maximilian

    2013-01-01

    Reconstruction of the posterior cruciate ligament (PCL) by a tibial press-fit fixation of the patellar tendon with an accessory bone plug is a promising approach because no foreign materials are required. Until today, there is no data about the biomechanical properties of such press-fit fixations. The aim of this study was to compare the biomechanical qualities of a bone plug tibial inlay technique with the commonly applied interference screw of patellar tendon PCL grafts. Twenty patellar tendons including a bone block were harvested from ten human cadavers. The grafts were implanted into twenty legs of adult German country pigs. In group P, the grafts were attached in a press-fit technique with accessory bone plug. In group S, the grafts were fixed with an interference screw. Each group consisted of 10 specimens. The constructs were biomechanically analyzed in cyclic loading between 60 and 250 N for 500 cycles recording elongation. Finally, ultimate failure load and failure mode were analyzed. Ultimate failure load was 598.6±36.3 N in group P and 653.7±39.8 N in group S (not significant, P>0.05). Elongation during cyclic loading between the 1st and the 20th cycle was 3.4±0.9 mm for group P and 3.1±1 mm for group S. Between the 20th and the 500th cycle, elongation was 4.2±2.3 mm in group P and 2.5±0.9 mm in group S (not significant, P>0.05). This is the first study investigating the biomechanical properties of tibial press-fit fixation of the patellar tendon with accessory bone plug in posterior cruciate ligament reconstruction. The implant-free tibial inlay technique shows equal biomechanical characteristics compared to an interference screw fixation. Further in vivo studies are desirable to compare the biological behavior and clinical relevance of this fixation device. PMID:24416479

  4. Arthroscopic reduction and internal fixation of acetabular fractures.

    PubMed

    Kim, Hyangkyoung; Baek, Ji-Hoon; Park, Sang-Min; Ha, Yong-Chan

    2014-04-01

    Arthroscopic reduction and screw fixation of acetabular fractures have not been reported. In this case report, arthroscopic treatment for acetabular fracture is reported for two patients. A 49-year-old man diagnosed with acetabular posterior wall fracture was treated by arthroscopic reduction and fixation using two screws. A 20-year-old woman who diagnosed with anterior column fracture was fixed using a screw using the arthroscopic technique prior to open reduction and internal fixation in the iliac bone fracture. Arthroscopic reduction and fixation in some case of acetabular fracture could be good indication with additional advantages of joint debridement and loose body removal. PMID:24306124

  5. Unilateral Posterior Atlantoaxial Transarticular Screw Fixation in Patients with Atlantoaxial Instability : Comparison with Bilateral Method

    PubMed Central

    Hue, Yun Hee; Yi, Hyeong-Joong; Oh, Seong Hoon; Oh, Suck Jun; Ko, Yong

    2009-01-01

    Objective Bilateral C1-2 transarticular screw fixation (TAF) with interspinous wiring has been the best treatment for atlantoaxial instability (AAI). However, several factors may disturb satisfactory placement of bilateral screws. This study evaluates the usefulness of unilateral TAF when bilateral TAF is not available. Methods Between January 2003 and December 2007, TAF was performed in 54 patients with AAI. Preoperative studies including cervical x-ray, three dimensional computed tomogram, CT angiogram, and magnetic resonance image were checked. The atlanto-dental interval (ADI) was measured in preoperative period, immediate postoperatively, and postoperative 1, 3 and 6 months. Results Unilateral TAF was performed in 27 patients (50%). The causes of unilateral TAF were anomalous course of vertebral artery in 20 patients (74%), severe degenerative arthritis in 3 (11%), fracture of C1 in 2, hemangioblastoma in one, and screw malposition in one. The mean ADI in unilateral group was measured as 2.63 mm in immediate postoperatively, 2.61 mm in 1 month, 2.64 mm in 3 months and 2.61 mm in 6 months postoperatively. The mean ADI of bilateral group was also measured as following; 2.76 mm in immediate postoperative, 2.71 mm in 1 month, 2.73 mm in 3 months, 2.73 mm in 6 months postoperatively. Comparison of ADI measurement showed no significant difference in both groups, and moreover fusion rate was 100% in bilateral and 96.3% in unilateral group (p=0.317). Conclusion Even though bilateral TAF is best option for AAI in biomechanical perspectives, unilateral screw fixation also can be a useful alternative in otherwise dangerous or infeasible cases through bilateral screw placement. PMID:19352478

  6. C1-c2 pedicle screw fixation for treatment of old odontoid fractures.

    PubMed

    Qi, Lei; Li, Mu; Zhang, Shuai; Si, Haipeng; Xue, Jingsong

    2015-02-01

    Nonunion and C1-C2 instability of odontoid fractures usually result from delayed diagnosis and inappropriate treatment. However, the available treatment options for odontoid fractures remain controversial. The authors evaluated the effectiveness of internal screw fixation via the C1 and C2 pedicle in cases of old odontoid fractures. This retrospective study included 21 patients with old odontoid fractures (13 men and 8 women; mean age, 46.5 years; range, 24-69 years). Internal screw fixation via the C1 and C2 pedicle was performed in all patients. Fracture reduction and C1-C2 fusion were assessed with imaging. The neck pain visual analog scale score and cervical spinal cord functional Japanese Orthopaedic Association score (for those who had cervical spinal cord injury) were used to evaluate the effectiveness of treatment. Postoperative complications were recorded. Postoperative imaging showed that the C1-C2 dislocation was satisfactorily repositioned in all patients. Bone fusion was observed 1 year after surgery in all patients. No loosening or breaking of internal fixation occurred. The preoperative neck pain visual analog scale score was 5.9±1.5 and improved significantly to 1.8±0.8 after surgery (P<.001). The Japanese Orthopaedic Association score in patients with cervical spinal injury (n=14) was 9.2±1.9 and also significantly improved to 13.8±1.9 at the last follow-up examination (P<.001), with an average improvement rate of 61.0%. No iatrogenic vertebral artery injury or severe spinal cord injury occurred. Screw fixation via the C1 and C2 pedicle was found to be an effective and safe surgical approach for the treatment of old odontoid fractures with C1-C2 dislocation or instability. PMID:25665108

  7. Open reduction and internal fixation of patellar fractures with tension band wiring through cannulated screws.

    PubMed

    Malik, Mudasir; Halwai, Manzoor Ahmad

    2014-10-01

    The purpose of this study was to evaluate effectiveness and safety of a relatively new technique of open reduction and internal fixation of displaced transverse patellar fractures with tension band wiring (TBW) through parallel cannulated compression screws. A total of 30 patients with displaced transverse patellar fracture were enrolled in this prospective study. Of the 30 patients, 20 patients had trauma due to fall, 5 due to road traffic accident, 2 due to fall of heavy object on the knee, 2 due to forced flexion of knee, and 1 had fracture due to being beaten. All 30 patients were treated with vertical skin exposure, fracture open reduction, and internal fixation by anterior TBW through 4.0?mm cannulated screws. The postoperative rehabilitation protocol was standardized. The patients were followed postsurgery to evaluate time required for radiographic bone union, knee joint range of motion (ROM), loss of fracture reduction, material failure, and the overall functional result of knee using Bostman scoring. All the fractures healed radiologically, at an average time of 10.7 weeks (range, 8-12 weeks). The average ROM arc was 129.7 degrees (range, 115-140 degrees). No patient had loss of fracture reduction, implant migration, or material failure. The average Bostman score was 28.6 out of 30. Anterior TBW through cannulated screws for displaced transverse fractures is safe and effective alternative treatment. Good functional results and recovery can be expected. PMID:24414389

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

    PubMed Central

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

    2015-01-01

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

  9. Multifragmentary Tibial Pilon Fractures: Midterm Results After Osteosynthesis with External Fixation and Multiple Lag Screws

    PubMed Central

    Kiene, Johannes; Herzog, Jan; Jürgens, Christian; Paech, Andreas

    2012-01-01

    Osteosynthesis of intraarticular tibial pilon fractures is preferably achieved using locking plates via a minimally invasive technique. If combined with severe soft tissue damage there is a high risk of wound-healing deficits after plate osteosynthesis. Thus our aim was to find an alternative method of treatment for those cases with combined soft tissue injuries. We report on five cases with comminuted fractures of the joint surface combined with critical soft tissue condition that were treated with lag screws and external fixation (AO) applied across the ankle joint. All five patients were followed up, undergoing clinical and radiological examination. Using this approach we achieved fracture healing of comminuted fractures without further complications. Clinical follow-up after an average of 55.6 (36–75) months revealed a mean AOFAS score of 81 (62–100). We therefore propose combined treatment using lag screws with external fixation as a practical treatment option for those fractures for which lag screws combined with a locking plate are not feasible or when there is a high risk of wound-healing deficits due to severe soft tissue damage. PMID:23002413

  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. CT-Guided Transfacet Pedicle Screw Fixation in Facet Joint Syndrome: A Novel Approach.

    PubMed

    Manfré, Luigi

    2014-10-31

    Axial microinstability secondary to disc degeneration and consequent chronic facet joint syndrome (CFJS) is a well-known pathological entity, usually responsible for low back pain (LBP). Although posterior lumbar fixation (PIF) has been widely used for lumbar spine instability and LBP, complications related to wrong screw introduction, perineural scars and extensive muscle dissection leading to muscle dysfunction have been described. Radiofrequency ablation (RFA) of facet joints zygapophyseal nerves conventionally used for pain treatment fails in approximately 21% of patients. We investigated a "covert-surgery" minimal invasive technique to treat local spinal instability and LBP, using a novel fully CT-guided approach in patients with axial instability complicated by CFJS resistant to radioablation, by introducing direct fully or partially threaded transfacet screws (transfacet fixation - TFF), to acquire solid arthrodesis, reducing instability and LBP. The CT-guided procedure was well tolerated by all patients in simple analogue sedation, and mean operative time was approximately 45 minutes. All eight patients treated underwent clinical and CT study follow-up at two months, revealing LBP disappearance in six patients, and a significant reduction of lumbar pain in two. In conclusion, CT-guided TFF is a fast and safe technique when facet posterior fixation is needed. PMID:25363265

  12. Fixation of the Lapidus arthrodesis with a plantar interfragmentary screw and medial low profile locking plate.

    PubMed

    Cottom, James M

    2012-01-01

    The Lapidus arthrodesis can be used to correct pathology within the forefoot or midfoot, and severe hallux valgus deformities as well as hypermobility of the medial column may be amenable to correction with this procedure. Many different skeletal fixation methods have been described for this procedure, and one form that appears to provide enough construct stability to allow patients to bear weight early in the postoperative period is described herein. This construct consists of an interfragmental compression screw oriented from the plantar aspect of the first metatarsal to the superior aspect of the medial cuneiform, with medial locking plate augmentation. PMID:22632842

  13. Odontoid Synchondrosis Fracture Treated by C1-2 Polyaxial Screw-Rod Fixation

    PubMed Central

    2014-01-01

    The synchondrosis between the dens and the body of axis normally fuses between 5 and 7 years of age. Until this age, synchondrosis fractures can occur in children. Most synchondrosis fractures are conventionally treated by external immobilization alone. We report a 10-year-old child with odontoid synchondrosis fracture who was treated by C1 lateral mass and C2 pars screw rod fixation with a successful outcome and discuss the possible reasons for occurrence of odontoid synchondrosis fracture in this older child as well as the indications for surgery in this condition. PMID:25024826

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

    PubMed

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

    2015-01-01

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

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

    PubMed Central

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

    2015-01-01

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

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

    PubMed

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

    2015-04-01

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

  17. Cervical anterior transpedicular screw fixation (ATPS)—Part II. Accuracy of manual insertion and pull-out strength of ATPS

    Microsoft Academic Search

    Heiko Koller; Frank Acosta; Mark Tauber; Michael Fox; Hudelmaier Martin; Rosmarie Forstner; Peter Augat; Rainer Penzkofer; Christian Pirich; H. Kässmann; Herbert Resch; Wolfgang Hitzl

    2008-01-01

    Reconstruction after multilevel decompression of the cervical spine, especially in the weakened osteoporotic, neoplastic or\\u000a infectious spine often requires circumferential stabilization and fusion. To avoid the additional posterior surgery in these\\u000a cases while increasing rigidity of anterior-only screw-plate constructs, the authors introduce the concept of anterior transpedicular\\u000a screw (ATPS) fixation. We demonstrated its morphological feasibility as well as its indications

  18. Improving fixation strength of pedicle screw by microarc oxidation treatment: an experimental study of osteoporotic spine in sheep.

    PubMed

    Shi, Lei; Wang, Ling; Zhang, Yang; Guo, Zheng; Wu, Zi-xiang; Liu, Da; Gao, Ming-xuan; Chen, Huan; Fu, Suo-chao; Lei, Wei

    2012-08-01

    Failure of fixation caused by loosening of pedicle screws in osteoporosis is a problem in spinal surgery. We compared the in vivo fixation strength between pedicle screws treated with microarc oxidation (MAO) and untreated screws in an osteoporotic model of ovariectomized sheep. The MAO treated and untreated screws were placed in lumbar vertebral bodies. After 3 months of implantation, biomechanical tests, micro-CT analysis, and histological observations were conducted to examine the performance of the two groups. At time 0, no significant difference was found between the two groups in biomechanical tests (p > 0.05); 3 months later, higher pull-out strength and load with less displacement were detected in the MAO-treated group (p < 0.05). Micro-CT analysis showed that the tissue mineral density, bone volume fraction, trabecular thickness, and trabecular number in the MAO-treated group were all higher than those in untreated group (p < 0.05), and trabecular spacing was smaller (p < 0.05). Histologically, the bone-implant interface in the MAO-treated group was better than that in untreated group (p < 0.05). In conclusion, pedicle screws with a bioactive surface treated by MAO can improve screw fixation strength in osteoporotic spines in sheep. PMID:22234960

  19. [Odontoid fracture: Long-term subarachnoid hemorrhage after anterior screw fixation. Case report and literature review].

    PubMed

    Le Corre, M; Suleiman, N; Lonjon, N

    2012-12-01

    Odontoid fractures have been classified by Anderson and D'Alonzo into three main categories. The most unstable injuries, type II fractures involve the base of the odontoid peg at the junction with the C2 body. Due to the proximity of vital neural structures, fracture of the odontoid process may result in instability and fatal neurological damage. Treatment aims to re-establish stability of the atlanto-axial complex by restoring the odontoid process. This may be achieved by conservative or surgical treatment. Anterior screw fixation of the odontoid peg is an interresting alternative surgical option but this technique has a significant complication rate. However, vascular injury is very rare with three case reported in the literature: one case of an intracranial vertebral artery (VA) injury, one case of a cervical internal carotid artery (ICA) injury and one case of anterior pseudoaneurysm of the spinal artery branch. We report a new case of long term vascular injury after screw fixation revealed by a subarachnoid hemorrhage. We discuss the incidence, the mechanisms of injury and the conditions necessary for the occurrence of this complication. PMID:22683208

  20. Outcome of Pedicle Screw Fixation and Monosegmental Fusion in Patients with Fresh Thoracolumbar Fractures

    PubMed Central

    Rohilla, Rajesh Kumar; Kamboj, Kulbhushan; Magu, Narender Kumar; Kaur, Kiranpreet

    2014-01-01

    Study Design Prospective clinical study. Purpose The present prospective study aims to evaluate the clinical, radiological, and functional and quality of life outcomes in patients with fresh thoracolumbar fractures managed by posterior instrumentation of the spine, using pedicle screw fixation and monosegmental fusion. Overview of Literature The goals of treatment in thoracolumbar fractures are restoring vertebral column stability and obtaining spinal canal decompression, leading to early mobilization of the patient. Methods Sixty-six patients (46 males and 20 females) of thoracolumbar fractures with neurological deficit were stabilized with pedicle screw fixation and monosegmental fusion. Clinical, radiological and functional outcomes were evaluated. Results The mean preoperative values of Sagittal index, and compression percentage of the height of the fractured vertebra were 22.75° and 46.73, respectively, improved (statistically significant) to 12.39°, and 24.91, postoperatively. The loss of correction of these values at one year follow-up was not statistically significant. The mean preoperative canal compromise (%) improved from 65.22±17.61 to 10.06±5.31 at one year follow-up. There was a mean improvement in the grade of 1.03 in neurological status from the preoperative to final follow-up at one year. Average Denis work scale index was 4.1. Average Denis pain scale index was 2.5. Average WHOQOL-BREF showed reduced quality of life in these patients. Patients of early surgery group (operated within 7 days of injury) had a greater mean improvement of neurological grade, radiological and functional outcomes than those in the late surgery group, but it was not statistically significant. Conclusions Posterior surgical instrumentation using pedicle screws with posterolateral fusion is safe, reliable and effective method in the management of fresh thoracolumbar fractures. Fusion helps to decrease the postoperative correction loss of radiological parameters. There is no correlation between radiographic corrections achieved for deformities and functional outcome and quality of life post spinal cord injury. PMID:24967043

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

    PubMed Central

    2011-01-01

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

  2. 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

  3. Mechanical analysis of femoral neck fracture fixation with dynamic condylar screw in synthetic bone

    PubMed Central

    Freitas, Anderson; Maciel, Rafael Almeida; Lima, Renato De Almeida; Souto, Diogo Ranier De Macedo; Ferrer, Marcelo De Almeida

    2014-01-01

    Objective: To analyze statistically results in biomechanical testing of fixation of femoral neck Pauwels type III fractures, on synthetic bone, with dynamic condylar screw (DCS) and control group. Methods: Ten synthetic bones of a national brand were used. Test Group: fixation was performed after osteotomy at 70o tilt using DCS plate with four holes. We analyzed the resistance of this fixation with 5 mm displacement and rotational deviation (Step 1) and with10 mm (Step 2). Control group: the models were tested in their integrity until the femoral neck fracture occurred. Results: The values of the test group in Step 1 showed a mean of 974N and SD = 114N. In Stage 2, we obtained on average 1335N and SD = 98N. The values in the control group were: 1544N, 1110N, 1359N, 1194N, 1437N, respectively. Statistical analysis using the Mann-Whitney test for comparison of the maximum force (N) between the test group and the control, in Step 2, demonstrated that there is no significant difference between the DCS and control plates (p = 0.91). Conclusion: There is no significant difference between the DCS boards and the control group exposed to full resistance. Level of Evidence III, Case Control. PMID:25328435

  4. Ideal screw entry point and projection angles for posterior lateral mass fixation of the atlas: an anatomical study.

    PubMed

    Simsek, Serkan; Yigitkanli, Kazim; Seçkin, Hakan; Comert, Ayhan; Acar, Halil I; Belen, Deniz; Tekdemir, Ibrahim; Elhan, Alaittin

    2009-09-01

    Although various posterior insertion angles for screw insertion have been proposed for C1 lateral mass, substantial conclusions have not been reached regarding ideal angles and average length of the screw yet. We aimed to re-consider the morphometry and the ideal trajections of the C1 screw. Morphometric analysis was performed on 40 Turkish dried atlas vertebrae obtained from the Department of Anatomy at the Medical School of Ankara University. The quantitative anatomy of the screw entry zone, trajectories, and the ideal lengths of the screws were calculated to evaluate the feasibility of posterior screw fixation of the lateral mass of the atlas. The entry point into the lateral mass of the atlas is the intersection of the posterior arch and the C1 lateral mass. The optimum medial angle is 13.5 +/- 1.9 degrees and maximal angle of medialization is 29.4 +/- 3.0 degrees . The ideal cephalic angle is 15.2 +/- 2.6 degrees , and the maximum cephalic angle is 29.6 +/- 2.6 degrees . The optimum screw length was found to be 19.59 +/- 2.20 mm. With more than 30 degrees of medial trajections and cephalic trajections the screw penetrates into the spinal canal and atlantooccipital joint, respectively. Strikingly, in 52% of our specimens, the height of the inferior articular process was under 3.5 mm, and in 70% was under 4 mm, which increases the importance of the preparation of the screw entry site. For accommodation of screws of 3.5-mm in diameter, the starting point should be taken as the insertion of the posterior arch at the superior end of the inferior articular process with a cephalic trajection. This study may aid many surgeons in their attempts to place C1 lateral mass screws. PMID:19644713

  5. A method for the fatigue testing of pedicle screw fixation devices.

    PubMed

    Goel, V K; Winterbottom, J M; Weinstein, J N

    1994-11-01

    Spinal devices/instrumentation are used to augment the stability of a decompressed spinal segment during surgery. Like any other mechanical component, the device can fail. A standard in vitro test protocol, was developed to determine load vs number of cycles to failure curve for a pedicle screw-plate/rod type spinal device. The protocol based on the use of an 'artificial spine' model, is clinically relevant. The protocol was used to characterize the load-carrying capacities and failure modes of a specific pedicle screw-rod type fixation device to demonstrate its appropriateness. The devices (Kaneda) were tested in the quasi-static as well as fatigue bending modes. In the bending fatigue mode, the devices failed at loads significantly smaller than the corresponding quasi-static failure load magnitude (806 N). The device exhibited an endurance limit in the fatigue bending mode. The device is not likely to exhibit failure if subjected to cyclic loads which cause less than 380 N axial compression (and an accompanying bending moment relative to the device of less than 13.57 Nm). The failures observed in specimens subjected to the fatigue tests ranged from complete to partial breakage of the paraspinal rods as opposed to failure due to permanent deformation (yielding) of the rods in the quasi-static bending test specimens. The protocol developed can be used for any other screw-plate/rod type spinal instrumentation. The use of a standard protocol by researchers would enable a comparison of various devices currently available in the market. Such comparative data would be useful for the scientific community, and agencies such as the FDA and ASTM.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7798289

  6. Surgical outcome of posterior short segment trans-pedicle screw fixation for thoracolumbar fractures

    PubMed Central

    Khare, Shailendra; Sharma, Vijay

    2013-01-01

    Background Vast majority of spine fractures in thoracolumbar region are unstable and often associated with neurological deficit. With the advancement of technology, these fractures are now more often managed operatively. The present study aimed at evaluating the role of open reduction & internal fixation using pedicle screws and short segment fixation in patients with Thoracic and Lumbar spine fractures. Design In this prospective study, 25 patients in age group of 15–65 years (mean age 28.25 years) with thoracolumbar fractures with associated neurological deficit or compression fractures with loss of more than 50% vertebral height or angulations more than 20° with or without neurological deficit were included. The results were evaluated based on restoration and maintenance of vertebral body height, spinal lordosis/kyphosis and evaluation of the neurological recovery which was done at regular intervals using Frankel's grading. Results The mean follow-up period was 20.3 months. The average preoperative kyphotic angle as measured by Cobbs method was 20° which improved to 7.8° following instrumentation. The average preoperative vertebral height was 58.65% which improved to 78.55% postoperatively. Preoperatively, only 20% of patients had useful paraplegia (Frankel grade D and E) while 80% had useless paraplegia (Frankel's grade C and below). Following surgery, 60% patients had useful paraplegia while 40% had useless paraplegia. Conclusion Short segment trans-pedicle posterior fixation is helpful for not only stabilization of the fractures and restoration of anatomy, but also maintaining the same over a period with good functional outcome. PMID:24396235

  7. Biomechanical Analysis of Fusion Segment Rigidity Upon Stress at Both the Fusion and Adjacent Segments: A Comparison between Unilateral and Bilateral Pedicle Screw Fixation

    PubMed Central

    Kim, Ho-Joong; Kang, Kyoung-Tak; Chang, Bong-Soon; Lee, Choon-Ki; Kim, Jang-Woo

    2014-01-01

    Purpose The purpose of this study was to investigate the effects of unilateral pedicle screw fixation on the fusion segment and the superior adjacent segment after one segment lumbar fusion using validated finite element models. Materials and Methods Four L3-4 fusion models were simulated according to the extent of decompression and the method of pedicle screws fixation in L3-4 lumbar fusion. These models included hemi-laminectomy with bilateral pedicle screw fixation in the L3-4 segment (BF-HL model), total laminectomy with bilateral pedicle screw fixation (BF-TL model), hemi-laminectomy with unilateral pedicle screw fixation (UF-HL model), and total laminectomy with unilateral pedicle screw fixation (UF-TL model). In each scenario, intradiscal pressures, annulus stress, and range of motion at the L2-3 and L3-4 segments were analyzed under flexion, extension, lateral bending, and torsional moments. Results Under four pure moments, the unilateral fixation leads to a reduction in increment of range of motion at the adjacent segment, but larger motions were noted at the fusion segment (L3-4) in the unilateral fixation (UF-HL and UF-TL) models when compared to bilateral fixation. The maximal von Mises stress showed similar patterns to range of motion at both superior adjacent L2-3 segments and fusion segment. Conclusion The current study suggests that unilateral pedicle screw fixation seems to be unable to afford sufficient biomechanical stability in case of bilateral total laminectomy. Conversely, in the case of hemi-laminectomy, unilateral fixation could be an alternative option, which also has potential benefit to reduce the stress of the adjacent segment. PMID:25048501

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

    PubMed Central

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

    2013-01-01

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

  9. A Meta-Analysis of Unilateral versus Bilateral Pedicle Screw Fixation in Minimally Invasive Lumbar Interbody Fusion

    PubMed Central

    Liu, Zheng; Fei, Qi; Wang, Bingqiang; Lv, Pengfei; Chi, Cheng; Yang, Yong; Zhao, Fan; Lin, Jisheng; Ma, Zhao

    2014-01-01

    Study Design Meta-analysis. Background Bilateral pedicle screw fixation (PS) after lumbar interbody fusion is a widely accepted method of managing various spinal diseases. Recently, unilateral PS fixation has been reported as effective as bilateral PS fixation. This meta-analysis aimed to comparatively assess the efficacy and safety of unilateral PS fixation and bilateral PS fixation in the minimally invasive (MIS) lumbar interbody fusion for one-level degenerative lumbar spine disease. Methods MEDLINE/PubMed, EMBASE, BIOSIS Previews, and Cochrane Library were searched through March 30, 2014. Randomized controlled trials (RCTs) and controlled clinical trials (CCTs) on unilateral versus bilateral PS fixation in MIS lumbar interbody fusion that met the inclusion criteria and the methodological quality standard were retrieved and reviewed. Data on participant characteristics, interventions, follow-up period, and outcomes were extracted from the included studies and analyzed by Review Manager 5.2. Results Six studies (5 RCTs and 1 CCT) involving 298 patients were selected. There were no significant differences between unilateral and bilateral PS fixation procedures in fusion rate, complications, visual analogue score (VAS) for leg pain, VAS for back pain, Oswestry disability index (ODI). Both fixation procedures had similar length of hospital stay (MD?=?0.38, 95% CI?=??0.83 to 1.58; P?=?0.54). In contrast, bilateral PS fixation was associated with significantly more intra-operative blood loss (P?=?0.002) and significantly longer operation time (P?=?0.02) as compared with unilateral PS fixation. Conclusions Unilateral PS fixation appears as effective and safe as bilateral PS fixation in MIS lumbar interbody fusion but requires less operative time and causes less blood loss, thus offering a simple alternative approach for one-level lumbar degenerative disease. PMID:25375315

  10. The self adapting washer for lag screw fixation of mandibular fractures: finite element analysis and preclinical evaluation.

    PubMed

    Terheyden, H; Mühlendyck, C; Feldmann, H; Ludwig, K; Härle, F

    1999-02-01

    Besides rigid fixation, lag screws have distinct advantages compared with plates in appropriate indications in mandibular fractures. However, in current lag screw systems, the relatively small area of the screw head has to transfer the tensile force which can exceed 1000 N in the symphysis, to the thin cortical bone plate. Countersinking, which is obligatory in most systems, will weaken the cortical plate. Finite element analysis (FEA) revealed that load in this situation can exceed the normal tensile strength of metal and bone. Consequently, a new washer was constructed which both increased the supporting surface and did not require countersinking. The washer is self adapting (SAW) to the cortical plate in a defined position, forming a ball and socket joint with the screw head. Using the FEA model, a ten-fold reduction in load on bone and metal was observed with the new washer. In a miniature pig mandibular symphysis fracture model, the clinical applicability and a favourable histological reaction were demonstrated, compared with conventional lag screw designs. PMID:10188129

  11. A prospective trial of poly-L-lactic/polyglycolic acid co-polymer plates and screws for internal fixation of mandibular fractures.

    PubMed

    Ferretti, C

    2008-03-01

    The aim of this study was to test the performance of poly-L-lactic/polyglycolic acid (PLLA/PGA) co-polymer plates and screws in the fixation of mandibular fractures. Following clinical and radiographic examination, internal fixation was achieved with PLLA/PGA co-polymer plates and screws in 31 patients. Elastic maxillomandibular fixation was maintained for 4 weeks and a blenderized diet for 6 weeks. Patients were followed up at 1 week, 6 weeks, and 3, 6 and 12 months post surgery, and evaluated clinically for swelling, pain, mucosal discoloration and occlusal relation. Segment stability, fracture healing and screw-hole ossification were assessed radiographically. Of the 29 patients who completed the trial, 20 had an uncomplicated postoperative period, resulting in complete bone union. Radiographic evidence of screw-hole ossification was noted in several patients, with considerable site-dependent rate variation. Nine patients developed complications ranging from minor dehiscence (4 patients) to frank sepsis requiring plate removal (5 patients), resulting in a 22.5% complication rate. There were no cases of non-union at the end of the fixation period. The reported complication rate following titanium internal fixation of mandibular fractures is 13.7%-43%. PLLA/PGA co-polymer plate and screw fixation of mandibular fractures, although technically more challenging and costly, is a viable alternative to traditional metal devices in selected patients. PMID:18295449

  12. Pedicle screw placement at the sacrum: anatomical characterization and limitations at S1.

    PubMed

    Robertson, P A; Plank, L D

    1999-06-01

    Anatomical and biomechanical data have suggested that pedicle screw fixation at the sacrum is optimum in the anteromedial direction into the S1 vertebral body, yet the possibility of posterior iliac crest interference with this screw pathway has been considered but not defined. This study aimed to determine if the anteromedial direction of screw placement into the vertebral body is possible in all cases at S1 and to assess the limiting effect of the posterior iliac crest. Computed tomography scans of the upper sacrum at the S1 pedicle parallel to the sacral endplate were examined in 100 patients. Analysis using a digitizer allowed characterization of an ideal screw pathway with variable screw and screw head diameters in an anteromedial direction into the S vertebral body. The effects of the posterior iliac crest upon these pathways were studied. The study demonstrated that anteromedial placement with bicortical fixation at the vertebral body was theoretically possible in almost all (98.5%) cases. Because the sacral body is often wider than the sacral spinal canal, a straight-ahead screw direction will often achieve placement into the S1 vertebral body, if the starting point for the screw allows screw placement adjacent to the medial border of the S1 pedicle with only 1.5 mm of cortical bone separating the canal and the screw. The space between the posterior iliac crest and the lateral aspect of the screw corridor ranges from a maximum of 52.4 mm to a minimum of 12.8, 6.2, and 0 mm for the 7-, 10-, and 12.5-mm screw corridors. On only three occasions (1.5%) was the ideal screw corridor not possible because of posterior iliac crest overlap. In each case, this occurred only unilaterally and when the widest of the screw corridors (12.5 mm) was used. Both the distance between the posterior iliac crests and the space available for optimum screw placement are greater in females than males. PMID:10382776

  13. Intramedullary screw fixation with bone autografting to treat proximal fifth metatarsal metaphyseal-diaphyseal fracture in athletes: a case series

    PubMed Central

    2012-01-01

    Background Delayed unions or refractures are not rare following surgical treatment for proximal fifth metatarsal metaphyseal-diaphyseal fractures. Intramedullary screw fixation with bone autografting has the potential to resolve the issue. The purpose of this study was to evaluate the result of the procedure. Methods The authors retrospectively reviewed 15 athletes who underwent surgical treatment for proximal fifth metatarsal metaphyseal-diaphyseal fracture. Surgery involved intramedullary cannulated cancellous screw fixation after curettage of the fracture site, followed by bone autografting. Postoperatively, patients remain non weight-bearing in a splint or cast for two weeks and without immobilization for an additional two weeks. Full weight-bearing was allowed six weeks postoperatively. Running was permitted after radiographic bone union, and return-to-play was approved after gradually increasing the intensity. Results All patients returned to their previous level of athletic competition. Mean times to bone union, initiation of running, and return-to-play were 8.4, 8.8, and 12.1?weeks, respectively. Although no delayed unions or refractures was observed, distal diaphyseal stress fractures at the distal tip of the screw occurred in two patients and a thermal necrosis of skin occurred in one patient. Conclusions There were no delayed unions or refractures among patients after carrying out a procedure in which bone grafts were routinely performed, combined with adequate periods of immobilization and non weight-bearing. These findings suggest that this procedure may be useful option for athletes to assuring return to competition level. PMID:22818585

  14. C1-C3 Lateral Mass Screw-Rod Fixation and Fusion for C2 Pathologies and Hangman's Fractures

    PubMed Central

    Haque, Mohammod Raziul

    2014-01-01

    Study Design Retrospective clinical study. Purpose We report our experience of eight patients treated with C1-C3 lateral mass rod-screw stabilization and fusion in the treatment of Hangman's fracture and other axis pathologies. Overview of Literature Different surgical approaches, both anterior and posterior, have been described for treating Hangman's fracture and other pathologies where surgery is indicated. Methods All patients who underwent surgical treatment for Hangman's fracture and axial pathology where C1-C3 lateral mass screw-rod stabilization and fusion done, following reduction of the fracture or removal of the pathology were included in this series. The recorded patient management data was retrospectively studied. Results There were 8 cases in total. All were male, with an average age of 40.75 years. Hangman's fracture occurred in 6 cases (75%), one with metastatic squamous cell carcinoma and the remaining with plasmocytoma. Among the Hangman's fractures 4 (66.66%) had no neuro-deficit. Reduction and bilateral C1-C3 lateral mass screw and rod fixation with posterior fusion by bone graft was performed in all cases. In 2 cases, a C2 body tumor was removed transorally. All patients with neuro-deficit fully recovered, except one who expired in the early post-operative period. Rest of all patients were leading a normal life till last follow up. Conclusions Although the number of cases was very small with a relatively short follow up period, C1 and C3 lateral mass screw-rod fixation followed by fusion showed promise as an effective and biomechanically sound way for the treatment of properly selected Hangman's fracture cases, and may also be suitable in other axial pathologies. PMID:25558315

  15. [Anatomical and radiological aspects in lumbopelvic fixation].

    PubMed

    Gothner, M; Dudda, M; Schildhauer, T A

    2013-11-01

    Spinal and pelvic surgery (as in neuromuscular scoliosis or unilateral highly unstable vertical sacral fractures or unstable H- or U-shaped sacral fractures) relies on lumbopelvic fixation. This technique belongs to the standard procedures for lumbosacral injuries in orthopedic surgery. Preoperatively, a CT scan with 1 mm slices is essential to detect anatomical variants and cortical narrow nesses. For optimal insertion of pedicel screws, knowledge of the pedicle diameter and length is necessary and screws should be placed convergent to each other taking into consideration the pedicle length and angle. For placement of the iliac screws exact knowledge of the anatomy is essential to avoid cortical wall perforation and neurovascular injuries. The safest screw path was determined as the bony canal between the posterior superior iliac spine (PSIS) and the anterior inferior iliac spine (AIIS). Intraoperatively, standard fluoroscopic views allow safe placement of the screws. The aim of the following manuscript is to illustrate anatomical and morphological aspects of the spine and pelvis as well as to describe important bony landmarks and optimal intraoperative C-arm views for optimal screw insertion. PMID:24233082

  16. CT- and fluoroscopy-guided percutaneous screw fixation of a "carrot-stick" spinal fracture in an elderly man with ankylosing spondylitis.

    PubMed

    Huwart, Laurent; Amoretti, Nicolas

    2013-12-01

    We present a case of percutaneous fixation of a "carrot-stick" spinal fracture in an elderly patient with ankylosing spondylitis (AS). A surgical stabilization was not possible in this 83-year-old man with comorbidities. Under local anesthesia, percutaneous screw fixation of a transdiscal shear fracture at the level T10-T11 was performed using computed tomography (CT) and fluoroscopy guidance. Two 4.0-mm Asnis III cannulated screws were placed to fix facet joints using transfacet pedicle pathway. The procedure time was 30 min. Using the visual analog scale (VAS), pain decreased from 10, preoperatively, to 1 after the procedure. Radiographic fusion was observed at a 3-month post-procedural CT scan. CT- and fluoroscopy-guided percutaneous screw fixation of spinal fractures could potentially be an alternative to surgery in elderly AS patients with poor performance status. PMID:23842576

  17. A Systematic Review and Meta-Analysis of Unilateral versus Bilateral Pedicle Screw Fixation in Transforaminal Lumbar Interbody Fusion

    PubMed Central

    Hu, Xu-Qi; Wu, Xin-Lei; Xu, Cong; Zheng, Xu-Hao; Jin, Yong-Long; Wu, Li-Jun; Wang, Xiang-Yang; Xu, Hua-Zi; Tian, Nai-Feng

    2014-01-01

    Background Transforaminal lumbar interbody fusion (TLIF) has become one of the most widely used procedures for lumbar spinal disorders. However, it is still unclear whether TLIF with unilateral pedicle screw (PS) fixation is as effective as that with bilateral PS fixation. We performed a meta-analysis of the literatures and aimed to gain a better understanding of whether TLIF with unilateral PS fixation was safe and effective for lumbar diseases. Methodology/Principal Findings We systematically searched Ovid, Springer, and Medline databases for relevant randomized controlled trials (RCTs) that compared the clinical and radiological outcomes of unilateral versus bilateral PS fixation in TLIF. Risk of bias in included studies was assessed using the Cochrane Risk of Bias tool. We generated pooled risk ratios or weighted mean differences across studies. According to our predefined inclusion criteria, seven RCTs with a total of 441 patients were included in this study. Baseline characteristics were similar between the unilateral and bilateral groups. Our meta-analysis showed that no significant difference was detected between the two groups in terms of postoperative clinical function, fusion status, reoperation rate, complication rate, and hospital stay (p>0.05). Pooled estimates revealed that the unilateral group was associated with significantly reduced implant cost, operative time and blood loss (p<0.05). Conclusions/Significances Our meta-analysis suggested TLIF with unilateral PS fixation was as safe and effective as that with bilateral PS fixation for lumbar diseases in selected patients. Despite these findings, our meta-analysis was based on studies with small sample size and different study characteristics that might lead to the inconsistent results such as various functional outcomes among the included studies. Therefore, high-quality randomized controlled trials with larger sample size are also needed to further clarify these issues and to provide the long-term outcomes. PMID:24489929

  18. Fixation strength of biocomposite wedge interference screw in ACL reconstruction: effect of screw length and tunnel\\/screw ratio. A controlled laboratory study

    Microsoft Academic Search

    Antonio Herrera; Fernando Martínez; Daniel Iglesias; José Cegoñino; Elena Ibarz; Luis Gracia

    2010-01-01

    BACKGROUND: Primary stability of the graft is essential in anterior cruciate ligament surgery. An optimal method of fixation should be easy to insert and provide great resistance against pull-out forces. A controlled laboratory study was designed to test the primary stability of ACL tendinous grafts in the tibial tunnel. The correlation between resistance to traction forces and the cross-section and

  19. 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 g/cm2 and a mean osseus screw purchase of 27.2 mm was 467.8 N. In comparison, POS of 22 VBS screws with a mean BMD of 0.533 g/cm2 and a mean osseus screw purchase of 16.0 mm was 181.6 N. The difference in ultimate pull-out strength between the ATPS and VBS group was significant (p < 0.000001). Also, accuracy of ATPS placement in axial plane was shown to be significantly correlated with POS. In contrast, there was no correlation between screw-length, BMD, or level of insertion and the POS of ATPS or VBS. The study demonstrated that the use of ATPS might be a new technique worthy of further investigation. The use of ATPS shows the potential to increase construct rigidity in terms of screw-plate pull-out resistance. It might diminish construct failures during anterior-only reconstructions of the highly unstable decompressed cervical spine. Electronic supplementary material The online version of this article (doi:10.1007/s00586-007-0573-x) contains supplementary material, which is available to authorized users. PMID:18224357

  20. Percutaneous screw fixation versus conservative treatment for fractures of the waist of the scaphoid: a prospective randomised study.

    PubMed

    McQueen, M M; Gelbke, M K; Wakefield, A; Will, E M; Gaebler, C

    2008-01-01

    We randomly allocated 60 consecutive patients with fractures of the waist of the scaphoid to percutaneous fixation with a cannulated Acutrak screw or immobilisation in a cast. The range of movement, the grip and pinch strength, the modified Green/O'Brien functional score, return to work and sports, and radiological evidence of union were evaluated at each follow-up visit. Patients were followed sequentially for one year. Those undergoing percutaneous screw fixation showed a quicker time to union (9.2 weeks vs 13.9 weeks, p < 0.001) than those treated with a cast. There was a trend towards a higher rate of nonunion in the non-operative group, although this was not statistically significant. Patients treated by operation had a more rapid return of function and to sport and full work compared with those managed conservatively. There was a very low complication rate. We recommend that all active patients should be offered percutaneous stabilisation for fractures of the waist of the scaphoid. PMID:18160502

  1. Effects of different mandibular fracture patterns on the stability of miniplate screw fixation in angle mandibular fractures.

    PubMed

    Pektas, Z O; Bayram, B; Balcik, C; Develi, T; Uckan, S

    2012-03-01

    The aim of the present study was to evaluate the effects of horizontally favourable and unfavourable mandibular fracture patterns on the fixation stability of titanium plates and screws by simulating chewing forces. Favourable and unfavourable mandibular fractures on 22 sheep hemimandibles were fixed with 4-hole straight titanium plates and 2.0mm×7mm titanium screws according to the Champy technique. Hemimandibles were mounted with a fixation device in a servohydraulic testing unit for compressive testing. Displacement values under 20, 60, 100, 120, 150, 200N, maximum displacements, and maximum forces the model could resist before breakage were recorded and compared. The authors found no statistically significant differences between the groups for the displacement values in the force range 60-200N (60, 100, 120, 150 and 200N). Statistically significant differences for maximum displacement values (displacement values at the breaking forces) between the groups were found (P<0.05). There was no evidence for the need to apply different treatment modalities to mandibular fractures regardless of whether the factures are favourable or not. PMID:22178275

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

    PubMed Central

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

    2014-01-01

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

  3. The radiological feature of anterior occiput-to-axis screw fixation as it guides the screw trajectory on 3D printed models: a feasibility study on 3D images and 3D printed models.

    PubMed

    Wu, Ai-Min; Wang, Sheng; Weng, Wan-Qing; Shao, Zhen-Xuan; Yang, Xin-Dong; Wang, Jian-Shun; Xu, Hua-Zi; Chi, Yong-Long

    2014-12-01

    Anterior occiput-to-axis screw fixation is more suitable than a posterior approach for some patients with a history of posterior surgery. The complex osseous anatomy between the occiput and the axis causes a high risk of injury to neurological and vascular structures, and it is important to have an accurate screw trajectory to guide anterior occiput-to-axis screw fixation. Thirty computed tomography (CT) scans of upper cervical spines were obtained for three-dimensional (3D) reconstruction. Cylinders (1.75?mm radius) were drawn to simulate the trajectory of an anterior occiput-to-axis screw. The imitation screw was adjusted to 4 different angles and measured, as were the values of the maximized anteroposterior width and the left-right width of the occiput (C0) to the C1 and C1 to C2 joints. Then, the 3D models were printed, and an angle guide device was used to introduce the screws into the 3D models referring to the angles calculated from the 3D images. We found the screw angle ranged from ?1 (left: 4.99±4.59°; right: 4.28±5.45°) to ?2 (left: 20.22±3.61°; right: 19.63±4.94°); on the lateral view, the screw angle ranged from ?1 (left: 13.13±4.93°; right: 11.82±5.64°) to ?2 (left: 34.86±6.00°; right: 35.01±5.77°). No statistically significant difference was found between the data of the left and right sides. On the 3D printed models, all of the anterior occiput-to-axis screws were successfully introduced, and none of them penetrated outside of the cortex; the mean ?4 was 12.00±4.11 (left) and 12.25±4.05 (right), and the mean ?4 was 23.44±4.21 (left) and 22.75±4.41 (right). No significant difference was found between ?4 and ?4 on the 3D printed models and ?3 and ?3 calculated from the 3D digital images of the left and right sides. Aided with the angle guide device, we could achieve an optimal screw trajectory for anterior occiput-to-axis screw fixation on 3D printed C0 to C2 models. PMID:25526447

  4. Occiput/C1-C2 fixations using intra-laminar screw of axis - A long-term follow-up.

    PubMed

    Sinha, Sanjiv; Jagetia, Anita; Aher, Rajendra B; Butte, Manoj Kumar V

    2014-12-01

    Background. The surgical management of the craniocervical junction is challenging. Rigid posterior fixation of occiput/C1-C2 can be performed using a variety of surgical techniques including C2 pedicle/pars interarticularis, transarticular and intralaminar screw fixations. Methods. Forty-one patients were treated with occipital plate/C1 lateral mass and C2 intra-laminar screw fixations for basilar invagination and congenital atlantoaxial subluxation, post-traumatic instability, tuberculous and rheumatoid arthritis-associated atlantoaxial dislocation. Out of forty-one, thirty-six patients had bilateral crossing intra-laminar screws and five had ipsilateral laminar screw fixation bilaterally. Results. Follow-up was done in thirty-nine patients from 6 months to 8 years (mean: 21 months) and solid osseous fusion could be achieved in all (100%). One patient was lost to follow-up and another patient died of a cause unrelated to surgical technique. Pre-operative and post-operative Neurosurgical Cervical Spine Scale showed improvement in all patients having features of myelopathy. There were no neurological or vascular complications. However, nine patients had posterior laminar breach, eight had anterior laminar penetrations and three had wound infections. One patient had transient bulbar palsy and one patient had hardware failure in the form of avulsion of the midline occipital plate. Conclusions. Intra-laminar screw fixation is a safe alternative to transarticular and transpedicular/pars interarticularis fixation of C2 with advantage of having no risk of injury to vertebral artery and comparable biomechanical and pull-out strength. PMID:25472926

  5. Enhanced lapidus arthrodesis: crossed screw technique with middle cuneiform fixation further reduces sagittal mobility.

    PubMed

    Galli, Melissa M; McAlister, Jeffrey E; Berlet, Gregory C; Hyer, Christopher F

    2015-01-01

    Persistent medial column sagittal mobility can be encountered despite successful first tarsometatarsal stabilization if fixation has been limited to the first tarsometatarsal joint. The purpose of the present cadaveric research was to quantify the effect of a third point of fixation from the base of the first metatarsal to the middle cuneiform compared with the traditional isolated first tarsometatarsal fixation. Ten matched pairs of below-the-knee specimens, with a known cause of death, sex, ethnicity, and age, height, weight, and body mass index at death, were used for our examination. Portable fluoroscopy aided with the accurate placement of all points of fixation. Measurements of movement were obtained using the validated Klaue device. The 20 matched below-the-knee specimens were from 10 cadavers (2 female and 8 male donors, aged 72.8 ± 9.3 years, body mass index 21.1 ± 4.2 kg/m(2)). The sagittal plane motion of the first ray was 7.45 ± 1.82 mm before fixation. With isolated first tarsometatarsal fixation, the sagittal motion decreased to 4.41 ± 1.51 mm and decreased further to 3.12 ± 1.06 mm, with the addition of middle cuneiform fixation. Statistically significant enhancement of the stability of sagittal first ray motion was noted with the addition of the first metatarsal to middle cuneiform pin, even after simulated Lapidus fixation. Our findings suggest that first metatarsal to middle cuneiform fixation can be beneficial if excessive sagittal motion is present after standard 2-point fixation and can play a role in the prevention of recurrence and complications. PMID:25456344

  6. Atlantoaxial arthrodesis using C1-C2 transarticular screw fixation in a case of Morquio syndrome.

    PubMed

    Kulkarni, Arvind G; Shah, Siddharth M

    2011-09-01

    Prophylactic or therapeutic arthrodesis is recommended for atlantoaxial instability in Morquio syndrome. Occipitocervical fusion, the common approach for upper cervical fusion in Morquio syndrome sacrifices the movements at the occipitoatlantal joints. The use of C1-C2 transarticular screws for achieving C1-C2 arthrodesis, without compromising mobility at the occipitoatlantal joint in Morquio syndrome has not been reported. We report a case of Morquio syndrome with atlantoaxial instability and odontoid hypoplasia, where we successfully achieved C1-C2 arthrodesis using transarticular screws and bone graft. The advantages of this method over other methods of atlantoaxial arthrodesis in Morquio syndrome have also been discussed. PMID:21886932

  7. 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.

  8. Iatrogenic Injury of Profunda Femoris Artery Branches after Intertrochanteric Hip Screw Fixation for Intertrochanteric Femoral Fracture: A Case Report and Literature Review

    PubMed Central

    Koutsoumpelis, Andreas; Vergadis, Chrysovalantis; Mourikis, Anastasios; Georgopoulos, Sotiris E.

    2014-01-01

    A case of arterial rupture of the profunda femoris arterial branches, following dynamic hip screw (DHS) fixation for an intertrochanteric femoral fracture, is presented. Bleeding is controlled by coil embolization, but, later on, the patient underwent orthopedic material removal due to an infection of a large femoral hematoma. PMID:24716097

  9. Oesophageal perforation caused by screw displacement 16?months following anterior cervical spine fixation.

    PubMed

    Leaver, Nicholas; Colby, Alexandra; Appleton, Nathan; Vimalachandran, Dale

    2015-01-01

    Anterior cervical spine plating is a standard procedure for fixing unstable vertebral fractures. Following surgery, oesophageal perforation has an incidence of 0.25% and this is usually hours following surgery, due to over prominent screws or friction between the oesophagus and the plate. Instrumentation failure of these plates months or years following surgery is very rare but potentially life-threatening. We report a case of microcytic anaemia which was investigated by oesophagogastroduodenoscopy, and subsequently found that a screw from the anterior plate had lifted off and perforated the oesophagus. This is very rare, but emphasises an important lesson. Anyone presenting with gastrointestinal bleeding or infectious signs, with a history of cervical spine plating should be investigated immediately for instrumentation failure as it brings a high mortality. PMID:25796082

  10. Unilateral versus Bilateral Pedicle Screw Fixation for Degenerative Lumbar Diseases: A Meta-Analysis of 10 Randomized Controlled Trials

    PubMed Central

    Li, Xianzhou; Lv, Chaoliang; Yan, Tingzhen

    2015-01-01

    Background The common and effective treatment for degenerative lumbar diseases is lumbar spinal fusion. Controversy still exists on the choice for instrumentation with spinal fusion procedures. Therefore, we conducted this meta-analysis exclusively of RCTs to compare the clinical outcomes of patients receiving bilateral versus unilateral pedicle screw fixation (PSF). Material/Methods After systematic review of published and unpublished literature, a meta-analysis was conducted to compare the 2 treatment strategies. The methodological quality of the literature was assessed using the PEDro critical appraisal tool. Results Data synthesis showed less blood loss (P<0.001) and shorter operative time (P<0.001) in patients receiving unilateral PSF compared to bilateral PSF. However, there was no significant difference in fusion rates and functional outcomes between the 2 groups. Conclusions The meta-analysis indicated no significant difference in fusion rates and functional outcomes between the 2 treatment procedures, but unilateral PS fixation reduced blood loss and operative time. PMID:25774950

  11. Percutaneous fixation with Schanz screws for displaced two- and three- part fractures of the proximal humerus in patients above fifty years of age

    PubMed Central

    Eid, Abdelsalam; Osman, Mohamed; Fekry, Hosam-Eldeen

    2011-01-01

    Purpose: The aim of this study is to evaluate whether two 3.0 mm Schanz screws in two-part proximal humeral fractures (plus one additional Schanz screw or K wire in three-part fractures) can provide enough stability to allow early mobilization until healing occurs in elderly patients. Settings and Design: This prospective study was performed in the Orthopaedic Department of our University Hospital. Patients and Methods: We performed closed reduction and percutaneous pinning for thirty-three patients with proximal humerus fractures. Twenty-seven patients were available for the final follow-up. Of those 27 patients, 17 had two-part surgical neck fractures; while 10 had three-part fractures. For fixation, we used two 3.0 mm Schanz screws in patients with two-part fractures plus one additional Schanz screw or K wire in the 10 patients with three-part fractures. Results: The mean Constant score modified according to the age and sex was 89.8% (range: 77.3-97.2%). Fifteen patients had excellent results, 11 patients had good results, and one patient had a fair result. Conclusion: Closed reduction and percutaneous pinning with two Schanz screws for two-part surgical neck humeral fractures, plus an additional Schanz screw or K wire for three-part proximal humeral fractures is a useful and effective technique that provides enough stability to allow an early rehabilitation program till union occurs in elderly patients. Level of Evidence: IV; therapeutic study, case series. PMID:21897582

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

    PubMed Central

    2014-01-01

    Background Lateral mass screw fixation (LSF) techniques have been widely used for reconstructing and stabilizing the cervical spine; however, complications may result depending on the choice of surgeon. There are only a few reports related to LSF applications, even though fracture fixation has become a severe complication. This study establishes the three-dimensional finite element model of the lower cervical spine, and compares the stress distribution of the four LSF techniques (Magerl, Roy-Camille, Anderson, and An), following laminectomy -- to explore the risks of rupture after fixation. Method CT scans were performed on a healthy adult female volunteer, and Digital imaging and communication in medicine (Dicom) data was obtained. Mimics 10.01, Geomagic Studio 12.0, Solidworks 2012, HyperMesh 10.1 and Abaqus 6.12 software programs were used to establish the intact model of the lower cervical spines (C3-C7), a postoperative model after laminectomy, and a reconstructive model after applying the LSF techniques. A compressive preload of 74 N combined with a pure moment of 1.8 Nm was applied to the intact and reconstructive model, simulating normal flexion, extension, lateral bending, and axial rotation. The stress distribution of the four LSF techniques was compared by analyzing the maximum von Mises stress. Result The three-dimensional finite element model of the intact C3-C7 vertebrae was successfully established. This model consists of 503,911 elements and 93,390 nodes. During flexion, extension, lateral bending, and axial rotation modes, the intact model’s angular intersegmental range of motion was in good agreement with the results reported from the literature. The postoperative model after the three-segment laminectomy and the reconstructive model after applying the four LSF techniques were established based on the validated intact model. The stress distribution for the Magerl and Roy-Camille groups were more dispersive, and the maximum von Mises stress levels were lower than the other two groups in various conditions. Conclusion The LSF techniques of Magerl and Roy-Camille are safer methods for stabilizing the lower cervical spine. Therefore, these methods potentially have a lower risk of fixation fracture. PMID:25106498

  13. Biomechanical comparison of dynamic condylar screw and locking compression plate fixation in unstable distal femoral fractures: An in vitro study

    PubMed Central

    Singh, Ashutosh Kumar; Rastogi, Amit; Singh, Vakil

    2013-01-01

    Background: Distal femur fractures are difficult to manage and the selection of implant for internal fixation remains controversial. The objective of this study is to establish the relative strength of fixation of a distal femoral locking plate (DFLP) compared with the dynamic condylar screw (DCS) in the distal femur fractures. Materials and Methods: Study was conducted on 16 freshly harvested cadaveric distal femoral specimens, eight implanted with DCS and other eight with DFLP. The construct was made unstable by removing a standard sized medial wedge of 1 cm base (gap-osteotomy) beginning 6 cm proximal to the lateral joint line in distal metaphyseal region with the loss of medial buttress. Fatigue test was conducted under load control mode at the frequency of I Hz. Specimens were subjected to cyclic loading of 2 kN, under observation for 50,000 cycles or until failure/cutout, which ever occurred earlier. Results: In DFLP group, there was no implant failure and the average number of cycles sustained was 50,000. Six out of eight specimens completed 50,000 cycles and two failed in DCS group. The average number of cycles sustained by DCS was 46150. Though the bone quality as assessed by dual energy X-ray absorptiometry DEXA was comparable in both DFLP and DCS group (P = 0.06), none failed in DFLP group and subsidence was 1.02 ± 0.34 mm (range: 0.60-1.32 mm), which was significantly 43% lower (P = 0.006) than subsidence in DCS group (1.82 ± 0.58; range: 1.20-3.08 mm). The average stiffness of DCS group was 52.8 ± 4.2 N/mm, which was significantly lower than average stiffness of locked condylar plate group (71.2 ± 5.1 N/mm) (P = 0.02). Conclusions: DFLP fixation of the distal femur fractures resulted in stronger construct than the DCS fixation in both cyclic loading and ultimate strength in biomechanical testing of a simulated A3 distal femur fracture. PMID:24379469

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

    PubMed Central

    2014-01-01

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

  15. Novel Pedicle Screw and Plate System Provides Superior Stability in Unilateral Fixation for Minimally Invasive Transforaminal Lumbar Interbody Fusion: An In Vitro Biomechanical Study

    PubMed Central

    Zhu, Qingan; Zhou, Yue; Li, Changqing; Liu, Huan; Huang, Zhiping; Shang, Jin

    2015-01-01

    Purpose This study aims to compare the biomechanical properties of the novel pedicle screw and plate system with the traditional rod system in asymmetrical posterior stabilization for minimally invasive transforaminal lumbar interbody fusion (MI-TLIF). We compared the immediate stabilizing effects of fusion segment and the strain distribution on the vertebral body. Methods Seven fresh calf lumbar spines (L3-L6) were tested. Flexion/extension, lateral bending, and axial rotation were induced by pure moments of ± 5.0 Nm and the range of motion (ROM) was recorded. Strain gauges were instrumented at L4 and L5 vertebral body to record the strain distribution under flexion and lateral bending (LB). After intact kinematic analysis, a right sided TLIF was performed at L4-L5. Then each specimen was tested for the following constructs: unilateral pedicle screw and rod (UR); unilateral pedicle screw and plate (UP); UR and transfacet pedicle screw (TFS); UP and TFS; UP and UR. Results All instrumented constructs significantly reduced ROM in all motion compared with the intact specimen, except the UR construct in axial rotation. Unilateral fixation (UR or UP) reduced ROM less compared with the bilateral fixation (UP/UR+TFS, UP+UR). The plate system resulted in more reduction in ROM compared with the rod system, especially in axial rotation. UP construct provided more stability in axial rotation compared with UR construct. The strain distribution on the left and right side of L4 vertebral body was significantly different from UR and UR+TFS construct under flexion motion. The strain distribution on L4 vertebral body was significantly influenced by different fixation constructs. Conclusions The novel plate could provide sufficient segmental stability in axial rotation. The UR construct exhibits weak stability and asymmetrical strain distribution in fusion segment, while the UP construct is a good alternative choice for unilateral posterior fixation of MI-TLIF. PMID:25807513

  16. Time course of bone screw fixation following a local delivery of Zoledronate in a rat femoral model - A micro-finite element analysis.

    PubMed

    Kettenberger, Ulrike; Latypova, Adeliya; Terrier, Alexandre; Pioletti, Dominique P

    2015-05-01

    A good fixation of osteosynthesis implants is crucial for a successful bone healing but often difficult to achieve in osteoporotic patients. One possible solution to this issue is the local delivery of bisphosphonates in direct proximity to the implants, A critical aspect of this method, that has not yet been well investigated, is the time course of the implant fixation following the drug release. Usual destructive mechanical tests require large numbers of animals to produce meaningful results. Therefore, a micro-finite element (microFE) approach was chosen to analyze implant fixation. In vivo micro computed tomography (microCT) scans were obtained, first weekly and later bi-weekly, after implantation of polymeric screws in the femoral condyles of ovariectomized rats. In one half of the animals, Zoledronate was released from a hydrogel matrix directly in the peri-implant bone stock, the other animals were implanted only with screws as control. The time course of the implant fixation was investigated with linear elastic microFE models that were created based on in vivo microCT scans. The numerical models were validated against experimental pullout-tests measurements in an additional cadaver study. The microFE analysis revealed a significant increase in force at yield of the Zoledronate treated group compared to the control group. The force of the treated group was 28% higher after 17 days of screw implantation, 42% higher after 31 days. The significant difference persisted until the end of the in vivo study at day 58 (p<0.01). The early onset and prolonged duration of the implant anchorage improvement that was found in this study indicates the great potential of Zoledronate-loaded hydrogel for an enhancement of osteosynthesis implant fixation in impaired bone. PMID:25679481

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

    PubMed Central

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

    2013-01-01

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

  18. Percutaneous kyphoplasty and pedicle screw fixation for the management of thoraco-lumbar burst fractures.

    PubMed

    Fuentes, Stéphane; Blondel, Benjamin; Metellus, Philippe; Gaudart, Jean; Adetchessi, Tarek; Dufour, Henry

    2010-08-01

    The study design includes prospective evaluation of percutaneous osteosynthesis associated with cement kyphoplasty on 18 patients. The objective of the study is to assess the efficacy of a percutaneous method of treating burst vertebral fractures in patients without neurological deficits. Even if burst fractures are frequent, no therapeutic agreement is available at the moment. We report in this study the results at 2 years with a percutaneous approach for the treatment of burst fractures. 18 patients were included in this study. All the patients had burst vertebral fractures classified type A3 on the Magerl scale, between levels T9 and L2. The patients' mean age was 53 years (range 22-78 years) and the neurological examination was normal. A percutaneous approach was systematically used and a kyphoplasty was performed via the transpedicular pathway associated with percutaneous short-segment pedicle screw osteosynthesis. The patients' follow-up included CT scan analysis, measurement of vertebral height recovery and local kyphosis, and clinical pain assessments. With this surgical approach, the mean vertebral height was improved by 25% and a mean improvement of 11.28 degrees in the local kyphotic angle was obtained. 3 months after the operation, none of the patients were taking class II analgesics. The mean duration of their hospital stay was 4.5 days (range 3-7 days) and the mean follow-up period was 26 months (range 17-30 months). No significant changes in the results obtained were observed at the end of the follow-up period. Minimally invasive methods of treating burst vertebral fractures can be performed via the percutaneous pathway. This approach gives similar vertebral height recovery and kyphosis correction rates to those obtained with open surgery. It provides a short hospital stay, however, and might therefore constitute a useful alternative to open surgical methods. PMID:20496038

  19. Polymer cable/grip-plate system with locking screws for stable fixation to promote healing of trochanteric osteotomies or fractures in revision total hip arthroplasty.

    PubMed

    Berend, Keith R; Willen, Jacob L; Morris, Michael J; Adams, Joanne B; Lombardi, Adolph V

    2014-11-01

    Multiple methods have been proposed to establish stable fixation to promote healing of trochanteric osteotomies or fractures in revision total hip arthroplasty (revTHA), from wiring techniques through cable-plate systems with or without supplemental locking screws. The purpose of this study is to report the clinical results of a single cable-plate system with locked screw fixation in revTHA. Between 2009 and 2012, 27 grip-plates (Supercable® System, Kinamed Inc., Camarillo, CA) were used in 26 patients in 27 revTHA procedures. Utilization was 12 1-hole (50 mm) grip-plates, 10 2-hole (135 mm) grip-plates, four 4-hole (190 mm) grip-plates, and one 6-hole (245 mm) grip-plate. There were 14 women and 12 men. Age averaged 63.2 years and BMI averaged 29.4 kg/m2. At average 2.5 year follow-up, grip-plate fixation was considered successful in 22 hips (81%) with five failures. Three failures consisted of 50 mm/short grip-plates used in one trochanteric slide, and two intraoperative trochanteric fractures during revTHA. The two additional failures were related to pre-revision trochanteric avulsion from bony necrosis of the proximal femur. An additional three grip-plates were removed electively for soft-tissue irritation and pain but with successful fixation and bony healing. Thus 70% of hips were free of reoperation related to the grip-plate. All other hips had successful fixation and the grip-plate was not symptomatic. In this study, the cable-grip system and isoelastic Supercables provided reliable fixation for adequate healing of difficult ETO and trochanteric fractures with an 81% rate of mechanical success with radiographic and clinical healing observed. PMID:25398403

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

    PubMed Central

    2012-01-01

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

  1. Biomorphometric analysis of ilio-sacro-iliacal corridors for an intra-osseous implant to fix posterior pelvic ring fractures.

    PubMed

    Gras, Florian; Hillmann, Sophia; Rausch, Sascha; Klos, Kajetan; Hofmann, Gunther O; Marintschev, Ivan

    2015-02-01

    It is hypothesized that ilio-sacro-iliacal corridors for a new envisioned pelvic ring implant (trans-sacral nail with two iliacal bolts = ISI-nail: ilio-sacro-iliacal nail) exists on the level of S1- or S2-vertebra in each patient. The corridors of 84 healthy human pelves (42x ?; 42x ?, 18-85 years) were measured in high resolution CT scans using the Merlin Diagnostic Workcenter Software. Trans-sacral corridors (? 9 mm diameter) on the level of S1 and S2 were found in 62% and 54% of pelves with a mean length [mm ± SD] of 164 ± 12.9 and 142 ± 10.2. Corresponding iliac corridors were present in all specimens in caudally tilted axial planes of 37.8 ± 0.67° and 53.7 ± 0.94° in relation to the operating table plane and divergent angulations of 69.0 ± 0.49° and 70.1 ± 0.32° in relation to the sagittal midline plane. Sacral dysmorphism, with compensatory larger S2 corridors were prevalent in 24% of pelves; ilio-sacro-iliacal osseous corridors for the envisioned implant were found in 88% of pelves on the level of S1 or S2. In the remaining 12% with too narrow corridors for any trans-sacral implant (screws, bars, ISI nail) alternative fixation methods have to be considered. Expected advantages of the envisioned ISI nail compared to available fixation devices are discussed. PMID:25408471

  2. Biomechanical effects of polyaxial pedicle screw fixation on the lumbosacral segments with an anterior interbody cage support

    Microsoft Academic Search

    Shih-Hao Chen; Ruey Mo Lin; Hsiang-Ho Chen; Kai-Jow Tsai

    2007-01-01

    BACKGROUND: Lumbosacral fusion is a relatively common procedure that is used in the management of an unstable spine. The anterior interbody cage has been involved to enhance the stability of a pedicle screw construct used at the lumbosacral junction. Biomechanical differences between polyaxial and monoaxial pedicle screws linked with various rod contours were investigated to analyze the respective effects on

  3. Guided bone regeneration technique in the esthetic zone: a novel approach using resorbable PLLA-PGA plates and screw fixation. A case report.

    PubMed

    Fabbri, Giacomo; Brennan, Myra; Manfredi, Massimiliano; Ban, Georgio

    2009-10-01

    The use of biodegradable fixation materials or devices during maxillofacial, craniofacial, and orthopedic reconstructive surgical procedures reduces or eliminates the need to perform a second surgical procedure, which would otherwise be required to remove a nonbiodegradable device. This article presents a novel approach to augment a horizontally deficient alveolar ridge using both a resorbable plate/screw fixation system composed of a polylactic acid-polyglycolic acid (PLLA-PGA) copolymer to provide a rigid scaffolding for the bone chips and a resorbable collagen barrier (Bio-Gide, Osteohealth) to secure the graft material. For periodontal reconstructive procedures, such as guided bone regeneration, the clinical application of this technique may be advantageous and also provide a more esthetic result by minimizing the need for an additional surgical procedure. (Int J Periodontics Restorative Dent 2009;29:543-547.). PMID:19888498

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

    PubMed Central

    2014-01-01

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

  5. Screw fixation via diploic bone paralleling to occiput table: anatomical analysis of a new technique and report of 11 cases.

    PubMed

    Mingsheng, Tan; Huimin, Wang; Xin, Jiang; Ping, Yi; Hongyu, Wei; Feng, Yang; Wu, Wang; Guangbo, Zhang

    2007-12-01

    Several types of posterior approaches have been adopted for occipitocervical fusion. Prior to this study, Foerater et al. in 1927 used a fibular strut graft in the site between the occiput and the lower cervical spine to achieve fusion. Since then, various techniques including wrings, Hartshill loop, AO reconstructive plate, and AXIS occipital plate were described and used widely. As far as we know, all these techniques involve the screw placement vertical to the diploic bone; however none has ever addressed the feasibility of screw placement in occiput parallelling to the diploic bone. In our study, 30 dry specimens of human occiputs were measured manually using vernier calipers and protractors. The intradiploic screw was first supposed to be inserted inferiorly to the superior nuchal line (SNL) prominence. The entry point located at the superior edge of the SNL prominence. Afterward, the measurements of extracranial occiput in SNL area on midline and bilateral 15 mm to the midline saggital-cutting planes of the occiput were conducted. The thickness of the occipital bone at the location of SNL prominence, the entry point, the exit point and the screw orientation were measured, respectively. Afterward, 11 patients with craniocervical malformation were treated surgically using this alternative and their X-ray radiographs and CT scans were evaluated postoperatively. The data showed that the occipital at the site of SNL prominence was the thickest. The thickest point was external occipital protuberance (EOP), which was up to 14 mm. The thickness decreased gradually from the site of SNL to the superior border of surgical decompressed area. The actual length of screw channel was about 26 mm. The mean thickness for safe screw insertion ranged from 5.73 to 14.14 mm. A total of 22 intraocciput screws parallel to diploic bone were placed precisely, without injury to the cerebral and inner occipital venous sinus. The results confirm that occiput is available for holding intraocciput screw paralleling to diploic bone. PMID:17899218

  6. Image-Based Planning and Validation of C1-C2 Transarticular Screw Fixation Using Personalized Drill Guides

    Microsoft Academic Search

    Kirsten Martens; Kris Verstreken; Johan Van Cleynenbreugel; Karel Van Brussel; Jan Goffin; Guy Marchal; Paul Suetens

    1999-01-01

    \\u000a Posterior transarticular spine fusion is a surgical procedure used to stabilize the cervical bodies C1 and C2. Currently,\\u000a spine screws are used most frequently, according to the procedure of Magerl. As the anatomy is rather complex and the view\\u000a is limited, this procedure has a high risk factor. Thus we present and validate a planning system for cervical screw insertion

  7. Arterial Injury to the Profunda Femoris Artery following Internal Fixation of a Neck of Femur Fracture with a Compression Hip Screw.

    PubMed

    Craxford, Simon; Gale, Michael; Lammin, Kimberly

    2013-01-01

    We report the case of an 82-year-old woman who developed extensive proximal thigh swelling and persistent anaemia following internal fixation of an extracapsular neck of femur fracture with a dynamic hip screw (DHS). This was revealed to be a pseudoaneurysm of a branch of profunda femoris artery on angiography. Her case was further complicated by a concurrent pulmonary embolism (PE). She underwent endovascular coil embolisation of the pseudoaneurysm. An IVC filter was inserted and the patient was fully anticoagulated once it had been ensured that there was no active bleeding. In this case, we review the potential for anatomical variations in the blood supply to this region and discuss treatment options for a complicated patient. We recommend that a pseudoaneurysm should be part of a differential diagnosis for postoperative patients with anaemia refractory to blood transfusion so as not to miss this rare but potentially serious complication. PMID:24455367

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

    PubMed

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

    2014-03-01

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

  9. Randomized prospective study of ACL reconstruction with interference screw fixation in patellar tendon autografts versus femoral metal plate suspension and tibial post fixation in hamstring tendon autografts: 5-year clinical and radiological follow-up results.

    PubMed

    Harilainen, Arsi; Linko, Eric; Sandelin, Jerker

    2006-06-01

    Patellar tendon graft has been the most frequently used material in anterior cruciate ligament (ACL) reconstruction, but the hamstring tendons have been increasingly used as well; however, which graft is to be preferred is not adequately supported by existing clinical studies. In this prospective randomized clinical trial, the study hypothesis was that the hamstring tendons are equally good graft material as the patellar tendon in ACL reconstruction. Ninety-nine patients with laxity due to a torn ACL underwent arthroscopically assisted reconstruction with graft randomization according to their birth year to either patellar tendon with metal interference screw fixation or double looped semitendinosus and gracilis tendons with fixation similar to the Endobutton technique using a titanium metal plate suspension proximally and screw-washer postdistally. Excluding preoperative Lysholm knee score, there were no significant differences between the two groups in the preoperative and operative data. A standard rehabilitation regimen was used for all the patients, including immediate postoperative mobilization without a knee brace, protected weight bearing for 2 weeks, and return to full activity at 6-12 months postoperatively. Forty patients in the patellar tendon group and 39 patients in the hamstring tendon group were available for clinical evaluation at median 5 years after surgery (ranges 3 years 11 months-6 years 7 months). The results revealed no statistically significant differences with respect to clinical and instrumented laxity testing, isokinetic muscle torque measurements, International Knee Documentation Committee ratings, Lysholm (knee score), Tegner (activity level) and Kujala patellofemoral knee scores. There was an enlargement of the drill tunnels, statistically more in the hamstring tendon group, but no increase from 2 to 5 years in either group. Narrowing of the joint spaces (IKDC measurement method) from 2 to 5 years postoperatively was seen in both the groups, however, without difference between the two groups. PMID:16552549

  10. Internal Reduction Established by Occiput-C2 Pedicle Polyaxial Screw Stabilization in Pediatric Atlantoaxial Rotatory Fixation

    Microsoft Academic Search

    Deniz Belen; Serkan Simsek; Kazim Yigitkanli; Murad Bavbek

    2006-01-01

    Atlantoaxial rotatory fixation is an uncommon disorder of childhood, which can be treated conservatively whendiagnosed early. Although spontaneous correction occasionally occurs, most of the patients usually benefit from collar or traction therapies. If there is no intervention or if all external therapeutic modalities fail, the deformity may become chronic and irreducible. In such rare cases, surgical correction and stabilization are

  11. Tacks: a new technique for craniofacial fixation.

    PubMed

    Cohen, S R; Holmes, R E; Amis, P; Fitchner, H; Shusterman, E M

    2001-11-01

    Biodegradable fixation in craniofacial surgery provides secure fixation while eliminating much of the concern over intracranial migration of metallic plates and screws. One limitation of present biodegradable systems, however, is the need for tapping the drill hole before screw insertion. Herein, a new method of rigid, biodegradable fixation with tacks (Macrapore, Inc., San Diego, CA) is described. The tacks are made of a 70:30 ratio of the L and DL form of polylactic acid (L,DL-PLA). Degradation times range from 18 to 36 months. Newer prototypes are nearly developed for more rapid dissolution times. From April 1999 to February 2000, tack fixation has been applied in 100 patients (51 males, 49 females aged 3 months to 61 years). Indications for operation were craniosynostosis (n = 33); craniofacial trauma or post-traumatic deformities (n = 11); cleft lip and palate (n = 13); craniofacial syndromes (n = 18); other diagnoses (n = 11). Patients underwent fronto-orbital advancement with cranial reshaping; monobloc osteotomy, open reduction-internal fixation of fractures; hypertelorbitism repair; cranioplasty; stabilization of grafts; major cranial reconstruction; zygomatic advancement; alveolar cleft repair; and iliac bone graft donor site protection. Tacks were also used for temporalis muscle and lateral canthal suspension. Follow-up ranged from 16 to 28 months. Complications occurred in 7 patients, 4 of whom had infections and during debridement had biodegradable implants removed. None of the complications appeared to be related to the use of tacks. The tacks are carried in a specially designed holder and may be placed by hand or with the light tap of a mallet on the tack driver. An automatic driver has been developed. Overall, the performance of the tacks has been excellent. They are easily handled by the nursing personnel and rapidly inserted by the surgeon. Stability appears to be excellent. At this time, it is probably preferable to employ tap and screws for orthognathic surgery or other osteotomies with substantial load bearing. PMID:11711829

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

    PubMed Central

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

    2014-01-01

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

  13. Influence of the volume of bone defect, bone grafting methods, and hook fixation on stress on the Kerboull-type plate and screw in total hip arthroplasty: three-dimensional finite element analysis.

    PubMed

    Kaku, Nobuhiro; Hara, Katsutoshi; Tabata, Tomonori; Tsumura, Hiroshi

    2015-02-01

    For total hip arthroplasty or revision surgery using acetabular reinforcement cross-plates, choosing between bulk and morselized bone grafts for filling acetabular defects is challenging. We used finite element model (FEM) analysis to clarify various stresses on the cross-plate based on bone defect size, bone graft type, and presence or absence of hook fixation to the bone. We constructed 12-pattern FEMs and calculated the maximum stress generated on the Kerboull-type (KT) plate and screw. Bone defects were classified into four patterns according to the volume. Regarding the bone graft type, bulk bone grafts were considered as cortical bone, and morselized bone grafts were considered to consist of cancellous bone. Models were compared based on whether hook fixation was used and whether a gap was present behind the plate. The upper surface of the host bone was fixed, and a 1,000-N load was imposed on the horizontal axis at 71°. Larger bone defects increased the stress on the KT plate and screws. This stress increased when no bone was grafted; it was lower when bulk cortical bone grafts were used for filling than when morselized cancellous bone grafts were used. For cortical bone grafts, the increased stress on the KT plate and screws was lowered with hook removal. Attaching the hook to the bone and filling the gap behind the KT plate with an adequate bone graft reduced the stress on the KT plate and screws, particularly for large bone defects filled by bulk bone grafting. PMID:24964969

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

    PubMed Central

    2014-01-01

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

  15. Multilevel mini-open TLIFs and percutaneous pedicle screw fixation: description of a simple technical nuance used to increase intraoperative safety and improve workflow. Tips and tricks and review of the literature.

    PubMed

    Barbagallo, Giuseppe M V; Certo, Francesco; Visocchi, Massimiliano; Sciacca, Giovanni; Piccini, Mario; Albanese, Vincenzo

    2015-04-01

    We describe a technical variation used to enhance intraoperative safety and efficiency in multilevel percutaneous pedicle screw fixation (PPSFs) and mini-open transforaminal lumbar interbody fusion (m-TLIFs). A review of the literature on percutaneous screw insertion techniques and related pitfalls is presented. PPSFs and m-TLIFs are increasingly used techniques in multilevel lumbar degenerative disease. Facetectomy and TLIF are usually performed before inserting ipsilateral pedicle screws. Such techniques can cause unintended violation of the pedicle and injure the dura or neural structures, particularly in multilevel cases. A literature review revealed a lack of intraoperative and fluoroscopic images detailing the technique for multilevel PPSF and m-TLIF(s) performed through tubular, expandable retractors. Thirteen patients with two- to four-level disease underwent multilevel PPSF and m-TLIF (one to four levels). The Kirschner Cage Screw (KCS) technique, consisting of early insertion of K-wires in all pedicles followed by facetectomy and m-TLIF(s) and, finally, screw insertion, was used in order to minimize the risk of dural/neural injuries. Neither CSF (cerebrospinal fluid) leaks nor nerve root injuries nor technique-related complications were encountered with a follow-up ranging from 7 to 38 months (mean 23.6). In conclusion, the KCS technique allows safe identification of the pedicles without opening the canal during m-TLIF(s). Moreover, by visualizing the K-wires inside the retractor, the surgeon can check the pedicle position during facetectomy, and screws can be introduced with a minimal risk of neural or dural injuries. We believe that the proposed technique increases the safety and ease of the procedure, particularly in multilevel cases. PMID:25391632

  16. Mechanical analysis of fixation methods for anterior cruciate ligament reconstruction with hamstring tendon graft. An experimental study in sheep knees

    Microsoft Academic Search

    Carlo Fabbriciani; Pier Damiano Mulas; Fabio Ziranu; Laura Deriu; Donatella Zarelli; Giuseppe Milano

    2005-01-01

    This study evaluates the structural properties of the femur–anterior cruciate ligament (ACL) graft–tibia complex, comparing different graft fixation techniques in sheep knees. Four fixation devices were tested both for femoral fixation (Transfix, absorbable screw, RCI screw and Linx-HT) and tibial fixation (bone plug with metal screw, absorbable screw with staple, RCI screw and cancellous screw with spiked washer). The graft

  17. Scarf osteotomy without screw fixation

    Microsoft Academic Search

    M. Maestro

    2007-01-01

    The scarf osteotomy is now well recognised as reliable and effective to contribute to the correction of the majority of hallux\\u000a valgus. The challenge remains for the correction of severe deformities with metatarsus varus angle >18? and Distal Metatarsal\\u000a Articular Angle (DMAA) >15?. In order to significantly improve in 3D the metatarsal head displacements, our scarf design became more oblique,

  18. CT-based 3-D visualisation of secure bone corridors and optimal trajectories for sacroiliac screws.

    PubMed

    Mendel, Thomas; Radetzki, Florian; Wohlrab, David; Stock, Karsten; Hofmann, Gunther Olaf; Noser, Hansrudi

    2013-07-01

    Sacroiliac screw (SI) fixation represents the only minimally invasive method to stabilise unstable injuries of the posterior pelvic ring. However, it is technically demanding. The narrow sacral proportions and a high inter-individual shape variability places adjacent neurovascular structures at potential risk. In this study a CT-based virtual analysis of the iliosacral anatomy in the human pelvis was performed to visualise and analyse 3-D bone corridors for the safe placement of SI-screws in the first sacral segment. Computer-aided calculation of 3-D transverse and general SI-corridors as a sum of all inner-bony 7.3-mm screw positions was done with custom-made software algorithms based on CT-scans of intact human pelvises. Radiomorphometric analysis of 11 CT-DICOM datasets using the software Amira 4.2. Optimal screw tracks allowing the greatest safety distance to the cortex were computed. Corridor geometry and optimal tracks were visualised; measurement data were calculated. A transverse corridor existed in 10 pelvises. In one dysmorphic pelvis, the pedicular height at the level of the 1st neural foramina came below the critical distance of 7.3mm defined by the outer screw diameter. The mean corridor volume was 45.2 cm3, with a length of 14.9cm. The oval cross-section measured 2.8 cm2. The diameter of the optimal screw pathway with the greatest safety distance was 14.2mm. A double cone-shaped general corridor for screw penetration up to the centre of the S1-body was calculated bilaterally for every pelvis. The mean volume was 120.6 cm3 for the left side and 115.8 cm3 for the right side. The iliac entry area measured 49.1 versus 46.0 cm2. Optimal screw tracks were calculated in terms of projected inlet and outlet angles. Multiple optimal screw positions existed for each pelvis. The described method allows an automated 3-D analysis with regard to secure SI-screw corridors even with a high number of CT-datasets. Corridor visualisation and calculation of optimal screw tracks trains the visual thinking of the surgeon and can improve pre-operative planning. Prospectively, the introduced method can be implemented in computer-assisted surgery applications involving pelvic trauma. PMID:23246561

  19. Iliac insufficiency fractures.

    PubMed

    Davies, A M; Bradley, S A

    1991-04-01

    Twenty-five post-menopausal women with one or more insufficiency fractures of the pelvic ring are reported. In 80% of cases the fractures were multiple and a total of 79 insufficiency fractures was identified. Twelve iliac insufficiency fractures were present in 11 patients located at one of three sites: above and parallel to the acetabular roof ("supra-acetabular"), extending diagonally across the iliac ala from the greater sciatic notch ("oblique iliac"), and adjacent to the sacro-iliac joint ("superomedial iliac"). The plain radiographic appearances of these iliac fractures were typically subtle with ill defined medullary sclerosis, due to trabecular compression, the cardinal sign. Scintigraphy revealed the fractures as foci of increased activity which, in the presence of multiple pelvic insufficiency fractures, may be mistaken for metastatic disease. Computed tomography can be helpful in confirming the presence of suspected fractures, revealing further occult fractures and also excluding the likelihood of malignancy. PMID:2025768

  20. 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

  1. Modified Trajectory of C2 Laminar Screw - Double Bicortical Purchase of the Inferiorly Crossing Screw

    PubMed Central

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

    2008-01-01

    The crossing laminar screw fixation might be the most recently developed approach among various fixation techniques for C2. The new construct has stability comparable to transarticular or transpedicular screw fixation without risk of vertebral artery injury. Quantitative anatomical studies about C2 vertebra suggest significant variation in the thickness of C2 lamina as well as cross sectional area of junction of lamina and spinous process. We present an elderly patient who underwent an occipito-cervical stabilization incorporating crossed C2 laminar screw fixation. We preoperatively recognized that she had low profiles of C2 lamina, and thus made a modification of trajectory for the inferiorly crossing screw. We introduce a simple modification of crossing C2 laminar screw technique to improve stability in patients with low laminar profiles. PMID:19096618

  2. Two-Stage Surgical Management of Multilevel Symptomatic Thoracic Haemangioma Using Ethanol and Iliac Crest Bone Graft

    PubMed Central

    Brahmajoshyula, Venkatramana; Mayi, Shivanand; Teegala, Suman

    2014-01-01

    This article presents a 56-year-old obese female who presented with back pain and progressive weakness in her lower limbs for three months. She was bed-ridden for one week before reporting to our hospital. Plain radiographs showed vertical striations in multiple vertebrae classical of haemangioma. Magnetic resonance imaging (MRI) spine revealed multiple thoracic and lumbar vertebral haemangiomas. Extra osseous extension of haemangioma at T12 was causing spinal cord compression. Two-stage surgery was performed with absolute alcohol (ethanol) injection followed by pedicle screw fixation and decompression with tricortical iliac crest bone graft into the vertebral body. Postoperatively rapid neurological improvement was seen. After three weeks, she could walk independently. One year later, computed tomography showed complete incorporation of bone graft and maintained vertebral body height. MRI showed complete resolution of the cord edema at T12. These findings indicated diminished vascularity of the tumor. PMID:25187869

  3. Two-stage surgical management of multilevel symptomatic thoracic haemangioma using ethanol and iliac crest bone graft.

    PubMed

    Degulmadi, Devanand; Brahmajoshyula, Venkatramana; Mayi, Shivanand; Teegala, Suman

    2014-08-01

    This article presents a 56-year-old obese female who presented with back pain and progressive weakness in her lower limbs for three months. She was bed-ridden for one week before reporting to our hospital. Plain radiographs showed vertical striations in multiple vertebrae classical of haemangioma. Magnetic resonance imaging (MRI) spine revealed multiple thoracic and lumbar vertebral haemangiomas. Extra osseous extension of haemangioma at T12 was causing spinal cord compression. Two-stage surgery was performed with absolute alcohol (ethanol) injection followed by pedicle screw fixation and decompression with tricortical iliac crest bone graft into the vertebral body. Postoperatively rapid neurological improvement was seen. After three weeks, she could walk independently. One year later, computed tomography showed complete incorporation of bone graft and maintained vertebral body height. MRI showed complete resolution of the cord edema at T12. These findings indicated diminished vascularity of the tumor. PMID:25187869

  4. Less invasive reduction and fusion of fresh A2 and A 3 traumatic L 1-L 4 fractures with a novel vertebral body augmentation implant and short pedicle screw fixation and fusion.

    PubMed

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

    2014-04-01

    The aim of this clinical study was to report on the efficacy in reduction and safety in PMMA leakage of a novel vertebral augmentation technique with PEEK and PMMA, together with pedicle screws in the treatment of fresh vertebral fractures in young adults. Twenty consecutive young adults aged 45 ± 11 years with fresh burst A3/AO or severely compressed A2/AO fractures underwent via a less invasive posterior approach one-staged reduction with a novel augmentation implant and PMMA plus 3-vertebrae pedicle screw fixation and fusion. Radiologic parameters as segmental kyphosis (SKA), anterior (AVBHr) and posterior vertebral body height ratio (PVBHr), spinal canal encroachment (SCE), cement leakage and functional parameters as VAS, SF-36 were measured pre- and post-operatively. Hybrid construct restored AVBHr (P < 0.000), PVBHr (P = 0.02), SKA (P = 0.015), SCE (P = 0.002) without loss of correction at an average follow-up of 17 months. PMMA leakage occurred in 3 patients (3 vertebrae) either anteriorly to the fractured vertebral body or to the adjacent disc, but in no case to the spinal canal. Two pedicle screws were malpositioned (one medially, one laterally to the pedicle at the fracture level) without neurologic sequelae. Solid posterolateral spinal fusion occurred 8-10 months post-operatively. Pre-operative VAS and SF-36 scores improved post-operatively significantly. This study showed that this novel vertebral augmentation technique using PEEK implant and PMMA reduces and stabilizes via less invasive technique A2 and A3 vertebral fractures without loss of correction and leakage to the spinal canal. PMID:24170266

  5. Minimally Invasive Posterior Trans-muscular C1-C2 Screw Fixation Through an Anatomical Corridor to Preserve Occipitocervical Tension Band: Surgical Anatomy and Clinical Experience.

    PubMed

    Díaz, Roberto; Berbeo, Miguel E; Villalobos, Luis M; Vergara, Manuel F; Osorio, Enrique

    2014-01-01

    The C1-C2 joint is affected by multiple entities that may produce biomechanical instability. Optimal management for atlantoaxial instability has been searched by ways of different surgical techniques with different results, generating discussion between second effects of a particular treatment. Lateral dissections can place the axial neck musculature and ligaments at risk of neural denervations or vascular compromise. Either of these entities may result in significant postoperative atrophy, pain, and instability. Minimally invasive techniques for the treatment of spinal disorders allow to our patients less morbid procedures with equal or better results compared to conventional surgery. In the following paper, we review the anatomy of the atlantoaxial joint and propose a minimally invasive trans-muscular C1-C2 fusion technique using C1 lateral-mass screws and C2 pedicular screws. We describe cases with surgical, clinical, and radiographic follow-up. PMID:24265049

  6. Hydroxyapatite Coating Of Threaded Pins Enhances Fixation

    Microsoft Academic Search

    G. Magyar; S. Toksvig-Larsen; A. Moroni

    1997-01-01

    We measured the insertion and extraction torque forces in a randomised study of 76 external fixation screws in 19 patients treated by hemicallotasis for osteoarthritis of the medial side of the knee. The patients were randomised to have either standard tapered screws (Orthofix 6\\/5 mm) or the same screws with hydroxyapatite (HA) coating. One patient had two standard and two

  7. Clinical application of C2 laminar screw technique

    PubMed Central

    Feng, Leling; Xu, Rongming; Liu, Xiaochen; Lee, Alan H.; Sun, Shaohua; Zhao, Liujun; Hu, Yong; Liu, Guanyi

    2010-01-01

    C2 laminar screws have become an increasingly used alternative method to C2 pedicle screw fixation. However, the outcome of this technique has not been thoroughly investigated. A total of 35 cases with upper cervical spinal instability undergoing C2 laminar screw fixation were reviewed. All cases had symptoms of atlantoaxial instability, such as craniocervical junction pain, and were fixed with the Vertex cervical internal fixation system. A total of 68 screws were placed and hybrid constructs (a C2 translaminar screw combined with a C2 pars screw) were incorporated in two patients. In this series, there were no intraoperative complications and no cases of neurological worsening or vascular injury from hardware placement. Computed tomographic scans demonstrated a partial dorsal laminar breach in ten patients. None of these resulted in neurological symptoms. None of the patients was found to have a breach of the ventral laminar cortex. All the C2 laminar screws fixations were performed successfully. There was no instability seen on the films with no evidence of hardware failure or screw loosening during the follow-up period in all patients. In conclusion, C2 laminar screw technique is straightforward and easily adopted; it can efficiently and reliably restore upper cervical stability. It is an alternative method to C2 pedicle screw fixation, especially in patients with unilateral occlusion of vertebral artery and pedicle deformity of C2. PMID:20524135

  8. Complications at screw removal in slipped capital femoral epiphysis treated by cannulated titanium screws

    Microsoft Academic Search

    T. Ilchmann; K. Parsch

    2006-01-01

    Introduction: Various modes of fixation are proposed for the treatment of slips of the capital femoral epiphysis (SCFE). We describe our experience with the use and removal of a new, cannulated titanium screw (Asnis III, Stryker®, Howmedica). Patients and methods: Single cannulated titanium screws had been inserted in 101 hips of 65 patients in the 3-year period from 2001 to

  9. Are plasticity models required to predict relative risk of lag screw cut-out in finite element models of trochanteric fracture fixation?

    PubMed

    Goffin, Jérôme M; Pankaj, Pankaj; Simpson, A Hamish

    2014-01-01

    Using a finite element model of unstable trochanteric fracture stabilized with a sliding hip screw, the benefits of two plasticity-based formulations, Drucker-Prager and crushable foam, were evaluated and compared to the commonly used linear elastic model of trabecular bone in order to predict the relative risk of lag screw cut-out for five distinct load cases. The crushable foam plasticity formulation leads to a much greater strain localization, in comparison to the other two models, with large plastic strains in a localized region. The plastic zone predicted with Drucker-Prager is relatively more diffuse. Linear elasticity associated with a minimum principal strain criterion provides the smallest volume of elements susceptible to yielding for all loading modes. The region likely to undergo plastic deformation, as predicted by the linear elastic model, is similar to that obtained from plasticity-based formulations, which indicates that this simple criterion provides an adequate estimate of the risk of cut-out. PMID:24182773

  10. A new adhesive technique for internal fixation in midfacial surgery

    Microsoft Academic Search

    Kira Endres; Rudolf Marx; Joachim Tinschert; Dieter Christian Wirtz; Christian Stoll; Dieter Riediger; Ralf Smeets

    2008-01-01

    BACKGROUND: The current surgical therapy of midfacial fractures involves internal fixation in which bone fragments are fixed in their anatomical positions with osteosynthesis plates and corresponding screws until bone healing is complete. This often causes new fractures to fragile bones while drilling pilot holes or trying to insert screws. The adhesive fixation of osteosynthesis plates using PMMA bone cement could

  11. Should we use cortical bone screws for cortical bone trajectory?

    PubMed

    Ueno, Masaki; Sakai, Rina; Tanaka, Kensei; Inoue, Gen; Uchida, Kentaro; Imura, Takayuki; Saito, Wataru; Nakazawa, Toshiyuki; Takahira, Naonobu; Mabuchi, Kiyoshi; Takaso, Masashi

    2015-04-01

    OBJECT In 2009, Santoni et al. reported cortical bone trajectory (CBT) as a method of inserting pedicle screws to obtain more solid fixation, and proposed the use of cortical trajectory screws with a more closely placed thread (cortical screws) for CBT. Since the entry trajectory in CBT differs from that in the traditional trajectory, it is unclear whether the increased strength derives from the specific trajectory or the shape of the screw thread in contact with the cortical bone. Whether the use of cortical screws is always required with CBT thus remains unclear. The authors therefore investigated the relationship between screw entry trajectory and screw thread characteristics and pullout strength in animal experiments. METHODS Lumbar vertebrae (L1-L4) from 4-month-old female pigs were randomly assigned to one of 4 groups, with cancellous screws or cortical screws inserted via the traditional trajectory or CBT. For pullout strength testing, the screw was pulled out vertically against the direction of insertion. Rod pullout testing (toggle testing) was also performed, and the peak breaking strength was measured. RESULTS The maximum pullout strength was significantly greater for CBT using cortical screws than for the traditional trajectory using cancellous screws. Pullout strength tended to be higher when cortical screws were used in both CBT and the traditional trajectory, although the difference was not significant. Toggle testing showed no significant differences among the 4 groups. CONCLUSIONS The specific unconventional trajectory seemed to have a major impact on the increased strength obtained with CBT. PMID:25594731

  12. Evaluation of thoracic pedicle screw placement in adolescent idiopathic scoliosis

    PubMed Central

    Tosun, Bilgehan; Atmaca, Halil; Sarisoy, Hasan Tahsin; Buluç, Levent

    2009-01-01

    Pedicle screw fixation is a challenging procedure in thoracic spine, as inadvertently misplaced screws have high risk of complications. The accuracy of pedicle screws is typically defined as the screws axis being fully contained within the cortices of the pedicle. One hundred and eighty-five thoracic pedicle screws in 19 patients that were drawn from a total of 1.797 screws in 148 scoliosis patients being suspicious of medial and lateral malpositioning were investigated, retrospectively. Screw containment and the rate of misplacement were determined by postoperative axial CT sections. Medial screw malposition was measured between medial pedicle wall and medial margin of the pedicle screw. The distance between lateral margin of the pedicle screw and lateral vertebral corpus was measured in lateral malpositions. A screw that violated medially greater than 2 mm, while lateral violation greater than 6 mm was rated as an “unacceptable screw”. The malpositions were medial in 20 (10.8%) and lateral in 34 (18.3%) screws. Medially, nine screws were rated as acceptable. Of the 29 acceptable lateral misplacement, 13 showed significant risk; five to aorta, six to pleura, one to azygos vein and one to trachea. The acceptability of medial pedicle breach may change in each level with different canal width and a different amount of cord shift. In lateral acceptable malpositions, the aorta is always at a risk by concave-sided screws. This CT-based study demonstrated that T4–T9 concave segments have a smaller safe zone with respect to both cord-aorta injury in medial and lateral malpositions. In these segments, screws should be accurate and screw malposition is to be unacceptable. PMID:19526376

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

    PubMed Central

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

    2013-01-01

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

  14. Biomechanical and histological evaluation of an expandable pedicle screw in osteoporotic spine in sheep

    Microsoft Academic Search

    Shiyong Wan; Wei Lei; Zixiang Wu; Da Liu; Mingxuan Gao; Suochao Fu

    2010-01-01

    Transpedicular fixation can be challenging in the osteoporotic spine as reduced bone mineral density compromises the mechanical\\u000a stability of the pedicle screw. Here, we sought to investigate the biomechanical and histological properties of stabilization\\u000a of expandable pedicle screw (EPS) in the osteoporotic spine in sheep. EPSs and standard pedicle screws, SINO screws, were\\u000a inserted on the vertebral bodies in four

  15. Revision cruciate ligament surgery with retention of femoral interference screws.

    PubMed

    Miller, M D

    1998-01-01

    As the popularity of cruciate ligament reconstruction continues to escalate, the need for revision surgery has also increased. Revision cruciate ligament surgery is often associated with difficult technical challenges including removing previously placed femoral interference screws. Not only can this hardware be difficult to remove, interference screw extraction often creates a large bony defect immediately adjacent to the revised femoral tunnel that can jeopardize the fixation of the new cruciate ligament graft. It is often possible to perform revision cruciate ligament reconstruction without removing femoral interference screws. This technical note provides several examples of this technique. Routine removal of femoral interference screws during revision cruciate ligament surgery is often not necessary. PMID:9486347

  16. Atrial fixation leads--a visual aid confirming actual fixation.

    PubMed

    Conti, J B; Curtis, A B

    1992-02-01

    Various active fixation mechanisms are available for atrial lead implantation. Confirmation of actual fixation of the lead tip in the myocardium is sometimes difficult with standard techniques such as fluoroscopy. Our observation of organized clockwise/counterclockwise motions of the fixation stylet in synchrony with atrial systole confirms adequate positioning of the Accufix model #330-801 atrial lead in the right atrial appendage, which is helpful when the screw is difficult to visualize under fluoroscopy. This observation was confirmed in nine patients. PMID:1372408

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

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

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

  18. Cannulated screw unraveling: a case series and literature-based review of an under-recognized complication.

    PubMed

    Kupperman, Eli; Franko, Orrin; Indresano, Andrew; Girard, Paul

    2013-01-01

    Partially threaded cannulated screws have enhanced the orthopedic surgeon's ability to fix periarticular fractures. There are many reports of complications and hardware failure during screw removal, but those during fracture fixation are under-reported and under-recognized in the literature. We describe a 21-year-old healthy man with a grade 1 open displaced medial epicondylar humerus fracture. Upon fracture fixation in the OR using a partially threaded cannulated screw over a Kirschner wire, the threads of the screw unraveled. The operating surgeon felt increased resistance and the unraveling was demonstrated on intra-operative fluoroscopy. The screw was removed by hand without hardware retention and a new K-wire and cannulated screw were used for definitive fixation. We found seven previous cases reporting a similar complication with mixed presentations and results. All occurred in young healthy patients, six of which were males. Six of the seven cases made no mention of a tactile change in resistance during fixation and only one of the seven pre-drilled the cortex prior to placement of the cannulated screw. We believe that screw unraveling is an under-reported complication of fracture fixation with cannulated screws that should be recognized by the orthopedic community. We found intra-operative fluoroscopy integral to the recognition of the problem in our case and recommend its use in fracture fixation with cannulated screws. We also suggest pre-drilling of cortices, especially when operating on young patients with strong bone. PMID:23104015

  19. Intrapelvic Migration of the Lag Screw in Intramedullary Nailing

    PubMed Central

    Toki, Shunichi; Hamada, Daisuke; Yoshioka, Shinji; Tsutsui, Takahiko; Tamaki, Yasuaki; Sairyo, Koichi

    2014-01-01

    Internal fixation with intramedullary devices has gained popularity for the treatment of intertrochanteric femoral fractures, which are common injuries in the elderly. The most common complications are lag screw cut out from the femoral head and femoral fracture at the distal tip of the nail. We report here a rare complication of postoperative lag screw migration into the pelvis with no trauma. The patient was subsequently treated with lag screw removal and revision surgery with total hip arthroplasty. This case demonstrated that optimal fracture reduction and positioning of the lag screw are the most important surgical steps for decreasing the risk of medial migration of the lag screw. Furthermore, to prevent complications, careful attention should be paid to subsequent steps such as precise insertion of the set screw. PMID:25610680

  20. Midline lumbar fusion with cortical bone trajectory screw.

    PubMed

    Mizuno, Masaki; Kuraishi, Keita; Umeda, Yasuyuki; Sano, Takanori; Tsuji, Masanori; Suzuki, Hidenori

    2014-01-01

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

  1. Hybrid Fixation of Tibial Eminence Fractures in Skeletally Immature Patients

    PubMed Central

    Gans, Itai; Babatunde, Oladapo M.; Ganley, Theodore J.

    2013-01-01

    Tibial eminence fractures most commonly occur in children and adolescents. When treating displaced fractures of the tibial eminence, some surgeons prefer screw fixation whereas others prefer suture fixation. The ultimate goal is to limit morbidity through early return to range of motion and activity. In this technical note, we describe 2 hybrid fixation techniques for fixing tibial eminence fractures, one for type III and the other for type IV fractures. The first technique (variation A) is used to treat type III fractures and combines use of both a bioabsorbable compression screw and suture for fixation. The second technique (variation B) is used to treat type IV fractures and combines use of both a bioabsorbable compression screw and shoulder anchor fixation. We have found that these methods provide efficient, secure, and reliable fixation using standard techniques common to arthroscopic surgery. In addition, the growth plates are spared in children and adolescents, and the need for reoperation to remove hardware is eliminated. PMID:24265991

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

    PubMed

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

    2004-01-01

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

  3. Anatomic study of individualized and improved pedicle screw implantation in the lower cervical spine.

    PubMed

    Liu, Yuan; Zhang, Bin; Dai, Min; Xiong, Han-Chu; Gao, Song; Li, Bin-Hua; Yao, Hao-Qun; Cao, Kai; Liu, Zhi-Li

    2015-02-01

    The objective of this study was to explore a safe, reliable, and effective method for pedicle screw implantation in the lower cervical spine. Recently, a number of studies have shown that cervical pedicle screw fixation is better than roadside steel plate after cervical screw internal fixation within the scope of its indications. However, the difficulty of the former surgery technology is relatively higher and it is much easier to cause many complications. Therefore, domestic and foreign scholars have been positively exploring safer, easier operations and cheaper methods of pedicle screw implantation in the lower cervical spine. The lower cervical spine areas (C3-C7) of 7 adult cadavers were carried out with computed tomography (CT) scans of 1-mm slices. The entry point, angle, and length of the screws were determined by the measurement of CT images in a picture archiving and communication system. The pedicle screws were implanted with the technique of improved Abumi pedicle screw placement in the lab. The accuracy of the screws was evaluated by the Andrew CT classification criteria of pedicle screw position and gross observation after the experiment. A total of 66 screws were implanted in the lower cervical spine, and 90.9% of the screws inserted were found to be in an optimal position. The method of individualized and improved pedicle screw implantation in the lower cervical spine is relatively safe and reliable, which can be considered to be used in the clinic. PMID:25692438

  4. Ball screw inspection setup

    NASA Astrophysics Data System (ADS)

    Janusz, Rzepka; Sambor, Slawomir; Pienkowski, Janusz; Bielenin, Marcin

    2003-05-01

    In the following paper we describe arrangements of laser interferometer for investigation of screws and for inspection of ball screws. We have constructed two of them, namely: the technological setup for investigations of screw in process of production and the ball screw inspection setup. The former one is used to measure the pitch of screws. The data gathered during measurement is used to calculate the parameters for grinding machine. The later setup is used for testing parameters of complete ball screws. The software supporting this setup makes calculation of parameters of tested ball screw and creation of reports possible. Additionally, the inspection setup is the one that the torque measuring arrangements have been integrated on. Both the arrangements and the software allow for measurements of all parameters during movement of nut in full travel length of the ball screw and make charts and reports.

  5. Intraoperative 3-dimensional imaging (O-arm) for assessment of pedicle screw position: Does it prevent unacceptable screw placement?

    PubMed Central

    Sembrano, Jonathan N.; Polly, David W.; Ledonio, Charles Gerald T.; Santos, Edward Rainier G.

    2012-01-01

    Background Pedicle screws are biomechanically superior over other spinal fixation devices. When improperly positioned, they lose this advantage and put adjacent structures at risk. Accurate placement is therefore critical. Postoperative computed tomography (CT) scans are the imaging gold standard and have shown malposition rates ranging from 2% to 41%. The O-arm (Medtronic Navigation, Louisville, Colorado) is an intraoperative CT scanner that may allow intervention for malpositioned screws while patients are still in the operating room. However, this has not yet been shown in clinical studies. The primary objective of this study was to assess the usefulness of the O-arm for evaluating pedicle screw position by answering the following question: What is the rate of intraoperative pedicle screw revision brought about by O-arm imaging information? A secondary question was also addressed: What is the rate of unacceptable thoracic and lumbar pedicle screw placement as assessed by intraoperative O-arm imaging? Methods This is a case series of consecutive patients who have undergone spine surgery for which an intraoperative 3-dimensional (3D) CT scan was used to assess pedicle screw position. The study comprised 602 pedicle screws (235 thoracic and 367 lumbar/sacral) placed in 76 patients, and intraoperative 3D (O-arm) imaging was obtained to assess screw position. Action taken at the time of surgery based on imaging information was noted. An independent review of all scans was also conducted, and all screws were graded as either optimal (no breach), acceptable (breach ?2 mm), or unacceptable (breach >2 mm). The rate of pedicle screw revision, as detected by intraoperative 3D CT scan, was determined. Results On the basis of 3D imaging information, 17 of 602 screws (2.8%) in 14 of 76 cases (18.4%) were revised at the time of surgery. On independent review of multiplanar images, 11 screws (1.8%) were found to be unacceptable, 32 (5.3%) were acceptable, and 559 (92.9%) were optimal. All unacceptable screws were revised to an optimal or acceptable position, and an additional 6 acceptable screws were revised to an optimal position. Thus, by the end of the cases, none of the 602 pedicle screws in the 76 surgical procedures was in an unacceptable position. Conclusion The new-generation intraoperative 3D imaging system (O-arm) is a useful tool that allows more accurate assessment of pedicle screw position than plain radiographs or fluoroscopy alone. It prompted intraoperative repositioning of 2.8% of pedicle screws in our series. Most importantly, it allowed identification and revision of all unacceptably placed pedicle screws without the need for reoperation. PMID:25694871

  6. Use of Cortical Bone Screws in Maxillofacial Surgery - A Prospective Study

    PubMed Central

    Satish, Madatanapalli; Rahman, NM Mujeeb; Reddy, V Sridhar; Yuvaraj, A; Muliyar, Sabir; Razak, P Abdul

    2014-01-01

    Background: The aim of this study is to evaluate the various applications of cortical bone screws in oral and maxillofacial surgery. Materials & Methods: The study was conducted in a teaching hospital located in, Bangalore, India, on 20 patients. These patients were categorized into three groups depending on the applications of these screws like, for achieving intermaxillary fixation in Group-1, for treatment of simple, undisplaced fractures by “Tension wire” method in Group-2, and further application of these screws were evaluated in Group-3. Different parameters were used to evaluate the efficacy of these screws. Results: In Group-1(n=12) there was satisfactory occlusion in all the patients with minimal incidence of complications. In Group-2 (n=4) post-operative reduction and fixation was satisfactory and in Group-3 (n=4) the function of these screws was satisfactory when it was used for vestibuloplasty and also as a suspension wiring in treatment of comminuted fracture of zygoma with minimal incidence of complications. Conclusion: Use of cortical bone screws is a valid alternative for achieving intermaxillary fixation, reduction and fixation of simple, undisplaced or minimally displaced fractures through Tension wire method owing to its simplicity, economy and ease of use, and as a fixation method for apically positioned flap in vestibuloplasty procedure. How to cite the article: Satish M, Rahman NM, Reddy VS, Yuvaraj A, Muliyar S, Razak PA. Use of Cortical Bone Screws in Maxillofacial Surgery - A Prospective Study. J Int Oral Health 2014;6(2):62-7. PMID:24876704

  7. Clinical degradation and biocompatibility of different bioabsorbable interference screws: A report of six cases

    Microsoft Academic Search

    Andreas C. Stähelin; Andreas Weiler; Hansjörg Rüfenacht; Reinhard Hoffmann; Alfred Geissmann; Richard Feinstein

    1997-01-01

    The clinical biocompatibility and degradation of bioabsorbable interference screws of different polymer composition is described in this report for six patients who underwent repeat arthroscopy after anterior cruciate ligament (ACL) reconstruction. Bioabsorbable interference screws were used for bone plug fixation of bone—patellar tendon—bone (BPTB) autografts. Poly (L-lactide) (PLLA) interference screws were used in one case, poly (D,L-lactide-co-glycolide) (PDLLA-co-PGA) in two

  8. Mechanical properties of two canine iliac fracture fixation systems

    E-print Network

    VanGundy, Thomas Eugene

    1988-01-01

    view of hemipelves illustrating loading positions for testing modes. . . . . 12 Composite force versus displacement plot for torsional test specimens. . . . . . . . . . . . . 16 Composite force versus displacement plot for E, test specimens. 16... Composite force versus displacement plot for E~ test specimens. . . . . . . . . . . . . . . . . . . . 17 Composite force versus displacement plot for E~ test specimens. . . . . . . . . . . . . . . 17 10 Bar graph illustrating mean values of stiffness...

  9. A biomechanical comparison of internal fixation techniques for ankle arthrodesis.

    PubMed

    Clifford, Craig; Berg, Scott; McCann, Kevin; Hutchinson, Byron

    2015-01-01

    The purpose of the present study was to compare the primary bending stiffness characteristics of 5 different ankle arthrodesis fixation techniques: 3 compression screws, an anterior locking plate, a lateral locking plate, an anterior locking plate with a compression screw, and a lateral locking plate with a compression screw. A total of 25 full-scale anatomic models consisting of fourth-generation composite tibiae and tali were tested using an Instron 4505 Universal Testing System. We hypothesized that the use of a compression screw with a locking plate would add considerable stiffness to the fixation construct compared with the use of a locking plate alone. The data have shown that an anterior or lateral plate with a compression screw provides significantly greater stiffness than both a plate and 3 compression screws used individually. No significant difference was seen between the anterior plate with a compression screw and the lateral plate with a compression screw. No significant differences were found among the use of an anterior plate, a lateral plate, or 3 compression screws. We have concluded that when using a locking plate in an anterior or lateral configuration, the addition of a compression screw will considerably increase the primary bending stiffness of ankle arthrodesis. PMID:25116232

  10. Screw Dislocations in Graphite.

    PubMed

    Hennig, G R

    1965-02-12

    Graphite contains varying concentrations of screw dislocations whose Burgers vector parallels the c axis. Single crystals of natural graphite contain very few such dislocations; furthermore, their Burgers vector always exceeds 450 angstroms. Pyrolytic graphites annealed above 3000 degrees C contain abundant screw dislocations, ranging from 10(6) to 5 x 10(8) per square centimeter in two different samples prepared by somewhat different methods. The Burgers vectors of these screws are predominantly 3.35 angstroms. PMID:17758193

  11. The Use of Small Titanium Screws for Orthodontic Anchorage

    Microsoft Academic Search

    T. Deguchi; T. Takano-Yamamoto; R. Kanomi; J. K. Hartsfield; W. E. Roberts; L. P. Garetto

    2003-01-01

    The use of conventional dental implants for orthodontic anchorage is limited by their large size. The purpose of this study was to quantify the histomorphometric properties of the bone-implant interface to analyze the use of small titanium screws as an orthodontic anchorage and to establish an adequate healing period. Overall, successful rigid osseous fixation was achieved by 97% of the

  12. ORV Arthroscopic Reduction and Internal Fixation of Tibial Eminence Fractures

    PubMed Central

    Myer, Daniel M.; Purnell, Gregory J.; Caldwell, Paul E.; Pearson, Sara E.

    2013-01-01

    Tibial eminence fractures are an uncommon but well-described avulsion of the anterior cruciate ligament. Treatment principles are based on the amount and pattern of fracture displacement. Management has evolved from closed reduction and immobilization to arthroscopic reduction and internal fixation followed by early rehabilitation. Various fixation methods have evolved, ranging from arthroscopic reduction and percutaneous screw fixation to arthroscopic suture repair. We present a technique for arthroscopic reduction and internal fixation using a cannulated drill bit and high-strength suture. This technique facilitates anatomic reduction with uncomplicated tunnel placement and suture passing in an effort to allow strong fixation and early rehabilitation. PMID:24400179

  13. The upside down Endurant iliac limb stent graft for treatment of a common iliac artery aneurysm.

    PubMed

    Koike, Yuya; Nishimura, Jun-ichi; Hase, Soichiro; Yamasaki, Motoshige

    2014-01-01

    Endovascular repair of the coverage from the common iliac artery to the external iliac artery after the internal iliac artery embolization has been proven to be a safe and effective treatment in isolated iliac artery aneurysms. But in cases in which the diameter of the proximal sealing zone is larger than that of the distal sealing zone, a reverse-tapered device is needed. We described the off-label use of the Endurant iliac limb stent graft in an upside down configuration to accommodate this diameter mismatch. PMID:24178729

  14. Complications associated with thoracic pedicle screws in spinal deformity

    PubMed Central

    Li, Gang; Lv, Guohua; Passias, Peter; Kozanek, Michal; Metkar, Umesh S.; Liu, Zhongjun; Wood, Kirkham B.; Rehak, Lubos

    2010-01-01

    Thoracic pedicle screws have superior anchoring strength compared with other available fixation techniques. However, these are not universally accepted in many developing countries because of the concerns regarding safety and complications. In addition, there is evidence that pedicle morphology is unique in Chinese patients. The goal of this study was to analyze the complications seen at our institution, while using thoracic pedicle screws for the treatment of thoracic deformity, and to determine the safety of our techniques for the treatment of thoracic deformity in a Chinese population. From 1998 to 2005, there were 208 thoracic deformity patients treated at our institution, 70 of whom were male and 138 were female. Their age ranged from 11 to 55 years (mean of 14.9 years). All of them underwent corrective deformity surgery using posterior pedicle screw systems and follow-up was available for at least 3 years. Etiologic diagnoses included adolescent idiopathic scoliosis in 119 patients, congenital kyphoscoliosis in 38, adult scoliosis in 37 and undetermined in 14. Screw positions were evaluated using intraoperative and postoperative radiographs and a CT scan was performed when a concern for screw malposition was present. All radiographic evaluations were carried out in a double-blinded fashion. A total of 1,123 thoracic pedicle screws were inserted (5.4 thoracic screws/patient). The deformity correction rate was 81, 65 and 62% for idiopathic, congenital and adult scoliosis patients, respectively. The overall complication rate was 16.5% at the final follow-up. Complication rates directly and indirectly related to pedicle screws were 7.2 and 9.3%, respectively. There were no significant screw-related neurologic or visceral complications that adversely affected long-term results. The complications seen with thoracic pedicle screws in a Chinese population were similar to other populations and could be utilized safely for the treatment of thoracic deformity in this population. PMID:20237943

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

    PubMed Central

    2010-01-01

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

  16. A comparative evaluation of osteosynthesis with lag screws, miniplates, or Kirschner wires for mandibular condylar process fractures

    Microsoft Academic Search

    Tsutomu Sugiura; Kazuhiko Yamamoto; Kazuhiro Murakami; Masahito Sugimura

    2001-01-01

    Purpose: This study compared the clinical and radiologic outcomes of open treatment of mandibular condylar process fractures using lag screws, miniplates, or Kirschner wires. Patients and Methods: Open reduction and internal fixation was performed for severely displaced or dislocated mandibular condylar process fractures in 23 patients (26 fractures) using Eckelt lag screws, in 10 patients (10 fractures) using Kirschner wires,

  17. Suture Bridge Fixation of a Femoral Condyle Traumatic Osteochondral Defect

    PubMed Central

    Bowers, Andrea L.

    2008-01-01

    Internal fixation of a traumatic osteochondral defect presents a challenge in terms of obtaining anatomic reduction, fixation, and adequate compression for healing. Fixation with countersunk intraarticular screws, Herbert screws, bioabsorbable screws and pins, mini-cancellous screws, and glue tissue adhesive have been reported with varying results. We present an alternative fixation method used in two patients for femoral condylar defects that achieved anatomic reduction with compression via a cruciate-shaped suture bridge construct tied down over a bony bridge. This fixation method allowed early passive range of motion and permitted high-quality MRI for followup of fracture healing and articular cartilage integrity. Arthroscopic examination of one of two patients at 6 months followup showed the gross appearance of a healed, anatomically reduced fracture. With 1 year followup for one patient and 2 years for the other, the patients have resumed activity as tolerated with full, painless range of motion at the knee. Longer-term outcomes are unknown. However, the suture bridge is an alternative means of fixation with encouraging early results for treatment of traumatic osteochondral fragments in the knee. Level of Evidence: Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence. PMID:18584263

  18. Incorporation of C-1 lateral mass screws in occipitocervical and atlantoaxial fusions for children 8 years of age or younger. Technical note.

    PubMed

    Jea, Andrew; Taylor, Michael D; Dirks, Peter B; Kulkarni, Abhaya V; Rutka, James T; Drake, James M

    2007-08-01

    The authors describe the novel use of C-1 lateral mass screws in four children 8 years of age or younger, in whom occipitocervical or atlantoaxial fusion was performed for trauma or os odontoideum. The authors retrospectively reviewed the demographics and procedural data of four children, ranging in age from 2 to 8 years, who required and underwent surgical fixation. Although C1-2 screw/rod constructs involving individual C-1 lateral mass screws and C-2 pars interarticularis or pedicle screws have been widely applied in adults, only C1-2 transarticular screw fixation has been reported in children less than 8 years of age. This report demonstrates the successful results of rigid occipitocervical and atlantoaxial fusion in four children in whom C-1 lateral mass screws were placed as part of a screw/rod construct. There was one instance of a vertebral artery injury, and the lessons learned from this complication are discussed. PMID:18459894

  19. Surgical anatomy for pelvic external fixation.

    PubMed

    Solomon, L B; Pohl, A P; Chehade, M J; Malcolm, A M; Howie, D W; Henneberg, M

    2008-10-01

    Pelvic external fixators have a high rate of reported complications, most of which relate to pin placement. In this descriptive study, we analyzed the morphology of the ilium in cadaveric specimens and compared these with the measures obtained from normal human pelvic computer tomograph scans, and how these related to each of the three basic configurations of pin positioning for the external fixation of a pelvis: anterosuperior (Slätis type), anteroinferior (supra-acetabular), and subcristal. The irregular shape and size of the iliac wing and the abdominal wall overlying the pin's insertion site could hinder accurate placement of anterosuperior pins. Potential disadvantages of the use of anteroinferior pins was found related to the deep location of the anterior inferior iliac spine, interference with the hip flexion area, risk of hip joint penetration, and the variable obliquity of the ilium. As subcristal pins are positioned between two superficial bony landmarks of the iliac crest, our findings suggest that they are more likely to have a correct placement and avoid complications. PMID:18773474

  20. Mechanical performance of the standard Orthofix external fixator.

    PubMed

    Chao, E Y; Hein, T J

    1988-07-01

    Static and fatigue tests of the standard Orthofix unilateral external fixator (Orthofix SRL, Verona, Italy) were performed. Under similar fixation configurations, the Orthofix device offered higher bending stiffness in both directions, equal torsional stiffness, and lower axial stiffness when compared to the Hoffmann-Vidal quadrilateral frame with full pins. The bending resistance of the Orthofix ball joint was found to be proportional to its locking cam tightening torque. After applying 2 million loading cycles to the bone ends fixed by the device, the overall stiffness characteristics of the frame did not change significantly. Repetitive manual tightening and loosening of the ball joint caused abrasive wear on the cam and bushing surfaces. The locking position of the cam migrated for a mean of 45 degrees. After 50 cycles of tightening and bending to failure, the ball joint locking strength was reduced by 20% to 25%, but the stiffness did not change. Wear and stripping of the seat of the fixator body locking screw and the pin fixation screw threads were also noted. Based on the test results, the standard Orthofix device could be re-used, but certain fixator components must be inspected and replaced. The ball joint locking cam and fixation screws required periodic tightening during clinical application to prevent loss of frame stiffness under repetitive loading. Modifications of the fixator design are recommended to improve its mechanical performance. PMID:3405906

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

    SciTech Connect

    Ichihashi, Shigeo, E-mail: shigeoichihashi@yahoo.co.jp; Higashiura, Wataru; Itoh, Hirofumi; Sakaguchi, Shoji; Kichikawa, Kimihiko [Nara Medical University, Department of Radiology (Japan)

    2013-06-15

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

  2. Acute Iliac Artery Rupture: Endovascular Treatment

    SciTech Connect

    Chatziioannou, A.; Mourikis, D.; Katsimilis, J.; Skiadas, V., E-mail: bill_skiadas@yahoo.gr; Koutoulidis, V.; Katsenis, K.; Vlahos, L. [University of Athens, Radiology Department, Areteion Hospital (Greece)

    2007-04-15

    The authors present 7 patients who suffered iliac artery rupture over a 2 year period. In 5 patients, the rupture was iatrogenic: 4 cases were secondary to balloon angioplasty for iliac artery stenosis and 1 occurred during coronary angioplasty. In the last 2 patients, the rupture was secondary to iliac artery mycotic aneurysm. Direct placement of a stent-graft was performed in all cases, which was dilated until extravasation was controlled. Placement of the stent-graft was successful in all the cases, without any complications. The techniques used, results, and mid-term follow-up are presented. In conclusion, endovascular placement of a stent-graft is a quick, minimally invasive, efficient, and safe method for emergency treatment of acute iliac artery rupture, with satisfactory short- and mid-term results.

  3. Aortic-Iliac Thrombosis in a Horse

    PubMed Central

    Crawford, W. H.

    1982-01-01

    A horse with a history of chronic lameness was presented with signs of abdominal pain. A diagnosis of intestinal obstruction was initially made and treatment was ineffective. Further examination revealed an aortic obstruction in the area of the bifurcation of the iliac vessels. Postmortem results supported the clinical findings. The clinical signs of aortic-iliac thrombosis are consistent with the lameness pattern and abdominal distress. ImagesFigure 1. PMID:17422112

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

    PubMed Central

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

    2014-01-01

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

  5. Design of an occipito-cervical fixation device.

    PubMed

    Shepherd, D E; Bolger, C M; Leahy, J C; Mathias, K J; Hukins, D W

    2000-01-01

    Metal plates may be used to stabilize the cervical spine. The plates are attached to the posterior of the vertebra by placing screws into the lateral masses. The plating may be extended, in the form of rod or plate, to connect with and support the occiput. Several problems, such as screw loosening and the plate obscuring the surgeon's view as a screw is being inserted, have been identified with present plate systems. This paper describes the initial design for a cervical fixation device to overcome these problems, and the design and development that was undertaken to enable a prototype device to be manufactured. PMID:10997060

  6. Rotordynamics of Twin-Screw Pumps

    E-print Network

    Aboel Hassan Muhammed, Ameen

    2013-02-26

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

  7. Helical screw viscometer

    DOEpatents

    Aubert, J.H.; Chapman, R.N.; Kraynik, A.M.

    1983-06-30

    A helical screw viscometer for the measurement of the viscosity of Newtonian and non-Newtonian fluids comprising an elongated cylindrical container closed by end caps defining a circular cylindrical cavity within the container, a cylindrical rotor member having a helical screw or ribbon flight carried by the outer periphery thereof rotatably carried within the cavity whereby the fluid to be measured is confined in the cavity filling the space between the rotor and the container wall. The rotor member is supported by axle members journaled in the end caps, one axle extending through one end cap and connectable to a drive source. A pair of longitudinally spaced ports are provided through the wall of the container in communication with the cavity and a differential pressure meter is connected between the ports for measuring the pressure drop caused by the rotation of the helical screw rotor acting on the confined fluid for computing viscosity.

  8. A prospective randomized study of ACL-reconstructions using bone-patellar tendon-bone grafts fixed with bioabsorbable or metal interference screws

    Microsoft Academic Search

    Jon Olav Drogset; Lene Granrud Straume; Ingrid Bjørkmo; Gunnar Myhr

    2011-01-01

    \\u000a Abstract\\u000a Introduction  Bioabsorbable screws are, at the expense of metal screws, increasingly used as fixation device in ACL-reconstructions. The\\u000a possible advantages with bioabsorbable screws are better postoperative MRI evaluations and easier revision surgery.\\u000a \\u000a \\u000a \\u000a \\u000a Purpose  The aim of this study was to compare the clinical outcome after ACL-reconstructions with BPTB-grafts fixed with metal interference\\u000a screws or bioabsorbable screws 7 years postoperatively. The resorption of

  9. SPECT-CT Assessment of Pseudarthrosis after Spinal Fusion: Diagnostic Pitfall due to a Broken Screw.

    PubMed

    Rager, Olivier; Amzalag, Gaël; Varoquaux, Arthur; Schaller, Karl; Ratib, Osman; Tessitore, Enrico

    2013-01-01

    A 43-year-old drug addicted female was referred for a L5-S1 posterolateral in situ fixation with autologous graft because of an L5/S1 severe discopathy with listhesis. After six months, low back pain recurred. A Tc-99m HDP SPECT-CT diagnosed a pseudarthrosis with intense uptake of the L5-S1 endplates and a fracture of the right S1 screw just outside the metal-bone interface without any uptake or bone resorption around the screw. The absence of uptake around a broken screw is a pitfall that the physician should be aware of. PMID:24159394

  10. SPECT-CT Assessment of Pseudarthrosis after Spinal Fusion: Diagnostic Pitfall due to a Broken Screw

    PubMed Central

    Rager, Olivier; Amzalag, Gaël; Varoquaux, Arthur; Schaller, Karl; Ratib, Osman; Tessitore, Enrico

    2013-01-01

    A 43-year-old drug addicted female was referred for a L5-S1 posterolateral in situ fixation with autologous graft because of an L5/S1 severe discopathy with listhesis. After six months, low back pain recurred. A Tc-99m HDP SPECT-CT diagnosed a pseudarthrosis with intense uptake of the L5-S1 endplates and a fracture of the right S1 screw just outside the metal-bone interface without any uptake or bone resorption around the screw. The absence of uptake around a broken screw is a pitfall that the physician should be aware of. PMID:24159394

  11. The Screw-worm.

    E-print Network

    Francis, M. (Mark)

    1890-01-01

    , it is thought advisable to give a more exhaustive report of the life history of the insect, together with illustrations (see note 1) and description (see note 2) for identification. The screw-worm is the larva or maggot of a dipterous insect (Lacilia macel...

  12. NUT SCREW MECHANISMS

    Microsoft Academic Search

    1958-01-01

    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 ;

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

    PubMed Central

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

    2007-01-01

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

  14. Modified osteomyocutaneous iliac crest flaps transplantation.

    PubMed

    Liu, Jun; Song, Dajiang; Li, Jinsong; Xu, Jian; Lv, Hongbin

    2015-04-01

    The paper aims to improve the operative technique of osteomyocutaneous iliac crest flap harvesting, further minimise morbidity of donor site, and improve the effect of recipient site reconstruction. From March 2005 to March 2011, 55 cases of osteomyocutaneous iliac crest flap harvested by different methods were performed to reconstruct the defects of the extremities. Twenty-nine cases were reconstructed with a traditional deep circumflex iliac artery osteomusculocutaneous flap. Twenty-six cases were repaired with modified osteomyocutaneous iliac crest flaps. In 29 cases with a traditional DCIA osteomusculocutaneous flap, two cases showed the injured lateral femoral cutaneous nerve. Flapnecrosis was significant in two cases. Arterial compromise occurred in one case 5 days after operation completion and led to flap failure. Three flaps developed postoperative venous congestion, but only one flap received re-exploration. In the other two cases, some stitches were removed for decompression. All three flaps survived. In two cases, marginal flap necrosis occurred, but no secondary skin grafting was required. In 26 cases with modified flap transplantation, one case showed the injured lateral femoral cutaneous nerve. All flaps survived totally. Osseous integration was achieved in all 55 cases in 3 ? 9 months after operation. The modified osteomyocutaneous iliac crest flap technique enhances flap safety, provides the additional advantages of reducing donor-site morbidity, and improves the recipient-site contour. PMID:25001367

  15. Do Newer-Generation Bioabsorbable Screws Become Incorporated into Bone at Two Years After ACL Reconstruction with Patellar Tendon Graft?

    PubMed Central

    Cox, Charles L.; Spindler, Kurt P.; Leonard, James P.; Morris, Brent J.; Dunn, Warren R.; Reinke, Emily K.

    2014-01-01

    Background: Bioabsorbable interference screws are used frequently for graft fixation in ACL (anterior cruciate ligament) reconstruction. The resorption properties of many available screws that are marketed as bioabsorbable are not well defined. The CALAXO (Smith & Nephew Endoscopy) and MILAGRO (DePuy Synthes) bioabsorbable screws contain polymers of poly(lactic-co-glycolic acid) (PLGA) plus additives to encourage osseointegration over time. The purpose of this study was to evaluate radiographic and magnetic resonance imaging (MRI) properties and compare patient-reported outcomes at a minimum of two years of follow-up after ACL reconstruction using CALAXO or MILAGRO bioabsorbable interference screws. Methods: A cohort of patients who underwent ACL reconstruction in which the fixation used was either CALAXO or MILAGRO screws returned for repeat radiographs for evaluation of tunnel widening, repeat MRI for evaluation of graft integrity and screw breakdown, and completion of the pain and symptom items of the KOOS (Knee injury and Osteoarthritis Outcome Score) questionnaire. Results: At a mean of three years (range, 2.5 to 4.0 years) after surgery, thirty-one patients with sixty-two CALAXO screws and thirty-six patients with seventy-two MILAGRO screws returned for repeat evaluation. Two blinded, independent reviewers found no significant differences between the two screw types when comparing radiographs for tibial or femoral tunnel widening or MRIs for graft integrity, tibial and femoral foreign body reactions, or femoral screw degradation. Both reviewers found a significant difference between the two screw types when comparing tibial screw degradation properties (p < 0.01). All analyzed CALAXO screws were rated as partially intact or degraded; the MILAGRO screws were more likely to be rated as intact. No significant differences were noted between the two screw types when comparing the two KOOS subscales. Conclusions: CALAXO screws in the tibial tunnel were more likely to be rated as degraded or partially degraded compared with MILAGRO screws at a mean of three years after implantation for ACL reconstruction. Although these newer-generation bioabsorbable screws were designed to promote osseointegration, no tunnel narrowing was noted, and in the majority of cases the remains of the screws were present at approximately three years. Level of Evidence: Therapeutic Level II. See Instructions for Authors for a complete description of levels of evidence. Peer Review: This article was reviewed by the Editor-in-Chief and one Deputy Editor, and it underwent blinded review by two or more outside experts. The Deputy Editor reviewed each revision of the article, and it underwent a final review by the Editor-in-Chief prior to publication. Final corrections and clarifications occurred during one or more exchanges between the author(s) and copyeditors. PMID:24500587

  16. Transsacral screw safe zone size by sacral segmentation variations.

    PubMed

    Lee, John J; Rosenbaum, Samuel L; Martusiewicz, Alex; Holcombe, Sven A; Wang, Stewart C; Goulet, James A

    2015-02-01

    Variations in sacral segmentation may preclude safe placement of transsacral screws for posterior pelvis fixation. We developed a novel automated 3D technique to determine the safe zone size for transsacral screws in the upper two sacral segments in 526 adult pelvis computed tomography scans. Safe zone sizes were then compared by gender and sacral segmentation variations (number of neuroforamen and the presence/absence of lumbosacral transitional vertebrae, ± LSTV). Ten millimeters was used as the safety threshold for a large screw. 3 (0.6%), 366 (70%), and 157 (30%) sacra had 3, 4, or 5 neuroforamen, respectively. Eighty-eight (17%) were +LSTV. Safe zone size depended on gender, number of neuroforamen in -LSTV sacra and presence of LSTV (p < 0.001) but not on the uni- or bilateral nature of the LSTV. 17% of -LSTV sacra were below the safety threshold in S1, 27% in S2, whereas 3% of +LSTV sacra were below in S1, 74% in S2. Of -LSTV sacra that cannot take an S1 screw safely, 77% can do so in S2, leaving only 4% of sacra that cannot accommodate a screw safely in either upper segment. The results demonstrate a predictable pattern of safe zone size based on gender and sacral segmentation variations. PMID:25231682

  17. Bladder necrosis secondary to internal iliac artery embolization following pelvic fracture.

    PubMed

    Ali, Ahmed; Nabi, Ghulam; Swami, Satchi; Somani, Bhaskar

    2014-04-01

    A 49-year-old man following a road traffic accident (RTA) had an unstable pelvic fracture with urethral injury. Internal pelvic fixation with Supra-pubic catheter (SPC) drainage of his bladder was done. This failed to stop the bleeding and a pelvic angiography with bilateral internal iliac embolization using steel coils was performed successfully controlling the bleeding. After 4 weeks, the patient developed wound infection (Clavien Grade III) and on exploration, bladder necrosis was found. A urinary diversion using ileal conduit with excision of bladder was performed. A biopsy of the excised bladder confirmed bladder necrosis with a foreign material (coil) in one arterial lumen. PMID:24833834

  18. Anterior dislocation of hip following DHS fixation of intertrochanteric fracture: A case report

    PubMed Central

    Syed, Farhan; Eachempati, Krishna Kiran; Apsingi, Sunil

    2014-01-01

    Intertrochanteric fractures are commonly seen in elderly population. 90% of these occur following a trivial fall. Dynamic hip screw fixation is one of the most common modality of treatment, although intramedullary fixation devices are gaining popularity in recent times, especially in unstable fractures. Dislocation of hip following a DHS fixation of hip is a very rare complication. There are only two case reports which describes dislocation of hip following DHS fixation of an intertrochanteric fracture. Here we present a case of anterior dislocation of hip following DHS fixation of an intertrochanteric fracture. We also discuss about the possible causes of this rare complication, its management and follow up.

  19. New implant designs for fracture fixation in osteoporotic bone

    Microsoft Academic Search

    J. Goldhahn; J. Seebeck; R. Frei; B. Frenz; I. Antoniadis; E. Schneider

    2005-01-01

    Screws are one of the limiting factors for fixation of implants, particularly in poor bone quality. A class of new implants with an implant–bone–interface optimized regarding load transition by increasing the peripheral area might improve the anchorage of implants in osteoporotic bone. However, the shape of these implants requires new technologies for insertion. The goal of the work presented here

  20. Late diagnosis of perforation of the aorta by a pedicle screw.

    PubMed

    Soultanis, Konstantinos Chr; Sakellariou, Vasileios I; Starantzis, Konstantinos A; Papagelopoulos, Panayiotis J

    2013-08-01

    Although the clinical and biomechanical advantages of pedicle screws are well documented, the accuracy of their insertion is always a concern.Injury of neurovascular structures could be devastating. Perforation of the aorta from posteriorly placed screws is fortunately rare but could end up being lethal. We present a review of the current literature along with two illustrative cases with aorta perforation from posterior pedicle screws. An 82-year-old female with a history of thoracic kyphosis and a 26-year-old female with scoliotic deformity were referred to our institution owing to back pain. Both patients had undergone correction of their deformities and posterior fixation using posterior pedicle screws and rods 5 years previously. During the diagnostic work-up, which included CT scans, we incidentally found one pedicle screw to be malpositioned, exiting the vertebral body and perforating the aorta. The patients were offered a combined orthopaedic and vascular procedure, including screw removal and endovascular stenting of the aorta. Potential complications from the presence of a screw inside the pulsatile aorta, and the complexity of revision surgery should be well considered before proceeding to such a difficult surgical procedure. Systemic postoperative follow-up imaging and safer intraoperative practices during screw placement are important. PMID:24205763

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

    PubMed Central

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

    2015-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

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

  3. An isolated iliac wing stress fracture in a marathon runner.

    PubMed

    Amorosa, Louis F; Serota, Alana C; Berman, Nathaniel; Lorich, Dean G; Helfet, David L

    2014-02-01

    Iliac stress fractures are uncommon and are usually insufficiency fractures related to osteoporosis. Only 2 previous case reports of iliac stress fractures in runners that extended into the sacroiliac joint, and 1 previous case of an isolated iliac wing stress fracture not involving the sacroiliac joint were found in the English language literature. We report on a second case of an isolated stress fracture of the iliac wing in a female marathon runner and the associated diagnosis of the female athlete triad. Iliac stress fractures can be an occult cause of hip pain in athletes and should be included in the differential diagnosis of hip pain in a marathon runner. PMID:24551864

  4. Far cortical locking screws in distal femur fractures.

    PubMed

    Adams, John D; Tanner, Stephanie L; Jeray, Kyle J

    2015-03-01

    Distal femur fractures routinely heal by secondary bone healing, which relies on interfragmentary motion. Periarticular locking plates are commonly used for fixation in distal femur fractures but are associated with a high nonunion rate, likely due to the stiffness of the constructs. Far cortical locking (FCL) screws are designed to allow micromotion at the near cortex while maintaining purchase in only the far cortex. Although clinical data are limited, these screws have been shown in biomechanical studies to provide excellent interfragmentary motion, and animal models have shown increased callus formation compared with traditional locking screws. The purpose of this study was to examine the clinical effects that FCL screws have on healing in distal femur fractures treated with locked constructs. In this retrospective case series, 15 patients with a distal femur fracture treated with MotionLoc screws (Zimmer, Warsaw, Indiana) were analyzed. Serial radiographs were evaluated for callus presence and time to union. All fractures were either 33-A3 or 33-C2 according to the AO classification system, and 5 (33%) were open. Bone loss was recorded in 2 patients. There were no nonunions, and average time to union was 24 weeks. There were no implant failures, and all 5 open fractures, including the 2 with bone loss, healed without intervention. There was 1 reoperation due to painful hardware. Although this is a small case series, these results are promising. Far cortical locking screws may provide the answer to the high nonunion rate associated with distal femur fractures treated with traditional locked constructs. [Orthopedics. 2015; 38(3):e153-e156.]. PMID:25760500

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

    PubMed

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

    2004-09-01

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

  6. Intraosseous correction of misdirected cannulated screws and fracture malalignment using a bent tip 2.0 mm guidewire: technique and indications.

    PubMed

    Scolaro, John A; Routt, Milton Lee Chip

    2013-07-01

    Percutaneous pelvic screw placement is a technically demanding procedure. A precise intraosseous pathway must be prepared before screw placement into any osseous fixation pathway of the pelvis. Adjustments to a drill or guidewire become increasingly difficult as the instrument is advanced within the pelvis. We present a reliable and reproducible technique using a 2.0 mm guidewire that allows for correction of an initially misdirected drill within the pelvis. This technique also allows for manipulation and reduction of certain malaligned pelvic fractures prior to percutaneous cannulated screw placement. This technique does not substitute for poor surgical technique but is used to optimize the position of percutaneously placed pelvic screws. PMID:23589066

  7. Biomechanical characterisation of a degradable magnesium-based (MgCa0.8) screw.

    PubMed

    Waizy, Hazibullah; Weizbauer, Andreas; Maibaum, Matthias; Witte, Frank; Windhagen, Henning; Lucas, Arne; Denkena, Berend; Meyer-Lindenberg, Andrea; Thorey, Fritz

    2012-03-01

    Magnesium alloys have been in the focus of research in recent years as degradable biomaterial. The purpose of this study was the biomechanical characterisation of MgCa0.8-screws. The maximum pull out force of screws was determined in a synthetic bone without corrosion and after fixed intervals of corrosion: 24, 48, 72 and 96 h. This in vitro study has been carried out with Hank's solution with a flow rate corresponding to the blood flow in natural bone. A maximum pull out force (F(max)) of 201.5 ± 9.3 N was measured without corrosion. The biomechanical parameter decreased by 30% after 96 h in corrosive medium compared to the non-corrosion group. A maximum load capacity of 28 ± 7.6 N/h was determined. Our biomechanical data suggests that this biodegradable screw provides a promising bone-screw-fixation and has great potential for medical application. PMID:22210311

  8. An Innovative Universal Screw Removal Instrument

    PubMed Central

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

    2015-01-01

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

  9. Stability of fixation of diacapitular fractures of the mandibular condylar process by ultrasound-aided resorbable pins (SonicWeld Rx® System) in pigs.

    PubMed

    Schneider, Matthias; Eckelt, Uwe; Reitemeier, Bernd; Meissner, Heike; Richter, Gerd; Loukota, Richard; Stadlinger, Bernd

    2011-06-01

    To assess the stability of osteosynthesis in diacapitular condylar fractures we compared fixation using ultrasound-aided resorbable pins with poly-(D,L)-lactide (SonicWeld® Rx, KLS Martin, Tuttlingen, Germany) with that of titanium screws in 20 pig mandibles, 10 in each group. Isolated diacapitular fractures were created using a surgical chisel. Ten fractures were each repositioned and fixed by two pins (17 and 11 mm long, 2.1mm in diameter), and 10 fractures were fixed by two titanium screws of equal length, 2.0mm in diameter. Shear tests were done immediately after treatment to measure the maximum force to disrupt the fixation. Fixation with pins resisted mean shear forces of 310N until the pins fractured, whereas fixation with titanium screws failed at 918N when the screws pulled out of the bone. Long-term stability and resorption of pins will have to be analysed in an in vivo study. PMID:20627494

  10. Biomechanical comparison of different combinations of hook and screw in one spine motion unit - an experiment in porcine model

    PubMed Central

    2014-01-01

    Background The biomechanical performance of the hooks and screws in spinal posterior instrumentation is not well-characterized. Screw-bone interface failure at the uppermost and lowermost vertebrae is not uncommon. Some have advocated for the use of supplement hooks to prevent screw loosening. However, studies describing methods for combined hook and screw systems that fully address the benefits of these systems are lacking. Thus, the choice of which implant to use in a given case is often based solely on a surgeon’s experience instead of on the biomechanical features and advantages of each device. Methods We conducted a biomechanical comparison of devices instrumented with different combinations of hooks and screws. Thirty-six fresh low thoracic porcine spines were assigned to three groups (12 per group) according to the configuration used for of fixation: (1) pedicle screw; (2) lamina hook and (3) combination of pedicle screw and lamina hook. Axial pullout tests backward on transverse plane in the direction normal to the rods were performed using a material testing machine and a specially designed grip with self-aligned function. Results The pullout force for the pedicle screws group was significantly greater than for the hooks and the combination (p??0.05). Conclusions Pedicle screws achieve the maximal pullout strength for spinal posterior instrumentation. PMID:24913189

  11. 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

  12. 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. PMID:21126086

  13. 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.

  14. Split spline screw

    NASA Technical Reports Server (NTRS)

    Vranish, John M. (inventor)

    1993-01-01

    A split spline screw type payload fastener assembly, including three identical male and female type split spline sections, is discussed. The male spline sections are formed on the head of a male type spline driver. Each of the split male type spline sections has an outwardly projecting load baring segment including a convex upper surface which is adapted to engage a complementary concave surface of a female spline receptor in the form of a hollow bolt head. Additionally, the male spline section also includes a horizontal spline releasing segment and a spline tightening segment below each load bearing segment. The spline tightening segment consists of a vertical web of constant thickness. The web has at least one flat vertical wall surface which is designed to contact a generally flat vertically extending wall surface tab of the bolt head. Mutual interlocking and unlocking of the male and female splines results upon clockwise and counter clockwise turning of the driver element.

  15. Cement augmentation of intertrochanteric fracture fixation: a cadaver comparison of 2 techniques.

    PubMed

    Choueka, J; Koval, K J; Kummer, F J; Zukerman, J D

    1996-04-01

    We evaluated 2 techniques of cement augmentation to enhance fixation of intertrochanteric hip fractures. 4 fixation groups with 6 cadaver femurs in each group were compared: stainless steel lag screw and side plate with and without cement augmentation and a titanium alloy expandable dome plunger and side plate with and without cement augmentation. Gauges were used to establish the mechanical behavior of intact and then fractured femurs to simple uniaxial loads. Subsequent loading to failure allowed determination of maximum fixation strengths and modes of failure. Cement augmentation of each device increased its load to failure. There was no significant difference between the cemented lag screw and the uncemented dome plunger groups with average loads to failure of 4.0 x 10(3) N. The greatest average load to failure was in the cemented dome plunger group (5.6 x 10(3) N) with the lowest in the uncemented sliding hip screw group (3.6 x 10(3) N). Device cut-out as a cause of failure occurred mostly in the uncemented lag screw group. Sliding was enhanced by those methods that increased the fixation surface area within the femoral head, unless cement encroached in the region of the barrel-screw junction. Strain analysis showed that the dome plunger unloaded the bone at the calcar, regardless of cement augmentation, while the sliding hip screw allowed for compressive stresses in this area. Proper cement augmentation increases load to failure and minimizes nail cut-out for both devices studied. However, the dome plunger, a device with a large fixation area in the femoral head, was equally effective and eliminated potential cement encroachment. Failure of intertrochanteric fracture fixation in osteoporotic bone may be minimized by an appropriate choice of device or cement augmentation. PMID:8623570

  16. Common iliac and hypogastric aneurysms: open and endovascular repair.

    PubMed

    Katsargyris, A; Oikonomou, K; Klonaris, C; Bal, A; Yanar, F; Verhoeven, E L

    2015-04-01

    Currently, there are a variety of open surgical, endovascular, and hybrid options to treat iliac artery aneurysms (IAA). Anatomy of the common iliac artery (CIA) with regard to proximal and distal neck, involvement of the iliac bifurcation, and choice to preserve the ipsilateral internal iliac artery (IIA) all play a role in the decision process towards the preferred treatment method. This manuscript describes the available open surgical and endovascular techniques for the treatment of IAA. Indications, advantages and limitations, and outcomes of each technique are discussed. PMID:25512317

  17. Successful Emergency Stenting of Acute Ruptured False Iliac Aneurysm

    SciTech Connect

    Bierdrager, Edwin; Lohle, Paul N.M.; Schoemaker, Cees M.; Lampmann, Leo E.H. [Department of Radiology, St. ElisabethHospital, Hilvarenbeekse weg 60, 5022 GC, Tilburg (Netherlands); Berge Henegouwen, Dennis P. van; Hamming, Jaap F. [Department ofSurgery, St. Elisabeth Hospital, Hilvarenbeekse weg 60, 5022 GC, Tilburg (Netherlands)

    2002-01-15

    A 75-year-old man complaining of acute abdominal pain, 1 month after elective surgical repair of an abdominal aortic aneurysm by an aortabi-iliac bypass graft, was referred and admitted to the emergency room. Imaging by sonography and computed tomography scan revealed a ruptured iliac pseudoaneurysm at the right iliac anastomotic site with associated large retroperitoneal hematoma. We inserted a self-expanding covered Z-stent graft by a transfemoral approach and the iliac anastomotic pseudoaneurysm was successfully excluded. Our case demonstrates the possibilities of an endovascular approach for providing a fast, efficient and less aggravating procedure in order to treat these life-threatening conditions.

  18. Electromagnetic Navigation in Minimally Invasive Spine Surgery: Results of a Cadaveric Study to Evaluate Percutaneous Pedicle Screw Insertion

    PubMed Central

    Fraser, Justin F.; Von Jako, Ron; Carrino, John A.

    2008-01-01

    Background This cadaveric study compared efficacy and safety of an electromagnetic (EM) guidance system versus conventional fluoroscopy for percutaneous pedicle screw fixation. As percutaneous pedicle screw fixation becomes increasingly common in spinal surgery, intraoperative imaging systems that maximize efficiency while minimizing radiation exposure and inaccurate trajectories will be progressively more important. Published studies have validated the safety of percutaneous screw fixation using conventional fluoroscopic guidance and frameless optical stereotaxy, though EM guidance systems have not been evaluated for percutaneous placement in the lumbosacral spine. The aim of the study was to evaluate the clinical applicability of an EM system for minimally invasive spine fusion in the lumbosacral spine. Methods Five human cadaveric specimens underwent bilateral lumbosacral percutaneous screw fixation from L1 to S1 using conventional anteroposterior (AP) and lateral fluoroscopic techniques on one side and 2-dimesional (2D) EM guidance on each matching side. Intraoperative efficiency was evaluated, and pedicle, vertebral, and critical breach rates were assessed on postoperative computed tomography (CT). Results Overall mean fluoroscopy time per screw was 58.9 ± 44.7 seconds for conventional fluoroscopy compared to 27.4 ± 13.5 seconds for electromagnetic guidance (P = .0003). Pedicle, vertebral, and critical breach rates for the L1-S1 were 32.1%, 10.7%, and 25.0% for conventional fluoroscopy and 42.8%, 10.7%, and 14.1% for electromagnetic guidance (difference not statistically significant [ns]). In comparing critical breaches in the lumbar spine (L1-L5), there was a significant difference between 2-D EM guidance (0) and CF guidance (6) (P = .02). Conclusions Two-dimensional EM navigation provides a modality for lumbosacral percutaneous pedicle screw fixation that is more efficient and safer than conventional fluoroscopy. This data provides a foundation for further clinical trials of this technology. Level of Evidence Level 5 – Bench Research

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

    PubMed

    Choi, Sungwook; Kang, Hyunseong; Bang, Hyeongsig

    2014-08-01

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

  20. Coronal Acetabular Fractures: The Anterior Approach in Computed Tomography-Navigated Minimally Invasive Percutaneous Fixation

    Microsoft Academic Search

    Augustinus Ludwig Jacob; Norbert Suhm; Achim Kaim; Pietro Regazzoni; Wolfgang Steinbrich; Peter Messmer

    2000-01-01

    Purpose: To demonstrate the technical feasibility of the anterior approach to the coronal roof component of carefully selected acetabular\\u000a fractures in computed tomography (CT)-navigated closed reduction and percutaneous fixation (CRPF).\\u000a \\u000a \\u000a \\u000a \\u000a Methods: Four patients with nondisplaced or slightly displaced coronal fractures of the acetabular roof were treated with percutaneous\\u000a screw fixation. Screws were implanted over guidepins placed under CT navigation. Mean

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

    PubMed

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

    2012-06-01

    Unequivocally, pedicle screw instrumentation has evolved as a primary construct for the treatment of both common and complex spinal disorders. However an inevitable and potentially major complication associated with this type of surgery is misplacement of a pedicle screw(s) which may result in neural and vascular complications, as well as impair the biomechanical stability of the spinal instrumentation resulting in loss of fixation. In light of these potential surgical complications, critical reviews of outcome data for treatment of chronic, low-back pain using pedicle screw instrumentation concluded that "pedicle screw fixation improves radiographically demonstrated fusion rates;" however the expense and complication rates for such constructs are considerable in light of the clinical benefit (Resnick et al. 2005a). Currently, neuromonitoring using free-run and evoked (triggered) electromyography (EMG) is widely used and advocated for safer and more accurate placement of pedicle screws during open instrumentation procedures, and more recently, guiding percutaneous placement (minimally invasive) where the pedicle cannot be easily inspected visually. The latter technique, evoked or triggered EMG when applied to pedicle screw instrumentation surgeries, has been referred to as the pedicle screw stimulation technique. As concluded in the Position Statement by the American Society of Neurophysiological Monitoring (ASNM), multimodality neuromonitoring using free-run EMG and the pedicle screw stimulation technique was considered a practice option and not yet a standard of care (Leppanen 2005). Subsequently, the American Association of Neurological Surgeons/Congress of Neurological Surgeons (AANS/CNS) Joint Section on Disorders of the Spine and Peripheral Nerves published their "Guidelines for the Performance of Fusion Procedures for Degenerative Disease of the Lumbar Spine" (Heary 2005, Resnick et al. 2005a, Resnick et al. 2005b). It was concluded that the "primary justification" of intraoperative neuromonitoring"... is the perception that the safety and efficacy of pedicle screw fixation are enhanced..." (Resnick et al. 2005b). However in summarizing a massive (over 1000 papers taken from the National Library of Medicine), contemporary, literature review spanning nearly a decade (1996 to 2003), this invited panel (Resnick et al. 2005b) recognized that the evidence-based documents contributing to the parts related to pedicle screw fixation and neuromonitoring were "... full of potential sources of error ..." and lacked appropriate, randomized, prospective studies for formulating rigid standards and guidelines. Nevertheless, current trends support the routine use and clinical utility of these neuromonitoring techniques. In particular free-run and triggered EMG have been well recognized in numerous publications for improving both the accuracy and safety of pedicle screw implantation. Currently, treatment with pedicle screw instrumentation routinely involves all levels of the spine - lumbosacral, thoracic, and cervical. Significant historical events, various neuromonitoring modalities, intraoperative alarm criteria, clinical efficacy, current trends, and caveats related to pedicle screw stimulation along the entire vertebral column will be reviewed. PMID:22808751

  2. Evaluation of the syndesmotic-only fixation for Weber-C ankle fractures with syndesmotic injury

    PubMed Central

    Mohammed, R; Syed, S; Metikala, S; Ali, SA

    2011-01-01

    Background: With the length of the fibula restored and the syndesmosis reduced anatomically, internal fixation using a plating device may not be necessary for supra-syndesmotic fibular fractures combined with diastasis of inferior tibio-fibular joint. A retrospective observational study was performed in patients who had this injury pattern treated with syndesmosis-only fixation. Materials and Methods: 12 patients who had Weber type-C injury pattern were treated with syndesmosis only fixation. The treatment plan was followed only if the fibular length could be restored and if the syndesmosis could be anatomically reduced. Through a percutaneous or mini-open reduction and clamp stabilization of the syndesmosis, all but one patient had a single tricortical screw fixation across the syndesmosis. Patients were kept non-weight-bearing for 6 weeks, followed by screw removal at an average of 8 weeks. Outcomes were assessed using an objective ankle scoring system (Olerud and Molander scale) and by radiographic assessment of the ankle mortise. Results: At a mean follow-up of 13 months, the functional outcome score was 75. Excellent to good outcomes were noted in 83% of the patients. Ankle mortise was reduced in all cases, and all but one fibular fracture united without loss of fixation. Six patients had more than one malleolar injury, needing either screw or anchor fixations. One patient had late diastasis after removal of the syndesmotic screw and underwent revision surgery with bone grafting of the fibula. This was probably due to early screw removal, before union of the fibular fracture had occurred. Conclusion: We recommend syndesmosis-only fixation as an effective treatment option for a combination of syndesmosis disruption and Weber type-C lateral malleolar fractures. PMID:21886929

  3. Delayed Iliac Abscess as An Unusual Complication of an Iliac Bone Graft in an Orthognathic Case

    Microsoft Academic Search

    G. De Riu; S. M. Meloni; M. T. Raho; R. Gobbi; A. Tullio

    2008-01-01

    The reconstruction of large maxillofacial defects generally requires harvesting bone from extra-oral sites. The main source of autogenous bone is the iliac crest. This donor site is used to obtain bone for augmentation in orthopaedic surgery, neurosurgery, and oral and maxillofacial surgery, where the main indications are secondary and tertiary osteoplasty in patients with cleft-lip and palate, reconstruction of bony

  4. 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. PMID:25390875

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

    PubMed Central

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

    2009-01-01

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

  6. New techniques and alternative fixation for the lapidus arthrodesis.

    PubMed

    Young, Nathan J; Zelen, Charles M

    2013-07-01

    Arthrodesis of the first metatarsocuneiform joint is a powerful and durable procedure to help correct moderate to severe hallux valgus and/or first ray hypermobility. However, painful nonunion remains a notoriously high potential outcome. Research regarding locking plates seems promising, and data show lower rates of nonunion. Innovative fixation techniques are new and should be considered in the future as further literature is available on their long-term use. Regardless of the fixation, proper joint preparation and good compression is fundamentally the most important. A case of Lapidus fusion with locking plates after a failed arthrodesis with screws alone is presented. PMID:23827494

  7. Deviation analysis of atlantoaxial pedicle screws assisted by a drill template.

    PubMed

    Hu, Yong; Yuan, Zhen-Shan; Kepler, Christopher K; Albert, Todd J; Xie, Hui; Yuan, Jian-Bing; Dong, Wei-Xin; Wang, Cheng-Tao

    2014-05-01

    Although C1-C2 pedicle screw fixation provides an excellent fusion rate and rigid fixation, this technique has a potential risk. It is essential to develop an accurate screwing method to avoid this neurovascular injury. To develop and validate the accuracy of a novel navigational template for C1-C2 pedicle screw placement in cadaveric specimens, computed tomography scans with 1-mm-wide cuts were obtained of 32 cadaveric cervical specimens. The authors developed 64 three-dimensional full-scale templates that were created by computer modeling with a rapid prototyping technique from the computed tomography data. Drill templates were constructed with a custom trajectory for each level and side. The drill templates were used to guide the establishment of a pilot hole for screw placement. The average distances between ideal and actual entry points of the C1 pedicle screws in the x, y, and z axes were 0.16±0.46 mm, 0.11±0.52 mm, and -0.01±0.54 mm, respectively, on the left side and 0.11±0.49 mm, 0.01±0.56 mm, and -0.09±0.59 mm, respectively, on the right side. The average distances between ideal and actual entry points of the C2 pedicle screws in the x, y, and z axes were 0.05±0.54 mm, 0.20±0.59 mm, and -0.06±0.58 mm, respectively, on the left side and 0.17±0.55 mm, 0.1±0.58 mm, and -0.01±0.49 mm, respectively, on the right side. Factors related to human error and imprecision are responsible for most malpositioning of instrumentation. The rapid prototyping drill template for C1-C2 screw placement is described to minimize human error, although it introduces error related to computer software and variation in manufacturing. PMID:24810817

  8. Cervical pedicle screw placement: feasibility and accuracy of two new insertion techniques based on morphometric data.

    PubMed

    Reinhold, M; Magerl, F; Rieger, M; Blauth, M

    2007-01-01

    This morphometric and experimental study was designed to assess the dimensions and axes of the subaxial cervical pedicles and to compare the accuracy of two different techniques for subaxial cervical pedicle screw (CPS) placement using newly designed aiming devices. Transpedicular fixation is increasingly used for stabilizing the subaxial cervical spine. Development of the demanding technique is based on morphometric studies of the pedicle anatomy. Several surgical techniques have been developed and evaluated with respect to their feasibility and accuracy. The study was carried out on six conserved human cadavers (average age 85 years). Axes and dimensions of the pedicles C3-C7 (60 pedicles) were measured using multislice computed tomography (CT) images prior to surgery. Two groups consisting of 3 specimens and 30 pedicles each were established according to the screw placement technique. For surgical technique 1 (ST1) a para-articular mini-laminotomy was performed. Guidance of the drill through the pedicle with a handheld aiming device attached onto the medial aspect of the pedicle inside the spinal canal. Screw hole preparation monitored by lateral fluoroscopy. In surgical technique 2 (ST2) a more complex aiming device was used for screw holes drilling. It consists of a frame with a fully adjustable radiolucent arm for carrying the instruments necessary for placing the screws. The arm was angled according to the cervical pedicle axis as determined by the preoperative CT scans. Drilling was monitored by lateral fluoroscopy. In either technique 3.5 mm screws made of carbon fiber polyetheretherketone (CF-PEEK) were inserted. The use of the CF-PEEK screws allowed for precise postoperative CT-assessment since this material does not cause artifacts. Screw placement was qualified from ideal to unacceptable into four grades: I = screw centered in pedicle; IIa = perforation of pedicle wall less than one-fourth of the screw diameter; IIb = perforation more than one-fourth of the screw diameter without contact to neurovascular structures; III = screw more than one-fourth outside the pedicle with contact to neurovascular structures. Fifty-six pedicle screws could be evaluated according to the same CT protocol that was used preoperatively. Accuracy of pedicle screw placement did not reveal significant differences between techniques 1 and 2. A tendency towards less severe misplacements (grade III) was seen in ST2 (15% in ST2 vs. 23% in ST1) as well as a higher rate of screw positions graded IIa (62% in ST2 vs. 43% in ST1). C4 and C5 were identified to be the most critical vertebral levels with three malpositioned screws each. Because of the variability of cervical pedicles preoperative CT evaluation with multiplanar reconstructions of the pedicle anatomy is essential for transpedicular screw placement in the cervical spine. Cadaver studies remain mandatory to develop safer and technically less demanding procedures. A similar study is projected to further develop the technique of CPS fixation with regard to safety and clinical practicability. PMID:16628443

  9. Cervical pedicle screw placement: feasibility and accuracy of two new insertion techniques based on morphometric data

    PubMed Central

    Magerl, F.; Rieger, M.; Blauth, M.

    2006-01-01

    This morphometric and experimental study was designed to assess the dimensions and axes of the subaxial cervical pedicles and to compare the accuracy of two different techniques for subaxial cervical pedicle screw (CPS) placement using newly designed aiming devices. Transpedicular fixation is increasingly used for stabilizing the subaxial cervical spine. Development of the demanding technique is based on morphometric studies of the pedicle anatomy. Several surgical techniques have been developed and evaluated with respect to their feasibility and accuracy. The study was carried out on six conserved human cadavers (average age 85 years). Axes and dimensions of the pedicles C3–C7 (60 pedicles) were measured using multislice computed tomography (CT) images prior to surgery. Two groups consisting of 3 specimens and 30 pedicles each were established according to the screw placement technique. For surgical technique 1 (ST1) a para-articular mini-laminotomy was performed. Guidance of the drill through the pedicle with a handheld aiming device attached onto the medial aspect of the pedicle inside the spinal canal. Screw hole preparation monitored by lateral fluoroscopy. In surgical technique 2 (ST2) a more complex aiming device was used for screw holes drilling. It consists of a frame with a fully adjustable radiolucent arm for carrying the instruments necessary for placing the screws. The arm was angled according to the cervical pedicle axis as determined by the preoperative CT scans. Drilling was monitored by lateral fluoroscopy. In either technique 3.5 mm screws made of carbon fiber polyetheretherketone (CF-PEEK) were inserted. The use of the CF-PEEK screws allowed for precise postoperative CT-assessment since this material does not cause artifacts. Screw placement was qualified from ideal to unacceptable into four grades: I = screw centered in pedicle; IIa = perforation of pedicle wall less than one-fourth of the screw diameter; IIb = perforation more than one-fourth of the screw diameter without contact to neurovascular structures; III = screw more than one-fourth outside the pedicle with contact to neurovascular structures. Fifty-six pedicle screws could be evaluated according to the same CT protocol that was used preoperatively. Accuracy of pedicle screw placement did not reveal significant differences between techniques 1 and 2. A tendency towards less severe misplacements (grade III) was seen in ST2 (15% in ST2 vs. 23% in ST1) as well as a higher rate of screw positions graded IIa (62% in ST2 vs. 43% in ST1). C4 and C5 were identified to be the most critical vertebral levels with three malpositioned screws each. Because of the variability of cervical pedicles preoperative CT evaluation with multiplanar reconstructions of the pedicle anatomy is essential for transpedicular screw placement in the cervical spine. Cadaver studies remain mandatory to develop safer and technically less demanding procedures. A similar study is projected to further develop the technique of CPS fixation with regard to safety and clinical practicability. PMID:16628443

  10. Failure strengths of concentric and eccentric implants for hamstring graft fixation.

    PubMed

    Gwynne-Jones, David P; Draffin, Joanne; Vane, Andrew G S; Craig, Roy A; McMahon, Simon F

    2008-03-01

    The purpose of this study is to compare the initial failure strengths of various interference screw devices used for tibial fixation of hamstring grafts in anterior cruciate ligament reconstruction and the effect of concentric or eccentric screw position. Quadrupled tendon grafts were harvested from freshly killed sheep. The grafts were then prepared and fixed in the distal femur using various devices (Intrafix (DePuy Mitek Raynham, MA, USA), RCI screw (Smith and Nephew Acufex, Mansfield, MA, USA), Wedge screw (Stryker Endoscopy, San Jose, CA, USA) in concentric position and Wedge screw in eccentric position with an interlock pin). The load required to cause mechanical failure of each construct was measured. The Intrafix device had a significantly greater mean strength to failure than all the other implants (mean 941 +/- 280 N) (P = 0.015 to P < 0.0001). The wedge screw inserted concentrically (737 +/- 134 N) had significantly greater initial failure strength than the wedge eccentric with interlock pin (458 +/- 266 N) (P = 0.03) and the RCI screw (464 +/- 107 N) (P = 0.00036). In this sheep model the Intrafix device with sheath inserted concentrically had significantly greater initial failure strength than the other interference screws. Concentric positioning of the wedge interference screw gave significantly greater initial failure strength of a quadruple tendon graft than eccentric positioning. The use of the Intrafix device or concentric positioning of an interference screw should result in increased initial fixation strength of hamstring grafts. This may allow more vigorous early rehabilitation and may result in less late graft laxity after anterior cruciate ligament reconstruction. PMID:18269483

  11. 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

  12. The Endovascular Management of Iliac Artery Aneurysms

    SciTech Connect

    Stroumpouli, Evangelia [St George's Hospital, Department of Radiology (United Kingdom); Nassef, Ahmed; Loosemore, Tom; Thompson, Matt [St George's Hospital, Department of Vascular Surgery (United Kingdom); Morgan, Robert; Belli, Anna-Maria [St George's Hospital, Department of Radiology (United Kingdom)], E-mail: Anna.Belli@stgeorges.nhs.uk

    2007-11-15

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

  13. A biomechanical analysis of the self-retaining pedicle hook device in posterior spinal fixation.

    PubMed

    van Laar, Wilbert; Meester, Rinse J; Smit, Theo H; van Royen, Barend J

    2007-08-01

    Regular hooks lack initial fixation to the spine during spinal deformity surgery. This runs the risk of posterior hook dislodgement during manipulation and correction of the spinal deformity, that may lead to loss of correction, hook migration, and post-operative junctional kyphosis. To prevent hook dislodgement during surgery, a self-retaining pedicle hook device (SPHD) is available that is made up of two counter-positioned hooks forming a monoblock posterior claw device. The initial segmental posterior fixation strength of a SPHD, however, is unknown. A biomechanical pull-out study of posterior segmental spinal fixation in a cadaver vertebral model was designed to investigate the axial pull-out strength for a SPHD, and compared to the pull-out strength of a pedicle screw. Ten porcine lumbar vertebral bodies were instrumented in pairs with two different instrumentation constructs after measuring the bone mineral density of each individual vertebra. The instrumentation constructs were extracted employing a material testing system using axial forces. The maximum pull-out forces were recorded at the time of the construct failure. Failure of the SPHD appeared in rotation and lateral displacement, without fracturing of the posterior structures. The average pull-out strength of the SPHD was 236 N versus 1,047 N in the pedicle screws (P < 0.001). The pull-out strength of the pedicle screws showed greater correlation with the BMC compared to the SPHD (P < 0.005). The SPHD showed to provide a significant inferior segmental fixation to the posterior spine in comparison to pedicle screw fixation. Despite the beneficial characteristics of the monoblock claw construct in a SPHD, that decreases the risk of posterior hook dislodgement during surgery compared to regular hooks, the SPHD does not improve the pull-out strength in such a way that it may provide a biomechanically solid alternative to pedicle screw fixation in the posterior spine. PMID:17203270

  14. Occipital condyle to cervical spine fixation in the pediatric population.

    PubMed

    Kosnik-Infinger, Libby; Glazier, Steven S; Frankel, Bruce M

    2014-01-01

    Fixation at the craniovertebral junction (CVJ) is necessary in a variety of pediatric clinical scenarios. Traditionally an occipital bone to cervical fusion is preformed, which requires a large amount of hardware to be placed on the occiput of a child. If a patient has previously undergone a posterior fossa decompression or requires a decompression at the time of the fusion procedure, it can be difficult to anchor a plate to the occipital bone. The authors propose a technique that can be used when faced with this difficult challenge by using the occipital condyle as a point of fixation for the construct. Adult cadaveric and a limited number of case studies have been published using occipital condyle (C-0) fixation. This work was adapted for the pediatric population. Between 2009 and 2012, 4 children underwent occipital condyle to axial or subaxial spine fixation. One patient had previously undergone posterior fossa surgery for tumor resection, and 1 required decompression at the time of operation. Two patients underwent preoperative deformity reduction using traction. One child had a Chiari malformation Type I. Each procedure was performed using polyaxial screw-rod constructs with intraoperative neuronavigation supplemented by a custom navigational drill guide. Smooth-shanked 3.5-mm polyaxial screws, ranging in length from 26 to 32 mm, were placed into the occipital condyles. All patients successfully underwent occipital condyle to cervical spine fixation. In 3 patients the construct extended from C-0 to C-2, and in 1 from C-0 to T-2. Patients with preoperative halo stabilization were placed in a cervical collar postoperatively. There were no new postoperative neurological deficits or vascular injuries. Each patient underwent postoperative CT, demonstrating excellent screw placement and evidence of solid fusion. Occipital condyle fixation is an effective option in pediatric patients requiring occipitocervical fusion for treatment of deformity and/or instability at the CVJ. The use of intraoperative neuronavigation allows for safe placement of screws into C-0, especially when faced with a challenging patient in whom fixation to the occipital bone is not possible or is less than ideal. PMID:24206344

  15. An Articulating Tool for Endoscopic Screw Delivery

    E-print Network

    Petrzelka, Joseph Edward

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

  16. Safety of coil embolization of the internal iliac artery in endovascular grafting of abdominal aortic aneurysms

    Microsoft Academic Search

    Frank J. Criado; Eric P. Wilson; Omaida C. Velazquez; Jeffrey P. Carpenter; Clyde Barker; Eric Wellons; Omran Abul-Khoudoud; Ronald M. Fairman

    2000-01-01

    Purpose: During endovascular grafting of an abdominal aortic aneurysm (AAA), iliac limb extension to the external iliac artery may be indicated when the common iliac artery is ectatic or aneurysmal. Preliminary or concomitant coil embolization of the internal iliac artery (IIA) is thus necessary to prevent potential reflux and endoleak. We sought to determine the safety of hypogastric flow interruption

  17. Screw placement in slipped upper femoral epiphysis: is good the enemy of better?

    PubMed Central

    Allami, Mohamad K.; Varghese, Bobin; Almaiyah, Mohammed; Giannoudis, Peter

    2007-01-01

    Introduction and aims A single hip screw is the recommended method of fixation for slipped upper femoral epiphysis (SUFE). Current practice favours the placement of the screw in the centre of the femoral head on both anteroposterior and lateral planes to avoid the risks of chondrolysis and avascular necrosis (AVN). We investigated the correlation between different positions of the screw in the femoral head and the prevalence of AVN, chondrolysis, late slippage and the time to epiphyseal closure. Methods The clinical notes and radiographs of 38 consecutive patients (61 hips) who underwent single screw fixation for SUFE were evaluated retrospectively with a mean follow-up of 36 months. Two-way ANOVA and the post hoc test was performed to analyse the correlation between the different variables and the outcome at the 5% level of significance. Results There were 16 acute slips, 18 chronic slips and ten acute-on-chronic slips. Seventeen slips were treated prophylactically. Mild slip was encountered in 39 hips, moderate slip in four and severe slip in one. The central–central position was only achieved in 51% of cases. The most significant results of the study were as follows: (1) no significant difference between the time to epiphyseal closure and the position of the screw, and (2) no late slippage or chondrolysis was observed in our series. Conclusion Our results showed that the positioning of the screw other than in the centre of the femoral head has the ability to provide physeal stability and has no correlation with the timing to closure of the epiphysis and the risk of avascular necrosis or chondrolysis. We therefore recommend that other positions be considered if the “optimal central–central position” is not initially achieved – specifically for the treatment of mild slip – as the potential hazards from several attempts to achieve the optimum position outweigh the benefits. PMID:19308493

  18. Iliac arterial-enteric fistulas occurring after pelvic irradiation

    SciTech Connect

    Vetto, J.T.; Culp, S.C.; Smythe, T.B.; Chang, A.E.; Sindelar, W.F.; Sugarbaker, P.H.; Heit, H.A.; Giordano, J.M.; Kozloff, L.

    1987-05-01

    Fistulas from the iliac artery to the bowel constitute a condition that is often lethal. Excluding fistulas related to vascular grafts, a review of previously reported cases shows that they are most often due to atherosclerotic iliac aneurysms. Three unusual cases of this condition that occurred after high-dose pelvic irradiation for treatment of cancer are presented; in no case was recurrent tumor evident. These cases suggest that high-dose pelvic irradiation can predispose to the formation of iliac arterial-enteric fistulas, particularly if sepsis or inflammation develops. The definitive surgical management of these fistulas entails bowel resection, arterial ligation, and extra-anatomic bypass.

  19. Endovascular treatment of iliac vein compression syndrome (May-Thurner).

    PubMed

    Budnur, Srinivas Chikkaswamy; Singh, Bhupinder; Mahadevappa, Nagesh Chamarajnagar; Reddy, Babu; Nanjappa, Manjunath C

    2013-01-01

    May-Thurner syndrome is a rare condition that results from narrowing of the left common iliac vein (CIV) lumen due to pulsatile compression from the right common iliac artery (CIA) as it crosses anterior to it. We present a case of 24-years old female with left lower limb deep venous thrombosis (DVT). Duplex ultrasonography revealed extensive left-sided DVT. Magnetic resonance venogram suggested DVT with left CIV being compressed by right CIA. Pharmaco-mechanical catheter directed thrombolysis-thrombectomy followed by left iliac vein stent placement restored patency to the venous system, with resolution of symptoms. PMID:22829161

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

    SciTech Connect

    Ruebben, Alexander; Tettoni, Serena; Muratore, Pierluigi; Rossato, Dennis; Savio, Daniele; Rabbia, Claudio [Radiologia del Pronto Soccorso, Servizio di Angioradiologia, Azienda Ospedaliera San Giovanni Battista, Corso Bramante 88, I-10126 Turin (Italy)

    1998-07-15

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

  1. Outcome After Open Reduction and Internal Fixation of Lisfranc Joint Injuries

    Microsoft Academic Search

    R. S. KUO; N. C. TEJWANI; C. W. DIGIOVANNI; S. K. HOLT; S. K. BENIRSCHKE; S. T. HANSEN; B. J. SANGEORZAN

    2000-01-01

    Background: Open reduction and internal fixation has been recommended as the treatment for most un- stable injuries of the Lisfranc (tarsometatarsal) joint. It has been thought that purely ligamentous injuries have a poor outcome despite such surgical management. Methods: We performed a retrospective study of patients who underwent open reduction and screw fixa- tion of a Lisfranc injury in a

  2. Ionising radiation during internal fixation of extracepsular neck of femur fractures

    Microsoft Academic Search

    P. V. Giannoudis; J. McGuigan; D. L. Shaw

    1998-01-01

    This study analyses the relationship between the level of experience of both surgeon and radiographer and the radiation dose administered in theatre, during fixation of extracapsular proximal femoral fractures. From the 63 dynamic hip screw procedures performed, 10 were done by Senior House Officers (SHOs), 10 by Consultants and 43 by Registrars, whereas Basic Radiographers were involved in all cases.

  3. Early outcomes of proximal humerus fracture fixation with locking plate and intramedullary fibular strut graft.

    PubMed

    Tan, Edwin; Lie, Denny; Wong, M K

    2014-09-01

    Proximal humerus fractures are commonly encountered in elderly patients. Surgical treatment demonstrates high complication rates, including varus construct collapse and screw cutout. In this study, the authors evaluate the clinical outcome of locking plate fixation with intramedullary fibular strut graft augmentation as a primary surgical treatment in the prevention of early collapse and screw cutout. A total of 9 patients were evaluated. Surgery was performed for displaced proximal humerus fractures between April and December 2011. Patients were either class 2, 3, or 4, according to Neer classification. Mean patient age was 75.4 years. Preoperative and immediate, 6-week, and 3-month postoperative radiographs were evaluated. Head-shaft angles were measured to assess for varus collapse and displacement. Range of motion, complication rates, and functional recovery were also evaluated. Patients underwent open reduction and internal fixation with placement of an intramedullary fibular strut graft. Fixation was achieved with a Philos plate (Synthes, Oberdorf, Switzerland). Reduction and fixation were evaluated with radiographs. Passive exercises and range of motion were allowed immediately postoperatively, and all patients achieved active abduction and forward flexion 6 weeks postoperatively. Shoulder radiographs taken 12 weeks postoperatively revealed no loss of reduction or screw cutout. The introduction of the locking plate has improved outcomes. The addition of an intramedullary strut graft has shown improved preliminary results. Maintained reduction was observed in all 9 patients in the early postoperative period, and good functional motion was achieved. No incidence of screw cutout was recorded. PMID:25350626

  4. The single screw extrusion of pastes

    Microsoft Academic Search

    A. S. Burbidge; J. Bridgwater

    1995-01-01

    Screw extrusion is widely used but little is known about the design and operation of this type of equipment save in the polymer industry. Particularly with the advent of high-performance, high-value ceramic materials, it has become important to extend knowledge. Here a mathematical model for a flooded screw brings together recent paste rheology and a model of screw extrusion developed

  5. Rotary screw compressors in the gas patch

    Microsoft Academic Search

    Jandjel

    1996-01-01

    In 1959, Howden introduced the oil-injected rotary screw (OIS) compressor, which has, since then, methodically replaced the reciprocating (piston) compressor in applications such as air, refrigeration and fuel gas. Rotary screw compressors have been making inroads in gas recovery, a field once dominated by reciprocating compressors. Rotary screws do not require extensive maintenance, thus downtime is minimized throughout an operating

  6. Evaluation of anatomic landmarks and safe zones for screw placement in the atlas via the posterior arch

    PubMed Central

    Barvencik, Florian; Briem, Daniel; Kolb, Jan P.; Seitz, Sebastian; Rueger, Johannes M.; Püschel, Klaus; Amling, Michael

    2009-01-01

    Several studies have evaluated quantitative anatomic data for direct lateral mass screw fixation. To analyze anatomic landmarks and safe zones for optimal screw placement through the posterior arc of the human atlas, morphometric parameters of 41 adult native human atlas specimens were quantitatively measured. Internal dimensions of the atlas (lateral mass, maximum and minimum intraosseous screw length), minimum height and width of the posterior arc and optimal screw insertion angles were defined on pQCT scans. By this, an optimal posterior screw insertion point (OIP) and a preferable screw direction (PSD) through the posterior arch into the lateral mass of C1 were defined. External dimensions (transverse and sagittal diameter) as well as the width of the mid-portion of C1 lateral mass were significantly higher in male specimens. The mean height of the posterior arch at the vertebral artery groove was 4.1 ± 0.8 mm in female and 4.6 ± 0.9 mm in male specimens. The optimal screw insertion point was located 21.6 ± 1.7 mm in female and 23.6 ± 2.3 mm in male lateral from the posterior tubercle of C1 (P < 0.01). The preferable screw direction was a mean medial inclination of 7.9 ± 1.9° in female and 7.3 ± 2.7° in male specimens and a mean rostral direction of 2.4 ± 1.8° in female and 3.1 ± 1.7° in male specimens. In conclusion, the presented study provides information for the use and design of upper cervical spine instrumentation techniques, such as screw placement to C1 via the posterior arch. The characterization of working areas and safe zones (OIP, PSD) might contribute to a minimization of screw malposition in this highly demanding instrumentation technique. PMID:19882180

  7. In vitro and in vivo evaluations of nano-hydroxyapatite/polyamide 66/glass fibre (n-HA/PA66/GF) as a novel bioactive bone screw.

    PubMed

    Su, Bao; Peng, Xiaohua; Jiang, Dianming; Wu, Jun; Qiao, Bo; Li, Weichao; Qi, Xiaotong

    2013-01-01

    In this study, we prepared nano-hydroxyapatite/polyamide 66/glass fibre (n-HA/PA66/GF) bioactive bone screws. The microstructure, morphology and coating of the screws were characterised, and the adhesion, proliferation and viability of MC3T3-E1 cells on n-HA/PA66/GF scaffolds were determined using scanning electron microscope, CCK-8 assays and cellular immunofluorescence analysis. The results confirmed that n-HA/PA66/GF scaffolds were biocompatible and had no negative effect on MC3T3-E1 cells in vitro. To investigate the in vivo biocompatibility, internal fixation properties and osteogenesis of the bioactive screws, both n-HA/PA66/GF screws and metallic screws were used to repair intercondylar femur fractures in dogs. General photography, CT examination, micro-CT examination, histological staining and biomechanical assays were performed at 4, 8, 12 and 24 weeks after operation. The n-HA/PA66/GF screws exhibited good biocompatibility, high mechanical strength and extensive osteogenesis in the host bone. Moreover, 24 weeks after implantation, the maximum push-out load of the bioactive screws was greater than that of the metallic screws. As shown by their good cytocompatibility, excellent biomechanical strength and fast formation and ingrowth of new bone, n-HA/PA66/GF screws are thus suitable for orthopaedic clinical applications. PMID:23861888

  8. All Screwed Up : A Memoir

    Microsoft Academic Search

    Steven Fellner

    2009-01-01

    Murder attempts... missing umbilical cords... haunted quarries... fat camps... These darkly comic stories fill the pages of All Screwed Up. Young, gay, and poor, Steve Fellner attempts to shed his trailer park past and seize a better life for himself. But coming from the sticks offers a certain kind of freedom: no one expects anything from you, so you can

  9. Percutaneous Ablation of an Internal Iliac Aneurysm Using Tissue Adhesive

    Microsoft Academic Search

    Richard J. T. Owen; Ralph Jackson; Henry W. Loose; Timothy A. Lees; Paul Dunlop; John D. G. Rose

    2000-01-01

    We report the percutaneous injection of tissue adhesive (Tisseal, Immuno, Vienna, Austria) to ablate a 12-cm internal iliac\\u000a aneurysm. The complex history of this lesion included previous surgery for a ruptured aortic aneurysm, attempted repair of\\u000a the internal iliac aneurysm, and several embolization procedures. These factors precluded further open repair or transcatheter\\u000a techniques and dictated the choice of a more

  10. Iliac vein compression in an asymptomatic patient population

    Microsoft Academic Search

    Melina R Kibbe; Michael Ujiki; A. Lee Goodwin; Mark Eskandari; James Yao; Jon Matsumura

    2004-01-01

    ObjectiveMay-Thurner syndrome is a well-recognized anatomic variant that is associated with the development of symptomatic acute venous thrombosis of the left iliac vein. However, the natural frequency of compression of the left iliac vein and its clinical significance in asymptomatic disease has not been established. Therefore the purpose of this descriptive anatomic study was to determine the incidence of left

  11. Gender Does Not Influence Outcomes after Iliac Angioplasty

    Microsoft Academic Search

    Justin D. Orr; Nicholas J. Leeper; Brian Funaki; Jeffrey Leef; Bruce L. Gewertz; Tina R. Desai

    2002-01-01

      The current study was undertaken to evaluate the potential influence of gender on iliac angioplasty outcomes. All iliac angioplasty\\u000a procedures performed at a tertiary care center from 1994 to 1999 were reviewed. One hundred four angioplasties with or without\\u000a stenting were performed in 44 women (56 limbs) and 40 men (48 limbs). Age and atherosclerotic risk factors were similar in

  12. Nonunion after trapeziometacarpal arthrodesis: comparison between K-wire and internal fixation.

    PubMed

    Singh, H P; Hoare, C; Beresford-Cleary, N; Anakwe, R; Hayton, M

    2015-05-01

    We reviewed 63 trapeziometacarpal arthrodeses (57 patients) performed in our unit between April 2007 and May 2013 for osteoarthritis. K-wires, plates, headless compression screws and memory staples were used for fixation. The average age of patients was 50 (range 20-78) years and there were 36 men and 21 women with a mean follow-up of 36 (range 6-62) months. K-wires were used in 31 cases, staples in 12, plates in five, and screws in 15 joints. The overall non-union rate was 11%, however, when using K-wires for fixation, it was 20%. Union was achieved in all cases when staples or screws were used for fixation. Disabilities of the Arm, Shoulder and Hand scores were higher in cases where non-union occurred compared with those that united (66.7 vs. 21.9). Trapeziometacarpal arthrodesis for osteoarthritis gives good clinical outcome with lower (DASH) scores when union occurs. K-wire fixation led to a 20% non-union rate, and as a result, the senior author no longer uses this method of fixation. PMID:24916633

  13. Metallurgical examination of gun barrel screws

    SciTech Connect

    Bird, E.L.; Clift, T.L.

    1996-06-01

    The examination was conducted to determine the extent of degradation that had occurred after a series of firings; these screws prevent live rounds of ammunition from being loaded into the firing chamber. One concern is that if the screw tip fails and a live round is accidentally loaded into the chamber, a live round could be fired. Another concern is that if the blunt end of the screw begins to degrade by cracking, pieces could become small projectiles during firing. All screws used in firing 100 rounds or more exhibited some degree degradation, which progressively worsened as the number of rounds fired increased. (SEM, metallography, x-ray analysis, and microhardness were used.) Presence of cracks in these screws after 100 fired rounds is a serious concern that warrants the discontinued use of these screws. The screw could be improved by selecting an alloy more resistant to thermal and chemical degradation.

  14. Recurrent Laryngeal Edema Imitating Angioedema Caused by Dislocated Screw after Anterior Spine Surgery

    PubMed Central

    Wójtowicz, Piotr; Szafarowski, Tomasz; Migacz, Ewa; Krzeski, Antoni

    2015-01-01

    The anterior cervical spine surgery is a common procedure to stabilize vertebrae damaged by various diseases. The plates and screws are usually used in the spine fixation. This kind of instrumentation may detach from the bones which is a rare but well-known complication. A 77-year-old male presented to the otorhinolaryngology department with throat pain, choking, and dysphagia. At first the angioedema was diagnosed and he was treated conservatively. The endoscopy revealed laryngeal edema, being more defined on the right side with right vocal fold paresis. CT scans showed the stabilizing plate with two screws attached tightly and the back-out of the third screw toward soft tissue of the neck. In the meantime, his condition deteriorated and he needed tracheotomy. In few days the surgical removal of the dislocated screw was performed successfully. Although two-month follow-up reported no obstruction of the larynx, the vocal folds paresis with gradual functional improvement was observed. Long-term complication of anterior spine surgery sometimes may suggest laryngeal angioedema at first. If the conservative treatment is ineffective and there is a history of anterior spine surgery, the clinicians should consider the displacement of the plate or screws in differential diagnosis. PMID:25755901

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

    PubMed Central

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

    2014-01-01

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

  16. External-to-Internal Iliac Stent-Graft: Medium-Term Patency Following Exclusion of a Retrogradely Perfused Common Iliac Aneurysm

    SciTech Connect

    Nicholls, Marcus John, E-mail: marcusnicholls@hotmail.co [York Hospitals NHS Foundation Trust, Department of Radiology (United Kingdom); McPherson, Simon [Leeds Teaching Hospitals NHS Trust (United Kingdom)

    2010-08-15

    Following complicated aortic aneurysm surgery a complete left iliac occlusion resulted in buttock claudication. A retrogradely perfused right common iliac aneurysm expanded. Exclusion was by external-to-internal iliac stent-graft. No deterioration in claudication occurred with medium-term stent-graft patency.

  17. A new adhesive technique for internal fixation in midfacial surgery

    PubMed Central

    Endres, Kira; Marx, Rudolf; Tinschert, Joachim; Wirtz, Dieter Christian; Stoll, Christian; Riediger, Dieter; Smeets, Ralf

    2008-01-01

    Background The current surgical therapy of midfacial fractures involves internal fixation in which bone fragments are fixed in their anatomical positions with osteosynthesis plates and corresponding screws until bone healing is complete. This often causes new fractures to fragile bones while drilling pilot holes or trying to insert screws. The adhesive fixation of osteosynthesis plates using PMMA bone cement could offer a viable alternative for fixing the plates without screws. In order to achieve the adhesive bonding of bone cement to cortical bone in the viscerocranium, an amphiphilic bone bonding agent was created, analogous to the dentin bonding agents currently on the market. Methods The adhesive bonding strengths were measured using tension tests. For this, metal plates with 2.0 mm diameter screw holes were cemented with PMMA bone cement to cortical bovine bone samples from the femur diaphysis. The bone was conditioned with an amphiphilic bone bonding agent prior to cementing. The samples were stored for 1 to 42 days at 37 degrees C, either moist or completely submerged in an isotonic NaCl-solution, and then subjected to the tension tests. Results Without the bone bonding agent, the bonding strength was close to zero (0.2 MPa). Primary stability with bone bonding agent is considered to be at ca. 8 MPa. Moist storage over 42 days resulted in decreased adhesion forces of ca. 6 MPa. Wet storage resulted in relatively constant bonding strengths of ca. 8 MPa. Conclusion A new amphiphilic bone bonding agent was developed, which builds an optimizied interlayer between the hydrophilic bone surface and the hydrophobic PMMA bone cement and thus leads to adhesive bonding between them. Our in vitro investigations demonstrated the adhesive bonding of PMMA bone cement to cortical bone, which was also stable against hydrolysis. The newly developed adhesive fixing technique could be applied clinically when the fixation of osteosynthesis plates with screws is impossible. With the detected adhesion forces of ca. 6 to 8 MPa, it is assumed that the adhesive fixation system is able to secure bone fragments from the non-load bearing midfacial regions in their orthotopic positions until fracture consolidation is complete. PMID:18489785

  18. Predicting preference from fixations

    Microsoft Academic Search

    Mackenzie G. Glaholt; Mei-chun Wu; Eyal M. Reingold

    2009-01-01

    We measured the strength of the association between looking behaviour and preference. Participants selected the most preferred face out of a grid of 8 faces. Fixation times were correlated with selection on a trial-by-trial basis, as well as with explicit preference ratings. Furthermore, by ranking features based on fixation times, we were able to successfully predict participants' preferences for novel

  19. Fixation: A Bibliography.

    ERIC Educational Resources Information Center

    Pedrini, D. T.; Pedrini, Bonnie C.

    Fixation and regression were considered complementary by Freud. You tend to regress to a point of fixation. They are both opposed to progression. In the general area, Anna Freud has written (The Ego and the Mechanisms of Defence. London: Hogarth and the Psycho-Analytic Institute, 1937), Sears has evaluated (Survey of Objective Studies of…

  20. 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.

  1. The lateral sacral triangle--a decision support for secure transverse sacroiliac screw insertion.

    PubMed

    Mendel, T; Noser, H; Wohlrab, D; Stock, K; Radetzki, F

    2011-10-01

    Sacroiliac (SI) screw fixation represents an effective method to stabilise pelvic injuries. However, to date neither reliable radiological landmarks nor effective anatomical classifications of the sacrum exist. This study investigates the influence of variability in sacral shape on secure transverse SI-screw positioning. Furthermore, consistent correlations of these anatomical conditions are analysed with respect to standard planar pelvic views. For shape analysis, 80 human computed tomography data sets were segmented with the software Amira 4.2 to obtain 3D reconstructions. We identified anatomical conditions (ACs) according to the extent of the effect on the bony screw pathway. Subsequently, the pelvis was spatially aligned using representative bone protuberances in order to create standard Matta projections. In each view, the ACs were described in terms of distance from bone landmarks. Three-dimensional shape analysis revealed the height of the pedicular isthmus (PH) as the limiting variable for secure screw insertion. The lateral and outlet views allowed an orthogonal projection of PH. In the lateral view, the ratio of the lateral sacral triangle framed by the S1 body height and width showed a high correlation to PH (p = 0.0001). A boundary ratio of 1.5 represented a reliable variable to determine whether or not a screw can be inserted (positive predictive value: 97%). In the outlet view, the distance between the S1 endplate and the SI joint top level (EJ) strongly correlated with PH (p = 0.0001). With EJ 0 mm, screw insertion was possible in all cases (100%). SI-screw insertion requires a well-planned procedure. Orientation of the sacral pedicle is of extreme relevance. A narrow sacroiliac channel and high sacral shape variability limit secure screw placement. However, no determining parameters exist, allowing accurate prediction of secure screw insertion based on X-rays or fluoroscopy. The lateral sacral triangle in the lateral view represents a simple and accurate preoperative method of support for the surgeon's decision to undertake this procedure. No additional technical effort is necessary. A boundary ratio of 1.5 predicts a sufficient bone stock for at least one 7.3 mm screw. Furthermore, the evaluation of the outlet projection can be used to assess the safety of the operation. Basically, a preoperative lateral pelvic image should be mandatory. PMID:22081808

  2. C2 Anatomy for Translaminar Screw Placement Based on Computerized Tomographic Measurements

    PubMed Central

    Phankhongsab, Anuchit

    2015-01-01

    Study Design Anatomical study. Purpose To evaluate the anatomy of the C2 lamina for translaminar screw placement based on computerized tomographic measurements. Overview of Literature C2 translaminar screw insertion is a novel technique for atlanto-axial fixation. The risk of vertebral artery injury can be decreased by this technique. However, a large series of anatomical studies on C2 anatomy in Asian populations is still lacking. Methods Two hundred adult C2 vertebrae were evaluated by computerized tomographic imaging. The measured parameters included inner and outer transverse diameters of C2 lamina, C2 laminar length and spino-laminar angle. C2 vertebrae with lamina screw placement feasibility were defined as those with inner transverse diameter larger than 3.5 mm. Results The mean inner transverse diameter of the C2 lamina was 4.23±1.22 mm. It was significantly larger in males than in females (4.44±1.29 mm vs. 3.96±1.06 mm, p=0.005). The mean outer transverse diameter of C2 lamina was 6.64±1.36 mm. The mean C2 laminar length was 37.26±4.42 mm. The mean C2 spino-laminar angle was 56.42±6.42 degrees. Seventy-nine percents of patients had inner transverse diameter larger than 3.5 mm. Conclusions C2 translaminar screw fixation was feasible in the majority of the adult population. However, there were some people who had small C2 lamina. We recommend preoperative computed tomography evaluation to confirm the feasibility of screw placement.

  3. Causes and managements of postoperative complications after degenerative scoliosis treatments with internal fixation

    PubMed Central

    Yang, Yong-Hong; Zheng, Jie; Lou, Shu-Liang

    2014-01-01

    Objective: To investigate the causes and managements of early postoperative complications of degenerative scoliosis (DS) treated with internal pedicle screw fixation. Methods: From Jan 2000 to Apr 2013, 325 DS patients treated with internal pedicle screw fixation in our hospital were retrospectively involved. The categories, causes, managements and outcomes of early postoperative complications were statistically analyzed. Results: Early postoperative complications occurred in 10.76% of the patients including 16 cases of lower limb numb or pain, 6 cases of decreased lower limb sensitivity and motor functions, which accounted for 62.86% of all complications, followed by incision infections (4/35, 11.43%) and rare cases of cerebrospinal fluid leakage, cardiac and renal inadequacy, urinary system and pulmonary infections. The incidence of overall complications (19.79%, p = 0.001) and nerve injuries (11.46%, p = 0.000) were significantly higher in long-segment than in short-segment fixations. Improper screw implanting, over correction of scoliosis and insufficient blood supply of the spinal cord during operation were risk factors for early postoperative complications and most of them were cured by anti-infection medication, incision dressing change, nerve nourishment, adjusting the screws and anti-osteoporosis treatments within 6 months after surgery. Only three cases with severe nerve injury did not improve until the 6 months postoperative follow-up. Conclusions: Most of the postoperative complications in our DS patients disappeared within 6 months after surgery and more than half of complications were nerve injuries. PMID:25550945

  4. Periodic variation of preloading in ball screws

    Microsoft Academic Search

    S. Frey; M. Walther; A. Verl

    2010-01-01

    The preloading is a main characteristic for the functionality of a ball screw. The path of preloading during operation with\\u000a no thrust load is an indicator for the actual inner forces, the friction produced by the ball screw and finally for the quality\\u000a of the unit. Due to manufacturing tolerances the preloading over the useful travel of the ball screw

  5. High energy tibial plateau fractures treated with hybrid external fixation

    PubMed Central

    2011-01-01

    Management of high energy intra-articular fractures of the proximal tibia, associated with marked soft-tissue trauma, can be challenging, requiring the combination of accurate reduction and minimal invasive techniques. The purpose of this study was to evaluate whether minimal intervention and hybrid external fixation of such fractures using the Orthofix system provide an acceptable treatment outcome with less complications. Between 2002 and 2006, 33 patients with a median ISS of 14.3 were admitted to our hospital, a level I trauma centre, with a bicondylar tibial plateau fracture. Five of them sustained an open fracture. All patients were treated with a hybrid external fixator. In 19 of them, minimal open reduction and stabilization, by means of cannulated screws, was performed. Mean follow-up was 27 months (range 24 to 36 months). Radiographic evidence of union was observed at 3.4 months (range 3 to 7 months). Time for union was different in patients with closed and grade I open fractures compared to patients with grade II and III open fractures. One non-union (septic) was observed (3.0%), requiring revision surgery. Pin track infection was observed in 3 patients (9.1%). Compared to previously reported series of conventional open reduction and internal fixation, hybrid external fixation with or without open reduction and minimal internal fixation with the Orthofix system, was associated with satisfactory clinical and radiographic results and limited complications. PMID:21756337

  6. Shock-Absorbent Ball-Screw Mechanism

    NASA Technical Reports Server (NTRS)

    Hirr, Otto A., Jr.; Meneely, R. W.

    1986-01-01

    Actuator containing two ball screws in series employs Belleville springs to reduce impact loads, thereby increasing life expectancy. New application of springs increases reliability of equipment in which ball screws commonly used. Set of three springs within lower screw of ball-screw mechanism absorbs impacts that result when parts reach their upper and lower limits of movement. Mechanism designed with Belleville springs as shock-absorbing elements because springs have good energy-to-volume ratio and easily stacked to attain any stiffness and travel.

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

    PubMed

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

    2015-03-01

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

  8. Scaphoid excision and 4-corner fusion using retrograde headless compression screws.

    PubMed

    Ball, Brandon; Bergman, Joseph W

    2012-12-01

    Scapholunate advanced collapse is a predictable form of wrist arthritis resulting from longstanding scapholunate instability. Four-corner fusion and scaphoid excision is a reliable procedure used to treat scapholunate advanced collapse wrist that improves pain and preserves range of motion. Multiple methods of achieving fixation have been described for the procedure including K-wires, staples, and headless compression screws. In previously described techniques, the compression screws are inserted in an antegrade manner, breaching the articular surface of the lunate. Even small areas of chondral damage may undermine the long-term durability of the radiocarpal joint. Given the 4-corner fusion relies on the integrity of the radiolunate articulation for success, it would seem advantageous to preserve the articular cartilage of the lunate. The technique described here involves retrograde insertion of headless compression screws to achieve a 4-corner fusion. Although it is still early, we anticipate that this procedure will result in similar fusion rates to other forms of fixation. PMID:23160552

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

    PubMed

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

    2015-04-01

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

  10. Efficacy of Iliac Crest vs. Medpor in Orbital Floor Reconstruction

    Microsoft Academic Search

    Hari Ram; R. K. Singh; Shadab Mohammad; Anup Kumar Gupta

    2010-01-01

    Aim  The present study is to compare the effectiveness of iliac crest graft and medpor implant, for repairing traumatic orbital\\u000a floor defects.\\u000a \\u000a \\u000a \\u000a \\u000a Materials and methods  A total of 20 patients were included in the study. Autogenous iliac crest graft and medpor implant was used in 10 patients\\u000a of the each group. Patients were evaluated for the presence or absence of diplopia, enophthalmos,

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

    Microsoft Academic Search

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

    2004-01-01

    This biomechanical study compares the initial fixation strength of a novel bioabsorbable two-shell expansion bolt (EB) with that of a well-established interference-screw technique in bone–patellar tendon–bone (BPTB) reconstruction in a calf model. Thirty tibia plateaus (age 5–6 months) were assigned to three groups: In groups I and II, trapezoidal bone plugs of BPTB grafts were fixed with bioabsorbable poly-L-lactide interference

  12. Comparison of five different fixation techniques of sagittal split ramus osteotomy using three-dimensional finite elements analysis.

    PubMed

    Sato, F R L; Asprino, L; Noritomi, P Y; da Silva, J V L; de Moraes, M

    2012-08-01

    The aim of this study was to compare the mechanical stress over hemimandible substrate and hardware after sagittal split ramus osteotomy (SSRO) fixed with five different techniques using three-dimensional (3D) finite element analysis. A 3D finite element model of a hemimandible was created and a 5mm advancement SSRO was simulated on a computer model. The model was fixed with five different techniques: 3 linear 60° screw arrangement; 3 linear 90° screw arrangement; 3 inverted L screw arrangement; 1 conventional miniplate; and 1 locking miniplate with four monocortical screws. Load was applied until 3mm displacement was reached and the results were compared with previous mechanical and photoelastic tests, thus analysing the mechanical stresses developed in the proximity of miniplates and screws and within the fixation system itself. The maximum principal stress values demonstrate a lower mechanical stress rate in bone and in the fixation system with the inverted L arrangement, followed by the linear 90° and linear 60° arrangements. The locking miniplate/screw system presented lower maximum principal stress and better stress distribution compared with the conventional system. Under the conditions tested, the reversed L arrangement provided the most favourable stress dissipation behaviour. PMID:22510341

  13. Adverse consequences of internal iliac artery occlusion during endovascular repair of abdominal aortic aneurysms

    Microsoft Academic Search

    Laura A. Karch; Kim J. Hodgson; Mark A. Mattos; William T. Bohannon; Don E. Ramsey; Robert B. McLafferty

    2000-01-01

    Objective: Embolization of the internal iliac artery (IIA) may be performed during endovascular abdominal aortic aneurysm (AAA) repair if aneurysmal disease of the common iliac artery precludes graft placement proximal to the IIA orifice. The IIA may also be unintentionally occluded because of iliac trauma or coverage by the endograft. The purpose of this study was to determine the incidence,

  14. Noise Level of Precision Ball Screws

    Microsoft Academic Search

    Toshiharu Kajita; Akihiko Ishikawa

    1996-01-01

    We have derived a formula to evaluate the noise level of NSK precision ball screws based on data accumulated for over 10 years. Our database indicates that the factor which plays an important role in ball screw noise is the product of three parameters: ball diameter, ball pitch circle diameter, and rotational speed. The derived formula enables us to estimate

  15. Ball screw type wave power generator

    Microsoft Academic Search

    K.-I. Ohmata; H. Shimoda

    1979-01-01

    To obtain an even flow of electric power form fluctuating wave energy, the authors devised a ball screw type wave power generator (BSTWPG) which consists of a pressure plate, ball screws and nuts, one-way clutches, flywheels and generators. The equations of motion of the BSTWPG system are shown and the digital simulation using Continuous System Simulation Language is developed on

  16. In vitro study of accuracy of cervical pedicle screw insertion using an electronic conductivity device (ATPS part III)

    Microsoft Academic Search

    Heiko Koller; Wolfgang Hitzl; Frank Acosta; Mark Tauber; Juliane Zenner; Herbert Resch; Yasutsugu Yukawa; Oliver Meier; Rene Schmidt; Michael Mayer

    2009-01-01

    Reconstruction of the highly unstable, anteriorly decompressed cervical spine poses biomechanical challenges to current stabilization\\u000a strategies, including circumferential instrumented fusion, to prevent failure. To avoid secondary posterior surgery, particularly\\u000a in the elderly population, while increasing primary construct rigidity of anterior-only reconstructions, the authors introduced\\u000a the concept of anterior transpedicular screw (ATPS) fixation and plating. We demonstrated its morphological feasibility, its

  17. Dynamic Hip Screw for the Treatment of Femoral Neck Fractures: A Prospective Study with 96 Patients

    PubMed Central

    Schwartsmann, Carlos Roberto; Jacobus, Lucas Senger; Spinelli, Leandro de Freitas; Boschin, Leonardo Carbonera; Gonçalves, Ramiro Zilles; Yépez, Anthony Kerbes; Barreto, Rodrigo Py Gonçalves; Silva, Marcelo Faria

    2014-01-01

    Objectives. To study the correlation between avascular necrosis and the demographics, time elapsed from fracture to surgery, quality of reduction, Garden classification, and the position of the screw following use of the dynamic hip screw (DHS) in the treatment of subcapital neck fractures. Methods. A prospective study of 96 patients with subcapital neck fractures was carried out in a faculty hospital. Patients underwent surgery with closed reduction and internal fixation with DHS. Results. There were 58% male and 42% female patients, with a mean age of 53 years (+/?14). In terms of Garden classification, 60% were Garden IV, 26% were Garden III, and 14% were Garden II. Nonunion was observed in three cases (3%) and was treated with valgus intertrochanteric osteotomy, in all cases leading to successful healing. Avascular necrosis was observed in 16% of patients. The positioning of the screw into the femoral head showed a significant correlation with necrosis. Conclusions. The incidence of necrosis in patients under the age of 50 years is twice as high as that in older patients. Displacement is a predictive factor regarding osteonecrosis and is associated with a high and anterior position of the screw in the femoral head. Level II of evidence. Study Type: therapeutic study. PMID:24967124

  18. Arthroscopic 4-Point Suture Fixation of Anterior Cruciate Ligament Tibial Avulsion Fractures

    PubMed Central

    Boutsiadis, Achilleas; Karataglis, Dimitrios; Agathangelidis, Filon; Ditsios, Konstantinos; Papadopoulos, Pericles

    2014-01-01

    Tibial eminence avulsion fractures are rare injuries occurring mainly in adolescents and young adults. When necessary, regardless of patient age, anatomic reduction and stable internal fixation are mandatory for fracture healing and accurate restoration of normal knee biomechanics. Various arthroscopically assisted fixation methods with sutures, anchors, wires, or screws have been described but can be technically demanding, thus elongating operative times. The purpose of this article is to present a technical variation of arthroscopic suture fixation of anterior cruciate ligament avulsion fractures. Using thoracic drain needles over 2.4-mm anterior cruciate ligament tibial guidewires, we recommend the safe and easy creation of four 2.9-mm tibial tunnels at different angles and at specific points. This technique uses thoracic drain needles as suture passage cannulas and offers 4-point fixation stability, avoiding potential complications of bony bridge fracture and tunnel connection. PMID:25685674

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

    PubMed Central

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

    2014-01-01

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

  20. Load Sharing Mechanism Across Graft-Bone Interface in Static Cervical Locking Plate Fixation

    PubMed Central

    Han, In Ho; Kuh, Sung Uk; Chin, Dong Kyu; Jin, Byung Ho; Cho, Yong Eun

    2009-01-01

    Objective This study is a retrospective clinical study over more than 4 years of follow up to understand the mechanism of load sharing across the graft-bone interface in the static locking plate (SLP) fixation compared with non-locking plate (NLP). Methods Orion locking plates and Top non-locking plates were used for SLP fixation in 29 patients and NLP fixation in 24 patients, respectively. Successful interbody fusion was estimated by dynamic X-ray films. The checking parameters were as follows : screw angle (SA) between upper and lower screw, anterior and posterior height of fusion segment between upper and lower endplate (AH & PH), and upper and lower distance from vertebral endplate to the end of plate (UD & LD). Each follow-up value of AH and PH were compared to initial values. Contributions of upper and lower collapse to whole segment collapse were estimated. Results Successful intervertebral bone fusion rate was 100% in the SLP group and 92% in the NLP group. The follow-up mean value of SA in SLP group was not significantly changed compared with initial value, but follow-up mean value of SA in NLP group decreased more than those in SLP group (p=0.0067). Statistical analysis did not show a significant difference in the change in AH and PH between SLP and NLP groups (p>0.05). Follow-up AH of NLP group showed more collapse than PH of same group (p=0.04). The upper portion of the vertebral body collapsed more than the lower portion in the SLP fixation (p=0.00058). Conclusion The fused segments with SLP had successful bone fusion without change in initial screw angle, which was not observed in NLP fixation. It suggests that there was enough load sharing across bone-graft interface in SLP fixation. PMID:19444346

  1. Expansion rates and outcomes for iliac artery aneurysms

    Microsoft Academic Search

    Steven M. Santilli; Shane E. Wernsing; Eugene S. Lee

    2000-01-01

    Purpose: The expansion rates and outcomes of iliac artery aneurysms (IAAs) were determined. Methods: A retrospective chart review was conducted to identify patients in whom IAAs had been diagnosed between June 1990 and March 1999 in a vascular surgery service at a large university-affiliated Veterans Affairs medical center. The patients were veterans, 187 men and two women, in whom the

  2. Sharp Recanalization for Chronic Left Iliac Vein Occlusion

    SciTech Connect

    Ito, Nobutake, E-mail: nobutake@rad.med.keio.ac.jp; Isfort, Peter; Penzkofer, Tobias [RWTH Aachen University, Department of Diagnostic and Interventional Radiology, University Hospital (Germany); Grommes, Jochen; Greiner, Andreas [RWTH Aachen University, Department of Vascular Surgery, University Hospital (Germany); Mahnken, Andreas [RWTH Aachen University, Department of Diagnostic and Interventional Radiology, University Hospital (Germany)

    2012-08-15

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

  3. Percutaneous Endovascular Treatment of Chronic Iliac Artery Occlusion

    SciTech Connect

    Carnevale, F. C. [Institute of Radiology, University of Sao Paulo, Department of Interventional Radiology (Brazil)], E-mail: fcarnevale@uol.com.br; De Blas, Mariano; Merino, Santiago; Egana, Jose M. [Hospital De Guipuzcoa, Department of Radiology (Spain); Caldas, Jose G.M.P. [Institute of Radiology, University of Sao Paulo, Department of Interventional Radiology (Brazil)

    2004-09-15

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

  4. Minimal iliac bone harvesting in sinus lift surgery.

    PubMed

    Thiéry, G; Lari, N; Adam, S; Salles, F

    2013-08-01

    For sinus grafting, the authors propose a minimal posterior iliac bone harvesting, with local anesthesia. Autogenous bone grafting continues to be considered the gold standard for sinus grafting. The classic harvesting sites are calvarial, anterior iliac, and tibial, and harvesting is usually practiced under general anesthesia. We performed this technique in 7 patients under local anesthesia. In the posterior iliac crest, with a specific trocar for bone puncture biopsy, bone was harvested. We performed 1 cm longer for 5-mm diameter of bone. Three bone biopsies were harvested on each side. The harvested cancellous bone (5 cm(3)) was mixed with triphosphocalcic (TCP) material (2 cm(3)), and blood (1 cm(3)). A classic sinus lift was realized. After 6 months, the success rate of bone grafting was 100%. Each of the 7 patients could be implanted by an average of 4 dental implants by superior maxillary. For sinus lift, this simple posterior iliac-bone biopsy harvesting under local anesthesia is very comfortable for the patient and also safe. It provides enough marrow bone to be mixed with TCP for a sinus lift. PMID:20545541

  5. Endovascular Stent-Grafting for Infected Iliac Artery Pseudoaneurysms

    SciTech Connect

    Sanada, Junichiro, E-mail: sanadaj@rad.m.kanazawa-u.ac.jp; Matsui, Osamu [Kanazawa University School of Medicine, Department of Radiology (Japan); Arakawa, Fumitaka; Tawara, Mari [Toyama Red Cross Hospital, Department of Radiology (Japan); Endo, Tamao [Kanazawa University School of Medicine, Department of Radiology (Japan); Ito, Hiroshi [Noto General Hospital, Department of Radiology (Japan); Ushijima, Satoshi [Noto General Hospital, Department of Surgery (Japan); Endo, Masamitsu [National Hospital of Kanazawa, Department of Cardiovascular Surgery (Japan); Ikeda, Masahiro; Miyazu, Katsuyuki [Toyama Red Cross Hospital, Department of Cardiovascular Surgery (Japan)

    2005-01-15

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

  6. Alignment of pedicle screws with pilot holes: can tapping improve screw trajectory in thoracic spines?

    PubMed Central

    Erkan, Serkan; Hsu, Brian; Mehbod, Amir A.; Perl, John; Transfeldt, Ensor E.

    2009-01-01

    Pedicle screws are placed using pilot holes. The trajectory of pilot holes can be verified by pedicle sounding or radiographs. However, a pilot hole alone does not insure that the screw will follow the pilot hole. No studies have characterized the risk of misalignment of a pedicle screw with respect to its pilot hole trajectory. The objective of this study was to measure the misalignment angles between pedicle screws and pilot holes with or without tapping. Six human cadaveric thoracic spines were used. One hundred and forty pilot holes were created with a straight probe. Steel wires were temporarily inserted and their positions were recorded with CT scans. The left pedicles were tapped with 4.5 mm fluted tap and the right pedicles remained untapped. Pedicle screws (5.5 mm) were inserted into the tapped and untapped pedicles followed by CT scans. The trajectories of pilot holes and screws were calculated using three-dimensional vector analysis. A total of 133 pilot holes (95%) were inside pedicles. For the untapped side, 14 out of 68 (20%) screws did not follow the pilot holes and were outside the pedicles. For the tapped side, 2 out of 65 (3%) did not follow and breached the pedicles. The average misalignment angles between the screw and pilot hole trajectory were 7.7° ± 6.5° and 5.6° ± 3.2° for the untapped side and tapped side, respectively (P < 0.05). Most pedicle screws had lateral screw breach (13 out of 16) whereas most pilot holes had medial pedicle breach (6 out of 7). Tapping of pilot holes (1 mm undertap) helps align pedicle screws and reduces the risk of screw malposition. Although most pedicle screws had lateral breach, the risk of medial pedicle breach of the pilot holes must be recognized. PMID:19526377

  7. 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.

  8. Finite element analysis of a subtrochanteric fractured femur with dynamic hip screw, dynamic condylar screw, and proximal femur nail implants--a comparative study.

    PubMed

    Sowmianarayanan, S; Chandrasekaran, A; Kumar, R Krishna

    2008-01-01

    Selection of the correct type of implant for fracture fixation has become a very interesting problem in the orthopaedic community. The present work studies the biomechanical behaviour of the femur with three different implant configurations for simple transverse subtrochanteric fracture and the intact femur using finite element analysis. The implants considered in this study are as follows: dynamic hip screw (DHS), dynamic condylar screw (DCS), and proximal femur nail (PFN). The modelling software Unigraphics and finite element simulation software ANSYS are used for the present analysis. The three implants are compared for deflection, stress, and strains. The simulation also includes modelling of the cortical defect near the fracture. An estimation of the critical depth of the cortical defect based on the von Mises stress is obtained using this study on the DHS implant. The displacement and principal stress on the proximal femur have been compared for all the implant models. The stresses on the cortical screws for DCS and DHS implants have also been compared. The result shows that the DHS and DCS implants behave in a similar way to the intact femur compared with the PFN implant. PMID:18335723

  9. Biomechanical evaluation of a bioabsorbable expansion bolt for hamstring graft fixation in ACL reconstruction: an experimental study in calf tibial bone

    Microsoft Academic Search

    S. Piltz; R. Dieckmann; L. Meyer; P. Strunk; W. Plitz; G. Lob

    2005-01-01

    Introduction: The purpose of our study was to evaluate and compare the primary fixation strength of a novel bioabsorbable two shell expansion bolt (EB) with that of a well-established interference screw-fixation technique in hamstring reconstruction of the anterior cruciate ligament. Materials and methods: Thirty calf tibia plateaus (age 5–6 months) were assigned to three groups: In group I (n=10) triple-stranded hamstring

  10. Comparison of Bioabsorbable Suture Anchor Fixation on the Tibial Side for Anterior Cruciate Ligament Reconstruction Using Free Soft Tissue Graft: Experimental Laboratory Study on Porcine Bone

    PubMed Central

    Na, Suk In; Lee, Jong Min; Park, Ju Yong

    2014-01-01

    Purpose The use of graft tissue fixation using bioabsorbable interference screws (BISs) in anterior cruciate ligament (ACL) reconstruction offers various advantages, but limited pullout strength. Therefore, additional tibial fixation is essential for aggressive rehabilitation. We hypothesized that additional graft tissue fixation using bioabsorbable suture anchors (BSA) would provide sufficient pull-out strength. Materials and Methods Twenty four fresh frozen porcine distal femur and patellar tendon preparations were used. All specimens were divided into three groups based on additional fixation methods: A, isolated BIS; B, BIS and BSA; and C, BIS and post cortical screw. Tensile testing was carried out under an axial load. Ultimate failure load and ultimate failure load after cyclic loading were recorded. Results The ultimate failure loads after load to failure testing were 166.8 N in group A, 536.4 N in group B, and 438 N in group C; meanwhile, the ultimate failure loads after load to failure testing with cyclic loading were 140 N in group A, 466.5 N in group B, and 400 N in group C. Stiffness after load to failure testing was 16.5 N/mm in group A, 33.5 N/mm in group B, and 40 N/mm in group C. An additional BSA fixation resulted in a significantly higher ultimate failure load and stiffness than isolated BIS fixation, similar to post screw fixation. Conclusion Additional fixation using a BSA provided sufficient pullout strength for ACL reconstruction. The ultimate failure load of the BSA technique was similar to that of post cortical screws. PMID:24719145

  11. The Fixation of Nitrogen.

    ERIC Educational Resources Information Center

    Andrew, S. P. S.

    1978-01-01

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

  12. Update: Biological Nitrogen Fixation.

    ERIC Educational Resources Information Center

    Wiseman, Alan; And Others

    1985-01-01

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

  13. Flow patterns in twin-screw extruders

    Microsoft Academic Search

    O. S. Carneiro; G. Caldeira; J. A. Covas

    1999-01-01

    Flow visualisation studies in an intermeshing co-rotating twin-screw extruder operated under starve-fed conditions are presented. Different numbers of kneading discs and relative staggering angles were used in the definition of the mixing blocks. Conveying and left-handed elements were also utilised. The images recorded provided information on flow patterns, on the degree of filling of the screw channels and on the

  14. Parametric modeling of ball screw spindles

    Microsoft Academic Search

    A. Dadalau; M. Mottahedi; K. Groh; A. Verl

    2010-01-01

    In the product development process numerical optimization can successfully be applied in the early product design stages.\\u000a In the very common case of ball screw drives, the dynamical behavior is most depending on the geometrical shape of the ball\\u000a screw itself. Properties like axial and torsional stiffness, moment of inertia, maximum velocity and acceleration are determined\\u000a not only by the

  15. Patella Fracture Fixation with Suture and Wire: you Reap what you Sew

    PubMed Central

    Egol, Kenneth; Howard, Daniel; Monroy, Alexa; Crespo, Alexander; Tejwani, Nirmal; Davidovitch, Roy

    2014-01-01

    Introduction Operative fixation of displaced inferior pole patella fractures has now become the standard of care. This study aims to quantify clinical, radiographic and functional outcomes, as well as identify complications in a cohort of patients treated with non-absorbable braided suture fixation for inferior pole patellar fractures. These patients were then compared to a control group of patients treated for mid-pole fractures with K-wires or cannulated screws with tension band wiring. Methods In this IRB approved study, we identified a cohort of patients who were diagnosed and treated surgically for a displaced patella fracture. Demographic, injury, and surgical information were recorded. All patients were treated with a standard surgical technique utilizing non-absorbable braided suture woven through the patellar tendon and placed through drill holes to achieve reduction and fracture fixation. All patients were treated with a similar post-operative protocol and followed up at standard intervals. Data were collected concurrently at follow up visits. For purpose of comparison, we identified a control cohort with middle third patella fractures treated with either k-wires or cannulated screws and tension band technique. Patients were followed by the treating surgeon at regular follow-up intervals. Outcomes included self-reported function and knee range of motion compared to the uninjured side. Results Forty-nine patients with 49 patella fractures identified retrospectively were treated over 9 years. This cohort consisted of 31 females (63.3%) and 18 males (36.7%) with an average age of 57.1 years (range 26 - 88 years). Patients had an average BMI of 26.48 (range 19 - 44.08). Thirteen patients with inferior pole fractures underwent suture fixation and 36 patients with mid-pole fractures underwent tension band fixation (K-wire or cannulated screws with tension band). In the suture cohort, one fracture failed open repair (7.6%), which was revised again with sutures and progressed to union. Of the 36 fractures repaired with a tension band fixation, 11 underwent secondary surgery due to hardware pain or fixation failure (30.6%). At one year, no difference was seen in knee range of motion between cohorts. All fractures healed radiographically. Those patients who required reoperation or removal of hardware had significantly diminished range of motion about their injured knee (p > 0.005). Conclusions Patients who sustain inferior pole patella fractures have limited options for fracture fixation. Suture repair is clinically acceptable, yielding similar results to patella fractures repaired with metal implants. Importantly, patients undergoing suture repair appear to have fewer hardware related postoperative complications than those receiving wire fixation for midpole fractures. PMID:25328461

  16. A locking contoured plate for distal fibular fractures: mechanical evaluation in an osteoporotic bone model using screws of different length.

    PubMed

    Zahn, Robert K; Jakubietz, Michael; Frey, Sönke; Doht, Stefanie; Sauer, Alexander; Meffert, Rainer H

    2014-02-01

    Osteoporotic bone with poor mechanical capacity provides limited stability after fixation of ankle fractures. Stabilization with an implant providing increased fixation strength in osteoporotic bone could reduce failure rates of fixation and allow a more functional treatment. The purpose of this study was to evaluate a locking contoured plate for fixation of distal fibular fractures in comparison with a conventional contoured plate in an osteoporotic bone model. Eighty cylinders of osteoporotic bone surrogates were fixed with the two plates. We performed torque-to-failure and cyclic testing experiments using screws of different length with a Zwick/Roell testing machine. The locking system showed higher torque-to-failure and maximum torque levels as compared with the conventional plate in torque-to-failure experiments and torsional cyclic testing. The locking contoured plate provides improved fixation strength in the osteoporotic bone model. The locking system may be appropriate for fixation of distal fibular fractures, especially in osteoporotic bone with poor mechanical capacity. PMID:23676259

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

    SciTech Connect

    Franchin, Marco [Varese University Hospital, University of Insubria, Department of Surgical Sciences, General Surgery 1, School of Medicine (Italy); Tozzi, Matteo; Piffaretti, Gabriele, E-mail: gabriele.piffaretti@uninsubria.it [Varese University Hospital, University of Insubria, Department of Surgical Sciences, Vascular Surgery, School of Medicine (Italy); Carrafiello, Gianpaolo [Varese University Hospital, University of Insubria, Department of Radiology, Interventional Radiology, School of Medicine (Italy); Castelli, Patrizio [Varese University Hospital, University of Insubria, Department of Surgical Sciences, Vascular Surgery, School of Medicine (Italy)

    2011-10-15

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

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

    PubMed Central

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

    2014-01-01

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

  19. Calcifications of Iliac Arteries in Newborns and Infants

    PubMed Central

    Meyer, W. W.; Lind, J.

    1972-01-01

    Calcific incrustations of the primary internal elastic membrane in the common and internal iliac arteries could be shown grossly by a modified Von Kossa reaction in one-half of all necropsied newborns and infants in the first 4 weeks of life. The calcium content of the Von Kossa positive lesions was verified by Voigt's technique. After the age of 1 year calcific deposits were found in nearly every case. It is unlikely that resorption of these early calcific deposits occurs with growth. The early development of calcific incrustations in the common and internal iliac arteries is obviously related to their position and function in the fetal circulation, i.e. to the higher haemodynamic load which results from the rapid increase in blood flow to the placenta during fetal development, and is associated with an accelerated growth and widening of both vessels. In both iliac arteries only the well-differentiated, thick primary internal elastic membrane becomes calcified in childhood. This membrane is not present throughout the circumference of these arteries, but is developed in certain sectors only. Hence, the predilection site of the calcific incrustations, as well as their gross and microscopical patterns, is determined by the structural peculiarities of both iliac arteries, i.e. by the heterogeneous differentiation of the elastic elements in the vessel's tube. The significance of this heterogeneous structure for the development of later atherosclerotic lesions is still to be evaluated. ImagesFIG. 1.FIG. 3.FIG. 4.FIG. 5.FIG. 6.FIG. 7.FIG. 8.FIG. 9.PLATE A.PLATE B.PLATE C.PLATE D.PLATE E.PLATE F. PMID:4113749

  20. Early tissue responses to zoledronate, locally delivered by bone screw, into a compromised cancellous bone site: a pilot study

    PubMed Central

    2014-01-01

    Background In fracture treatment, adequate fixation of implants is crucial to long-term clinical performance. Bisphosphonates (BP), potent inhibitors of osteoclastic bone resorption, are known to increase peri-implant bone mass and accelerate primary fixation. However, adverse effects are associated with systemic use of BPs. Thus, Zoledronic acid (ZOL) a potent BP was loaded on bone screws and evaluated in a local delivery model. Whilst mid- to long-term effects are already reported, early cellular events occurring at the implant/bone interface are not well described. The present study investigated early tissue responses to ZOL locally delivered, by bone screw, into a compromised cancellous bone site. Methods ZOL was immobilized on fibrinogen coated titanium screws. Using a bilateral approach, ZOL loaded test and non-loaded control screws were implanted into femoral condyle bone defects, created by an overdrilling technique. Histological analyses of the local tissue effects such as new bone formation and osteointegration were performed at days 1, 5 and 10. Results Histological evaluation of the five day ZOL group, demonstrated a higher osseous differentiation trend. At ten days an early influx of mesenchymal and osteoprogenitor cells was seen and a higher level of cellular proliferation and differentiation (p?screw contact and bone volume values within the defect tended to increase. Local drug release did not induce any adverse cellular effects. Conclusion This study indicates that local ZOL delivery into a compromised cancellous bone site actively supports peri-implant osteogenesis, positively affecting mesenchymal cells, at earlier time points than previously reported in the literature. PMID:24656151

  1. The Mechanics of External Fixation

    PubMed Central

    Rozbruch, S. Robert

    2006-01-01

    External fixation has evolved from being used primarily as a last resort fixation method to becoming a main stream technique used to treat a myriad of bone and soft tissue pathologies. Techniques in limb reconstruction continue to advance largely as a result of the use of these external devices. A thorough understanding of the biomechanical principles of external fixation is useful for all orthopedic surgeons as most will have to occasionally mount a fixator throughout their career. In this review, various types of external fixators and their common clinical applications are described with a focus on unilateral and circular frames. The biomechanical principles that govern bony and fixator stability are reviewed as well as the recommended techniques for applying external fixators to maximize stability. Additionally, we have illustrated methods for managing patients while they are in the external frames to facilitate function and shorten treatment duration. PMID:18751766

  2. The Turn of the Screw: Optimal Design of an Archimedes Screw

    Microsoft Academic Search

    Chris Rorres

    2000-01-01

    The geometry of an Archimedes screw is governed by certain external parameters (its outer radius, length, and slope) and certain internal parameters (its inner radius, number of blades, and the pitch of the blades). The external parameters are usually determined by the location of the screw and how much water is to be lifted. The internal parameters, however, are free

  3. Novel posterior fixation keratoprosthesis

    NASA Astrophysics Data System (ADS)

    Lacombe, Emmanuel

    1992-08-01

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

  4. CARBON DIOXIDE FIXATION.

    SciTech Connect

    FUJITA,E.

    2000-01-12

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

  5. Balloon-expandable common iliac artery occluder device for endovascular aneurysm repair.

    PubMed

    Silberzweig, J E; Marin, M L; Hollier, L H; Mitty, H A; Connelly, T L

    2001-01-01

    This study was performed to evaluate the efficacy of a balloon-expandable Palmaz stent common iliac artery occluder device for endovascular stent-graft repair of aortoiliac aneurysms. Eighty-four patients (79 men, 5 women; age range 60-95 yr; mean age, 76 yr) with aortoiliac aneurysms underwent endovascular stent-graft repair. The repair consisted of a stent-graft extending from the abdominal aorta to the iliac or common femoral artery, a cross-femoral bypass graft, and an endovascular arterial occluder device within the contralateral common iliac artery. The occluder device consisted of a 5-cm segment of 6-mm diameter polytetrafluoroethylene (PTFE) graft with a purse-string suture occluding the leading end and a Palmaz stent sutured to the trailing end. The occluder device was delivered through a 17F catheter via an arteriotomy. Eighty-three of the 84 patients received aortic endografts. In one case, infrarenal aortic rupture occurred during deployment of the aortic stent requiring conversion to an open surgical repair. Initial technical success for occluder device insertion was achieved in 78 of the remaining 83 patients. Failure to advance the occluder device delivery sheath through a diseased iliac artery occurred in one patient. Common iliac artery rupture occurred during balloon expansion and occluder device deployment in two patients. Two patients required additional coil embolization of the common iliac artery adjacent to the occluder device at the time of stent-graft insertion to correct incomplete iliac occlusion. Delayed occluder device-related complications included one patient with a postoperative iliac endoleak who required percutaneous coil embolization and one patient with a postoperative iliac endoleak in whom a contained aortic aneurysm rupture developed that was treated by surgical ligation of the common iliac artery. Use of the Palmaz stent-based iliac artery occluder device is an effective technique to induce common iliac artery thrombosis to facilitate endoluminal stent-graft aneurysm repair. PMID:11586452

  6. Basic Study for Ultrasound-Based Navigation for Pedicle Screw Insertion Using Transmission and Backscattered Methods

    PubMed Central

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

    2015-01-01

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

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

    PubMed

    Peterson, Kyle S; Hyer, Christopher F

    2015-01-01

    Charcot neuroarthropathy is frequently recognized as a major cause of morbidity in patients with neuropathic diabetes mellitus. Recently, intramedullary beam screw fixation has been used for midfoot Charcot reconstructions. Ten below-the-knee cadaveric specimens were used to demonstrate an antegrade, posterior approach for placement of a medial column beam screw, with specific attention to the proximity of the anatomic structures at risk. Six structures at risk were identified, including the sural nerve, ankle joint, flexor hallucis longus tendon, Achilles tendon, neurovascular bundle, and peroneal tendon sheath. The sural nerve was the most commonly injured structure, injured in 50% of the limbs. The Achilles and flexor hallucis longus tendons were injured in 20% and the ankle joint in 10% of the limbs. The neurovascular bundle and peroneal tendon sheath were located over 1 cm from the reference guidewire and were considered safe structures in this approach. Our results have demonstrated an alternative posterior approach to the delivery of an intramedullary medial column beam screw, instead of a retrograde technique beginning in the metatarsal heads. Our results have also made clear the need to be aware of the potential for damage to the sural nerve, Achilles tendon, flexor hallucis longus tendon, and ankle joint. PMID:25456342

  8. Temperature calculation for extruder screws with internal heat pipes

    NASA Astrophysics Data System (ADS)

    Lakemeyer, C.; Schöppner, V.

    2014-05-01

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

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

    SciTech Connect

    Fahrni, Markus [University Hospital of Zurich, Zurich, Department of Radiology (Switzerland); Lachat, Mario M [University Hospital of Zurich, Zurich, Clinic of Cardiovascular Surgery (Switzerland); Wildermuth, Simon; Pfammatter, Thomas [University Hospital of Zurich, Zurich, Department of Radiology (Switzerland)], E-mail: pfammatter@dmr.usz.ch

    2003-09-15

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

  10. Fixation techniques for the anterior cruciate ligament reconstruction: early follow-up. A systematic review of level I and II therapeutic studies.

    PubMed

    Speziali, Andrea; Delcogliano, Marco; Tei, Matteo; Placella, Giacomo; Bartoli, Matteo; Menghi, Amerigo; Cerulli, Giuliano

    2014-12-01

    The purpose of our study was that to systematically review the fixation techniques for the ACL reconstruction and associated clinical outcomes at the early follow-up. Systematic search on three electronic databases (Cochrane register, Medline and Embase) of fixation devices used for primary ACL reconstruction with doubled semitendinosus and gracilis and bone-patellar tendon-bone autografts in randomized clinical trials of level I and II of evidence published from January 2001 to December 2011. Therapeutic studies collected were with a minimum 12-month follow-up, and the clinical outcomes were evaluated by at least one of International Knee Documentation Committee, Lysholm and Tegner functional scales and at least one of the following knee stability tests: arthrometric AP tibial translation, Lachman test and pivot-shift test. Nineteen articles met the inclusion criteria. At the femoral side cross-pin, metallic interference screw, bioabsorbable interference screw, and suspensory device were used in 32.3, 27.3, 24.8, 15.5% of patients, respectively. At the tibial side fixation was achieved with metallic interference screw, bioabsorbable interference screw, screw and plastic sheath, screw post and cross-pin in 38.7, 31, 15.7, 12.8, and 1.7% of patients, respectively. Side-to-side anterior-posterior tibial translation was 1.9 ± 0.9, 1.5 ± 0.9, 1.5 ± 0.8, 2.2 ± 0.4 mm for metallic interference screw, bioabsorbable screw, cross-pin and suspensory device, respectively. At least two-third of all the patients achieved good-to-excellent clinical outcomes. Rate of failure was 6.1, 3.3, 1.7 and 1.2% for bioabsorbable interference screw, metallic interference screw, cross-pin and suspensory device, respectively. Clinical outcomes are good to excellent in almost two-third of the patients but several pitfalls that affect the current fixation techniques as graft tensioning such as graft-tunnel motion are still unaddressed. PMID:25269758

  11. Medial patellofemoral ligament reconstruction: a new technique for graft fixation at the patella without implants.

    PubMed

    Shafizadeh, Sven; Balke, Maurice

    2014-02-01

    Patellofemoral instability is a complex disorder that is often accompanied by insufficiency or tearing of the medial patellofemoral ligament. Over the past few years, several techniques using free tendon grafts for medial patellofemoral ligament reconstruction have become popular because of their reproducible effect and good outcome. Whereas most surgeons prefer femoral fixation of the graft using an interference screw, the possibilities of patellar fixation are numerous. All of the different techniques have their own advantages and pitfalls. We describe a technique in which we drill 2 blind-ending tunnels (1 cm) at the medial aspect of the patella, where the doubled graft (not the free ends) is pulled in and fixed. By using a special technique for shuttling the sutures, there is no need for an additional skin incision and no need for implants, allowing very secure graft fixation without a relevant risk of fracture. PMID:24749029

  12. Design optimisation and experimental evaluation of dorsal double plating fixation for distal radius fracture.

    PubMed

    Chen, Alvin Chao-Yu; Lin, Yu-Hao; Kuo, Hsien-Nan; Yu, Tsung-Chih; Sun, Ming-Tsung; Lin, Chun-Li

    2013-04-01

    This study determines the relative effects of changes in osteoporosis condition, plate/screw design factors (plate angle/length/width/thickness and screw diameter) and fixation methods (screw number and screw length) on the biomechanical response of dorsal double plating (DDP) fixation at a distal radius fracture to determine the optimal design and evaluate its biomechanical strength using the dynamic fatigue test. Eighteen CAD and finite element (FE) models corresponding to a Taguchi L18 array were constructed to perform numerical simulations to simulate the mechanical responses of a DDP fixed in a simply distal radius fracture bone. The Taguchi method was employed to determine the significance of each design factor in controlling bone/plate/screw stress and distal fragment displacement under axial (100 N), bending (1 N m) and torsion (1 N m) loads. Simulation results indicated that the order rank to determine the mechanical response was the plate thickness, plate width, screw diameter, and number of screws. Dorsal intermediate (L) plate with 60 mm length, 1.8 mm thickness, 6.0 mm width and 2.8 mm diameter, 20 mm length dual-thread locking screw can be found for optimisation. The DDP, including an L plate with 0°, 30° and 60° angles and a straight I plate, were made with Ti6Al4V to fix onto the sawbones with three corresponding radius fractures to perform the dynamic testing. The specimens were oscillated with loads between 10 N and 150 N at 5 Hz for 20,000 cycles. The average stiffness in 20,000 test cycles was 425.7 N/mm, 461.1 N/mm and 532.1N/mm for the 0°, 30° and 60° constructs, respectively. No difference in stiffness was found in the same angled constructs throughout the 20,000 cycles of testing (p > 0.05). Lack of gross construct failures during cyclic testing and reasonable stiffness corroborated that our new constructs tested to date seem stable enough to support restricted post-operative loads. PMID:23099020

  13. Absorbable biologically based internal fixation.

    PubMed

    Ibrahim, Ahmed M S; Koolen, Pieter G L; Kim, Kuylhee; Perrone, Gabe S; Kaplan, David L; Lin, Samuel J

    2015-01-01

    Absorbable devices for use in internal fixation have advanced over the years to become reliable and cost-effective alternatives to metallic hardware. In the past, biodegradable fixation involved a laborious implantation process, and induced osteolysis and inflammatory reactions. Modern iterations exhibit increased strength, smoother resorption, and lower rates of reactivity. A newer generation manufactured from silk has emerged that may address existing limitations and provide a greater range of fixation applications. PMID:25440418

  14. 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.

  15. Rotary screw compressors in the gas patch

    SciTech Connect

    Jandjel, D.G.

    1996-01-01

    In 1959, Howden introduced the oil-injected rotary screw (OIS) compressor, which has, since then, methodically replaced the reciprocating (piston) compressor in applications such as air, refrigeration and fuel gas. Rotary screw compressors have been making inroads in gas recovery, a field once dominated by reciprocating compressors. Rotary screws do not require extensive maintenance, thus downtime is minimized throughout an operating year. Preventive maintenance is simple, since it consists of regular oil sample analysis which does not require system shut-down. As a result of the slide valve, OIS compressors can tune to field conditions with the greatest of ease, and without complicated process control. In addition, this method of capacity control is more efficient than unloading or use of a bypass-recirculation line. Both engineers and operators alike have found this flexibility to be a most redeeming feature. Finally, OIS compressors are capable of much larger flows then recips. 2 figs.

  16. Low energy high pressure miniature screw valve

    DOEpatents

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

    2006-12-12

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

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

    PubMed

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

    2015-02-01

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

  18. 21 CFR 888.3070 - Pedicle screw spinal system.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES ORTHOPEDIC DEVICES Prosthetic Devices § 888.3070 Pedicle screw spinal system. (a) Identification. Pedicle screw spinal systems...

  19. 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.

  20. Clinical and economic impact of using generic 7.3-mm cannulated screws at a level II trauma center.

    PubMed

    Althausen, Peter L; Kurnik, Chris G; Shields, Troy; Anderson, Scott R; Gurnea, Taylor P; Coll, Daniel; Lu, Minggen

    2014-09-01

    We retrospectively studied the clinical and economic impact of a cost-containment program using high quality generic 7.3-mm screws for fixation of femoral neck fractures and pelvic ring injuries at a level II trauma center. Included in the study were 174 patients with femoral neck fractures or posterior pelvic ring injuries. These injuries were managed with 203 conventional and 178 generic implants. Study results showed no significant differences in age, sex, American Society of Anesthesiologists status, or fracture pattern; no differences in operative time, estimated blood loss, or complication rates; no increase in varus collapse, shortening, screw cutout, screw deformation, loosening, or conversion to arthroplasty; and no differences in hospital complications of deep venous thrombosis, pulmonary embolism, urinary tract infection, or pressure sores. Overall, our hospital realized a 70% reduction in implant costs, resulting in calendar-year savings of $50,531. At our institution, use of generic 7.3-mm cannulated screws has been a success. Hospital implant costs decreased significantly without any associated increase in complication rate or change in radiographic outcome. Generic implants have the potential to markedly reduce operative costs as long as quality products are used. PMID:25251525

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

    PubMed

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

    2015-01-01

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

  2. Distribution of the internal iliac artery of the male cat

    E-print Network

    Bratton, Gerald Roy

    1970-01-01

    DISTRIBUTION OZ THE INTEP~iAL ILIAC ARTERY OF THE MALE CAT Thesis by GERALD ROY BRATTON Submitted to the Graduate College of Texas A E: M Un versity in partial fur f1 llment of tne reouirements for the degree of MASTER OF SCIENCE December... 1970 Major Subject: Veterinary Anatomy DISTRIBUTION OE THL" iNTE1VlAL ILZAC ARTERy GF THE AiALE CAT A Thesis by (xERALD ROY BRATTON Approved as to style and content ny; Member) Tt 1 *f D " 'tj M . R !'rlember) Deoember 1970 ABSTFACT...

  3. Intraoral epimucosal fixation for reducible maxillary fractures of the jaws; surgical considerations in comparison to current techniques.

    PubMed

    Cortese, Antonio; Savastano, Germano; Amato, Massimo; Pantaleo, Giuseppe; Claudio, Pier Paolo

    2014-11-01

    Fractures of the jaw are often treated with rigid and stable internal fixation using plates or miniplates. Early surgery for jaw fractures is the optimal treatment; however, if a late treatment is begun, often the adoption of other protocols is needed. When the jaw fracture has one free bone fragment with 2 full-thickness lesions of mucoperiosteal soft tissues both on the buccal and palatal sides, the risk of resorption or necrosis is very high after elevating a mucoperiosteal flap for rigid fixation. For this reason, we developed an intraoral epimucosal fixation technique using self-locking screws and plates. Substantial advantages of this new technique, in comparison with other commonly used fixation techniques, consisted in the prevention of bone resorption or necrosis by safe and simple screw insertion procedure after manipulation of the fracture for reduction in closed surgery. Major indications for epimucosal fixation in closed surgery are the presence of jaw fractures without dislocation or reducible jaw fractures by manipulation particularly in edentulous patients. PMID:25318439

  4. Definitive Bone Fixation and Reconstruction: Conversion from Temporary External Fixation to Internal Fixation Methods

    Microsoft Academic Search

    Craig S. Bartlett; Benjamin Geer; David L. Helfet

    \\u000a Temporary external fixation is frequently employed in the military combat theater of operations to temporize devastating extremity\\u000a injuries and facilitate transport of the wounded soldier. Multiple civilian and a few military studies have provided helpful\\u000a insight into the staged treatment of these injuries including conversion of temporary external fixation to definitive stabilization\\u000a with internal fixation. Diaphyseal fractures of the long

  5. A Novel Pedicle Screw with Mobile Connection: A Pilot Study

    PubMed Central

    Oshima, Masashi; Ajiro, Yasumitsu; Uei, Hiroshi

    2014-01-01

    To prevent adjacent disc problems after spinal fusion, a pedicle screw with a mobile junction between the head and threaded shaft was newly developed. The threaded shaft of the screw has 10 degrees mobility in all directions, but its structure is to prevent abnormal translation and tilting. This screw was evaluated as follows: (1) endurance test: 106 times rotational stress was applied; (2) biological reactions: novel screws with a mobile head and conventional screws with a fixed head were inserted into the bilateral pedicles of the L3, L4, and L5 in two mini pigs with combination. Eight months after surgery, vertebral units with the screw rod constructs were collected. After CT scan, the soft and bony tissues around the screws were examined grossly and histologically. As a result, none of the screws broke during the endurance test stressing. The mean amount of abrasion wear was 0.0338?g. In the resected mini pig section, though zygapophyseal joints between fixed-head screws showed bony union, the amount of callus in the zygapophyseal joints connected with mobile-head screws was small, and joint space was confirmed by CT. No metalloses were noted around any of the screws. Novel screws were suggested to be highly durable and histologically safe. PMID:24724103

  6. Right Double Inferior Vena Cava (IVC) with Preaortic Iliac Confluence - Case Report and Review of Literature.

    PubMed

    Babu, C S Ramesh; Lalwani, Rekha; Kumar, Indra

    2014-02-01

    Anomalies of the inferior vena cava (IVC) are uncommon and most of them remain asymptomatic. Though rare, anomalies of IVC can lead to severe hemorrhagic complications especially during aortoiliac surgery. Prior knowledge of these variations facilitates proper interpretation of radiological images and safe performance of interventional procedures and surgeries. During routine anatomical dissection of abdomen in a female cadaver we observed the presence of right sided duplication of IVC. Both IVCs were present on the right side of abdominal aorta, one ventral and the other more dorsal in position and named ventral right IVC and dorsal right IVC. The ventrally and medially placed IVC, which appeared to be the main IVC was formed by the union of two common iliac veins in front of the right common iliac artery (Preaortic iliac confluence-"Marsupial Cava"). The right external iliac vein continued as the more dorsally and laterally placed dorsal right IVC. The right internal iliac vein after receiving a transverse anastomotic vein from the external iliac continued as the right common iliac vein. This transverse anastomosis was present behind the right common iliac artery. The narrower dorsal right IVC joined the wider ventral right IVC just below the level of renal veins to form a single IVC. The abdominal aorta presented a convexity to the left. PMID:24701503

  7. Right Double Inferior Vena Cava (IVC) with Preaortic Iliac Confluence – Case Report and Review of Literature

    PubMed Central

    Babu, C.S. Ramesh; Lalwani, Rekha; Kumar, Indra

    2014-01-01

    Anomalies of the inferior vena cava (IVC) are uncommon and most of them remain asymptomatic. Though rare, anomalies of IVC can lead to severe hemorrhagic complications especially during aortoiliac surgery. Prior knowledge of these variations facilitates proper interpretation of radiological images and safe performance of interventional procedures and surgeries. During routine anatomical dissection of abdomen in a female cadaver we observed the presence of right sided duplication of IVC. Both IVCs were present on the right side of abdominal aorta, one ventral and the other more dorsal in position and named ventral right IVC and dorsal right IVC. The ventrally and medially placed IVC, which appeared to be the main IVC was formed by the union of two common iliac veins in front of the right common iliac artery (Preaortic iliac confluence-“Marsupial Cava”). The right external iliac vein continued as the more dorsally and laterally placed dorsal right IVC. The right internal iliac vein after receiving a transverse anastomotic vein from the external iliac continued as the right common iliac vein. This transverse anastomosis was present behind the right common iliac artery. The narrower dorsal right IVC joined the wider ventral right IVC just below the level of renal veins to form a single IVC. The abdominal aorta presented a convexity to the left. PMID:24701503

  8. Eighth international congress on nitrogen fixation

    SciTech Connect

    Not Available

    1990-01-01

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

  9. DINITROGEN FIXATION IN ILLINOIS BUNDLEFLOWER

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Illinois bundleflower [Desmanthus illinoensis (Michx.) MacMillan] is a warm-season perennial forage legume that may serve as a pulse crop. Its productivity is influenced by its N2 fixation capability. Our objective was to estimate symbiotic N2 fixation of three Illinois bundleflower accessions from ...

  10. 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.

  11. Semi-Empirical Screw Compressor Chiller Model

    E-print Network

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

    and kW/ton with an accuracy of 4-7% when compared to the 4,104 data points acquired from a screw chiller system. The semi-empirical chiller model results were also compared to the Gordon-Ng model predictions as a function of the percentage chiller...

  12. High Bandwidth Control of Ball Screw Drives

    Microsoft Academic Search

    K. Erkorkmaz; A. Kamalzadeh

    2006-01-01

    This paper presents a tracking control strategy for high speed ball screw drives. Rigid body motion is controlled using adaptive sliding mode control. Torsional vibrations are modeled, experimentally identified, and compensated in the control law using notch filtering and active cancellation techniques. Attenuation of torsional resonances improves the stability margins and enables high positioning bandwidth to be achieved. The axis

  13. Improvements In Ball-Screw Linear Actuators

    NASA Technical Reports Server (NTRS)

    Iskenderian, Theodore; Joffe, Benjamin; Summers, Robert

    1996-01-01

    Report describes modifications of design of type of ball-screw linear actuator driven by dc motor, with linear-displacement feedback via linear variable-differential transformer (LVDT). Actuators used to position spacecraft engines to direct thrust. Modifications directed toward ensuring reliable and predictable operation during planned 12-year cruise and interval of hard use at end of cruise.

  14. COMPRESSION LOAD TRANSMISSION IN SCREW COMPRESSORS

    Microsoft Academic Search

    G. P. Adams; Z. H. Qin

    1997-01-01

    In the current investigations of the bearing forces in screw compressors, the supports at the bearings are basically treated as ideal, simply supported boundary conditions. By using statics theory, the loads on the rotors are converted to the bearings at the suction and discharge ends. Some studies on rotor dynamics have shown that the behaviors of a rotor bearing system

  15. Calculation of Rotor Interference in Screw Compressors

    Microsoft Academic Search

    N. Stosic; Ian K. Smith; A. Kovacevic

    Small rotor clearances are today a vital prerequisite for an efficient screw compressor. The clearances are responsible for compressor leakages, small clearance will minimise them and thereby increase both, the volumetric and adiabatic efficiency. A continuous improvement in the rotor manufacturing equipment has been achieved during the recent years and tight production tolerances may now be applied to compressor rotors.

  16. 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.

  17. Iliac artery endofibrosis in a middle-aged female long-distance runner.

    PubMed

    van Rensburg, Dina Christina Janse; van Rensburg, Audrey Jansen; van Duuren, Elsa Margaretha; Grant, Catharina Cornelia

    2014-12-01

    Exercise-induced iliac artery endofibrosis is a recently described abnormality of the external iliac artery that typically affects younger, healthy endurance athletes. Characteristic of the initially termed cyclist's iliac syndrome is lower limb pain during exercise with rapid recovery after exercise. This clinically complicated case describes an older female long-distance runner in whom an incorrect diagnosis of fibromuscular dysplasia was originally made when she presented with claudication and thrombosis of the right external iliac artery. A thrombectomy and bilateral balloon angioplasty were performed; however, her symptoms persisted. Four months later, she unexpectedly complained of dual calf claudication, a diagnosis of exercise-induced iliac artery endofibrosis was made, and a bilateral prosthetic graft bypass procedure was performed, which resulted in a good outcome. PMID:25122104

  18. Iliac Vein Compression Syndrome due to Bladder Distention Caused by Urethral Calculi

    PubMed Central

    Ikegami, Akiko; Kondo, Takeshi; Tsukamoto, Tomoko; Ohira, Yoshiyuki; Ikusaka, Masatomi

    2015-01-01

    We report a rare case of iliac vein compression syndrome caused by urethral calculus. A 71-year-old man had a history of urethral stenosis. He complained of bilateral leg edema and dysuria for 1 week. Physical examination revealed bilateral distention of the superficial epigastric veins, so obstruction of both common iliac veins or the inferior vena cava was suspected. Plain abdominal computed tomography showed a calculus in the pendulous urethra, distention of the bladder (as well as the right renal pelvis and ureter), and compression of the bilateral common iliac veins by the distended bladder. Iliac vein compression syndrome was diagnosed. Bilateral iliac vein compression due to bladder distention (secondary to neurogenic bladder, benign prostatic hyperplasia, or urethral calculus as in this case) is an infrequent cause of acute bilateral leg edema. Detecting distention of the superficial epigastric veins provides a clue for diagnosis of this syndrome. PMID:25802794

  19. Biomechanical rationale for implant choices in femoral neck fracture fixation in the non-elderly.

    PubMed

    Panteli, Michalis; Rodham, Paul; Giannoudis, Peter V

    2015-03-01

    Femoral neck fractures represent a relatively uncommon injury in the non-elderly population often resulting from high-energy trauma. The cornerstone of their management is anatomic reduction and stable internal fixation of the femoral neck in an attempt to salvage the femoral head. Complications including avascular necrosis of the femoral head, non-union and post-traumatic osteoarthritis are not uncommon. The clinical outcomes of these patients can be improved with good pre-operative planning, optimization of surgical procedures and introduction of new improved implants and techniques. In the herein study, we attempt to describe the biomechanical properties of the hip and compare the performance of the most commonly used devices. Experimental evidence suggests that in Pauwels type III fracture patterns a cephalomedullary nail was significantly stronger in axial loading. Moreover, in unstable basicervical patterns cannulated screws (triangular configuration) demonstrated a lower ultimate load to failure, whereas in subcapital or transervical patterns both the cannulated screws (triangular configuration) and the sliding hip screw demonstrated no compromise in fixation strength. The fracture pattern appears to be the major determinant of the ideal type of implant to be selected. For a successful outcome each patient needs to be considered on an individual basis taking into account all patient and implant related factors. PMID:25597514

  20. Surgical rib fixation - Technical aspects.

    PubMed

    Marasco, Silvana; Saxena, Pankaj

    2015-05-01

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

  1. [Accuracy of fluoroscopic navigation of pedicle screws. CT-based evaluation of bone screw placement].

    PubMed

    Fritsch, E; Duchow, J; Seil, R; Grunwald, I; Reith, W

    2002-04-01

    While the advantages of C-arm navigation in computer-assisted spine surgery are obvious, the accuracy of pedicle screw placement with virtual fluoroscopy still needs to be verified. The C-arm-based ION system (Medtronic Sofamor Danek) was used to navigate pedicle screw insertion in patients undergoing spinal surgery for various conditions. In a prospective study, a total of 160 screws were inserted in the first 30 consecutive patients since introduction of the system at our institution: 54 at the thoracic spine (highest level: TH4) and 106 at the lumbar spine. Computed tomography (CT) scans were performed postoperatively by two independent radiologists to control the accuracy of screw placement at the level of the pedicles after reconstruction of axial images according to Laine et al. The comparison of the calculated accuracy rate of pedicle screw placement using virtual fluoroscopy with reported results achieved with CT-based navigation shows similar results for virtual fluoroscopy and a remarkable increase of accuracy in comparison to reports on conventional pedicle screw placement. PMID:12056280

  2. Biomechanical study in polyurethane mandibles of different metal plates and internal fixation techniques, employed in mandibular angle fractures.

    PubMed

    Semeghini Guastaldi, Fernando Pozzi; Hochuli-Vieira, Eduardo; Guastaldi, Antonio Carlos

    2014-11-01

    The aim of this study was to perform a physicochemical and morphological characterization and compare the mechanical behavior of an experimental Ti-Mo alloy to the analogous metallic Ti-based fixation system, for mandibular angle fractures. Twenty-eight polyurethane mandibles were uniformly sectioned on the left angle. These were divided into 4 groups: group Eng 1P, one 2.0-mm plate and 4 screws 6 mm long; group Eng 2P, two 2.0-mm plates, the first fixed with 4 screws 6 mm long and the second with 4 screws 12 mm long. The same groups were created for the Ti-15Mo alloy. Each group was subjected to linear vertical loading at the first molar on the plated side in a mechanical testing unit. Means and standard deviations were compared with respect to statistical significance using ANOVA. The chemical composition of the Ti-15Mo alloy was close to the nominal value. The mapping of Mo and Ti showed a homogeneous distribution. SEM of the screw revealed machining debris. For the plates, only the cpTi plate undergoes a surface treatment. The metallographic analysis reveals granular microstructure, from the thermomechanical trials. A statistically significant difference was found (P < 0.05) when the comparison between both internal fixation techniques was performed. The 2P technique showed better mechanical behavior than 1P. PMID:25340696

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

    PubMed Central

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

    2014-01-01

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

  4. 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. PMID:25724313

  5. Medial Patellofemoral Ligament Reconstruction With a Looped Semitendinosus Tendon, Using Knotless Anchor Fixation on the Patella and Hybrid Fixation on the Femur

    PubMed Central

    Golant, Alexander; Quach, Tony; Rosen, Jeffrey E.

    2014-01-01

    Medial patellofemoral ligament (MPFL) reconstruction is a reliable surgical method for stabilizing a dislocating patella, with multiple techniques previously described. Although outcomes are generally favorable, the procedure is technically demanding and relies on precise identification of native MPFL insertion sites, secure fixation of the graft to these sites, and appropriate graft tension. We describe a technique for MPFL reconstruction with a looped semitendinosus tendon. The 2 free limbs of the graft are secured into blind-end patellar sockets with knotless anchors, and the looped end is initially secured into a medial femoral socket with a button on the opposite (lateral) cortex. Use of an adjustable-loop button allows for gradual adjustment of graft tension, as well as re-tensioning after cycling of the knee, before final aperture fixation on the femur with an interference screw. PMID:24904762

  6. Bioabsorbable fixation of scaphoid fractures and non-unions; analysis of early clinical outcomes.

    PubMed

    Ya'ish, F; Bailey, C A; Kelly, C P; Craigen, M A

    2013-01-01

    The vast majority of devices used for internal fixation of the scaphoid are metallic. This two-center study aimed to report the results of scaphoid fixation using a cannulated, bioabsorbable device made from a hydroxyapatite and poly-L-lactide composite in 29 consecutive patients. Fixation was performed for seven acute fractures and twenty-two established non-unions. Union was achieved in 72.4% of patients. Six of the acute fractures and fifteen of the non-unions united successfully. Modified Mayo Wrist Score ranged between good to excellent in all patients who successfully united, whereas patients who failed to unite ranged between poor to excellent, with one poor and two moderate scores. No adverse biocompatibility reactions were seen. Two failures with broken screws were re-explored and one of these was thought to be due to screw mal-placement. The device used is an alternative to conventional metal implants and produces comparable union rates to metallic devices in the short term. PMID:24156576

  7. Porous hydroxyapatite ceramics and their ability to be fixed by commercially available screws

    Microsoft Academic Search

    M. D. Ichiro Ono; M. D. Tohru Tateshita; Takehiko Nakajima

    1999-01-01

    We developed porous hydroxyapatite ceramics (HAP) which are screw fixable and evaluated the fixing abilities of commercially available screws using pull-out tests with the HAP implants. The fixing abilities were higher in the following order: Leibinger micro PLUS titanium screw>Osteomed M3 titanium screw>Leibinger standard mini screw>Martin-drill free screw. In preliminary examinations, the fixing ability of each of the screws differed

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

    PubMed

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

    2015-03-16

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

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

    PubMed Central

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

    2015-01-01

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

  10. Femoral head necrosis treated with vascularized iliac crest graft.

    PubMed

    Pavlovcic, V; Dolinar, D; Arnez, Z

    1999-01-01

    We reviewed 24 hips with avascular necrosis of the femoral head in 24 patients treated with vascularized iliac bone grafts 12 years after operation. In 7 patients the necrosis was classified as Ficat Stage II and in 17 patients as Stage III. Eight patients showed poor results. In 6 hips with fair results, moderate progression of the necrosis was noted at 3 to 8 years postoperatively. In 5 hips showing good results, slow progression with incipient signs of arthrosis were noted 8 years after surgery. In the remaining 5 patients with excellent results, no evidence of progression was noted 9 to 14 years postoperatively. The method described is recommended for treatment in the Ficat Stage II and early Stage III, when necrosis does not yet involve the complete femoral head. PMID:10486026

  11. Compression Load Transmission in Screw Compressors

    NASA Astrophysics Data System (ADS)

    Adams, G. P.; Qin, Z. H.

    1997-11-01

    In the current investigations of the bearing forces in screw compressors, the supports at the bearings are basically treated as ideal, simply supported boundary conditions. By using statics theory, the loads on the rotors are converted to the bearings at the suction and discharge ends. Some studies on rotor dynamics have shown that the behaviors of a rotor bearing system are, to some extent, controlled by the bearings that support the rotor. Therefore, it is important to study the dynamic performance of the rotor bearing system in screw compressors so that the bearing forces can be more accurately described. In this paper, a numerical method is presented for computing the compression loads by integrating the pressure over the rotor surface. Vector calculus and numerical integration methods are implemented to calculate the compression loads in order to obtain a robust procedure that can be applied to arbitrary rotor profiles. In addition, a dynamic model of a rigid compressor rotor supported by two cylindrical roller bearings and a four point contact ball bearing is developed from basic principles. This model simulates the dynamic responses of a typical screw compressor configuration. It includes five degrees of freedom of rotor motion interacting with the bearings of non-linear characteristics. Under the compression loads, the resulting bearing forces in the screw compressor are compared with those obtained by assuming ideal, simply supported boundary conditions at the bearings. It is shown that the interactions between the rotor and bearings are quite different by coupling the global rotor motion with the local dynamics of the bearings.

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

    SciTech Connect

    Whittaker, Charlotte Sara, E-mail: c_whittaker1@yahoo.co.uk; Ananthakrishnan, Ganapathy; DeNunzio, Mario Cosimo; Quarmby, John Winston; Bungay, Peter Mark [Derbyshire Royal Infirmary (United Kingdom)

    2008-07-15

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

  13. Molecular Biology of Nitrogen Fixation

    ERIC Educational Resources Information Center

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

    1975-01-01

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

  14. Evaluation of Bone Fixation Implants

    E-print Network

    Perkins, Luke 1990-

    2012-12-10

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

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

    PubMed

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

    2013-12-01

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

  16. 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

  17. Distal radius fixation through a mini-invasive approach of 15 mm. PART 1: a series of 144 cases.

    PubMed

    Lebailly, Frédéric; Zemirline, Ahmed; Facca, Sybille; Gouzou, Stéphanie; Liverneaux, Philippe

    2014-08-01

    The volar Henry approach is becoming the gold standard for distal radius fracture fixation. It decreases the incidence of nonunion, limits complications especially complex regional pain syndrome (CRPS) type I, and allows early mobilization of the wrist. Nonetheless, it has some disadvantages such as the size of the incision, which is not esthetically pleasing, and the loss of ligamentotaxis. This is why some authors have developed a mini-invasive approach. The aim of this work was to evaluate the feasibility of the anterior mini-invasive approach of 15 mm in a clinical series of 144 cases of distal radius fracture. All patients were operated under regional anesthesia using the same techniques by five surgeons of the same team. According to the AO classification, there were 83 type A fractures, 2 type B, and 59 type C. A volar plate (Step One(®), Newclip Technics™, Haute-Goulaine, France) was used in all cases. The 2 proximal metaphyseal screws and the 2 distal central epiphyseal screws were monoaxial locking. The 2 distal ulnar and radial epiphyseal screws were placed in polyaxial locking at 20° angulation maximum. Skin closure without drainage was performed. No postoperative immobilization was prescribed, and patients were encouraged to use their upper limb immediately postoperative. No postoperative physiotherapy was prescribed. The mean follow-up was 4.1 months. The final size of the incision was on average 16.1 mm. Mean pain score was 1.8. The Quick DASH score was average 25. Average range of motion was more than 85 %, and global force of the hand was 67 % compared with contralateral side. On X-ray, the mean radial slope was 22°, the mean radial tilt was 8.3°, and the mean radioulnar variance/index was -0.4 mm. There were nine cases of CRPS type I, which all resolved. Specific complications included two secondary displacements and nine tenosynovitis cases. No tendon rupture was noted. Two intra-articular distal radioulnar joint screws had to be removed at 3 months. One epiphyseal screw required removal 1 month postoperative due to loosening. There were no intra-articular radiocarpal screws. Distal radius fracture fixation using a mini-invasive approach is a reliable and reproducible procedure with few complications. It allows anatomical reduction in the distal radius fractures including intra-articular ones. It can be associated with arthroscopy, scaphoid screw fixation or even percutaneous pinning. Thus, most traumatic lesions of the wrist bony or soft tissue can be treated through this mini-invasive approach. PMID:24258689

  18. Titanium Plate Fixation for Sternal Dehiscence in Major Cardiac Surgery

    PubMed Central

    Kim, Wan Kee; Kim, Gwan Sic; Jung, Sung-Ho; Choo, Suk Jung; Chung, Cheol Hyun; Lee, Jae Won

    2013-01-01

    Background Sternal dehiscence is one of the most troublesome complications following cardiac surgery. Treatment failure and consequent lethal outcomes are very common. The aim of this study was to evaluate titanium plate fixation as a treatment for sternal dehiscence following major cardiac surgery. Materials and Methods Between 2010 and 2012, 17 patients underwent sternal reconstruction using horizontal titanium plating for the treatment of post-cardiac-surgery sternal dehiscence. The plates were cut and shaped, and then were fixed to corresponding costal segments using 2-3 titanium screws per each side. Results The median age of our patients was 66 years (range, 50 to 78 years) and 9 were female. Indications for sternal reconstruction included aseptic sternal dehiscence in 3 patients and osteomyelitis in 14 patients including 6 patients who were diagnosed with mediastinitis. During the operation, sternal resection and autologous flap interposition were combined in 11 patients. One patient died due to sepsis. Two patients required additional soft tissue wound revisions. Another patient presented with a tuberculous wound infection which was resolved using anti-tuberculosis medications. The postoperative course was uncomplicated in the other 13 patients. Conclusion Titanium plate fixation that combines appropriate debridement and flap interposition is very effective for the treatment of sternal dehiscence following major cardiac surgery. PMID:24003409

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

    PubMed

    Bartoní?ek, Jan; Rammelt, Stefan

    2014-11-01

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

  20. Dual load path ball screw with rod end swivel

    NASA Technical Reports Server (NTRS)

    Wngett, Paul (Inventor)

    2002-01-01

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

  1. Unilateral versus bilateral pedicle screw instrumentation for single-level minimally invasive transforaminal lumbar interbody fusion.

    PubMed

    Shen, Xiaolong; Zhang, Hailong; Gu, Xin; Gu, Guangfei; Zhou, Xu; He, Shisheng

    2014-09-01

    Minimally invasive transforaminal lumbar interbody fusion (MIS TLIF) has become an increasingly popular method of lumbar arthrodesis. However, there are few published studies comparing the clinical outcomes between unilateral and bilateral instrumented MIS TLIF. Sixty-five patients with degenerative lumbar spine disease were enrolled in this study. Thirty-one patients were randomized to the unilateral group and 34 to the bilateral group. Recorded demographic data included sex, age, preoperative diagnosis, and degenerated segment. Operative time, blood loss, hospital stay length, complication rates, and fusion rates were also evaluated. The Oswestry Disability Index (ODI) score and Visual Analog Scale (VAS) pain score data were obtained. All patients were asked to follow-up at 3 and 6 months after surgery, and once every 6 months thereafter. The mean follow-up was 26.6 months (range 18-36 months). The two groups were similar in sex, age, preoperative diagnosis, and operated level. The unilateral group had significantly shorter operative time, lower blood loss, and shorter hospital time than the bilateral group. The average postoperative ODI and VAS scores improved significantly in each group. No significant differences were found between the two groups in relation to ODI and VAS. All patients showed evidence of fusion at 12 months postoperatively. The total fusion rate, screw failure, and general complication rate were not significantly different. Results showed that single-level MIS TLIF with unilateral pedicle screw fixation would be sufficient in the management of preoperatively stable patients with lumbar degenerative disease. It seems that MIS TLIF with unilateral pedicle screw instrumentation is a better choice for single-level degenerative lumbar spine disease. PMID:24814852

  2. [3-dimensional movement analysis after internal fixation of pelvic ring fractures. A computer simulation].

    PubMed

    Culemann, U; Pohlemann, T; Hüfner, T; Gänsslen, A

    2000-11-01

    Several studies exist describing the biomechanical behavior of several external or internal fixation techniques of the posterior and anterior pelvic ring. Recently, the traditional models using isolated anatomical sections or fixed pelvic ring specimens for evaluation of linear or two-dimensional data have been replaced by three-dimensional measurement systems and simulations of muscle forces. These studies have contributed important information to the understanding of the biomechanics of the intact and injured pelvic ring, however, a consequent movement analysis is still missing. In the present study, 3-D data acquired during several series of testing implants for stabilization of the posterior pelvic ring (sacrum: sacral bars, sacral plates, transiliosacral lag screws; Sl joint: anterior plates, transiliosacral lag screws), using a complete pelvic ring model with single leg stance and static abductor muscle simulation, were converted into a commercially available 3-D animation package. By use of simple graphical representation of anatomical elements of the posterior pelvic ring, reproducible and reliable movement patterns for different types of stabilization could be identified, which demonstrated potential "weakness" of the fixation before failure occurred. These movements were analyzed by "replay functions" and were comparable to observations during the original experiment. The following movements were observed. Sacral fracture, transforaminal: (1) rotation of the transiliosacral lag screws around its axis, even with a second screw into S1; (2) Sacral bars: shearing with compression of the cranial-posterior fracture zone; (3) Sacral plates: minimal translation in the proximal fracture zone and distraction in the distal fracture line, effectively compensated by an additional plate at the S3 level. Sl joint disruption: (1) anterior plating (two plates), minimal translation in the plane of the Sl joint; (2) transiliosacral lag screws, rotational movement around the axis of the screws with only minimal movement at the S1 level. The provided information confirmed the observations and allowed a more detailed and comfortable examination of movement patterns. A better understanding of potential "failure zones" might be useful to optimize the dimensions, design, and the positioning of implants for the pelvic girdle. For further studies, more complex computer models including finite element technology might be useful to add accessory information and could result in a decreased need of living specimen testing. PMID:11142886

  3. Endovascular treatment of isolated iliac artery aneurysms with anaconda stent graft limb.

    PubMed

    Karathanos, Christos; Kaperonis, Elias; Xanthopoulos, Dimitrios; Konstantopoulos, Theophanis; Exarchou, Maria; Loupou, Caterini; Papavassiliou, Vassilios

    2013-01-01

    Isolated aneurysms of the iliac arteries are relatively rare conditions that traditionally have been treated by surgical reconstruction. We report our experience with endovascular treatment of iliac artery aneurysms (IAAs) with Anaconda stent graft limb. Two male patients were found to have 4.5 and 3.6?cm isolated common IAAs, respectively. The endograft was successfully advanced and deployed precisely to the intended position in both cases. In one case the internal iliac artery was embolized. No type I or II endoleak was observed immediately after the procedure. In one patient postimplantation fever (>38°C) and gluteal claudication occurred. After 2?years followup both iliac endovascular stent grafts are patent and without endoleak. Endovascular treatment with Anaconda limb stent graft seems to be a safe and feasible alternative to open surgery. PMID:23862094

  4. External iliac vein – transplant ureteral fistula combined with renal cell carcinoma: an unusual case of hematuria

    PubMed Central

    Luo, Jin-dan; Liu, Ben; Wang, Ping; Zhou, Feng; Xu, Xiang-lai; Li, Shi-qi; Cai, Song-liang; Wang, Yi-min

    2014-01-01

    Iliac vein-ureteral fistula is a rare cause of hematuria. The diagnosis of an iliac vein-ureteral fistula can be elusive even with the use of multiple methods. With regards to the treatment, there appears to be a shift in management from primarily open surgical to primarily angiographic management. We present a unique case of an external iliac vein – transplant ureteral fistula. A 48 year-old female complained of recurrent gross hematuria. She underwent transplant nephrectomy and radical left nephrectomy because of rejection of transplanted kidney and cystic renal cell carcinoma when the hematuria arose for the first time. Ten months later, the hematuria recurred again, and cystoscopy showed bleeding from the right transplant ureteral orifice. Open exploration confirmed the diagnosis of external iliac vein – transplant ureteral fistula. Diagnostic difficulties and treatment dilemma of such a rare cause of hematuria are also discussed. PMID:25092990

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

    SciTech Connect

    Beese, Richard C. [St. George's Hospital, Department of Radiology (United Kingdom); Tomlinson, Mark A. [St. George's Hospital, Department of Vascular Surgery (United Kingdom); Buckenham, Timothy M. [St. George's Hospital, Department of Radiology (United Kingdom)

    2000-05-15

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

  6. Endofibrosis of Iliac Arteries in High-Performance Athletes: Diagnostic Approach and Minimally Invasive Endovascular Treatment

    SciTech Connect

    Giannoukas, Athanasios D., E-mail: agiannoukas@hotmail.com; Berczi, Viktor; Anoop, Unnikrishnan; Cleveland, Trevor J.; Beard, Jonathan D.; Gaines, Peter A. [Northern General Hospital, Sheffield Vascular Institute (United Kingdom)

    2006-10-15

    The aim of this article is to report our experience in the diagnosis of two cases of iliac artery endofibrosis or arteriopathy, a rare entity occurring in high-performance athletes, presenting with intermittent claudication (right-sided in both) after maximal exercise. External iliac artery endofibrosis or arteriopathy is a likely diagnosis in competitive athletes free of cardiovascular risk factors who present with leg claudication. Arteriography and a papaverine-assisted mean pressure gradient across the iliac arteries of more than 10 mmHg is a useful diagnostic approach. Moreover, balloon angioplasty of the iliac artery in that patient, in whom a pressure gradient was detected, resulted in symptomatic relief for 2 months followed by mild symptom recurrence. Thus, although balloon angioplasty is feasible and safe, it might not be adequate to treat this entity and, thus, its value remains undefined.

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

    SciTech Connect

    Chowdhury, M. M., E-mail: moti3773@yahoo.i [Stoke Mandeville Hospital, Department of Radiology (United Kingdom); Northeast, A.; Lintott, P. [Stoke Mandeville Hospital, Department of Surgery (United Kingdom); Liong, W.-C.; Warakaulle, D. R., E-mail: dinuke.warakaulle@buckshosp.nhs.u [Stoke Mandeville Hospital, Department of Radiology (United Kingdom)

    2010-10-15

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

  8. A minimally invasive posterior lumbar interbody fusion using percutaneous long arm pedicle screw system for degenerative lumbar disease

    PubMed Central

    He, Er-Xing; Cui, Ji-Hao; Yin, Zhi-Xun; Li, Chuang; Tang, Cheng; He, Yi-Qian; Liu, Cheng-Wei

    2014-01-01

    The aim of this study is to evaluate the therapeutic efficacy of patients with lumbar degeneration and instability treated with percutaneous pedicle screw fixation and minimally invasive lumbar interbody fusion. Twenty-one patients were selected in our hospital from November, 2012 to March, 2013. The patients with an average age 55.62 years, including 8 vertebral spondylolisthesis, 4 lumbar intervertebral disc herniation, and 9 lumbar spinal canal stenosis cases. All the patients were managed to take the lumbar MRI and radiographs. The comparison of preoperative and postoperative (3 days, 2 weeks, 3 months) VAS and ODI score were analyzed. The results indicated that VAS scores were 7.14 ± 0.79 before operation, and 5.19 ± 0.81 in 3 days after operation, 4 ± 0.84 after 2 weeks, and 2.67 ± 0.66 after 3 months. The pain was relieved, and the postoperative VAS score was lower than that before treatment (P < 0.05). ODI score was 55.8 ± 11.4 before operation, 47.38 ± 9.38 after 3 days, 41.38 ± 8.09 after 2 weeks, 35.76 ± 4.50 after 3 months. ODI score was obviously decreased (P < 0.05). In conclusion, percutaneous pedicle screw fixation combined with minimally invasive interbody fusion is a safe, effective, feasible minimally invasive spine operation, with worthy for spreading. PMID:25550904

  9. 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.

  10. Endovascular Treatment of Common Iliac Occlusion in the Presence of Persistent Sciatic Artery

    SciTech Connect

    Mofidi, R., E-mail: rmofidi@doctors.net.uk; Macaskill, E. J.; Griffiths, G. D.; Chakraverty, S. [Ninewells Hospital, Department of Vascular Surgery (United Kingdom)

    2008-07-15

    Persistent sciatic artery is a rare congenital anomaly. It is associated with increased incidence of aneurysmal dilatation, thrombosis, distal embolization, and atherosclerotic change. We describe the case of a patient with persistent sciatic artery who presented with a critically ischemic left leg as a result of an occluded left common iliac artery, which was treated by angioplasty and stenting, and discuss the endovascular iliac recanalization in the presence of a persistent sciatic artery.

  11. Observer Variability of Iliac Artery Measurements in Endovascular Repair of Abdominal Aortic Aneurysms

    Microsoft Academic Search

    Brajesh K. Lal; Joaquim J. Cerveira; Craig Seidman; Paul B. Haser; Richard Kubicka; Zafar Jamil; Frank T. Padberg; Robert W. Hobson; Peter J. Pappas

    2004-01-01

    Accurate measurement of iliac arteries is essential for successful delivery of aortic endografts without iliac limb endoleak. Although intravascular ultrasound measurements may be reliable, they require an invasive procedure. Therefore, helical computed tomography (hCT) has become the most commonly used modality for obtaining preprocedure arterial diameter measurements. The accuracy of hCT remains ill-defined, however, because an anatomic gold standard with

  12. Spontaneous Posterior Iliac Crest Regeneration Enabling Second Bone Graft Harvest; A Case Report

    Microsoft Academic Search

    Elias C. Papadopoulos; Patrick F. O’Leary; Ioannis P. Pappou; Federico P. Girardi

    2009-01-01

    We present a case of a revision spinal fusion in which successful bone graft reharvesting was performed from the posterior\\u000a iliac crest 4 years after initial intracortical harvesting. To date, only anterior iliac crest regeneration has been reported\\u000a in orthopedic trauma patients. A 70-year-old man with a history of two prior instrumented lumbar fusion operations developed\\u000a thoracolumbar kyphosis junctional to the

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

    SciTech Connect

    Trehan, Vijay; Nigam, Arima; Ramakrishnan, S. [G. B. Pant Hospital, Department of Cardiology (India)], E-mail: ramakgmc@rediffmail.com

    2007-02-15

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

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

    PubMed

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

    2015-04-01

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

  15. Two load sharing plates fixation in mandibular condylar fractures: biomechanical basis.

    PubMed

    Parascandolo, Salvatore; Spinzia, Alessia; Parascandolo, Stefano; Piombino, Pasquale; Califano, Luigi

    2010-07-01

    Mandibular condylar fractures have a high incidence but there is no consensus regarding the best choice of osteosynthesis. From a review of the literature, it is evident that the technique used most frequently for fixation is the positioning of a single plate despite complications concerning plate fracture or screw loosening have been reported by various authors. Different studies have highlighted that the stability of osteosynthesis is correlated with the mechanical strains occurring in the condylar region, generated by the muscles of mastication. The aim of our study was, through a mandibular finite element model (FEM), to confirm this correlation and to analyse the behaviour of single and double elements of union in the fixation of mandibular subcondylar fractures. We concluded that the use of two plates provides greater stability compared with the single plate, reducing the possibility of displacement of the condylar fragment. Therefore we recommend that this technique should be adopted whenever possible. PMID:19944616

  16. Complex Common and Internal Iliac or Aortoiliac Aneurysms and Current Approach: Individualised Open-Endovascular or Combined Procedures

    PubMed Central

    Kotsis, Thomas; Louizos, Louizos Alexander; Theodoraki, Kassiani

    2014-01-01

    Objective. Bilateral internal iliac artery aneurysms constitute the utmost configuration of infrarenal aortoiliac disease. We detail characteristic aortoiliac disease patterns and reconstructive techniques we have used, along with a visualized decision-making chart and a short review of the literature. Material and Methods. A retrospective, observational study of twelve clinical cases of patients with aortoiliac disease are described. Two patients had a common iliac artery aneurysm and were managed by the application of inversed stent-grafts; another case was repaired by the insertion of a standard bifurcated stent-graft flared in the right common iliac artery and with an iliac branched device in the left iliac arterial axis. Open approach was used in 5 cases and in 4 cases a combination of aortouniliac stent-grafting with femoral-femoral bypass was applied. Results. Technical success was 100%. One endoleak type Ib in a flared iliac limb was observed and corrected by internal iliac embolism and use of an iliac limb stent-graft extension. We report 100% patency rate during 26.3 months of followup. Conclusion. Individualized techniques for the management of isolated iliac or aortoiliac aneurismal desease with special concern in maintaining internal iliac artery perfusion lead to elimination of perioperative complications and long-term durability and patency rates. PMID:25328706

  17. What is the relevance of the tip-apex distance as a predictor of lag screw cut-out?

    PubMed

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

    2013-01-01

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

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

    PubMed Central

    Amaritsakul, Yongyut; Chao, Ching-Kong

    2013-01-01

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

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

    SciTech Connect

    Dalainas, Ilias, E-mail: hdlns@freemail.gr; Nano, Giovanni; Stegher, Silvia; Bianchi, Paolo; Malacrida, Giovanni; Tealdi, Domenico G. [Policlinico San Donato, University of Milan, 1st Unit of Vascular Surgery (Italy)

    2008-03-15

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

  20. [Unilateral triangular lumbopelvic stabilization: indications and techniques].

    PubMed

    Hoffmann, M F; Dudda, M; Schildhauer, T A

    2013-11-01

    Operative fixation has become treatment of choice for unstable sacral fractures. Osteosynthesis for these fractures results in loss of reduction in up to 15%. Vertical sacral fractures involving the S1 facet joint (Isler 2 and 3) may lead to multidirectional instability. Multidirectional instability of the posterior pelvic ring and lumbopelvic junction may be stabilized and forces balanced by a so-called lumbopelvic triangular fixation. Lumbopelvic triangular fixation combines vertical fixation between the lumbar vertebral pedicle and the ilium, with horizontal fixation, as an iliosacral screw or a transiliacal plate osteosynthesis. The iliac screw is directed from the posterior superior iliac spine (PSIS) to the anterior inferior iliac spine (AIIS). Thereby, lumbopelvic fixation decreases the load to the sacrum and SI joint and transfers axial loads from the lumbar spine directly onto the ilium. Triangular lumbopelvic fixation allows early full weight bearing and therefore reduces prolonged immobilization. The placement of iliac screws may be a complex surgical procedure. Thus, the technique requires thorough surgical preparation and operative logistics. Wound-related complications may occur. Preexisting Morell-Lavalée lesions increase the risk for infection. Prominent implants cause local irritation and pain. Hardware prominence and pain are markedly reduced with screw head recession into the PSIS. PMID:24233083

  1. The influence of a suction device on fixation of a cemented cup using RSA.

    PubMed

    Timperley, A John; Whitehouse, Sarah L; Hourigan, Patrick G

    2009-03-01

    The quality of technique used at the time of socket cementation is crucial in ensuring a durable long-term result of the implant. We asked whether a new instrument, an aspirator retractor introduced into the wing of the ilium before socket preparation and cementation, would enhance cement fixation as defined by RSA and radiographic examination. We randomized 38 patients into two groups. The surgical technique was identical between the groups with the exception of the use of the aspirator retractor. Patients were followed clinically and with radiostereometry at a minimum of 2 years. We compared gross radiographic appearances, including the depth of penetration of cement and the incidence of postoperative and 2-year radiolucent lines. There was no difference in proximal migration between the two groups. No improvement of fixation was proven from the measured translations and rotations of the socket in the suction group. We found no difference in the number or extent of radiolucent lines or the depth of cement penetration when the iliac suction device was used in conjunction with contemporary cementing techniques. Although the data suggest no short-term advantage in this small study, we will continue to follow these patients presuming there will be improved outcomes in the longer term and since the device provides an easier method of obtaining adequate fixation, especially if technical difficulties are encountered during the pressurization procedure. PMID:18998193

  2. Femoral Reconstruction Using External Fixation

    PubMed Central

    Palatnik, Yevgeniy; Rozbruch, S. Robert

    2011-01-01

    Background. The use of an external fixator for the purpose of distraction osteogenesis has been applied to a wide range of orthopedic problems caused by such diverse etiologies as congenital disease, metabolic conditions, infections, traumatic injuries, and congenital short stature. The purpose of this study was to analyze our experience of utilizing this method in patients undergoing a variety of orthopedic procedures of the femur. Methods. We retrospectively reviewed our experience of using external fixation for femoral reconstruction. Three subgroups were defined based on the primary reconstruction goal lengthening, deformity correction, and repair of nonunion/bone defect. Factors such as leg length discrepancy (LLD), limb alignment, and external fixation time and complications were evaluated for the entire group and the 3 subgroups. Results. There was substantial improvement in the overall LLD, femoral length discrepancy, and limb alignment as measured by mechanical axis deviation (MAD) and lateral distal femoral angle (LDFA) for the entire group as well as the subgroups. Conclusions. The Ilizarov external fixator allows for decreased surgical exposure and preservation of blood supply to bone, avoidance of bone grafting and internal fixation, and simultaneous lengthening and deformity correction, making it a very useful technique for femoral reconstruction. PMID:21991425

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

    PubMed

    Sethi, Anil; Lee, Sandra; Vaidya, Rahul

    2009-03-01

    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

  4. 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

  5. Wet Granulation in a Twin-Screw Extruder: Implications of Screw Design

    E-print Network

    Thompson, Michael

    granulation in twin-screw extrusion machinery is an attractive tech- nology for the continuous processing negative) reasons for adopting continuous processes in pharmaceutical produc- tion and pointed to extrusion known continuous tech- niques for granulation, a learning curve should be expected as more extrusion

  6. Cerclage wiring in internal fixation of acetabular fractures.

    PubMed

    Schopfer, A; Willett, K; Powell, J; Tile, M

    1993-01-01

    In the last 100 fractures of the acetabulum surgically treated in our institution, cerclage wires have been used as a reduction tool in 14 patients. In each case the fracture pattern affected both columns, and nine of them were approached through a single ilioinguinal exposure. To evaluate our initial experience with the method, these patients were reviewed using medical records, operative notes, and radiological assessment to determine its indications and effectiveness. In each patient, using a limited further dissection, at least one cerclage wire was passed through the greater sciatic notch, embracing the proximal extent of a posterior column fragment. It was then tightened above the anterior-inferior iliac spine, achieving reduction. In 11 cases reduction was obtained to within 1 mm, and joint congruence with < 3 mm of residual displacement was obtained in 13 hips. This reduction was maintained until union, except in one case, where it was lost postsurgery. Cerclage wires may be used to successfully effect an indirect reduction of the posterior column from an anterior approach in fractures affecting both columns, where the posterior column fracture line is proximal. The technique may contribute to fracture stabilization, but supplementary fixation was added in 12 of our patients. PMID:8326428

  7. Outcomes of osteoporotic trochanteric fractures treated with cement-augmented dynamic hip screw

    PubMed Central

    Gupta, Rakesh Kumar; Gupta, Vinay; Gupta, Navdeep

    2012-01-01

    Background: Dynamic hip screw (DHS) has been the standard treatment for stable trochanteric fracture patterns, but complications of lag screw cut out from a superior aspect, due to inadequate bone anchorage, occur frequently in elderly osteoporotic patients. Polymethylmethacrylate (PMMA) has been used as an augmentation tool to facilitate fixation stability in cadaveric femora for biomechanical studies and in pathological fractures. However, there are very few reports on the utilization of PMMA cement to prevent these complications in fresh intertrochanteric fractures. A prospective study was conducted to evaluate the outcome and efficacy of PMMA augmented DHS in elderly osteoporotic patients with intertrochanteric fractures. Materials and Methods: The study included 64 patients (AO type31-A2.1 in eight, A2.2 in 29, A2.3 in 17 patients, and 31-A3.1 in five, A3.2 in three, and A3.3 in two patients) with an average age of 72 years (60 – 94 years) of which 60 were available for final followup. PMMA augmentation of DHS was performed in all cases by injecting PMMA cement into the femoral head with a custommade gun designed by the authors. The clinical outcome was rated as per the Salvati and Wilson scoring system at the time of final followup of one year. Results were graded as excellent (score > 31), good (score 24 – 31), fair (score 16 – 23), and poor (score < 16). Results: Fracture united in all patients and the average time to union was 13.8 weeks (range 12 – 16 weeks). At an average followup of 18 months (range 12 – 24 months), no incidence of varus collapse or superior screw cut out was observed in any of the patients in spite of weightbearing ambulation from the early postoperative period. There was no incidence of avascular necrosis (AVN) or cement penetration into the joint in our series. Most of the patients were able to regain their prefracture mobility status with a mean hip pain score of 8.6. Conclusion: Cement augmentation of DHS appears to be an effective method of preventing osteoporosis related complications of fracture fixation in the trochanteric fractures. The technique used for cement augmentation in the present study is less likely to cause possible complications of cement augmentation like thermal necrosis, cement penetration into the joint, and AVN hip. PMID:23325965

  8. Gluteal Compartment Syndrome following an Iliac Bone Marrow Aspiration

    PubMed Central

    Vega-Najera, Carlos; Leal-Contreras, Carlos; Leal-Berumen, Irene

    2013-01-01

    The compartment syndrome is a condition characterized by a raised hydraulic pressure within a closed and non expandable anatomical space. It leads to a vascular insufficiency that becomes critical once the vascular flow cannot return the fluids back to the venous system. This causes a potential irreversible damage of the contents of the compartment, especially within the muscle tissues. Gluteal compartment syndrome (GCS) secondary to hematomas is seldom reported. Here we present a case of a 51-year-old patient with history of a non-Hodgkin lymphoma who underwent a bone marrow aspiration from the posterior iliac crest that had excessive bleeding at the puncture zone. The patient complained of increasing pain, tenderness, and buttock swelling. Intraoperative pressure validation of the gluteal compartment was performed, and a GCS was diagnosed. The patient was treated with a gluteal region fasciotomy. The patient recovered from pain and swelling and was discharged shortly after from the hospital. We believe clotting and hematologic disorders are a primary risk factor in patients who require bone marrow aspirations or biopsies. It is important to improve awareness of GCS in order to achieve early diagnosis, avoid complications, and have a better prognosis. PMID:24392235

  9. Molybdenum Trafficking for Nitrogen Fixation

    PubMed Central

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

    2009-01-01

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

  10. Broken nylon iris fixation sutures.

    PubMed

    Cohan, B E; Pearch, A C; Schwartz, S

    1979-12-01

    Broken nylon iris sutures, used to fixate the Worst suture lens, occurred in 41 of a series of 215 eyes, a remarkably high frequency. The estimated average time to break was 27.8 months. Over three fourths of the borken sutures were discovered incidentally on a return visit. Complications related to the broken suture occurred in 21 eyes. The characteristic complication was corneal epithelial edema caused by intermittent touch of the endothelium by the broken suture; spontaneous lens dislocation was infrequent. Light and scanning electron microscopy revealed that biodegradation caused the suture break. Broken iris sutures can be avoided by fixation of the lens with a nonbiodegradable suture. PMID:517621

  11. Accuracy analysis of SCARA industrial robot based on screw theory

    Microsoft Academic Search

    Zhao Liang; Su Meng; Diao Changkun

    2011-01-01

    Based on an analysis of error sources of industrial robots, we build a pose error model of industrial robots with screw theory, which overcomes the defect that the error on the y-axis could not be reflected by the classical D-H parameter method. Given the error sources which influence the end- executor's accuracy, we established a screw representation of the static

  12. Study on the load distribution of ball screws with errors

    Microsoft Academic Search

    Xuesong Mei; Masaomi Tsutsumi; Tao Tao; Nuogang Sun

    2003-01-01

    A model is developed to analyze the load distribution of ball screws with geometry errors. The load distribution of the contact of the balls and grooves is theoretically investigated under various load conditions. The results demonstrate that the negative geometry errors of the ball screw result in the decrease of the load on balls or guiding grooves, and when the

  13. Robust compensation of elastic deformations in ball screw drives

    Microsoft Academic Search

    Amin Kamalzadeh; Daniel J. Gordon; Kaan Erkorkmaz

    2010-01-01

    Elastic deformations occur in ball screw drives typically due to inertial forces, guideway friction, and cutting forces. This results in elongation and compression of the ball screw, which deteriorates the dynamic linear positioning accuracy. Closing the control loop with a linear encoder helps to alleviate this problem to a certain extent. However, linear scales cost significantly more than rotary encoders

  14. FRICTION TORQUE AND EFFICIENCY IN BALL - SCREW SYSTEMS

    Microsoft Academic Search

    George V. Puiu; Dumitru N. Olaru; Vasile Puiu

    Complex relations for the friction torque and efficiency in a ball-screw system has been developed. The relations was adapted for a ball-screw system and influence of the speed and load on total friction torque were investigated. The efficiency of the system was computed and good agreement with the literature results was obtained. Also, a relation for the global friction coefficient

  15. Kinematic optimization of ball-screw transmission mechanisms

    Microsoft Academic Search

    D. Mundo; H. S. Yan

    2007-01-01

    The paper proposes a method for the kinematic optimization of transmission mechanisms, where non-circular (NC) gears are used to perform a mechanical control on the output motion. The investigation presented here deals with the motion control of a ball-screw transmission mechanism. The objective is lowering the peak acceleration value of the screw, by designing a pair of variable radius gears

  16. Correlation between feed velocity and preloading in ball screw drives

    Microsoft Academic Search

    A. Verl; S. Frey

    2010-01-01

    The efficiency and reliability of ball screw feed drives is a mayor issue concerning the productivity of modern machine tools. The preloading of a ball screw thereby determines the dynamical operational behavior as well as the attainable life span. The research results presented in this paper now clearly show that the value of pretension changes depending on the velocity of

  17. Compensation of Axial Vibrations in Ball Screw Drives

    Microsoft Academic Search

    A. Kamalzadeh; K. Erkorkmaz

    2007-01-01

    This paper presents a precision control strategy for ball screw drives. Axial vibrations are modeled and actively compensated in the control law, which enables the realization of high positioning bandwidth. Lead errors, arising from imperfections of the screw, are modeled and removed from the loop by offsetting their effect from the command trajectory and position feedback signals. Effectiveness of the

  18. NCI-Frederick PHL - Fixatives and Solutions

    Cancer.gov

    Services Price List Courier Services & Shipment Procedures Scheduling Contact Information Related Links Establishing an Account PHL Forms PHL Portal Fixatives and Solutions Routine fixatives: 10% Neutral Buffered Formalin (NBF) 37 - 40% Formaldehyde………………………………………1000mL distilled

  19. Twin screw granulation - review of current progress.

    PubMed

    Thompson, M R

    2014-11-17

    Abstract 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

  20. 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

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

    PubMed Central

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

    2014-01-01

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

  2. Advanced Age and Disease Predict Lack of Symptomatic Improvement after Endovascular Iliac Treatment in Male Veterans

    PubMed Central

    Assi, Roland; Brownson, Kirstyn E.; Hall, Michael R.; Kuwahara, Go; Vasilas, Penny; Dardik, Alan

    2015-01-01

    Background: Endovascular angioplasty and stent placement is currently the most frequent treatment for iliac artery occlusive disease. However, despite a successful endovascular procedure, some patients do not experience symptomatic improvement and satisfaction with their care. This study seeks to identify patient-related factors associated with lack of symptomatic improvement after endovascular iliac artery treatment in male veterans. Methods: Retrospective review of patients treated with endovascular methods for iliac artery occlusive disease between January 2008 and July 2012 at VA Connecticut Healthcare System. Symptomatic improvement on the first post-operative visit was evaluated, with bilateral treatments counted separately. Results: Sixty-two patients had 91 iliac arteries treated with angioplasty and stent placement. Forty-seven (52 percent) legs had critical limb ischemia, and 77 (85 percent) had at least two-vessel distal runoff. Angiographic success was 100 percent. Patient-reported symptomatic improvement at the first post-operative visit was 55 percent (50/91). Lack of symptomatic improvement correlated with older age (OR 1.09 [1.03-1.17], p = 0.008), presence of critical limb ischemia (OR 3.03 [1.09-8.65], p = 0.034), and need for additional surgical intervention (OR 5.61 [1.65-17.36], p = 0.006). Survival, primary and secondary patency, and freedom from restenosis were comparable between patients who reported symptomatic improvement and those who did not. Conclusions: Despite angiographically successful revascularization, patients who are older or have critical limb ischemia who are treated with isolated endovascular iliac artery intervention are more likely to require additional interventions and less likely to experience symptomatic improvement. These patients may need more extensive infra-inguinal revascularization than isolated iliac angioplasty and stent placement, despite a preserved ankle-brachial index. Quality of life needs to be measured with formal instruments after iliac artery endovascular treatment, especially to determine long term outcomes. PMID:25745377

  3. The Analysis of Soil Resistance During Screw Displacement Pile Installation

    NASA Astrophysics Data System (ADS)

    Krasinski, Adam

    2015-02-01

    The application of screw displacement piles (SDP) is still increasing due to their high efficiency and many advantages. However, one technological problem is a serious disadvantage of those piles. It relates to the generation of very high soil resistance during screw auger penetration, especially when piles are installed in non-cohesive soils. In many situations this problem causes difficulties in creating piles of designed length and diameter. It is necessary to find a proper method for prediction of soil resistance during screw pile installation. The analysis of screw resistances based on model and field tests is presented in the paper. The investigations were carried out as part of research project, financed by the Polish Ministry of Science and Higher Education. As a result of tests and analyses the empirical method for prediction of rotation resistance (torque) during screw auger penetration in non-cohesive subsoil based on CPT is proposed.

  4. In vivo study of magnesium plate and screw degradation and bone fracture healing.

    PubMed

    Chaya, Amy; Yoshizawa, Sayuri; Verdelis, Kostas; Myers, Nicole; Costello, Bernard J; Chou, Da-Tren; Pal, Siladitya; Maiti, Spandan; Kumta, Prashant N; Sfeir, Charles

    2015-05-01

    Each year, millions of Americans suffer bone fractures, often requiring internal fixation. Current devices, like plates and screws, are made with permanent metals or resorbable polymers. Permanent metals provide strength and biocompatibility, but cause long-term complications and may require removal. Resorbable polymers reduce long-term complications, but are unsuitable for many load-bearing applications. To mitigate complications, degradable magnesium (Mg) alloys are being developed for craniofacial and orthopedic applications. Their combination of strength and degradation make them ideal for bone fixation. Previously, we conducted a pilot study comparing Mg and titanium devices with a rabbit ulna fracture model. We observed Mg device degradation, with uninhibited healing. Interestingly, we observed bone formation around degrading Mg, but not titanium, devices. These results highlighted the potential for these fixation devices. To better assess their efficacy, we conducted a more thorough study assessing 99.9% Mg devices in a similar rabbit ulna fracture model. Device degradation, fracture healing, and bone formation were evaluated using microcomputed tomography, histology and biomechanical tests. We observed device degradation throughout, and calculated a corrosion rate of 0.40±0.04mm/year after 8weeks. In addition, we observed fracture healing by 8weeks, and maturation after 16weeks. In accordance with our pilot study, we observed bone formation surrounding Mg devices, with complete overgrowth by 16weeks. Bend tests revealed no difference in flexural load of healed ulnae with Mg devices compared to intact ulnae. These data suggest that Mg devices provide stabilization to facilitate healing, while degrading and stimulating new bone formation. PMID:25712384

  5. A modified technique for Gore Excluder limb deployment in difficult iliac anatomy during endovascular abdominal aortic aneurysm repair.

    PubMed

    Vourliotakis, George; Katsargyris, ?thanasios; Tielliu, Ignace F J; Zeebregts, Clark J; Verhoeven, Eric L G

    2015-02-01

    Complex iliac anatomy including extreme tortuosity constitutes a relative contraindication for endovascular abdominal aortic aneurysm repair with additional risk of limb-graft occlusion. The Gore Excluder limb-graft is a flexible stent-graft, which adapts easily to iliac tortuosity. Nevertheless, the presence of the stiff guide wire does not always allow for an ideal apposition of the stent graft to the angulated common iliac artery vessel wall. We describe herein a modified technique for Gore Excluder limb-graft deployment with partial removal of the stiff wire in cases with difficult tortuous or narrow iliac arteries during endovascular abdominal aortic aneurysm repair. PMID:24668057

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

    PubMed Central

    Howat, William J.; Wilson, Beverley A.

    2014-01-01

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

  7. Biomechanical analysis of pedicle screw placement: a feasibility study.

    PubMed

    Wagnac, Eric; Michardière, Denis; Garo, Anaïs; Arnoux, Pierre-Jean; Mac-Thiong, Jean-Marc; Aubin, Carl-Eric

    2010-01-01

    In spinal instrumentation surgery, the optimal placement of pedicle screws that takes into account the cortical/cancellous bone quality, geometry and property distribution, and screw design is still undetermined despite several in vitro experiments. The objective of this study was to evaluate the feasibility of using a detailed finite element model (FEM) of an instrumented vertebra to simulate screw axial pull-out and to analyze the bone-screw mechanical interaction. The FEM was built using CT-scan images of the L3 vertebra (0.6mm thick contiguous slices) of a 50th percentile human male volunteer, in order to virtually implant a fully customizable pedicle screw in a straight-forward position. The 753,000 elements model takes into account local cortical bone thickness and integrates advanced material behavior (elasto-plastic) laws that simulate bone failure. Screw axial pull-out was simulated and compared to in vitro experimental data, and the stress distribution at the screw thread-bone interface was analyzed. The simulated screw pull-out force (non-linear response with a failure at 640N) was within the range of experimental data (500-660N). Von Mises stresses in the bony structures were concentrated around the root of each internal thread, with the maximum stress located near the first proximal thread, in the cortical bone of the posterior wall of the pars. This study shows the feasibility and relevance of using a detailed FEM to simulate screw pull-out and to analyze the bone-screw mechanical interaction. PMID:20543418

  8. A Surgical Method for Determining Proper Screw Length in ACDF

    PubMed Central

    Park, Hae-Gi; Kang, Moo-Sung; Kim, Kyung-Hyun; Park, Jeong-Yoon; Kim, Keun-Su

    2014-01-01

    Objective We describe a surgical tool that uses the distractor pin as a reference for determining proper screw length in ACDF. It is critical that screw purchase depth be as deep as possible without violating or penetrating the posterior cortical wall, which ensures strong pull out strength. Methods We enrolled 81 adult patients who underwent ACDF using an anterior cervical plate from 2010 to 2012. Patients were categorized into Groups A (42 patients: retractor pin used as a reference for screw length) and B (39 patients: control group). Intraoperative lateral x-rays were taken after screwing the retractor pin to confirm the approaching vertebral level. The ratio of retractor pin length to body anteroposterior (A-P) diameter was measured as a reference. Proper screw length was determined by comparison to the reference. Results The average distance from screw tip to posterior wall was 3.0±1.4mm in Group A and 4.1±2.3mm in Group B. The ratio of screw length to body sagittal diameter was 86.2±5.7% in Group A and 80.8±9.0% in Group B. Screw length to body sagittal diameter ratios higher than 4/5 occurred in 33 patients (90%) in Group A and 23 patients (59%) in Group B. No cases violated the posterior cortical wall. Conclusion We introduce a useful surgical method for determining proper screw length in ACDF using the ratio of retractor pin length to body A-P diameter as a reference. This method allows for deeper screw purchase depth without violation of the posterior cortical wall. PMID:25346756

  9. Biomechanical evaluation of interfragmentary compression at tibia plateau fractures in vitro using different fixation techniques: a CONSORT-compliant article.

    PubMed

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

    2015-01-01

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

  10. Real-Time Estimation of Ball-Screw Thermal Elongation Based upon Temperature Distribution of Ball-Screw

    Microsoft Academic Search

    Takehiko Kodera; Kazuhiro Yokoyama; Kazuo Miyaguchi; Yutaka Nagai; Takamasa Suzuki; Masami Masuda; Takanori Yazawa

    2004-01-01

    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

  11. A mechanism for the origin of screw dislocation sequences, giant screw dislocations, and polytypism in platelet crystals

    Microsoft Academic Search

    D. Kuhlmann-Wilsdorf; Dhananjai Pandey; P. Krishna

    1980-01-01

    Several workers have observed growth spirals of very large step heights on platelet crystals, sometimes associated with polytypism. These are attributed to spiral growth round a sequence of similar screw dislocations in a close planar array or a single giant screw dislocation. Polytypism can be (but is not necessarily) caused by such giant growth steps. The origin of the dislocations

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

    NASA Technical Reports Server (NTRS)

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

    2004-01-01

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

  13. Arthroscopic Posterior Bone Block Procedure: A New Technique Using Suture Anchor Fixation

    PubMed Central

    Boileau, Pascal; Hardy, Marie-Béatrice; McClelland, Walter B.; Thélu, Charles-Edouard; Schwartz, Daniel G.

    2013-01-01

    We present a novel all-arthroscopic technique of posterior shoulder stabilization that uses suture anchors for both bone block fixation and capsulolabral repair. The bone graft, introduced inside the glenohumeral joint through a cannula, is fixed with 2 suture anchors. The associated posteroinferior capsulolabral repair places the bone block in an extra-articular position. In this article we present the detailed arthroscopic technique performed in a consecutive series of 15 patients and report the early results. We also report the positioning, healing, and remodeling of the bone block using postoperative 3-dimensional computed tomography. The benefits of this new technique are as follows: (1) it is all arthroscopic, preserving the posterior deltoid and posterior rotator cuff muscles; (2) it is accurate, resulting in appropriate bone block positioning; (3) it is efficient, allowing for consistent bone graft healing; (4) it is anatomic, both restoring the glenoid bone stock and repairing the injured posterior labrum; and (5) it is safe, limiting hardware-related complications and eliminating the risk of injury to vital structures associated with drilling or screw insertion from posterior to anterior. We believe that this technique is advantageous because it does not use screws for fixation and may be safer for the patient. PMID:24892011

  14. LCP distal ulna hook plate as alternative fixation for fifth metatarsal base fracture.

    PubMed

    Lee, Sang Ki; Park, Ju Sang; Choy, Won Sik

    2013-08-01

    Intramedullary screw fixation is the most common treatment for fifth metatarsal base fractures. Screw application does not achieve accurate reduction in fracture with small fragments, osteoporotic bone, or Lawrence zone 1 fractures, however. On the basis of similar anatomical architectures between the distal ulna and the fifth metatarsal base, the purpose of this study was to assess the results of a locking compression plate (LCP) distal ulna hook plate in stabilizing displaced zone 1 or 2 fifth metatarsal base fractures. Nineteen patients with Lawrence zone 1 (n = 12) or 2 (n = 7) fractures of the fifth metatarsal base were treated surgically with an LCP distal ulna hook plate. The patients were evaluated clinically and radiographically, and functional outcomes were graded by using the American Orthopaedic Foot and Ankle Society (AOFAS) midfoot scoring system. Radiographic bony union was obtained in all patients, at an average of 7.4 weeks. The mean AOFAS midfoot score improved from 26 (range, 0-45) preoperatively to 94 (range, 72-100) points at the final follow-up. There were three patients with post-traumatic cubometatarsal arthrosis and one patient with sural nerve neuropraxia. In our experience, the distal ulna hook plate achieves a high rate of bony consolidation and anatomically suitable fixation in zone 1 or 2 fifth metatarsal base fractures. We also suggest that the LCP distal ulna hook plate should be considered as an alternative treatment in multifragmentary, osteoporotic, and tuberosity avulsion (zone 1) fifth metatarsal base fractures. PMID:23412193

  15. Methacarn (methanol-Carnoy) fixation

    Microsoft Academic Search

    Holde Puchtler; Faye Sweat Waldrop; Susan N. Meloan; Mary S. Terry; H. M. Conner

    1970-01-01

    According to chemical data, methanol raises the shrinkage temperature of collagen significantly more than ethanol (86° C versus 70° C). Since increase of shrinkage temperature appears desirable in tissues to be embedded in paraffin, methanol was substituted for ethanol in Carnoy's fluid. This methanol-Carnoy mixture is referred to as methacarn solution. The fixation-embedding procedure was similar to that described in

  16. [Risk of Bleeding from the internal Iliac Artery and Its Branches in Pelvic Fractures: Cadaver Study].

    PubMed

    Bá?a, V; Marvanová, Z; Štefela, J; Hašplová, K; Kachlík, D; Džupa, V

    2015-01-01

    PURPOSE OF THE STUDy The study was designed to investigate whether anatomical variations of the anterior and posterior divisions of the internal iliac artery and their branches are associated with different risks of bleeding resulting from injury to the posterior pelvic segment. MATERIAL AND METHODS The study was carried out on 19 cadavers. The dissected area included the internal iliac artery from the common iliac artery bifurcation to the origins of the superior gluteal artery, the inferior gluteal artery and the internal pudendal artery. Using an electronic slide rule, distances between the bifurcation and the origin of each branch from either the anterior or the posterior division were measured. The diameter of each vessel was also determined. Findings of the study were compared with variations described in the literature. The degree of risk for bleeding related to different anatomical variations of the internal iliac artery and its branches was evaluated based on the proximity to the bone. RESULTS There are six anatomical variations of internal iliac artery branches. Four of them were found: type A1 was recorded in 10 specimens, type A2 in six, type B1 in two and type C in one specimen. Types B2 and D were not seen. DISCUSSION The type B2 and C anatomical variations were considered to carry higher risks of bleeding due to injury to the posterior pelvic segment. These variations are characterized by vessels larger in diameter and a longer course of the posterior division along the posterior part of the greater sciatic notch (area often involved in unstable pelvic ring fractures). On the other hand, the type C variation showed a longer internal iliac artery separated from the bone with a thick layer of soft tissue, which suggested lower risk than was attributed to the dominant type A1 variation. It was not possible to evaluate type B2 variation because it is very rare and was not found in study material. In type A2 and B1 variations, the branches were separated from bony structures similarly to the dominant type A1 variation. CONCLUSIONS The cadaver study designed to assess the risk of bleeding associated with different morphological variations of the branching pattern of the internal iliac artery did not identify any anatomical arrangement that might carry a higher risk of injury to the vessels by free bone fragments of the posterior segment in unstable pelvic fractures. It can be concluded that less common branching patterns of the internal iliac artery are not associated with higher risk of bleeding than the dominant type A1 variation. Key words: pelvic injury, risk of arterial bleeding, internal iliac artery and its branches. PMID:25748661

  17. Understanding Nitrogen Fixation

    SciTech Connect

    Paul J. Chirik

    2012-05-25

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

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

    SciTech Connect

    Bharwani, N., E-mail: nishatbharwani@gmail.com; Raja, J. [St George's NHS Trust, Radiology Department (United Kingdom); Choke, E. [St George's Vascular Institute, St George's NHS Trust, Department of Vascular Surgery (United Kingdom); Belli, A. M. [St George's NHS Trust, Radiology Department (United Kingdom); Thompson, M. M. [St George's NHS Trust, Department of Vascular Surgery (United Kingdom); Morgan, R. A.; Munneke, G. [St George's NHS Trust, Radiology Department (United Kingdom)], E-mail: Graham.Munneke@stgeorges.nhs.uk

    2008-05-15

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

  19. The use and efficacy of intra-operative stress tests in supination-external rotation IV ankle fracture fixation.

    PubMed

    Gill, Sarah L; Behman, Amy; Cochrane, Lynda A; Love, Gavin J

    2015-02-01

    This study examines stress radiograph use in SER IV ankle fracture fixation; the efficacy of external rotation (ERST) and lateral hook (LHST) stress tests with incidence of subsequent fixation failure secondary to syndesmotic diastasis. 154 skeletally mature patients were admitted to our unit with ankle fractures in 12 months. 42 non-SER fractures and 32 SER fractures treated without ORIF were excluded, as were 14 which featured a syndesmotic screw in the primary ORIF. The remaining 66 SER IV fixations were included in the final sample (17 men, 49 women; median age 49 years). No stress test was performed in 51.5% of cases without a single subsequent failure in these fixations. ERST was the more commonly performed test (incidence 30.3%); negative predictive value (NPV) 0.95. Incidence of LHST was 18.2%; NPV 0.83. Both tests were performed in 6.1% of cases; NPV 0.75. The incidence of failure secondary to syndesmotic diastasis was 6.1% (4/66). Notably, there were no failures in the cases where no stress test was performed. Use of either or both external rotation and lateral hook stress tests resulted in failures to detect syndesmotic diastasis with consequent failure of fixation. This study suggests that syndesmotic injuries are not missed due to an absence of a stress test but that stress tests are not sufficiently sensitive or correctly interpreted. Clinical judgement in cases where syndesmotic injury is not present appears accurate. If syndesmotic injury is clinically suspected, apply caution and insert a syndesmotic screw rather than relying on stress test results. PMID:24613185

  20. Timing of internal fixation of femoral neck fractures. A systematic review and meta-analysis of the final outcome.

    PubMed

    Papakostidis, Costas; Panagiotopoulos, Andreas; Piccioli, Andrea; Giannoudis, Peter V

    2015-03-01

    The aim of the present study was to evaluate the effect of timing of internal fixation of intracapsular fractures of the neck of femur on the development of late complications, particularly osteonecrosis of femoral head (ONFH) and non-union. We undertook a systematic review of the literature adhering to the PRISMA guidelines. There were 7 eligible reports for the final analysis. The methodological quality of component studies was assessed with the Coleman Methodology Score (CMS). Each included study was assigned a score independently by the two reviewers. The final score of each individual study constituted the average value of the scores given by the two reviewers. The agreement between the two assessors was tested with intraclass correlation coefficient (ICC). The CMS ranged from 37 to 64 within component studies (mean: 46.5, SD: 10.8, median: 41). The ICC was 0.94 (95% CI: 0.69-0.99), implying a nearly perfect agreement between the two assessors. Based on the available data regarding the timing of operative fixation of the femoral neck fractures, 4 discreet pairs of comparison groups could be created: (1) fractures fixed within 6h from injury versus fractures fixed after 6h from injury; (2) fractures fixed within 12h versus after 12h; (3) fractures fixed within 24h versus after 24h; and (4) fractures fixed within 6h versus after 24h. Outcome measures were analyzed within each one of the above pairs of treatment groups. The following subgroups analyses were a priori decided: (1) initial fracture displacement (displaced vs. undisplaced fractures); (2) fixation method (cannulated screws vs. sliding hip screw); (3) quality of reduction (anatomic vs non-anatomic reduction). This study failed to prove any essential association between timing of NOF fracture internal fixation and incidence of AVN. With respect to non-union though, it indicated that delay of internal fixation of more than 24h could increase substantially the odds of non-union. PMID:25616675

  1. 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

  2. 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.

  3. 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.

  4. 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.

  5. Salvaging the Pullout Strength of Stripped Screws in Osteoporotic Bone

    PubMed Central

    Pechon, Pierre H. M.; Mears, Simon C.; Langdale, Evan R.; Belkoff, Stephen M.

    2013-01-01

    Our goal was to determine whether the pullout strength of stripped screw holes in osteoporotic bone could be increased with readily available materials from the operating room. We inserted 3.5-mm stainless steel nonlocking self-tapping cortical screws bicortically into 5 osteoporotic humeri. Each screw was first stripped by rotating it 1 full turn past maximum torque. In the control group, the screw was pulled out using an MTS machine (858; MTS Inc, Eden Prairie, Minnesota). In the treatment groups, the screw was removed, the hole was augmented with 1 of the 3 materials (stainless steel wire, polysorb suture, or polyethylene terephthalate glycol plastic sheet), and the screws were replaced and then pulled out. The effect of material on pullout strength was checked for significance (P < .05) using a general linearized latent and mixed model (Stata10; StataCorp, College Station, Texas). The mean (95% confidence interval) pullout strength for the unaugmented hole was 138 N (range 88-189), whereas the holes augmented with plastic, suture, or wire had mean pullout strengths of 255 N (range 177-333), 228 N (range 149-308), and 396 N (range 244-548), respectively. Although wire augmentation resulted in pullout strength that was significantly greater than that of the unaugmented screw, it was still below that of the intact construct. PMID:24093076

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

    PubMed

    Canpolat, Ceyhun; Ozkurt-Kayahan, Zeynep; Kazazo?lu, 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. PMID:24393481

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

    PubMed Central

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

    2013-01-01

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

  8. Outcome of double bundle anterior cruciate ligament reconstruction using crosspin and aperture fixation

    PubMed Central

    Joshi, Deepak; Jain, Vineet; Goyal, Ankit; Bahl, Vibhu; Modi, Prashant; Chaudhary, Deepak

    2014-01-01

    Background: Double bundle anterior cruciate ligament (DBACL) reconstruction is said to reproduce the native anterior cruciate ligament (ACL) anatomy better than single bundle anterior cruciate ligament, whether it leads to better functional results is debatable. Different fixation methods have been used for DBACL reconstruction, the most common being aperture fixation on tibial side and cortical suspensory fixation on the femoral side. We present the results of DBACL reconstruction technique, wherein on the femoral side anteromedial (AM) bundle is fixed with a crosspin and aperture fixation was done for the posterolateral (PL) bundle. Materials and Methods: Out of 157 isolated ACL injury patients who underwent ACL reconstruction, 100 were included in the prospective study. Arthroscopic DBACL reconstruction was done using ipsilateral hamstring autograft. AM bundle was fixed using Transfix (Arthrex, Naples, FL, USA) on the femoral side and bio interference screw (Arthrex, Naples, FL, USA) on the tibial side. PL bundle was fixed on femoral as well as on tibial side with a biointerference screw. Patients were evaluated using KT-1000 arthrometer, Lysholm score, International Knee Documentation Committee (IKDC) Score and isokinetic muscle strength testing. Methods: Out of 157 isolated ACL injury patients who underwent ACL reconstruction, 100 were included in the prospective study. Arthroscopic DBACL reconstruction was done using ipsilateral hamstring autograft. AM bundle was fixed using Transfix (Arthrex, Naples, FL, USA) on the femoral side and bio interference screw (Arthrex, Naples, FL, USA) on the tibial side. PL bundle was fixed on femoral as well as on tibial side with a biointerference screw. Patients were evaluated using KT-1000 arthrometer, Lysholm score, International Knee Documentation Committee (IKDC) Score and isokinetic muscle strength testing. Results: The KT-1000 results were evaluated using paired t test with the P value set at 0.001. At the end of 1 year, the anteroposterior side to side translation difference (KT-1000 manual maximum) showed mean improvement from 5.1 mm ± 1.5 preoperatively to 1.6 mm ± 1.2 (P < 0.001) postoperatively. The Lysholm score too showed statistically significant (P < 0.001) improvement from 52.4 ± 15.2 (range: 32-76) preoperatively to a postoperative score of 89.1 ± 3.2 (range 67-100). According to the IKDC score 90% patients had normal results (Category A and B). The AM femoral tunnel initial posterior blow out was seen in 4 patients and confluence in the intraarticular part of the femoral tunnels was seen in 6 patients intraoperatively. The quadriceps strength on isokinetic testing had an average deficit of 10.3% while the hamstrings had a 5.2% deficit at the end of 1 year as compared with the normal side. Conclusion: Our study revealed that the DBACL reconstruction using crosspin fixation for AM bundle and aperture fixation for PL bundle on the femoral side resulted in significant improvement in KT 1000, Lysholm and IKDC scores. PMID:24600062

  9. [Uretero-external iliac artery fistula with longterm indwelling of ureteral stent].

    PubMed

    Hashimoto, Mamoru; Shimizu, Nobutaka; Toyoda, Shingo; Saito, Yoshitaka; Yamamoto, Yutaka; Minami, Takafumi; Hayashi, Taiji; Tsuji, Hidenori; Nozawa, Masahiro; Yoshimura, Kazuhiro; Ishii, Tokumi; Uemura, Hirotsugu

    2014-06-01

    We report a case of a patient with a fistula between the right ureter and external iliac artery. The patient was a 75-year-old woman who had undergone abdominal radical hysterectomy for uterine cancer, and whole pelvis radiotherapy for right external iliac lymph node metastasis. Her post-operative course was complicated by hydronephrosis of the right kidney, which was treated by the insertion of a double-J stent. While removing the frequently obstructed double-J stent after percutaneous nephrostomy, arterial hemorrhage occurred from the external urethral meatus. Computed tomographic scan demonstrated right ureteral external iliac artery fistula formation located adjacent to the pseudoaneurysm. The patient was treated successfully with endovascular stent grafting and has showed no episode of hematuria since then. PMID:25001641

  10. [Cockett's syndrome, May-Thurner syndrome, or iliac vein compression syndrome].

    PubMed

    Gil Martín, A R; Carreras Aja, M; Arrieta Ardieta, I; Labayen Azparren, I

    2014-01-01

    Iliac vein compression syndrome (also known as May-Thurner syndrome or Cockett's syndrome) is a rare clinical entity in which the left common iliac vein is compressed when it passes between the right common iliac artery and the spine. The sustained compression and trauma caused by the pulsatile force of the artery on the vein damage the intima and lead to the formation of membranes or bands in the vascular lumen that hinder or obstruct the flow of blood in the vein, favoring thrombus formation. The current treatment strategy of choice is endovascular vein patch angioplasty and stenting with the aim of improving the caliber of the lumen and enabling normal venous drainage. We present two cases of May-Thurner syndrome and review the clinical and CT findings. PMID:22621823

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

    SciTech Connect

    Tsetis, Dimitrios [University Hospital of Heraklion, Medical School of Crete, Department of Radiology (Greece)], E-mail: tsetis@med.uoc.gr; Uberoi, Raman [John Radcliffe Hospital, Department of Radiology (United Kingdom)

    2008-03-15

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

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

    SciTech Connect

    Mofidi, R., E-mail: rmofidi@doctors.net.uk; Bhat, R.; Nagy, J.; Griffiths, G. D.; Chakraverty, S. [Ninewells Hospital, Department of Vascular Surgery and Radiology (United Kingdom)

    2007-09-15

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

  13. Tightening force and torque of nonlocking screws in a reverse shoulder prosthesis A. Terrier a,

    E-print Network

    Guerraoui, Rachid

    Tightening force and torque of nonlocking screws in a reverse shoulder prosthesis A. Terrier a, , S Arthroplasty Reversed prosthesis Screw Cadaveric study Background: Reversed shoulder arthroplasty and screwing angle, of the nonlocking screws of the Aquealis reversed prosthesis. In addition, the amount

  14. The Development of using the digital projection method to measure the contact angle of ball screw

    Microsoft Academic Search

    Chun-Jen Chen; Wenyuh Jywe; Yu-Chun Liu; Hsin-Hong Jwo

    2011-01-01

    The ball screw frequently used to drive or translate the parts on the precision machine, such as machine tool and motorized stage. Therefore they were most frequently used on the precision machine, semiconductor equipment, medical instrument and aero industry. The main parts of ball screw are screw, ball and nut. The contact angle between the screw, ball and nut will

  15. Moving follower rest design using vibration absorbers for ball screw grinding

    Microsoft Academic Search

    C. C. Cheng; C. P. Kuo; F. C. Wang; W. N. Cheng

    2009-01-01

    A novel design of follower rest used in ball screw grinding machine is proposed. Installed on the grinding wheel holder and moving along the ball screw, the follower rest is designed to be a vibration absorber with its driving point attached on the ball screw close to the grinding zone. It is used not only to suppress the ball screw

  16. Analysis of Material Flow in Screw Extrusion of Aluminum

    SciTech Connect

    Haugen, Bjoern; Oernskar, Magnus; Welo, Torgeir; Wideroee, Fredrik [Department of Engineering Design and Materials, NTNU (Norway)

    2010-06-15

    Screw extrusion of aluminum is a new process for production of aluminum profiles. The commercial potential could be large. Little experimental and numerical work has been done with respect to this process.The material flow of hot aluminum in a screw extruder has been analyzed using finite element formulations for the non-Newtonian Navier-Stokes equations. Aluminum material properties are modeled using the Zener-Holloman material model. Effects of stick-slip conditions are investigated with respect to pressure build up and mixing quality of the extrusion process.The numerical results are compared with physical experiments using an experimental screw extruder.

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

    NASA Astrophysics Data System (ADS)

    Myshlyaev, M. M.

    2012-03-01

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

  18. Effects of Estradiol on Transcriptional Profiles in Atherosclerotic Iliac Arteries in Ovariectomized Cynomolgus Macaques

    PubMed Central

    Eyster, Kathleen M.; Appt, Susan; Chalpe, Abha; Mark-Kappeler, Connie J.; Register, Thomas C.; Clarkson, Thomas B.

    2013-01-01

    Objective To assess the in vivo effects of estradiol treatment on arterial gene expression in atherosclerotic post-menopausal female monkeys. Methods Eight ovariectomized cynomolgus monkeys were fed atherogenic diets for 6.5 years. The left iliac artery was biopsied before randomization to estradiol (E2, 1 mg/day human equivalent dose, n=4) or vehicle (n=4) groups for 8 months. The right iliac artery was obtained at necropsy. Transcriptional profiles in pretreatment versus posttreatment iliac arteries were compared to assess responses of atherosclerotic arteries to estradiol. Results Iliac artery plaque size did not differ between E2 and placebo groups at baseline or over the treatment period. Nevertheless, estradiol treatment was associated with increased expression of 106 genes and decreased expression of 26 genes in iliac arteries. Estradiol treatment increased expression of extracellular matrix (ECM) genes, including types I and VI collagen (COL1A1, COL6A2) and fibulin-2 (FBLN-2), suggestive of an increase in the proportion or phenotype of smooth muscle or fibroblasts in the lesions. Also increased were components of the insulin-like growth factor (IGF) pathway [IGF-1, IGF binding protein 4 (IGFBP4) and IGFBP5], and the Wnt signaling pathway [secreted frizzled-related protein 2 (SFRP2), SFRP4, low density lipoprotein receptor-related protein 6 (LRP6), and Wnt 1 inducible signaling pathway protein 2 (WISP2)]. Conclusions Estradiol treatment of monkeys with established atherosclerosis resulted in effects on iliac artery gene expression that suggested changes in the cellular composition of the lesions. Moreover, it is likely that the presence of atherosclerotic plaque affected the gene expression responses of the arteries to estrogen. PMID:23760433

  19. Technique, Complication, and Long-Term Outcome for Endovascular Treatment of Iliac Artery Occlusion

    SciTech Connect

    Ozkan, Ugur, E-mail: radugur@yahoo.com; Oguzkurt, Levent; Tercan, Fahri [Baskent University, Department of Radiology, Faculty of Medicine (Turkey)

    2010-02-15

    The aim of this study was to report technical details, procedure-related complications, and results of endovascular treatment in chronic iliac artery occlusion. Between 2001 and 2008, endovascular treatments of 127 chronic iliac artery occlusions in 118 patients (8 women and 110 men; mean age, 59 years) were retrospectively reviewed. The study was based on Ad Hoc Committee on Reporting Standards (Society for Vascular Surgery/International Society for Cardiovascular Surgery Standards). All occlusions were treated with stent placement with or without preliminary balloon angioplasty. Kaplan-Meier estimators were used to determine patency rates. Univariate and multivariate analyses were performed to determine variables affecting successful recanalization, major complications, early stent thrombosis ({<=}30 days), and primary and secondary patency rates. Initial technical success was achieved in 117 (92%) procedures. Successful recanalization was obtained by antegrade approach in 69 of 77 (90%) procedures and by retrograde approach in 52 of 105 (50%) procedures (p < 0.001). Complications were encountered in 28 (24%) patients [minor in 7 patients (6%) and major in 22 patients (19%)]. One death occurred in the operative period secondary to iliac artery rupture. Early stent thrombosis was seen in eight (7%) patients. Presence of critical limb ischemia (p = 0.03), subintimal recanalization (p = 0.03), and major complication (p = 0.02) were the independent predictors of early stent thrombosis on multivariate analysis. Primary and secondary patency rates at 5 years were 63 and 93%, respectively. Presence of critical limb ischemia, TASC type C iliac lesions, combined occlusions of both common and external iliac arteries, and major complications were associated with decreased patency rates on univariate analysis, whereas these factors were not independent predictors of stent patency on multivariate analysis. In conclusion, endovascular treatment of iliac artery occlusion has a high technical success rate with favorable long-term patency rate. Success of recanalization increases with use of the antegrade approach and with the presence of a stump of artery before the occlusion.

  20. Clinical application of a new plate fixation system in open-door laminoplasty.

    PubMed

    Jiang, Liangjun; Chen, Weishan; Chen, Qixin; Xu, Kan; Wu, Qionghua; Li, Fangcai

    2012-02-01

    The purpose of this retrospective clinical series was to evaluate the benefits and complications of plate fixation for open-door laminoplasty in cervical spondylotic myelopathy with multilevel spinal stenosis compared with open-door laminoplasty without fixation. Forty-nine patients underwent open-door laminoplasty for cervical myelopathy with multilevel spinal stenosis with at least 13 months of follow-up. A plate was used as the sole method of fixation between the lateral mass and lamina with 3 screws. Computed tomography scans obtained pre- and postoperatively were assessed for plate complications and spinal canal enlargement. Pre- and postoperative neurological condition was assessed by the Japanese Orthopedic Association (JOA) myelopathy score. Overall cervical spine range of motion (ROM) was measured in full flexion and extension radiographs pre- and postoperatively. No restenosis due to door reclosure was noted, and no plates failed. No screws were backed out or broken. Almost all patients showed neurological improvement. The JOA score increased by 3.9±0.7 points in the suture group and 4.3±0.8 points in the plate group (P>.05). The postoperative increase in mean anteroposterior diameter of the spinal canal from C3 to C7 was 4.5±0.6 mm in the suture group and 5.1±0.5 mm in the plate group. The greater mean anteroposterior diameter increase in the plate group was statistically significant (P<.01). The mean cervical ROM decreased in the plate and suture groups postoperatively (P<.001). No significant difference was found in mean cervical ROM reduction between the groups (P>.05). No difference in axial symptoms was found between the 2 groups. PMID:22310411

  1. The effect of high temperature intraoperative molding on bioabsorbable PLLA-PGA craniofacial fixation.

    PubMed

    Pietrzak, William S; Eppley, Barry L

    2006-09-01

    Bioabsorbable internal fixation has become an established part of the surgeons' armamentarium. There are several unique aspects of bioabsorbable polymers that can enhance their versatility. One of these is the application of heat to adapt the implant. Hot-tip cautery has been used for years to cut and otherwise customize bioabsorbable implants intraoperatively. As the tips of these devices can reach temperatures of over 1,000 degrees C, there is the potential that such practice can modify the degradation properties of these polymers. This study was performed to better understand the extent to which this potential exists. Screw heads of an 82:18 poly-L-lactic acid and poly-glycolic acid copolymer were modified by repeated passage of a hot-tip cautery wire, deforming the hex geometry to that of a ball. There was no significant difference between the glass transition temperature (approximately 59 degrees C) and inherent viscosity (approximately 1.45 dL/g) of treated and untreated screw heads, indicating no overall change in these properties throughout the mass of the screw head. Additionally, these properties were measured and comparisons made between the treated screw heads and untreated plates made of the same polymer during 28-day exposure to an in vitro bath (pH 7.4, 37 degrees C). The glass transition temperature and inherent viscosity exhibited declines during this period, with no significant differences between the two groups. Collectively, these results suggest that hot-tip cautery results in no substantial changes in the degradation characteristics of this polymer. PMID:17003621

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

    SciTech Connect

    Uberoi, Raman, E-mail: raman.uberoi@orh.nhs.uk [John Radcliffe Hospital, Department of Interventional Radiology (United Kingdom); Tsetis, Dimitrios [University Hospital of Heraklion, Medical School of Crete, Department of Radiology (Greece); Shrivastava, Vivek [John Radcliffe Hospital, Department of Interventional Radiology (United Kingdom); Morgan, Robert; Belli, Anna-Maria [St. George's Hospital, Department of Interventional Radiology (United Kingdom)

    2011-02-15

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

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

    SciTech Connect

    Kwon, Joon Ho; Kim, Man Deuk, E-mail: mdkim@yuhs.ac; Lee, Kwang-hun; Lee, Myungsu; Lee, Mu Sook; Won, Jong Yun; Park, Sung Il; Lee, Do Yun [Yonsei University College of Medicine, Department of Radiology, Research Institute of Radiological Science, Severance Hospital (Korea, Republic of)] [Yonsei University College of Medicine, Department of Radiology, Research Institute of Radiological Science, Severance Hospital (Korea, Republic of)

    2013-02-15

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

  4. Percutaneous retrieval of a partially expanded iliac artery stent: case report.

    PubMed

    Davies, R P; Voyvodic, F

    1992-01-01

    A partially expanded, intraluminal, balloon-expandable Palmaz vascular stent was retrieved percutaneously in a 48-year-old woman after attempted placement across a common iliac artery stenosis. A pinhole in the balloon prevented expansion, and the stent could not be stabilized to allow balloon exchange. The stent was snared by a 5Fr 4 mm balloon catheter replaced coaxially through the stent and then withdrawn into a 14Fr Amplatz sheath which had been percutaneously placed in the external iliac artery. Open surgical removal of the stent was thus avoided. PMID:1571924

  5. The Classic: The Iliac Apophysis: An Invaluable Sign in the Management of Scoliosis

    PubMed Central

    2009-01-01

    This Classic article is a reprint of the original work by Joseph C. Risser, The Iliac Apophysis: An Invaluable Sign in the Management of Scoliosis. An accompanying biographical sketch of Joseph C. Risser, MD is available at DOI 10.1007/s11999-009-1095-0. The Classic Article is ©1958 by Lippincott Williams & Wilkins and is reprinted with permission from Risser JC. The iliac apophysis: an invaluable sign in the management of scoliosis. Clin Orthop Relat Res. 1958;11:111–119.

  6. A rare cause of massive haematuria: Internal iliac artery-ureteric fistula.

    PubMed

    Rao, Ahsan M; Khalil, Ahmed; Suttie, Stuart

    2015-04-01

    Ureteric fistula into the arterial tree is a well-recognised, but uncommon condition. The involvement of internal iliac artery is rare. We present a rare case of fistulous communication and subsequent infection of an internal iliac artery aneurysm and ureter secondary to insertion of ureteric stent following endovascular exclusion of the aneurysm and its management. Nephrostogram identified the fistula not seen on computerised tomography. This case highlights the awareness of such pathology allowing for prompt recognition of the condition and importance of appropriate imaging. PMID:24903530

  7. Mechanical evaluation of cross pins used for femoral fixation of hamstring grafts in ACL reconstructions.

    PubMed

    Bellisari, Gregory E; Kaeding, Christopher C; Litsky, Alan S

    2010-10-01

    The goal of this study was to test the mechanical strength of 4 different cross pins currently available for femoral fixation by loading each cross pin to failure as received and determine the effect of 1 million cycles of fatigue loading. Additionally, the strength of resorbable pins was tested after prolonged exposure to biologic conditions. Six implants each of the Arthrotek LactoSorb (Biomet, Warsaw, Indiana), Mitek RigidFix (DePuy Mitek Inc, Raynham, Massachusetts), Arthrotek Bone Mulch Screw (Biomet), cortical allograft, and control were tested for 3-point failure without prior loading and after cyclic loading between 50 to 200 N at 10 Hz for 1 million cycles. The bioabsorbable pins were placed in sterile water at 37°C and tested after 2, 4, and 6 months for 3-point failure strength. All implants tested without antecedent loading demonstrated adequate strength for initial fixation for hamstring grafts. During fatigue testing, RigidFix implants (n=6) failed at 18,893±8365 cycles (with a central deformation of 0.48±0.11 mm prior to fracture). All of the other implants tested endured 1 million cycles of loading (50-200 N) without fracture or 1.5 mm central deformation. Neither of the bioabsorbable pins demonstrated a significant change in yield strength after prolonged exposure to water. All implants tested demonstrated adequate strength for initial fixation of hamstring grafts. The metal and bone implants far exceed the strength required to sustain mechanical fixation until biological fixation occurs; both polymeric implants demonstrated that they maintained enough mechanical strength to achieve this goal. PMID:20954667

  8. Tibial bone bridge and bone block fixation in double-bundle anterior cruciate ligament reconstruction without hardware: a technical note.

    PubMed

    Siebold, R; Thierjung, H; Cafaltzis, K; Hoeschele, E; Tao, J; Ellert, T

    2008-04-01

    Current techniques for tibial graft fixation in four tunnels double bundle (DB) anterior cruciate ligament (ACL) reconstruction are by means of two interference screws or by extracortical fixation with a variety of different implants. We introduce a new alternative tibial graft fixation technique for four tunnels DB ACL reconstruction without hardware. About 3.5 to 5.5 cm bone cylinder with a diameter of 7 mm is harvested from the anteromedial (and posterolateral) tibial bone tunnel (s) with a core reamer. The anteromedial (AM) and posterolateral (PL) hamstring tendon grafts (or alternatively tendon allografts) are looped over an extracortical femoral fixation device and cut in length according to the total femorotibial bone tunnel length. The distal 3 cm of each, the AM- and PL bundle graft are armed with two strong No. 2 nonresorbable sutures and the four suture ends of each graft are tied to each other over the 2 cm wide cortical bone bridge between the tibial AM and PL bone tunnel. In addition the AM- and/or PL bone block which was harvested at the beginning of the procedure is re-impacted into the two tibial bone tunnels. A dorsal splint is used for the first two postoperative weeks and physiotherapy is started the second postoperative day. The technique is applicable for four tunnels DB ACL reconstruction in patients with good tibial bone quality. The strong fixation technique preserves important tibial bone stock and avoids the use of tibial hardware which knows disadvantages. It does increase tendon to bone contact and tendon-to-bone healing and does reduce implant costs to those of a single bundle (SB) ACL reconstruction. Revision surgery may be facilitated significantly but the technique should not be used when bony defects are present. In case of insufficient bone bridge fixation or bone blocks hardware fixation can be applied as usual. PMID:18066528

  9. DISCOVER: Dutch Iliac Stent trial: COVERed balloon-expandable versus uncovered balloon-expandable stents in the common iliac artery: study protocol for a randomized controlled trial

    PubMed Central

    2012-01-01

    Background Iliac artery atherosclerotic disease may cause intermittent claudication and critical limb ischemia. It can lead to serious complications such as infection, amputation and even death. Revascularization relieves symptoms and prevents these complications. Historically, open surgical repair, in the form of endarterectomy or bypass, was used. Over the last decade, endovascular repair has become the first choice of treatment for iliac arterial occlusive disease. No definitive consensus has emerged about the best endovascular strategy and which type of stent, if any, to use. However, in more advanced disease, that is, long or multiple stenoses or occlusions, literature is most supportive of primary stenting with a balloon-expandable stent in the common iliac artery (Jongkind V et al., J Vasc Surg 52:1376-1383,2010). Recently, a PTFE-covered balloon-expandable stent (Advanta V12, Atrium Medical Inc., Hudson, NH, USA) has been introduced for the iliac artery. Covering stents with PTFE has been shown to lead to less neo-intimal hyperplasia and this might lower restenosis rates (Dolmatch B et al. J Vasc Interv Radiol 18:527-534,2007, Marin ML et al. J Vasc Interv Radiol 7:651-656,1996, Virmani R et al. J Vasc Interv Radiol 10:445-456,1999). However, only one RCT, of mediocre quality has been published on this stent in the common iliac artery (Mwipatayi BP et al. J Vasc Surg 54:1561-1570,2011, Bekken JA et al. J Vasc Surg 55:1545-1546,2012). Our hypothesis is that covered balloon-expandable stents lead to better results when compared to uncovered balloon-expandable stents. Methods/Design This is a prospective, randomized, controlled, double-blind, multi-center trial. The study population consists of human volunteers aged over 18 years, with symptomatic advanced atherosclerotic disease of the common iliac artery, defined as stenoses longer than 3 cm and occlusions. A total of 174 patients will be included. The control group will undergo endovascular dilatation or revascularization of the common iliac artery, followed by placement of one or more uncovered balloon-expandable stents. The study group will undergo the same treatment, however one or more PTFE-covered balloon-expandable stents will be placed. When necessary, the aorta, external iliac artery, common femoral artery, superficial femoral artery and deep femoral artery will be treated, using the standard treatment. The primary endpoint is absence of binary restenosis rate. Secondary endpoints are reocclusion rate, target-lesion revascularization rate, clinical success, procedural success, hemodynamic success, major amputation rate, complication rate and mortality rate. Main study parameters are age, gender, relevant co-morbidity, and several patient, disease and procedure-related parameters. Trial registration Dutch Trial Register, NTR3381. PMID:23164097

  10. 21 CFR 888.3070 - Pedicle screw spinal system.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

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

  11. 21 CFR 888.3070 - Pedicle screw spinal system.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

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

  12. 21 CFR 888.3070 - Pedicle screw spinal system.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

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

  13. 21 CFR 888.3070 - Pedicle screw spinal system.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

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

  14. Wet-gas compression in twin-screw multiphase pumps

    E-print Network

    Chan, Evan

    2009-05-15

    Multiphase pumping with twin-screw pumps is a relatively new technology that has been proven successful in a variety of field applications. By using these pumps to add energy to the combined gas and liquid wellstream with minimal separation...

  15. 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

  16. Crystal geometry of screw dislocation glide in tungsten nanocrystals

    NASA Astrophysics Data System (ADS)

    Sadanov, E. V.

    2015-02-01

    A zigzag pattern of low-temperature dislocation glide occurring in tungsten nanocrystals in the intersecting planes {110} and {211}, which belong to the <111> crystallographic zone, has been revealed using field ion microscopy. It has been shown that cores of 1/2[111] screw dislocations are undissociated within the limits of the resolution of the field ion microscope. It has been found experimentally that surface atoms are displaced into metastable positions in the region of the trace of screw dislocation motion.

  17. Modeling and positioning control of a ball screw driven stage

    Microsoft Academic Search

    M. J. Jang; K. C. Lin; C. L. Chen

    2004-01-01

    The demand for high precision stages has received great attention due to the progress of nanotechnology. In the ball-screw-driven systems, the friction behavior dominates the resulting performance and is usually known as the stick-slip phenomenon. In this paper, friction models are introduced to describe the dynamic behavior of a conventional ball-screw-driven x-y stage. Two sets of controllers corresponding to the

  18. Metatarsal Osteotomy Using Double-Threaded Screws - Biomechanical Analysis

    Microsoft Academic Search

    Anna Ziebowicz; Anita Kajzer; Wojciech Kajzer; Jan Marciniak

    \\u000a The fundamental purpose of this research was to determine the biomechanical characteristics of the first metatarsal bone -\\u000a double-threaded screws system made of stainless steel (Cr-Ni-Mo) and an assessment of its stability. To define the biomechanical\\u000a characteristics of the system, the finite element method and experimental method were applied. Geometric models of metatarsal\\u000a bone and double-threaded screws, were discretized by

  19. On giant screw dislocations in ZnS polytype crystals

    Microsoft Academic Search

    S. Mardix; A. R. Lang; I. Blech

    1971-01-01

    Vapour-grown platelet crystals of ZnS containing long-period polytypes have been found by x-ray topography to contain a single screw dislocation with a very large Burgers vector parallel to the c axis. Individual polytype regions can have highly perfect lattices; the few dislocations observed in them in addition to the giant screw have Burgers vectors in the basal plane. A divergent-beam

  20. Modeling and control of a twin-screw extruder

    E-print Network

    Richburg, Leslie Leitzy

    1989-01-01

    MODELING AND CONTROL OF A TWIN-SCREW EXTRUDER A Thesis LESLIE LEITZY RICHBHRG Submitted to the Office of Graduate Studies of Texas ARM TJniversitl in partial fulfillment of the requirements for the degree of MASTER OF SCIE'FACE December 1989... Major Subject: Agricultural Engineering MODELING AND CONTROL OF A TWIN-SCREW EXTRUDER A Thesis by LESLIE LEITZY RICHBURG A. Dale Whittaker (Chair of Committee) Donald A. Bender (Member) Don R. Bittner (Member) . R. Hocking Larry . Wisdom...

  1. Residence time distribution in a corotating twin-screw extruder

    Microsoft Academic Search

    J. P Puaux; G Bozga; A Ainser

    2000-01-01

    A modeling study for the polymer flow and mixing in a corotating twin-screw extruder is presented. The residence time distribution (RTD) in a fully intermeshing corotating twin-screw extruder was measured, using iron powder as tracer, and an LDPE as flow material. Pulse-type input signal experiments were performed in different working conditions. To fit the experimental data obtained on two different

  2. Isthmus-guided cortical bone trajectory for pedicle screw insertion.

    PubMed

    Iwatsuki, Koichi; Yoshimine, Toshiki; Ohnishi, Yu-ichiro; Ninomiya, Kosi; Ohkawa, Toshika

    2014-08-01

    Herein is described cortical bone trajectory (CBT), a new path for pedicle screw insertion for lumbar vertebral fusion. Because the points of insertion are under the end of the inferior articular process, and because the screws are inserted toward the lateral side, there is less soft tissue development than with the conventional technique; the CBT technique therefore enables less invasive surgery than the conventional technique. However, it has some drawbacks. For example, in the original CBT approach, the points of insertion are in the vicinity of the end of the inferior articular process. Because this joint has been destroyed in many patients who have indications for intervertebral fusion surgery, it is sometimes difficult to use it as a reference point for screw insertion location. With severe lateral slippage, the screw insertion site can become significantly dislocated sideways, with possible resultant damaging to the spinal canal and/or nerve root. The CBT technique here involved inserting the screws while keeping clear of the intervertebral foramen with the assistance of side view X-ray fluoroscopy and using the end of the inferior articular process and the isthmus as points of reference for screw location. PMID:25179360

  3. Fixational eye movements and binocular vision

    PubMed Central

    Otero-Millan, Jorge; Macknik, Stephen L.; Martinez-Conde, Susana

    2014-01-01

    During attempted visual fixation, small involuntary eye movements–called fixational eye movements–continuously change of our gaze’s position. Disagreement between the left and right eye positions during such motions can produce diplopia (double vision). Thus, the ability to properly coordinate the two eyes during gaze fixation is critical for stable perception. For the last 50 years, researchers have studied the binocular characteristics of fixational eye movements. Here we review classical and recent studies on the binocular coordination (i.e., degree of conjugacy) of each fixational eye movement type: microsaccades, drift and tremor, and its perceptual contribution to increasing or reducing binocular disparity. We also discuss how amblyopia and other visual pathologies affect the binocular coordination of fixational eye movements. PMID:25071480

  4. Overcoming fixation with repeated memory suppression.

    PubMed

    Angello, Genna; Storm, Benjamin C; Smith, Steven M

    2015-04-01

    Fixation (blocks to memories or ideas) can be alleviated not only by encouraging productive work towards a solution, but, as the present experiments show, by reducing counterproductive work. Two experiments examined relief from fixation in a word-fragment completion task. Blockers, orthographically similar negative primes (e.g., ANALOGY), blocked solutions to word fragments (e.g., A_L_ _GY) in both experiments. After priming, but before the fragment completion test, participants repeatedly suppressed half of the blockers using the Think/No-Think paradigm, which results in memory inhibition. Inhibiting blockers did not alleviate fixation in Experiment 1 when conscious recollection of negative primes was not encouraged on the fragment completion test. In Experiment 2, however, when participants were encouraged to remember negative primes at fragment completion, relief from fixation was observed. Repeated suppression may nullify fixation effects, and promote creative thinking, particularly when fixation is caused by conscious recollection of counterproductive information. PMID:24575886

  5. Comparison of locked plate fixation and nonoperative management for displaced proximal humerus fractures in elderly patients.

    PubMed

    Okike, Kanu; Lee, Olivia C; Makanji, Heeren; Morgan, Jordan H; Harris, Mitchel B; Vrahas, Mark S

    2015-04-01

    Use of locked plate fixation for proximal humerus fractures in elderly patients has increased markedly in recent years. We conducted a study to compare outcomes of operative (locked plate fixation) and nonoperative management of these fractures. From our database, we identified 207 displaced proximal humerus fractures that met all inclusion and exclusion criteria. For patients who accepted our invitation to return for evaluation, clinical outcome was assessed using several questionnaires: Constant; DASH (Disabilities of the Arm, Shoulder, and Hand); SMFA (Short Musculoskeletal Functional Assessment); and Patient Reported Outcomes Measurement Information System (PROMIS) Physical Function Computer Adaptive Test. Of the 207 patients, 61 were managed operatively and 146 nonoperatively. Operative patients had lower rates of malunion but higher rates of complications, which included screw perforation, loss of fixation, infection, and secondary surgical procedures. Forty-seven patients (a mix of operative and nonoperative) accepted our invitation to return for clinical evaluation at a mean follow-up of 3.3 years. The 2 groups' clinical outcomes were similar. PMID:25844592

  6. Radical excision combined with instrumented fixation in the management of thoracic epidural angiolipoma: a case report

    PubMed Central

    2014-01-01

    Introduction Spinal angiolipoma is a benign uncommon neoplasm composed of mature lipocytes admixed with abnormal blood vessels. They account for only 0.04% to 1.2% of all spinal tumors. We present a case of thoracic epidural angiolipoma treated by combining radical resection with instrumented spinal fixation, without any surgical complication. Case presentation A 32-year-old Asian woman presented with dorsal epidural angiolipoma at the upper-thoracic level. She had a seven-month history of gradually worsening weakness and numbness in her lower extremities. Imaging studies of her thoracic spine demonstrated a heterogeneously well-enhancing mass, located in her posterior epidural space without surrounding bone erosion at the upper thoracic level. We also observed compression of her thoracic cord. During surgery, a reddish-gray, highly vascularized mass was excised. Her facet joints had to be resected to expose the part migrating into the intervertebral foramen. Because there was concern regarding the stability of her thoracic spine, we performed spinal fixation using pedicle screws. Histopathological study of the surgical specimen showed a typical angiolipoma. Conclusion Angiolipomas can be radically excised with good prognosis. Surgical removal is the preferred treatment for spinal angiolipoma, and the prognosis after surgical management is very good. Although outcomes remained favorable despite incomplete resections in a number of spinal angiolipoma, complete removal is preferred. We successfully achieved total resection without any surgical complication by combining radical resection with instrumented spinal fixation. PMID:25412677

  7. Pullout strength of misplaced pedicle screws in the thoracic and lumbar vertebrae - A cadaveric study

    PubMed Central

    Saraf, Shyam K; Singh, Ravindra P; Singh, Vakil; Varma, Ashish

    2013-01-01

    Background: The objective of this cadaveric study was to analyze the effects of iatrogenic pedicle perforations from screw misplacement on the mean pullout strength of lower thoracic and lumbar pedicle screws. We also investigated the effect of bone mineral density (BMD), diameter of pedicle screws, and the region of spine on the pullout strength of pedicle screws. Materials and Methods: Sixty fresh human cadaveric vertebrae (D10–L2) were harvested. Dual-energy X-ray absorptiometry (DEXA) scan of vertebrae was done for BMD. Titanium pedicle screws of different diameters (5.2 and 6.2 mm) were inserted in the thoracic and lumbar segments after dividing the specimens into three groups: a) standard pedicle screw (no cortical perforation); b) screw with medial cortical perforation; and c) screw with lateral cortical perforation. Finally, pullout load of pedicle screws was recorded using INSTRON Universal Testing Machine. Results: Compared with standard placement, medially misplaced screws had 9.4% greater mean pullout strength and laterally misplaced screws had 47.3% lesser mean pullout strength. The pullout strength of the 6.2 mm pedicle screws was 33% greater than that of the 5.2 mm pedicle screws. The pullout load of pedicle screws in lumbar vertebra was 13.9% greater than that in the thoracic vertebra (P = 0.105), but it was not statistically significant. There was no significant difference between pullout loads of vertebra with different BMD (P = 0.901). Conclusion: The mean pullout strength was less with lateral misplaced pedicle screws while medial misplaced pedicle screw had more pullout strength. The pullout load of 6.2 mm screws was greater than that of 5.2 mm pedicle screws. No significant correlation was found between bone mineral densities and the pullout strength of vertebra. Similarly, the pullout load of screw placed in thoracic and lumbar vertebrae was not significantly different. PMID:23798753

  8. Monitoring the reduced scattering coefficient of bone tissues on the trajectory of pedicle screw placement using near-infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Liu, Yangyang; Wang, Yuyan; Qian, Zhiyu; Zhao, Jinzhe; Cao, Xinzhi; Li, Weitao

    2014-11-01

    Pedicle screw (PS) fixation has been widely used for spine diseases. Scientists and clinicians employ several approaches to navigate PS during operation. We have demonstrated the feasibility of monitoring the reduced scattering coefficient (?s?) on the trajectory of PS using near-infrared spectroscopy (NIRS). To perform the in-vitro monitoring, an NIRS measurement system was introduced and the reduced scattering coefficients of different sites in porcine pedicle were accurately deduced from the spectrum. Moreover, the changes of the reduced scattering coefficient along the different paths were studied. The results show reduced scattering coefficients on different regions of bones can be significantly distinguished. Furthermore, monitoring experiments along different paths confirmed that a reduced scattering coefficient would change versus the depth of puncture in pedicles. Thus, the proposed monitoring system based on NIRS provides a potential for guiding PS during operation.

  9. Nitrogen fixation in coniferous bark litter

    Microsoft Academic Search

    Assi Weber; Veronica Sundman

    1986-01-01

    Summary  Non-symbiotic heterotrophic N2 fixation in coniferous bark litter was investigated with the acetylene reduction assay under aerobic and anaerobic conditions. The litter studied was composed essentially of bark, of pH 5 and a C\\/N ratio of 101; the ratio of available C to available N, which governs N2 fixation, was considerably higher. The rate of N2 fixation was estimated as

  10. Pin loosening in external skeletal fixation

    E-print Network

    Vittal, Bamini

    1993-01-01

    styled after Journal of Biomechanica/ Engineering Kreus did not precisely document the incidence and details of complications. Towards the end of World War II, however, the high incidence of significant complications associated with external fixation... of external skeletal fixation. Following World War II, the Committee on Fracture and Trauma Surgery of the American Academy of Orthopedic Surgeons investigated the efficiency, practicality, and rightful place of external skeletal fixation. The Committee...

  11. Neck of femur fracture fixation in a bilateral amputee: an uncommon condition requiring an improvised fracture table positioning technique.

    PubMed

    Berg, Andrew James; Bhatia, Chandra

    2014-01-01

    While neck of femur fractures are common it is rare to see this injury in a bilateral leg amputee. Special consideration needs to be given to the management of these patients. We report the case of a 58-year-old man with bilateral leg amputation who presented to the emergency department with left hip pain following a fall. A fracture of the left neck of femur with extension into the femoral shaft was diagnosed. Internal fixation was planned with a dynamic hip screw. Standard fracture table setup, which allows for traction of the fractured limb and positioning of the contralateral limb such that anteroposterior and lateral X-rays can be obtained, was not possible in this case due to the amputations. We highlight considerations that need to be made in positioning a bilateral amputee for neck of femur fracture fixation and also highlight an improvised technique that can be utilised by other surgeons. PMID:24563044

  12. Unilateral lateral mass fixation of cervical spinal low-grade chondrosarcoma with intralesional resection: A case report

    PubMed Central

    CHEN, BO; YANG, YAN; CHEN, LIANG; ZHOU, FENG; YANG, HUILIN

    2014-01-01

    In total, ~10% of chondrosarcomas arise from the mobile spine, and these are prone to local recurrence despite being low-grade malignant tumors. Almost all patients will present with pain and a palpable mass in the area of the lesion. For adequate management of the disease, an early diagnosis and careful surgical staging are important. The present study reports a case of cervical spinal low-grade chondrosarcoma in a young female presenting with a slow-growing mass that had not metastasized during a 3-year period. A unilateral lateral mass fixation system of screws and rods was installed following an intralesional resection of the tumor. At present, two years following the surgery, the patient exhibits no neurological deficiency symptoms. Therefore, unilateral fixation presents an effective alternative technique for the treatment of patients with a lesion on the cervical spine. PMID:24765168

  13. An analytical investigation of high-temperature heat pump system with screw compressor and screw expander for power recovery

    Microsoft Academic Search

    I. Tamura; H. Taniguchi; H. Sasaki; R. Yoshida; I. Sekiguchi; M. Yokogawa

    1997-01-01

    An analytical investigation of a high-temperature heat pump system was developed to estimate the thermal cycle and to assess the thermal fluids for their high-temperature delivery (up to 180°C) capacities without decomposition or the use of lubricant mechanisms. Then, a screw-type compressor was applied in the above conditions. Furthermore, a screw expander was also used as a replacement for the

  14. A congenital iliac anomaly often associated with sacral lipoma and ipsilateral lower extremity weakness

    Microsoft Academic Search

    William H. McAlister; Marilyn J. Siegel; Gary D. Shackelford

    1978-01-01

    Eight patients with an anomaly of the iliac bone consisting of a protuberance projecting into the greater sciatic notch are discussed. The anomaly may be associated with sciatic nerve compression and atrophy; sacral, buttock, or intradural lipomata; tethered spinal cord; and ipsilateral lower extremity weakness. Surgical treatment can result in improvement of neurologic symptoms and signs.

  15. Renal revascularization in high-risk patients: The role of iliac renal bypass

    Microsoft Academic Search

    Jean-Marc Fichelle; Giovanni Colacchio; Jean-Christophe Farkas; Alain Tugaye; Pascal Priollet; Claude Laurian; Jean-Michel Cormier

    1992-01-01

    Between 1984 and 1989, 29 iliac renal artery bypasses were performed in 29 patients (mean age 67.8 years) with severe renovascular disease due to atheroma. The indication for renal artery reconstruction was hypertension in all patients, which was associated with kidney failure in 16 cases. In six cases, reconstruction was performed after failure or complications of percutaneous transluminal angioplasty. The

  16. [Resection of iliac vessels and adnexial cancer: report of 2 cases].

    PubMed

    Lacorre, A; Gauthier, T; Gardet, E; Berger, J; Loum, O; Monteil, J; Tubiana, N; Aubard, Y

    2014-04-01

    Aim of no residual macroscopic disease has to be the objective of the gynecologist oncologist surgeon. It can require extensive surgical procedures in all the abdomen area. We report 2 rare cases of cytoreductive surgery with iliac vessels resection and use of vascular prosthesis. We discuss the opportunity of this surgery with high morbidity. PMID:24411338

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

    SciTech Connect

    Kwak, Hyo-Sung; Han, Young-Min, E-mail: ymhan@chonbuk.ac.kr; Chung, Gyung-Ho [Chonbuk National University Medical School, Department of Diagnostic Radiology (Korea, Republic of); Yu, Hee Chul; Jeong, Yeon-Jun [Chonbuk National University Medical School, Department of Surgery (Korea, Republic of)

    2006-10-15

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

  18. Endovascular Treatment of Proximal Bilateral Iliac Limb Dislocation and Kinking following Endovascular Abdominal Aortic Aneurysm Repair

    SciTech Connect

    Alerci, Mario; Wyttenbach, Rolf [Ospedale San Giovanni, Department of Radiology (Switzerland)], E-mail: rolf.wyttenbach@bluewin.ch; Bogen, Marcel [Ospedale San Giovanni, Department of Surgery (Switzerland); Segesser, Ludwig K. von [Centre Hospitalier Universitaire Vaudois-CHUV, Department of Cardiovascular Surgery (Switzerland); Gallino, Augusto [Ospedale San Giovanni, Department of Vascular Medicine (Switzerland); Inglese, Luigi [Ospedale San Donato, Servizio di Emodinamica (Italy)

    2005-05-15

    We report the case of a 69-year-old man with a late type 1b endoleak due to proximal migration of both iliac limbs 5 years after endovascular repair of an abdominal aortic aneurysm. The endovascular method used to correct bilaterally this condition is described. Final angiographic control shows patency of the stent-graft without signs of endoleak.

  19. [Endovascular closure of iatrogenic arteriovenous anastomosis of the iliac artery and vein].

    PubMed

    Sin'kov, M A; Murashkovski?, A L; Pogorelov, E A; Golovin, A A; Kalinichenko, N A; Khaes, B L; Kokov, A N; Kheraskov, V Iu; Evtushenko, S A; Popov, V A; Barbarash, L S

    2014-01-01

    The presented herein clinical case report concerns successful endovascular closure of a iatrogenic lesion of the iliac artery and inferior vena cava with formation of a pathological arteriovenous anastomosis manifesting itself by venous thromboembolic syndrome and severe right-ventricular insufficiency. PMID:24722024

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

    SciTech Connect

    Huetink, K. [Leiden University Medical Center, Department of Radiology (Netherlands)], E-mail: k.huetink@lumc.nl; Steijling, J.J.F. [University Medical Center, Department of Vascular Surgery (Netherlands); Mali, W.P.T.M. [University Medical Center, Department of Radiology (Netherlands)

    2008-03-15

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

  1. Therapeutic Consequences of Variation in Intraarterial Pressure Measurements After Iliac Angioplasty

    SciTech Connect

    Tetteroo, Eric; Haaring, Cees; Engelen, Andries D. van [Department of Radiology, Room E.01.132, University Hospital Utrecht, Heidelberglaan 100, NL-3584 CX Utrecht (Netherlands); Graaf, Yolanda van der [Department of Clinical Epidemiology, University Hospital Utrecht, Heidelberglaan 100, NL-3584 CX Utrecht (Netherlands); Mali, Willem P.T.M. [Department of Radiology, Room E.01.132, University Hospital Utrecht, Heidelberglaan 100, NL-3584 CX Utrecht (Netherlands)

    1997-11-15

    Purpose: To assess the accuracy of intraarterial measurement of transstenotic pressure gradients for the detection of hemodynamically suboptimal iliac angioplasty. Methods: In 14 patients, referred for diagnostic angiography, mean pressure gradients in the aorta and iliac artery were obtained twice, using a double-sensor pressure catheter. Additional iliac measurements were performed during pharmacologically induced flow augmentation. Repeatability was assessed by calculation of the mean difference plus standard deviation (MD {+-} SD) and repeatability coefficient (2 x SD). These results were extrapolated to 137 iliac angioplasty procedures with secondary stenting where there was a residual pressure gradient > 10 mmHg. Results: MD {+-} SD for repeated measurements at rest and during flow augmentation were 0 {+-} 2 mmHg and 1 {+-} 3 mmHg, respectively. Repeatability coefficients were 3 and 6 mmHg. Mean pressure gradients after hemodynamically insufficient angioplasty were 8 {+-} 7 mmHg at rest and 17 {+-} 5 mmHg following vasodilatation. Inaccurate pressure recordings may have led to inappropriate stent placement in less than 2.5%, and inappropriate denial of stent placement in less than 5% of the lesions. Conclusion: Variability of intraarterial pressure measurements has little consequence in the detection of hemodynamically significant stenosis after angioplasty.

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

    SciTech Connect

    Uberoi, Raman, E-mail: raman.uberoi@orh.nhs.uk; Milburn, Simon; Moss, Jon [John Radcliffe Hospital, Department of Radiology (United Kingdom)

    2009-09-15

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

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

    SciTech Connect

    Onal, Baran; Ilgit, Erhan T.; Yuecel, Cem; Ozbek, Erdal; Vural, Murat; Akpek, Sergin [Department of Radiology, School of Medicine, Gazi University, Besevler, 06510 Ankara (Turkey)

    1998-09-15

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

  4. Screw Instability and Blandford-Znajek Mechanism

    E-print Network

    Li-Xin Li

    2000-01-25

    When magnetic field lines thread a rotating black hole's horizon and connect with remote astrophysical loads, the rotational energy of the black hole can be extracted through the Blandford-Znajek mechanism. Due to the rotation of the black hole, the magnetic field lines are twisted and toroidal components are generated. So poloidal electric currents are induced and the black hole's rotational energy is transported to the astrophysical loads through Poynting flux. The Blandford-Znajek mechanism has been considered to be a possible process for powering extragalactic jets. In this paper we show that due to the screw instability of magnetic field, the toroidal components of the magnetic field, and thus the poloidal currents, cannot exceed the limits given by the Kruskal-Shafranov criterion. This significantly lowers the power of the Blandford-Znajek mechanism when the loads are far from the black hole. So the Blandford-Znajek mechanism can only work efficiently within the neighborhood of the black hole. The implications of the results for the scenario of extragalactic jets powered by the Blandford-Znajek mechanism are discussed.

  5. MagScrew TAH: an update.

    PubMed

    Weber, Stephan; Kamohara, Keiji; Klatte, Ryan S; Luangphakdy, Viviane; Flick, Christine; Chen, Ji-Feng; Casas, Fernando; Ootaki, Yoshio; Kopcak, Michael; Akiyama, Masatoshi; Hirschman, Gordon B; Chapman, Peter A; Donahue, Arthur; Wetterau, William; Prisco, Charles; Mast, Roy; Sherman, Craig; Fukamachi, Kiyotaka; Smith, William A

    2005-01-01

    The MagScrew Total Artificial Heart (TAH) system is the result of a close collaboration among the Cleveland Clinic Foundation, Foster Miller Technologies, Wilson Greatbatch Ltd, and Whalen Biomedical Inc. The system components are the thoracic blood pumping unit with attached compliance chamber and refill port, implantable electronic control unit, implantable battery pack, transcutaneous energy transmission system, external battery pack, and a telemetry system for communication with the electronic control unit. System in vitro tests are underway for system characterization and durability demonstration, whereas in vivo tests were conducted to evaluate system performance and biocompatibility under physiologic conditions. The passively filling pump uses a left master alternate left and right ejection control mode and has a Starling law-like response to venous pressure. The in vitro tests documented excellent hydraulic pump performance with high device output of over 9 l/min at left atrial pressures below 12 mm Hg. Atrial balance was well maintained under all test conditions. The in vivo tests demonstrated good biocompatibility without use of anticoagulant therapy. Experimental durations have ranged between 0 and 92 days. Postexplant evaluation of tissue samples did not reveal any sign of thromboembolic events or tissue damage due to device operation. PMID:16340348

  6. 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.

  7. Methanotrophy induces nitrogen fixation during peatland development

    PubMed Central

    Larmola, Tuula; Leppänen, Sanna M.; Tuittila, Eeva-Stiina; Aarva, Maija; Merilä, Päivi; Fritze, Hannu; Tiirola, Marja

    2014-01-01

    Nitrogen (N) accumulation rates in peatland ecosystems indicate significant biological atmospheric N2 fixation associated with Sphagnum mosses. Here, we show that the linkage between methanotrophic carbon cycling and N2 fixation may constitute an important mechanism in the rapid accumulation of N during the primary succession of peatlands. In our experimental stable isotope enrichment study, previously overlooked methane-induced N2 fixation explained more than one-third of the new N input in the younger peatland stages, where the highest N2 fixation rates and highest methane oxidation activities co-occurred in the water-submerged moss vegetation. PMID:24379382

  8. Methanotrophy induces nitrogen fixation during peatland development.

    PubMed

    Larmola, Tuula; Leppänen, Sanna M; Tuittila, Eeva-Stiina; Aarva, Maija; Merilä, Päivi; Fritze, Hannu; Tiirola, Marja

    2014-01-14

    Nitrogen (N) accumulation rates in peatland ecosystems indicate significant biological atmospheric N2 fixation associated with Sphagnum mosses. Here, we show that the linkage between methanotrophic carbon cycling and N2 fixation may constitute an important mechanism in the rapid accumulation of N during the primary succession of peatlands. In our experimental stable isotope enrichment study, previously overlooked methane-induced N2 fixation explained more than one-third of the new N input in the younger peatland stages, where the highest N2 fixation rates and highest methane oxidation activities co-occurred in the water-submerged moss vegetation. PMID:24379382

  9. Tibial rotational osteotomy with intramedullary nail fixation

    PubMed Central

    Stevens, Peter M.

    2009-01-01

    There are several theoretic advantages of using intramedullary rod fixation for tibial osteotomy fixation. We performed a retrospective review of patients who were treated with a mid-diaphyseal osteotomy of the tibia fixed with an intramedullary rod for isolated, symptomatic tibial torsion. Forty patients (59 tibias) were included in the study and were followed for a minimum of 12 months or until rod removal (average follow-up 22.6 months). Major complication rate was 8.5%, which is comparable to alternative methods of fixation. We believe that intramedullary rods are a safe alternative for fixation of tibial rotational osteotomy in patients with physeal closure. PMID:19941168

  10. The influence of screw configuration on the pretreatment performance of a continuous twin screw-driven reactor (CTSR).

    PubMed

    Choi, Chang Ho; Um, Byung-Hwan; Oh, Kyeong Keun

    2013-03-01

    A combination of a continuous twin screw-driven reactor (CTSR) and a dilute acid pretreatment was used for the pretreatment of biomass with a high cellulose content and high monomeric xylose hydrolyzate. With the newly modified CTSR screw configuration (Config. 3), the influences of the screw rotational speed (30-60 rpm), of the pretreatment conditions such as acid concentration (1-5%) and reaction temperature (160-175 °C) at the operating condition of biomass feeding rate (1.0 g/min) and acid feeding rate (13.4 mL/min) on the pretreatment performance were investigated. The cellulose content in the pretreated rape straw was 67.1% at the following optimal conditions: barrel temperature of 165 °C, acid concentration of 3.0% (w/v), and screw rotational speed of 30 rpm. According to the three screw configurations, the glucose yields from enzymatic hydrolysis were 70.1%, 72.9%, and 78.7% for screw Configs. 1, 2, and 3, respectively. PMID:23395738

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

    SciTech Connect

    Minko, P., E-mail: peterminko@yahoo.com; Bücker, A. [University Hospital Homburg/Saar, Department of Diagnostic and Interventional Radiology (Germany); Laschke, M.; Menger, M. [University Hospital Homburg/Saar, Institute of Clinical and Experimental Surgery (Germany); Bohle, R. [University Hospital Homburg/Saar, Department of Pathology (Germany); Katoh, M. [University Hospital Homburg/Saar, Department of Diagnostic and Interventional Radiology (Germany)

    2013-06-08

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

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

    SciTech Connect

    Malagari, Katerina, E-mail: kmalag@aias.gr; Brountzos, Elias; Gougoulakis, Alexandros; Papathanasiou, Matilda; Alexopoulou, Efthymia; Mastorakou, Renata; Kelekis, Dimitris [University of Athens, 2nd Department of Radiology (Greece)

    2004-09-15

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

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

    SciTech Connect

    Coupe, Nicholas J., E-mail: optimus2050@hotmail.com; Ling, Lynn; Cowling, Mark G.; Asquith, John R. [University Hospital of North Staffordshire, City General Hospital, Department of Radiology (United Kingdom); Hopkinson, Gregory B. [University Hospital of North Staffordshire, City General Hospital, Department of Surgery (United Kingdom)

    2009-07-15

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

  14. Nitrogen fixation method and apparatus

    DOEpatents

    Chen, H.L.

    1983-08-16

    A method and apparatus for achieving nitrogen fixation includes a volumetric electric discharge chamber. The volumetric discharge chamber provides an even distribution of an electron beam, and enables the chamber to be maintained at a controlled energy to pressure (E/p) ratio. An E/p ratio of from 5 to 15 kV/atm of O[sub 2]/cm promotes the formation of vibrationally excited N[sub 2]. Atomic oxygen interacts with vibrationally excited N[sub 2] at a much quicker rate than unexcited N[sub 2], greatly improving the rate at which NO is formed. 1 fig.

  15. Fracture repair of the distal portion of the radius by use of a condylar screw implant in an adult horse.

    PubMed

    Rodgerson, D H; Wilson, D A; Kramer, J

    2001-06-15

    An 8-year-old American Quarter Horse gelding was evaluated because of an open fracture involving the left radius. The horse had fallen during training and became immediately non-weight-bearing in the left forelimb. On initial evaluation, the horse was unable to bear weight on that limb; radiography revealed a long oblique fracture of the distal metaphysis of the radius with minimal displacement of the fracture fragments. Because of the configuration of the fracture, we recommended surgical intervention with internal fixation. A condylar screw implant and 4.5-mm broad dynamic compression plate were applied to the medial and dorsolateral aspects of the radius, respectively. The horse recovered in a sling and full-limb bandage. Six months after discharge, the horse was reevaluated because of a grade 4/5 lameness in the same limb. Palpation revealed signs of severe pain over the distomedial aspect of the radius. Radiography of the left radius revealed severe osteolysis beneath the distal aspect of the condylar screw implant. Surgical removal of the medial plate was performed. Sixteen months after the initial fracture repair, the horse had returned to light training without signs of lameness. Removal of the dorsal plate may be indicated if this horse is to return to aggressive training or becomes lame in the left forelimb. PMID:11417743

  16. FEM evaluation of cemented-retained versus screw-retained dental implant single-tooth crown prosthesis

    PubMed Central

    Cicciu, Marco; Bramanti, Ennio; Matacena, Giada; Guglielmino, Eugenio; Risitano, Giacomo

    2014-01-01

    Prosthetic rehabilitation of partial or total edentulous patients is today a challenge for clinicians and dental practitioners. The application of dental implants in order to recover areas of missing teeth is going to be a predictable technique, however some important points about the implant angulation, the stress distribution over the bone tissue and prosthetic components should be well investigated for having final long term clinical results. Two different system of the prosthesis fixation are commonly used. The screw retained crown and the cemented retained one. All of the two restoration techniques give to the clinicians several advantages and some disadvantages. Aim of this work is to evaluate all the mechanical features of each system, through engineering systems of investigations like FEM and Von Mises analyses. The FEM is today a useful tool for the prediction of stress effect upon material and biomaterial under load or strengths. Specifically three different area has been evaluated through this study: the dental crown with the bone interface; the passant screw connection area; the occlusal surface of the two different type of crown. The elastic features of the materials used in the study have been taken from recent literature data. Results revealed an adequate response for both type of prostheses, although cemented retained one showed better results over the occlusal area. PMID:24955150

  17. A computational study on the effect of fracture intrusion distance in three- and four-part trochanteric fractures treated with Gamma nail and sliding hip screw.

    PubMed

    Goffin, Jérôme M; Pankaj, Pankaj; Simpson, A Hamish

    2014-01-01

    Using finite element analysis, the behaviors of the Gamma nail and the sliding hip screw (SHS) were compared in an osteoporotic bone model for the fixation of three- and four-part trochanteric fractures (31-A2 in the AO classification, types IV and V in Evans' classification). The size of the medial fragment was varied based on clinical data, and the case of a fractured greater trochanter was also considered. Our results showed that for Evans' type V stabilized with a Gamma nail and for Evans' types IV and V with the SHS, cancellous bone around the lag screw is susceptible to yielding, thus indicating a risk of cut-out. The volume of bone susceptible to yielding increases with an increase in size of the medial fragment. Conversely, Evans' type IV with a Gamma nail was not predicted to cut out. Our findings suggest that future clinical trials investigating fixation of unstable proximal fractures should include the size of the medial fragment and the integrity of the greater trochanter as covariables and be powered to evaluate whether intramedullary devices are superior to SHSs for Evans' type IV fractures and inferior/equivalent for type V. PMID:24123306

  18. 21 CFR 878.3250 - External facial fracture fixation appliance.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...2013-04-01 false External facial fracture fixation appliance. 878.3250...Devices § 878.3250 External facial fracture fixation appliance. (a) Identification. An external facial fracture fixation appliance is a...

  19. 21 CFR 878.3250 - External facial fracture fixation appliance.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...2014-04-01 false External facial fracture fixation appliance. 878.3250...Devices § 878.3250 External facial fracture fixation appliance. (a) Identification. An external facial fracture fixation appliance is a...

  20. Unilateral fixation for treatment of occipitocervical instability in children with congenital vertebral anomalies of the craniocervical junction.

    PubMed

    Mazur, Marcus D; Ravindra, Vijay M; Brockmeyer, Douglas L

    2015-04-01

    OBJECT Patients with occipitocervical (OC) instability from congenital vertebral anomalies (CVAs) of the craniocervical junction (CCJ) often have bony abnormalities that make instrumentation placement difficult. Within this patient population, some bilateral instrumentation constructs either fail or are not feasible, and a unilateral construct must be used. The authors describe the surgical management and outcomes of this disorder in patients in whom unilateral fixation constructs were used to treat OC instability. METHODS From a database of OC fusion procedures, the authors identified patients who underwent unilateral fixation for the management of OC instability. Patient characteristics, surgical details, and radiographic outcomes were reviewed. In each patient, CT scans were performed at least 4 months after surgery to evaluate for fusion. RESULTS Eight patients with CVAs of the CCJ underwent unilateral fixation for the treatment of OC instability. For 4 patients, the procedure occurred after a bilateral OC construct failed or infection forced hardware removal. For the remainder, it was the primary procedure. Two patients required reoperation for hardware revision and 1 developed nonunion requiring revision of the bone graft. Ultimately, 7 patients demonstrated osseous fusion on CT scans and 1 had a stable fibrous union. CONCLUSIONS These findings demonstrate that a unilateral OC fixation is effective for the treatment of OC instability in children with CVAs of the CCJ in whom bilateral screw placement fails or is not feasible. PMID:25828503