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1

Radiographic study of iliac screw passages  

PubMed Central

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

2014-01-01

2

Biomechanical stability of bioabsorbable screws for fixation of acetabular osteotomies.  

PubMed

The purpose of this study was to compare the biomechanical stability of triple innominate osteotomies fixed with either bioabsorbable or stainless steel screws. Triple innominate osteotomies were performed on composite hemipelves and fixed with either three 4.5-mm bioabsorbable screws or three stainless steel 4.5-mm screws. Two screws were placed from the iliac wing into the acetabular fragment, and 1 screw was placed from below the acetabular fragment into the iliac wing. Eight specimens for each screw type were biomechanically tested in an anatomical position (replicating weight bearing) and in a flexed and abducted position (replicating spica cast positioning). Specimens were cyclically loaded between 10 and 450 N to simulate the hip contact force in this population. Lower screws were then removed, and specimens were tested under identical conditions. Fragment displacement (mm) and construct stiffness (N/mm) were compared with a 2-way analysis of variance (P < 0.05). There were no significant differences between materials for fragment displacement or construct stiffness. Anatomical position showed significantly less displacement than spica position for both materials. Initial displacement in the spica position was significantly less during lower loads for stainless steel fixation. Bioabsorbable screws demonstrate comparable biomechanical stability to stainless steel screws in anatomical and spica positions at physiological loads. Flexion and abduction of the femur adversely affect the stability of the construct for both materials. Bioabsorbable screws behave similarly to steel screws when stabilizing triple innominate osteotomies and would have the advantage of not requiring a second surgery for screw removal. Confirmation of biocompatibility should be completed before widespread clinical application. PMID:17414017

Adamczyk, Mark J; Odell, Tim; Oka, Richard; Mahar, Andrew T; Pring, Maya E; Lalonde, François D; Wenger, Dennis R

2007-01-01

3

Intramedullary screw fixation of lateral malleolus fractures.  

PubMed

A biomechanical evaluation of intramedullary versus buttress plate and lag screw fixation of lateral malleolus fractures is combined with a clinical evaluation of 44 patients with lateral malleolus fractures who underwent intramedullary screw fixation. The biomechanical study was performed in experimentally produced, Weber B, supination-eversion ankle fractures. The fractures were fixed with one of the two above fixation methods and then placed under a torsional load to failure. Sixteen cadaver ankles were tested as compared with native bone. The intramedullary screw provided 66.5% the resistance of torsion, and the buttress plate and lag screw provided 61.5% the resistance to torsion. There was no statistical difference between these two groups. The 44 fractures treated with an intramedullary screw were reviewed retrospectively. There was one failure of fixation, and one prominent hardware problem. Time to full weightbearing averaged 7.2 weeks. These results suggest that intramedullary screw fixation of noncomminuted lateral malleolus fractures provides stable fixation with good clinical results. This technique has the advantages of providing dynamic intramedullary fixation with limited surgical dissection and no subcutaneous hardware. PMID:7849975

Bankston, A B; Anderson, L D; Nimityongskul, P

1994-11-01

4

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

PubMed Central

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

2014-01-01

5

Effect of Screw Length on Bioabsorbable Interference Screw Fixation in a Tibial Bone Tunnel  

Microsoft Academic Search

Initial tibial fixation strength is the weak link after anterior cruciate ligament reconstruction with a quadrupled hamstring tendon graft fixed with bioabsorbable interference screws. The purpose of this study was to determine the biomechanical differences between 28-mm and tapered 35-mm interference screws for tibial fixation of a soft tissue graft in 16 young cadaveric tibias. Failure mode, displacement before failure,

Jeffrey B. Selby; Darren L. Johnson; Peter Hester; David N. M. Caborn

2001-01-01

6

Intermaxillary fixation screw for endotracheal tube fixation in the edentulous patient with facial burns.  

PubMed

Endotracheal tube fixation in patients with severe facial burns and edentulism is a challenge. We describe a simple and elegant method to secure the endotracheal tube in such patients by means of an intermaxillary fixation screw. PMID:24948409

Fleissig, Y; Rushinek, H; Regev, E

2014-10-01

7

Fixation of mandibular fractures with biodegradable plates and screws  

Microsoft Academic Search

Objective. Little data exist regarding the use of biodegradable plates and screws for the internal fixation of human mandibular fractures. The purpose of this study was to evaluate the stability of biodegradable, self-reinforced poly-L-lactide plates and screws for the internal fixation of fractures of the human mandible. Study Design. Twenty-two individuals (14 male, 8 female; average age, 26.3 years) with

Kaan C. Yerit; Georg Enislidis; Christian Schopper; Dritan Turhani; Felix Wanschitz; Arne Wagner; Franz Watzinger; Rolf Ewers

2002-01-01

8

Sacroiliac screw fixation: A mini review of surgical technique  

PubMed Central

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

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

2014-01-01

9

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

PubMed Central

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

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

2014-01-01

10

Screw fixation of the syndesmosis: a cadaver model comparing stainless steel and titanium screws and three and four cortical fixation  

Microsoft Academic Search

We assessed syndesmotic set screw strength and fixation capacity during cyclical testing in a cadaver model simulating protected weight bearing. Sixteen fresh frozen legs with artificial syndesmotic injuries and a syndesmotic set screw made of stainless steel or titanium, inserted through three or four cortices, were axially loaded with 800N for 225,000 cycles in a materials testing machine. The 225,000

Annechien Beumer; Martin M. Campo; Ruud Niesing; Judd Day; Gert-Jan Kleinrensink; Bart A. Swierstra

2005-01-01

11

Four-Screw Plate Fixation vs Conventional Fixation for Diaphyseal Fractures of the Forearm  

PubMed Central

Background: Standard treatment of diaphyseal fractures of the forearm is open reduction and fixation using dynamic compression plates (DCP) and screws. This technique uses screw placement in all 6 or more of the plate holes except the hole over the fracture line. We hypothesized that DCP with selective 4-screw bicortical placement can provide adequate fixation for these fractures. Objectives: The aim of this study was to evaluate the results of conventional 6 or more screw fixation versus 4 screw fixation for adults with diaphyseal fractures of the forearm. Patients and Methods: In this prospective study, 128 fractures of the ulna, radius or both bones of the forearm in 87 patients were treated in either one of these two groups: Open reduction and internal fixation (ORIF) with conventional DCP and screws or ORIF using DCP and selective 4- screw placement. Fractures were transverse or oblique in pattern without gross comminution. In a total of 41 patients with fractures, 28 single ulnar and 18 single radius fractures were included. Follow-up visits were done at 3-6 and 12-16 weeks and at 6 months. Outcome with respect to union an nonunion rates, union time, infection, and device failure was noted. Results: No change in alignment was noted in any patient. Union time in conventional and selective bicortical 4-screw fixation was 74.8 days and 73.6 days respectively which showed no significant difference (P = 0.064). Union rate and infection was 92.1% and 3.2% in conventional and 95.3% and 0% in the selective group respectively. Non-union was observed in 5 and 3 cases of fractures in conventional and the selective group respectively. Conclusions: For treatment of the transverse or oblique diaphyseal fractures of the forearm, fixation by a same length 3.5 mm DCP with selective 4-screw cortical fixation (2 screws on each side of the fracture site) had similar results in comparison with conventional 6 or more DCP screws. Because of lesser impact on host bone and smaller incision, the selective 4-screw insertion can be an alternative technique for treatment of these fractures. PMID:24829892

Mehdi Nasab, Seyed Abdolhossein; Sarrafan, Nasser; Sabahi, Saeed

2012-01-01

12

Hamstring tendon fixation using interference screws: a biomechanical study in calf tibial bone  

Microsoft Academic Search

It has recently been shown that graft fixation close to the ACL insertion site is optimal in order to increase anterior knee stability. Hamstring tendon fixation using interference screws offers this possibility and a round threaded titanium interference screw has been previously developed. The use of a round threaded biodegradable interference screw may be equivalent. In addition, to increase initial

A Weiler; RF Hoffmann; AC Stähelin; HJ Bail; CJ Siepe; NP Südkamp

1998-01-01

13

Initial fixation strength of polylactic acid interference screws in anterior cruciate ligament reconstruction  

Microsoft Academic Search

The initial fixation properties of bioresorbable polylactic acid (PLA) interference screws designed for anterior cruciate ligament reconstruction were evaluated using an in vitro bovine model. The surgical technique of interference screw fixation of the bone-patellar tendon-bone autograft complex performed clinically was reproduced in an adult bovine model. The reconstructed knee was tested oriented in 30 degrees of flexion to allow

JA Abate; PD Fadale; MJ Hulstyn; WR Walsh

1998-01-01

14

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

PubMed Central

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

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

2014-01-01

15

Mechanical properties of two canine iliac fracture fixation systems  

E-print Network

. Computer generated plots of force versus displace- ment were made for determination of the stiffness and failure strength of the specimen. Failure was defined as exceedance of ultimate strength or fracture gap propaga- tion of greater than 2 mm. Failed.... Either situation is considered exceedance of ultimate strength. In all plated specimens in all testing modes failure was defined in terms of fracture gap propagation greater than 2 mm. In torsional testing the bone plate fixation system usually...

VanGundy, Thomas Eugene

2012-06-07

16

Posterior pelvic ring fractures: Closed reduction and percutaneous CT-guided sacroiliac screw fixation  

Microsoft Academic Search

Purpose  To assess the midterm results of closed reduction and percutaneous fixation (CRPF) with computed tomography (CT)-guided sacroiliac\\u000a screw fixation in longitudinal posterior pelvic ring fractures.\\u000a \\u000a \\u000a \\u000a Methods  Thirteen patients with 15 fractures were treated. Eleven patients received a unilateral, two a bilateral, screw fixation.\\u000a Twenty-seven screws were implanted. Continuous on-table traction was used in six cases. Mean radiological follow-up was 13\\u000a months.

Augustinus Ludwig Jacob; Peter Messmer; Klaus-Wilhelm Stock; Norbert Suhm; Bernard Baumann; Pietro Regazzoni; Wolfgang Steinbrich

1997-01-01

17

Failure of synthes anterior cervical fixation device by fracture of Morscher screws: a biomechanical study.  

PubMed

Anterior cervical fixation using the Synthes system has become increasingly popular. Two screw types for anchoring the plates include a "solid" titanium expansion screw and a plasma-sprayed fenestrated expansion screw that permits bony ingrowth. These screws were compared clinically and in the laboratory. In our first 20 cases using Synthes plates secured by Morscher fenestrated screws, 3 failures were observed, unilaterally in 1 patient and bilaterally in 2 others. In the unilateral screw failure, the contralateral screw was "solid" and did not fail. In the mechanical studies, screws were secured in the Synthes plate and embedded into methylmethacrylate and subjected to a sinusoidal bending moment to the mid-shaft of the screw. Load deflection data and cycles to failure were recorded. Fenestrated screws were found to demonstrate nearly twice as much deformation at failure and tolerated significantly fewer cycles to failure than did "solid" screws (p < 0.05). Because benefits of bony ingrowth into the screw are not well identified, the risks of fenestrated screw failure should preclude their routine use. PMID:8003828

Hollowell, J P; Reinartz, J; Pintar, F A; Morgese, V; Maiman, D J

1994-04-01

18

Monoaxial Pedicle Screws Are Superior to Polyaxial Pedicle Screws and the Two Pin External Fixator for Subcutaneous Anterior Pelvic Fixation in a Biomechanical Analysis  

PubMed Central

Purpose. Comparison of monoaxial and polyaxial screws with the use of subcutaneous anterior pelvic fixation. Methods. Four different groups each having 5 constructs were tested in distraction within the elastic range. Once that was completed, 3 components were tested in torsion within the elastic range, 2 to torsional failure and 3 in distraction until failure. Results. The pedicle screw systems showed higher stiffness (4.008 ± 0.113?Nmm monoaxial, 3.638 ± 0.108?Nmm Click-x; 3.634 ± 0.147?Nmm Pangea) than the exfix system (2.882 ± 0.054?Nmm) in distraction. In failure testing, monoaxial pedicle screw system was stronger (360?N) than exfixes (160?N) and polyaxial devices which failed if distracted greater than 4?cm (157?N Click-x or 138?N Pangea). The exfix had higher peak torque and torsional stiffness than all pedicle systems. In torsion, the yield strengths were the same for all constructs. Conclusion. The infix device constructed with polyaxial or monoaxial pedicle screws is stiffer than the 2 pin external fixator in distraction testing. In extreme cases, the use of reinforcement or monoaxial systems which do not fail even at 360?N is a better option. In torsional testing, the 2 pin external fixator is stiffer than the pedicle screw systems. PMID:24368943

Vaidya, Rahul; Onwudiwe, Ndidi; Roth, Matthew; Sethi, Anil

2013-01-01

19

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

PubMed

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

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

2014-02-01

20

Atlantoaxial transarticular screw fixation and posterior fusion using ultra-high-molecular-weight polyethylene cable.  

PubMed

This article attempts to evaluate the effectiveness of the ultra-high-molecular-weight polyethylene (UHMW-PE) cable system in atlantoaxial transarticular screw fixation and posterior fusion through the clinical results of 10 postoperative patients with atlantoaxial subluxation secondary to rheumatoid arthritis. Among them, one patient with only one screw placed owing to an anomalous vertebral artery had the correction loss of the 3-mm atlas-dens interval after surgery. Another patient had a second operation to remove the screw and cable after 2 years 11 months because a unilateral transarticular screw had come to protrude through the lateral mass of the atlas ventrally. All patients had achieved C1-C2 osseous fusion without any complications associated with this cable system. The UHMW-PE cable is a very useful material as sublaminar wiring in atlantoaxial transarticular screw fixation and posterior fusion. PMID:16189448

Yonezawa, Ikuho; Arai, Yasuhisa; Tsuji, Takaaki; Takahashi, Masaki; Kurosawa, Hisashi

2005-10-01

21

Efficacy analysis of pedicle screw internal fixation of fractured vertebrae in the treatment of thoracolumbar fractures  

PubMed Central

The present study aimed to discuss the method and effect of posterior internal fixation of thoracolumbar fractures strengthened by the vertical stress pedicle screw fixation of fractured vertebrae. Patients with single thoracolumbar fractures were examined retrospectively. Fourteen patients (group A) had been treated with vertical stress pedicle screw fixation of a fractured vertebra and sixteen patients (group B) received traditional double-plate fixation, as a control. All patients were diagnosed with fresh fractures with a complete unilateral or bilateral pedicle and no explosion of the inferior half of the vertebral body or inferior endplate. In group A, patients received conventional posterior distraction and lumbar lordosis restoration, as well as pedicle screws in the fractured vertebra in a vertical direction to relieve stress to achieve a local stress balance. All patients were followed up postoperatively for 4–18 months (average, 12.6 months). The vertical stress pedicle screw fixation assisted in the reduction of vertebrae fracture, which reduced the postoperative Cobb’s angle loss. There was a significant difference in the change of Cobb’s angle between the two groups one year after surgery (P<0.01). Conditional application of pedicle screws in a single thoracolumbar fracture enhances the stability of the internal fixation system and is conducive to the correction of kyphosis and maintenance of the corrective effects. PMID:23407593

HUANG, WEIJIE; LUO, TAO

2013-01-01

22

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

PubMed

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

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

2013-12-01

23

Less is more: lag screw only fixation of lateral malleolar fractures  

PubMed Central

Displaced fractures of the lateral malleolus are typically treated with plate osteosynthesis with or without the use of lag screws, and immobilisation in a plaster cast for up to 6 weeks. Fixation through a smaller incision with less metal, such as lag screw only fixation, would theoretically lead to decreased infection rates and less irritation caused by hardware. The purpose of this study was to evaluate the benefits and success of lag screw only fixation of the lateral malleolus in non-comminuted oblique fractures of the lateral malleolus. A total of 25 patients who had non-comminuted unstable oblique fractures of their lateral malleolus that had been surgically fixed with lag screws only were retrospectively evaluated. All patients were younger than 60 years of age. Evaluation of the success of fixation, complications, resultant mobility and patient satisfaction was based on information gathered from chart reviews, X-ray findings and a standardised questionnaire based on the AOFAS Foot and Ankle Outcomes Questionnaire. These results were compared to an age-matched group of 25 consecutive patients treated with plate osteosynthesis. Of the 25 patients fixed with lag screws, nine had an unstable fracture of the lateral malleolus only, ten were bimalleolar fractures and six were trimalleolar. Eighteen patients were treated with two lag screws, and seven were treated with three lag screws. The bi- and trimalleolar fractures were treated with standard partially threaded cancellous screws. None of the lag screw-only group lost reduction. There were no documented wound infections in the lag screw group as compared to three deep infections in the plate group. Lag screw-only patients reported no palpable hardware as compared to 50% of the plate group. AOFAS scores at a mean of 12 months post-operative were similar in both groups. Lag screw only fixation of the lateral malleolus is a safe and effective method that has a number of advantages over plate osteosynthesis, in particular less soft tissue dissection, less prominent, symptomatic and palpable hardware and a reduced requirement for secondary surgical removal. PMID:16947052

O'Shea, Kieran; Burke, Tom

2006-01-01

24

Hybrid computer-guided and minimally open surgery: anterior lumbar interbody fusion and translaminar screw fixation.  

PubMed

Less invasiveness is the way forward for spinal surgery. Minimal disruption of tissue, preservation of muscle function, and restoration of normal spinal alignment are still the goals of most surgical procedures. An anterior lumbar fusion technique using a less invasive procedure with the addition of translaminar screws is described. The autograft is harvested from the vertebral body, thus avoiding the morbidity associated with an iliac crest bone graft. The operative steps for the procedure are described. PMID:10766061

Kumar, N; Wild, A; Webb, J K; Aebi, M

2000-02-01

25

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

PubMed

The present work introduces a method of screw fixation of femoral neck fractures in the presence of osteoporosis, according to an original concept of the establishment of two supporting points for the implants and their biplane positioning in the femoral neck and head. The provision of two steady supporting points for the implants and the highly increased (obtuse) angle at which they are positioned allow the body weight to be transferred successfully from the head fragment onto the diaphysis, thanks to the strength of the screws, with the patient's bone quality being of least importance. The position of the screws allows them to slide under stress with a minimal risk of displacement. The method was developed in search of a solution for those patients for whom primary arthroplasty is contraindicated. The method has been analysed in relation to biomechanics and statics. For the first time, a new function is applied to a screw fixation-the implant is presented as a simple beam with an overhanging end. PMID:21966288

Filipov, Orlin

2011-10-01

26

Early complications of medial opening wedge high tibial osteotomy using autologous tricortical iliac bone graft and T-plate fixation  

Microsoft Academic Search

Despite several advantages of medial opening wedge high tibial osteotomy, this procedure has been noted to have a high rate of complications especially with the use of a spacer plate for fixation. We retrospectively evaluated the early complications of 138 medial opening wedge high tibial osteotomies done using autologous tricortical iliac bone graft and T-plate fixation(AO locking compression T-plate, Ti\\/3H

Dong Ju Chae; Gautam M. Shetty; Kook Hyun Wang; Antonio Santa Cruz Montalban Jr; Jong In Kim; Kyung Wook Nha

2011-01-01

27

Cannulated screw and hexapodal fixator reconstruction for compound upper tibial fractures  

PubMed Central

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

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

2014-01-01

28

A video guided solution for screw insertion in orthopedic plate fixation  

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

29

Magnetic resonance imaging analysis of the bioabsorbable Milagro™ interference screw for graft fixation in anterior cruciate ligament reconstruction  

Microsoft Academic Search

Ligament graft fixation with bioabsorbable interference screws is a standard procedure in cruciate ligament replacement. Previous\\u000a screw designs may resorb incompletely, and can cause osteolysis and sterile cysts despite being implanted for several years.\\u000a The aim of this study was to examine the in vivo degradation and biocompatibility of the new Milagro™ interference screw (Mitek,\\u000a Norderstedt, Germany). The Milagro™ interference screw

K.-H. Frosch; T. Sawallich; G. Schütze; A. Losch; T. Walde; P. Balcarek; F. Konietschke; K. M. Stürmer

2009-01-01

30

An investigation of the effects of hydroxyapatite coatings on the fixation strength of cortical screws.  

PubMed

Hydroxyapatite (HA) are commonly applied to orthopaedic implants for acceleration of osteointegration and so overcoming the loosening problems such as in cortical screws. Electrophoretic deposition (EPD) of hydroxyapatite was applied for coating of cortical screws in this work. The effects of hydroxyapatite-coated and uncoated cortical screws on insertion and extraction torque were investigated through in vivo experiments. Three groups of screws were undertaken: first group with no coating, second group coated with HA and the third group coated with HA+interlayer, a synthetic calcium silicate compound. Five sheep were operated, and 60 cortical (20 x 3) screws from those of groups were implanted in cortical femurs to observe the effect of HA and interlayer on screws. Results show that as an alternative to plasma spray coating method, the EPD process enables to produce a quick, easy, cheap and uniform adjustable coating layer. Also from biomechanical and SEM examinations, HA coating by EPD method of cortical screws resulted in extremely improved fixation with reduced risk of loosening problem. PMID:15694605

Yildirim, O S; Aksakal, B; Celik, H; Vangolu, Y; Okur, A

2005-04-01

31

Posterolateral lumbar and lumbosacral fusion with and without pedicle screw internal fixation.  

PubMed

Forty-seven patients who had lumbar or lumbosacral fusion with or without pedicle screw internal fixation by one surgeon for treatment of degenerative lumbar disease with clinical instability were retrospectively reviewed by an independent observer. Eighteen of the 21 patients whose fusions were internally fixed with the Variable Spinal Plating (VSP) system were available for review. A control group consisted of 27 patients who had fusion without internal fixation. The rate of pseudarthrosis did not significantly differ between the two groups (VSP group, 22%; versus control group, 26%). Twelve (67%) of the 18 patients treated with fusion and VSP instrumentation were considered to have had a good or excellent outcome, whereas 19 (70%) of the 27 patients treated by fusion without internal fixation had good or excellent results. Two VSP-instrumented patients had postoperative leg dysesthesias, whereas this complication was not observed in the control group. Bilateral posterolateral lumbar or lumbosacral fusion without internal fixation is as effective as and safer than fusion with pedicle screw instrumentation. PMID:1395279

Bernhardt, M; Swartz, D E; Clothiaux, P L; Crowell, R R; White, A A

1992-11-01

32

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

SciTech Connect

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

Huegli, R. W. [University Hospital, Basel, Department of Radiology (Switzerland)], E-mail: rhuegli@uhbs.ch; Messmer, P. [University Hospital, Zuerich, Division of Trauma Surgery (Switzerland); Jacob, A. L.; Regazzoni, P. [University Hospital, Basel, Department of Surgery, Trauma Unit (Switzerland); Styger, S. [University Hospital, Basel, Department of Radiology (Switzerland); Gross, T. [University Hospital, Basel, Department of Surgery, Trauma Unit (Switzerland)

2003-09-15

33

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

PubMed

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

Manfré, Luigi

2014-10-31

34

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

PubMed Central

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

2014-01-01

35

Intramedullary screw fixation in proximal fifth-metatarsal fractures in sports: clinical and biomechanical analysis  

Microsoft Academic Search

Introduction and purpose  Intramedullary screw fixation (ISF) of proximal fifth-metatarsal fractures is known as first treatment option in young, sports\\u000a active patients. No study analyzed functional and biomechanical outcome before. Hypothetically ISF leads to (1) a high bony\\u000a union rate within 12 weeks, (2) normal hindfoot eversion strength, and (3) normal gait and plantar pressure distribution.\\u000a \\u000a \\u000a \\u000a Methods  Fourteen out of 22 patients were

André Leumann; Geert Pagenstert; Peter Fuhr; Beat Hintermann; Victor Valderrabano

2008-01-01

36

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

NASA Astrophysics Data System (ADS)

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

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

2008-09-01

37

Biomechanical stability of a supra-acetabular pedicle screw Internal Fixation device (INFIX) vs External Fixation and plates for vertically unstable pelvic fractures  

PubMed Central

Background We have recently developed a subcutaneous anterior pelvic fixation technique (INFIX). This internal fixator permits patients to sit, roll over in bed and lie on their sides without the cumbersome external appliances or their complications. The purpose of this study was to evaluate the biomechanical stability of this novel supraacetabular pedicle screw internal fixation construct (INFIX) and compare it to standard internal fixation and external fixation techniques in a single stance pelvic fracture model. Methods Nine synthetic pelves with a simulated anterior posterior compression type III injury were placed into three groups (External Fixator, INFIX and Internal Fixation). Displacement, total axial stiffness, and the stiffness at the pubic symphysis and SI joint were calculated. Displacement and stiffness were compared by ANOVA with a Bonferroni adjustment for multiple comparisons Results The mean displacement at the pubic symphysis was 20, 9 and 0.8?mm for external fixation, INFIX and internal fixation, respectively. Plate fixation was significantly stiffer than the INFIX and external Fixator (P?=?0.01) at the symphysis pubis. The INFIX device was significantly stiffer than external fixation (P?=?0.017) at the symphysis pubis. There was no significant difference in SI joint displacement between any of the groups. Conclusions Anterior plate fixation is stiffer than both the INFIX and external fixation in single stance pelvic fracture model. The INFIX was stiffer than external fixation for both overall axial stiffness, and stiffness at the pubic symphysis. Combined with the presumed benefit of minimizing the complications associated with external fixation, the INFIX may be a more preferable option for temporary anterior pelvic fixation in situations where external fixation may have otherwise been used. PMID:23017093

2012-01-01

38

Management of Unstable Thoracolumbar Spinal Fractures by Pedicle Screws and Rods Fixation  

PubMed Central

Background: The thoracolumbar junction is the most common area of injury to the axial skeleton. Forces along the long stiff kyphotic thoracic spine switch abruptly into the mobile lordotic lumbar spine at the thoracolumbar junction. Goals of treatment are to obtain a painless, balanced, stable spine with optimum neurological function and maximum spine mobility. The present prospective study has evaluated the effectiveness of pedicle screw instrumentation in various fractures around the TL spine to overcome the complications encountered in the conservative line of management of these fractures. Materials & Methods: Thirty cases of fractures around the TL spine were operated with posterior pedicle screw fixation one or two level above and below the fracture. The cases were followed up for a mean of 9.5 months with radiological and neurological evaluation. Results: The average age groups of the patients studied were 21 to 53 years majority were males, fall from height being the predominant mode of injury involving the T12 and L1 vertebral body. The unstable burst fractures the most common type of fracture, radiological parameters sagittal angle and index were recorded pre and post-operatively. The neurological grading was done using the ASIA score. Follow-up was done for a minimum of 5 months where sagittal angle reduction achieved was 10.75 at final follow-up from 23.5 pre-operative. The sagittal index achieved at final follow-up was 72% compared to the pre-operative mean of 53%. The neurological improvement was regarded to be fair enough for the type of injury sustained and fixation achieved. Conclusion: We found that the application of posterior instrumentation using pedicle screw and rod resulted in a reasonable correction of the deformity with a significant reduction in recumbency-associated complications; the limiting factor being the small study group and short follow-up period. PMID:24701500

B.M., Muralidhar; Hegde, Durgaprasad; Hussain, P.S.B.

2014-01-01

39

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

PubMed Central

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.

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

2014-01-01

40

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

PubMed Central

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

Pesenti, Sebastien; Peltier, Emilie; Adetchessi, Tarek; Dufour, Henry; Fuentes, Stephane

2014-01-01

41

Comparison of Pullout Strength between 3.5-mm Fully Threaded, Bicortical Screws and 4.0-mm Partially Threaded, Cancellous Screws in the Fixation of Medial Malleolar Fractures  

Microsoft Academic Search

Displaced medial malleolus fractures are considered unstable and typically require open reduction and internal fixation for anatomic reduction and early joint range of motion. These fractures are usually fixated with either compression lag screws or tension band wiring depending on the fracture pattern, size of the distal fragment, and bone quality. When fracture fixation fails, it is typically in pullout

Jason D. Pollard; Ali Deyhim; Ryan B. Rigby; Nathan Dau; Christy King; Lawrence M. Fallat; Cynthia Bir

2010-01-01

42

Trans-sacral screw fixation in the treatment of high dyplastic developmental spondylolisthesis  

PubMed Central

We describe the case of a 67-year-old woman with L5-S1 ontogenetic spondylolisthesis treated with pedicle fixation associated with interbody arthrodesis performed with S1-L5 trans-sacral screwing according to the technique of Bartolozzi. The procedure was followed by a wide decompressive laminectomy. The patient had a progressive improvement of the symptoms which gradually disappeared in 12 mo. The radiograph at 6 and 12 mo showed complete fusion system. The choice of treatment in L5-S1 ontogenetic spondylolithesis is related to a correct clinical and diagnostic planning (X-ray, computer tomography magnetic resonance imaging, Measurement). In particular, the severity index and the square of unstable zone, and the standard measurements already described in the literature, are important to understand and to plane the correct surgical strategy, that require, in most of the times, fusion and interbody artrodesis. PMID:24303480

Landi, Alessandro; Marotta, Nicola; Mancarella, Cristina; Tarantino, Roberto; Delfini, Roberto

2013-01-01

43

Biomechanical study of the influence of stability for the pedicle screws fixation by injured vertebral screw when the pedicle cortex perforation.  

PubMed

Objective To explore the impact of pedicle cortex perforation on the stability of internal fixation of the vertebral body fracture,and to compare the stability of the vertebrae with pedicle cortex perforation after the injured vertebra transpedicular screw fixation by different ways. Methods A total of 36 fresh thoracic and lumbarvertebrae samples of adult sheep (T13-L1) were equally divided into four groups (A,B,C and D) by using the random number table method. The vertebral compression fracture was performed in the L1 vertebral body of the four groups using the Chiba's method. Four pedicle screws were fixed on the upper and lower injured vertebrae of four groups. In addition,the group C was fixed into a pedicle screw through the injured vertebrae;D group was set two pedicle screws through the injured vertebrae. Then the samples of group B,C,and D were removed a quarter of either side of lateral T14 thoracic pedicle,which was considered as the pedicle cortex perforation model. Four groups were performed fatigue test of 10 000 times by(300±105)N load. The drawing force of the screw and the stability of injured thoracolumbar vertebrae were measured and the differences in every group were compared. Results The axial compressive stiffness and maximum drawing force of screws in the other three groups were significantly higher than those in group B (all P=0.000). The maximum range of motion in four directions of group B were significantly larger than those of the other three groups (all P=0.000). The stiffness and the drawing force in groups C and D were significantly larger than those in the group A (all P=0.000),and the maximum range of motion in four directions of the two groups were lower than that of group A (P=0.002,P=0.005). Every testing indicator in group C had no significant difference when compared with group D (P>0.05). Conclusions The pedicle cortex perforation seriously affects the stability of the fractured vertebral body. The injured vertebra transpedicular screw can increase the stability of internal fixation. PMID:25176211

Shi, Yan; Feng, Su; Zhi-Min, Zhang

2014-08-31

44

The flying buttress construct for posterior spinopelvic fixation: a technical note  

PubMed Central

Background Posterior fusion of the spine to the pelvis in paediatric and adult spinal deformity is still challenging. Especially assembling of the posterior rod construct to the iliac screw is considered technically difficult. A variety of spinopelvic fixation techniques have been developed. However, extreme bending of the longitudinal rods or the use of 90-degree lateral offset connectors proved to be difficult, because the angle between the rod and the iliac screw varies from patient to patient. Methods We adopted a new spinopelvic fixation system, in which iliac screws are side-to-side connected to the posterior thoracolumbar rod construct, independent of the angle between the rod and the iliac screw. Open angled parallel connectors are used to connect short iliac rods from the posterior rod construct to the iliac screws at both sides. The construct resembles in form and function an architectural Flying Buttress, or lateral support arches, used in Gothic cathedrals. Results and discussion Three different cases that illustrate the Flying Buttress construct for spinopelvic fixation are reported here with the clinical details, radiographic findings and surgical technique used. Conclusion The Flying Buttress construct may offer an alternative surgical option for spinopelvic fixation in circumstances wherein coronal or sagittal balance cannot be achieved, for example in cases with significant residual pelvic obliquity, or in revision spinal surgery for failed lumbosacral fusion. PMID:21489256

2011-01-01

45

Guideline update for the performance of fusion procedures for degenerative disease of the lumbar spine. Part 12: pedicle screw fixation as an adjunct to posterolateral fusion.  

PubMed

The utilization of pedicle screw fixation as an adjunct to posterolateral lumbar fusion (PLF) has become routine, but demonstration of a definitive benefit remains problematic. The medical evidence indicates that the addition of pedicle screw fixation to PLF increases fusion rates when assessed with dynamic radiographs. More recent evidence, since publication of the 2005 Lumbar Fusion Guidelines, suggests a stronger association between radiographic fusion and clinical outcome, although, even now, no clear correlation has been demonstrated. Although several reports suggest that clinical outcomes are improved with the addition of pedicle screw fixation, there are conflicting findings from similarly classified evidence. Furthermore, the largest contemporary, randomized, controlled study on this topic failed to demonstrate a significant clinical benefit with the use of pedicle screw fixation in patients undergoing PLF for chronic low-back pain. This absence of proof should not, however, be interpreted as proof of absence. Several limitations continue to compromise these investigations. For example, in the majority of studies the sample size is insufficient to detect small increments in clinical outcome that may be observed with pedicle screw fixation. Therefore, no definitive statement regarding the efficacy of pedicle screw fixation as a means to improve functional outcomes in patients undergoing PLF for chronic low-back pain can be made. There appears to be consistent evidence suggesting that pedicle screw fixation increases the costs and complication rate of PLF. High-risk patients, including (but not limited to) patients who smoke, patients who are undergoing revision surgery, or patients who suffer from medical conditions that may compromise fusion potential, may appreciate a greater benefit with supplemental pedicle screw fixation. It is recommended, therefore, that the use of pedicle screw fixation as a supplement to PLF be reserved for those patients in whom there is an increased risk of nonunion when treated with only PLF. PMID:24980589

Groff, Michael W; Dailey, Andrew T; Ghogawala, Zoher; Resnick, Daniel K; Watters, William C; Mummaneni, Praveen V; Choudhri, Tanvir F; Eck, Jason C; Sharan, Alok; Wang, Jeffrey C; Dhall, Sanjay S; Kaiser, Michael G

2014-07-01

46

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

PubMed Central

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

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

2013-01-01

47

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

PubMed Central

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

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

2014-01-01

48

Analysis of failure following anterior screw fixation of Type II odontoid fractures in geriatric patients.  

PubMed

Anterior screw fixation of Type II odontoid fractures has been recommended. Only few publications analyse the mechanism of failure in geriatric patients. We reviewed 18 male and 15 female patients aged 65 and above for parameters that influence the development of postoperative loss of correction, delayed union or non-union. Patients were stratified in two groups: 21 cases in Group A (union) and 12 patients in Group B (loss of correction, delayed union, non-union, revision surgery). Statistically significant correlation (p < 0.05) could be detected between failure to heal and: (1) degenerative changes in the atlanto-odontoid joint, (2) severity of osteoporosis in the odontoid process, (3) posterior oblique fracture type, (4) suboptimal fracture reduction, (5) suboptimal position of implant following demanding intraoperative conditions, (6) quality of fracture compression and (7) severity of fracture comminution. The overall morbidity and mortality rates were 29.0 and 8.6%, respectively. Our results indicate that these factors should be addressed regarding the selection of the operative treatment method in the geriatric patient. PMID:21728075

Osti, Michael; Philipp, Helmut; Meusburger, Berthold; Benedetto, Karl Peter

2011-11-01

49

Biomechanical In Vitro - Stability Testing on Human Specimens of a Locking Plate System Against Conventional Screw Fixation of a Proximal First Metatarsal Lateral Displacement Osteotomy  

PubMed Central

Introduction: The aim of this study was to examine resistance to angulation and displacement of the internal fixation of a proximal first metatarsal lateral displacement osteotomy, using a locking plate system compared with a conventional crossed screw fixation. Materials and Methodology: Seven anatomical human specimens were tested. Each specimen was tested with a locking screw plate as well as a crossed cancellous srew fixation. The statistical analysis was performed by the Friedman test. The level of significance was p = 0.05. Results: We found larger stability about all three axes of movement analyzed for the PLATE than the crossed screws osteosynthesis (CSO). The Friedman test showed statistical significance at a level of p = 0.05 for all groups and both translational and rotational movements. Conclusion: The results of our study confirm that the fixation of the lateral proximal first metatarsal displacement osteotomy with a locking plate fixation is a technically simple procedure of superior stability. PMID:22675409

Arnold, Heino; Stukenborg-Colsman, Christina; Hurschler, Christof; Seehaus, Frank; Bobrowitsch, Evgenij; Waizy, Hazibullah

2012-01-01

50

Minimally invasive transforaminal lumbar interbody fusion with unilateral pedicle screw fixation: comparison between primary and revision surgery.  

PubMed

Minimally invasive surgery with a transforaminal lumbar interbody fusion (MIS TLIF) is an important minimally invasive fusion technique for the lumbar spine. Lumbar spine reoperation is challenging and is thought to have greater complication risks. The purpose of this study was to compare MIS TLIF with unilateral screw fixation perioperative results between primary and revision surgeries. This was a prospective study that included 46 patients who underwent MIS TLIF with unilateral pedicle screw. The patients were divided into two groups, primary and revision MIS TLIF, to compare perioperative results and complications. The two groups were similar in age, sex, and level of operation, and were not significantly different in the length of follow-up or clinical results. Although dural tears were more common with the revision group (primary 1; revision 4), operation time, blood loss, total perioperative complication, and fusion rates were not significantly different between the two groups. Both groups showed substantial improvements in VAS and ODI scores one year after surgical treatment. Revision MIS TLIF performed by an experienced surgeon does not necessarily increase the risk of perioperative complication compared with primary surgery. MIS TLIF with unilateral pedicle screw fixation is a valuable option for revision lumbar surgery. PMID:24949483

Kang, Moo Sung; Park, Jeong Yoon; Kim, Kyung Hyun; Kuh, Sung Uk; Chin, Dong Kyu; Kim, Keun Su; Cho, Yong Eun

2014-01-01

51

Posterior short segment pedicle screw fixation and TLIF for the treatment of unstable thoracolumbar/lumbar fracture  

PubMed Central

Background Currently, Posterior Short Segment Pedicle Screw Fixation is a popular procedure for treating unstable thoracolumbar/lumbar burst fracture. But progressive kyphosis and a high rate of hardware failure because of lack of the anterior column support remains a concern. The efficacy of different methods remains debatable and each technique has its advantages and disadvantages. Methods A consecutive series of 20 patients with isolated thoracolumbar/lumbar burst fractures were treated by posterior short segment pedicle screw fixation and transforaminal thoracolumbar/lumbar interbody fusion (TLIF) between January 2005 and December 2007. All patients were followed up for a minimum of 2 years. Demographic data, neurologic status, anterior vertebral body heights, segmental Cobb angle and treatment-related complications were evaluated. Results The mean operative time was 167 minutes (range, 150–220). Blood loss was 450 ~ 1200 ml, an average of 820 ml. All patients recovered with solid fusion of the intervertebral bone graft, without main complications like misplacement of the pedicle screw, nerve or vessel lesion or hard ware failure. The post-operative radiographs demonstrated a good fracture reduction and it was well maintained until the bone graft fusion. Neurological recovery of one to three Frankel grade was seen in 14 patients with partial neurological deficit, three grades of improvement was seen in one patient, two grades of improvement was observed in 6 patients and one grade of improvement was found in 6 patients. All the 6 patients with no paraplegia on admission remained neurological intact, and in one patient with Frankel D on admission no improvement was observed. Conclusion Posterior short-segment pedicle fixation in conjunction with TLIF seems to be a feasible option in the management of selected thoracolumbar/lumbar burst fractures, thereby addressing all the three columns through a single approach with less trauma and good results. PMID:24517217

2014-01-01

52

Analysis of stress induced by screws in the vertebral fixation system  

PubMed Central

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

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

2014-01-01

53

The Retroacetabular Angle Determines the Safe Angle for Screw Placement in Posterior Acetabular Fracture Fixation  

PubMed Central

Introduction. A method for the determination of safe angles for screws placed in the posterior acetabular wall based on preoperative computed tomography (CT) is described. It defines a retroacetabular angle and determines its variation in the population. Methods. The retroacetabular angle is the angle between the retroacetabular surface and the tangent to the posterior acetabular articular surface. Screws placed through the marginal posterior wall at an angle equal to the retroacetabular angle are extraarticular. Medial screws can be placed at larger angles whose difference from the retroacetabular angle is defined as the allowance angles. CT scans of all patients with acetabular fractures treated in our institute between September 2002 to July 2007 were used to measure the retroacetabular angle and tangent. Results. Two hundred thirty one patients were included. The average (range) age was 42 (15–74) years. The average (range) retroacetabular angle was 39 (30–47) degrees. The average (range) retroacetabular tangent was 36 (30–45)?mm. Conclusions. Placing the screws at an average (range) angle of 39 (33–47) degrees of anterior inclination with the retroacetabular surface makes them extraarticular. Angles for medial screws are larger. Safe angles can be calculated preoperatively with a computer program. PMID:24959359

Tadros, Ayman M. A.; Oxland, Thomas R.; O'Brien, Peter

2013-01-01

54

Hybrid computer-guided and minimally open surgery: anterior lumbar interbody fusion and translaminar screw fixation  

Microsoft Academic Search

Less invasiveness is the way forward for spinal surgery. Minimal disruption of tissue, preservation of muscle function, and restoration of normal spinal alignment are still the goals of most surgical procedures. An anterior lumbar fusion technique using a less invasive procedure with the addition of translaminar screws is described. The autograft is harvested from the vertebral body, thus avoiding the

N. Kumar; A. Wild; J. K. Webb; M. Aebi

2000-01-01

55

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

PubMed Central

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

Patzer, Thilo; Kircher, Jorn; Krauspe, Ruediger

2012-01-01

56

Biomechanical comparison of unilateral and bilateral pedicle screws fixation for transforaminal lumbar interbody fusion after decompressive surgery -- a finite element analysis  

PubMed Central

Background Little is known about the biomechanical effectiveness of transforaminal lumbar interbody fusion (TLIF) cages in different positioning and various posterior implants used after decompressive surgery. The use of the various implants will induce the kinematic and mechanical changes in range of motion (ROM) and stresses at the surgical and adjacent segments. Unilateral pedicle screw with or without supplementary facet screw fixation in the minimally invasive TLIF procedure has not been ascertained to provide adequate stability without the need to expose on the contralateral side. This study used finite element (FE) models to investigate biomechanical differences in ROM and stress on the neighboring structures after TLIF cages insertion in conjunction with posterior fixation. Methods A validated finite-element (FE) model of L1-S1 was established to implant three types of cages (TLIF with a single moon-shaped cage in the anterior or middle portion of vertebral bodies, and TLIF with a left diagonally placed ogival-shaped cage) from the left L4-5 level after unilateral decompressive surgery. Further, the effects of unilateral versus bilateral pedicle screw fixation (UPSF vs. BPSF) in each TLIF cage model was compared to analyze parameters, including stresses and ROM on the neighboring annulus, cage-vertebral interface and pedicle screws. Results All the TLIF cages positioned with BPSF showed similar ROM (<5%) at surgical and adjacent levels, except TLIF with an anterior cage in flexion (61% lower) and TLIF with a left diagonal cage in left lateral bending (33% lower) at surgical level. On the other hand, the TLIF cage models with left UPSF showed varying changes of ROM and annulus stress in extension, right lateral bending and right axial rotation at surgical level. In particular, the TLIF model with a diagonal cage, UPSF, and contralateral facet screw fixation stabilize segmental motion of the surgical level mostly in extension and contralaterally axial rotation. Prominent stress shielded to the contralateral annulus, cage-vertebral interface, and pedicle screw at surgical level. A supplementary facet screw fixation shared stresses around the neighboring tissues and revealed similar ROM and stress patterns to those models with BPSF. Conclusions TLIF surgery is not favored for asymmetrical positioning of a diagonal cage and UPSF used in contralateral axial rotation or lateral bending. Supplementation of a contralateral facet screw is recommended for the TLIF construct. PMID:22591664

2012-01-01

57

Anterior single screw fixation of odontoid fracture with intraoperative isoC 3-dimensional imaging  

Microsoft Academic Search

Purpose  The purpose of this study was to assess the value of isocentric C-arm three-dimensional (Iso-C 3D) fluoroscopy for the insertion\\u000a of an anterior odontoid screw. The results of the Iso-C 3D group were compared with that of an historic control group using\\u000a conventional fluoroscopy.\\u000a \\u000a \\u000a \\u000a \\u000a Methods  Twenty-nine patients diagnosed with type II or rostral-type III odontoid fractures were treated with a single

Yong Liang Yang; Bai Sheng Fu; Rachel W. Li; Paul N. Smith; Wei Dong Mu; Lian Xin Li; Dong Sheng Zhou

58

Comparison between the rigidity of bicortical screws and a miniplate for fixation of a mandibular setback after a simulated bilateral sagittal split osteotomy  

Microsoft Academic Search

Purpose: This investigation compared the biomechanical stability of three bicortical screws with that of a single four-hole miniplate after 5-mm mandibular setback after a bilateral sagittal split osteotomy (BSSO) in cadaver mandibles.Materials and Methods: Thirty human cadaver hemimandibles underwent BSSO followed by two different rigid fixation techniques. All specimens had no third molar, bony pathology, or evidence of mandibular fracture,

Wichit Tharanon

1998-01-01

59

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

PubMed Central

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

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

2013-01-01

60

The dynamic condylar screw in the management of subtrochanteric fractures: does judicious use of biological fixation enhance overall results?  

Microsoft Academic Search

Subtrochanteric fractures are fraught with certain anatomic, biologic and biomechanical challenges. Evolution of implants\\u000a like the Gamma nail, fixed-angle nail plates, compression hip screws and dynamic hip screws with trochanteric stabilization\\u000a plates underlines a persistent quest for a better implant. We studied the dynamic condylar screw DCS as an implant on a series\\u000a of 30 consecutive patients with subtrochanteric fractures.

Manzoor Ahmed Halwai; Shabir Ahmed Dhar; Mohammed Iqbal Wani; Mohammed Farooq Butt; Bashir Ahmed Mir; Murtaza Fazal Ali; Imtiyaz Hussain Dar

2007-01-01

61

[A new design of internal fixation for scoliosis-multi-screw fixed distractor-compressor via the vertebral pedicle and its clinical application].  

PubMed

A new scoliotone, which is made up of screws, sockets, clamps, distraction rod and compression rod, was used stabilize immobilization of the spine in 10 cases. This scoliotone can produce free motion in three different levels, and has a strong power of fixation, distraction, compression and antitraction. In 10 cases when the patient's spinal curvature (cobb's angle) was less than 50 degrees, the average range of correction was 78.2% and the correction rate of kyphosis peak was 90%. When the spinal curvature was between 50 to 100 degrees, the average range of correction was 68.2%, and the correction rate of kyphosis peak was 87.7%. If the spinal curvature was more than 100 degrees, the average range of correction rate of kyphosis peak was 82%. After the operation, the patient might not be immobilized. In this paper, the biomechanical features of the vertebral arch, internal fixation and correction of kyphosis peak were discussed. PMID:1813237

Chi, Y L

1991-08-01

62

C7 intralaminar screw placement, an alternative to lateral mass or pedicle fixation for treatment of cervical spondylytic myelopathy, kyphotic deformity, and trauma: A case report and technical note  

PubMed Central

Background: The authors present a case to illustrate the necessity and technical feasibility of C7 laminar screw placement for treatment of sub-axial cervical spondylitic myelopathy. The indications for C7 lateral mass screw placement was required internal fixation, with small lateral masses (8 mm) and pedicles (4 mm). Case Description: A 67-year-old female with compressive myelopathy after a fall from standing is presented. Magnetic resonance (MR) imaging of the cervical spine showed severe C3-6 spondylosis with canal and foraminal compromise. Computed tomography of the cervical spine confirmed the MR imaging findings as well as showed suboptimal lateral mass and pedicles for screw placement. The patient underwent a C3-6 laminectomy, C3-6 lateral mass, and C7 laminar screw placement. Postoperatively, the patient recovered without complication. Conclusion: Internal fixation of the cervical spine after iatrogenic destabilization by decompression of neural elements secondary to advanced spondylosis can be technically challenging. Anatomical landmarks needed for safe placement of lateral mass or pedicle instrumentation are often distorted by the patients’ advanced pathology or Inherent biology. The C7 screw is a key structural element to a long construct and therefore necessitates large lateral masses or pedicles to safely place a functional screw. C7 laminar screws may be placed safely without fluoroscopic guidance when sufficient C7 lateral mass or pedicle screws are not possible or with undue risk. PMID:24575319

Koltz, Michael T.; Maulucci, Christopher M.; Sansur, Charles A.; Hamilton, D. Kojo

2014-01-01

63

Role of the O-arm and Computer-assisted Navigation of Safe Screw Fixation in Children with Traumatic Rotatory Atlantoaxial Subluxation  

PubMed Central

Study Design A retrospective analysis of 7 patients with traumatic rotatory atlanto-axial subluxation. Overview of Literature Cases of traumatic rotatory atlantoaxial subluxation in children are difficult to be stabilized. Surgical challenges include: narrow pedicles, medial vertebral arteries, vertebral artery anomalies, fractured pedicles or lateral masses, and fixed subluxation. The use of O-arm and computer-assisted navigation are still tested as aiding tools in such operative modalities. Purpose Report of clinical series for evaluation of the safety of use of the O-arm and computed assisted-navigation in screw fixation in children with traumatic rotatory atlantoaxial subluxation. Methods In the present study, 7 cases of rotatory atlantoaxial traumatic subluxation were operated between December 2009 and March 2011. All patient-cases had undergone open reduction and instrumentation using atlas lateral mass and axis pedicle screws with intraoperative O-arm with computer-assisted navigation. Results All hardware was safely placed in the planned trajectories in all the 7 cases. Intraoperative O-arm and computer assisted-navigation were useful in securing neural and vascular tissues safety with tough-bony purchases of the hardware from the first and only trial of application with sufficient reduction of the subluxation. Conclusions Successful surgery is possible with using the intraoperative O-arm and computer-assisted navigation in safe and proper placement of difficult atlas lateral mass and axis pedicle screws for rotatory atlantoaxial subluxation in children. PMID:23275810

Orief, Tamer; Almusrea, Khaled; Alfawareh, Mohamed; Soualmi, Lahbib; Orz, Yasser

2012-01-01

64

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

PubMed Central

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

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

2014-01-01

65

The flying buttress construct for posterior spinopelvic fixation: a technical note  

Microsoft Academic Search

Background  Posterior fusion of the spine to the pelvis in paediatric and adult spinal deformity is still challenging. Especially assembling\\u000a of the posterior rod construct to the iliac screw is considered technically difficult. A variety of spinopelvic fixation techniques\\u000a have been developed. However, extreme bending of the longitudinal rods or the use of 90-degree lateral offset connectors proved\\u000a to be difficult,

Barend J van Royen; Martijn van Dijk; Dirk PH van Oostveen; Bas van Ooij; Agnita Stadhouder

2011-01-01

66

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

Microsoft Academic Search

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

Deniz Belen; Serkan Simsek; Kazim Yigitkanli; Murad Bavbek

2006-01-01

67

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

PubMed Central

Study Design An in-vitro study. Purpose The current study is aimed at investigating the differences in stability between short posterior fixation (SPF), hybrid posterior fixation (HPF), and long posterior fixation (LPF) with and without anterior column augmentation using calcium phosphate bone cement (CaP) for treating burst fractures (BFs). Overview of Literature The ideal treatment for thoracolumbar BF is controversial regarding the use of short or LPF constructs. Methods Seven human thoracolumbar spines (T9-L4) were tested on a six degree of freedom spine simulator in three physiologic planes, flexion-extension (FE), lateral bending (LB), and axial rotation (AR). Tested surgical constructs included the following: intact, injury (BF), SPF (T12-L2), HPF (T11-L2), LPF (T11-L3), SPF+CaP, HPF+CaP, LPF+CaP, and CaP alone (CaP). Range of motion (ROM) was recorded at T12-L2 in FE, LB, and AR. Results The reduction in mean ROM trended as follows: LPF>HPF>SPF. Only LPF constructs and HPF with anterior column augmentation significantly reduced mean ROM in FE and LB compared to the intact state. All instrumented constructs (SPF, HPF, and LPF) significantly reduced ROM in FE and LB compared to the injured condition. Furthermore, the instrumented constructs did not provide significant rotational stability. Injecting CaP provided minimal additional stability. Conclusions For the injury created, LPF and HPF provided better stability than SPF with and without anterior column augmentation. Therefore, highly unstable fractures may require extended, long or hybrid fusion constructs for optimum stability. PMID:24596603

Peters, Todd; Hussain, Mir; Khalil, Saif

2014-01-01

68

Quantitative anatomic basis of antegrade lag screw placement in posterior column of acetabulum  

Microsoft Academic Search

Background  Lag screw fixation has been recommended for treatment of acetabular and pelvic fracture for several years. The aim of the\\u000a present study was to determine the projection of the axis of the posterior column on the inner table of the iliac wing in\\u000a the supra-acetabular region.\\u000a \\u000a \\u000a \\u000a Methods  Thirty adult dried bony hemipelves specimens and other five intact adult dried pelvic specimens

Wei-dong Mu; Xian-quan Wang; Tang-hong Jia; Dong-sheng Zhou; Ai-xin Cheng

2009-01-01

69

A case of hypertrophic ischial tuberosity non-union treated by closed wedge osteotomy and plate and screws fixation.  

PubMed

We report a case of a 21-year-old male with massive hypertrophic ischial tuberosity non-union. Among multiple other lesions, the patient suffered an open avulsion of the ischial tuberosity in a severe traffic accident in adolescence. A conservative treatment was decided for the avulsion. Because of sciatic pain and difficulties while sitting since the age of 19, X-rays were realised and showed a massive hypertrophic non-union of the ischial tuberosity. To preserve hamstring origin with bone attachment, the non-union was mobilised, reduced by osteotomy and fixed by plate and screws. At the follow up of one year, the patient sits without pain and can work without interruption. Avulsion of the ischial tuberosity is infrequent and the diagnosis is often missed (Gidwani et al., BMJ 329:99-100, 2004; Hamada, Clin Orthop 31:117-130, 1963). This lesion is more often seen in adolescence as the consequence of a sport injury (Gidwani et al., BMJ 329:99-100, 2004). Treatment is generally conservative and outcome good. Surgical therapy is only needed in cases with severe displacement. Long-term problems are seldom and surgical therapy to solve these problems is the exception. PMID:23411936

Putman, S; Rommens, P M

2013-04-01

70

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

PubMed

This retrospective study compares efficacy and safety of balloon kyphoplasty (BK) with calcium phosphate (Group A) versus KIVA implant with PMMA (Group B) reinforced with three vertebrae pedicle screw constructs for A2 and A3 single fresh non-osteoporotic lumbar (L1-L4) fractures in 38 consecutive age- and diagnosis-matched patient populations. Extracanal leakage of both low-viscosity PMMA and calcium phosphate (CP) as well as the following roentgenographic parameters: segmental kyphosis (SKA), anterior (AVBHr) and posterior (PVBHr) vertebral body height ratio, spinal canal encroachment (SCE) clearance, and functional outcome measures: VAS and SF-36, were recorded and compared between the two groups. All patients in both groups were followed for a minimum 26 (Group A) and 25 (Group B) months. Extracanal CP and PMMA leakage was observed in four (18 %) and three (15 %) vertebrae/patients of group A and B, respectively. Hybrid fixation improved AVBHr, SKA, SCE, but PVBHr only in group B. VAS and SF-36 improved postoperatively in the patients of both groups. Short-segment construct with the novel KIVA implant restored better than BK-fractured lumbar vertebral body, but this had no impact in functional outcome. Since there was no leakage difference between PMMA and calcium phosphate and no short-term adverse related to PMMA use were observed, we advice the use of PMMA in fresh traumatic lumbar fractures. PMID:23982115

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

2014-07-01

71

Posterior transodontoid fixation: A new fixation (Kotil) technique.  

PubMed

Anterior odontoid screw fixation or posterior C1-2 fusion techniques are routinely used in the treatment of Type II odontoid fractures, but these techniques may be inadequate in some types of odontoid fractures. In this new technique (Kotil technique), through a posterior bilateral approach, transarticular screw fixation was performed at the non-dominant vertebral artery (VA) side and posterior transodontoid fixation technique was performed at the dominant VA side. C1-2 complex fusion was aimed with unilateral transarticular fixation and odontoid fixation with posterior transodontoid screw fixation. Cervical spinal computed tomography (CT) of a 40-year-old male patient involved in a motor vehicle accident revealed an anteriorly dislocated Type II oblique dens fracture, not reducible by closed traction. Before the operation, the patient was found to have a dominant right VA with Doppler ultrasound. He was operated through a posterior approach. At first, transarticular screw fixation was performed at the non-dominant (left) side, and then fixation of the odontoid fracture was achieved by directing the contralateral screw (supplemental screw) medially and toward the apex. Cancellous autograft was scattered for fusion without the need for structural bone graft or wiring. Postoperative cervical spinal CT of the patient revealed that stabilization was maintained with transarticular screw fixation and reduction and fixation of the odontoid process was achieved completely by posterior transodontoid screw fixation. The patient is at the sixth month of follow-up and complete fusion has developed. With this new surgical technique, C1-2 fusion is maintained with transarticular screw fixation and odontoid process is fixed by concomitant contralateral posterior transodontoid screw (supplemental screw) fixation; thus, this technique both stabilizes the C1-2 complex and fixes the odontoid process and the corpus in atypical odontoid fractures, appearing as an alternative new technique among the previously defined C1-C2 fixation techniques in eligible cases. PMID:22013375

Kotil, Kad?r; Köksal, Neslihan Sütpideler; Kayac?, Selim

2011-01-01

72

Posterior transodontoid fixation: A new fixation (Kotil) technique  

PubMed Central

Anterior odontoid screw fixation or posterior C1-2 fusion techniques are routinely used in the treatment of Type II odontoid fractures, but these techniques may be inadequate in some types of odontoid fractures. In this new technique (Kotil technique), through a posterior bilateral approach, transarticular screw fixation was performed at the non-dominant vertebral artery (VA) side and posterior transodontoid fixation technique was performed at the dominant VA side. C1-2 complex fusion was aimed with unilateral transarticular fixation and odontoid fixation with posterior transodontoid screw fixation. Cervical spinal computed tomography (CT) of a 40-year-old male patient involved in a motor vehicle accident revealed an anteriorly dislocated Type II oblique dens fracture, not reducible by closed traction. Before the operation, the patient was found to have a dominant right VA with Doppler ultrasound. He was operated through a posterior approach. At first, transarticular screw fixation was performed at the non-dominant (left) side, and then fixation of the odontoid fracture was achieved by directing the contralateral screw (supplemental screw) medially and toward the apex. Cancellous autograft was scattered for fusion without the need for structural bone graft or wiring. Postoperative cervical spinal CT of the patient revealed that stabilization was maintained with transarticular screw fixation and reduction and fixation of the odontoid process was achieved completely by posterior transodontoid screw fixation. The patient is at the sixth month of follow-up and complete fusion has developed. With this new surgical technique, C1-2 fusion is maintained with transarticular screw fixation and odontoid process is fixed by concomitant contralateral posterior transodontoid screw (supplemental screw) fixation; thus, this technique both stabilizes the C1-2 complex and fixes the odontoid process and the corpus in atypical odontoid fractures, appearing as an alternative new technique among the previously defined C1-C2 fixation techniques in eligible cases. PMID:22013375

Kotil, Kad?r; Köksal, Neslihan sütpideler; Kayac?, Selim

2011-01-01

73

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

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

2014-01-01

74

Resorbable screws versus pins for optimal transplant fixation (SPOT) in anterior cruciate ligament replacement with autologous hamstring grafts: rationale and design of a randomized, controlled, patient and investigator blinded trial [ISRCTN17384369  

PubMed Central

Background Ruptures of the anterior cruciate ligament (ACL) are common injuries to the knee joint. Arthroscopic ACL replacement by autologous tendon grafts has established itself as a standard of care. Data from both experimental and observational studies suggest that surgical reconstruction does not fully restore knee stability. Persisting anterior laxity may lead to recurrent episodes of giving-way and cartilage damage. This might at least in part depend on the method of graft fixation in the bony tunnels. Whereas resorbable screws are easy to handle, pins may better preserve graft tension. The objective of this study is to determine whether pinning of ACL grafts reduces residual anterior laxity six months after surgery as compared to screw fixation. Design/ Methods SPOT is a randomised, controlled, patient and investigator blinded trial conducted at a single academic institution. Eligible patients are scheduled to arthroscopic ACL repair with triple-stranded hamstring grafts, conducted by a single, experienced surgeon. Intraoperatively, subjects willing to engage in this study will be randomised to transplant tethering with either resorbable screws or resorbable pins. No other changes apply to locally established treatment protocols. Patients and clinical investigators will remain blinded to the assigned fixation method until the six-month follow-up examination. The primary outcome is the side-to-side (repaired to healthy knee) difference in anterior translation as measured by the KT-1000 arthrometer at a defined load (89 N) six months after surgery. A sample size of 54 patients will yield a power of 80% to detect a difference of 1.0 mm ± standard deviation 1.2 mm at a two-sided alpha of 5% with a t-test for independent samples. Secondary outcomes (generic and disease-specific measures of quality of life, magnetic resonance imaging morphology of transplants and devices) will be handled in an exploratory fashion. Conclusion SPOT aims at showing a reduction in anterior knee laxity after fixing ACL grafts by pins compared to screws. PMID:15723704

Stengel, Dirk; Matthes, Gerrit; Seifert, Julia; Tober, Volker; Mutze, Sven; Rademacher, Grit; Ekkernkamp, Axel; Bauwens, Kai; Wich, Michael; Casper, Dirk

2005-01-01

75

Predictive Factors for a Kyphosis Recurrence Following Short-Segment Pedicle Screw Fixation Including Fractured Vertebral Body in Unstable Thoracolumbar Burst Fractures  

PubMed Central

Objective The technique of short segment pedicle screw fixation (SSPSF) has been widely used for stabilization in thoracolumbar burst fractures (TLBFs), but some studies reported high rate of kyphosis recurrence or hardware failure. This study was to evaluate the results of SSPSF including fractured level and to find the risk factors concerned with the kyphosis recurrence in TLBFs. Methods This study included 42 patients, including 25 males and 17 females, who underwent SSPSF for stabilization of TLBFs between January 2003 and December 2010. For radiologic assessments, Cobb angle (CA), vertebral wedge angle (VWA), vertebral body compression ratio (VBCR), and difference between VWA and Cobb angle (DbVC) were measured. The relationships between kyphosis recurrence and radiologic parameters or demographic features were investigated. Frankel classification and low back outcome score (LBOS) were used for assessment of clinical outcomes. Results The mean follow-up period was 38.6 months. CA, VWA, and VBCR were improved after SSPSF, and these parameters were well maintained at the final follow-up with minimal degree of correction loss. Kyphosis recurrence showed a significant increase in patients with Denis burst type A, load-sharing classification (LSC) score >6 or DbVC >6 (p<0.05). There were no patients who worsened to clinical outcome, and there was no significant correlation between kyphosis recurrence and clinical outcome in this series. Conclusion SSPSF including the fractured vertebra is an effective surgical method for restoration and maintenance of vertebral column stability in TLBFs. However, kyphosis recurrence was significantly associated with Denis burst type A fracture, LSC score >6, or DbVC >6. PMID:25368766

Kim, Gun-Woo; Hur, Hyuk; Lee, Jung-Kil; Kim, Jae-Hyoo; Kim, Soo-Han

2014-01-01

76

Simultaneous anterior and posterior screw fixations confined to the axis for stabilization of a 3-part fracture of the axis (odontoid, dens, and hangman fractures): report of 2 cases.  

PubMed

Fractures of the axis are considered to be one of the most common injuries to the cervical spine, accounting for more than 20% of all cervical spine fractures. Multiple fractures of the axis are much rarer, accounting for 1% of all cervical fractures. Management of such complex fractures is still challenging, and there is no strong consensus for the treatment. The authors describe the cases of 2 patients who presented with 3-part fractures of the axis consisting of an odontoid Type II fracture and a Levine-Edwards Type IA fracture, which were treated with concurrent insertion of an anterior odontoid screw and bilateral posterior pedicle screws. The cases presented were characterized by 1) a Type II odontoid fracture; 2) a Type IA traumatic spondylolisthesis with no or a little translation and angulation of C-2 on C-3 in a ring fracture of the axis; and 3) no disorders at the C2-3 disc on MR images. Therefore, the authors performed surgery confined to the axis by concurrently inserting an anterior odontoid screw and posterior bilateral pedicle screws without arthrodesis of C2-3. This was followed with cervical soft collar fixation for only 1-2 weeks. The outcomes were favorable, including good osteosynthesis, high primary stability, early patient mobilization, and preserved range of motion of the cervical spine at C2-3 as well as at C1-2. PMID:24409982

Shinbo, Jun; Sameda, Hiroaki; Ikenoue, Sumio; Takase, Kan; Yamaguchi, Takeshi; Hashimoto, Eiko; Enomoto, Takahiro; Kanazuka, Aya; Mimura, Masaya

2014-03-01

77

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

PubMed

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

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

2013-10-01

78

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

PubMed Central

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

Troussel, Serge

2007-01-01

79

Suture Bridge Fixation of a Femoral Condyle Traumatic Osteochondral Defect  

Microsoft Academic Search

Internal fixation of a traumatic osteochondral defect presents a challenge in terms of obtaining anatomic reduction, fixation,\\u000a and adequate compression for healing. Fixation with countersunk intraarticular screws, Herbert screws, bioabsorbable screws\\u000a and pins, mini-cancellous screws, and glue tissue adhesive have been reported with varying results. We present an alternative\\u000a fixation method used in two patients for femoral condylar defects that

Andrea L. Bowers; G. Russell Huffman

2008-01-01

80

Comparison of Cotrel-Dubousset pedicle screws and hooks in the treatment of idiopathic scoliosis  

Microsoft Academic Search

Eighty-two patients with idiopathic scoliosis were treated by Cotrel-Dubousset instrumentation between 1987 and 1991. Twenty were treated with hooks only, 47 with screws and hooks, and 15 with screws only. The methods were compared and the findings showed that screw fixation can be used in the thoracic spine without neurological complications. The screws provided immediate stability with rigid fixation, together

S. I. Suk; C. K. Lee; H. J. Min; K. H. Cho; J. H. Oh

1994-01-01

81

Geometric accuracy of 3D coordinates of the Leksell stereotactic skull frame in 1.5 Tesla- and 3.0 Tesla-magnetic resonance imaging: a comparison of three different fixation screw materials.  

PubMed

We assessed the geometric distortion of 1.5-Tesla (T) and 3.0-T magnetic resonance (MR) images with the Leksell skull frame system using three types of cranial quick fixation screws (QFSs) of different materials-aluminum, aluminum with tungsten tip, and titanium-for skull frame fixation. Two kinds of acrylic phantoms were placed on a Leksell skull frame using the three types of screws, and were scanned with computed tomography (CT), 1.5-T MR imaging and 3.0-T MR imaging. The 3D coordinates for both strengths of MR imaging were compared with those for CT. The deviations of the measured coordinates at selected points (x = 50, 100 and 150; y = 50, 100?and 150) were indicated on different axial planes (z = 50, 75, 100, 125?and 150). The errors of coordinates with QFSs of aluminum, tungsten-tipped aluminum, and titanium were <1.0, 1.0 and 2.0 mm in the entire treatable area, respectively, with 1.5 T. In the 3.0-T field, the errors with aluminum QFSs were <1.0 mm only around the center, while the errors with tungsten-tipped aluminum and titanium were >2.0 mm in most positions. The geometric accuracy of the Leksell skull frame system with 1.5-T MR imaging was high and valid for clinical use. However, the geometric errors with 3.0-T MR imaging were larger than those of 1.5-T MR imaging and were acceptable only with aluminum QFSs, and then only around the central region. PMID:25034732

Nakazawa, Hisato; Mori, Yoshimasa; Yamamuro, Osamu; Komori, Masataka; Shibamoto, Yuta; Uchiyama, Yukio; Tsugawa, Takahiko; Hagiwara, Masahiro

2014-11-01

82

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

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

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

2014-04-01

83

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

PubMed Central

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

Brahmajoshyula, Venkatramana; Mayi, Shivanand; Teegala, Suman

2014-01-01

84

Bioabsorbable interference screw fixation of distal biceps ruptures through a single anterior incision: a single-surgeon case series and review of the literature  

Microsoft Academic Search

Introduction  We present a single-surgeon series of 14 acute ruptured distal biceps tendons repaired using a biotenodesis screw through\\u000a a single anterior incision.\\u000a \\u000a \\u000a \\u000a \\u000a Patients  The demographics of this population reveal a typical injury pattern and reflect the preponderance of distal biceps ruptures\\u000a in the middle aged, active male. Goniometric post-operative assessment of flexion, pronation and supination range demonstrates\\u000a excellent clinical function in

Will G. P. Eardley; Saurabh Odak; T. Simon Adesina; Richard P. Jeavons; Jim L. McVie

2010-01-01

85

Biomechanical evaluation of patellar and hamstring tendon graft fixation for anterior cruciat ligament reconstruction using a poly-(D, L-lactide) interference screw  

Microsoft Academic Search

Summary  \\u000a Anterior cruciate ligament (ACL) reconstruction using autologous hamstring tendons are being performed more frequently and\\u000a satisfactory results have been reported. Advantages such as low donor site morbidity and ease of harvest as well as disadvantages\\u000a like low initial construct stiffness have been described. Recently, it has been demonstrated that graft fixation close to\\u000a the original ACL insertion sites increases

A. Weiler; R. F. G. Hoffmann; N. P. Südkamp; C. J. Siepe; N. P. Haas

1999-01-01

86

Long-term results of pediculo-body fixation and posterolateral fusion for lumbar spondylolisthesis.  

PubMed

Grob et al. (Eur Spine J 5:281-285, 1996) illustrated a new fixation technique in inveterate cases of grade 2-3 spondylolisthesis (degenerative or spondylolytic): a fusion without reduction of the spondylolisthesis. Fixation of the segment was achieved by two cancellous bone screws inserted bilaterally through the pedicles of the lower vertebra into the body of the upper slipped vertebra. Since 1998 we have been using this technique according to the authors' indications: symptomatic spondylolisthesis with at least 25% anterior slippage and advanced disc degeneration. Afterwards this technique was used also in spondylolisthesis with low reduction of the disc height and slippage less than 25%. In every case we performed postero-lateral fusion and fixation with two AO 6.5 Ø thread 16 mm cancellous screws. From 1998 to 2002 we performed 62 fusions for spondylolisthesis with this technique: 28 males (45.16%) and 34 females (54.84%), mean age 45 years (14-72 years). The slipped vertebra was L5 in 57 cases (92%), L4 in 2 cases (3.2%), L3 in 1 case (1.6%), combined L4 and L5 in 2 cases (3.2%). In all cases there was an ontogenetic spondylolisthesis with lysis. Lumbar pain was present in 22 patients and lumbar-radicular pain was present in 40 patients. The mean preoperative VAS was 6.2 (range 5-8) for lumbar pain, and 5.5 (range 4-7) for leg pain. The fusion area was L5-S1 in 53 cases (85.5%), L3-L4 in 1 case (1.6%), L4-S1 in 8 cases (12.9%). A decompression of the spinal canal by laminectomy was performed in 33 procedures (53%). When possible a bone graft was done from the removed neural arc, and from the posterior iliac crest in the other cases. The mean blood loss was about 254 ml (100-1,000). The mean operative time was 75 min (range 60-90). The results obtained by computerized analysis at follow-up at least 5 years after surgery showed a significant improvement in preoperative symptoms. The patients were asymptomatic in 52 cases (83.9%); strained-back pain was present in 8 cases (12.9%), and there was persistent lumbar-radicular pain in 2 cases (3.2%). The mean ODI score was 2.6%, the mean VAS back pain was 1.3, the mean VAS leg pain 0.7. Some complications were observed: a nerve root compression by a screw invasion of intervertebral foramen, resolved by screw removal; an iliac artery compression by a lateral exit screw from pediculo, resolved by screw removal; a deep iliac vein phlebitis with thrombosis caused by external compression due to a wrong intraoperative position, treated by medicine. Two cases of synthesis mobilization and two cases of broken screws was detected. No cases of pseudoarthrosis and immediate or late superficial or deep infection were observed. The analysis of the long-term results of the spondylolisthesis surgical treatment with direct pediculo-body screw fixation and postero-lateral fusion gave a very satisfactory response. The technique is reliable in allowing an optimal primary stability, creating the best biomechanical conditions to obtain a solid fusion. PMID:19444490

Zagra, Antonino; Giudici, Fabrizio; Minoia, Leone; Corriero, Andrea Saverio; Zagra, Luigi

2009-06-01

87

Long-term results of pediculo-body fixation and posterolateral fusion for lumbar spondylolisthesis  

PubMed Central

Grob et al. (Eur Spine J 5:281–285, 1996) illustrated a new fixation technique in inveterate cases of grade 2–3 spondylolisthesis (degenerative or spondylolytic): a fusion without reduction of the spondylolisthesis. Fixation of the segment was achieved by two cancellous bone screws inserted bilaterally through the pedicles of the lower vertebra into the body of the upper slipped vertebra. Since 1998 we have been using this technique according to the authors’ indications: symptomatic spondylolisthesis with at least 25% anterior slippage and advanced disc degeneration. Afterwards this technique was used also in spondylolisthesis with low reduction of the disc height and slippage less than 25%. In every case we performed postero-lateral fusion and fixation with two AO 6.5 Ø thread 16 mm cancellous screws. From 1998 to 2002 we performed 62 fusions for spondylolisthesis with this technique: 28 males (45.16%) and 34 females (54.84%), mean age 45 years (14–72 years). The slipped vertebra was L5 in 57 cases (92%), L4 in 2 cases (3.2%), L3 in 1 case (1.6%), combined L4 and L5 in 2 cases (3.2%). In all cases there was an ontogenetic spondylolisthesis with lysis. Lumbar pain was present in 22 patients and lumbar-radicular pain was present in 40 patients. The mean preoperative VAS was 6.2 (range 5–8) for lumbar pain, and 5.5 (range 4–7) for leg pain. The fusion area was L5–S1 in 53 cases (85.5%), L3–L4 in 1 case (1.6%), L4–S1 in 8 cases (12.9%). A decompression of the spinal canal by laminectomy was performed in 33 procedures (53%). When possible a bone graft was done from the removed neural arc, and from the posterior iliac crest in the other cases. The mean blood loss was about 254 ml (100–1,000). The mean operative time was 75 min (range 60–90). The results obtained by computerized analysis at follow-up at least 5 years after surgery showed a significant improvement in preoperative symptoms. The patients were asymptomatic in 52 cases (83.9%); strained-back pain was present in 8 cases (12.9%), and there was persistent lumbar-radicular pain in 2 cases (3.2%). The mean ODI score was 2.6%, the mean VAS back pain was 1.3, the mean VAS leg pain 0.7. Some complications were observed: a nerve root compression by a screw invasion of intervertebral foramen, resolved by screw removal; an iliac artery compression by a lateral exit screw from pediculo, resolved by screw removal; a deep iliac vein phlebitis with thrombosis caused by external compression due to a wrong intraoperative position, treated by medicine. Two cases of synthesis mobilization and two cases of broken screws was detected. No cases of pseudoarthrosis and immediate or late superficial or deep infection were observed. The analysis of the long-term results of the spondylolisthesis surgical treatment with direct pediculo-body screw fixation and postero-lateral fusion gave a very satisfactory response. The technique is reliable in allowing an optimal primary stability, creating the best biomechanical conditions to obtain a solid fusion. PMID:19444490

Giudici, Fabrizio; Minoia, Leone; Corriero, Andrea Saverio; Zagra, Luigi

2009-01-01

88

[The biomechanics of screws, cerclage wire and cerclage cable].  

PubMed

In contrast to fracture fixation, when performing an osteotomy the surgeon is able to plan preoperatively. The resulting fixation and compression of the bone fragments are the most important points. A stable osteosynthesis should prevent dislocation of bone fragments and improve bone healing. Beside plates, cerclages can be used for tension band or diaphysis bone fixation. Moreover, cortical or cancellous screws can be used for osteotomy fixation. This work describes biomechanical principles for fixation after an osteotomy with cerclages and cortical or cancellous screws. It also summarizes the materials and geometries used, as well as their influence on the stability of the osteosynthesis. PMID:23615626

Schröder, C; Woiczinski, M; Utzschneider, S; Kraxenberger, M; Weber, P; Jansson, V

2013-05-01

89

Biomechanical Analysis of Differing Pedicle Screw Insertion Angles  

PubMed Central

Background Pedicle screw fixation to stabilize lumbar spinal fusion has become the gold standard for posterior stabilization. A significant percentage of surgical candidates are classified as obese or morbidly obese. For these patients, the depth of the incisions and soft tissue makes it extremely difficult to insert pedicle screws along the pedicle axis. As such, the pedicle screws could only be inserted in a much more sagittal axis. However, biomechanical stability of the angled screw insertion has been controversial. We hypothesized that the straight or parallel screw was a more stable construct compared to the angled or axially inserted screw when subjected to caudal cyclic loading. Methods We obtained 12 fresh frozen lumbar vertebrae from L3 to L5 from five cadavers. Schantz screws (6.0mm) were inserted into each pedicle, one angled and along the axis of the pedicle and the other parallel to the spinous process. Fluoroscopic imaging was used to guide insertion. Each screw was then subjected to caudal cyclic loads of 50N for 2000 cycles at 2Hz. Analysis of initial damage, initial rate, and total damage during cyclic loading was undertaken. Findings Average total fatigue damage for straight screws measured 0.398±0.38 mm, and 0.689±0.96 mm for angled screws. Statistical analysis for total fatigue damage ratio of angled to straight screws revealed that a significant stability was achieved in straight- screw construct (p<0.03). Interpretation This study showed that straight screw insertion results in a more stable pedicle-screw construct. The angled screw insertion technique resulted in more scattered values of damage indicating that the outcome from the angled screw fixation is less predictable. This validates the use of this technique to implant pedicle screws across the axis of the pedicle rather than along the axis, (parallel to the midline sagittal line), and has broad implications in instrumented posterior lumbar spinal surgery. PMID:17208340

Sterba, William; Kim, Do-Gyoon; Fyhrie, David P.; Yeni, Yener N.; Vaidya, Rahul

2007-01-01

90

Fractured neck of femur below long spinopelvic fixation for Charcot spine: a case report  

PubMed Central

Introduction We present a case of a patient with a previously undescribed complication: intertrochanteric femoral neck insufficiency fracture after long-segment instrumented spinopelvic fusion to the ilium for Charcot spine. Case presentation A 42-year-old Caucasian man with post-traumatic complete T6 paraplegia presented to our institution after developing Charcot spinal arthropathy at L3 and L4 and symptoms of autonomic dysreflexia 21 years after his original spinal cord injury. Multiple anterior and posterior surgeries were required to eventually achieve stabilization of his thoracolumbar spine to his pelvis and resolution of symptoms. The most distal fixation point was two iliac wing screws bilaterally. At 10 weeks after the final spinal surgery and after posterior spinal bony consolidation had occurred, he sustained an intertrochanteric femoral neck fracture, distal to the iliac fixation, whilst bending forward in his wheelchair. His proximal femoral fracture was internally fixed with an intramedullary device. Conclusions Spinal Charcot’s arthropathy is a rare condition that may occur in patients with post-traumatic spinal cord injury. Although associated with high risk of complications, circumferential instrumented fusion in Charcot spine can restore spinal stability. Insufficiency fractures of the proximal femur are possible complications of long spinopelvic fusions. PMID:24378187

2013-01-01

91

Biomechanical comparison of pedicle screws versus spinous process screws in C2 vertebra  

PubMed Central

Background: Biomechanical studies have shown C2 pedicle screw to be the most robust in insertional torque and pullout strength. However, C2 pedicle screw placement is still technically challenging. Smaller C2 pedicles or medial localization of the vertebral artery may preclude safe C2 pedicle screw placement in some patients. The purpose of this study was to compare the pullout strength of spinous process screws with pedicle screws in the C2. Materials and Methods: Eight fresh human cadaveric cervical spine specimens (C2) were harvested and subsequently frozen to ?20°C. After being thawed to room temperature, each specimen was debrided of remaining soft tissue and labeled. A customs jig as used to clamp each specimen for screw insertion firmly. Screws were inserted into the vertebral body pairs on each side using one of two methods. The pedicle screws were inserted in usual manner as in previous biomechanical studies. The starting point for spinous process screw insertion was located at the junction of the lamina and the spinous process and the direction of the screw was about 0° caudally in the sagittal plane and about 0° medially in the axial plane. Each vertebrae was held in a customs jig, which was attached to material testing machine (Material Testing System Inc., Changchun, China). A coupling device that fit around the head of the screw was used to pull out each screw at a loading rate of 2 mm/min. The uniaxial load to failure was recorded in Newton'st dependent test (for paired samples) was used to test for significance. Results: The mean load to failure was 387 N for the special protection scheme and 465 N for the protection scheme without significant difference (t = ?0.862, P = 0.403). In all but three instances (38%), the spinous process pullout values exceeded the values for the pedicle screws. The working distances for the spinous process screws was little shorter than pedicle screws in each C2 specimen. Conclusion: Spinous process screws provide comparable pullout strength to pedicle screws of the C2. Spinous process screws may provide an alternative to pedicle screws fixation, especially with unusual anatomy or stripped screws.

Liu, Guan-yi; Mao, Lu; Xu, Rong-ming; Ma, Wei-hu

2014-01-01

92

Bicondylar Hoffa Fracture Successfully Treated with Headless Compression Screws  

PubMed Central

Bicondylar coronal plane fracture, eponymically named Hoffa fractures, is an extremely rare injury. We present a case of isolated unilateral bicondylar Hoffa fracture that was successfully treated with open reduction and internal fixation using headless compression screws with satisfactory results. We inserted posteroanteriorly oriented Acutrak screws perpendicular to the fracture plane via lateral parapatellar arthrotomy, which provided excellent compression across the fracture. PMID:25140263

Kuroda, Ryosuke; Kurosaka, Masahiro

2014-01-01

93

Apparatus to test insertion and removal torque of bone screws.  

PubMed

This paper describes affordable equipment for testing bone screw torque, corresponding to ASTM standard F543-00 for testing metallic medical bone screws. Correct testing of thin and long bone screws is essential due to screw failures during insertion and removal of the screws. Furthermore, insertion torque is an important factor in predicting fixation strength, screw pull-out force and effects of surface treatment of screws. The capability of the custom-built tester was determined using polytetrafluoroethylene and wood disc samples and bone screws. Bovine cortical bones allowed testing to the failure limit, i.e. the torque increased in long screws to the fracture limit. For 2.7 and 3.5 mm thick self-tapping cortical bone screws, the failure torques were 30-50 per cent higher than the minimum values required by the standard (1.0 and 2.3 N m respectively). The equipment provided reproducible results and fulfilled the ASTM standard very well. Preliminary testing with amorphous diamond coated bone screws showed good durability of the coating and on average 10-15 per cent lower torque values compared with uncoated screws. The equipment can be used to measure insertion and removal torques as described in the standard. Furthermore, it also allows testing of normal screws and bolts. PMID:14702987

Koistinen, A; Santavirta, S; Lappalainen, R

2003-01-01

94

Systemic nickel allergy after internal fixation of a bunionectomy.  

PubMed

Allergic reactions to implanted metals have been estimated to occur in 1% to 5% of orthopedic cases. Stainless steel screws, which contain 14% nickel, are commonly used for internal fixation in an array of podiatric procedures. We present a rare case of a systemic allergic reaction to nickel secondary to stainless steel screw fixation in a bunionectomy procedure. PMID:24774988

Zhubrak, Michelle; Bar-David, Tzvi

2014-01-01

95

A new adhesive technique for internal fixation in midfacial surgery  

Microsoft Academic Search

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

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

2008-01-01

96

The bikini area and bikini line as a location for anterior subcutaneous pelvic fixation: an anatomic and clinical investigation.  

PubMed

Anterior external fixation for pelvic fractures has been the standard for acute stabilization but definitive treatment often leads to pin tract infection, is uncomfortable, and limits patient mobility. We recently developed a subcutaneous anterior pelvic fixator which addresses these issues (INFIX). The objective of this study is to introduce the Bikini Area and Bikini Line as the subcutaneous anatomical location where this apparatus is placed. A study was preformed on eight cadaveric specimens to define the location of the subcutaneous device with respect to anatomic structures. We examined 23 people of various body mass indexes to examine the anterior pelvic anatomy. This was followed by implantation on 42 individuals in whom we reviewed CT scans to assess the location of the implant. We asked these same 42 individuals whether they could sit, stand, and lie on their sides and if they had any discomfort. We measured the dimensions of 26 retrieved rods to approximate the curve of the Bikini Line. Finally in 14 individuals we performed vascular ultrasound to assess the flow in the iliac and femoral vessels with the implant in place in the sitting and standing position. Neurovascular structures are not affected by placing the INFIX device at the Bikini Line, patients are comfortable, mobile and complications are minimized by this procedure. A rod placed on the Bikini Line which connects screws inserted into the anterior inferior iliac spine on each side does not interfere with sitting, standing, or the neurovascular structures. PMID:22927118

Vaidya, R; Oliphant, B; Jain, R; Nasr, K; Siwiec, R; Onwudiwe, N; Sethi, A

2013-04-01

97

A cementless, elastic press-fit socket with and without screws  

PubMed Central

Background The acetabular component has remained the weakest link in hip arthroplasty regarding achievement of long-term survival. Primary fixation is a prerequisite for long-term performance. For this reason, we investigated the stability of a unique cementless titanium-coated elastic monoblock socket and the influence of supplementary screw fixation. Patient and methods During 2006–2008, we performed a randomized controlled trial on 37 patients (mean age 63 years (SD 7), 22 females) in whom we implanted a cementless press-fit socket. The socket was implanted with additional screw fixation (group A, n = 19) and without additional screw fixation (group B, n = 18). Using radiostereometric analysis with a 2-year follow-up, we determined the stability of the socket. Clinically relevant migration was defined as > 1 mm translation and > 2º rotation. Clinical scores were determined. Results The sockets without screw fixation showed a statistically significantly higher proximal translation compared to the socket with additional screw fixation. However, this higher migration was below the clinically relevant threshold. The numbers of migratory sockets were not significantly different between groups. After the 2-year follow-up, there were no clinically relevant differences between groups A and B regarding the clinical scores. 1 patient dropped out of the study. In the others, no sockets were revised. Interpretation We found that additional screw fixation is not necessary to achieve stability of the cementless press-fit elastic RM socket. We saw no postoperative benefit or clinical effect of additional screw fixation. PMID:23083434

2012-01-01

98

Surgical screw segmentation for mobile C-arm CT devices  

NASA Astrophysics Data System (ADS)

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.

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

2014-03-01

99

The iliac passion.  

PubMed Central

"The Iliac Passion" traces a return from the new but busy and rapidly growing discipline of "bioethics" to its source in "fundamental philosophical inquiry." The dilemma between bioethics and medicine is examined in two ways. First, the philosophical concept of the "big question" is presented. If we ask of life or of human experience "What does it all mean?", the "it" needs to be defined, and what I propose to do is to "take on" the "it." In Part Two, the task of combining the medical-technical objectifying mode of thinking about patients, necessary to treat them effectively, with the ability to understand and sympathize with their pain and distress, is illustrated by means of a personal story or parable. PMID:1494895

Natanson, M.

1992-01-01

100

Nonunion after primary treatment of tibia fractures with external fixation  

Microsoft Academic Search

The authors retrospectively reviewed 207 fractures of tibial diaphysis, treated primarily with external fixation without bone grafting. Forty-two fractures (20.3%) resulted in nonunion and required reoperation. Parameters analyzed for their significance for nonunion included, soft tissue damage, energy of injury, method of fracture reduction, type of external fixation frame, supplemental interfragmentary screw fixation, dynamization at the fracture site, and postoperative

N. Papaioannou; D. Mastrokalos; P. J. Papagelopoulos; M. Tyllianakis; J. Athanassopoulos; P. A. Nikiforidis

2001-01-01

101

Posterior fixation of the upper cervical spine: contemporary techniques.  

PubMed

Instrumentation in the upper cervical spine has changed considerably in the past two decades. Previous stand-alone wiring techniques have been made largely obsolete with the development of occipital segmental plating, transarticular screws, and C1 lateral mass screws, as well as a myriad of C2 fixation options, including pedicle, pars, and translaminar screws. Polyaxial screws and segmental fixation are more user-friendly than stand-alone wiring and provide a stronger construct. Awareness of the risks and benefits associated with the use of modern instrumentation and thorough familiarity with the anatomy of the upper cervical spine are essential to avoid complications and optimize outcomes. PMID:21292929

Bransford, Richard J; Lee, Michael J; Reis, Abilio

2011-02-01

102

Fatigue strength of common tibial intramedullary nail distal locking screws  

PubMed Central

Background Premature failure of either the nail and/or locking screws with unstable fracture patterns may lead to angulation, shortening, malunion, and IM nail migration. Up to thirty percent of all unreamed nail locking screws can break after initial weight bearing is allowed at 8–10 weeks if union has not occurred. The primary problem this presents is hardware removal during revision surgery. The purposes of our study was to evaluate the relative fatigue resistance of distal locking screws and bolts from representative manufacturers of tibial IM nail systems, and develop a relative risk assessment of screws and materials used. Evaluations included quantitative and qualitative measures of the relative performance of these screws. Methods Fatigue tests were conducted to simulate a comminuted fracture that was treated by IM nailing assuming that all load was carried by the screws. Each screw type was tested ten times in a single screw configuration. One screw type was tested an additional ten times in a two-screw parallel configuration. Fatigue tests were performed using a servohydraulic materials testing system and custom fixturing that simulated screws placed in the distal region of an appropriately sized tibial IM nail. Fatigue loads were estimated based on a seventy-five kilogram individual at full weight bearing. The test duration was one million cycles (roughly one year), or screw fracture, whichever occurred first. Failure analysis of a representative sample of titanium alloy and stainless steel screws included scanning electron microscopy (SEM) and quantitative metallography. Results The average fatigue life of a single screw with a diameter of 4.0 mm was 1200 cycles, which would correspond roughly to half a day of full weight bearing. Single screws with a diameter of 4.5 mm or larger have approximately a 50 percent probability of withstanding a week of weight bearing, whereas a single 5.0 mm diameter screw has greater than 90 percent probability of withstanding more than a week of weight bearing. If two small diameter screws are used, our tests showed that the probability of withstanding a week of weight bearing increases from zero to about 20 percent, which is similar to having a single 4.5 mm diameter screw providing fixation. Conclusion Our results show that selecting the system that uses the largest distal locking screws would offer the best fatigue resistance for an unstable fracture pattern subjected to full weight bearing. Furthermore, using multiple screws will substantially reduce the risk of premature hardware failure. PMID:19371438

Griffin, Lanny V; Harris, Robert M; Zubak, Joseph J

2009-01-01

103

Distal tibial fracture post syndesmotic screw removal: an adverse complication  

Microsoft Academic Search

Fractures of the ankle are common injuries. Some ankle fractures have an associated injury to the syndesmosis, necessitating\\u000a fixation with one or more screws. Generally, the overall outcome post ankle fracture is good. However, several complications\\u000a have also been described. The current authors describe a distal tibial fracture following syndesmotic screw removal. A 77-year-old\\u000a woman was admitted with a bimaleollar

Mustafa Citak; Manuel Backhaus; Gert Muhr; Thomas Kälicke

104

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

PubMed

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

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

2013-07-01

105

[The effect of an angle-stable plate-screw connection and various screw diameters on the stability of plate osteosynthesis. An FE model study].  

PubMed

In a finite element model of a human femur with an attached stainless steel six-hole plate exposed to a load equivalent to that set up by standing on one leg, pressures on the face of the screw holes, bending stresses in the screws, and axial bone stresses in the mid-plate transverse section were determined. The calculations were performed for minor thread diameters of 3 mm, 5 mm and 8 mm. Further calculations were done assuming a fixator-like rigid screw-plate connection. As a model of a fracture a medial bone defect was chosen. The results show a definitive influence of the screw diameter and the screw-plate connection on the load distribution in the system. Increasing screw diameter makes for lower bone stresses combined with increased bending stability, a larger part of the load being carried by the plate. The rigid screw-plate connection (plate fixator) causes less bone stresses, but high bending stresses are set up the points of screw-plate fixation. Maximal stresses for screw and bone are found at the end of the plate, caused by the large difference in the E-module between the steel plate and the bone. End-plate bone and screws are loaded in excess of their material limits when 3 mm core diameters are used, and sometimes when 5 mm core diameters are used, under the assumed conditions. When a medial bone defect reducing the bone cross-sectional area by 44% is present, the loads on the inner screws increase by a factor of 3 and the loads of the distant screws, by a factor of only 1.3. The maximal pressure in the bone cross section increases 4-fold. PMID:2281325

Seide, K; Zierold, W; Wolter, D; Kortmann, H R

1990-12-01

106

The Use of Small Titanium Screws for Orthodontic Anchorage  

Microsoft Academic Search

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

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

2003-01-01

107

Biomechanical impact of C2 pedicle screw length in an atlantoaxial fusion construct  

PubMed Central

Background: Posterior, atlantoaxial (AA) fusions of the cervical spine may include either standard (26 mm) or short (16 mm) C2 pedicle screws. This manuscript focused on an in vitro biomechanical comparison of standard versus short C2 pedicle screws to perform posterior C1-C2 AA fusions. Methods: Twelve human cadaveric spines underwent C1 lateral mass screw and standard C2 pedicle screw (n = 6) versus short C2 pedicle screw (n = 6) fixation. Six additional controls were not instrumented. The peak torque, peak rotational interval, and peak stiffness of the constructs were analyzed to failure levels. Results: The peak torque to construct failure was not statistically significantly different among the control spine (12.2 Nm), short pedicle fixation (15.5 Nm), or the standard pedicle fixation (11.6 Nm), P = 0.79. While the angle at the peak rotation statistically significantly differed between the control specimens (47.7° of relative motion) and the overall instrumented specimens (P < 0.001), the 20.7° of relative rotation in the short C2 pedicle screw specimens was not statistically significantly higher than the 13.7° of relative rotation in the standard C2 pedicle screw specimens (P = 0.39). Similarly, although the average stiffness was statistically significantly lower in control group (0.026 Nm/degree) versus the overall instrumented specimens (P = 0.001), the standard C2 pedicle screws (2.54 Nm/degree) did not differ from the short C2 pedicle screws Conclusions: Both standard and short C2 pedicle screws allow for equally rigid fixation of C1 lateral mass-C2 AA fusions. Usage of a short C2 pedicle screw may be an acceptable method of stabilization in carefully selected patient populations. PMID:25289157

Xu, Risheng; Bydon, Mohamad; Macki, Mohamad; Belkoff, Stephen M.; Langdale, Evan R.; McGovern, Kelly; Wolinsky, Jean-Paul; Gokalsan, Ziya L.; Bydon, Ali

2014-01-01

108

A review of locking compression plate biomechanics and their advantages as internal fixators in fracture healing.  

PubMed

Metallic implants are often involved in the open reduction and internal fixation of fractures. Open reduction and internal fixation is commonly used in cases of trauma when the bone cannot be healed using external methods such as casting. The locking compression plate combines the conventional screw hole, which uses non-locking screws, with a locking screw hole, which uses locking head screws. This allows for more versatility in the application of the plate. There are many factors which affect the functionality of the plate (e.g., screw placement, screw choice, length of plate, distance from bone, etc.). This paper presents a review of the literature related to the biomechanics of locking compression plates and their use as internal fixators in fracture healing. Furthermore, this paper also addresses the materials used for locking compression plates and their mechanical behavior, parameters that control the overall success, as well as inherent bone quality results. PMID:17904257

Miller, Danielle L; Goswami, Tarun

2007-12-01

109

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

PubMed

We conducted a study to determine if there is a significant difference in ultimate load, yield strength, and fatigue strength between solid core screws and cannulated screws and if a solid core insert placed inside a cannulated screw would have biomechanical effects similar to those of a solid core screw. Five screw designs were tested: Synthes 4.5-mm solid core and 4.5-mm cannulated and our prototype 4.0-mm solid core, 4.0-mm cannulated, and 4.0-mm cannulated with solid core insert. Biomechanical testing with 3-point bending was used to determine ultimate load, yield strength, and cycles to failure for 6 screws of each design. Ultimate load, yield strength, and cycles to failure were significantly (P < .05) lower in the Synthes 4.5-mm cannulated screws than in the Synthes solid core screws and significantly lower in the prototype cannulated screws than in the prototype solid core screws (P < .05) and prototype cannulated screws with solid core inserts (P < .05). There was no significant difference (P > .05) in ultimate load, yield strength, or cycles to failure between the prototype cannulated screws with solid core inserts and the prototype solid core screws. PMID:25251531

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

2014-09-01

110

Helical screw viscometer  

DOEpatents

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.

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

1983-06-30

111

Blocks and Screws  

NSDL National Science Digital Library

In this lesson, each student is given a block of wood and a screw (or nail), and is asked to put the screw into the block, without any tool (like a screwdriver or hammer). Their efforts, with varying success, lead to a discussion of contrivances, using various items and strategies as make-do (contrived) tools for which they were not intended, and an exploration of many examples of contrivances or adaptive compromises and other imperfections in the living world, especially in humans. This situation may be better explained by evolution rather than the result of intelligent design.

Patterson, Tim

112

Decompressive cervical laminectomy and lateral mass screw-rod arthrodesis. Surgical analysis and outcome  

PubMed Central

Background This study evaluates the outcome and complications of decompressive cervical Laminectomy and lateral mass screw fixation in 110 cases treated for variable cervical spine pathologies that included; degenerative disease, trauma, neoplasms, metabolic-inflammatory disorders and congenital anomalies. Methods A retrospective review of total 785 lateral mass screws were placed in patients ages 16-68 years (40 females and 70 males). All cases were performed with a polyaxial screw-rod construct and screws were placed by using Anderson-Sekhon trajectory. Most patients had 12-14-mm length and 3.5 mm diameter screws placed for subaxial and 28-30 for C1 lateral mass. Screw location was assessed by post operative plain x-ray and computed tomography can (CT), besides that; the facet joint, nerve root foramen and foramen transversarium violation were also appraised. Results No patients experienced neural or vascular injury as a result of screw position. Only one patient needed screw repositioning. Six patients experienced superficial wound infection. Fifteen patients had pain around the shoulder of C5 distribution that subsided over the time. No patients developed screw pullouts or symptomatic adjacent segment disease within the period of follow up. Conclusion decompressive cervical spine laminectomy and Lateral mass screw stabilization is a technique that can be used for a variety of cervical spine pathologies with safety and efficiency. PMID:21595968

2011-01-01

113

Suture Bridge Fixation of a Femoral Condyle Traumatic Osteochondral Defect  

PubMed Central

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

Bowers, Andrea L.

2008-01-01

114

Augmentation of implant fixation in osteoporotic bone.  

PubMed

Osteoporosis presents a dilemma for the orthopedic surgeon. Screw fixation within the bone is crucial for mechanical stabilization, maintenance of reduction, and ultimately, fracture healing. For the patient, soft bones and physiological fragility usually benefit from immediate weight bearing and mobility to avoid further disuse osteoporosis, deconditioning, and immobility. For implant companies, traditional screws, plates, and nails function for simple fractures and compliant patients. Locked plating has improved screw purchase in osteoporotic bone and has expanded fracture fixation capabilities but is not the panacea for all fractures. For orthopedic surgeons, traditional surgical augmentation for osteoporosis consisting of dual plating, augmentation with polymethyl methacrylate, joint replacement, and now locked plating are beneficial. In order to advance orthopedic care in the expanding population of elderly osteoporotic patients, modern solutions utilizing the dual properties of secure fixation and relatively flexible implants are required. Endosteal substitution, extraosteal substitution, and combined nail/plate combinations are methods of utilizing traditional implants in a nontraditional way. Nonsurgical augmentation of fracture fixation is also paramount. PMID:23054960

Jones, Clifford B

2012-12-01

115

Screw implantation in the globe: the risk of delayed hardware migration from craniofacial repair.  

PubMed

Plating system modification has enabled the use of rigid fixation in younger patients having maxillofacial surgery. One of the common reported complications of the use of plates and screws in children is screw migration due to skeletal maturation. Ophthalmic complications due to maxillofacial surgery reported to date include oculomotor and abducens palsies, lacrimal damage and vision loss due to infection, retrobulbar hemorrhage, and compartment syndrome. We describe a complication unique to screw migration resulting in orbital fixation and near-globe rupture in a patient with Treacher Collins syndrome. We hope to alert our colleagues to the potential risk of screw and hardware migration and breakage, particularly in the setting of craniofacial surgery performed on a child before maturation of craniofacial osseous structures. PMID:24036744

Sadiq, Mohammad Ali A; Prabhu, Sanjay P; Fearon, Jeffrey A; Taghinia, Amir H; Dagi, Linda R

2013-09-01

116

Traumatic anterior hip dislocation associated with anterior and inferior iliac spines avulsions and a capsular-labral lesion  

PubMed Central

A 16-year-old man had a traumatic accident during motor-cross racing and sustained an anterior hip dislocation with fracture of anterior superior and anterior inferior iliac spines. The hip was emergently reduced and further imaging was obtained to evaluate the lesion and bony fragments. Computed tomography confirmed the presence of two large fragments and a small fragment from the antero-inferior acetabulum. The patient underwent open reduction and internal fixation of the iliac spines and the reparation of anterior hip capsule. No complications occur after 1 year of follow-up. We present the case and a review of the literature for this lesion. PMID:18427923

Brugo, G.

2008-01-01

117

Bioabsorbable Tricalcium Phosphate Bone Cement Strengthens Fixation of Suture Anchors  

Microsoft Academic Search

Background  Failure of suture anchor fixation in rotator cuff repair can occur at different interfaces. Prior studies show fixation at\\u000a the bone-anchor interface can be augmented using polymethylmethacrylate (PMMA) cement, and screw fixation into bone can be\\u000a strengthened using bioabsorbable tricalcium phosphate cement.\\u000a \\u000a \\u000a \\u000a \\u000a Questions\\/purposes  We wished to determine whether augmentation of suture anchor fixation using bioabsorbable tricalcium phosphate cement would\\u000a increase pullout

Rayshad Oshtory; Derek P. Lindsey; Nicholas J. Giori; Faisal M. Mirza

2010-01-01

118

Substitutes for human cadaveric bone in maxillofacial rigid fixation research  

Microsoft Academic Search

Objective: Various materials have been used as human bone substitutes in rigid fixation research. We hypothesize that these substitutes behave differently than human cadaveric bone in maxillofacial research. Study Design: Screw insertion torque and pull-out strength of titanium maxillofacial self-tapping bone screws (1.0 mm and 2.4 mm outer diameter) were measured in cadaveric mandible and in the following materials: bovine

Todd L Bredbenner; Richard H Haug

2000-01-01

119

Comparison of Outcomes after Atlantoaxial Fusion with Transarticular Screws and Screw-Rod Constructs  

PubMed Central

Objective The purpose of this study was to compare the radiological and neurological outcomes between two atlantoaxial fusion method for atlantoaxial stabilization; C1 lateral mass-C2 pedicle screws (screw-rod constructs, SRC) versus C1-2 transarticular screws (TAS). Methods Forty-one patients in whom atlantoaxial instability was treated with atlantoaxial fixation by SRC group (27 patients, from March 2005 to May 2011) or TAS group (14 patients, from May 2000 to December 2005) were retrospectively reviewed. Numeric rating scale (NRS) for pain assessment, Oswestry disability index (ODI), and Frankel grade were also checked for neurological outcome. In radiologic outcome assessment, proper screw position and fusion rate were checked. Perioperative parameters such as blood loss during operation, operation time, and radiation exposure time were also reviewed. Results The improvement of NRS and ODI were not different between both groups significantly. Good to excellent response in Frankel grade is shown similarly in both groups. Proper screw position and fusion rate were also observed similarly between two groups. Total bleeding amount during operation is lesser in SRC group than TAS group, but not significantly (p=0.06). Operation time and X-ray exposure time were shorter in SRC group than in TAS group (all p<0.001). Conclusion Both TAS and SRC could be selected as safe and effective treatment options for C1-2 instability. But the perioperative result, which is technical demanding and X-ray exposure might be expected better in SRC group compared to TAS group. PMID:25132931

Kim, Ji Yong; Oh, Chang Hyun; Park, Hyeong-Chun; Seo, Hyun Sung

2014-01-01

120

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

PubMed Central

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

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

2010-01-01

121

Absorbable fasteners for the fixation of ankle fractures.  

PubMed

Bioabsorbable materials have been used for the treatment of fractures for more than a century. We reviewed the results of a combined series of 30 ankle fractures from Bad Hersfeld, Germany, and Louisville, Kentucky, using initially polyglycolide and more recently poly-L-lactide screws and rods. The results were comparable to treatment with metal screws. The advantage of bioabsorbable implants is they do not need operations to take them out. There was a low incidence of reaction around the screw heads, which was reduced further with the use of the newer self-reinforced poly-L-lactate screws. The technique for use of plastics is different than the methods for placement of metal screws. Bioabsorbables will have an increasing role in fracture fixation in the future. PMID:10189771

George, K; Becker, D; Seligson, D

1999-03-01

122

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

PubMed Central

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

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

2013-01-01

123

The Effects of Screw Length on Stability of Simulated Osteoporotic Distal Radius Fractures Fixed with Volar Locking Plates  

PubMed Central

Purpose Volar plating for distal radius fractures has caused extensor tendon ruptures secondary to dorsal screw prominence. This study was designed to determine the biomechanical impact of placing unicortical distal locking screws and pegs in an extra-articular fracture model. Methods Volar-locking distal radius plates were applied to 30 osteoporotic distal radius models. Radii were divided into 5 groups based on distal locking fixation: bicortical locked screws, 3 lengths of unicortical locked screws (abutting the dorsal cortex [full length], 75% length, and 50% length to dorsal cortex), and unicortical locked pegs. Distal radius osteotomy simulated a dorsally comminuted, extra-articular, fracture. Each constructs stiffness was determined under physiologic loads (axial compression, dorsal bending volar bending) before and after 1000 cycles of axial conditioning and prior to axial loading to failure (2mm of displacement) and subsequent catastrophic failure. Results Cyclic conditioning did not alter constructs stiffness. Stiffness to volar bending and dorsal bending forces were similar between groups. Final stiffness(N/mm) under axial load was statistically equivalent for all groups: bicortical screws(230), full-length unicortical screws(227), 75% length unicortical screws(226), 50% length unicortical screws(187), unicortical pegs(226). Force(N) at 2 mm displacement was significantly less for 50% length unicortical screws(311) compared to bicortical screws(460), full-length unicortical screws(464), 75% length unicortical screws(400), and unicortical pegs(356). Force(N) to catastrophic fracture was statistically equivalent between groups but mean values for pegs(749) and 50% length unicortical(702) screws were 16-21% less than means for bicortical(892), full-length unicortical(860), and 75% length(894) unicortical constructs. Discussion Locked unicortical distal screws of at least 75% length produce construct stiffness similar to bicortical fixation. Unicortical distal fixation for extra-articular distal radius fractures should be entertained to avoid extensor tendon injury since it does not appear to compromise initial fixation. Clinical Relevance Biomechanical comparison of distal fixation techniques during volar locked plating for distal radius fracture. PMID:22305729

Wall, Lindley B.; Brodt, Michael D.; Silva, Matthew J.; Boyer, Martin I.; Calfee, Ryan P.

2013-01-01

124

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

PubMed Central

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

2014-01-01

125

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

PubMed Central

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

2013-01-01

126

Three-dimensional load displacement properties of posterior lumbar fixation.  

PubMed

Pedicular fixation devices for the posterior treatment of segmental spinal instability are thought to offer enhanced stabilization compared with sublaminar wire systems, while avoiding the immobilization of multiple normal motion segments. We compared the performance of three dissimilar stabilization systems: the Hartshill rectangle, the Acromed/Steffee interpedicular screw and plate, and the Synthes/Dick fixateur interne. Human cadaveric lumbosacral specimens were first tested intact, then after a laminectomy and a facetectomy at the L3/L4 level, and finally after the fixation devices were sequentially attached. Constructs spanning two to four vertebral levels were compared for stabilization of the resected lumbar spine segments. When tested in compression, the Acromed/Steffee system with pedicular screws at L2-L5 allowed significantly less intersegmental distraction than the Synthes/Dick construct with screws at L2 and L5 only, and less than the intact and the destabilized uninstrumented spine. When sagittally rotated, the Acromed/Steffee construct with screws at L2-L5, or at L2 and L5, allowed significantly less distraction than the intact or destabilized segments, and the construct with screws at L2 through L5 allowed less distraction than the Synthes/Dick constructs with screws at L3/L4 or L2/L5. With the exception of the Acromed/Steffee system with screws at four levels, there were no significant differences in distraction allowed between the Synthes/Dick and Acromed/Steffee constructs, or between the multisegment and single segment constructs. There were no significant differences in stiffness across levels L3/L4 with the various implants. Results indicate that the use of posterior spine constructs significantly augment the stability of posterior segmental defects. Pedicular fixation immediately cephalad and caudad to the defect provided stable fixation in this application. PMID:1762002

Shea, M; Edwards, W T; Clothiaux, P L; Crowell, R R; Nachemson, A L; White, A A; Hayes, W C

1991-01-01

127

Bilateral Three-Level Lumbar Spondylolysis Repaired by Hook-Screw Technique  

PubMed Central

We report a case of bilateral three-level lumbar spondylolysis that was directly repaired by use of hook-screw technique. The patient complained of low back pain for 2 years that progressively worsened and was exacerbated with standing and walking. He also mentioned bilateral sciatalgia. The neurological examination was normal. Interestingly, we found bilateral lumbar spondylolysis in L3, L4, and L5 levels in imaging studies. After proving that spondylolysis was the source of the low back pain by local anesthetic agent injection, we used a direct technique for correction of spondylolysis by use of a hook-screw device plus decortications of lysis area and iliac crest autograft. We assessed the patient after surgery to evaluate pain recovery and fusion rate. The results were favorable and proved the efficacy of the hook-screw technique for treatment of symptomatic multilevel lumbar spondylolysis. PMID:24353947

Sharifi, Guive; Jahanbakhshi, Amin; Daneshpajouh, Behnam; Rahimizadeh, Abolfazl

2012-01-01

128

Feasibility of Bilateral Crossing C7 Intralaminar Screws: A Cadaveric Study  

PubMed Central

Objective When the pedicle screw insertion technique is failed or not applicable, C7 intralaminar screw insertion method has been used as an alternative or salvage fixation method recently. However, profound understanding of anatomy is required for safe application of the bilaterally crossing laminar screw at C7 in clinic. In this cadaveric study, we evaluated the anatomic feasibility of the bilateral crossing intralaminar screw insertion and especially focused on determination of proper screw entry point. Methods The C7 vertebrae from 18 adult specimens were studied. Morphometric measurements of the mid-laminar height, the minimum laminar thickness, the maximal screw length, and spino-laminar angle were performed and cross-sectioned vertically at the screw entry point (spino-laminar junction). The sectioned surface was equally divided into 3 parts and maximal thickness and surface area of the parts were measured. All measurements were obtained bilaterally. Results The mean mid-laminar height was 13.7 mm, mean minimal laminar thickness was 6.6 mm, mean maximal screw length was 24.6 mm, and mean spinolaminar angle was 50.8±4.7°. Based on the measured laminar thickness, the feasibility of 3.5 mm diameter intralaminar screw application was 83.3% (30 sides laminae out of total 36) when assuming a tolerance of 1 mm on each side. Cross-sectional measurement results showed that the mean maximal thickness of upper, middle, and lower thirds was 5.0 mm, 7.5 mm, and 7.3 mm, respectively, and mean surface area for each part was 21.2 mm2, 46.8 mm2, and 34.7 mm2, respectively. Fourteen (38.9%) sides of laminae would be feasible for 3.5 mm intralaminar screw insertion when upper thirds of C7 spino-laminar junction is the screw entry point. In case of middle and lower thirds of C7 spino-laminar junction, 32 (88.9%) and 28 (77.8%) sides of laminae were feasible for 3.5 mm screw insertion, respectively. Conclusion The vertical cross-sectioned area of middle thirds at C7 spinolaminar junction was the largest area and 3.5 mm screw can be accommodated with 77.8% of feasibility when lower thirds were the screw entry point. Thus, selection of middle and lower thirds for each side of screw entry point in spino-laminar junction would be the safest way to place bilateral crossing laminar screw within the entire lamina. This anatomic study result will help surgeons to place the screw safely and accurately.

Baek, Tae-Hyun; Hong, Jae-Taek; Kim, Daniel H.; Shin, Dongsuk; Lee, Sang-Won

2014-01-01

129

Removal of bicortical screws and other osteosynthesis material that caused symptoms after bilateral sagittal split osteotomy: a retrospective study of 251 patients, and review of published papers.  

PubMed

Rigid fixation with either bicortical screws or miniplates is the current standard way to stabilise the mandibular segments after bilateral sagittal split osteotomy (BSSO). Both techniques are widely used and the superiority of one or other method is still debatable. One complication of rigid fixation is the need to remove the osteosynthesis material because of associated complaints. The main aim of this retrospective study was to analyse how often we needed to remove bicortical screws because they caused symptoms after BSSO in our clinic. Review of other published papers also enabled us to investigate the reported rates of removal of screws and miniplates at other centres. The mean (SD) duration of follow-up of 251 patients (502 sites) was 432 (172) days, and the number of bicortical screws removed in our clinic was 14/486 sites (3%). Other methods of fixation were used at 16 sites. We found no significant association between removal of bicortical screws and age, sex, presence of third molars, or bad splits. Published rates of removal of bicortical screws and miniplates are 3.1%-7.2% and 6.6%-22.2% per site, respectively. These findings show that fixation with bicortical screws after BSSO is associated with a low rate of removal of osteosynthesis material. Reported incidences imply a lower rate of removal for screws than for miniplates. PMID:24953784

Verweij, Jop P; Houppermans, Pascal N W J; Mensink, Gertjan; van Merkesteyn, J P Richard

2014-10-01

130

Low noise lead screw positioner  

NASA Technical Reports Server (NTRS)

A very precise and low noise lead screw positioner, for positioning a retroreflector in an interferometer is described. A gas source supplies inert pressurized gas, that flows through narrow holes into the clearance space between a nut and the lead screw. The pressurized gas keeps the nut out of contact with the screw. The gas flows axially along the clearance space, into the environment. The small amount of inert gas flowing into the environment minimizes pollution. By allowing such flow into the environment, no seals are required between the end of the nut and the screw.

Perkins, Gerald S. (inventor)

1986-01-01

131

Minimal invasive treatment for scaphoid fractures using the cannulated herbert screw system.  

PubMed

Internal fixation of scaphoid fractures avoids the problems associated with prolonged plaster immobilization and, at the same time, allows an early return to activity for these mostly young patients.Internal fixation of the scaphoid is greatly facilitated by the use of specially designed headless bone screws, such as the Herbert bone screw, originally developed specifically for internal fixation of the scaphoid; furthermore, the advent of cannulated scaphoid screws has made closed (percutaneous fixation) stabilization of the scaphoid a reality. Indeed, this method has now become the treatment of choice for the majority of acute scaphoid fracture, bringing with it all the advantages of internal fixation without the disadvantages of open surgery.However, the success of closed treatment is also dependent on an accurate assessment of the fracture, and for this reason, we now advocate the routine use of computed tomography preoperatively. Because of the complex, 3-dimensional shape of the scaphoid, simple x-rays alone are inadequate, whereas computed tomography, parallel to the long axis of the scaphoid, allows excellent visualization of the fracture and any associated deformity, which must be corrected at the time of surgery.We describe here our method of treating acute scaphoid fractures, and we report the outcome of minimally invasive fixation. PMID:16518213

Moser, Veith L; Krimmer, Hermann; Herbert, Timothy J

2003-12-01

132

Endoscopic ACL reconstruction using stryker biosteon cross-pin femoral fixation and interlock cross-pin tibial fixation.  

PubMed

Hamstring tendon autografts have, over the past decade, increasingly become the graft of choice for anterior cruciate ligament (ACL) reconstructions. Studies have shown that multiply stranded hamstring grafts have superior biomechanical characteristics when compared to patellar tendon autografts. Harvests of hamstring tendons have been shown to cause less donor-site morbidity than the harvest of patellar bone-tendon-bone grafts. Historically, however, fixation methods for hamstring grafts have limited their successful use. Fixation for both the tibia and femur distant from the intra-articular portions of the graft decreased the stiffness of the construct. The fixation also contributed to tunnel widening and ganglion formation. New methods have been developed to maximize the mechanical strengths of hamstring grafts and optimize biological factors in healing of the graft to the bone tunnels. Femoral cross-pin fixation provides secure fixation close to the knee joint, while also allowing for placement of the graft in the native ACL footprint at the far posterior aspect of the intercondylar notch. Tibial interference screw fixation allows fixation close to the joint as well. Addition of the interlock pin through the interference screw increases pullout strength significantly. Recent advances in material science have led to the development of bioabsorbable implants that afford high initial fixation strengths while limiting subsequent complications from permanent hardware. PMID:15455332

Berg, Troy L; Paulos, Lonnie E

2004-01-01

133

Modified C1 lateral mass screw insertion using a high entry point to avoid postoperative occipital neuralgia.  

PubMed

For the past decade, a screw-rod construct has been used commonly to stabilize the atlantoaxial joint, but the insertion of the screw through the C1 lateral mass (LM) can cause several complications. We evaluated whether using a higher screw entry point for C1 lateral mass (LM) fixation than in the standard procedure could prevent screw-induced occipital neuralgia. We enrolled 12 consecutive patients who underwent bilateral C1 LM fixation, with the modified screw insertion point at the junction of the C1 posterior arch and the midpoint of the posterior inferior portion of the C1 LM. We measured postoperative clinical and radiological parameters and recorded intraoperative complications, postoperative neurological deficits and the occurrence of occipital neuralgia. Postoperative plain radiographs were used to check for malpositioning of the screw or failure of the construct. Four patients underwent atlantoaxial stabilization for a transverse ligament injury or a C1 or C2 fracture, six patients for os odontoideum, and two patients for C2 metastasis. No patient experienced vertebral artery injury or cerebrospinal fluid leak, and all had minimal blood loss. No patient suffered significant occipital neuralgia, although one patient developed mild, transient unilateral neuralgia. There was also no radiographic evidence of construct failure. Twenty screws were positioned correctly through the intended entry points, but three screws were placed inferiorly (that is, below the arch), and one screw was inserted too medially. When performing C1-C2 fixation using the standard (Harms) construct, surgeons should be aware of the possible development of occipital neuralgia. A higher entry point may prevent this complication; therefore, we recommend that the screw should be inserted into the arch of C1 if it can be accommodated. PMID:23117140

Lee, Sun-Ho; Kim, Eun-Sang; Eoh, Whan

2013-01-01

134

Helical screw expander evaluation project  

Microsoft Academic Search

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

R. McKay

1982-01-01

135

Split spline screw  

NASA Technical Reports Server (NTRS)

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.

Vranish, John M. (inventor)

1993-01-01

136

Carbon nanotube Archimedes screws.  

PubMed

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

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

2010-12-28

137

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

Microsoft Academic Search

Internal fixation is the established dorsal standard procedure for the treatment of thoracolumbar fractures. The main problem\\u000a of the procedure is the false positioning of the pedicle screws. The exact determination of pedicle screws has up to now only\\u000a been possible through postoperative computed tomography. This study was intended to clarify the diagnostic value of intraoperative\\u000a 3D scans after pedicle

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

2009-01-01

138

An isolated iliac wing stress fracture in a marathon runner.  

PubMed

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

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

2014-02-01

139

Novel free-hand T1 pedicle screw method: Review of 44 consecutive cases  

PubMed Central

Summary of Background Data: Multilevel posterior cervical instrumented fusions are becoming more prevalent in current practice. Biomechanical characteristics of the cervicothoracic junction may necessitate extending the construct to upper thoracic segments. However, fixation in upper thoracic spine can be technically demanding owing to transitional anatomy while suboptimal placement facilitates vascular and neurologic complications. Thoracic instrumentation methods include free-hand, fluoroscopic guidance, and CT-based image guidance. However, fluoroscopy of upper thoracic spine is challenging secondary to vertebral geometry and patient positioning, while image-guided systems present substantial financial commitment and are not readily available at most centers. Additionally, imaging modalities increase radiation exposure to the patient and surgeon while potentially lengthening surgical time. Materials and Methods: Retrospective review of 44 consecutive patients undergoing a cervicothoracic fusion by a single surgeon using the novel free-hand T1 pedicle screw technique between June 2009 and November 2012. A starting point medial and cephalad to classic entry as well as new trajectory were utilized. No imaging modalities were employed during screw insertion. Postoperative CT scans were obtained on day 1. Screw accuracy was independently evaluated according to the Heary classification. Results: In total, 87 pedicle screws placed were at T1. Grade 1 placement occurred in 72 (82.8%) screws, Grade 2 in 4 (4.6%) screws and Grade 3 in 9 (10.3%) screws. All Grade 2 and 3 breaches were <2 mm except one Grade 3 screw breaching 2-4 mm laterally. Only two screws (2.3%) were noted to be Grade 4, both breaching medially by less than 2 mm. No new neurological deficits or returns to operating room took place postoperatively. Conclusions: This modification of the traditional starting point and trajectory at T1 is safe and effective. It attenuates additional bone removal or imaging modalities while maintaining a high rate of successful screw placement compared to historical controls.

Rivkin, Mark A.; Okun, Jessica F.; Yocom, Steven S.

2014-01-01

140

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

PubMed Central

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

2014-01-01

141

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

PubMed Central

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

Cornelius, Carl-Peter; Ehrenfeld, Michael

2010-01-01

142

Comparative clinical study of locking screws versus smooth locking pegs in volar plating of distal radius fractures.  

PubMed

The present study was performed to test the null hypothesis on no difference in stability of fixation after volar plating of intra-articular distal radius fractures (AO C2-C3) with either locking smooth pegs or locking screws in a clinical setting. A retrospective evaluation included adult patients with C2-C3 AO fractures treated with a volar plate with locking smooth pegs or locking screws. Radiographic assessment was performed to evaluate extra- and intra-articular parameters in the early postoperative period and after bone union. Twenty-seven consecutive patients were included. Thirteen cases had fixation with locking screws and 14 had fixation with locking smooth pegs. Both groups had bone fragment displacement after fixation. However, there were no significant differences between the groups either in extra- or intra-articular parameters defined by Kreder et al. (1996). Our study shows that, in a clinical setting, there is no difference in stability fixation between locking screws or smooth locking pegs in C2-C3 distal radius fractures. PMID:24401740

Boretto, J G; Pacher, N; Giunta, D; Gallucci, G L; Alfie, V; De Carli, P

2014-09-01

143

Anterior inferior iliac spine apophyseal avulsion fracture.  

PubMed

A case of anterior inferior iliac spine (AIIS) apophyseal avulsion fracture caused while playing football is reported. A 16-year-old amateur football player felt severe pain in his left groin while kicking the ball during training. There was point tenderness over the anterior inferior iliac spine (AIIS). Avulsion fracture of AIIS was considered clinically. Radiographs confirmed the diagnosis. He was treated with a conservative rehabilitation program. He is still an active football player. Avulsion fractures follow violent or explosive muscular contractions against a fixed resistance, sudden deceleration, or stretching of the involved muscle or as a result of a direct trauma. This injury usually occurs with an extension moment to the hip joint, with the knee flexed, and it is commonly seen in sports that involve kicking. AIIS avulsion fractures should be a diagnostic consideration in patients with pain in the groin who are involved in activities requiring high-level forces of flexion of the hip. PMID:12735624

Yildiz, Cemil; Aydin, Taner; Yildiz, Yavuz; Kalyon, Tunc Alp; Basbozkurt, Mustafa

2003-01-01

144

Intraoperative CT navigation for glenoid component fixation in reverse shoulder arthroplasty.  

PubMed

CT navigation has been shown to improve component positioning in total shoulder arthroplasty. The technique can be useful in achieving strong initial fixation of the metal backed glenoid in reverse shoulder arthroplasty. We report a 61 years male patient who underwent reverse shoulder arthroplasty for rotator cuff arthropathy. CT navigation was used intraoperatively to identify best possible glenoid bone and to maximize the depth of the fixation screws that anchor the metaglene portion of the metal backed glenoid component. Satisfactory positioning of screws and component was achieved without any perforation or iatrogenic fracture in the scapula. CT navigation can help in maximizing the purchase of the fixation screws that dictate the initial stability of the glenoid component in reverse shoulder arthroplasty. The technique can be extended to improve glenoid component position [version and tilt] with the availability of appropriate software. PMID:23531710

Gavaskar, Ashok S; Vijayraj, K; Subramanian, Sd Muthukumar

2013-01-01

145

Intraoperative CT navigation for glenoid component fixation in reverse shoulder arthroplasty  

PubMed Central

CT navigation has been shown to improve component positioning in total shoulder arthroplasty. The technique can be useful in achieving strong initial fixation of the metal backed glenoid in reverse shoulder arthroplasty. We report a 61 years male patient who underwent reverse shoulder arthroplasty for rotator cuff arthropathy. CT navigation was used intraoperatively to identify best possible glenoid bone and to maximize the depth of the fixation screws that anchor the metaglene portion of the metal backed glenoid component. Satisfactory positioning of screws and component was achieved without any perforation or iatrogenic fracture in the scapula. CT navigation can help in maximizing the purchase of the fixation screws that dictate the initial stability of the glenoid component in reverse shoulder arthroplasty. The technique can be extended to improve glenoid component position [version and tilt] with the availability of appropriate software. PMID:23531710

Gavaskar, Ashok S; Vijayraj, K; Subramanian, SD Muthukumar

2013-01-01

146

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

PubMed

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

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

147

Biomechanical analysis and clinical effects of bridge combined fixation system for femoral fractures.  

PubMed

This work aimed to compare the stress distribution and mechanical properties of our bridge combined fixation system and commonly used metal locking plate screw system by finite element analysis and by using the Zwick/Z100 testing machine. In addition, we also investigated the clinical outcome of our bridge combined fixation system for femoral fractures in 59 patients from June 2005 to January 2013. As a result, the stress distribution in the bone plate and screws of metal locking plate screw system during walking and climbing stairs was significantly lower than that of metal locking plate screw system. No significant difference in the displacement was observed between two systems. The equivalent bending stiffness of bridge combined fixation system was significantly lower than that of metal locking plate screw system. There were no significant differences in the bending strength, yield load, and maximum force between two systems. All the cases were followed up for 12-24 months (average 18 months). The X-ray showed bone callus was formed in most patients after 3 months, and the fracture line was faint and disappeared at 6-9 months postoperatively. No serious complications, such as implant breakage and wound infection, occurred postoperatively. According to self-developed standard for bone healing, clinical outcomes were rated as excellent or good in 55 out of 59 patients (success rate: 93.2%). Therefore, our findings suggest that our bridge combined fixation system may be a promising approach for treatment of long-bone fractures. PMID:25201264

Wang, Da-Xing; Xiong, Ying; Deng, Hong; Jia, Fu; Gu, Shao; Liu, Bai-Lian; Li, Qun-Hui; Pu, Qi; Zhang, Zhong-Zi

2014-09-01

148

Successful Emergency Stenting of Acute Ruptured False Iliac Aneurysm  

SciTech Connect

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.

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

149

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

PubMed

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

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

150

An Articulating Tool for Endoscopic Screw Delivery  

E-print Network

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 ...

Petrzelka, Joseph Edward

151

Biomechanical comparison of inside–outside screws, cables, and regular screws, using a sawbone model  

Microsoft Academic Search

Our aim was to conduct a biomechanical comparison of the pull-out strengths of inside–outside (I\\/O) screws, cables, and bone screws to determine whether I\\/O screws provide greater pull-out resistance than cables or bone screws, and their effectiveness with the screw diameter. There is no remarkable biomechanical experimental study comparing the I\\/O technique with conventional spinal techniques. The diameter of the

Yusuf Sukru Caglar; Fuat Torun; Thomas Glenn Pait; William Hogue; Melih Bozkurt; Serdar Özgen

2005-01-01

152

The Endovascular Management of Iliac Artery Aneurysms  

SciTech Connect

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.

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

153

Failure of cement-augmented pedicle screws in the osteoporotic spine: a case report.  

PubMed

The treatment of patients with osteoporosis and spinal abnormalities that require surgical intervention is difficult because of the challenge of achieving fixation in osteoporotic bone. As the population ages, this challenge is becoming a common problem in the field of spinal surgery. Although numerous publications exist about the biomechanical benefits of various fixation devices and techniques, no standard of care has emerged that offers a clear method for accomplishing spinal stabilization in such patients. This case presents the failure mode of cement-augmented pedicle screws in a patient with severe osteoporosis, a description of the methods used to attain fixation and spinal stability during the revision surgery, and the outcome achieved for the patient 1 year after surgery. An 82-year-old female with a T9 burst fracture and a history of osteoporosis underwent minimally invasive instrumentation from T5 to T12, fusion from T7 to T11, and decompression from T8 to T10. Four weeks after surgery, the patient returned to the hospital because of back pain. Imaging studies showed that the pedicle screws at T11 and T12, which were augmented with polymethylmethacrylate (PMMA), had pulled out of the vertebral bodies. The pedicle screws failed by disengaging from the PMMA and displacing posteriorly and inferiorly. The PMMA did not appear to move during this process. A revision surgery was performed, in which the posterior construct was extended caudally and cephalad, the pedicle screws were augmented with PMMA, and a titanium hook and woven polyester band were used to increase the points of fixation. At 1-year follow-up after revision, our patient showed radiographic evidence of fusion, and the construct continued to maintain stability in the osteoporotic spine. PMID:24319620

Mesfin, Addisu; Komanski, Christopher B; Khanna, A Jay

2013-09-01

154

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

PubMed Central

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

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

2014-01-01

155

Biomechanical measurements of cortical screw purchase in five types of human and artificial humeri.  

PubMed

Humerus shaft fracture fixation is largely dependent on cortical screw purchase in host bone. Only 2 prior studies assessed cortical screw purchase in human humeral shafts, but were of very limited scope and did not fully assess humerus material properties. Also, no studies evaluated the human dried or artificial humeri both commercially available from Sawbones. Vashon, WA, USA. Therefore, present authors measured cortical screw purchase in human fresh-frozen (FF) (n=19), human embalmed (EM) (n=18), human dried (DR) (n=14), artificial "normal" (AN) (n=13), and artificial "osteoporotic" (AO) (n=13) humeri. Each humerus had 2 bicortical screws of 3.5-mm diameter inserted 20mm apart through the shaft's anterior and posterior cortices. Absolute force, displacement, and energy for screw-bone interface failure were measured by screw pullout tests, afterwhich data were normalized by total surface area engaged at the screw-bone interface. For absolute force, AN humeri reached a higher load than EM (p=0.001) and AO (p<0.001) humeri, whilst AN humeri achieved lower normalized force than DR humeri (p=0.018). For absolute displacement, AO humeri achieved a lower level than FF humeri (p=0.013), whilst for normalized displacement AN humeri had lower levels than all other groups (p?0.005) and AO humeri had lower values than EM humeri (p=0.029). For absolute and normalized energy, there were no statistical differences (p?0.066). Human bone mineral density (BMD) ranged from 0.7 to 1.8g/cm(2) and was linearly correlated to screw pullout parameters in 14 of 18 cases (R=0.61 to 0.96), whilst humerus age was not. Consequently, it is recommended that human fresh-frozen, human embalmed, and human dried humeri can be used interchangeably for cortical screw purchase, since they were statistically equivalent for all comparisons. However, artificial humeri were involved in all statistical differences observed and, thus, may not replicate cortical screw purchase in human humeri. To date, this is the most comprehensive study on cortical screw purchase in human and artificial humeral shafts. PMID:24295967

Aziz, Mina S R; Nicayenzi, Bruce; Crookshank, Meghan C; Bougherara, Habiba; Schemitsch, Emil H; Zdero, Radovan

2014-02-01

156

A biomechanical analysis of an instrumented spinal fixator under torsional loads.  

PubMed

The effect of design features of an internal spinal fixator on the loading of its individual components is paramount to the understanding of the interaction between the fixator and the instrumented spine. Using a corpectomy injury model, a strain gauge instrumented spinal fixation device was employed to investigate the role of clamp tightening torque and the inclusion of transverse bars on the distribution of bending and torsional moments acting on the fixator under torsional loading. The increase in clamp torque from 5 to 10 Nm caused a marked decrease (40%) in torsional moments acting on the vertical rods, an increase of 24% in torsional moments acting on the screws and an increase of 44% in bending moments acting on the rods along the sagittal plane of the fixator. The inclusion of transverse elements significantly increased (132%) the bending moment acting on the rods and decreased (92%) the bending moments acting on the screws along the sagittal plane. The change in both design parameters significantly reduced the response hysteresis and decreased the asymmetry of loading. A theoretical model, developed to elucidate the load path mechanisms underlying this response, successfully predicted the external response of the fixator. This model suggested both design parameters would affect the internal force and moment distribution across the fixator and the relative role of each load response mechanism in effecting this response. The changes in load patterns across the fixator will influence both its ability to augment the process of spinal fusion and the long-term performance of its components. PMID:15713308

Alkalay, R N; Sharpe, D; Bader, D L

2005-04-01

157

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

PubMed Central

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

2014-01-01

158

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

PubMed

The purpose of this study was to describe the radiological characteristics of a previously unreported finding: posterior iliac offset at the sacroiliac joint and to assess its association with pelvic instability as measured by initial displacement and early implant loosening or failure. Radiographs from 42 consecutive patients with a mean age of 42 years (18 to 77; 38 men, four women) and mean follow-up of 38 months (3 to 96) with Anteroposterior Compression II injuries, were retrospectively reviewed. Standardised measurements were recorded for the extent of any diastasis of the pubic symphysis, widening of the sacroiliac joint, static vertical ramus offset and a novel measurement (posterior offset of the ilium at the sacroiliac joint identified on axial CT scan). Pelvic fractures with posterior iliac offset exhibited greater levels of initial displacement of the anterior pelvis (anterior sacroiliac widening, pubic symphysis diastasis and static vertical ramus offset, p < 0.001,0.034 and 0.028, respectively). Pelvic fractures with posterior ilium offset also demonstrated higher rates of implant loosening regardless of fixation method (p = 0.05). Posterior offset of the ilium was found to be a reliable and reproducible measurement with substantial inter-observer agreement (kappa = 0.70). Posterior offset of the ilium on axial CT scan is associated with greater levels of initial pelvic displacement and early implant loosening. Cite this article: Bone Joint J 2014;96-B:1535-9. PMID:25371470

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

2014-11-01

159

Helical screw expander evaluation project  

NASA Technical Reports Server (NTRS)

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.

Mckay, R.

1982-01-01

160

Helical screw expander evaluation project  

NASA Astrophysics Data System (ADS)

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.

McKay, R.

1982-03-01

161

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

PubMed Central

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

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

2014-01-01

162

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

PubMed

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

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

2014-01-01

163

Optimal technique of screw placement in the ischial tuberosity for posterior acetabular fractures.  

PubMed

Thirty dry adult bony specimens and eight embalmed cadavers were used to report on the morphological data of the ischial tuberosity and to determine the most optimal technique for ischial tuberosity screw placement for open reduction and internal fixation of posterior acetabular fractures. The average width, height, and depth of the ischial tuberosity were 27.0 mm, 32.2 mm, and 32.4 mm, respectively. The average angles between the posterior and medial aspects and between the posterior and lateral aspects of the ischial tuberosities were 79.5 degrees, and 111.5 degrees, respectively. The risk to the internal pudendal neurovascular bundle increases with either a more medially placed screw or a laterally placed screw that is angled medially. The tendinous origin of the hamstrings becomes quite substantial (7-10 mm thick) at a point 2 cm distal to the inferior acetabular margin. The exposure of the ischial tuberosity should therefore be restricted to this level. The entry point of the screws should be 5 mm or 10 mm medial to the lateral margin of the ischial tuberosity, and the screws should be directed 35-40 degrees, 45-50 degrees, and 50-55 degrees caudally at the level of the inferior acetabular margin and 1 cm and 2 cm below it, respectively, to obtain the most favorable bony purchase. PMID:8667107

Xu, R; Ebraheim, N A; Biyani, A; Yeasting, R A

1996-01-01

164

Ionising radiation during internal fixation of extracepsular neck of femur fractures  

Microsoft Academic Search

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.

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

1998-01-01

165

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

Microsoft Academic Search

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

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

166

Bilateral tubular minimally invasive approach for decompression, reduction and fixation in lumbosacral lythic spondylolisthesis.  

PubMed

This video demonstrates the minimally invasive surgical technique used in a 56-year-old woman suffering from L-5 spondylolysis and grade 2 L5-S1 spondylolisthesis. The first author used expandable tubular retractors bilaterally to perform neural decompression, mini-open TLIF, spondylolysthesis reduction and L5-S1 pedicle screw fixation. L-5 cement augmentation was performed through cannulated and fenestrated screws to enhance resistance to screw pull-out secondary to reduction maneuvers. Sequential surgical steps related to microsurgery, spondylolysthesis reduction and instrumentation are shown and commented. We submit that in cases of lythic spondylolisthesis a bilateral traversing and exiting nerve roots decompression is a safer option prior to performing the deformity reduction and fixation; the proposed minimally invasive technique may help in reducing surgical morbidity and improving postoperative recovery. The video can be found here: http://youtu.be/G4Qdg-A-Y3M. PMID:23829858

Barbagallo, Giuseppe M V; Certo, Francesco; Sciacca, Giovanni; Albanese, Vincenzo

2013-07-01

167

Wet Granulation in a Twin-Screw Extruder: Implications of Screw Design  

E-print Network

as an efficient and flexible technique for continuous high-shear wet granulation. Extruders can readily processWet Granulation in a Twin-Screw Extruder: Implications of Screw Design M.R. THOMPSON, J. SUN MMRI granulation in twin-screw extrusion machinery is an attractive tech- nology for the continuous processing

Thompson, Michael

168

Fixation of zygomatic and mandibular fractures with biodegradable plates  

PubMed Central

Context: In this prospective study, 13 randomly selected patients underwent treatment for zygomatic–complex fractures (2 site fractures) and mandibular fractures using 1.5 / 2 / 2.5-mm INION CPS biodegradable plates and screws. Aims: To assess the fixation of zygomatic-complex and mandibular fractures with biodegradable copolymer osteosynthesis system. Materials and Methods: In randomly selected 13 patients, zygomatic-complex and mandibular fractures were plated using resorbable plates and screws using Champy's principle. All the cases were evaluated clinically and radiologically for the type of fracture, need for the intermaxillary fixation (IMF) and its duration, duration of surgery, fixation at operation, state of reduction at operation, state of bone union after operation, anatomic reduction, paresthesia, occlusal discrepancies, soft tissue infection, immediate and late inflammatory reactions related to biodegradation process, and any need for the removal of the plates. Statistical Analysis Used: Descriptives, Frequencies, and Chi-square test were used. Results: In our study, the age group range was 5 to 55 years. Road traffic accidents accounted for the majority of patients six, (46.2%). Postoperative occlusal discrepancies were found in seven patients as mild to moderate, which resolved with IMF for 1-8 weeks. There were minimal complications seen and only as soft tissue infection. Conclusions: Use of biodegradable osteosynthesis system is a reliable alternative method for the fixation of zygomatic-complex and mandibular fractures. The biodegradable system still needs to be refined in material quality and handling to match the stability achieved with metal system. Biodegradable plates and screws is an ideal system for pediatric fractures with favorable outcome. PMID:23662255

Degala, Saikrishna; Shetty, Sujeeth; Ramya, S

2013-01-01

169

Retro-odontoid cystic mass treated by laminectomy and C1-C2 fixation  

PubMed Central

Retro-odontoid cysts associated with chronic atlantoaxial subluxation are extremely rare. This article describes a case of retro-odontoid cystic mass associated with chronic atlantoaxial subluxation and its management with posterior C1 and partial C2 laminectomy and C1-C2 pedicle screw fixation without resection of the retro-odontoid cyst. A 64-year-old woman experienced a sudden onset of neck pain, hand and foot paresthesia. Atlantoaxial instability associated with a retro-odontoid cystic mass was found in the imaging. The patient underwent posterior C1 and partial C2 laminectomy and C1-C2 pedicle screws fixation without resection of the retro-odontoid cyst. During the 24 months followup period, the cyst disappeared completely and the patient remained symptom free and returned to independent daily living. These findings suggest that posterior laminectomy and fixation without resection of the retro-odontoid cyst is relatively simple and safe and the results are satisfactory.

Lin, Dasheng; Ding, Zhenqi; Guo, Yanjie; Lian, Kejian

2014-01-01

170

The role of reduction and internal fixation of Lisfranc fracture-dislocations: a systematic review of the literature  

PubMed Central

A systematic review of the literature was performed in order to evaluate the role of reduction and internal fixation in the management of Lisfranc joint fracture–dislocations. Articles were extracted from the Pubmed database and the retrieved reports were included in the study only if pre-specified eligibility criteria were fulfilled. Eleven articles were eligible for the final analysis, reporting data for the management of 257 patients. Injuries of the first three metatarsal rays were treated by closed reduction and internal fixation with screws in 16.3% of the patients, open reduction and internal fixation with screws in 66.5% and open reduction and internal fixation with Kirschner wires (K-wires) in 17.1% of the patients. The preferred method for the stabilisation of the fourth and fifth metatarsal rays was K-wires. Screw-related complications were common and were reported in 16.1% of the cases. The mean American Orthopaedic Foot and Ankle Society midfoot score was 78.1 points. Post-traumatic radiographic arthritis was reported in 49.6% of the patients, but only in 7.8% of them it was severe enough to warrant an arthrodesis. We conclude that open reduction and internal fixation of the first three metatarsal rays with screws is a reliable method for the management of Lisfranc injuries. This can be complemented by K-wires application in the fourth and fifth metatarsal rays if needed. PMID:20683593

Stavlas, Panagiotis; Roberts, Craig S.; Xypnitos, Fragiskos N.

2010-01-01

171

A new adhesive technique for internal fixation in midfacial surgery  

PubMed Central

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

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

2008-01-01

172

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

SciTech Connect

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.

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

173

Helical rotary screw expander power system  

Microsoft Academic Search

An energy converter for the development of wet steam geothermal fields is described. A project to evaluate and characterize a helical rotary screw expander for geothermal applications is discussed. The helical screw expander is a positive displacement machine which can accept untreated corrosive mineralized water of any quality from a geothermal well. The subjects of corrosion, mineral deposition, the expansion

R. A. McKay; R. S. Sprankle

1974-01-01

174

Effect of occipitocervical fusion with screw-rod system for upper cervical spine tumor  

PubMed Central

Background Craniospinal junction tumors are rare but severe lesions. Surgical stabilization has been established to be an ideal treatment for upper cervical tumor pathology. The purpose of this study was to evaluate the effect of a screw-rod system for occipitocervical fusion. Methods A total of 24 cases with C1 and C2 cervical tumor underwent occipitocervical fusion with Vertex screw-rod internal fixation from January 2005 to December 2012. Preoperative X-ray and MRI examinations were performed on all patients before the operation, after the operation, and during last follow-up. The JOA score was used to assess neurological function pre and postoperatively. Results All the patients were followed up for 6 to 42 months with an average of 24 months. The result of X-ray showed that bony fusion was successful in 18 patients at 3 months and 6 patients at 6 months of follow-ups. There was no deterioration of spinal cord injury. The JOA Scores of neurological function increased significantly. Conclusion The screw-rod system offers strong fixation and good fusion for occipitocervical fusion. It is an effective and reliable method for reconstruction of upper cervical spine tumor. PMID:24884456

2014-01-01

175

Objective Guidelines for Removing an External Fixator after Tibial Lengthening Using Pixel Value Ratio: A Pilot Study  

Microsoft Academic Search

During limb lengthening over an intramedullary nail, decisions regarding external fixator removal and weightbearing depend\\u000a on the amount of callus seen at the lengthening area on radiographs. However, this method is subjective and objective evaluation\\u000a of the amount of callus likely would minimize nail or interlocking screw breakage and refracture after fixator removal. We\\u000a asked how many cortices with full

Li Zhao; Qing Fan; K. P. Venkatesh; Man S. Park; Hae Ryong Song

2009-01-01

176

To evaluate the efficacy of biodegradable plating system for fixation of maxillofacial fractures: A prospective study  

PubMed Central

Aims: The present study was undertaken to evaluate the efficacy of biodegradable plating system for fixation of maxillofacial fractures and to study the morbidity associated with the use of biodegradable plates and screws. Materials and Methods: This prospective study consisted of 10 patients with maxillofacial fractures requiring open reduction and internal fixation. Fractures with infection, comminuted and pathological fractures were excluded. All were plated with biodegradable system (Inion CPS) using standard plating principles and observed for a total period of 24 weeks. Characteristics of the fractures, ease of use of bioresorbable plate/screw system and post operative complications were assessed. Results: Of total 10 patients, eight patients were of midface fracture and two pediatric patients with mandibular fracture, with nine male and one female. The mean age was 32.8 years. Out of 20 plates and 68 screws applied to the 10 fractures sites; there were three incidences of screw breakage with no other intraoperative difficulties. Paresthesia of the infraorbital nerve was present in two patients, and recovered completely in four weeks after surgery. Fracture reduction was considered to be satisfactory in all cases. One patient developed postsurgical infection and was managed with oral antibiotics and analgesics. Conclusions: Favorable healing can be observed through the use of biodegradable plates and screws to stabilize selected midface fractures in patients of all ages, as well as mandible fractures in early childhood, however further studies with more sample size are required. PMID:24665170

Bali, Rishi K.; Sharma, Parveen; Jindal, Shalu; Gaba, Shivani

2013-01-01

177

Reconstruction of the lumbar spine using AO DCP plate internal fixation.  

PubMed

Augmentation of lumbar spine fusion with internal fixation using pedicle screw systems has gained wide currency because it offers rigid stabilization to foster fusion healing. The AO DCP plate has been employed in Europe as a spinal implant with pedicle fixation using 6.5 mm, full-threaded cancellous bone screws with success. This report details the experience of using this device for lumbar spine fusion in a series of 46 North American patients with a mean follow-up of 1.25 years (range 1-2.5 years). Thirty-one patients had had prior lumbar spine surgery with poor outcomes, and 15 had had no prior surgery. All were treated surgically for lumbar degenerative disease with canal decompression, internal fixation with AO plates, and fusion with autologous bone grafting posterolaterally. Complications included two early and one delayed wound infection; five cases of screw loosening; three cases of screw breakage; and three cases of screw impingement upon a nerve. Results of surgery in 17 patients with failed interbody fusion included good to excellent pain relief in 59%, and solid fusion in 76%. In 14 patients with failed posterior surgery the good to excellent pain relief rate was 79%, and the fusion rate was 86%. In 15 patients undergoing primary surgery there was 89% good to excellent pain relief and a solid fusion rate of 87%. The benefits accruing from augmentation of the fusion with internal fixation using AO DCP plates are positive and justify its continued use. Complications encountered in the early experience have been significantly reduced in subsequent series, indicating the existence of a "learning curve" effect which would mandate specific training of spinal surgeons in the technique. PMID:2913675

Thalgott, J S; LaRocca, H; Aebi, M; Dwyer, A P; Razza, B E

1989-01-01

178

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

Microsoft Academic Search

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

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

2009-01-01

179

Magnetic Resonance Imaging of Bioabsorbable Polylactic Acid Interference Screws During the First 2 Years After Anterior Cruciate Ligament Reconstruction  

Microsoft Academic Search

Summary: Bioabsorbable screws composed of poly(L-lactic acid) (PLA) were used for graft fixation and studied prospectively with serial magnetic resonance imaging (MRI) scans at 8, 16, and 24 months after autogenous patellar tendon anterior cruciate ligament (ACL) reconstruction in 10 patients. Conventional spin echo, proton density , and T2-weighted double echo sequences were obtained, as well as T2-weighted fat-saturated fast

William H. Warden; Robert Friedman; Louis M. Teresi; Douglas W. Jackson

1999-01-01

180

[The dynamic hip screw with support plate--a reliable osteosynthesis for highly unstable "reverse" trochanteric fractures?].  

PubMed

ORIF management of unstable trochanteric fractures of type A3 of the A0 classification is difficult because of lateral dislocation of the proximal fractured segments, particularly when only the sliding hip-screw is used for fixation. A connectable butt-press plate was recently developed in order to prevent this type of dislocation. We review the results with this fixation technique in 22 elderly patients with an average age of 76 years who presented with highly unstable trochanteric fracture of the A3 type. Three patients died of diseases unrelated to the trauma or operation before the fractures had healed. The other 19 were followed prospectively until fracture healing had occurred. Complaints, leg shortening and changes in the CCD angle were recorded. Furthermore, the mobility score was determined. Although the patients were able to bear full weight after the operation, no lateral dislocation of fragments was observed. Only 1 patient had a varus dislocation of 5 degrees until the fracture had consolidated. This was due to severe osteopenia and subsequent dislocation of the screw within the femoral head. No pseudarthrosis, osteitis or rotational malalignment was noted. Five of the surviving patients had a lower mobility score after fracture healing as compared to the status before the fracture was sustained. On the basis of this review, we recommend the use of this new connectable buttress plate with sliding hip screws because it provides sufficient fixation of highly unstable fractures of type A3. PMID:9035954

Dávid, A; Hüfner, T; Lewandrowski, K U; Pape, D; Muhr, G

1996-11-01

181

[Iliac venous aneurysm: a case report and review of literature].  

PubMed

Primary iliac vein aneurisms are extremely rare being described as anomaly, without any history of trauma, cardiovascular pathology or arteriovenous fistula. This clinical condition has a high rate of potentially fatal complications: pulmonary embolism; ruptured aneurism; deep vein thrombosis. There are only 7 cases of iliac vein aneurism described in the literature. We describe an additional case of a 59-year old patient presented with abdominal pain, right lower limb edema and palpable mass in the right iliac area. Ultrasound (US) revealed a liquid formation, confirmed by computed tomography (CT). Surgical removal of the aneurism with lateral venorrhaphy was performed. Postoperative evolution was uneventful. The patient is asymptomatic during 36 month follow-up. PMID:21698869

Ghidirim, Gh; Mi?in, I; Gagauz, I; Condra?chi, E

2011-01-01

182

The biomechanics of guided growth: does screw size, plate size, or screw configuration matter?  

PubMed

Guided growth with the eight-plate is a commonly used technique to correct angular limb deformities in children. However, the optimal combination of plate size, screw size, and screw configuration has not been determined. Using osteotomized femoral sawbones and a rail frame, we developed a growth model to examine the effect of these variables at 6-month, 12-month, and 18-month growth increments. The mean annual coronal plane change was 11.3°. Screw size and plate size were not associated with the rate of angular correction. Screw configuration was important, with parallel screws resulting in optimal correction at all time points compared with divergent screws (P<0.05). PMID:24322536

Schoenleber, Scott J; Iobst, Christopher A; Baitner, Avi; Standard, Shawn C

2014-03-01

183

Implant Removal after Percutaneous Short Segment Fixation for Thoracolumbar Burst Fracture : Does It Preserve Motion?  

PubMed Central

Objective The purpose of this study was to evaluate the efficacy of implant removal of percutaneous short segment fixation after vertebral fracture consolidation in terms of motion preservation. Methods Between May 2007 and January 2011, 44 patients underwent percutaneous short segment screw fixation due to a thoracolumbar burst fracture. Sixteen of these patients, who underwent implant removal 12 months after screw fixation, were enrolled in this study. Motor power was intact in all patients, despite significant vertebral height loss and canal compromise. The patients were divided into two groups by degree of osteoporosis : Group A (n=8), the non-osteoporotic group, and Group B (n=8), the osteoporotic group. Imaging and clinical findings including vertebral height loss, kyphotic angle, range of motion (ROM), and complications were analyzed. Results Significant pain relief was achieved in both groups at final follow-up versus preoperative values. In terms of vertebral height loss, both groups showed significant improvement at 12 months after screw fixation and restored vertebral height was maintained to final follow-up in spite of some correction loss. ROM (measured using Cobb's method) in flexion and extension in Group A was 10.5° (19.5/9.0°) at last follow-up, and in Group B was 10.2° (18.8/8.6°) at last follow-up. Both groups showed marked improvement in ROM as compared with the screw fixation state, which was considered motionless. Conclusion Removal of percutaneous implants after vertebral fracture consolidation can be an effective treatment to preserve motion regardless of osteoporosis for thoracolumbar burst fractures. PMID:24653799

Kim, Hyeun Sung; Ju, Chang Il; Wang, Hui Sun; Lee, Sung Myung; Kim, Dong Min

2014-01-01

184

Dynesys fixation for lumbar spine degeneration.  

PubMed

The dynamic fixation system Dynesys is utilized in the last 10 years for treatment of degenerative segmental disease of the lumbar spine. Dynesys is a semi-rigid fixation system that allows minimal lengthening and shortening between two segmental pedicle screws as opposed to a rigid metal bar. Thus, the system is regarded to maintain stability and near physiological motion patterns of the lumbar spine. The theoretical advantage of this system is to stabilize the treated segment and to prevent adjacent segment degeneration. The goal of this prospective trial was to evaluate clinical, radiographic, and computed tomography (CT) scan outcomes in 54 consecutive cases. Postoperative complications are discussed in detail. Forty cases were recruited with a mean follow-up of 16 months (range, 12 to 37). Postoperative pain scores (Hannover Activities of Daily Living Questionnaire and VAS for back and leg pain) improved in 29 cases (73%) and was best when dynamic fusion was combined with nerve root decompression. Outcome data were not superior to conventional rigid fusion systems and had a considerable number of complications requiring revision surgery in 27.5% of cases. PMID:17906883

Bothmann, Matthias; Kast, Erich; Boldt, Gerald Jens; Oberle, Joachim

2008-04-01

185

Semi-Empirical Screw Compressor Chiller Model  

E-print Network

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

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

186

Additional Drive Circuitry for Piezoelectric Screw Motors  

NASA Technical Reports Server (NTRS)

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

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

2004-01-01

187

A computational biomechanical investigation of posterior dynamic instrumentation: combination of dynamic rod and hinged (dynamic) screw.  

PubMed

Currently, rigid fixation systems are the gold standard for degenerative disk disease treatment. Dynamic fixation systems have been proposed as alternatives for the treatment of a variety of spinal disorders. These systems address the main drawbacks of traditional rigid fixation systems, such as adjacent segment degeneration and instrumentation failure. Pedicle-screw-based dynamic stabilization (PDS) is one type of these alternative systems. The aim of this study was to simulate the biomechanical effect of a novel posterior dynamic stabilization system, which is comprised of dynamic (hinged) screws interconnected with a coiled, spring-based dynamic rod (DSDR), and compare it to semirigid (DSRR and RSRR) and rigid stabilization (RSRR) systems. A validated finite element (FE) model of L1-S1 was used to quantify the biomechanical parameters of the spine, such as range of motion, intradiskal pressure, stresses and facet loads after single-level instrumentation with different posterior stabilization systems. The results obtained from in vitro experimental intact and instrumented spines were used to validate the FE model, and the validated model was then used to compare the biomechanical effects of different fixation and stabilization constructs with intact under a hybrid loading protocol. The segmental motion at L4-L5 increased by 9.5% and 16.3% in flexion and left rotation, respectively, in DSDR with respect to the intact spine, whereas it was reduced by 6.4% and 10.9% in extension and left-bending loads, respectively. After instrumentation-induced intradiskal pressure at adjacent segments, L3-L4 and L5-S1 became less than the intact in dynamic rod constructs (DSDR and RSDR) except in the RSDR model in extension where the motion was higher than intact by 9.7% at L3-L4 and 11.3% at L5-S1. The facet loads were insignificant, not exceeding 12N in any of the instrumented cases in flexion. In extension, the facet load in DSDR case was similar to that in intact spine. The dynamic rod constructions (DSDR and RSDR) led to a lesser peak stress at screws compared with rigid rod constructions (DSRR and RSRR) in all loading cases. A dynamic construct consisting of a dynamic rod and a dynamic screw did protect the adjacent level from excessive motion. PMID:24599026

Erbulut, Deniz U; Kiapour, Ali; Oktenoglu, Tunc; Ozer, Ali F; Goel, Vijay K

2014-05-01

188

The treatment of fractures with a dynamic axial fixator.  

PubMed

The results obtained with a lightweight dynamic axial fixator in the treatment of fractures are reported. The apparatus comprises a single bar with articulating ends which clamp self-tapping screws and can be locked at an angle appropriate for axial alignment. A telescopic facility allows ready conversion from rigid to dynamic fixation once periosteal callus formation has commenced. Reduction and controlled distraction or compression are achieved by means of a detachable compressor unit. We treated 288 patients with fresh fractures and 50 with ununited fractures. The success rate for fresh fractures was 94%, with average healing times ranging from 3.4 to 6.5 months. In ununited fractures also, the success rate was 94% with average healing times ranging from 4.7 to 6.5 months. Complications were minimal. The device is versatile and can be applied in an average of 15 minutes. It permits ambulatory fracture care without sacrificing a sound anatomical result. PMID:6746689

De Bastiani, G; Aldegheri, R; Renzi Brivio, L

1984-08-01

189

Freehand thoracic pedicle screw technique using a uniform entry point and sagittal trajectory for all levels: preliminary clinical experience.  

PubMed

Object Experience with freehand thoracic pedicle screw placement is well described in the literature. Published techniques rely on various starting points and trajectories for each level or segment of the thoracic spine. Furthermore, few studies provide specific guidance on sagittal and axial trajectories. The goal of this study was to propose a uniform entry point and sagittal trajectory for all thoracic levels during freehand pedicle screw placement and determine the accuracy of this technique. Methods The authors retrospectively reviewed postoperative CT scans of 33 consecutive patients who underwent open, freehand thoracic pedicle-screw fixation using a uniform entry point and sagittal trajectory for all levels. The same entry point for each level was defined as a point 3 mm caudal to the junction of the transverse process and the lateral margin of the superior articulating process, and the sagittal trajectory was always orthogonal to the dorsal curvature of the spine at that level. The medial angulation (axial trajectory) was approximately 30° at T-1 and T-2, and 20° from T-3 to T-12. Breach was defined as greater than 25% of the screw diameter residing outside of the pedicle or vertebral body. Results A total of 219 thoracic pedicle screws were placed with a 96% accuracy rate. There were no medial breaches and 9 minor lateral breaches (4.1%). None of the screws had to be repositioned postoperatively, and there were no neurovascular complications associated with the breaches. Conclusions It is feasible to place freehand thoracic pedicle screws using a uniform entry point and sagittal trajectory for all levels. The entry point does not have to be adjusted for each level as reported in existing studies, although this technique was not tested in severe scoliotic spines. While other techniques are effective and widely used, this particular method provides more specific parameters and may be easier to learn, teach, and adopt. PMID:25147977

Fennell, Vernard S; Palejwala, Sheri; Skoch, Jesse; Stidd, David A; Baaj, Ali A

2014-11-01

190

Percutaneous Endovascular Treatment of Chronic Iliac Artery Occlusion  

SciTech Connect

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.

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

191

Sharp Recanalization for Chronic Left Iliac Vein Occlusion  

SciTech Connect

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.

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

192

External iliac artery dissection causing early renal transplant dysfunction.  

PubMed

External iliac artery dissection after kidney transplantation is a rare, catastrophic but potentially reversible complication. Treatment which may save both the transplant and the patient requires clinical suspicion, timely imaging, and prompt intervention. This case report describes successful diagnosis of this complication and surgical intervention which saved the kidney and safeguarded blood supply to the patient's leg. PMID:24695666

Lee, Gwyn; Barlow, Adam; Doughman, Tahir; Nicholson, Michael L

2014-01-01

193

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

PubMed

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

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

2012-09-01

194

WRIST ARTHRODESIS USING AN EMBEDDED ILIAC CREST BONE GRAFT  

Microsoft Academic Search

34 patients treated by the iliac crest bone graft technique for wrist arthrodesis were reviewed. The average age was 45.6 years and the mean follow-up was 45 months. The procedure is performed through a straight ulnar approach and the head of the ulna is removed. A longitudinal trench is created in both distal radius and carpus preserving the anterior, posterior

E. LENOBLE; H. OVADIA; D. GOUTALLIER

1993-01-01

195

Endovascular Stent-Grafting for Infected Iliac Artery Pseudoaneurysms  

SciTech Connect

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.

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

196

Biomechanical comparison of mono-segment transpedicular fixation with short-segment fixation for treatment of thoracolumbar fractures: A finite element analysis.  

PubMed

Mono-segment transpedicular fixation is a method for the treatment of certain types of thoracolumbar spinal fracture. Finite element models were constructed to evaluate the biomechanics of mono-segment transpedicular fixation of thoracolumbar fracture. Spinal motion (T10-L2) was scanned and used to establish the models. The superior half of the cortical bone of T12 was removed and the superior half of the cancellous bone of the T12 body was assigned the material properties of injured bone to mimic vertebral fracture. Transpedicular fixation of T11 and T12 was performed to produce a mono-segment fixation model; T11 and L1 were fixed to produce a short-segment fixation model. Motion differences between functional units and von Mises stress on the spine and implants were measured under axial compression, anterior bending, extensional bending, lateral bending and axial rotation. We found no significant difference between mono- and short-segment fixations in the motion of any functional unit. Stress on the T10/T11 nucleus pulposus and T10/T11 and L1/L2 annulus fibrosus increased significantly by about 75% on anterior bending, extensional bending and lateral bending. In the fracture model, stress was increased by 24% at the inferior endplate of T10 and by 43% at the superior endplate of L2. All increased stresses were reduced after fixation and lower stress was observed with mono-segment fixation. In summary, the biomechanics of mono-segment pedicle screw instrumentation was similar to that of conventional short-segment fixation. As a minimally invasive treatment, mono-segment fixation would be appropriate for the treatment of selected thoracolumbar spinal fractures. PMID:25267283

Xu, Guijun; Fu, Xin; Du, Changling; Ma, Jianxiong; Li, Zhijun; Tian, Peng; Zhang, Tao; Ma, Xinlong

2014-10-01

197

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

PubMed Central

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

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

2014-01-01

198

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

Microsoft Academic Search

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

Chris Rorres

2000-01-01

199

Balloon Occlusion of the Contralateral Iliac Artery to Assist Recanalization of the Ipsilateral Iliac Artery in Total Aortoiliac Occlusion: A Technical Note  

PubMed Central

Endovascular recanalization of chronic total aortoiliac occlusion is technically challenging. Inability to reenter the true aortic lumen, following retrograde iliac recanalization, is one of the most common causes of failure. We describe a case of a total aortoiliac occlusion where balloon occlusion of the right common iliac artery, following its recanalization from a brachial approach, was used to facilitate antegrade recanalization of the occluded contralateral left common iliac artery. PMID:23762730

Jaffan, Abdel Aziz A.

2013-01-01

200

Improving Carbon Fixation Pathways  

PubMed Central

A recent resurgence in basic and applied research on photosynthesis has been driven in part by recognition that fulfilling future food and energy requirements will necessitate improvements in crop carbon-fixation efficiencies. Photosynthesis in traditional terrestrial crops is being reexamined in light of molecular strategies employed by photosynthetic microbes to enhance the activity of the Calvin cycle. Synthetic biology is well-situated to provide original approaches for compartmentalizing and enhancing photosynthetic reactions in a species independent manner. Furthermore, the elucidation of alternative carbon-fixation routes distinct from the Calvin cycle raises possibilities that alternative pathways and organisms can be utilized to fix atmospheric carbon dioxide into useful materials. PMID:22647231

Ducat, Daniel C.

2012-01-01

201

Spiral Intermaxillary Fixation  

PubMed Central

Intermaxillary fixation (IMF) remains an important component in the management of many facial fractures. During IMF, dental occlusion plays an important role as a guide and therapeutic tool. Since time immemorial there is a constant quest of oral and maxillofacial surgeons to find a quick way for IMF. The desire to develop an alternate interdental fixation technique, which not only would decrease the risk to the operator and gingival trauma but also accurately satisfy dental occlusion, lead to the development of this novel technique of “spiral IMF.” PMID:23730425

Kumar, Yuvika Raj; Chaudhary, Zainab; Sharma, Pankaj

2012-01-01

202

Femoral tunnel-interference screw divergence in anterior cruciate ligament reconstruction using bone-patellar tendon-bone graft: A comparison of two techniques  

PubMed Central

Background: Interference screw is a popular fixation device used to rigidly fix bone-patellar tendon-bone (B-PT-B) graft both in femoral and tibial tunnels in anterior cruciate ligament (ACL) reconstruction. Parallel placement of screw is difficult in transtibially drilled femoral tunnel but always desired as it affects pullout strength of the graft. Commonly, interference screw into the femoral tunnel is inserted through the anteromedial (AM) or accessory AM portal. These portals are not-in-line with the transtibially drilled femoral tunnel. Furthermore, these portals increase the divergence of the interference screw in the femoral tunnel. We hypothesized that interference screw placement through patellar tendon (PT) portal (through donor defect) in transtibially drilled femoral tunnel can be less divergent. We report the prospective randomized study to investigate the difference of divergence of interference screw placed through PT portal and AM portal and its clinical relevance. Materials and Methods: Forty-one patients underwent femoral tunnel B-PT-B graft fixation through AM portal (group 1) and other 41 (group 2) through PT portal. Femoral tunnel-interference screw divergence was measured on postoperative digital lateral X-rays. Ha’s method was used to grade divergence. The clinical outcome was assessed by postoperative intervention knee documentation committee grading (IKDC) and Lysholm score at 2 years followup. Results: Mean tunnel-screw divergence in sagittal plane through AM portal was 13.38° (95% CI: 12.34-14.41) and through PT portal was 7.20° (95% CI: 6.25-8.16) (P<0.0001). In AM portal group, 82.9% patients had divergence in either grade 3 or 4 category, whereas in PT portal group, 82.9% patients were in grade 1 or 2 category (P<0.0001). Mean Lysholm score were 92.8 and 94.5 at two-year follow-up in both groups which were statistically not significant. The International knee documentation committee grades of patients in both groups were similar and had no statistical significance. Conclusion: Femoral interference screw placement through the PT portal leads to significantly less screw divergence as compared with screw placement through the AM portal. However, this difference in divergence is not reflected in clinical outcome. PMID:21559106

Pandey, Vivek; Acharya, Kiran; Rao, Sharath; Rao, Sripathi

2011-01-01

203

Stable fixation of osteoporotic fractures and nonunions in the upper limb - life before the "locking plate".  

PubMed

I have had a wonderful opportunity over the past 30 years to surgically reconstruct many complex fractures and non- unions in the upper limb in the elderly patient with underlying osteoporosis and prior to the development of the "locked plate". This article will present a number of specific techniques using standard LC-DCP and screw in a variety of applications to provide stable internal fixation. These include the use of long plates; creating a "waved plate" initially described by Blatter and Weber; double plating; 3.5 mm intramedullary plate combined with a larger plate on the cortex; custom and machi- ned blade plates as well as enhancement of screw fixation with bone cement and/ or Norian SRS cement. PMID:21040646

Jupiter, J B; Wyss, H

2010-10-01

204

Population-based design of mandibular fixation plates with bone quality and morphology considerations.  

PubMed

In this paper we present a new population-based implant design methodology, which advances the state-of-the-art approaches by combining shape and bone quality information into the design strategy. The method may enhance the mechanical stability of the fixation and reduces the intra-operative in-plane bending which might impede the functionality of the locking mechanism. The computational method is presented for the case of mandibular locking fixation plates, where the mandibular angle and the bone quality at screw locations are taken into account. The method automatically derives the mandibular angle and the bone thickness and intensity values at the path of every screw from a set of computed tomography images. An optimization strategy is then used to optimize the two parameters of plate angle and screw position. The method was applied to two populations of different genders. Results for the new design are presented along with a comparison with a commercially available mandibular locking fixation plate (MODUS(®) TriLock(®) 2.0/2.3/2.5, Medartis AG, Basel, Switzerland). The proposed designs resulted in a statistically significant improvement in the available bone thickness when compared to the standard plate. There is a higher probability that the proposed implants cover areas of thicker cortical bone without compromising the bone mineral density around the screws. The obtained results allowed us to conclude that an angle and screw separation of 129° and 9 mm for females and 121° and 10 mm for males are more suitable designs than the commercially available 120° and 9 mm. PMID:23053302

Bousleiman, Habib; Iizuka, Tateyuki; Nolte, Lutz-Peter; Reyes, Mauricio

2013-02-01

205

Influence of Hydroxyapatite-Coated and Growth Factor–Releasing Interference Screws on Tendon-Bone Healing in an Ovine Model  

PubMed Central

Purpose Our purpose was to determine whether a bioresorbable interference screw coated with a hydroxyapatite-based mineral layer designed to release an engineered peptide growth factor (linkBMP-2 [where “BMP-2” indicates bone morphogenetic protein 2]) improved tendon-bone healing compared with a screw without coating. Methods Tagged linkBMP-2 peptides were used to quantify binding efficiency and release kinetics on 9 mineral-coated BIORCI screws (Smith & Nephew, Andover, MA). Fourteen mature female sheep were used in this study. In each of the 14 sheep, each stifle was randomized to either receive a linkBMP-2–coated or uncoated interference screw (n ± 14 per treatment). The sheep were euthanized at 6 weeks after surgery. Eight sheep were subjected to biomechanical testing for peak load at failure and stiffness, and six sheep were used for histologic analysis according to a semiquantitative scoring scale. Results The linkBMP-2 molecule bound efficiently to the surface of mineral-coated interference screws. Over 80% of the initially bound linkBMP-2 was released during a 6-week time frame in vitro. Peak load at failure in the linkBMP-2–coated interference screw group (mean ± SD, 449.3 ± 84.7 N) was not significantly different from that in the uncoated group (421.0 ± 61.8 N) (P = .22). Stiffness in the linkBMP-2–coated interference screw group (157.3 ± 39.6 N/mm) was not significantly different from that in the uncoated group (140.6 ± 20.3 N/mm) (P = .12). Histologic analysis showed that the tendons in the linkBMP-2–coated interference screw group had higher scores (better) than the uncoated group. In the linkBMP-2–coated interference screw group, mesenchymal cells were present at the interface between screw and tendon, whereas these cells were not present in the uncoated group. Conclusions We found that linkBMP-2 can be bound onto a mineral-coated BIORCI interference screw surface and subsequently released from the screw surface in a sustained manner. The histologic result of this study showed that the linkBMP-2–coated interference screw significantly improved the histologic scores of early tendon-bone healing in this sheep model. Clinical Relevance This linkBMP-2 coating material may improve early tendon/ligament fixation. PMID:19962070

Lu, Yan; Markel, Mark D.; Nemke, Brett; Lee, J. Sam; Graf, Ben K.; Murphy, William L.

2014-01-01

206

The acetabular component in total hip arthroplasty. Evaluation of different fixation principles.  

PubMed

Initial stability is necessary for permanent fixation of acetabular cups. Biologic reactions to submicron particles such as localized bone resorption may lead to implant failure. The aim of the study was to evaluate different fixation principles of acetabular components. Four randomized studies and one case-control study were performed to evaluate different bone cements, different cup designs, use of ceramic coating or not, different type of screws and the need of additional screw fixation or not. Radiostereometry (RSA) makes it possible to analyze small translations and rotations of implants with a high accuracy. This method is suitable for evaluation of early stability and was used in four of the studies. Clinical and radiological follow-up were performed regularly. The cements were tested in the laboratory. 30 patients (mean age 71 years, range: 63-76) received total hip arthroplasties and were randomised to fixation with Boneloc (14) or Palacos cum gentamicin (16) bone cement. The curing temperature was 23 degrees lower for the Boneloc cement but the tensile strength was reduced and the elastic modulus was lower compared to Palacos. The proximal cup migration was greater in the Boneloc group up to 12 months (p 0.04) and these cups migrated medially in contrast to a small lateral migration seen in the Palacos group (p 0.04). Radiolucencies were more pronounced in the Boneloc group at 12 months (p 0.04). 155 patients (171 hips, mean age 50 years, range: 24-64) received uncemented hip arthroplasties. 84 hips were randomised to the PCA and 87 to the Harris-Galante I designs. The 10-year survival rates were 85% for the PCA and 99% for the Harris-Galante I cups (revision as end-point). The wear and clinical results did not differ. 43 patients (mean age 60 years, range 44-68) received uncemented porous cups with a titanium mesh in pure titanium (Harris-Galante II) and were randomised to additional fixation with either biodegradable screws (23, poly-L-lactic acid, PLLA) or screws made of titanium alloy (20). Increased proximal and medial-lateral translations (p 0.02, 0.04) but less rotation around the longitudinal axis (p 0.04) were seen in the PLLA group up to 2 years. There were also more pronounced radiolucencies anteriorly in this group at 2 years. The clinical results did not differ. 23 uncemented porous cups (Harris-Galante II) with hydroxyapatite-tricalciumphosphate coating (HA/TCP) were pair-wise matched to uncoated cups. Up to 2 years, decreased rotations around the horizontal axis were recorded in the HA/TCP-coated cups. Central postoperative gaps were more frequently seen in the HA/TCP group (p < 0.01), but at 2 years radiolucencies were more pronounced in the uncoated group (p < 0.01). The wear and clinical results did not differ. 62 patients (64 hips, mean age 56 years, range: 32-75) were randomized to porous Trilogy cups with (30) and without (34) cluster holes for additional screw fixation. Up to 2 years there were no differences in migration, wear, radiographic findings or clinical results. In conclusion Boneloc cement was associated with poor fixation due to inferior mechanical properties. The PLLA screws did not provide sufficient stability. Unacceptably high failure rates were recorded for the PCA cup. HA/TCP coating improved the fixation and the interface of porous cups. HA/TCP coated porous cups can be fixed without adjunctive screw fixation. PMID:10572504

Thanner, J

1999-08-01

207

Temperature calculation for extruder screws with internal heat pipes  

NASA Astrophysics Data System (ADS)

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.

Lakemeyer, C.; Schöppner, V.

2014-05-01

208

Update: Biological Nitrogen Fixation.  

ERIC Educational Resources Information Center

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,…

Wiseman, Alan; And Others

1985-01-01

209

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

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

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

2014-01-01

210

Computer navigation assisted fixation in neglected C2-C3 dislocation in an adult  

PubMed Central

A 49-year-old male presented with neck pain and deformity following an industrial accident sustained two months back. His neurology was normal except for a minimal weakness in left biceps (grade 4/5). Radiographs, magnetic resonance imaging and computed tomographic scan revealed fracture dislocation of C2-C3 with significant lateral translation of C2 over C3 without disc herniation. In view of unsuccessful closed reduction and absent disc herniation at the level of dislocation, a posterior only reduction, stabilisation and fusion with Iso-C 3D computer navigation-assisted cervical pedicle screw fixation with transverse rod-screw construct was performed. At 6 months followup the patient was completely relieved of his symptoms and was able to return to his previous occupation. The rare case is reported for the management by Iso-C 3D computer navigation assisted cervical pedicle screw fixation and reduction with transverse rod-screw construct at each involved level. PMID:21886931

Rajasekaran, S; Subbiah, M; Shetty, Ajoy Prasad

2011-01-01

211

Screw expander for light duty diesel engines  

NASA Technical Reports Server (NTRS)

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.

1983-01-01

212

Posterior internal fixation plus vertebral bone implantation under navigational aid for thoracolumbar fracture treatment  

PubMed Central

The aim of this study was to investigate the method of posterior thoracolumbar vertebral pedicle screw reduction and fixation combined with vertebral bone implantation via the affected vertebral body under navigational aid for the treatment of thoracolumbar fractures. The efficacy of the procedure was also measured. Between June 2005 and March 2011, posterior thoracolumbar vertebral pedicle screw reduction and fixation plus artificial bone implantation via the affected vertebral pedicle under navigational aid was used to treat 30 patients with thoracolumbar fractures, including 18 males and 12 females, ranging in age from 21 to 57 years. Compared with the values prior to surgery, intraspinal occupation, vertebral height ratio and Cobb angle at the follow-up were significantly improved. At the long-term follow-up, the postoperative Cobb angle loss was <1° and the anterior vertebral body height loss was <2 mm. Posterior thoracolumbar vertebral pedicle screw reduction and fixation combined with vertebral bone implantation via the affected vertebral body under navigational aid may increase the accuracy and safety of surgery, and it is an ideal method of internal implantation. Bone implantation via the affected vertebral body may increase vertebral stability. PMID:23935737

ZHOU, WEI; KONG, WEIQING; ZHAO, BIZHEN; FU, YISHAN; ZHANG, TAO; XU, JIANGUANG

2013-01-01

213

Computer-assisted virtual technology in intracapsular condylar fracture with two resorbable long-screws.  

PubMed

Our aim was to fix intracapsular condylar fractures (ICF) with two resorbable long screws using preoperative computer-assisted virtual technology. From February 2008 to July 2011, 19 patients with ICF were treated with two resorbable long screws. Preoperatively we took panoramic radiographs and spiral computed tomography (CT). Depending on their digital imaging and communications in medicine (DICOM) data, the dislocated condylar segments were restored using the SimPlant Pro™ software, version 11.04. The mean (SD) widths of the condylar head and neck from lateral to medial were 19.01 (1.28)mm and 13.84 (1.13)mm, respectively. In all patients, the mandibles and the ICF seen intraoperatively corresponded with the preoperative three-dimensional and virtual reposition. All patients were followed up for 6-46 months (mean 21). Occlusion and mouth opening had been restored completely in all but one patient, and absolute anatomical reduction was also achieved in most cases. Computer-assisted virtual technology plays an important part in the diagnosis of ICF, as well as in its preoperative design. Fixation with only two resorbable long screws is an effective and reliable method for fixing ICF. PMID:22546281

Wang, W H; Deng, J Y; Zhu, J; Li, M; Xia, B; Xu, B

2013-03-01

214

C2 Pars/Pedicle Screws in Management of Craniocervical and Upper Cervical Instability  

PubMed Central

Study Design A retrospective study. Purpose To evaluate the efficacy and the safety of craniocervical and upper cervical stabilization by using C2 pars/pedicle screw fixations. Overview of Literature The management of craniocervical and upper cervical instability has progressed over the past two decades due to good achievements in the instrumentation and the increased awareness on spinal anatomy and biomechanics. However, there is insufficient studies or solid conclusions on this topic, thus, we tried to investigate and present our findings. Methods Twenty-two patients were operated upon and were followed up from March 2008 to October 2010. One patient had craniocervical instability (post-surgical), 15 patients had atlantoaxial instability of different etiologies (trauma, tumors, inflammatory and degenerative) and 6 patients had hangman fractures. Patients' ages ranged from 18 to 52 years old. with 5 female patients and 17 male patients. Results Radiological follow ups performed immediately post-operation showed good screw positioning and complete reductions in nearly all the cases. All patients were followed up for more than one year. Sound fusions were observed among all patients. Conclusions The use of pars/pedicle screws is a very effective, sound, safe and easy surgical modality for treating craniocervical, atlantoaxial and upper cervical instabilities. Increasing studies for the biomechanics of this important region and longer periods of follow-ups are necessary to document the usefulness of this modality when treating such patients. PMID:24761197

2014-01-01

215

Transmission of a Screw Dislocation Across a Coherent, Nonslipping Interface  

E-print Network

1 Transmission of a Screw Dislocation Across a Coherent, Nonslipping Interface Yao Shen materials (B), Energy methods (B), Transmission across interfaces Abstract Current research of slip transmission of a screw dislocation across a coherent, non-slipping interface is presented

Anderson, Peter M.

216

Iliac bone histomorphometry in adults and children with osteogenesis imperfecta.  

PubMed Central

Histomorphometric analysis was performed on transiliac undecalcified bone biopsies taken from eight adults and four children with osteogenesis imperfecta. Double tetracycline labelling done before the biopsy allowed measurement of the calcification rate in 11 patients. The adults, as well as the children, had thin iliac cortices and considerably decreased trabecular bone volume. In addition, the calcification rate was significantly reduced. Since the thickness index of osteoid seams was low or normal in all subjects, it indicated a reduced bone formation at the cellular level. In the adults, there was no significant increase in the parameters of bone resorption or in the bone formation rates at the basic multicellular unit and the tissue levels. Thus the histomorphometric profile of iliac bone in osteogenesis imperfecta is characterised by cortical and trabecular osteoporosis with decreased activity of the individual osteoblasts. These findings would suggest the use of therapeutic agents stimulating bone formation rather than agents inhibiting bone resorption in osteogenesis imperfecta. PMID:6490947

Ste-Marie, L G; Charhon, S A; Edouard, C; Chapuy, M C; Meunier, P J

1984-01-01

217

Emergency Endovascular 'Bridge' Treatment for Iliac-Enteric Fistula  

SciTech Connect

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.

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

218

Histomorphometry of fresh frozen iliac crest bone biopsies  

Microsoft Academic Search

Summary  Although methods are well established for the rapid histological preparation of fresh frozen soft tissues, they remain inadequate\\u000a for the preservation of hard tissues. A recent technique for sectioning fresh frozen bone, in which sections can be prepared\\u000a within an hour, has been applied to undecalcified human iliac crest bone biopsies. Quantitative analysis has shown that the\\u000a static remodeling variables

D. Howard Carter; Janet M. Barnes; Jean E. Aaron

1989-01-01

219

Percutaneous Treatment in Iliac Artery Occlusion: Long-Term Results  

SciTech Connect

We evaluated the long-term results of recanalization with primary stenting for patients with long and complex iliac artery occlusions. This was a retrospective nonrandomised study. Between 1995 and 1999, 138 patients underwent recanalization of an occluded iliac artery with subsequent stenting. Patency results were calculated using Kaplan-Meier analysis. The mean length of follow-up was 108 months. Variables affecting primary stent patency such as patient age; stent type and diameter; lesion site, shape, and length; Society of Cardiovascular and Interventional Radiology classification; total runoff score; Fontaine classification; and cardiovascular risk factors were analysed using Breslow test. These variables were then evaluated for their relation to stent patency using Cox proportional hazards test. Technical success was 99%. Primary patency rates were 90% (SE .024), 85% (SE .029), 80% (SE .034), and 68% (SE .052) at 3, 5, 7, and 10 years, respectively. Lesion site (p = 0.022) and stent diameter (p = 0.028) were shown to have a statistically significant influence on primary stent patency. Long-term results of iliac recanalization and stent placement were excellent, without major complications, even in highly complex vascular obstructions. A primary endovascular approach appears to be justified in the majority of patients as a less invasive alternative treatment to surgery. In any case, a first-line interventional approach should be considered in elderly patients or in patients with severe comorbidities.

Gandini, Roberto; Fabiano, Sebastiano; Chiocchi, Marcello; Chiappa, Roberto, E-mail: robchiap@libero.it; Simonetti, Giovanni [University of Rome Tor Vergata, Departments of Diagnostic Imaging, Interventional Radiology, Molecular Imaging, and Radiotherapy (Italy)

2008-11-15

220

Novel posterior fixation keratoprosthesis  

NASA Astrophysics Data System (ADS)

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.

Lacombe, Emmanuel

1992-08-01

221

A Novel Pedicle Screw with Mobile Connection: A Pilot Study  

PubMed Central

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

Oshima, Masashi; Ajiro, Yasumitsu; Uei, Hiroshi

2014-01-01

222

CARBON DIOXIDE FIXATION.  

SciTech Connect

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.

FUJITA,E.

2000-01-12

223

[Results of 30 keratoprostheses with retrocorneal fixation].  

PubMed

Keratoprosthesis is the last solution for corneally blind patients who cannot benefit from corneal grafts. The indications are limited to blind patients with monophthalmia and bilateral problems that are otherwise untreatable. After implanting the Choyce and Strampelli's devices for more than 10 years, we abandoned these anterior fixation techniques and now use a keratoprosthesis in which the sole mechanical fixation consists of a posterior support which is subsequently sealed by the fibrosis produced by the endothelial-Descement tissues. This new prosthesis is made of two pieces, an optic and an haptic fashioned out of CQ-PMMA. To minimize expulsion, the haptic outer diameter is greater than the central corneal orifice through which the optic is inserted and screwed into the haptic. The keratoprosthesis refractive power can be easily adjusted after lensectomy by changing the 40 D for a 63 D optic. The prosthesis is implanted in a single step surgical procedure, and can be implanted in phakic eyes while respecting the physiology and anatomy of these fragile eyes. This single step procedure reduces the usual repeated operations required when using, other techniques. We operated 12 cases of pseudopemphigus, 9 cases of burns, 7 cases of trachoma, and 2 cases of pseudophakic oedema with good cosmetic and visual results with a follow-up ranging from several months to more than 3 years. The results obtained with this new keratoprosthesis are encouraging. The results have been analysed and classified into: anatomic and functional success 20 cases, anatomic success and functional failures 4 cases, anatomic failures 6 cases. PMID:8282949

Lacombe, E

1993-01-01

224

A technique for retrieving fractured implant screws.  

PubMed

The use of dental implants as a source of support and retention for fixed restorations is common. This report describes the use of a fragment removal instrument together with the use of ultrasonic instrumentation to retrieve a screw fragment. PMID:24268685

Imam, Ahmad Y; Moshaverinia, Alireza; Chee, Winston W L; McGlumphy, Edwin A

2014-01-01

225

Visuality in The Turn of the Screw: \\  

Microsoft Academic Search

Scarry is referring to the half-formed, transitory, vanishing quality of ghosts—a quality shared, more or less, by any mental image we might choose to form in the mind's eye. In this sense The Turn of the Screw is a perfect ghost story. It is a story about seeing ghosts, about picturing them, and perhaps about imagining them altogether. In fact,

Josh Rothman

226

Screw-Together George W. Hart  

E-print Network

Screw-Together Cube George W. Hart Dept. Computer Science Stony Brook University http related forms. Martin Gardner credits a related three-piece cube dissection to John E. Morse [1]. William and George Miller is commercially available at [3]. I came to appreciate the elegance of this family of forms

227

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

PubMed

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

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

2014-12-01

228

Percutaneous transgluteal coil embolization of bilateral internal iliac artery aneurysms via direct superior gluteal artery access.  

PubMed

Proximal surgical ligation of internal iliac artery aneurysms without occlusion of the outflow vessels can lead to continued aneurysm expansion and possible rupture from retrograde flow. Percutaneous embolization options are limited because there is no direct transarterial antegrade access to the aneurysm if the internal iliac artery has been ligated. We describe the first case of bilateral percutaneous transgluteal coil embolizations to treat surgically excluded bilateral internal iliac artery aneurysms. PMID:23890817

Kabutey, Nii-Kabu; Siracuse, Jeffrey J; Gill, Heather; Kundi, Rishi; Meltzer, Andrew J; Schneider, Darren B

2014-07-01

229

An investigation of post-operative morbidity following iliac crest graft harvesting  

Microsoft Academic Search

Objective A study which examined the morbidity experienced by patients who underwent iliac crest bone graft procedures.Design A post-operative questionnaire was forwarded to patients who underwent iliac crest bone graft procedures at a single centre.Subjects One hundred and fourteen patients underwent iliac crest bone grafts for intra-oral augmentation.Results Ninety-eight patients (80%) returned post-operative questionnaires. Eighty of the 98 (81.6%) patients

G C Kostakis; A Joshi

2004-01-01

230

Medial Patellofemoral Ligament Reconstruction: A New Technique for Graft Fixation at the Patella Without Implants  

PubMed Central

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

Shafizadeh, Sven; Balke, Maurice

2014-01-01

231

Biomechanical analysis and design of a dynamic spinal fixator using topology optimization: a finite element analysis.  

PubMed

Surgeons often use spinal fixators to manage spinal instability. Dynesys (DY) is a type of dynamic fixator that is designed to restore spinal stability and to provide flexibility. The aim of this study was to design a new spinal fixator using topology optimization [the topology design (TD) system]. Here, we constructed finite element (FE) models of degenerative disc disease, DY, and the TD system. A hybrid-controlled analysis was applied to each of the three FE models. The rod structure of the topology optimization was modelled at a 39 % reduced volume compared with the rigid rod. The TD system was similar to the DY system in terms of stiffness. In contrast, the TD system reduced the cranial adjacent disc stress and facet contact force at the adjacent level. The TD system also reduced pedicle screw stresses in flexion, extension, and lateral bending. PMID:24737048

Lin, Hung-Ming; Liu, Chien-Lin; Pan, Yung-Ning; Huang, Chang-Hung; Shih, Shih-Liang; Wei, Shun-Hwa; Chen, Chen-Sheng

2014-05-01

232

Osteotomy and fracture fixation in children and teenagers.  

PubMed

Significant changes have occurred recently in fixation methods following fracture or osteotomy in children and teenagers. Children have benefited the most from these advances. A child's growth is anatomically and physiologically ensured by the growth plate and periosteum. The need to keep the periosteum intact during trauma cases has led to the introduction of flexible intramedullary nailing. We will review the basic principles of this safe, universally adopted technique, and also describe available material, length and diameter options. The problems and the limitations of this method will be discussed extensively. In orthopedics, the desire to preserve the periosteum has led to the use of locking compression plates. Because of their low profile and high stability, they allow the micromovements essential for bone union. These new methods reduce the immobilization period and allow autonomy to be regained more quickly, which is especially important in children with neurological impairment. The need to preserve the growth plate, which is well known in pediatric surgery, is reviewed with the goal of summarizing current experimental data on standard fracture and osteotomy fixation methods. Adjustable block stop wires provide better control over compression. These provide an alternate means of fixation between K-wires and screws (now cannulated) and have contributed to the development of minimally invasive surgical techniques. The aim of this lecture is to provide a rationale for the distinct technical features of pediatric surgery, while emphasizing the close relationship between the physiology of growth, bone healing and technical advances. PMID:24394918

de Billy, B; Gindraux, F; Langlais, J

2014-02-01

233

New method for fixation point of tibialis posterior tendon transfer  

PubMed Central

Background The transfer of the tibialis posterior tendon to the dorsum of foot can restore the function of theparalyzed dorsiflexor muscles of the foot and ankle. In order to reduce the wound complication in the insertionsite of tendon to bone by a plantar knop we used a new method of fixation by an absorbable screw inserted dorsally. Methods we performed this operation on 15 patients in a 3 years period. All patients had drop foot deformitydue to irreversible lesions of the peroneal nerve. The inclusion criteria was the peroneal nerve palsy that wasnot improved after 18 months even by using nerve releasing or nerve repairing. All patients were evaluatedafter 6 months for ankle function and wound complications. Result Of 15 patients one was excluded from study. At 6 month ten patients got excellent score (66%) and 4good score (26%) further ankle function. There was no wound complication at insertion site Conclusion This simple modification for insertion site fixation had good result in restoring ankle functionwhiles eliminated the possibility of plantar pressure sores caused by fixation knop. PMID:24926176

Yeganeh, Ali; Motaghi, Arash; Shahhoseini, Gholamreza; Farahini, Hosein

2013-01-01

234

Endovascular Therapeutic Options for Isolated Iliac Aneurysms with a Working Classification  

SciTech Connect

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)

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

235

Numerical investigations of MRI RF field induced heating for external fixation devices  

PubMed Central

Background The magnetic resonance imaging (MRI) radio frequency (RF) field induced heating on external fixation devices can be very high in the vicinity of device screws. Such induced RF heating is related to device constructs, device placements, as well as the device insertion depth into human subjects. In this study, computational modeling is performed to determine factors associated with such induced heating. Methods Numerical modeling, based on the finite-difference time-domain (FDTD) method, is used to evaluate the temperature rises near external device screw tips inside the ASTM phantom for both 1.5-T and 3-T MRI systems. The modeling approach consists of 1) the development of RF coils for 1.5-T and 3-T, 2) the electromagnetic simulations of energy deposition near the screw tips of external fixation devices, and 3) the thermal simulations of temperature rises near the tips of these devices. Results It is found that changing insertion depth and screw spacing could largely affect the heating of these devices. In 1.5-T MRI system, smaller insertion depth and larger pin spacing will lead to higher temperature rise. However, for 3-T MRI system, the relation is not very clear when insertion depth is larger than 5?cm or when pin spacing became larger than 20?cm. The effect of connection bar material on device heating is also studied and the heating mechanism of the device is analysed. Conclusions Numerical simulation is used to study RF heating for external fixation devices in both 1.5-T and 3-T MRI coils. Typically, shallower insertion depth and larger pin spacing with conductive bar lead to higher RF heating. The heating mechanism is explained using induced current along the device and power decay inside ASTM phantom. PMID:23394173

2013-01-01

236

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

PubMed

Pedicle screws have become the gold standard of spinal instrumentation over the past decade owing to their biomechanical superiority. Despite their advantages, pedicle screw instrumentation is potentially dangerous, and surgeons wish to improve accuracy of screw placement to avoid complications associated with screw misplacement. The anatomy of the pedicles is variable throughout the spine, and several landmarks and trajectories have been suggested to aid safe placement of pedicle screws in the spine. Several techniques such as x-ray and computed tomography scan imaging coupled with computer-aided navigation are available to improve accuracy of screw insertion. Intraoperative neuromonitoring with the help of triggered electromyographic recordings has evolved as an objective evidence of assessing pedicle breach and proximity of the screw to neural structures. While all imaging and electrophysiological modalities should be applied on an individualized basis, finally no adjunctive technique can fully replace the need for surgical expertise and experience. PMID:23207586

Joglekar, Siddharth B; Mehbod, Amir A

2012-12-01

237

The Mechanics of External Fixation  

Microsoft Academic Search

External fixation has evolved from being used primarily as a last resort fixation method to becoming a main stream technique\\u000a used to treat a myriad of bone and soft tissue pathologies. Techniques in limb reconstruction continue to advance largely\\u000a as a result of the use of these external devices. A thorough understanding of the biomechanical principles of external fixation\\u000a is

Austin T. Fragomen; S. Robert Rozbruch

2007-01-01

238

Posterior Surgery for Adolescent Idiopathic Scoliosis With Pedicle Screws and Ultra-high Molecular Weight Polyethylene Tape: Achieving the Ideal Thoracic Kyphosis.  

PubMed

STUDY DESIGN:: Prospective clinical case series. OBJECTIVES:: To describe our surgical procedure and results for posterior correction and fusion with a hybrid approach using pedicle screws, hooks, and ultra-high molecular weight polyethylene tape with direct vertebral rotation (DVR) (the PSTH-DVR procedure) for treatment of adolescent idiopathic scoliosis (AIS) with satisfactory correction in the coronal and sagittal planes. SUMMARY OF BACKGROUND DATA:: Introduction of segmental pedicle screws in posterior surgery for AIS has facilitated good correction and fusion. However, procedures using only pedicle screws have risks during screw insertion, higher costs, and decreased postoperative thoracic kyphosis. We have obtained good outcomes compared with segmental pedicle screw fixation in surgery for AIS using a relatively simple operative procedure (PSTH-DVR) that uses fewer pedicle screws. METHODS:: The subjects were 30 consecutive patients with AIS who underwent the PSTH-DVR procedure and were followed for a minimum of two years. Preoperative flexibility, preoperative and postoperative Cobb angles, correction rates, loss of correction, thoracic kyphotic angles (T5-T12), coronal balance, sagittal balance, and shoulder balance were measured on plain radiographs. Rib hump, operation time, estimated blood loss, spinal cord monitoring findings, complications, and scoliosis research society (SRS)-22 scores were also examined. RESULTS:: The mean preoperative curve of 58.0° (range 40°-96°) was corrected to a mean of 9.9° postoperatively, and the correction rate was 83.6%. Fusion was obtained in all patients without loss of correction. In ten cases with preoperative kyphosis angles (T5-T12) <10°, the preoperative mean of 5.8° improved to 20.2° at the final follow-up. Rib hump and coronal, sagittal and shoulder balances were also improved, and good SRS-22 scores were achieved at final follow-up. CONCLUSION:: The correction of deformity with PSTH-DVR is equivalent to that of all-pedicle screw constructs. The procedure gives favorable correction, is advantageous for kyphosis compared with segmental screw fixation, and uses the minimum number of pedicle screws. Therefore, the PSTH-DVR procedure may be useful for treatment of idiopathic scoliosis. PMID:22907066

Imagama, Shiro; Ito, Zenya; Wakao, Norimitsu; Ando, Kei; Hirano, Kenichi; Tauchi, Ryoji; Muramoto, Akio; Matsui, Hiroki; Matsumoto, Tomohiro; Sakai, Yoshihito; Katayama, Yoshito; Matsuyama, Yukihiro; Ishiguro, Naoki

2012-08-18

239

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

Microsoft Academic Search

\\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

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

240

Allograft anterior tibialis tendon with bioabsorbable interference screw fixation in anterior cruciate ligament reconstruction  

Microsoft Academic Search

For a variety of reasons, bone–patellar tendon–bone and Achilles tendon allografts have been used more commonly in anterior cruciate ligament reconstruction. Soft-tissue allografts used mainly are the semitendinosus, gracilis, and occasionally the quadriceps tendons. The anterior tibialis tendon is a thick, strong tendon that can be prepared with one doubling of the graft, has a large cross-sectional area, and has

David N. M. Caborn; Jeffrey B. Selby

2002-01-01

241

Histological Study on the Left Common Iliac Vein Spur  

PubMed Central

The spur occasionally seen in a left common iliac vein was investigated by anatomical and histological examination of cadavers so the occurrence mechanism could be discussed. Spurs were found in six cases of the 28 cadavers (21.4%) and they were classified into few different kinds of composition of endosporia, tunica media and adventitia. It is considered that there may be different formation mechanisms and stages even in cases of similar anatomical finding. (*English translation of J Jpn Coll Angiol 2013; 53: 43-47) PMID:25298827

Ohta, Takashi; Hayashi, Shogo; Yokoi, Toyoharu; Arima, Takahiro; Asamoto, Ken; Nakano, Takashi

2014-01-01

242

Helical Screw Expander Evaluation Project. Final report  

Microsoft Academic Search

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

McKay

1982-01-01

243

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

PubMed Central

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

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

2013-01-01

244

Fixation Time for Evolutionary Graphs  

NASA Astrophysics Data System (ADS)

Evolutionary graph theory (EGT) is recently proposed by Lieberman et al. in 2005. EGT is successful for explaining biological evolution and some social phenomena. It is extremely important to consider the time of fixation for EGT in many practical problems, including evolutionary theory and the evolution of cooperation. This study characterizes the time to asymptotically reach fixation.

Nie, Pu-Yan; Zhang, Pei-Ai

245

Biomechanical in vitro evaluation of three stable internal fixation techniques used in sagittal osteotomy of the mandibular ramus: a study in sheep mandibles  

PubMed Central

Among the osteotomies performed in orthognathic surgery, the sagittal osteotomy of the mandibular ramus (SOMR) is the most common, allowing a great range of movements and stable internal fixation (SIF), therefore eliminating the need of maxillomandibular block in the postoperative period. Objectives: The purpose of this study was to evaluate the biomechanical resistance of three national systems used for SIF in SOMR in sheep mandibles. Material and methods: The study was performed in 30 sheep hemi-mandibles randomly divided into 3 experimental groups, each containing 10 hemi-mandibles. The samples were measured to avoid discrepancies and then subjected to SOMR with 5-mm advancement. In group I, 2.0x12 mm screws were used for fixation, inserted in an inverted "L" pattern (inverted "L" group). In group II, fixation was performed with two 2.0x12 mm screws, positioned in a linear pattern and a 4-hole straight miniplate and four 2.0x6.0 mm monocortical screws (hybrid group). In group III, fixation was performed with two 4-hole straight miniplates and eight 2.0x6.0 mm monocortical screws (mini plate group). All materials used for SIF were supplied by Osteosin - SIN. The hemimandibles were subjected to vertical linear load test by Kratos K2000MP mechanical testing unit for loading registration and displacement. Results: All groups showed similar resistance during mechanical test for loading and displacement, with no statistically significant differences between groups according to analysis of variance. Conclusion: These results indicate that the three techniques of fixation are equally effective for clinical fixation of SOMR. PMID:23032203

de OLIVERA, Leandro Benetti; SANT'ANA, Eduardo; MANZATO, Antonio Jose; GUERRA, Fabio Luis Bunemer; ARNETT, G. William

2012-01-01

246

Eighth international congress on nitrogen fixation  

SciTech Connect

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.

Not Available

1990-01-01

247

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

PubMed Central

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

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

2014-01-01

248

A Comparative Evaluation of Femorofemoral Crossover Bypass and Iliofemoral Bypass for Unilateral Iliac Artery Occlusive Disease  

Microsoft Academic Search

The purpose of this study was to compare the results of extra-anatomic femorofemoral crossover bypass grafting to the anatomic iliofemoral bypass grafting procedure in the treatment of patients with unilateral iliac artery occlusive disease with respect to patency and limb salvage.The records of all patients with unilateral iliac artery disease who underwent revas cularization between January 1988 and December 1995

Munier M. Nazzal; Jamal J. Hoballah; Claudio Jacobovicz; Chittur R. Mohan; Mario Martinasevic; Stephen M. Ryan; William J. Sharp; Timothy F. Kresowik; John D. Corson

1998-01-01

249

Treatment of Type I Endoleak in an Iliac Aneurysm with Balloon Expandable Palmaz Stent  

Microsoft Academic Search

Endovascular exclusion of the peripheral arterial aneurysms with covered stent grafts have been used to decrease the operative morbidity and mortality in comorbid old patients. However, endoleaks remain a problem. The authors present a case of left common iliac artery aneurysm, which was treated by endovascular therapy. Initially, internal iliac artery was occluded with coil embolization to prevent type II

Kutsi Koseoglu; Mustafa Parildar; Ismail Oran; Ahmet Memis

2003-01-01

250

Static histomorphometry of human iliac crest and vertebral trabecular bone: a comparative study  

Microsoft Academic Search

We recently developed a new, rapid method for conducting static histomorphometry on large histologic sections. This method has now been applied on both iliac crest and lumbar vertebral bone to compare the age-related changes at these two skeletal sites and to investigate the correlation between the histomorphometric measures at the iliac crest and the vertebral body. The material comprised matched

J. S. Thomsen; E. N. Ebbesen; Li. Mosekilde

2002-01-01

251

Experimental investigation of the use of drag reducing agents in conjunction with twin-screw multiphase pumps  

E-print Network

: 1) simple screw pump, 2) single screw pump, 3) twin-screw pump, and 4) three-screw pump. The simple screw pump is an extensive version of the axial-flow, or propeller, pump. It is based on the principle of Archimedes screw and has been developed...: 1) simple screw pump, 2) single screw pump, 3) twin-screw pump, and 4) three-screw pump. The simple screw pump is an extensive version of the axial-flow, or propeller, pump. It is based on the principle of Archimedes screw and has been developed...

Carrillo Plazas, Gabriel D

2012-06-07

252

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

PubMed

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

Ishizuka, Shuichi; Habara, Maoto; Nasu, Kenya

2014-03-01

253

Use of anteroposterior view fluoroscopy for targeting percutaneous pedicle screws in cases of spinal deformity with axial rotation.  

PubMed

Object Over the past decade percutaneous pedicle screws have become popular for the minimally invasive treatment of spinal disorders. However, until the last 5 years the presence of a significant spinal deformity was regarded as a relative contraindication for percutaneous instrumentation. Recent advances in surgical technique and intraoperative technology have made percutaneous fixation in complex spinal pathologies more commonplace. The authors report their experience using a parsimonious method for uniplanar fluoroscopic targeting of pedicles in challenging cases. Methods The authors performed a retrospective analysis of patients with adult spinal deformity who underwent percutaneous pedicle screw instrumentation from 2008 to 2013. Cases were included if a spiral slice postoperative CT scan was obtained. All cases had a minimum of 10° of axial rotation and typically had additional accompanying anatomical abnormalities. Screws were assessed for any pedicle violations as well as any impingement of the surrounding facet joints. Results A total of 410 pedicle screws were placed in 36 patients with an average 6.4 levels of instrumentation per patient. The mean age was 67 years (range 44-86 years) and there were 25 females. Of the 410 screws, 29 (7.1%) had some medial or lateral pedicle violation. Of these, 15 (3.7%) were Grade 1, 6 (1.4%) were Grade 2, and 8 (2.0%) were Grade 3 violations. Of the Grade 3 violations, 2 each were at the L-4, L-5, and S-1 levels, and 1 each was at the T-10 and L-1 levels. Two of the patients had symptoms and both underwent screw repositioning, one during the same admission and the other in a delayed fashion. Both were at the L-5 and S-1 levels with anatomically highly medialized pedicles. There were no motor deficits, and both removals were for numbness. Of the 72 screws at the proximal end of the construct, there were 6 facet violations (8.3%). Four (5.6%) of these were Grade 1, 1 (1.4%) was Grade 2, and 1 (1.4%) was Grade 3. Conclusions The anteroposterior fluoroscopic technique can be effectively used by spinal surgeons to cannulate the pedicles in patients with rotational deformities. The complication rate in this challenging population is acceptable and is in accordance with the existing literature. However, caution should be used at L-5 and S-1 when the pedicle is narrow and highly medialized, rendering an indistinct medial wall on anteroposterior imaging. PMID:25170657

Ahmad, Faiz U; Wang, Michael Y

2014-11-01

254

Unilateral versus bilateral pedicle screw instrumentation for single-level minimally invasive transforaminal lumbar interbody fusion.  

PubMed

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

Shen, Xiaolong; Zhang, Hailong; Gu, Xin; Gu, Guangfei; Zhou, Xu; He, Shisheng

2014-09-01

255

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

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

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

2013-12-01

256

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

PubMed Central

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

Lee, Sandra; Vaidya, Rahul

2008-01-01

257

[Improvement of graft fixation methods for reconstruction of the anterior cruciate ligament].  

PubMed

In N. N. Priorov Institute of Traumatology and Orthopedics, atografts with bone blocks have been extensively used over the last 10 years to reconstruct anterior cruciate ligament after sports, ballet, and circus injuries. The autografts are fixed by interference screws at the level of the articular space. Reconstruction of the anterior cruciate ligament by this technique was performed in more than 800 patients (99%) between 1998 and 2006. Positive outcome was achieved in the majority of the cases (93%). A more universal method for the fixation of autografts with bone blocks has been employed since 2005 using polylactic acid pins, the Rigidfix system, and Milago interference screws. The Rigidfix system is most suitable for revisional reconstruction and may serve as an alternative tool for the primary reconstruction of the anterior cruciate ligament. PMID:19065738

Orletski?, A K; Timchenko, D O

2008-01-01

258

Evaluation of Bone Fixation Implants  

E-print Network

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...

Perkins, Luke 1990-

2012-12-10

259

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

PubMed Central

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

Amaritsakul, Yongyut; Chao, Ching-Kong

2013-01-01

260

Screw dislocations in GaN  

SciTech Connect

GaN has received much attention over the past few years because of several new applications, including light emitting diodes, blue laser diodes and high-power microwave transistors. One of the biggest problems is a high density of structural defects, mostly dislocations, due to a lack of a suitable lattice-matched substrate since bulk GaN is difficult to grow in large sizes. Transmission Electron Microscopy (TEM) has been applied to study defects in plan-view and cross-sections on samples prepared by conventional techniques such as mechanical thinning and precision ion milling. The density of dislocations close to the sample surface of a 1 mm-thick HVPE sample was in the range of 3x109 cm-2. All three types of dislocations were present in these samples, and almost 50 percent were screw dislocations. Our studies suggest that the core structure of screw dislocations in the same material might differ when the material is grown by different methods.

Liliental-Weber, Zuzanna; Jasinski, Jacek B.; Washburn, Jack; O'Keefe, Michael A.

2002-02-15

261

Successful treatment of posttraumatic phlegmasia cerulea dolens by reconstructing the external iliac vein: a case report  

PubMed Central

Introduction Phlegmasia cerulea dolens is a rare condition caused by complete venous occlusion leading to impaired arterial flow. To prevent progression to limb gangrene, prompt diagnosis and treatment initiation are paramount. Here we report a rare case of posttraumatic phlegmasia cerulea dolens after ligation of the iliac vein to save the patient's life, with successful treatment by reconstructing the external iliac vein. This is the first report of posttraumatic phlegmasia cerulea dolens induced by iliac vein ligation. Case presentation A 49-year-old Chinese man was admitted to a local hospital for severe knife trauma with massive intraperitoneal bleeding. During exploratory laparotomy, he was diagnosed with traumatic rupture of his left external iliac vein without injury to the iliac artery. The proximal and distal parts of his injured external iliac vein were ligated to control the bleeding and rescue him, but his left leg quickly became severe swollen, cyanotic and pulseless. He was diagnosed with posttraumatic phlegmasia cerulea dolens after being transferred to our university hospital. After a retrievable filter was placed in his inferior vena cava via his right femoral vein, he underwent reopening of his abdomen followed by successful surgical reconstruction of his left iliac vein. He was treated with anticoagulation therapy postoperatively and his signs and symptoms improved markedly. He was discharged in a stable condition, with nearly full resolution of symptoms, 35 days after the operation. Conclusions Our case demonstrates that ligation of an injured iliac vein may induce phlegmasia cerulea dolens in a posttraumatic scenario; prompt reconstruction of the iliac vein to restore the venous drainage is an effective treatment for phlegmasia cerulea dolens with impending gangrene. PMID:24885801

2014-01-01

262

Distal radius fixation through a mini-invasive approach of 15 mm. PART 1: a series of 144 cases.  

PubMed

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

Lebailly, Frédéric; Zemirline, Ahmed; Facca, Sybille; Gouzou, Stéphanie; Liverneaux, Philippe

2014-08-01

263

Optimized rotor pitch distributions for screw spindle vacuum pumps  

Microsoft Academic Search

Screw spindle vacuum pumps are characterised by a high suction performance and the ability to achieve high pressure ratios. Screw spindle vacuum pumps have varying progressions for the rotor pitch gradient, depending on the manufacturer. From a scientific point of view, the question arises which rotor gradient along the rotors has to be preferred for a particular set of operating

D. Pfaller; A. Brümmer; K. Kauder

2011-01-01

264

Transmission of a Screw Dislocation Across a Coherent, Slipping Interface  

E-print Network

1 Transmission of a Screw Dislocation Across a Coherent, Slipping Interface Yao Shen(a) and Peter M of interfacial sliding during dislocation transmission. A straight screw dislocation parallel to a bimaterial. Interfacial sliding is predicted to increase the critical applied shear crit of interfaces for transmission

Anderson, Peter M.

265

Fatigue strength of common tibial intramedullary nail distal locking screws  

Microsoft Academic Search

BACKGROUND: Premature failure of either the nail and\\/or locking screws with unstable fracture patterns may lead to angulation, shortening, malunion, and IM nail migration. Up to thirty percent of all unreamed nail locking screws can break after initial weight bearing is allowed at 8–10 weeks if union has not occurred. The primary problem this presents is hardware removal during revision

Lanny V. Griffin; Robert M Harris; Joseph J Zubak

2009-01-01

266

FORMING PROCESS OF SCREW SPIKE IN DOUBLE CONFIGURATION  

Microsoft Academic Search

Summary. In this paper technology of screw spikes manufacturing, based on the flashless forging and hot rolling in double configuration, is presented. The forging takes place in closed dies and the obtained workpiece is rolled in its middle part on cross-wedge rolling mill in order to make screw thread. As the result of this process, it is possible to eliminate

COMPLAS VIII; S. Wero?ski; Andrzej Gontarz; Zbigniew Pater

267

Application studies of CFRTP hexagon socket head cap screws  

NASA Astrophysics Data System (ADS)

PPS thermoplastic CFRP is used to fabricate screws via injection molding; these samples were tested for tensile strength and torque vs axial tension. Attention was given to the effects of various lubricants. When MoS2 was applied to the screw's threading, its axial tension increased from 10 to 16 kN.

Sano, Akihiko; Matsumoto, Masaru

268

DESIGN OF OIL-LESS HELICAL TWIN SCREW MACHINES  

Microsoft Academic Search

A twin screw machine is described as oil-less when the working chamber between the contacting helical rotors and the casing, which is usually flooded by oil, operates with no oil or a very small quantity of oil injected in it. Such a mode of operation has been shown to be viable in two experimental projects in which three screw machine

Ian K Smith; Ahmed Kovaèeviæ

269

MATHEMATICAL ANALYSIS OF OIL INJECTED TWIN SCREW COMPRESSOR  

Microsoft Academic Search

Mathematical analysis of oil injected twin-screw compressor is carried out on the basis of the laws of perfect gas, and standard thermodynamic relations. Performance of an oil injected twin-screw compressor depends on a large number of design parameters. A computer model for calculating compressor performance and to validate the results with experimental data is developed. The flow coefficients required to

N. Seshaiah; R. K. Sahoo

270

Performance Analysis of Oil Injected Twin Screw Compressor  

Microsoft Academic Search

Oil injected twin-screw air compressors are widely used for medium pressure applications in cryogenic industries. Conversion of these compressors for helium applications is in great demand due to their inherent advantages. A mathematical model of an oil injected twin-screw compressor has been constructed basing on the laws of perfect gas and standard thermodynamic relations to evaluate compressor efficiencies. The complete

N. Seshaiah; Subrata Kr; Ranjit Kr; Sunil Kr

2006-01-01

271

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

SciTech Connect

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.

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

272

Performance of Screw Compressor for Small-Capacity Helium Refrigerators  

NASA Astrophysics Data System (ADS)

A helium compressor is one of the important components comprising a cryogenic refrigerator. The purpous of this investigation is to develop a new small-capacity helium screw compressor. The performance of a single-stage compressor at high compression ratio and the cooling performance of the compressor are investigated. A semi-hermetic screw compressor with new profile screw rotors, with which high performance can be obtained, is utilized in this investigation. Lubricating oil is applied to cool the compressor motor and the compressed gas. As a result, an overall isentropic efficiency of 80% is obtained when helium is compressed to a compression ratio of 19.8 with a single-stage screw compressor. At the same time, the temperature of a compressor motor and discharge gas can be maintained at low levels. Therefore, it is found that a single-stage screw compressor can compress helium to high compression ratio.

Urashin, Masayuki; Matsubara, Katsumi; Izunaga, Yasushi

273

Open reduction and percutaneous fixation of a rare hamstring avulsion fracture.  

PubMed

Surgical treatment has been advocated for ischial tuberosity avulsion fractures in athletes. This article presents the case of an elite rower with a large avulsion fracture involving the entire inferior obturator ring with a novel technique for open reduction using a limited Kocher-Langenbeck approach and percutaneous fixation using posterior column lag screws. The fracture healed anatomically, and at 1?year follow-up the patient had full range of motion, normal gait and had returned to high-level sporting activities. PMID:25257887

Watts, Chad D; Hartzler, Robert U; Cross, William W

2014-01-01

274

A Surgical Method for Determining Proper Screw Length in ACDF  

PubMed Central

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.

Park, Hae-Gi; Kang, Moo-Sung; Kim, Kyung-Hyun; Park, Jeong-Yoon; Kim, Keun-Su

2014-01-01

275

Comparison of unipolar and bipolar active fixation atrial pacing leads.  

PubMed

The purpose of this investigation was to compare the acute pacing and sensing characteristics of a new bipolar active fixation atrial pacing lead with those of a unipolar atrial lead of similar design. Pacing threshold voltage and current, lead impedance, and atrial electrogram amplitude and slew rate were measured at the time of surgery in 28 consecutive patients undergoing DDD pacing system implantation. Eleven patients received a Medtronic 6957J-58 unipolar active fixation atrial lead and 17 patients were given a Medtronic 4016-58 bipolar lead. Both leads are polyurethane-insulated with the distal electrode being a platinum alloy screw-helix with a surface area of 8.0 mm2. There were no significant differences in the threshold voltage (1.01 V unipolar versus 1.05 V bipolar) or current (1.93 mA unipolar versus 1.78 mA bipolar) of the two leads. The mean impedance of the bipolar active fixation lead was 618 ohms compared to 479 ohms for the unipolar lead (p = 0.02). The mean amplitude of the atrial electrogram was 4.64 mV for the bipolar lead and 3.11 mV for the unipolar lead (p = 0.02). The atrial electrogram exceeded 5 mV in 10 of 17 patients with the bipolar lead but zero of 11 with the unipolar lead. There was no significant difference in the mean slew rate of the leads (1.09 V/s bipolar versus 0.73 V/s unipolar; p = 0.18). Over a follow-up period of up to 10 months, all patients remained in either the DDD or DDI modes with no episodes of atrial sensing or pacing failure.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2456532

Kay, G N; Epstein, A E; Plumb, V J

1988-05-01

276

Design of Fracture Fixation Plate for Necessary and Sufficient Bone Stress Shielding  

NASA Astrophysics Data System (ADS)

The objective of treating the fractured bone is to achieve painless functioning of the bone and undisturbed healing at the fracture. Internal fixation by stiff bone-plate is one of the standard methods to achieve these objectives. Recently, there is considerable interest in the usage of compliant plates to enhance bone healing with reduced stress shielding. Herein, first an analytical solution is developed to determine screw forces in the bone-plate assembly that conforms the plate and the bone under bending load. Based on the analytical calculations, an optimal fixator plate selection criterion for necessary and sufficient stress shielding is proposed. Second, effectiveness of employing a non-homogeneous stiffness graded (SG) plate rather than a homogeneous stainless steel (SS) plate for stress shielding is investigated using a finite element method. It is found that stress shielding on bone by SG plate is less compared to SS plate.

Ramakrishna, Kotlanka; Sridhar, Idapalapati; Sivashanker, Sathiamoorthy; Khong, Kok Sun; Ghista, Dhanjoo N.

277

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

SciTech Connect

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.

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

278

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

SciTech Connect

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

Oguzkurt, Levent, E-mail: loguzkurt@yahoo.com; Tercan, Fahri [Baskent University, Adana Teaching and Medical Research Center, Department of Radiology (Turkey); Sener, Mesut [Baskent University, Adana Teaching and Medical Research Center, Department of Anesthesiology and Reanimation (Turkey)

2006-06-15

279

External iliac vein - transplant ureteral fistula combined with renal cell carcinoma: an unusual case of hematuria  

PubMed Central

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

Luo, Jin-dan; Liu, Ben; Wang, Ping; Zhou, Feng; Xu, Xiang-lai; Li, Shi-qi; Cai, Song-liang; Wang, Yi-min

2014-01-01

280

Stability of the noncircular screw pinch  

NASA Astrophysics Data System (ADS)

The magnetohydrodynamic stability of a slightly noncircular screw pinch with arbitrary cross-sectional shape is investigated analytically and numerically using two models: the surface-current model and the force-free model. For the surface-current model the noncircular correction to the instability growth rate is given in analytical form: (1) for the case nq is about or equal to m, where q is the safety factor and m and n are the azimuthal and longitudinal mode numbers of the instability, and (2) for the special case of purely transverse perturbations (n = 0). For the force-free model, the noncircular correction to the marginal stability condition is obtained. This is done analytically for nq is about or equal to m, and for fixed boundary internal modes.

Miller, G.

1980-11-01

281

Screw Compressor Characteristics for Helium Refrigeration Systems  

NASA Astrophysics Data System (ADS)

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 mechanisms, as well as to implement practical solutions.

Ganni, V.; Knudsen, P.; Creel, J.; Arenius, D.; Casagrande, F.; Howell, M.

2008-03-01

282

Spline-locking screw fastening strategy  

NASA Technical Reports Server (NTRS)

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.

Vranish, John M.

1992-01-01

283

Spline-Locking Screw Fastening Strategy (SLSFS)  

NASA Technical Reports Server (NTRS)

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.

Vranish, John M.

1991-01-01

284

External fixation of femoral defects in athymic rats: Applications for human stem cell implantation and bone regeneration  

PubMed Central

An appropriate animal model is critical for the research of stem/progenitor cell therapy and tissue engineering for bone regeneration in vivo. This study reports the design of an external fixator and its application to critical-sized femoral defects in athymic rats. The external fixator consists of clamps and screws that are readily available from hardware stores as well as Kirschner wires. A total of 35 rats underwent application of the external fixator with creation of a 6-mm bone defect in one femur of each animal. This model had been used in several separate studies, including implantation of collagen gel, umbilical cord blood mesenchymal stem cells, endothelial progenitor cells, or bone morphogenetic protein-2. One rat developed fracture at the proximal pin site and two rats developed deep tissue infection. Pin loosening was found in nine rats, but it only led to the failure of external fixation in two animals. In 8 to 10 weeks, various degrees of bone growth in the femoral defects were observed in different study groups, from full repair of the bone defect with bone morphogenetic protein-2 implantation to fibrous nonunion with collagen gel implantation. The external fixator used in these studies provided sufficient mechanical stability to the bone defects and had a comparable complication rate in athymic rats as in immunocompetent rats. The external fixator does not interfere with the natural environment of a bone defect. This model is particularly valuable for investigation of osteogenesis of human stem/progenitor cells in vivo. PMID:23593535

Foo, Terasa; Reagan, Jeffrey; Watson, John T; Moed, Berton R

2013-01-01

285

Long-Term Follow-Up of Iliac Wallstents  

SciTech Connect

We evaluated the long-term results of the iliac artery stent placement for the treatment of patients with intermittent claudication. From November 1988 to December 1998, 303 legs were treated with metal stents in 259 patients with iliac occlusive arterial disease in a follow-up study approved by the institutional review board. Stenoses (n = 162) were treated after failed angioplasty and occlusions (n = 141) were treated with primary stent placement. According to Fontaine's clinical classification of chronic ischemia, 266 (88%) legs presented stage IIB, 14 (5%) stage III, and 23 (7%) stage IV. In all legs, self-expandable stents (Wallstent) were implanted. The patients were followed up with clinical examination, ankle brachial- index examination measurement and intravenous angiography. The data were analyzed using the univariate analysis (Kaplan-Meier method) and multivariate analysis (Cox proportional model). The primary endpoint of the study was the identification of restenosis or reoclusion of the stenting arterial segment and a secondary endpoint that was an identification of the risk factors of restenosis and reoclusion. The mean {+-} SD ankle-brachial index pre-, post-procedure, and in the last control was 0.58 {+-} 0.18, 0.90 {+-} 0.23, and 0.86 {+-} 0.24, respectively. Primary cumulative patency rates were 70% {+-} 4 after 5 years, and 65% {+-} 5 after 7 years, and secondary patency rates were 92% {+-} 2 after 5 years, and 87% {+-} 4 after 9 years. Immediate complications in the first 24 hours appeared in 12 (4%) legs, thrombosis in 5 legs, 3 legs presented with distal embolism, 2 thrombi at the access site and pseudo aneurysm and artery rupture in 1 leg. A patient died in the first 24 hours. Within 30 days after the procedure seven complications, 3 thromboses and 4 stenosis appeared. During follow-up, 42 (16%) patients died of other causes. The main causes of death were cardiac disease (39%), cerebrovascular disease (15%), cancer (7%), respiratory diseases (4%), and death due to accidents (2%), and other causes (9%). In 24% of the cases there was insufficient information to assign a principal cause of death. Thirty-six patients (13%) were lost to follow-up. Complications arose in 54 (18%) legs due to occlusion of the treated segment (29%), and stenosis due to intimal hyperplasia (27%). Thirteen patients required surgical treatment. Primary and secondary patency mean time was 80 {+-} 3.7 and 102 {+-} 2.4 months, respectively. We found no significant relation between patency and the quality of run-off, but a small vessel diameter and the female gender were negative predictive factors for failure (proportional hazards model). The use of stents for treatment of iliac artery occlusive disease may be considered an effective method with a low complication rate and acceptable long-term follow-up results.

Reyes, Ricardo [Hospital Dr. Negrin, Vascular and Interventional Radiology Unit (Spain); Carreira, Jose Martin [Universidad de, Dept of Radiology (Spain)], E-mail: mrjoseca@usc.es; Gude, Francisco [Hospital Clinico Universitario de Santiago, Clinical Epidemiology Unit (Spain); Gorriz, Elias; Gallardo, Laura; Pardo, Maria Dolores; Hermida, Maria [Hospital Dr. Negrin, Vascular and Interventional Radiology Unit (Spain)

2004-11-15

286

A retrospective study of iliac crest bone grafting techniques with allograft reconstruction: do patients even know which iliac crest was harvested?  

PubMed

Object Considerable biological research has been performed to aid bone healing in conjunction with lumbar fusion surgery. Iliac crest autograft is often considered the gold standard because it has the vital properties of being osteoconductive, osteoinductive, and osteogenic. However, graft site pain has been widely reported as the most common donor site morbidity. Autograft site pain has led many companies to develop an abundance of bone graft extenders, which have limited proof of efficacy. During the surgical consent process, many patients ask surgeons to avoid harvesting autograft because of the reported pain complications. The authors sought to study postoperative graft site pain by simply asking patients whether they knew which iliac crest was grafted when a single skin incision was made for the fusion operation. Methods Twenty-five patients underwent iliac crest autografting with allograft reconstruction during instrumented lumbar fusion surgery. In all patients the autograft was harvested through the same skin incision but with a separate fascial incision. At various points postoperatively, the patients were asked if they could tell which iliac crest had been harvested, and if so, how much pain did it cause (10-point Numeric Rating Scale). Results Most patients (64%) could not correctly determine which iliac crest had been harvested. Of the 9 patients who correctly identified the side of the autograft, 7 were only able to guess. The 2 patients who confidently identified the side of grafting had no pain at rest and mild pain with activity. One patient who incorrectly guessed the side of autografting did have significant sacroiliac joint degenerative pain bilaterally. Conclusions Results of this study indicate the inability of patients to clearly define their graft site after iliac crest autograft harvest with allograft reconstruction of the bony defect unless they have a separate skin incision. This simple, easily reproducible pilot study can be expanded into a larger, multiinstitutional investigation to provide more definitive answers regarding the ideal, safe, and cost-effective bone graft material to be used in spinal fusions. PMID:25014500

Pirris, Stephen M; Nottmeier, Eric W; Kimes, Sherri; O'Brien, Michael; Rahmathulla, Gazanfar

2014-10-01

287

Complex Common and Internal Iliac or Aortoiliac Aneurysms and Current Approach: Individualised Open-Endovascular or Combined Procedures  

PubMed Central

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

Kotsis, Thomas; Louizos, Louizos Alexander; Theodoraki, Kassiani

2014-01-01

288

Fracture mechanisms of retrieved titanium screw thread in dental implant.  

PubMed

Titanium and its alloy are increasingly attracting attention for use as biomaterials. However, delayed fracture of titanium dental implants has been reported, and factors affecting the acceleration of corrosion and fatigue have to be determined. The fractured surface of a retrieved titanium screw and metallurgical structures of a dental implant system were analyzed. The outer surface of the retrieved screw had a structure different from that of the as-received screw. It was confirmed that a shear crack initiated at the root of the thread and propagated into the inner section of the screw. Gas chromatography revealed that the retrieved screw had absorbed a higher amount of hydrogen than the as-received sample. The grain structure of a titanium screw, immersed in a solution known to induce hydrogen absorption, showed features similar to those of the retrieved screw. It was concluded that titanium in a biological environment absorbs hydrogen and this may be the reason for delayed fracture of a titanium implant. PMID:12033593

Yokoyama, Ken'ichi; Ichikawa, Tetsuo; Murakami, Hiroki; Miyamoto, Youji; Asaoka, Kenzo

2002-06-01

289

New device to treat chronic subdural hematoma--hollow screw.  

PubMed

Different surgical approaches exist for the treatment of chronic subdural hematoma. None of these approaches is superior to the other, so a minimal-invasive device (a hollow screw) was developed. The system consists of a stable hollow screw of surgical steel with a perforated tip, a hand-drill, screwdriver with guide, and collection bag. To place the screw in the skull local anesthesia is necessary followed by stab incision and percutaneous trephination. The screw is then placed in the bone and the guide removed. After spontaneous drainage and irrigation, a closed drainage system with a collection bag is connected with the screw. First results with the new technology are promising, with a high rate of completely treated patients and a low rate of complications. Two of 86 patients had a local skin infection after implantation of the screw, and in 22 patients the procedure was repeated due to one or more cases of recurrent or residual hematoma. No neurological deterioration was caused by the screw or the surgical approach. The advantages of this new system are: quick and simple procedure, minimal invasive, excellent function, inexpensive and reusable. PMID:10048060

Emonds, N; Hassler, W E

1999-01-01

290

A biomechanical analysis of atlantoaxial stabilization methods using a bovine model. C1/C2 fixation analysis.  

PubMed

The reliability and initial postoperative stability of six widely used C1-C2 surgical constructs were evaluated by nondestructive biomechanical testing of ten fresh bovine upper cervical spine segments. The six fixation techniques were the simple midline sublaminar C1 wiring (SMW), the modified Gallie wiring (MGW), the Brook wedge arthrodesis (BWA), the bilateral lateral mass screw (LMS), and the Clark arthrodesis without (CWO) and with (CW) the adjunctive use of polymethylmethacrylate (PMMA) cement. Instability was produced by resection of the base of the dens. Intact, destabilized, and instrumented constructs were tested in unconstrained flexion, extension, torsion, anterior, and posterior shear forces. The LMS and CW techniques proved the most effective in achieving C1-C2 stability. Sublaminar C2 wiring methods tended to have greater torsional and shear stiffness. Less rigid fixation techniques frequently loosened. All non-PMMA-enhanced wired constructs failed to restore the ability to adequately resist the posterior translation of C1 on C2. Stabilization of an unstable atlantoaxial articulation is best accomplished by a lateral mass screw or sublaminar C1-C2 PMMA-enhanced technique. Other techniques provided less consistent and reliable surgical fixation. Because of the inadequacy of wired constructs to resist posterior shear in patients with this instability pattern, the usual treatment may need to be modified to include more prolonged or protective external immobilization or more rigid fixation techniques. Although less rigid, the SMW and the MGW techniques are safer because they require less-frequent passage of sublaminar wires, avoid potential problems with PMMA, and obviate the hazards of further lateral dissection and insertion of the transarticular screws. PMID:8472462

Smith, M D; Kotzar, G; Yoo, J; Bohlman, H

1993-05-01

291

Intersection of screw dislocations in fcc crystals during torsional deformation  

NASA Astrophysics Data System (ADS)

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.

Myshlyaev, M. M.

2012-03-01

292

Noninvasive method for retrieval of broken dental implant abutment screw  

PubMed Central

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

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

2014-01-01

293

The influence of a suction device on fixation of a cemented cup using RSA.  

PubMed

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

Timperley, A John; Whitehouse, Sarah L; Hourigan, Patrick G

2009-03-01

294

S rod fixation to the sacrum in patients with neuromuscular spinal deformities.  

PubMed

A new form of pelvic fixation has been designed for use in patients with neuromuscular spinal deformities to overcome the problems imposed by the Galveston technique. One end of a Luque rod is prebent into an S shaped configuration and placed over the sacral ala supplying firm fixation across the lumbosacral junction without crossing the sacroiliac joint. It fixes firmly against the sacral ala by distracting against a hook or screw in the lumbar spine. A 12 year retrospective review of 67 patients with severe neuromuscular spinal deformities was accomplished. All surgeries were performed by one surgeon. All patients had good deformity correction with an average followup of 6 years and 2 months. Complications included: recurrence of pelvic obliquity (one patient), skin break-down over hardware (one patient), migration of hardware at sacrum (two patients), and rod breakage (five patients). The S rod is recommended for all patients with neuromuscular spinal deformities who require instrument fixation to the pelvis. Its ease of insertion and decreased operative time allow for a safe and dependable alternative fixation to the sacrum without crossing the sacroiliac joint. PMID:10416388

McCarthy, R E; Bruffett, W L; McCullough, F L

1999-07-01

295

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

296

A rare three part proximal ulnar shear fracture requiring innovative reduction and fixation in a paediatric elbow  

PubMed Central

Fracture of the proximal ulna in children is an uncommon injury with various classification models. An 8-year-old boy presented to our emergency department with an isolated three part intra-articular fracture of his right proximal ulna from an extension injury sustained during skiing which has not been previously described in the literature. He was taken to the operating room for open reduction and internal fixation. Two cannulated screws positioned in a posterior–anterior direction were used to hold the reduction. He was discharged from the hospital 24 h post-reduction in a complete cast. At 5 weeks follow-up, his elbow radiographs indicate no loss of reduction and at 4 months follow-up, he has regained a full range of movement at the elbow joint. The cannulated screws were left in situ as it did not cause him any harm. We propose that the described fracture pattern should be managed by open reduction and internal fixation (cannulated screws used to hold the reduction, position in a posterior–anterior direction). PMID:24876402

Lee, S.W.J.; Murray, O.; Duncan, R.

2014-01-01

297

Screw dislocation driven growth of nanomaterials.  

PubMed

Nanoscience and nanotechnology impact our lives in many ways, from electronic and photonic devices to biosensors. They also hold the promise of tackling the renewable energy challenges facing us. However, one limiting scientific challenge is the effective and efficient bottom-up synthesis of nanomaterials. We can approach this core challenge in nanoscience and nanotechnology from two perspectives: (a) how to controllably grow high-quality nanomaterials with desired dimensions, morphologies, and material compositions and (b) how to produce them in a large quantity at reasonable cost. Because many chemical and physical properties of nanomaterials are size- and shape-dependent, rational syntheses of nanomaterials to achieve desirable dimensionalities and morphologies are essential to exploit their utilities. In this Account, we show that the dislocation-driven growth mechanism, where screw dislocation defects provide self-perpetuating growth steps to enable the anisotropic growth of various nanomaterials at low supersaturation, can be a powerful and versatile synthetic method for a wide variety of nanomaterials. Despite significant progress in the last two decades, nanomaterial synthesis has often remained an "art", and except for a few well-studied model systems, the growth mechanisms of many anisotropic nanostructures remain poorly understood. We strive to go beyond the empirical science ("cook-and-look") and adopt a fundamental and mechanistic perspective to the anisotropic growth of nanomaterials by first understanding the kinetics of the crystal growth process. Since most functional nanomaterials are in single-crystal form, insights from the classical crystal growth theories are crucial. We pay attention to how screw dislocations impact the growth kinetics along different crystallographic directions and how the strain energy of defected crystals influences their equilibrium shapes. Furthermore, such inquiries are supported by detailed structural investigation to identify the evidence of dislocations. The dislocation-driven growth mechanism not only can unify the various explanations behind a wide variety of exotic nanoscale morphologies but also allows the rational design of catalyst-free solution-phase syntheses that could enable the scalable and low cost production of nanomaterials necessary for large scale applications, such as solar and thermoelectric energy conversions, energy storage, and nanocomposites. In this Account, we discuss the fundamental theories of the screw dislocation driven growth of various nanostructures including one-dimensional nanowires and nanotubes, two-dimensional nanoplates, and three-dimensional hierarchical tree-like nanostructures. We then introduce the transmission electron microscopy (TEM) techniques to structurally characterize the dislocation-driven nanomaterials for future searching and identifying purposes. We summarize the guidelines for rationally designing the dislocation-driven growth and discuss specific examples to illustrate how to implement the guidelines. By highlighting our recent discoveries in the last five years, we show that dislocation growth is a general and versatile mechanism that can be used to grow a variety of nanomaterials via distinct reaction chemistry and synthetic methods. These discoveries are complemented by selected examples of anisotropic crystal growth from other researchers. The fundamental investigation and development of dislocation-driven growth of nanomaterials will create a new dimension to the rational design and synthesis of increasingly complex nanomaterials. PMID:23738750

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

2013-07-16

298

Supra-acetabular placement of external fixator pins: a safe and expedient method of providing the injured pelvis with stability.  

PubMed

Applying a stable anterior pelvic external fixator frame is a skill that should be mastered by all orthopedic surgeons who treat acutely injured patients. Splinting of an unstable pelvis during resuscitation can help to reduce the volume of the true pelvis, pending definitive surgical stabilization of the pelvic ring. Supra-acetabular pin placement, less familiar to most surgeons than iliac wing pin placement is, can provide a more reliable pin-bone interface and thus allow improved reduction ability with fewer soft-tissue complications. Because of their location, supra-acetabular pins also seem to be better tolerated than iliac crest pins when used for definitive management of the pelvic ring disruption. A young man who sustained a type II anteroposterior compression injury in a motor vehicle accident presented with symphyseal disruption (7 cm wide) and left anterior sacroiliac joint disruption. During resuscitation, the pelvis was anatomically reduced and stabilized with a supra-acetabular pin-based external fixator. Pin locations, chosen using palpable and cutaneous landmarks, were inserted without additional imaging guidance. The fracture was reduced anatomically, and the frame was used for definitive management of the pelvic ring injury. PMID:15828520

Poelstra, Kornelis A; Kahler, David M

2005-03-01

299

Hinged external fixation of the elbow.  

PubMed

Hinged external fixation of the elbow provides the advantages of static fixation with the benefits of continued motion through the joint. Indications for the use of this method of fixation include traumatic instability, distraction interposition arthroplasty, instability after contracture release, and instability after excision of heterotopic ossification. Orthopedic surgeons should be familiar with hinged fixators and their application when faced with an unstable ulnohumeral joint. PMID:20670807

Chen, Neal C; Julka, Abhishek

2010-08-01

300

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

301

Options for acetabular fixation surfaces.  

PubMed

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

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

2007-01-01

302

Understanding Nitrogen Fixation  

SciTech Connect

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

Paul J. Chirik

2012-05-25

303

Osmolarity of osmium tetroxide and glutaraldehyde fixatives  

Microsoft Academic Search

Synopsis  The evidence available to date for the importance of fixative osmolarity is considered together with some observations on the volume changes of crab axons after fixation by osmium tetroxide and glutaraldehyde. The results obtained are compared with those obtained from crab axons and from amphioxus skin cells which had been processed and examined with the electron microscope after initial fixation

Q. Bone; K. P. Ryan

1972-01-01

304

Arthroscopic Posterior Bone Block Procedure: A New Technique Using Suture Anchor Fixation  

PubMed Central

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

Boileau, Pascal; Hardy, Marie-Beatrice; McClelland, Walter B.; Thelu, Charles-Edouard; Schwartz, Daniel G.

2013-01-01

305

Screw Type Steam Compressors for Mechanical Vapor Recompression (MVR) Systems  

E-print Network

SCREW TYPE STEAM COMPRESSORS FOR MECHANICAL VAPOR RECOMPRESSION (MVR) SYSTEMS K. KAWAMURA AND THOMAS-L. APALOO MYCOM CORPORATION, LOS ANGELES, CALIFORNIA MATSUDA, MAYEKAWA MFG. CO., TOKYO, JAPAN ABSTRACT In processes of evaporation...SCREW TYPE STEAM COMPRESSORS FOR MECHANICAL VAPOR RECOMPRESSION (MVR) SYSTEMS K. KAWAMURA AND THOMAS-L. APALOO MYCOM CORPORATION, LOS ANGELES, CALIFORNIA MATSUDA, MAYEKAWA MFG. CO., TOKYO, JAPAN ABSTRACT In processes of evaporation...

Kawamura, K.; Apaloo, Thomas-L.

306

Segmental pedicle screw instrumentation in idiopathic thoracolumbar and lumbar scoliosis  

Microsoft Academic Search

The role of posterior correction and fusion in thoracolumbar and lumbar scoliosis as well as pedicle screw instrumentation\\u000a in scoliosis surgery are matters of debate. Our hypothesis was that in lumbar and thoracolumbar scoliosis, segmental pedicle\\u000a screw instrumentation is safe and enables a good frontal and sagittal plane correction with a fusion length comparable to\\u000a anterior instrumentation. In a prospective

H. Halm; T. Niemeyer; T. Link; U. Liljenqvist

2000-01-01

307

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

PubMed Central

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

Howat, William J.; Wilson, Beverley A.

2014-01-01

308

Post-operative internal hernia through an orifice underneath the right common iliac artery after Dargent's operation.  

PubMed

We report the case of a 39-year-old woman with ileus resulting from a small bowel incarceration underneath the right common iliac artery. The patient had a history of a radical trachelectomy with laparoscopic pelvic lymphadenectomy ("Dargent's operation") for cervical carcinoma. After dissection of the iliac vessels, a small bowel loop could slide underneath the common iliac artery. The hernia was closed by gluing a collagen patch over the right common iliac artery onto the retroperitoneal cavity. To our knowledge, such a case has not previously been reported in the medical literature. PMID:23793860

Ardelt, M; Dittmar, Y; Scheuerlein, H; Bärthel, E; Settmacher, U

2014-12-01

309

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

SciTech Connect

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

Fretz, V.; Binkert, C. A., E-mail: Christoph.Binkert@ksw.c [Kantonsspital Winterthur, Department of Radiology (Switzerland)

2010-10-15

310

Helical Screw Expander Evaluation Project. Final report  

SciTech Connect

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.

McKay, R.

1982-03-01

311

An analytical investigation of high-temperature heat pump system with screw compressor and screw expander for power recovery  

Microsoft Academic Search

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

I. Tamura; H. Taniguchi; H. Sasaki; R. Yoshida; I. Sekiguchi; M. Yokogawa

1997-01-01

312

SCAI expert consensus statement for aorto-iliac arterial intervention appropriate use.  

PubMed

Aorto-iliac arterial occlusive disease is common and may cause a spectrum of chronic symptoms from intermittent claudication to critical limb ischemia. Treatment is indicated for symptoms that have failed lifestyle and medical therapies or occasionally to facilitate other interventional procedures such as TAVR and/or placement of hemodynamic assist devices. It is widely accepted that TASC A, B, and C lesions are best managed with endovascular intervention. In experienced hands, most TASC D lesions may be treated by endovascular methods, and with the development of chronic total occlusion devices, many aorto-iliac occlusions may be recanalized safely by endovascular means. Interventional cardiologists should be well versed in the anatomy, as well as the treatment of aorto-iliac disease, given their need to traverse these vessels during transfemoral procedures. Overall, aorto-iliac occlusive disease is more commonly being treated with an endovascular-first approach, using open surgery as a secondary option. This document was developed to guide physicians in the clinical decision-making related to the contemporary application of endovascular intervention among patients with aorto-iliac arterial disease. © 2014 Wiley Periodicals, Inc. PMID:24740523

Klein, Andrew J; Feldman, Dmitriy N; Aronow, Herbert D; Gray, Bruce H; Gupta, Kamal; Gigliotti, Osvaldo S; Jaff, Michael R; Bersin, Robert M; White, Christopher J

2014-10-01

313

A case of gross haematuria due to an ureteric-iliac artery fistula.  

PubMed

A case of gross haematuria due to an ureteric-iliac artery fistula We report a case of a 75-year-old man presented with gross haematuria and left hydronephrosis due to an ureteric iliac- artery fistula . Medical history included a previous positioning of aorto-bisiliac graft and an iliac artery stent placed to exclude an hypogastric aneurysm. A retrograde pyelography revealed a compression of the middle ureter and an extravasation of contrast at that level, for this reason a double J stent was inserted. Contrast-enhanced computed tomography showed the presence of a fistula between the left ureter and the internal iliac. The patient underwent endovascular treatment using a stent-graft with the subsequent patient's recovery. Ureteric iliac-artery fistula is a rare condition and it generally manifests with life threatening gross bleeding. We suggest a multidisciplinary clinical approach in order to achieve the best results for the patient and to avoid severe complications. Endovascular techniques have been demonstrated to be effective and rapid in the treatment of this emergency condition; ureteral stenting is also recommended. PMID:24395028

Madonia, Massimo; Russo, Giorgio Ivan; Trignano, Emilio; Paliogiannis, Panagiotis; Cimino, Sebastiano; Corbu, Carlo; Morgia, Giuseppe

2013-12-01

314

Outcome of double bundle anterior cruciate ligament reconstruction using crosspin and aperture fixation  

PubMed Central

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

Joshi, Deepak; Jain, Vineet; Goyal, Ankit; Bahl, Vibhu; Modi, Prashant; Chaudhary, Deepak

2014-01-01

315

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

NASA Astrophysics Data System (ADS)

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

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

316

Quality Improvement Guidelines for Endovascular Treatment of Iliac Artery Occlusive Disease  

SciTech Connect

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.

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

317

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

SciTech Connect

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.

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

318

Early Palma procedure after iliac vein injury in abdominal penetrating trauma.  

PubMed

Ligation for penetrating abdominal vein trauma may have better outcome than a vascular reconstruction in an unstable patient. However, symptoms of chronic venous insufficiency may appear over time. We describe our surgical experience with 4 patients who underwent iliac vein ligation followed by venous bypass with a modified Palma derivation between 48 and 240 hours after sustaining penetrating abdominal trauma with concomitant iliac vein injury. Patients were assessed for venous symptoms and conduit patency with continuous wave Doppler and duplex scanning. One graft occluded acutely and the remaining three remain patent with functioning valves. In order to preserve venous outflow after severe iliac vein injury, we think that venous ligation as a part of damage control surgery followed by a modified Palma operation may prevent chronic symptoms of venous outflow obstruction without compromising an already injured patient. PMID:18727974

Alcocer, Francisco; Aguilar, Jesus; Agraz, Salvador; Jordan, William D

2008-09-01

319

Technique, Complication, and Long-Term Outcome for Endovascular Treatment of Iliac Artery Occlusion  

SciTech Connect

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.

Ozkan, Ugur, E-mail: radugur@yahoo.com; Oguzkurt, Levent; Tercan, Fahri [Baskent University, Department of Radiology, Faculty of Medicine (Turkey)

2010-02-15

320

Tibial slope and patellar height after opening wedge high tibia osteotomy using autologous tricortical iliac bone graft  

Microsoft Academic Search

Our aim was to evaluate the alteration in angle of posterior slope of the tibia and the degree of patellar height following medial opening wedge high tibia osteotomy(HTO) using autologous tricortical iliac bone graft in 32 consecutive patients.Twenty three females and nine males underwent medial opening wedge high tibia osteotomy (HTO) using autologous tricortical iliac bone graft in 34 knees

Dong Ju Chae; Gautam M. Shetty; Dong Bong Lee; Hyun Woo Choi; Seung Beom Han; Kyung Wook Nha

2008-01-01

321

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

SciTech Connect

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.

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

322

Impotence due to External Iliac Steal Syndrome: Treatment with Percutaneous Transluminal Angioplasty and Stent Placement  

PubMed Central

We report a case of erectile dysfunction caused by external iliac artery occlusion, associated with pelvic steal syndrome; bilateral internal iliac arteries were patent. The patient stated that he had experienced erectile dysfunction at similar times along with claudication, but he did not mention it before angiography. He expressed that the erectile dysfunction did not last long and that he felt completely okay after the interventional procedure, in addition to his claudication. Successful treatment of the occlusion, by percutaneous transluminal angioplasty and stent implantation, helped resolve erectile dysfunction completely and treat the steal syndrome. PMID:23323034

Oguzkurt, Levent; Kaya, Bilal; Tekbas, Guven; Ozkan, Ugur

2013-01-01

323

Impotence due to external iliac steal syndrome: treatment with percutaneous transluminal angioplasty and stent placement.  

PubMed

We report a case of erectile dysfunction caused by external iliac artery occlusion, associated with pelvic steal syndrome; bilateral internal iliac arteries were patent. The patient stated that he had experienced erectile dysfunction at similar times along with claudication, but he did not mention it before angiography. He expressed that the erectile dysfunction did not last long and that he felt completely okay after the interventional procedure, in addition to his claudication. Successful treatment of the occlusion, by percutaneous transluminal angioplasty and stent implantation, helped resolve erectile dysfunction completely and treat the steal syndrome. PMID:23323034

Gür, Serkan; Oguzkurt, Levent; Kaya, Bilal; Tekbas, Güven; Ozkan, Ugur

2013-01-01

324

Endovascular iliac rescue technique for complete arterial avulsion after transcatheter aortic valve replacement.  

PubMed

Transcatheter aortic valve replacement (TAVR) has emerged as an alternative therapy to open aortic valve repair for high-risk patients with aortic stenosis, but larger delivery sheath size is associated with vascular complications. We report 2 cases in which a minimally invasive technique was used for the hybrid repair of confirmed or suspected large-bore sheath traumatic avulsion (i.e., "iliac on a stick") after TAVR. We believe our hybrid approach to rescuing the iliac artery in suspected or confirmed complete artery avulsion could improve outcomes for patients who require TAVR. PMID:23901016

Obon-Dent, Mauricio; Reul, Ross M; Mortazavi, Ali

2014-08-01

325

Endovascular aortic injury repair after thoracic pedicle screw placement.  

PubMed

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

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

2014-09-01

326

Screw dislocations in GaN grown by different methods  

SciTech Connect

A study of screw dislocations in Hydride-Vapor-Phase-Epitaxy (HVPE) template and Molecular-Beam-Epitaxy (MBE) over-layers was performed using Transmission Electron Microscopy (TEM) in plan-view and in cross-section. It was observed that screw dislocations in the HVPE layers were decorated by small voids arranged along the screw axis. However, no voids were observed along screw dislocations in MBE overlayers. This was true both for MBE samples grown under Ga-lean and Ga-rich conditions. Dislocation core structures have been studied in these samples in the plan-view configuration. These experiments were supported by image simulation using the most recent models. A direct reconstruction of the phase and amplitude of the scattered electron wave from a focal series of high-resolution images was applied. It was shown that the core structures of screw dislocations in the studied materials were filled. The filed dislocation cores in an MBE samples were stoichiometric. However, in HVPE materials, single atomic columns show substantial differences in intensities and might indicate the possibility of higher Ga concentration in the core than in the matrix. A much lower intensity of the atomic column at the tip of the void was observed. This might suggest presence of lighter elements, such as oxygen, responsible for their formation.

Liliental-Weber, Z.; Zakharov, D.; Jasinski, J.; O'Keefe, M.A.; Morkoc, H.

2003-05-27

327

Ball screw preload loss detection using ball pass frequency  

NASA Astrophysics Data System (ADS)

A technique of determining the onset of preload loss in a ball screw feed drive system via monitoring the change of ball pass frequency is proposed. The ball pass frequency of a ball screw with preload is smaller than that of ball screw without preload due to friction caused by the preload. Results from both simulations and experiments show that the ball pass frequency can be detected using the method of Angular Velocity Vold-Kalman Filtering Order Tracking (AV VKF-OT). And AV VKF-OT provides a much better performance as compared to the traditional order tracking in terms of resolution and accuracy. Tests were conducted on ball screw feed drive systems with different preloads for the performance assessment of the ball pass frequency detection. Results show that the preload loss increases the ball pass frequency and also induces the side band around the ball pass frequency, which provides promising criteria in detecting the onset of preload loss of ball screws.

Tsai, P. C.; Cheng, C. C.; Hwang, Y. C.

2014-10-01

328

Comparative study on stress distribution around internal tapered connection implants according to fit of cement- and screw-retained prostheses  

PubMed Central

PURPOSE The aim of this study was to compare the passivity of implant superstructures by assessing the strain development around the internal tapered connection implants with strain gauges. MATERIALS AND METHODS A polyurethane resin block in which two implants were embedded served as a measurement model. Two groups of implant restorations utilized cement-retained design and internal surface of the first group was adjusted until premature contact between the restoration and the abutment completely disappeared. In the second group, only nodules detectable to the naked eye were removed. The third group employed screw-retained design and specimens were generated by computer-aided design/computer-aided manufacturing system (n=10). Four strain gauges were fixed on the measurement model mesially and distally to the implants. The strains developed in each strain gauge were recorded during fixation of specimens. To compare the difference among groups, repeated measures 2-factor analysis was performed at a level of significance of ?=.05. RESULTS The absolute strain values were measured to analyze the magnitude of strain. The mean absolute strain value ranged from 29.53 to 412.94 µm/m at the different strain gauge locations. According to the result of overall comparison, the cement-retained prosthesis groups exhibited significant difference. No significant difference was detected between milled screw-retained prostheses group and cement-retained prosthesis groups. CONCLUSION Within the limitations of the study, it was concluded that the cement-retained designs do not always exhibit lower levels of stress than screw-retained designs. The internal adjustment of a cement-retained implant restoration is essential to achieve passive fit. PMID:24049573

Lee, Mi-Young; Heo, Seong-Joo; Park, Eun-Jin

2013-01-01

329

FEM evaluation of cemented-retained versus screw-retained dental implant single-tooth crown prosthesis  

PubMed Central

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

Cicciu, Marco; Bramanti, Ennio; Matacena, Giada; Guglielmino, Eugenio; Risitano, Giacomo

2014-01-01

330

[Observations on before and after employ of screw of implant denture with SEM].  

PubMed

The loss of screw is one of the clinic complication in MDIC implant denture cases. The purpose of this study is to find the cause of loss of screw. The authors has studied MDIC implant denture with SEM before and after employ of the screw and found that the causes of screw loss were crevice corrosion and friction pressure. Crevice corrosion may promote the loss of screw. Base the above condition, it is necessary to select Ti-alloy screw and associat with anticorrosive measure in MDIC implant denture construction. PMID:10677963

Song, Y; Xu, J; Ma, X

1997-03-01

331

Mild coal gasification screw pyrolyzer development and design  

SciTech Connect

Our objective is to produce information and design recommendations needed for the development of an efficient continuous process for the mild gasification of caking bituminous coals. We have focused on the development of an externally heated pyrolyzer in which the sticky, reacting coal is conveyed by one or more screws. We have taken a multifaceted approach to forwarding the development of the externally-heated screw pyrolyzer. Small scale process experiments on a 38-mm single screw pyrolyzer have been a major part of our effort. Engineering analyses aimed at producing design and scaleup equations have also been important. Process design recommendations follow from these. We critically review our experimental data and experience, and information from the literature and equipment manufactures for the purpose of making qualitative recommendations for improving practical pyrolyzer design and operation. Benchscale experiments are used to supply needed data and test some preliminary concepts. 6 refs., 4 figs., 1 tab.

Camp, D.W.

1990-08-01

332

[Dental reconstruction with non-precious metal screws and posts].  

PubMed

A short review of the current methods for restoring destroyed dental crowns by mechanical retentive elements. The causes leading to failure in such restorations are mentioned in a short review of literature. Main causes are corrosive changes in posts and screws anchored in root canals. This is why a special chapter deals with the problem of corrosion. A systematic enumeration of various corrosions in posts and screws is illustrated by a choice of clinical and radiological illustrations. The author's own metallurgical analytic investigations of the posts and screws available commercially allow to divide them into 4 typical nonprecious metal groups: Inox steel, cromium nickel steel, cromium nickel molybdene steel and brass alloys. The reasons for resistance to corrosion lie in the different metallographic structures and processing methods. Further investigations are finished and will be published later in this journal. PMID:392757

Wirz, J; Johner, M; Pohler, O

1979-11-01

333

Arthroscopic coracoclavicular ligament reconstruction using biologic and suture fixation.  

PubMed

Presented in this report is a modified arthroscopic approach to acromioclavicular joint reconstruction via suture and allograft fixation. An arthroscopic approach is used to expose the base of the coracoid by use of electrocautery. After an open distal clavicle excision is performed, clavicular and coracoid tunnels are created under arthroscopic visualization as previously described by Wolf and Pennington. The myotendinous end of a semitendinosus allograft is sutured to a Spider plate (Kinetikos Medical, San Diego, CA). The tendinous end of the graft is prepared with a running baseball stitch. A Nitinol wire with a loop end (Arthrex, Naples, FL) is used to pass 2 free FiberTape sutures (Arthrex) and the leading sutures from the tendinous end of the graft through the clavicular and coracoid tunnels, exiting out the anterior portal. One of the FiberTape sutures is retrieved with a grasper and passed over the anterior aspect of the distal clavicle. The second FiberTape suture and the allograft are passed over the distal end of the resected clavicle. While the acromioclavicular joint is held reduced, the FiberTape sutures are tied to the plate and the allograft is tensioned medially until the plate is embedded against the superior surface of the clavicle. The tendinous end of the graft is secured to the superior surface of the clavicle with a Bio-tenodesis screw (Arthrex) medial to the clavicular tunnel. PMID:17637416

Pennington, William T; Hergan, David J; Bartz, Brian A

2007-07-01

334

Fixational eye movements and binocular vision  

PubMed Central

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

Otero-Millan, Jorge; Macknik, Stephen L.; Martinez-Conde, Susana

2014-01-01

335

Revascularização de artéria ilíaca interna para tratamento de isquemia crítica de membro inferior Revascularization of the internal iliac artery for critical lower limb ischemia treatment  

Microsoft Academic Search

Patients with aortoiliac occlusive disease and critical lower limb ischemia depend on large collateral circulation to maintain limb viability, in which the internal iliac artery plays a fundamental role. We present a case report of critical left lower limb ischemia treatment in a patient with ostial occlusion of the ipsilateral common iliac artery and refilling of internal iliac artery, deep

Hugsmaer Pelicioni Filho; Marcus Ageu; Ribeiro Batista; George Carchedi Luccas

336

SEM and fractography analysis of screw thread loosening in dental implants.  

PubMed

Biological and technical failures of implants have already been reported. Mechanical factors are certainly of importance in implant failures, even if their exact nature has not yet been established. The abutment screw fracture or loosening represents a rare, but quite unpleasant failure. The aim of the present research is an analysis and structural examination of screw thread or abutment loosening compared with screw threads or abutment without loosening. The loosening of screw threads was compared to screw thread without loosening of three different implant systems; Branemark (Nobel Biocare, Gothenburg, Sweden), T.B.R. implant systems (Benax, Ancona, Italy) and Restore (Lifecore Biomedical, Chaska, Minnesota, USA). In this study broken screws were excluded. A total of 16 screw thread loosenings were observed (Group I) (4 Branemark, 4 T.B.R and 5 Restore), 10 screw threads without loosening were removed (Group II), and 6 screw threads as received by the manufacturer (unused) (Group III) were used as control (2 Branemark, 2 T.B.R and 2 Restore). The loosened abutment screws were retrieved and analyzed under SEM. Many alterations and deformations were present in concavities and convexities of screw threads in group I. No macroscopic alterations or deformations were observed in groups II and III. A statistical difference of the presence of microcracks were observed between screw threads with an abutment loosening and screw threads without an abutment loosening. PMID:17897496

Scarano, A; Quaranta, M; Traini, T; Piattelli, M; Piattelli, A

2007-01-01

337

Early postoperative failure of a new intramedullary fixation device for midshaft clavicle fractures.  

PubMed

The Sonoma CRx device (Sonoma Orthopedic Products, Santa Rosa, California) is a recently introduced intramedullary device with a flexible shaft that becomes rigid once actuated to allow deployment within the sigmoidal contour of the clavicular shaft. Medial intramedullary cortical purchase is obtained by grippers and lateral purchase through a locking bicortical buttressing screw. This article describes 2 cases of early hardware failure using this device. In both cases, early postoperative radiographs demonstrate adequate initial fracture reduction and implant position. Both patients sustained repeat injuries, one under low physiologic load and the other after returning to mixed martial arts 4 months postoperatively. Implant failure was noted after reinjury in both cases. Complete healing and full return to function was documented for both patients at 2 years. Proper patient selection and counseling regarding the limitations of this intramedullary fixation device are important. Biomechanical comparison of this implant to plate fixation under physiologic loads of combined axial compression and torsion may shed light on differences in fixation stability. PMID:24200452

Wilson, David J; Weaver, DeWayne L; Balog, Todd P; Arrington, Edward D

2013-11-01

338

Comparison of Functional Recovery in the Very Early Period After Surgery Between Plate and Nail Fixation for Correction of Stable Femoral Intertrochanteric Fractures  

PubMed Central

Purpose: This study aimed to compare the differences in functional recovery between patients undergoing plate and nail fixation in the very early period after surgery. Method: This study was designed as a controlled clinical trial that included 18 patients who were surgically treated with either dynamic hip screw as plate fixation or proximal femoral nail as nail fixation for stable intertrochanteric fractures. In particular, all patients selected for the study reported walking completely independently without the use of walking aids prior to sustaining their initial fracture. In all, 8 patients (mean age, 73.8 years; range, 65-89 years) were treated with plate fixation (group plate) and 10 patients (mean age, 79.7 years; range, 70-90 years) were treated with nail fixation (group nail). Functional evaluations were assessed every week after surgery using the Japanese Orthopaedic Association (JOA) hip functional scores and active range of motion (ROM) of the hip joint. Results: The recovery of activities of daily living (ADLs) according to JOA hip functional scores at week 4 after surgery was significantly better in group nail than in group plate (P = .03), whereas active ROM of hip flexion improved significantly in group plate than in group nail at weeks 3 and 4 after surgery (P = .04 and P = .02, respectively). Conclusions: The results suggested that nail fixation may provide a more rapid recovery of ADLs than that of plate fixation in the very early period after surgery. However, plate fixation may provide better ROM of hip flexion than that of nail fixation.

Fushimi, Kazunari; Shirai, Goshi; Fukuta, Masashi

2014-01-01

339

Long-term results of cemented and screwed acetabular components.  

PubMed

The authors report their experience in the use of various types of acetabular components (cemented and screwed) in 253 hip prostheses with "Biodirect" femoral component and ceramic femoral head. A long-term follow-up of 148 hip prostheses (58.5% of the total) was carried out, 36 Müller type polyethylene and 61 Biolox ceramic acetabular components, and 51 screwed sockets of various models were used. From a clinical and radiographical standpoint, the ceramic acetabular component proved the most valid in the short and medium term, confirming the favourable biomechanical conditions which derive from ceramic/ceramic coupling. PMID:8567260

Agrifoglio, E; Federici, A; Sanguineti, F; Maxena, S; Giacchè, P

1993-01-01

340

Virtual estimates of fastening strength for pedicle screw implantation procedures  

NASA Astrophysics Data System (ADS)

Traditional 2D images provide limited use for accurate planning of spine interventions, mainly due to the complex 3D anatomy of the spine and close proximity of nerve bundles and vascular structures that must be avoided during the procedure. Our previously developed clinician-friendly platform for spine surgery planning takes advantage of 3D pre-operative images, to enable oblique reformatting and 3D rendering of individual or multiple vertebrae, interactive templating, and placement of virtual pedicle implants. Here we extend the capabilities of the planning platform and demonstrate how the virtual templating approach not only assists with the selection of the optimal implant size and trajectory, but can also be augmented to provide surrogate estimates of the fastening strength of the implanted pedicle screws based on implant dimension and bone mineral density of the displaced bone substrate. According to the failure theories, each screw withstands a maximum holding power that is directly proportional to the screw diameter (D), the length of the in-bone segm,ent of the screw (L), and the density (i.e., bone mineral density) of the pedicle body. In this application, voxel intensity is used as a surrogate measure of the bone mineral density (BMD) of the pedicle body segment displaced by the screw. We conducted an initial assessment of the developed platform using retrospective pre- and post-operative clinical 3D CT data from four patients who underwent spine surgery, consisting of a total of 26 pedicle screws implanted in the lumbar spine. The Fastening Strength of the planned implants was directly assessed by estimating the intensity - area product across the pedicle volume displaced by the virtually implanted screw. For post-operative assessment, each vertebra was registered to its homologous counterpart in the pre-operative image using an intensity-based rigid registration followed by manual adjustment. Following registration, the Fastening Strength was computed for each displaced bone segment. According to our preliminary clinical study, a comparison between Fastening Strength, displaced bone volume and mean voxel intensity showed similar results (p < 0.1) between the virtually templated plans and the post-operative outcome following the traditional clinical approach. This study has demonstrated the feasibility of the platform in providing estimates the pedicle screw fastening strength via virtual implantation, given the intrinsic vertebral geometry and bone mineral density, enabling the selection of the optimal implant dimension adn trajectory for improved strength.

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

2014-03-01

341

Modeling fixation locations using spatial point processes.  

PubMed

Whenever eye movements are measured, a central part of the analysis has to do with where subjects fixate and why they fixated where they fixated. To a first approximation, a set of fixations can be viewed as a set of points in space; this implies that fixations are spatial data and that the analysis of fixation locations can be beneficially thought of as a spatial statistics problem. We argue that thinking of fixation locations as arising from point processes is a very fruitful framework for eye-movement data, helping turn qualitative questions into quantitative ones. We provide a tutorial introduction to some of the main ideas of the field of spatial statistics, focusing especially on spatial Poisson processes. We show how point processes help relate image properties to fixation locations. In particular we show how point processes naturally express the idea that image features' predictability for fixations may vary from one image to another. We review other methods of analysis used in the literature, show how they relate to point process theory, and argue that thinking in terms of point processes substantially extends the range of analyses that can be performed and clarify their interpretation. PMID:24084942

Barthelmé, Simon; Trukenbrod, Hans; Engbert, Ralf; Wichmann, Felix

2013-01-01

342

Image recorder with microwave fixation  

SciTech Connect

The present invention is directed to improvement in an image recorder for recording developed images or toner images by microwave fixation. According to the invention there is used a novel thermoplastic developer comprising of two components. The first component contains a dielectric material which is able to absorb microwave and generate heat by dielectric loss. The second component contains magnetic loss exothermic material. The microwave absorbing power of the first component is improved by heating the first component with heat generated from the second component.

Hosono, N.; Isaka, K.

1984-11-13

343

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

PubMed Central

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

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

2012-01-01

344

Directional Atherectomy in Iliac Stent Failure: Clinical Technique and Histopathologic Correlation  

SciTech Connect

Purpose: To assess the feasibility and efficacy of directional atherectomy in the treatment of iliac stent stenosis or occlusion and to evaluate the histologic composition of excised atherectomy specimens. Methods: Directional atherectomy of six occluded and 10 severely stenosed iliac stents was undertaken in 12 patients at a mean interval of 28 months (range 3-69 months) after stent insertion for occlusive aortoiliac disease. In cases of stent occlusion, atherectomy was preceded by low-dose thrombolysis. In all patients stent clearance with return of femoral pulses was achieved within 24 hr and there were no significant complications. All excised specimens were sent for histologic examination. Results: Eleven patients (92%) remain symptom free with unlimited walking distance at a mean follow-up interval of 11.5 months (range 3-31 months) after treatment. Histologic examination revealed typical myointimal hyperplasia at three excision sites, intimal fibrosis at three sites, atheroma at four sites and organized thrombus at six sites. Conclusion: Atherectomy offers an effective treatment in iliac stent occlusion and restenosis with no significant adverse effects. Debulking of these lesions seems to offer a more logical approach than simple balloon angioplasty. Clinical and duplex follow-up confirms satisfactory outcome within the first year but longer-term results are not yet known. The histologic data obtained demonstrate that stent restenosis and occlusion are likely to be multifactorial, and challenge the assumption that myointimal hyperplasia is the sole cause of iliac stent occlusion.

Ettles, Duncan F. [Department of Radiology, Hull Royal Infirmary, Anlaby Road, Hull HU3 2JZ, East Yorkshire (United Kingdom); MacDonald, Alastair W.; Burgess, Paul A. [Department of Pathology, Castlehill Hospital, Castle Road, Cottingham HU 16 5JQ, East Yorkshire (United Kingdom); Nicholson, Anthony A.; Dyet, John F. [Department of Radiology, Hull Royal Infirmary, Anlaby Road, Hull HU3 2JZ, East Yorkshire (United Kingdom)

1998-11-15

345

Endovascular Stent-Graft Placement as Emergency Treatment for Ruptured Iliac Pseudoaneurysm  

SciTech Connect

A 65-year-old woman with advanced mucinous carcinoma of the ovary presented with massive rectal bleeding caused by rupture of an iliac artery pseudoaneurysm into the bowel. Surgery was contraindicated due to the patient's poor clinical condition. We successfully placed an endovascular stent-graft that excluded the pseudoaneurysm. There were no complications, and the patient recovered well.

Aytekin, Cueneyt; Boyvat, Fatih; Yildirim, Erkan; Coskun, Mehmet [Department of Radiology, BakentUniversity Faculty of Medicine, Ankara (Turkey)

2002-08-15

346

Percutaneous Endovascular Stent-Graft for Iliac Pseudoaneurysm Following Lumbar Discectomy  

SciTech Connect

In a 24-year-old woman, an iliac pseudoaneurysm following lumbar discectomy was successfully treated by percutaneous placement of a self-expanding stent-graft. A postprocedural angiogram demonstrated complete exclusion of the pseudoaneurysm without leakage of contrast agent.

Hong, Seong J.; Oh, Joo H.; Yoon, Yup [Department of Diagnostic Radiology, College of Medicine, Kyung Hee University, 1, Hoekidong, Dongdaemunku, Seoul 130-702 (Korea, Republic of)

2000-11-15

347

Bone disease in African children with slipped capital femoral epiphysis: Histomorphometry of Iliac crest biopsies  

Microsoft Academic Search

African teenagers with slipped capital femoral epiphysis (SCFE) not infrequently also have genu valgum (knock-knee). Because we had previously demonstrated metabolic bone disease attributable to dietary calcium deficiency in black teenagers with genu valgum, we examined 29 black teenagers (15 male, 14 female) with SCFE for metabolic bone disease. Each patient had an iliac crest bone biopsy taken (after double

C. M. Schnitzler; E. D. Daniels; J. M. Mesquita; G. P. Moodley; D. Zachen; J. Cakic; J. M. Pettifor

1998-01-01

348

Internal Iliac Artery Embolization during an Endovascular Aneurysm Repair with Detachable Interlock Microcoils  

PubMed Central

Objective The purpose of this study was to evaluate the effectiveness of detachable interlock microcoils for an embolization of the internal iliac artery during an endovascular aneurysm repair (EVAR). Materials and Methods A retrospective review was conducted on 40 patients with aortic aneurysms, who had undergone an EVAR between January 2010 and March 2012. Among them, 16 patients were referred for embolization of the internal iliac artery for the prevention of type II endoleaks. Among 16 patients, 13 patients underwent embolization using detachable interlock microcoils during an EVAR. Computed tomographic angiographies and clinical examinations were performed during the follow-up period. Technical success, clinical outcome, and complications were reviewed. Results Internal iliac artery embolizations using detachable interlock microcoils were technically successful in all 13 patients, with no occurrence of procedure-related complications. Follow-up imaging was accomplished in the 13 cases. In all cases, type II endoleak was not observed with computed tomographic angiography during the median follow-up of 3 months (range, 1-27 months) and the median clinical follow-up of 12 months (range, 1-27 months). Two of 13 (15%) patients had symptoms of buttock pain, and one patient died due to underlying stomach cancer. No significant clinical symptoms such as bowel ischemia were observed. Conclusion Internal iliac artery embolization during an EVAR using detachable interlock microcoils to prevent type II endoleaks appears safe and effective, although this should be further proven in a larger population.

Kim, Woo Chul; Hong, Kee Chun; Kim, Jang Yong; Cho, Soon Gu; Park, Jae Young

2014-01-01

349

The incidence of iliac, femoral, and popliteal artery aneurysms in hospitalized patients  

Microsoft Academic Search

Purpose: Previous studies have attempted to determine the incidence and mortality rate of abdominal aortic aneurysms in a variety of populations; however, the incidence of iliac, femoral, and popliteal artery aneurysms have not been established. The objective of this study was to determine the incidence of lower extremity aneurysms in hospitalized patients in the state of Utah, which has a

Peter F. Lawrence; Shauna Lorenzo-Rivero; Joseph L. Lyon

1995-01-01

350

[Endovascular closure of iatrogenic arteriovenous anastomosis of the iliac artery and vein].  

PubMed

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

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

351

Effect of Atorvastatin-Eluting Stents in a Rabbit Iliac Artery Restenosis Model  

PubMed Central

Statins have pleiotropic effects, which include the inhibition of neointima hyperplasia, the inhibition of vascular inflammation, and platelet inhibition. The aim of this study was to examine the effect of an atorvastatin-eluting stent (AES) in a rabbit iliac artery overstretch restenosis model. Ten rabbits were used in this study (10 rabbits, 10 iliac arteries for each stent). An AES and paclitaxel-eluting stent (PES) were implanted in the left and right iliac arteries in a rabbit (2 stents in each rabbit). The stents were deployed with oversizing (stent/artery ratio 1.3:1), and histopathologic analysis was assessed at 28 days after stenting. There were no significant differences in the injury score, lumen area, or inflammation score. There were significant differences in the neointimal area (0.7±0.18 mm2 in the AES group vs. 0.4±0.25 mm2 in the PES group, p<0.01), in the percentage stenosis area (14.8±5.06% in the AES group vs. 10.5±6.80% in the PES group, p<0.05), and in the fibrin score (0.4±0.51 in the AES group vs. 2.7±0.48 in the PES group, p<0.001). Although the AES did not suppress neointimal hyperplasia compared with the PES, it showed a superior arterial healing effect in a rabbit iliac artery overstretch restenosis model. PMID:24400214

Lim, Kyung Seob; Bae, In Ho; Park, Jun-Kyu; Park, Dae Sung; Kim, Jong Min; Kim, Jung Ha; Cho, Dong Lyun; Sim, Doo Sun; Park, Keun-Ho; Hong, Young Joon; Ahn, Youngkeun

2013-01-01

352

Crossover iliofemoral bypass grafting for treatment of unilateral iliac atherosclerotic disease  

Microsoft Academic Search

Purpose: In patients with unilateral iliac disease, a less invasive procedure than aortobifemoral bypass grafting may be desirable, especially in poor-risk patients or when sexual dysfunction is feared. In these cases, femorofemoral (FF) bypass grafting is often proposed. Compared with FF bypass grafting, iliofemoral (IF) bypass grafting avoids bilateral exposure of the groins, which may reduce the risk of infection.

Jean-Olivier Defraigne; César Vazquez; Raymond Limet

1999-01-01

353

Comparative study of iliac crest and proximal femur histomorphometry in normal patients  

Microsoft Academic Search

The relation between the bone histomorphometric profile of the iliac crest and regions of the proximal femur was investigated. In the proximal femur four blocks were selected, representing the subchondral principal compressive (SPC) and tensile (SPT) regions, the zone near the medial cortex in the principal compressive region (MPC), and the zone medial to the greater trochanter (MGT). Undecalcified tissue

N L Fazzalari; R J Moore; B A Manthey; B Vernon-Roberts

1989-01-01

354

Determination of connectivity density in human iliac crest bone biopsies assessed by a computerized method  

Microsoft Academic Search

The aim of the present study was to design a computer program (based on the ConnEulor principle) for direct measurement of 3-D connectivity density in iliac crest bone sections, as used for conventional histomorphometry. We used the physical disector principle and developed an algorithm for nonlinear alignment of the disector pairs. 3-D connectivity was evaluated in transiliac specimens from 30

J. S. Thomsen; J. Barlach; Li. Mosekilde

1996-01-01

355

29 CFR 1926.305 - Jacks-lever and ratchet, screw, and hydraulic.  

Code of Federal Regulations, 2010 CFR

...Jacks-lever and ratchet, screw, and hydraulic. 1926.305 Section 1926.305...Jacks—lever and ratchet, screw, and hydraulic. (a) General requirements. ...otherwise secured at once. (ii) Hydraulic jacks exposed to freezing...

2010-07-01

356

Symbiotic N 2 -fixation in alpine tundra: ecosystem input and variation in fixation rates among communities  

Microsoft Academic Search

Annual inputs of symbiotic N2-fixation associated with 3 species of alpine Trifolium were estimated in four alpine communities differing in resource supplies. We hypothesized that fixation rates would vary according to the degree of N, P, and water limitation of production, with the higher rates of fixation in N limited communities (dry meadow, moist meadow) and lower rates in P

William D. Bowman; James C. Schardt; Steven K. Schmidt

1996-01-01

357

A new bicortical tibial fixation technique in anterior cruciate ligament reconstruction with quadruple hamstring graft.  

PubMed

We report a prospective series of 101 patients receiving a four-strand semitendinosus-gracilis autograft for anterior cruciate ligament reconstruction using a new bicortical tibial fixation technique with bioabsorbable interference screws. Patients (average age 32 years) were operated on between November 1997 and Mai 1998, and follow-up was at least 12 months postoperatively. The evaluation consisted of history, clinical examination, IKDC score, Cincinnati Knee Score, KT-1000 testing, standardized radiography and magnetic resonance imaging. One hundred patients were available for follow-up. There were two traumatic reruptures 6 and 11 months postoperatively. By IKDC score 87 patients were in groups A and B, 12 in group C, and 2 with a rerupture in group D. Mean Cincinnati Knee Score was 82 (range 46-100), KT-1000 manual maximum at follow-up showed an average difference of 1.7 mm between the sides. Full extension was rapidly achieved in all cases, and flexion averaged 135 degrees . Considering the enlargement caused by the bioabsorbable interference screws, the incidence of tunnel widening was 6.6% on the femoral side and 1.7% on the tibial side. Tunnel widening did not affect the clinical results. Three patients experienced an effusion after more than 6 months postoperatively. There was one infection, which settled without functional impairment after early arthroscopic lavage and intravenous antibiotics. Otherwise no complications occurred. The described technique for anterior cruciate ligament reconstruction combines the advantage of anatomical graft position with sufficient graft fixation. A short intra-articular graft construct with a strong tendon to bone interface was created. Clinically, 87% of patients had a normal or nearly normal IKDC score at follow-up. Magnetic resonance imaging revealed a considerable increase in tunnel area caused by the insertion of the interference screws. On the other hand, the development of a "fibrous interzone" between the graft and the bone tunnel was prevented in most cases. At short-term follow-up the bicortical tibial fixation proved to be efficient even with an aggressive rehabilitation program. PMID:10975262

Buelow, J U; Siebold, R; Ellermann, A

2000-01-01

358

Hybrid dynamic modeling of a high-speed ball-screw drive system  

Microsoft Academic Search

The longitudinal and torsional vibration of a lead-screw usually limits the closed-loop performance of a high-speed ball-screw drive system. It is difficult to accurately characterize the high frequency dynamics of the ball-screw drive system via a traditional lumped modeling method. This paper proposes a hybrid parameter modeling method. The model contains a distributed parameter model of the lead-screw with the

Yan Liu; Tong Zhao; Hui Zhang

2010-01-01

359

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

PubMed Central

Background Various fabrication methods are used to improve the stability and osseointegration of screws within the host bone. The aim of this study was to investigate whether roughened surface titanium screws fabricated by electron beam melting can provide better stability and osseointegration as compared with smooth titanium screws in sheep cervical vertebrae. Methods Roughened surface titanium screws, fabricated by electron beam melting, and conventional smooth surface titanium screws were implanted into sheep for 6 or 12 weeks (groups A and B, respectively). Bone ingrowth and implant stability were assessed with three-dimensional imaging and reconstruction, as well as histological and biomechanical tests. Results No screws in either group showed signs of loosening. Fibrous tissue formation could be seen around the screws at 6 weeks, which was replaced with bone at 12 weeks. Bone volume/total volume, bone surface area/bone volume, and the trabecular number were significantly higher for a define region of interest surrounding the roughened screws than that surrounding the smooth screws at 12 weeks. Indeed, for roughened screws, trabecular number was significantly higher at 12 weeks than at 6 weeks. On mechanical testing, the maximum pullout strength was significantly higher at 12 weeks than at 6 weeks, as expected; however, no significant differences were found between smooth and roughened screws at either time point. The maximum torque to extract the roughened screws was higher than that required for the smooth screws. Conclusions Electron beam melting is a simple and effective method for producing a roughened surface on titanium screws. After 12 weeks, roughened titanium screws demonstrated a high degree of osseointegration and increased torsional resistance to extraction over smooth titanium screws. PMID:24788866

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

2014-01-01

360

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

SciTech Connect

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.

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

361

Incorporation of prefabricated screw, pneumatic, and solenoid valves into microfluidic devices  

E-print Network

Incorporation of prefabricated screw, pneumatic, and solenoid valves into microfluidic devices S This paper describes a method for prefabricating screw, pneumatic, and solenoid valves and embedding them a technique for creating standardized, prefabricated valves of three types--screw valves, pneumatic valves

Prentiss, Mara

362

Piezoelectric actuators for screw-in cartridge valves  

Microsoft Academic Search

Research has been undertaken to explore the possibility of using smart materials for the actuation of screw-in cartridge valves. Four types were considered and a piezoelectric (PZT) stack was selected as the most appropriate actuator. The concept of a spool valve piloted by a PZT valve was chosen for investigation. A mathematical model of a hydraulic system with a spool

Xiaoping Ouyang; Derek Tilley; Patrick Keogh; Huayong Yang; Nigel Johnson; Chris Bowen; Peter Hopkins

2008-01-01

363

Probabilistic model and experimental identification of screw-attachment in  

E-print Network

for the screw-attachment of large light partition wall between plasterboard (CPC) plate and metallic frame in Materials Characterisation Location: New Forest, ENGLAND Date: JUN 17-19, 2009, New Forest : United Kingdom element is a large light partition wall with plasterboard using metallic frame. The plasterboard

Paris-Sud XI, Université de

364

Intelligent Operation Parameters Optimization for Screw Conveyor Based on PSO  

Microsoft Academic Search

Particle swarm optimization (PSO) is a population based stochastic optimization technique. As a result, PSO algorithm is widely used in mechanical engineering design field. Screw conveyors are used extensively in agriculture and processing industries for elevating and\\/or transporting bulk materials over short to medium distances. They are very effective for conveying dry particulate solids, giving good control over the throughput.

Jianghui Cai; Wenjun Meng

2010-01-01

365

Screw dislocation in a two-phase isotropic thin film  

NASA Astrophysics Data System (ADS)

By using the complex potential and conformal mapping techniques, the stress field of a straight screw dislocation lying parallel to the surface of a two-phase isotropic thin film of equal thickness in each phase and a welded interface is analyzed. The solution, when reduced to a single-phase thin film, is in agreement with that derived by Liebfried and Dietze using an infinite array of image dislocations. The presence of a second phase is found to increase the magnitude of the stress components for the screw dislocation except for ?xz near the interface where the effect is the reverse. The image force on the dislocation near the interface can be attractive or repulsive depending upon whether the dislocation is situated in the hard or soft phase. In the case where the dislocation is situated in the soft phase, the total image force tends to drive the screw dislocation to the surface. Furthermore, the screw dislocation is found to be unstable at the interface. The elastic solution for an interfacial dislocation becomes a special case.

Chu, S. N. G.

1982-04-01

366

A molecular "screw-clamp": accelerating click reactions in miniemulsions.  

PubMed

The interface as a "screw clamp": the copper-free 1,3-dipolar azide-alkyne cycloaddition at the interface of nanodroplets in miniemulsions was studied in detail by NMR spectroscopic methods. The reaction at the oil-water interface proved to exhibit higher rate constants, increased molecular weights and high regioregularity compared to the reaction in solution. PMID:25068922

Alexandrino, Evandro M; Buchold, Philipp; Wagner, Manfred; Fuchs, Adrian; Kreyes, Andreas; Weiss, Clemens K; Landfester, Katharina; Wurm, Frederik R

2014-09-18

367

Throttling means for geothermal streams. [helical screw expander  

Microsoft Academic Search

A helical screw expander for deriving energy from geothermally heated water is described. The expander includes a pair of helical rotors with helical structures fitted in an expansion chamber. The geothermally heated water is introduced into said chamber through a throttle port located at an end face of the expansion chamber, whereby precipitation which occurs as a consequence of reduction

Sprankle

1976-01-01

368

INTERIOR VIEW OF JAMES HARRIS CUTTING SCREW THREADS INTO THE ...  

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

INTERIOR VIEW OF JAMES HARRIS CUTTING SCREW THREADS INTO THE INTERIOR OF FITTINGS ON ONE IN A BANK OF TAPPING MACHINES, EACH OPERATED BY THE SAME WORKER SIMULTANEOUSLY BUT TIMED TO REQUIRE WORKER ACTION AT INTERVALS THAT DO NOT INTERFERE WITH THE OTHER MACHINES. - Stockham Pipe & Fittings Company, Tapping Room, 4000 Tenth Avenue North, Birmingham, Jefferson County, AL

369

Positive identification facilitated by implanted metallic plate and screws.  

PubMed

Personal identification is an essential subject in forensic practice. With skeletonized remains, an anthropological examination is performed for personal identification. Here we describe the positive identification of skeletonized human remains from the serial numbers of implanted metallic plate and screws. PMID:19534396

Kinoshita, Hiroshi; Motomura, Hiroyuki; Kasuda, Shogo; Nishiguchi, Minori; Matsui, Kiyoshi; Takahashi, Motonori; Ouchi, Harumi; Minami, Takako; Yamamura, Takehiko; Otsu, Nao; Yoshida, Shie; Adachi, Nobuyuki; Ohta, Takehiko; Hishida, Shigeru

2009-04-01

370

21 CFR 888.3010 - Bone fixation cerclage.  

Code of Federal Regulations, 2011 CFR

... 2011-04-01 false Bone fixation cerclage. 888...ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED...Prosthetic Devices § 888.3010 Bone fixation cerclage. (a) Identification. A bone fixation cerclage...

2011-04-01

371

21 CFR 888.3010 - Bone fixation cerclage.  

Code of Federal Regulations, 2010 CFR

... 2010-04-01 false Bone fixation cerclage. 888...ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED...Prosthetic Devices § 888.3010 Bone fixation cerclage. (a) Identification. A bone fixation cerclage...

2010-04-01

372

21 CFR 888.3010 - Bone fixation cerclage.  

Code of Federal Regulations, 2012 CFR

... 2012-04-01 false Bone fixation cerclage. 888...ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED...Prosthetic Devices § 888.3010 Bone fixation cerclage. (a) Identification. A bone fixation cerclage...

2012-04-01

373

21 CFR 888.3010 - Bone fixation cerclage.  

Code of Federal Regulations, 2013 CFR

... 2013-04-01 false Bone fixation cerclage. 888...ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED...Prosthetic Devices § 888.3010 Bone fixation cerclage. (a) Identification. A bone fixation cerclage...

2013-04-01

374

Fixation and the Road Not Taken  

Microsoft Academic Search

In this article, the psychic and existential impact that fixation has on an individual's life is addressed. A person may drift through years that are dictated by the circuitous path of a fixation and its vicissitude of the repetition compulsion. When such \\

Peter Shabad

1987-01-01

375

Bioabsorbable fixation in orthopaedic surgery and traumatology  

Microsoft Academic Search

Bioabsorbable internal fixation devices were introduced clinically in the treatment of fractures and osteotomies of the extremities at the Department of Orthopaedics and Traumatology, Helsinki University, in 1984. Since November 5, 1984, a total of 3200 patients were managed using bone or ligament fixation devices made of self-reinforced (matrix and fibres of the same polymer) bioabsorbable alpha-hydroxy polyesters. The devices

Pentti U Rokkanen; Ole Böstman; Eero Hirvensalo; E. Antero Mäkelä; Esa K Partio; Hannu Pätiälä; Seppo Vainionpää; Kimmo Vihtonen; Pertti Törmälä

2000-01-01

376

Nitrogen fixation in Lake Mendota, Madison, Wisconsin  

Microsoft Academic Search

The cffccts of various environmental conditions, and of ccl1 composition, heterocyst con- tent, and nitrogen content of algal s'amples, on fixation of N, by colonial and filamentous algae in Lake Mendota were investigated. IIctcrocyst content and temperature were significantly and positively related to accty- lcnc recluction activity ( NB fixation); depth of sample collection was negatively related. Rvailablc data do

MARGUERITE SHERMAN TORREY; G. F. LEE

1976-01-01

377

Original article The economics of nitrogen fixation  

E-print Network

. Of course, soil type and climate also affect the value of nitrogen, but so do fertiliser and crop and animalOriginal article The economics of nitrogen fixation Steven SCHILIZZI*, David J. PANNELL Agriculture the economic value of nitrogen fixation in a Mediterranean-type farming system in Western Australia, as well

Paris-Sud XI, Université de

378

Dynamic Lumbar Pedicle Screw-Rod Stabilization: Two-Year Follow-Up and Comparison with Fusion  

PubMed Central

Background: A lumbar pedicular dynamic stabilization system (LPDSS) is an alternative to fusion for treatment of degenerative disc disease (DDD). In this study, clinical and radiological results of one LPDSS (Saphinaz, Medikon AS, Turkey) were compared with results of rigid fixation after two-year follow-up. Methods: All patients had anteroposterior and lateral standing x-rays of the lumbar spine preoperatively and at 3 months, 12 months and 24 months after surgery. Lordosis of the lumbar spine, segmental lordosis and ratio of the height of the intervertebral disc spaces (IVS) measured preoperatively and at 3 months, 12 months and 24 months after surgery. All patients underwent MRI and/or CT preoperatively, 3months, 12 months and 24 months postoperatively. The ratio of intervertebral disc space to vertebral body height (IVS) and segmental and lumbar lordosis were evaluated preoperatively and postoperatively. Pain scores were evaluated via Visual Analog Scale (VAS) and Oswestry Disability Index (ODI) preoperatively and postoperatively. Results: In both groups, the VAS and ODI scores decreased significantly from preoperatively to postoperatively. There was no difference in the scores between groups except that a lower VAS and ODI scores were observed after 3 months in the LPDSS group. In both groups, the IVS ratio remained unchanged between preoperative and postoperative conditions. The lumbar and segmental lordotic angles decreased insignificantly to preoperative levels in the months following surgery. Conclusions: Patients with LPDSS had equivalent relief of pain and maintenance of sagittal balance to patients with standard rigid screw-rod fixation. LPDSS appears to be a good alternative to rigid fixation. PMID:20448815

Ozer, Ali Fahir; Crawford, Neil R; Sasani, Mehdi; Oktenoglu, Tunc; Bozkus, Hakan; Kaner, Tuncay; Aydin, Sabri

2010-01-01

379

Eighth international congress on nitrogen fixation. Final program  

SciTech Connect

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.

Not Available

1990-12-31

380

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

SciTech Connect

We present a case of acute small-bowel bleeding from the collateral artery of the superior mesenteric-left deep circumflex iliac artery that was successfully managed by transarterial coil embolization.

Shimohira, Masashi, E-mail: m_shimohira@yahoo.co.jp; Ogino, Hiroyuki; Sasaki, Shigeru; Nishikawa, Hiroko; Shibamoto, Yuta [Nagoya City University Graduate School of Medical Sciences, Department of Radiology (Japan)

2009-03-15

381

Successful Percutaneous Coil Embolization of a Ruptured Internal Iliac Artery Aneurysm Remnant after Abdominal Aortic Aneurysm Repair via the Deep Iliac Circumflex Artery  

PubMed Central

Here, we describe a case of an 83-year-old man treated with percutaneous IIA coil embolization for an enlarging remnant IIA aneurysm. CT scans revealed a contained rupture and persistent flow in the right IIA with the enlargement. We selected percutaneous embolization via the deep iliac circumflex artery, that was communicating with the superior gluteal artery and the IIA. Coil embolization of the arteries supplying the IIA aneurysm was successfully performed with 12 embolization coils placed in the IIA and its branches. The absence of blood flow and shrinkage of the aneurysm were confirmed by CT three months after embolization. PMID:24719671

2014-01-01

382

Dinitrogen fixation in aphotic oxygenated marine environments  

PubMed Central

We measured N2 fixation rates from oceanic zones that have traditionally been ignored as sources of biological N2 fixation; the aphotic, fully oxygenated, nitrate (NO?3)-rich, waters of the oligotrophic Levantine Basin (LB) and the Gulf of Aqaba (GA). N2 fixation rates measured from pelagic aphotic waters to depths up to 720 m, during the mixed and stratified periods, ranged from 0.01 nmol N L?1 d?1 to 0.38 nmol N L?1 d?1. N2 fixation rates correlated significantly with bacterial productivity and heterotrophic diazotrophs were identified from aphotic as well as photic depths. Dissolved free amino acid amendments to whole water from the GA enhanced bacterial productivity by 2–3.5 fold and N2 fixation rates by ~2-fold in samples collected from aphotic depths while in amendments to water from photic depths bacterial productivity increased 2–6 fold while N2 fixation rates increased by a factor of 2 to 4 illustrating that both BP and heterotrophic N2 fixation were carbon limited. Experimental manipulations of aphotic waters from the LB demonstrated a significant positive correlation between transparent exopolymeric particle (TEP) concentrations and N2 fixation rates. This suggests that sinking organic material and high carbon (C): nitrogen (N) micro-environments (such as TEP-based aggregates or marine snow) could support high heterotrophic N2 fixation rates in oxygenated surface waters and in the aphotic zones. Indeed, our calculations show that aphotic N2 fixation accounted for 37 to 75% of the total daily integrated N2 fixation rates at both locations in the Mediterranean and Red Seas with rates equal or greater to those measured from the photic layers. Moreover, our results indicate that that while N2 fixation may be limited in the surface waters, aphotic, pelagic N2 fixation may contribute significantly to new N inputs in other oligotrophic basins, yet it is currently not included in regional or global N budgets. PMID:23986748

Rahav, Eyal; Bar-Zeev, Edo; Ohayon, Sarah; Elifantz, Hila; Belkin, Natalia; Herut, Barak; Mulholland, Margaret R.; Berman-Frank, Ilana

2013-01-01

383

Equally good fixation of cemented and uncemented cups in total trapeziometacarpal joint prostheses  

PubMed Central

Background and purpose Cup failure is a recognized problem in total trapeziometacarpal (TM) joint prostheses; it may be related to poor fixation, which can be revealed by radiostereometric analysis (RSA). We compared the early implant migration of cemented trapezium cups to that of uncemented screw cups. Patients and methods In a prospective, parallel-group, randomized patient-blinded clinical trial, we included 32 hands in 28 patients (5 males) with a mean age of 58 (40–77) years and with Eaton stage-2 or -3 osteoarthritis of the trapeziometacarpal joint. Patients were randomized to surgery with a cemented DLC all-polyethylene cup (C) (n = 16) or an uncemented hydroxyapatite-coated chrome-cobalt Elektra screw cup (UC) (n = 16). Uncemented cups were inserted without threading of the bone. Stereoradiographs for evaluation of cup migration (primary effect size) and DASH and pain scores were obtained during 2 years of follow-up. Results The 2-year total translation (TT) was similar (p = 0.2): 0.24 mm (SD 0.10) for the C (n = 11) and 0.19 mm (SD 0.16) for the UC (n = 11). Variances were similar (p = 0.4). Judged by RSA, 2 UC cups and 1 C cup became loose (TT > 1 mm). Both UC cups were found to be loose at revision. Grip strength, pain, and DASH scores were similar between groups at all measurement points. Interpretation Early implant fixation and clinical outcome were equally good with both cup designs. This is the first clinical RSA study on trapezium cups, and the method appears to be clinically useful for detection of loose implants. PMID:23343372

2013-01-01

384

Dis Colon Rectum . Author manuscript Usefulness of laboratory data in the management of right iliac fossa pain  

E-print Network

. Patients and methods Patients with right iliac fossa pain referred to the surgeon were included. Blood with the evolution of the inflammatory process. Its predictive values improve in combination with the leukocyte count

Boyer, Edmond

385

Endovascular PTFE-Covered Stent for Treatment of an External Iliac Artery Pseudoaneurysm in the Presence of Chronic Infection  

SciTech Connect

A 75-year-old woman with an external iliac artery pseudoaneurysm, thought to have resulted from a chronic loosening and infection of a total hip replacement, was successfully treated by placement of a covered endoluminal stent.

Warren, Martin J., E-mail: martin.warren@ldh.nhs.uk; Fabian, Sebastian [Luton and Dunstable NHS Trust, Diagnostic Imaging (United Kingdom); Tisi, Paul [Luton and Dunstable NHS Trust, Department of Vascular Surgery (United Kingdom)

2007-07-15

386

Experience with titanium devices for rib fixation and coverage of chest wall defects  

PubMed Central

OBJECTIVES To describe our experience with two new titanium-based devices for chest wall reconstruction and stabilization. METHODS A retrospective analysis of 18 consecutive patients (multiple rib fractures n = 9, iatrogenic rib fracture n = 2, lung herniation n = 2, chest wall tumour n = 5) who underwent surgery for rib fractures or chest wall tumours requiring chest wall resection and reconstruction between October 2010 and March 2012 was conducted. Chest wall defects and rib fractures were fixed with titanium clips and bars or titanium plates and screws through a posterolateral thoracotomy. RESULTS There were 12 males, and the median age was 61 years. There were no postoperative deaths. The only postoperative complication observed was a pleural effusion requiring drainage in one patient who had titanium clips for the fixation of multiple traumatic rib fractures. Median length of stay of the drain and median length of hospital stay were 3 days (range 1–6) and 4 days (range 2–42 days), respectively. The average follow-up period of operatively managed patients was 6 months, (range 2–14 months). Two cases of hardware failure occurred in two patients treated for a lung hernia with large chest wall defects involving the anterior costal margin with either devices. CONCLUSIONS Titanium devices (clips and bars; screws and plates) are effective and safe for repair of rib fractures and large chest wall defect reconstruction with minimal complications and good long-term results. PMID:22815325

Bille, Andrea; Okiror, Lawrence; Karenovics, Wolfram; Routledge, Tom

2012-01-01

387

A new volar plate DiPhos-RM for fixation of distal radius fracture: preliminary report.  

PubMed

We analyzed the efficiency of a new plate DiPhos-RM in CFR-PEEK [carbon-fiber-reinforced poly (etheretherketone)] for the volar fixation of distal radius fractures. The new plate's composition has the advantage of x-ray absolute transparency, therefore allowing to monitor the healing of the fracture. The desired combination of high strength and low rigidity is obtained through the use of the polymer composites CFR-PEEK. In this preliminary study (from March 2012 to June 2012), 10 cases of intra-articular distal radius fractures were treated with DiPhos-RM produced by Lima Corporate (Italy). The fractures were classified according to the AO classification, 4 fractures were type C1, 3 type C2, and 3 were A2. A preoperative computed tomography scan was carried out in all patients. One patient also underwent a postoperative computed tomography scan. Grip strength, range of motion, and DASH score were evaluated at follow-up. There were no cases of hardware failure. Specifically, no loss of position or alignment of fixed-angle locking screws or breakage of the plate were observed. Radiographic union was present at an average of 6 weeks (range, 5 to 8 wk). The overall preliminary experience with this new plate is favorable. The new plate is easy to apply and provides the surgeon dual options of fixed-angle or variable-angle screws. It was rigid enough to maintain the reduction also in AO type C articular fractures. PMID:23423235

Tarallo, Luigi; Mugnai, Raffaele; Adani, Roberto; Catani, Fabio

2013-03-01

388

Complications after selective embolization in the bilateral internal iliac arteries and the median sacral artery with gelfoam particles in dogs  

PubMed Central

Objective: The study aimed to observe the complications after the bilateral internal iliac arteries and the median sacral artery embolization by different severity and combinations of gelfoam particles. Methods: Sixteen healthy adult dogs were randomly divided into five groups. Under the monitoring of digital subtraction angiography (DSA), gelfoam particles with diameter of 50-150 ?m were applied. In group A, embolization was performed up to the trunk of bilateral internal iliac arteries and the median sacral artery; in group B, embolization was up to the trunk of bilateral internal iliac arteries; in group C, embolization was up to the first branch of bilateral internal iliac arteries and the median sacral artery; in group D, embolization was up to the trunk of unilateral internal iliac artery and the median sacral artery; in group E embolization was performed up to the trunk of unilateral internal iliac artery. Results: Seven dogs died within 48 hours after embolization. In the dead animals of groups A, C and D, there were rectum necrosis and lamellar obfuscation and hemorrhage edema in bladder. In the histological examination, there are rectum and bladder cell dissociation, inflammatory cell infiltration and epithelial cell ablating in the dead animals. The embolization mainly presented in arterioles with a diameter of 100-200 ?m. Conclusion: When gelfoam particles of 50-150 ?m in diameter were applied for embolization in the internal iliac artery and median sacral artery, at least unilateral internal iliac artery should be preserved when embolization is performed in the proximal artery and the trunk.

Li, Yetian; Wang, Wei; Wang, Guangye; Yin, Zongsheng

2014-01-01

389

Trauma-associated bleeding from the bilateral internal iliac arteries resolved using angiographic embolization.  

PubMed

Pelvic fracture is associated with high mortality. The management of major pelvic injuries remains one of the most important issues in modern trauma care. A 39-year-old male patient presented at the emergency department after being hit with a 500 kg load. His general condition was average with unstable vital signs. Pelvic tomography revealed fractured bone structure, thickening secondary to hematoma in both iliopsoas muscles, and hemorrhage-related active extravasation in the left internal iliac trace. The patient's hemodynamics worsened despite fluid and blood replacement, and angiographic embolization was scheduled. Bilateral embolization of the iliac artery was performed. Control angiography confirmed that full embolization was established. The patient was monitored in intensive care, but expired after three days due to acute kidney failure, disseminated intravascular coagulation, and multi-organ failure. Angiographic embolization is a technique improves hemorrhage control in pelvic trauma but can also increase risk of complications such as ischemia and necrosis. PMID:24347219

Aygün, Ali; Karaca, Yunus; Ayan, Emin; Suha, Türkmen; Dinç, Hasan

2013-11-01

390

Transient occlusion of bilateral internal iliac arteries facilitates bloodless operative field in subcapsular prostatectomy.  

PubMed

Transurethral resection of the prostate is the gold standard of surgical treatment for benign prostatic hyperplasia (BPH). Nevertheless, open subcapsular prostatectomy is still performed for large BPH. While enucleation of prostatic adenoma is being performed, unneglectable bleeding can occur and surgeons need to rush to remove adenomas, often using fingers and in a blinded fashion. The blood supply to the prostatic capsule and adenoma can be reduced to a marked extent in subcapsular prostatectomy if the bilateral internal iliac arteries are transiently occluded. Thus, a bloodless operative field is reasonably acquired during enucleation of adenoma, which would, otherwise, be a cause for concern to surgeons due to bleeding. It is not always applicable, but it could be an option if the estimated volume of BPH is more than 100?mL. In two cases, bilateral internal iliac arteries were occluded with Bulldog clamps, and then adenomas of 159 and 97?g were enucleated. PMID:22431941

Takeuchi, Takumi; Zaitsu, Masayoshi; Mikami, Koji; Yui, Shunsuke; Takeshima, Yuta; Okamoto, Naohiko; Imao, Sadao

2012-01-01

391

Treatment of Secondary Stent-Graft Collapse After Endovascular Stent-Grafting for Iliac Artery Pseudoaneurysms  

SciTech Connect

We report the case of a patient who developed an asymptomatic pseudoaneurysm in the left external iliac artery after transplant nephrectomy. The pseudoaneurysm most probably arose as a suture aneurysm from the external iliac artery after removal of the graft renal artery. Obviously we can not exclude the possibility it was a true aneurysm, although this seems much less likely. The pseudoaneurysm was detected during a routine CT scan and was treated interventionally with a stent-graft. One month later the asymptomatic patient underwent a vascular ultrasound examination including color Doppler, power Doppler, and B-flow as a routine control. An endoleak with collapse of the stent-graft was diagnosed. There was no evidence of stent infection. At a reintervention, the pseudoaneurysm was successfully treated using two uncovered Palmaz stents at the proximal and distal edge of the stent graft. Peri- and post-interventional ultrasound and CT angiography confirmed the exclusion of the aneurysm without an endoleak.

Clevert, D.-A. [Institute of Clinical Radiology, University of Munich - Grosshadern Campus (Germany)], E-mail: clevert@web.de; Stickel, M.; Steitz, H.-O.; Kopp, R. [University of Munich, Department of Surgery, Klinikum Grosshadern (Germany); Strautz, T.; Flach, P.; Johnson, T. [Institute of Clinical Radiology, University of Munich - Grosshadern Campus (Germany); Jung, E.M. [Klinikum Passau, Department of Diagnostic Radiology (Germany); Jauch, K.W. [University of Munich, Department of Surgery, Klinikum Grosshadern (Germany); Reiser, M. [Institute of Clinical Radiology, University of Munich - Grosshadern Campus (Germany)

2007-02-15

392

Endovascular treatment of an iliac artery rupture caused by invasive Salmonella spondylodiscitis.  

PubMed

The rate of non-typhoid Salmonella infections has increased remarkably in recent years. Endovascular system infection is one of the most serious forms of extraintestinal Salmonella infection. The abdominal aorta is frequently involved, while bone and joint involvement are rarely seen. We present a rare case of successful endovascular treatment of a left iliac artery rupture and pseudoaneurysm both occurring due to the direct invasion of lumbar spondylodiscitis caused by Salmonella typhimurium. PMID:25230272

Kur?un, Ebru; Turunç, Tuba; Ozkan, U?ur; Demiro?lu, Yusuf Ziya

2014-01-01

393

Sonographic evaluation of apophyseal ossification of the iliac crest in forensic age diagnostics in living individuals  

Microsoft Academic Search

Due to the requirement to minimise exposure to radiation, it is desirable to develop non-ionising imaging procedures for the\\u000a analysis of skeletal maturation for forensic age diagnostics in living individuals. The present pilot study analyses the applicability\\u000a of ultrasound examinations for the evaluation of apophyseal ossification of the iliac crest. With reference to the sonographic\\u000a staging of clavicular ossification, the

Sven Schmidt; Andreas Schmeling; Per Zwiesigk; Heidi Pfeiffer; Ronald Schulz

2011-01-01

394

Reference Diameters of the Abdominal Aorta and Iliac Arteries in the Korean Population  

PubMed Central

Purpose It is important to know the normal diameter of artery throughout the body so that clinicians are able to determine when an artery becomes aneurysmal. However, there are no previous studies on the normal diameter of arteries in the general Korean population. The purpose of this article is to determine the normal reference diameters of the abdominal aorta and iliac arteries in the Korean population. Materials and Methods We recruited the study population from three cities in Korea for the abdominal aortic aneurysm (AAA) screening. We measured the diameter of the aorta and iliac arteries. We analyzed the reference diameter of the population without AAA. The results were analyzed by Student's t-test and ANOVA on SPSS version 19. A p value <0.05 was considered to be statistically significant. Results One thousand two hundred and twenty-nine people were enrolled. 478 men and 751 women, with a mean age of 63.9±10.1 years (range 50 to 91) were examined. Eleven out of 1229 (0.89%) were diagnosed with AAA. In the population of 1218 people without AAA, the mean diameters (cm) of male/female were 2.20/2.11 (p<0.001) at suprarenal, 2.04/1.90 (p<0.001) at renal, 1.90/1.79 (p<0.001) at infrarenal, 1.22/1.17 (p<0.001) at right iliac and 1.47/1.15 (p=0.097) at the left iliac, respectively. There was a significantly larger diameter in the male population. The diameter of each level increased with age. Conclusion The normal reference diameter of the infrarenal abdominal aorta in the Korean population is 1.9 cm in males and 1.79 cm in females. The diameter of the abdominal aorta increases with age. PMID:23225798

Ahn, Hyung-Joon; Park, Ho-Chul

2013-01-01

395

Iliac crest autograft versus alternative constructs for anterior cervical spine surgery: Pros, cons, and costs  

PubMed Central

Background: Grafting choices available for performing anterior cervical diskectomy/fusion (ACDF) procedures have become a major concern for spinal surgeons, and their institutions. The “gold standard”, iliac crest autograft, may still be the best and least expensive grafting option; it deserves to be reassessed along with the pros, cons, and costs for alternative grafts/spacers. Methods: Although single or multilevel ACDF have utilized iliac crest autograft for decades, the implant industry now offers multiple alternative grafting and spacer devices; (allografts, cages, polyether-etherketone (PEEK) amongst others). While most studies have focused on fusion rates and clinical outcomes following ACDF, few have analyzed the “value-added” of these various constructs (e.g. safety/efficacy, risks/complications, costs). Results: The majority of studies document 95%-100% fusion rates when iliac crest autograft is utilized to perform single level ACDF (X-ray or CT confirmed at 6-12 postoperative months). Although many allograft studies similarly quote 90%-100% fusion rates (X-ray alone confirmed at 6-12 postoperative months), a recent “post hoc analysis of data from a prospective multicenter trial” (Riew KD et. al., CSRS Abstract Dec. 2011; unpublished) revealed a much higher delayed fusion rate using allografts at one year 55.7%, 2 years 87%, and four years 92%. Conclusion: Iliac crest autograft utilized for single or multilevel ACDF is associated with the highest fusion, lowest complication rates, and significantly lower costs compared with allograft, cages, PEEK, or other grafts. As spinal surgeons and institutions become more cost conscious, we will have to account for the “value added” of these increasingly expensive graft constructs. PMID:22905321

Epstein, Nancy E.

2012-01-01

396

Nonisothermal model of single screw extrusion of generalized Newtonian fluids  

SciTech Connect

A nonisothermal model of the single screw extrusion processing of generalized Newtonian fluids is presented. Various temperature dependent forms of a generalized Newtonian fluid constitutive equation representing the Herschel-Bulkley fluid and its simplifications, including Bingham plastic, power law of Ostwald-de Waele, and Newtonian fluids, are applicable. The model includes the generally ignored transverse convection terms of the equation of energy. The importance of keeping the transverse convection terms in the analysis is demonstrated by applying the model and comparing findings to experimental results involving the transverse flow temperature distributions in single screw extruders, available in the literature. The numerical instabilities, arising principally from the convection terms, generally encountered in high-Peclet-number extrusion flows, could be eliminated by the use of the streamline upwind/Petrov-Galerkin formulation. The model is sufficiently general to accommodate Navier's wall slip at the wall boundary condition commonly encountered during the processing of gels and concentrated suspensions.

Lawal, A.; Kalyon, D.M. (Stevens Inst. of Technology, Hoboken, NJ (United States). Highly Filled Materials Inst.)

1994-07-01

397

Analysis of Eyring-Powell fluid in helical screw rheometer.  

PubMed

This paper aims to study the flow of an incompressible, isothermal Eyring-Powell fluid in a helical screw rheometer. The complicated geometry of the helical screw rheometer is simplified by "unwrapping or flattening" the channel, lands, and the outside rotating barrel, assuming the width of the channel is larger as compared to the depth. The developed second order nonlinear differential equations are solved by using Adomian decomposition method. Analytical expressions are obtained for the velocity profiles, shear stresses, shear at wall, force exerted on fluid, volume flow rates, and average velocity. The effect of non-Newtonian parameters, pressure gradients, and flight angle on the velocity profiles is noticed with the help of graphical representation. The observation confirmed the vital role of involved parameters during the extrusion process. PMID:24707194

Siddiqui, A M; Haroon, T; Zeb, M

2014-01-01

398

The Effect of Endovascular Revascularization of Common Iliac Artery Occlusions on Erectile Function  

SciTech Connect

To determine the incidence of erectile dysfunction in patients with common iliac artery (CIA) occlusive disease and the effect of revascularization on erectile function using the sexual health inventory for males (SHIM) questionnaire. All patients (35 men; mean age 57 {+-} 5 years; range 42-67 years) were asked to recall their sexual function before and 1 month after iliac recanalization. Univariate and multivariate analyses were performed to determine variables effecting improvement of impotence. The incidence of impotence in patients with CIA occlusion was 74% (26 of 35) preoperative