Sample records for iliac screw fixation

  1. Trans-iliac pin/bolt/screw internal fixation for sacroiliac luxation or separation in cats: six cases.

    PubMed

    Yap, Fui W; Dunn, Andrew L; Farrell, Michael; Calvo, Ignacio

    2014-04-01

    Trans-iliac pin, bolt or screw stabilisation was performed on six cats with sacroiliac (SI) luxation and separation. For the purpose of this study, SI luxation is defined as the separation of the iliac wing from the sacrum without fracture of the sacral or iliac wing; SI separation is defined as the separation of the iliac wing from the sacrum secondary to fracture of the sacrum and/or the iliac wing. Complications, surgical time and medium-to-long-term outcome were assessed by a retrospective review of the clinical records and owner questionnaires. Postoperative reduction of the SI joint was good-to-excellent in all cases and the outcome was considered good-excellent in all cats apart from one, where the trans-iliac bolt migrated dorsally from the iliac wing. This cat had bilateral SI luxations. Based on our results, trans-iliac fixation of SI luxation/separation is associated with good clinical outcome and should be considered as a treatment option in unilateral SI luxation in cats. Caution should be exercised in the use of trans-iliac pin/bolt as the sole method of stabilisation in bilateral SI luxations. PMID:24043721

  2. Mechanical properties of two canine iliac fracture fixation systems

    E-print Network

    VanGundy, Thomas Eugene

    1988-01-01

    to plate fixation for o lique canine iliac fracture fixation. The savings on implant fees and ease of lag screw application also may be a consideration for the veterinary surgeon. REFERENCES 1. Brinker WO, Piermattei DL, Flo GL. Handbook of Small..., for providng the funding that made this project possible. vi1 TABLE OF CONTENTS Page INTRODUCTION MATERIALS AND METHODS RESULTS Specimen Dimensions Static Testing Dynamic Testing DISCUSSION Pretesting Considerations Testing Considerations...

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

    PubMed Central

    2014-01-01

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

  4. Biodegradable Interference Screw Fixation Exhibits Pull-Out Force and Stiffness Similar to Titanium Screws

    Microsoft Academic Search

    Andreas Weiler; Henning J. Windhagen; Michael J. Raschke; Andrea Laumeyer; Reinhard F. G. Hoffmann

    1998-01-01

    Recently, increased interest in biodegradable interference screws for bone-tendon-bone graft fixation has led to numerous screws becoming available. The implants are made from different polymers and have different designs, which might influence their mechanical properties. Several studies have reported a wide range of mechanical results for these screws using different biomechanical models. The aim of the present study is to

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

    PubMed Central

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

    2014-01-01

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

  6. 21 CFR 872.4880 - Intraosseous fixation screw or wire.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...4880 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Surgical Devices § 872.4880 Intraosseous fixation screw or wire. (a)...

  7. 21 CFR 872.4880 - Intraosseous fixation screw or wire.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...4880 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Surgical Devices § 872.4880 Intraosseous fixation screw or wire. (a)...

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

    PubMed Central

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

    2014-01-01

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

  9. Primary Stability of Interference Screw FixationInfluence of Screw Diameter and Insertion Torque

    Microsoft Academic Search

    Dieter Kohn; Christoph Rose

    1994-01-01

    Interference screw fixation is frequently used in anterior cruciate ligament reconstruction with the bone-patellar tendon-bone graft. There have been no data available about the influence of screw diameter and insertion torque on primary stability. We designed a cadaveric study using paired knees to analyze the comparative effectiveness of 20-mm long screws of different diam eters (9 mm versus 7 mm)

  10. Outpatient percutaneous screw fixation of the acute Jones fracture

    Microsoft Academic Search

    Norman Mindrebo; K. Donald Shelbourne; Charles D. Van Meter; Arthur C. Rettig

    1993-01-01

    Nine patients (8 men and 1 woman, ranging in age from 17 to 22 years) who sustained a Jones fracture were treated with percutaneous intramedullary screw fixation as outpatients. All of the patients were varsity athletes. Seven were Division I scholarship athletes. Beginning at 7 to 10 days after surgery, all patients were allowed weightbearing as tolerated with a CAM

  11. The EndoPearl device increases fixation strength and eliminates construct slippage of hamstring tendon grafts with interference screw fixation

    Microsoft Academic Search

    Andreas Weiler; Manuel Richter; Gerhard Schmidmaier; Frank Kandziora; Norbert P. Südkamp

    2001-01-01

    Purpose: The EndoPearl (Linvatec, Largo, FL), a biodegradable device to augment the femoral interference screw fixation of hamstring tendon grafts has been developed. The first objective of this study was to compare the initial fixation strength of quadrupled hamstring tendons and biodegradable interference screw fixation with and without the application of the EndoPearl device. The second objective was to determine

  12. Subaxial subluxation after atlantoaxial transarticular screw fixation in rheumatoid patients

    PubMed Central

    Neo, Masashi; Sakamoto, Takeshi; Fujibayashi, Shunsuke; Yoshitomi, Hiroyuki; Nakamura, Takashi

    2009-01-01

    The most common cervical abnormality associated with rheumatoid arthritis (RA) is atlantoaxial subluxation, and atlantoaxial transarticular screw fixation has proved to be one of the most reliable, stable fixation techniques for treating atlantoaxial subluxation. Following C1–C2 fixation, however, subaxial subluxation reportedly can bring about neurological deterioration and require secondary operative interventions. Rheumatoid patients appear to have a higher risk, but there has been no systematic comparison between rheumatoid and non-rheumatoid patients. Contributing radiological factors to the subluxation have also not been evaluated. The objective of this study was to evaluate subaxial subluxation after atlantoaxial transarticular screw fixation in patients with and without RA and to find contributing factors. Forty-three patients who submitted to atlantoaxial transarticular screw fixation without any concomitant operation were followed up for more than 1 year. Subaxial subluxation and related radiological factors were evaluated by functional X-ray measurements. Statistical analyses showed that aggravations of subluxation of 2.5 mm or greater were more likely to occur in RA patients than in non-RA patients over an average of 4.2 years of follow-up, and postoperative subluxation occurred in the anterior direction in the upper cervical spine. X-ray evaluations revealed that such patients had a significantly smaller postoperative C2–C7 angle, and that the postoperative AA angle correlated negatively with this. Furthermore, anterior subluxation aggravation was significantly correlated with the perioperative atlantoaxial and C2–C7 angle changes, and these two changes were strongly correlated to each other. In conclusion, after atlantoaxial transarticular screw fixation, rheumatoid patients have a greater risk of developing subaxial subluxations. The increase of the atlantoaxial angel at the operation can lead to a decrease in the C2–C7 angle, followed by anterior subluxation of the upper cervical spine and possibly neurological deterioration. PMID:19337758

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

    Microsoft Academic Search

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

    1998-01-01

    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

  14. Salvage of failed osteosynthesis of an intracapsular fracture of the femoral neck using two cannulated compression screws and a vascularised iliac crest bone graft.

    PubMed

    Xiaobing, Y; Dewei, Z

    2015-07-01

    We evaluated the outcome of treatment of nonunion of an intracapsular fracture of the femoral neck in young patients using two cannulated screws and a vascularised bone graft. A total of 32 patients (15 women and 17 men, with a mean age of 36.5 years; 20 to 50) with failed internal fixation of an intracapsular fracture were included in the study. Following removal of the primary fixation, two cannulated compression screws were inserted with a vascularised iliac crest bone graft based on the ascending branch of the lateral femoral circumflex artery. At a mean follow-up of 6.8 years (4 to 10), union was achieved in 27 hips (84%). A total of five patients with a mean age of 40.5 years (35 to 50) had a persistent nonunion and underwent total hip arthroplasty as also did two patients whose fracture united but who developed osteonecrosis of the femoral head two years post-operatively. Statistical analysis showed that younger patients achieved earlier and more reliable union (p < 0.001). The functional outcome, as assessed by the Harris Hip score, was better in patients aged < 45 years compared with those aged > 45 years (p < 0.001). These findings suggest that further fixation using two cannulated compression screws and a vascularised iliac crest bone graft is an effective salvage treatment in patients aged < 45 years, in whom osteosynthesis of a displaced intracapsular fractures of the femoral neck has failed. Cite this article: Bone Joint J 2015; 97-B:988-91. PMID:26130357

  15. Mechanical properties of two canine iliac fracture fixation systems 

    E-print Network

    VanGundy, Thomas Eugene

    1988-01-01

    hemi- pelves with implants. The osteotomy was standardized and oblique simulating a common clinical fracture. Forty specimens were tested once to failure (static testing). Ten specimens were tested in torsional loading. Ten specimens were tested... for stiffness, strength and cross sectional area for specimen groups in each testing mode. 15 LIST OF FIGURES Figure Page Length and position of osteotomy in relation to the iliac isthmus. . . . . . . . Radiograph of paired implant specimens illustrating...

  16. Self-tapping versus standard tapped titanium screw fixation in the upper extremity.

    PubMed

    Bickley, M B; Hanel, D P

    1998-03-01

    Most screws used in fracture fixation necessitate a separate step for tapping of the screw hole. Titanium screw systems have been developed in which the screws can be inserted directly after a drill hole is made. These self-tapping screws thereby eliminate an operative step. A retrospective study was conducted that evaluated all wrist and hand procedures performed between January 1992 and December 1994 by 1 surgeon using screw fixation. The results of 39 cases treated with standard tapped titanium screws were compared with 28 cases treated with self-tapping titanium screws. Nearly identical union and complication rates were obtained in each group. Comparable results can be obtained with self-tapping screw fixation, which limits the number of instruments needed, eliminates an operative step, and thereby may diminish operative risk and shorten operative time. PMID:9556274

  17. Transarticular screw fixation for atlantoaxial instability - modified Magerl's technique in 38 patients

    Microsoft Academic Search

    Raj Bahadur; Tarun Goyal; Saravdeep S Dhatt; Sujit K Tripathy

    2010-01-01

    BACKGROUND: Symptomatic atlantoaxial instability needs stabilization of the atlantoaxial joint. Among the various techniques described in literature for the fixation of atlantoaxial joint, Magerl's technique of transarticular screw fixation remains the gold standard. Traditionally this technique combines placement of transarticular screws and posterior wiring construct. The aim of this study is to evaluate clinical and radiological outcomes in subjects of

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

    Microsoft Academic Search

    JA Abate; PD Fadale; MJ Hulstyn; WR Walsh

    1998-01-01

    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

  19. Biomechanical analysis of expansion screws and cortical screws used for ventral plate fixation on the cervical spine

    PubMed Central

    Ullrich, Bernhard; Huber, Gerd; Morlock, Michael M.

    2009-01-01

    Compared to bicortical screws, the surgical risk of injuring intraspinal structures can be minimized with the use of monocortical screws. However, this reduction should not be achieved at the expense of the stability of the fixation. With monocortical stabilization, the expansion screws have the potential of absorbing high loads. Therefore, they are expected to be a suitable alternative to bicortical screws for revision surgeries and in osteoporotic bone. The purpose of this in vitro study was to investigate the stiffness of the two screw-plate systems used for ventral stabilization of the cervical spine, by focusing on the suitability of expansion screws as tools for revision treatments. The study was conducted in ten functional units of human cervical spines. The device sample stiffness was determined for four conditions using a turning moment of 2.25 N m each around one of the three principle axes. The conditions were native, destabilized, primarily stabilized with one of the screw-plate systems, followed by secondary stabilization using the expansion screw implant. The stabilized samples achieved a comparable, in most cases higher stiffness than the native samples. The samples undergoing secondary stabilization using expansion screws tend to display greater stiffness for all three axes compared to the primarily stabilized samples. The achieved tightening moment of the screws was higher than the one achieved with primary fixation. Both plates revealed similar primary stability. Revision surgeries with secondary instrumentation achieve a high stiffness of the screwed up segments. Monocortical expansion screws combined with a trapezoidal plate allow ventral stabilization of the cervical spine that is comparable to the plate fixation using bicortical screws. PMID:19588171

  20. Bone cement or bone substitute augmentation of pedicle screws improves pullout strength in posterior spinal fixation

    Microsoft Academic Search

    S. L. Evans; C. M. Hunt; S. Ahuja

    2002-01-01

    Pedicle screws are widely used to fix posterior spinal implants. However, in some situations, such as at the ends of long constructs in scoliosis correction, the screws may pull out of the pedicles. This limits the use of pedicle screw fixation where bone quality is poor. The aim of this study was to investigate the effect of using either a

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

    PubMed Central

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

    2014-01-01

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

  2. Prevention of arthrofibrosis after arthroscopic screw fixation of tibial spine fracture in children and adolescents.

    PubMed

    Parikh, Shital N; Myer, David; Eismann, Emily A

    2014-01-01

    Arthrofibrosis is a major complication of tibial spine fracture treatment in children, potentially resulting in knee pain, quadriceps weakness, altered gait, decreased function, inability to return to sports, and long-term osteoarthritis. Thus, prevention rather than treatment of arthrofibrosis is desirable. The purpose of this study was to evaluate an aggressive postoperative rehabilitation and early intervention approach to prevent permanent arthrofibrosis after tibial spine fracture treatment and to compare epiphyseal and transphyseal screws for fixation. A consecutive series of 24 patients younger than age 18 with displaced type II and III tibial spine fractures who underwent arthroscopic reduction and screw fixation between 2006 and 2011 were retrospectively reviewed. Final range of motion was compared between patients with epiphyseal (n=12) and transphyseal (n=9) screws. One-third (4 of 12) of patients with epiphyseal screws underwent arthroscopic debridement and screw removal approximately 3 months postoperatively; 3 patients lacked 5° to 15° of extension, 1 experienced pain with extension, and 1 had radiographic evidence of screw pullout, loss of reduction, and resultant malunion. In the transphyseal screw group, 3 patients had 10° loss of extension, and all corrected after arthroscopic debridement and screw removal. The two groups did not significantly differ in time to hardware removal or return to sports or final range of motion. No growth disturbances were identified in patients after transphyseal screw removal. An aggressive approach of postoperative rehabilitation and early intervention after arthroscopic reduction and screw fixation of tibial spine fractures in children was successful in preventing permanent arthrofibrosis. PMID:24683658

  3. Serial lead impedance measurements confirm fixation of helical screw electrodes during pacemaker implantation.

    PubMed

    Roelke, M; Bernstein, A D; Parsonnet, V

    2000-04-01

    The purpose of this study was to determine whether serial measurements of helical screw pacemaker lead impedance could reliably confirm electrode fixation in the right atrium and right ventricle. Fixation is generally assessed fluoroscopically, which can be misleading because the myocardium is radiolucent. Alternatively, because the electrical conductivity of blood is greater than that of myocardium, serial measurements of the lead impedance might be expected to show an impedance increase with appropriate fixation of the pacemaker electrode when the electrode becomes embedded in myocardial tissue. Impedance measurements were made during the placement of 23 atrial and 28 ventricular active fixation electrodes in 31 consecutive patients. Impedance measurements were recorded in unipolar and bipolar electrode configurations with the electrode free floating in the chamber, unfixed (with exposed screws) but touching the endocardial surface, and after fixation. No significant impedance differences were found between free-floating and unfixed electrode positions. With fixation, the lead impedance increased significantly in the ventricle (P = 0.0001, unipolar and bipolar) and the atrium (P = 0.0069 unipolar and 0.0052 bipolar). Typical increases, reflected by median values, were 197 ohms unipolar and 203 ohms bipolar in the ventricle and 47 ohms unipolar and 53 ohms bipolar in the atrium for electrodes with permanently exposed or retractable screw designs. Comparing serial measurements of lead impedance before and after electrode fixation is a valid electrical method of confirming appropriate fixation of helical screw electrodes. PMID:10793439

  4. Microsurgical anterior decompression and internal fixation with iliac bone graft and titanium plates for treatment of cervical intervertebral disc herniation

    Microsoft Academic Search

    M. Miihlbauer; W. Saringer; M. Aichholzer; M. Sunder-Plassmann

    1995-01-01

    Summary 42 cervical interbody fusions with iliac bone graft and titanium plate fixation were performed between October 1991 and March 1994. The mean follow up period in this study was 10.7 months. In 32 cases fusion was done for 1 and in 10 cases for 2 segments. 2 different types of plates were used. In 25 cases micro-osteosynthesis plates and

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

    PubMed Central

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

    2013-01-01

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

  6. Refracture of proximal fifth metatarsal (Jones) fracture after intramedullary screw fixation in athletes.

    PubMed

    Wright, R W; Fischer, D A; Shively, R A; Heidt, R S; Nuber, G W

    2000-01-01

    This study details six instances of refracture of clinically and radiographically healed fractures of the base of the fifth metatarsal after intramedullary screw fixation. Four professional football players, one college basketball player, and one recreational athlete underwent intramedullary screw fixation of fifth metatarsal fractures. The athletes were released to full activities an average of 8.5 weeks (range, 5.5 to 12) after fixation, when healing was clinically and radiographically documented. Three football players developed refracture within 1 day of return to full activity. The other three athletes refractured at 2.5, 4, and 4.5 months after return to activity. Two football players underwent repeat fixation with larger screws and returned to play in the same season. The college basketball player underwent bone grafting and returned to play in subsequent seasons. The other three athletes underwent nonoperative management and healed uneventfully over 6 to 8 weeks. On the basis of this series, we recommend that 1) screw fixation using a large-diameter screw should be given careful consideration for patients with large body mass for whom early return to activity is important; 2) functional bracing, shoe modification, or an orthosis should be considered for return to play; 3) if refracture occurs, exchange to a larger screw may allow return to play in the same season; and 4) alternative imaging should be considered to help document complete healing. PMID:11032233

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

    PubMed

    Huang, Weijie; Luo, Tao

    2013-03-01

    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

  8. Bioabsorbable Versus Metallic Screw Fixation for Tibiofibular Syndesmotic Ruptures: A Meta-Analysis.

    PubMed

    van der Eng, Dorien M; Schep, Niels W L; Schepers, Tim

    2015-01-01

    Ankle fractures with syndesmotic rupture require operative treatment. In most cases, this consists of fixation of the tibiofibular joint with 1 or more screws. Bioabsorbable screws are used for the same purpose but have the advantage that screw removal is unnecessary. The aim of the present study was to compare the results of bioabsorbable and metallic syndesmotic screws. A systematic search was performed in the Ovid MEDLINE electronic database and Google Scholar. Three randomized controlled trials and one comparison study, with 260 patients, were included. The experimental group consisted of patients with syndesmotic injuries treated with bioabsorbable screws versus the control group (patients treated with metallic screws). The primary outcomes were complications and wound infections. No statistically significant difference was demonstrable in the overall number of complications between the 2 groups. In the group of patients with a bioabsorbable screw, 32 of 137 (23.4%) experienced a complication versus 7 of 123 patients (5.7%) with a metallic screw. Data on wound-related complications showed no statistically significant difference, 19.7% versus 5.7%. The average maximum range of motion in both groups was comparable. Bioabsorbable syndesmotic screws and metallic syndesmotic screws were comparable with respect to the incidence of complications and range of motion. However, the absolute number of complications was greater with bioabsorbable screws. PMID:25960058

  9. Fracture risk and initial fixation of a cementless glenoid implant: the effect of numbers and types of screws.

    PubMed

    Suarez, Daniel R; Valstar, Edward R; Rozing, Piet M; van Keulen, Fred

    2013-10-01

    The initial fixation of an anatomical cementless glenoid component, provided by different numbers and types of screws, and the risk of bone fracture were evaluated by estimating the bone-implant interface micromotions and the principal strains around the prosthesis. Four different fixation configurations using locking or compression screws were tested. Estimation of the micromotions at the bone-implant interface was performed both experimentally, using an in vitro model, and computationally, using a numerical model. Principal bone strains were estimated using the numerical model. Subject variability was included by modelling two different bone qualities (healthy and rheumatoid bone). For the fixation configurations that used two screws, experimental and modelling results found that the micromotions at the bone-implant interface did not change with screw type. However, screw type had a significant effect on fixation when only one screw was used; in this case, a locking screw resulted in less micromotion at the bone-implant interface compared with the compression screw. Bone strains were predicted by the numerical model, and strains were found to be independent of the screw type; however, the predicted strain levels calculated in rheumatoid bone were larger than the strain levels that may cause bone damage for most considered arm positions. Predicted bone strain in healthy bone did not reach this level. While proper initial component fixation that allows biological fixation can be achieved by using additional screws, the risk of bone failure around the screws must be considered, especially in cases of weak bone. PMID:23804951

  10. Implant failure in a proximal femoral fracture treated with dynamic hip screw fixation

    PubMed Central

    Dabis, John; Abdul-Jabar, Hani B.; Dabis, Hosam

    2015-01-01

    Dynamic hip screw fixation is a common orthopaedic procedure and to date, still can cause difficulties to the senior trauma surgeon. We present a case where an extra-capsular fracture of the proximal femur was managed with a dynamic hip screw (DHS) fixation. She proceeded to the operating theatre, where the fracture was stabilized with a 75-mm DHS and short-barrelled plate. The implant position was checked with intraoperative screening and the position accepted. Following attempted mobilization at 11 days post-operatively, the patient developed a recurrence of her preoperative pain. X-ray showed that the implant screw had separated from the barrel. Later scrutiny of the intraoperative screening films revealed that the barrel and screw were not engaged at the time of surgery. Intraoperative screening films should be carefully checked to ensure congruity of implant components. PMID:26136561

  11. Implant failure in a proximal femoral fracture treated with dynamic hip screw fixation.

    PubMed

    Dabis, John; Abdul-Jabar, Hani B; Dabis, Hosam

    2015-01-01

    Dynamic hip screw fixation is a common orthopaedic procedure and to date, still can cause difficulties to the senior trauma surgeon. We present a case where an extra-capsular fracture of the proximal femur was managed with a dynamic hip screw (DHS) fixation. She proceeded to the operating theatre, where the fracture was stabilized with a 75-mm DHS and short-barrelled plate. The implant position was checked with intraoperative screening and the position accepted. Following attempted mobilization at 11 days post-operatively, the patient developed a recurrence of her preoperative pain. X-ray showed that the implant screw had separated from the barrel. Later scrutiny of the intraoperative screening films revealed that the barrel and screw were not engaged at the time of surgery. Intraoperative screening films should be carefully checked to ensure congruity of implant components. PMID:26136561

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

    SciTech Connect

    Jacob, Augustinus Ludwig [Kantonsspital-Universitaetskliniken, Institute of Diagnostic Radiology (Switzerland); Messmer, Peter [Kantonsspital-Universitaetskliniken, Department of Surgery (Switzerland); Stock, Klaus-Wilhelm [Kantonsspital-Universitaetskliniken, Institute of Diagnostic Radiology (Switzerland); Suhm, Norbert [Kantonsspital-Universitaetskliniken, Department of Surgery (Switzerland); Baumann, Bernard [Kantonsspital-Universitaetskliniken, Institute of Diagnostic Radiology (Switzerland); Regazzoni, Pietro [Kantonsspital-Universitaetskliniken, Department of Surgery (Switzerland); Steinbrich, Wolfgang [Kantonsspital-Universitaetskliniken, Institute of Diagnostic Radiology (Switzerland)

    1997-07-15

    Purpose. To assess the midterm results of closed reduction and percutaneous fixation (CRPF) with computed tomography (CT)-guided sacroiliac screw fixation in longitudinal posterior pelvic ring fractures. Methods. Thirteen patients with 15 fractures were treated. Eleven patients received a unilateral, two a bilateral, screw fixation. Twenty-seven screws were implanted. Continuous on-table traction was used in six cases. Mean radiological follow-up was 13 months. Results. Twenty-five (93%) screws were placed correctly. There was no impingement of screws on neurovascular structures. Union occurred in 12 (80%), delayed union in 2 (13%), and nonunion in 1 of 15 (7%) fractures. There was one screw breakage and two axial dislocations. Conclusion. Sacroiliac CRPF of longitudinal fractures of the posterior pelvic ring is technically simple, minimally invasive, well localized, and stable. It should be done by an interventional/surgical team. CT is an excellent guiding modality. Closed reduction may be a problem and succeeds best when performed as early as possible.

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

    PubMed

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

    2015-02-01

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

  14. Use of self-tapping metal screws for temporary fixation of a resorbable plate system in maxillofacial surgery.

    PubMed

    Iwai, Toshinori; Omura, Susumu; Aoki, Noriaki; Tohnai, Iwai

    2015-05-01

    Resorbable plate systems have been used in maxillofacial surgery to obviate the need for plate removal. However, resorbable plates and screws are very costly, and refixation with additional screws may be necessary when reduction or repositioning of the bone segment is inaccurate. Here we report the use of self-tapping metal screws for temporary fixation of a resorbable plating system in maxillofacial surgery to avoid the use of additional screws following inaccurate fixation or the reuse of resorbable screws, which may result in loosening. PMID:25974798

  15. Screw fixation of an OCD loose body: 21-year results.

    PubMed

    Cvetanovich, Gregory L; Mall, Nathan A; Van Thiel, Geoffrey S; Chahal, Jaskarndip; Bach, Bernard

    2013-12-01

    Osteochondritis dissecans (OCD) lesions can progress to loose body formation for which treatment is controversial and may involve excision or fixation. There is a paucity of published data regarding long-term outcomes following OCD loose body fixation. This case report presents an interval follow-up of a patient from a previous small case series of individuals who underwent open reduction internal fixation of large, lateral OCD loose bodies. At 21-year follow-up the patient has full, pain-free range of motion, and has not required subsequent surgery. This case, to our knowledge, is the first to report over 20-year follow-up from fixation of an OCD loose body and demonstrates a good long-term outcome. Clinicians should consider replacement and fixation of an OCD loose body when possible, as this may provide the best chance of long-term function. PMID:23288769

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

    PubMed Central

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

    2008-01-01

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

  17. The biomechanics of interference screw fixation of patellar tendon anterior cruciate ligament grafts

    Microsoft Academic Search

    Charles H. Brown; Aaron T. Hecker; John A. Hipp; Elizabeth R. Myers; Wilson C. Hayes

    1993-01-01

    Twenty-seven paired human cadaveric knee specimens were used to determine the effect of surgical technique and various interference screw parameters on the pullout strength of patellar tendon femoral bone blocks. The study compared the fixation strength of endoscop ically inserted and conventional \\

  18. Short segment screw fixation without fusion in treatment for unstable thoracolumbar burst fracture

    PubMed Central

    Tang, Jiaguang; Liu, Yishan; Cao, Zheng; Hu, Yuan; Lu, Xiang; Lin, Bin

    2014-01-01

    This study aims to evaluate clinical efficacy of short segment pedicle screw fixation without bone fusion for unstable thoracolumbar burst fracture. Nineteen patients younger than 40 years old with unstable thoracolumbar burst fractures were included. The surgical procedure included postural reduction for 3 days and screw fixations at one level above, one level below and at the fractured level itself. The implants were removed 12 months after initial operation. Imaging and clinical findings were analyzed at preoperative, 12 months after surgery, just before implant removal, and at six months after implant removal. Results indicated that difference was statistically significant between preoperative period or postoperative 1 year follow-up, just before implant removal and 6 months after implant removal (P < 0.05). Results at postoperative 1 year follow-up, just before implant removal and 6 months after implant removal were better than preoperative period. There were no significant complications or neurological deterioration after screws insert and removal in any patient. The rate of clinical outcome with excellent and good was 94.7%. In conclusion, short segment pedicle screw fixation without bone fusion can be an effective and safe operative srategytechnique in the management of young patients suffering from unstable burst fracture. PMID:25664090

  19. Use of C2 spinous process screw for posterior cervical fixation as substitute for laminar screw in a patient with thin laminae

    PubMed Central

    Nagata, Kosei; Baba, Satoshi; Chikuda, Hirotaka; Takeshita, Katsushi

    2013-01-01

    Rigid screw fixation of C2 including transarticular screw and pedicle screw contain the risk of vertebral artery (VA) injury. On the other hand, translaminar screws are considered to be safer for patients with anomalous VA. But C2 translaminar screw placement was limited in patients who have thin laminas and there is marked variation in C2 laminar thickness. Appropriate C2 fixation method for a patient who has thin laminas and high-riding VA together was controversial. Here, we present a case of an elderly Asian woman who had thin laminas and high-riding VA together with progressive myelopathy to report a first case of C2 spinous process screw insertion. Although the stability and safety of C2 spinous process screw was reported in cadaver series, there was no clinical report to our knowledge. Spinous process screw can be an option of C2 fixation for patients with high-riding VA and severe degenerated cervical spines including thin C2 laminas. PMID:23814004

  20. Anti-RANKL treatment improves screw fixation in cancellous bone in rats.

    PubMed

    Bernhardsson, Magnus; Sandberg, Olof; Aspenberg, Per

    2015-06-01

    Bisphosphonates improve implant fixation in randomised clinical trials of knee prostheses, hip prostheses and dental implants. However, a limited amount of bone resorption is required for bisphosphonates to exert an effect. Anti-RANKL treatment does not have this limitation, and we therefore tested whether if they might be more effective for improvement of implant fixation. This is of interest, as anti-RANKL treatment with denosumab is now in common clinical use. Male SD rats received a stain-less steel screw in the right proximal tibia and a drill hole in the left (n=42). They were randomised to subcutaneous injections of either alendronate (20?g/kg/day), alendronate (200?g/kg/day), osteoprotegerin with an Fc tag (OPG-Fc; 8mg/kg, twice weekly), or saline control. After 4 weeks, the fixation of the steel screw was measured by pull-out test. The tibia with the drill hole was evaluated with ?CT. OPG-Fc increased the pull-out force compared to saline controls by 153% (p<0.001). There was no significant difference between OPG-Fc and the alendronate groups. OPG-Fc increased the bone density (BV/TV) in the previous drill hole compared to controls 7-fold (p<0.001). This increase was higher than with any alendronate dose (p<0.001). OPG-Fc increased the bone density of the L5 vertebral body, but there was no significant difference between OPG-Fc and alendronate. Our results suggest that screw fixation in cancellous bone can be dramatically improved by an anti-RANKL agent. The effect was comparable to very high bisphosphonate doses. Screw insertion in cancellous bone elicits a metaphyseal fracture healing response, and our findings might be relevant not only for implant fixation, but also for fracture healing in cancellous bone. PMID:25744169

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

    PubMed Central

    Rai, Deepak K; Kannampilly, Antony J

    2014-01-01

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

  2. Cement Embolism into the Venous System after Pedicle Screw Fixation: Case Report, Literature Review, and Prevention Tips

    PubMed Central

    Kerry, Ghassan; Ruedinger, Claus; Steiner, Hans-Herbert

    2013-01-01

    The strength of pedicle screws attachment to the vertebrae is an important factor affecting their motion resistance and long term performance. Low bone quality, e.g. in osteopenic patients, keeps the screw bone interface at risk for subsidence and dislocation. In such cases, bone cement could be used to augment pedicle screw fixation. But its use is not free of risk. Therefore, clinicians, especially spine surgeons, radiologists, and internists should become increasingly aware of cement migration and embolism as possible complications. Here, we present an instructive case of cement embolism into the venous system after augmented screw fixation with fortunately asymptomatic clinical course. In addition we discuss pathophysiology and prevention methods as well as therapeutic management of this potentially life-threatening complication in a comprehensive review of the literature. However, only a few case reports of cement embolism into the venous system were published after augmented screw fixation. PMID:24191184

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

    SciTech Connect

    Mendez, Jose C. [Hospital Virgen de la Salud, Avda., Department of Neuroradiology (Spain)], E-mail: jmendezce@hotmail.com; Gonzalez-Llanos, Francisco [Hospital Virgen de la Salud, Avda., Deparment of Neurosurgery (Spain)

    2005-01-15

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

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

    PubMed Central

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

    2014-01-01

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

  5. Mandibular fractures treated with maxillomandibular fixation screws (MMFS method).

    PubMed

    Imazawa, Takashi; Komuro, Yuzo; Inoue, Masahiro; Yanai, Akira

    2006-05-01

    The purpose of the treatment of mandibular fractures is to restore proper dental occlusion and stable temporomandibular joint movement, as well as the reduction of the displaced fracture. Consideration must be given to the selection of the most appropriate surgical and rehabilitation methods in such patients. Typical surgical methods for the treatment of mandibular fractures include the arch bar method or plating at the location of the fracture combined with fixing the mandible to the maxilla using the arch bar method. However arch bars and circumdental wires, which require teeth for fixation, damage teeth and periodontal tissue, and tend to be uncomfortable for patients during the fixation period. Moreover, daily maintenance of oral hygiene is difficult for patients with an arch bar. Surgeons are also exposed to the risk of blood-transmitted diseases through skin punctures by wires when affixing these devices. For these reasons, we chose to study the potential of the MMFS method, which is thought to lessen all of the following problems: tissue damage, operating time, patient discomfort, and possible exposure to percutaneous infectious disease due to puncture of gloves and skin by the wires. We demonstrated the utility of the MMFS method in the present study. PMID:16770195

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

    PubMed Central

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

    2013-01-01

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

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

    PubMed

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

    1998-03-01

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

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

    PubMed Central

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

    2009-01-01

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

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

    PubMed

    Malik, Mudasir; Halwai, Manzoor Ahmad

    2014-10-01

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

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

    NASA Astrophysics Data System (ADS)

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

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

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

    NASA Astrophysics Data System (ADS)

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

    2008-09-01

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

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

    PubMed Central

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

    2015-01-01

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

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

    PubMed Central

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

    2015-01-01

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

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

    PubMed Central

    2011-01-01

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

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

    PubMed Central

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

    2014-01-01

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

  16. Minimally invasive percutaneous screw fixation of traumatic spondylolisthesis of the axis.

    PubMed

    Buchholz, Avery Lee; Morgan, Steven L; Robinson, Leslie C; Frankel, Bruce M

    2015-05-01

    OBJECT Most cases of traumatic spondylolisthesis of the axis (hangman's fracture) can be treated nonoperatively with reduction and subsequent immobilization in a rigid cervical collar or halo. However, in some instances, operative management is necessary and can be accomplished by using either anterior or posterior fusion techniques. Because open posterior procedures can result in significant blood loss, pain, and limited cervical range of motion, other less invasive options for posterior fixation are needed. The authors describe a minimally invasive, navigation-guided technique for surgical treatment of Levine-Edwards (L-E) Type II hangman's fractures. METHODS For 5 patients with L-E Type II hangman's fracture requiring operative reduction and internal fixation, percutaneous screw fixation directed through the fracture site was performed. This technique was facilitated by use of intraoperative 3D fluoroscopy and neuronavigation. RESULTS Of the 5 patients, 2 were women, 3 were men, and age range was 46-67 years. No intraoperative or postoperative complications occurred. All patients wore a rigid cervical collar, and flexion-extension radiographs were obtained at 6 months. For all patients, dynamic imaging demonstrated a stable construct. CONCLUSIONS L-E type II hangman's fractures can be safely repaired by using percutaneous minimally invasive surgical techniques. This technique may be appropriate, depending on circumstances, for all L-E Type I and II hangman's fractures; however, the degree of associated ligament injury and disc disruption must be accounted for. Percutaneous fixation is not appropriate for L-E Type III fractures because of significant displacement and ligament and disc disruption. This report is meant to serve as a feasibility study and is not meant to show superiority of this procedure over other surgical options. PMID:25723118

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

    PubMed Central

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

    2014-01-01

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

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

    PubMed Central

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

    2013-01-01

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

  19. Transarticular screw fixation of C1-2 for the treatment of arthropathy-associated occipital neuralgia.

    PubMed

    Pakzaban, Peyman

    2011-02-01

    Two patients with occipital neuralgia due to severe arthropathy of the C1-2 facet joint were treated using atlantoaxial fusion with transarticular screws without decompression of the C-2 nerve root. Both patients experienced immediate postoperative relief of occipital neuralgia. The resultant motion elimination at C1-2 eradicated not only the movement-evoked pain, but also the paroxysms of true occipital neuralgia occurring at rest. A possible pathophysiological explanation for this improvement is presented in the context of the ignition theory of neuralgic pain. This represents the first report of C1-2 transarticular screw fixation for the treatment of arthropathy-associated occipital neuralgia. PMID:21214317

  20. Placement of occipital condyle screws for occipitocervical fixation in a pediatric patient with occipitocervical instability after decompression for Chiari malformation.

    PubMed

    Bekelis, Kimon; Duhaime, Ann-Christine; Missios, Symeon; Belden, Clifford; Simmons, Nathan

    2010-08-01

    In cadaveric studies and recently in one adult patient the occipital condyle has been studied as an option to allow bone purchase by fixation devices. In the current case the authors describe the use of occipital condyle screws in a child undergoing occipitocervical fixation. To the best of the authors' knowledge this case is the first reported instance of this technique in a pediatric patient. This girl had a history of posterior fossa decompression for Chiari malformation Type I when she was 22 months of age. When she was 6 years old she presented with neck pain on flexion and extension of her head. Magnetic resonance imaging in flexion and extension revealed occipitocervical instability. She underwent an occiput to C-2 posterior arthrodesis with bilateral screw placement in the occipital condyles, C-2 lamina, and C-1 lateral masses. Postoperatively, she was neurologically intact. Computed tomography demonstrated a stable construct, and her cervical pain had resolved on follow-up. PMID:20672939

  1. Effect of Crosslinks on the Stability of the Spine and the Pedicle Screw Fixation.

    PubMed

    Xiang-Yu, Zhang; Feng, S U; Shi, Yan; Zhi-Min, Zhang; Pei-Nan, Zhang

    2015-06-30

    Objective To evaluate the effect of crosslinks on the stability of the spine and pedicle screws. Methods Compression fracture of the L1 vertebra was produced in 30 fresh thoracic and lumbar vertebrae samples obtained from adult sheep,which were divided into 3 groups(n=10)with lot-drawing method. Four screws were fixed onto the superior and inferior pedicles of vertebral arch close to the fractured vertebrae,with different number of crosslinks(0 in Group A,1 in Group B,and 2 in Group C)on the rods. After fixation,the samples were subject to 10 000 times of fatigue test with 1.5 Hz load on the HY-3080 computer-control electronic universal test machine and HY-1000NM computer-control torsion test machine. The axial compressive stiffness,maximum pullout strength,and range of motion(ROM)of 6 directions,i.e.,flexion,extension,left and right lateral bending,and left and right axial rotation of the 3 groups were measured and compared. Results There were no statistically significant differences in axial compressive stiffness as well as the ROM of flexion,extension,and left and right lateral bending(all P>0.05). The maximum pullout strength was significantly smaller in Group A and Group B than in Group C [(129.56±29.63)N vs.(294.67±23.25)N,P=0.000;(254.02±36.29)vs.(294.67±23.25)N,P=0.006]. The ROM of left axial rotation was the highest in Group A(13.35°±1.06°),followed by Group B(12.23°±1.06°)and Group C(11.04°±0.74°)(F=13.44,P=0.000;Group B vs. Group A,P=0.000;Group B vs. Group C,P=0.001;Group C vs. Group A,P=0.000). The ROM of right axial rotation was also the highest in Group A(13.56°±1.15°),lower in Group B(12.39°±1.01°)and the lowest in Group C(10.81°±0.51°)(F=21.91,P=0.000;Group B vs. Group A,P=0.002;Group B vs. Group C,P=0.001;Group C vs. Group A,P=0.000). Conclusion Crosslinks may reinforce the pullout strength of the screws and improve the axial stability of the spine. PMID:26149138

  2. Anterior transpedicular screw fixation of cervical spine: Is it safe? Morphological feasibility, technical properties, and accuracy of manual insertion.

    PubMed

    Koktekir, Ender; Toktas, Zafer Orkun; Seker, Askin; Akakin, Akin; Konya, Deniz; Kilic, Turker

    2015-06-01

    OBJECT Due to lack of construct stability of the current anterior cervical approaches, supplemental posterior cervical approaches are frequently employed. The use of an anterior-only approach with anterior transpedicular screws (ATPSs) has been proposed as a means of providing 3-column fixation. This study was designed to investigate the feasibility of anterior transpedicular screw (ATPS) fixation of cervical spine, to obtain the morphological measurements for technical prerequisites, and to evaluate the accuracy of the ATPS using fluoroscopy. METHODS The study included both radiological and anatomical investigations. The radiological investigations were based on data from cervical spine CT scans performed in 65 patients. Technical prerequisites of ATPS were calculated using OsiriX for Mac OS. In the anatomical part of the study, 30 pedicles (C3-7) from 6 formalin-preserved cadavers were manually instrumented. Measurements obtained included pedicle width (PW), pedicle height (PH), pedicle transverse angle (PTA), distance of the entry point from the midline (DEPM), and distance of the entry point from the superior endplate (DEPSEP). The authors also analyzed screw position in the manually instrumented vertebrae. RESULTS The mean PW and PH values showed a tendency to increase from C-3 to C-7 in both males and females. The means were significantly larger for both PW and PH in males than in females at all levels (p = 0.001). The overall mean PTA value was significantly lower at C-7 (p < 0.0001). The mean value for the distance of entry point from the midline (DEPM) represented a point at the contralateral side of the pedicle for every level except C-7. The mean DEPSEP values showed significant differences between all levels (p < 0.0001). Seven of the 30 screws were identified as breaching the pedicle (23.3%); these screw malplacements were seen at C-3 (3 screws), C-4 (2 screws), and C-5 (2 screws). CONCLUSIONS The morphological measurements of this study demonstrated that ATPS fixation is feasible in selected cases. They indicate that ATPS insertion using a fluoroscopy-assisted pedicle axis view is safe at the C-6 and C-7 levels, but the results at the other levels did not prove the safety of this technique. PMID:25815805

  3. Titanium-alloy enhances bone-pedicle screw fixation: mechanical and histomorphometrical results of titanium-alloy versus stainless steel

    Microsoft Academic Search

    Finn Bjarke Christensen; Michel Dalstra; Flemming Sejling; Søren Overgaard; Cody Bünger

    2000-01-01

    Several types of pedicle screw systems have been utilized to augment lumbar spine fusion. The majority of these systems are\\u000a made of stainless steel (Ss), but titanium-alloy (Ti-alloy) devices have recently been available on the market. Ti-alloy implants\\u000a have several potential advantages over Ss ones. High bioactivity and more flexibility may improve bone ingrowth and mechanical\\u000a fixation, and the material

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

    PubMed

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

    2011-11-01

    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

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

    PubMed

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

    2015-05-01

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

  6. Simulation-based particle swarm optimization and mechanical validation of screw position and number for the fixation stability of a femoral locking compression plate.

    PubMed

    Lee, Chian-Her; Shih, Kao-Shang; Hsu, Ching-Chi; Cho, Tomas

    2014-01-01

    Locking compression plates (LCPs) have been used to fix femoral shaft fractures. Previous studies have attempted to identify the best LCP screw positions and numbers to achieve the fixation stability. However, the determined screw positions and numbers were mainly based on the surgeons' experiences. The aim of this study was to discover the best number and positions of LCP screws to achieve acceptable fixation stability. Three-dimensional numerical models of a fractured femur with the LCP were first developed. Then, the best screw position and number of LCPs were determined by using a simulation-based particle swarm optimization algorithm. Finally, the results of the numerical study were validated by conducting biomechanical tests. The results showed that the LCP with six locking screws resulted in the necessary fixation stability, and the best combination of positions of locking screws inserted into the LCP was 1-5-6-7-8-12 (three locking screws on either side of the bone fragment with two locking screws as close as practicable to the fracture site). In addition, the numerical models and algorithms developed in this study were validated by the biomechanical tests. Both the numerical and experimental results can provide clinical suggestions to surgeons and help them to understand the biomechanics of LCP systems. PMID:24090880

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

    PubMed Central

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

    2015-01-01

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

  8. Interference Screw Fixation of Soft Tissue Grafts in Anterior Cruciate Ligament Reconstruction: Part 1Effect of Tunnel Compaction by Serial Dilators Versus Extraction Drilling on the Initial Fixation Strength

    Microsoft Academic Search

    Janne T. Nurmi; Pekka Kannus; Harri Sievänen; Timo Järvelä; Markku Järvinen; Teppo L. N. Järvinen

    2004-01-01

    Background:Compaction of the bone-tunnel walls by serial dilation is believed to enhance the interference screw fixation strength of the soft tissue grafts in anterior cruciate ligament (ACL) reconstruction.Hypothesis:Serial dilation enhances the fixation strength of soft tissue grafts in ACL reconstruction over extraction drilling.Study Design:Randomized experimental study.Methods:Initial fixation strength of the doubled anterior tibialis tendon grafts (fixed with a bioabsorbable interference

  9. Three-dimensional image navigation system-assisted anterior cervical screw fixation for treatment of acute odontoid fracture

    PubMed Central

    Zou, Debo; Zhang, Kaining; Ren, Yanjun; Wu, Yingguang; Yang, Yun; Li, Yu

    2014-01-01

    This study is to investigate the role of three-dimensional image navigation system for surgical treatment of odontoid fracture. A total of 21 patients were enrolled in this study. The anterior cervical hollow screw fixation was performed for treatment of acute odontoid fracture under monitoring of isocentric C-arm three-dimensional navigation system (Iso-C 3D) navigation system. The postoperative follow-up investigation duration was 13.8 ± 4.4 months. Twenty patients with odontoid fracture had bone union without intraoperative and postoperative complications. No loosening, dislocation or fracture of screw occurred. The average healing time was from 3 to 4 months. The cervical postoperative organ function evaluation of patients was scored by Smiley-Webster scoring methods. Eighteen cases were scored as excellent; 2 cases were scored as fine; 1 case was scored as good; and no case was scored as poor. Iso-C 3D image navigation system-assisted anterior cervical screw fixation is an effective approach for treatment of odontoid fracture. PMID:25550950

  10. Subsidence of metal interbody cage after posterior lumbar interbody fusion with pedicle screw fixation.

    PubMed

    Tokuhashi, Yasuaki; Ajiro, Yasumitsu; Umezawa, Natsuki

    2009-04-01

    Posterior lumbar interbody fusion is considered to be an excellent fusion procedure to stabilize anterior support, correct alignment in the sagittal and coronal plane, and achieve foraminal decompression by lifting the disk height. The metal interbody cage in posterior lumbar interbody fusion is thought to be useful to prevent collapse of the graft bone and to correct and maintain disk height; however, some studies have noted a gradual decrease of disk height due to cage subsidence. Therefore, to investigate the significance of cage subsidence, 86 disk levels radiographically confirmed to have good union in 66 patients with posterior lumbar interbody fusion combined with pedicle screw fixation and a single metal cage for degenerative lumbar disease were retrospectively evaluated. The follow-up period ranged from 3 years to 10 years 3 months, with a mean of 7 years 9 months. Cage subsidence often showed a gradual increase over time. At final follow-up, subsidence averaged 4.0 mm on the cranial surface and 2.7 mm on the caudal surface. Although the average increase of disk height was 3.2 mm immediately postoperatively, the final disk height decreased by 4.2 mm on average from that time. The degree of cage subsidence and decrease of disk height were not correlated with the final clinical results. Subsidence was not correlated with bone mineral density in the vertebral body, body weight, or site of the insertion. On the other hand, the wedge shape of the cage and the thickness of the resected endplate had a significant influence on cage subsidence. PMID:19388615

  11. Comparison of the tissue response to absorbable self-reinforced polylactide screws and metallic screws in the fixation of cancellous bone osteotomies: an experimental study on the rabbit distal femur.

    PubMed

    Viljanen, J T; Pihlajamäki, H K; Törmälä, P O; Rokkanen, P U

    1997-05-01

    The availability of absorbable fracture-fixation devices for clinical use calls for better knowledge of the reaction of bone tissue to absorbable polyester implants as compared with similar metallic devices. To examine and compare the tissue response to biodegradable and metallic screws within cancellous bone, a transverse transcondylar osteotomy of the distal femur was fixed with absorbable self-reinforced polylevolactide screws in 35 rabbits and with stainless-steel screws in 35 rabbits. New bone formation and consolidation of the osteotomy were examined histologically, histomorphometrically, and microradiographically within standardized sample fields 1, 3, 6, 12, 24, 36, and 48 weeks postoperatively. The intact contralateral femur served as the control. A vigorous osteoconductive response to the polylevolactide screws was observed at 3 weeks postoperatively, and the osteoid surface fraction was significantly higher in all follow-ups than in the contralateral femora. In the femora with metallic screws, new bone formation was seen 3, 6, and 12 weeks postoperatively, but at 24, 36, and 48 weeks the osteoid surface fraction did not differ significantly from that of the intact control femora. The total bone area was significantly larger in the femora with self-reinforced polylevolactide screws than in the control bone 6-48 weeks postoperatively; in the femora with metallic screws, this was found only at 6 and 12 weeks. After 48 weeks, the femora fixed with metallic screws had statistically smaller total bone area than the intact control femora. Solid bone union was seen in 84% of the osteotomies in the self-reinforced polylevolactide group and in 76% of those in the metallic group after 3 weeks or more. No signs of degradation of the self-reinforced polyleuolactide implant and only a mild foreign-body reaction with no accumulations of inflammatory cells to either self-reinforced polylevolactide or metallic screws were observed during the follow-up period. Both types of screws seemed to induce an osteostimulatory response around their threads. This phenomenon was transient for metallic screws but lasted for at least 48 weeks for self-reinforced polylevolactide screws. The polylevolactide screw does not seem to cause osteopenia at the implantation site. The fixation properties of both self-reinforced polylevolactide screws and metallic screws appear to be sufficient for the fixation of small fragments of cancellous bone. PMID:9246086

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

    PubMed Central

    Haque, Mohammod Raziul

    2014-01-01

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

  13. A single-stage posterior approach with open reduction and pedicle screw fixation in subaxial cervical facet dislocations.

    PubMed

    Park, Jin Hoon; Roh, Sung Woo; Rhim, Seung Chul

    2015-07-01

    OBJECT The optimal treatment for cervical facet dislocations is controversial, but the generally accepted process recommends an initial closed reduction with the next step determined according to the success of the closed reduction and the presence of traumatic disc herniation. This study aimed to show the efficacy of a posterior approach performed with an open reduction and pedicle screw fixation with removal of disc particles, if required, in the management of subaxial cervical dislocations. METHODS Between March 2012 and September 2013, 21 consecutive patients with cervical facet dislocations were enrolled. The affected levels were as follows: 4 at C3-4; 2 at C4-5; 5 at C5-6; and 10 at the C6-7 level. Seven patients had traumatic disc herniations. Closed reduction was not attempted; a prompt posterior cervical surgery was performed instead. After open reduction, pedicle screw fixation was performed. In cases with traumatic disc herniation, herniated disc fragments were excised via a posterolateral approach and successful decompressions were determined by postoperative MRI studies. Clinical outcomes were assessed using the American Spinal Injury Association (ASIA) grading system. Radiological outcomes were assessed by comparing the degree of subluxation and the angle of segmental lordosis between pre- and postoperative CT scans. RESULTS All patients improved neurologically. The mean segmental angles improved from 7.3° ± 8.68° to -5.9° ± 4.85°. The mean subluxation improved from 23.4% ± 16.52% to 2.6% ± 7.19%. Disc fragments were successfully removed from the 7 patients with herniated discs, as shown on MRI. CONCLUSIONS Open reduction followed by pedicle screw fixation or posterolateral removal of herniated disc fragments is a good treatment option for cervical facet dislocations. PMID:25909272

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

    PubMed Central

    2014-01-01

    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

  15. 3D Mapping of Safe and Danger Zones in the Maxilla and Mandible for the Placement of Intermaxillary Fixation Screws

    PubMed Central

    Purmal, Kathiravan; Alam, Mohammad Khursheed; Pohchi, Abdullah; Abdul Razak, Noor Hayati

    2013-01-01

    Intermaxillary (IMF) screws feature several advantages over other devices used for intermaxillary fixation, but using cone beam computed tomography (CBCT) scans to determine the safe and danger zones to place these devices for all patients can be expensive. This study aimed to determine the optimal interradicular and buccopalatal/buccolingual spaces for IMF screw placement in the maxilla and mandible. The CBCT volumetric data of 193 patients was used to generate transaxial slices between the second molar on the right to the second molar on the left in both arches. The mean interradicular and buccopalatal/buccolingual distances and standard deviation values were obtained at heights of 2, 5, 8 and 11 mm from the alveolar bone crest. An IMF screw with a diameter of 1.0 mm and length of 7 mm can be placed distal to the canines (2 - 11 mm from the alveolar crest) and less than 8 mm between the molars in the maxilla. In the mandible, the safest position is distal to the first premolar (more than 5 mm) and distal to the second premolar (more than 2 mm). There was a significant difference (p<0.05) between the right and left quadrants. The colour coding 3D template showed the safe and danger zones based on the mesiodistal, buccopalatal and buccolingual distances in the maxilla and mandible.The safest sites for IMF screw insertion in the maxilla were between the canines and first premolars and between the first and second molars. In the mandible, the safest sites were between the first and second premolars and between the second premolar and first molar. However, the IMF screw should not exceed 1.0 mm in diameter and 7 mm in length. PMID:24367643

  16. Continued growth of the hip after fixation of slipped capital femoral epiphysis using a single cannulated screw with a proximal threading

    Microsoft Academic Search

    Frédéric Sailhan; Aurélien Courvoisier; Océane Brunet; Franck Chotel; Jérôme Berard

    2011-01-01

    Background  The most commonly used method for unstable slipped capital femoral epiphysis (SCFE) remains in situ fixation. Depending on\\u000a the surgeon’s preference, screws or Kirschner wires are used for stabilizing the slipped upper femoral epiphysis. The purpose\\u000a of this study was to evaluate the ability of a single cannulated screw with a proximal threading to ensure stabilization,\\u000a growth, and remodeling of

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

    PubMed Central

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

    2014-01-01

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

  18. Biodegradable wire fixation in olecranon and patella fractures combined with biodegradable screws or plugs and compared with metallic fixation

    Microsoft Academic Search

    T. Juutilainen; H. Patiälä; P. Rokkanen; P. Törmälä

    1995-01-01

    The outcome of olecranon and patella fractures fixed with biodegradable implants (self-reinforced poly-l-lactide wire combined with self-reinforced polyglycolide screw or self-reinforced poly-l-lactide plug) or with metallic implants (tension band wiring, Kirschner wire and metallic cerclage wire) was compared in a prospective, randomized study. Twenty-five olecranon fractures (15 with biodegradable implants and 10 with metallic ones) and 10 patella fractures (6

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

    PubMed

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

    2014-12-01

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

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

    PubMed Central

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

    2014-01-01

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

  1. Lag screw fixation of an extensor process fracture in a foal with flexural deformity.

    PubMed Central

    MacLellan, K N; MacDonald, D G; Crawford, W H

    1997-01-01

    A 4-month-old colt with stage I flexural deformity of the distal interphalangeal joint was diagnosed as having a type IV nondisplaced fracture of the extensor process of the 3rd phalanx. An inferior check ligament desmotomy and internal fixation of the fracture were performed. Favorable long-term results for internal fixation of extensor process fractures are presented. Images Figure 1a. Figure 1b. PMID:9105720

  2. Palmar Fixation of Dorsally Displaced Distal Radius Fractures Using Locking Plates with Smartlock Locking Screws

    Microsoft Academic Search

    T. C. WONG; C. C. YEUNG; Y. CHIU; S. H. YEUNG; F. K. IP

    2009-01-01

    We performed a prospective cohort study on a consecutive series of 35 unstable, dorsally displaced distal radius fractures, which were treated with palmar locking plates and SmartLock locking screws. There were 17 men and 18 women with a mean age of 44 years who were reviewed at a mean follow-up of 10 months. All the fractures healed at a mean

  3. [Sagittal splitting with screw fixation in patients with mesial bite wearing dentures--planning surgery and prosthetic design].

    PubMed

    Krenkel, Ch; Anthofer, R; Lixl, G

    1989-03-01

    In fully or partially edentulous patients with mesial bite undergoing surgical correction, the possibilities for avoiding intermaxillary fixation were studied. For stable osteosynthesis of mandibular osteotomies preoperative prostheses are needed in these patients to keep the jaws in their proper relation during surgery. This requires cephalic adjustment of the maxillary cast and articular adjustment of the mandibular cast in the articulator. The mandibular cast is shifted along an aluminum wedge designed to match the inclination of the occlusal plane until the alveolar rests are in proper relation to one another. If the occlusal plane is neglected, uncontrollable tilting of the mandible may occur. This may favor relapses. As Slavicek (1984) showed the mean inclination of the occlusal plane relative to the hinge axis-orbital plane to be 12.87 degrees (scatter 5.99 degrees) with dorsal convergence in 1,213 patients, 3 aluminium wedges with different inclinations were designed. These are suited for 92.5% of all cases with tolerances of +/- 3 degrees. Mandibular casts are pasted to geometric paper and shifted along the aluminium wedge to the desired position; the distance they are shifted is read from the paper. This distance is transferred to the teleradiograph and the changes in profile are checked. Preoperatively, prostheses can then be tailored to match the desired alveolar crest relation. During surgery, these prostheses serve as splints for setting the mandible as designed in the model. The osteotomy fragments are then screwed together transbuccally with miniscrews and clawed washers. The latter provide for a firm seat of the traction screws in the mandible at a safe distance from the mandibular canal. Postoperative intermaxillary fixation can thus be avoided. PMID:2700405

  4. Bone Anchor Fixation in Abdominal Wall Reconstruction: A Useful Adjunct in Suprapubic and Para-iliac Hernia Repair.

    PubMed

    Blair, Laurel J; Cox, Tiffany C; Huntington, Ciara R; Ross, Samuel W; Kneisl, Jeffrey S; Augenstein, Vedra A; Heniford, B Todd

    2015-07-01

    Suprapubic hernias, parailiac or flank hernias, and lumbar hernias are difficult to repair and are associated with high-recurrence rates owing to difficulty in obtaining substantive overlap and especially mesh fixation due to bone being a margin of the hernia. Orthopedic suture anchors used for ligament reconstruction have been used to attach prosthetic material to bony surfaces and can be used in the repair of these hernias where suture fixation was impossible. A prospective, single institution study of ventral hernia repairs involving bone anchor mesh fixation was performed. Demographics, operative details, and outcomes data were collected. Twenty patients were identified, with a mean age 53 (range: 35-70 years) and mean body mass index 28.4 kg/m(2) (range 21-38). Ten lumbar, seven suprapubic, and three parailiac hernias were studied. The majority were recurrent hernias (n = 13), with one to seven previously failed repairs. The mean hernia defect size was very large (270 cm(2); range: 56-832 cm(2)) with average mesh size of 1090 cm(2) (range 224-3640 cm(2)). Both Mitek GII (Depuy, Raynham, MA) and JuggerKnot 2.9-mm (Biomet, Biomedical Instruments, Warsaw, IN) anchors were used, with an average of four anchors/case (range: 1-16). Mean operative time was 218 minutes (120-495). There were three minor complications, no operative mortality, and no recurrences during an average follow-up of 24 months. Pelvic bone anchors permit mesh fixation in high-recurrence areas not amenable to traditional suture fixation. The ability to safely and effectively use bone anchor fixation is an essential tool in complex open ventral hernia repair. PMID:26140889

  5. Occult internal iliac arterial injury identified during open reduction internal fixation of an acetabular fracture: A report of two cases.

    PubMed

    Chaus, George W; Heng, Marilyn; Smith, Raymond M

    2015-07-01

    We present two cases of occult internal iliac arterial injury identified during operative reduction of a widely displaced posterior column posterior wall acetabular fracture. This complication was not recognised until reduction of the column fracture. There were no preoperative signs or symptoms indicative of a vascular injury. These cases emphasise the heightened awareness one must have when treating widely displaced posterior column fractures of the acetabulum, especially those fractures with extension into the greater sciatic notch, as previously formed clot can become dislodged and hemostasis lost. We also present management options when this complication occurs. We believe any surgeon treating acetabular fractures should be aware of this serious and potentially fatal complication. PMID:25986669

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

    PubMed

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

    2015-01-01

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

  7. Late foreign-body reaction to PLLA screws used for fixation of acetabular osteotomy

    Microsoft Academic Search

    D. Seino; S. Fukunishi; S. Yoshiya

    2007-01-01

    A 31-year-old woman underwent rotational acetabular osteotomy for acetabular dysplasia. At surgery, the acetabular fragment\\u000a and the grafted bone were fixed with PLLA screws. One year 7 months after surgery, the patient returned to our clinic with\\u000a acute swelling and pain with sinus formation. Based on the diagnosis of an infection, local debridement was performed. Histological\\u000a examination of the debrided

  8. Early Weight Bearing of Calcaneal Fractures Treated by Intraoperative 3D-Fluoroscopy and Locked-Screw Plate Fixation

    PubMed Central

    Kienast, B; Gille, J; Queitsch, C; Kaiser, M.M; Thietje, R; Juergens, C; Schulz, A.P

    2009-01-01

    Operative therapy of intraarticular fractures of the calcaneus is an established surgical standard. The aim is an accurate reduction of the fracture with reconstruction of Boehler’s angle, length, axis and subtalar joint surface. Intraoperative 3D-fluoroscopy with the Siremobil Iso-C 3D® mobile C-arm system is a valuable assistant for accurate reconstruction of these anatomical structures. Remaining incongruities can be recognized and corrected intraoperatively. The achieved reduction can be fixed by the advantages of an internal fixator (locked-screw plate interface). In the period of October 2002 until April 2007 we operated 136 patients with intraarticular fractures of the calcaneus by means of anatomical reduction, and internal plate fixator under intraoperative control of 3D-fluoroscopy. All patients were supplied with an orthesis after the operation which allowed weight bearing of 10 kg for 12 weeks for the patients operated between October 2002 and October 2004 (Group A). Transient local osteoporosis was observed in all X-Rays at follow-up after an average of 8,6 months. Therefore we changed our postoperative treatment plan for the patients operated between November 2004 and April 2007 (Group B). Weight bearing started with 20 KG after 6 weeks, was increased to 40 KG after 8 weeks and full weight bearing was allowed after 10 weeks for these patients. In no case a secondary dislocation of the fracture was seen. No bone graft was used. At follow up the average American Foot and Ankle Society Score (AOFAS) were 81 for Group_A, compared to 84 for Group B, treated with earlier weight bearing. Autologous bone graft was not necessary even if weight bearing was started after a period of six weeks postoperatively. The combination of 3D-fluoroscopy with locked internal fixation showed promising results. If the rate of patients developing subtalar arthrosis will decrease by this management will have to be shown in long term follow up. PMID:19750017

  9. Excision of extensive midfoot pigmented villonodular synovitis with microvascular anastamosis of iliac crest bone graft using external fixation: a case report.

    PubMed

    Oloff, Lawrence; Miller, Kevin

    2011-10-01

    Pigmented villonodular synovitis (PVNS) is a relatively rare lesion in the foot and ankle, most commonly involving the ankle joint and atypically, the subtalar and midtarsal joints. It is a benign proliferative disease characterized by an increase in villous or nodular synovium in joints. Resection of the tumor is often indicated in most cases because of the potentially aggressive joint destructive nature of this lesion. This report presents a case of chronic enlarging pervasive midtarsal and metatarsal-cuneiform joint PVNS in a 28-year-old male. This patient had a midtarsal mass that enlarged over a period of 2 years, causing increased pain, deformity, and difficulty with ambulation. Cross-sectional imaging studies identified evidence of erosive disease through much of the midfoot articulations, with biopsy confirming the mass as PVNS. The dimensions of the mass approximated 5.5 cm × 4.1 cm × 2.8 cm. Simple resection was problematic because of the size and multiple joints involved. Amputation was most commonly advised by multiple consultants. The patient preferred attempt at limb salvage. En bloc resection and placement of a revascularized iliac crest bone graft was used to fill the defect. The graft was microvascularly anastamosed and fixated with standard external fixation. Pathologic and histologic specimens from surgical biopsy reconfirmed the diagnosis of PVNS postoperatively. Second-stage arthrodesis was performed when the patient was stable and disease free. The patient was followed postoperatively for 10 years without recurrence and was able to return to full function and partake in moderate athletic activity at last visit. This case describes a retrospective review of the procedure and reconstruction, as well as an overview of current surgical management of PVNS. PMID:21926367

  10. Bilateral atlas laminar hook combined with transarticular screw fixation for an unstable bursting atlantal fracture

    Microsoft Academic Search

    Xiang Guo; Bin Ni; Mingfei Wang; Jian Wang; Songkai Li; Fengjin Zhou

    2009-01-01

    Introduction  The unstable atlas burst fracture (“Jefferson fracture”) is a fracture of the anterior and posterior atlantal arch with rupture\\u000a of the transverse atlantal ligament and an incongruence of the atlanto-occipital and the atlanto-axial joint facets. The posterior\\u000a atlantoaxial fusion is frequently used to reconstruct the stability of atlantoaxial joint. Conventional posterior atlantoaxial\\u000a fixations are associated with high rates of pseudoarthrosis

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

    PubMed Central

    2014-01-01

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

  12. 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

    Wichit Tharanon

    1998-01-01

    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,

  13. Evaluation of stress distribution in resorbable screw fixation system: three-dimensional finite element analysis of mandibular setback surgery with bilateral sagittal split ramus osteotomy.

    PubMed

    Choi, Jae-Pyong; Baek, Seung-Hak; Choi, Jin-Young

    2010-07-01

    The purpose of this study was to evaluate the stress distribution of resorbable screw (RS) and cortical/cancellous bone in the mandibular setback surgery with bilateral sagittal split ramus osteotomy (BSSRO) according to fixation geometry and number of RSs using three-dimensional finite element analysis. Three-dimensional virtual models of the mandible and bicortical RS (INION CPS System; diameter, 2.5 mm; length, 12 mm [Inion Ltd, Tampere, Finland]) were constructed by Mimics (Materialise, Ann Arbor, MI) using three-dimensional computed tomography DICOM data with 0.5-mm-thickness cut. After 8-mm setback BSSRO was performed, fixation between the proximal and distal segments of the mandible was done with bicortical RS. Fixation options were classified into 3RL (3 RSs with linear configuration at the retromolar area), 2R1A (2 RSs at the retromolar area and 1 RS at the mandibular angle area), 2R1B (2 RSs at the retromolar area and 1 RS at the mandibular body area), and 3R1A (3 RSs at the retromolar area and 1 RS at the mandibular angle area). After applying the occlusal load of 132 N on the lower first molar, stress distributions of the RSs and cortical/cancellous bone in each option were analyzed by ANSYS program (ANSYS Inc, Canonsburg, PA). Maximum stress concentration was found at the anterior RS fixation in the retromolar area in all options. Although 3R1A fixation showed more even distribution of stress concentration than other fixation options, 2R1A fixation was comparable with 3R1A fixation in view of yield stress in RSs. In terms of fixation geometry and number of RSs, both 2R1A and 3R1A fixation configurations might provide proper stress distribution in BSSRO. PMID:20613578

  14. Cervical screw missing secondary to delayed esophageal fistula: case report.

    PubMed

    Cagli, Sedat; Isik, H Serdar; Zileli, Mehmet

    2009-10-01

    Although anterior surgical approaches to the cervical spine have become popular and safe in recent years, they also have some complications. We present a case of loss of an anterior cervical plate screw by the natural tracts. The patient was a 47- year-old woman who was operated on for cervical spondylotic myelopathy at another institution. Surgical interference included two levels of anterior discectomy, iliac graft placement and fixation using plate and screws. Two years later, plate dislocation and partial migration of the upper screws were observed. After 7 years the patient complained of dysphagia and she accepted removal of the osteosynthesis. Radiographical examination showed that one of the upper screws was missing and two lower screws were broken. Esophageal perforation was found during the surgery and repaired. Further progress was favourable. Complications associated with esophageal perforation may range from massive infection and death to spontaneous recovery. Erosion of the esophageal wall due to extruded bulky constructs may lead to a persistent fistula, abscess or septic diffusion. Spontaneous perforation of the esophagus and screw loss via the gastrointestinal tract make this case interesting.. PMID:19847769

  15. Pooled Analysis of Non-Union, Re-Operation, Infection, and Approach Related Complications after Anterior Odontoid Screw Fixation

    PubMed Central

    Tian, Nai-Feng; Hu, Xu-Qi; Wu, Li-Jun; Wu, Xin-Lei; Wu, Yao-Sen; Zhang, Xiao-Lei; Wang, Xiang-Yang; Chi, Yong-Long; Mao, Fang-Min

    2014-01-01

    Background Anterior odontoid screw fixation (AOSF) has been one of the most popular treatments for odontoid fractures. However, the true efficacy of AOSF remains unclear. In this study, we aimed to provide the pooled rates of non-union, reoperation, infection, and approach related complications after AOSF for odontoid fractures. Methods We searched studies that discussed complications after AOSF for type II or type III odontoid fractures. A proportion meta-analysis was done and potential sources of heterogeneity were explored by meta-regression analysis. Results Of 972 references initially identified, 63 were eligible for inclusion. 54 studies provided data regarding non-union. The pooled non-union rate was 10% (95% CI: 7%–3%). 48 citations provided re-operation information with a pooled proportion of 5% (95% CI: 3%–7%). Infection was described in 20 studies with an overall rate of 0.2% (95% CI: 0%–1.2%). The main approach related complication is postoperative dysphagia with a pooled rate of 10% (95% CI: 4%–17%). Proportions for the other approach related complications such as postoperative hoarseness (1.2%, 95% CI: 0%–3.7%), esophageal/retropharyngeal injury (0%, 95% CI: 0%–1.1%), wound hematomas (0.2%, 95% CI: 0%–1.8%), and spinal cord injury (0%, 95% CI: 0%–0.2%) were very low. Significant heterogeneities were detected when we combined the rates of non-union, re-operation, and dysphagia. Multivariate meta-regression analysis showed that old age was significantly predictive of non-union. Subgroup comparisons showed significant higher non-union rates in age ?70 than that in age ?40 and in age 40 to <50. Meta-regression analysis did not reveal any examined variables influencing the re-operation rate. Meta-regression analysis showed age had a significant effect on the dysphagia rate. Conclusions/Significances This study summarized the rates of non-union, reoperation, infection, and approach related complications after AOSF for odontoid factures. Elderly patients were more likely to experience non-union and dysphagia. PMID:25058011

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

    PubMed Central

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

    2015-01-01

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

  17. Intraoperative Computed Tomography Navigation for Transpedicular Screw Fixation to Treat Unstable Thoracic and Lumbar Spine Fractures: Clinical Analysis of a Case Series (CARE-Compliant).

    PubMed

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

    2015-05-01

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

  18. The Warwick Hip Trauma Evaluation One -an abridged protocol for the WHiTE One Study: An embedded randomised trial comparing the X-bolt with slidinghip screw fixation in extracapsular hip fractures.

    PubMed

    Griffin, X L; McArthur, J; Achten, J; Parsons, N; Costa, M L

    2013-01-01

    Fractures of the proximal femur are one of the greatest challenges facing the medical community, constituting a heavy socioeconomic burden worldwide. Controversy exists regarding the optimal treatment for patients with unstable trochanteric proximal femoral fractures. The recognised treatment alternatives are extramedullary fixation usually with a sliding hip screw and intramedullary fixation with a cephalomedullary nail. Current evidence suggests that best results and lowest complication rates occur using a sliding hip screw. Complications in these difficult fractures are relatively common regardless of type of treatment. We believe that a novel device, the X-Bolt dynamic plating system, may offer superior fixation over a sliding hip screw with lower reoperation risk and better function. We therefore propose to investigate the clinical effectiveness of the X-bolt dynamic plating system compared with standard sliding hip screw fixation within the framework of a the larger WHiTE (Warwick Hip Trauma Evaluation) Comprehensive Cohort Study. Cite this article: Bone Joint Res 2013;2:206-9. PMID:24089290

  19. The use of a virtual three-dimensional model to evaluate the intraosseous space available for percutaneous screw fixation of acetabular fractures.

    PubMed

    Attias, N; Lindsey, R W; Starr, A J; Borer, D; Bridges, K; Hipp, J A

    2005-11-01

    We created virtual three-dimensional reconstruction models from computed tomography scans obtained from patients with acetabular fractures. Virtual cylindrical implants were placed intraosseously in the anterior column, the posterior column and across the dome of the acetabulum. The maximum diameter which was entirely contained within the bone was determined for each position of the screw. In the same model, the cross-sectional diameters of the columns were measured and compared to the maximum diameter of the corresponding virtual implant. We found that the mean maximum diameter of virtual implant accommodated by the anterior columns was 6.4 mm and that the smallest diameter of the columns was larger than the maximum diameter of the equivalent virtual implant. This study suggests that the size of the screw used for percutaneous fixation of acetabular fractures should not be based solely on the measurement of cross-sectional diameter and that virtual three-dimensional reconstructions might be useful in pre-operative planning. PMID:16260671

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

    Microsoft Academic Search

    Deniz Belen; Serkan Simsek; Kazim Yigitkanli; Murad Bavbek

    2006-01-01

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

  1. Comparison of healing process in open osteotomy model and open fracture model: Delayed healing of osteotomies after intramedullary screw fixation.

    PubMed

    Klein, Moritz; Stieger, Andrea; Stenger, David; Scheuer, Claudia; Holstein, Jörg H; Pohlemann, Tim; Menger, Michael D; Histing, Tina

    2015-07-01

    Murine osteotomy and fracture models have become the standard to study molecular mechanisms of bone healing. Because there is little information whether the healing of osteotomies differs from that of fractures, we herein studied in mice the healing of femur osteotomies compared to femur fractures. Twenty CD-1 mice underwent a standardized open femur osteotomy. Another 20 mice received a standardized open femur fracture. Stabilization was performed by an intramedullary screw. Bone healing was studied by micro-CT, biomechanical, histomorphometric and protein expression analyses. Osteotomies revealed a significantly lower biomechanical stiffness compared to fractures. Micro-CT showed a reduced bone/tissue volume within the callus of the osteotomies. Histomorphometric analyses demonstrated also a significantly lower amount of osseous tissue in the callus of osteotomies (26% and 88% after 2 and 5 weeks) compared to fractures (50% and 100%). This was associated with a delayed remodeling. Western blot analyses demonstrated comparable BMP-2 and BMP-4 expression, but higher levels of collagen-2, CYR61 and VEGF after osteotomy. Therefore, we conclude that open femur osteotomies in mice show a markedly delayed healing when stabilized less rigidly with an intramedullary screw. This should be considered when choosing a model for studying the mechanisms of bone healing in mice. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 33:971-978, 2015. PMID:25732349

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

    PubMed Central

    Peters, Todd; Hussain, Mir; Khalil, Saif

    2014-01-01

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

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

    PubMed Central

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

    2014-01-01

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

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

    PubMed Central

    2014-01-01

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

  5. 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

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

    2005-01-01

    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

  6. Retrieval of broken iliosacral screws: The power of a push screw.

    PubMed

    El Dafrawy, Mostafa H; Osgood, Greg M

    2015-07-01

    Percutaneous iliosacral screw fixation is a common technique that is widely used for unstable posterior pelvic ring disruptions. Complications of posterior percutaneous iliosacral screw fixation include implant malpositioning and hardware failure. Removal of iliosacral screws in broken or symptomatic hardware is sometimes necessary. To our knowledge, there are few reports addressing pelvic implant removal, and most of those report on anterior pelvic implants and symphyseal plates. There are no reports describing techniques for retrieval of broken iliosacral screws. We present two cases involving removal of broken sacroiliac screws, review the literature regarding iliosacral implant extraction, and identify important aspects of safe extraction of iliosacral screws and the potential complications associated with their retrieval. We further describe a novel and powerful technique to facilitate percutaneous removal of broken screw fragments, using a "push screw" to drive a broken screw fragment from a position buried in bone. PMID:25986663

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

    PubMed Central

    Troussel, Serge

    2007-01-01

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

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

    PubMed

    Debusscher, Felix; Troussel, Serge

    2007-10-01

    Spondylolysis is a common entity, a minority of people affected by this disease need medical care, and only a few require surgery. Reconstruction of the pars interarticularis is an interesting alternative to segmental fusion; this technique has the advantage of preserving segmental motion. Most authors report good results for young patients without intervertebral disk or facet degenerative changes. Moreover Louis also showed good to excellent results with his technique carried out among people who presented a satisfactory disk height (equal to two thirds of normal height). This could extend the number of patients for whom pars interarticularis repair could be proposed. In this study, the limit of reconstruction was set at grade 3 of 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

  9. Scarf osteotomy without screw fixation

    Microsoft Academic Search

    M. Maestro

    2007-01-01

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

  10. Pedicle Instrumentation Failure in Thoracolumbar Fixation

    Microsoft Academic Search

    Mohamed Lotfy; Nasser M. Sayed Ahmed; Alaa A. Farag; Walid Raafat; Walid A. Badawy; Hossam Ibrahim; Islam Abou El Fotouh; Ahmed Saleh

    2007-01-01

    Objective: The authors reviewed factors related to the surgical techniques resulting in failure of the construct of the internal fixation of thoracolumbar fractures through transpedicular screw systems and how to be avoided. Patients and Methods: The authors reviewed 280 consecutive patients with traumatic thoracolumbar fractures who underwent spinal surgical fixation with short segment transpedicular screw instrumentation at three institutions, between

  11. Clinical Comparison of Fixation Methods for Patellar Bone Quadriceps Tendon Autografts in Anterior Cruciate Ligament ReconstructionAbsorbable Cross-pins Versus Absorbable Screws

    Microsoft Academic Search

    Ottmar Gorschewsky; Robert Stapf; Laurent Geiser; Ulrich Geitner; Wolfram Neumann

    2007-01-01

    Background: Recently, the use of the quadriceps tendon transplant with bone block (patellar bone quadriceps tendon autografts) for anterior cruciate ligament reconstruction has increasingly been reported.Hypothesis: Clinical results after the implantation of a patellar bone quadriceps tendon autograft fixed with cross-pins or screws will show no significant difference between the 2 techniques with regard to stability, function, and subjective satisfaction.

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

    PubMed

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

    2009-06-01

    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

  13. A Case of Pedicle Screw Loosening Treated by Modified Transpedicular Screw Augmentation with Polymethylmethacrylate

    PubMed Central

    Kang, Suk-Hyung; Kim, Kyoung-Tae; Park, Seung Won

    2011-01-01

    We report a case of pedicle screw loosening treated by modified transpedicular screw augmentation technique using polymethylmethacrylate (PMMA), which used the anchoring effect of hardened PMMA. A 56-year-old man who had an L3/4/5 fusion operation 3 years ago complained of continuous low back pain after this operation. The computerized tomography showed a radiolucent halo around the pedicle screw at L5. We augmented the L5 pedicle screw with modified pedicle screw augmentation technique using PMMA and performed an L3/4/5 pedicle screw fixation without hook or operation field extension. This modified technique is a kind of transpedicular stiffness augmentation using PMMA for the dead space around the loosed screw. After filling the dead space with 1-2 cc of PMMA, we inserted a small screw. Once the PMMA hardened, we removed the small screw and inserted a thicker screw along the existing screw threading to improve the pedicle screws' pullout strength. At 10 months' follow-up, x-ray showed strong fusion of L3/4/5. The visual analogue scale (VAS) of his back pain was improved from 9 to 5. This modified transpedicular screw augmentation with PMMA using anchoring effect is a simple and effective surgical technique for pedicle screw loosening. However, clinical analyses of long-term follow-up and biomechanical studies are needed. PMID:21494370

  14. Medial malleolar fractures: a biomechanical study of fixation techniques.

    PubMed

    Fowler, T Ty; Pugh, Kevin J; Litsky, Alan S; Taylor, Benjamin C; French, Bruce G

    2011-08-01

    Fracture fixation of the medial malleolus in rotationally unstable ankle fractures typically results in healing with current fixation methods. However, when failure occurs, pullout of the screws from tension, compression, and rotational forces is predictable. We sought to biomechanically test a relatively new technique of bicortical screw fixation for medial malleoli fractures. Also, the AO group recommends tension-band fixation of small avulsion type fractures of the medial malleolus that are unacceptable for screw fixation. A well-documented complication of this technique is prominent symptomatic implants and secondary surgery for implant removal. Replacing stainless steel 18-gauge wire with FiberWire suture could theoretically decrease symptomatic implants. Therefore, a second goal was to biomechanically compare these 2 tension-band constructs. Using a tibial Sawbones model, 2 bicortical screws were compared with 2 unicortical cancellous screws on a servohydraulic test frame in offset axial, transverse, and tension loading. Second, tension-band fixation using stainless steel wire was compared with FiberWire under tensile loads. Bicortical screw fixation was statistically the stiffest construct under tension loading conditions compared to unicortical screw fixation and tension-band techniques with FiberWire or stainless steel wire. In fact, unicortical screw fixation had only 10% of the stiffness as demonstrated in the bicortical technique. In a direct comparison, tension-band fixation using stainless steel wire was statistically stiffer than the FiberWire construct. PMID:21815575

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

    PubMed Central

    2013-01-01

    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

  16. Lumbopelvic fusion with a new fixation technique in lumbosacral agenesis: three cases

    PubMed Central

    Akel, Ibrahim; Demirkiran, Halil Gokhan

    2011-01-01

    Purpose Patients with lumbosacral agenesis characteristically sit on their iliac wings with their torsos bent forward, which yields an increase in intra-abdominal pressure and, subsequently, negative effects on their diaphragm. The sacrum is not available as an anchor point for instrumentation. Dunn-McCarthy rods or Galveston fixations cannot be performed due to these limited anatomic properties. On the other hand, the absence of necessary bone mass for fusion anteriorly limits the fusion interventions to the posterior. Therefore, a secure and rigid fixation is essential to preclude the need for an external support. There are limited publications discussing different techniques due to the relatively rare incidence of the disease. We report the clinical and radiological results of a new technique applied to three patients in which previously recommended methods are modified. Methods Two 6-year-old female patients and one 5-year-old male patient with lumbosacral agenesis underwent posterior lumbopelvic instrumentation and fusion. Together with standard pedicle screw spinal instrumentation, pelvic fixation is obtained with a combination of supero-inferior directed rod and/or screw to overcome deforming forces created at the flexion–extension pivot points of the lumbopelvic junction. Autogenic anterior tibial cortical structural graft is used for laminopelvic bridging, and demineralized bone matrix is used for the augmentation of osteoinduction. A single leg hip spica is applied for 4 months to protect the fixation. Results Total correction yielded an aligned spine with a posture that allows for sitting on the ischial spines for all three patients. Solid fusion was observed to maintain this correction at the final follow-up. Conclusion The use of new-generation pediatric spinal instrumentation systems with a new technique without knee disarticulation provides a safe and effective fixation and fusion in lumbosacral agenesis. PMID:22295050

  17. Morphometric evaluation of subaxial cervical spine using multi-detector computerized tomography (MD-CT) scan: the consideration for cervical pedicle screws fixation

    PubMed Central

    2014-01-01

    Background Cervical pedicle screw (CPS) insertion is a technically demanding procedure. The quantitative understanding of cervical pedicle morphology, especially the narrowest part of cervical pedicle or isthmus, would minimize the risk of catastrophic damage to surrounding neurovascular structures and improve surgical outcome. The aim of this study was to investigate morphology and quantify cortical thickness of the cervical isthmus by using Multi-detector Computerized Tomography (MD-CT) scan. Methods The cervical CT scans were performed in 74 patients (37 males and 37 females) with 1-mm slice thickness and then retro-reconstructed into sagittal and coronal planes to measure various cervical parameters as follows: outer pedicle width (OPW), inner pedicle width (IPW), outer pedicle height (OPH), inner pedicle height (IPH), pedicle cortical thickness, pedicle sagittal angle (PSA), and pedicle transverse angle (PTA). Results Total numbers of 740 pedicles were measured in this present study. The mean OPW and IPW significantly increased from C3 to C7 while the mean OPH and IPH of those showed non-significant difference between any measured levels. The medial-lateral cortical thickness was significantly smaller than the superior-inferior one. PTA in the upper cervical spine was significantly wider than the lower ones. The PSA changed from upward inclination at upper cervical spine to the downward inclination at lower cervical spine. Conclusions This study has demonstrated that cervical vertebra has relatively small and narrow inner pedicle canal with thick outer pedicle cortex and also shows a variable in pedicle width and inconsistent transverse angle. To enhance the safety of CPS insertion, the entry point and trajectories should be determined individually by using preoperative MD-CT scan and the inner pedicle width should be a key parameter to determine the screw dimensions. PMID:24725394

  18. Arthroscopic Posterior Shoulder Stabilization With an Iliac Bone Graft and Capsular Repair: A Novel Technique

    PubMed Central

    Smith, Tomas; Goede, Fabian; Struck, Melena; Wellmann, Mathias

    2012-01-01

    Several surgical approaches have been described for the treatment of recurrent posterior shoulder instability. Many authors have performed posterior bone block procedures with good results not only in the presence of glenoid bone loss or dysplasia but also in the case of capsular hyperlaxity and poor soft-tissue quality. Open techniques often require an extensive approach with the disadvantage of a poor cosmetic result and possible insufficiency of the deltoid muscle. Furthermore, the treatment of concomitant pathologies and the correct placement of the bone graft are difficult. Therefore we describe an all-arthroscopic posterior shoulder stabilization technique with an iliac bone graft and capsular repair that is intended to improve the pre-existing open procedure. The key steps of the operation are the precise placement and screw fixation of the bone block at the posterior glenoid under arthroscopic control and the subsequent posterior capsular refixation and plication using 2 suture anchors to create an extra-articular graft position. PMID:23766993

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

    Microsoft Academic Search

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

    2008-01-01

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

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

    PubMed Central

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

    2008-01-01

    This is an experimental study on human cadaver spines. The objective of this study is to compare the pullout forces between three screw augmentation methods and two different screw designs. Surgical interventions of patients with osteoporosis increase following the epidemiological development. Biomechanically the pedicle provides the strongest screw fixation in healthy bone, whereas in osteoporosis all areas of the vertebra are affected by the disease. This explains the high screw failure rates in those patients. Therefore PMMA augmentation of screws is often mandatory. This study involved investigation of the pullout forces of augmented transpedicular screws in five human lumbar spines (L1–L4). Each spine was treated with four different methods: non-augmented unperforated (solid) screw, perforated screw with vertebroplasty augmentation, solid screw with vertebroplasty augmentation and solid screw with balloon kyphoplasty augmentation. Screws were augmented with Polymethylmethacrylate (PMMA). The pullout forces were measured for each treatment with an Instron testing device. The bone mineral density was measured for each vertebra with Micro-CT. The statistical analysis was performed with a two-sided independent student t test. Forty screws (10 per group and level) were inserted. The vertebroplasty-augmented screws showed a significant higher pullout force (mean 918.5 N, P = 0.001) than control (mean 51 N), the balloon kyphoplasty group did not improve the pullout force significantly (mean 781 N, P > 0.05). However, leakage occurred in some cases treated with perforated screws. All spines showed osteoporosis on Micro-CT. Vertebroplasty-augmented screws, augmentation of perforated screws and balloon kyphoplasty augmented screws show higher pullout resistance than non-augmented screws. Significant higher pullout forces were only reached in the vertebroplasty augmented vertebra. The perforated screw design led to epidural leakage due to the position of the perforation in the screw. The position of the most proximal perforation is critical, depending on screw design and proper insertion depth. Nevertheless, using a properly designed perforated screw will facilitate augmentation and instrumentation in osteoporotic spines. PMID:18781342

  1. Screw prominences related to palmar locking plating of distal radius

    Microsoft Academic Search

    T. S. Sügün; N. Karabay; Y. Gürbüz; K. Özaksar; T. Toros; M. Kayalar

    2011-01-01

    Fixation of unstable distal radius fractures with palmar locking plates provides a stable reduction and early return of function, but complications arising from unrecognized dorsally prominent screws penetrating the extensor compartments are increasingly reported. Standard radiographs and fluoroscopy may not adequately visualize screw lengths, owing to the complex shape of the dorsum of the distal radius. We examined 46 distal

  2. Evaluation of 3 Fixation Devices for Tibial-Sided Anterior Cruciate Ligament Graft Backup Fixation.

    PubMed

    Verioti, Christopher A; Sardelli, Matthew C; Nguyen, Tony

    2015-07-01

    We conducted a study to biomechanically evaluate 3 methods of tibial-sided fixation for anterior cruciate ligament reconstruction: fully threaded interference screw only, interference screw backed with 4.75-mm SwiveLock anchor, and fully threaded bio-interference screw backed with 4.5-mm bicortical screw (all Arthrex). Thirty skeletally mature porcine tibiae were used. The first group was prepared by graft fixation within the tibial tunnel using only an interference screw. The second and third groups included an interference screw with 2 types of secondary fixation: 4.5-mm bicortical post and SwiveLock anchor. Mechanical testing consisted of 500 cycles between 50 and 250 N at 1 Hz, followed by a pull to failure conducted at 20 mm per minute. Ultimate load-to-failure testing demonstrated the largest mean (SD) load tolerated in the post/washer group, 1148 (186) N, versus the SwiveLock group, 1007 (176) N, and the screw-only group, 778 (139) N. There was no statistical difference between the 2 backup fixation groups. Use of a SwiveLock anchor as backup fixation at the tibial side in soft-tissue anterior cruciate ligament reconstruction is a safe, effective alternative to a bicortical post and provides statistically equivalent pullout strength with unlikely requirement for future hardware removal. PMID:26161768

  3. Iliac crest bone graft donor site hernia: not so uncommon

    PubMed Central

    Prabhu, Raghunath; Kumar, Nawin; Shenoy, Rajgopal

    2013-01-01

    A 73-year-old man, who had undergone fracture fixation of humerus with LCP plating and bone grafting, presented again with a peri-implant fracture after 1?year. A repeat surgery was contemplated and replating was performed with tricortical bone graft harvested from the iliac crest. In the postoperative period the patient developed a tender swelling at the graft site with nausea and abdominal discomfort. It was managed conservatively thinking it to be a haematoma at the graft site. In the following 2?days his symptoms worsened. A CT abdomen showed the herniation of caecum from the bone graft donor site with obstruction. The patient was taken up for emergency surgical repair, the caecum was reduced and polypropylene mesh hernioplasty was performed. The patient recovered well without recurrence in the follow-up period. Iliac crest bone graft site hernia is not so uncommon and care has to be taken while harvesting. PMID:23761618

  4. A finite element parametric study of clavicle fixation plates.

    PubMed

    Pendergast, Megan; Rusovici, Razvan

    2015-06-01

    A finite element simulation on a fracture fixated clavicle was performed to study the effects of different fracture fixation parameters on the callus region. Specifically, parameters such as plate material, thickness, plate/bone gap, screw length, and locking vs. non-locking screws were explored. Plate thickness and locking vs. non-locking screws were found to be influential to construct stiffness where plate/bone gap and number of screws were not as sensitive. Copyright © 2015 John Wiley & Sons, Ltd. PMID:25641811

  5. Anatomical study of axis for odontoid screw thickness, length, and angle

    PubMed Central

    Tun, Kagan; Cemil, Berker; Yorubulut, Mehmet; Karahan, S. Tuna; Tekdemir, Ibrahim

    2008-01-01

    Anterior odontoid screw fixation is a safe and effective method for treatment of odontoid fractures. The screw treads should fit into the odontoid medulla, should pass the fracture line, and should pull fractured odontoid tip against body of axis in order to achieve optimum screw placement and treatment. This study has demonstrated optimal anterior odontoid screw thickness, length, and optimal angle for safe and strong anterior odontoid screw placement. Dry bone axis vertebrae were evaluated by direct measurements, X-ray measurements, and computerized tomography (CT) measurements. The screw thickness (inner diameter of the odontoid) was measured as well as screw length (distance between anterior-inferior point body of axis and tip of odontoid), and screw angle (the angle between basis of axis and tip of odontoid). The inner diameter of odontoid bone was measured as 6.5 ± 1.9 mm, the screw length was 37.6 ± 3.3 mm, and the screw angle was 62.4 ± 4.7 on CT. There was no statistical difference between X-ray and CT in the measurements of screw thickness and angle. X-ray and CT measurements are both safe methods to determine the inner odontoid diameter and angle preoperatively. Screw length should be measured on CT only. To provide safe and strong anterior odontoid screw fixation, screw thickness, length, and angle should be known preoperatively, and these can be measured on X-ray and CT. PMID:19005694

  6. Biomechanical evaluation of a medial knee reconstruction with comparison of bioabsorbable interference screw constructs and optimization with a cortical button.

    PubMed

    Wijdicks, Coen A; Brand, Emily J; Nuckley, David J; Johansen, Steinar; LaPrade, Robert F; Engebretsen, Lars

    2010-11-01

    Current fixation techniques in medial knee reconstructions predominantly utilize interference screws alone for soft tissue graft fixation. The use of concurrent fixation techniques as part of a hybrid fixation technique has also been suggested to strengthen soft tissue fixation, although these hybrid fixation techniques have not been biomechanically validated. The purpose was to biomechanically evaluate two distal tibial superficial MCL graft fixation techniques that consisted of an interference screw alone and in combination with a cortical button. Furthermore, the aim was to compare interference screws of different constructs. Twenty-four porcine tibias (average bone mineral density of 1.3 ± 0.2 g/cm(2); range, 1.0-1.6 g/cm(2), measured by DEXA scan) were divided into 4 groups of six specimens each. Group Ia consisted of a 7 × 23-mm poly-L-lactide (PLLA) interference screw. Group Ib utilized a PLLA interference screw in combination with a cortical button. Group IIa consisted of a 7 × 23-mm composite 70% poly(L-lactide-co-D, L-lactide) and 30% biphasic calcium phosphate (BCP) interference screw. Group IIb also utilized a composite interference screw in combination with a cortical button. The specimens were biomechanically tested with cyclic (500 cycles, 50-250 N, 1 Hz) and load-to-failure (20 mm/min) parameters. During cyclic loading, a significant increase in stiffness was seen for the PLLA hybrid 29.6 (±6.9) N/mm fixation compared to the PLLA screw-only 21.2 (±3.8) N/mm group (P < 0.05). Failure loads were 407.8 (±77.9) N for the composite screw, 445 (±72.2) N for the PLLA screw-only, 473.9 (±69.6) N for the composite hybrid fixation, and 511.0 (±78.5) N for the PLLA hybrid fixation. The PLLA screw alone was found to provide adequate fixation for a superficial MCL reconstruction, and the use of a cortical suture button combined with the PLLA screw resulted in a stiffer fixation during cyclic loading. The current reconstruction superficial MCL graft fixation technique utilizing a PLLA interference screw alone serves as an adequate recreation of the native tibial superficial MCL strength. In addition, a hybrid fixation with a cortical button which lends additional cyclic stiffness to its fixation would be advisable for use in suboptimal fixation cases. PMID:20563561

  7. Biomechanical and morphometric evaluation of occipital condyle for occipitocervical segmental fixation.

    PubMed

    Hong, Jae Taek; Takigawa, Tomoyuki; Sugisaki, Keizo; Espinoza Orías, Alejandro A; Inoue, Nozomu; An, Howard S

    2011-01-01

    Two recent novel techniques of occipital fixation are the occipitoatlantal (C0-C1) transarticular screw technique and the direct occipital condyle screw technique. The present study evaluated and compared the biomechanical stability of the direct occipital condyle screw and C0-C1 transarticular screw with the established method for craniocervical spine fixation using the midline occipital keel screw and C1 lateral mass screw. Morphometric evaluation of the occipital condyle and the hypoglossal canal was performed to avoid hypoglossal nerve injury during the screw placement. Thirteen recently frozen cadaveric specimens were used. The occipital condyle anatomy and the hypoglossal canal dimension were measured using reconstructed computed tomography images. Insertion torque and pullout strength were evaluated to compare the midline occipital keel screw, C0-C1 transarticular screw, C1 lateral mass screw, and direct occipital condyle screw. The dimensions of the occipital condyle allow use of a 3.5 or 4.0-mm diameter screw. Mean pullout strength was 1619.6 N for the midline occipital keel screw, 870.7 N for the C0-C1 transarticular screw, 707.0 N for the C1 lateral mass screw, and 431.7 N for the direct occipital condyle screw. Mean insertion torque was 0.55 Nm for the midline occipital keel screw, 0.32 Nm for the C0-C1 transarticular screw, 0.14 Nm for the C1 lateral mass screw, and 0.11 Nm for the direct occipital condyle screw. The condylar anatomy allows direct insertion of the occipital condyle screw and C0-C1 transarticular screw. These techniques are suitable options for the treatment of craniovertebral junction instabilities in selected patients. PMID:22027245

  8. [The value of posterior iliac osteotomy in the treatment of ectopia vesicae. Two-cases (author's transl)].

    PubMed

    Aubert, J; Mourasse, P; Noël, G; Clarac, J P

    1979-01-01

    The authors emphasise the value of bilateral posterior iliac oestotomy in facilitating aponeurotic and cutaneous closure of ectopia vesicae. The osteotomy cuts the wing of the iliac bone above the greater sciatic notch 2 cms lateral to the sacroiliac joint. The new point made by the author is the use of an external fixation device the pins of which are implanted only in the iliac crest in the still young child, whilst in the adolescent a more solid method of fixation involves in insertion of additional pins in the pubis (taking care to avoid the femoral vessels). The recommended operative schedule is as follows: 1) Simple posterior iliac osteotomy. 2) Bed rest for 8 to 15 days until cutaneous healing of the iliac incisions. 3) Urological phase (which for the author consists of excision of the plaque with ureterocolic implantation) with aponeurotic closure (using eliptical strips fashioned from the rectus sheath) and simple cutaneous closure without any traction because of the osteotomies. 4) Insertion of external fixation device at the end of the urological phase. This is supported by 2 cases reports with and uncomplicated postoperative course from both a urological and orthopaedic standpoint. PMID:537133

  9. A new concept for implant fixation: bone-to-bone biologic fixation.

    PubMed

    Kim, D Y; Kim, J R; Jang, K Y; Lee, K B

    2015-01-01

    Many attempts have been made to reduce complications of bone implant, such as pedicle screw loosening. To address this problem, the authors suggest a new concept of bone-to-bone biologic fixation using recombinant human bone morphogenetic protein-2 (rhBMP-2)-loaded cannulated pedicle screws. Recombinant human bone morphogenetic protein-2 is an osteoinductive cytokine. Four types of titanium pedicle screws were tested (uncannulated, cannulated with no loading, beta-tricalcium phosphate (TCP)-loaded, and TCP/BMP2 loaded) using 16 miniature pigs. Radiological evaluation was conducted to assess the fusion and loosening of pedicle screws. Twelve weeks after implantation, peak torsional extraction torque was measured, and the pedicle screw and bone interface was evaluated by micro-computed tomography (µCT) and histologic examination. The mean value of the radiological score was significantly greater in the TCP/BMP2 loaded group at 12 weeks post-operation compared to those in the other groups. CT images showed distinct bone formation surrounding TCP/BMP2 loaded cannulated pedicle screws compared to the other groups. Mean extraction torsional peak torque at 12 weeks postoperative was more than 10-fold higher in the TCP/BMP2 loaded pedicle screw group than in the other groups. Bone surface and bone volume, as quantitated through µCT, were higher in the TCP/BMP2 loaded group. Histologic examination revealed bone-to-bone fixation at the interface of pedicle screws and pre-existing bone. Bone-to-bone biologic fixation through the holes of TCP/BMP2 loaded pedicle screws significantly increased fixation strength and represents a novel method that can be applied to osteoporotic or tumour spine surgeries. PMID:25978116

  10. Aspiration of Osteoprogenitor Cells for Augmenting Spinal Fusion: Comparison of Progenitor Cell Concentrations from the Vertebral Body and Iliac Crest

    PubMed Central

    MCLAIN, ROBERT F.; FLEMING, JAMES E.; BOEHM, CYNTHIA A.; MUSCHLER, GEORGE F.

    2005-01-01

    Background: Successful arthrodesis in challenging clinical scenarios is facilitated when the site is augmented with autograft bone. The iliac crest has long been the preferred source of autograft material, but graft harvest is associated with frequent complications and pain. Connective tissue progenitor cells aspirated from the iliac crest and concentrated with allograft matrix and demineralized bone matrix provide a promising alternative to traditional autograft harvest. The vertebral body, an even larger reservoir of myeloproliferative cells, should provide progenitor cell concentrations similar to those of the iliac crest. Methods: Twenty-one adults (eleven men and ten women with a mean age of 59 ± 14 years) undergoing posterior lumbar arthrodesis and pedicle screw instrumentation underwent transpedicular aspiration of connective tissue progenitor cells. Aspirates were obtained from two depths within the vertebral body and were quantified relative to matched, bilateral aspirates from the iliac crest that were obtained from the same patient at the same time. Histochemical analysis was used to determine the prevalence of vertebral progenitor cells relative to the depth of aspiration, the vertebral level, age, and gender, as compared with the iliac crest standard. The cell count, progenitor cell concentration (cells/cc marrow), and progenitor cell prevalence (cells/million cells) were calculated. Results: Aspirates of vertebral marrow demonstrated comparable or greater concentrations of progenitor cells compared with matched controls from the iliac crest. Progenitor cell concentrations were consistently higher than matched controls from the iliac crest (p = 0.05). The concentration of osteogenic progenitor cells was, on the average, 71% higher in the vertebral aspirates than in the paired iliac crest samples (p = 0.05). With the numbers available, there were no significant differences relative to vertebral body level, the side aspirated, the depth of aspiration, or gender. An age-related decline in cellularity was suggested for the iliac crest aspirates. Conclusions: The vertebral body is a suitable site for aspiration of bone marrow for graft augmentation during spinal arthrodesis. PMID:16322615

  11. Lateral Mass Fixation in the Subaxial Cervical Spine.

    PubMed

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

    2015-08-01

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

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

    PubMed

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

    2013-07-01

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

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

    PubMed Central

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

    2014-01-01

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

  14. Anatomic Consideration of the C1 Laminar Arch for Lateral Mass Screw Fixation via C1 Lateral Lamina : A Landmark between the Lateral and Posterior Lamina of the C1

    PubMed Central

    Kim, Jung-Hwan; Kwak, Dai-Soon; Han, Seung-Ho; Cho, Sung-Min; You, Seung-Hoon

    2013-01-01

    Objective To clarify the landmark for deciding the entry point for C1 lateral mass screws via the posterior arch by using 3-dimensional (3D) computed images. Methods Resnick insisted that the C1 posterior arch could be divided into pure posterior and lateral lamina (C1 pedicle). Authors studied where this transition point (TP) is located between the posterior lamina and the C1 pedicle and how it can be recognized. The 3D computed images of 86 cadaver C1s (M : F=45 : 41) were used in this study. Results The superior ridge of the C1 posterior arch had 2 types of orientation. One was in the vertical direction in the C1 posterior lamina and the other was in the horizontal direction in the C1 pedicle. The TP was located at the border between the 2 areas, the same site as the posterior end of the groove of the vertebral artery. On posterior-anterior projection, the posterior arch was sharpened abruptly at TP. We were unable to identify the TP in 6.4% of specimens due to complete or partial osseous bridges. A total of 93.8% of the TP were located between the most enlarged point of the spinal canal and the medial wall of the vertebral artery. Conclusion The anatomic entry zone of C1 lateral laminar screws was clarified and identified based on the TP by using preoperative 3D computed images. PMID:24044076

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

    PubMed Central

    2010-01-01

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

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

    SciTech Connect

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

    2013-06-15

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

  17. Fractures of the Proximal Fifth Metatarsal: Percutaneous Bicortical Fixation

    PubMed Central

    Mahajan, Vivek; Chung, Hyun Wook

    2011-01-01

    Background Displaced intraarticular zone I and displaced zone II fractures of the proximal fifth metatarsal bone are frequently complicated by delayed nonunion due to a vascular watershed. Many complications have been reported with the commonly used intramedullary screw fixation for these fractures. The optimal surgical procedure for these fractures has not been determined. All these observations led us to evaluate the effectiveness of percutaneous bicortical screw fixation for treating these fractures. Methods Twenty-three fractures were operatively treated by bicortical screw fixation. All the fractures were evaluated both clinically and radiologically for the healing. All the patients were followed at 2 or 3 week intervals till fracture union. The patients were followed for an average of 22.5 months. Results Twenty-three fractures healed uneventfully following bicortical fixation, with a mean healing time of 6.3 weeks (range, 4 to 10 weeks). The average American Orthopaedic Foot & Ankle Society (AOFAS) score was 94 (range, 90 to 99). All the patients reported no pain at rest or during athletic activity. We removed the implant in all cases at a mean of 23.2 weeks (range, 18 to 32 weeks). There was no refracture in any of our cases. Conclusions The current study shows the effectiveness of bicortical screw fixation for displaced intraarticular zone I fractures and displaced zone II fractures. We recommend it as one of the useful techniques for fixation of displaced zone I and II fractures. PMID:21629475

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

    PubMed Central

    Bowers, Andrea L.

    2008-01-01

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

  19. Absorbable Screws Versus Metallic Screws for Distal Tibiofibular Syndesmosis Injuries: A Meta-Analysis.

    PubMed

    Xie, Yuanlong; Cai, Lin; Deng, Zhouming; Ran, Bing; Hu, Chao

    2015-01-01

    A meta-analysis was performed to investigate the outcomes between absorbable screw (AS) and metallic screw (MS) fixation for distal tibiofibular syndesmosis injuries (DTSIs). Randomized controlled trials comparing AS versus MS fixation in DTSIs were searched systematically, and the outcomes were analyzed using Review Manager Software, version 5.2. The risk ratio (RR) or mean difference with the 95% confidence interval (CI) was calculated using the fixed effects or random effects model. A total of 16 studies were included in the meta-analysis. No statistically significant difference was found between AS and MS fixation in excellent and good functional recovery rate (RR 1.11, 95% CI 1.00 to 1.23, I(2) = 60%, p = .06), infection (RR 1.66, 95% CI 0.73 to 3.79, I(2) = 0%, p = .23), incidence of pain (RR 0.68, 95% CI 0.24 to 1.92, I(2) = 12%, p = .47), screw broken (RR 0.31, 95% CI 0.03 to 2.93, I(2) = %, p = .31), heterotopic ossification (RR 1.93, 95% CI 0.21 to 17.62, I(2) = 51%, p = .56; 472 cases in 4 studies), fracture healing time (mean difference -1.88, 95% CI -3.51 to -0.26, I(2) = 93%, p = .02,), duration of operation time (mean difference 7.64, 95% CI -3.80 to 19.09, I(2) = 98%, p = .19). The incidence of foreign body reaction was higher with AS fixation (RR 6.07, 95% CI 2.54 to 14.50, I(2) = 0%, p < .001). The reoperation rate was higher with MS fixation (RR 0.08, 95% CI 0.03 to 0.18, I(2) = 77%, p < .01). The functional outcomes of AS were as good as those with MS for DTSIs. Other than the foreign body reaction, the complications occurring after AS fixation were not as serious as those with MS fixation. AS fixation might be a preferable alternative for reconstruction of DTSIs. PMID:25956019

  20. Augmentation of implant fixation in osteoporotic bone.

    PubMed

    Jones, Clifford B

    2012-12-01

    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

  1. Influence of micro- and nano-hydroxyapatite coatings on the osteointegration of metallic (Ti6Al4 V) and bioabsorbable interference screws: an in vivo study.

    PubMed

    Aksakal, B; Kom, M; Tosun, H B; Demirel, M

    2014-07-01

    The purpose of this study is to show and compare the fixation and osteointegration capability of metallic and bioabsorbable interference screws. For this, 8×20-mm interference screws were implanted into the bone tunnel in the proximal tibial metaphysis of sheep. The nano- (25 nm±0.8) and microscale (25 ?m±0.5) hydroxyapatite were both dip-coated on Ti6Al4 V interference screws via an in vivo study. After the initial 12 weeks of postoperative, the pullout test, histopathology, X-ray diffraction and scanning electron microscopy examinations were performed. This multidisiplined work showed that the coated screws particularly those with nano-sized-HA coating and the bioabsorbable screws enhanced fixation and provided better stabilization, bone ingrowth and osteointegration than that of uncoated and microscale HA-coated screws. The bioabsorbable screws showed better histopathologic results. PMID:23689912

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

    PubMed Central

    2013-01-01

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

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

    PubMed Central

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

    2014-01-01

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

  4. Intra-operative computer navigation guided cervical pedicle screw insertion in thirty-three complex cervical spine deformities

    PubMed Central

    Rajasekaran, S.; Kanna, P. Rishi Mugesh; Shetty, T. Ajoy Prasad

    2010-01-01

    Background: Cervical pedicle screw fixation is challenging due to the small osseous morphometrics and the close proximity of neurovascular elements. Computer navigation has been reported to improve the accuracy of pedicle screw placement. There are very few studies assessing its efficacy in the presence of deformity. Also cervical pedicle screw insertion in children has not been described before. We evaluated the safety and accuracy of Iso-C 3D-navigated pedicle screws in the deformed cervical spine. Materials and Methods: Thirty-three patients including 15 children formed the study group. One hundred and forty-five cervical pedicle screws were inserted using Iso-C 3D-based computer navigation in patients undergoing cervical spine stabilization for craniovertebral junction anomalies, cervico-thoracic deformities and cervical instabilities due to trauma, post-surgery and degenerative disorders. The accuracy and containment of screw placement was assessed from postoperative computerized tomography scans. Results: One hundred and thirty (89.7%) screws were well contained inside the pedicles. Nine (6.1%) Type A and six (4.2%) Type B pedicle breaches were observed. In 136 levels, the screws were inserted in the classical description of pedicle screw application and in nine deformed vertebra, the screws were inserted in a non-classical fashion, taking purchase of the best bone stock. None of them had a critical breach. No patient had any neurovascular complications. Conclusion: Iso-C navigation improves the safety and accuracy of pedicle screw insertion and is not only successful in achieving secure pedicle fixation but also in identifying the best available bone stock for three-column bone fixation in altered anatomy. The advantages conferred by cervical pedicle screws can be extended to the pediatric population also. PMID:20890413

  5. Subclavian artery injury secondary to clavicular plate fixation: a novel operative approach

    PubMed Central

    Perera, Kalpa G.; Clifford, Celia; Maddock, Lachlan

    2015-01-01

    We present the case of a 32-year-old male with a delayed symptomatic left subclavian artery pseudoaneurysm secondary to protruding screws from prior perpendicular clavicular plate fixations. The pseudoaneurysm development and our operative approach are unique to the few similar cases available in the literature. The patient presented with a progressive pulsatile mass behind his left clavicle associated with paraesthesia. Angiography demonstrated a subclavian pseudoaneurysm adjacent to a prominent fixation screw. Offending screws were removed and the pseudoaneurysm was repaired using a reversed greater saphenous vein graft. This case illustrates an unusual aetiology for pseudoaneurysm development and highlights a successful operative intervention. PMID:25877827

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

    PubMed

    Demir, Teyfik

    2015-05-01

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

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

    PubMed

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

    2015-06-01

    This study reviews the outcomes and revision rates of degenerative lumbar fusion surgery using cortical trajectory pedicle screws in lieu of traditional pedicle screw instrumentation. Pedicle screw fixation can be a challenge in patients with low bone mineral density. Wide posterior approaches to the lumbar spine exposing lateral to the facet joints and onto transverse processes causes an additional degree of muscular damage and blood loss not present with a simple laminectomy. A cortical bone trajectory pedicle screw has been proposed as an alternative to prevent screw pullout and decrease the morbidity associated with the wide posterior approach to the spine. We present a series of eight consecutive patients using a cortical bone trajectory instead of traditional pedicle screw fixation for degenerative conditions of the lumbar spine. A retrospective review of our institutional registry data identified eight patients who had cortical screws placed with the assistance of O-arm Stealth navigation (Medtronic Sofamor Danek, Memphis, TN, USA) from 2010-2013. We analyzed the need for revision, the maintenance of reduction and the incidence of screw pullout or breakage. Our review demonstrated that two of eight patients were revised at an average of 12months. The reasons for these revisions were pseudarthrosis and caudal adjacent segment failure. All patients who were revised had frank screw loosening. We present early clinical results of a new technique that has been shown to have a better fixation profile in laboratory testing. Our less than favorable early clinical results should be interpreted with caution and highlight important technical issues which should be considered. PMID:25769253

  8. Comparison of plate-screw systems used in mandibular fracture reduction: finite element analysis.

    PubMed

    Lovald, Scott T; Khraishi, Tariq; Wagner, Jon; Baack, Bret; Kelly, James; Wood, John

    2006-10-01

    A finite element model of the human dentate mandible has been developed to provide a comparison of fixation systems used currently for fracture reduction. Volume domains for cortical bone, cancellous bone, and teeth were created and meshed in ANSYS 8.0 based on IGES curves created from computerized tomography data. A unilateral molar clench was loaded on the model with a fracture gap simulated along the symphysis. Results based on Von Mises stress in cortical and cancellous bone surrounding the screws, and on fracture surface spatial fixation, show some relative differences between different screw-plate systems, yet all were judged to be appropriate in their reduction potential. PMID:16995751

  9. Helical screw viscometer

    DOEpatents

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

    1983-06-30

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

  10. The utility of the fluoroscopic skyline view during volar locking plate fixation of distal radius fractures.

    PubMed

    Vaiss, Lucile; Ichihara, Satoshi; Hendriks, Sarah; Taleb, Chihab; Liverneaux, Philippe; Facca, Sybille

    2014-11-01

    Background?Open reduction and internal fixation (ORIF) using a volar locking plate is a common method for treating displaced distal radius fractures. There is, however, the risk of extensor tendon rupture due to protrusion of the screw tips past the dorsal cortex, which cannot always be adequately seen on a lateral fluoroscopic view. We therefore wished to compare the sensitivity of an intraoperative fluoroscopic skyline view to a lateral fluorosocopic view in detecting past pointing of these screws. Material and Methods?Our series included 75 patients with an average age of 59 years who underwent volar locked plate fixation of a displaced distal radius fracture. Intraoperative anteroposterior (AP), lateral, and skyline fluoroscopic views were performed in each case. The number of screws that were seen to protrude past the dorsal cortex of the distal fracture fragment were recorded for both the lateral and skyline views. The number of screws that required exchange was also documented. Results?No screws were seen to protrude past the dorsal cortical bone on the lateral fluroscopic views. 15 of 300 screws (5%) were seen to protrude past the dorsal cortex by an average of 0.8?mm (range, 0.5 to 2 mm) and were exchanged for shorter screws in 11/75 patients. Conclusion?Our results demonstrate that the skyline is more sensitive than a lateral fluoroscopic view at demonstrating protrusion of the screws in the distal fracture fragment following volar locked plate fixation. Level of Evidence?IV. PMID:25364637

  11. [Technical note: iliac crest bone graft harvesting in children].

    PubMed

    Bertrand, B; Philandrianos, C; Apostolou, N; Casanova, D; Bardot, J

    2014-06-01

    Harvesting iliac crest bone in children is special because of the presence of a thick cartilage. Constant pressure on the internal iliac fossa, ascends the skin, and moves the abdominal muscles away from the iliac crest. A single incision is then used for cutaneous and subcutaneous dissection. An internal piece of cartilage is then removed and the iliac muscle retracted in order to harvest cortical and spongy bone from the internal side of the iliac crest. That pièce of cartilage is then sutured at its initial place. During the harvesting, the surgeon needs to be careful to preserve the lateral femoral cutaneous nerve. PMID:24512894

  12. Subtrochanteric femur fracture after removal of screws for femoral neck fracture in a child.

    PubMed

    Song, Kwang Soon; Lee, Si Wook

    2015-01-01

    Displaced femoral neck fractures are rare in children and are associated with a high rate of complications. Subtrochanteric fractures after cannulated screw fixation of femoral neck fractures in adults are well recognized, and there are several reports on the topic. However, there are no reports on complications related to hardware or subtrochanteric fractures after removal of the screws in the treatment of femoral neck fractures in children. Here we report the case of a 10-year-old boy who sustained a subtrochanteric fracture after the screw removal and healing that followed a femoral neck fracture. PMID:25566556

  13. Numerical simulation research to both the external fixation surgery scheme of intertrochanteric fracture and the healing process, and its clinical application.

    PubMed

    Wang, Xian-Kang; Ye, Jin-Duo; Gu, Fu-Shun; Wang, Ai-guo; Zhang, Chun-Qiu; Tian, Qian-Qian; Li, Xue; Dong, Li-Min

    2014-01-01

    In this paper, the single arm external fixation of intertrochanteric fracture healing process after surgery was simulated to obtain a postoperative fracture healing and stress distribution in the external fixator. Firstly CT images of intertrochanteric fracture are reconstructed into the femur solid model. Then based, the external fixator is installed on the model, which lastly formed a finite element model of unilateral external fixation for intertrochanteric fracture. The calculated results show: during the beginning of the fracture healing, there is much higher stress in both screws and femur in the model with solid screws than that in the model with hollow screw. The stress of the femur in the model with hollow screw is more evenly. During the middle time of Fracture healing, stress in the femoral head significantly decreases. And the stress at fracture site gradually increased with the healing occurrence. According to the results, the authors designed hollow screws to use external fixation surgery. Surgery confirmed that the use of hollow screws in fractures treatment can satisfy the strength requirements, and can effectively reduce operative time, less patient suffering. The research for external fixation can provide a reference, and promote the use of external fixation hollow screws. PMID:24211947

  14. Treatment and complications in flaccid neuromuscular scoliosis (Duchenne muscular dystrophy and spinal muscular atrophy) with posterior-only pedicle screw instrumentation

    Microsoft Academic Search

    Hitesh N. Modi; Seung-Woo Suh; Jae-Young Hong; Jae-Woo Cho; Jong-Hoon Park; Jae-Hyuk Yang

    2010-01-01

    Literature has described treatment of flaccid neuromuscular scoliosis using different instrumentation; however, only one article\\u000a has been published using posterior-only pedicle screw fixation. Complications using pedicle screws in paralytic neuromuscular\\u000a scoliosis has not been described before. To present results and complications with posterior-only pedicle screws, a retrospective\\u000a study was carried out in 27 consecutive patients with flaccid neuromuscular scoliosis (Duchenne

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

    PubMed

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

    2015-09-01

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

  16. A novel fixation system for acetabular quadrilateral plate fracture: a comparative biomechanical study.

    PubMed

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

    2015-01-01

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

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

    PubMed

    Marie, Cronskär

    2015-08-01

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

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

    PubMed Central

    2014-01-01

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

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

    PubMed Central

    Jayakumar, Prakash; Ring, David

    2015-01-01

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

  20. The Screw-worm. 

    E-print Network

    Francis, M. (Mark)

    1890-01-01

    TEXAS AGRICULTURAL EXP II,HIMEXT Srl'ATION. BULLETIN No. 12, ~*fZkRP ** SEPTEMBER, 1890. .$, y~, 'TWORM. AGRICULTURAL' AND MECHANICAL COLLEGE OF TEXAS. All Bulletins of this Station are issued free. Any one interested... to Director. ,nt Agriculturist. . . naala~ant in Chemistrv. . . LVL~L~OI' . . Assists . . Assista A ..-:-A- TEXAS AGYLICULTUliAL EXYEliIMEXT STATION. THE SCREW-WORM. - . . . .. .-. -- M. FRANCIS, D. V. M. ~ - - In the First Annual Report...

  1. Drill Free Screws: a new form of osteosynthesis screw.

    PubMed

    Heidemann, W; Gerlach, K L; Gröbel, K H; Köllner, H G

    1998-06-01

    Although the application of self-tapping and non self-tapping screws is virtually universal in cranio-maxillofacial surgery, the inevitable, time consuming procedure of drilling a pilot hole has some potential disadvantages, such as damage to nerves, tooth roots or tooth germs, thermal necrosis of the bone and drill bit breakage. Drill Free Screws (DFS) are a recently developed type of osteosynthesis screws, having a tip like a cork screw and specially formed cutting flutes which enable insertion of the screws without drilling. DFS 1.5 and 2 mm were inserted into discs of wood, polyvinylchloride (PVC) and porcine mandibular bone of varying thicknesses between 2 and 4 mm. The values of insertion torque and maximum torque were recorded using an electric torque tester. Thereafter, the screws were inserted with a fixed torque and uniaxial pull out tests were performed. In comparison with this, the same procedure was performed using 1.5 and 2 mm self-tapping titanium screws. Ten trials for each screw-material-combination were conducted to determine insertion torque, maximum torque and pull out analysis. The results showed that the holding power of DFS lay between 70 and 104% of the holding power of self-tapping titanium screws; only in PVC was the difference more than 15%. PMID:9702635

  2. Tangential views of the articular surface of the distal radius—aid to open reduction and internal fixation of fractures

    Microsoft Academic Search

    Deepak Kumar; L Breakwell; S. C Deshmukh; B. K Singh

    2001-01-01

    Open reduction and internal fixation of comminuted, displaced intra-articular or potentially unstable fractures of the distal radius with plate and screws has increasingly become a favoured treatment. Intra-operative assessment of fixation with the help of an image intensifier has always been difficult because of the anatomy of the distal radius. Imaging of the implants placed as distal as possible to

  3. Bone registration method for robot assisted surgery: pedicle screw insertion.

    PubMed

    Abdel-Malek, K; McGowan, D P; Goel, V K; Kowalski, D; Smith, S B

    1997-01-01

    A registration method that identifies bone geometry with respect to a robotic manipulator arm is presented. Although the method is generally applicable to many orthopaedic internal fixation procedures, it was only demonstrated for the insertion of pedicle screws in vertebral bodies for spine fixation. The method relies upon obtaining an impression of the vertebral bodies. Computerized tomography (CT) scans of both vertebrae and mould are reconstructed using a computer aided engineering (CAE) system. From the reconstructions, the surgeon is able to do preoperative planning including selection of pedicle screw diameter, direction of screw through pedicle, point of entry and length of engagement. The three-dimensional models are than meshed to determine positions of the surgeon's preoperative plan relative to the mould. Intra-operative positions are defined in space by a mechanical fixture rigidly attached to the mould and designed to allow a manipulator end-effector to recognize the global coordinates of the in vivo spine. The theory and methodology were validated using a five-axis manipulator arm. This initial presentation assumes and allows no relative motion between vertebrae in vivo. PMID:9255999

  4. Low noise lead screw positioner

    NASA Technical Reports Server (NTRS)

    Perkins, Gerald S. (inventor)

    1986-01-01

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

  5. Reduced bone tunnel enlargement post hamstring ACL reconstruction with poly- l-lactic acid\\/hydroxyapatite bioabsorbable screws

    Microsoft Academic Search

    James Robinson; Chris Huber; Paul Jaraj; Philippe Colombet; Michel Allard; Philippe Meyer

    2006-01-01

    Bone tunnel enlargement following anterior cruciate ligament (ACL) reconstruction can complicate revision surgery. This study compared postoperative tibial tunnel widening in patients who underwent arthroscopically assisted, single-incision, four-strand hamstring ACL reconstruction using a poly-l-lactic acid\\/hydroxyapatite blend (PLLA+HA) bioabsorbable interference screw for tibial fixation, with those in whom a plain poly-l-lactic acid (PLLA) screw was used. Thirty-four patients (13 with PLLA+HA

  6. Radiographic Evaluation of Dorsal Screw Penetration After Volar Fixed-Angle Plating of the Distal Radius: A Cadaveric Study

    Microsoft Academic Search

    Steven D. Maschke; Peter J. Evans; David Schub; Richard Drake; Jeffrey N. Lawton

    2007-01-01

    Introduction  Extensor tendon irritation and attritional tendon ruptures are potentially serious complications after open reduction and\\u000a internal fixation of distal radius fractures. These complications are well recognized after dorsal plating of distal radii;\\u000a and these are now being reported after errant screw placement during volar fixed-angle plating. Intraoperative detection of\\u000a improper screw placement is critical, as corrective action can be taken

  7. Comparison of costs in ankle fractures treated with absorbable or metallic fixation devices

    Microsoft Academic Search

    T. Juutilainen; H. Pätiälä; M. Ruuskanen; P. Rokkanen

    1997-01-01

    The economic costs of ankle fractures treated operatively with self-reinforced polyglycolide acid (SR-PGA) screws, with self-reinforced poly-L-lactide acid (SR-PLLA) screws or with metallic implants was determined. All patients were divided into three groups according to the fixation material used. Open and otherwise complicated fractures were excluded. The total expense of operations in each group was taken into account. The average

  8. Spontaneous rupture of the left common iliac vein.

    PubMed

    Gaschignard, N; Le Paul, Y; Maouni, T; Le Priol, P D

    2000-09-01

    We report a case of spontaneous rupture of the left common iliac vein in a 58-year-old woman. Because of hemorrhagic shock, the intervention had to be performed under emergency circumstances, precluding repair of the external iliac vein, which was ligated. The postoperative course was uneventful. We also review the 17 prior cases found in the literature. PMID:10990565

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

    PubMed

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

    2014-09-01

    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

  10. Validation of an improved method to calculate the orientation and magnitude of pedicle screw bending moments.

    PubMed

    Freeman, Andrew L; Fahim, Mina S; Bechtold, Joan E

    2012-10-01

    Previous methods of pedicle screw strain measurement have utilized complex, time consuming methods of strain gauge application, experience high failure rates, do not effectively measure resultant bending moments, and cannot predict moment orientation. The purpose of this biomechanical study was to validate an improved method of quantifying pedicle screw bending moment orientation and magnitude. Pedicle screws were instrumented to measure biplanar screw bending moments by positioning four strain gauges on flat, machined surfaces below the screw head. Screws were calibrated to measure bending moments by hanging certified weights a known distance from the strain gauges. Loads were applied in 30?deg increments at 12 different angles while recording data from two independent strain channels. The data were then analyzed to calculate the predicted orientation and magnitude of the resultant bending moment. Finally, flexibility tests were performed on a cadaveric motion segment implanted with the instrumented screws to demonstrate the implementation of this technique. The difference between the applied and calculated orientation of the bending moments averaged (±standard error of the mean (SEM)) 0.3?±?0.1?deg across the four screws for all rotations and loading conditions. The calculated resultant bending moments deviated from the actual magnitudes by an average of 0.00?±?0.00 Nm for all loading conditions. During cadaveric testing, the bending moment orientations were medial/lateral in flexion-extension, variable in lateral bending, and diagonal in axial torsion. The technique developed in this study provides an accurate method of calculating the orientation and magnitude of screw bending moments and can be utilized with any pedicle screw fixation system. PMID:23083202

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

    PubMed

    Choi, Sungwook; Kang, Hyunseong; Bang, Hyeongsig

    2014-08-01

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

  12. Early fracture of a bioabsorbable tibial interference screw after ACL reconstruction with subsequent chondral injury.

    PubMed

    Hall, Michael P; Hergan, David M; Sherman, Orrin H

    2009-03-01

    Graft fixation in anterior cruciate ligament (ACL) reconstruction is commonly performed with bioabsorbable devices. This article presents a case of a broken bioabsorbable tibial interference screw (Gentle Threads; Biomet, Warsaw, Indiana) that presented as an intra-articular loose body 4 months after ACL reconstruction with posterior tibialis tendon allograft. A 19-year-old man presented with symptoms of pain and catching for 1 week but reported no history of trauma. The broken screw tip was identified on magnetic resonance imaging examination, and the remaining screw appeared to be overinserted into the tibia. During arthroscopic removal, a 10-mm screw tip was found in the lateral gutter. The ACL graft was found to be well fixed, but small areas of chondral damage were found in the patellofemoral and medial compartment. The patient's symptoms resolved postoperatively. To our knowledge, this is the earliest report of a broken bioabsorbable interference screw and only the second report of subsequent chondral injury due to intra-articular migration. Although rare, late breakage and intra-articular migration of bioabsorbable interference screws should be considered during the postoperative evaluation of any patient with pain or mechanical symptoms, regardless of trauma. This case also supports the importance of both measurement of tibial tunnel length and inspection of the intercondylar notch following interference screw insertion. Orthopedic surgeons performing ACL reconstruction must be aware of this possible complication and its potential for devastating chondral injury. PMID:19309052

  13. Occipital condyle screw placement and occipitocervical instrumentation using three-dimensional image-guided navigation.

    PubMed

    Le, Tien V; Burkett, Clint; Ramos, Edwin; Uribe, Juan S

    2012-05-01

    Occipital condyle (OC) screws are an alternative cephalad fixation point in occipitocervical fusion. Safe placement of occipital, C1 lateral mass, and C2 pars screws have been described previously, but not OC screws. The craniocervical junction is complex, and a thorough understanding of the anatomy is needed. Three-dimensional (3D) image-guided navigation was used in six patients. There were no complications related to image-guided navigation during the placement of 12 OC screws and we found that this navigation can serve as a useful adjunct when placing an OC screw. Technical considerations of placing OC and C1 lateral mass screws are discussed with particular reference to patient positioning and the StealthStation® S7™ image-guided navigational platform (Medtronic, Minneapolis, MN, USA). The reference arc is attached to the head-clamp and faces forward. The optical camera and monitor are positioned at the head of the table for a direct, non-obstructed line-of-sight. To minimize intersegmental movement, the OC should not be drilled until all other screws have been placed. We conclude that 3D image-guided navigation is a useful adjunct that can be safely and effectively used for placement of instrumentation of the upper cervical spine including the OC. PMID:22356730

  14. Placement of C2 laminar screws using three-dimensional fluoroscopy-based image guidance

    PubMed Central

    Foy, Andrew B.

    2007-01-01

    The use of C2 laminar screws in posterior cervical fusion is a relatively new technique that provides rigid fixation of the axis with minimal risk to the vertebral artery. The techniques of C2 laminar screw placement described in the literature rely solely on anatomical landmarks to guide screw insertion. The authors report on their experience with placement of C2 laminar screws using three-dimensional (3D) fluoroscopy-based image-guidance in eight patients undergoing posterior cervical fusion. Overall, fifteen C2 laminar screws were placed. There were no complications in any of the patients. Average follow-up was 10 months (range 3–14 months). Postoperative computed tomographic (CT) scanning was available for seven patients allowing evaluation of placement of thirteen C2 laminar screws, all of which were in good position with no spinal canal violation. The intraoperative planning function of the image-guided system allowed for 4-mm diameter screws to be placed in all cases. Using modified Odom’s criteria, excellent or good relief of preoperative symptoms was noted in all patients at final follow-up. PMID:18034268

  15. An Innovative Universal Screw Removal Instrument

    PubMed Central

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

    2015-01-01

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

  16. Is the Etiology of Pretibial Cyst Formation After Absorbable Interference Screw Use Related to a Foreign Body Reaction?

    Microsoft Academic Search

    Guillem Gonzalez-Lomas; Ryan T. Cassilly; Fabrizio Remotti; William N. Levine

    2011-01-01

    Background  Arthroscopically assisted anterior cruciate ligament reconstruction using a bioabsorbable tibial fixation screw is occasionally\\u000a complicated by pretibial cyst formation. The few case reports describing pretibial cyst formation noted several graft types\\u000a and fixation techniques, making it difficult to establish one etiology. Some literature suggests cysts form from communication\\u000a between the joint and pretibial area leading to extravasation of joint fluid,

  17. Simple coating with fibronectin fragment enhances stainless steel screw osseointegration in healthy and osteoporotic rats.

    PubMed

    Agarwal, Rachit; González-García, Cristina; Torstrick, Brennan; Guldberg, Robert E; Salmerón-Sánchez, Manuel; García, Andrés J

    2015-09-01

    Metal implants are widely used to provide structural support and stability in current surgical treatments for bone fractures, spinal fusions, and joint arthroplasties as well as craniofacial and dental applications. Early implant-bone mechanical fixation is an important requirement for the successful performance of such implants. However, adequate osseointegration has been difficult to achieve especially in challenging disease states like osteoporosis due to reduced bone mass and strength. Here, we present a simple coating strategy based on passive adsorption of FN7-10, a recombinant fragment of human fibronectin encompassing the major cell adhesive, integrin-binding site, onto 316-grade stainless steel (SS). FN7-10 coating on SS surfaces promoted ?5?1 integrin-dependent adhesion and osteogenic differentiation of human mesenchymal stem cells. FN7-10-coated SS screws increased bone-implant mechanical fixation compared to uncoated screws by 30% and 45% at 1 and 3 months, respectively, in healthy rats. Importantly, FN7-10 coating significantly enhanced bone-screw fixation by 57% and 32% at 1 and 3 months, respectively, and bone-implant ingrowth by 30% at 3 months compared to uncoated screws in osteoporotic rats. These coatings are easy to apply intra-operatively, even to implants with complex geometries and structures, facilitating the potential for rapid translation to clinical settings. PMID:26100343

  18. Histoplasma complement fixation

    MedlinePLUS

    Histoplasma complement fixation is a blood test that checks for infection due to a fungus called Histoplasma capsulatum ( H. ... for Histoplasma antibodies using a laboratory method called complement fixation. This technique checks if your body has ...

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

    Microsoft Academic Search

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

    2009-01-01

    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):\\u000a a fusion without reduction of the spondylolisthesis. Fixation of the segment was achieved by two cancellous bone screws inserted\\u000a bilaterally through the pedicles of the lower vertebra into the body of the upper slipped vertebra. Since 1998

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

    PubMed

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

    2014-01-01

    This report describes the use of custom-positioned vertical screws (CVS) to attach primary telescopic crowns to implant abutments. In a private practice setting, 37 patients with 40 double crown-retained implant overdentures (IODs) with a clearance fit (Marburg double crowns) were followed. All primary crowns on the 120 implant abutments were retained using CVS. After a mean followup period of 3.55 ± 1.37 years (range: 1.5 to 6.3 years), one abutment screwloosening incident was reported (incidence: 0.08%). No loosening of any of the screw-retained primary crowns occurred. CVS may represent a viable fixation concept for IODs. PMID:25390875

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

    PubMed

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

    2014-11-23

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

  2. Biomechanical evaluation of a new fixation device for the thoracic spine.

    PubMed

    Hongo, Michio; Ilharreborde, Brice; Gay, Ralph E; Zhao, Chunfeng; Zhao, Kristin D; Berglund, Lawrence J; Zobitz, Mark; An, Kai-Nan

    2009-08-01

    The technology used in surgery for spinal deformity has progressed rapidly in recent years. Commonly used fixation techniques may include monofilament wires, sublaminar wires and cables, and pedicle screws. Unfortunately, neurological complications can occur with all of these, compromising the patients' health and quality of life. Recently, an alternative fixation technique using a metal clamp and polyester belt was developed to replace hooks and sublaminar wiring in scoliosis surgery. The goal of this study was to compare the pull-out strength of this new construct with sublaminar wiring, laminar hooks and pedicle screws. Forty thoracic vertebrae from five fresh frozen human thoracic spines (T5-12) were divided into five groups (8 per group), such that BMD values, pedicle diameter, and vertebral levels were equally distributed. They were then potted in polymethylmethacrylate and anchored with metal screws and polyethylene bands. One of five fixation methods was applied to the right side of the vertebra in each group: Pedicle screw, sublaminar belt with clamp, figure-8 belt with clamp, sublaminar wire, or laminar hook. Pull-out strength was then assessed using a custom jig in a servohydraulic tester. The mean failure load of the pedicle screw group was significantly larger than that of the figure-8 clamp (P = 0.001), sublaminar belt (0.0172), and sublaminar wire groups (P = 0.04) with no significant difference in pull-out strength between the latter three constructs. The most common mode of failure was the fracture of the pedicle. BMD was significantly correlated with failure load only in the figure-8 clamp and pedicle screw constructs. Only the pedicle screw had a statistically significant higher failure load than the sublaminar clamp. The sublaminar method of applying the belt and clamp device was superior to the figure-8 method. The sublaminar belt and clamp construct compared favorably to the traditional methods of sublaminar wires and laminar hooks, and should be considered as an alternative fixation device in the thoracic spine. PMID:19404687

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

    PubMed Central

    2014-01-01

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

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

    PubMed

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

    2014-01-01

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

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

    PubMed

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

    2013-10-01

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

  6. A comparison of stress distributions for different surgical procedures, screw dimensions and orientations for a Temporomandibular joint implant

    Microsoft Academic Search

    Amit Roy Chowdhury; Ajay Kashi; Subrata Saha

    2011-01-01

    Finite element analysis is a useful analytical tool for the design of biomedical implants. The aim of this study was to investigate the behavior of temporomandibular joint implants with multiple design variables of the screws used for fixation of the implant. A commercially available implant with full mandible was analyzed using a finite element software package. The effects of different

  7. Lateral mass fixation in subaxial cervical spine: anatomic review.

    PubMed

    Mohamed, Elrahmany; Ihab, Zidan; Moaz, Anwar; Ayman, Nabawi; Haitham, Abo-Elw

    2012-03-01

    Introduction?The cervical spine is a highly mobile segment of the spinal column, liable to a variety of diseases and susceptible to trauma. It is a complex region where many vital structures lie in close proximity. Lateral mass screw fixation has become the method of choice in stabilizing subaxial cervical spine among other posterior cervical fixation techniques whenever the posterior elements are absent or compromised. Objective?This study examined cervical specimens of cadavers and cervical computed tomography (CT) scans to minimize as much as possible complications of cervical lateral mass screw placement such as vertebral artery or nerve root injuries, facet joint violations, or inadequate placement. Methods?Forty normal cervical CT scans, obtained from the emergency unit as part of the trauma workup, were included in this study plus 10 cervical cadaveric specimens obtained from the Alexandria Neuro-anatomy laboratory. There were three fixed parameters for screw insertion in this study. First, the point of screw insertion was the midpoint of the lateral mass; it was the crossing point between the sagittal and axial planes of the posterior cortex of the lateral mass. Second, the direction of the screw in the craniocaudal plane was 30 degrees cranially to avoid facet joint penetration. Third, the exit point of the screw was located on the ventral cortex of the lateral mass just lateral to the root of the transverse process in the midaxial cut of each lateral mass, to make a sound bicortical fixation without injuring the vertebral artery or the nerve root. The selected screw trajectory in this study was the line drawn between the inlet and exit points. The depth and width of the lateral mass of the cervical vertebrae from C3 to C7 were measured as well as the angle of screw trajectory from the sagittal plane. All these measures were applied on the cadaveric specimens to make sure that no injury to the vertebral artery, nerve root, or facet joint occurred. Results?As regards the collected measurements of the lateral mass of all subaxial cervical vertebrae, the study revealed that the average depth of the lateral mass was 12.83?±?1.28 mm. The average width of the lateral mass was 11.92?±?0.96 mm. The average divergent angle of bicortical screw insertion without injury to the vertebral artery or the nerve root was 19.51?±?1.83 degrees. As regard the cadaveric specimens, based on all the collected measurements taken from the CT scans, there was no reported injury to the vertebral arteries or nerve roots or penetration to the facet joints. Conclusion?Lateral mass fixation can be applied easily and safely for all levels of subaxial cervical spine from C3 to C6 with the following parameters: (1) the point of entry is the midpoint of the lateral mass; (2) the screw trajectory is directed 30 degrees cranially and 20 degrees laterally; (3) the screw length is 13 to 15 mm. PMID:24353945

  8. Soft Tissue Tendon Graft Fixation in Serially Dilated or Extraction-Drilled Tibial TunnelsA Porcine Model Study Using High-Resolution Quantitative Computerized Tomography

    Microsoft Academic Search

    Brad S. Dunkin; John Nyland; Andrew R. Duffee; Jeffrey A. Brunelli; Robert Burden; David Caborn

    2007-01-01

    Background: Tibial tunnel preparation may contribute to improved soft tissue graft fixation.Hypothesis: Step dilation produces greater tunnel wall bone volume than does extraction drilling and increases fixation strength. Bioabsorbable interference screw divergence decreases fixation strength, regardless of tunnel preparation method.Study Design: Controlled laboratory study.Methods: Twenty porcine tibias were divided into 2 groups of 10 with matching mean apparent bone mineral

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

    Microsoft Academic Search

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

    1998-01-01

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

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

    Microsoft Academic Search

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

    2000-01-01

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

  11. Direct pediculo-body fixation in cases of spondylolisthesis with advanced intervertebral disc degeneration

    Microsoft Academic Search

    D. Grob; T. Humke; J. Dvorak

    1996-01-01

    In inveterate cases of grade 2–3 spondylolisthesis (degenerative or spondylolytic), segmental mobility may be reduced by radiologically confirmed disc resorption. Fusion may be indicated in patients with persistent pain. A simple technique for fusion without reduction of the spondylolisthesis is presented. Fixation of the segment is achieved by two cancellous bone screws inserted bilaterally through the pedicles of the lower

  12. Computer-Assisted Percutaneous Scaphoid Fixation: Concepts and Evolution

    PubMed Central

    Smith, Erin J.; Ellis, Randy E.; Pichora, David R.

    2013-01-01

    Background?The treatment for undisplaced scaphoid waist fractures has evolved from conventional cast immobilization to percutaneous screw insertion. Percutaneous fixation reduces some of the risks of open surgery, but can be technically demanding and carries the risk of radiation exposure. Recently, computer-assisted percutaneous scaphoid fixation (CAPSF) has been gaining interest. Materials and Methods?Conventional percutaneous scaphoid fixation is performed under fluoroscopic guidance and involves insertion of a guide wire along the length of the scaphoid to facilitate placement of a cannulated screw. Adapting computer-assisted techniques for scaphoid fixation poses several unique challenges including patient tracking and registration. Results?To date, five groups have successfully implemented systems for CAPSF. These systems have implemented wrist immobilization strategies to resolve the issue of patient tracking and have developed unique guidance techniques incorporating 2D fluoroscope, cone-beam CT, and ultrasound, to circumvent patient-based registration. Conclusions?Computer-aided percutaneous pinning of scaphoid waist fractures can significantly reduce radiation exposure and has the potential to improve the accuracy of this procedure. This article reviews the rationale for, and the evolution of, CAPSF and describes the key principles of computer-assisted technology. PMID:24436833

  13. Expandable insert serves as screw anchor

    NASA Technical Reports Server (NTRS)

    1966-01-01

    Expandable self-locking adapter secures components to panels having one accessible side. Mounting holes in the panels may not be threaded to accommodate screws, therefore, the adapter contains a female thread that will mate a mounting screw.

  14. Limiting the dimension of a screw-access hole with an interim screw-retained prosthesis.

    PubMed

    Wadhwani, Chandur; Chung, Kwok-Hung

    2015-06-01

    Fabricating an interim screw-retained prosthesis often involves obliteration of the abutment screw access site, which later must be exposed. This frequently results in excessive preparation of the screw access site with poor esthetics and a weaker restoration. The technique described expedites the process by locating the access site and limits the size of the screw access hole preparation. PMID:25858223

  15. Screw symmetry in columnar crystals

    E-print Network

    A. Mughal

    2013-06-12

    We show that the optimal packing of hard spheres in an infinitely long cylinder yields structures characterised by a screw symmetry. Each packing can be assembled by stacking a basic unit cell ad infinitum along the length of the cylinder with each subsequent unit cell rotated by the same twist angle with respect to the previous one. In this paper we quantitatively describe the nature of this screw operation for all such packings in the range 1 <= D/d <= 2.715 and also briefly discuss their helicity.

  16. Design of a head fixation device for experiments in behaving monkeys.

    PubMed

    Isoda, Masaki; Tsutsui, Ken-Ichiro; Katsuyama, Narumi; Naganuma, Tomoka; Saito, Naohiro; Furusawa, Yoshihito; Mushiake, Hajime; Taira, Masato; Tanji, Jun

    2005-02-15

    We have designed a new device for head fixation of behaving monkeys. The fixation device consists of a duralumin head ring mounted with four screw holders. It is firmly fixed to the animal's skull with four stainless steel screw pins. The head ring is then attached to a primate chair in any desirable position and angle using a set of adjustable plates. The device has been used for behavioral training that requires accurate gaze monitoring and for recording single-unit activity over a several-month period. The advantage of our device is that it is simple to use; it can be attached readily without major surgical procedures and it can be quickly removed when experiments are not running. This head fixation system is suitable for behavioral experiments and single-unit recording studies. It may also be applicable for studies on functional imaging of the macaque brain, by constructing it of non-magnetic materials. PMID:15661310

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

    PubMed Central

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

    2010-01-01

    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

  18. An eigenproblem approach to classical screw theory

    Microsoft Academic Search

    Sandipan Bandyopadhyay; Ashitava Ghosal

    2009-01-01

    This paper presents a novel algebraic formulation of the central problem of screw theory, namely the determination of the principal screws of a given system. Using the algebra of dual numbers, it shows that the principal screws can be determined via the solution of a generalised eigenproblem of two real, symmetric matrices. This approach allows the study of the principal

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

    PubMed Central

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

    2014-01-01

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

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

    PubMed Central

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

    2008-01-01

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

  1. Guide to radiation fixatives

    SciTech Connect

    Tawil, J.J.; Bold, F.C.

    1983-11-01

    This report identifies and then characterizes a variety of substances available in the market place for potential effectiveness as a fixative on radiologically contaminated surfaces. The substances include both generic chemicals and proprietary products. In selecting a fixative for a particular application, several attributes of the fixative may be relevant to the choice. These attributes include: toxicity, durability, and cleanliness and removability. In addition to the attributes of the fixative, one should also take into account certain characteristics of the site to be treated. These characteristics relate to climate, nature of the surface, use to which the treated surface will be put, subsequent cleanup operations, and type of neighboring surfaces. Finally, costs and potential environmental effects may influence the decision. A variety of fixatives are evaluated with respect to these various attributes and summarized in a reference table.

  2. A screw propelling capsule robot

    Microsoft Academic Search

    Huajin Liang; Yisheng Guan; Zhiguang Xiao; Chao Hu; Zhiyong Liu

    2011-01-01

    This paper presents a novel approach to active capsule robot, traversing in a tubular and compliant environment containing solid-liquid mixture. One of the application fields is active capsule endoscopy intended to navigate inside the gastrointestinal tract for diagnosis and therapy. This robot is driven by a screw impeller, which converts rotation to axial motion in two ways: one is through

  3. Air-Lubricated Lead Screw

    NASA Technical Reports Server (NTRS)

    Perkins, G. S.

    1983-01-01

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

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

    PubMed Central

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

    2015-01-01

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

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

    PubMed Central

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

    2014-01-01

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

  6. Minimally Invasive Pedicle Screw Placement in A Case of L4 Fracture: Case Report with Review of Literature

    PubMed Central

    Agrawal, Abhishek; Mizuno, Junichi; Kato, Yoko; Inoue, Tatsushi; Sano, Hirotoshi

    2010-01-01

    Introduction: Pedicle screw instrumentation provides a rigid construct to promote fusion in cases of spinal trauma and degenerative diseases. Minimally invasive percutaneous technique in lumbar spine is a safe and reliable procedure as compared to the well established Magerl technique. It is a straight forward alternative to open approaches or minimally invasive ones and the accuracy of screw placement is also similar to that reported for other techniques. Case Report: A 16 year old high school boy presented to us with accidental fall from third floor. He was suffering from common cold with resulting high fever. He developed low back ache with bilateral radiculopathy and weakness of dorsiflexors. Neuro-imaging revealed a burst fracture of L4 vertebral body (type A 3.3 according to Magerl/AO spine classification), with bone fragments compromising the spinal canal. Delayed surgery was planned in view of anticipated excessive bleeding from the wound site in addition to poor general condition. Using a bone impactor, the bony fragments were impacted back into the original vertebral body space. Sextant (Medtronic Sofamor Danek, Tennessee, USA) percutaneous pedicle screw and rod fixation device was then used as a rigid construct to stabilize the lumbar spine. Post-operative CT scan and MRI revealed accurate pedicle screw fixation with adequately decompressed spinal canal. Conclusion: Short segment fusion with minimally invasive pedicle screwing following decompression of cauda equina was considered to be a minimally invasive approach for this case. PMID:22028760

  7. Acute changes in the pacing threshold after lead implantation. Comparison between retractable and sweet-tip active-fixation leads.

    PubMed

    Kashiwase, Kazunori; Kobayashi, Hiroshi; Hirata, Akio; Wada, Mitsuru; Nakanishi, Hiroyuki; Ueda, Yasunori

    2012-01-01

    Although the pacing threshold of steroid-eluting active-fixation leads remains stable over the long term, it changes rapidly after screw-in. We compared the pacing threshold in the acute phase between retractable and Sweet-Tip active-fixation leads. We studied 132 patients who were implanted with active-fixation leads for new pacemaker implantation or additional leads required due to disconnected/leaking leads. Pacing threshold was measured at 4 time points: before screw-in, immediately, and 5 and 10 minutes after screw-in. If the pacing threshold was > 1.5 volts (V) at 5 minutes, we changed the pacing site so that it became ? 1.5 V. A total of 169 retractable leads (Medtronic: 107 leads, St. Jude Medical: 62 leads) and 33 Sweet-Tip leads (Boston: 33 leads) were implanted. Eighty-nine leads were implanted in the atrium and 113 leads in the ventricle. Seventy patients were implanted with both atrial and ventricular leads. The pacing threshold of Sweet-Tip leads increased immediately after screw-in, while that of retractable leads decreased (Sweet-Tip: 0.20 ± 0.57 V, Retractable: -0.15 ± 0.53 V, P < 0.05). The pacing threshold of both types of leads decreased similarly from immediately to 5 minutes after screw-in (Sweet Tip: -0.29 ± 0.43 V, Retractable: -0.25 ± 0.36 V, P = NS). Few changes in the threshold were detected between 5 and 10 minutes. Because the pacing threshold of Sweet-Tip active-fixation leads increased immediately after screw-in and that of both type leads decreased from immediately to 5 minutes, we should measure the pacing threshold from 5 minutes after screw-in. PMID:22688314

  8. Evaluation of unilateral cage-instrumented fixation for lumbar spine

    PubMed Central

    2010-01-01

    Background To investigate how unilateral cage-instrumented posterior lumbar interbody fusion (PLIF) affects the three-dimensional flexibility in degenerative disc disease by comparing the biomechanical characteristics of unilateral and bilateral cage-instrumented PLIF. Methods Twelve motion segments in sheep lumbar spine specimens were tested for flexion, extension, axial rotation, and lateral bending by nondestructive flexibility test method using a nonconstrained testing apparatus. The specimens were divided into two equal groups. Group 1 received unilateral procedures while group 2 received bilateral procedures. Laminectomy, facectomy, discectomy, cage insertion and transpedicle screw insertion were performed sequentially after testing the intact status. Changes in range of motion (ROM) and neutral zone (NZ) were compared between unilateral and bilateral cage-instrumented PLIF. Results Both ROM and NZ, unilateral cage-instrumented PLIF and bilateral cage-instrumented PLIF, transpedicle screw insertion procedure did not revealed a significant difference between flexion-extension, lateral bending and axial rotation direction except the ROM in the axial rotation. The bilateral group's ROM (-1.7 ± 0. 8) of axial rotation was decreased significantly after transpedicle screw insertion procedure in comparison with the unilateral group (-0.2 ± 0.1). In the unilateral cage-instrumented PLIF group, the transpedicle screw insertion procedure did not demonstrate a significant difference between right and left side in the lateral bending and axial rotation direction. Conclusions Based on the results of this study, unilateral cage-instrumented PLIF and bilateral cage-instrumented PLIF have similar stability after transpedicle screw fixation in the sheep spine model. The unilateral approach can substantially reduce exposure requirements. It also offers the biomechanics advantage of construction using anterior column support combined with pedicle screws just as the bilateral cage-instrumented group. The unpleasant effect of couple motion resulting from inherent asymmetry was absent in the unilateral group. PMID:21070626

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

    PubMed Central

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

    2014-01-01

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

  10. Safe Osteocutaneous Radial Forearm Flap Harvest with Prophylactic Internal Fixation

    PubMed Central

    Shnayder, Yelizaveta; Tsue, Terance T.; Toby, E. Bruce; Werle, Andreas H.; Girod, Douglas A.

    2011-01-01

    We studied the efficacy of prophylactic plate fixation technique and a modified harvest of the osteocutaneous radial forearm free flap (OCRFFF) to minimize the incidence of postoperative donor radius pathological fracture. We retrospectively studied of the first 70 consecutive patients undergoing OCRFFF harvest by the University of Kansas Head and Neck Microvascular Reconstruction Team. Mean follow-up was 13 months. One of two patients undergoing OCRFFF harvest without prophylactic fixation developed a pathological radius fracture. The 68 subsequent OCRFFF patients underwent prophylactic fixation of the donor radius, and none developed a symptomatic radius fracture. Five of 68 patients did have a radiographically visible fracture requiring no intervention. The plate fixation technique was further modified to exclude monocortical screws in the radius bone donor defect (subsequent 39 patients), without any further fractures detected. One patient required forearm hardware removal for an attritional extensor tendon tear. The described modified OCRFFF harvest and prophylactic plate fixation technique may eliminate postoperative pathological fracture of the donor radius. Donor morbidity is similar to that of the fasciocutaneous radial forearm free flap , affording safe use of OCRFFF in head and neck reconstruction. PMID:22942941

  11. Safe osteocutaneous radial forearm flap harvest with prophylactic internal fixation.

    PubMed

    Shnayder, Yelizaveta; Tsue, Terance T; Toby, E Bruce; Werle, Andreas H; Girod, Douglas A

    2011-09-01

    We studied the efficacy of prophylactic plate fixation technique and a modified harvest of the osteocutaneous radial forearm free flap (OCRFFF) to minimize the incidence of postoperative donor radius pathological fracture. We retrospectively studied of the first 70 consecutive patients undergoing OCRFFF harvest by the University of Kansas Head and Neck Microvascular Reconstruction Team. Mean follow-up was 13 months. One of two patients undergoing OCRFFF harvest without prophylactic fixation developed a pathological radius fracture. The 68 subsequent OCRFFF patients underwent prophylactic fixation of the donor radius, and none developed a symptomatic radius fracture. Five of 68 patients did have a radiographically visible fracture requiring no intervention. The plate fixation technique was further modified to exclude monocortical screws in the radius bone donor defect (subsequent 39 patients), without any further fractures detected. One patient required forearm hardware removal for an attritional extensor tendon tear. The described modified OCRFFF harvest and prophylactic plate fixation technique may eliminate postoperative pathological fracture of the donor radius. Donor morbidity is similar to that of the fasciocutaneous radial forearm free flap , affording safe use of OCRFFF in head and neck reconstruction. PMID:22942941

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

    PubMed

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

    2015-07-01

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

  13. Iliac anatomy and the incidence of adjunctive maneuvers during endovascular abdominal aortic aneurysm repair

    PubMed Central

    Park, Kihyuk

    2015-01-01

    Purpose Challenging iliac anatomy remains an important issue during endovascular aneurysm repair (EVAR), and it is known that the length of the common iliac artery (CIA) is shorter in Asians than in Western groups. We analyzed both the iliac anatomy and the incidence of adjunctive maneuvers to overcome iliac artery-related difficulties during EVAR. Methods Seventy-four EVARs were performed for abdominal aortic aneurysm between January 2010 and March 2013. Patient demographic data, iliac anatomical characteristics (presence of iliac artery aneurysm, iliac artery diameter and length, and iliac tortuosity), and adjunctive iliac artery maneuvers were reviewed retrospectively. Results Mean CIA length was 52.8 mm (range, 6.6-98.0 mm) on the right and 56.3 mm (range, 0-94.8 mm) on the left. CIA length was ?20 mm, except in one patient with bilateral short CIAs. Forty patients (54%) had a CIA aneurysm, and 18 had aneurysms on both sides. Iliac adjunctive procedures were performed in 38 patients (51%) as follows: 23 internal iliac artery (IIA) embolizations or ligations, seven IIA revascularizations, 16 external iliac artery (EIA) balloon angioplasties or stenting, one EIA patch angioplasty, one EIA interposition, two femoral endarterectomies with patch angioplasty, and nine femoro-femoral bypasses after EVAR with an aorto-uni-iliac device. Technical success for the adjunctive iliac procedures was achieved in all patients. Conclusion Short CIA length was uncommon. Although many patients had access-related difficulties, most were overcome by an endovascular or hybrid technique. Liberal use of iliac adjunctive procedures can facilitate EVAR.

  14. [The Herbert screw in pseudoarthrosis of the carpal scaphoid].

    PubMed

    Massart, P; Tazi, F; Finet, P; Bèzes, H

    1990-01-01

    For nearly three years, the authors have ensured scaphoid union by fixation with a double thread T.J. Herbert's screw. In these 25 cases a cancellous bone graft was used to fill the defect which would have left shortening of the scaphoid Twenty-two of the 25 cases, obtained rapid union, and 20 had a good or very good clinical result. One doubtful union and two cases of non-union occurred. One of these non-unions required revision. The main advantage of this procedure is to allow early mobilization of the wrist. This early is very appreciated by the patients who were immobilized several months by conservative treatment for their initial fracture. PMID:1703425

  15. Helical screw expander evaluation project

    NASA Technical Reports Server (NTRS)

    Mckay, R.

    1982-01-01

    A one MW helical rotary screw expander power system for electric power generation from geothermal brine was evaluated. The technology explored in the testing is simple, potentially very efficient, and ideally suited to wellhead installations in moderate to high enthalpy, liquid dominated field. A functional one MW geothermal electric power plant that featured a helical screw expander was produced and then tested with a demonstrated average performance of approximately 45% machine efficiency over a wide range of test conditions in noncondensing, operation on two-phase geothermal fluids. The Project also produced a computer equipped data system, an instrumentation and control van, and a 1000 kW variable load bank, all integrated into a test array designed for operation at a variety of remote test sites. Data are presented for the Utah testing and for the noncondensing phases of the testing in Mexico. Test time logged was 437 hours during the Utah tests and 1101 hours during the Mexico tests.

  16. Helical screw expander evaluation project

    NASA Astrophysics Data System (ADS)

    McKay, R.

    1982-03-01

    A one MW helical rotary screw expander power system for electric power generation from geothermal brine was evaluated. The technology explored in the testing is simple, potentially very efficient, and ideally suited to wellhead installations in moderate to high enthalpy, liquid dominated field. A functional one MW geothermal electric power plant that featured a helical screw expander was produced and then tested with a demonstrated average performance of approximately 45% machine efficiency over a wide range of test conditions in noncondensing, operation on two-phase geothermal fluids. The Project also produced a computer equipped data system, an instrumentation and control van, and a 1000 kW variable load bank, all integrated into a test array designed for operation at a variety of remote test sites. Data are presented for the Utah testing and for the noncondensing phases of the testing in Mexico. Test time logged was 437 hours during the Utah tests and 1101 hours during the Mexico tests.

  17. Photographic fixative poisoning

    MedlinePLUS

    Photographic developer poisoning; Hydroquinone poisoning; Quinone poisoning; Sulfite poisoning ... Hydroquinones Quinones Sodium thiosulfate Sodium sulfite/bisulfite Boric acid Photographic fixative can also break down (decompose) to form sulfur ...

  18. Pregnancy management for a patient with graft occlusion after right iliac artery bypass surgery.

    PubMed

    Nakae, Ruriko; Matsuzaki, Shinya; Egawa-Takata, Tomomi; Mimura, Kazuya; Kanagawa, Takeshi; Kimura, Tadashi

    2015-06-01

    We describe an extremely rare case of a pregnant woman who had a successful delivery despite developing bypass graft occlusion after right external iliac bypass surgery. External and common iliac artery bypass surgery is often performed when arteriosclerosis obliterans or thromboangiitis obliterans result in iliac artery occlusion or when revascularization is required because of iliac artery injury. Because arteriosclerosis obliterans and thromboangiitis obliterans rarely develop in young women or girls, most physicians have little experience with graft occlusion after iliac artery bypass surgery. Here we describe and discuss the published work pertaining to this extremely rare case. PMID:25511914

  19. Analysis of plastic deformation in cortical bone after insertion of coated and non-coated self-tapping orthopaedic screws.

    PubMed

    Koistinen, A P; Korhonen, H; Kiviranta, I; Kröger, H; Lappalainen, R

    2011-07-01

    Insertion of internal fracture fixation devices, such as screws, mechanically weakens the bone. Diamond-like carbon has outstanding tribology properties which may decrease the amount of damage in tissue. The purpose of this study was to investigate methods for quantification of cortical bone damage after orthopaedic bone screw insertion and to evaluate the effect of surface modification on tissue damage. In total, 48 stainless steel screws were inserted into cadaver bones. Half of the screws were coated with a smooth amorphous diamond coating. Geometrical data of the bones was determined by peripheral quantitative computed tomography. Thin sections of the bone samples were prepared after screw insertion, and histomorphometric evaluation of damage was performed on images obtained using light microscopy. Micro-computed tomography and scanning electron microscopy were also used to examine tissue damage. A positive correlation was found between tissue damage and the geometric properties of the bone. The age of the cadaver significantly affected the bone mineral density, as well as the damage perimeter and diameter of the screw hole. However, the expected positive effect of surface modification was probably obscured by large variations in the results and, thus, statistically significant differences were not found in this study. This can be explained by natural variability in bone tissue, which also made automated image analysis difficult. PMID:21870370

  20. Unifying screw geometry and matrix transformations

    SciTech Connect

    Samuel, A.E.; McAree, P.R.; Hunt, K.H. (Univ. of Melbourne, Parkville (Australia))

    1991-10-01

    Transformation matrices are widely used in robotics for kinematic analysis and trajectory planning. Screw geometry offers better geometric insight into such analyses. In this article the authors unify the two approaches through the use of invariant properties of orthogonal matrices under similarity transformations. They give a complete expression for the finite screw motion in terms of the entires of a 3 {times} 3 dual-number transformation matrix. Their analysis suggests that the finite screw is suitable for trajectory planning, and they develop a concise expression that gives the transformation matrix describing the displacement at each point along the path of the finite screw motion.

  1. Augmentation of unstable pertrochanteric fractures in the osteoporotic elderly patient: operative technique for 1 or 2 head screw systems.

    PubMed

    Dall'Oca, C; Maluta, T; Lavini, F; Micheloni, G M; Bondi, M; Magnan, B

    2014-01-01

    The incidence of proximal femoral fractures has substantially risen in the elderly. This rise has been attributed to an increase in their life span and the underlying poor bone stock and osteoporosis. One of the main reasons for revision surgery, reported to be as high as 19%, is the cut-out of the fixation device at the apex of the femoral head. Augmentation, facilitated by injecting cement (PMMA) around the apex of the proximal screw of the fixation device is considered a useful method with regards to the increased purchase between the bone and implant interface. The aim of this study is the description of the cement Augmentation operative technique for unstable osteoporotic pertrochanteric fractures with 1-2 femoral head screw devices. PMID:25409720

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

    PubMed

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

    2014-10-01

    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

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

    PubMed

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

    2015-04-01

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

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

    Microsoft Academic Search

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

    2009-01-01

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

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

    Microsoft Academic Search

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

    1999-01-01

    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

  6. Osteomyelitis after TightRope(®) fixation of the ankle syndesmosis: a case report and review of the literature.

    PubMed

    Hong, Choon Chiet; Lee, Wei Ting; Tan, Ken Jin

    2015-01-01

    Fixation of ankle syndesmosis injuries using the Ankle TightRope(®) has been gaining popularity. It has been shown to produce good results, facilitate early weightbearing, reduce the need for implant removal, and allow an earlier return to work and, possibly, a more anatomic syndesmotic reduction compared with screw fixation. However, its usage has been associated with complications such as soft tissue irritation, infection and wound breakdown, suture-button subsidence, and pathologic fracture from the screw tract. We describe a case of chronic osteomyelitis and suture-button migration associated with TightRope(®) fixation and a limited contact-dynamic compression plate for ankle syndesmosis disruption and lateral malleolus fracture. PMID:25451206

  7. Long stemmed total knee arthroplasty with interlocking screws: a computational bone adaptation study.

    PubMed

    Nyman, Jeffry S; Hazelwood, Scott J; Rodrigo, Juan J; Martin, R Bruce; Yeh, Oscar C

    2004-01-01

    The ability of an interlocking screw fixation technique to minimize bone loss related to stress shielding in the tibia was investigated and compared to the abilities of cement and press-fit fixation. Full bony ingrowth has been associated with greater stress shielding than partial ingrowth; therefore, the effect of intimate bonding of the stem to bone on subsequent bone loss was also studied. A damage- and disuse-based remodeling theory was coupled with a two-dimensional finite element model of the tibia to predict changes in bone remodeling following long stemmed total knee arthroplasty (TKA) for four different fixation techniques (cement, press-fit, interlock with bony ingrowth, and interlock without bony ingrowth). Remodeling changes commenced with the model state variables--bone area fraction, mechanical stimulus, damage, and remodeling activity--at steady-state values predicted by the intact tibia simulation. After TKA and irrespective of fixation technique, the model predicted elevated remodeling due to disuse, in which more bone was removed than replenished. In regions below the tibial tray and along the cortices, the interlocking stem with full bony ingrowth and the cemented stem caused the least amount of bone loss. An interlocking stem with a smooth, matted finish did not reduce the bone loss associated with interlocking fixation. PMID:14656659

  8. Bone ingrowth and stress shielding with a porous surface coated fracture fixation plate.

    PubMed

    Pilliar, R M; Cameron, H U; Binnington, A G; Szivek, J; Macnab, I

    1979-09-01

    The extent of bone remodelling under metal fixation plates attached to bone by (i) normal screw fixation and (ii) bone ingrowth into a porous metallic surface underlayer sintered to the metal plate was investigated. Extensive bone remodelling was observed under the integrally bonded porous surface layered plate. This remodelling could be attributed to the more extensive stress transfer from bone to metal plate because of the good bone-to-implant bonding. The importance of stress shielding with high stiffness implants is demonstrated. PMID:383716

  9. Iliac bone histomorphometry in adults and children with osteogenesis imperfecta.

    PubMed Central

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

    1984-01-01

    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

  10. Actinomyces infection causing acute right iliac fossa pain.

    PubMed

    Govindarajah, Narendranath; Hameed, Waseem; Middleton, Simon; Booth, Michael

    2014-01-01

    This is a case of a 75-year-old man being admitted to the on-call surgical department with acute abdominal pain. On arrival he was clinically dehydrated and shocked with localised pain over McBurney's point and examination findings were suggestive of appendiceal or other colonic pathology. Full blood testing revealed a white cell count of 38×10(9)/L and a C reactive protein (CRP) of 278?mg/L. A CT scan revealed a gallbladder empyema that extended into the right iliac fossa. This case highlights the potential for a hyperdistended gallbladder empyema to present as acute right iliac fossa pain with blood tests suggestive of complicated disease. Further analysis confirmed Actinomyces infection as the underlying aetiology prior to a laparoscopic subtotal cholecystectomy. This case serves to remind clinicians of this as a rare potential cause of atypical gallbladder pathology. PMID:24872493

  11. Migration pattern of cementless press fit cups in the presence of stabilizing screws in total hip arthroplasty

    PubMed Central

    2011-01-01

    The aim of this study was to evaluate the initial acetabular implant stability and late acetabular implant migration in press fit cups combined with screw fixation of the acetabular component in order to answer the question whether screws are necessary for the fixation of the acetabular component in cementless primary total hip arthroplasty. One hundred and seven hips were available for follow-up after primary THA using a cementless, porous-coated acetabular component. A total of 631 standardized radiographs were analyzed digitally by the "single-film-x-ray-analysis" method (EBRA). One hundred 'and one (94.4%) acetabular components did not show significant migration of more than 1 mm. Six (5.6%) implants showed migration of more than 1 mm. Statistical analysis did not reveal preoperative patterns that would identify predictors for future migration. Our findings suggest that the use of screw fixation for cementless porous- coated acetabular components for primary THA does not prevent cup migration. PMID:21486725

  12. Improved screw theory using second order terms

    Microsoft Academic Search

    Jun Takamatsu; H. Kimura; Katsushi Ikeuchi

    2002-01-01

    The local displacement of an object is very useful for deciding grasp stability, generating trajectories, recognizing assembly tasks, and so on. To calculate this displacement, the screw theory is employed. It is equivalent to the first order Taylor expansion of the displacement. The screw theory is very convenient, because the displacement is formulated as simultaneous linear inequalities, and a powerful

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

    PubMed Central

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

    2014-01-01

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

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

    SciTech Connect

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

    2011-10-15

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

  15. Twin screw granulation: steps in granule growth.

    PubMed

    Dhenge, Ranjit M; Cartwright, James J; Hounslow, Michael J; Salman, Agba D

    2012-11-15

    The present work focuses on the study of the progression of granules in different compartments along the length of screws in a twin screw granulator (TSG). The effects of varying powder feed rate; liquid to solid ratio and viscosity of granulation liquid on properties of granules was studied. The bigger granules produced at the start of the process were found to change in terms of size, shape and strength along the screw length at all the conditions investigated. The granules became more spherical and their strength increased along the screw length. Tracer granules were also introduced in order to understand the role of kneading and conveying elements in the TSG. The kneading elements promoted consolidation and breakage while the conveying elements led to coalescence, breakage and some consolidation. The results presented here help to provide a qualitative and quantitative understanding of the twin screw granulation process. PMID:22960611

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

    PubMed

    Thanner, J

    1999-08-01

    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

  17. Update: Biological Nitrogen Fixation.

    ERIC Educational Resources Information Center

    Wiseman, Alan; And Others

    1985-01-01

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

  18. The Fixation of Nitrogen.

    ERIC Educational Resources Information Center

    Andrew, S. P. S.

    1978-01-01

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

  19. Late migration of threaded wire (schanz screw) from right distal clavicle to the cervical spine.

    PubMed

    Tsai, Chun-Hao; Hsu, Horng-Chaung; Huan, Chun-Yin; Chen, Hsien-Te; Fong, Yi-Chin

    2009-01-01

    We report a 49-year-old man who had undergone osteosynthesis to treat right distal clavicular fracture with a threaded wire (Schanz screw). The wire could not be removed due to its firm fixation within the bone. Eight years later, migration of the broken wire to the right 7th cervical vertebra punctured the lamina, with no spinal cord injury noted. The threaded wire was extracted from the C7 lamina emergently. No complication occurred after pin removal or during the 1-year postoperative follow-up. PMID:19181599

  20. External Fixation combined with Limited Internal Fixation versus Open Reduction Internal Fixation for Treating Ruedi-Allgower Type III Pilon Fractures

    PubMed Central

    Guo, Yongzhi; Tong, Liangyong; Li, Shaoguang; Liu, Zhi

    2015-01-01

    Background The optimal treatment of type III pilon fractures remains controversial. Hence, we performed this study to investigate whether open reduction and internal fixation (ORIF) is superior to external fixations combined with limited internal fixations (EFLIF). Material/Methods From January 2012 to October 2013, a total of 78 patients were included. Twenty-six patients underwent EFLIF and 52 patients underwent ORIF. All subjects were followed up at 1, 3, 6, and 12 months postoperatively. All outcomes and complications were recorded. Results No statistical differences were observed in Mazur score or ROM between the 2 groups. There were significant differences between the 2 groups in hospital stay (P<0.001), reduction results (P=0.019), screw loosening (P=0.025), and traumatic arthritis (P=0.037). Conclusions Similar functional outcomes were achieved in EFLIF and ORIF groups. Due to several limitations of this study, a well-designed randomized controlled trial involving more patients and long-term follow-up is needed to find an optimal treatment protocol. PMID:26050786

  1. External Fixation combined with Limited Internal Fixation versus Open Reduction Internal Fixation for Treating Ruedi-Allgower Type III Pilon Fractures.

    PubMed

    Guo, Yongzhi; Tong, Liangyong; Li, Shaoguang; Liu, Zhi

    2015-01-01

    BACKGROUND The optimal treatment of type III pilon fractures remains controversial. Hence, we performed this study to investigate whether open reduction and internal fixation (ORIF) is superior to external fixations combined with limited internal fixations (EFLIF). MATERIAL AND METHODS From January 2012 to October 2013, a total of 78 patients were included. Twenty-six patients underwent EFLIF and 52 patients underwent ORIF. All subjects were followed up at 1, 3, 6, and 12 months postoperatively. All outcomes and complications were recorded. RESULTS No statistical differences were observed in Mazur score or ROM between the 2 groups. There were significant differences between the 2 groups in hospital stay (P<0.001), reduction results (P=0.019), screw loosening (P=0.025), and traumatic arthritis (P=0.037). CONCLUSIONS Similar functional outcomes were achieved in EFLIF and ORIF groups. Due to several limitations of this study, a well-designed randomized controlled trial involving more patients and long-term follow-up is needed to find an optimal treatment protocol. PMID:26050786

  2. Biomechanical comparison of internal fixation techniques for the Akin osteotomy of the proximal phalanx.

    PubMed

    Chacon, Yolanda; Fallat, Lawrence M; Dau, Nathan; Bir, Cynthia

    2012-01-01

    The Akin osteotomy is performed at the proximal phalanx for correction of an abducted great toe in a hallux abducto valgus deformity. Several internal fixation techniques have been widely advocated; however, their respective stabilities have not been compared. A biomechanical analysis was performed comparing 5 commonly used fixation techniques for the Akin osteotomy to determine the strongest method in simulated weightbearing in sawbone models. An Akin osteotomy was uniformly performed on 25 sawbones and fixated with 5 different internal fixation types, including a 2-hole locking plate and locking screws, a heat-sensitive memory staple (8 mm × 8 mm), a 28-gauge monofilament wire, 2.7-mm bicortical screws, and crossed 0.062-in. Kirschner wires. The results of simulated weightbearing load to failure rates with an Instron compression device demonstrated the following mean load to failures: crossed Kirschner wire, 57.05 N; 2-hole locking plate, 36.49 N; monofilament wire, 35.69 N; heat-sensitive memory staple, 34.32 N; and 2.7-mm bicortical screw, 13.66 N. Statistical analysis demonstrated the crossed Kirschner wire technique performed significantly better than the other fixation techniques (p < .007); the 4 other techniques were found not to be significantly different statistically (p = .041) from each another. Our study results suggest a crossing Kirschner wire construct significantly increases the stability of the Akin osteotomy in a sawbone model. This might be clinically extrapolated in an effort to improve patient outcomes because these osteotomies can undergo nonunion and malunion, resulting in postoperative pain and swelling. PMID:22819001

  3. A geometrical introduction to screw theory

    NASA Astrophysics Data System (ADS)

    Minguzzi, E.

    2013-05-01

    This work introduces screw theory, a venerable but little known theory aimed at describing rigid body dynamics. This formulation of mechanics unifies in the concept of screw the translational and rotational degrees of freedom of the body. It captures a remarkable mathematical analogy between mechanical momenta and linear velocities, and between forces and angular velocities. For instance, it clarifies that angular velocities should be treated as applied vectors and that, under the composition of motions, they sum with the same rules of applied forces. This work provides a short and rigorous introduction to screw theory intended for an undergraduate and general readership.

  4. A geometrical introduction to screw theory

    E-print Network

    E. Minguzzi

    2012-11-20

    This work introduces screw theory, a venerable but yet little known theory aimed at describing rigid body dynamics. This formulation of mechanics unifies in the concept of screw the translational and rotational degrees of freedom of the body. It captures a remarkable mathematical analogy between mechanical momenta and linear velocities, and between forces and angular velocities. For instance, it clarifies that angular velocities should be treated as applied vectors and that, under the composition of motions, they sum with the same rules of applied forces. This work provides a short and rigorous introduction to screw theory intended to an undergraduate and general readership.

  5. Novel posterior fixation keratoprosthesis

    NASA Astrophysics Data System (ADS)

    Lacombe, Emmanuel

    1992-08-01

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

  6. CARBON DIOXIDE FIXATION.

    SciTech Connect

    FUJITA,E.

    2000-01-12

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

  7. Screw pull-out force is dependent on screw orientation in an anterior cervical plate construct.

    PubMed

    DiPaola, Christian P; Jacobson, Justin A; Awad, Hani; Conrad, Bryan P; Rechtine, Glenn R

    2007-07-01

    Two common justifications for orienting cervical screws in an angled direction is to increase pull-out strength and to allow use of longer screws. This concept is widely taught and has guided implant design. Fixed versus variable angle systems may offer strength advantages. The purpose of our study is to test the influence of screw orientation and plate design on the maximum screw pull-out load. Variable and fixed angle 4.0 x 15 mm and 4.0 x 13 mm self-tapping screws were used to affix a Medtronic Atlantis cervical plate to polyurethane foam bone samples (density 0.160/cm). This synthetic product is a model of osteoporotic cancellous bone. The fixed angle screws can only be placed at 12 degrees convergent to the midline and 12 degrees in the cephalad/caudal ("12 degrees up and in") direction. Three groups were tested: (1) all fixed angle screws, (2) variable angle, all screws 12 degrees up and in, (3) variable angle, all screws 90 degrees to the plate. Plate constructs were pulled off with an Instron DynaMight 8841 servohydrolic machine measuring for maximum screw pull-out force. There was no difference between group 1, fixed angle (288.4 +/- 37.7 N) (mean +/- SD) and 2, variable angle group (297.7 +/- 41.31 N P< or =0.73). There was a significant increase in maximum pull-out force to failure for the construct with all screws at 90 degrees (415.2+/-17.4 N) compared with all screws 12 degrees "up and in" (297.4 +/- 41.3 N, P< or =0.0016). Group 3 done with 13 mm screws, showed a trend toward better pull-out strength, compared to group 2 w/15 mm screws (345.2 +/- 20.5 vs. 297.4 +/- 41.3, P< or =0.06). In this plate pull-out model, screw orientation influences maximum force to failure. When all 4 screws are 90 degrees to the plate the construct has the greatest ability to resist pullout. Fixed angle designs show no advantage over variable angle. These findings are contrary to current teaching. PMID:17607102

  8. Internal fixation versus hemiarthroplasty versus total hip arthroplasty for displaced subcapital fractures of femur — 13 year results of a prospective randomised study

    Microsoft Academic Search

    Kasetti J. Ravikumar; Gavin Marsh

    2000-01-01

    In this prospective randomised trial we compare the mortality, morbidity and functional results of patients following each of the three principal methods of treatment for displaced subcapital fractures of the femur. Two hundred and ninety patients over the age of 65 years were included and randomly allocated to undergo closed reduction and internal fixation with a sliding compression screw plate

  9. Bicondylar tibial plateau fractures treated with fine-wire circular external fixation.

    PubMed

    Ferreira, N; Marais, L C

    2014-04-01

    Bicondylar tibial plateau fractures are serious injuries to a major weight-bearing joint. These injuries are often associated with severe soft tissue injuries that complicate surgical management. We reviewed 54 consecutive patients who sustained bicondylar tibial plateau fractures that were treated with limited open reduction and cannulated screw fixation combined with fine-wire circular external fixation. Forty-six patients met the inclusion criteria of this retrospective review. Eight patients were excluded because they did not complete a minimum of 1-year follow-up. Thirty-six patients had Schatzker type-VI, and ten patients had Schatzker type-V fractures. All fractures were united without loss of reduction; there were no incidences of wound complications, osteomyelitis or septic arthritis. The average Knee Society Clinical Rating Score was 81.6, translating to good clinical results. Minor pin track infection was the most common complication encountered. This review concludes that fine-wire circular external fixation, combined with limited open reduction and cannulated screw fixation, consistently produces good functional results without serious complications. PMID:24510395

  10. Elastically suspending the screw holes of a locked osteosynthesis plate can dampen impact loads.

    PubMed

    Capanni, Felix; Hansen, Kirk; Fitzpatrick, Daniel C; Madey, Steven M; Bottlang, Michael

    2015-06-01

    Impact damping by elastic fixation is a principal engineering strategy to increase the durability of load-bearing structures exposed to prolonged dynamic loading. This biomechanical study evaluated axial impact damping provided by a novel dynamic locking plate. In this design, locking screw holes are elastically suspended within a silicone envelope inside the locking plate. Axial impact damping was assessed for 3 distinct fixation constructs applied to bridge a 10-mm fracture gap of a femoral diaphysis surrogate: a standard locking plate, a dynamic locking plate, and an Ilizarov ring fixator. First, the 3 fixation constructs were characterized by determining their axial stiffness. Subsequently, constructs were subjected to a range of axial impact loads to quantify damping of force transmission. Compared with standard locked plating constructs, dynamic plating constructs were 58% less stiff (P < .01) and Ilizarov constructs were 88% less stiff (P < .01). Impact damping correlated inversely with construct stiffness. Compared with standard plating, dynamic plating constructs and Ilizarov constructs dampened the transmission of impact loads by up to 48% (P < .01) and 74% (P < .01), respectively. In conclusion, lower construct stiffness correlated with superior damping of axial impact loads. Dynamic locking plates provide significantly greater impact damping compared with standard locking plates. PMID:25642697

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

    E-print Network

    Bratton, Gerald Roy

    1970-01-01

    origin from any of the visceral branches of the internal iliac artery. The prostatic Arteries About 1 to 2 mm. posterior to the origin of the artery of the ductus deferens the internal pudendal artery gives rise to 1 or 2 prostatic arteries. . 27... The diaphragm was incised along its costal attachment and the crura were loosened. The sterno- pericardi- l ligament, posterior vena cava, and esoph- agus were transected on the thoracic side of the diaph ann. The abdominal viscera, along with the diaphragm...

  12. Rotordynamics of Twin-Screw Pumps 

    E-print Network

    Aboel Hassan Muhammed, Ameen

    2013-02-26

    geometry, the circumferential pressure field around the screws is not balanced, resulting in net dynamic and static pressures applied on the rotors. The research work presented here aims at building and verifying a model to predict both: (1) the exciting...

  13. Rotordynamics of Twin-Screw Pumps

    E-print Network

    Aboel Hassan Muhammed, Ameen

    2013-02-26

    geometry, the circumferential pressure field around the screws is not balanced, resulting in net dynamic and static pressures applied on the rotors. The research work presented here aims at building and verifying a model to predict both: (1) the exciting...

  14. Cycling Losses During Screw Air Compressor Operation 

    E-print Network

    Maxwell, J. B.; Wheeler, G.; Bushnell, D.

    1995-01-01

    Air compressors use 10-13 % of a typical industrial facilities' total electricity. Because they often operate at part load, their part load efficiency significantly affects plant energy cost. An intensive study of screw air compressor part load...

  15. Semi-Empirical Screw Compressor Chiller Model

    E-print Network

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

    Director, Energy Systems Laboratory College Station, TX USA Rhett D. Graves, P.E. Research Associate II, Department of Mechanical Engineering Mississippi State University Starkville, MS USA ABSTRACT A screw chiller model which is based on a first...

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

    PubMed Central

    2014-01-01

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

  17. Additional Drive Circuitry for Piezoelectric Screw Motors

    NASA Technical Reports Server (NTRS)

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

    2004-01-01

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

  18. [Laparoscopic ligation of the internal iliac artery in bleeding cervix carcinoma].

    PubMed

    Skret, A; Obrzut, B; Stachurski, J

    1995-01-01

    Laparoscopic ligation of internal iliac artery was performed in two patients with bleeding from stage II cervical cancer. The hemostatic effect, shortening of convalescence and early initiation of radiotherapy was obtained. Additionally, during procedure the lymph node sampling was performed. Laparoscopy appeared to be an alternative procedure to abdominal or extraperitoneal ligation of internal iliac artery. PMID:7483884

  19. Iliac artery pseudoaneurysm rupture following excision of an infected hip prosthesis.

    PubMed

    Smith, George H; Nutton, Richard W; Fraser, Simon C

    2011-09-01

    We report a case of external iliac artery aneurysm rupture during removal of the acetabular component for septic loosening. Potentially fatal hemorrhage would have occurred if the risk had not been recognized, and the external iliac vessels exposed to gain vascular control before proceeding with implant removal. A review of the literature on vascular injury at revision hip surgery is presented. PMID:21074354

  20. Delayed Esophageal Pseudodiverticulum after Anterior Cervical Spine Fixation: Report of 2 Cases

    PubMed Central

    Sadrizadeh, Ali; Soltani, Ehsan; Abili, Mehdi; Dehghanian, Paria

    2015-01-01

    Introduction: Although perforation of the esophagus, in the anterior cervical spine fixation, is well established, cases with delayed onset, especially cases that present pseudodiverticulum, are not common. In addition, management of the perforation in this situation is debated. Case Report: Delayed esophageal pseudodiverticulum was managed in two patients with a history of anterior spine fixation. Patients were operated on, the loose plate and screws were extracted, the wall of the diverticulum was excised, the perforation on the nasogastric tube was suboptimally repaired, and a closed suction drain was placed there. The NGT was removed on the 7th day and barium swallow demonstrated no leakage at the operation site; therefore, oral feeding was started without any problem Conclusion: In cases with delayed perforation, fistula, or diverticulum removal of anterior fixation instruments, gentle repair of the esophageal wall without persistence on definitive and optimal perforation closure, wide local drainage, early enteral nutrition via NGT, and antibiotic prescription is suggested. PMID:25938087

  1. [Implant materials for the internal fixation of midfacial fractures].

    PubMed

    Stuck, B A; Heller, T

    2011-11-01

    The material used for osteosynthesis plays a crucial role in the management of facial fractures. Plates need to be flexible enough to be bent and should not be palpable through the skin, while ensuring stable fixation und adequate biocompatibility. Although stainless steel was initially the material of choice, titanium has become the standard material due to its superior biocompatibility. While the explantation of titanium plates and screws appears unnecessary in general, it should be considered in cases of dislocation, cosmetic concerns, pain and infection. Due to their limited initial stability and a potential increase in local complications, resorbable materials based on polymeric lactose are used with caution in midfacial fractures in adults. Our own retrospective study comparing the postoperative complications after fixation of lateral midfacial fractures with titanium and resorbable systems demonstrated a low complication rate for both systems (7-8%) and no statistically significant difference between the two. The appropriate material for fixation should be selected based on the localization and severity of the fracture, the experience of the surgeon as well as on the age and overall condition of the patient. PMID:22012485

  2. Repair of a high-flow iliac arteriovenous fistula using a thoracic endograft.

    PubMed

    Cronin, Brett; Kane, Justin; Lee, William; Shriki, Jabi; Weaver, Fred A

    2009-03-01

    Open surgical repair of iliac arteriovenous fistulas is associated with significant morbidity and mortality, making endovascular repair an attractive alternative. This report describes a 39-year-old man who was admitted with two-pillow orthopnea, edema, and fatigue. He had sustained a gunshot wound to the pelvis 13 years previously. Six years after the gunshot wound, he was diagnosed with cardiomegaly and high-output congestive heart failure. A magnetic resonance angiography documented a large pelvic arteriovenous fistula. A diagnostic contrast angiogram confirmed a high-flow fistula between the left distal main internal iliac artery and left common iliac vein. A Gore TAG thoracic endoprosthesis (W. L. Gore and Assoc, Flagstaff, Ariz) was used to repair this large, high-flow internal iliac artery-common iliac vein arteriovenous fistula. PMID:19147317

  3. Absorbable biologically based internal fixation.

    PubMed

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

    2015-01-01

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

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

    PubMed Central

    Li, Lijun; Tian, Wei

    2015-01-01

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

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

    PubMed

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

    2015-01-01

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

  6. Nitrogen fixation apparatus

    DOEpatents

    Chen, Hao-Lin (Walnut Creek, CA)

    1984-01-01

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

  7. A comparison of four tibial-fixation systems in hamstring-graft anterior ligament reconstruction.

    PubMed

    Robert, Henri; Bowen, Mark; Odry, Guillaume; Collette, Michel; Cassard, Xavier; Lanternier, Hubert; De Polignac, Thierry

    2015-02-01

    The aim of this study was to evaluate at time-zero four tibial fixations on four major criteria: the elongation and cyclic stiffness of the hamstring graft construct under cyclic loading, the yield load and pullout stiffness under load at failure. Four fixation systems were tested: the Delta screw, the WasherLoc, the TightRope Reverse and the tape locking screw on 32 tibiae of adult pigs using 32 pairs of human semitendinosus and gracilis tendons. Two tests were performed: cyclic tests using loads at 70-220 N, to measure the elongation at the end of the cycles, followed by load-to-failure testing to measure the yield load and the cyclic stiffness. The mean elongation was 1.23 mm for the TLS, 3.81 mm for the Delta, 3.59 mm for the WasherLoc and 3.91 mm for the TightRope. The mean yield loads and SD were 1,015 ± 129 N for the TLS, 844 ± 394 N for the Delta, 511 ± 95 N for the WasherLoc and 567 ± 112 N for the TightRope. The results showed the significant superiority of TLS and Delta over WasherLoc and tibial TightRope in regard to yield load. The results showed the significant superiority of TLS over the other fixations in regard to slippage. The TLS system and the Delta screw provide a better quality of primary fixation to the tibia, but further in vitro studies are needed. PMID:24816761

  8. Eighth international congress on nitrogen fixation

    SciTech Connect

    Not Available

    1990-01-01

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

  9. Biomechanical analysis of acetabular revision constructs: is pelvic discontinuity best treated with bicolumnar or traditional unicolumnar fixation?

    PubMed

    Gililland, Jeremy M; Anderson, Lucas A; Henninger, Heath B; Kubiak, Erik N; Peters, Christopher L

    2013-01-01

    Pelvic discontinuity in revision total hip arthroplasty presents problems with component fixation and union. A construct was proposed based on bicolumnar fixation for transverse acetabular fractures. Each of 3 reconstructions was performed on 6 composite hemipelvises: (1) a cup-cage construct, (2) a posterior column plate construct, and (3) a bicolumnar construct (no. 2 plus an antegrade 4.5-mm anterior column screw). Bone-cup interface motions were measured, whereas cyclical loads were applied in both walking and descending stair simulations. The bicolumnar construct provided the most stable construct. Descending stair mode yielded more significant differences between constructs. The bicolumnar construct provided improved component stability. Placing an antegrade anterior column screw through a posterior approach is a novel method of providing anterior column support in this setting. PMID:22595181

  10. [3-D finite element modeling of internal fixation of mandibular mental fracture and the design of boundary constraints].

    PubMed

    Luo, Xiaohui; Wang, Hang; Fan, Yubo

    2007-04-01

    This study was aimed to develop a 3-D finite element (3-D FE) model of the mental fractured mandible and design the boundary constrains. The CT images from a health volunteer were used as the original information and put into ANSYS program to build a 3-D FE model. The model of the miniplate and screw which were used for the internal fixation was established by Pro/E. The boundary constrains of different muscle loadings were used to simulate the 3 functional conditions of the mandible. A 3-D FE model of mental fractured mandible under the miniplate-screw internal fixation system was constructed. And by the boundary constraints, the 3 biting conditions were simulated and the model could serve as a foundation on which to analyze the biomechanical behavior of the fractured mandible. PMID:17591250

  11. 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

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

    2012-01-01

    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

  12. DINITROGEN FIXATION IN ILLINOIS BUNDLEFLOWER

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  13. Overdesign of external fixation systems.

    PubMed

    Habboushe, M P

    1992-05-01

    This article reviews 850 cases of open fractures of the extremities caused by high velocity missiles and shell fragments, and treated by two varieties of external fixation devices. If a protocol for grading the severity of injury is followed, the results encourage avoiding sophisticated, expensive, and overdesigned external fixation systems. PMID:1589355

  14. Twin screw wet granulation: Binder delivery.

    PubMed

    Saleh, Mohammed F; Dhenge, Ranjit M; Cartwright, James J; Hounslow, Michael J; Salman, Agba D

    2015-06-20

    The effects of three ways of binder delivery into the twin screw granulator (TSG) on the residence time, torque, properties of granules (size, shape, strength) and binder distribution were studied. The binder distribution was visualised through the transparent barrel using high speed imaging as well as quantified using offline technique. Furthermore, the effect of binder delivery and the change of screw configuration (conveying elements only and conveying elements with kneading elements) on the surface velocity of granules across the screw channel were investigated using particle image velocimetry (PIV). The binder was delivered in three ways; all solid binder incorporated with powder mixture, 50% of solid binder mixed with powder mixture and 50% mixed with water, all the solid binder dissolved in water. Incorporation of all solid binder with powder mixture resulted in the relatively longer residence time and higher torque, narrower granule size distribution, more spherical granules, weaker big-sized granules, stronger small-sized granules and better binder distribution compared to that in other two ways. The surface velocity of granules showed variation from one screw to another as a result of uneven liquid distribution as well as shown a reduction while introducing the kneading elements into the screw configuration. PMID:25869451

  15. Maxillary sinus perforation by orthodontic anchor screws.

    PubMed

    Motoyoshi, Mitsuru; Sanuki-Suzuki, Rina; Uchida, Yasuki; Saiki, Akari; Shimizu, Noriyoshi

    2015-01-01

    To facilitate safe placement of orthodontic anchor screws (miniscrews), we investigated the frequency of maxillary sinus perforation after screw placement and the effect of sinus perforation on screw stability. Maxillary sinus perforations involving 82 miniscrews (diameter, 1.6 mm; length, 8 mm) were evaluated using cone-beam computed tomography. All miniscrews were placed in maxillary alveolar bone between the second premolar and first molar for anchorage for anterior retraction in patients undergoing first premolar extraction. The placement torque and screw mobility of each implant were determined using a torque tester and a Periotest device, and variability in these values in relation to sinus perforation was evaluated. Eight of the 82 miniscrews perforated the maxillary sinus. There was no case of sinusitis in patients with miniscrew perforation and no significant difference in screw mobility or placement torque between perforating and non-perforating miniscrews. The sinus floor was significantly thinner in perforated cases than in non-perforated cases. A sinus floor thickness of 6.0 mm or more is recommended in order to avoid miniscrew perforation of the maxillary sinus. (J Oral Sci 57, 95-100, 2015). PMID:26062857

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

    PubMed

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

    2015-03-16

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

  17. Surgical rib fixation - technical aspects.

    PubMed

    Marasco, Silvana; Saxena, Pankaj

    2015-05-01

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

  18. Reconstruction of residual mandibular defects by iliac crest bone graft in war-wounded Iraqi civilians, 2006-2011.

    PubMed

    Guerrier, Gilles; Alaqeeli, Ali; Al Jawadi, Ammar; Foote, Nancy; Baron, Emmanuel; Albustanji, Ashraf

    2015-07-01

    Our aim was to assess the long-term results, complications, and factors associated with failure of mandibular reconstructions among wounded Iraqi civilians with mandibular defects. Success was measured by the quality of bony union, and assessed radiographically and by physical examination. Failures were defined as loss of most or all of the bone graft, or inability to control infection. During the 6-year period (2006-2011), 35 Iraqi patients (30 men and 5 women, mean age 33 years, range 15-57) had residual mandibular defects reconstructed by iliac crest bone grafts. The causes were bullets (n=29), blasts (n=3), and shrapnel (n=3). The size of the defect was more than 5cm in 19 cases. Along the mandible the defect was lateral (n=14), central/lateral (n=5), lateral/central/lateral in continuity (n=6), and central in continuity (n=10). The mean time from injury to operation was 548 days (range 45-3814). All but 2 patients had infected lesions on admission. Bony fixation was ensured by locking reconstruction plates (n=27), non-locking reconstruction plates (n=6), and miniplates (n=2). Complications were associated with the reconstruction plate in 2 cases, and donor-site morbidity in 5. After a mean follow-up of 17 months (range 6-54), bony union was achieved in 28 (80%). The quality of the bone was adequate for dental implants in 23 cases (66%). Our results suggest that war-related mandibular defects can be reconstructed with non-vascularised bone grafts by multistage procedures with good results, provided that the soft tissues are in good condition, infection is controlled, and the method of fixation is appropriate. Further studies are needed to assess the role of vascularised free flaps in similar conditions. PMID:22748406

  19. Banking of cryopreserved iliac artery and vein homografts: clinical uses in transplantation.

    PubMed

    Heng, Wee Ling; Madhavan, Krishnakumar; Wee, Priscilla; Seck, Tracy; Lim, Yeong Phang; Lim, Chong Hee

    2015-06-01

    Iliac artery and vein homografts are critical for revascularization in living-donor liver transplantation. Since 2010, National Cardiovascular Homograft Bank and National University Hospital have collaborated in the pioneer endeavor of banking iliac vessel homografts for such surgeries in Singapore. This article aims to demonstrate that the processing, decontamination and cryopreservation techniques that our bank follow, help preserve iliac vessel homografts for a longer duration as compared to homografts preserved using short-term preservation techniques. This paper reports the first 4 years of post-operative outcome for recipients as a preliminary report for a longer-term outcome study. Criteria for donor assessment, techniques of iliac vessel homograft recovery, processing, decontamination, cryopreservation and storage according to the American Association of Tissue Banks standards are also described. From 2010 until 2013, we discovered of the iliac vessel homografts processed, 17 (94.4 %) were suitable for clinical use. Nine iliac artery grafts (64 %) and one iliac vein graft (14 %) were implanted. Irrespective of vessel type, homografts <90 mm in length were of little use. Of the nine current iliac vessel homograft recipients, eight patients (89 %) had living-donor liver transplantation and one patient (11 %) had reconstruction of the right internal carotid artery after resection of an aneurysm. Our preliminary results supports existing literatures that suggest cryopreserved iliac vessel homografts can be successfully used for revascularization in liver transplantation and reconstruction of carotid artery. Encouraging short-term post-operative patient outcomes have been achieved, with no report of adverse event attributed to implanted homografts. We believe that our processing, decontamination and cryopreservation techniques have helped preserve the homografts for longer duration as compared to homografts preserved using short-term preservation techniques. PMID:25151404

  20. The stability of fixation of proximal femoral fractures: a radiostereometric analysis.

    PubMed

    van Embden, D; Stollenwerck, G A N L; Koster, L A; Kaptein, B L; Nelissen, R G H H; Schipper, I B

    2015-03-01

    The aim of this study was to quantify the stability of fracture-implant complex in fractures after fixation. A total of 15 patients with an undisplaced fracture of the femoral neck, treated with either a dynamic hip screw or three cannulated hip screws, and 16 patients with an AO31-A2 trochanteric fracture treated with a dynamic hip screw or a Gamma Nail, were included. Radiostereometric analysis was used at six weeks, four months and 12 months post-operatively to evaluate shortening and rotation. Migration could be assessed in ten patients with a fracture of the femoral neck and seven with a trochanteric fracture. By four months post-operatively, a mean shortening of 5.4 mm (-0.04 to 16.1) had occurred in the fracture of the femoral neck group and 5.0 mm (-0.13 to 12.9) in the trochanteric fracture group. A wide range of rotation occurred in both types of fracture. Right-sided trochanteric fractures seem more rotationally stable than left-sided fractures. This prospective study shows that migration at the fracture site occurs continuously during the first four post-operative months, after which stabilisation occurs. This information may allow the early recognition of patients at risk of failure of fixation. PMID:25737524

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

    PubMed

    Szivek, J A; Yapp, R A

    1989-04-01

    Orthopaedic internal fracture fixation plates are subjected to combined axial, bending, and torsional loads in vivo which can cause screw loosening and implant failure. This paper outlines a relatively simple technique which allows controlled application of combined axial, bending, and torsional loading to examine the loosening rate of cortical screws used to attach these plates. Fiber reinforced polycarbonate rods with a tensile strength similar to that of cortical bone were cut at half their length to simulate fractured tibii. These were compression plated using a standardized technique and placed in a loading fixture. Joint loads at the knee determined from force plate analysis and statics were applied to a plated fixture during testing. The design of the fixture allowed adjustment of the proportion of bending and torsional loads applied to the test samples. It also allowed a reproducible means of applying a predetermined axial, bending, and torsional load. Screw loosening following cyclical loading was evaluated by measuring the amount of angular displacement required to retighten screws to a prescribed torque value. A torque wrench was modified to allow the measurement of these displacements. PMID:2722901

  2. Femoral head necrosis treated with vascularized iliac crest graft.

    PubMed

    Pavlovcic, V; Dolinar, D; Arnez, Z

    1999-01-01

    We reviewed 24 hips with avascular necrosis of the femoral head in 24 patients treated with vascularized iliac bone grafts 12 years after operation. In 7 patients the necrosis was classified as Ficat Stage II and in 17 patients as Stage III. Eight patients showed poor results. In 6 hips with fair results, moderate progression of the necrosis was noted at 3 to 8 years postoperatively. In 5 hips showing good results, slow progression with incipient signs of arthrosis were noted 8 years after surgery. In the remaining 5 patients with excellent results, no evidence of progression was noted 9 to 14 years postoperatively. The method described is recommended for treatment in the Ficat Stage II and early Stage III, when necrosis does not yet involve the complete femoral head. PMID:10486026

  3. Screw expander for light duty diesel engines

    NASA Technical Reports Server (NTRS)

    1983-01-01

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

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

    SciTech Connect

    Whittaker, Charlotte Sara, E-mail: c_whittaker1@yahoo.co.uk; Ananthakrishnan, Ganapathy; DeNunzio, Mario Cosimo; Quarmby, John Winston; Bungay, Peter Mark [Derbyshire Royal Infirmary (United Kingdom)

    2008-07-15

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

  5. 21 CFR 888.3070 - Pedicle screw spinal system.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... “Warning: The safety and effectiveness of pedicle screw spinal systems have been established...requiring fusion with instrumentation. These conditions...pseudarthrosis). The safety and effectiveness of these...pedicle screw spinal systems should be...

  6. 21 CFR 888.3070 - Pedicle screw spinal system.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... “Warning: The safety and effectiveness of pedicle screw spinal systems have been established...requiring fusion with instrumentation. These conditions...pseudarthrosis). The safety and effectiveness of these...pedicle screw spinal systems should be...

  7. 21 CFR 888.3070 - Pedicle screw spinal system.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... “Warning: The safety and effectiveness of pedicle screw spinal systems have been established...requiring fusion with instrumentation. These conditions...pseudarthrosis). The safety and effectiveness of these...pedicle screw spinal systems should be...

  8. 21 CFR 888.3070 - Pedicle screw spinal system.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... “Warning: The safety and effectiveness of pedicle screw spinal systems have been established...requiring fusion with instrumentation. These conditions...pseudarthrosis). The safety and effectiveness of these...pedicle screw spinal systems should be...

  9. KINEMATIC ANALYSIS OF LOWER MOBILITY COOPERATIVE ARMS BY SCREW THEORY

    E-print Network

    Paris-Sud XI, Université de

    KINEMATIC ANALYSIS OF LOWER MOBILITY COOPERATIVE ARMS BY SCREW THEORY Philip Long1 , St´ephane Caro.secondname}@irccyn.ec-nantes.fr Keywords: Cooperative Manipulators:Humanoid Robots: Screw theory Abstract: This paper studies the kinematic

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

    PubMed Central

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

    2015-01-01

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

  11. A geometrical introduction to screw theory

    E-print Network

    Minguzzi, E

    2012-01-01

    Since the addition of applied forces must take into account the line of action, applied forces do not belong to a vector space. Screw theory removes this geometrical limitation and solves other mechanical problems by unifying, in a single concept, the translational and rotational degrees of freedom. Although venerable this theory is little known. By introducing some innovations, I show how screw theory can help us to rapidly develop several standard and less standard results in classical mechanics. The connection with the Lie algebra of the group of rigid maps is clarified.

  12. Screw Systems, Singular Trajectories and DarbouxType Motions

    E-print Network

    Donelan, Peter

    Screw Systems, Singular Trajectories and Darboux­Type Motions M. W. Cocke and C. G. Gibson by the associated screw system. We present a classification of screw systems based on a Lie group representation body motions abound in theory and practice. The instantaneous centre of rotation for a continuous (or

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

    PubMed Central

    Oshima, Masashi; Ajiro, Yasumitsu; Uei, Hiroshi

    2014-01-01

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

  14. Design and experimental evaluation of adjustable bone plates for mandibular fracture fixation.

    PubMed

    Cervantes, Thomas M; Slocum, Alexander H; Seldin, Edward B

    2012-01-01

    Conventional bone plates are commonly used for surgical mandibular fracture fixation. Improper alignment between bone segments, however, can result in malocclusion. Current methods of fixation require a surgeon to visually align segments of bone and affix a metal plate using bone screws, after which little can be done to adjust alignment. A method of adjusting fracture alignment after plate placement, without screw removal, presents an improvement over costly and risky revision surgery. A modified bone plate has been designed with a deformable section to give surgeons the ability to reduce misalignments at the fracture site. The mechanics of deformation for various adjustment mechanisms was explored analytically, numerically, and experimentally to ensure that the adjustable plate is comparable to conventional bone plates. A static force of 358.8 N is required to deform the adjustable bone plate, compared with predicted values of 351 N using numerical simulation and 362 N using a simple beam theory. Dynamic testing was performed to simulate in vivo loading conditions and evaluate load-capacity in both deformed and un-deformed bone plates. Results indicate that bending stiffness of a rectangular bone plate is 709 N/mm, compared with 174 N/mm for an octagonal plate and 176 N/mm for standard plates. Once deformed, the rectangular and octagonal plates had a stiffness of 323 N/mm and 228 N/mm, respectively. Un-deformed and deformed adjustable bone plates have efficacy in bone segment fixation and healing. PMID:22036033

  15. Bioabsorbable fixation of scaphoid fractures and non-unions; analysis of early clinical outcomes.

    PubMed

    Ya'ish, F; Bailey, C A; Kelly, C P; Craigen, M A

    2013-01-01

    The vast majority of devices used for internal fixation of the scaphoid are metallic. This two-center study aimed to report the results of scaphoid fixation using a cannulated, bioabsorbable device made from a hydroxyapatite and poly-L-lactide composite in 29 consecutive patients. Fixation was performed for seven acute fractures and twenty-two established non-unions. Union was achieved in 72.4% of patients. Six of the acute fractures and fifteen of the non-unions united successfully. Modified Mayo Wrist Score ranged between good to excellent in all patients who successfully united, whereas patients who failed to unite ranged between poor to excellent, with one poor and two moderate scores. No adverse biocompatibility reactions were seen. Two failures with broken screws were re-explored and one of these was thought to be due to screw mal-placement. The device used is an alternative to conventional metal implants and produces comparable union rates to metallic devices in the short term. PMID:24156576

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

    SciTech Connect

    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

    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.

  17. Hybrid management of a spontaneous ilio-iliac arteriovenous fistula: a case report

    PubMed Central

    2011-01-01

    Introduction Spontaneous iliac arteriovenous fistulae are a rare clinical entity. Such localized fistulation is usually a result of penetrating traumatic or iatrogenic injury. Clinical presentation can vary greatly but commonly includes back pain, high-output congestive cardiac failure and the presence of an abdominal bruit. Diagnosis, therefore, is often incidental or delayed. Case presentation We report a case of a spontaneous ilio-iliac arteriovenous fistula in a 68-year-old Caucasian man detected following presentation with unilateral claudication and congestive cardiac failure. Following computed tomography evaluation, the fistula was successfully treated with a combined endovascular (aorto-uni-iliac device) and open (femoro-femoral crossover) approach. Conclusion Endovascular surgery has revolutionized the management of such fistulae and we report an interesting case of a high-output iliac arteriovenous fistulae successfully treated with a hybrid vascular approach. PMID:21859469

  18. Failure of posterior titanium atlantoaxial cable fixation

    Microsoft Academic Search

    Rolando Garcia; Stephen Gorin

    2003-01-01

    Background context: The operative treatment of rotatory atlantoaxial instability remains controversial. The use of cable fixation has largely replaced the use of wire for interlaminar fixation. Although cable fixation offers biomechanical advantages over wire fixation, it is still at risk of fatigue failure. The authors were unable to locate any published reports of fatigue failure of titanium cables in the

  19. Impact of Stent Design on In-Stent Stenosis in a Rabbit Iliac Artery Model

    Microsoft Academic Search

    C. M. Sommer; L. Grenacher; U. Stampfl; F. U. Arnegger; C. Rehnitz; H. Thierjung; S. Stampfl; I. Berger; G. M. Richter; H. U. Kauczor; B. A. Radeleff

    2010-01-01

    The purpose of this study was to evaluate the impact of stent design on in-stent stenosis in rabbit iliac arteries. Four different\\u000a types of stent were implanted in rabbit iliac arteries, being different in stent design (crown or wave) and strut thickness\\u000a (50 or 100 ?m). Ten stents of each type were implanted. Each animal received one crown and one wave

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

    SciTech Connect

    Trehan, Vijay; Nigam, Arima; Ramakrishnan, S. [G. B. Pant Hospital, Department of Cardiology (India)], E-mail: ramakgmc@rediffmail.com

    2007-02-15

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

  1. Parameter estimation during automated screw insertions

    Microsoft Academic Search

    Mongkom Klingajay; Lakmal D. Seneviratne; Kaspar Althoefer

    2002-01-01

    Threaded fastenings are a common assembly method, accounting for over a quarter of all assembly operations. Threaded fastenings are popular because they permit easy disassembly for maintenance, repair, relocation and recycling. Screw insertions are typically carried out manually and are a difficult problem to automate. As a result there is very little published research on automating threaded fastenings, and most

  2. Computer simulation of screw dislocation in aluminum

    NASA Technical Reports Server (NTRS)

    Esterling, D. M.

    1976-01-01

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

  3. ROBOT WELDING TRAJECTORY PLANNING USING SCREW THEORY

    Microsoft Academic Search

    Renato Ventura; Bayan Henriques; Carlos Eduardo Pereira; Alexandre Queiroz Bracarense; Raul Guenther; Antonio O. Dourado; Daniel Martins

    This article presents a methodology for trajectory plannin g in robot welding applications, which handles parts with geometric restrictions . Differential kinematics are calc ulated using the screws theory and an optimal welding positi on (plain position) is obtained when defining the welding seque nce. The latter is the major contribution of the proposed methodology, since previous work have only

  4. A screw theory of static beams

    Microsoft Academic Search

    J. M. Selig; X. Ding

    2001-01-01

    We derive the deflection equation of a simple beam using the screw theory. The effects of tension, torsion and bending of the beam can be unified into a single equation. We begin by looking at the compliance matrix for small elements of the beam. This is loosely based on the work by von Mises (1924). We reproduce von Mises' results

  5. Screw Compressor Characteristics for Helium Refrigeration Systems

    Microsoft Academic Search

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

    2008-01-01

    The oil injected screw compressors have practically replaced all other types of compressors in modern helium refrigeration systems due to their large displacement capacity, minimal vibration, reliability and capability of handling helium's high heat of compression. At the present state of compressor system designs for helium systems, typically two-thirds of the lost input power is due to the compression system.

  6. A model for biomass screw feeding

    Microsoft Academic Search

    Jianjun Dai; John R. Grace

    2008-01-01

    Successful feeding is critical to biomass utilization processes, but trouble-free delivery is difficult due to particle heterogeneity, physical characteristics and moisture content. A model, extended from previous models in the literature, is proposed to delineate what limits screw feeding in terms of the mechanisms of blockage and to predict torque requirements for biomass materials. Predictions on feeding of wood pellets,

  7. Spinal somatosensory evoked potential evaluation of acute nerve-root injury associated with pedicle-screw placement procedures: an experimental study.

    PubMed

    Jou, I-Ming; Hsu, Che-Chia; Chern, Tai-Chang; Chen, Wen-Yi; Dau, Yuan-Chang

    2003-03-01

    Pedicle screws for spinal fixation risk neural damage because of the proximity between screw and nerve root. We assessed whether spinal somatosensory evoked potential (SSEP) could selectively detect pedicle-screw-related acute isolated nerve injury. Because pedicle screws are too large for a rat's spine, we inserted a K-wire close to the pedicle in 32 rats, intending not to injure the nerve root in eight (controls), and to injure the L4 or L5 root in 24. We used sciatic-nerve-elicited SSEP pre- and postinsertion. Radiologic, histologic, and postmortem observations confirmed the level and degree of root injury. Sciatic (SFI), tibial (TFI), and peroneal function indices (PFI) were calculated and correlated with changes in potential. Although not specific for injuries to different roots, amplitude reduction immediately postinsertion was significant in the experimental groups. Animals with the offending wire left in place for one hour showed a further non-significant deterioration of amplitude. Electrophysiologic changes correlated with SFI and histologic findings in all groups. SSEP monitoring provided reliable, useful diagnostic and intraoperative information about the functional integrity of single nerve-root injury. These findings are clinically relevant to acute nerve-root injury and pedicle-screw insertion. If a nerve-root irritant remains in place, a considerable neurologic deficit will occur. PMID:12568971

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

    PubMed Central

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

    2013-01-01

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

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

    PubMed

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

    2015-05-01

    Spinal fixation in the osteoporotic patient can be challenging due to the poor trabecular bone quality of the vertebral body. Patients with osteoporotic vertebral body compression fractures are at risk for future compression fractures at adjacent levels, especially after cement augmentation. The purpose of this technical report is to describe the utilization of a cortical screw trajectory along with kyphoplasty for a patient with an osteoporotic compression fracture as well as degenerative spinal disease. This trajectory allows for the possibility of percutaneous pedicle access in the event of future compression fractures. Our patient underwent a decompressive laminectomy and kyphoplasty at the level of an osteoporotic compression fracture. The fracture was stabilized with cortical screw instrumentation and fusion at a level above and a level below the fracture. Subsequently the patient developed an adjacent level fracture within the fusion construct. Due to the utilization of a cortical screw trajectory for the initial fusion, the traditional pedicle trajectory was still accessible. As a result, the new fracture was treated with a percutaneous kyphoplasty through a standard pedicle trajectory. In conclusion, the use of a cortical screw trajectory for stabilization of osteoporotic compression fractures provides for a stronger bone screw interface and avoids osteoporotic trabecular vertebral body bone. At the same time this trajectory allows for future percutaneous pedicular access in the event that the patient suffers future compression fractures. PMID:25724313

  10. Treatment of a left common iliac aneurysm with endovascular Powerlink stentgraft in a patient with an occlusion of a left common iliac stent.

    PubMed

    Libeer, F; Peeters, P; Verbist, J

    2009-01-01

    Isolated iliac aneurysms are uncommon and account for only 2% of all abdominal aneurysms. Typically, patients presenting with this pathology are operated on surgically. In our patient, however, surgery could have been an option but the patient had undergone a laparotomy more than 50 years earlier because of a gun-shot wound, so we preferred an endovascular repair. Furthermore, regular endovascular repair with a straight tube stentgraft was impossible due to the absence of a proximal neck. Consequently, we opted for placing a bifurcated stentgraft to exclude the iliac aneurysm. PMID:20184070

  11. Long-Term Follow-Up of Iliac Wallstents

    SciTech Connect

    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

    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.

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

    PubMed Central

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

    2014-01-01

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

  13. Posterior lumbar interbody fusion using one diagonal fusion cage with transpedicular screw\\/rod fixation

    Microsoft Academic Search

    Jie Zhao; Tiesheng Hou; Xinwei Wang; Shengzhong Ma

    2003-01-01

    Posterior lumbar interbody fusion (PLIF) using threaded cages has gained wide popularity for lumbosacral spinal disease. Our biomechanical tests showed that PLIF using a single diagonal cage with unilateral facetectomy does add a little to spinal stability and provides equal or even higher postoperative stability than PLIF using two posterior cages with bilateral facetectomy. Studies also demonstrated that cages placed

  14. Use of a synthetic bone void filler to augment screws in osteopenic ankle fracture fixation

    Microsoft Academic Search

    GeirStray Andreassen; PerReidar Høiness; Inge Skraamm; Odd Granlund; Lars Engebretsen

    2004-01-01

    IntroductionSufficiently stable constructs may be difficult to obtain with ankle fractures in patients with severe osteopenic bone. Augmentation of the osteosynthesis with a new synthetic bone void filler may help to solve this problem, and it can improve the clinical outcome.Materials and methodsA prospective, open-label study was performed in two surgical clinics in Norway. In 37 of 42 selected patients

  15. Posterior interbody fusion using laminectomy bone and transpedicular screw fixation in the treatment of lumbar spondylolisthesis

    Microsoft Academic Search

    György I Csécsei; Álmos P Klekner; József Dobai; Attila Lajgut; Judit Sikula

    2000-01-01

    BACKGROUNDLaminectomy bone is used widely in posterolateral lumbar fusion, but not interbody fusion. No prospective evaluation of interbody fusion using bone grafts from the posterior neural arch in spondylolisthesis has been found in the literature. We prospectively studied series of patients operated on for lumbar spondylolisthesis to evaluate clinical improvement and bony fusion.METHODSForty-six patients were operated on for lumbar spondylolisthesis

  16. One point fixation of zygomatic tripod fractures in the zygomatic buttress through Keen's intraoral approach: A review of 30 cases

    PubMed Central

    Dakir, Abu; Muthumani, T.; Prabu, N. P.; Mohan, Rakesh; Maity, Abhishek

    2015-01-01

    For decades, facial beauty and esthetics have been one of the most important quests of the human race. The lateral prominence and convexity of the zygomatic bone makes it the most important bone for providing the aesthetic facial look and sets up the facial width but at the same time this prominence and convexity makes this bone more vulnerable to injury. Zygomatic complex fractures or tripod fractures are the second most common fractures after nasal fractures among facial injuries. Several studies have been undertaken regarding the reduction and fixation of zygomatic fractures with mini plates and screws. In 2002 Fujioka et al in vivo studies successfully proved that one point fixation at the zygomaticomaxillary complex gives three point alignment and sufficient rigidity when the fractures are not comminuted. In this article, 30 cases have been reviewed with one point fixation of zygomatic complex tripod fractures at the zygomatic buttress through Keen's intraoral approach along with advantages and disadvantages. PMID:26015722

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

    PubMed

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

    2009-03-01

    The quality of technique used at the time of socket cementation is crucial in ensuring a durable long-term result of the implant. We asked whether a new instrument, an aspirator retractor introduced into the wing of the ilium before socket preparation and cementation, would enhance cement fixation as defined by RSA and radiographic examination. We randomized 38 patients into two groups. The surgical technique was identical between the groups with the exception of the use of the aspirator retractor. Patients were followed clinically and with radiostereometry at a minimum of 2 years. We compared gross radiographic appearances, including the depth of penetration of cement and the incidence of postoperative and 2-year radiolucent lines. There was no difference in proximal migration between the two groups. No improvement of fixation was proven from the measured translations and rotations of the socket in the suction group. We found no difference in the number or extent of radiolucent lines or the depth of cement penetration when the iliac suction device was used in conjunction with contemporary cementing techniques. Although the data suggest no short-term advantage in this small study, we will continue to follow these patients presuming there will be improved outcomes in the longer term and since the device provides an easier method of obtaining adequate fixation, especially if technical difficulties are encountered during the pressurization procedure. PMID:18998193

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

    PubMed

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

    2015-04-01

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

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

    SciTech Connect

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

    2010-10-15

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

  20. Percutaneous Cannulated Screws with Tension Band Wiring Technique in Patella Fractures

    PubMed Central

    2013-01-01

    Introduction Most patellar fractures are transverse involving the central third. Open reduction and stabilization of transverse patellar fractures is indicated if there is more than 2-3 mm of fragment separation and/or articular incongruity. Surgical Technique This study describes a percutaneous 2 cannulated screws and modified tension band wiring technique to treat transverse patellar fractures. Materials and Methods We performed 30 cases of displaced transverse patellar fractures with this technique. The clinical outcomes of these patients were evaluated with simple radiographs, range of motion and Lyshom score. Results This technique has shown to provide satisfactory clinical results and excellent knee functions. Conclusions This technique provide stable fixation, allows early motion exercise by minimizing injury to extensor mechanism and reduce cosmetic problem in scar. PMID:24369000

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

    PubMed Central

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

    2013-01-01

    Background Salvage surgery for failed lumbar spine fusion with a loosened pedicle screw is challenging. In general, the strategy includes replacement with larger and longer pedicle screws, augmentation with polymethylmethacrylate cement or hydroxyapatite granules, and extension of fused segments. The purpose of this study is to introduce a new technique for pedicle screw replacement after failed lumbar spine fusion. Methods Five salvage operations were performed using a different trajectory (DT) pedicle screw replacement technique based on 3-dimensional radiological information. Position of the alternative pedicle screws was planned carefully on the computer screen of a computed tomography-based navigation system before the operation. To obtain sufficient initial stability, 1 of 2 techniques was chosen, depending on the patient. One technique created a completely new route, which did not interfere with the existing screw hole, and the other involved penetration of the existing screw hole. Results DT pedicle screws were replaced successfully according to the preoperative plan. In all patients, bony union were achieved at the final follow-up period without any instrument failure. Extension of the fused segments could be avoided by using the DT pedicle screw replacement technique combined with transforaminal lumbar interbody fusion. Conclusions The DT pedicle screw replacement technique is a treatment option for salvage lumbar spine surgery. Clinical relevance The current technique is a treatment option for salvage operations that can both avoid extension of a fused segment and achieve successful bony union. PMID:25694906

  2. Biomass granular screw feeding: An experimental investigation

    Microsoft Academic Search

    Jianjun Dai; John R. Grace

    2011-01-01

    Successful feeding is critical to biomass utilization processes, but difficult due to the heterogeneity, physical properties and moisture content of the particles. The objectives of the present study were to find the mechanisms of blockage in screw feeding and to determine the effects of particle mean size (0.5–15mm), size distribution, shape, moisture content (10–60%), density and compressibility on biomass particle

  3. Kidney transplantation in a patient with absent right common iliac artery and congenital renal abnormalities

    PubMed Central

    Tay, Clifton Ming; Siew, Edwin Poh Yiew; Ng, Tze-Kiat; Vathsala, Anantharanam; Tiong, Ho Yee

    2015-01-01

    Introduction Congenital atresia of the common and external iliac arteries is a rare vascular anomaly that may be associated with congenital renal or genitourinary malformations. In ESRD patients, its presence may pose potential problems during renal transplantation. Case presentation We report a rare case of kidney transplantation in a patient with VACTERL syndrome who was found to have absent right common and external iliac arteries during pre-operative imaging. Vascular supply to the right lower limb is derived from an anomalous branch from the left internal iliac artery which takes on a convoluted course across the pelvis. Kidney transplantation was performed successfully with implantation performed on the left side. Discussion Isolated cases of congenital iliac artery atresia have been described in association with urological abnormalities but no clear association has yet been established. However, we feel that it may be useful to perform routine angiographic evaluation for ESRD patients with congenital genitourinary abnormalities being planned for kidney transplantation. While most cases of congenital iliac artery anomalies are symptomatic with claudication, some remain asymptomatic with normal physical examination findings. There is some evidence in literature suggesting the usefulness of routine pre-operative CT in a selective group of patients. Conclusion Kidney transplantation in such cases is safe and we recommend routine pre-operative imaging of patients known to have congenital genitourniary abnormalities. The kidney should be implanted heterotopically to the contralateral side of the vascular anomaly and care must be taken to preserve vascular supply to the lower limbs. PMID:25839434

  4. Screw dislocations in the field theory of elastoplasticity

    NASA Astrophysics Data System (ADS)

    Lazar, Markus

    2002-10-01

    A (microscopic) static elastoplastic field theory of dislocations with moment and force stresses is considered. The relationship between the moment stress and the Nye tensor is used for the dislocation Lagrangian. We discuss the stress field of an infinitely long screw dislocation in a cylinder, a dipole of screw dislocations and a coaxial screw dislocation in a finite cylinder. The stress fields have no singularities in the dislocation core and they are modified in the core due to the presence of localized moment stress. Additionally, we calculated the elastoplastic energies for the screw dislocation in a cylinder and the coaxial screw dislocation. For the coaxial screw dislocation we find a modified formula for the so-called Eshelby twist which depends on a specific intrinsic material length.

  5. Screw dislocations in the field theory of elastoplasticity

    E-print Network

    Markus Lazar

    2002-09-30

    A (microscopic) static elastoplastic field theory of dislocations with moment and force stresses is considered. The relationship between the moment stress and the Nye tensor is used for the dislocation Lagrangian. We discuss the stress field of an infinitely long screw dislocation in a cylinder, a dipole of screw dislocations and a coaxial screw dislocation in a finite cylinder. The stress fields have no singularities in the dislocation core and they are modified in the core due to the presence of localized moment stress. Additionally, we calculated the elastoplastic energies for the screw dislocation in a cylinder and the coaxial screw dislocation. For the coaxial screw dislocation we find a modified formula for the so-called Eshelby twist which depends on a specific intrinsic material length.

  6. UK DRAFFT - A randomised controlled trial of percutaneous fixation with kirschner wires versus volar locking-plate fixation in the treatment of adult patients with a dorsally displaced fracture of the distal radius

    PubMed Central

    2011-01-01

    Background Fractures of the distal radius are extremely common injuries in adults. However, the optimal management remains controversial. In general, fractures of the distal radius are treated non-operatively if the bone fragments can be held in anatomical alignment by a plaster cast or orthotic. However, if this is not possible, then operative fixation is required. There are several operative options but the two most common in the UK, are Kirschner-wire fixation (K-wires) and volar plate fixation using fixed-angle screws (locking-plates). The primary aim of this trial is to determine if there is a difference in the Patient-Reported Wrist Evaluation one year following K-wire fixation versus locking-plate fixation for adult patients with a dorsally-displaced fracture of the distal radius. Methods/design All adult patients with an acute, dorsally-displaced fracture of the distal radius, requiring operative fixation are potentially eligible to take part in this study. A total of 390 consenting patients will be randomly allocated to either K-wire fixation or locking-plate fixation. The surgery will be performed in trauma units across the UK using the preferred technique of the treating surgeon. Data regarding wrist function, quality of life, complications and costs will be collected at six weeks and three, six and twelve months following the injury. The primary outcome measure will be wrist function with a parallel economic analysis. Discussion This pragmatic, multi-centre trial is due to deliver results in December 2013. Trial registration Current Controlled Trials ISRCTN31379280 UKCRN portfolio ID 8956 PMID:21914196

  7. Molybdenum Trafficking for Nitrogen Fixation

    PubMed Central

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

    2009-01-01

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

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

    PubMed Central

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

    2013-01-01

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

  9. The gauge theory of dislocations: A nonuniformly moving screw dislocation

    NASA Astrophysics Data System (ADS)

    Lazar, Markus

    2010-07-01

    We investigate the nonuniform motion of a straight screw dislocation in infinite media in the framework of the translational gauge theory of dislocations. The equations of motion are derived for an arbitrarily moving screw dislocation. The fields of the elastic velocity, elastic distortion, dislocation density and dislocation current surrounding the arbitrarily moving screw dislocation are derived explicitly in the form of integral representations. We calculate the radiation fields and the fields depending on the dislocation velocities.

  10. Screw theoretic view on dynamics of spatially compliant beam

    Microsoft Academic Search

    Xi-lun Ding; J. M. Selig

    2010-01-01

    Beams with spatial compliance can be deformed as bending in a plane, twisting, and extending. In terms of the screw theory\\u000a on rigid body motions, the concept of “deflection screw” is introduced, a spatial compliant beam theory via the deflection\\u000a screw is proposed, and the spatial compliance of such a beam system is presented and analysed based on the material

  11. Complement fixation test to C. burnetii

    MedlinePLUS

    The complement fixation test to C. burnetii is a blood test that checks for infection due to bacterium called ... for Coxiella antibodies using a laboratory method called complement fixation. This technique checks if the body has ...

  12. Minimally Invasive Technique for PMMA Augmentation of Fenestrated Screws

    PubMed Central

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

    2015-01-01

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

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

    PubMed Central

    Howat, William J.; Wilson, Beverley A.

    2014-01-01

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

  14. Venous Covered Stent: Successful Occlusion of a Symptomatic Internal Iliac Arteriovenous Fistula

    SciTech Connect

    Cronin, P.; McPherson, S.; Meaney, J.F. [Department of Radiology, Jubilee Wing, Leeds General Infirmary, Great George Street, Leeds LS1 3EX (United Kingdom); Mavor, A. [Department of Vascular Surgery, Leeds General Infirmary, Great George Street, Leeds LS1 3EX (United Kingdom)

    2002-08-15

    We report the placement of a covered stent within the internal iliac vein (IIV) to occlude a symptomatic iatrogenic internal iliac arteriovenous fistula following an abdominal aortic graft. Angiography revealed a direct communication between an internal iliac graft to artery anastomosis and the right IIV with rapid shunting into the inferior vena cava and a small associated pseudoaneurysm. Femoral, brachial or axillary arterial access was precluded. The fistula was successfully occluded by a stent-graft placed in the IIV. Arteriovenous fistula can be treated in a number of ways including covered stent placement on the arterial side. To the best of our knowledge this is the first time placement in a vein has been described. Where access is difficult or the procedure carries a high risk of complication, avenous covered stent may offer an alternative.

  15. [Cockett's syndrome, May-Thurner syndrome, or iliac vein compression syndrome].

    PubMed

    Gil Martín, A R; Carreras Aja, M; Arrieta Ardieta, I; Labayen Azparren, I

    2014-01-01

    Iliac vein compression syndrome (also known as May-Thurner syndrome or Cockett's syndrome) is a rare clinical entity in which the left common iliac vein is compressed when it passes between the right common iliac artery and the spine. The sustained compression and trauma caused by the pulsatile force of the artery on the vein damage the intima and lead to the formation of membranes or bands in the vascular lumen that hinder or obstruct the flow of blood in the vein, favoring thrombus formation. The current treatment strategy of choice is endovascular vein patch angioplasty and stenting with the aim of improving the caliber of the lumen and enabling normal venous drainage. We present two cases of May-Thurner syndrome and review the clinical and CT findings. PMID:22621823

  16. CARBON FIXATION BY CULTURED CLAMSCARBON FIXATION BY CULTURED CLAMSCARBON FIXATION BY CULTURED CLAMSCARBON FIXATION BY CULTURED CLAMS Patrick BakerPatrick Baker

    E-print Network

    Florida, University of

    CARBON FIXATION BY CULTURED CLAMSCARBON FIXATION BY CULTURED CLAMSCARBON FIXATION BY CULTURED, Gainesville, FL, USA Clam Farming in FloridaClam Farming in Florida Calculating Carbon per Clam Bag E t l th E th g Calculating Carbon per Clam Bag Eat a clam, save the EarthEat a clam, save the Earth · Northern

  17. FIXATIVES AND EMBEDDING MEDIA FOR IMMUNOCYTOCHEMISTRY

    Microsoft Academic Search

    B. B. Rawdon

    1998-01-01

    In this article fixation and embedding procedures compatible with preparation of animal tissues for immunocytochemistry are reviewed. A number of methods is available for light microscopic immunocytochemistry: these include cryostat, freeze-dried and wax sections of tissue fixed with either vapour or immersion fixatives. Use of the microwave oven to fix tissues for immunocytochemistry is also discussed. Fixation methods for immuno-electron

  18. Transit Fixatives: An Innovative Study

    PubMed Central

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

    2015-01-01

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

  19. Posterior atlantoaxial fixation: A cadaveric and fluoroscopic step-by-step technical guide

    PubMed Central

    Sattarov, Kamran; Skoch, Jesse; Abbasifard, Salman; Patel, Apar S.; Avila, Mauricio J.; Walter, Christina M.; Baaj, Ali A.

    2015-01-01

    Background: Atlantoaxial surgical fixation is widely employed treatment strategy for a myriad of pathologies affecting the stability of the atlantoaxial joint. The most common technique used in adults, and in certain cases in children, involves a posterior construct with C1 lateral mass screws, and C2 pars or pedicle screws. This technical note aims to provide a step-by-step guide to this procedure using cadaveric and fluoroscopic images. Methods: An embalmed, human, cadaveric, specimen was used for this study. The subject did not have obvious occipital-cervical pathology. Dissections and techniques were performed to mimic actual surgical technique. Photographs were taken during each step, and the critical aspects of each step were highlighted. Fluoroscopic images from a real patient undergoing C1/C2 fixation were also utilized to further highlight the anatomic-radiographic relationships. This study was performed without external or industry funding. Results: Photographic and radiographic pictures and drawings are presented to illustrate the pertinent anatomy and technical aspects of this technique. The nuances of each step, including complication avoidance strategies are also highlighted. Conclusions: Given the widespread utilization of this technique, described step-by-step guide is timely for surgeons and trainees alike. PMID:26005587

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

    PubMed

    Lee, Eugene S; Dawson, David L

    2010-01-01

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

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

    SciTech Connect

    Kwon, Joon Ho; Kim, Man Deuk, E-mail: mdkim@yuhs.ac; Lee, Kwang-hun; Lee, Myungsu; Lee, Mu Sook; Won, Jong Yun; Park, Sung Il; Lee, Do Yun [Yonsei University College of Medicine, Department of Radiology, Research Institute of Radiological Science, Severance Hospital (Korea, Republic of)] [Yonsei University College of Medicine, Department of Radiology, Research Institute of Radiological Science, Severance Hospital (Korea, Republic of)

    2013-02-15

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

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

    PubMed Central

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

    2015-01-01

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

  3. May-Thurner syndrome (iliac vein compression) and thrombosis in adolescents.

    PubMed

    Raffini, Leslie; Raybagkar, Deepti; Cahill, Anne Marie; Kaye, Robin; Blumenstein, Marilyn; Manno, Catherine

    2006-11-01

    May-Thurner syndrome refers to anatomic compression of the left iliofemoral vein by the overriding right iliac artery. We report three adolescents who presented to our pediatric hospital with iliac vein thrombosis and were diagnosed with May-Thurner syndrome. Each received catheter-directed thrombolysis followed by balloon angioplasty to restore flow. Two patients had endovascular stents placed. The procedures were well tolerated, without major complications. Additional thrombophilic risk factors were identified in each patient. Though uncommon, pediatric hematologists should consider May-Thurner syndrome in adolescents who present with a left lower extremity thrombosis. Aggressive therapy may be warranted due to the risk of post-thrombotic syndrome. PMID:16365865

  4. Postfusion pullout strength comparison of a novel pedicle screw with classical pedicle screws on synthetic foams.

    PubMed

    Arslan, Arslan K; Demir, Teyfik; Ormeci, Mehmet F; Camu?cu, Necip; Türeyen, Kudret

    2013-02-01

    Pullout is a very common failure mode on the use of pedicle screws. Numerous studies were completed to increase the pullout strength of pedicle screws especially for osteoporotic bones. In this study, a previously designed pedicle screw type was tested before and after fusion condition. Synthetic polyurethane foams were used in all tests. Three different grades of foams were used in tests to simulate severely osteoporotic, osteoporotic, and healthy bones. Test blocks were produced and characterized in our clinical biomechanics laboratory. Foaming of polyurethane was accepted as fusion process (bone in growth). Pedicle screw including radial holes (new design) was tested both before and after the fusion. It also exhibited remarkably higher pullout strength after fusion than before fusion and most of other alternatives stated in the literature. In total, 70% higher pullout strength was achieved with new design after fusion. On the other hand, new design did not dominate other alternatives when comparison was carried out on severely osteoporotic and healthy bones. To the knowledge of the authors, this is the first study investigating the postfusion properties on synthetic foams. PMID:23513982

  5. Wet granulation in a twin-screw extruder: implications of screw design.

    PubMed

    Thompson, M R; Sun, J

    2010-04-01

    Wet granulation in twin-screw extrusion machinery is an attractive technology for the continuous processing of pharmaceuticals. The performance of this machinery is integrally tied to its screw design yet little fundamental knowledge exists in this emerging field for granulation to intelligently create, troubleshoot, and scale-up such processes. This study endeavored to systematically examine the influence of different commercially available screw elements on the flow behavior and granulation mechanics of lactose monohydrate saturated at low concentration (5-12%, w/w) with an aqueous polyvinyl-pyrrolidone binder. The results of the work showed that current screw elements could be successfully incorporated into designs for wet granulation, to tailor the particle size as well as particle shape of an agglomerate product. Conveying elements for cohesive granular flows were shown to perform similar to their use in polymer processing, as effective transport units with low specific mechanical energy input. The conveying zones provided little significant change to the particle size or shape, though the degree of channel fill in these sections had a significant influence on the more energy-intensive mixing elements studied. The standard mixing elements for this machine, kneading blocks and comb mixers, were found to be effective for generating coarser particles, though their mechanisms of granulation differed significantly. PMID:19890935

  6. Modeling bicortical screws under a cantilever bending load.

    PubMed

    James, Thomas P; Andrade, Brendan A

    2013-12-01

    Cyclic loading of surgical plating constructs can precipitate bone screw failure. As the frictional contact between the plate and the bone is lost, cantilever bending loads are transferred from the plate to the head of the screw, which over time causes fatigue fracture from cyclic bending. In this research, analytical models using beam mechanics theory were developed to describe the elastic deflection of a bicortical screw under a statically applied load. Four analytical models were developed to simulate the various restraint conditions applicable to bicortical support of the screw. In three of the models, the cortical bone near the tip of the screw was simulated by classical beam constraints (1) simply supported, (2) cantilever, and (3) split distributed load. In the final analytical model, the cortices were treated as an elastic foundation, whereby the response of the constraint was proportional to screw deflection. To test the predictive ability of the new analytical models, 3.5?mm cortical bone screws were tested in a synthetic bone substitute. A novel instrument was developed to measure the bending deflection of screws under radial loads (225?N, 445?N, and 670?N) applied by a surrogate surgical plate at the head of the screw. Of the four cases considered, the analytical model utilizing an elastic foundation most accurately predicted deflection at the screw head, with an average difference of 19% between the measured and predicted results. Determination of the bending moments from the elastic foundation model revealed that a maximum moment of 2.3?N m occurred near the middle of the cortical wall closest to the plate. The location of the maximum bending moment along the screw axis was consistent with the fracture location commonly observed in clinical practice. PMID:24105350

  7. Screw-type pump for coal feeding

    SciTech Connect

    Hilbert, J.D. Jr.

    1983-05-01

    This article describes the Type-M pumps system, which provides the reliable and accurate coal feeding needed for the success of fluidized-bed combustion and other coal-firing requirements. The Type-M pump feed unit provides the safety feature with its internal flapper valve to prevent the possibility of blowback. It features bearing supports at both ends of the screw impeller shaft which permits smooth running and maintenance-free operation under variable feed and light load conditions. It has demonstrated its capability to handle not only finely pulverized coal but also coarse coal as well as a mixture of coarse coal and 1/8 x 0 limestone.

  8. Injection of coal by screw feed

    NASA Technical Reports Server (NTRS)

    Fisher, R.

    1977-01-01

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

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

    PubMed Central

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

    2014-01-01

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

  10. Bifurcated Aortoiliac Endograft Limb Occlusion during Deployment and Its Bailout Conversion Using the External Iliac Artery to Internal Iliac Artery Endograft Technique.

    PubMed

    Kehagias, Elias; Kontopodis, Nikolaos; Tsetis, Dimitrios; Ioannou, Christos V

    2015-07-01

    Endovascular aneurysm repair has become the preferred method to treat abdominal aortic aneurysms (AAAs). The Ovation TriVascular Stent-Graft system introduces a unique concept of separation of the metal (stent) and fabric (graft) portion of the endograft's main body to facilitate delivery through ultra-low profile 14F devices. In the setting of a narrow distal aneurysmal lumen, usually due to the presence of thrombus, deployment of this endograft may be complicated by folding and collapse of the (unsupported by a stent) aortic body or limbs, making catheterization and ballooning impossible. We present a case of Ovation endograft contralateral limb collapse in a tight AAA lumen due to thrombus deposition, which led to folding and total occlusion of the limb and made limb catheterization impossible. This is a real-life example of how the external iliac artery to internal iliac artery endograft technique may be used as a bailout procedure, converting the procedure into an aortouni-iliac graft. To our knowledge, this is the first reported bailout use of this technique in English literature which may be used in selected cases. PMID:25770386

  11. Fatigue strength of common tibial intramedullary nail distal locking screws

    Microsoft Academic Search

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

    2009-01-01

    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

  12. Screw dislocation in zirconium: an ab initio study Emmanuel Clouet

    E-print Network

    Paris-Sud XI, Université de

    Screw dislocation in zirconium: an ab initio study Emmanuel Clouet CEA, DEN, Service de Recherches in zirconium is controlled by 1/3 1¯210 screw dislocations gliding in the prism planes of the hexagonal close zirconium and is known to be related to the number of valence electrons in the d band. We use ab initio

  13. Accuracy analysis of SCARA industrial robot based on screw theory

    Microsoft Academic Search

    Zhao Liang; Su Meng; Diao Changkun

    2011-01-01

    Based on an analysis of error sources of industrial robots, we build a pose error model of industrial robots with screw theory, which overcomes the defect that the error on the y-axis could not be reflected by the classical D-H parameter method. Given the error sources which influence the end- executor's accuracy, we established a screw representation of the static

  14. Manufacturing of the composite screw rotors by resin transfer molding

    Microsoft Academic Search

    Young Goo Kim; Dai Gil Lee; Park Kyoun Oh

    1995-01-01

    A screw-type pump with at least two rotors that are composed of male and female rotors with helical extending lands and grooves is increasingly used because it has a smaller weight to power ratio and produces less noise and vibration compared to conventional reciprocating pumps.Most male and female rotors of the screw type pump have been manufactured by machining. The

  15. A simple method to ensure proper screw position and plate size selection using the Morscher cervical spine locking plate. Technical note.

    PubMed

    Ball, P A; Benzel, E C; Baldwin, N G

    1994-04-01

    The use of bone plate instrumentation with screw fixation has proved to be a useful adjunctive measure in anterior cervical spine fusion surgery. Proper fitting, positioning, and attachment of this instrumentation have been shown to be frequently suboptimal if done without radiographic guidance. The most commonly used method of radiographic assistance for placement of this instrumentation is fluoroscopy. While this gives satisfactory technical results, it is expensive and time-consuming, and exposes the patient and the operating room personnel to ionizing radiation. The authors present a simple technique to ensure screw placement and plate fitting using Kirschner wires and a single lateral radiograph. This technique saves time, reduces exposure to radiation, and has led to satisfactory results in over 20 operative cases. PMID:8151358

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

    PubMed Central

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

    2014-01-01

    Background: Double bundle anterior cruciate ligament (DBACL) reconstruction is said to reproduce the native anterior cruciate ligament (ACL) anatomy better than single bundle anterior cruciate ligament, whether it leads to better functional results is debatable. Different fixation methods have been used for DBACL reconstruction, the most common being aperture fixation on tibial side and cortical suspensory fixation on the femoral side. We present the results of DBACL reconstruction technique, wherein on the femoral side anteromedial (AM) bundle is fixed with a crosspin and aperture fixation was done for the posterolateral (PL) bundle. Materials and Methods: Out of 157 isolated ACL injury patients who underwent ACL reconstruction, 100 were included in the prospective study. Arthroscopic DBACL reconstruction was done using ipsilateral hamstring autograft. AM bundle was fixed using Transfix (Arthrex, Naples, FL, USA) on the femoral side and bio interference screw (Arthrex, Naples, FL, USA) on the tibial side. PL bundle was fixed on femoral as well as on tibial side with a biointerference screw. Patients were evaluated using KT-1000 arthrometer, Lysholm score, International Knee Documentation Committee (IKDC) Score and isokinetic muscle strength testing. Methods: Out of 157 isolated ACL injury patients who underwent ACL reconstruction, 100 were included in the prospective study. Arthroscopic DBACL reconstruction was done using ipsilateral hamstring autograft. AM bundle was fixed using Transfix (Arthrex, Naples, FL, USA) on the femoral side and bio interference screw (Arthrex, Naples, FL, USA) on the tibial side. PL bundle was fixed on femoral as well as on tibial side with a biointerference screw. Patients were evaluated using KT-1000 arthrometer, Lysholm score, International Knee Documentation Committee (IKDC) Score and isokinetic muscle strength testing. Results: The KT-1000 results were evaluated using paired t test with the P value set at 0.001. At the end of 1 year, the anteroposterior side to side translation difference (KT-1000 manual maximum) showed mean improvement from 5.1 mm ± 1.5 preoperatively to 1.6 mm ± 1.2 (P < 0.001) postoperatively. The Lysholm score too showed statistically significant (P < 0.001) improvement from 52.4 ± 15.2 (range: 32-76) preoperatively to a postoperative score of 89.1 ± 3.2 (range 67-100). According to the IKDC score 90% patients had normal results (Category A and B). The AM femoral tunnel initial posterior blow out was seen in 4 patients and confluence in the intraarticular part of the femoral tunnels was seen in 6 patients intraoperatively. The quadriceps strength on isokinetic testing had an average deficit of 10.3% while the hamstrings had a 5.2% deficit at the end of 1 year as compared with the normal side. Conclusion: Our study revealed that the DBACL reconstruction using crosspin fixation for AM bundle and aperture fixation for PL bundle on the femoral side resulted in significant improvement in KT 1000, Lysholm and IKDC scores. PMID:24600062

  17. Screw dislocations in GaN

    SciTech Connect

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

    2002-02-15

    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.

  18. Percutaneous Endovascular Stent-Graft for Iliac Pseudoaneurysm Following Lumbar Discectomy

    SciTech Connect

    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

    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.

  19. Endovascular Treatment of Proximal Bilateral Iliac Limb Dislocation and Kinking following Endovascular Abdominal Aortic Aneurysm Repair

    SciTech Connect

    Alerci, Mario; Wyttenbach, Rolf [Ospedale San Giovanni, Department of Radiology (Switzerland)], E-mail: rolf.wyttenbach@bluewin.ch; Bogen, Marcel [Ospedale San Giovanni, Department of Surgery (Switzerland); Segesser, Ludwig K. von [Centre Hospitalier Universitaire Vaudois-CHUV, Department of Cardiovascular Surgery (Switzerland); Gallino, Augusto [Ospedale San Giovanni, Department of Vascular Medicine (Switzerland); Inglese, Luigi [Ospedale San Donato, Servizio di Emodinamica (Italy)

    2005-05-15

    We report the case of a 69-year-old man with a late type 1b endoleak due to proximal migration of both iliac limbs 5 years after endovascular repair of an abdominal aortic aneurysm. The endovascular method used to correct bilaterally this condition is described. Final angiographic control shows patency of the stent-graft without signs of endoleak.

  20. Post-Kidney Transplantation Iliac Artery Stenosis due toIatrogenic Injury: Case Report

    SciTech Connect

    Khankan, Azzam Anwar, E-mail: akhankan@radiol.med.osaka-u.ac.jp; Maeda, Munehiro; Osuga, Keigo; Murakami, Takamichi; Nakamura, Hironobu [Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka 565-0871, Department of Radiology (Japan)

    2003-04-15

    We report a case of left external iliac artery lesions as a complication of post-kidney transplantation due to vascular clamp application injury. The lesions were proximal stenosis and distal occlusion just near the graft anastomosis site and they were diagnosed incidentally during the embolization for arteriovenous fistula. Angiography confirmed the diagnosis and it was managed successfully by percutaneous interventional techniques.

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

    PubMed Central

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

    2015-01-01

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

  2. Use of the Vascularized Iliac-Crest Flap in Musculoskeletal Lesions

    PubMed Central

    Tonoli, Cristiane; Bechara, Alexandre H. S.; Rossanez, Roberto; Belangero, William D.; Livani, Bruno

    2013-01-01

    Bone loss was in the past treated by several methods, such as bone distraction and the use of nonvascularized or tissue-bank bone grafts. With the advent of modern microsurgical techniques, the vascularized bone flap has been used with good results; it resolves local nutritional problems, repairs soft tissue that is often damaged by severe trauma, and treats bone loss due to tumors, pseudarthroses, and osteomyelitis. This paper reports the authors' experience with the use of vascularized iliac-crest flaps to treat orthopedic pathologies in five patients with traumatic bone loss (<10?cm), three with osteomyelitis, and three with atrophic nonunion. In all cases, the same surgeon obtained a vascularized iliac-crest flap with a pedicle based on the deep iliac circumflex artery. All flaps consolidated within a mean period of 3 months. These findings demonstrate that the use of an iliac-crest flap is a treatment option in cases of bone loss and that it is associated with good functional results and minimal donor-site morbidity. PMID:24233062

  3. Forensic age estimation through evaluation of the apophyseal ossification of the iliac crest in Western Chinese.

    PubMed

    Zhang, Kui; Dong, Xiao-Ai; Chen, Xiao-Gang; Li, Yuan; Deng, Zhen-Hua

    2015-07-01

    The criminal age estimation procedures have gained greatest significance to date, a reliable age diagnostics may depend on data of skeletal maturation from different socioeconomic status. In order to establish the iliac crest apophysis as a possible criterion for forensic age estimation in a different socioeconomic status, and to examine the pace of ossification for the iliac crest apophysis in Western Chinese, one thousand seven hundreds and seventy-seven conventional pelvic radiographs relating to West China Han group routinely taken between January 2010 and June 2012 have been sighted. The data was analysed with separation of the sexes. The results indicated that stage 2a was last observed in females at the age of 17.00 and in males at the age of 18.01, stage 3a was first achieved in females at the age of 14.46 and in males at the age of 15.31, stage 4 was observed between 17.95 and 25.98 years for male and between 18.36 and 25.95 years for female. By comparison with previous studies, our research indicated that Western Chinese presents a delaying development for the iliac crest apophysis. Furthermore, the present study with eight stages of ossification for the iliac crest offers a valuable alternative method of estimation of 18 years of age for Western Chinese. PMID:25982819

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

    NASA Technical Reports Server (NTRS)

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

    2004-01-01

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

  5. Clinical application of a new plate fixation system in open-door laminoplasty.

    PubMed

    Jiang, Liangjun; Chen, Weishan; Chen, Qixin; Xu, Kan; Wu, Qionghua; Li, Fangcai

    2012-02-01

    The purpose of this retrospective clinical series was to evaluate the benefits and complications of plate fixation for open-door laminoplasty in cervical spondylotic myelopathy with multilevel spinal stenosis compared with open-door laminoplasty without fixation. Forty-nine patients underwent open-door laminoplasty for cervical myelopathy with multilevel spinal stenosis with at least 13 months of follow-up. A plate was used as the sole method of fixation between the lateral mass and lamina with 3 screws. Computed tomography scans obtained pre- and postoperatively were assessed for plate complications and spinal canal enlargement. Pre- and postoperative neurological condition was assessed by the Japanese Orthopedic Association (JOA) myelopathy score. Overall cervical spine range of motion (ROM) was measured in full flexion and extension radiographs pre- and postoperatively. No restenosis due to door reclosure was noted, and no plates failed. No screws were backed out or broken. Almost all patients showed neurological improvement. The JOA score increased by 3.9±0.7 points in the suture group and 4.3±0.8 points in the plate group (P>.05). The postoperative increase in mean anteroposterior diameter of the spinal canal from C3 to C7 was 4.5±0.6 mm in the suture group and 5.1±0.5 mm in the plate group. The greater mean anteroposterior diameter increase in the plate group was statistically significant (P<.01). The mean cervical ROM decreased in the plate and suture groups postoperatively (P<.001). No significant difference was found in mean cervical ROM reduction between the groups (P>.05). No difference in axial symptoms was found between the 2 groups. PMID:22310411

  6. Surgical Repair of Transplant Renal Artery Stenosis With Preserved Cadaveric Iliac Artery Grafts

    PubMed Central

    Shames, Brian D.; Odorico, Jon S.; D’Alessandro, Anthony M.; Pirsch, John D.; Sollinger, Hans W.

    2003-01-01

    Objective To review the authors’ experience with ABO-matched, preserved, cadaveric, iliac artery grafts for treatment of transplant renal artery stenosis (TRAS). Summary Background Data TRAS is an important and treatable cause of hypertension and graft dysfunction in renal allograft recipients. Surgical treatment is reserved for lesions that are not amenable to percutaneous transluminal angioplasty (PTA) or for recurrence after PTA. Various surgical options for reconstruction of the transplant renal artery exist, although no single technique has been demonstrated to be superior. The authors have used preserved, blood type-matched, iliac artery grafts procured from cadaver organ donors to reconstruct transplant renal arteries in patients with specific lesions and following unsuccessful PTAs. Methods Between 1991 and 2001, 21 patients underwent reconstruction of allograft renal arteries using cadaveric iliac artery as conduit. Charts, operative notes, and imaging studies of all patients were reviewed. A successful intervention for TRAS was defined as technical success as well as a decrease in serum creatinine and/or blood pressure 6 weeks after the procedure. Development of a hemodynamically significant lesion following renal artery reconstruction was considered a recurrence. Results In patients treated with surgical reconstruction, hemodynamically significant TRAS occurred at or within 1 to 2 mm of the anastomosis in 13 patients, in the middle of the renal artery in 4, and secondary to a kink in 2 patients. Surgical treatment was undertaken in seven patients following unsuccessful PTA. Two patients had aneurysms of the iliac artery. Reconstruction using cadaveric iliac artery was successful in 19 of 21 (90%) patients, and only 1 these patients (4.8%) failed due to recurrence, with a median follow-up of 42 months. Graft loss secondary to TRAS occurred in two patients. The authors have not seen any long-term complications related to cadaveric iliac artery grafts, and the majority of the allografts continue to function well. Conclusions Surgical reconstruction of the transplant renal artery with blood type-matched iliac artery grafts should be considered a viable option for patients with specific anatomic lesions, those who have had an unsuccessful PTA, and those with recurrence following PTA. PMID:12496538

  7. Machining of a bioactive nanocomposite orthopedic fixation device.

    PubMed

    Sparnell, Amie; Aniket; El-Ghannam, Ahmed

    2012-08-01

    Bioactive ceramics bond to bone and enhance bone formation. However, they have poor mechanical properties which restrict their machinability as well as their application as load bearing implants. The goal of this study was to machine bioactive fixation screws using a silica-calcium phosphate nanocomposite (SCPC50). The effect of compact pressure, holding time, and thermal treatment on the microstructure, machinability, and mechanical properties of SCPC50 cylinders were investigated. Samples prepared by powder metallurgy technique at compact pressure range of 100-300 MPa and treated at 900°C/1 h scored a poor machinability rating of (1/5) due to the significant formation of amorphous silicate phase at the grain boundaries. On the other hand, lowering of compact pressure and sintering temperature to 30 MPa/3 h and 700°C/2 h, respectively, minimized the formation of the amorphous phase and raised the machinability rating to (5/5). The modulus of elasticity and ultimate strength of machinable SCPC50 were 10.8 ± 2.0 GPa and 72.8 ± 22.8 MPa, respectively, which are comparable to the corresponding values for adult human cortical bone. qRT-PCR analyses showed that bone cells attached to SCPC50 significantly upregulated osteocalcin mRNA expression as compared to the cells on Ti-6Al-4V. Moreover, cells attached to SCPC50 produced mineralized bone-like tissue within 8 days. On the other hand, cells attached to Ti-6Al-4V failed to produce bone mineral under the same experimental conditions. Results of the study suggest that machinable SCPC50 has the potential to serve as an attractive new material for orthopedic fixation devices. PMID:22692822

  8. Salvaging the pullout strength of stripped screws in osteoporotic bone.

    PubMed

    Pechon, Pierre H M; Mears, Simon C; Langdale, Evan R; Belkoff, Stephen M

    2013-06-01

    Our goal was to determine whether the pullout strength of stripped screw holes in osteoporotic bone could be increased with readily available materials from the operating room. We inserted 3.5-mm stainless steel nonlocking self-tapping cortical screws bicortically into 5 osteoporotic humeri. Each screw was first stripped by rotating it 1 full turn past maximum torque. In the control group, the screw was pulled out using an MTS machine (858; MTS Inc, Eden Prairie, Minnesota). In the treatment groups, the screw was removed, the hole was augmented with 1 of the 3 materials (stainless steel wire, polysorb suture, or polyethylene terephthalate glycol plastic sheet), and the screws were replaced and then pulled out. The effect of material on pullout strength was checked for significance (P < .05) using a general linearized latent and mixed model (Stata10; StataCorp, College Station, Texas). The mean (95% confidence interval) pullout strength for the unaugmented hole was 138 N (range 88-189), whereas the holes augmented with plastic, suture, or wire had mean pullout strengths of 255 N (range 177-333), 228 N (range 149-308), and 396 N (range 244-548), respectively. Although wire augmentation resulted in pullout strength that was significantly greater than that of the unaugmented screw, it was still below that of the intact construct. PMID:24093076

  9. Salvaging the Pullout Strength of Stripped Screws in Osteoporotic Bone

    PubMed Central

    Pechon, Pierre H. M.; Mears, Simon C.; Langdale, Evan R.; Belkoff, Stephen M.

    2013-01-01

    Our goal was to determine whether the pullout strength of stripped screw holes in osteoporotic bone could be increased with readily available materials from the operating room. We inserted 3.5-mm stainless steel nonlocking self-tapping cortical screws bicortically into 5 osteoporotic humeri. Each screw was first stripped by rotating it 1 full turn past maximum torque. In the control group, the screw was pulled out using an MTS machine (858; MTS Inc, Eden Prairie, Minnesota). In the treatment groups, the screw was removed, the hole was augmented with 1 of the 3 materials (stainless steel wire, polysorb suture, or polyethylene terephthalate glycol plastic sheet), and the screws were replaced and then pulled out. The effect of material on pullout strength was checked for significance (P < .05) using a general linearized latent and mixed model (Stata10; StataCorp, College Station, Texas). The mean (95% confidence interval) pullout strength for the unaugmented hole was 138 N (range 88-189), whereas the holes augmented with plastic, suture, or wire had mean pullout strengths of 255 N (range 177-333), 228 N (range 149-308), and 396 N (range 244-548), respectively. Although wire augmentation resulted in pullout strength that was significantly greater than that of the unaugmented screw, it was still below that of the intact construct. PMID:24093076

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

    PubMed Central

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

    2013-01-01

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

  11. Sacrospinous ligament fixation for vaginal vault prolapse

    Microsoft Academic Search

    T. Lantzsch; C. Goepel; M. Wolters; H. Koelbl; H. D. Methfessel

    2001-01-01

    Introduction. To assess intra- and postoperative complications and to look for long term follow-up results in women with sacrospinous ligament\\u000a fixation. Methods. Between 1988 and 1999, 200 women (mean age 59.8 years, range 33 to 83 years) underwent vaginal unilateral sacrospinous ligament\\u000a fixation. 172 patients had had prior hysterectomy. In 28 patients concomitant hysterectomy and sacrospinous ligament fixation\\u000a was performed.

  12. Helical screw rheometer: a new concept in rotational rheometry

    SciTech Connect

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

    1984-01-01

    The helical screw rheometer represents a new concept in viscometry: a rotational instrument that generates a pressure difference and therefore does not require torque measurement. The device is basically a metering screw that operates with no discharge. The results that are necessary to obtain the power-law constitutive parameters from pressure drop and rotation rate data are presented along with comparisons between theory and experiment for a prototype instrument operated at ambient conditions. The helical screw rheometer may offer advantages over conventional instruments for: 1) high-pressure measurements, 2) chemically-reacting fluids, 3) heterogeneous fluids and 4) on-line measurements.

  13. Analysis of Material Flow in Screw Extrusion of Aluminum

    SciTech Connect

    Haugen, Bjoern; Oernskar, Magnus; Welo, Torgeir; Wideroee, Fredrik [Department of Engineering Design and Materials, NTNU (Norway)

    2010-06-15

    Screw extrusion of aluminum is a new process for production of aluminum profiles. The commercial potential could be large. Little experimental and numerical work has been done with respect to this process.The material flow of hot aluminum in a screw extruder has been analyzed using finite element formulations for the non-Newtonian Navier-Stokes equations. Aluminum material properties are modeled using the Zener-Holloman material model. Effects of stick-slip conditions are investigated with respect to pressure build up and mixing quality of the extrusion process.The numerical results are compared with physical experiments using an experimental screw extruder.

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

    PubMed

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

    2014-04-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2011-10-01

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

  16. Modeling fixation locations using spatial point processes.

    PubMed

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

    2013-01-01

    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

  17. PERIODATE-LYSINE-PARAFORMALDEHYDE FIXATIVE A NEW FIXATIVE FOR IMMUNOELECTRON MICROSCOPY

    Microsoft Academic Search

    PAUL K. NAKANE

    A new fixative which primarily stabilizes carbohydrate moieties was developed for immunoelectron microscopy. It contains periodate, lysine and paraformaldehyde. Theoreti- cally, the carbohydrates are oxidized by periodate and cross-linked by lysine. The fixative can preserve antigenicity as well as paraformaldehyde and ultrastructure as well as glutaraldehyde. Using this fixative and the peroxidase-labeled antibody technique, base- ment membrane antigen was localized

  18. Evolution from open surgical to endovascular treatment of ureteral-iliac artery fistula

    PubMed Central

    Malgor, Rafael D.; Oderich, Gustavo S.; Andrews, James C.; McKusick, Michael; Kalra, Manju; Misra, Sanjay; Gloviczki, Peter; Bower, Thomas C.

    2015-01-01

    Purpose To review the indications and results of open surgical and endovascular treatment for ureteral-iliac artery fistula (UIAF). Methods We reviewed the clinical data of 20 consecutive patients treated for 21 UIAFs between 1996 and 2010. Since 2004, iliac artery stent grafts were the primary treatment except for complex fistulas with enteric contamination or abscess. Endpoints were early morbidity and mortality, patient survival, vessel or graft patency, freedom from vascular or stent graft/graft infection, and freedom from recurrent bleeding. Results There were 20 patients, 15 females, and five males, with mean age of 63 ± 13 years. Predisposing factors for UIAF were prior tumor resection in 18 patients, radiation in 15, ureteral stents in 15, ileal conduits in four, and ileofemoral grafts in three. All patients presented with hematuria, which was massive in 10. Treatment included iliac stent grafts in 11 patients/12 fistulas (55%), with internal iliac artery (IAA) exclusion in nine, femoral crossover graft with IAA exclusion in five, direct arterial repair in three, and ureteral exclusion with percutaneous nephrostomy and no arterial repair in one. There were no early deaths. Five of eight patients treated by open surgical repair developed complications, which included enterocutaneous fistula in three and superficial wound infection in two. Four patients (36%) treated by iliac stent grafts had complications, including pneumonia, non-ST segment elevation myocardial infarction, buttock claudication, and early stent occlusion in one each. After a median follow-up of 26 months, no one had recurrent massive hematuria, but minor bleeding was reported in three. Patient survival at 5 years was 42% compared with 93% for the general population (P < .001). Freedom from any recurrent bleeding at 3 years was 76%. In the stent graft group, primary and secondary patency rates and freedom from stent graft infection at 3 years were 81%, 92%, and 100%. Conclusions UIAF is a rare complication associated with prior tumor resection, radiation, and indwelling ureteral stents. In select patients without enteric communication or abscess, iliac artery stent grafts are safe and effective treatment, and carry a low risk of recurrent massive hematuria or stent graft infection on early follow-up. Direct surgical repair carries a high risk of enterocutaneous fistula. PMID:22326578

  19. Nitrogen fixation method and apparatus

    DOEpatents

    Chen, H.L.

    1983-08-16

    A method and apparatus for achieving nitrogen fixation includes a volumetric electric discharge chamber. The volumetric discharge chamber provides an even distribution of an electron beam, and enables the chamber to be maintained at a controlled energy to pressure (E/p) ratio. An E/p ratio of from 5 to 15 kV/atm of O[sub 2]/cm promotes the formation of vibrationally excited N[sub 2]. Atomic oxygen interacts with vibrationally excited N[sub 2] at a much quicker rate than unexcited N[sub 2], greatly improving the rate at which NO is formed. 1 fig.

  20. Nitrogen fixation method and apparatus

    DOEpatents

    Chen, Hao-Lin (Walnut Creek, CA)

    1983-01-01

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

  1. 21 CFR 868.5770 - Tracheal tube fixation device.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...2011-04-01 2011-04-01 false Tracheal tube fixation device. 868.5770 Section...Therapeutic Devices § 868.5770 Tracheal tube fixation device. (a) Identification. A tracheal tube fixation device is a device used to...

  2. 21 CFR 868.5770 - Tracheal tube fixation device.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...2014-04-01 2014-04-01 false Tracheal tube fixation device. 868.5770 Section...Therapeutic Devices § 868.5770 Tracheal tube fixation device. (a) Identification. A tracheal tube fixation device is a device used to...

  3. 21 CFR 868.5770 - Tracheal tube fixation device.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...2012-04-01 2012-04-01 false Tracheal tube fixation device. 868.5770 Section...Therapeutic Devices § 868.5770 Tracheal tube fixation device. (a) Identification. A tracheal tube fixation device is a device used to...

  4. 21 CFR 868.5770 - Tracheal tube fixation device.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...2013-04-01 2013-04-01 false Tracheal tube fixation device. 868.5770 Section...Therapeutic Devices § 868.5770 Tracheal tube fixation device. (a) Identification. A tracheal tube fixation device is a device used to...

  5. 21 CFR 868.5770 - Tracheal tube fixation device.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...2010-04-01 2010-04-01 false Tracheal tube fixation device. 868.5770 Section...Therapeutic Devices § 868.5770 Tracheal tube fixation device. (a) Identification. A tracheal tube fixation device is a device used to...

  6. 21 CFR 888.3060 - Spinal intervertebral body fixation orthosis.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...Spinal intervertebral body fixation orthosis. 888.3060 Section 888.3060...Spinal intervertebral body fixation orthosis. (a) Identification. A spinal intervertebral body fixation orthosis is a device intended to...

  7. 21 CFR 888.3060 - Spinal intervertebral body fixation orthosis.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...Spinal intervertebral body fixation orthosis. 888.3060 Section 888.3060...Spinal intervertebral body fixation orthosis. (a) Identification. A spinal intervertebral body fixation orthosis is a device intended to...

  8. 21 CFR 888.3050 - Spinal interlaminal fixation orthosis.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...false Spinal interlaminal fixation orthosis. 888.3050 Section 888.3050...3050 Spinal interlaminal fixation orthosis. (a) Identification. A spinal interlaminal fixation orthosis is a device intended to...

  9. 21 CFR 888.3050 - Spinal interlaminal fixation orthosis.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...false Spinal interlaminal fixation orthosis. 888.3050 Section 888.3050...3050 Spinal interlaminal fixation orthosis. (a) Identification. A spinal interlaminal fixation orthosis is a device intended to...

  10. A Screw -Theoretic Framework for Musculoskeletal System Modeling and Analysis

    E-print Network

    Krovi, Venkat

    A Screw -Theoretic Framework for Musculoskeletal System Modeling and Analysis by Michael J. Del of tools for musculoskeletal system analysis, leveraging methodologies which have revolutionized can model, simulate, and analyze a redundant musculoskeletal system with (i) an adequate degree

  11. Screw anchors economically control pipeline buoyancy in muskeg

    SciTech Connect

    Robertson, R.; Curle, R. [NOVA Gas Transmission Ltd., Calgary, Alberta (Canada)

    1995-04-24

    To control buoyancy of large-diameter pipelines that cross such wet areas as muskeg swamps in Alberta Province, Canada, NOVA Gas Transmission Ltd., Calgary, for more than 6 years investigated alternatives to traditional concrete weights. The company`s research indicated that helical screw anchors offer cost-effective buoyancy control for natural-gas pipelines 20-in. OD and larger. Muskegs are organic soils with high water tables, low shear strengths, and low densities (specific gravity of 1.04). NOVA`s experience demonstrated practical and cost benefits of screw anchors to resist uplift forces. And among other benefits, substitution of screw anchors for concrete weights significantly reduced the number of heavy trucks that must be moved across the muskeg. The paper discusses buoyancy control, pipeline adaptation, pipe stresses and corrosion, pipeline construction and screw-anchor installation, economics and other benefits.

  12. Wet-gas compression in twin-screw multiphase pumps 

    E-print Network

    Chan, Evan

    2009-05-15

    encountered when operating under conditions with high gas volume fractions (GVF). Twin-screw multiphase pumps experience a severe decrease in efficiency when operating under wet-gas conditions, GVF over 95%. Field operations have revealed severe vibration...

  13. Wet-gas compression in twin-screw multiphase pumps

    E-print Network

    Chan, Evan

    2009-05-15

    Multiphase pumping with twin-screw pumps is a relatively new technology that has been proven successful in a variety of field applications. By using these pumps to add energy to the combined gas and liquid wellstream with minimal separation...

  14. Screw-matrix method in dynamics of multibody systems

    NASA Astrophysics Data System (ADS)

    Yanzhu, Liu

    1988-05-01

    In the present paper the concept of screw in classical mechanics is expressed in matrix form, in order to formulate the dynamical equations of the multibody systems. The mentioned method can retain the advantages of the screw theory and avoid the shortcomings of the dual number notation. Combining the screw-matrix method with the tool of graph theory in Roberson/Wittenberg formalism. We can expand the application of the screw theory to the general case of multibody systems. For a tree system, the dynamical equations for each j-th subsystem, composed of all the outboard bodies connected by j-th joint can be formulated without the constraint reaction forces in the joints. For a nontree system, the dynamical equations of subsystems and the kinematical consistency conditions of the joints can be derived using the loop matrix. The whole process of calculation is unified in matrix form. A three-segment manipulator is discussed as an example.

  15. Unilateral fixation for treatment of occipitocervical instability in children with congenital vertebral anomalies of the craniocervical junction.

    PubMed

    Mazur, Marcus D; Ravindra, Vijay M; Brockmeyer, Douglas L

    2015-04-01

    OBJECT Patients with occipitocervical (OC) instability from congenital vertebral anomalies (CVAs) of the craniocervical junction (CCJ) often have bony abnormalities that make instrumentation placement difficult. Within this patient population, some bilateral instrumentation constructs either fail or are not feasible, and a unilateral construct must be used. The authors describe the surgical management and outcomes of this disorder in patients in whom unilateral fixation constructs were used to treat OC instability. METHODS From a database of OC fusion procedures, the authors identified patients who underwent unilateral fixation for the management of OC instability. Patient characteristics, surgical details, and radiographic outcomes were reviewed. In each patient, CT scans were performed at least 4 months after surgery to evaluate for fusion. RESULTS Eight patients with CVAs of the CCJ underwent unilateral fixation for the treatment of OC instability. For 4 patients, the procedure occurred after a bilateral OC construct failed or infection forced hardware removal. For the remainder, it was the primary procedure. Two patients required reoperation for hardware revision and 1 developed nonunion requiring revision of the bone graft. Ultimately, 7 patients demonstrated osseous fusion on CT scans and 1 had a stable fibrous union. CONCLUSIONS These findings demonstrate that a unilateral OC fixation is effective for the treatment of OC instability in children with CVAs of the CCJ in whom bilateral screw placement fails or is not feasible. PMID:25828503

  16. Monitoring the reduced scattering coefficient of bone tissues on the trajectory of pedicle screw placement using near-infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Liu, Yangyang; Wang, Yuyan; Qian, Zhiyu; Zhao, Jinzhe; Cao, Xinzhi; Li, Weitao

    2014-11-01

    Pedicle screw (PS) fixation has been widely used for spine diseases. Scientists and clinicians employ several approaches to navigate PS during operation. We have demonstrated the feasibility of monitoring the reduced scattering coefficient (?s?) on the trajectory of PS using near-infrared spectroscopy (NIRS). To perform the in-vitro monitoring, an NIRS measurement system was introduced and the reduced scattering coefficients of different sites in porcine pedicle were accurately deduced from the spectrum. Moreover, the changes of the reduced scattering coefficient along the different paths were studied. The results show reduced scattering coefficients on different regions of bones can be significantly distinguished. Furthermore, monitoring experiments along different paths confirmed that a reduced scattering coefficient would change versus the depth of puncture in pedicles. Thus, the proposed monitoring system based on NIRS provides a potential for guiding PS during operation.

  17. Numerical Synthesis of Overconstrained Mechanisms Based on Screw Theory

    Microsoft Academic Search

    René Bartkowiak; Christoph Woernle

    \\u000a An approach for the synthesis of overconstrained single-loop mechanisms with helical joints using screw theory is presented.\\u000a By expressing higher-order derivatives of the screw axes with respect to the joint coordinates a local approximation of the\\u000a closure conditions is obtained. The approximation is used to define conditions for the finite mobility of overconstrained\\u000a mechanisms.

  18. Design of Limb for Parallel Mechanism Based on Screw Theory

    Microsoft Academic Search

    Zhigang Lai; Lixin Li; Ping' an Liu

    2010-01-01

    \\u000a Based on the reciprocal relationship of twist and wrench in screw theory, the mathematical model for limb of parallel manipulator\\u000a is established in this paper. According to the motion modes of mobile platform (translation or rotation), we concluded the\\u000a geometric conditions which the prismatic joint or revolute joint must meet with by analyzing the constraint screw on the platform,\\u000a which

  19. Finite displacements of points, planes, and lines via screw theory

    Microsoft Academic Search

    I. A. Parkin

    1995-01-01

    Geometrical elements, namely point, directed plane, and directed line, are here taken in isolation from any rigid body to which they may belong. The available finite screws are fully determined for a general finite displacement of each element. Each screw carries a quasi-pitch, or “quatch”, that reduces to the commonly-accepted pitch when a displacement becomes infinitesimal. Each element-displacement has its

  20. Crystal geometry of screw dislocation glide in tungsten nanocrystals

    NASA Astrophysics Data System (ADS)

    Sadanov, E. V.

    2015-02-01

    A zigzag pattern of low-temperature dislocation glide occurring in tungsten nanocrystals in the intersecting planes {110} and {211}, which belong to the <111> crystallographic zone, has been revealed using field ion microscopy. It has been shown that cores of 1/2[111] screw dislocations are undissociated within the limits of the resolution of the field ion microscope. It has been found experimentally that surface atoms are displaced into metastable positions in the region of the trace of screw dislocation motion.

  1. Eighth international congress on nitrogen fixation. Final program

    SciTech Connect

    Not Available

    1990-12-31

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

  2. [Acetabuloplasty by pedicled transfer of the iliac crest apophysis in the dog].

    PubMed

    Teot, L; Dussault, R G; Arnault, F; Blimke, B; Pfeil, J; Pous, J G

    1987-01-01

    Appositional incremental acetabuloplasty using a self growing iliac crest graft pedicle on its epipyseal vessels was performed in 54 puppies 3 months old. Remodeling an adaptation to the shape of the acetabulum is excellent in most of the cases, issuing into a spherical composite cavity. Persistance of a hyaline cartilage is noted until the end of the first years, but long term morphological transmission electronmicroscopy studies demonstrate a progressive transformation into fibrocartilage. This experimental study demonstrates the possibility to use remodeling and growth properties of a pedicled iliac crest, transplanted as an iland flap on the extraarticular acetabular roof. This new surgical technique can be proposed for the care of difficult dysplastic hips in children. PMID:3303718

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

    SciTech Connect

    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

    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.

  4. Backflow in twin-screw-type multiphase pump

    SciTech Connect

    Egashira, Kazuyuki; Shoda, Shinji; Tochikawa, Tetsuro [Japan National Oil Corp., Chiba (Japan); Furukawa, Akinori [Kyushu Univ. (Japan)

    1998-02-01

    The performance of a twin-screw-type multiphase pump was investigated from the viewpoints of backflow in a gap along the twin-screw shafts and of scaleup parameters. Although both the backflow and the scaleup parameters have been recognized as important factors in developing multiphase pumps, they have not yet been clarified. The twin-screw pump was equipped with pressure sensors, set in the multiphase-test facility, and experimented with under various conditions to clarify the relationship between backflow rates and factors such as differential pressure, gas-void fractions (GVF`s), and the rotation speed of the shaft. A physical model was proposed with the empirical relationship of pressure distribution along the screw, and was successfully associated with scaleup parameters, such as the geometrical data of the twin-screw pump. Then it was used successfully to simulate the backflow in twin-screw pumps on relatively broad experimental conditions, judging from the comparison between the model and the experimental data.

  5. Biochemical Approaches to Improved Nitrogen Fixation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Improving symbiotic nitrogen fixation by legumes has emerged again as an important topic on the world scene due to the energy crisis and lack of access to nitrogen fertilizer in developing countries. We have taken a biochemical genomics approach to improving symbiotic nitrogen fixation in legumes. L...

  6. Bioabsorbable fixation in orthopaedic surgery and traumatology

    Microsoft Academic Search

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

    2000-01-01

    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

  7. Whole Animal Perfusion Fixation for Rodents

    PubMed Central

    Gage, Gregory J.; Kipke, Daryl R.; Shain, William

    2012-01-01

    The goal of fixation is to rapidly and uniformly preserve tissue in a life-like state. While placing tissue directly in fixative works well for small pieces of tissue, larger specimens like the intact brain pose a problem for immersion fixation because the fixative does not reach all regions of the tissue at the same rate 5,7. Often, changes in response to hypoxia begin before the tissue can be preserved 12. The advantage of directly perfusing fixative through the circulatory system is that the chemical can quickly reach every corner of the organism using the natural vascular network. In order to utilize the circulatory system most effectively, care must be taken to match physiological pressures 3. It is important to note that physiological pressures are dependent on the species used. Techniques for perfusion fixation vary depending on the tissue to be fixed and how the tissue will be processed following fixation. In this video, we describe a low-cost, rapid, controlled and uniform fixation procedure using 4% paraformaldehyde perfused via the vascular system: through the heart of the rat to obtain the best possible preservation of the brain for immunohistochemistry. The main advantage of this technique (vs. gravity-fed systems) is that the circulatory system is utilized most effectively. PMID:22871843

  8. [Intrascleral haptic fixation of intraocular lenses].

    PubMed

    Scharioth, G B

    2014-03-01

    Scharioth's intrascleral haptic fixation in cases of no or insufficient capsular support has become a standardized and safe procedure for long-term fixation of intraocular lenses. The surgical technique is explained in detail. The postoperative results have demonstrated a low complication rate and a lack of contraindications for this technique. PMID:24549683

  9. Nitrogen fixation in Lake Mendota, Madison, Wisconsin

    Microsoft Academic Search

    MARGUERITE SHERMAN TORREY; G. F. LEE

    1976-01-01

    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

  10. Effects of Equol on Gene Expression in Female Cynomolgus Monkey Iliac Arteries

    PubMed Central

    Eyster, K; Appt, S.; Chalpe, A.; Register, T.; Clarkson, T.

    2014-01-01

    Background and Aims To examine effects of equol, the soy phytoestrogen metabolite, on gene expression in the monkey iliac artery. Methods and Results A high fat/high cholesterol diet was fed to eight ovariectomized cynomolgus monkeys for 6.5 years. After biopsy of the left iliac artery, the animals were randomized to two treatment groups for 8 months; the treatment groups were equol (23.7 mg/100 g diet, n=4) and vehicle (n=4). The right iliac artery was removed at necropsy. Gene expression in the iliac arteries in response to equol was determined by DNA microarray. Comparison of atherosclerotic lesions and plasma lipids at pre- versus post-equol treatment time points and in vehicle versus equol treatment groups did not identify any significant differences. Despite the lack of effect of equol on these parameters, 59 genes were down-regulated and 279 were up-regulated in response to equol. Comparison of these data to previous work identified 10 genes regulated in opposite directions by equol compared to presence of atherosclerosis plaque (Menopause 2011;18:1087–1095) and 55 genes differentially expressed in the same direction in response to both equol and estradiol (Eyster et al., Menopause 2013; in press). Conclusions Similar responses of genes to both equol and estradiol may reflect the extent to which equol serves as a natural selective estrogen receptor modulator in the arteries. Opposite responses of 10 genes to equol versus the presence of atherosclerosis implicates those genes in the potential protective effects of equol in arteries. PMID:24525253

  11. External iliac artery occlusion in a paediatric patient following handlebar trauma

    PubMed Central

    Singla, Animesh A.; McPherson, Danielle; Singla, Apresh A; Cross, Jane; Leslie, Anthony

    2015-01-01

    Arterial occlusion following blunt trauma is an uncommon occurrence. We report an unusual case of delayed external iliac artery occlusion in a young male following blunt abdominal injury. He was successfully treated with thromboendarterectomy and saphenous vein patch repair. There have only been a handful of documented cases occurring in the paediatric population. All patients presenting with groin injury from this mechanism should be carefully investigated and monitored for risk of vascular injury. PMID:25733671

  12. Arteriovenous fistula complicating iliac artery pseudo aneurysm: diagnosis by CT angiography.

    PubMed

    Huawei, L; Bei, D; Huan, Z; Zilai, P; Aorong, T; Kemin, C

    2002-01-01

    Fistula formation to the inferior vena cava is a rare complication of aortic aneurysm which is often misdiagnosed clinically. In one hundred of reported arteriocaval fistulae, none was originating from the right common iliac artery. We report a case of ileo-caval fistula due to a iatrogenic pseudoaneurysm. High resolution 3D imaging using breath-hold CT angiography is highly specific in identifying the location, extent of the aortocaval fistula as well as the neighbouring anatomic structures. PMID:12083621

  13. Rupture of external iliac artery during microscopic lumbar disc surgery -A case report-

    PubMed Central

    Yi, Youngjae; Kim, Yeo-Jung; Mok, Jeong-Min; Kim, Hyun Soo

    2010-01-01

    Iatrogenic vascular injury during lumbar disc surgery is a rare but serious complication. This paper reports a patient who sustained an injury to the iliac artery while undergoing intervertebral disc surgery at the lumbar region. He suffered from massive bleeding and shock. An urgent laparatomy was performed under cardiopulmonary bypass, and the vascular injuries were repaired successfully. This case shows that a rapid diagnosis and immediate intervention can result in a favorable outcome. PMID:21286434

  14. Carbon consequences of a nitrogen fixation feedback

    NASA Astrophysics Data System (ADS)

    Levy, J.; Medvigy, D.; Hedin, L.; Batterman, S. A.; Xu, X.

    2014-12-01

    Tropical forests constitute a globally important carbon sink but it is unclear how their productivity and carbon storage depend upon nutrients. There is increasing evidence of an ecosystem carbon-nitrogen feedback mechanism, by which symbiotic dinitrogen (N2) fixing trees can provide the nitrogen needed to maintain high rates of forest biomass growth following disturbance. Field-based evaluation of this feedback is difficult, however, as the expected effects on forest carbon stores would emerge very slowly, over decades to centuries of ecological succession. Moreover, there is no known way to inhibit the fixation process in trees without causing structural damage and perturbing the carbon cycle. Coupled land biogeochemistry-vegetation models offer a way to examine the role of feedbacks that unfold over successional time. However, it is unclear how the process of nitrogen fixation ought to be represented in models so that they can capture the potential effect of fixation on the long-term forest carbon sink. In this study, we integrate a newly developed individual-based model with field observations across Panamanian tropical forests to address: 1) whether N2 fixation enhances tropical forest carbon storage; 2) whether models must resolve fixation at the individual plant level to capture the fixation feedback; and 3) whether fixation interacts with plant functional types (i.e., early, mid, vs. late succession) to determine the carbon sink? We find that forests that have fixation recover faster and store more carbon in the long term than forests without fixation. This results in 94-118% more plant carbon stored by 30 years and an additional 13 tons C ha -1 stored over 300 years when compared to forests without fixation. Additionally, resolving fixation at the individual plant level is necessary to capture nitrogen dynamics over time and is particularly important for modeling succession and disturbance events. Finally, we find that the overall fixation effect is the result of two processes, the direct effect of the fixation on carbon accumulation and the indirect effect of fixation on the successional plant functional type sequence.

  15. Arterial wall lymphangiogenesis is increased in the human iliac atherosclerotic arteries: involvement of CCR7 receptor.

    PubMed

    Grzegorek, Irmina; Drozdz, Katarzyna; Chmielewska, Magdalena; Gomulkiewicz, Agnieszka; Jablonska, Karolina; Piotrowska, Aleksandra; Karczewski, Maciej; Janczak, Dariusz; Podhorska-Okolow, Marzena; Dziegiel, Piotr; Szuba, Andrzej

    2014-12-01

    Twenty-six iliac artery segments were divided in two groups: atherosclerotic (A) and nonatherosclerotic (NA). Expression of LYVE-1, VEGF-C, VEGF-D, and CCR7 receptor were studied with immunohistochemistry (IHC) and Western blot (WB). IHC was performed on 26 samples of iliac arteries obtained from deceased 19 organ donors. The samples were divided into an atherosclerotic group (A) [subjects with history of cardiovascular disease (hypertension, ischemic heart disease) or/and diabetes] (n=16), and a nonatherosclerotic group (NA) [subjects without any known cardiovascular diseases or cardiovascular risk factors] (n=10). WB was performed on 19 iliac artery segments obtained from two groups, based on clinical data: an atherosclerotic group (A) [patients with atherosclerosis, who underwent surgery for lower limb ischemia] (n=10), and a nonatherosclerotic group (NA) [deceased organ donors without cardiovascular diseases/risk factors (n=9)]. Expression of LYVE-1, VEGF-C, VEGF-D, and CCR-7 was increased in atherosclerotic arteries. Positive correlations between LYVE-1 and VEGF-C expression in the intima-media complex assessed by IHC: (r=0.54; p=0.005) and WB: (r=0.47; p=0.005) were found. Positive correlations between expression of CCR-7 and other markers were observed. Lymphangiogenesis is enhanced within the atherosclerotic arterial wall. Our results confirm lymphatic system activation with increased lymphangiogenesis and lymphocyte/macrophage trafficking in atherosclerosis. PMID:25318003

  16. Embolization of the Internal Iliac Artery: Cost-Effectiveness of Two Different Techniques

    SciTech Connect

    Pellerin, Olivier, E-mail: olivier.pellerin@egp.aphp.f [Georges Pompidou European Hospital, Cardiovascular Radiology Department (France); Caruba, Thibaud [Hopital Europeen Georges Pompidou, Pharmacy (France); Kandounakis, Yanis; Novelli, Luigi [Georges Pompidou European Hospital, Cardiovascular Radiology Department (France); Pineau, Judith; Prognon, Patrice [Hopital Europeen Georges Pompidou, Pharmacy (France); Sapoval, Marc [Georges Pompidou European Hospital, Cardiovascular Radiology Department (France)

    2008-11-15

    The purpose of this study was to compare the cost-effectiveness of coils versus the Amplatzer Vascular Plug (AVP) for occlusion of the internal iliac artery (IAA). Between 2002 and January 2006, 13 patients (mean age 73 {+-} 13 years) were referred for stent-grafting of abdominal aortic aneurysm (n = 6); type I distal endoleak (n = 3), isolated iliac aneurysm (n = 3), or rupture of a common iliac aneurysm (n = 1). In all patients, extension of the stent-graft was needed because the distal neck was absent. Two different techniques were used to occlude the IIA: AVP in seven patients (group A) and coil embolization in six patients (group C). Immediate results and direct material costs were assessed retrospectively. Immediate success was achieved in all patients, and simultaneous stent-grafting was successfully performed in two of six patients in group C versus five of seven patients in group A. In all group A patients, a single AVP was sufficient to achieve occlusion of the IIA, accounting for a mean cost of 485 Euro , whereas in group C patients, an average of 7 {+-} 3 coils were used, accounting for a mean cost of 1,745 Euro . Mean average cost savings using the AVP was 1,239 Euro . When IIA occlusion is needed, the AVP allows a single-step procedure at significant cost savings.

  17. The Volume Behavior of Autogenous Iliac Bone Grafts After Sinus Floor Elevation: A Clinical Pilot Study.

    PubMed

    Gerressen, Marcus; Riediger, Dieter; Hilgers, Ralf-Dieter; Hölzle, Frank; Noroozi, Nelson; Ghassemi, Alireza

    2015-06-01

    Iliac crest is still regarded as one of the most viable source of autogenous graft materials for extensive sinus floor elevation. Three-dimensional resorption behavior has to be taken into account in anticipation of the subsequent insertion of dental implants. We performed 3-dimensional volume measurements of the inserted bone transplants in 11 patients (6 women and 5 men; mean age = 2.3 years) who underwent bilateral sinus floor elevation with autogenous iliac crest grafts. In order to determine the respective bone graft volumes, cone-beam computerized tomography studies of the maxillary sinuses were carried out directly after the operation (T0), as well as 3 months (T1) and 6 months (T2) postoperatively. The acquired DICOM (Digital Imaging and Communications in Medicine) data sets were evaluated using suitable analysis software. We evaluated statistical significance of graft volumes changes using a linear mixed model with the grouping factors for time, age, side, and sex with a significance level of P = .05. 38.9% of the initial bone graft volume, which amounted to 4.2 cm(3), was resorbed until T1. At T2, the average volume again decreased significantly by 18.9 % to finally reach 1.8 cm(3). The results show neither age nor side dependency and apply equally to both sexes. Without functional load, iliac bone grafts feature low-volume stability in sinus-augmentation surgery. Further clinical and animal studies should be done to detect the optimal timing for implant placement. PMID:24303797

  18. Comparison between Platelet-Rich Plasma and Autologous Iliac Grafts for Tibial Osteotomy

    PubMed Central

    D’Elia, Caio Oliveira; de Rezende, Márcia Uchôa; Bitar, Alexandre Carneiro; Tatsui, Nelson; Pécora, José Ricardo; Hernandez, Arnaldo José; Camanho, Gilberto Luis

    2010-01-01

    Objective: Platelet-rich plasma (PRP) has the capacity to improve the bone-healing process. The aim of this pilot study was to investigate the occurrence of bone healing and the time taken to achieve this in patients submitted to medial opening wedge high tibial osteotomy (MOWHTO), comparing platelet-rich plasma with bone marrow aspirate to autologous iliac graft. Design: Twenty-five patients who underwent tibial osteotomy were randomly divided into 2 groups: a control group, which received autologous iliac grafts (14 patients), and a study group, which received a compound of PRP and bone marrow aspirate (11 patients). Results: The bone-healing rates achieved were 100% in the control group and 91% in the study group. There was no difference in the time taken to achieve bone healing between the groups. Conclusions: The use of a combination of PRP and bone marrow aspirate, as a bone substitute, did not demonstrate any advantage over the use of an autologous iliac graft in MOWHTO.

  19. Laser angioplasty with lensed fibers and a holmium:YAG laser in iliac artery occlusions

    NASA Astrophysics Data System (ADS)

    White, Christopher J.; Ramee, Stephen R.; Mesa, Juan E.; Collins, Tyrone J.; Kotmel, Robert; Godfrey, Maureen A.

    1991-05-01

    Holmium-YAG (2.1 (mu) ) laser recanalization was attempted in 10 totally occluded miniature swine iliac arteries using a lensed fiber delivery system. The iliac artery occlusions were created in a Yucatan miniature swine model of atherosclerosis by means of a high cholesterol diet and balloon endothelial denudation. In order to increase the spot size, a spherical silica lens was attached to the distal end of a 300 micrometers core diameter silica optical fiber. The holmium-YAG laser was operated in the free-running mode with 250 microsecond(s) ec pulses at 4 Hz. The energy delivered was 225 mJ per pulse for the 1.0 mm lensed fiber and 200 mJ per pulse for the 1.3 mm lensed fiber. Laser energy was delivered in 2 to 5 second bursts. Successful recanalization was achieved in all 10 arteries attempted without perforation of the arterial wall. The average length of the occlusions was 5.0 +/- 1.8 cm. Following successful laser recanalization significant stenoses (>50%) remained in all of the arteries as judged by angiography. In conclusion, the lensed fibers coupled to the pulsed holmium-YAG laser were safe and effective in recanalizing these difficult lesions in relatively straight iliac arteries. There is potential clinical utility for this system as an adjunct to balloon angioplasty in patients with lesions which are unable to be crossed with guidewires.

  20. Combination of microvascular medial femoral condyle and iliac crest flap for hemi-midface reconstruction.

    PubMed

    Brandtner, C; Hachleitner, J; Buerger, H; Gaggl, A

    2015-06-01

    In midface defects including the orbit (Brown class III and IV), no single flap can provide adequate reconstruction. In this technical note, the combination of vascularized iliac crest flap and vascularized medial femoral condyle flap (MFC) is described. The vascularized iliac crest flap is reported to be the gold standard for maxilla reconstruction. There is, however, no consensus on the best method for orbital and nasal wall reconstruction. The MFC flap can be harvested as a thin corticoperiosteal flap or as an osteomyocutaneous flap. Due to the periosteal blood supply, this flap can be customized for an individual defect of the upper hemi-midface. It is therefore of great benefit in orbital and nasal wall reconstruction. By combining the deep circumflex iliac artery (DCIA) bone flap and the MFC flap, the best standard reconstruction technique of the hemi-maxilla can be combined with a new anatomical precise microvascular reconstruction technique of the orbit. A nearly symmetric midface appearance can be achieved. PMID:25835757

  1. Iliac arteriovenous fistula due to spinal disk surgery. Causes severe hemodynamic repercussion with pulmonary hypertension.

    PubMed Central

    Machado-Atías, I; Fornés, O; González-Bello, R; Machado-Hernández, I

    1993-01-01

    We present a case of a 46-year-old man with a pulsatile mass in the left inferior abdominal quadrant that irradiated a continuous murmur extending to the left lumbar region. Despite an 8-year history of cardiomegaly, he appeared to be asymptomatic except for the mass and could recollect no traumatic injury or surgery that might have caused it. Near the vertebral column, we found a small scar, the result of spinal disk surgery 11 years before. Following chest radiography and electrocardiography, we located the suspected arteriovenous fistula by selective angiography of the aorta and its branches: a communication of the left iliac artery with the left iliac vein had resulted in a very large left-to-right shunt and a severely dilated inferior vena cava. We then divided and isolated the arterial segment containing the fistula, but left this segment in continuity with the left iliac vein by over-sewing both ends. To avoid injury to surrounding structures, dissection was limited to the area of maximal thrill. Hemodynamic improvement was immediate, and the postoperative course was uneventful. At the present time, almost 3 years postoperatively, the patient is asymptomatic. Images PMID:8508067

  2. [A comparative analysis of results of operative treatment of olecranon fracture utilizing Gruca screw and Weber girth].

    PubMed

    Bednarenko, Marcin; Kotela, Ireneusz; Bo?tu?, Witold; Jakubowski, Lukasz

    2006-01-01

    An injury to the elbow constitutes 3.5% of all injuries of the movement system and of these 31% concern olecranon fractures. In the majority of cases they are intra-articular fractures, unstable because of the action of the triceps muscle of the arm. Most of the patients require operative treatment. In the years 1984-2001 in the Traumatic and Orthopedic Ward we treated 49 patients with olecranon fractures. In 30 patient we utilized Gruca screw and in 10 of them Weber girth. 3 fractures were fixed with a wire loop and the remaining 6 did not require operative but only conservative treatment. The results were estimated according to the Hofbauer's scale in 37 patients among whom 27 were treated making a fixation with a Gruca screw and 10 by using Weber girth. Altogether, we achieved good and satisfactory results in 33 cases and bad results in 4 cases. Based on these results there is no evident superiority of one method over the other. The study emphasizes the importance of the correct qualification to either therapeutic method. PMID:17784540

  3. The prognostic value of tip-to-apex distance (TAD index) in intertrochanteric fractures fixed by dynamic hip screw

    PubMed Central

    Sedighi, Ali; Sales, Jafar Ganjpour; Alavi, Sahar

    2012-01-01

    Intertrochanteric fractures (ITFs) are the most common type of fractures requiring surgical intervention. They also have the highest surgical mortality among orthopedic operations. Among the many different techniques used for fixation of this type of fracture, use of the Dynamic Hip Screw (DHS) has gained wide acceptance. This current study was designed to assess positive predictive value of tip-to-apex distance (TAD) index in the prognosis of patients treated with DHS. The study was designed according to a descriptive-analytic protocol, made up of 100 cases of ITFs caused by falling, treated in the Shohada Orthopedic Center, Tabriz, Iran. All patients underwent lateral and antero-posterior hip X-ray to measure TAD index. The cohort was followed for three months after DHS placement. Of a total of 100 cases (53 male, 47 female) with a mean age of 76.7 years (range 29–100 years), 43% had grade 4, 29% grade 3, 21% grade 5, 5% grade 2 and 2% grade 6 osteoporosis. The screw position was postero-inferior in 57%, central in 40% and superior in 3% of patients. Minimum and maximum TAD index were 20 and 28 mm, respectively. Mean TAD was 23.5 mm. There were no post-operative complications in 84% of cases. Screw failure was the most common complication in the remaining 16% of patients. The study shows a statistically significant correlation between TAD index and cut-off rate in patients with intertrochanteric fractures of femoral bone treated by DHS. This validates the use of TAD index in determining the prognosis of patients treated by DHS. PMID:23589760

  4. A computational study on the effect of fracture intrusion distance in three- and four-part trochanteric fractures treated with Gamma nail and sliding hip screw.

    PubMed

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

    2014-01-01

    Using finite element analysis, the behaviors of the Gamma nail and the sliding hip screw (SHS) were compared in an osteoporotic bone model for the fixation of three- and four-part trochanteric fractures (31-A2 in the AO classification, types IV and V in Evans' classification). The size of the medial fragment was varied based on clinical data, and the case of a fractured greater trochanter was also considered. Our results showed that for Evans' type V stabilized with a Gamma nail and for Evans' types IV and V with the SHS, cancellous bone around the lag screw is susceptible to yielding, thus indicating a risk of cut-out. The volume of bone susceptible to yielding increases with an increase in size of the medial fragment. Conversely, Evans' type IV with a Gamma nail was not predicted to cut out. Our findings suggest that future clinical trials investigating fixation of unstable proximal fractures should include the size of the medial fragment and the integrity of the greater trochanter as covariables and be powered to evaluate whether intramedullary devices are superior to SHSs for Evans' type IV fractures and inferior/equivalent for type V. PMID:24123306

  5. Dinitrogen fixation in aphotic oxygenated marine environments

    PubMed Central

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

    2013-01-01

    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

  6. Methodological Underestimation of Oceanic Nitrogen Fixation Rates

    PubMed Central

    Mohr, Wiebke; Großkopf, Tobias; Wallace, Douglas W. R.; LaRoche, Julie

    2010-01-01

    The two commonly applied methods to assess dinitrogen (N2) fixation rates are the 15N2-tracer addition and the acetylene reduction assay (ARA). Discrepancies between the two methods as well as inconsistencies between N2 fixation rates and biomass/growth rates in culture experiments have been attributed to variable excretion of recently fixed N2. Here we demonstrate that the 15N2-tracer addition method underestimates N2 fixation rates significantly when the 15N2 tracer is introduced as a gas bubble. The injected 15N2 gas bubble does not attain equilibrium with the surrounding water leading to a 15N2 concentration lower than assumed by the method used to calculate 15N2-fixation rates. The resulting magnitude of underestimation varies with the incubation time, to a lesser extent on the amount of injected gas and is sensitive to the timing of the bubble injection relative to diel N2 fixation patterns. Here, we propose and test a modified 15N2 tracer method based on the addition of 15N2-enriched seawater that provides an instantaneous, constant enrichment and allows more accurate calculation of N2 fixation rates for both field and laboratory studies. We hypothesise that application of N2 fixation measurements using this modified method will significantly reduce the apparent imbalances in the oceanic fixed-nitrogen budget. PMID:20838446

  7. A comparison study between periosteum and resorbable collagen membrane on iliac block bone graft resorption in the rabbit calvarium

    PubMed Central

    2014-01-01

    Background To compare the different resorption patterns between resorbable membrane barrier and periosteum after iliac block bone grafting radiographically and histologically. Methods Eighteen mature male rabbits weighing from 2.0 to 2.5 kg were used. The recipient site was the rabbit skull, and autogenous iliac bone was used as the grafting material. The harvested iliac block bones were divided in the following groups: autogenous iliac block bone with preservation of the periosteum (the periosteum group), autogenous iliac block bone covered with a resorbable collagen membrane (Biomesh®, Samyang Co, Korea) after removing the periosteum (the collagen membrane group), and autogenous iliac block bones with removal of the periosteum (the control group). In each experimental group, periosteum or resorbable collagen membrane of the donor site was fixed directed to the periosteum of the recipient site. The specimens were examined macroscopically, radiographically, histologically, and histomorphometrically at every 2, 4, and 8 weeks. Results All groups presented excellent bone graft healing state without inflammation, dehiscence, or displacement. The radiolucency increased from mild to moderate in all groups over the experiment. The mean thickness of the upper end of the cortical iliac bone graft was statistically significantly different between the control group and the periosteum group, between the four-week and eight-week control group, and between the four- week and eight-week periosteum group (p?&?0.05). Conclusion This study suggests that both the periosteum and the resorbable collagen membrane may help to prevent soft tissue infiltration into the bone graft and to reduce bone graft resorption compared to block graft alone. PMID:24886656

  8. The biomechanical analysis of three plating fixation systems for periprosthetic femoral fracture near the tip of a total hip arthroplasty

    PubMed Central

    2010-01-01

    Background A variety of techniques are available for fixation of femoral shaft fractures following total hip arthroplasty. The optimal surgical repair method still remains a point of controversy in the literature. However, few studies have quantified the performance of such repair constructs. This study biomechanically examined 3 different screw-plate and cable-plate systems for fixation of periprosthetic femoral fractures near the tip of a total hip arthroplasty. Methods Twelve pairs of human cadaveric femurs were utilized. Each left femur was prepared for the cemented insertion of the femoral component of a total hip implant. Femoral fractures were created in the femurs and subsequently repaired with Construct A (Zimmer Cable Ready System), Construct B (AO Cable-Plate System), or Construct C (Dall-Miles Cable Grip System). Right femora served as matched intact controls. Axial, torsional, and four-point bending tests were performed to obtain stiffness values. Results All repair systems showed 3.08 to 5.33 times greater axial stiffness over intact control specimens. Four-point normalized bending (0.69 to 0.85) and normalized torsional (0.55 to 0.69) stiffnesses were lower than intact controls for most comparisons. Screw-plates provided either greater or equal stiffness compared to cable-plates in almost all cases. There were no statistical differences between plating systems A, B, or C when compared to each other (p > 0.05). Conclusions Screw-plate systems provide more optimal mechanical stability than cable-plate systems for periprosthetic femur fractures near the tip of a total hip arthroplasty. PMID:20653962

  9. Femoral supracondylar focal dome osteotomy with plate fixation for acute correction of frontal plane knee deformity.

    PubMed

    El Ghazaly, Sherif Ahmed; El-Moatasem, El-Hussein Mohamed

    2015-04-01

    Focal dome osteotomy (FDO) allows deformity correction without secondary translational deformity. The purpose of this study was to evaluate the degree of correction and knee functional outcome after correction of frontal knee deformity using femoral supracondylar FDO fixed with plate and screws. A prospective study included 12 consecutive cases of femoral frontal plane deformity that underwent correction using supracondylar focal osteotomy fixed by plate and screws. Average age was 27 years, while mean follow-up was 2.1 years. Functional assessment was done using the Hospital for Special Surgery (HSS) knee score. The HSS knee score improved from 85 to 96.8 points. Desired correction was achieved in all cases. Postoperative mechanical axis analysis on long film and scanogram showed no secondary deformity. The overall postoperative mechanical axis was at 3.2 mm medially (range 2-5 mm). Autogenous bone graft was not used in any case, and uneventful osteotomy union was achieved at a mean of 13.8 weeks. Minor complications were encountered in two cases. There were no implant failures or reoperations. Supracondylar FDO of the femur with plate fixation is a reproducible technique that can produce full correction of distal femoral frontal plane deformity, while avoiding creating a secondary deformity. Knee function was improved with good patient satisfaction. PMID:25861038

  10. In vitro biomechanical comparison of six different fixation methods following 5-mm sagittal split advancement osteotomies.

    PubMed

    Oguz, Y; Watanabe, E R; Reis, J M; Spin-Neto, R; Gabrielli, M A; Pereira-Filho, V A

    2015-08-01

    The sagittal split ramus osteotomy (SSRO) is a surgical technique used widely to treat many congenital and acquired mandibular discrepancies. Stabilization of the osteotomy site and the potential for skeletal relapse after the procedure are still major problems. The aim of this study was to compare the mechanical stability of six methods of rigid fixation in SSRO using a biomechanical test model. Sixty polyurethane replicas of human hemimandibles were divided into six groups. In group I, the osteotomies were fixed with two four-hole titanium miniplates; in group II, with one four-hole miniplate; in group III, with one four-hole miniplate+a bicortical screw; in group IV, with a grid miniplate; in group V, with a four-hole locking miniplate; and in group VI, with a six-hole miniplate. A linear load in the premolar region was applied to the hemimandibles. The resistance forces (N) needed to displace the distal segment by 1, 3, and 5mm were recorded and the data transmitted from the load cell to a computer. One-way analysis of variance with Tukey's post hoc test was performed to compare the means between groups. For the three displacement conditions, there was a strong tendency for the 2.0-mm plate+screw and the grid plate to have higher values. PMID:25840861

  11. Locking screw apparatus and method for underwater remote replacement

    SciTech Connect

    Balog, L.J.

    1987-07-28

    A method is described for locking in place a screw which secures together first and second structures in the internal region of a nuclear reactor core. The first structure has a screw bore with a counterbore portion formed in an outer surface. The method comprises the steps of: forming a lateral recess in the counterbore portion and spaced from the outer surface, providing an elongated screw having an enlarged shoulder flange and an angular drive head with a lateral width substantially less than that of the counterbore portion, disposing the screw through the screw bore in threaded engagement with the second structure and with the shoulder rotatably seated in the counterbore portion. This provides a locking member having an angular opening and disposing it in the counterbore portion against the flange with the drive head received in the opening for engagement with the locking member to prevent rotation. This deforms a portion of the locking member into the recess for engagement to prevent movement of the locking member with respect to the first structure.

  12. Nitrogen fixation on Arctic glaciers, Svalbard

    NASA Astrophysics Data System (ADS)

    Telling, Jon; Anesio, Alexandre M.; Tranter, Martyn; Irvine-Fynn, Tristram; Hodson, Andy; Butler, Catriona; Wadham, Jemma

    2011-09-01

    Glacier surfaces contain a wide diversity of microorganisms and can host a range of microbial activities. However, microbial nutrient cycling on glaciers is poorly understood. This study is the first to document nitrogen fixation (nitrogenase activity) on glaciers and demonstrate its importance in supporting microbial growth. Rates of nitrogen fixation (nitrogenase activity) in cryoconite holes on three valley glaciers in Svalbard ranged from <2.0 to 99.9 ?mol ethylene m-2 d-1 with rates inversely correlated to concentrations of available inorganic nitrogen. Annual inputs of nitrogen by nitrogen fixation on a glacier catchment scale are more than 2 orders of magnitude lower than the combined nitrogen inputs from snowmelt and rain. However, nitrogen fixation can be important for supporting microbial growth on the glaciers during the middle to late melt season after the snowline has retreated upslope.

  13. Methanotrophy Induces Nitrogen Fixation in Boreal Mosses

    NASA Astrophysics Data System (ADS)

    Tiirola, M. A.

    2014-12-01

    Many methanotrophic bacterial groups fix nitrogen in laboratory conditions. Furthermore, nitrogen (N) is a limiting nutrient in many environments where methane concentrations are highest. Despite these facts, methane-induced N fixation has previously been overlooked, possibly due to methodological problems. To study the possible link between methanotrophy and diazotrophy in terrestrial and aquatic habitats, we measured the co-occurrence of these two processes in boreal forest, peatland and stream mosses using a stable isotope labeling approach (15 N2 and 13 CH4 double labeling) and sequencing of the nifH gene marker. N fixation associated with forest mosses was dependent on the annual N deposition, whereas methane stimulate N fixation neither in high (>3 kg N ha -1 yr -1) nor low deposition areas, which was in accordance with the nifH gene sequencing showing that forest mosses (Pleurozium schreberi and Hylocomium splendens ) carried mainly cyanobacterial N fixers. On the other extreme, in stream mosses (Fontinalis sp.) methane was actively oxidized throughout the year, whereas N fixation showed seasonal fluctuation. The co-occurrence of the two processes in single cell level was proven by co-localizing both N and methane-carbon fixation with the secondary ion mass spectrometry (SIMS) approach. Methanotrophy and diazotrophy was also studied in peatlands of different primary successional stages in the land-uplift coast of Bothnian Bay, in the Siikajoki chronosequence, where N accumulation rates in peat profiles indicate significant N fixation. Based on experimental evidence it was counted that methane-induced N fixation explained over one-third of the new N input in the younger peatland successional stages, where the highest N fixation rates and highest methane oxidation activities co-occurred in the water-submerged Sphagnum moss vegetation. The linkage between methanotrophic carbon cycling and N fixation may therefore constitute an important mechanism in the rapid accumulation of N during the primary succession of peatlands. It is still an open issue whether methanotrophy induces N fixation directly or by enhancing phototrophic or heterotrophic N fixation.

  14. Dynamics of free, straight dislocation pairs. I. Screw dislocations

    SciTech Connect

    Eykholt, R.; Trugman, S.A.; Srolovitz, D.J.

    1989-06-01

    Analytic expressions are derived for the motion of a pair of interacting, straight, parallel (or antiparallel) screw dislocations in an applied stress field. Analysis of the equations of motion of the dislocations shows that, under most circumstances, the velocity of a dislocation is proportional to the driving force (i.e., the motion is overdamped), and, in this limit, the results are exact. However, when the two dislocations are very close together, inertial terms begin to play a role, and the resultant ''finite-mass'' corrections are treated perturbatively. For the case of antiparallel screw dislocations, a capture cross section exists and is given by the product of the shear modulus and the Burgers vector over the applied stress. Based on these results, a simple statistical analysis of the motion of a large number of screw dislocations is presented.

  15. CMM probe compensation methods for measuring complex screw surface

    NASA Astrophysics Data System (ADS)

    Zhao, Qiancheng; Yang, Tianlong; Yin, Xiyun

    2013-01-01

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

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

    PubMed

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

    2011-04-25

    Archimedes micro-screws have been fabricated by three-dimensional two-photon polymerization using a Nd:YAG Q-switched microchip laser at 532nm. Due to their small sizes they can be easily manipulated, and made to rotate using low power optical tweezers. Rotation rates up to 40 Hz are obtained with a laser power of 200 mW, i.e. 0.2 Hz/mW. A photo-driven micropump action in a microfluidic channel is demonstrated with a non-optimized flow rate of 6 pL/min. The optofluidic properties of such type of Archimedes micro-screws are quantitatively described by the conservation of momentum that occurs when the laser photons are reflected on the helical micro-screw surface. PMID:21643076

  17. Tunable helium bubble superlattice ordered by screw dislocation network

    NASA Astrophysics Data System (ADS)

    di, Zengfeng; Bai, Xian-Ming; Wei, Qiangmin; Won, Jonghan; Hoagland, Richard G.; Wang, Yongqiang; Misra, Amit; Uberuaga, Blas P.; Nastasi, Michael

    2011-08-01

    Helium bubble nucleation at low-angle twist boundaries in gold has been investigated. It is found that the helium bubbles preferentially nucleate at screw dislocation nodal points and result in helium bubble superlattice formation, which is completely isomorphic with the screw dislocation network along the twist-grain boundary. Molecular statics calculations reveal that defect formation/solution energies along the screw dislocations, especially at the nodal points, are lower than their bulk counterparts. It is believed that this driving force is responsible for the helium bubble superlattice formation. Our study suggests that grain boundary engineering via adjustable twist angles in parallel boundaries to form tunable 3D bubble superlattices could afford a very promising approach for design of radiation tolerant materials.

  18. Special Aspects of Nitrogen Fixation by Blue-Green Algae

    Microsoft Academic Search

    Rosalie M. Cox; P. Fay

    1969-01-01

    When carbon dioxide fixation was over 90% inhibited by CMU, nitrogen fixation remained unaffected in nitrogen-starved cells of Anabaena cylindrica. In normal cells under the same conditions nitrogen fixation was about 50% inhibited by CMU. These data suggest, first, that nitrogen fixation in this organism is independent of reducing potential generated by non-cyclic photo-electron transport and, secondly, that nitrogen fixation

  19. Pin loosening in external skeletal fixation 

    E-print Network

    Vittal, Bamini

    1993-01-01

    OF TABLES Page TABLE 1 Table showing the problems and complications of external fixations. TABLE 2 Table showing the experimental design. . . 22 TABLE 3 Table showing the number of cadaver dogs tested and the twist out rates and the pull out rates... included a chapter outlining technical details pertinent to the prevention of unnecessary complications associated with the use of external fixation. While their discussion of the strategies for avoiding complications was extensive, Shaar and Document...

  20. Biological nitrogen fixation: A scientific perspective

    Microsoft Academic Search

    R. H. Burris

    1988-01-01

    The discoveries of Hellriegel and Wilfarth ended the period of controversy about the existence of biological N2 fixation and launched a period featuring the agronomic application of the inoculation of legumes. Serious studies of the\\u000a biochemistry of N2 fixation started in the late 1920's, and defined some of the basic properties of the N2-fixing system. Application of15N as a tracer

  1. Stability of external skeletal fixation clamps

    E-print Network

    Sandel, Mark Eugene

    1995-01-01

    STABILITY OF EXTERNAL SKELETAL FIXATION CLAMPS A Thesis by MARK EUGENE SANDEL Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE May 1995 Major... Eugene Sandel, B. S. , Texas A%M University Chair of Advisory Committee: Dr. William A. Hyman External skeletal fixation is commonly used for treatment of many orthopedic diseases and injuries in both human and animal patients. It is mainly used...

  2. Simple technique for removing broken pedicular screw with plain and serviceable screwdriver

    Microsoft Academic Search

    Ahmet H. Kaya; Adnan Dagcinar; Fahrettin Celik; Alparslan Senel

    2008-01-01

    Removing the broken pedicular screw after spinal hardware failure is usually problematic. A specially designed simple screwdriver\\u000a and easy removal technique of broken pedicular screw with this screwdriver are described in this article.

  3. 29 CFR 1926.305 - Jacks-lever and ratchet, screw, and hydraulic.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

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

  4. Iliac crest allograft glenoid reconstruction for recurrent anterior shoulder instability in athletes: Surgical technique and results

    PubMed Central

    Mascarenhas, Randy; Raleigh, Eden; McRae, Sheila; Leiter, Jeff; Saltzman, Bryan; MacDonald, Peter B.

    2014-01-01

    Performing a labral repair alone in patients with recurrent anterior instability and a large glenoid defect has led to poor outcomes. We present a technique involving the use of the iliac crest allograft inserted into the glenoid defect in athletes with recurrent anterior shoulder instability and large bony defects of the glenoid (>25% of glenoid diameter). All athletes with recurrent anterior shoulder instability and a large glenoid defect that underwent open anterior shoulder stabilization and glenoid reconstruction with the iliac crest allograft were followed over a 4-year period. Preoperatively, a detailed history and physical exam were obtained along with standard radiographs and magnetic resonance imaging of the affected shoulder. All patients also completed the Simple Shoulder Test (SST) and American Shoulder and Elbow Surgeons (ASES) evaluation forms preoperatively. A computed tomography scan was obtained postoperatively to assess osseous union of the graft and the patient again went through a physical exam in addition to completing the SST, ASES, and Western Ontario Shoulder Instability Index (WOSI) forms. 10 patients (9 males, 1 female) were followed for an average of 16 months (4–36 months) and had a mean age of 24.4 years. All patients exhibited a negative apprehension/relocation test and full shoulder strength at final follow-up. Eight of 10 patients had achieved osseous union at 6 months (80.0%). ASES scores improved from 64.3 to 97.8, and SST scores improved from 66.7 to 100. Average postoperative WOSI scores were 93.8%. The use of the iliac crest allograft provides a safe and clinically useful alternative compared to previously described procedures for recurrent shoulder instability in the face of glenoid deficiency. PMID:25538432

  5. Fracture fixation problems in osteoporosis.

    PubMed

    Strømsøe, Knut

    2004-02-01

    Osteoporosis, or loss of bone mass and microarchitectural deterioration of bone tissue, does not only enhance risk of fracture but also represents a problem in osteofixation of fractures in fracture treatment. Aging of the western population changes the epidemiology of fractures. An increasing socioeconomic interest in geriatric traumatology makes the need for much urgent study in the field of osteoporotic fractures self evident. It is no longer the province of only one medical group to look for fragmented solutions in the treatment of osteoporotic fractures. Efforts have to be united across professional boundaries to meet the challenge of this problem. Assessment of bone mineral may be used in evaluation of fracture risk but also in the choice of implant as well as in the design of implants used in fracture treatment. The differences in mechanical properties of different types of bone in the same individual have to be respected. Changes in the pattern of fractures and problems with implant anchorage in bone, due to a demographic increase in patients with osteoporosis remain problems requiring new solutions. Still basic principals in fracture treatment may not be eclipsed by new fixation devices. PMID:14736465

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

    PubMed Central

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

    2014-01-01

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

  7. Biodegradation of Inion fast-absorbing biodegradable plates and screws.

    PubMed

    Losken, H Wolfgang; van Aalst, John A; Mooney, Mark P; Godfrey, Virginia L; Burt, Tripti; Teotia, Sumeet; Dean, Shay B; Moss, Jonathan R; Rahbar, Reza

    2008-05-01

    Biodegradable plates and screws are recommended for use in surgery of the craniofacial skeleton of children. To be effective and not interfere with growth of the child's skull, the plates must biodegrade sufficiently to release the holding power of the plate and screw within 1 year. It is also essential that excessive foreign body reaction and cyst formation does not occur when the plates and screws biodegrade. The purpose of this experimental study was to evaluate the rate of biodegradation of Inion CPS Baby biodegradable plates and screws under different clinical circumstances in the rabbit craniofacial skeleton and evaluate their efficacy for use in pediatric craniofacial surgery. Foreign body reaction would be evaluated. Inion baby plates and screws were tested in a rabbit model. Plates were applied to the frontal bone, over a bony defect of the parietal bone, to a nasal bone fracture, and inserted in the subcutaneous space over the occipital bone in thirty 6-week-old rabbits. Six rabbits were euthanized at 9, 12, 15, and 18 months' postoperative time point and examined for residual plates and screws. Bone from each surgical site was excised, fixed by immersion in 10% neutral-buffered formalin, decalcified in Immunocal solution, and examined by 7-microm paraffin sections stained with hematoxylin and eosin. At 9 months, the plates and screws had effectively biodegraded and no longer had holding power on the bones. Fragmentation of the implant material was noted. Residual implant material was still present on gross and histologic examination in rabbits at 9, 12, 15, and 18 months. Residue of a screw was still palpable in 1 rabbit at 18 months. There was no evidence of cyst formation in any of the examined specimens. Macrophages and giant cells were present in most of the specimens at 9, 12, 15, and 18 months. Findings from the current study revealed a relative short resorption time (9 mo) and normal inflammatory sequelae in an adult rabbit model. These findings suggest that these plates may be used safely in fixing the pediatric craniofacial skeleton. PMID:18520394

  8. Determination of the of rate cross slip of screw dislocations

    PubMed

    Vegge; Rasmussen; Leffers; Pedersen; Jacobsen

    2000-10-30

    The rate for cross slip of screw dislocations during annihilation of screw dipoles in copper is determined by molecular dynamics simulations. The temperature dependence of the rate is seen to obey an Arrhenius behavior in the investigated temperature range: 225-375 K. The activation energy and the effective attempt frequency can therefore be extracted from the simulations. The transition state energy for the annihilation process is calculated by identifying the transition state using the nudged elastic band path technique. The two activation energies agree very well, indicating that transition state theory is applicable for this type of process. PMID:11041947

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

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

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

  10. Screw- versus cement-retained implant restorations: current concepts.

    PubMed

    Lee, Angie; Okayasu, Kozue; Wang, Hom-Lay

    2010-02-01

    The debate between screw- versus cement-retained implant prostheses has long been discussed but the best type of implant prosthesis remains controversial among practitioners. An understanding of their properties will help the clinician in selecting the ideal prosthesis for each clinical case while promoting final esthetic outcomes. With the evolving technology and knowledge, an update of the current trends is necessary. This article provides an overview of the different characteristics of screw- and cement-retained implant restorations, and how they may influence the esthetics, retrievability, retention, passivity, occlusion, accessibility, cost, and provisional restorations. Problems and complications frequently encountered are discussed and treatment solutions are proposed. PMID:20147811

  11. Effect of cement washout on loosening of abutment screws and vice versa in screw- and cement- retained implant-supported dental prosthesis

    PubMed Central

    Kim, Seok-Gyu; Son, Mee-Kyoung

    2015-01-01

    PURPOSE The purpose of this study was to examine the abutment screw stability of screw- and cement-retained implant-supported dental prosthesis (SCP) after simulated cement washout as well as the stability of SCP cements after complete loosening of abutment screws. MATERIALS AND METHODS Thirty-six titanium CAD/CAM-made implant prostheses were fabricated on two implants placed in the resin models. Each prosthesis is a two-unit SCP: one screw-retained and the other cemented. After evaluating the passive fit of each prosthesis, all implant prostheses were randomly divided into 3 groups: screwed and cemented SCP (Control), screwed and noncemented SCP (Group 1), unscrewed and cemented SCP (Group 2). Each prosthesis in Control and Group 1 was screwed and/or cemented, and the preloading reverse torque value (RTV) was evaluated. SCP in Group 2 was screwed and cemented, and then unscrewed (RTV=0) after the cement was set. After cyclic loading was applied, the postloading RTV was measured. RTV loss and decementation ratios were calculated for statistical analysis. RESULTS There was no significant difference in RTV loss ratio between Control and Group 1 (P=.16). No decemented prosthesis was found among Control and Group 2. CONCLUSION Within the limits of this in vitro study, the stabilities of SCP abutment screws and cement were not significantly changed after simulated cement washout or screw loosening. PMID:26140172

  12. Internal Iliac Artery Aneurysmo–Colonic Fistula after Endovascular Stent-Graft Repair: A Case Report

    PubMed Central

    Fukada, Johji; Tamiya, Yukihiko

    2015-01-01

    We describe rare ilio-enteric fistula that developed after endovascular repair of a left internal iliac artery aneurysm (IIAA). An 83-year-old man with a history of previous surgeries via laparotomies suddenly developed a high fever 3 years after undergoing endovascular abdominal aortic repair (EVAR) with a stent-graft to treat a left isolated IIAA. Computed tomography imaging revealed a fistula between the IIAA and the sigmoid colon. A colostomy was created because severe intraperitoneal adhesions prevented resection of the IIAA. The postoperative course was uneventful and the patient remained free of infection without antibiotics. Residual aneurysms can cause complications after EVAR. PMID:25848433

  13. Internal iliac artery aneurysmo-colonic fistula after endovascular stent-graft repair: a case report.

    PubMed

    Yanase, Yohsuke; Fukada, Johji; Tamiya, Yukihiko

    2015-01-01

    We describe rare ilio-enteric fistula that developed after endovascular repair of a left internal iliac artery aneurysm (IIAA). An 83-year-old man with a history of previous surgeries via laparotomies suddenly developed a high fever 3 years after undergoing endovascular abdominal aortic repair (EVAR) with a stent-graft to treat a left isolated IIAA. Computed tomography imaging revealed a fistula between the IIAA and the sigmoid colon. A colostomy was created because severe intraperitoneal adhesions prevented resection of the IIAA. The postoperative course was uneventful and the patient remained free of infection without antibiotics. Residual aneurysms can cause complications after EVAR. PMID:25848433

  14. Perforated sigmoid diverticulitis in a lumbar hernia after iliac crest bone graft - a case report

    PubMed Central

    2014-01-01

    Background The combination of perforated diverticulitis in a lumbar hernia constitutes an extremely rare condition. Case presentation We report a case of a 66 year old Caucasian woman presenting with perforated sigmoid diverticulitis localized in a lumbar hernia following iliac crest bone graft performed 18 years ago. Emergency treatment consisted of laparoscopic peritoneal lavage. Elective sigmoid resection was scheduled four months later. At the same time a laparoscopic hernia repair with a biologic mesh graft was performed. Conclusion This case shows a very seldom clinical presentation of lumbar hernia. Secondary colonic resection and concurrent hernia repair with a biologic implant have proven useful in treating this rare condition. PMID:25051974

  15. Percutaneous Transosseous Embolization of Internal Iliac Artery Aneurysm Type II Endoleak: Report of Two Cases

    SciTech Connect

    Gemmete, Joseph J., E-mail: gemmete@umich.edu; Arabi, Mohammad; Cwikiel, Wojciech B. [University of Michigan Health System, Department of Radiology (United States)

    2011-02-15

    This report describes two cases of successful treatment of an internal iliac artery aneurysm (IIAA) type II endoleak utilizing a percutaneous transosseous access that could not be treated using an endovascular or standard percutaneous approach. A direct percutaneous approach through bone was chosen to avoid vital structures and the surrounding bowel. The procedure was successful and required minimal fluoroscopy time compared with other treatment options. We believe this procedure is an alternative to some of the more complex and technically challenging means of treating this lesion.

  16. Successful Recanalization of a Longstanding Right Common Iliac Artery Occlusion with a Radiofrequency Guidewire

    SciTech Connect

    Tapping, C. R.; Uri, I. F.; Dixon, S.; Bratby, M. J.; Anthony, S.; Uberoi, R., E-mail: raman.uberoi@orh.nhs.uk [John Radcliffe Hospital, Department of Radiology (United Kingdom)

    2012-10-15

    We describe a case of successful recanalization of a longstanding right common iliac occlusion with a radiofrequency (RF) guidewire. The patient had been symptomatic with claudication for 3 years, and a preliminary attempt to cross the lesion using conventional techniques proved unsuccessful. Using low and medium intensity RF pulses and a PowerWire, a tract through the occlusion was established, which allowed subsequent stenting with an excellent angiographic result and a good immediate clinical response. We propose this as a useful technique in the peripheral arterial system for occlusive lesions not amenable to traditional recanalization techniques.

  17. Dissection of left iliac artery during anterior lumbar interspace fusion: Report of a case.

    PubMed

    Fischer, Uwe M; Davies, Mark G; Sayed, Hosam El

    2015-04-01

    Vascular injury is an uncommon complication of spine surgery. Among the different approaches, anterior lumbar interbody fusion has increased potential for vascular injuries, since the great vessels and their branches overly the disc spaces to be operated on, and retraction of these vessels is necessary to gain adequate surgical exposure. The reported incidence for anterior lumbar interbody fusion-associated vascular injuries ranges from 0% to 18.1%, with venous laceration as the most common type. We report a case of anterior lumbar interbody fusion-associated left common iliac artery dissection leading to delayed acute limb ischemia developing in early post-operative period. PMID:24848500

  18. Superior border versus inferior border fixation in displaced mandibular angle fractures: prospective randomized comparative study.

    PubMed

    Singh, V; Khatana, S; Bhagol, A

    2014-07-01

    A prospective randomized comparative study was conducted to compare open reduction and internal fixation of displaced fractures (>2mm) via intraoral approach with application of a single monocortical miniplate according to Champy's ideal line of osteosynthesis (group A) versus an extraoral approach with application of an inferior border plate with at least two holes (bicortical screws) on either side of the fracture line (group B). Clinical and radiographic assessment was done preoperatively, immediately postoperative, and at 1, 4, and 12 weeks of follow-up. Parametric and non-parametric data were evaluated by independent samples t-test and ?(2) analysis, respectively; P<0.05 was considered statistically significant. There was no significant difference between the two groups with regard to complication rates, although functional outcomes including pain (visual analogue scale score) at the 1-week follow-up and inter-incisal mouth opening at the 12-week follow-up were found to be better in group B. On radiographic assessment, the inferior border was better aligned in group B than in group A, with no superior border distraction in group B. The duration of surgery was shorter in group B, and this was considered to be the easier approach for fixation of the device as assessed by the surgeons. PMID:24636170

  19. Combined Chronic Occipito-atlantal and Atlanto-axial Rotator Fixation with Cerebral Palsy.

    PubMed

    Kim, Jae Hong; Kim, Jung Hee; Jang, Se Youn; Kong, Min Ho

    2013-09-01

    Occipito-atlantalrotatory subluxation that occurs in conjunction with atlanto-axial rotator fixation is extremely rare. The common clinical characteristics are painful torticollis and cock robin position presented with the head tilted to one side and rotated to the other side. The object of this report is to emphasize that AARF combined with OARF may be caused by a variety of conditions, to be must need algorithm for proper management, apparently. A torticollis patient who had cerebral palsy presented with severe nuchal pain and wryneck for a long period. The patient had a history of fallen down 16 years ago which caused severe nuchal pain. The conservative management had failed to correct the deformity and instability. we decided to operate using occiput-C1-C2 arthrodesis and C3-4-5 bilateral screw fixation for reinforcement. Now he doesn't have neurologic deficit and shows good outcome enough to sustain his head, not using his hands, in his daily life. PMID:24757487

  20. New treatment of iliac artery disease: focus on the Absolute Pro® Vascular Self-Expanding Stent System

    PubMed Central

    Gates, Lindsay; Indes, Jeffrey

    2013-01-01

    Management of iliac artery disease has evolved over the years, from a surgical-only approach to a primarily endovascular-only approach as the first line treatment option. This has been continuously improved upon with the advent of new devices and applied technologies. Most recently in particular, the literature has shown good, reliable outcomes with the use of self-expandable stents in iliac artery atherosclerotic lesions. Nevertheless, no device is without its limitations, and the Absolute Pro® Vascular Self-Expanding Stent System was designed with the intent of overcoming some of the shortcomings of other available stents while maintaining acceptable postprocedural outcomes. Based on preliminary industry-acquired data, it has achieved these goals and appears to be an emergent competitor for the treatment of both focal and complex iliac artery lesions. PMID:24049463

  1. A novel approach toward pedicle screw placement in the thoracic spine

    Microsoft Academic Search

    John Thalgott; Mark Kabins; James Giuffre

    2002-01-01

    Purpose of study: Because of the smaller size of the thoracic pedicle, primarily in the coronal plane, most surgeons have opted to avoid the used of transpedicular screws in the thoracic spine. A new technique for placement of screws through thoracic pedicles with and without lateral wall violation is described.Methods used: From April 1992 through February 1999, 1,064 pedicle screws

  2. Influence of the coating material on the loosing of dental implant abutment screw joints

    Microsoft Academic Search

    C. N. Elias; D. C. Figueira; P. R. Rios

    2006-01-01

    Dental implant abutment screw joints tend to loosen and prosthesis rotation has been observed under clinical conditions. Some dental implant manufacturers suggest coated abutment screw to prevent the displacement of dental prosthesis. In the present work, the opening torque (N cm) was measured as a function of tightening torque (N cm) for dental implant abutment screws coated with four different

  3. MECHANICS OF THE TAPER INTEGRATED SCREWED-IN (TIS) ABUTMENTS USED IN DENTAL IMPLANTS

    E-print Network

    Müftü, Sinan

    1 MECHANICS OF THE TAPER INTEGRATED SCREWED-IN (TIS) ABUTMENTS USED IN DENTAL IMPLANTS by Dinçer. Keywords: Dental implants; Taper lock; Morse taper; Conical interference fit; Tapered screw; Screw mechanics; Loosening torque, Tightening torque #12;3 INTRODUCTION A dental implant system serves

  4. On Screw-Transform Manifolds Russell A. Manning Charles R. Dyer

    E-print Network

    Dyer, Charles R.

    describes the mathematical theory of screw-transform manifolds and their use in camera self cali- brationOn Screw-Transform Manifolds Russell A. Manning Charles R. Dyer Department of Computer Sciences transformation that moves the camera from the first location to the second location is equivalent to a screw

  5. Improved Screw Theory using Second Order Terms Jun Takamatsu Hiroshi Kimurat Katsushi Ikeuchi

    E-print Network

    Ikeuchi, Katsushi

    Improved Screw Theory using Second Order Terms Jun Takamatsu Hiroshi Kimurat Katsushi Ikeuchi this displacement, the screw theory is employed. It is equivalent to the first order Taylor expansion of the displacement. The screw theory is very convenient, because the displacement is formulated as simulta- neous

  6. Calculating Possible Local Displacement of Curve Objects using Improved Screw Theory

    E-print Network

    Ikeuchi, Katsushi

    Calculating Possible Local Displacement of Curve Objects using Improved Screw Theory Jun Takamatsu of objects have been pro- posed. To calculate this displacement, the screw theory is employed polyhedral objects only. Because the screw theory cannot treat curvature information of objects

  7. The singularity study of spatial hybrid mechanisms based on screw theory

    Microsoft Academic Search

    J.-S. Zhao; K. Zhou; Z.-J. Feng; Z.-Y. Tan

    2005-01-01

    In this paper, a novel methodology based on screw theory to study the singularity of spatial hybrid mechanisms is presented. According to the physical meaning of inverse screws, we introduce the equivalent kinematic screws to replace the function of those of the parallel limbs, and therefore the hybrid branch can be transformed into a pure series kinematic chain which can

  8. Gauge-field-theory solution of the elastic state of a screw dislocation in a dispersive

    E-print Network

    Sharma, Pradeep

    Gauge-field-theory solution of the elastic state of a screw dislocation in a dispersive (non the solution of most screw dislocation problems in the gauge non-local theory of defects, provided, NY 12309, USA The relaxed state of a type of topological defect (screw dislocation) located

  9. Collision Prediction for Polyhedra under Screw Motions Byungmoon Kim Jarek Rossignac

    E-print Network

    Rossignac, Jarek

    General Terms Theory Keywords Collision Detection, Screw Motion, Polyhedra Permission to make digitalCollision Prediction for Polyhedra under Screw Motions Byungmoon Kim Jarek Rossignac bmkim the relative motion between pairs of objects by a sequence of screw motion segments, each defined

  10. Screw-theoretic analysis models for felid jaw mechanisms Michael J. Delsignore, Venkat N. Krovi *

    E-print Network

    Krovi, Venkat

    Elsevier Ltd. All rights reserved. Keywords: Screw-theory; Musculoskeletal systems; Optimization; CableScrew-theoretic analysis models for felid jaw mechanisms Michael J. Delsignore, Venkat N. Krovi of quasi-static computational models for musculoskeletal analysis, leverag- ing screw-theoretic techniques

  11. A Case of Severe Hemorrhagic Cystitis Caused by Melphalan with Successful Bladder Preservation by Ligation of Bilateral Internal Iliac Arteries

    PubMed Central

    Takeuchi, Takumi; Zaitsu, Masayoshi; Mikami, Koji; Takeshima, Yuta; Matsunaga, Takashi; Okamoto, Naohiko; Imao, Sadao

    2010-01-01

    Hemorrhagic cystitis is a disorder which causes bleeding from diffusely inflammatory bladder mucosa. Here we present a case of severe hemorrhagic cystitis caused by melphalan. A 70-year-old man with multiple myeloma was presented with suddenly commenced massive gross hematuria. During an attempt of transurethral coagulation of bladder mucosa, bladder perforation into peritoneal cavity was suspected, then open laparotomy was indicated. We isolated bilateral internal iliac arteries and ligated them in order to control continued bleeding. After that, bladder bleeding was suddenly diminished. Ligation of internal iliac arteries may be a choice in controlling massive bleeding from bladder with severe hemorrhagic cystitis when laparotomy was inevitable. PMID:20593040

  12. Two Cases of Successful Inferior Mesenteric Artery Preservation with Bare Metal Stent in Endovascular Iliac Artery Aneurysm Repair

    PubMed Central

    2013-01-01

    During endovascular aneurysm repair, interruption of the inferior mesenteric artery (IMA) or internal iliac arteries (IIAs) is thought to be associated with postoperative pelvic ischemic complications, including ischemic colitis. However, preserving the IIA does not guarantee protection against ischemic colitis. We herein report two cases of bilateral common iliac artery aneurysms, which were treated with bifurcated stent grafting with bilateral IIA embolization and simultaneous IMA stent placement to prevent colonic ischemia. This procedure might be effective for both preserving the IMA circulation and preventing ischemic colitis. PMID:24130629

  13. Covered Stent in the Superior Gluteal Artery in a Hybrid Approach to Treat Internal Iliac Artery Aneurysm: A Technical Note.

    PubMed

    Noël-Lamy, Maxime; Teng Tan, Kong; Lindsay, Thomas

    2015-07-01

    This brief report describes a hybrid endovascular and open procedure to treat internal iliac artery (IIA) aneurysms and preserve pelvic blood flow. A covered stent was deployed before surgery in the superior gluteal artery, extending across the IIA aneurysm, with the proximal end in the common iliac artery lumen. During open aortoiliac aneurysm repair, the stent graft was anastomosed in an end-to-side manner to the surgical graft. Four aneurysms were treated in 3 patients. Technical success was achieved in all cases. There were no complications or repeat interventions. Stents were all patent at imaging follow-up (range, 6-25 mo). Patients were free from buttock claudication. PMID:26095271

  14. Atlantoaxial Screw Fixation for the Treatment of Isolated and Combined Unstable Jefferson Fractures – Experiences with 8 Patients

    Microsoft Academic Search

    C. Hein; H.-P. Richter; S. A. Rath

    2002-01-01

    Summary.  \\u000a ?The unstable atlas burst fracture (“Jefferson fracture”) is a fracture of the anterior and posterior atlantal arch with rupture\\u000a of the transverse atlantal ligament and an incongruence of the atlanto-occipital and the atlanto-axial joint facets. The question\\u000a whether it has to be treated surgically or nonsurgically is still discussed and remains controversial. During the last decade\\u000a 8 patients with

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

    Microsoft Academic Search

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

    2007-01-01

    Several types of posterior approaches have been adopted for occipitocervical fusion. Prior to this study, Foerater et al.\\u000a in 1927 used a fibular strut graft in the site between the occiput and the lower cervical spine to achieve fusion. Since then,\\u000a various techniques including wrings, Hartshill loop, AO reconstructive plate, and AXIS occipital plate were described and\\u000a used widely. As

  16. Surgical femorocaval bypass for treating chronic iliac vein occlusion: a case report

    PubMed Central

    Hao, Qingzhi; Ma, Ruiping; Kang, Yanmeng; Chen, Bainan; Wang, Bin; Zheng, Yuehong

    2014-01-01

    Chronic inferior vena cava and iliac vein occlusion, caused by long-term of deep venous thrombosis, will lead to swelling of the limbs, venous claudication and intractable ulcer. However, conservative treatment is often ineffective for vein occlusion. With the development of interventional techniques, endovascular therapy has become the first choice for the treatment of vein occlusion with higher success rate and lower trauma. However, for cases those fail endovascular therapy or for segmental veno-occlusive diseases with low long-term patency rate, venous bypass might be the only option. And, design of anastomotic stoma and orificium fistulae design is crucial to the success of operation. A case of long term deep venous thrombosis patient with occlusion in bilateral iliac vein and distal inferior vena cava was admitted and treated with interventional therapy. Unfortunately, this method failed. Then, we selected reasonable anastomotic stoma and orificium fistulae and performed femorocaval bypass. The 12 month follow-up results showed that the swelling was successively relieved and the ulcer healed. This indicated that rational anastomotic stoma and orificium fistulae could guarantee the exact clinical efficacy of venous bypass and higher long-term patency rate. PMID:25419436

  17. Trace elements in the wall of abdominal aortic aneurysms with and without coexisting iliac artery aneurysms.

    PubMed

    Ziaja, Damian; Chudek, Jerzy; Sznapka, Mariola; Kita, Andrzej; Biolik, Grzegorz; Siero?-Sto?tny, Karolina; Pawlicki, Krzysztof; Domalik, Jolanta; Ziaja, Krzysztof

    2015-06-01

    Iliac artery aneurysms (IAA) and abdominal aortic aneurysms (AAA) frequently coexist. It remains unknown whether the content of trace elements in AAA walls depends on the coexistence of IAAs. The aim of this study was to compare the content of selected trace elements in AAA walls depending on the coexistence of IAAs. The content of trace elements was assessed in samples of AAA walls harvested intraoperatively in 19 consecutive patients. In the studied group, coexisting IAAs were diagnosed in 11 out of the 19 patients with AAA. The coexistence of IAAs was associated with a slightly lower content of nickel (0.28 (0.15-0.40) vs. 0.32 (0-0.85)?mg/g; p?=?0.09) and a significantly higher content of cadmium (0.71 (0.26-1.17) vs. 0.25 (0.20-0.31)?mg/g; p?=?0.04) in AAA walls. The levels of the remaining studied elements, copper, zinc, manganese, magnesium and calcium, were comparable. The elevated levels of cadmium in the walls of AAA coexisting with IAAs may suggest an impact of the accumulation of this trace element on the greater damage of the iliac artery wall. PMID:25637566

  18. Gout in the spine and sacri-iliac joints: radiological manifestations

    SciTech Connect

    Jajic, I.

    1982-06-01

    It is well known that deposits of urates in soft tissues occur commonly in gout, particularly in para-articular areas and in articular cartilages of the limbs. Involvement of the spine and sacro-iliac joints by such deposits, however, has been regarded as being relatively unusual and has attracted little attention in the literature. As we were impressed by the frequency of episodes of acute back pain in our patients with gouty arthritis, established definitely on clinical and biochemical grounds, we undertook a radiological investigation of the spine and sacro-iliac joints in a series of 54 subjects. It was suspected that their episodes of pain were clinical manifestations of gout, and 12 of the group had suffered one or more attacks. Of these 12 subjects, eight were found to have radiological abnormalities. In six subjects, evidence of sacro-iliitis was demonstrated, which is comparable to the report of Resnick and Reinke (8), and in two patients vertebral lesions corresponded to those described by Jaffe (5). Hyperostotic spondylosis was present in no fewer than 29 of the series. Although lacking histological confirmation of the lesions demonstrated radiologically, we believe that our suspicions have been confirmed.

  19. Single and Tandem Stents in Sheep Iliac Arteries: Is There a Difference in Patency?

    SciTech Connect

    Schuermann, Karl; Vorwerk, Dierk; Buecker, Arno; Grosskortenhaus, Stefanie; Guenther, Rolf W. [Department of Diagnostic Radiology, University of Technology, Pauwelsstrasse 30, D-52057 Aachen (Germany)

    1998-09-15

    Purpose: To compare patency and neointima formation of single and tandem arterial stents. Methods: In each of six sheep, two Memotherm nitinol stents (tandem stents) were inserted into the external iliac artery on one side and a single stent into the artery on the opposite side. The size of the iliac lumen was assessed in the proximal, middle, and distal segments of the stents by intravascular ultrasound (IVUS) before, immediately after, and 1 month after implantation when the sheep were killed. Neointimal thickness was determined in the proximal, middle, and distal segments of each stent by light microscopy. Results: All stents remained patent. There was no significant difference in lumen and neointimal thickness between single and tandem stents. Cranial tandem stents showed a significantly wider lumen and smaller neointimal thickness than caudal tandem stents. In the proximal and distal segments, the lumen of the stents was significantly smaller and the neointimal thickness greater than in the middle segment; differences in neointimal thickness were significant only between the proximal and the middle segment. Conclusion: In an experimental setting, tandem stents did not interfere with one another with regard to patency and neointima formation when compared with a single contralateral stent. Neointimal thickening after stent insertion seems to be inversely related to the original arterial diameter.

  20. Calculation of axial forces on the screw in rubber extruders

    Microsoft Academic Search

    S. P. Konclrakov; M. S. Samoilov; N. V. Tyabin; A. G. Govsha

    1972-01-01

    A special hydraulic thrust bearing (Fig. 1) was developed for measuring the axial forces of the screw. The thrust bearing consists of a body 7, a guiding collar 4, a rubber collar 6, assembled in one unit using a clamping nut 5. The cavity formed between the body 7 and the collar 6, and also the connecting pipe 9 and

  1. 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

  2. Twin-screw extrusion of ‘Pesta’-encapsulated biocontrol agents

    Microsoft Academic Search

    D. J. Daigle; W. J. Connick; C. D. Boyette; M. P. Lovisa; K. S. Williams; M. Watson

    1997-01-01

    ‘Pesta’ granules in which fungal propagules are encapsulated in a wheat gluten matrix were prepared in multipound quantities by twin-screw extrusion and fluid bed drying. Dough formulations for extrusion contained wheat flour and kaolin, or wheat flour, kaolin and rice flour, plus water and fungal inoculum. Conidial inoculum of Colletotrichum truncatum, a pathogen of the weed hemp sesbania (Sesbania exaltata),

  3. Some refinements of the theory of the viscous screw pump.

    NASA Technical Reports Server (NTRS)

    Elrod, H. G.

    1972-01-01

    Recently performed analysis for herringbone thrust bearings has been incorporated into the theory of the viscous screw pump for Newtonian fluids. In addition, certain earlier corrections for sidewall and channel curvature effects have been simplified. The result is a single, refined formula for the prediction of the pressure-flow relation for these pumps.

  4. Successive Screw Approximation in Ising Lattice Gauge Theory

    NASA Astrophysics Data System (ADS)

    Katsumori, H.

    1984-01-01

    Kramers and Wannier's successive screw technique is applied to the three-dimensional Ising lattice gauge theory. The largest eigenvalue of the transfer matrix is directly calculated on a computer, independently of Monte Carlo simulation. Anomalous behavior of the specific heat implies the existence of a phase transition.

  5. Force between two parallel screw dislocations - gauge theory result

    NASA Astrophysics Data System (ADS)

    Valsakumar, M. C.; Sahoo, Debendranath

    1996-02-01

    The expression for the force between two parallel screw dislocations is derived in the framework of the Yang-Mills-type gauge theory of dislocations earlier proposed by Kadic and Edelen [A gauge theory of dislocations and disclinations (Springer, Berlin, 1983)] and later developed by Valsakumar and Sahoo [Bull. Mater. Sci. 10 (1988) 3].

  6. Dynamics of parallel manipulators by means of screw theory

    Microsoft Academic Search

    J. Gallardo; J. M. Rico; A. Frisoli; D. Checcacci; M. Bergamasco

    2003-01-01

    An approach to the dynamic analysis of parallel manipulators is presented. The proposed method, based on the theory of screws and on the principle of virtual work, allows a straightforward calculation of the actuator forces as a function of the external applied forces and the imposed trajectory. In order to show the generality of such a methodology, two case studies

  7. Jerk Influence Coefficients, via Screw Theory, of Closed Chains

    Microsoft Academic Search

    J. Gallardo-Alvarado; J. M. Rico-Martinez

    2001-01-01

    In this paper a novel method for determining the kinematic influence coefficients up to the jerk analysis of closed chains with multiple degrees of freedom by means of screw theory, also known as motor algebra, is introduced. A closed chain is obtained by rigidly attaching the end-effector of a serial chain to the base link. This condition ensures that the

  8. Force between two parallel screw dislocations — gauge theory result

    Microsoft Academic Search

    M. C. Valsakumar; Debendranath Sahoo

    1996-01-01

    The expression for the force between two parallel screw dislocations is derived in the framework of the Yang-Mills-type gauge theory of dislocations earlier proposed by Kadic and Edelen [A gauge theory of dislocations and disclinations (Springer, Berlin, 1983)] and later developed by Valsakumar and Sahoo [Bull. Mater. Sci. 10 (1988) 3].

  9. A computational analysis of screw transformations in robotics

    Microsoft Academic Search

    JANEZ FUNDA; RICHARD P. PAUL

    1990-01-01

    A computational analysis and a comparison of line-oriented representations of general (i.e. rotational and translational) spatial displacements of rigid bodies are presented. Four mathematical formalisms for effecting a general spatial screw displacement are discussed and analyzed in terms of computational efficiency in performing common operations needed in kinematic analysis of multilinked spatial mechanisms. The corresponding algorithms are analyzed in terms

  10. 39. VIEW OF VESSEL STERNON IN DRYDOCK. NOTE TWIN SCREWS ...

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

    39. VIEW OF VESSEL STERN-ON IN DRYDOCK. NOTE TWIN SCREWS AND RUDDER. GENTLEMEN IN VIEW UNKNOWN Original 5'x5' photograph taken by Robert S. Douglas in 1966 - Pilot Schooner "Alabama", Moored in harbor at Vineyard Haven, Vineyard Haven, Dukes County, MA

  11. The empirical modeling of a Lysholm screw expander

    Microsoft Academic Search

    R. F. Stiedel; K. A. Brown; D. H. Pankow

    1983-01-01

    This is a description of the development of an engine model for the prediction of mass flow rate, power, efficiency and exhaust quality for a Lysholm Screw Expander at a given set of operating conditions. The testing of an expander having a rotor diameter of 130 mm (5.12 inches) and an expansion ratio of 5.3 was performed with simulated geothermal

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

    E-print Network

    Kawamura, K.; Apaloo, Thomas-L.

    1986-01-01

    the low pressure steam to a usable pressure for reinjection into the process stream. Mycom has developed, designed and installed two large MVR systems using screw compressors: one for a brewery and the other for a whiskey plant. This paper discusses...

  13. Review Article: Screw Compressors in Refrigeration and Air Conditioning

    Microsoft Academic Search

    Nikola Stoši?

    2004-01-01

    Recent advances in the techniques for manufacturing vital parts, such as rotors and bearings, have enabled improvements to be made to screw compressors that were difficult to imagine only a few years ago. This has inevitably influenced the prospects for these machines in refrigeration and air-conditioning applications. Some aspects of this are presented, together with well known but not always

  14. A Screw Syzygy with Applications to Robot Singularity Computation

    Microsoft Academic Search

    J. M. Selig; Peter Donelan

    A syzygy is a relation between invariants. In this paper a syzygy is presented between invariants of sequences of six screws\\u000a under the action of the Euclidean group. This relation is useful in simplifying the computation of the determinant of a robot\\u000a Jacobian and hence can be used to investigate the singularities of robot manipulators.

  15. Covering the screw-access holes of implant restorations in the esthetic zone: a clinical report.

    PubMed

    Saboury, Abolfazl; Gooya, Ali

    2014-11-01

    Screw-retained implant restorations have an advantage of predictable retention as well as retrievability, and obviate the risk of excessive sub-gingival cement commonly associated with cement retained implant restorations. Screw-retained restorations generally have screw access holes, which can compromise esthetics and weaken the porcelain around the holes. The purpose of this study is to describe the use of a separate overcasting crown design to cover the screw access hole of implant screw-retained prosthesis for improved esthetics. PMID:25628703

  16. The Fixation and Saccade P3

    PubMed Central

    Dandekar, Sangita; Ding, Jian; Privitera, Claudio; Carney, Thom; Klein, Stanley A.

    2012-01-01

    Although most instances of object recognition during natural viewing occur in the presence of saccades, the neural correlates of objection recognition have almost exclusively been examined during fixation. Recent studies have indicated that there are post-saccadic modulations of neural activity immediately following eye movement landing; however, whether post-saccadic modulations affect relatively late occurring cognitive components such as the P3 has not been explored. The P3 as conventionally measured at fixation is commonly used in brain computer interfaces, hence characterizing the post-saccadic P3 could aid in the development of improved brain computer interfaces that allow for eye movements. In this study, the P3 observed after saccadic landing was compared to the P3 measured at fixation. No significant differences in P3 start time, temporal persistence, or amplitude were found between fixation and saccade trials. Importantly, sensory neural responses canceled in the target minus distracter comparisons used to identify the P3. Our results indicate that relatively late occurring cognitive neural components such as the P3 are likely less sensitive to post saccadic modulations than sensory neural components and other neural activity occurring shortly after eye movement landing. Furthermore, due to the similarity of the fixation and saccade P3, we conclude that the P3 following saccadic landing could possibly be used as a viable signal in brain computer interfaces allowing for eye movements. PMID:23144959

  17. Nitrogen fixation and nitrogen fertilization of soybeans.

    PubMed

    Merbach, W; Jacob, H J

    1996-08-01

    Abstract In pot experiments with (15)N labelled soil and mineral (15)N, the influence of Bradyrhizobium (Rhizobium japonicum) inoculation and N fertilization on the symbiotic N(2) fixation and yield of soybeans [Glycine max (L.) Merill., cv. 'Fiskeby V'] was investigated. Symbiotic N(2) fixation only occured after inoculation with Bradyrhizobium. Considerable differences in efficiency of the bacterial preparations were observed. Shortly after flowering, the symbiotic nitrogen fixation was finished and, subsequently, soybeans took up considerable N amounts from the soil. N fertilization at seeding suppressed N(2) fixation of soybeans. In this case, the dry matter and nitrogen yield increased, because the loss of fixed nitrogen was overcompensated by the mineral N uptake. During flowering of soybeans, the N(2) fixation was not affected by N supply, because this process was already terminated. The mineral N was additionally available to the plants and led to increased N amounts in plants. It was absorbed to a considerable degree by soybeans. The mineral N was translocated (partly, after intermediate storage in the vegetative organs) into the seeds thus increasing their yields. PMID:22088108

  18. The general theory of blade screws including propellers, fans, helicopter screws, helicoidal pumps, turbo-motors, and different kinds of helicoidal blades

    NASA Technical Reports Server (NTRS)

    De Bothezat, George

    1920-01-01

    Report presents a theory which gives a complete picture and an exact quantitative analysis of the whole phenomenon of the working of blade screws, but also unites in a continuous whole the entire scale of states of work conceivable for a blade screw. Chapter 1 is devoted to the establishment of the system of fundamental equations relating to the blade screw. Chapter 2 contains the general discussion of the 16 states of work which may establish themselves for a blade screw. The existence of the vortex ring state and the whirling phenomenon are established. All the fundamental functions which enter the blade-screw theory are submitted to a general analytical discussion. The general outline of the curve of the specific function is examined. Two limited cases of the work of the screw, the screw with a zero constructive pitch and the screw with an infinite constructive pitch, are pointed out. Chapter 3 is devoted to the study of the propulsive screw or propeller. (author)

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

    PubMed Central

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

    2009-01-01

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

  20. Biometric recognition via fixation density maps

    NASA Astrophysics Data System (ADS)

    Rigas, Ioannis; Komogortsev, Oleg V.

    2014-05-01

    This work introduces and evaluates a novel eye movement-driven biometric approach that employs eye fixation density maps for person identification. The proposed feature offers a dynamic representation of the biometric identity, storing rich information regarding the behavioral and physical eye movement characteristics of the individuals. The innate ability of fixation density maps to capture the spatial layout of the eye movements in conjunction with their probabilistic nature makes them a particularly suitable option as an eye movement biometrical trait in cases when free-viewing stimuli is presented. In order to demonstrate the effectiveness of the proposed approach, the method is evaluated on three different datasets containing a wide gamut of stimuli types, such as static images, video and text segments. The obtained results indicate a minimum EER (Equal Error Rate) of 18.3 %, revealing the perspectives on the utilization of fixation density maps as an enhancing biometrical cue during identification scenarios in dynamic visual environments.