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Copyright of European Spine Journal is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Using an interactive, 3D, kinematic simulation of the human skeleton, the motion of the sacro-iliac (SI) joint is modeled based upon descriptions available in the literature. The major ligaments are added to the simulation data structure using deformable cubic B-spline curve paths. Ligament strains were generated and studied in response to the motion simulations. Results improve our understanding of sacro-iliac kinematics and highlight the importance of further studies to elucidate pathological as well as normal SI joint and ligament function.

In the view of efficiency and cost effectiveness the increasing incidence of gunshot wounds in Europe demands a modification of treatment protocols. The general basis are debridement of soft tissue injuries, antibiotics and fracture stabilization. The pathology of gunshot wounds and established treatment algorhithms, however have to be adjusted to the ongoing development of gun technology and the thereby caused specific lesions. The treatment of injuries caused by high velocity projectiles necessitates a proactive surgical strategy. Small caliber gunshot wounds can be treated more conservatively. The following review presents an overview on the ballistic and surgical basis for the treatment of gunshot wounds of the musculoskeletal system.

Intramedullary nailing is the standard treatment for closed and some open unstable diaphyseal tibia fractures. Fluoroscopy, while essential for proper nail placement can subject the surgical team and patient to substantial radiation. A new targeting system for tibia nail distal interlocking was developed by Orthofix to limit fluoroscopy. This prospective clinical study compares the Orthofix targeting system versus a free-hand technique for the tibial nail distal interlocking. Fifty eight consecutive patients with sixty tibial fractures amenable for nail fixation were randomly assigned into two equal groups: Group 1: Orthofix distally based distal targeting device and Group 2: a free-hand technique. In all the cases stabilization was achieved with a reamed statically locked tibial nail. Recorded data included accuracy of screw placement, duration of surgery prior to and during distal interlocking, and the fluoroscopy time prior to and during distal interlocking. Both groups revealed comparable fracture patterns. In all fractures the technical aspects of the surgical treatment were performed without complications. There was no statistically significant difference between the groups in the mean time of surgery prior to (62.02 vs. 61.01 min, P=0.92) and during distal interlocking (17.06 vs. 19.08 min, P=0.55), or in the total surgical time (81 vs. 85 min), respectively. Neither was there a statistically significant difference in the mean fluoroscopy time prior to distal interlocking (69 vs. 81 s, p=0.22) nor in the total fluoroscopy time (84 vs. 117 s). There was however, a statistically significant difference between the Orthofix and free-hand groups with regards to the mean fluoroscopy time during distal interlocking (15 vs. 36 s, P=0.01, respectively). This study demonstrates that the distally based distal targeting device by Orthofix for tibial nailing can significantly decrease the mean fluoroscopy time necessary to complete distal interlocking versus free-hand technique.

The radiographic interpretation of sacroiliac screws relative to the S1 neuroforamen is difficult for orthopedic surgeons and radiologists. Computed tomography (CT) with axial images alone or combined with multiplanar reconstructions are often used to assess screw position. The reliability, reproducibility, and accuracy of orthopedist and radiologist interpretations of axial CT images with and without multiplanar reconstructions was determined using 24 cadaveric hemipelves with known sacroiliac screw position. Interobserver reliability of determining screw position was fair for orthopedists and slight for radiologists regardless of imaging modality or screw composition. Intraobserver reproducibility was moderate for orthopedists regardless of imaging modality or screw type. Reproducibility among radiologists was moderate using axial images of titanium screws and substantial with addition of multiplanar reconstructions. Overall accuracy was similar for orthopedists and radiologists. CT images with multiplanar reconstructions improve accuracy in determining sacroiliac screw position, but not significantly. Current imaging modalities are limited by large inaccuracies and by interobserver and intraobserver variation.

Recombinant adenoviral vectors have been shown to be potential new tools for a variety of musculoskeletal defects. Much emphasis in the field of orthopedic research has been placed on developing systems for the production of bone. This study aims to determine the necessary conditions for sustained production of high levels of active bone morphogenetic protein 2 (BMP2) using a recombinant adenovirus type 5 (Ad5BMP2) capable of eliciting BMP2 synthesis upon infection and to evaluate the consequences for osteoprogenitor cells. The results indicate that high levels (144 ng/ml) of BMP2 can be produced in non-osteoprogenitor cells (A549 cell line) by this method and the resultant protein appears to be three times more biologically active than the recombinant protein. Surprisingly, similar levels of BMP2 expression could not be achieved after transduction with Ad5BMP2 of either human bone marrow stromal cells or the mouse bone marrow stromal cell line W20-17. However, human bone marrow stromal cells cultured with 1 microM dexamethasone for four days, or further stimulated to become osteoblast-like cells with 50 microg/ml ascorbic acid, produced high levels of BMP2 upon Ad5BMP2 infection as compared to the undifferentiated cells. The increased production of BMP2 in adenovirus transduced cells following exposure to 1 microM dexamethasone was reduced if the cells were not given 50 microg/ml ascorbic acid. When bone marrow stromal cells were allowed to become confluent in culture prior to differentiation, BMP2 production in response to Ad5BMP2 infection was lost entirely. Furthermore, the increase in BMP2 synthesis seen during differentiation was greatly decreased when Ad5BMP2 was administered prior to dexamethasone treatment. In short, the efficiency of adenovirus mediated expression of BMP2 in bone marrow stromal cells appears to be dependent on the differentiation state of these cells., (Copyright 2001 Wiley-Liss, Inc.)

Pelvic fractures (PF) sustained from accidents are commonly believed to be a major cause of mortality in polytraumatized patients. The purpose of this paper is to determine whether PF are usually the primary cause or a contributing cause of mortality in these patients. A 10-year retrospective review was performed of all polytrauma patients with PF who were admitted to, and died, at a large, level-I trauma center. The pelvic injury was graded according to Schatzker and Tile into stable (type A), partially stable (type B), and unstable (type C). The injury severity score (ISS), which incorporates associated injuries and their potential impact on mortality, was calculated for all patients. For each patient, a separate subjective designation of the probable cause of death was determined. We identified 74 decedents with PF following deceleration trauma. The pelvic fractures were classified as 12 type A (16%), 36 type B (49%), and 26 type C (35%). The mean ISS was extremely high, 40.6 +/- 1.4 (range 18-75), more than four times the score for simply a severe PF. The ISS was also not significantly different among the three pelvic fracture groups (P = 0.613). The records subjectively identified PF as the precipitating cause of death in only 13% of the patients. In this study, patients who died with PF had an ISS that implicated at least one or two additional major visceral injuries. These data do not support the hypothesis that PF, regardless of its complexity, is the usual primary cause or the major precipitating event of death in the polytraumatized patient. In these patients, mortality appears to be a function of the associated injuries based on the ISS calculation.

Background: Locked intramedullary (IM) nailing has been recognized as one of the most reliable methods for treatment of femoral shaft fractures. Although IM nails are routinely used in the treatment of these fractures, the long-term effects of retained IM nails are unknown., Methods: Seventeen patients with radiographically documented healed fracture of femoral diaphysis after locked IM nailing technique were evaluated at a follow-up of at least 18 months postoperatively. All patients had returned to their preinjury level of function and activity before the study. The bone mineral densities (BMD) of the injured and contralateral femora were measured using dual energy x-ray absorptiometry (DEXA). BMD of symmetrical regions in the femoral neck and medial and lateral femoral cortex of the implanted and contralateral femora were compared. Postinjury muscle function was assessed from measurement of the isometric strength of six separate muscle groups (quadriceps, hamstrings, hip extensors, hip flexors, hip abductors, and hip adductors) in treated and control extremities., Results: The average BMD of the femoral neck region of instrumented femora was 9% less than in contralateral control. Within the medial cortex, BMD of the control femora was an average of 20% greater than in the implanted side. In the lateral cortex, the difference averaged 13%. The isometric dynamometric data demonstrated a statistically significant reduction in the strength of the quadriceps of the instrumented extremities as compared with the contralateral ones. There was no significant difference in the strength of the hamstrings, hip extensors, hip flexors, abductors, or adductors. In the control extremities, the average torque generated by isometric contraction of the quadriceps was 3.45+/-1.35 times greater than by the hamstrings. Torque in extension/flexion and abduction/adduction was also observed., Conclusion: Our data suggest that limbs with long-term retained IM nails experience a significant reduction in the femur BMD and quadriceps muscle strength. These findings may not be simply related to the implant, and further study is warranted to determine the causes of these changes.

Historically, posterior fixation and fusion have been the most popular method of internally stabilizing the cervical spine after injury. Although techniques such as wiring are effective for most injuries, these methods are inadequate in the absence of intact posterior elements or extension and rotation injuries. We review the indications and techniques for posterolateral mass plate fixation that are useful in these difficult fractures.

This study examined the influence of early versus late initial presentation of patients with cervical spine facet dislocation on presentation, neurologic deficit, and the success of closed reduction. Thirty-four patients were studied, and approximately 35% presented at least 72 hours following their injury. Compared with patients who presented early, this late group demonstrated less neurologic deficit, and closed reduction was less likely to be successful. These findings suggest that a distinction should exist in the management algorithm between early versus late presentation of cervical facet dislocation.

In the United States, train-related accidents account for more than 18,000 injuries and 1,200 fatalities annually, yet there is a paucity of literature pertaining to this unique injury. We reviewed the medical records of 98 of 135 cases of train-related trauma treated at Ben Taub General Hospital, Baylor College of Medicine, Houston, Texas, from 1990 to 1995. There were 50 train-pedestrian accidents, 47 train-automobile accidents, and 1 train-motorcycle accident, with a mean patient age of 30.1 years (range, 2 to 66 years). Eighteen patients (18%) were pronounced dead on arrival or died shortly after admission. Of the other 80 patients, 27 (34%) were discharged from the emergency department after minor medical treatment, while 53 (66%) were hospitalized, of whom 10 (13%) later expired. The mean Injury Severity Score (ISS) was 11.9 (discharged, 1.8; hospitalized, 14.3; expired, 29.2). Forty-five patients (56%) sustained 57 extremity fractures, and 30 patients (38%) required 40 amputations. Mean Mangled Extremity Severity Score (MESS) for all injured extremities was 5.2 (amputation, 7.7; no amputation, 2.8). On average, the hospitalization cost per patient was greater than $18,698, while the reimbursement from the patients was $2,261, leaving the hospital with a net deficit of approximately 2 million dollars. Surprisingly, train accidents do not always result in serious injury. However, when serious injury is sustained, it is often of high morbidity (amputation) and mortality, which appears to correlate well with the initial MESS and ISS. Extrapolating our cost data to include all train-related accident injuries and deaths indicates that the direct costs to society may exceed 300 million dollars annually. Greater public awareness and preventive measures may reduce the tremendous human and financial costs of train-related accidents.