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Biomedical subjects

R W Lindsey

Publications and source records attributed to R W Lindsey.

At least 19 recordsLinked to original sources
PubMed2005

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

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.

Acetabulum↗
PubMed2003

Osteoinduction by ex vivo adenovirus-mediated BMP2 delivery is independent of cell type.

The objective of the study was to analyze and compare the abilities of various human cell types with inherently dissimilar osteogenic potentials to induce heterotopic bone formation following ex vivo transduction with two distinct adenoviral vectors encoding bone morphogenetic protein type 2 (BMP2). The cells comprised primary human bone marrow mesenchymal stem cells (BM-MSCs), primary human skin fibroblasts (SFs), and a human diploid fetal lung cell line (MRC-5). The vectors included adenovirus type 5 or a chimeric adenovirus type 5 with the fiber gene of adenovirus type 35 (Ad5F35-BMP2), both demonstrating significantly different expression of BMP2 in vitro. The experimental groups consisted of the three human cell types transduced with each of the two adenoviral vectors. Using nonobese diabetic severe combined immunodeficiency (NOD/SCID) mice, the transduced cells were injected intramuscularly following ex vivo adenoviral transduction. The nature and extent of heterotopic bone formation were analyzed radiographically and histologically. At 14 days postinjection, abundant, highly mineralized bone was formed in mice injected with Ad5F35-BMP2-transduced cells irrespective of the cell type. There was no statistically significant difference in the amount of bone formed between BM-MSCs, SFs, and MRC-5 cells transduced with Ad5F35-BMP2, as assessed from bone surface area on biplanar plain radiography. Substantially lesser amounts or no bone could be detected in mice injected with cells transduced with Ad5-BMP2. Immunohistochemical analysis confirmed the presence of human cells in muscle as early as 2 days postdelivery; however, at 6-7 days after injection, the transduced cells could not be detected in surrounding muscle, or in the heterotopic bone, indicating the host origin of the newly formed bone. The results of the study demonstrate no significant difference in osteoinductive properties between BM-MSCs, SFs, and MRC-5 cells transduced ex vivo with the same type of adenovirus encoding BMP2. The level of BMP2 expression appears to be a crucial factor determining the extent of heterotopic bone formation and was significantly affected by the type of adenovirus used. In the cell types studied, Ad5F35-BMP2 was more efficacious than Ad5-BMP2 in providing adequate levels of BMP2 for efficient osteoinduction.

Adenoviridae↗
PubMed2002

[Treatment approaches in gunshot injuries of the extremities].

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.

Arm Injuries↗
PubMed2001

Pelvic fracture among polytrauma decedents. Trauma-based mortality with pelvic fracture--a case series of 74 patients.

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.

Adult↗
PubMed2001

Tibial intramedullary nail distal interlocking screw placement: comparison of the free-hand versus distally-based targeting device techniques.

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.

Adolescent↗
PubMed2001

Preemptive analgesic effects of ketorolac in ankle fracture surgery.

BACKGROUND: Preemptive analgesia has been difficult to show in human experiments. If ketorolac has preemptive effects, then there may be an advantage to administering it at the beginning of surgery despite the potential for increased blood loss. METHODS: The authors performed a randomized, double-blind, controlled trial of 48 patients scheduled for ankle fracture surgery in a county trauma hospital. Anesthesia management was standardized and included adequate opioid analgesia (5 microg/kg fentanyl and 0.1 mg/kg morphine). Intravenous 30 mg ketorolac was administered to 23 patients before tourniquet inflation and to 25 patients after tourniquet inflation. Visual analog scale pain scores, morphine patient-controlled analgesia consumption, nausea-vomiting, and postoperative bleeding were measured. RESULTS: The 23 patients given ketorolac before tourniquet inflation had no increase in pain postoperatively compared with their preoperative baseline (P = 0.280). The 25 patients who received ketorolac minutes later after tourniquet inflation had significant increases in their postoperative pain compared with their preoperative baseline (P = 0.00116). This effect was short-lived, and by 6 h the pain score in this group was not significantly more than it was preoperatively. Intergroup comparison showed a lower visual analog scale score at 2 (P = 0.0203) and 4 h (P = 0.00549) in the preemptive group and lower nausea scores at hour 6 (P = 0.00704). There was no difference in patient-controlled analgesia consumption between groups. CONCLUSIONS: Intravenous 30 mg ketorolac appears to have preemptive analgesic effects in patients undergoing ankle fracture repair. Ketorolac administered before tourniquet inflation prevents postoperative pain being perceived as more intense than preoperative pain.

Adult↗
PubMed2001

Computed tomography assessment of sacroiliac screw placement relative to the first sacral neuroforamen.

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.

Aged↗
PubMed2000

Bending of the Cotrel-Dubousset instrumentation after direct trauma: a case report.

STUDY DESIGN: Case report. OBJECTIVES: To describe a fracture through the fusion mass of a spine that had been corrected previously with Cotrel-Dubousset rods. These rods had failed in bending after direct trauma. SUMMARY OF BACKGROUND DATA: Nine years after successful treatment of scoliosis with Cotrel-Dubousset instrumentation, the patient was in a motor vehicle accident and sustained a hyperextension spine injury with complete L1-L2 paraplegia and disruption of the fusion mass. The Cotrel-Dubousset instrumentation rods, which failed in bending, could not be corrected in situ, and the angulated segments had to be resected. The spine then became extremely unstable, and the patient consulted the authors for definitive stabilization. RESULTS: The spine was stabilized by attaching the proximal and distal retained Cotrel-Dubousset instrumentation to supplemental rods in a "domino" fashion. Crosslinks were added to improve the torsional stability. Intraoperatively, the fracture was well reduced, and the fixation was stable. A posterolateral fusion was performed with allogenic bone graft. CONCLUSION: Bent Cotrel-Dubousset instrumentation rods are still very strong and may not correct in situ.- If resection is required, the retained portions of Cotrel-Dubousset instrumentation can serve as attachments to restore stable fixation a "domino"technique.

Accidents, Traffic↗
PubMed2000

The cylindrical titanium mesh cage for treatment of a long bone segmental defect: description of a new technique and report of two cases.

This report describes a new technique for treatment of a segmental defect in long bones that uses a cylindrical titanium mesh cage, in combination with cancellous bone allograft and demineralized bone matrix putty (Grafton), stabilized with a statically locked intramedullary nail. Two clinical cases of tibia defects treated with this technique are presented. At the one-year follow-up, radiographically both cases demonstrated excellent limb alignment, stability, and bony healing. Immediate full weight-bearing was initiated in each case, and early limb functional recovery was achieved. Preliminary data suggest that this technique may be a reasonable alternative to currently used methods for management of select long bone segmental defects.

Adult↗
PubMed2000

Long-term residual musculoskeletal deficits after femoral shaft fractures treated with intramedullary nailing.

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.

Adolescent↗
PubMed2000

Posterior lateral mass plate fixation of the cervical spine.

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.

Bone Plates↗
PubMed1998

Imaging assessment of sacroiliac screw placement relative to the neuroforamen.

STUDY DESIGN: Twenty-four cannulated sacroiliac screws were placed bilaterally into 12 cadaveric pelvi (12 titanium screws and 12 stainless-steel screws) and were imaged using conventional and multiplanar reconstructed computed tomography. OBJECTIVES: To determine whether sacroiliac screw position assessment relative to the neuroforamen is enhanced by: 1) computed tomography using multiplanar reconstructions and 2) the use of titanium screws rather than stainless-steel screws. SUMMARY OF BACKGROUND DATA: To the authors' knowledge, there have been no prior studies demonstrating the accuracy of multiplanar computed tomography compared with that of conventional (axial) tomography in determining the position of sacroiliac screws relative to the neuroforamen. Although titanium screws have been shown to have less scatter than stainless-steel screws, the effect of alloy composition on the radiographic accuracy of interpreting the screw position relative to the sacral neuroforamen is unknown. METHODS: Screws were deliberately placed into: position A, in which the screw did not violate the neuroforamen; position B, in which the threads of the screw came within 3 mm of the neuroforamen; and position C, in which the screw clearly was nearly centered in the neuroforamen. The degrees of accuracy in assessing screw position relative to the neuroforamen using conventional (axial) images and using multiplanar reconstructed images were compared. RESULTS: The axial images were accurate in determining screw position relative to the neuroforamen in 50% of cases in which titanium screws were used and in 42% of cases in which stainless-steel screws were used. The corresponding values for multiplanar reconstructions were 92% for cases in which titanium screws were used and 67% for cases in which stainless-steel screws were used. The accuracy of multiplanar reconstructions was statistically better than that of axial images (P < 0.05). Metallic scatter was increased in stainless-steel screws. CONCLUSIONS: The results of this study suggest that the use of computed tomography with multiplanar reconstruction improves accuracy in determining sacroiliac screw position relative to the neuroforamen. The assessment of screw position may be facilitated using titanium screws.

Aged↗
PubMed1998

Effect of ciprofloxacin on the proliferation of osteoblast-like MG-63 human osteosarcoma cells in vitro.

Locally applied antibiotic therapy is gaining popularity for the treatment of infections associated with open fractures and posttraumatic osteomyelitis. With use of local techniques, ciprofloxacin levels as high as 1,300 microg/ml, or over 200 times the bone levels achieved with intravenous administration, have been reported. To study the possible effects of ciprofloxacin on bone, osteoblast-like cells from the MG-63 human osteosarcoma cell line were studied. The cells were grown in antibiotic-free media and exposed to concentrations of ciprofloxacin at 0, 10, 100, 200, and 1,000 microg/ml to establish an initial dose-response curve. Media containing the appropriate dose of ciprofloxacin were changed every 24 hours. Cell number and [3H]thymidine incorporation per cell were determined at 0, 24, and 72 hours. A second dose-response curve was performed at concentrations of 0, 10, 20, 40, and 80 microg/ml. Three experiments, each with four observations, were performed. The results of this study demonstrated that ciprofloxacin caused significant decreases (p < 0.05) in cell number at 40 microg/ml at 24 hours and 20 microg/ml at 72 hours. [3H]thymidine incorporation per cell decreased significantly at levels of 80 microg/ml at 24 hours and 20 microg/ml at 72 hours. The authors conclude that reported local levels of ciprofloxacin seen in vivo inhibit the proliferation of human osteoblast-like cells in vitro.

Anti-Infective Agents↗
PubMed1998

Optimal location of a single distal interlocking screw in intramedullary nailing of distal third femoral shaft fractures.

OBJECTIVE: This biomechanical study was done to determine the effect of the level of a single distal screw in a static intramedullary (IM) femoral nail on the stability of fixation of a fracture in the distal third of the femur. DESIGN: Fifteen composite fiberglass femora were osteotomized transversely in the distal third of the femur. A Grosse-Kempf nail was implanted into the femurs, which were divided into three groups of five specimens. Single screw distal nail locking was varied distal to the osteotomy site for each group at 2.5, 5.0, and 7.5 centimeters, respectively. INTERVENTION: All instrumented femurs were mounted on a servohydraulic testing machine and fitted with transducers to measure axial, rotational, and bending displacements. Specimens were cyclically loaded (one hertz) in simultaneous torsion (moment: +/- 10 newton-meters) and axial compression (amplitude: 2,000 newtons) for 500 cycles with a 250-pound abductor force. MAIN OUTCOME MEASUREMENT: Data from linear and rotational transducers were sampled at 100 hertz for five cycles before cycling, every 100 cycles of loading, and immediately after cycling. Custom computer software was developed to convert transducer signals into static and dynamic measurements of axial motion (in millimeters), rotation (in degrees), and angulation (in degrees). RESULTS: Osteotomy site dynamic rotation increased significantly in specimens locked at 7.5 centimeters when compared with the 2.5-centimeter group. There was minimal difference between the stability of the 5.0-centimeter and 7.5-centimeter groups. There was no significant change in position at the fracture site before or after cyclic loading with respect to axial shortening, rotation, or bending. Both dynamic axial and angular displacements were also unaffected by screw position. CONCLUSION: The location of a single distal interlocking screw in static IM nail fixation of distal third femur fractures can significantly affect rotational stability but not axial or angular fixation.

Biomechanical Phenomena↗
PubMed1998

Cervical facet dislocation: management following delayed diagnosis.

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.

Adolescent↗
PubMed1998

Train accidents involving pedestrians, motor vehicles, and motorcycles.

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.

Accidents, Traffic↗