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Biomedical subjects

B L Allen

Publications and source records attributed to B L Allen.

At least 73 records · Page 4Linked to original sources
PubMed1977

Vascular injuries associated with dislocation of the knee.

Two hundred and forty-five knee dislocations were analyzed including forty-one new cases. The high incidence of injuries to the popliteal artery that accompanies this lesion (32 per cent) was confirmed, and it was re-emphasized that vascular repair must be completed within six or at the most eight hours from the time of injury to avoid amputation. Of the patients not treated within that time period, 86 per cent had an amputation and two-thirds of the remaining 14 per cent had ischemic changes.

Amputation, Surgical↗
PubMed1975

The Pavlik harness for congenital dislocated hips.

The use of the Pavlik harness for treatment of congenital dislocated hips was begun at The University of Texas Medical Branch at Galveston, Texas, in August 1973. A method for rapid measurement and construction was subsequently developed. Data on length of use and case studies are presented.

Hip Dislocation, Congenital↗
PubMedDate not supplied

Same-day versus staged anterior-posterior spinal surgery in a neuromuscular scoliosis population: the evaluation of medical complications.

The medical complications occurring in 29 patients with neuromuscular spinal deformity undergoing two-stage anterior-posterior spinal fusion ("staged") were compared with 16 neuromuscular patients undergoing single-stage anterior-posterior spinal fusion ("same day"). Thirty-six (124%) major and minor medical complications occurred postoperatively in the staged patients, whereas 14 (88%) major or minor complication were present in same-day surgery patients. Thirty-five percent of staged patients had no complications, whereas 63% of same-day patients were without complications. Associated findings comparing the two-stage procedure to the single-stage surgery included operative and anesthesia time increase, increased blood-volume loss, increased blood transfusion, decreased nutritional parameters, and longer hospital stays. With either approach, there is the risk of significant complications in this vulnerable population.

Adolescent↗
PubMedDate not supplied

Graphic analysis of femoral growth in young children with Perthes' disease.

A cohort of 20 children, younger than 5.5 years at the time of onset of unilateral Perthes' disease, were studied by computer graphic analysis. Graphic outlines derived from each child's series of anterior posterior radiographs of the pelvis and hips were aligned on layers in a computer application such that changes over time could be directly visualized and measured. In these young children, injury to the cartilaginous growth mechanisms accounted for almost all of the abnormal change in the shape of the proximal femur; growth abnormalities had been established by the time of initial radiographs and persisted both as constant growth-rate change and growth-direction change until skeletal maturity. Despite the similar degree of radiographic bone necrosis, outcomes differed, and the specific growth aberrations were highly unique to the individual. At the time of the most recent radiographs, among the diseased hips 7 had spherical femoral heads larger than the normal side, eight had elliptical femoral heads congruent with the acetabulum, and five had elliptical femoral heads with a flat area congruent with the acetabulum. The study did not provide evidence to support a logic for brace or surgical treatment of young children with Perthes' disease.

Adolescent↗
PubMedDate not supplied

A mechanistic classification of closed, indirect fractures and dislocations of the lower cervical spine.

Closed, indirect fractures and dislocations of the lower cervical spine occur in families or groups within which there is a spectrum of anatomic damage to a cervical motion segment. This study of 165 cases demonstrates the various spectra of injury, called phylogenies, and develops a classification based on the mechanism of injury. The common groups are compressive flexion, vertical compression, distractive flexion, compressive extension, distractive extension, and lateral flexion. The probability of an associated neurologic lesion relates directly to the type and severity of cervical spine injury. With use of the classification, it is possible to formulate a rational treatment plan for injuries to the cervical spine.

Adolescent↗
PubMedDate not supplied

The Galveston technique of pelvic fixation with L-rod instrumentation of the spine.

From April 1978 to October 1982, the authors performed 44 pelvic fixations as part of L-rod instrumentation of a spinal deformity. Thirty scoliosis and revision scoliosis cases with a minimum of 1 year follow-up were analyzed for changes of the instrumentation with respect to the pelvis, angular changes at the lumbosacral junction, radiolucency about the portions of the rods providing pelvic fixation, and success of lumbosacral fusion. The technique for fixation was different among three groups of patients. A pelvic fixation technique in which the pelvic segments of the rods were longer than 6 cm, completely intraosseous through their iliac course, and within 1.5 cm of the sciatic notch, yielded the best results.

Adolescent↗
PubMedDate not supplied

A biomechanical study of thoracolumbar spinal fractures with bone in the canal. Part I. The effect of laminectomy.

A simulation of thoracolumbar spinal fractures with bone in the canal was performed using fresh cadaver spines. In the study, a hole was drilled anterior to posterior in vertebral body T12 to accommodate a microload cell and displacement transducer that was then manually pushed into the canal to simulate the compressive effect of retropulsed bone on the spinal cord. In this part of the study, measurements were made pre- and postlaminectomy. The results indicated that laminectomy had no decompressive effect with up to 35% occlusion of the canal. Measurements of dural wall deflection during penetration of the load cell indicated that the anterior wall deformed locally due to penetration of the load cell with minimal displacement of the posterior wall occurring.

Adult↗
PubMedDate not supplied

A biomechanical study of thoracolumbar spinal fractures with bone in the canal. Part II. The effect of flexion angulation, distraction, and shortening of the motion segment.

In the second part of this biomechanical study of thoracolumbar spinal fractures with bone in the neural canal contract force on the spinal cord--meningeal complex was measured with relation to varying fracture wedge depth, flexion angulations, and distraction and shortening of the fracture model motion segment. The removal of progressively deeper vertebral body wedges did not change the measured contact force/depth of penetration characteristics, however, the resistance to flexion angulation was decreased. Distraction of the motion segment an average of 5.2 mm increased significantly the contact force at the same depth of penetration compared with the case of normal vertebral body height. Shortening an average of 3.2 mm did not have a significant effect. Flexion angulation to 20 degrees did not change the depth/force characteristic in either the shortened or distracted case.

Adult↗
PubMedDate not supplied

Neurologic injuries with the Galveston technique of L-rod instrumentation for scoliosis.

A group of surgeons who used the Galveston technique for L-rod instrumentation (LRI) were surveyed to learn their experience with associated neurologic injuries. Among 507 LRIs for scoliosis there were two partial cord syndromes (0.4%), 13 "nerve root hyperesthesias" (2.6%), and two other nerve injuries (0.4%). All patients, except one with mild residuals after a partial cord injury, fully recovered from their neurologic problem. Experience in spinal surgery, education about LRI strategies and techniques, hands-on technical instruction, and use of an established process for LRI are believed to be the factors that enabled these surgeons to perform this complex procedure with relative safety.

Adolescent↗
PubMedDate not supplied

The immature goat as an animal model for Legg-Calvé-Perthes disease.

Legg-Calvé-Perthes disease (LCPD) results from avascular necrosis of the capital femoral epiphysis in growing children. This disease often yields a significant deformity of the proximal femur, which may result in osteoarthritis. Its cause is unknown, although extensive radiographic, clinical, and histologic evaluations have been performed. Attempts at developing an animal model for LCPD have been unsuccessful. Previous models have been based predominantly on determining the vascular etiology of the disease. There is a need for an animal model that mimics the growth pattern of the proximal femur seen in LCPD. Such a model would allow for the development and testing of new treatments. Thus far, no treatment strategy has been completely successful. A study involving graphic analysis of radiographs found that arrested anterolateral physeal growth with continued or accelerated perichondrial ring and posteromedial epiphyseal growth would account for the most severe morphologic changes observed in the femoral heads of patients with LCPD. A surgical procedure was performed to ablate the capital femoral physis in goat kids in an attempt to mimic the changes noted in this study. The procedure was evaluated with radiographs, gross specimens, and histopathologic slides. Graphic analysis of the radiographs revealed changes in the shape of the operated femoral head compared with the unoperated femoral head. While bone, fibrous, and fibrocartilaginous bridges were histologically observed across the physis, the resultant deformities did not mimic the changes identified in the graphic analysis study, perhaps because of inconsistencies in the surgical ablative techniques, which will require further modification. This study provides the basis for further research to develop a successful model.

Animals↗
PubMedDate not supplied

Growth profiles and articular cartilage characterization in a goat model of Legg-Calve-Perthes disease.

Numerous animal species, including the goat, have been evaluated as potential models for human Legg-Calve-Perthes disease (LCPD). These models disrupt the vasculature of the femoral head, causing it to collapse, and therefore do not mimic all the clinical patterns of the human disease. Baseline data regarding the weight and femoral length in the growing goat are not available. This study characterized the goat's normal growth for comparison with that of humans. The growth aberrations in the proximal femur created by surgically ablating the capital physis were described and compared with the aberrations observed in human LCPD cases. Age, weight, and femoral length (test and control) data were obtained for goats approximately 1 to 14 months of age. At 4 months of age, a craniolateral surgical approach was used to expose the cranial lateral capital physis so that it could be cauterized. Postoperative radiographs were evaluated by graphic analysis to assess the resultant changes in the morphology of the proximal femur. The articular cartilage of the femoral head and acetabulum was evaluated mechanically, using indentation testing, to determine the apparent modulus of elasticity, and histopathologically regarding its thickness and proteoglycan content. The proximal femurs of goats and humans exhibit similar morphology and growth patterns. There was a positive correlation between age, weight, and femoral lengths in the goat. The surgical procedure was effective in ablating the capital femoral physis as indicated by shorter femoral lengths and fragmented, flattened, and mushroomed femoral heads. The histopathological data revealed that the articular cartilage was significantly thicker in the operated hip joints at the ventrocaudal and cranial acetabula and the dorsal and ventral femoral heads. The test cartilage exhibited significantly less positive staining for proteoglycans in the dorsocaudal and the cranial acetabula as well as the ventral femoral head. The apparent modulus of elasticity, of the test cartilage was significantly lower than the control value at the dorsocaudal acetabulum. These data show that the surgical procedure produced morphological changes that mimic those in human LCPD. The increased thickness of the articular cartilage of the LCPD femoral head may account for the articular degeneration observed in older patients with LCPD, as increased cartilage thickness is associated with decreased tissue quality.

Animals↗
PubMedDate not supplied

Predictive value of intraoperative clubfoot radiographs on revision rates.

The predictive value of intraoperative radiographic assessment and its correlation with short term revision rates is presented for surgical correction of resistant clubfoot. Seventy-three children (115 feet) who underwent a primary procedure at one institution for idiopathic clubfoot between January 1991 and December 1994 were reviewed. A strategy using sequential release guided by intraoperative radiographs was employed in all cases. The intraoperative radiographic findings correlated with the need for early revision surgery, with residual radiographic evidence of cavus deformity associated with the greatest risk for revision. The sequential release strategy resulted in fewer overcorrections compared with historical controls of more complete subtalar release.

Analysis of Variance↗