Treatment of slipped capital femoral epiphysis with a spica cast.

Thirteen patients who had seventeen slipped capital femoral epiphyses were managed with a spica cast between 1984 and 1986. The average time in the plaster cast was three months. Complications were noted in fourteen of the hips. Three pressure sores developed in two patients. Further slipping developed in three hips once the cast had been removed, and chondrolysis developed in one of these hips. Chondrolysis developed in eight additional hips, and the lesion was transient in four of them. Degenerative changes developed in all nine hips with chondrolysis, regardless of whether the chondrolysis was transient or permanent. The degenerative changes were Iowa Grade I in three of these hips, Grade II in two hips, and Grade III in four. Chondrolysis developed in six of the eight black patients and in four of the five black boys. Chondrolysis developed in six of the nine hips that had a Grade-II or III slip. These findings have led us to abandon the use of a spica cast as a mode of treatment for slipped capital femoral epiphysis.

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.

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.

The biomechanics of decompressive laminectomy.

The biomechanical effect of laminectomy as a means of relieving compression of the spinal cord-meningeal complex by an anterior mass was studied in ten grossly normal human cadaver spines. The basic experimental set-up involved drilling a sagittal plane hole transversely across a vertebral body to provide direct access to the anterior aspect of the neural canal. After securing a probe and linearly variable differential transformer (LVDT) assembly at each site to be tested, the probe was gently pushed into the neural canal; contact force against the tip of the probe as well as the depth of probe penetration was measured and recorded. Laminectomy did not alter the resulting contact force/anterior penetration plots at the fifth cervical, seventh thoracic, 12th thoracic, or third lumbar vertebra. Using the probe/LVDT assembly to measure anterior dural displacement and a cantilever displacement device to measure posterior dural displacement after laminectomy at the 12th thoracic vertebra, the authors found that although the anterior dura underwent gross displacement as the probe was pushed into the neural canal, the posterior dura displaced to a minimal degree. The extent of the laminectomy was not a factor. The study did not demonstrate any possible mechanism by which laminectomy could reduce the pressure exerted on the dura and neural elements by an anterior mass in a spine with otherwise normal neural canal dimensions.

Biomechanical comparisons of spinal fracture models and the stabilizing effects of posterior instrumentations.

In this study, the authors evaluated the stiffness of motion segments in intact spines in two spine fracture models, and with each of five implant systems used for posterior fixation of thoracolumbar spine fractures. The devices represented a cross-section of types, including those employing sublaminar wires with and without laminar hooks, pedicle screws, plates, and rods. Two spine fracture models, one partially and one totally destabilized, were used in the tests of the instrumentation. Stiffness, or the magnitude of load needed to produce a unit displacement of the construct in the direction of the applied load, was measured in flexion, extension, lateral bending, and torsion in combination with a compressive force. Both horizontal plane shear and angular displacements were measured in the two fracture patterns. All evaluations were made by testing the difference in stiffness for statistical significance among groups. The results showed significant differences in stiffness without instrumentation among intact spines, partly destabilized spines (anterior two-thirds of disk and posterior ligaments removed), and totally destabilized spines (only anterior longitudinal ligament intact). The implant/spine constructs were least stiff relative to the intact spine in torsion, followed in increasing order of stiffness with flexion, lateral bending, and extension. In the Roy-Camille plate with six-screw fixation was found to produce the stiffest construct, followed by wired Harrington rods, C-rods and J-rods, and the Vermont internal fixator.(ABSTRACT TRUNCATED AT 250 WORDS)

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.

A biomechanical study of thoracolumbar spine fractures with bone in the canal. Part III. Mechanical properties of the dura and its tethering ligaments.

Experiments were performed to determine some mechanical properties of the spinal cord-meningeal (SCM) complex and its tethering elements with reference to factors contributing to contact pressure of an anterior mass on the SCM complex with spinal fracture and the development of some means to relieve the pressure. Measurements were made using a combined microload cell and displacement transducer that was passed posteriorly through a hole drilled in vertebra T12 through the interpedicular space and contacted the cord. Loss of nerve roots and anterior ligaments as dural tethers in the lumbar region permitted the SCM complex to fall out of the lordosis of the canal and fail to resist transverse loading. Head and neck flexion increased contact force for a given depth of penetration, particularly in the cervical region. This was consistent with measurements of strain along the dura that was greatest in the cervical region. The dura was found to be elastic, having a failure strain averaging 34% but was uniform in thickness, stiffness, and elastic modulus along its length. The study did not delineate any surgical manipulation other than removal of the anterior mass that would be beneficial when there is anterior compression of the spinal cord.

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.

Rib regeneration area as an indicator of fusion area in adolescent idiopathic scoliosis.

This retrospective study of 24 patients with adolescent idiopathic scoliosis who underwent L-rod instrumentation, posterior thoracoplasty, and rib-bone grafting analyzed the correlation between the quality of rib regeneration and the host response to the rib-bone grafts. A planimetric technique was used to quantitate the coronal plane area of the resected ribs and of an L1-L2 concave fusion area immediately after surgery and at the end of the first postsurgical year. Using computerized regression analysis, these and other variables such as age, Cobb angle, and grafting technique were studied. Rib regeneration correlated with spinal fusion but not with age or Cobb angle. A better host response with strip vs. morseled graft was suggested, but not statistically proven. The data strongly support the belief that systemic biologic factors are a major variable affecting the quality of the fusion procedure.

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.

Topics of interest in pediatric orthopedics.

This two-in-one article presents an overview of septic arthritis of the hip and school screening for adolescent idiopathic scoliosis--two problems commonly shared by the pediatrician and the pediatric orthopedic surgeon. The importance of aggressive diagnostic measures and treatment for the septic hip is emphasized and the basis for the rationale is given. In the section on scoliosis, the reader is introduced to the "scoliometer," and a rationale for management of most of these children by the primary physician is given.

An algorithm for the treatment of unstable thoracolumbar fractures.

This article describes a fracture classification used at the University of Texas Medical Branch that takes into account the fracture mechanics and attempts to match the requirements of the fracture to the strong points of a particular spinal implant. The present algorithm for the treatment of thoracolumbar fractures is presented, and its efficacy is demonstrated by comparing it with an evolutionary group of spinal fractures cases

A 1988 perspective on the Galveston technique of pelvic fixation.

The Galveston technique for pelvic fixation was used in 40 patients who underwent scoliosis surgery with pelvic fixation at The University of Texas Medical Branch from February 1980 through June 1987. Analysis of the outcomes indicates that extension of a scoliosis fusion to the pelvis can be undertaken with excellent chance for success and without the necessity of routine postsurgical casting or bracing. Accurate contouring of the L-rod implant and meticulous fusion technique are essential to success.

Considerations in the treatment of cerebral palsy patients with spinal deformities.

The natural history of spinal deformities in the cerebral palsy patient is different than that in the idiopathic patient. Consequently, the approach to the patient with cerebral palsy and the surgical decision-making are different from that in the idiopathic patient. The present article gives the UTMB approach to the treatment of the cerebral palsy patient and the unique considerations that must be taken into account when treating these patients. Specific references are made to the use of L-rod instrumentation to stabilize the spinal deformity in the cerebral palsy patient.

A modified Harrington technique for scoliosis.

Post-Harrington techniques for adolescent idiopathic scoliosis have increased the complexity of scoliosis surgery while contributing only biomechanically more secure fixation and sagittal contour preservation. On the the basis of principles defined by Harrington, the authors developed a simplified technique that accomplishes equivalent outcomes.

Distraction instrumentation outcomes in scoliosis.

The short-term outcomes of a new distraction technique using a small rod spinal instrumentation system (WRIGHTLOCK) are reported for adolescent idiopathic scoliosis. No caudally directed thoracic hooks were used. Seventy-four children aged 11.7 to 17.5 years who underwent consecutive posterior instrumentations are reviewed. Their curves improved from a mean of 55.6 degrees to 22.7 degrees (average of 59.2% correction). At 2.7 years mean follow-up, coronal curves lost an average of 4.2 degrees correction. Overall, there was a mean increase of 4.4 degrees in kyphosis. Children with the most preoperative hypokyphosis were afforded the greatest gains in kyphosis. Instrumentation resulted in a mean loss of 8.2 degrees lumbar lordosis. These results compare favorably with published results for other multihook systems.