Spinal epidural hemangioma related to pregnancy.

We report the case of a 39-year-old woman with adolescent idiopathic scoliosis presenting with myelopathy secondary to a spinal epidural hemangioma. MRI showed an epidural soft tissue mass within the spinal canal between T5 and T9 with severe spinal cord compression. Symptoms had a temporal relationship to her pregnancy. Surgical removal of the epidural hemangioma rapidly relieved her symptoms and neurologic deficits. Follow-up examination 2 years later demonstrated normal motor and sensory function, without any neurologic sequelae or progression of deformity.

Surgical treatment of adolescent idiopathic scoliosis: a comparative study of two segmental instrumentation systems.

This study compares two different surgical techniques and instrumentation types in the treatment of adolescent idiopathic scoliosis. The charts and radiographs of 116 patients with adolescent idiopathic scoliosis treated by posterior spine fusion with Isola or Cotrel-Dubousset instrumentation were reviewed. Patients were separated into two equivalent groups matched for age, sex, curve type, and curve magnitude. All patients had a minimum of 2 years follow-up. The instrumentation in group 1 consisted of hooks, wires, and pedicle screws. That used in group 2 was limited to hooks and rods. The Mann-Whitney, Wilcoxin, and the paired Student t tests for matched pairs were used for statistical analysis. Patients in group 1 had increased curve correction (66% vs. 52%), apical vertebral translation (63% vs. 30%), and correction of the end vertebral tilt angle (11 degrees vs. 3 degrees) (p < 0.001). The percentage of coronal curve correction in curves larger than 65 degrees also was greater in group 1 (59% vs. 40%). Physiologic sagittal alignment was obtained in 80% of the patients in group 1 and 25% in group 2. No major complication or pseudoarthrosis occurred in either group. This study supports improved correction of curve magnitude, apical translation, and end vertebral tilt angle with the use of multiple anchor types compared with the correction achieved with standard hook-and-rod constructs.

Safety of sublaminar wires with Isola instrumentation for the treatment of idiopathic scoliosis.

STUDY DESIGN: To investigate the incidence of acute neurologic complications of use of sublaminar wires with third-generation spine instrumentation for the treatment of idiopathic scoliosis. OBJECTIVES: To assess the safety of sublaminar wires in the surgical treatment of idiopathic scoliosis. SUMMARY OF BACKGROUND DATA: The use of sublaminar wires in spine deformity for neuromuscular scoliosis and the Luque system has been reported. Use of sublaminar wires is an integral part of the technique in the surgical treatment of spine deformity with Isola instrumentation (AcroMed, Cleveland, OH). To date, the safety of this technique has not been documented. METHODS: The average age of the patients was 37 years (range, 11-74 years). Preoperative diagnosis was adolescent idiopathic scoliosis in 75 patients and adult idiopathic scoliosis in 66. One hundred nine were primary surgeries, and 32 were revision. Detailed evaluation of the curve type, curve magnitude, number of vertebrae instrumented, level of vertebrae wired, postoperative neurologic deficit, and the findings of intraoperative spinal cord monitoring was performed. Wires were always passed just before corrective maneuvers were performed. RESULTS: A total of 1366 wires were placed, 65% (n = 888) in the thoracic region, 22% (n = 300) in the thoracolumbar, and 13% (n = 178) in the lumbar. No permanent change in intraoperative spinal cord monitoring was detected. Stagnara wake-up test was performed in all patients. No patient with adolescent idiopathic scoliosis had neurologic complication. Two adults underwent revision surgery and had transient dysesthesia in the leg, which completely resolved with observation. CONCLUSION: Despite the increasing complexity of spinal instrumentation systems, sublaminar wire placement is a safe and useful adjunct in the surgical treatment of neurologically intact patients with idiopathic scoliosis.

Safety and efficacy of pedicle screw placement for adult spinal deformity with a pedicle-probing conventional anatomic technique.

A prospective study of 50 adults treated with fusion, realignment, and segmental spinal instrumentation for spinal deformity was conducted to assess the safety, accuracy, and efficacy of the free-hand pedicle screw placement technique. Postoperative computed tomographic scans were performed to evaluate the placement of 282 screws and were correlated with patients' clinical outcomes. Five screws were placed at T12, 26 at L1, 39 at L2, 48 at L3, 73 at L4, 35 at L5, and 50 at S1. Nine screws (3%) were misplaced and included three screws (1.06%) that violated the medial wall with no clinical sequelae or revision surgery needed. There were no neurologic deficits related to screw placement. The free-hand technique is a safe and cost-effective method for pedicular screw placement during surgery for adult spine deformities.

Streaming potential of human lumbar anulus fibrosus is anisotropic and affected by disc degeneration.

The streaming potential responses of non-degenerate and degenerate human anulus fibrosus were measured in a one-dimensional permeation configuration under static and dynamic loading conditions. The goal of this study was to investigate the influence of the changes in tissue structure and composition on the electrokinetic behavior of intervertebral disc tissues. It was found that the static streaming potential of the anulus fibrosus depended on the degenerative grade of the discs (p = 0.0001) and on the specimen orientation in which the fluid flows (p = 0.0001). For a statically applied pressure of 0.07 MPa, the ratio of streaming potential to applied pressure ranged from 5.3 to 6.9 mV/MPa and was largest for Grade I tissue with axial orientation and lowest for Grade III tissue with circumferential orientation. The dynamic streaming potential responses of anulus fibrosus were sensitive to the degeneration of the disc: the total harmonic distortion factor increased by 108%, from 3.92 +/- 0.66% (mean +/- SD) for Grade I specimens to 8.15 +/- 3.05% for Grades II and III specimens. The alteration of streaming potential reflects the changes in tissue composition and structure with degeneration. To our knowledge, this is the first reported data for the streaming potential of human intervertebral disc tissues. Knowledge of the streaming potential response of the intervertebral disc provides an understanding of potentially important signal transduction mechanisms in the disc and of the etiology of intervertebral disc degeneration.

The anisotropic hydraulic permeability of human lumbar anulus fibrosus. Influence of age, degeneration, direction, and water content.

STUDY DESIGN: Experimental investigation to determine the effect of intervertebral disc degeneration on the kinetic behavior of fluid in human anulus fibrosus. OBJECTIVES: To measure the hydraulic permeability coefficient of anulus fibrosus specimens in the axial, circumferential, and radial directions to determine the anisotropic permeability behavior of nondegenerate and degenerate human intervertebral discs over a range of ages. SUMMARY OF BACKGROUND DATA: Fluid, a major component of normal intervertebral discs, plays a significant role in their load-supporting mechanisms. Transport of fluid through the intervertebral disc is important for cell nutrition and disc viscoelastic and swelling behaviors. The hydraulic permeability coefficient is the most important material property governing the rate of fluid transport. However, little is known about the anisotropic behavior of this kinetic property and how it is influenced by disc degeneration. METHODS: Using a permeation testing apparatus developed recently, testing was performed on 306 axial, circumferential, and radial anulus fibrosus specimens from the posterolateral region of 30 human lumbar (L2-L3) discs. A new method, flow-controlled testing protocol, was developed to measure the hydraulic permeability coefficient. RESULTS: The hydraulic permeability coefficient of anulus fibrosus depended significantly on the disc degenerative grade (P = 0.0001) and flow direction (P = 0.0001). For the nondegenerate group (Grade I), the hydraulic permeability was significantly anisotropic (P < 0.05), with the greatest value in the radial direction (1.924 x 10(-15) m4/Ns) and the lowest value in the circumferential direction (1.147 x 10(-15) m4/Ns). This anisotropic kinetic (flow) behavior of anulus fibrosus varied with disc degeneration. For the Grade III specimen group, there was no significant difference in hydraulic permeability coefficient among the three major directions (P = 0.37). With disc degeneration, the hydraulic permeability coefficient was decreased in the radial direction and increased in the axial and circumferential directions. The variations of hydraulic permeability coefficient from nondegenerate discs (Grade I) to mildly degenerate discs (Grade II) in each direction were significant (P < 0.05). However, the changes in permeability from Grade II to Grade III groups were not significant (P > 0.05) except in the circumferential direction (3.8% increase; P < 0.05). CONCLUSIONS: The hydraulic permeability of human nondegenerate anulus fibrosus is direction-dependent (i.e., anisotropic), with the greatest permeability in the radial direction. With disc degeneration, the radial permeability of anulus fibrosus decreases, mainly because of decreased water content, and the axial and circumferential permeability coefficients increase, mainly because of structural change, leading to more isotropic permeability behavior for Grade III discs.

Degeneration affects the anisotropic and nonlinear behaviors of human anulus fibrosus in compression.

Axial and radial specimens of non-degenerate and degenerate human anulus fibrosus (AF) were tested in confined compression to test the hypothesis that degeneration significantly affects the compressive properties of AF. Due to the highly oriented structure of AF, a secondary objective was to investigate anisotropic behaviors of AF in compression. Uniaxial swelling and stress relaxation experiments were performed on site-matched samples of anulus from the anterior outer region of L2-3 intervertebral discs. The experimental stress-relaxation behavior was modeled using the finite deformation biphasic theory and a finite-difference approximation scheme. Significant effects of degeneration but not orientation were detected for the reference stress offset, sigma(offset), and parameters describing the compressive stiffness (i.e. reference aggregate modulus, H(A0), and nonlinear stiffening coefficient, beta). Average values were 0.13+/-0.06 and 0.05+/-0.05 MPa for sigma(offset), 0.56+/-0.21 and 1.10+/-0.53 MPa for H(A0) and 2.13+/-1.48 and 0.44+/-0.61 for beta for all normal and degenerate specimens, respectively. No significant effect of degeneration or orientation were detected for either of the parameters describing the strain-dependent permeability (i.e. reference permeability, k0 and strain-dependent permeability coefficient, M) with average values for all specimens of 0.20+/-0.10 x 10(-15) m4/N-s and 1.18+/-1.30 for k0 and M, respectively. The loss of sigma(offset) was compensated with an elastic stiffening and change in the shape of the equilibrium stress-strain curve with H(A0) for degenerate tissues almost twice that of normal tissues and beta less than one sixth. The increase in reference elastic modulus with degeneration is likely related to an increase in tissue density resulting from the loss of water content. The significant effects of degeneration reported in this study suggested a shift in load carriage from fluid pressurization and swelling pressure to deformation of the solid matrix of the AF. The results also suggest that the highly organized and layered network of the anulus fibrosus, which gives rise to significant anisotropic effects in tension, does not play a major role in contributing to the magnitude of compressive stiffness or the mechanisms of fluid flow of the anulus in the confined compression configuration.

Rheumatoid arthritis of the cervical spine.

Rheumatoid arthritis most often affects the cervical spine, resulting in clinical and radiographic findings. For most patients with rheumatoid arthritis the cervical involvement represents a relatively benign process, but, in a small percentage of these patients, a progressive instability pattern develops that may compromise neural or vascular structures. The rate of neural compromise because of cervical instability ranges from 11% to 58%. The clinical manifestation may be radiculopathy, myelopathy, quadriplegia, and, in extreme instances, sudden death.

Reconstructive spine surgery in pediatric patients with major loss in vital capacity.

Thirty-two pediatric patients with severe restrictive lung disease identified with vital capacities < 40% of predicted, who had undergone major reconstructive spine surgery, were reviewed. There were 18 boys and 14 girls, the mean age was 13 years (range, 7-17), and the mean vital capacity was 31% of predicted (range, 16-39%). Fifty-four procedures were performed, 13 posterior only, one of which was staged, and 19 anterior and posterior procedures, of which 15 were staged and four were sequential. The incidence of pulmonary complications (pneumonia, reintubation, pneumothorax, respiratory arrest, or the need for tracheostomy) was 19% (six patients), and only three patients required tracheostomy. The surgical and perioperative mortality rate was zero. Patients who had a thoracotomy or a thoracoabdominal approach had a significantly higher number of pulmonary complications. The use of preoperative decreased vital capacity as a measure of inoperability excludes the young patient most in need of surgical intervention. With improved preoperative, intraoperative, and postoperative techniques, careful monitoring, and the cooperation of pediatric pulmonologists and intensivists, reconstructive spine surgery can be performed in the pediatric patient with severe decreased vital capacity with very acceptable morbidity and mortality.

A biomechanical study of torque and accuracy of halo pin insertional devices.

The purpose of the present study was to assess the accuracy and repeatability of the torque achieved with a variety of devices used for the insertion of halo pins. We found that equivalent devices from the same manufacturer did not reliably achieve the same torque, that the same device used by different surgeons did not reliably achieve the same torque, and that the devices achieved varying levels of accuracy and repeatability. The proportion of trials in which the achieved torque was within +/- 10 per cent of the intended torque averaged 64 per cent (range, less than 1 to 100 per cent). Our data suggest that the insertion of halo pins with use of most currently available torque-setting devices is an inherently inaccurate process.

Technique and results of fixation to the sacrum with iliosacral screws.

This article describes the technique of iliosacral screw fixation, as well as a retrospective review of 28 consecutive patients who had spine fusion to the sacrum with iliosacral screws, with a minimum follow-up of 2 years. The study included 6 male and 22 female patients. Average age at the time of surgery was 43 years, and mean follow-up time was 3.5 years. There were no neurologic complications at final follow-up evaluation. Ninety-five percent of the patients had radiographic evidence of fusion. Three patients required iliosacral screw removal because of suboptimal intraoperative Kirschner-wire placement. Optimal intraoperative radiographic evaluation for accurate iliosacral screw placement is recommended. The use of iliosacral screws is also a useful addition to the armamentarium of the spine surgeon when fixation to the sacrum is required.

Epidural compression in the spinal canal caused by excessive adipose tissue. A case report.

Excessive deposition of fat in the epidural space is rare. In a recent review of the literature, there were 15 reported cases, 14 were associated with steroid use and one was attributed to hypothyroidism. This report reviews treatment of a patient with symptoms of cauda equina compression caused by epidural adipose tissue. He had no history of steroid use or obvious evidence of an underlying endocrinopathy.

The iliotibial band lateral sling procedure and its effect on the results of anterior cruciate ligament reconstruction.

The effect of iliotibial band "lateral sling" augmentation on long-term outcome in ACL reconstruction using free autogenous central-third patellar tendon was evaluated retrospectively. Eighty reconstructions were reviewed; the minimum followup was 2 years and the average was 4 years. Sixty percent of the procedures involved supplementation with a lateral sling. By both clinical evaluation and KT-1000 measurement, there were no differences in the results of patients with lateral sling augmentation and those without it. In addition, 40% of patients had chronic pain and/or swelling related to the lateral sling. We do not currently recommend the routine use of a lateral sling augmentation for ACL reconstruction using central-third patellar tendon.

Effect of modern cement technique on acetabular fixation total hip arthroplasty. A retrospective study in matched pairs.

The modern cement technique has significantly reduced the bone-cement interface radiolucency and, therefore, it is suggested that the results of the cemented socket with this technique should be the basis for comparison with other methods of fixation.