Transpedicular eggshell osteotomies for congenital scoliosis using frameless stereotactic guidance.

STUDY DESIGN: Three cases of multiplanar congenital scoliosis corrected by a transpedicular eggshell osteotomy using frameless stereotactic guidance are reported. OBJECTIVE: To show an alternative surgical technique for correcting and fusing complex congenital spinal curves. SUMMARY OF BACKGROUND DATA: Children with congenital scoliosis can have progressive curves causing significant multiplanar deformities. In older children, traditional approaches to spinal corrective surgery including fusion in situ, convex growth arrest, and hemivertebra excision can achieve only limited corrections. METHODS: Three older patients who had congenital scoliosis with significant multiplanar curves underwent one-stage posterior transpedicular eggshell osteotomy. Three-dimensional reconstructive images and frameless stereotactic guidance were used for preoperative selection of osteotomy levels and accurate placement of pedicle screws. After completion of the osteotomy, closure was obtained with extension of the hips. RESULTS: The average coronal correction of the major curve was 28.7 degrees (range, 22-33 degrees ). The average correction of the plumb line or lateral displacement from the center of the trunk was 4.8 cm (range, 3-7.5 cm). A significant kyphotic deformity was corrected 38 degrees, and a pelvic tilt was reduced from 7 to 3 cm. CONCLUSIONS: One-stage posterior reduction eggshell osteotomy can be used to correct a sagittal and/or coronal congenital spinal curve imbalance. Frameless stereotactic guidance for solid pedicle screw fixation was essential to the achievement of rigid spinal stabilization before arthrodesis. Transpedicular eggshell osteotomy is a technique that should be considered for older patients who have congenital scoliosis with multiplanar spinal abnormalities.

The use of traction methods to correct severe cervical deformity in rheumatoid arthritis patients: a report of five cases.

STUDY DESIGN: A case series is presented. OBJECTIVES: To describe the methods of correction used in this study for flexible severe cervical deformity, and to report the results in patients with rheumatoid arthritis. SUMMARY OF BACKGROUND DATA: Long-standing rheumatoid arthritis can lead to severe cervical deformity, causing significant functional deficits and poor cosmesis. Information on the use of traction combined with surgical stabilization to achieve correction of flexible deformity in rheumatoid patients is sparse in the English literature. METHODS: A review of five cases, including pertinent history, physical examination, radiographic evaluation, traction techniques, surgical stabilization, and outcomes, was conducted. RESULTS: Excellent correction of deformity and radiographic union were achieved in all the patients. One patient had minimal loss of correction after surgery and thereafter remained stable. Pin tract infections were the only significant complication. CONCLUSIONS: Severe cervical flexible deformity in rheumatoid patients can cause significant disability and can be treated successfully with a combination of traction techniques and surgical stabilization.

Remifentanil- and fentanyl-based anesthesia for intraoperative monitoring of somatosensory evoked potentials.

We sought to compare effects of remifentanil- and fentanyl-based anesthesia on the morphology of somatosensory evoked potentials (SSEPs) and speed of recovery from anesthesia. Forty-one patients undergoing spinal surgery and requiring intraoperative monitoring of SSEPs were randomized into two groups. In Group 1, anesthesia was induced with sodium thiopental and maintained with fentanyl, 50% nitrous oxide in oxygen, and 0.5%--0.75% isoflurane. In Group 2, anesthesia was induced with sodium thiopental and maintained with remifentanil, 50% oxygen in air, and 0.5%--0.75% isoflurane. The variables compared included hemodynamic changes during the induction and intubation, the interval from the end of anesthesia to extubation, intraoperative blood loss and fluid administration, and changes in latency and amplitude of the P37--N45 component of posterior tibial nerve somatosensory evoked potentials and the N20--P24 component of median nerve somatosensory evoked potentials. The two groups were matched for demographics, ASA physical status, and duration of surgery. Hemodynamic profiles after the induction and intubation were similar. There were significant differences between groups in time intervals from the end of anesthesia to extubation (15.3 +/- 12.8 vs 5.3 +/- 2.3 min; P = 0.0001) and ability to follow verbal commands (14.6 +/- 11.9 vs 4.5 +/- 2.4 min; P = 0.0001), with the Remifentanil group showing earlier recovery. Variability (coefficient of variation) of P37--N45 latency was greater (0.026 vs 0.014; P = 0.001) in the Fentanyl group.

Efficacy of the laparoscopic approach for anterior lumbar spinal fusion.

BACKGROUND: This study compares the immediate postoperative outcomes in patients who undergo laparoscopic and open anterior lumbar spinal fusion and describes the learning curve associated with the performance of this procedure. METHODS: The charts of patients who underwent anterior lumbar spinal fusion between January 1995 and July 1999 were reviewed. Data pertaining to the operation and postoperative course were analyzed and compared. RESULTS: Eighty-nine patients underwent anterior lumbar spinal fusion. Fourteen patients were excluded; a full analysis was performed on the records of the remaining 75 patients. Fifty-five patients underwent an attempted laparoscopic procedure, and 20 patients underwent an open procedure. The conversion rate was 38% (21/55 patients) in the group who underwent the laparoscopic procedure. In the 34 patients whose laparoscopic procedure was completed, there was significantly less blood loss and shorter postoperative ileus, but the operative time was longer, when compared with patients who underwent the open procedure. The laparoscopic procedures performed in 1999 resulted in fewer conversions, less blood loss, and a shorter operating room time, when compared with the laparoscopic procedures in 1998. CONCLUSIONS: Laparoscopic anterior lumbar spinal fusion improves immediate postoperative results when compared with open anterior lumbar spinal fusion.

Restoration of pedicle screw fixation with an in situ setting calcium phosphate cement.

STUDY DESIGN: Pedicle screws were pulled out of human cadaveric vertebrae before and after augmentation with polymethylmethacrylate or in situ-setting calcium phosphate cement. The fixation strength of screws augmented with calcium phosphate cement was compared with that of screws augmented with polymethylmethacrylate. OBJECTIVES: To determine whether a new in situ-setting calcium phosphate cement might be suitable for augmenting the fixation of pedicle screws. The principle objective was to compare the pull-out resistance of screws augmented with calcium phosphate cement with the pull-out behavior of screws augmented with polymethylmethacrylate. Polymethylmethacrylate augmentation was chosen as the standard because of its current clinical use. Five types of screws were tested to determine whether screw design had an effect on the efficacy of augmentation. SUMMARY OF BACKGROUND DATA: Although many factors affect the pull-out resistance of pedicle screws, a key determinant of their performance is the strength of their attachment to the spine. In elderly, osteopenic patients, the screw-bone interface is especially at risk for stripping during insertion or pull-out after surgery. In these patients, polymethylmethacrylate has been used to augment pedicle screw fixation, although its use is not without risk. In situ-setting calcium phosphate cements may provide an alternative to polymethylmethacrylate in this application. Like polymethylmethacrylate, calcium phosphate cements can be injected into the prepared screw hole. They have the added advantage of being resorbed and replaced during healing and normal bone remodeling. METHODS: Thirty human lower lumbar vertebrae (L3-L5) were implanted bilaterally with one of five types of pedicle screws (n = 6 for each screw type). The screws were pulled out 3.0 mm at 0.25 mm/sec with a servohydraulic materials testing machine. The 3.0-mm pull-out distance, which was slightly longer than one thread pitch, was designed to strip the screw-bone interface but to leave the pedicle otherwise intact. After the initial testing, the screws in each vertebrae were removed, and the screw tracks were filled with 2.0 cc of polymethylmethacrylate (one side) or calcium phosphate cement (contralateral side). After augmentation, the screws were reinserted, and the cements were allowed to harden for 24 hours. Postaugmentation testing followed the protocols for preaugmentation testing, and the pull-out resistance of screws augmented with calcium phosphate cement was compared with the pull-out resistance of screws augmented with polymethylmethacrylate. RESULTS: Mechanically, calcium phosphate cement compared favorably with polymethylmethacrylate for augmenting pedicle screws. Both restored the strength of the screw-bone interface: across all screw types, the average increase in pull-out strength was 147% with polymethylmethacrylate augmentation and 102% with calcium phosphate cement. There were no significant differences because of screw type with either type of augmentation. CONCLUSIONS: The in situ-setting calcium phosphate cement investigated in this study compared favorably with polymethylmethacrylate in a single-cycle, pull-out test of augmented pedicle screws in senile trabecular bone. With further evaluation, this cement may offer an alternative to polymethylmethacrylate for the enhancement of pedicle screw fixation clinically.

The role of pediculolaminar fixation in compromised pedicle bone.

STUDY DESIGN: This in vitro study analyzed the effects of a supralaminar hook on pedicle screw fixation in compromised pedicle bone. OBJECTIVES: To determine the ability of pediculolaminar fixation to restore pedicle screw pull-out strength after stripping of senile pedicle bone. SUMMARY OF BACKGROUND DATA: Despite improvements in pedicle screw design, the bone-screw interface remains the "weakest link" in pedicle screw fixation. This interface is especially vulnerable in osteoporotic bone previously instrumented pedicles, and at the ends of long instrumentation constructs. METHODS: Side-to-side testing between a pedicle screw and a pedicle screw supplemented with a supralaminar hook (pediculolaminar fixation) was performed in human cadaveric lumbar vertebrae. Comparisons were made for intact and compromised pedicle bone. RESULTS: Pediculolaminar fixation restored 89% of intact pedicle screw pull-out strength whereas the pedicle screw alone restored only 19% of intact pull-out strength. The role of pediculolaminar fixation was greatest in weaker bone. Significant differences were noted in energy to failure and post-failure energy. In intact bone, the pediculolaminar construct did not increase pull-out strength or energy to failure, although it did have a greater post-failure energy. CONCLUSIONS: Pediculolaminar fixation can augment pedicle screw fixation in pedicle bone compromised by previous stripping or significant osteoporosis or both.

A pilot study of the effects of a perflubron emulsion, AF 0104, on mixed venous oxygen tension in anesthetized surgical patients.

A pilot study of a perfluorochemical (PFC) emulsion was undertaken to determine whether administration of a perflubron emulsion could result in measurable changes in mixed venous oxygen tension. Seven adult surgical patients received a 0.9-g PFC/kg intravenous dose of perflubron emulsion after acute normovolemic hemodilution (ANH). Hemodynamic and oxygen transport data were collected before and after ANH, immediately after PFC infusion, and at approximate 15-min intervals throughout the surgical period. There were no clinically significant hemodynamic changes associated with the administration of the PFC emulsion. There was a significant increase in mixed venous oxygen tension (PVO2) after the PFC infusion, while cardiac output and oxygen consumption were unchanged. As surgery progressed, the hemoglobin concentration decreased with ongoing blood loss while PVO2 values remained at or above predosing levels. Peak perflubron blood levels were 0.8 g/dL immediately postinfusion, and approximately 0.3 g/dL at 1 h. This pilot study demonstrates that administration of perflubron emulsion results in measurable changes in mixed venous oxygen tension during intraoperative ANH.

The sagittal alignment of the cervical spine in adolescent idiopathic scoliosis.

To assess the sagittal orientation of the cervical and thoracolumbar spine, 38 adolescents with idiopathic scoliosis were studied. The C7 plumb line and Cobb angles from C2-6, T1-12, and L1-S1 were measured on preoperative films. Lateral radiographs with > 1-year follow-up after surgical correction were available for the same measurements in 28 patients. The preoperative curve from C2-6 was 6 +/- 11 degrees of kyphosis. There was a significant correlation between the loss of thoracic kyphosis and the development of cervical kyphosis for the entire group preoperatively (p = 0.009). Postoperatively, cervical kyphosis increased to 11 +/- 9 degrees at 1-year follow-up (p = 0.05). There was no progression of cervical kyphosis in patients with "thoracic hypokyphosis" (kyphosis < 20 degrees). Cervical kyphosis increased in patients with "normal" thoracic kyphosis (20-40 degrees) and in patients with hyperkyphosis (kyphosis > 40 degrees) after surgery, despite preservation of thoracolumbar sagittal contour. There were no significant differences between the sagittal contour of patients treated with Cotrel-Dubousset or Harrington instrumentation.

A comparison study of treatment of thoracolumbar fractures using the ACE Posterior Segmental Fixator and Cotrel-Dubousset instrumentation.

The results of 26 consecutive thoracolumbar fractures treated with Cotrel-Dubousset instrumentation (CDI) (n = 12) or the ACE Posterior Segmental Fixator (n = 14) with a mean follow up of 20.2 months were analyzed. Preoperatively, no statistically significant difference was noted between the two treatment groups. Postoperatively, no statistically significant difference was noted for improvement of kyphosis (mean: -6.00 degrees ACE, 1.92 degrees CDI), vertebral body height (mean: 17.86% ACE, 18.83% CDI), vertebral body angle (mean: -6.21 degrees ACE, -5.42 degrees CDI), or estimated blood loss (mean: 1544 cc ACE, 1620 cc CDI). All patients with incomplete paraplegia improved by at least one Frankel grade. Statistically significant differences were noted in operative time (mean: 269 minutes ACE, 357 minutes CDI, P < .0005), and in the number of instrumented levels (mean: 3 ACE, 5.8 CDI). All patients exhibited solid fusion radiographically. Thoracolumbar fractures can be effectively treated by either CDI or the ACE Fixator. The ACE Fixator has the advantage of sparing motion segments and decreased operative time.

Acute spondylolytic spondylolisthesis. Risk of progression and neurological complications.

Acute spondylolytic spondylolisthesis was diagnosed after major trauma in five patients. The level of injury was between the third and fourth lumbar vertebrae in one patient and between the fifth lumbar and first sacral vertebrae in four. The initial spondylolisthesis was grade I in four patients and grade III in one. Four of the patients were initially managed non-operatively. The deformity did not progress in a five-year-old boy with grade-I spondylolisthesis who had been managed with immobilization in a body cast. The deformity progressed in two of the adolescents who had been managed non-operatively; the progression was from grade I to grade III in one of these patients and from grade III to grade V (spondyloptosis) in the other, in whom a cauda equina syndrome also developed. The latter patient was subsequently managed with posterior reduction and arthrodesis followed by an anterior arthrodesis, and the neurological deficits resolved. The deformity also progressed, from grade I to grade II over three years, in a fifty-seven-year-old woman who had been managed non-operatively. One patient who had a grade-I deformity was managed with immediate operative stabilization followed by immobilization in a thoracolumbosacral orthosis; the deformity did not progress. Although minor or repetitive trauma is often associated with spondylolysis, high-energy trauma may produce a more severe form of spondylolysis with spondylolisthesis. These deformities are more unstable, with instability similar to that of a fracture-dislocation, and they have a greater propensity to progress than the usual form of spondylolytic spondylolisthesis.(ABSTRACT TRUNCATED AT 250 WORDS)

Failed back surgeries and minnesota multiphasic personality inventory (MMPI) profiles.

MMPI profiles were evaluated for 105 prospective surgical patients who had previously undergone surgery or other procedures for treatment of back pain. Patients were classified into groups having undergone zero, one, two, three, or four or more previous surgeries. While all groups demonstrated a characteristicsomatogenic profile, none of the MMPI validity or clinical scales significantly differentiated the groups and there was no relationship between increased number of surgeries and MMPI scale characteristics. These results support the nonoptimistic prognostication of thesomatogenic MMPI profile for surgical intervention for back pain but show no clear relationship of MMPI profile characteristics to degree of experience of previously failed surgery.

Cotrel-Dubousset hook and screw combination for spine fractures.

A review of 14 patients treated for spinal fracture using lumbar pedicle screw and thoracic pediculotransverse claw "hybrid" Cotrel-Dubousset fixation was performed. Pedicle screw fixation was used one level below the most inferiorly injured vertebrae. Pediculotransverse claw constructs were used for thoracic level fixation three segments above the superior injured vertebrae. Fractures were classified as burst (n = 9), burst dislocation (n = 3), and thoracic facet dislocation (n = 2). Complications included one patient who increased his kyphosis postoperatively before stabilizing at 3 months and one patient with a single screw breakage noted at 1 year. Both patients are asymptomatic. Early results demonstrate that this hybrid pedicle screw and pediculotransverse claw fixation is a satisfactory alternative to other posterior distraction methods. The use of the claw fixation superiorly allows for safe instrumentation in the thoracic spine, where pedicle screw placement is hazardous or may not be possible due to the small pedicle diameter.

The halo-Ilizarov distraction cast for correction of cervical deformity. Report of six cases.

Six patients were managed with gradual reduction of a deformity of the cervical spine, before operative stabilization, with use of a modified halo cast with adjustable distraction components that allowed the patient to sit and walk while the deformity was being corrected. The distraction components were constructed from the distractors, hinges, and connectors of an Ilizarov apparatus. The diagnoses were atlanto-axial subluxation secondary to rheumatoid arthritis, atlanto-axial rotatory subluxation secondary to juvenile rheumatoid arthritis, post-traumatic atlanto-axial rotatory subluxation, ankylosing spondylitis with an angulated fracture of the seventh cervical vertebra, atlanto-occipital and atlanto-axial subluxation secondary to familial cervical dysplasia, and cervicothoracic kyphosis secondary to laminectomy and radiation for astrocytoma. All of the deformities were corrected initially, but the deformity partially recurred in three patients: in the lower cervical area because of pseudarthrosis in one, and between the occiput and the first cervical vertebra after arthrodesis between the first and second cervical vertebrae in two. Complications included an infection at the site of the halo pin, which led to replacement of the pin (one patient); pressure sores under the body cast (two patients); dislodgment of the halo secondary to a fall, which necessitated reapplication of the halo (one patient); and pneumonia (one patient). Spinal distraction with halo-cast traction is a useful adjunct in the treatment of selected complex cervical and high thoracic deformities. Gradual three-dimensional correction may be obtained in a controlled fashion, while the patient is allowed out of bed to sit and walk.

Substance P innervation of lumbar spine facet joints.

Sixteen adult human lumbar spine facet joints were harvested from patients undergoing various lumbar spine procedures. Diagnoses included degenerative disc disease, adult spinal deformity, facet joint degenerative arthritis, and degenerative spondylolisthesis. Facet joints were processed for routine hematoxylin and eosin staining. Immunohistochemical analysis was performed using a monoclonal antibody to substance P. All facets grossly exhibited evidence of degenerative disease, including cartilage surface irregularity and fibrillation. Histological examination of facets obtained from patients with degenerative spinal conditions demonstrated erosion channels extending through the subchondral bone and calcified cartilage into the articular cartilage. Immunostaining showed the presence of substance P-positive nerve fibers within these erosion channels, and also within marrow spaces. The presence of substance P nerve fibers within subchondral bone of degenerative lumbar facet joints implicates this type of joint in the etiology of low back pain.

Salvage reconstruction in acute and late sequelae from pyogenic thoracolumbar infection.

Nine patients treated surgically for complicated pyogenic osteomyelitis of the thoracolumbar spine are reported. All patients were treated with anterior debridement and stabilization with nonvascularized autogenous fibular strut grafts. In addition, seven underwent a posterior spinal fusion with instrumentation. The average length of follow-up was 25 months. There was no recurrence of infection, no pseudoarthrosis, and the fibular struts appeared incorporated in all patients. Seven patients had postoperative improvement or resolution of their back pain. The use of nonvascularized autogenous fibular strut grafts for reconstruction of the spine following debridement for vertebral osteomyelitis is an effective procedure. The advantages of using the fibula for grafting are its strength and length for spanning several vertebral segments, and it can provide multiple grafts.

Metastatic vertebral disease in children.

We retrospectively reviewed 19 children with osseous vertebral metastases. The average age was 10.9 years at diagnosis of the primary tumor and 11.2 years at diagnosis of metastasis. The location of the multiple metastases was cervical (three), thoracic (14), and lumbar (10). Treatment consisted of chemotherapy (19), radiation therapy (12), and operation (seven). Ten children died at an average of 13 months after diagnosis of the primary tumor; nine are alive at an average of 72 months after diagnosis. All four children treated with chemotherapy, spinal radiation, and laminectomy, and who survived > 2 months, developed deformity. In this particular situation, we encourage consideration of spinal stabilization when it is appropriately coordinated with radiation and chemotherapy.

A case of traumatic spino-pelvic dissociation.

A case of traumatic spino-pelvic dissociation is reported. The unusual fracture pattern (grade III-B open left sacroiliac joint fracture dislocation, Denis type I longitudinal right sacral fracture, transverse sacral fracture at the S3-4 level, and a left comminuted pelvic wing fracture) led to a complete dislocation of the spine from the pelvis, transection of the left S1 and S2 nerve roots, and intrusion of the cranial portion of the spine into the pelvis. The patient underwent open reduction internal fixation of the spine and the pelvis in combination with general surgical management. Two years postinjury, the patient lives independently and walks with one cane.

Osteoid osteoma and osteoblastoma of the spine.

Eleven patients with spinal osteoid osteoma and six patients with spinal osteoblastoma treated between 1975 and 1990 were reviewed to characterize the tumors as they affect the spine and to define the important differences between the two tumors. All patients with cervical osteoid osteoma presented with pain, limited range of motion of the neck, and torticollis. Four osteoblastomas had soft-tissue components in the epidural space, necessitating dissection of the tumor from the dura. No soft-tissue component was found in any of the osteoid osteomas. Our results were similar to a metaanalysis of the clinical, radiographic, and surgical findings of all published cases of spinal osteoid osteoma and osteoblastoma. Important features that have not been emphasized in the literature are the high incidence of torticollis with cervical lesions and the frequent association of epidural invasion with osteoblastoma. Surgeons treating osteoblastoma of the spine should be prepared to dissect tumor from the dura.