Analysis of the risk factors for the development of post-operative spinal epidural haematoma.

In order to identify the risk factors and the incidence of post-operative spinal epidural haematoma, we analysed the records of 14 932 patients undergoing spinal surgery between 1984 and 2002. Of these, 32 (0.2%) required re-operation within one week of the initial procedure and had an International Classification of Diseases (ICD)-9 code for haematoma complicating a procedure (998.12). As controls, we selected those who had undergone a procedure of equal complexity by the same surgeon but who had not developed this complication. Risks identified before operation were older than 60 years of age, the use of pre-operative non-steroidal anti-inflammatories and Rh-positive blood type. Those during the procedure were involvement of more than five operative levels, a haemoglobin < 10 g/dL, and blood loss > 1 L, and after operation an international normalised ratio > 2.0 within the first 48 hours. All these were identified as significant (p < 0.03). Well-controlled anticoagulation and the use of drains were not associated with an increased risk of post-operative spinal epidural haematoma.

Anterior spinal cord injury with preserved neurogenic 'motor' evoked potentials.

OBJECTIVE: To describe two cases in which intraoperative monitoring of neurogenic 'motor' evoked potentials (NMEPs) did not identify a spinal cord injury that resulted in paraplegia. METHODS: Bilateral tibial nerve somatosensory evoked potential (SEP) and NMEP testing was performed in two patients during spinal deformity corrective surgery using standard stimulation and recording parameters. These potentials were obtained repetitively throughout the primary procedures and were performed again during a subsequent procedure that took place after the discovery of paraplegia. RESULTS: SEP and NMEP signals were preserved in both patients and no adverse events were identified during the initial procedures. Postoperatively, paraplegia was identified immediately upon recovery from anesthesia and preserved posterior column function was apparent on clinical exam. In the procedures following the discovery of paraplegia, SEP and NMEP signals remained comparable with signals elicited in the initial surgeries. CONCLUSIONS: Based on these cases and previously published experimental evidence, we conclude that while 'NMEPs' remain a useful second test of spinal cord function, they are not reliable indicators of motor tract function. An alternate term, such as 'spinally-elicited peripheral nerve responses' should be used.

Production of a reproducible spinal burst fracture for use in biomechanical testing.

We have developed a technique to create a reproducible spinal burst fracture of the 12th vertebral body using 6-8-week-old calf spines with ribs, muscles, and vessels resected. We used the entire thoracolumbar segment of 20 calf spines with a standardized 5-mm-deep slice placed onto the body of T12 and the T11-12 disc. We then delivered a proximal-axial impact to the vertically mounted spine, preflexed to 15 degrees of forward flexion, by dropping a 32-kg weight, guided by a 1.55-m steel rod (potential energy = 487 J). Motion was limited to anterior flexion only, at the T12-13 disc, by splinting the rest of the spinal segments. Fractures were documented with the use of radiographs and computed tomography (CT) scans. We noted disruption of the vertebral column and end plates, fracture of the posterior body wall, fracture of the pedicles, and retropulsion of bony fragments into the neural canal. With the production of a reproducible spinal burst fracture model, various spinal fixation devices can be applied and tested.

An anatomical comparison of the human and bovine thoracolumbar spine.

The bovine spine has been frequently selected as the model for in vitro mechanical studies. A comparative anatomical study has been presented describing important differences and similarities between selected areas in the adult human and calf thoracolumbar spinal segment. Differences in column length and curvature were observed. The total length of the adult bovine vertebral column was found to be on average 209 cm longer than the adult human spine. Equivalent thoracolumbar lengths were obtained by selecting 6-8 week-old dairy calves, which because of their young age had the benefit of consistent bone density. The bovine spine was found to have only a single cervical lordotic curve and a single thoracolumbar kyphotic curve (2). A quantitative comparison of selected dimensions of vertebrae T6, T12, and L3 was performed, and significant findings are discussed. The bovine spinous processes were found to be on average 111% greater in length at level T6, which contributed to a 56% greater total anterior/posterior length at this level in comparison to the vertebrae of an adult male. A 23% greater bovine intertransverse length at level L3 was also shown. The orientation of the human and bovine superior facets, while being in the same general plane and direction, varied as much as 10.5 and 107% at vertebral level L3 on the two axes measured. These significantly different measurements were considered important factors that can influence experimental results when using the bovine spine as a model.

Anterior Zielke instrumentation for spinal deformity in adults.

Fifty-eight adults who had scoliosis or hyperlordosis had anterior arthrodesis and Zielke instrumentation. Postoperatively, the curve improved 68 per cent in forty-nine patients who had idiopathic scoliosis and 40 per cent in nine patients who had paralytic scoliosis or hyperlordosis or congenital scoliosis. More correction was obtained when a derotator apparatus was used. Only one patient had failure of the instrumentation that necessitated additional surgical treatment. All of the arthrodeses resulted in osseous fusion. No patient who had idiopathic scoliosis lost correction (average follow-up, forty-two months; range, thirty to seventy-eight months). There were no serious complications. Lumbar lordosis decreased an average of 24 per cent compared with the preoperative measurement. This decrease was thought to be related to the correction of vertebral rotation in the curve and to the surgical technique. Use of the Zielke instrumentation resulted in excellent correction, which was not lost postoperatively in the patients who had an idiopathic curve and which was associated with minimum complications.

Cauda equina syndrome and lumbar disc herniation.

In a retrospective chart review of the cases of thirty-one patients with cauda equina syndrome secondary to a central disc lesion, we identified two modes of presentation. The first was an acute mode (ten patients) in which there were abrupt, more severe symptoms and signs and a slightly poorer prognosis after decompression, especially for the return of bladder function. The second mode of presentation (twenty-one patients) was a slower onset, characterized by prior symptoms for varying time-intervals before the more gradual onset of the cauda equina syndrome. All patients had urinary retention preoperatively. Bladder function was the most seriously affected function preoperatively and remained so postoperatively. The prognosis for return of motor function was good, since twenty-seven of the thirty patients who were operated on regained normal motor function. Preoperatively all patients had sciatica, which was bilateral in fourteen and unilateral in seventeen. The average time to surgical decompression after the patient was seen ranged from 1.1 days for the more acute lesions to 3.3 days for the second group. There was no correlation of these times with return of function. Therefore, even though early surgery is recommended, decompression does not have to be performed in less than six hours if recovery is to occur, as has been suggested in the past.

Van Nes rotational osteotomy for treatment of proximal femoral focal deficiency and congenital short femur.

The results of twenty Van Nes rotational osteotomies for unilateral proximal femoral focal deficiency and congenital short femur were analyzed after follow-ups of two to eight years. Assessed on the basis of prosthetic function, the results were good in ten, fair in six, and poor in four. Twelve patients required a rerotation procedure, six of them twice, because of postoperative derotation. Appropriate leg-length discrepancy to place the ankle, converted to the knee, at the right level, as well as normal ankle and foot motion and muscle power, are prerequisites to the procedure, which should be deferred until the child is about twelve years old to avoid prolonged hospitalization for rerotation and gait training.

The measurement of skin blood flow in peripheral vascular disease by epicutaneous application of Xenon133.

Radioactive xenon133 applied epicutaneously was used to study the skin blood flow below the knee in sixteen normal subjects, in eight patients with peripheral vascular disease not requiring amputation, and in a blind study of twenty-nine patients requiring amputation. Following these twenty-nine amputations, the flow rates were made known and correlated with the rates of healing. When the flow rates were above 1.5 milliliters per minute per 100 grams of tissue (skin), the wounds generally healed. In thirteen other patients, Syme or below-the-knee amputations were performed on the basis of the flow rates, and all of the wounds healed. The test, therefore, is now used routinely prior to amputation for peripheral vascular disease as an adjunct to clinical judgment in the determination of the level of amputation.

Adolescent idiopathic scoliosis. Long-term effect of instrumentation extending to the lumbar spine.

We evaluated eighty-three patients in whom adolescent idiopathic scoliosis had been treated with a posterior spinal arthrodesis and Harrington instrumentation extending to the second, third, fourth, or fifth lumbar vertebra. All eighty-three patients completed a questionnaire, and fifty-five patients were also examined clinically and roentgenographically at a follow-up evaluation at an average of twelve years (range, ten to sixteen years). Twelve patients had a type-I curve; twenty-six, a type-II curve; sixteen, a type-III curve; and one, a type-IV curve, according to the classification of King et al. The preoperative Cobb angle of the primary curve averaged 60 degrees and ranged from 40 to 100 degrees. The curve was an average of 35 degrees (range, 15 to 65 degrees) at the most recent follow-up evaluation. Functional assessment with use of information from the questionnaire revealed an average spine score of 81 points (range, 18 to 99 points). On the basis of the score, thirty-five patients were considered to have had an excellent result; twenty, a good result; thirteen, a fair result; and fifteen, a poor result. Sixty-three (76 per cent) of the eighty-three patients had low-back pain compared with thirty (50 per cent) of sixty individuals who served as a control group. This difference was significant (p < 0.001; chi-square test). Eighteen patients (22 per cent) needed additional spinal procedures. Fourteen patients (17 per cent) did not think that the goals of the initial operation had been accomplished.(ABSTRACT TRUNCATED AT 250 WORDS)

Anterior fixation for burst fractures of the thoracic and lumbar spine with or without neurological involvement.

This report details the use of the anterior approach for burst fractures of the thoracic and lumbar spine. The indication for dural decompression is acute neurological injury arising from significant canal intrusion. The use of anterior fixation devices, and in particular the anterior Kostuik-Harrington system, generally eliminates the necessity for a posterior approach. Anterior surgery has been performed in 80 cases for burst injuries of the thoracic and lumbar spine. Fifty-seven of these were paraparetic. While there were two cases of nonunion and 11 screw breakages, there were no early or late vascular or neurological complications. Average neurological recovery was 1.6 grades on the Frankel scale. All incomplete paraplegics recovered at least one grade. All complete paraplegics (four) failed to show any recovery.

Anterior Kostuik-Harrington distraction systems for the treatment of kyphotic deformities.

Based on the biomechanical principles of anterior distractive forces combined with instrumentation to decrease sagittal bending moments, an anterior system using a modification of Harrington instrumentation has been developed for the correction of kyphotic deformities. It has been used in the treatment of acute burst fractures in 100 cases, posttraumatic kyphosis in 45 cases, Scheuermann's kyphosis in 36 cases, rigid round backs in three cases, acute rigid kyphosis (congenital) in four cases, postlaminectomy in 21 cases, flat back syndrome in 56 cases, kyphosis secondary to tumor in ten cases, and kyphosis secondary to osteoporosis with fracture in four cases. A total of 279 cases have been treated with anterior instrumentation. Complications include breakage of 35 screws and four rods. There have been no early or late vascular or neurologic sequelae related to instrumentation. The biomechanical basis for the treatment of kyphotic deformities includes an anterior distractive force to resist compressive loads and, where possible, segmental fixation to decrease sagittal bending moments combined with bone grafts far from the neutral axis. This system provides these benefits with minimal risk and morbidity.

Anterior spinal cord decompression for lesions of the thoracic and lumbar spine, techniques, new methods of internal fixation results.

Seventy-nine patients, 51 with a fresh neurologic deficit, underwent anterior spinal cord decompression, block bone grafting and anterior internal fixation. AO plates were used in nine patients. Dwyer cables in 15, anterior Harrington systems in 20, and solid Hall rods with Dwyer screws in 23. Cases included 13 tumors (six metastatic, five primary malignant, two benign), 15 late kyphotics (13 congenital and two old tuberculosis), 15 pyogenic (nontuberculous) infections, 32 fractures and four thoracic discs. Levels of decompression were from T5 to L5 with the majority (23) at L1. The neurologic deficit improved in 100% of those with incomplete paraplegia, and was graded according to the Frankel classification. None was made worse. Surgical indications were: progressive neurologic deficit in 51 patients, tumors in 13, correction of deformity in 55, failure of infection to respond to conservative measures in 15, cachexia in nine, (many patients had more than one indication). Bone grafts included 11 rib grafts, 24 block iliac grafts with ribs and 44 iliac block grafts. Complications included three nonunions, two common iliac vein lacerations, one death (pulmonary) and two post-thoractomy syndrome. The more recent use of an anterior Harrington distraction system allows for greater correction of kyphotic deformities and more rigid internal fixation which in time allows for early ambulation in a brace. Supplementary posterior fixation is generally no longer necessary except where more than one vertebral body is resected.

Decision making in adult scoliosis.

This report analyzes a series of 350 adult patients whose spinal deformity was treated surgically. Indications included pain, curve progression, cosmesis, structural disabilities, neurologic complications, cardiorespiratory problems, and failed previous surgery. Discography was helpful in assessing complex pain problems, and its use led to improved results of surgery because of more comprehensive preoperative definition of the problem. Pain relief occurred in 70% of patients. Traction, either the halo-femoral or the halo-pelvic type, was used in 62 patients. Complex surgery, including anterior and posterior approaches, is required in curves of large magnitude, especially when curves are rigid. Overall curve correction in this series was 40%.

Pitfalls of biomechanical testing.

A review of the pitfalls of biomechanical testing and its experimental designs are presented in order to provide a format for the young spinal experimentor, and an outline of procedural error and logical thinking for nonclinical spinal experimentation, be it in vitro, in vivo, or with mathematical modeling. Subsequent sections deal with the specifics of in vitro and in vivo testing and mathematical modeling.

The incidence of low-back pain in adult scoliosis.

To date no knowledge of the incidence of scoliosis in adults and its relationship to low-back pain is available. In order to arrive at an understanding of low-back pain in adult scoliosis, a study of 5000 intravenous pyelograms was performed. The incidence of lumbar and thoracolumbar curves was 2.9%. One hundred and fifty-nine of the 189 patients found to have scoliosis were contacted. The incidence of back pain was 59% (similar to that in the general population). Back pain was subdivided into mild (44%), moderate (49%), or severe (7%). The curve was subdivided into three categories: 10-24 degrees, 25-44 degrees, and 45+ degrees. Of the 82 idiopathic curves with pain, 64 were in group 1, 15 in group 2, and 3 in group 3. Forty-three percent had mild pain, 50% had moderate pain, and 7% had severe pain. As the degree of curvature increased, the severity of pain increased, especially for curves of more than 45 degrees. Patients without back pain tended to have smaller curves. the presence of facet sclerosis correlated with a history of pain in 64%. There was a high correlation between radiologic changes at the curve apex and pain. Age bore no relationship to the incidence of pain.

Anterior stabilization, instrumentation, and decompression for post-traumatic kyphosis.

Thirty-seven patients underwent surgery for late post-traumatic kyphosis in the lumbar, thoracolumbar, or thoracic spine. Indications for surgery included: increasing deformity, pain, and persistent neurologic deficit with paraparesis in eight, and development of late spinal stenosis in a further nine patients. All patients underwent anterior correction with Kostuik-Harrington instrumentation. Seventeen patients with neurologic deficit underwent decompression over appropriate levels as well. No posterior fusions or instrumentation were carried out. Stable arthrodesis with correction of the deformity occurred in 36 of 37 patients with only one nonunion. Pain was reduced significantly in 78% of patients. Late neurologic improvement of a significant functional degree occurred in three of eight paraparetics. All patients with spinal stenosis had relief of their symptoms and signs.

Spinal fusions to the sacrum in adults with scoliosis.

Forty-five skeletally mature patients averaging 44.3 years of age had spinal fusions which extended to the sacrum for pain and/or progression of their scoliosis. The primary diagnosis was idiopathic scoliosis in 35 patients, congenital scoliosis in two patients, and paralytic scoliosis in eight patients. A single curve pattern was present in 41 patients and the remainder had double primary curves. Thirty-eight patients had single stage procedures and 35 of these were done posteriorly. There was an evolution in the type of posterior instrumentation used over the 12 years. Thirty-five patients (78%) had at least one significant postsurgical complication. Thirteen of 22 patients with loss of lordosis required corrective osteotomies. Other complications included pseudoarthrosis in ten patients and neurologic complications in five patients, four of which had complete recovery. Twenty-five patients required a total of 51 subsequent surgical procedures. Despite a 51% initially poor result and a high complication rate, the final results were good or fair in 93% of the patients. This change was primarily the result of successful subsequent surgical procedures for correction of loss of lordosis and pseudoarthrosis. The adult scoliosis patient should be fused to the sacrum only if the lumbosacral disc is clearly a source of pain or the degree of pelvic obliquity makes it necessary in the paralytic curve. Every effort must be made to carefully preserve the patient's lumbar lordosis. Better results were obtained by using segmental spinal fixation in the form of sublaminar wiring of double Luque rods.

Continuous electromyographic monitoring to detect nerve root injury during thoracolumbar scoliosis surgery.

STUDY DESIGN: The results of intraoperative monitoring during a case of nerve root injury sustained from scoliosis surgery to the thoracolumbar spine are described. OBJECTIVES: To improve the efficacy of intraoperative monitoring in preventing nerve root injury during scoliosis surgery. SUMMARY OF BACKGROUND DATA: Posterior tibial nerve somatosensory-evoked potentials are the electrophysiologic modality most commonly used for spinal cord monitoring during thoracolumbar spine surgery. Although radiculopathy is a more frequent postoperative complication than myelopathy, monitoring of mixed-nerve, somatosensory-evoked potentials may not detect injuries to individual nerve roots. METHODS: The patient described in this report developed left L5 radiculopathy after scoliosis surgery to the thoracolumbar spine. During surgery, intraoperative electromyographic monitoring identified frequent trains of neurotonic discharges in the left anterior tibial muscle. Bilateral, posterior, tibial nerve, somatosensory-evoked potentials remained normal. The left L5 nerve root was explored 9 days after the original surgery and was found to be compressed by bony structures. Electrophysiologic testing showed that the nerve root had undergone significant Wallerian degeneration, but remained in partial continuity. RESULTS: Nerve root injury was detected by neurotonic discharges identified during intraoperative electromyographic monitoring, but not by somatosensory-evoked potentials, which remained normal. When the injured nerve root was explored, a simple electromyographic technique was used to characterize the extent and type of injury. CONCLUSIONS: The authors of this study recommend electromyographic monitoring of appropriate lumbosacral myotomes in addition to somatosensory-evoked potentials during this type of procedure.

Surgical management of metastatic renal carcinoma of the spine.

A total of 33 patients with renal cell carcinoma metastatic to the spine underwent spinal decompression over a 5-year period; 20 were operated on for neurologic dysfunction, and the remainder for pain alone. Surgery was performed anteriorly in 21, posteriorly in 9, and combined in 3 cases. The surgical approach was determined by the preoperative anatomic localization of the tumor. Of these patients 88% had fusions with instrumentation and polymethylmethacrylate; 88% of patients had partial or complete relief of pain; and 64% of bedridden patients subsequently were able to walk. Neurologic function improved in 60% of patients with a neurologic deficit; however, only 36% of incontinent patients regained bladder control. Survival averaged 8.0 +/- 1.5 months. Survival correlated with the degree of neurologic dysfunction and the presence of other known metastases. Recurrent cord compression developed in 49% of patients, usually at the same level; 9 of these 16 patients had repeat decompression, with similar operative results as the primary procedure in terms of pain and neurologic function. Blood loss was variable but often significant. Preoperative embolization appeared to be beneficial. Precise tumor localization preoperatively directing the surgical approach and better patient selection would likely improve results and decrease morbidity. Good palliation appeared to be achieved in regards to both pain relief and improved neurologic function.

Combined single stage anterior and posterior osteotomy for correction of iatrogenic lumbar kyphosis.

Fifty-four patients were treated by a standardized single stage anterior opening wedge and a posterior closing extension wedge osteotomy for back pain associated with postoperative loss of lumbar lordosis (iatrogenic flat back syndrome). Presenting complaints were fatigue, pain and a stooped posture. Etiological factors were, in descending order of frequency, distraction instrumentation with the lower end at the L5 or S1 vertebra, thoracolumbar junction kyphosis greater than 15 degrees, especially if associated with a hypokyphotic thoracic spine, and degenerative changes above and below a previous fusion. Kostuik-Harrington instrumentation was used anteriorly for the opening wedge and Dwyer cables and screws together with a midline plate were used posteriorly for the closing extension osteotomy. Malunion occurred in three patients, one requiring recorrection. Pain relief occurred in 48 (90%). Neurological complications occurred in two patients, one with permanent deficient. Follow-up averaged 4 years. Average preosteotomy lordosis L1-S1 was 21.5 degrees and was restored to 49 degrees (equal to the lordosis before the initial surgery) for an average correction of 29 degrees, (range 24 degrees to 63 degrees). Prevention of this complication can be accomplished by maintaining normal lordosis at the time of initial surgery.