Laparoscopic spinal fusion

This article details the development of the laparoscopic technique of interbody spinal fusion. The rationale for this procedure is discussed as are indications, contraindications, and operative technique. The results of over 100 laparoscopic lumbar fusions are presented along with their complications and surgical recommendations.     

Alternatives to spinal fusion

Techniques have changed significantly with the advent of less invasive surgical techniques for disc excision and spinal fusion; these include the development of rigid internal fixation devices using multiple points of fixation and the better knowledge of the biology of spinal fusion. Despite these improvements in technology, room exists for alternative forms of surgical treatment because of significant failures particularly related to spinal fusions.     

Fatal pulmonary fat embolism after dorsal spinal fusion

OBJECTIVE: To determine whether health shop staff give specific therapeutic recommendations to someone who describes symptoms associated with serious pathology and to determine whether they refer this person to conventional medical care. DESIGN: Quantitative survey using participant observation. SETTING: Health food shops selling herbal, homeopathic or nutritional remedies in inner London. METHOD: A researcher visited 29 health food shops and claimed to be suffering from severe, daily headaches of recent onset. The researcher recorded on tape whether the health shop staff took diagnostic information; recommended any therapeutic intervention; asked about or recommended seeing a general practitioner (GP); asked about use of conventional drugs. Coding of the interactions was carried out independently by two researchers. RESULTS: Whereas all but two shops recommended a specific therapeutic intervention, less than one in four advised a GP consultation. Forty-two different interventions were recommended. There was little consistency in the advice given. CONCLUSION: Health food shops need to review the circumstances in which they should venture to provide advice and the basis on which they make any therapeutic recommendations. Shops selling over-the-counter herbal, homeopathic and health food products are a common feature of UK high streets. Such shops could be a useful source of health information and advice to their customers, but could also lead to harm, for example by delaying treatment of known benefit, if their recommendations were to be inaccurate or inappropriate.     

Biomechanical testing sequelae relevant to spinal fusion and instrumentation

The increasing prevalence of spinal disorders and associated treatments has produced a dramatic increase in the number of available devices. The biomechanical evaluation leading to the design, development, and implementation of spinal instrumentation has resulted in a number of in vitro and in vivo testing methods. This article reviews some of the methods and associated results obtained by various evaluation techniques of spinal fusion hardware. Current work and future considerations also are presented.     

Aerobic and anaerobic microbiology of surgical-site infection following spinal fusion

The aerobic and anaerobic microbiology of surgical-site infections (SSI) following spinal fusion was retrospectively studied. This was done by reviewing the clinical and microbiological records at the Naval Hospital in Bethesda, Md., from 1980 to 1992. Aspirates of pus from 25 infection sites showed bacterial growth. Aerobic bacteria only were recovered from 9 (36%) specimens, anaerobic bacteria only were recovered from 4 (16%), and mixed aerobic and anaerobic bacteria were recovered from 12 (48%). Sixty isolates were recovered: 38 aerobes (1.5 isolates per specimen) and 22 anaerobes (0.9 isolate per specimen). The predominant aerobes were Escherichia coli (n = 8) and Proteus sp. (n = 7). The predominant anaerobes were Bacteroides fragilis group (n = 9) and Peptostreptococcus sp. (n = 6) isolates. An increase in recovery of E. coli and B. fragilis was noted in patients with bowel or bladder incontinence. This study highlights the polymicrobial nature of SSI and the importance of anaerobic bacteria in SSI following spinal fusion.     

Muscle and musculocutaneous flap coverage of exposed spinal fusion devices

Midline wound dehiscence in the back with exposure of spinal stabilization devices remains a challenging problem, mainly in the presence of infection. Usually, the treatment consists of instrumentation removal, wound debridement, and antibiotic therapy. These can result in instability of the spine and significantly prolong the hospitalization. The use of muscle and musculocutaneous flaps provides excellent soft-tissue coverage, obliterates the dead space, controls the infection, and creates conditions to salvage the hardware. Eight cases of spinal rod instrumentation, complicated by wound infection and dehiscence, have been treated successfully with single or multiple muscles and musculocutaneous flaps. Our method of treatment for these complex wounds, in two institutions, is discussed.     

Contrast enhancement in primary tumors of the brain and spinal cord

The patterns of contrast enhancement by CT and MR imaging for most intramedullary primary tumors of the brain and spinal cord are discussed. Contrast administration allows for the separation of tumor from normal neighboring tissues in most cases. Although most of the published data refer to contrast-enhanced CT scanning, gadolinium-enhanced MR imaging has become the modality of choice in the evaluation of primary central nervous system tumors.     

Radiological and functional outcome after anterior lumbar interbody spinal fusion

The efficacy of hCG treatment was studied in 182 cryptorchid patients. The efficacy of the treatment correlated with the initial position of the testis. None of the abdominal testes reached a normal position, whereas 90% of high scrotal testes descended during the treatment. Fifty-four boys who were treated unsuccessfully with hCG and 29 untreated boys were biopsied. The biopsies were performed on 32 scrotal and 87 maldescended testes to examine the state of the organ and the effects of hCG treatment. In biopsies, the volume densities of seminiferous tubules, interstitial tissue and blood vessels were counted, and the sections screened for interstitial bleeding. Significant differences between scrotal and maldescended testes were found in all of the volume densities measured. Interstitial bleeding occurred rarely in scrotal testes, whereas in maldescended testes it was frequently apparent. hCG treatment induced a significant increase in the volume density of both interstitial tissue and blood vessels. Even though the hCG treatment induced measurable, possibly harmful, changes both in scrotal and maldescended testes, our data do not prove that hCG treatment causes permanent damage to the testis.     

One-stage internal fixation and anterior fusion in complex cervical spinal disorders

The authors describe their experience with the Morscher titanium cervical plate with cancellous locking screws in the management of complex cervical spine disorders. Fifty patients (32 males and 18 females) with a mean age of 54 years (range 10 to 84 years) underwent anterior spinal fixation that extended two to five vertebral bodies, using a titanium cervical plate and autogenous bone graft. Surgeries were performed for a variety of reasons: one for a congenital lesion, five for spinal neoplasms, nine for trauma, and 35 for degenerative arthritides. Ten patients had symptomatic kyphoses due to previous laminectomy, failed anterior surgery, or trauma. Satisfactory fixation and fusion with no neurological deterioration was obtained in all but two cases. Specific complications included six cases of dysphagia, one of sepsis, one of Horner's syndrome, and one case in which the patient had a fatal myocardial infarction the night after surgery. At the end of the follow-up period, fusion was found to have occurred in all remaining cases with no outstanding implant-related problems.     

Maturation of the posterolateral spinal fusion and its effect on load-sharing of spinal instrumentation. An in vivo sheep model

We investigated the temporal relationship among the biomechanical, radiographic, and histological properties of a posterolateral spinal fusion mass to elucidate the changes in load-sharing of the spinal instrumentation and that of the fusion mass throughout the healing process. Destabilization of the posterior spinal column and transpedicular screw fixation at the segments between the third and fourth and the fifth and sixth lumbar vertebrae was performed in twenty-four sheep. A posterolateral spinal arthrodesis with use of autologous corticocancellous bone graft was done randomly at one of the two segments; the other segment (without bone graft) served as the instrumented control. Six animals each were killed at four, eight, twelve, and sixteen weeks postoperatively. Biomechanical testing showed that the posterolateral fusion mass had increased mechanical stiffness after the fourth week. The strain on the hardware, measured with use of rods instrumented with strain-gauges, decreased significantly (p < 0.01) beginning at eight weeks. Radiographically, three independent observations of each of the six animals at each time-period showed that, although all of the fusion masses were considered solid unions at sixteen weeks, bridging of trabecular bone was noted during only ten of eighteen observations at twelve weeks, three of eighteen observations at eight weeks, and none of eighteen observations at four weeks. Computerized tomography and histomorphometric analyses demonstrated that mineralization in the fusion mass increased in a linear fashion even after eight weeks. Histologically, the fusion mass consisted predominantly of woven bone at eight weeks; thereafter, it was gradually trabeculated. CLINICAL RELEVANCE: We found a great discrepancy between biomechanical stability and histological maturation of the posterolateral fusion mass. The biomechanical properties of a stable spinal fusion preceded the radiographic appearance of a solid fusion by at least eight weeks, suggesting that immature woven bone provided substantial stiffness to the fusion mass. The spinal instrumentation was subjected predominantly to bending stress rather than to axial stress, and the load-sharing of the spinal instrumentation decreased concurrently with the development of the spinal fusion.     

Prevalence of perioperative complications after anterior spinal fusion for patients with idiopathic scoliosis

BACKGROUND: The most common primary brain tumors in children and adults are of astrocytic origin. Classic histologic grading schemes for astrocytomas have included evaluating the presence or absence of nuclear abnormalities, mitoses, vascular endothelial proliferation, and tumor necrosis. MATERIALS AND METHODS: We evaluated the vascular pattern of 17 astrocytoma surgical specimens (seven from children and 10 from adults), and four normal brains obtained at autopsy, utilizing antibody to glial fibrillary acidic protein (GFAP) and von Willebrand factor (vWF) utilizing confocal microscopy. A modified WHO classification was used. RESULTS: All tumor cases showed cells positive for GFAP. Control tissues showed a few, widely separated vessels. Pilocytic astrocytomas (four cases) showed lacy clusters of small-to-medium sized vessels, with intact vessel wall integrity. Diffuse, low grade astrocytoma (three cases) showed a staining pattern similar to control tissue; intermediate grade (one case), anaplastic astrocytoma (three cases) and gliobastoma multiforme (six cases) showed an increased vessel density with multiple small vessels (glomeruloid clusters), some with prominent intimal hyperplasia, loss of vessel wall integrity, and with numerous vWF-positive single cells/microvessels within the tumor substance. CONCLUSIONS: Evaluation of astrocytomas utilizing antibody to vWF and confocal microscopy aids in the grading of these neoplasms.     

Intraoperative awakening for early recognition of possible neurologic sequelae during Harrington-rod spinal fusion

To permit early recognition of possible cord trauma due to spinal fusion with Harrington-rod instrumentation, 42 patients were awakened introperatively for testing voluntary motor function of the limbs. N2O-O2-curare and morphine were used for anesthesia in all patients. In 5 patients, who refused IV induction, halothane was given for induction only. Only 1 patient had any complaint referrable to being awakened intraoperatively. The awakening caused no displacement of Harrington rods in any patient. No neurologic sequelae were found.     

Microdecompression and uninstrumented single-level fusion for spinal canal stenosis with degenerative spondylolisthesis

STUDY DESIGN: A retrospective review was completed on 21 patients who had a "least invasive" (one or two level) microdecompression and uninstrumented single-segment lumbar fusion for spinal canal stenosis with degenerative spondylolisthesis. OBJECTIVE: To determine whether a "least invasive" approach to lumbar spinal canal stenosis and degenerative spondylolisthesis would yield acceptable results. SUMMARY OF BACKGROUND DATA: The prevailing surgical technique for symptomatic spinal canal stenosis with degenerative spondylolisthesis is a wide midline decompression and instrumented fusion. METHODS: On an average of 38 months postoperatively, 21 patients were personally assessed on four scores: 1) their overall satisfaction with the outcome of surgery, 2) an analog back and leg pain scale, 3) a functional evaluation scale, and 4) Ferguson (upshot) anterior-posterior lumbosacral and lateral flexion-extension radiographs. RESULTS: The overall satisfactory outcome on all four scales was 16 (76%) of 21. Twenty of twenty-one patients had relief of their claudicant leg pain; the overall fusion rate was 18 (86%) of 21. Two of three patients with a pseudarthrosis had a successful outcome on the patient-oriented outcome (1, 2, and 3) scales (excluding the radiograph scale), and one was a failure. One patient with a solid fusion was a failure because of continuing back pain. One patient with a solid fusion was a failure because of continuing leg pain. The overall satisfactory outcome on the nonradiographic scales was 18 of 21, for an 86% patient satisfaction rate. CONCLUSIONS: In this retrospective study, a "least invasive" surgical approach to lumbar degenerative spondylolisthesis with spinal canal stenosis causing claudicant leg pain produced acceptable results.     

Value of early postoperative plain radiography following BOP fusion in cervical spinal surgery

After anterior decompression and interbody fusion with biocompatible osteoconductive polymer (BOP) for cervical degenerative disease it is common practice to perform early radiography to evaluate the results, as a questionnaire sent to 136 consultants neurosurgeons in UK demonstrated. Radiographs of 39 patients following the procedure were analysed and it was concluded that the practice is of no value.     

Optimal selection and preparation of fresh frozen corticocancellous allografts for cervical interbody spinal fusion

STUDY DESIGN: Iliac crest corticocancellous allografts for anterior interbody fusion were harvested from six cadavers. The grafts were cut sequentially from left and right crests and randomly assigned to tricortical or bicortical preparations. Their compression strengths then were determined and compared by matched pair analysis. OBJECTIVES: To quantify the failure strength of the grafts from different iliac locations and determine the optimal type of preparation of the grafts for anterior interbody fusion. SUMMARY OF BACKGROUND DATA: Iliac crest corticocancellous autografts and allografts commonly are used for interbody cervical fusions. However, graft strengths for specific sites have not been determined fully. METHODS: Six paired, fresh frozen, iliac crests were sectioned using a customized miter box into multiple 1-cm-thick grafts 1.5 cm in depth to simulate cervical interbody grafts. The left and right sides of each pair were randomly assigned to tricortical and bicortical preparations. The samples were tested by applying a compressive load to failure using a specialized fixture to simulate vertebral body loading. RESULTS: The grafts closer to the anterosuperior iliac spine had significantly higher failure loads and failure strengths than those closer to the posterosuperior iliac spine. The strengths of the bicortical grafts were 72 +/- 14% of the strengths of the tricortical grafts (P < 0.001). CONCLUSIONS: Anterior iliac crest grafts were stronger in compression, even after removal of one cortical surface, than posterior iliac crest grafts.     

Tri-calcium phosphate ceramics and allografts as bone substitutes for spinal fusion in idiopathic scoliosis as bone substitutes for spinal fusion in idiopathic scoliosis: comparative clinical results at four years

The authors present the results of a comparative study of two series of posterolateral arthrodeses for scoliosis performed using COTREL DUBOUSSET instrumentation. Fifty-four consecutive patients underwent surgery for idiopathic scoliosis using the same technique. Thirty received a graft consisting of a mixture of corticocancellous autologous and allogenic bone frozen at -80 degrees, and 24 patients were grafted with a mixture of cortico-cancellous autologous bone and sticks of tricalcium phosphate (TCP, Biosorb, SBM, Lourdes, France). All patients were seen at three, six and twelve months, then once a year for at least four years with clinical and radiological evaluation at each visit. At the final follow up visit, no radiologic signs of pseudoarthrosis were found in either group with a minimum follow-up of 4 years. The appearance of bone callus was considered satisfactory at 6 months in all cases; moreover callus seemed to be more important in the TCP series, although this assessment was subjective. TCP resorption was total after 2 years, while allograft fragments were visible on x-rays after 2 years. Minor mechanical complications occurred but did not influence the results. Loss of correction was 8% of that initially obtained in the allograft group and 2% in the TCP group. Loss of correction did not progress after 6 months in the TCP group and after 2 years in the allograft group. Based upon this experience, the use of synthetic bone substitutes such as TCP would appear to be a valuable alternative to allografts in posterolateral spinal arthrodesis for idiopathic scoliosis, and it would eliminate the risk of viral contamination inherent to allograft implantation. To our knowledge, there have been no previous comparative studies concerning the use of tricalcium phosphate versus allograft in the literature.     

Reversing the inhibitory effect of nicotine on spinal fusion using an osteoinductive protein extract

STUDY DESIGN: The effect on spinal fusion of an osteoinductive bone protein extract in the presence of a known inhibitor of spinal fusion (systemic nicotine) was studied prospectively in an animal model of posterolateral lumbar fusion. OBJECTIVES: To evaluate the ability of a bovine-derived osteoinductive bone protein extract to overcome the inhibitory effect of nicotine in a rabbit spine fusion model. SUMMARY OF BACKGROUND DATA: Multiple studies have demonstrated the ability of a variety of osteoinductive growth factors to serve as a bone graft substitute for lumbar spinal fusion under "normal" healing conditions. METHODS: Forty-eight adult female New Zealand white rabbits underwent spine arthrodesis at L5-L6 while receiving systemic nicotine through a subcutaneous miniosmotic pump. Arthrodesis was performed using one of the following three graft materials: 1) autogenous iliac crest, 2) osteoinductive bone protein delivered in an allogeneic demineralized bone matrix/ collagen carrier, or 3) osteoinductive bone protein delivered with autogenous iliac crest. Fusions were assessed by blinded manual palpation, radiography, and biomechanical testing. RESULTS: Of the 44 rabbits manually tested by blinded observers, all 14 in the osteoinductive bone protein plus autogenous iliac crest bone group had solid fusions (14 of 14), whereas the fusion rate was less in the osteoinductive bone protein plus demineralized bone matrix group (nine of 14, 64%; P = 0.02), and there were no fusions in the autogenous iliac crest only group (0 of 16, 0%; P = 0.000001). The use of osteoinductive bone protein with autogenous bone produced stronger and stiffer fusions compared with those using autogenous bone alone or osteoinductive bone protein with allograft bone. CONCLUSIONS: Cigarette smoking and nicotine are inhibitory factors in the healing of fractures and spine fusions. This study shows that the inhibitory effect of nicotine can be overcome with an osteoinductive bone growth factor in an animal model.