Degenerative spondylolisthesis. Developmental or acquired?

Degenerative spondylolisthesis is four times more common in women than in men. Although this gender difference has long been recognised there has been no explanation for it. We have examined the radiographs and CT scans of 118 patients over the age of 55 years and of a control group under the age of 46 years. Our findings confirmed the presence of more sagittally-orientated facet joints in patients with degenerative spondylolisthesis but did not show that the gender difference can be explained by the morphology of the facet joint. Furthermore, we conclude that the increased angle of the facet joint is the result of arthritic remodelling and not the primary cause of degenerative spondylolisthesis. It is more likely to be due to loss of soft-tissue resilience with subsequent failure of the facet joints which are acting as the last restraints to subluxation.

The Graf ligamentoplasty procedure. Comparison with posterolateral fusion in the management of low back pain.

STUDY DESIGN: A retrospective case-control comparison between the Soft Tissue Stablization System according to Graf and instrumented posterolateral fusion in a consecutive series of patients operated on by a single surgeon. OBJECTIVES: To compare clinical and radiologic outcomes at 1 and 2 years. SUMMARY OF BACKGROUND DATA: Although series have been reported showing encouraging results with the use of the Graf ligamentoplasty for low back pain no comparative data are available on outcome when compared with those in more conventional treatments. METHODS: Eighty-three consecutive patients operated on for low back pain in a single surgeon's practice (TMH) were recalled for clinical and radiologic review. Patients underwent either soft tissue stabilization or posterolateral fusion with pedicle screw instrumentation. Each patient chose between the procedures after advice that the Soft Tissue Stabilization System, although experimental, was a reversible procedure. Independent observers conducted the review at 1 and 2 years. The Low Back Outcome Score was used as an objective measure of outcome. In addition to this, patients underwent computed tomographic assessment of pedicle screw placement. RESULTS: There was no statistically significant difference between groups in age, sex, body weight, symptom duration, previous surgery, dependency on workers' compensation, preoperative diagnosis, smoking habits, and the number of motion segments instrumented. There was a significantly better outcome, when measured by the Low Back Outcome Score in the group of patients managed by posterolateral fusion at 1 year (P = 0.02), although at 2 years the difference was less (P < 0.34). Patients with facet joint-related pain did no better after Soft Tissue Stabilization than did patients of other diagnostic groups. Compensable cases did better at 1 year after fusion (P < 0.003), although again the difference was less marked at 2 years (P = 0.09). There was a trend toward a higher revision rate in the Soft Tissue Stabilization System group (P = 0.11) at 1 year with a statistically significant (P = 0.01) difference apparent at 2 years. Revision after Soft Tissue Stabilization was associated with a poorer outcome, similar to that seen in revision after fusion. Pedicle screw misplacement rates were no different between the two groups and increased in frequency at the more cranial vertebral levels. CONCLUSIONS: Outcome after Soft Tissue Stabilization was associated with a worse outcome at 1 year and a significantly higher revision rate at 2 years. Revision was associated with a poor outcome similar to that seen in revision after fusion.

Total 24-hour melatonin secretion in adolescent idiopathic scoliosis. A case-control study.

STUDY DESIGN: A case-control study of 24-hour urinary melatonin production in patients with adolescent idiopathic scoliosis. OBJECTIVES: To address the controversy over the role of melatonin deficiency in adolescent idiopathic scoliosis by measuring total melatonin production over a 24-hour period. SUMMARY OF BACKGROUND DATA: An association between melatonin deficiency and experimental scoliosis has been suggested in several animal species. Recent work has failed to show a deficiency in humans with scoliosis. However, this conclusion was based on single urinary estimations. In this study the period assayed was standardized to 24-hours for all patients to include the full diurnal cycle of melatonin excretion. METHODS: Consecutive patients at an outpatient clinic for adolescent idiopathic scoliosis were recruited as subjects for this study, and patients from a fracture clinic who were of similar age and gender were recruited as controls at their final follow-up examination after the healing of their fracture. Patients and control individuals collected urine over a 24-hour period that was divided into consecutive day and night collections of 12 hours each. Total urinary excretion of 6-sulphatoxy melatonin was determined by radioimmunoassay for each 12-hour period in patients and control individuals. RESULTS: No significant difference in diurnal, nocturnal, or total urine 6-sulphatoxy melatonin excretion was found between adolescent patients with idiopathic scoliosis and controls of similar age and gender. There was also no difference between the two groups when 6-sulphatoxy melatonin excretion was corrected for body weight, body surface area, and body mass index. Nor was there a significant difference between 6-sulphatoxy melatonin excretion of patients with scoliosis whose curves failed to progress over the course of a year and the excretion of those who underwent surgery. CONCLUSIONS: In adolescent idiopathic scoliosis, neither the presentation with a stable spinal deformity, nor presentation with a severe deformity requiring surgery is associated with melatonin deficiency.

Accuracy of diagnostic coding for Medicare patients under the prospective-payment system.

Reimbursement of hospitals by Medicare under the prospective-payment system is based on patients' diagnoses as coded at discharge. During the period October 1984 through March 1985, we studied the accuracy of the coding for diagnosis-related groups (DRGs) in hospitals receiving Medicare reimbursement. We used a two-stage cluster method to sample 7050 medical records from 239 hospitals that were stratified according to size. Using blinded techniques with reliability checks, medical-record specialists reabstracted the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes to assign correct DRGs to discharged patients. The correct DRGs were then compared with those originally assigned by the physician and the hospital administration. The study revealed an error rate of 20.8 percent in DRG coding. Errors were distributed equally between physicians and hospitals. Small hospitals had significantly higher error rates. Previous studies had found that errors occurred randomly, so that half the errors benefited the hospital financially and half penalized the hospital. The present study found that a statistically significant 61.7 percent of coding errors favored the hospital. These errors caused the average hospital's case-mix index--a measure of the complexity of illness of the hospital's patients--to increase by 1.9 percent. As a result, hospitals received higher net reimbursement from Medicare than was supportable by the medical records. We conclude that "creep" does occur in the coding of DRGs, resulting in overpayment to hospitals for patients covered by Medicare.