LUMBAR SPINAL STENOSIS - ASSESSMENT OF LONG-TERM OUTCOME 12 YEARS AFTER OPERATIVE AND CONSERVATIVE TREATMENT

The present study focuses on the long-term prognosis of radiographical ly verified stenosis of the lower lumbar spine. The purpose here was t o describe the outcome 12 years after radiographic diagnosis of spinal stenosis and to identify factors predicting disability after operativ e or conservative treatment. Data were compiled on 75 patients (43 men and 32 women) with changes in functional myelography diagnostic for s pinal stenosis. Their mean age at the interview 12 years later was 61 years. The sagittal diameter of the dural sac was measured from baseli ne myelographs at all intervertebral levels and was corrected for magn ification. In the interview, subjective outcome assessment was obtaine d with a structured questionnaire, and the low-back disorder was score d using the Oswestry disability index. The sagittal diameter of the du ral sac was severely stenotic (<7.0 mm) in 32 patients (26 operated), and moderately stenotic (7.0-10.5 mm) in 43 patients (31 operated). Th e severity of the stenosis significantly predicted disability, even wh en the effects of age, sex, therapy regimen, and body mass index a err adjusted for. For moderate and severe stenosis, the adjusted mean Osw estry indices were 28.4 and 39.1, respectively (p = 0.01). Therapy as such (operative versus nonoperative) did not significantly correlate w ith later disability. The radiographic severity of lumbar spinal steno sis predicts disability independently of therapy regimen. Randomized c linical trials are needed to establish the indications for surgical an d conservative treatment. Radiographic severity of the stenosis should be considered as an effect-modifying or confounding factor in clinica l trials and other studies focusing on the outcome of lumbar spinal st enosis.