Surgical results of lumbar spinal stenosis.

The purpose of this work was to evaluate the surgical results of lumbar spinal stenosis (LSS), and to find factors which influenced outcome. A total of 497 LSS patients fulfilled the inclusion criteria i.e. LSS was confirmed both radiologically and surgically, in the study period from 1974 to 1987. For various reasons 58 patients could not participate in the study, and hence, the results of this work were based on 439 surgically treated LSS patients. An excellent-to-good outcome was achieved in 62% of all patients with a mean follow-up time of 4.3 years. The prognostic factors for this result were able to work after surgery, able to work before surgery, no prior back surgery, age over 50 years, male sex, and leg pain. Of 86 patients who were working before surgery, 52 (60%) continued to work after operation, whereas of 223 patients who were on sick leave before surgery, 70 (31%) returned to work after operation. None of the preoperatively retired patients regained their ability to work postoperatively. The prognostic factors for ability to work after surgery were ability to work before surgery, age under 50 years, and no prior back surgery. The very long-term outcome (mean followup time of 12.4 years) was excellent-to-good in 68% of patients (59% women and 73% men). Furthermore, in the longitudinal follow-up, the result improved between 1985 (mean follow-up time 6.8 years) and 1991 (mean follow-up time 12.8 years). No special complications were manifested during this very long-term follow-up time. The patients with total or subtotal block in preoperative myelography achieved the best result. In this radiological category of LSS the proportion of patients with excellent-to-good outcome was very similar in women and men (73% and 77%). Furthermore, patients with block stenosis improved their result significantly in the longitudinal follow-up. The postoperative stenosis seen in computed tomography (CT) scans was observed in 65% of 90 patients, and it was severe in 23 patients (25%). However, this successful or unsuccessful surgical decompression did not correlate with patients' subjective disability, walking capacity or severity of pain. Previous back surgery had a strong worsening effect on surgical results. This effect was very clear in patients with total block in the preoperative myelography. The surgical result of a patient with previous back surgery was similar to that of a patient without previous back surgery when the time interval between the last two operations was more than 18 months.(ABSTRACT TRUNCATED AT 400 WORDS)