A prospective and consecutive study of surgically treated lumbar spinal stenosis. Part II: Five-year follow-up by an independent observer.

STUDY DESIGN: A prospective and consecutive study of surgical results obtained during serial follow-up investigations in patients who underwent surgery for central lumbar spinal stenosis.

OBJECTIVES: To evaluate the result after surgical decompression for lumbar spinal stenosis, at regular intervals after surgery, and to correlate these results with values for preoperative parameters; special interest was focused on the results in relation to the degree of constriction of the spinal canal.

SUMMARY OF BACKGROUND DATA: The outcome after surgery for spinal stenosis is debatable; long-term follow-up investigations have indicated deterioration with passing time. Results of studies in nonsurgical patients have demonstrated that the symptoms do not progress with time. Results of a meta-analysis of the literature on surgical results have demonstrated a wide variation of outcomes.

MATERIAL AND METHODS: In a prospective study, 105 consecutive patients who underwent surgical decompression (laminectomy with facet-preserving technique, but no fusion) were evaluated at follow-up examinations 4 months and 1, 2, and 5 years after surgery. At the follow-up examinations, the patient's opinion on the surgical result was registered, using a four-grade scale. The occurrence of pain at rest and at night was registered, as well as the patient's walking ability. Statistical analysis was performed, relating the surgical results to patient age, gender, preoperative duration of symptoms and radiographically observed constriction as described in Part I of this study. The radiologist was blinded to patient outcome. Logistic regression analysis was performed.

RESULTS: During the follow-up period, 19 patients underwent reoperation, consisting of fusion to treat lumbar pain (n = 4), repeat decompression because of progressive stenosis (n = 13), and repairs in response to surgical complications (n = 2). Follow-up results: The result, related to the recurrence of leg symptoms, deteriorated with passing time. Excellent results were reported by 63% to 67% at 4-month and 2-year follow-ups compared with 52% at the 5-year follow-up. There was a correlation between the constriction of the spinal canal and the outcome at all intervals. Patients with an anteroposterior diameter of 6 mm or less at the narrowest site had significantly better results. The logistic regression analysis demonstrated a significant correlation between a severe reduction of the anteroposterior diameter and excellent results and a tendency toward better results in patients with a shorter preoperative duration of symptoms. Improvement of walking ability was also associated with a pronounced constriction of the spinal canal.

CONCLUSION: The results after surgical decompression in patients with central spinal stenosis deteriorated with time. There was a significant correlation between good result and pronounced constriction of the spinal canal. Patients with a preoperative duration of symptoms of less than 4 years and patients with no preoperative back pain tended to have better surgical outcomes. The reoperation rate was 18% within 5 years. When surgery for spinal stenosis is contemplated, these prognostic factors should be taken into consideration: The "ideal patient" has a pronounced constriction of the spinal canal, insignificant lower back pain, no concomitant disease affecting walking ability, and a symptom duration of less than 4 years.