Study design: Prospective randomized controlled study.
Objective: To compare the outcome of indirect decompression by means of the X-Stop (Medtronics Inc., Minneapolis, MN) implant with conventional decompression in patients with neurogenic intermittent claudication due to lumbar spinal stenosis.
Summary of background data: Decompression is currently the "gold standard" for lumbar spinal stenosis but is afflicted with complications and a certain number of dissatisfied patients. Interspinous implants have been on the market for more than 10 years, but no prospective study comparing its outcome with decompression has been performed.
Methods: After power calculation, 100 patients were included: 50 in the X-Stop group and 50 in the decompression group. Patients with symptomatic 1- or 2-level lumbar spinal stenosis and neurogenic claudication relieved on flexion were included. X-Stop operations were performed under local anesthesia.The mean patient age was 69 (49-89) years, and the male/female distribution was 56/44. Minimal dural sac area was in all cases except two 80 mm or less.The noninferiority hypothesis included 6, 12, and 24 months of follow-up, and included. intention-to-treat as well as as-treated analyses.The primary outcome meansure was the Zürich Claudication Questionnaire, and the secondary outcome measures was the visual analogue scale pain, Short-Form 36 (SF-36), complications, and reoperations.
Results: The primary and secondary outcome measures of patients in both groups improved significantly. The results were similar at 6, 12, and 24 months and at no time point could any statistical difference between the 2 types of surgery be identified. Three patients (6%) in the decompression group underwent further surgery, compared with 13 patients (26%) in the X-Stop group (P = 0.04). Results were identical in intention-to-treat and as-treated analyses.
Conclusion: For spinal stenosis with neurogenic claudication, decompressive surgery as well as X-Stop are appropriate procedures. Similar results were achieved in both groups, however, with a higher number of reoperations in the X-Stop group. Patients having X-Stop removal and decompression experienced results similar to those randomized to primary decompression.
Level of evidence: 1.