Interspinous Process Decompression With the X-STOP Device for Lumbar Spinal Stenosis A 4-Year Follow-Up Study

X-STOP is the first interspinous process decompres- sion device that was shown to be superior to nonoperative therapy in patients with neurogenic intermittent claudication secondary to spinal stenosis in the multicenter randomized study at 1 and 2 years. We present 4-year follow-up data on the X-STOP patients. Patient records were screened to identify potentially eligible subjects who underwent X-STOP implanta- tion as part of the FDA clinical trial. The inclusion criteria for the trial were age of at least 50 years, leg, buttock, or groin pain with or without back pain relieved during flexion, being able to walk at least 50 feet and sit for at least 50 minutes. The exclusion criteria were fixed motor deficit, cauda equina syndrome, previous lumbar surgery or spondylolisthesis greater than grade I at the affected level. Eighteen X-STOP subjects participated in the study. The average follow-up was 51 months and the average age was 67 years. Twelve patients had the X-STOP implanted at either L3-4 or L4-5 levels. Six patients had the X-STOP implanted at both L3-4 and L4-5 levels. Six patients had a grade I spondylolisthesis. The mean preoperative Oswestry score was 45. The mean postoperative Oswestry score was 15. The mean improvement score was 29. Using a 15-point improvement from baseline Oswestry Disability Index score as a success criterion, 14 out of 18 patients (78%) had successful outcomes. Our results have demonstrated that the success rate in the X-STOP interspinous process decompression group was 78% at an average of 4.2 years postoperatively and are consistent with 2-year results reported by Zucherman et al previously and those reported by Lee et al. Our results suggest that intermediate-term outcomes of X-STOP surgery are stable over time as measured by the Oswestry Disability Index. S urgical decompression with or without fusion is the standard surgical treatment for patients with moder- ate to severe lumbar spinal stenosis. While offering the potential to improve the quality of life for the patients, it also has the potential for significant complications, especially when a fusion is performed. Postoperative complications may include the cardiovascular and pul- monary complications of general anesthesia, infection, iatrogenic instability, pseudarthrosis, hardware failure, and the need for future surgery because of the develop- ment of new diseases at the same or adjacent levels. An extensive meta-analysis of the literature of spinal stenosis surgery by Turner et al in 1992 showed the following complication rates for lumbar decompressive surgery: perioperative mortality 0.3%, dural tears 5.9%, deep infection 1.1%, superficial infection 2.3%, and deep vein thrombosis 2.7%, for an