Dynamic interspinous process stabilization: review of complications associated with the X-Stop device

Abstract

<jats:sec> <jats:title>Object</jats:title> <jats:p>The X-Stop interspinous device is designed for the treatment of patients with neurogenic intermittent claudication due to lumbar spinal stenosis. It distracts the posterior elements of adjacent vertebral bodies, unloading the intervertebral disc, limiting spinal extension, and improving central canal and neuroforaminal stenosis. In this paper, the authors reviewed the complications and failure/reoperation rates in a small series of patients and compared their results with other reported complication and failure/reoperation rates.</jats:p></jats:sec> <jats:sec> <jats:title>Methods</jats:title> <jats:p>The medical records of all patients who underwent placement of the X-Stop device for the treatment of NIC at the authors' institution were retrospectively evaluated, and demographic information, diagnosis, and preoperative pain levels were recorded. Postoperatively, patients subjectively graded the percentage (0–100%) of improvement in pain as well as the amount of residual pain and underwent imaging at 1-, 3-, and 6-month intervals. Approximately 4 years after X-Stop placement, information on long-term outcomes was obtained from patient medical records or additional follow-up.</jats:p></jats:sec> <jats:sec> <jats:title>Results</jats:title> <jats:p>Thirteen patients (8 men and 5 women) underwent placement of the X-Stop device. Central canal stenosis with bilateral foraminal stenosis was diagnosed in all patients: 9 (69%) of 13 had severe stenosis and 4 (31%) of 13 had moderate stenosis. Five patients (38%) also had associated Grade I spondylolisthesis. Nine patients underwent placement of the X-Stop device at the L4–5 interspinous space and 4 at both the L3–4 and L4–5 levels. The average duration of follow-up was 42.9 months (range 3–48 months). Initially, pain improved an average of 72% (range 50–100%) in these patients; however, preoperative pain returned in 77% of the patients (10 of 13). The overall complication rate was 38%, including 3 spinous process fractures (23%) and 2 instances of new-onset radiculopathy (15%). The ultimate failure rate requiring additional spinal surgery was 85% (11 of 13 patients). These complication and failure rates are much higher than those previously reported.</jats:p></jats:sec> <jats:sec> <jats:title>Conclusions</jats:title> <jats:p>Overdistraction, poor bone density, poor patient selection, and preexistent adjacent foraminal stenosis may all be factors in the development of the aforementioned complications. Thus, careful attention should be paid preoperatively to adjacent-level disease, bone density, appropriate implant size, and optimal patient selection.</jats:p></jats:sec>

Failure rates and complications of interspinous process decompression devices: a European multicenter study

“…38 Bowers et al showed a long-term complication rate of 38%, with 11 (85%) of 13 patients requiring additional spine surgery after X-Stop placement. 5 These authors observed a higher rate of spinous process fracture (23%) than previously reported.…”

“…In another study, since 80% of patients with Grade I spondylolisthesis required additional surgery after IPD placement, the authors supported the recommendation not to use X-Stop in patients with spondylolisthesis. 5 Stucki et al reported 2-year outcomes in 197 patients with neurogenic intermittent claudication treated with lumbar laminectomy versus X-Stop-treated patients, demonstrating higher Zurich Claudication Questionnaire success rates than the scores for laminectomy patients. 40 Turner and colleagues evaluated the cost-effectiveness of X-Stop and laminectomy surgery during the index hospitalization for the treatment of 33 patients with lumbar spinal stenosis in the US.…”

Clinical evaluation of the preliminary safety and effectiveness of a minimally invasive interspinous process device APERIUS® in degenerative lumbar spinal stenosis with symptomatic neurogenic intermittent claudication

“…Spinous process fracture, observed here and in other studies of IPDs, may be considered as potentially risk related specifically to interspinous process decompression, both in terms of the procedure and the device itself [11][12][13][14]. Fracture rates, and the means of detecting fractures, vary between studies, making direct comparisons difficult.…”

Determination of the biomechanical effect of an interspinous process device on implanted and adjacent lumbar spinal segments using a hybrid testing protocol: a finite-element study

“…For example, Miller et al 13 reported 2 cases of ISP failure in which gradual erosion of the spinous processes occurred because of consistent motion at the spacer-bone interface. Furthermore, Bowers et al 2 published medical records of complications associated Finite-element study of iSp devices using a hybrid protocol with implantation of the X-Stop device. They reported the fracture of spinous processes in 3 of 13 patients and suggested possible causes of fracture, including the degree of osteoporosis and over-distraction of the interspinous space with an oversized implant.…”