Implant Survival Analysis and Failure Modes of the X-Stop Interspinous Distraction Device

Study Design. Retrospective cohort study. Objective. To review the clinical outcome, implant survivorship and reasons for failure after X-Stop implantation. Summary of Background Data. Confl icting data exist concerning clinical outcome of the X-Stop interspinous spacer and little information is being published about implant survivorship and the need for revision surgery. Methods. This retrospective review evaluated 46 patients who underwent implantation of the X-Stop interspinous spacer for the treatment of neurogenic claudication. After a mean follow-up of 40 months, pain levels, 36-Item Short Form Health Survey (SF-36), Oswestry Disability Index (ODI), and the need for subsequent surgery were assessed and a Kaplan-Meier survivorship analysis was performed. Results. Within the follow-up period, the revision rate was found to be 30.4%. Lack of improvement at 6-week follow-up correlated well with subsequent revision surgery, which predominantly took place within 12 months after the index surgery. In patients who did not need to undergo revision surgery, clinical outcome parameters improved signifi cantly. Kaplan-Meier survivorship analysis predicted an implant survival probability of 0.68 at 48 months postoperatively. Conclusion. Clinical outcome after X-Stop implantation might be considerably less favorable than when it was being published previously. Patient selection might be a reason for early revision surgery. More criteria for better X-Stop indications might be needed.