Long-Term Outcomes for Lumbar Spinal Stenosis Patients Treated With X STOP®

Seven treatment success criteria were defined as follows: clinically significant improvement (at least 0.5 points) in Symptom Severity (SS) domain of Zurich Claudication Questionnaire (ZCQ), clinically significant improvement (at least 0.5 points) in Physical Function (PF) domain of ZCQ, Patient Satisfaction (PS) score of <2.5 points in ZCQ, no additional lumbar spinal stenosis surgery at the index level, maintenance of distraction, no device dislodgement, no device-related complications. All 7 criteria must be met to be considered a treatment success.

ZCQ is a validated outcomes instrument specific to lumbar spinal stenosis, and captures data in 3 distinct domains: SS, PF, and post-treatment Patient Satisfaction (PS). SS domain is based on seven questions (overall pain, pain frequency, pain in the back, pain in the leg, numbness, weakness, and balanced disturbance). The first 6 questions are scored 1 to 5. Balance disturbance is scored in a 1-3-5 scale. The SS score is the mean of all answered items in the questionnaire ranging from 1to 5. If more than two items were missing, the SS score was considered as missing. PF score is the mean of five physical function questions ranging from 1 to 4. If more than one item were missing, the PF score was considered as missing. In each domain, a lower score represents a better outcome/condition. The change is calculated as the score at 5+ years after X-STOP implantation minus the baseline score.

ZCQ is a validated outcomes instrument specific to lumbar spinal stenosis, and captures data in 3 distinct domains: SS, PF, and post-treatment Patient Satisfaction (PS). PS score is the mean of 6 questions scored from 1 to 4 if the number of responses exceeded four, a lower score represents a better outcome. Patients with mean scores <2.5 at 5 years postoperative evaluation were considered positive, which implied patient treatment satisfaction.

Quality of life was assessed by the SF-36 health survey. It includes 8 subdomains (bodily pain, physical functioning, role-physical, general health and vitality, social functioning, role-emotional, and mental health) and 2 component summaries (physical component summary [PCS] and mental component summary [MCS]). Scores for each subdomain and component summary range from 0 "worst" to 100 "best. The change from baseline to the 5 year postoperative visit for each of these domains is presented.

The surgeries that occurred subsequent to the original X-STOP implantation were categorized as revision, removal, reoperation, supplemental fixation, and other.