Comparison of two FDA-approved interspinous spacers for treatment of lumbar spinal stenosis: Superion versus X-STOP—a meta-analysis from five randomized controlled trial studies

BACKGROUND Decompressive laminectomy (DI) is a standard operation for lumbar spinal stenosis (LSS) patient with severe claudication symptoms for many years. However, patients whose symptom severity does not meet undergoing invasive surgery make therapeutic options into dilemma. Interspinous spacers (ISP) bridge the gap between surgical interventions and CC in management of LSS. In our study, we aim to systematically assess the two FDA-approved interspinous spacers for treatment of lumbar spinal stenosis: Superion versus X-STOP. METHODS Electronic databases, including PubMed, Embase, MEDLINE, Cochrane Library were searched to retrieve clinical trials concerning the comparison between Superion and X-STOP in treatment for lumbar spinal stenosis before April 2017. The following outcome measures were extracted: (1) Zurich Claudication Questionnaire (ZCQ) patient satisfaction score, (2) axial pain severity, (3) extremity pain severity, (4) back-specific functional impairment, (5) reoperation, and (6) complication. The data analysis was conducted with Review Manager 5.3. RESULTS Five randomized controlled trials (RCTs) with 1118 patients were included in this meta-analysis. The pooled analysis indicated that the Superion group is superior to X-STOP in axial pain severity (SMD: 0.03; 95% CI 0.15, 0.45; p < 0.0001, I2 = 41%, p = 0.16), ZCQ patient satisfaction score (SMD: 0.23; 95% CI 0.08, 0.38; p = 0.002, I2 = 0%, p = 0.61). However, Superion group showed similarity outcome in extremity pain severity (SMD: 0.18; 95% CI - 0.06, 0.43; p = 0.14, I2 = 62%, p = 0.05), back-specific functional impairment (SMD: 0.04; 95% CI - 0.10, 0.19; p = 0.56, I2 = 0%, p = 0.77), reoperation rate (RR: 1.10; 95% CI 0.82, 1.48; p = 0.51, I2 = 19%, p = 0.30), and complication (RR: 0.98; 95% CI 0.63, 1.53; p = 0.92, I2 = 0%, p = 0.83). CONCLUSION Both the Superion and X-STOP interspinous spacers can relieve symptoms of LSS. In addition, the Superion spacer may represent a promising spacer for patient with LSS. As we know, the effectiveness and safety of ISP is still considered investigational and unfavor clinical results in the medical literature may continue to limit the appeal of IPS to many surgeons in the future. However, because of the advantage of IPS technique, it will win a wide place in the future degenerative lumbar microsurgery.