Decompression alone versus interspinous/interlaminar device placement for degenerative lumbar pathologies: Systematic Review and Meta-Analysis

Introduction: Interspinous (ISD) and interlaminar devices (ILD) are marketed as minimally invasive mechanisms for alleviating symptoms in patients with degenerative lumbar spine pathologies causing cauda equina or nerve root compression. There have been inadequate comparisons of ISDs/ILDs to decompression alone.

Methods: Articles directly comparing outcomes for patients treated with decompression alone or with an ISD/ILD with or without concurrent decompression were identified. Outcomes of interest included postoperative back and leg pain scores, ODI, SF36, Zurich Claudication Questionnaire (ZCQ) scores, EQ5D scores, perioperative complications, and total treatment costs. Outcomes were analyzed at < 6 weeks, 3-months, 6-months, 1-year, 2-year, and last follow-up (LFU). Analyses were performed using RevMan software with random effects modeling.

Results: Of 1699 studies, 29 met criteria for inclusion. Compared to decompression-alone, ILD/ISD had significantly greater improvement in leg pain at 3mo (-1.43; [-1.78, -1.07]; p< 0.001), 6mo (-0.89; [-1.55, -0.24]; p=0.008), and 12mo (-0.97; [-1.25, -0.68]; p< 0.001), but not 2yr (p=0.22) or LFU (p=0.09). Back pain scores were better in the ISD/ILD group only at 1yr (-0.87; [-1.62, -0.13]; p=0.02). SF-36 physical component scores nor ZCQ symptom severity scores differed significantly at any examined endpoint. ZCQ physical function scores showed greater improvement for decompression alone at 6mo (0.35; [0.07, 0.63]; p=0.01) and 12mo (0.23; [0.00, 0.46]; p=0.05), while ODI and EQ-5D scores favored ILD/ISD at all time points, with the exception of 6mo ODI scores (p=0.07), though none reached the minimum clinically important difference (MCID). Perioperative complications were nonsignificantly higher in the ISD/ILD group (p=0.41), while reoperations (OR=1.75; [1.23, 2.48]; p=0.002) and total care costs (standardized mean difference 1.19; [0.62, 1.77]; p< 0.001) were significantly higher in the ILD/ISD groups.

Conclusion : Patient reported outcomes are largely similar between patients treated with decompression alone and those treated with ILD/ISD for degenerative lumbar pathologies; none of the observed differences reached accepted MCIDs. Costs and rates of reoperation are significantly higher in the ISD/ILD group though, suggesting current evidence does not support ILD/ISD use as a cost-effective alternative to surgical decompression.