Minimally invasive versus open surgery for cervical and lumbar discectomy: a systematic review and meta-analysis

INTRODUCTION: Minimally invasive surgery for discectomy may accelerate recovery and reduce pain, but it also requires technical expertise and is associated with increased risks. We performed a meta-analysis to determine the effects of minimally invasive versus open surgery on functional outcomes, pain, complications and reoperations among patients undergoing cervical or lumbar discectomy. METHODS: We searched MEDLINE, Embase and the Cochrane Library for reports of relevant randomized controlled trials published to Jan. 12, 2014. Two reviewers assessed the eligibility of potential reports and the risk of bias of included trials. We analyzed functional outcomes and pain using standardized mean differences (SMDs) that were weighted and pooled using a random-effects model. RESULTS: We included 4 trials in the cervical discectomy group (n = 431) and 10 in the lumbar discectomy group (n = 1159). Evidence overall was of low to moderate quality. We found that minimally invasive surgery did not improve long-term function (cervical: SMD 0.11, 95% confidence interval [CI] -0.09 to 0.31; lumbar: SMD 0.04, 95% CI -0.11 to 0.20) or reduce long-term extremity pain (cervical: SMD -0.21, 95% CI -0.52 to 0.10; lumbar: SMD 0.08, 95% CI -0.16 to 0.32) compared with open surgery. The evidence suggested overall higher rates of nerve-root injury (risk ratio [RR] 1.62, 95% CI 0.45 to 5.84), incidental durotomy (RR 1.56, 95% CI 0.80 to 3.05) and reoperation (RR 1.48, 95% CI 0.97 to 2.26) with minimally invasive surgery than with open surgery. Infections were more common with open surgery than with minimally invasive surgery (RR 0.24, 95% CI 0.04 to 1.38), although the difference was not statistically significant. INTERPRETATION: Current evidence does not support the routine use of minimally invasive surgery for cervical or lumbar discectomy. Well-designed trials are needed given the lack of high-quality evidence.