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

Abstract

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.

Figure 1:

Selection of articles for the meta-analysis. MIS = minimally invasive surgery.

Figure 2:

Risk-of-bias assessment of randomized controlled trials included in the meta-analysis. One trial had a low risk of bias,^,, 10 had a high risk of bias,^–,,–, and 3 had an uncertain risk of bias.^,,

Figure 3:

Funnel plot of long-term function in trials of minimally invasive surgery versus conventional open surgery for cervical (green circles) and lumbar (blue diamonds) discectomy. SMD = standardized mean difference.

Figure 4:

Pooled long-term (≥ 1 yr) function following minimally invasive surgery (MIS) and conventional open surgery for cervical and lumbar discectomy. Red lines show a zone of clinical equivalence based on a minimal important difference of 10 points on the Oswestry Disability Index. Standardized mean differences greater than zero favour MIS. CI = confidence interval.

Figure 5:

Pooled long-term (≥ 1 yr) pain in extremities following minimally invasive surgery (MIS) and conventional open surgery for cervical and lumbar discectomy. The cervical studies reported on pain in the upper extremities, and the lumbar studies reported on pain in the lower extremities. Red lines show a zone of clinical equivalence based on a minimal important difference of 2.5 points on the visual analogue scale. Standardized mean differences less than zero favour MIS. CI = confidence interval.

Figure 6:

Pooled long-term (≥ 1 yr) axial pain following minimally invasive surgery (MIS) and open surgery for cervical and lumbar discectomy. The cervical studies reported on neck pain and the lumbar studies reported on back pain. Red lines show a zone of clinical equivalence based on a minimal important difference of 3.5 points on the visual analogue scale. Standardized mean differences less than zero favour MIS. CI = confidence interval.