Efficacy of Electrical Stimulation for Spinal Fusion: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Spinal fusion is one of the most common procedures performed in spine surgery. As rates of spinal fusion continue to increase, rates of complications such as nonunions continue to increase as well. Current evidence supporting the use of electrical stimulation to promote fusion is inconclusive. This review aimed to determine if postoperative electrical stimulation is more efficacious than no stimulation or placebo in promoting radiographic fusion in patients undergoing spinal fusion. We searched the Cochrane Central Register of Controlled Trials (CENTRAL), EMBASE, CINAHL and MEDLINE from date of inception to current. Ongoing clinical trials were also identified and reference lists of included studies were manually searched for relevant articles. Two reviewers independently screened studies, extracted data, and assessed risk of bias. Data were pooled using the Mantel-Haenszel method. Trialists were contacted for any missing or incomplete data. Of 1184 articles screened, 7 studies were eligible for final inclusion (n = 941). A total of 487 patients received postoperative electrical stimulation and 454 patients received control or sham stimulation. All evidence was of moderate quality. Electrical stimulation (pulsed electromagnetic fields, direct current, and capacitive coupling) increased the odds of a successful fusion by 2.5-fold relative to control (OR = 2.53, 95% CI 1.86 to 3.43, p < 0.00001). A test for subgroup interaction by stimulation type, smoking status, and number of levels fused was not significant (p = 0.93, p = 0.82 and p = 0.65, respectively). This systematic review and meta-analysis found moderate-quality evidence supporting the use of postoperative electrical stimulation as an adjunct to spinal fusion surgery. Patients treated with electrical stimulation have significantly greater rates of successful fusion. The level of evidence for this study is therapeutic level I.