196 – ELECTRICAL STIMULATION IN SPINE FUSION: A META-ANALYSIS OF RANDOMISED CONTROLLED TRIALS

Abstract

Purpose: A significant proportion of spine fusion operations may result in a non-union. Electromagnetic stimulation is a non-invasive method used to promote spine fusion although the efficacy of its use in this regard remains uncertain. The purpose of this systematic review and meta-analysis is to evaluate the effect of electromagnetic stimulation on spine fusion.

Method: Five electronic databases (MEDLINE, Embase, CINAHL, PubMed and the Cochrane Central Register of Controlled Trials) were searched from database inception to July 2009 for randomized controlled trials of electrical stimulation and spinal fusion. In addition, we performed a hand search of four relevant journals from January 2000 to July 2009, the on-line proceedings of the North American Spine Society Annual Meeting from 2002 to 2008 and bibliographies of eligible trials. Trials randomizing adult patients undergoing any type of spine fusion to active treatment with direct current, capacitance coupled or pulsed electromagnetic field stimulation or placebo and reporting on fusion rates were included. Two independent reviewers extracted data regarding clinical outcomes, stimulation device, treatment regimen and methodologic quality.

Results: Of 1650 studies identified seven met the inclusion criteria. Electromagnetic stimulation in lumbar spine fusion was evaluated in five studies and two addressed cervical spine fusions. The use of electromagnetic stimulation in lumbar spine fusion resulted in a significant decrease in the risk of non-union (relative risk 0.60, 95% confidence interval 0.38 to 0.93, p = 0.02, I2 = 57%). The observed reduction in risk of nonunion with electromagnetic stimulation was not affected by smoking or the number of levels fused. Due to limited and conflicting trials, similar effects were not observed in the two studies evaluating cervical spine fusion rates (relative risk 0.85, 95% confidence interval 0.29 to 2.53, p = 0.77, I2 = 56%).

Conclusion: Pooled analysis shows a 40% reduction in the risk of non-union of lumbar spine fusions with the use of electromagnetic stimulation although a similar effect was not observed for fusions of the cervical spine. However, due to study heterogeneity the current indications for the use of electrical stimulation in spine fusion remain somewhat unclear.