Efficacy of electrical stimulation for spinal fusion: a meta-analysis of fusion rate

BACKGROUND CONTEXT: Many clinical studies have demonstrated the effectiveness of electrical stimulation as an adjunct to spinal arthrodesis. However, there is a paucity of comparative data among different electrical stimulation techniques. PURPOSE: To compare the efficacy of three electrical stimulation methods for spinal fusion based on the literature review. SAMPLE: Twenty-one articles, meeting all the inclusion criteria, were selected. A total of 1,381 patients were evaluated. STUDY DESIGN: Systematic literature review and meta-analysis. OUTCOME MEASURES: Fusion rates were determined using radiography or computed tomography. METHODS: A systematic literature review was conducted on spinal fusion surgeries with the aid of electrical stimulation devices. Only studies applying radiography or computed tomography for fusion assessment were included. Study groups were divided based on electrical stimulation types and were further grouped by other patient characteristics. Pooled estimates and 95% confidence intervals (CIs) were calculated by random-effects meta-analysis. RESULTS: The pooled fusion rate for all studies was 85% (95% CI, 79-90). There were 14 direct current, 1 capacitive coupling (CC), and 10 inductive coupling studies in our analysis, with combined fusion rate of 85% (95% CI, 76-91), 90% (95% CI, 83-95), and 85% (95% CI, 74-93), respectively. There were no statistically significant differences among the three electrical stimulation methods. Further subgroup analysis suggested that age, sex, smoking status, surgery type, fusion levels, fusion column, implant use, and graft type did not significantly influence the fusion rate. CONCLUSIONS: The three types of electrical stimulation devices had similar clinical efficacy in promoting bone growth for spinal fusion. The results for CC stimulation should be applied with caution as only one relevant study was identified. (C) 2013 Elsevier Inc. All rights reserved.