The efficacy of electrical spinal fusion stimulators on fusion rates: a meta-analysis

Abstract

Background: Previous studies have investigated the clinical effectiveness of electrical stimulation. However, minimal aggregate data from randomized controlled trials (RCT) exist to determine the overall efficacy of stimulators on spinal fusion outcomes. Thus, a meta-analysis of RCTs was undertaken to elucidate the effect of spinal fusion stimulators on fusion rates after spinal fusion procedures. Methods: This meta-analysis followed Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. RCTs that compared fusion rates between cohorts receiving either electrical stimulation or a placebo/control following spinal fusion were included. Studies were obtained from literature searches of PubMed and MEDLINE databases. Articles without 1 yr follow-up or complete randomization were excluded. The primary outcome was fusion rate. A meta-analysis on relative risks for fusion was performed. The summary estimate was derived using Mantel-Haenszel methods. Results: Out of six RCTs, fusion rates ranged from 35.4% to 90.6% in stimulation groups, and 33.3% to 92.8% in control groups. There was no significant difference in fusion rates between spinal stimulator and control groups (P=0.067). Four of six studies exhibited a variety of study population characteristics, including a mixture of primary and revision spinal fusions, single-level and multi-level procedures, and electrical stimulation types. Conclusions: The results from the present study suggest no significant effect of spinal fusion stimulators on rates of spinal fusion when compared to control treatments. Physicians should use caution when interpreting these studies. Further RCTs demonstrating uniformity are necessary to better understand the effects of electrical stimulators on spinal fusion.