Non-invasive electrical stimulation as an adjunct to fusion does not appear to offer any meaningful increase in fusion rate, although further and better quality research is needed. This is according to findings of a meta-analysis which were recently published by Abhijith Matur (University of Cincinnati College of Medicine, Cincinnati, USA) et al in the Journal of Neurosurgery: Spine.
The study authors note that the meta-analysis “does not support routine use of these [non-invasive electrical stimulation] devices to augment fusion rates, although the data are limited by a high risk of bias and a small number of available studies.”
The goal of the systematic review and meta-analysis was to determine outcomes of non-invasive electrical stimulation used as an adjunct to fusion procedures to improve rates of successful fusion.
The PubMed, Embase, and Cochrane Clinical Trials databases were searched according to search strategy and Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.
Random-effects meta-analyses of fusion rates with the three main modalities of non-invasive electrical stimulation, capacitively coupled stimulation (CCS), pulsed electromagnetic fields (PEMFs), and combined magnetic fields (CMFs), were conducted. Retrospective studies and clinical trials were included but animal studies excluded. Risk-of-bias analysis was performed with the Risk of Bias 2 (RoB 2) and Risk of Bias in Nonrandomised Studies of Interventions (ROBINS-I) tools.
The research identified eight articles with a total of 1,216 participants meeting criteria from 213 initial results. There was a high overall risk of bias identified for the majority of randomised studies and no meta-analysis could be performed for CCS as only one study was identified.
Meta-analysis of six studies of fusion rates in PEMF did not find any difference between treatment and control groups (odds ration [OR] 1.89, 95% confidence interval [CI] 0.36–9.80, p=0.449). In addition, meta-analysis of two studies of CMF found no difference in fusion rates between control and treatment groups (OR 0.9, 95% CI 0.07–11.93, p=0.939). Subgroup analysis of PEMF was limited given the small number of studies and patients, although significantly increased fusion rates were seen in some subgroups, say the authors.
Speaking to Spinal News International, Matur said: “This meta-analysis is important because it highlights the need for more evidence with regards to the efficacy of devices used for non-invasive electrical stimulation when used to augment fusion. Although these devices are easily given to patients and have minimal side effects, it is important to consider that these are also expensive devices.
“We found no evidence that non-invasive electrical stimulation increases rates of fusion and thus recommend using them with caution considering the high costs. Although some subgroups of patients were found to have significantly higher rates of fusion associated with PEMF, these patients largely came from studies which are now decades old and the subgroup analysis could only be based on the subgroups that the studies in the meta-analysis chose to report.
“Further studies will be needed to determine whether subgroups such as patients undergoing interbody fusion will benefit from PEMF or other non-invasive electrical stimulation modalities.”
