A double-blind study of capacitively coupled electrical stimulation as an adjunct to lumbar spinal fusions

A randomized double-blind prospective comparison with a placebo control. This report of the results is the first in an ongoing study.

To evaluate the effect of noninvasive capacitively coupled electrical stimulation on the success rate of lumbar spine fusion surgery, and to compare active with placebo stimulators as adjuncts to contemporary fusion techniques.

Previous studies have established the effectiveness of direct current and electromagnetic field stimulation as adjuncts for some forms of spinal fusion. None of the previous placebo-controlled studies on external bone stimulation included posterolateral fusion techniques, and most were conducted with prior generations of internal fixation hardware.

The investigation was conducted by 28 U.S. surgeons. Patients with a primary diagnosis of degenerative disc disease with or without other degenerative changes were selected. The study protocol defined success as a clinical outcome rated as excellent or good and a fusion documented as solid by both the investigator and the blinded independent radiologist. Disagreements on radiographic success were resolved by a second blinded independent reviewer.

For the 179 patients who completed treatment and evaluation, the overall protocol success rate (both clinical and radiographic results rated as successes) was 84.7% for the active patients and 64.9% for the placebo patients. This difference is highly significant according to the Yates corrected chi-square test (P = 0.0043). Best improvements in patient outcomes (20% or greater success rate) occurred when active stimulation was used in conjunction with posterolateral fusion (P = 0.006) and when internal fixation also was incorporated (P = 0.013).

This study was consistent in that active stimulation improved results for each stratification, although some strata had insufficient numbers of patients for the results to have statistical significance. Improved success rates when capacitively coupled stimulation is added to internal fixation are hypothesized to result from overcoming the biochemical effects of stress shielding.

Capacitively coupled stimulation is an effective adjunct to primary spine fusion, especially for patients with posterolateral fusion and those with internal fixation.