Implantable direct current spinal fusion stimulators do not decrease implant-related infections in a rabbit model

Electrical current detaches bacterial biofilm from implanted instrumentation. Hypothetically, this can decrease implant-related infection and allow retention of instrumentation in cases of postoperative wound infections. We conducted a prospective animal study to investigate whether a 60-μAmp implantable direct current (DC) fusion stimulator decreases implant-related infection rates in a multilevel fixed-implant postoperative spinal wound infection model in rabbits. Three dorsal sites, T13, L3, and L6, were instrumented in each rabbit. A 60-μAmp DC fusion stimulator was implanted in a subcutaneous pouch lateral to the instrumented sites, and leads were connected to 2 of 3 sites in each rabbit. All sites were inoculated with methicillin-sensitive Staphylococcus aureus (MSSA). Rabbits were euthanized at 7 days, and cultures were obtained from the surgical sites, including wound swab, bone, and implants. No significant reduction was observed in postoperative infection rates of bone or implant with 60-μAmp DC (95% and 77%, respectively) compared with no current (91% and 82%, respectively) (P > .5). No significant difference was observed in bacterial load (Ps = .25-.72) between sites receiving DC and control sites. Currently used 60-μAmp DC implantable spinal fusion stimulators do not significantly reduce the rate of postoperative implant-related spinal wound infections in a rabbit model.