Non-contact electrical stimulation via a Vector-potential transformer promotes bone healing in drill-hole injury model.

INTRODUCTION: We investigated the effects of non-contact electrical stimulation via a Vector-potential (VP) transformer, a novel physical therapy device, on bone healing in drill-hole injury models. MATERIALS AND METHODS: Six-week-old male Wistar rats, after a one-week acclimation period, were divided into three groups: the control group (CO), the bone injury group (BI), in which a drill-hole injury was created, and the VP stimulation group (VP), which received non-contact electrical stimulation via a VP transformer after bone injury. In the VP group, rats underwent stimulation at 200 kHz for 30 minutes per day, seven days per week. RESULTS: The VP group exhibited increased bone formation as early as day 7 post-injury, with significantly higher bone volume than the BI group at all time points (day 7: p = 0.0003; day 14: p = 0.0024; day 21: p = 0.0001). By day 21, the VP group showed lighter toluidine blue staining and reduced biglycan immunoreactivity compared to the BI group. Bone mineral density also increased (p = 0.0008). Osteoblasts in the VP group displayed abundant cytoplasm and a high capacity for osteocalcin synthesis. Additionally, the VP group demonstrated increased expression of Bglap (day 5: p = 0.0068; day 7: p = 0.0096) and Ctsk (day 7: p = 0.0329; day 14: p = 0.0171), along with a higher number of TRAP-positive osteoclasts (day 21: p = 0.0159) compared to the BI group. CONCLUSION: Non-contact electrical stimulation via a VP transformer promotes bone healing in drill-hole injury models.