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

## TL;DR

A new non-contact electrical stimulation device called a Vector-potential transformer helps accelerate bone healing in rats with drill-hole injuries.

## Contribution

The study introduces a novel non-contact electrical stimulation device that significantly enhances early bone healing in a rat injury model.

## Key findings

- VP stimulation increased bone volume significantly at all measured time points after injury.
- VP group showed increased bone mineral density and enhanced osteoblast activity.
- VP stimulation increased expression of bone-related genes like Bglap and Ctsk.

## Abstract

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.

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.

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.

Non-contact electrical stimulation via a VP transformer promotes bone healing in drill-hole injury models.