Orthopedic Implants Induced Unintended Nerve Stimulation During Transcutaneous Electrical Nerve Stimulation Treatment

Transcutaneous electrical nerve stimulation (TENS) is a widely used modality for pain relief and neuromuscular rehabilitation. However, the presence of implantable orthopedic devices can significantly distort the surrounding electric field, potentially leading to unintended neuronal activation. This study examines the influence of such implants on nerve stimulation during TENS therapy through a combination of numerical modeling and experimental validation. Electromagnetic simulations and neurophysiological modeling using NEURON, based on an anatomically accurate human body model, demonstrate pronounced electric field distortions at the edges of implantable devices, resulting in a lowered activation threshold for adjacent neurons. These findings are corroborated by phantom experiments, which show substantial alterations in electric field distribution in the presence of orthopedic plates and screws. The results suggest that TENS application should maintain a safe distance from implantable devices to minimize the risk of inadvertent nerve activation.