Osteocyte: the impresario in the electrical stimulation for bone fracture healing.

Delayed healing and nonunions of bone fracture are critical problems in orthopedic surgery. Electrical stimulation has been used as a therapeutic method for enhancing bone healing for a long time. Despite unanimous clinical success, the underlying mechanism concerning bone tissue in response to electrical stimulation remains poorly understood. In the meantime, emerging evidences suggest that osteocytes, with their unique location and morphologies, play an important role in regulating the behaviors of other bone cells, including osteoblasts, osteoclasts and their progenitor cells. In this paper, we hypothesize that osteocytes are the sensory cells for the electrical stimulation, and they orchestrate the whole process of new bone formation and remodeling in the electrotherapy for bone fracture. The postulated electrosensory transduction pathway might be a coupling effect of osteoblasts and osteoclasts, which is regulated by the biochemical signals expressed from osteocytes after sensing the membrane potential changes. It is believed that better understanding of this mechanism would facilitate optimizing the electrotherapy for bone disorders and assist in solving these clinical problems.