Use of spontaneous electromyography during revision and complex total hip arthroplasty.

Intraoperative peripheral nerve injury is a serious potential complication of orthopaedic surgery and various intraoperative neurophysiologic monitoring techniques have been used to avoid this complication. Although somatosensory evoked potentials have been used effectively in spinal surgery, the efficacy of this technique has not been demonstrated in total hip arthroplasty. Spontaneous electromyography is a promising, alternative nerve monitoring technique. This technique was used in 44 consecutive revision and complex hip arthroplasty procedures. Five cases demonstrated sustained electromyography activity during surgery that subsided after retractors were removed and the limb brought into an anatomic position. In none of these five cases was there any evidence of clinical neurologic dysfunction after surgery. One patient developed causalgia without any motor deficit, but had no sustained electromyography activity during surgery. Spontaneous electromyography provides real-time monitoring of nerve function that allows immediate corrective action to be taken before nerve injury occurs.