Intraoperative monitoring of motor pathways during operative fixation of acute acetabular fractures.

OBJECTIVE: To determine whether intra-operative spontaneous electromyography (EMG) was superior to somatosensory evoked potentials (SSEP) in the prevention of iatrogenic sciatic nerve injury.

DESIGN: Prospective, consecutive.

SETTING: Tertiary referral, teaching Hospital in New York City.

PATIENTS: Seventy-four patients with acutely displaced acetabular fractures.

MAIN OUTCOME MEASURE: Group A consisted of 24 patients who underwent intraoperative sciatic nerve monitoring using SSEP only. Group B consisted of 50 patients who underwent monitoring using both SSEP and spontaneous EMG. Motor potentials were recorded from the tibialis anterior, peroneus longus, abductor hallucis, and flexor hallucis longus muscles. All patients had independent preoperative and postoperative evaluations by the same neurologist.

RESULTS: One iatrogenic sciatic nerve injury occurred in group A and none in group B. Prolonged sciatic nerve compromise, demonstrated by significant intraoperative SSEP changes, occurred 2.4 times per case in group A and only 0.8 times per case in group B. In group B, spontaneous EMG noted compromise an average of 3.6 times per case (p < 0.0001).

CONCLUSIONS: The results of this study support spontaneous EMG as feasible and superior to SSEP monitoring in detecting intraoperative sciatic nerve comprise in acute acetabular fracture surgery. Spontaneous EMG permits earlier detection of intraoperative sciatic nerve comprise, allowing a more rapid response of the surgical team to noxious nerve stimuli. This may prevent permanent neurologic sequellae.