Session VIII - Pelvis

Iatrogenic Nerve Injury during Acetabular Fracture Surgery: A Comparison of Monitored and Unmonitored Patients

George J. Haidukewych, MD; Julia M. Scaduto, ARNP; Thomas G. DiPasquale, DO; Dolfi Herscovici, Jr., DO; Roy W. Sanders, MD, Florida Orthopaedic Institute, Tampa, FL

Purpose: Controversy surrounds the use of intraoperative nerve monitoring to decrease the incidence of iatrogenic nerve injury during acetabular fracture surgery. The purpose of this study was to review our experience with iatrogenic nerve injuries and the efficacy of intraoperative monitoring in a large consecutive series of operatively treated acetabular fractures.

Patients and Methods: Between 1/1/92 and 12/31/98 256 consecutive acetabular fractures were operatively treated at our level 1 trauma center. 143 patients were not monitored and 113 patients were monitored with SSEP or a combination of SSEP and EMG. Four patients were excluded >from the study due to inadequate documentation of their neurologic status. Thus 140 unmonitored procedures and 112 monitored procedures were available for review. Preoperative and postoperative neurovascular examinations, fracture type, use of traction, dislocation, operative approach and complications were analyzed. Patients with documented iatrogenic nerve injuries that underwent unmonitored procedures were re-examined. Motor strength, sensation, the need for gait aids, orthoses, analgesics and extent of recovery was evaluated.

Results: A traumatic nerve palsy was present in 11 of 140 (7.9%) unmonitored fractures and 13 of 112 (11.6%) monitored fractures (p=0.314). For the group as a whole there were 14 iatrogenic sciatic nerve palsies in 252 cases (5.6%). There were 4 iatrogenic sciatic palsies (2.9%) in the unmonitored group and 10 iatrogenic palsies (8.9%) in the monitored group (p=0.037). In the unmonitored group, 1/81 Kocher Langenbeck approaches (1.2%), 2/52 ilioinguinal approaches (3.9%), and 1/3 extended iliofemoral approaches developed a sciatic palsy. In the monitored group, 6/77 Kocher Langenbeck approaches (7.8 %), 3/25 ilioinguinal approaches (12%), and 1/6 combined approaches (16.7%) developed a sciatic palsy. In seven of the ten iatrogenic palsies in the monitored group, the intraoperative monitoring showed no significant abnormalities. 76 patients were monitored with SSEP alone, 9 had iatrogenic injuries (11.8%). 36 patients were monitored with SSEP and EMG, one had an iatrogenic injury (2.8%) (p=0.164). Clinical follow up was available for three of the four patients with iatrogenic injuries in the unmonitored group,. The mean clinical follow up was 27 months (8-60 months). Two patients had full motor and sensory recovery at a mean of 6 months. One had no recovery at 14 months and required an AFO for ambulation. None required analgesics for neurogenic pain or gait aids due to motor weakness.

Conclusions: The use of intraoperative nerve monitoring was not effective in decreasing the rate of iatrogenic sciatic palsy and additionally demonstrated a high rate of false negative readings. The addition of EMG to the monitoring protocol provided no advantage over unmonitored injury rates. Sciatic nerve injury was more common in ilioinguinal approaches in both groups, likely due to reduction techniques for the posterior column performed with the hip flexed, placing the sciatic nerve under tension.