Review Question - QID 610

The likelihood of complete functional recovery to preoperative strength levels is 35% to 40%.

Nerve palsy is an uncommon but acknowledged complication of total hip replacement. The overall prevalence is approximately 1%. The sciatic nerve, or the peroneal division of the sciatic nerve, is involved in nearly 80% of cases. The risk of nerve palsy in association with total hip replacement is increased for female compared with male patients, with a diagnosis of developmental dysplasia, and with patients undergoing revision surgery. A preoperative diagnosis of developmental dysplasia of the hip or posttraumatic arthritis, the use of a posterior approach, lengthening of the extremity, and use of an uncemented femoral implant increased the odds ratio of sustaining a motor nerve palsy (in Farrell study). In the majority of cases, the origin of the palsy is unknown. Because peripheral nerves are sensitive to compression, unrecognized compression may play a role in these cases.

Farrell performed a retrospective review of 27,004 primary THA’s done at Mayo. There was a 0.17% incidence rate of postoperative motor nerve dysfunction (29 pts with complete palsy, 18 with incomplete palsy). Of the twenty-eight patients with a complete palsy who were available for follow-up, only ten (36%) had complete recovery of motor strength, which took an average of 21.1 months.

Another study by Schmalzried et. al states a prevalence of 1%, with the sciatic nerve involved in 80% of those palsies. Complete, or essentially complete, recovery occurs in approximately 41% and another 44% have only a mild deficit. Patients with some motor function immediately after the operation and those who recover some motor function within approximately 2 weeks of surgery have a good prognosis for recovery.