Background: Nerve palsy is a potentially devastating complication
following total hip arthroplasty. The purpose of this study was to
retrospectively identify risk factors for, and the prognosis associated with,
a motor nerve palsy following primary total hip arthroplasty.
Methods: Between 1970 and 2000, 27,004 primary total hip
arthroplasties were performed at our institution. Forty-seven patients (0.17%)
with postoperative motor nerve dysfunction were identified by a review of the
complications log of a total joint database. The medical record of each
patient provided the data for this study. The average age of the patients was
fifty-seven years at the time of surgery. The patients had serial clinical
examinations for a minimum of two years, or until neurologic recovery or
death. The nerve palsies were classified as complete or incomplete, and only
patients with objective motor weakness were included in the study. The limb
lengths were measured on preoperative and postoperative radiographs, and those
data were then compared with the limb lengths in a matched cohort of patients
who had not sustained a nerve injury after a primary total hip arthroplasty.
The extent of neurologic recovery, the need for braces or walking aids, and
the use of medications for neurogenic pain were evaluated.
Results: There were twenty-nine complete motor nerve palsies
(sixteen peroneal, eleven sciatic, and two femoral) and eighteen incomplete
motor nerve palsies (fourteen peroneal, three sciatic, and one femoral). A
preoperative diagnosis of developmental dysplasia of the hip (p = 0.0004) or
posttraumatic arthritis (p = 0.01), the use of a posterior approach (p =
0.032), lengthening of the extremity (p < 0.01), and cementless femoral
fixation (p = 0.03) were associated with a significantly increased odds ratio
for the development of a postoperative motor nerve 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. Seven of the eighteen patients with an incomplete palsy fully
recovered their preoperative strength. Twenty-one patients required walking
aids, and fifteen required permanent use of an ankle-foot orthosis. Five
patients required daily medication for chronic neurogenic pain.
Conclusions: Motor nerve palsy is uncommon following primary total
hip arthroplasty. 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. The majority of the motor nerve
deficits in our series, whether complete or incomplete, did not fully
Level of Evidence: Prognostic Level II. See Instructions
to Authors for a complete description of levels of evidence.