Lateral femoral cutaneous nerve impairment after direct anterior approach for total hip arthroplasty.

The anterior supine approach for total hip arthroplasty (THA) offers the advantage of operating through a true intravascular and intranervous plane, but it places the lateral femoral cutaneous nerve at risk. The purpose of this study was to identify the incidence of and impairment relating to injury of the lateral femoral cutaneous nerve. We performed a retrospective chart review of 81 hips undergoing anterior supine THA from November 2005 through May 2007 to determine operative time, estimated blood loss, fluoroscopic time, type of anesthesia used, intraoperative complications, and postoperative systemic and wound complications. Postoperative radiographs were evaluated for leg-length discrepancy, acetabular inclination and anteversion, and femoral stem position. Patients were reassessed at 6 weeks, 3 months, 6 months, 1 year, and 2 years. At each visit, patients were questioned about numbness or paresthesias in the distribution of the lateral femoral cutaneous nerve; if present, the patient outlined the area with a marking pen. This area was photographed, and data were collected. No hip had frank numbness; 12 hips (14.8%) had paresthesias. For those 12, symptoms resolved in 4 by 6 months, in 6 by 1 year, and in 10 (83.3%) by 2 years; 2 remained unresolved. No significant difference was found between patients with and without paresthesias or between patients with resolved or unresolved paresthesias. Impaired sensation did not appear to affect functional outcome or Harris Hip Score. Incision position, dissection plane, retractor placement, tension and soft tissue handling, and surgeon experience may affect incidence of injury to the lateral femoral cutaneous nerve.