Direct anterior total hip arthroplasty (THA) is an increasingly utilized and patient-requested approach for arthroplasty carrying a unique set of complications. Injury to the lateral femoral cutaneous nerve (LFCN) can have a wide range of clinical symptoms ranging from hypesthesia to painful paresthesia. Long-term effects of this injury have not been well studied. We describe duration and severity of these symptoms and correlate their relationship with hip functional scores.
Between January 2009 and January 2016, 1665 patients with 1871 hips who underwent direct anterior THA by a single surgeon were surveyed for reported outcomes including Douleur Neuropathique 4-Interview (DN4-I), Hip Disability and Osteoarthritis Outcome Score for Joint Replacement (HOOS, JR), and Patient-Reported Outcomes Measurement Information System Short Form Global Health Assessment. The DN4-I was considered positive if 3 (or more) of 7 neuropathic pain symptoms were affirmed at present in the distribution of the LFCN of the affected leg.
Six hundred eighty patients accounting for 778 hips completed the survey. Overall, 16% of responders had positive DN4-I scores for continued neuropathic symptoms with a mean time since surgery of 3.9 years at assessment. Twenty-four percent of those responding within 2 years of surgery had positive scores compared with 15% from 2 to 4 years, 14% from 4 to 6 years, and 11% positive from 6 to 8 years after surgery. Of those with positive DN4-I scores, the most commonly affirmed neuropathic symptom was “numbness”, reported in 37% of patients. The overall average interval HOOS, JR score was 89.8. There were no differences in HOOS, JR or Patient-Reported Outcomes Measurement Information System scores for patients further out from surgery.
The most commonly experienced neuropathic symptom in the distribution of the LFCN following direct anterior THA is “numbness” that occurred in 37% of patients with a positive DN4-I score. Neuropathic symptoms improved in patients further out from surgery with pain reported in 11% of patients from 6 to 8 years postoperatively. Neuropathic symptoms significantly improve with time and appear to be independent of hip function scores.