Prospective evaluation of lateral femoral cutaneous nerve injuries during periacetabular osteotomy

Periacetabular osteotomies (PAOs) are used to treat acetabular dysplasia in younger patients, but are not without morbidity. Lateral femoral cutaneous nerve (LFCN) injuries are commonly associated with the approach for PAOs, but the true incidence and rate of resolution is not known. The purpose of this prospective study was to determine the incidence of LFCN injuries after PAO using an innovative nerve conduction study (NCS) and to report the patient-reported outcomes. We prospectively enrolled 23 patients (24 hips) undergoing PAOs to have pre- and post-operative NCSs at a mean of 12 weeks post-operative. Patients were followed prospectively. Patients were contacted 3 years post-operatively via phone to determine the presence and severity of symptoms. Patient-reported outcome scores were also correlated with patient symptoms. Patients (91%) reported one or more LFCN symptoms post-operatively. The most common symptoms were numbness (91%), tingling (36%), pain (18%) and burning (9%). Patients (67%) had evidence of LFCN injury based on NCSs. Symptoms (40%) resolved 4 months post-operatively. Two-thirds of patients had continued symptoms at 3 years. Only 1 patient required treatment. The incidence of LFCN injury after PAO is 90%, two-thirds of which can be identified objectively by NCS. Numbness is the most common symptom. LFCN symptoms (40%) resolve by 4 months, but two-thirds of patients may continue to have thigh numbness up to 3 years after surgery. Fortunately, symptoms are not clearly associated with outcome score and treatment for this complication is rare.