Feeling Numb

Abstract

A 56-year-old physically active male presented to clinic with worsening right hip pain over 3 years because of osteoarthritis. He ambulated with a visible antalgic limp, and range of motion was limited because of pain, with a forced internal rotation and active hip flexion of 25°. Anteroposterior pelvis and lateral view radiographs showed bone on bone arthritis with evidence of sclerosis on the acetabular margin. The hip was treated conservatively with cortisone injections for several months, but the pain continued to persist. The patient subsequently underwent direct anterior total hip arthroplasty (THA) and had loss of sensation postoperatively in his right quadriceps medially and was unable to flex his hip. At his 3-month follow-up, the patient underwent an electromyograph study and was found to have a femoral nerve palsy (FNP). The patient is now 15 months postoperatively, ambulating independently, and has recovered 75% of his strength in his right leg and 75% of his sensation has returned. This case study is used as a guide to delineate risk factors associated with this rare but debilitating palsy and underlines the importance of early diagnosis to maximize patients' chances of recovery. Direct anterior approach (DAA) is becoming an increasingly popular technique for THA because of its minimally invasive approach, shorter length of stay in hospital, and a perceived lower dislocation rate. FNP is a serious neurological complication that may follow the DAA. There are known risk factors in the development of the palsy, including female sex, developmental dysplasia of the hip, and iatrogenic injury through retraction. Early postoperative detection of the nerve deficit is key to starting early treatment to regain quadriceps function and sensation. Care should be taken when counseling patients on the risk of a nerve injury during a direct anterior THA and emphasis should be placed on promptly reporting any postoperative loss of sensation to facilitate and improve recovery.