Malloy P, et al. - From January 2012 to June 2015, researchers evaluated 50 participants to estimate the symptomatic hip muscle cross-sectional area (CSA) in patients with unilateral femoroacetabular impingement syndrome (FAIS) vs the asymptomatic-side hip muscle CSA and to ascertain the relationships between the hip muscle CSA and preoperative pain level, preoperative symptom duration, and postoperative function. They noticed significantly decreased CSAs in specific muscles of the symptomatic hip including the gluteus maximus, gluteus minimus, and rectus femoris when compared with the asymptomatic hip. They observed a moderate positive association of tensor fascia lata, pectineus, adductor longus, and obturator externus with preoperative pain level on a visual analog scale in unilateral FAIS patients. They suggested a compensatory change in muscle function around the hip joint in patients with unilateral FAIS. A compensatory change in muscle function was suggested around the hip joint in patients with unilateral FAIS.