The Iliopsoas: Anatomy, Clinical Evaluation, and Its Role in Hip Pain in the Athlete: A Scoping Review.

Disability due to iliopsoas (IP) pain and dysfunction is underdiagnosed in the athletic population. The IP unit consists of the psoas major and iliacus muscles converging to form the IP tendon and is responsible primarily for hip flexion strength but has a number of secondary contributions such as femoral movement, trunk rotation, core stabilization, and dynamic anterior stability to the hip joint. As the IP passes in front of the anterior acetabulum and labrum, the diagnosis of IP pain may be confused with labral tearing seen on magnetic resonance imaging. This is in addition to the low sensitivity of magnetic resonance imaging to detect IP tendinitis and bursitis. Resisted seated hip flexion as well as direct palpation of the IP tendon and muscle belly are useful to assess function and help determine whether the IP may be the source of pain, which is common in athletes. Both biomechanical and clinical investigations have demonstrated the role of IP as an anterior hip stabilizer. Patients with signs of hip microinstability, developmental dysplasia of the hip, and increased femoral anteversion are at risk of IP pain and poor outcomes after IP lengthening, highlighting the importance of the IP in providing dynamic anterior hip stability.