Athletic injuries are a common cause of hip flexor tendon rupture. In young patients, tendon rupture is likely to occur at the junction of the muscle and tendon. In adults, age-related degeneration and tendinopathy increase the risk rupture within the tendon itself. Forceful extension of the hip with the knee flexed can result in rupture of the rectus femoris tendon which is attached to the anterior inferior iliac spine (AIIS) or the sartorius tendon which is attached to the anterior superior iliac spine (ASIS). Patients may experience a popping sensation along with pain, swelling, and muscle weakness. X-rays and MRI scans may also be ordered to confirm the diagnosis. Rupture of the hip flexor tendon may be treated by hip arthroscopy to reattach the tendon.