The snapping iliopsoas tendon.

Herein we describe a previously seldom recognized variety of snapping hip, which is caused by snapping of the iliopsoas tendon over the iliopectineal eminence when the femur is moved from the flexed position at the hip and extended through 45 degrees of flexion. The finding is demonstrated with the patient supine and gently resisting gravity with the iliopsoas muscle, thus placing it under tension. At approximately 45 degrees of flexion, the iliopsoas tendon in two patients was confirmed radiographically to snap abruptly, coincident with an audible sound over the iliopectineal eminence of the pelvis. We believe that this occurs relatively frequently and is generally asymptomatic.