Coxa Saltans: The Snapping Hip Revisited.

Abstract

Coxa saltans, or "snapping hip," has several causes. These can be divided into three types: external, internal, and intra-articular. Snapping of the external type occurs when a thickened area of the posterior iliotibial band or the leading anterior edge of the gluteus maximus snaps forward over the greater trochanter with flexion of the hip. The internal type has a similar mechanism except that it is the musculotendinous iliopsoas that snaps over structures deep to it (usually the femoral head and the anterior capsule of the hip). Intra-articular snapping is due to lesions in the joint itself. Diagnosis of the external and internal types is usually made clinically. Radiography can be useful in confirming the diagnosis, particularly when bursography shows the iliopsoas tendon snapping with hip motion. Other radiologic modalities, such as computed tomography, magnetic resonance imaging, and arthrography, may also be helpful, especially when there is an intra-articular cause. Most cases of snapping hip are asymptomatic and can be treated conservatively. However, if the snapping becomes symptomatic, surgery may be necessary. There may also be a role for arthroscopy in the treatment of intra-articular lesions.