Snapping Hip Syndrome

Excerpt

Snapping hip syndrome, also known as coxa saltans (or dancer’s hip), is a clinical condition characterized by an audible or palpable snapping sensation that is heard during movement of the hip joint. Snapping hip has multiple etiologies and is classified based on the anatomic structure that is the cause/source of the snapping sensation. Historically, two main snapping hip categories were recognized:

1. Extra-articular

2. Intra-articular

The term intra-articular snapping hip has relatively fallen out of favor due to the increasing knowledge of intra-articular pathologies. These etiologies include loose bodies (e.g. secondary to synovial chondromatosis) or labral tears of the hip.

As the clinical terminology evolved, extra-articular snapping hip eventually became subclassified into:

1. External snapping hip

2. Internal snapping hip

External snapping hip is most commonly attributed to the iliotibial band moving over the greater trochanter of the femoral head during hip movements in flexion, extension, and external or internal rotation. Other causes include the proximal hamstring tendon rolling over the ischial tuberosity, either the fascia lata or the anterior aspect of the gluteus maximus rolling over the greater trochanter, and the psoas tendon rolling over the medial fibers of the iliacus muscle. A combination of defects is also possible; for example, thickening of both the posterior iliotibial band and anterior gluteus maximus, which snap over the greater trochanter at the same time.

Internal snapping hip most commonly occurs as the iliopsoas tendon snaps over underlying bony prominences, such as the iliopectinal eminence or the anterior aspect of the femoral head. Other causes include paralabral cysts and partial or complete bifurcation of the iliopsoas tendon. The snapping sensation can closely mimic intra-articular pathology since they both originate from the anterior hip area. Close physical exams and imaging can differentiate the two. It should be noted, however, that in approximately 50% of internal snapping hip cases, an additional intra-articular hip pathology is identified.