Causes / typical injury mechanism: The acetabular labrum is a U-shaped fibrocartilaginous structure surrounding the rim of the acetabulum. It is connected inferiorly by the transverse acetabular ligament. It acts to deepen the acetabulum and maintain femoral head contact within the acetabulum by creating a negative pressure within the acetabulum, thereby contributing to dynamic hip stability.

Since the labrum functions as a stabilizer of the hip joint, tears may alter normal hip kinematics and eventually contribute to osteoarthritis.

Classic history and presentation: A hip labrum tear often presents as deep mechanical anteromedial hip pain that may radiate to the groin or buttocks. There may be associated snapping with a sensation of locking. Patients often endorse night pain that prevents them from sleeping. Depending on the location of the tear, different movements will elicit symptoms.

Prevalence: Tears of the hip labrum are a common source of pain in athletes. Although the precise prevalence in the general population is unknown, they are the most common pathologic finding encountered during hip arthroscopy (90% of cases). It can affect patients of either sex but is most common in athletic female patients.

Risk factors: The greatest risk factor for hip labral tears is acetabular deformity (ie, developmental dysplasia of hip [DDH], femoroacetabular impingement [FAI], acetabular retroversion). Other risk factors include femoral head deformity (ie, slipped capital femoral epiphysis [SCFE], Legg-Calvé-Perthes disease, coxa valga) and sports requiring repeated hip extremes of motion (ie, running, soccer, gymnastics, ballet).

Pathophysiology: The 5 main causes of hip labral tears include trauma, FAI, capsular laxity / hip hypermobility, acetabular dysplasia (eg, DDH), and chronic degeneration. Up to 86% of tears occur in the anterior quadrant of the labrum, with the anterosuperior aspect being the most common anatomical location. Posterior labral tears are most commonly associated with traumatic events such as posterior hip dislocations.