Acetabular Labral Tear

An acetabular labral tear is an injury to the fibrocartilage rim of the hip socket that causes deep anterior groin pain, often with clicking or catching, in young and middle-aged active adults.

It often accompanies femoroacetabular impingement (FAI) but is not the same thing: tears also occur with dysplasia, hypermobility, trauma and early osteoarthritis. FAI syndrome is diagnosed only when symptoms, clinical signs and imaging agree. Tears are often mistaken for adductor strain or referred lumbar pain.

The labrum is a horseshoe-shaped fibrocartilage rim that deepens the socket, maintains the suction seal and contributes to stability and proprioception. It is widest anterosuperiorly, where most tears occur.

Main mechanisms:

• •FAI: repeated cam or pincer contact, the usual mechanism in young athletes
• •Dysplasia: under-coverage (lateral centre-edge angle under 20° to 25°) overloads the labrum
• •Hypermobility: microinstability, particularly in young women
• •Trauma: dislocation or subluxation
• •Degeneration: in middle-aged and older adults, often with early osteoarthritis, a different management pathway

FAI morphology:

• •Cam: aspherical femoral head-neck junction (alpha angle over 60° is a common threshold), typically young athletic men; shears the anterior labrum
• •Pincer: acetabular over-coverage (lateral centre-edge angle over 40°) or retroversion, typically middle-aged women; crushes the labrum
• •Mixed: both features, and the most common pattern