The hip joint is a congruent articulation of the femoral head (ball) and the acetabulum (socket) (Figure 1) while the acetabular labrum is a ring of fibrocartilage that is attached around the circumference of the acetabulum. The labrum increases the depth of the acetabulum, effectively increasing the surface area of contact and thereby provides stability to the joint.
Another important function of the acetabular labrum is to maintain the synovial fluid and the fluid pressure by sealing the joint and acting as a lubricator between the femoral head and acetabular cartilage. A tear in the labrum could result in a loss of this suction-seal effect increasing in the joint forces, which could potentially put the acetabular cartilage at a high risk of degeneration.
Injuries to the acetabular labrum can occur from chronic trauma due to repetitive hip motion or from acute trauma as, for example, from a direct blow to the hip or a forceful abnormal movement of the hip.