The artificial hip socket was sold for eight years to some 35, 000 people in the U.S. and more than 90, 000 people worldwide.

NPR: Trial Under Way In LA Hip Joint Replacement Suit

Think of the labrum as a ring of soft tissue that holds the ball of the femur, or thighbone, snugly in the hip joint's socket.

CNN: Gaga's injury related to 'being active'