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Hip impingement (FAI)

What is hip impingement (FAI)?

Hip impingement occurs when a problem inside the hip joint interferes with its smooth motion, preventing the ball from gliding smoothly inside the socket.

Over time, the cartilage can become damaged, leading to hip (or femoro acetabular) impingement, which is a risk factor for early osteoarthritis of the hip.

What causes hip impingement?

There are two main conditions which cause hip impingement:

  • Cam impingement is a deformity in the ball at the top of the femur, causing it to jam in the socket when the hip is bent.
  • Pincer impingement is a deformity of the socket which can cause the ball of the femur to rub against the rim of the socket when the hip is bent.

Hip impingement can also be caused by other, less common medical conditions such as coxa vara, which causes the thigh bone and ball to grow at different rates in children, and Legg-Calve-Perthes disease, which results in the death of bone in the ball of the joint, due to insufficient blood supply.

Hip impingement

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