Hip Impingement

What is hip impingement?

Hip impingement or Femoro-Acetabular Impingement (FAI) occurs when the bones of the hip joint impact each other where they shouldn’t. Normally the femur (which forms the ball in the hip joint, and goes down as the thigh bone) and acetabulum (which forms the socket of the hip and is part of the pelvic bone) move smoothly in the hip joint. In some hips the shape of the ball or socket or both means that they impact against each other abnormally during movement.

This impaction may cause pain. The abnormal shape may prevent movement and cause hip stiffness. The contact may damage the hip labrum and the cartilage in the acetabulum next to the labrum. However, many people have impingement without ever having pain or problems from it, or even knowing about it.

What are the signs of hip impingement?

Hip impingement may cause stiffness and groin pain. Some patients will have no symptoms at all. The impingement usually occurs as the hip is bent up and rotated inward (i.e. heel goes out, toes go in). This movement may be limited or painful.

What is the treatment for hip impingement?

Science has been unable to prove that fixing hip impingement can prevent problems like arthritis down the track. Treatment is only required if there is pain or stiffness causing problems now. If the pain has come on recently after sport or an injury then rest, anti-inflammatory medication and avoiding the position of discomfort can settle it down effectively.

If the pain is longer term or doesn’t settle, or always comes back on with a particular sport or activity then physiotherapy may help by stretching and strengthening the muscles around the hip and improving the pelvis position and muscle control.

Hip arthroscopy can remove the abnormal bone and repair any damage it has caused (e.g. a labral tear). It is effective in reducing pain and improving movement; we hope that removing the impinging bone will degrease arthritis down the track, but that has not been proven.

What is the hip labrum?

The labrum (LAY-brm) of the hip is a rim of cartilage around the edge of the socket which makes the socket deeper and helps keep the head of the femur (ball of the joint) sealed in it. On the inside surface it forms a smooth continuation of the cartilage of the socket.