Femoroacetabular Impingement, FAI, The Denver Clinic
Hip impingement describes a condition where there is loss of motion of the hip due to some type of excess bone formation. In addition to loss of motion most impingement causes hip pain as well.
Femoroacetabular impingement (FAI) is most commonly a result of excess bone that has formed around the head and/or neck of the femur. This is referred to as a "cam"-type impingement. A "pincer"-type impingement occurs when there is excess bone growth along the acetabular (socket) rim or when the socket is angled so the acetabulum and femur have a point of impact.
Labral tears are often associated with FAI. Common symptoms include groin pain and pain with hip flexion while the leg is rotated internally (toward the middle) and the leg moved inward. Most labral tears can be seen on MRI, and the excess bone grown can be seen on hip x-ray.
X-ray showing a "cam"-type lesion of the hip. The area between the white lines is excess growth of the socket that leads to impingement with hip motion.