What is femoroacetabular impingement and what causes it?  What
is femoroacetabular impingement and what causes it?
Femoroacetabular refers to the place where the femur (thigh
bone) and acetabulum (hip socket) meet. Impingement means
pinching.  In the case of femoroacetabular impingement (FAI),
the head of the femur butts up against the cartilage and pinches
it. Normally, the femoral head moves smoothly inside the hip
socket. The socket is just the right size to hold the head in
place.  If the acetabulum is too shallow or too small, the hip
can dislocate. In the case of FAI, the socket may be too deep.
The rim of the cartilage hangs too far over the head. When the
femur flexes and rotates, the cartilage gets pinched.  This
causes deep groin pain with activities that stress hip motion.
Prolonged walking is especially difficult.  The cause of the
problem is under considerable debate. For a long time it was
assumed that overload of the joint caused this kind of OA. But
no one could identify what was causing the