Femoro-acetabular impingement or FAI occurs when the ball of the head of the femur does not have its full range of motion within the socket of the acetabulum of the pelvis.Impingement itself is the premature and improper collision or impact between the head and/or neck of the femur and the acetabulum. This causes a decreased range of hip joint motion, in addition to pain. Most commonly, FAI is a result of excess bone that has formed around the head and/or neck of the femur, otherwise known as “cam”-type impingement. FAI also commonly occurs due to overgrowth of the acetabular (socket) rim, otherwise known as “pincer”-type impingement, or when the socket is angled in such a way that abnormal impact occurs between the femur and the rim of the acetabulum.
A) Normal Hip B) Cam impingement C) Pincer impingement D) Combination of cam and pincer impingement
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