Femoroacetabular impingement or FAI is a condition where the bones of your hip joint come too close and pinch tissue or cause too much friction. Usually, the ball of the hip joint (femoral head) sits on the femoral neck similar to an ice cream sitting on a cone. The pinching and friction occurs when the femoral head and neck contact the socket (acetabulum), creating damage to the hip joint. The pinching or friction may cause damage to the labrum (a fibrous cartilage that lines the outer edge of the socket) and/or the articular cartilage (the white covering over the bony surfaces that results in the very smooth surface gliding of the joint)
There are two described types of impingement:
‘Cam’ type impingement describes a ‘bump’ on the surface of the femoral head (ball) which jams on the rim of the (acetabulum) socket
This typically affects younger athletic men (common)
‘Pincer’ type which described an overdeep acetabulum (socket) which restricts the movement of the femoral head (ball)
This typically affects middle aged women (less common)
Often there is a degree of overlap between the types
Femoroacetabular Impingement (FAI) is associated with articular cartilage damage and labral tears and may result in hip arthritis at a younger age than usually occurs.
FAI is common in high-level athletes, but also occurs in active individuals. While either type of impingement can occur in men or women at any age, most frequently the Cam type of impingement tends to affect young (20s) male athletes, while Pincer tends to occur more commonly in women in their 30s and 40s who are athletically active. Sports associated with FAI include Martial Arts, Ballet, Cycling, Rowing, Golf, Tennis, Soccer, Football, Ice Hockey, Baseball, Lacrosse, Field Hockey, Rugby, Water Polo, and Deep squatting activities such as power lifting.
There may be no pain or symptoms
Pain or aching (usually located at the inner hip, or groin area), usually after walking, or prolonged sitting (such as in a car)
A locking, clicking or “catching” sensation within the joint
Pain sitting for long periods of time, like in a car
Difficulty putting on your socks and/or shoes
Difficulty walking up hill
Low back pain.
Pain at the SI (sacroiliac joint on back of pelvis), the buttock, or greater trochanter (side of hip).
It is often confused with other sources of pain, such as hip flexor tendinitis, pain from the back (disc or spine), testicular pain, sports hernia.