Hip Impingement (FAI)


Normally, the round head at the top of the femur bone (the thigh bone) glides smoothly in the hip socket. If the top of the femur is not round (cam impingement) or if the front edge of the socket is too prominent (pincer impingement), then the smooth motion is disrupted. This condition is called hip impingement or femoro acetabular impingement (FAI).


Hip impingement is usually without symptoms for many years. After a long time, it causes stiffness and pain in the groin or front of the thigh. FAI can also prevent individuals from flexing their hip beyond 90 degrees. Pain usually increases after prolong sitting, running or jumping. The condition, left untreated, can lead to osteoarthritis in the hip.

Causes and Risk Factors

FAI is caused by deformities in the femur, hip socket or a combination of both. The condition may begin at birth (congenital) or may develop as a child grows (acquired). The condition appears to be caused by a combination of genetic and environmental factors. Some researchers believe that the risk of FAI is increased by significant athletic activity before a child's bones are mature and that contact sports may make hip impingement worse.


A physician will test the hip for range of motion, which hip impingement limits, and may order X rays, MRI, and/or CT scans to detect the condition. Diagnosis is important, since hip impingement also can be caused by other conditions, such as Legg-Calve-Perthes disease, slipped capital femoral epiphysis, or Coxa Vera.


If the cartilage in the hip is still intact, then surgery can be performed to reshape the top of the femur or the socket so they fit better together, which is called debridement or osteoplasty. The earlier surgery is performed, the greater the likelihood of a complete recovery. Once cartilage has been damaged, surgery may still greatly reduce pain and increase range of motion. Your doctor will tell you if you are a good candidate for hip arthroscopic surgery, a minimally invasive option.

© 2000-2022 The StayWell Company, LLC. All rights reserved. This information is not intended as a substitute for professional medical care. Always follow your healthcare professional's instructions.
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