Femoro Acetabular Impingement (FAI), often referred to as Hip Impingement, is an abnormal shape of the hip. It affects approximately 30% of the general population and 90% of some sporting groups (e.g. footballers and ice hockey players). This condition increases the risk of developing arthritis over twenty years.
Often in the early stages it is not painful and so can be undiagnosed for years. The diagnosis itself is made by taking a patient history, physical examination and imaging studies including x-rays and MRI scans.
Most likely causes
There are two types of hip impingement, 'Cam' and 'Pincer' and you can get a combination of both. Normally the hip glides and moves smoothly as the ball shaped head of the femur moves in the cup shaped socket of acetabulum.
Cam Impingement is caused by a jamming or squeezing of an abnormally shaped femoral head and head-neck junction into the acetabulum during certain hip movements.
Pincer Impingement occurs when there is direct contact with the femoral neck or head-neck junction with part of the acetabulum edge and labrum. The acetabulum appears to be 'over deep.'
Treatment obviously depends on what form of impingement is present and is tailored to each individual. It can involve reshaping the femoral head and head-neck junction and/or recessing the acetabular rim and labrum.
When conservative methods of treatment fail to provide symptomatic relief then hip replacement surgery may be offered.
Video showing right hip arthroscopy for treating FAI