Hip impingement has been recognised and understood only relatively recently. This has arisen from the observation that some patients, usually males, develop early arthritis in their hips because their hips have a somewhat aspherical shape.

Quite commonly, people who have hips with this abnormal shape, start to get symptoms quite early on and a characteristic pattern of symptoms and x-ray signs are now recognised. The importance in the recognition of FAI lies in the fact that appropriate intervention before arthritis develops may well stop this from developing later in life, or at least delay the onset.

Symptoms of FAI

The condition usually becomes apparent in young athletic individuals who start to get pain in the groin and hip area. This is usually activity related and may become bad enough to result in them having to give up sporting activities. Frequently the condition is considered a “groin strain” and often patients undergo courses of physiotherapy to try and address it. Usually, however, it is rather resistant to treatment with physiotherapy and pain frequently recurs.

Signs

Patients may find that certain movements of the hip have become uncomfortable. This is usually flexion of the hip up towards the chest, as in putting on shoes, and frequently there is a restriction in the amount of internal rotation of the hip.

Diagnosis

The condition is usually recognisable on plain x-rays of the hip. The hip generally shows an elliptical rather than a spherical femoral head (cam impingement). There may also be abnormalities on the socket side of the hip with too much coverage of the femoral head leading to a different type of impingement (pincer impingement).

The signs may be quite subtle and many radiologists who report the x-ray appearance of the hip won’t necessarily recognise the condition. This means that many patients get false reassurance from the report of a normal x-ray when in fact there may be an abnormality present.

Once the condition is recognised on x-ray, more investigations may be necessary such as CT scans or an MRI to give more information about the shape of the joint and the damage that may have occurred to the lining of the joint as a result of the abnormal shape.