Impingement

Hip impingement or Femoroacetabular Impingement (FAI) is a condition that has only recently received attention for being recognised and understood. The condition relates to the abnormal shape of the femoral head or acetabulum (socket in which the femoral head sits). Quite commonly, people who have hips with this abnormal shape, start to get symptoms quite early on and present with a characteristic pattern of symptoms and x-ray signs.

The importance in the recognition of FAI lies in the fact that appropriate intervention must occur before arthritis develops.

  • Normal – the hip joint is described as a ‘ball and socket’ joint.  It is important to understand what a ‘normal’ hip joint looks like in order to appreciate the abnormalities that can occur
  • Cam-type FAI is caused by a ‘bump’ at the front of the femoral head/neck (the ‘ball’ portion of the joint)
  • Pincer-type FAI is caused by a deep socket of spikes of bone (osteophytes) at the front of the accetabulum (the ‘socket’ portion of the joint)
  • Mixed FAI is a combination of a Cam and Pincer abnormality

The exact cause of FAI is not completely understood. Proposals have been put forward to suggest that it is congential (people are born with the condition) or that it is simply due to degenerative changes or arthritis. It is probably a combination of the two.

Symptoms:

  • Pain is typically felt in the groin area as a sharp, ‘catching’ pain.  As a result it is often misdiagnosed as a groin strain and treated accordingly, however if misdiagnosed it can be resistant to physiotherapy treatment and pain frequently occurs
  • Patients typically display a painful arc of movement, normally flexion of the hip towards the chest and internal rotation
  • Crossing of the legs or putting the shoes on will normally cause pain

Diagnosis:

  • The description of a patient’s symptoms will normally lead an experienced clinician to the diagnosis of FAI
  • An experienced clinician will carry out tests that will elicit a patient’s pain to help with the diagnosis
  • The condition can usually be recognised on plain x-rays of the hip
  • A CT or MRI scan will give a more detailed picture of the exact shape of the femoral head and acetabulum

We have already mentioned that FAI falls into 2 categories:

  • If the hip generally shows an elliptical rather than a spherical femoral head, this is known as a cam impingement
  • Abnormalities of the socket (acetabulum) where there is too much coverage of the femoral head indicates a pincer impingement .

  • If the symptoms are mild then anti-inflammatories or painkillers will assist in offering relief
  • Restriction of activities that cause pain will help to settle the symptoms
  • Physiotherapy treatment in the form of manual and soft tissue techniques can help ease the symptoms.  Likewise, stretches and strengthening exercises for the muscle around the hip and core stability will help in the long term management
  • However, if the above do nothing to relief the symptoms then surgery may be required