Femoro-Acetabular Impingement (FAI)
This is a condition which has only been identified and treated for the last 5 to 10 years, hence many GP’s and some orthopaedic surgeons are not familiar with it. The best person to evaluate this as a potential source of problems around your hip is an orthopaedic surgeon with a special interest in early adult hip problems and hip arthroscopy.
There is an abnormality either in the shape of the femoral head (ball) or the acetabulum (socket). On the femoral head we frequently see a bump which means it is not a perfect sphere and this bump acts as a “Cam” over time damaging the cartilage inside the hip joint and the labrum. The socket may be too deep and as a result repeatedly catch on the thigh bone as the hip is moved around (“Pincer”), over time this results in damage to the labrum around the socket.
It is not clear what causes the hip to develop abnormaly but minor Cam and Pincer problems are regularly seen on hip xrays, and are often noted in patients who have developed hip arthritis. Some patients who have an excessive range of movement within the hip may also develop similar problems e.g. dancers, hypermobile joints.
Over time some patients with impingement develop restricted movements of the hip, clicking or pain. It is important to distinguish it from other sources of pain around the hip such as: low back pain, hernia, piriformis syndrome, trochanteric bursitis, or groin strains. Diagnosis is acheived with history and examination, and also with xray examination of the hip. Minor changes on the hip xray can be difficult to identify and the hip xray can also be normal with FAI. Most patients will undergo an MRI scan of the hip after an injection of dye and local anaesthetic into the joint. A CT (CAT) scan may also be required.
Treatment is with physiotherapy and avoiding precipitating activities. Stretching may worsen the symptoms so should be avoided. Pain-killers, anti-inflamatory tablets or cortisone injections may be used. If the symtoms to do not settle it may be possible to teat the impingement surgically. This is most often performed using hip arthroscopy, although occasionally open surgery is required (Ganz surgical dislocation).
Information on surgery for FAI is available from the National Institute for Clinical Excellence (NICE).