What is Hip Femoroacetabular Impingement? What to do?

What is Femoroacetabular Impingement?

Femoroacetabular Impingement (FAI) is a hip condition which describes a mechanical mismatch between the hip “ball” and the “socket”.

There are three described types of femoroacetabular impingement:

Cam Type FAI

‘Cam’ type femoroacetabular impingement describes a ‘bump’ on the surface of the femoral head (ball) which jams on the rim of the (acetabulum) socket. This typically affects young athletic men.

Pincer Type FAI

‘Pincer’ type femoroacetabular impingement describes an increased coverage by the acetabulum over the anterior femoral head. This typically affects middle aged women and is less common.

Mixed Type FAI

Often there can be a combination of both cam and pincer types, which is termed “

Mixed femoroacetabular impingement

What Causes Femoroacetabular Impingement?

It is believed that many normal people have ‘bumps’ or slightly over-deep sockets and could potentially develop femoroacetabular impingement – this is just the way we are built and develop.

The result of these deformities is increased friction between the acetabular socket and femoral head, which may result in pain and decreased range of motion.

However, the hip has to also be provoked in some way to cause damage. This explains the tendency for athletes, sporting professionals and active people to be more susceptible to this form of injury.

What are the Symptoms of Femoroacetabular Impingement?

FAI often presents as hip and groin pain with restricted range of hip motion.
Symptom onset can be acute, following injury, or insidious after prolonged exertion.
Pain is often provoked with prolonged sitting, walking, crossing the legs as well as during and after sport and exercise.
There will typically be a restriction in hip flexion and internal rotation range of motion.
Pain is primarily felt deep in the groin at the front of the hip, more rarely it can be on the side of the hip or the buttock.

How is Femoroacetabular Impingement Diagnosed?

Physical examination involves a series of hip tests.

Diagnosis is 90% positive with reproduction of symptoms on the impingement test – flexion adduction and internal rotation of the hip.

When testing hip range of motion there may be restriction in hip flexion and internal rotation.

Provocation of pain by flexion abduction and external rotation (FABER test) may provoke pain but is generally non-specific.

Radiology Tests for FAI

Radiology investigations for femoroacetabular impingement can be undertaken to confirm the diagnosis with AP X-rays of the pelvis and lateral X-rays of the hips being the first line of investigation.

Subsequent imaging techniques such as a CT or MRI scan may then be beneficial.

How is Femoroacetabular Impingement Treated?

An initial trial of non-operative treatment is advocated for most patients, as the pain is relatively self-limiting.

Physiotherapy can assist FAI by using a variety of techniques to:

mobilise the hip joint that stretch any tight structures eg joint capsule or muscles
improve soft tissue flexibility and length
strengthen the deep, intermediate and superficial hip muscles
progress hip muscle, proprioception, joint position sense and functional control to dynamically control your hip

Use of painkillers and anti-inflammatories may temporarily help the pain reduce the local anti-inflammatory reaction.

Hip Surgery for Femoroacetabular Impingement?

If your symptoms continue to remain unchanged on return to sport, then referral to an orthopaedic surgeon is recommended.

Surgical treatment for FAI is performed either by arthroscopic debridement or can be performed by open surgical debridement. While the techniques are quite different, the operations both aim to address the mechanical and pathological changes around the neck/acetabulum junction.

Post-FAI Hip Surgery Rehabilitation

A supervised hip rehabilitation program with your physiotherapist is an essential part of your post-surgical FAI recovery.

Recovery from hip arthroscopy typically takes 3-4 months, while open hip debridement is typically 12 months. Hip arthroscopy has been the preferred method in recent years and has reported excellent results with 80% of patients asymptomatic by 3-4 months and up to 95% having improved symptoms by one year.

For more advice about femoroacetabular impingement, please ask your physiotherapist or doctor.

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