Femoroacetabular Impingement (FAI)


Article by S.Armfield, Z. Russell

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.

cam femoroacetabular impingement

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. 

Pincer femoroacetabular impingement

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 a 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.

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 the hip range of motion there may be a 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 (FAI) 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.

Femoroacetabular Impingement Treatment

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 stretches 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 in 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% had improved symptoms by one year.

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

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Femoroacebular Impingement Treatment Options

More detailed information on the best rehabilitation for your FAI is available from your physiotherapist.

  • Early Injury Treatment
  • Avoid the HARM Factors
  • Soft Tissue Injury? What are the Healing Phases?
  • What to do after a Muscle Strain or Ligament Sprain?
  • Acupuncture and Dry Needling
  • Sub-Acute Soft Tissue Injury Treatment
  • Core Exercises
  • Gait Analysis
  • Biomechanical Analysis
  • Balance Enhancement Exercises
  • Proprioception & Balance Exercises
  • Agility & Sport-Specific Exercises
  • Medications?
  • Soft Tissue Massage
  • Brace or Support
  • Dry Needling
  • Electrotherapy & Local Modalities
  • Heat Packs
  • Kinesiology Tape
  • Neurodynamics
  • Prehabilitation
  • Strength Exercises
  • Stretching Exercises
  • Supportive Taping & Strapping
  • TENS Machine
  • Video Analysis
  • Yoga
  • Helpful Products for Femoroacebular Impingement


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    Related Injuries

    General Information

    Hip Joint Pain

    Lateral Hip Pain

    Adductor-related Groin Pain

    Pubic-related Groin Pain

    Inguinal-related Groin Pain

    • Inguinal hernia
    • Sportsman's hernia

    Iliopsoas-related Groin Pain

    • Hip Flexor Strain

    Other Muscle-related Pain

    Systemic Diseases

    Referred Sources

    Hip Surgery

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    FAQ's about Femoroacebular Impingement

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    Last updated 22-Feb-2019 09:21 AM

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