Femoro-Acetabular Impingement (FAI Hip)
FAI Hip – Femoro-Acetabular Impingement – is a hip condition in which there is a mechanical mismatch between the hip “ball” and the “socket”.
The misshapen ball (or socket) leads to a pinching of surrounding tissue when the hip is bent up or twisted inwards, causing pain.
There are three types of Hip FAI or femoro-acetabular impingement:
Cam Type FAI
‘Cam’ type femoro-acetabular impingement is where there is a ‘bump’ on the surface of the femoral head (ball) or femoral neck, which then leads to it jamming on the rim of the socket when the hip is bent up or twisted inwards. This typically affects young athletic men – we often see it in footballers and rowers.
Pincer Type Hip FAI
‘Pincer’ type femoro-acetabular impingement is where the shape of the socket differs from normal, making the socket deeper as it wraps around the front of the ball. This too leads to the ball and socket jamming when the hip is bent up. This typically affects middle aged women and is less common.
Mixed Type Hip FAI
Often there can be a combination of both cam and pincer types, which is called “Mixed” femoro-acetabular impingement.
What Causes FAI Hip – Femoro-Acetabular Impingement?
Most of the cause of FAI is the way we are built and develop. It is believed that many normal people have ‘bumps’ or slightly over-deep sockets and could potentially develop femoro-acetabular impingement.
These deformities lead to an increased friction between the socket and the ball, which may lead to pain and decreased range of motion.
However, having the differing shape doesn’t necessarily lead to pain. The hip has to also be provoked in some way to cause pain or damage. This explains the tendency for athletes, sporting professionals and active people to be more susceptible to complaining of pain from of injury.
What are the Symptoms of Femoro-Acetabular Impingement?
The main symptom of FAI Hip is pain in the hip or groin associated with a reduction in the range of motion of the hip.
The pain is mostly 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. It can come on acutely after an injury or specific aggravating event, or can come on slowly over time. The pain is often provoked with prolonged sitting, walking, crossing the legs as well as during and after sport and exercise.
The reduction in hip range of motion will typically be a restriction in hip flexion (knee towards chest) and internal rotation.
How do you Diagnose Femoro-Acetabular Impingement?
FAI Hip can be diagnosed clinically by your Leading Edge Physio with a series of special assessment techniques.
One of these tests is called the impingement test and when this test is positive (reproduces the pain), there is a 90% chance that FAI is present. Your physio will also check your range of motion and will be looking for the tell-tale sign of reduced flexion and internal rotation.
Your Leading Edge Physiotherapist will also do a full assessment of your muscular strength and control. Poor hip control (hyperlink to specific page) will lead to the two bones being more likely to impinge on each other. Identifying and addressing poor hip control may allow resolution of symptoms without further intervention.
If FAI Hip is suspected from the clinical examination, radiology (X-Rays, CT or MRI) can be used to confirm the diagnosis.
This X-Ray shows the most common finding of a prominent bump on the femoral neck (Cam Type FAI Hip).
MRI scans can also pick up associated damage to other hip structures such as hip labral tears (hyperlink to specific page)..
How Do You Treat FAI?
An initial trial of conservative treatment is recommended for femoro-acetabular impingement.
Your Leading Edge Physio will try to improve the range of motion of the joint by releasing tight structures (such as the muscles and hip capsule) with special massage and mobilisation techniques and dry needling. They will also aim to improve the strength and control of the joint to reduce any impingement that may occur as a result of poor hip control (hyperlinked to specific page).
Use of painkillers and anti-inflammatories may temporarily help the pain reduce the local anti-inflammatory reaction.
By employing these measures, most patients will be able to return to their sport of choice with a marked improvement in symptoms.
Will I Need Surgery For My FAI?
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 mostly by arthroscopic surgery where the surgeon aims to address the mechanical and pathological changes around the neck/acetabulum junction.
After surgery your Leading Edge Physio will supervise a post-surgical hip rehabilitation program, which is an essential part of your FAI recovery.
Recovery from hip arthroscopy typically takes 3-4 months. In recent years research has reported excellent results with 80% of patients asymptomatic by 3-4 months and up to 95% having improved symptoms by one year.
I Think I Have FAI – What Should I Do Right Now?
To help your injury resolve as fast as possible:
- avoid or modify activities and positions, which cause your pain. Recovery is easier if you stop irritating the hip.
- avoid sitting with knees higher than your hips.
- avoid sitting with legs crossed or sitting on you legs so that the hip is rotated.
- avoid sitting on the edge of the seat and contracting the muscles that flex your hips.
If you are not sure if you need an assessment, you can ENTER YOUR DETAILS HERE and one of our physios will give you a call back to discuss your problem and work out the next step in your recovery.