When the two surfaces of the hip joint move over each other, they usually move freely without any friction.
However if there is an alteration to either the socket part of the joint (the acetabulum) or the ball (the head of the femur), irritation may occur. This is known as Femoroacetabular Impingement, a common disorder of the hip characterised by obstructive pain and stiffness.
FAI can be classified as ‘cam’, ‘pincer’ or mixed.
A ‘cam’ FAI occurs when the femoral head junction is flattened or a small bump is present. A ‘pincer’ FAI occurs when the acetabular rim extends slightly, causing the femur to be impacted. However, about 85% of cases of FAI are ‘mixed’.
The most common symptom of FAI is acute localised pain in the hip or groin when resting in certain positions or with specific movements. Other symptoms include stiffness, loss of flexibility of the hip, locking, clicking or a feeling that the hip is about to ‘give way’.
Activities which cause the incongruous surfaces to repeatedly move over each other are naturally the main culprits. These can include prolonged sitting, twisting, sitting with crossed legs, horse riding, squatting and climbing stairs.
There are many factors which may cause an individual to develop FAI including;
- Hip dysplasia or malformation during infancy/childhood
- Repetitive stress within the hip joint
- A malunion of a femoral neck fracture
- Small bony growths around the joint (spurs)
- Normal anatomical variation
Physiotherapy Management
FAI can lead to osteoarthritis of the hip and there are both conservative and surgical options for treatment.
Conservative management involves laser therapy, passive joint mobilisations, core stability, back and lower limb strengthening.
A hydrotherapy program can be very helpful together with a home exercise program. Most people will respond well to this management with very few requiring further interventions.
A hip arthroscopy is the most common surgical procedure for this disorder —- removing points of irritation from the hip surfaces. After surgery, patients are usually referred for physiotherapy rehabilitation.
By Alison Ford
