What is FAI?
Femoroacetabular impingement (FAI) is a morphological condition of the hip that could potentially lead to hip or groin pain and decreased performance in young adults (Diamond et al, 2014). This condition itself is not pathological, and asymptomatic FAI is not uncommon (Brukner & Khan, 2012). A recent MRI systematic review identified 23% asymptomatic FAI in general population and 55% in young adult athletes (Frank et al, 2015). Then mean age of the FAI subjects in this study was 25 years old (Frank et al, 2015). FAI can also be a causative factor in future hip osteoarthritis (OA).
In a normal hip, the acetabulum (socket) of the pelvis (with a cartilage ring - the labrum - on top of the surface area to improve contact) and the head of femur should fit nicely to each other. In FAI, there is an abnormal bone spur or additional bone growth at either the surface of the femoral surface or acetabular surface, or both.
There are three types of FAI: Cam, pincer or mixed type. A study has shown that cam type FAI accounts for 78% of people with FAI and pincer type is less common, which account for 42%. The third type is a mix of cam and pincer type and it is the most common type which is observed in 88% of people with FAI (Beaulé et al, 2011)
It is not totally clear how FAI is developed. It could be due to excessive epiphyseal plate reaction between the femoral neck and head to repetitive torsional force. There is some evidence suggesting that there might be a genetic link to develop FAI, with siblings three times more likely to develop FAI (Brukner & Khan, 2012 & Pollard et al, 2010).
How is FAI diagnosed?
Diagnosing FAI can be challenging due to the lack of clinical gold standard tests. Although magnetic resonance imaging (MRI) or magnetic resonance arthrogram (MRA) are deemed to be the ‘’gold standard’’ at the moment, there is not any study to verify their accuracy and validity. There has been some systematic review trying to look at the diagnostic accuracy and validity of clinical tests for FAI, however, majority of the previous studies were either lower quality or based on sensitivity data or narrative discussion (Reiman et al, 2014 & Tijssen et al, 2012). Clinically, reduction in hip internal rotation when hip is flexed and positive FADIR (flexion, adduction and internal rotation) test are usually indication of FAI or labral pathology (Reiman et al, 2014). There are many causes of hip pain, such as groin strain, OA and trochanteric bursitis etc. In fact it is more important to confirm or clear differential diagnoses in a clinical setting when someone presented with hip pain (Dooley 2008). Typically this means ruling out other structures through mechanical testing.
There are two type of management towards FAI, non-operative treatment or surgical management. There has been superior evidence to suggest surgical management than non-operative treatment as outcome is better (Dooley 2008 & Harris et al, 2013). In terms of surgical techniques, arthroscopy appears to have equal or better outcome than other techniques (open dislocation & mini-open) with less complications and reoperation rate (Matsuda et al, 2011 & Harris et al, 2013).
To date the consensus of current studies promoted initial non operative treatment. There has been limited studies that look at non-operative management of FAI, however it was suggested to trial a period of conservative therapy, activity modification and non-steroid anti-inflammatories before (NSAIDs) (Wall et al, 2013). Researches have shown that people with FAI or OA have reduced general hip muscle size and muscle strength in most hip muscle groups – hip flexors, abductors and adductors etc. (Arokoski et al, 2002 & Casartelli et al 2011). Hence, regardless of whether surgical management is indicated, it is crucial to retrain and strengthen these muscle groups for pre/post-surgical rehabilitation or conservative management.
Take home message
In summary, FAI is common even among asymptomatic people. Proper assessment is important to clear differential diagnoses. FAI is also a treatable condition and if FAI is found to be the source of hip pain, early treatment is advised for better outcomes.
If you are wondering if you or someone you know has a symptomatic FAI, come in to see a highly skilled physiotherapist well versed in hip pain. Here at Thornleigh Performance Physiotherapy, we can give you an accurate diagnosis and treatment. We have an expertise in musculoskeletal physiotherapy and are near Beecroft, Cherrybrook, Hornsby, Normanhurst, Pennant Hills, Wahroonga, Westleigh, West Pennant Hills, and West Pymble. Here at Thornleigh Performance Physiotherapy, we can give you an accurate diagnosis and treatment.
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- Beaulé, P. E., Allen, D., Doucette, S., & Ramadan, O. (2011). 35. PREVALENCE OF ASSOCIATED DEFORMITIES IN PATIENTS WITH CAM TYPE FEMOROACETABULAR IMPINGEMENT. Journal of Bone & Joint Surgery, British Volume, 93(SUPP III), 250-250.
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