Femoral Acetabular Impingement (FAI)

Femoroacetabular Impingement is defined as a motion related clinical disorder associated with abnormal contact of the ball and socket joint of the hip. 


There are 2 types of FAI: Cam impingement refers to abnormal bony morphology of the femoral head resulting in a non-spherical femoral head. Pincer impingement refers to over coverage of the socket (acetabulum) or a deep socket resulting in premature contact of the 2 bony surfaces. 

Causes

Recent research shows that young athletes that undergo repetitive change of direction or pivoting loads such as AFL, soccer or hockey have a greater prevalence of Cam impingement due to the increased stress placed on the immature growing hip.

Signs & Symptoms

  • Pain in the buttock, thigh or groin 

  • Reduced range of motion especially hip flexion and internal rotation

  • Clicking, catching, stiffness, giving way or locking

  • Pain in the hip or groin after activity

  • Reduced trunk strength

  • Reduced hip muscle strength and dynamic balance

Differential Diagnosis

  • Acute hip pain due to tumour, infection, septic arthritis, osteomyelitis

  • Hip fracture and avascular necrosis are red flag conditions that should be ruled out. 

  • In athletes, other causes of hip pain include inguinal pathology, adductor pathology and athletic pubalgia

PROmotion Assessment and Outcomes Measures

FAI is diagnosed when all 3 factors below are present:

  • 1. Pain (eg with stair climbing/descending or single leg squat)

  • 2. Clinical signs of restricted range of motion (eg. FADIR position)

  • 3. Positive imaging finding on Xray or MRI

How to Manage

  • Best treatment consists of an individualised targeted rehab program that looks to strengthen the trunk, pelvis and surrounding muscles of the lower leg as well as improving control and movement patterns around the hip. 

  • This involves commitment of 3 sessions a week of strength training and progressive cardiovascular training of up to 45 mins per session every second day. 

  • Manual therapy can be used to compliment the main goal of strength training as there is often a large amount of associated muscular spasm that can contribute to pain but these effects are often short lived providing a window of opportunity to strengthen.

  • Activity and lifestyle modification is imperative to long term management and quality of life. 

  • Questionnaires such as the iHOT 33 and HOS ADL can be used to watch for decline of function or increased pain. 

  • Conservative physio led treatment should be trialled for at least 9-12 months before surgical management is considered. 

  • For those patients that do require arthroscopic surgery it is important to go into the operation with good strength and function to help with recovery after. Post-surgical rehab will look similar to the conservative treatment above.

References