Femoroacetabular Impingement (FAI) or hip impingement syndrome is a condition affecting the hip joint in young and middle-aged adults.[1] Impingement occurs when the ball shaped femoral head rubs abnormally[2] or doesn't have full range of motion in the acetabular socket.[3] Damage in the hip joint can occur to the articular cartilage or the labral cartilage (soft tissue bumper of the socket). Treatment options vary from conservative treatment to arthroscopic and open surgery.
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This affliction is characterised by abnormal contact between the proximal femur and rim of the acetabulum (hip socket). In most cases patients presenting with a deformity in the femoral head or acetabulum, a poorly positioned femoral-acetabular junction or the presence of both conditions are symptomatic of FAI. It is believed that a combination of certain factors may lead to some form of FAI. Predominantly a marginal developmental hip abnormality together with environmental factors such as the partaking in activities involving recurrent motion of the legs within a supraphysiologic range.[4]
There are three types of FAI. The first involves an excess of bone along the upper surface of the femoral head: this is known as a Cam deformity, the name being derived from the Dutch word for cog. The second is due to an excess of growth of the upper lip of the acetabular cup and is known as the Pincer deformity. The third is a mixture of the preceding two forms. The result of any of these deformities is increased friction between the acetabular cup and femoral head which may result in pain and loss or reduction of hip function.
Many activities involving recurrent hip motion increase the frequency of this abnormal contact in FAI sufferers. These include sports such as soccer, ice-skating and gymnastics. However, FAI-related pain may occur within a normal range of motion during actions not normally associated with a need for physical demand such as the motions of sitting down and standing up. This condition generally manifests itself in three forms: cam impingement, pincer impingement or mixed cam and pincer impingement. In cam impingement there is an abnormal bony lesion on the femoral head. In pincer impingement there is a bony lesion on the acetabulum which leads to over-coverage of the femoral head. In mixed cam and pincer impingement both conditions exist.
Some medical experts believe this to be a trigger or the beginning of hip osteoarthritis. Without hip-preserving treatment, there is a high likelihood of developing osteoarthritis with the subsequent requirement of a hip replacement procedure if still left untreated.
In sufferers, FAI-related pain may be felt in the groin, lower back and generally around the hip. The diagnosis of FAI typically involves a physical examination in which the range of motion of the leg in relation to the hip is tested. Positive limited flexibility would lead to further examination with x-ray, for a two-dimensional view of the hip joints. Subsequent imaging techniques such as a CT or MRI scan may then be used in order to produce a three-dimensional image showing the angles of the hip sockets, in addition to the condition of hip cartilage or signs of osteoarthritis.
The treatments for FAI vary considerably. Sufferers may be shown how to manage their condition and forego surgery. Conservative/nonsurgical treatments should always be considered first. This can include reducing levels of physical activity and having pain medication and physiotherapy sessions. Physical Therapy [physiotherapy] intervention may help to optimize alignment and mobility of the hip joint, therefore, decreasing excessive forces on irritable or weakened tissues. Physical Therapy can also help to identify specific movement patterns that may be injuring the involved hip. These types of interventions may be successful in reducing the pain and swelling in the joint, although in some cases, physical therapy can cause symptoms to worsen. Those who choose this route may require a hip replacement later in life. However, depending on the condition of the patient (e.g. elderly with advanced osteoarthritis), a hip replacement may be the best course of treatment. The downside of this is the need for subsequent hip replacement procedures and the limiting effects of the artificial hip.
Due to the condition being diagnosed frequently in adolescents and young adults, various surgical techniques have been developed in order to preserve the hip joint, preventing the need for a total hip replacement and allowing the patient to continue with an active lifestyle. Surgery may be arthroscopic or open. Periacetabular or rotational osteotomies are two common open surgery techniques that may be performed if investigations have shown there to be an abnormal angle of the hip joint. These primarily aim to alter the angle of the hip socket in such a way that contact between the acetabulum and femoral head are greatly reduced, allowing a greater range of movement. Femoral sculpting may be performed simultaneously, if required for a better overall shape of the hip joint.