Femoroacetabular Impingement Syndrome (FAI) occurs as a result of frequent pathologic contact between the femoral head-neck junction in the anterosuperior region and the acetabulum labrum, leading to articular and labral damage within the hip joint.
One classification of the condition as per a study conducted by Emara et al. involves functional resemblance to a cam impingement with the loss of asphericity from the femoral head to the neck anterolaterally, combined with a relative retroversion of the femoral head or a prominent portion engaging the articular surface of the acetabulum.
Another classification is a pincer impingement deformity involving a focal or global overcoverage of the femoral head by the anterior rim which produces a linear contact between the rim and femoral neck.
The pathophysiology of the two types of FAI were outlined in detail by Khan et al. in their study, with an emphasis on the predictable patterns of injury; the cam-type impingement has been found to occur mostly in young men, resulting in shear forces being applied from the aspherical portion of the femoral head as it articulates with the acetabulum.
This results in chondral delamination and detachment over time with the clinical presentation of the labral injury in cam-type FAI often involving detachment at the chondrolabral junction.
The pincer-type impingement, according to the authors, is seen frequently in women caused by repeated contact stress of a normal femoral head-neck against an abnormal area of the acetabulum – this could either be focal (for example, acetabular retroversion) or global (such as coxa profunda).
The biomechanical functioning of the hip is gradually affected by the consequent degeneration and tearing of the labrum in addition to the postero-inferior contre-coup cartilage lesion on the femoral head.
In order to decrease the abnormal mechanical contact between the acetabular edge and the femoral neck, it is important to improve hip range of motion which can also help reduce the risk of an individual developing pathologies to joints proximal and distal in the kinetic chain such as the pelvis and knee.
An active rehabilitation programme with stretching exercises designed to enhance hip external rotation and abduction in extension and flexion should be implemented in conjunction with the use of supportive foot devices.
Such devices can help in the treatment and management of any biomechanical discrepancies that could potentially increase abnormal movement patterns of the lower limbs including the hip – either preventing the onset of FAI and associated pathologies or improving ambulation in individuals diagnosed with FAI and associated pathologies.
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