Femoroacetabular impingement (FAI) has become an increasingly recognized cause of hip pain, especially in young active adults Accordingly, the body of knowledge surrounding the understanding and management of FAI has...
Femoroacetabular impingement (FAI) has become an increasingly recognized cause of hip pain, especially in young active adults Accordingly, the body of knowledge surrounding the understanding and management of FAI has grown substantially. It is imperative for sports medicine clinicians to understand current principles and best practices regarding the pathophysiology, diagnosis, and treatment of FAI Pathophysiology FAI is defined as “a pathologic mechanical process by which morphologic abnormalities of the acetabulum and/or femur combined with vigorous hip motion lead to repetitive collisions that damage the soft-tissue structures within the joint itself”. Notable soft-tissue structures include the acetabular labrum and the articular cartilage of the femoroacetabular joint.FAI has been traditionally classified into two distinct types: pincer impingement ( However, it is common to find both types of FAI in combination within the same hip Both cam and pincer deformities are characterized by a unique set of pathological bony malformations and abnormal hip biomechanics.
The epidemiology of FAI has been difficult to quantify. This is due to diagnostic challenges, including the presence or absence of radiographic morphologies and difficulty quantifying the exact degree of impingement (Brukner & Khan).Pincer impingement may occur due to a bony overgrowth located along the anterolateral rim of the acetabulum, exaggerated retroversion of the acetabulum (anterior overcoverage), or a deepened acetabular socket (coxa profunda). With repetitive hip flexion, the acetabular labrum is crushed between the abutment of the acetabular rim and the femoral head or neck.
The leverage produced by this persistent abutment may even cause a contrecoup injury to the the opposite region of the acetabular cartilage in some instances. Few studies have specifically investigated the process by which these anatomical anomalies develop, thus the etiology of pincer impingement is not well understood (Brukner & Khan). Pincer impingement is commonly observed in active middle-aged women.
Cam impingement occurs due to the rotation of a non-spherical femoral head within the acetabulum. The term “cam” refers to the projection on a rotating part of machinery, similar to that of a camshaft in an automobile. Cam deformities may stem from multiple etiologies, the first of which may arise from a slipped capital femoral epiphysis.
The slipped epiphysis causes an asymmetry of the anterior femoral neck, thus leading to a misalignment within the joint. Cam impingement is more common in young, athletic males compared to any other demographic. It’s incidence ranges from about 15 to 25% in this group, in contrast to 5% in the general population.Another etiology of cam impingement is based on the theory that vigorous sporting activity in adolescence may cause premature closure of the capital physis, but more evidence is needed to validate this theory.
If you are experiencing symptoms that may be related to femoroacetabular impingement syndrome, it is important to see a sports medicine physician. Early evaluation and treatment typically lead to better outcomes. Do not ignore pain or symptoms that are limiting your activity.
*This article is for educational purposes only and does not substitute for professional medical advice. Always consult a qualified healthcare provider.*
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