Femoroacetabular Impingement

What is Femoroacetabular Impingement?

Femoroacetabular impingement (FAI) is a complex condition that arises from structural abnormalities within the hip joint, leading to significant biomechanical challenges and potential long-term consequences. The primary characteristic of FAI is hip pain, which presents as a result of the bones of the ball and socket hip joint being abnormally shaped, thereby causing impingement, rubbing, irritation, and ultimately, damage to the joint.

There are three distinct types of abnormalities associated with FAI, each contributing to the mechanical dysfunction of the hip joint.

1. CAM Impingement:
This type of impingement involves an abnormality in the ball aspect of the femoral head, which is the rounded end of the thigh bone. In CAM impingement, the femoral head is not perfectly round, which hinders its smooth rotation within the acetabulum (the socket of the hip joint). As a result, during hip movements, such as flexion and rotation, the non-spherical shape of the femoral head causes it to abut against the acetabular rim, leading to impingement and subsequent damage.

2. Pincer Impingement:
Contrary to CAM impingement, pincer impingement involves an abnormality of the acetabulum itself. In this scenario, there is typically an extra bony extension around the rim of the acetabulum, resulting in a deeper and more constricted socket. As the femoral head moves within this deeper socket during activities, it can impinge against the overhanging bony structure of the acetabulum, causing friction, irritation, and potential damage to the joint surfaces.

3. Combined CAM and Pincer Impingement:
The third type of abnormality seen in FAI is a combination of both CAM and pincer impingements. In these cases, individuals exhibit deformities in both the femoral head and the acetabulum, amplifying the impingement and mechanical stress experienced by the hip joint during movement.

The structural abnormalities associated with FAI not only lead to impingement-related symptoms but also contribute to progressive damage to the articular cartilage, which lines the surfaces of the hip joint. Continuous rubbing and friction due to impingement can result in chondral damage, characterised by thinning or loss of the cartilage. This, in turn, can pave the way for early degenerative changes, such as the development of osteoarthritis within the hip joint.

Clinically, FAI often presents with pain localised to the anterior (front) aspect of the hip. This pain is made worse by activities that involve repetitive hip flexion, rotation, and sudden changes in direction, such as running, squatting, or pivoting movements. Understanding the specific abnormalities and biomechanical consequences of FAI is crucial for accurate diagnosis, targeted treatment strategies, and effective management to mitigate further joint damage and improve patient outcomes.

If you are suffering from Femoroacetabular Impingement (FAI), we have a team who is ready to help you and get you on the road to recovery. Book an appointment with Precision Health today!

Call us on (02) 9639 7337 or book online.

National Center for Biotechnology Information (NCBI). (2023). Femoroacetabular Impingement. StatPearls. Available at: https://www.ncbi.nlm.nih.gov/books/NBK547699/ (Accessed: 27 March 2024).

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