Disorders With The Hip Joint

The hip is known as a ball and socket joint. The ball element is called the femoral head, and is at the end of the thigh bone (femur). The socket is called the acetabulum and this is part of the pelvis. The joint surfaces that move against each other are protected with a structure called cartilage that is lubricated with fluid; this allows the joint to move with no resistance. Encompassing the hip joint are the capsule, ligaments, muscles, fascia, nerves and blood vessels. There exists a structure called the labrum which attaches to the boney rim of the acetabulum which serves to deepen the socket and have a operate as a vacuum seal.

Femoral Acetabular Impingement (FAI)

The shape, size and form of the hip joint can fluctuate from one person to another. This may be from how we are genetically programmed, or how the hip joint develops as we go from youth to maturity, or other reasons such as injury or pathology. Directly below, we have attempted to simplify the distinct types of boney differences which could cause impingement, but it is essential to understand that there can be various degrees of these and variants.

1.PINCER - This is when the boney rim of the socket (acetabulum) is covering more of the ball (femoral head) than in the average hip. A specific area of the socket is afflicted, and this causes 'pinching' of the hip joint structures when the hip joint moves, thus termed impingement. In a few individuals, there is global overcoverage (involves the entire socket), and this is named Coxa Profunda.

2.CAM - This phrase refers to a boney bump that is present near the top of the thigh bone (femoral neck). This bump can make the ball of the hip joint less spherical, and and once the hip joint moves, this bump can rub or snare against the hip joint structures.

3.CAM/PINCER MIXED IMPINGEMENT - From time to time there may be overcoverage of the socket (pincer/coxa profunda) and additionally, the boney bump (CAM) on the femur.

Hip Dysplasia

This is a condition where the socket is not covering the ball (femoral head), sufficiently. There are various levels of this. Measurements called the 'centre edge angle' are obtained from the xray to establish how much deficiency of coverage there is. Some patients are offered a precise operation by specialist Surgeons referred to as a peri-acetabular osteotomy (PAO) to help fix this.

Hip Labral Tears

The fibrocartilagenous labrum which encompasses the socket can at times be torn or become degenerate. There are various categories of this and it can be brought on by various factors including through injury or hip joint abnormalities such as FAI and dysplasia.

By Louise Grant Physiotherapist in Leeds