Disorders Which Might Occur With The Hip
The hip can be described as ball and socket joint. The ball component is referred to as the femoral head, it is at the end of the thigh bone (femur). The socket is known as the acetabulum and this is part of the pelvis. The joint surfaces that push against each other are protected with a structure called cartilage which is lubricated with fluid; this permits the joint to move with no friction. Encompassing the hip joint are the capsule, ligaments, muscles, fascia, nerves and blood vessels. There’s a structure called the labrum which attaches to the boney rim of the acetabulum which serves to deepen the socket and have a function as a vacuum seal.
Femoral Acetabular Impingement (FAI)
The shape, size and form of the hip joint can fluctuate from person to person. This may be from how we are genetically programmed, or how the hip joint develops as we go from childhood to adulthood, or other reasons such as injury or pathology. Listed below, we have attempted to simplify the distinct types of boney differences which often can cause impingement, but it is important to realise 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 affected, and this results in ‘pinching’ of the hip joint structures when the hip joint moves, thus termed impingement. In a few individuals, there is global overcoverage (involves the whole socket), and this is known as Coxa Profunda.
2.CAM – This term refers to a boney lump that is found towards the top of the thigh bone (femoral neck). This lump can make the ball of the hip joint less spherical, and and once the hip joint moves, this lump can rub or catch against the hip joint structures.
3.CAM/PINCER MIXED IMPINGEMENT – Sometimes there might be overcoverage of the socket (pincer/coxa profunda) and and with this, the boney bump (CAM) on the femur.
Hip Dysplasia
This is a problem where the socket is not covering the ball (femoral head), sufficiently. There are various degrees of this. Measurements referred to as the ‘centre edge angle’ are taken from the xray to determine how much lack of coverage there is. Some patients are offered a specific operation by consultant Surgeons termed a peri-acetabular osteotomy (PAO) to help fix this.
Hip Labral Tears
The fibrocartilagenous labrum which encompasses the socket can occasionally be torn or become degenerate. There are various categories of this and it can be caused by various reasons including through injury or hip joint abnormalities such as FAI and dysplasia.
If you are affected by any of the injuries described in this article, you should consult your nearest hip physio.
By Louise Grant Physio in North Leeds