OA of the hip can be caused by a hip injury earlier in life. Changes in the alignment of the hip, e.g. after a fracture inside the hip joint or of the surrounding bones, can lead to uneven weight distribution through the hip joint.
This eventually leads to accelerated ‘wear and tear’ of the joint. Some people are born with an abnormality in the shape of the hip joint. This is known as developmental dysplasia of the hip (DDH). Severe cases of DDH are usually detected from birth or early in life, but milder forms of DDH may only begin to cause discomfort in adult life.
Avascular necrosis (AVN) is another cause of degeneration of the hip joint. In this condition, the femoral head (the ball portion of the femur, or thigh bone) loses a substantial portion of its blood supply and begins to die. The dying femoral head is unable to withstand the large forces that are transmitted through the hip joint during even normal activities like walking and climbing stairs, and becomes increasingly deformed. AVN has been linked to alcoholism, fractures and dislocations of the hip, and long-term steroid treatment for other diseases. In some cases, no cause can be identified. Early cases of AVN can usually be diagnosed using an MRI of the hip joint.
In many cases of hip OA, however, no definite cause can be identified. In such instances, the degeneration of the hip joint is probably related to the effects of ageing and ‘wear-and-tear’.
