Why Replace The Hip?
The hip is replaced because of the symptoms a person experiences, not just because they have any particular condition. There are three main symptoms that would suggest a hip replacement should be carried out:
Pain
This is the overriding reason for performing a hip replacement. The commonest cause of pain in the hip is osteoarthritis, often referred to as degenerative disease. It is important that both surgeon and patient consider preoperatively whether the pain level is sufficient to justify undertaking such a major procedure. If replacement is performed when pain levels are not high, the result can be disappointing for the patient. However, if a patient has had unremitting, deep-seated pain for many months or years, the effect of a total hip replacement can be dramatic.
Deformity
Due to contracture formation, or to previous disease, the hip can become very deformed. This can make walking impossible and hip replacement may be offered as treatment in such cases. Patients with deformed joints usually also experience pain and it is the presence of the pain in addition to the deformity that justifies the total hip replacement. To perform the operation for deformity alone can be successful in terms of range of movement and function, but may leave a disappointed patient. The operation does not provide a true replacement hip; the end result is an artificial hip. To expect an artificial hip to behave exactly like a normal one is unrealistic. This sometimes happens, but not always.
The Other Joints Need To Be Protected
When hip disease is advanced, it is possible for the joint to become so destroyed that pain diminishes. As destruction progresses, so the range of movement decreases and so the strains normally borne by the hip are taken up by the joints surrounding it - in particular, the knee and the spine. It is occasionally necessary to perform a hip replacement in order to protect these adjacent joints from further damage.
Diagrammatic representation of osteoarthritis of the hip joint. The articular cartilage (gristle) becomes eroded, exposing underlying bone. Soon the bone becomes hardened (eburnated) and increasingly painful. Cysts appear deep inside the bone and osteophytes develop - protrusions from the margins of a joint that can restrict movement