Wednesday, August 14, 2013

Hip Replacement

Arthritis affects the hip joint just as it affects the knee. Hip arthritis is less common in Indians and Asians. One disease that we commonly see is avascular necrosis (AVN). In AVN the blood supply to the head of the femur (thigh bone) is cut off due to some pathology. The most common reasons for AVN are alcohol intake and steroid medication. The dead femoral head loses its round shape and becomes flat and deformed. This leads to destruction of the hip joint and arthritis. Patients have severe pain in the hip. Movements become restricted and very painful.   In advance stages patients have difficulty in walking. They walk slowly with a limp usually with support of a stick or walker.
There are many non surgical and surgical treatments of AVN in the early stages. However in the late stages the only solution is total hip replacement (THR). Similarly end stage arthritis of the hip due to any cause can be successfully treated by hip replacement alone. Hip replacement has been around for more than 60 years. In this time hip replacement has seen a tremendous evolution. Hip replacement can be partial or total. In partial hip replacement, only the ball (head of femur) is replaced. The original cup of the patient is retained. This surgery is typically done for older patients who fracture the neck of femur (hip fracture).
In total hip replacement, both the ball and socket is replaced. This surgery is done for hip arthritis where both ball and socket are damaged. Originally in total hip replacement both components (stem and cup) were fixed to bone with bone cement (cemented hip). The cemented stem (which holds the ball) works very well and has a long life. However the cemented cup lasts only 10 to 12 years. The need to improve life of the prosthesis led to the evolution of uncemented hips. In uncemented design, the cup and the stem are fitted into the bone without using cement. The surface of the stem and cup is made very rough or porous. This allows the bone to grow into the surface. As a result of this bone growth, the life of the prosthesis improves tremendously.  
Originally in total hip replacement, the ball was made ofmetal and the cup was made of high density plastic (metal onplastic). The problem with plastic is that it wears out over time. There has been a big improvement in these materials over the years. The original plastic has undergone a series of changes (highly cross linked) which has improved the durability of the plastic. The biggest change has been the introduction of ceramic. Early ceramic was brittle and had issues of breakage. With later generations of ceramic, the breakage problem was solved. By using ceramic heads instead of metal ones, the wear of the plastic cups is reduced (ceramic on plastic). Then came the ceramic cups. By using a ceramic cup and ceramic ball (ceramic on ceramic), there is very little wear of the cup and the life of the prosthesis is improved drastically. Ceramic on ceramic THR is ideal for the younger patient as it is very durable and lasts a long time. However it is a technically sensitive surgery and has to be done perfectly. It is also very expensive.
Total hip replacement is a life altering surgery. After the initial couple of months which are required to recover from the surgery, the patient starts experiencing dramatic relief of pain. Pain literally and magically disappears. In most arthritic conditions of the hip, the leg becomes short and thisshortening is corrected immediately after surgery. Movements become free and painless. Patient is able to walk normally without a limp or pain. Some patients even manage to run after surgery. In short patients become normal after hip replacement surgery and are cured of their arthritis. With modern surgical techniques and newer prosthetic materials and designs, these patients are able to enjoy their hip replacements for a long, long time.

1 comment:

Sourabh Vishwakarma said...

Very useful and sound information on Hip Replacement with thorough detail on Hip replacement surgery.Thank You