Joint Replacement - Hip Replacement

Conventional Total Hip Replacement (THR) is a very successful procedure for the treatment of arthritis of the hip, a condition causing considerable pain and loss of movement. The hip is a ball and socket joint, which allows the upper leg to move from side to side, back to front, and to rotate. The joint is made up of the head of the femur (the ball), which fits into the acetabulum (the socket). In the healthy hip, both the head of the femur and the acetabulum are covered with cartilage, a smooth surface which allows the joint to move freely.

How effective is a Hip replacement?
In the early 1960's, a British Surgeon called Sir John Charnley developed a new type of hip replacement called the low-friction arthroplasty which is still in use today. This procedure involves cutting the worn head off the femur and replacing it with a metal ball and stem in the shaft of the femur, and a plastic cup in the pelvis. Both are typically anchored to the bone by “bone cement”. This has become a very common surgical procedure and the implanted joints last for more than 20 years in the vast majority of patients.

What are the advantages of THR?
The main problem with Total Hip Replacement using polyethylene cups is that the polyethylene gradually wears, eventually reaching a point where the replacement joint no longer functions properly. In older people, with a lower activity level, this may not happen for 20 or more years, but in younger, more active patients, this may happen much sooner.

The other problem is that although the plastic itself is inert (well tolerated by the body) as the metal rubs against the plastic, tiny particles of the plastic are worn away. This plastic debris can cause an irritation. As the particles get between the bone and the artificial joint, this irritation causes surrounding bone to be absorbed by the body, leading to loosening of the artificial joint.

To overcome these problems in younger, more active patients requiring hip replacement, a different type of implant was needed and this was the reason Corin developed Hip Resurfacing.