[Modern trend in artificial joints]

When the bone and joint are destroyed by rheumatoid arthritis, fractures involving joint, bone tumor and osteoarthritis, surgical intervention is indicated to replace affected joint by artificial joint. In 1984, about 27,400 surgeries were done in Japan, including 12,000 endoprosthesis of femoral head and 9,400 total hip replacement. Materials used for artificial joint are stainless alloy, alumina-ceramic, polyethylene and silicon-rubber. Methalcrylate bone cement is frequently used to get anchoring between artificial joint and skeletal tissue, however, it has disadvantage in case of revision. Recently many designs of artificial joint without bone-cement have been developing. It has been elucidated that resistance at friction between ceramic and polyethylene is ten times lessened than metal and polyethylene. Polycentric architecture which is modified from simple ball and socket is known to be that wearing of artificial joint and bone structure is able to be decreased. Durability will be much improved by not only selecting a material but also by devising suitable design. Infection associated with implant should be strictly avoided by using clean operating room and prophylaxis with antibiotics.