Progress in Total Knee Arthroplasty : Deep Flexion

Total knee arthroplasty (TKA) is usually recommended for patients who have osteoarthritis (OA) and rheumatoid arthritis (RA) when conservative treatment is not effective. Since total condylar knee (I/B type I) was developed in 1973, the outcome of TKA has gotten better. Artificial knee joints can last for more than 10 years at present, and could last twenty years in the near future, especially with those for OA. Artificial knee joint was originally developed in the U.S. and Europe where sitting style of the people differs from ours. Therefore, artificial knee joint was designed to flex to a maximum of 120 degrees, enabling one to tie shoe strings. Deep knee flexion of more than 130 degrees, which suits Japanese daily-life sitting style: sitting upright with their legs folded under them, has not been considered. Recently, on the basis of good long term clinical results of TKA, artificial knee joint that enables deep knee flexion was developed by the Japanese researchers and has been used clinically in Japan. Deep knee flexion significantly improves Japanese ADL. On the other hand, TKA may have shorter lifespan because unexpected complications could occur from deep flexion after TKA