TKA Development in Japan: FNK

The Flexible Nichidai Knee (FNK) total knee system was developed through a joint research project collaboration with the Joint Group of the Department of Orthopaedic Surgery, Nihon University (Tokyo, JAPAN), and Nakashima Propeller Co., Ltd. (Okayama, JAPAN). The conventional imported total knee arthroplasty (TKA) implants used in Japan were designed to suit the bone shape and lifestyle of Westerners, resulting in problems such as size, weight, and low flexion angle after TKA in Japanese individuals. The FNK was developed based on the basic concept of “best suited to the bone shape and lifestyle of the Japanese.” The cruciate-retaining (CR) type was launched in 1995, followed by the posterior-stabilized (PS) type (Fig. 7.1) in 1998; since then, over 9000 cases have been performed in Japan.