Medial Pivot

The medial pivot (MP) TKA traces its roots back to the Freeman-Samuelson (FS)-1000 system (Finsbury, UK) [1] developed by Freeman et al. in 1994. It was one of the models developed in the history of TKA which used the functional approach [2], which places emphasis on the wear resistance of polyethylene inserts. It was first introduced in Japan in 1998 by Wright Medical Inc.(USA) as the Advance® Medial Pivot Knee, and was subsequently introduced in 2001 by Kyocera Inc.(Japan) as the MPK®. The former was replaced with its successor model, Evolution®, which was introduced in 2010, and the latter was succeeded by the Physio Knee (JMM) in 2005. Furthermore, in 2011, the MGK Sphere (Medacta, Switzerland), which was developed based on the aforementioned research by Freeman et al. [3], was introduced in Japan. Currently (November 2021), there are four MP-type TKA models that being utilized in Japan: Advance, Evolution, Physio Knee, and MGK sphere.