A total knee replacement (arthroplasty) is an artificial joint designed to replace the arthritic knee

It is basically a curved metal cap on the end of the femur (thigh bone) and a flat metal tray on the top of the tibia (shin bone) with a piece of polyethylene (i.e. plastic) that sits between the two pieces of metal

This allows a low friction environment for the surfaces to glide

Knee replacement kinematics is a balance between letting the knee ligaments dictate the knee motion versus allowing the knee implant to force the knee motion to do what the surgeon thinks is best

For further information please visit: https://hipknee.aahks.org/total-knee-replacement/