Abstract: A knee joint prosthesis kit which is composed of a femoral component having a housing and a shank implantable in a femur, a first tibial component having a first hinge leaf and a shank implantable in a tibia, a second tibial component having a second hinge leaf and a shank implantable in a tibia, and a pintle which can pivotally connect the housing of the femoral component with that tibial component whose leaf is inserted into the housing. This enables the femoral component and the first tibial component to pivot relative to each other abut a first axis which is normal or nearly normal to the shanks of the coupled components so that the resulting prosthesis can serve as a flexion type prosthesis.