Constrained prosthesis (1) for the knee joint comprising a femoral component (2) a tibial component (3) and an intermediate component (30) wherein the femoral component (2) is suitable for being constrained to an end of the femoral bone in proximity to the knee joint wherein the tibial component (3) is suitable for being constrained to an end of the tibial bone in proximity to the knee joint the femoral component (2) being suitable for coming into contact and being articulated with the tibial component (3) wherein the intermediate component (30) is placed in use between the femoral component (2) and the tibial component (3) and wherein the constrained prosthesis (1) comprises a first hinge (32a) and a second hinge (32b) adapted to rotatably constrain the femoral component (2) to the tibial component (3).
