A spacer device for the knee joint including a femoral component, a tibial component and an intermediate component, wherein the femoral component is adapted to be constrained to an end of the femoral bone in proximity to the knee joint, wherein the tibial component is adapted to be constrained to an end of the tibial bone in proximity to the knee joint, the femoral component being adapted to come into contact and to articulate with the tibial component, wherein the intermediate component is placed in use between the femoral component and the tibial component and wherein the constrained spacer device includes a first hinge and a second hinge adapted to rotatably constrain the femoral component to the tibial component.
