An assembly for the preparation of the proximal surface of the tibia for a tibia component of a prosthetic knee joint, said arrangement including: a tibia and femoral stability gap preparation plate and a joint liner, said tibia and femoral stability gap preparation plate adapted to be placed upon an initially resected proximal surface of the tibia, said tibia and femoral stability gap preparation plate further including an upper side, said upper side having a plurality of user operable height adjustable extension tabs (13, 14, 15), wherein each user operable height adjustable extension tab (13, 14, 15) is adapted to engage an underside of the joint liner, wherein said joint liner includes an upper articulated surface configured to engage a femoral component of the prosthetic knee joint, such that a height adjustment of said plurality of user operable height adjustable extension tabs (13, 14, 15) defines a stability gap as a measurement taken in each of extension, mid-flexion and flexion, wherein the stability gap is commensurate with a reference plane defined on the underside of the joint liner, characterised in that a final bone resection of the proximal surface of the tibia consistent with said reference plane provides for balanced angular movement between the tibia component and the femoral component of a prosthetic knee joint throughout an arc of motion from extension, mid-flexion and flexion; wherein the assembly comprises a final bone resection of the proximal surface of the tibia cutting guide arrangement, said final bone resection of the proximal surface of the tibia cutting guide arrangement including a cutting guide having an indicator in the form of a slot, wherein the slot provides a reference guide for a cutting blade or saw to cut the final bone resection of the proximal surface of the tibia; said joint liner and said final bone resection of the proximal surface of tibia cutting guide arrangement including a mounting arrangement, wherein the mounting arrangement is configured to provide a first mounted position between said joint liner and said final bone resection of the proximal surface of tibia cutting guide arrangement, wherein the slot is aligned with the same referenced plane as the referenced plane defined by the underside of the joint liner; and said mounting arrangement further configured to provide a second mounted position wherein the slot aligned with the same referenced plane of the underside of the joint liner is below the first mounted position and below the initial resected proximal surface of the tibia. a tibia and femoral stability gap preparation plate and a joint liner, said tibia and femoral stability gap preparation plate adapted to be placed upon an initially resected proximal surface of the tibia, said tibia and femoral stability gap preparation plate further including an upper side, said upper side having a plurality of user operable height adjustable extension tabs (13, 14, 15), wherein each user operable height adjustable extension tab (13, 14, 15) is adapted to engage an underside of the joint liner, wherein said joint liner includes an upper articulated surface configured to engage a femoral component of the prosthetic knee joint, such that a height adjustment of said plurality of user operable height adjustable extension tabs (13, 14, 15) defines a stability gap as a measurement taken in each of extension, mid-flexion and flexion, wherein the stability gap is commensurate with a reference plane defined on the underside of the joint liner, characterised in that a final bone resection of the proximal surface of the tibia consistent with said reference plane provides for balanced angular movement between the tibia component and the femoral component of a prosthetic knee joint throughout an arc of motion from extension, mid-flexion and flexion; wherein the assembly comprises a final bone resection of the proximal surface of the tibia cutting guide arrangement, said final bone resection of the proximal surface of the tibia cutting guide arrangement including a cutting guide having an indicator in the form of a slot, wherein the slot provides a reference guide for a cutting blade or saw to cut the final bone resection of the proximal surface of the tibia; said joint liner and said final bone resection of the proximal surface of tibia cutting guide arrangement including a mounting arrangement, wherein the mounting arrangement is configured to provide a first mounted position between said joint liner and said final bone resection of the proximal surface of tibia cutting guide arrangement, wherein the slot is aligned with the same referenced plane as the referenced plane defined by the underside of the joint liner; and said mounting arrangement further configured to provide a second mounted position wherein the slot aligned with the same referenced plane of the underside of the joint liner is below the first mounted position and below the initial resected proximal surface of the tibia.