An endoprosthetic tibial yoke for a rotating hinge subassembly comprising: a body member having a head disposed at a first end of the body member ; a tibial axial post extending from a second end of the body member , the second end being distally disposed from the first end , the head defining a transverse hinge bore extending through a first lateral side and a second lateral side of the head , the transverse hinge bore defining a transverse axis (TR) extending transversely through the transverse hinge bore , the tibial axial post defining a midline axis extending longitudinally through the tibial axial post , wherein a reference axis extends substantially orthogonally through the transverse axis (TR) and substantially parallelly to the midline axis and an offset distance (D) separates the midline axis from the reference axis, characterized in that the endoprosthetic tibial yoke further comprises an extension stop portion extending between the head and the tibial axial post , wherein the extension stop portion comprises snap-fit pockets and the tibial yoke further comprises a modular extension stop having locking tabs extending from a bottom of the modular extension stop , the locking tabs being configured to extend into the snap fit pockets of the extension stop portion of the yoke when the modular extension stop is in an installed position. a body member having a head disposed at a first end of the body member ; a tibial axial post extending from a second end of the body member , the second end being distally disposed from the first end , the head defining a transverse hinge bore extending through a first lateral side and a second lateral side of the head , the transverse hinge bore defining a transverse axis (TR) extending transversely through the transverse hinge bore , the tibial axial post defining a midline axis extending longitudinally through the tibial axial post , wherein a reference axis extends substantially orthogonally through the transverse axis (TR) and substantially parallelly to the midline axis and an offset distance (D) separates the midline axis from the reference axis, characterized in that the endoprosthetic tibial yoke further comprises an extension stop portion extending between the head and the tibial axial post , wherein the extension stop portion comprises snap-fit pockets and the tibial yoke further comprises a modular extension stop having locking tabs extending from a bottom of the modular extension stop , the locking tabs being configured to extend into the snap fit pockets of the extension stop portion of the yoke when the modular extension stop is in an installed position. the head defining a transverse hinge bore extending through a first lateral side and a second lateral side of the head , the transverse hinge bore defining a transverse axis (TR) extending transversely through the transverse hinge bore , the tibial axial post defining a midline axis extending longitudinally through the tibial axial post , wherein a reference axis extends substantially orthogonally through the transverse axis (TR) and substantially parallelly to the midline axis and an offset distance (D) separates the midline axis from the reference axis, characterized in that the endoprosthetic tibial yoke further comprises an extension stop portion extending between the head and the tibial axial post , wherein the extension stop portion comprises snap-fit pockets and the tibial yoke further comprises a modular extension stop having locking tabs extending from a bottom of the modular extension stop , the locking tabs being configured to extend into the snap fit pockets of the extension stop portion of the yoke when the modular extension stop is in an installed position. <EOS>