Endoprosthetic rotating hinge knee assemblies, subassemblies, and methods

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;
• and
• 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 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 and substantially parallelly to the midline axis, and
• wherein an offset distance separates the midline axis from the reference axis.

A rotating hinge subassembly comprising:

• a tibial yoke comprising:
• a head defining a transverse hinge bore extending through a first lateral side and a second lateral side of the head,
• a tibial axial post extending away from the head, and
• a body member disposed between the head and the tibial axial post, the body member separating the head from the tibial axial post by an offset distance;
• a femur box comprising:
• a first arm and a second arm extending posteriorly from a main body portion,
• the main body portion having a femoral fastening mechanism configured to engage a transverse surface of a femur box cavity of a femoral component of a knee joint endoprosthesis,
• wherein the first arm and the second arm respectively define axially aligned first and second arm bores,
• wherein the first arm is adjacently disposed to the first lateral side and the second arm is adjacently disposed to the second lateral side such that the first arm bore and the second arm bore axially align with the transverse hinge bore;
• a transverse hinge pin extending through the transverse hinge bore and into the first arm bore and the second arm bore.

A rotating hinge subassembly comprising:

• a tibial yoke comprising:
• a body member having a head disposed at a first end, and
• 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 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 orthogonally through the transverse axis and parallelly to the midline axis, and
• wherein an offset distance separates the midline axis from the reference axis;
• a femur box comprising:
• a first arm extending posteriorly from a main body portion,
• a second arm extending posteriorly from the main body portion,
• the second arm opposing the first arm,
• the main body portion defining a femoral fastening mechanism configured to engage a transverse surface of a femur box cavity of a femoral component of a knee joint endoprosthesis,
• wherein the first arm defines a first bore,
• wherein the second arm defines a second bore,
• wherein the first bore axially aligns with the second bore,
• wherein the first arm is adjacently disposed to the first lateral side and the second arm is adjacently disposed to the second lateral side such that the first bore and the second bore axially align with the transverse hinge bore;
• and
• a transverse hinge pin extending through the transverse hinge bore and into the first bore and the second bore to thereby hingedly engage the femur box to the head of the yoke.

A knee joint endoprosthesis comprising:

• a tibial component;
• a femoral component;
• and
• a rotating hinge subassembly having a first joint element configured to be coupled to the femoral component while having a second joint element being configured to be disposed in the tibial component, while being rotatable around a rotational axis in the tibial component, the rotating hinge subassembly comprising:
• a first joint element and a second joint element hingedly coupled to the first joint element,
• the first joint element defining:
• an engaged position, wherein the first joint element is disposed in the femoral component and engages the femoral component in a locking manner, and
• a disengaged position, wherein the first joint element is fully separated from the femoral component,
• wherein:
• the first joint element defines an engagement direction, wherein the first joint element is movable relative to the femoral component for transferring the first joint element from the disengaged position into the engaged position, and
• the engagement direction runs sagittally to the rotational axis.