Total knee replacement prosthesis with high order NURBS surfaces

A knee replacement prosthesis having anterior, posterior, lateral, medial, distal and proximal sides and sagittal, coronal and transverse planes, comprising:

• a) a femoral component that connects to the distal end of a resected femur, said femoral component including medial and lateral condyles having distal, articulating surfaces, and a patellar flange having an articulating patellar surface;
• and,
• b) a tibial component that connects to the proximal end of a resected tibia, said tibial component including a proximal bearing surface with medial and lateral concavities that articulate with said medial and lateral condyles;
• wherein said prosthesis enables anterior-posterior translation of the femur relative to the tibia, and
• wherein said prosthesis restricts axial tibial rotation during initial flexion to an intermediate point and enables axial tibial rotation after the prosthesis has been flexed beyond the intermediate position to full flexion.

A knee replacement prosthesis having anterior, posterior, lateral, medial, distal and proximal sides and sagittal, coronal and transverse planes, comprising:

• a) a femoral component that connects to the distal end of a resected femur, said femoral component including medial and lateral condyles having distal, articulating condylar surfaces, and a patellar flange having an articulating patellar surface;
• and,
• b) a tibial component that connects to the proximal end of a resected tibia, said tibial component including a proximal bearing surface with medial and lateral concavities that articulate with said medial and lateral condyles;
• wherein said condylar surfaces and said concavities are substantially defined by high order nonrational B spline surfaces.

A method of making a knee replacement prosthesis having anterior, posterior, lateral, medial, distal and proximal sides and sagittal, coronal and transverse planes, comprising the steps of:

• a) a femoral component that connects to the distal end of a resected femur, said femoral component including medial and lateral condyles having distal, articulating surfaces, and a patellar flange having a patellar articulating surface;
• and,
• b) a tibial component that connects to the proximal end of a resected tibia, said tibial component including a proximal bearing surface with medial and lateral concavities that articulate with said medial and lateral condyles;
• c) modeling said condylar surfaces and said concavities using NURBS.