Posterior stabilized mobile bearing knee

A posterior stabilized mobile bearing knee prosthesis, comprising:

• a femoral component having a medial condyle surface and a lateral condyle surface,
• a tibial tray having a platform with an elongated stem extending therefrom, the platform has an upper surface which mates with a downwardly extending anterior surface along an anterior edge, and
• a bearing positioned on the platform, the bearing having (i) a medial bearing surface configured to articulate with the medial condyle surface of the femoral component, (ii) a lateral bearing surface configured to articulate with the lateral condyle surface of the femoral component, (iii) a stem integrally formed with the bearing, the stem being received within a complementary bore in the tibial tray, and (iv) a spine integrally formed with the bearing, the spine being received within a notch in the femoral component,
• wherein the spine of the bearing contacts the femoral component such that at any position throughout the range of motion of the knee prosthesis, when viewed in a side elevational view, the anterior-most point of the bearing is positioned posteriorly of an imaginary line that is tangent to at least one of the medial condyle surface and the lateral condyle surface of the femoral component and intersecting a point on the anterior edge of the platform of the tibial tray.

A posterior stabilized mobile bearing knee prosthesis, comprising:

• a femoral component having (i) a pair of condyle surfaces spaced apart to define a notch therebetween, (ii) an anterior femoral cam positioned in the notch, and (iii) a posterior cam positioned in the notch,
• a tibial tray having a platform with an elongated stem extending therefrom, and
• a bearing positioned on the platform, the bearing having (i) a pair of bearing surfaces configured to articulate with condyle surfaces of the femoral component, and (ii) a spine extending integrally formed with the bearing and upwardly into the notch, the spine having an anterior tibial cam,
• wherein the anterior femoral cam and the anterior tibial cam are configured such that the anterior femoral cam contacts the anterior tibial cam at and beyond a predetermined degree of hyperextension, so as to cause the femoral component to roll anteriorly relative to the bearing during hyperextension beyond the predetermined degree of hyperextension.

A posterior stabilized mobile bearing knee prosthesis, comprising:

• a femoral component having a pair of condyle surfaces spaced apart to define a notch therebetween, an anterior femoral cam is positioned in the notch,
• a tibial tray having a platform with an elongated stem extending therefrom, and
• a bearing positioned on the platform, the bearing having (i) a pair of bearing surfaces configured to articulate with condyle surfaces of the femoral component, and (ii) a spine extending integrally formed with the bearing and upwardly into the notch, the spine having an anterior tibial cam,
• wherein when the tibial tray has a posterior inclination of 7° (i) the anterior femoral cam engages the anterior tibial cam at about 6° of hyperextension, and (ii) the anterior femoral cam engages the anterior tibial cam such that the femoral component anteriorly rolls relative to the bearing throughout a range of about 11°-18° of hyperextension.