Patent ID: 8137407

Claim:
A mobile bearing knee prosthesis apparatus, comprising: a tibial plate including a medial lobe and a lateral lobe conjoined in a dividing plane; a protuberance extending from the tibial plate, the protuberance including a protuberance sidewall, the protuberance sidewall being bisected by the dividing plane and including a pair of opposing eccentric convex arcuate portions, the pair of opposing eccentric convex arcuate portions including a first convex arcuate portion having a curvature radius relative to an axis medially offset from the dividing plane and a second convex arcuate portion having a curvature radius relative to an axis laterally offset from the dividing plane; and a tibio femoral insert defining a slot having a generally lateral-side curvature radius roughly equal to the curvature radius of the first convex arcuate portion of the protuberance sidewall and a generally medial-side curvature radius, a lateral-side curvature radius origin defined by said lateral-side curvature radius medially offset from the dividing plane, a medial-side curvature radius origin defined by said medial side curvature radius medially offset from the dividing plane; wherein the tibio-femoral insert is rotatable relative to the tibial plate about the medially offset axis when the protuberance sidewall is positioned in the slot.