A knee prosthesis in one embodiment includes a femoral component having a notch defined between spaced apart medial and a lateral condyle surfaces, the notch defining an elongated cam housing having a posterior cam at one end of the cam housing, and a tibial component including (i) a platform, (ii) a bearing supported on and rotatable in relation to the platform, the bearing defining medial and lateral bearing surfaces, and (iii) a spine projecting superiorly from the bearing within the cam housing, wherein the spine includes an anterior face and an opposite posterior face facing the posterior cam when the medial and lateral condyle surfaces are in articulating contact with the medial and lateral bearing surfaces, wherein the posterior face of the spine is concave along substantially the entire height of the spine, and wherein the spine terminates in a convex rounded posterior peak.
