An ankle prosthesis implant is disclosed herein. The ankle prosthesis implant includes a talar implant defining a superior bearing surface. The superior bearing surface includes a convex portion and a concave portion. The convex portion is defined in an anterior-posterior direction when viewed from a sagittal plane and has a neutral axis (X1) defined in a coronal plane at an anterior-posterior midline of the talar implant and extending in a medial-lateral direction. The concave portion is defined in the medial-lateral direction when viewed from the coronal plane, and the concave portion is swept about a secondary axis (X2) that is angled relative to the neutral axis (X1) upwards towards a medial end of the talar implant by an angle ().

A blade-like stem of a hip joint prosthesis for anchoring in the femur, including a prosthesis neck portion and a femur-anchoring portion extending therefrom and having a proximal end and a distal end, the femur-anchoring portion including a proximal arcuate portion extending from a location adjacent the proximal end and having a radius of curvature that changes in a distal-to-proximal direction, and the femur-anchoring portion further including a distal tapered portion extending from the proximal arcuate portion toward the distal end.

A blade-like stem of a hip joint prosthesis for anchoring in the femur, including a prosthesis neck portion and a femur-anchoring portion extending therefrom and having a proximal end and a distal end, the femur-anchoring portion including a proximal arcuate portion extending from a location adjacent the proximal end and having a radius of curvature that changes in a distal-to-proximal direction, and the femur-anchoring portion further including a distal tapered portion extending from the proximal arcuate portion toward the distal end.