Arthroplasty devices configured to reduce shear stress

A prosthesis for implantation into a bone, comprising:

• a sleeve having an inner passageway containing a central opening with at least one channel located on the periphery of said central opening, and an outer surface, sized to fit tightly within the bone, containing at least one section contacting the bone, said section having a textured surface to promote bone ingrowth;
• and a rod component comprising an elongated shank having an outer surface extending between a proximal end and a relatively narrow distal end, with at least a portion of said shank having at least one lobe extending therefrom, said portion of said shank sized to fit within said inner passageway of said sleeve;
• wherein when said rod component is inserted through said sleeve which has been inserted tightly into the bone, the interaction between said lobe of said shank of said rod component and said channel within said sleeve allow for a small amount of rotation, thus reducing torsional shear stress between said prosthesis and the bone.