a ball and socket joint prosthesis for use in arthroplasty is provided . the prosthesis includes a body for implantation at least partially within the medullary canal of a long bone . the long bone defines trabeculae in the proximal cancellous bone and lamellae in the cortical bone . the body includes a proximal portion thereof and a distal portion . the proximal portion has a medial periphery and includes surface features on a substantial portion of its proximal portion . the surface features are positioned to optimally transfer load from the prosthesis to the long bone .