Abstract: A cementless femoral stem prosthesis for use in hip replacement surgery is disclosed. The stem has a collar and a body having a fixed end and a shank end. The shank end is divided into a pair of adjustable endosteal plates that are secured to the cortical bone of the femur by screws. The present invention provides an improved femoral stem structure because the screws through the endosteal plates transfer the load to the cortical bone rather than the cancellous bone, the medial endosteal plate has a plurality of spurs to engage with the cancellous bone to increase the number of stress-strain points, and the collar transfers the load directly to the cortical bone. All of these features work in tandem to reduce the risk of stress shielding, bone resorption, prosthetic loosening, and other difficulties associated with femoral stem prostheses.

Abstract: A cementless femoral stem prosthesis for use in hip replacement surgery is disclosed. The stem has a collar and a body having a fixed end and a shank end. The shank end is divided into a pair of adjustable endosteal plates that are secured to the cortical bone of the femur by screws. The present invention provides an improved femoral stem structure because the screws through the endosteal plates transfer the load to the cortical bone rather than the cancellous bone, the medial endosteal plate has a plurality of spurs to engage with the cancellous bone to increase the number of stress-strain points, and the collar transfers the load directly to the cortical bone. All of these features work in tandem to reduce the risk of stress shielding, bone resorption, prosthetic loosening, and other difficulties associated with femoral stem prostheses.

Abstract: A cementless hip resurfacing prosthesis is provided. The prosthesis comprises a metallic cap that is fitted over the individual's femoral head to provide a new acetabular articulating surface. The metallic cap is affixed to the femur via a locking means extending from the inner surface of the metallic cap, which engages with a complimentary tubular fixation means attached to a plate. The plate is affixed to the lateral surface of the femur via a fixation screw, which extends through the fixation means, through the locking means, and engages with a complimentary threaded portion within the locking means. The plate is further affixed to the femur via a plurality of cortical screws, which also act to distribute the forces from the hip joint to avoid stress shielding and bone resorption effects commonly associated with hip replacement prostheses. Furthermore, the present invention is designed to reduce shear stresses on the femoral neck.