patent number 4642124
An improved hip prosthesis designed to simulate forces on a femur like those experienced by a normal, healthy femur. A ball is located atop the prosthesis at a proper anatomical angular relationship with a neck and collar therebelow. The prosthesis stem extends from the collar to a distal tip and includes a buttress section, a middle section and tip section. An inner surface of the buttress section is relieved and a compressible material is located thereat. The middle and tip sections of the stem are smooth, of common cross section, without any significant taper and the tip is adapted to avoid transmission of significant axial forces to the femur therebelow. When implanted with a luting agent, the majority of forces are axial compressive forces applied to the calcar and there is little or no wedging of the prosthesis in the medullary canal; little or no shear forces across the prosthesis - luting agent interface; and little or no axial stresses from the prosthesis tip distal to same.
Clemson University (Clemson, SC)