Effect of cementless bowed stem distal surface contour and coronal slot on femoral bone strains and torsional stability.

Six pairs of unembalmed cadaver femurs were instrumented with strain gauges and prepared with flexible reamers for insertion of long bowed cementless femoral stems. A fully porous-coated cobalt chrome stem was inserted into each left femur, and a distally fluted, slotted, stem of the same implant geometry and implant material was inserted into each right femur. Bone strains were measured during stem insertion and torsional stability tested after the stems were fully seated.

Impact biomechanics and pelvic deformation during insertion of press-fit acetabular cups.

Five fresh cadaver pelves were cleaned of soft tissue and instrumented with strain gauges. The acetabula were reamed, and a cementless cup, oversized at the periphery, was inserted. The applied force and cup acceleration were measured during insertion and used to calculate an effective mass of the cup, insertion device, and pelvis during each impact.