[Dynamic force measurement in implantation of total endoprostheses of the hip joint]

The forces within the femoral shaft have been studied in preparation for the total hip replacement. The experimental device consisted of a personal computer connected with a digital enhanced measurement system which converted the data, that was received from the strain gauges, mounted on the femur. The bitochanter hip replacement designed by Ecke was used as an example of a press fit endoprosthesis which is anchored cementless. It was implanted in femora of cadavers. The results showed an extension of the femur at first within the intertrochanteric region, and as the rasp was further implanted, it showed at the distal end of the rasp a medial extension and a lateral traction with a delay of 3 ms, proving that it was a result of a medullary extension. The maximum forces applied with the metal hammer were 3500 N. Fractures and fissures were provoked and the result showed that they were mostly due to a misplacement of the rasp.