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For the anchorage of femoral prosthesis stems in total hip arthroplasty, various cement application techniques are used. Experimental comparison of these techniques requires a set-up in which only the cementing technique itself is tested. We used a computer-controlled implantation device based on a milling machine and standardized artificial femur models. The stems are reproducibly positioned by the machine and any influence of manual positioning during the implantation is excluded. The results can be evaluated macroscopically and radiologically with no interference by disturbing bone--with sufficient sensitivity to objectify differences in cement quality. The increase in pressure in the peripheral medullary cavity, which is responsible for the embolisation, can be determined experimentally for the individual cementing technique. The experimental implantation device described enables a standardized comparison of various cementing techniques.

The displacement of the femoral epiphysis in epiphyseolysis capitis femoris is usually determined by measuring both the epiphysis-diaphysis angle (ED angle) in the plane of the dislocation and the epiphysis-torsion angle (ET angle) in the torsional plane. In this paper we define an epiphyseal version angle (EV angle) in the sagittal plane of the femur, calculate it trigonometrically and show it in diagrams and tables. The clinical application of the EV angle indicates that in cases of displacement with an ED angle of less than 135 degrees, absolute displacement is better shown than with the ET angle. Additionally, the EV angle improves our comprehension of the 3-D displacement due to the fact that, in the "Lauenstein" x-ray, the femur is increasingly projected more in a sagittal plane with increasing abduction. The essential correction using the Imhäuser-osteotomy is also done in the sagittal plane. The ability of the orthopaedic surgeon to visualize the situation in three dimensions is also improved by this additional standard plane.