[Experimental studies of the loading capacity and deformation of pertrochanter osteotomies in extra and...

52 human femora were examined for stabilization behaviour of pertrochanteric osteotomies as well as the significance of the osteotomy angle by intramedullary osteosynthesis with Ender nailing and by extramedullary osteosynthesis using a 145 degrees angular plate. The maximum stress tolerance of both osteosynthesis procedures in femora with flat angle osteotomies is only marginally different, but the stress tolerance of Ender nailing is much less in the steep osteotomies. With steep osteotomy angle the plastic as well as the entire distorsion of the osteosynthesis increased considerably. The distorsion following Ender nailing compared to the 145 degrees angular plating is approximately the same. With increased osteoporosis a decrease of stability and an increase of distorsion is found. This correlation is even more pronounced by steep angular osteotomy. In some cases the exact opposite can be found, so that the maximum stress can not be concluded from the osteoporosis degree found on an x-ray.