[Dynamic force resistance of different osteosynthetic procedures in pertrochanteric femoral fractures (author's transl)].

In a comparative experimental study stability of different extra- and intramedullar methods of osteosynthesis for stable and unstable pertrochanteric fractures has been examined under dynamical stress. For the treatment of stable pertrochanteric fractures in old patients the intramedullar methods of osteosynthesis (nailing by Ender of Küntscher) were shown to be biomechanically superior. Extramedullar osteosyntheses (130 degrees and 95 degrees angled plate) also guaranteed very high stability; under permanent stress however angled plates showed metal fatigue. In case of unstable pertrochanteric fractures the osteosyntheses with additional application of bone cement produced sufficient stability under permanent stress. The importance of reconstructing a stable medial support for the biomechanics of osteosynthetic materials was emphasized. According to our results especially the combination of 95 degrees angle-plates with bone cement permits immediate mobilisation of old patients in case of unstable pertrochanteric fractures.