Compound osteosynthesis of pathological fractures of the proximal femoral shaft. Experimental studies on the biomechanical effects of additional intramedullary splinting.

The biomechanical stability of two compound osteosynthesis techniques with and without intramedullary splinting were compared in 20 paired cadaver femora. Group A was stabilised using a contoured 12-hole DC plate and polymethylmethacrylate cement. In group B an additional intramedullary semi-diameter osteosynthesis plate was inserted parallel to the outer plate and transfixed with the same screws. The specimens were tested in a universal testing machine using a force applied to the specimen at 45 degrees to the load to provoke the most unfavourable condition, consisting of a bending moment and torsion. Both force and extension were recorded. The compound osteosynthesis with an additional intramedullary plate (group B) reached an average higher load stability. This increase of stability was not significant statistically.