We have already reported that the results of the surgical treatment for trochanteric fractures of the femur with Ender nailing and Kuntscher condylo -cephalic nailing were nearly the same. However, in the Kuntscher condylo - cephalic nailing group, we found more cases with problems with rotation, and in the Ender nailing group more shortening and varus deformity cases.
In order to investigate which method is superior biomechanically, compression stress tests and rotation stress tests were studied with the strain gauge method using cadaver wet bones. A two-legged stance method was taken. We used a 8mm Kuntscher nail and three 4mm Ender nails; one antevevsion nail, one varus nail and one standard nail. After that we osteotomized the femoral models through trochanters and made a stable type model, and an unstable type model according to Evans' classification, type 1 group 4.
Two displacement transducers were fixed over the osteotomized site, one anteromedially, one posteromedially. There were no obvious differences between Ender nailing and Kuntscher nailing in compression stress tests. But in rotation stress tests, Ender nailing was slightly superior.
It could be concluded that under such stress, the three diverged elastic Ender nails holds the proximal fragment better than the one 8mm clover-shaped Kuntscher nail.