Stability of femoral neck osteosynthesis. Comparison of fixation methods in cadavers.

Fixation of vertical femoral neck osteotomies in 50 cadavers was performed with either von Bahr screws or a sliding hip compression screw. One specimen from each pair of femora was used for the osteotomy, the other serving as an intact control. At 0.05 r of torsion the load-deformation test showed that three von Bahr screws provided the strongest fixation, and this was confirmed by the the ultimate torsional moment test. Regardless of positioning, even two von Bahr screws were stronger than the sliding compression screw with or without an additional lag screw. The results indicate that the best torsional stability in femoral neck fractures can be obtained with three 5.5-mm screws.