Slotted versus non-slotted locked intramedullary nailing for femoral shaft fractures.

Experimentally, two slotted nails, the Grosse-Kempf nail and the AO/ASIF universal femoral nail, were compared to the non-slotted Grosse-Kempf nail and control bone using a cadaver femoral osteotomy. The stiffnesses and strengths of the osteotomies fixed with slotted nails in 10-30 degrees torsion were 6-8% and the values of non-slotted nails 40% of control bone. The maximal moments were 14-18% and 48%, respectively. In the "clinical range" of torsion, the implant-bone construct never failed or was deformed. Clinically, 46 femoral shaft fractures were randomized to treatment with Gross-Kempf nails, 24 with slotted nails and 22 with non-slotted nails. Four complications in the slotted nail group and three in the non-slotted nail group were considered to be independent of the choice of nail and did not affect the end result. Three splinterings of the distal fragment, one resulting in a change of the osteosynthesis implant to a condylar plate, were considered to result from the high stiffness of the non-slotted nail. Osteosynthesis of femoral shaft fractures using slotted nails has not resulted in healing disturbances, which could be accounted for by the high torsional elasticity of the nail; there seems to be no indication for high-stiffness nails in femoral fractures.