Biomechanical study of nine different tibia locking nails.

We compared different nail types within the Bone/Implant-Complex to look for differences in stiffness for axial load, bending and torsion of the System. We simulated comminuted mid shaft fractures by a 2-cm defect osteotomy in paired human cadaver tibiae. We fixed tibiae with one of nine different interlocking nails [AO Unreamed Tibial Nail 9 mm (UTN9), AO Unreamed Tibial Nail 8 mm (UTN8), Russell & Taylor Delta Tibial Nail 9 mm (RTD), Russell & Taylor Reconstruction Tibial Nail 11 mm (RTR), Brooker & Wills Tibial Nail 11 mm (B&W), Grosse & Kempf Tibial Nail 11 mm (G&K), AO Universal Tibial Nail 11 mm (AOU), Klemm & Schellmann Tibial Nail 11 mm (K&S), and Börner & Mattheck Tibial Nail 11 mm (B-M)] according to the manufacturer's recommendations. In torque testing the unslotted nails (UTN9, UTN8, RTD, RTR, B&W) showed significantly higher stiffness compared to the slotted nails (G&K, AOU, K&S, B-M). Compared to intact bone, both groups of nails were significantly less stiff. In axial load testing large diameter nails interlocked by large diameter interlocking bolts (G&K, K&S, B-M) showed significantly higher stiffness. For A-P bending no significant differences between implants were found, but isolated bones showed significantly higher A-P bending stiffness. In varus-valgus bending large diameter nails (RTR, G&K, K&S, B-M) showed significantly higher bending stiffness compared to low diameter (UTN8, B&W) implants.