BIOMECHANICAL STUDY OF 9 DIFFERENT TIBIA LOCKING NAILS

We compared different nail types within the Bone/Implant-Complex to lo ok for differences in stiffness for axial load, bending and torsion of the System. We simulated comminuted mid shaft fractures by a 2-cm def ect osteotomy in paired human cadaver tibiae. We fixed tibiae with one of nine different interlocking nails [AO Unreamed Tibial Nail 9 mm (U TN9), AO Unreamed Tibial Nail 8 mm (UTN8), Russell & Taylor Delta Tibi al Nail 9 mm (RTD), Russell & Taylor Reconstruction Tibial Nail ii 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 & Schell mann Tibial Nail 11 mm (K&S), and Borner & Mattheck Tibial Nail 11 mm (B-M)] according to the manufacturer's recommendations. In torque test ing the unslotted nails (UTN9, UTN8, RTD, RTR, B&W) showed significant ly higher stiffness compared to the slotted nails (G&K, AOU, K&S, B-M) . Compared to intact bone, both groups of nails were significantly les s stiff. In axial load testing large diameter nails interlocked by lar ge diameter interlocking bolts (G&K, K&S, B-M) showed significantly hi gher stiffness. For A-P bending no significant differences between imp lants were found, but isolated bones showed significantly higher A-P b ending stiffness. In varus-valgus bending large diameter nails (RTR, G &K, K&S, B-M) showed significantly higher bending stiffness compared t o low diameter (UTN8, B&W) implants.