Biomechanical comparison of intramedullar versus extramedullar stabilization of intra-articular tibial plateau fractures.

BACKGROUND: Fractures of the proximal tibia occur very often and are a great challenge for trauma surgeons to stabilize. Although locked nails were developed to stabilize these fractures, this technique has not been sufficiently investigated. The purpose of this study was to biomechanically assess the stability of locked intramedullary nailing compared to locked plating.

METHODS: 16 fresh frozen human cadaveric tibiae were osteotomized in the meta-diaphyseal intersection with an osteotomy gap of 10 mm and a single osteotomy through the medial epicondyle to simulate a 41-C.2 fracture. Stabilization was performed with an angle stable locked Targon-TX nail (n = 8) and two additional canulated screws. The other testing group (n = 8) was treated with two canulated screws and a five-hole LCP-PLT. The bones were tested in a cyclic testing protocol with increasing loads under compression and a load sharing of 60 % through the medial tibial plateau and 40 % to the lateral side. Stiffness and fracture gap movement were measured and failure mode was assessed.

RESULTS: No significant differences were found between the two implants regarding load until failure. The stiffness of the intramedullary nailing group (927 N/mm) was statistically significantly higher than the stiffness of the plating group (564 N/mm). No differences were found for fracture gap movement in the z-axis. However, differences were found for dislocation of the proximal-lateral and proximal-medial fragments, with absolute values of 0.099 mm in the plate group and 0.66 mm in the nailing group at 800 N. Prior to failure, fracture gap movement was 0.22 mm for the plating group and 1.66 mm for the nailing group, a difference that was also statistically significantly different. The nailing group failed by screw cut-out while the plating group failed by screw breakage.

CONCLUSION: Nailing of proximal tibia fractures leads to a stiffer implant-bone construct than plating. Since no adverse effects were found after nailing it seems to be a good alternative to plating for intra-articular proximal tibia fractures, especially in patients with soft tissue problems.