A triangular support screw improves stability for lateral locking plates in proximal tibial fractures with metaphyseal comminution: a biomechanical analysis.

OBJECTIVE

This study evaluates a proximally angulated cortical screw forming a triangular construct in lateral locking plates of comminuted intraarticular tibial plateau fractures.

METHODS

Sixteen composite tibiae were used for the fracture model and a complete articular fracture of the proximal tibia (AO 41.C2) was performed. A compression force was applied to the medial tibial plateau with an alternating, stepwise loading: 250 N-10 N-300 N-10 N-350 N-10 N-400 N. The relative motion between the different fragments of each sample was measured using a contactless, 3-dimensional digital image correlation system.

RESULTS

Between the medial and lateral condyle, elastic as well as plastic shear was significantly lower using the triangular support screw (p < 0.05). In the metaphyseal region, elastic deformation remained identical, independent of the screw positioning. However, plastic deformation (varus collapse) was significantly reduced by 30-40% using a triangular support screw at higher compression forces (>300 N; p < 0.05).

CONCLUSION

Based on the results of this study, the use of a triangular support screw in metaphyseal comminuted tibial plateau fractures might enhance fracture stability. However, further studies are necessary to prove these biomechanical results in composite bone.