A BIOMECHANICAL STUDY: EFFECTIVENESS OF A TRABECULAR METAL AUGMENTED CONSTRUCT IN LATERAL TIBIAL PLATEAU DEPRESSED FRACTURES (AO TYPE B2.2)

Abstract

We compared internal fixation augmented with a trabecular metal implant to internal fixation augmented with morcellized bone grafting for depressed lateral tibial plateau fractures. Six cadaveric tibia pairs were prepared and tested on a MTS machine for both cyclic loading and static load to failure. Results showed greater resistance in cyclic loading and load to failure in the trabecular metal group. We found half the loss of reduction of the tibial articular surface compared after cyclic loading over 10 000 cycles. These surprising results show the biomechanical superiority of our trabecular metal construct over the current standard of care.

Restoration and maintenance of the plateau surface are the key points in the treatment of tibial plateau fractures. Any deformity of the articular surface jeopardises the future of the knee by causing osteoarthritis and axis deviation. The purpose of this study is to develop a more solid way to fix the Shatzker III fracture and to test a trabecular metal implant in the trauma setting for the first time.

Six matched pairs of fresh frozen human cadaveric tibias were fractured and randomly assigned to be treated with either the standard of care (two 4,5mm cortical raft screws augmented with morcellized bone graft) or the new method (the same screws supporting a 2 cm diameter trabecular metal disc placed under the comminuted articular surface). The specimens were tested in cyclic loading and put at load to failure.

The trabecular metal construct showed 40% less caudad displacement of the articular surface (1,43 mm vs 0,81 mm) in cyclic loading (p< 0.05). Its mechanical failure occurred at a mean of 3275 N compared to 2650 N for the standard of care construct (p< 0,05).

The current study shows the biomechanical superiority of our trabecular metal construct compared to the current standard of treatment with regards to both its resistance to caudad displacement of the articular surface in cyclic loading and its strength at load to failure. Trabecular metal is a good metaphyseal void filler in the studied fracture.