Locking versus nonlocking plates in mandibular reconstruction with fibular graft--a biomechanical ex vivo study

The main goal of the present study was to compare the biomechanical stability of locking plates and conventional miniplate combinations in human mandibles reconstructed with fibular grafts.

A specially developed and well-proven testing device reproduced the in vivo loading conditions on the mandible. Cadaveric human mandibles (n = 12) reconstructed with harvested human fibular bone grafts were divided into two groups, and different osteosynthesis systems were applied using two lines of plates per osteotomy. On the test apparatus, the specimens were stressed to failure, and interfragmentary movement was monitored and quantified with a contact-free optical measurement system.

The relevant interfragmentary movement results from a Euclidean summary calculation which considered all three spatial angles around the axes. Using values up to a maximum load of 300 N, the conventional six-hole miniplates (profile 1.0) had an average value of 7.45° ± 1.46°, and the locking six-hole plates (profile 1.3) had an average value of 12.16° ± 2.37° for rotational interfragmentary movement. The miniplate system exhibited a significantly superior performance in fixation compared to the fixed-angle system (p < 0.05).

According to these biomechanical experiments, both osteosynthesis devices provided sufficient stabilization at loads of up to 300 N. The six-hole miniplate system provided better stabilization of the osteotomy gap for mandibles reconstructed with fibular grafts.

The osteosynthesis system is essential for primary stability and the avoidance of pseudarthrosis formation. This study demonstrates that the miniplates provide sufficient stabilization and offers a method to improve fixation in reconstructed mandibles.