Fixation plate positioning remains controversial in clavicle fracture reconstruction. Biomechanical studies favor a superior plate placement and clinical series report very low mechanical complications for anteroinferior plate placement. To clarify this apparent discrepancy, a biomechanical finite element analysis of the deformation mode, stress patterns, and peak stresses involved with superior and anteroinferior clavicle plate fixation was performed.
Finite element models of the superior and anteroinferior reconstructions were built and the results were compared with those of the intact clavicle when loaded in axial compression and cantilever bending.
Superior plate placement was less likely to fail in axial compression but the anteroinferior plate placement was less likely to fail in cantilever bending. For all placements and loading modes, the region near the fracture gap experienced the highest stresses and was consequently critical for the behavior of the whole construct. The anteroinferior placement led to a deformation mode similar to the intact clavicle in both loading configurations, whereas the deformation mode with the superior placement was non-physiological.
Anterorinferior plating is generally preferable, because it induces deformation modes similar to the intact clavicle and is less likely to fail during normal physiological loading (cantilever bending). Superior placement of the reconstruction plate may be recommended for a patient with a high risk of shoulder impacts (axial compression). Design improvements in the bridging area of the plate and special attention to obtain a good fixation around the fracture could reduce plate failures and provide a stiffer construct.