A finite element analysis of bone plates available for prophylactic internal fixation of the radial osteocutaneous donor site using the sheep tibia model.

a b s t r a c t Introduction: The strengthening effect of prophylactic internal fixation (PIF) with a bone plate at the radial osteocutaneous flap donor site has previously been demonstrated using the sheep tibia model of the human radius. This study investigated whether a finite element (FE) model could accurately represent this biomechanical model and whether stress or strain based failure criteria are most appropriate. Methods: An FE model of an osteotomised sheep tibia bone was strengthened using 4 types of plates with unilocking or bicortical screw fixation. Torsion and 4-point bending simulations were performed. The maximum von Mises stresses and strain failure criteria were studied. Results: The strengthening effects when applying stress failure criteria (factor 1.76-4.57 bending and 1.33-1.80 torsion) were comparable to the sheep biomechanical model (factor 1.73-2.43 bending and 1.54-2.63 torsion). The strongest construct was the straight 3.5 mm stainless steel unilocking plate. Applying strain criteria the strongest construct was the straight 3.5 mm stainless DCP plate with bicortical screw fixation. Conclusions: The FE model was validated by comparison with the sheep tibia model. The complex biome- chanics at the bone-screw interface require further investigation. This FE modelling technique may be applied to a model of the human radius and other sites.