Finite element stress analysis of a hybrid fracture fixation plate

Metal plates are commonly used in the operative treatment of bone fractures (Figure 1).
Rigid metal plates stabilise the fracture site, maintain good contact between bone fragments. However,
treatment with rigid metal plates can cause localised bone atrophy due to stress shielding and
interference with blood circulation, and the weakened bone can refracture after plate removal.
A carbon fibre reinforced plate system that combines the torsional and bending rigidity of a metal
plate with the axial compliance of a polymer insert has been designed. A three-dimensional, quartersymmetric
finite element model was generated for a canine femur diaphysis plated with this
metal/polymer hybrid design. A model with a standard metal fixation plate was also generated for
comparison purpose. The stress state in the underlying bone was examined for several loading
conditions taken from published in vivo studies. The finite element model was used to study the
performance of biodegradable polymer inserts in the plate system. The flexible plate reduced stressshielding
effects at the fracture site when subjected to an axial load. The bending strength of the plate
was not compromised by the addition of the polymer inserts. Biodegradable inserts further enhanced
the performance of the new plate design, transferring less of the axial load to the plate as the inserts
broke down.

Citation:
Saidpour, Hossein (2006) ‘Finite element stress analysis of a hybrid fracture fixation plate’ Proceedings of Advances in Computing and Technology, (AC&T) The School of Computing and Technology 1st Annual Conference, University of East London, pp.173-183.