Biomechanical Evaluation of a Carbon Fibre Epoxy Composite Plate in an Injured and Healed Femur Using Infrared Thermography and Finite Element Analysis

Femur fractures are caused by high energy trauma or by musculoskeletal impairments, such as osteoporosis. The presence of total hip replacement (THR) superior to a femoral mid-shaft fracture greatly complicates fixation and treatment. The most conventional fracture fixation method is internal fixation by metal plate and screws. However, metal being stiffer than bone, causes stress shielding and bone resorption. The goal of this study was to evaluate the performance of a less stiff carbon fibre epoxy plate as fracture fixation in an injured and healed femur. IR thermography validated by finite element analysis (FEA) was used to investigate the stress patterns of an injured and healed femur under an average cyclic loading of 800 N at an adduction angle of 7 degrees to simulate the single-legged stance phase of walking. The average stiffness of an injured femur with carbon/epoxy plate was 532.1 N/mm (static) and 625.3 N/mm (dynamic) respectively, that increased to 597.6 N/mm (static) and 697.9 N/mm (dynamic) for the metal plate. For the healed femur, the average stiffness increased from 1660.3 N/mm (static) and 2010.0 N/mm (dynamic) for the carbon/epoxy plate to 1704.4 N/mm (static) and 2070.4 N/mm (dynamic) for the metal plate. IR stress maps for carbon/epoxy and metal plate (injured femur) showed an overall difference of 29.2% for the anterior and posterior sides. This is the first study to assess experimentally and computationally the biomechanical behavior of injured and healed synthetic femur with two different plates construct.