Fatigue test evaluation of a customised humeral component for an instrumented total elbow prosthesis and strain validation study

The survival rate of total elbow arthroplasty (TEA) is negatively impacted by the lack of available data on elbow biomechanics. This study developed a modified humeral component for TEA that is purposed to be instrumented to generate real-time 6 degrees of freedom (d.o.f) force and moment data during activities of daily living (ADL). The objectives are twofold: (1) to assess the safety of the modified humeral component under peak anticipated loads in fatigue, and (2) verify the strains measured under physiological loads with strains modelled using finite element analysis (FEA). Four modified titanium alloy humeral components were welded, and fatigue tested at 5 Hz for 5 million cycles under a compressive load of 700 N corresponding to moderate ADL. The strains were measured using triaxial 350 Ω rectangular rosette (45°) strain gauges bonded to three specific locations on the humeral component confirmed through an FE study. The four welded humeral components successfully withstood fatigue conditions and did not deform. The measured and modelled principal strains were confirmed to be highest at the external wall of the lateral cavity, with a percentage difference of <10 %.