Finite element analysis of the strain distribution in the humeral head tubercles during abduction: comparison of young and osteoporotic bone

Aim The aim of this work was to design an accurate 3D digital model of the humerus and rotator cuff muscles. This model was then used to study strain distribution in humeral tubercles according to bone density. Materials and methods The geometry of bone and muscle structures was reproduced using SURFDRIVER(C) software, based on anatomical sections, CT scans and MRI images from the Visible Human Project image library. The contours were transferred to PATRAN(C) software to rebuild volumes and mesh them. Calculations of strains and their distribution were performed using NASTRAN(C) software. All the elements were considered to be isotropes. Results The study of the distribution of stress magnitude according to the type of bone modeled, shows that some stresses in cortical bone are greater than those in cancellous bone and are also greater in old bone, implying more deformation in old bone at constant force. This study also shows that stresses do not penetrate deeply into cancellous tissue. Conclusion Observing the simulation results led understanding of the pathology of certain fractures of the proximal end of the humerus. This study also helped explain why certain types of osteosynthesis fail due to tubercles reconstruction failures.