Finite element modeling of the glenohumeral joint during external and internal rotation

A finite element modeling was performed in order to study the glenohumeral joint. A comparison study was conducted between the healthy humerus and an uncemented prosthetic humerus. We simulated the external and internal rotation of the glenohumeral joint in order to compare the deformation, strain and stress appeared in the prosthetic humerus with the healthy one. The results show that for the external rotation the solicitation typically appear in similar humeral positions but the mechanical solicitation for the healthy humerus have larger numerical values for the healthy humerus. For the internal rotation of the glenohumeral joint, the equivalent deformation and strain appear in similar humeral positions, while the maximum equivalent stress occurs in the distal prosthesis unlike in the distal epiphysis as it appears at the healthy shoulder. Due to the fact the implantation of the prosthesis makes the assembly more rigid, the numerical values for the internal rotation solicitation are larger for the un-prosthetic shoulder. This study is innovative due to the fact that it considers all muscle groups involved in external and internal rotation and obtains a realistic estimate of the mechanical solicitations appeared into the humerus. Possible fracture risk can be determined and prevented in case a prosthesis is implanted. It will be used to test different types of shoulder movements for both healthy and prosthetic one. It will be further used to test cemented prosthesis, and to determine the optimal cement type.