Fabrication and optimisation of Ti-6Al-4V lattice-structured total shoulder implants using laser additives manufacturing

In the current work it was aimed to study one of the most important challenges of orthopaedic implantation known as stress shielding. This problem arises from the elastic modulus mismatch between the implant and the surrounding tissue and can result in bone resorption and implant loosening. This objective was addressed by designing and optimising of a cellular-based lattice structure implant to control the stiffness of a humeral implant stem used in shoulder implant ap-plications. This study used a lattice optimisation tool to create different cellular designs, which were further analysed using finite element analysis (FEA). A laser powder bed fusion technique was used to fabricate Ti-6Al-4V test samples, and the obtained material properties were fed to the FEA model. The optimised cellular design was further fabricated using powder bed fusion, and a compression test was carried out to validate the FEA model. The yield strength, elastic modulus, and surface area to volume ratio of an optimised lattice structure, with a strut diameter of 1 mm, length of 5 mm, and 100 % percentage lattice in the design space of the implant model were found to be 200 MPa, 5 GPa, and 3.71 mm-1, respectively. The obtained properties indicates that the pro-posed cellular structure can be effectively applied for the operations of total shoulder replacement. Ultimately, this approach should lead to the improvement of the patient mobility as well as re-ducing the need for revision surgery due to implant loosening.