A COMPUTATIONAL STUDY OF DIFFERENT ADDITIVE MANUFACTURING-BASED TOTAL ANKLE REPLACEMENT DEVICES USING THREE-DIMENSIONAL HUMAN LOWER EXTREMITY MODELS WITH VARIOUS ANKLE POSTURES

摘要

Total ankle replacement (TAR) surgery is one of the useful methods to treat ankle arthritis. Selective laser melting that is an additive manufacturing (AM) technique has made it possible to fabricate orthopedic implants. However, there are rare studies to analyze AM implants using finite element method. Thus, the purpose of this study was to investigate the effect of the various porous designs with three types of tibial shapes for five ankle postures using three-dimensional (3D) human lower extremity models. The variable-axis-mobile-bearing (VAMB) TAR models were developed in one solid TAR design and three porous TAR designs on the tibial and talar components. Additionally, three shape designs (curved, flat, and tilted) of the tibial component were also evaluated. Each TAR design was assembled on the human lower extremity model with standing, inversion, eversion, plantar flexion, and dorsiflexion ankle postures. The results showed that there was a minor effect among the solid and porous TAR designs on the implant stability, the bone stress, and the implant stress. However, those performances in the plantar flexion were significantly reduced compared to that in the other ankle postures. Although the porous TAR designs have a higher risk of implant failure and bone breakage, it may have better bone-implant bonding ability. This study could help engineers and surgeons to understand the design rationale and biomechanics of AM-based TAR devices.