TAR (Total Ankle Replacement) is the best method to treat ankle arthritis. However,
the clinical problems are still being an enigma. Many aspects of TAR device investigated in various studies, including the structures, materials, and manufacturing techniques to improve the biomechanical performance of the TAR. The AM (additive manufacturing) techniques have been investigated on the fabrication of implants. However, this technique is still rarely studied for ankle joint replacement. Therefore, the purpose of this study was to investigate the effect of various surface designs with three types of tibial shape, gap interface between tibial with insert component, and number-position fixation rods of the tibial component for five conditions of ankle posture using the three-dimensional finite element of human lower extremity bone models.
The VAMB (Variable Axis Mobile Bearing) with some parameters that are consisting of various surface designs, tibial component shapes, various method to create the gap interfaces between tibial-insert component. Also, the number-position of fixation rods was developed using SolidWorks software. Each model was assembled on the three dimensional human lower extremity bone model withstanding, inversion, eversion, plantar flexion, and dorsiflexion postures. Thus, the finite element models were developed using ANSYS Workbench software. In the post-processing, the stability, the stress of TAR models, and the bone stress were analyzed to investigate the biomechanical performance of the TAR design.
The results show that there is a minor effect of different TAR designs on the implant stability, bone stress, and implant stress. However, the stability, bone stress, and implant stress value from each model on the plantar flexion posture is significantly decreased compared to other ankle postures. The design used solid surface has lower stress than porous designs for all ankle postures. Moreover, the way of reducing the volume on the insert method to create gap interfaces showed that it was able to reduce the bone and implant stress. The reduction of number fixation rods reduced the stress of the TAR component and the bone, but the position of the rods played an essential role on the stability, the implant stress, and bone stress. The three types of tibial component shapes, although the curved model had the lowest of maximum stress, were not significantly different result value.
Various TAR designs that considered several parameters on the five ankle postures can be successfully evaluated. The solid surface with 8-fixation rods could reduce the implant and bone stress, but the medium porous size with 6H-fixation rod design may have a better ability of bone-implant bonding and could reduce the bone loss. This study also can provide some information about TAR designs with AM based on the orthopedic surgeon about the biomechanical performances of the TAR device.

TTAR (Total Ankle Replacement) is the best method to treat ankle arthritis. However,
the clinical problems are still being an enigma. Many aspects of TAR device investigated in various studies, including the structures, materials, and manufacturing techniques to improve the biomechanical performance of the TAR. The AM (additive manufacturing) techniques have been investigated on the fabrication of implants. However, this technique is still rarely studied for ankle joint replacement. Therefore, the purpose of this study was to investigate the effect of various surface designs with three types of tibial shape, gap interface between tibial with insert component, and number-position fixation rods of the tibial component for five conditions of ankle posture using the three-dimensional finite element of human lower extremity bone models.
The VAMB (Variable Axis Mobile Bearing) with some parameters that are consisting of various surface designs, tibial component shapes, various method to create the gap interfaces between tibial-insert component. Also, the number-position of fixation rods was developed using SolidWorks software. Each model was assembled on the three dimensional human lower extremity bone model withstanding, inversion, eversion, plantar flexion, and dorsiflexion postures. Thus, the finite element models were developed using ANSYS Workbench software. In the post-processing, the stability, the stress of TAR models, and the bone stress were analyzed to investigate the biomechanical performance of the TAR design.
The results show that there is a minor effect of different TAR designs on the implant stability, bone stress, and implant stress. However, the stability, bone stress, and implant stress value from each model on the plantar flexion posture is significantly decreased compared to other ankle postures. The design used solid surface has lower stress than porous designs for all ankle postures. Moreover, the way of reducing the volume on the insert method to create gap interfaces showed that it was able to reduce the bone and implant stress. The reduction of number fixation rods reduced the stress of the TAR component and the bone, but the position of the rods played an essential role on the stability, the implant stress, and bone stress. The three types of tibial component shapes, although the curved model had the lowest of maximum stress, were not significantly different result value.
Various TAR designs that considered several parameters on the five ankle postures can be successfully evaluated. The solid surface with 8-fixation rods could reduce the implant and bone stress, but the medium porous size with 6H-fixation rod design may have a better ability of bone-implant bonding and could reduce the bone loss. This study also can provide some information about TAR designs with AM based on the orthopedic surgeon about the biomechanical performances of the TAR device.

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