Influence of keel shape of Salto TalarisTM total ankle prosthesis on the biomechanical performance on the bone-implant interface: A finite-element analysis.

Purpose: This study aimed to evaluate the effects of changing the keel shape of the tibial component of a keel-type total ankle prosthesis on its biomechanical behavior and to identify possible directions for further prosthesis selection and improvement.

Methods: Finite elements analysis was applied to analysis the influence on biomechanical effects of the shape of tibia implant keel in total ankle prostheses. CT of a male volunteer was used to develop tibia models with different prosthesis designs based on the tibia implant of Salto TalarisTM ankle prosthesis. Biomechanical properties including stress, micromotion and strain were evaluated.

Results: The peak stress and micromotion of the design with short keel and vertical holes were 85.3 MPa and 62.87 μm, respectively, which were 36.7 % and 84.4 % lower than the original design. The proportion of units with satisfactory osseointegration in the periprosthetic bone tissue reached 20.09 % in this design and was 19.1 % more than the original design.

Conclusion: Reducing the length of keel of the tibia prosthesis to the underlying support structure and reorienting the lateral holes to the vertical direction could improve the stability of the prosthesis by reducing possible sterile loosening through the improvement of the mechanical effects mentioned above. But this may require further experiments for verification.