Biomechanics of porous lattice-structured tibial implant design for TAR: Role of pore morphology, porosity and implant design.

BACKGROUND

Implant-bone micromotion and stress shielding play a crucial role in the long-term survival of tibial implant for Total Ankle Replacement (TAR). Both these biomechanical considerations are majorly relying on the design of implant and fixation features. The biomechanics of different porous structure features and porosity on biomechanical performance of tibial implant design remain unexplored. The objective is to investigate the role of pore morphology, porosity, and tibial design on the biomechanics of porous lattice-structured tibial implant design for TAR.

METHODS

This is achieved by simulating the biomechanical performance using three-dimensional Finite Element (FE) models of intact and implanted tibia. A total of 59 realistic FE models were developed: one intact tibia, two implanted tibiae with solid implants and 56 models featuring lattice tibial implants.

RESULTS

Results revealed that by incorporating a diamond lattice structure with 70% porosity on the proximal surface of the BOX tibial implant, stress shielding can be dealt with the appropriate initial fixation for promoting bone ingrowth. The results imply that tibia bone stresses and mean micromotion increase as porosity increases from 50% to 80%. BOX design offers reduced stress shielding, indicated by higher tibia bone stress distribution compared to the Infinity.

CONCLUSION

The findings emphasise the need for careful porous feature selection for the design of lattice tibial implant for TAR.