Placing the tibial component of an ankle prosthesis: results of a CT-based simulation in healthy adults.

Purpose: To characterize the 3D geometry of the distal tibia resection area from healthy individuals using CT-based digital implantation for proper preoperative sizing of TAA tibia component placement.

Methods: Standardized CT images of healthy ankle joints serving as intra-individual references for treatment of contralateral injuries were identified. The tibial cross section dedicated to virtually host the tibial component was digitally prepared, and the size of the virtual contact surface was calculated. Finally, out of five prototypes the one fitting best in terms of size and alignment was identified.

Results: CT scans taken from 319 subjects were used for the virtual implantation procedure. Body height and size of the distal tibia contact area correlated (r = 0.49 and 0.42 in females and males, each p < 0.001). Prosthesis sizes 2 and 3 fit well for the vast majority of patients, while the smallest and largest sizes are rarely required.

Conclusions: Digital implantation of the tibial component should be considered a valuable tool for preoperative planning as well as for the development of new implant types.