Currently, the number of total ankle prostheses performed is increasingly higher due to significant improvements in the new designs available. The literature describes that this procedure improves patients related outcome measures compared to their preoperative baseline state. A minimum 2 year follow-up is required for outcome publications. To date, there are no long-term studies analyzing how PROMs behave over time and when the outcomes stabilize. This is a retrospective cohort study of all total ankle prostheses implanted at a single tertiary center. Primary total ankle prostheses performed between 2003 and 2023 were analyzed. The scores for the physical component of the SF36 (PC SF36), the mental component of the SF36, the AAS, and the AOS were analyzed at the time of enrollment, at 6 months, and annually, up to 15 years postoperatively if available. Scores were compared over time using the Friedman test. Subsequently, if any statistically significant differences were observed, the differences between each period were analyzed using the Wilcoxon test. Finally, the P values were adjusted according to the Bonferroni correction. A total of 447 total ankle replacements were included in the study, with a mean follow-up of 10,85 years 1,73 – 21,75. No statistically significant differences were found in the AAS scores and the mental component of the SF36, while the AOS scores and the PC SF36 did show statistically significant differences (both P After comparing the different periods and adjusting these comparisons according to the Bonferroni correction, the AOS score showed improvement in all follow-up years compared to the patient's preoperative state. The score improves up to 2 years with minimal change between 1 and 2 years. After 15 years a deterioration in the score is observed. The PC SF36 score improved in all follow-up years compared to the preoperative score, up to 13 years; afterwards, there were no differences. The PC SF36 score improved mostly up to 1 year postoperatively and then remained stable over time. Revisions continued to occur out to 15 years. The AOS and PC SF36 scores improved up to 2 years, with minimal changes in the second year, and 1 year postoperatively, respectively. Afterwards, the PROMs showed minimal variation until 15 years for the AOS and 13 years for the PC SF36, when both scores began to decline. This study shows that follow up for studies can be 1 year, and it could also indicate that the patient outcomes are already determined after one year. However, to understand revision rates long term follow up is required.
Koolen et al. (Wed,) studied this question.