Optimizing Total Ankle Arthroplasty Analysis: A Comprehensive Assessment of Alignment and Patient-Reported Outcome Measures via Weight-Bearing CT

Category: Ankle Arthritis; Ankle Introduction/Purpose: Osteoarthritis (OA) of the tibiotalar joint is associated with a high degree of morbidity, comparable to the final stages of renal and heart failure. The incidence of OA in the tibiotalar joint is as high as 47.7 per 100,000 inhabitants, most of whom will require surgical intervention to improve their quality of life. To date, there is scarce literature on the alignment in Total Ankle Arthroplasty (TAA) and its implications for patient-reported outcome measures (PROMs). Furthermore, no evidence has yet analyzed the association between alignment assessed with weight-bearing CT (WB-CT) and PROMs. Methods: A prospective cohort study was conducted, including all TAAs performed between 2015 and 2023, with a minimum follow-up of 12 months and a WB-CT taken within the first 12 months postoperatively. Revision TAAs, those lost to follow-up, and cases lacking WB-CT in the first 12 months were excluded. The anterior distal tibial angle (ADTA) and medial distal tibial angle (MDTA) were assessed with WB-CT, along with the internal rotational angle of the talar component. TAAs exhibiting an ADTA or MDTA with angles outside the range of normality were considered to have misaligned prostheses. The PROMs were assessed in the preoperative scenario and again at 2 months, 6 months, 1-year and 2-year post-surgery. The association between alignment and PROMs was evaluated using the Mann-Whitney test, while the association between the internal rotation of the talar component and PROMs was analyzed with the Spearman test. Statistical significance was set at p=0.05. Results: 74 TAAs were included. No statistically significant difference was found between correctly aligned and misaligned prostheses in the ADTA or MDTA and PROMs. However, the internal rotation angle of the talar component showed a statistically significant association with both the vitality component (p = 0.01, rho = -0.52) and the physical function component (p < 0.01, rho = 0.60) of the SF-36 score. Meanwhile, the VAS, AOFAS, FAAM, FAOS, and SMFA showed no statistical association. Conclusion: In our cohort of patients with TAA, coronal or sagittal misalignment, as assessed with WB-CT, shows no association with PROMs. It's worth mentioning that PROMs are subjective, multifactorial measures that should be interpreted with caution, and the importance of achieving correct alignment should not be minimized. Although internal rotation of the talar component is associated with better PROMs, to date, no cutoff value has been described, and further efforts should be made to elucidate the optimum internal rotation of the talar component.