After some relatively poor results in the 1980s, there was a “reboot” with total ankle arthroplasty (TAA) in the late 1990s to improve outcomes so that TAA would provide a reliable treatment for patients with end-stage ankle arthritis. Advances in the understanding of the biomechanical requirements for ankle prostheses and which patients might benefit from them the most—plus the realization that TAA is a technically demanding surgical procedure that requires advanced education—have vastly improved the outcomes of these procedures. In fact, TAA has become reliable enough that we can now begin to tease out the patient variables that seem to affect outcomes.
In the February 6, 2019 issue of The Journal, Cunningham et al. use an extensive clinical TAA registry to identify patient characteristics that impact TAA outcomes. The good news is that, 30-plus years after the inauspicious outcomes of first-generation TAA, overall pain and function significantly improved among the patients in this study. However, current smoking was associated with poorer patient outcomes at the 5-year follow-up, as it seems to be with the vast majority of orthopaedic procedures. Also, at a mean 1- to 2-year follow-up, a previous surgical procedure on the ankle was associated with significantly smaller improvements in at least 1 patient-reported outcome. This makes sense because prior surgery leads to scarring and its attendant risk of infection and increased difficulty with exposure and the ideal placement of TAA components. Cunningham et al. also identified depression as being associated with worse TAA outcomes at all follow-up points, adding to our already ample body of evidence that patient psychological factors play a major role in orthopaedic surgical results.
Interestingly, these authors found that patients undergoing staged bilateral ankle arthroplasty did not do as well as those undergoing simultaneous bilateral TAAs. And somewhat surprisingly, the authors found obesity to be associated with better outcomes at the 5-year follow-up. This may be related to increased bone density and greater soft-tissue coverage, but this finding is still seemingly counterintuitive based on everything else we know about the negative associations between obesity and outcomes of other joint replacements.
As more surgeons and orthopaedic centers make use of TAA, it will be important for us to follow the lead of the total knee and total hip communities in providing large datasets to further clarify which factors—patient-related and surgical—lead to the best and worst patient outcomes. This study by Cunningham et al. provides a starting point upon which other research will hopefully build.
Marc Swiontkowski, MD