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
The relationship between orthopaedic foot and ankle surgeons and podiatric surgeons has been checkered. Many have advocated that the orthopaedic community should isolate itself from interaction with the podiatric community. Conversely, a smaller group of orthopaedic foot and ankle surgeons have recommended sharing CME endeavors with podiatric surgeons, and combining clinical services with them. As long as individual states continue to legislate surgeon scope-of-practice matters (38 states currently allow podiatric surgeons to perform ankle surgery), it seems to me that shared learning, combined clinical services, and collaborative research make the most sense for advancing foot and ankle care for as many patients as possible. We should all be willing to work with our surgical colleagues to improve everyone’s decision making and skill.
In the January 16, 2019 issue of The Journal, Chan et al. probe an administrative database to evaluate several outcomes after total ankle arthroplasty (TAA) and ankle arthrodesis performed by both types of surgeon. Probably because many podiatrists self-limit their practices to forefoot surgery, podiatric surgeons provided the treatment for only 18% of the patients in both ankle-surgery groups. When podiatrists were the primary surgeon, the authors found increased lengths of stay for both procedures and increased hospital costs for arthrodesis patients. The authors did not investigate the reasons for these increases, but they should be investigated in the future. Chan et al. did find that, in general, podiatric surgeons operated on sicker patients and tended to work in smaller, non-teaching hospitals.
The authors also found an increasing percentage of these procedures being performed by podiatrists over the period from 2011 to 2016. This is likely related to multiple factors, including variable availability of orthopaedic foot and ankle surgeons relative to podiatric surgeons in many communities, and an increased number of podiatry training programs that specialize in hindfoot surgery.
It seems to me that data like these from Chan et al. should be shared with both communities to foster discussions regarding how to optimize length of stay, costs, and patient outcomes across the board. The goal should always be to raise every surgeon’s level of care for the benefit of all patients.
Marc Swiontkowski, MD
Among the many variables discussed when patients and surgeons make a decision between ankle arthrodesis (fusion) and total ankle replacement (TAA) for end-stage ankle arthritis, in-hospital complication rate is an often-overlooked point of comparison, partly due to a dearth of good data.
In the September 6, 2017 edition of The Journal of Bone & Joint Surgery, Odum et al. report findings from a matched cohort study that compared these two ankle procedures in terms of minor and major perioperative complications. To make more of an apples-to-apples comparison, the authors statistically matched 1,574 patients who underwent a TAA with an equal number of those who underwent fusion.
A major in-hospital complication (such as a pulmonary embolism or mechanical hardware problem) occurred in 8.5% of fusion patients and in 5.3% of TAA patients. After adjusting for case mix, Odum et al. found that ankle arthrodesis was 1.8 times more likely than TAA to be followed by a major complication. Regarding minor in-hospital complications (such as venous thrombosis or hematoma/seroma), the authors found a 29% lower risk of complications among arthrodesis patients compared to TAA patients, although that difference was not statistically significant (p = 0.14). Regardless of surgical procedure, patient age ≤67 years and the presence of multiple comorbidities were independently associated with a higher risk of a major complication.
A possible explanation for the lower in-hospital major-complication rate in TAA patients, say the authors, is that “TAA is more likely to be performed in younger, healthier patients with better bone quality and smaller deformities.”
We have entered an era where total ankle arthroplasty (TAA) is accepted as a rational approach for patients with degenerative arthritis of the ankle. TAA results have been shown to be an improvement over arthrodesis in some recent comparative trials.
That was not always the case, however. In the 1980s, the orthopaedic community attacked ankle joint replacement with gusto, and numerous prosthetic designs were introduced with great enthusiasm based on short-term cohort studies. Unfortunately, the concept of TAA was all but buried as disappointing longer-term results with those older prosthetic designs appeared in the scientific literature. It took a full decade for new designs to appear and be subjected to longer-term follow-up studies before surgeons could gain ready access to more reliable instrumentation and prostheses. The producers of these implants behaved responsibly in this regard, facilitated by an FDA approval process that had increased in rigor.
In the December 21, 2016 issue of The Journal, Hofmann et al. publish their medium-term results with one prosthetic design that was FDA-approved in 2006. Implant survival among 81 consecutive TAAs was 97.5% at a mean follow-up of 5.2 years. There were only 4 cases of aseptic loosening and no deep infections in the cohort. Total range of motion increased from 35.5° preoperatively to 39.9° postoperatively.
The fact that a high percentage (44%) of ankles underwent a concomitant procedure at the time of TAA attests to the need for careful preoperative planning for alignment of the ankle joint and the need for thorough assessment of the hindfoot. The fact that a substantial percentage (21%) of ankles underwent another procedure after the TAA attests to the need for thoughtful benefit-risk conversations with patients prior to TAA.
I think the TAA concept and procedure are here to stay, but we still have much work to do in fine-tuning prosthetic designs and instrumentation and enhancing surgeon education for more reliable outcomes.
Marc Swiontkowski, MD