Background: The role of ankle arthroplasty in the treatment of ankle arthritis is controversial. Ankle fusion is commonly performed, but there is ongoing concern about functional limitations and arthritis in the adjacent subtalar joint following ankle arthrodesis. The use of ankle arthroplasty as an alternative to ankle fusion is expanding, but reported results have been limited to those in case series. The purpose of this study was to compare the reoperation rates following ankle arthrodesis and ankle replacement on the basis of observational, population-based data from all inpatient admissions in California over a ten-year period. Our hypothesis was that patients treated with ankle replacement would have a lower risk of undergoing subtalar fusion but a higher overall risk of undergoing major revision surgery.
Methods: We used California's hospital discharge database to identify patients who had undergone ankle replacement or ankle arthrodesis as inpatients in the years 1995 through 2004. Short-term outcomes, including rates of major revision surgery, pulmonary embolism, amputation, and infection, were examined. Long-term outcomes that were analyzed included the rates of major revision surgery and subtalar joint fusion. Logistic and proportional hazard regression models were used to estimate the impact of the choice of ankle replacement or ankle fusion on the rates of adverse outcomes, with adjustment for patient factors including age and comorbidity.
Results: A total of 4705 ankle fusions and 480 ankle replacements were performed during the ten-year study period. Patients who had undergone ankle replacement had an increased risk of device-related infection and of having a major revision procedure. The rates of major revision surgery after ankle replacement were 9% at one year and 23% at five years compared with 5% and 11% following ankle arthrodesis. Patients treated with ankle arthrodesis had a higher rate of subtalar fusion at five years postoperatively (2.8%) than did those treated with ankle replacement (0.7%). Regression analysis confirmed a significant increase in the risk of major revision surgery (hazard ratio, 1.93 [95% confidence interval, 1.50 to 2.49]; p < 0.001) but a decreased risk of subtalar fusion (hazard ratio, 0.28 [95% confidence interval, 0.09 to 0.87]; p = 0.03) in patients treated with ankle replacement compared with those treated with ankle fusion.
Conclusions: This study confirms that, compared with ankle fusion, ankle replacement is associated with a higher risk of complications but also potential advantages in terms of a decreased risk of the patient requiring subtalar joint fusion. Additional controlled trials are needed to clarify the appropriate indications for ankle arthrodesis and ankle replacement.