Abstract
Background
Total ankle arthroplasty is an accepted alternative to arthrodesis of the ankle. However, complication and failure rates remain high compared to knee and hip arthroplasty. Long-term results of the Scandinavian Total Ankle Replacement (STAR) are limited, with variable complication and failure rates observed. This prospective study presents the long-term survivorship and the postoperative complications of the STAR prosthesis. Additionally, clinical outcomes and radiographic appearance were evaluated.
Methods
Between May 1999 and June 2008, 134 primary total ankle arthroplasties were performed using the STAR prosthesis in 124 patients. The survivorship, postoperative complications and reoperations were recorded, with a minimum follow-up period of 7.5 years. Clinical results were assessed using the Foot Function Index (FFI) and the Kofoed score. The presence of component migration, cysts and radiolucency surrounding the prosthesis components, heterotopic ossifications and progression of osteoarthritis in adjacent joints were determined.
Results
The cumulative survival was 78% after a 10-year follow-up period (Figure 1). An ankle arthrodesis was performed in the 20 ankles that failed. Fourteen polyethylene insert fractures occurred. Other complications occurred in 29 ankles, requiring secondary procedures in 21 ankles. Nevertheless, the postoperative clinical results improved significantly. Osteolytic cysts were observed in 59 ankles and the surface area of these cysts increased during follow-up, without any association with the prosthesis alignment or clinical outcome. Heterotopic ossifications at the medial malleolus were present in 58 cases and at the posterior tibia in 73 cases, with no effect on clinical outcome. Osteoarthritis of the subtalar joint and talonavicular joint developed in 9 and 11 cases, respectively.
Conclusion
The long-term clinical outcomes for the STAR were found to be satisfactory. These results are consistent with previous studies; however, the survival and complication rates are still disappointing compared to the results obtained in knee and hip arthroplasty. Higher rates of successful outcomes following ankle arthroplasty are required, and these results highlight the need for further research to clarify the origin and significance of the reported complications.
Figure 1. Kaplan-Meier survivorship analysis with revision or removal of the tibia and/or the talus component for any reason as the endpoint, showing 78% (95% confidence interval 0.63–0.88) survival at 10.28 years follow-up
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