High Rate of Osteolytic Lesions in Medium-Term Followup after the AES Total Ankle Replacement

BACKGROUND: Some previous studies have shown a high percentage of early-onset and rapidly progressing osteolysis associated with total ankle arthroplasty (TAA) by the Ankle Evolutive System (AES). The purpose of our study was to analyze medium-term results at our institution. MATERIALS AND METHODS: Altogether 38 TAAs using AES prostheses were carried out between 2003 and 2007. Diagnoses were rheumatoid arthritis (71%), post-traumatic and idiopathic osteoarthritis (29%). The mean age was 54 years, followup 28 months. Tibial and talar components had hydroxyapatite coating on metal (Co-Cr) components (HA-coated). Since 2005 the design was changed and components were porous coated with titanium and hydroxyapatite (dual-coated). RESULTS: Two-year survival was 79% (95% CI: 56 to 98). At followup 34 (89%) primary tibial and talar components were preserved. In 19 (50%) TAAs osteolysis (more than or equal to 2 mm) occurred in the periprosthetic bone area and in nine (24%) comprised large "cyst-like osteolysis''. In HA-coated prostheses radiolucent lines (less than or equal to 2 mm) or osteolysis (more than or equal to 2 mm) were detected in 11 (100%) cases and in dual-coated prostheses in 19 (74%) (p = 0.08). On the other hand there was more large "cyst-like osteolysis'' around the dual-coated prosthesis and lesions were larger (p = 0.017). In rheumatoid arthritis osteolysis was detected in 14 (52%) and large "cyst-like osteolysis'' in seven (26%) prostheses and in the group of traumatic and idiopathic osteoarthritis in six (55%) and two (18%), respectively. CONCLUSION: This study showed a high frequency of osteolysis in medium-term followup after the AES ankle replacement. The outcome was not sufficiently beneficial and we have discontinued use of this prosthesis.