Short-Term Clinical and Radiological Results of the Infinity Ankle Arthroplasty: A Prospective Study

BackgroundAnkle joint arthroplasty is increasingly used in primary or secondary end-stage osteoarthritis. Initial reports on the fourth-generation Infinity total ankle system showed a high failure rate due to component loosening. The objective of this study was to assess complications, reoperations, patient reported outcome measures (PROMs) and radiographic findings after 1 year.MethodsData were prospectively collected in a local ankle surgery registry between January 2018 and March 2023. All cases of primary ankle arthroplasty using the Infinity system with a 1-year follow-up were included (106 ankles in 101 patients). Complications, revisions, and reoperations were described after 1 and 2 years, and the 1-year postoperative PROMs (AOFAS Ankle-Hindfoot score, MOxFQ, EQ5D, and EQ5D-VAS) were compared to preoperative values. One-year postoperative radiographs were assessed for signs of loosening.ResultsThe mean age was 65 years (SD 11.7), 55% were female, and the mean BMI was 27 kg/m² (SD 4.2). Main indications for arthroplasty were chronic instability (27%), inflammatory joint disease (25%) and posttraumatic osteoarthritis (22%). After 1 year, there were 6 (5.5%) reoperations, of which 3 (2.7%) were prosthesis revisions, and 3 (2.7%) were outside the primary operative site. One (0.9%) reoperation was due to aseptic loosening of the tibia component. After 2 years, there was 1 additional reoperation with a tibial osteotomy and exchange of polyethylene insert. All PROMs improved significantly between the preoperative and the 1-year follow-up assessment, with mean change in AOFAS 35.9 (P < .01), MOxFQ 46.9 (P < .01), EQ5D 0.36 (P < .01), and EQ5D-VAS 13.2 (P < .01). There were findings of radiolucent lines and/or cysts on 1-year postoperative radiographs in 9 cases (9%).ConclusionsWe found an acceptable rate of early aseptic loosening. All PROMs demonstrated a significant improvement from preoperative to 1-year postoperative assessment.Level of Evidence:Prospective cohort study, level II.