AKILE™ total ankle arthroplasty: Clinical and CT scan analysis of periprosthetic cysts

Introduction: Despite good clinical results following total ankle replacement (TAR), the development of large periprosthetic cysts ( > 400 mm(2)) in the medium-term is a source of concern. Objective: The primary objective of this study was to detect any large periprosthetic cysts in a cohort of AKILE (TM) patients using radiographs and CT scans, and then to compare these findings to published ones. Material and methods: A total of 127 TAR procedures were performed between June 1995 and January 2012. We retrospectively reviewed 68 cases with the newest AKILE (TM) implant design that had a minimum follow-up of 36 months. The average follow-up was 81 +/- 33 months; eight patients were lost to follow-up. The outcomes consisted of analyzing radiographs (A/P and lateral weight bearing views. Meary view and lateral views of flexion/extension) and helical CT scans, performing clinical evaluations (range of motion, AOFAS score, Foot Function Index, pain levels) and determining the survivorship of TAR implants. Results: TAR survival at 5 years was 79% for in situ implants and 62% for revision-free implants. The AOFAS score improved from 33.7 +/- 14.7 to 77.1 +/- 15.1 (out of 100) and the pain sub-score was 30.2 +/- 9.7 (out of 40) at the last follow-up. The average ankle range of motion was 32.3 degrees +/- 12.7 degrees on the radiographs. CT scan revealed Type A cysts (<200 mm(2)) under the talar implant in 52% of cases and in the tibia in 50% of cases; these cysts were smaller than 100 mm(2) in 80% of cases and had no effect on the implants. No periprosthetic cysts larger than 400 mm(2) in size were identified. Discussion: The medium-term functional results and survivorship are comparable to those reported for other TAR designs. The incidence of cysts was low overall and there were no large-diameter cysts, which should improve long-term survival. The implant's design and materials likely played a role in preserving the periprosthetic bone stock. The AKILE (TM) TAR has distinctive features related to the low rate of large periprosthetic cysts in the medium-term. Level of evidence: IV (retrospective case series). (C) 2014 Elsevier Masson SAS. All rights reserved.