Analysis of retrieved agility total ankle arthroplasty systems.
BACKGROUND
First generation total ankle arthroplasty (TAA) systems showed high rates of failure. The Agility (DePuy, Warsaw, IN) TAA system, a second generation design, had improved outcomes; however, implant failure due to loosening of the metallic components persisted. The purpose of this study was to analyze the damage modes and radiographic mode(s) of failure observed in retrieved Agility TAA.


METHODS
Ten devices were collected and each component was analyzed for common damage modes using microscopy. Clinical damage was analyzed with postoperative implant and preoperative revision procedure radiographs.


RESULTS
Analyses revealed damage/wear to retrieved components, including abrasion, dishing, and pitting. These third-body wear particles may be a precursor to wear debris induced osteolysis which could cause component loosening. Seven TAA systems were removed due to loosening or subsidence, suggesting component damage/wear may lead to clinically observed component loosening. Retrieval analysis indicated the polyethylene experiences edge loading, resulting in increased contact stresses to polyethylene in the primary articulation region and wear.


CONCLUSIONS
Since poor clinical outcomes have been associated with component instability and osteolysis, analyzing retrieved components wear and damage may be an important step toward improving implant design, thereby decreasing wear debris induced osteolysis and improving clinical outcomes.
Vaupel
Zachary
Z
William Beaumont Hospital, Department of Orthopaedic Research, Research Institute, Royal Oak, MI 48073-6769, USA. erin.baker@beaumont.edu
Baker
Erin A
EA
Baker
Kevin C
KC
Kurdziel
Michael D
MD
Fortin
Paul T
PT
D000328:Adult; D000843:Ankle Joint; D019643:Arthroplasty, Replacement / Q000295:instrumentation*; D015331:Cohort Studies; D006801:Humans; D007593:Joint Instability / Q000000981:diagnostic imaging / Q000209:etiology* / Q000601:surgery; D007595:Joint Prosthesis; D011474:Prosthesis Design; D011475:Prosthesis Failure; D011859:Radiography; D016059:Range of Motion, Articular; D012086:Reoperation; D012307:Risk Factors; D013997:Time Factors; D017211:Treatment Failure; D016474:Weight-Bearing