Total ankle replacement (TAR) has been used as a surgical intervention for arthritis since the 1970s. However, unlike clinically successful hip and knee replacements, TARs are renowned for extensive contraindications to surgery and high failure rates with an average of 83% survival at 5 years. The majority cite aseptic loosening as the reason for failure. The aim of this study wais to analyse retrieved TARs visually and through interferometry to identify potential the failure mechanisms associated with these devices. Retrieved total ankle replacements (n=11) from consecutive revision surgeries carried out at Chapel Allerton Hospital, Leeds between August 2012 and January 2014, were collected for study at the University of Leeds, under an NRES approved procedure (09/H1307/60). The bearing surfaces of the samples were visually inspected for evidence of damage and wear. The bearing surfaces between the tibial component and the flat surface of the polyethylene insert were then examined using a scanning white light interferometer (NP Flex, Bruker, USA). It was not possible to characterise the talar bearing surface or the inferior polyethylene surface at this stage through interferometry due to the curvature of the surface. The components were aligned and five sections on each of the surfaces measured. These sections represented; anterior-medial, anterior-lateral, posterior-medial, posterior lateral and central regions of the bearing surfaces. 3D roughness values were recorded, and the mean 3D surface roughness compared between implants. Measurements were taken on the medial and lateral aspects of the bearing surfaces to investigate whether damage was location specific. A coefficient of determination was calculated to assess the relationship between implantation time and surface roughness.Introduction
Methods
