Total Ankle Arthroplasty Polyethylene Wear Varies With Implant Type and Mode of Failure

Abstract

Background

Polyethylene wear is a mode of failure of any joint replacement, including total ankle arthroplasty (TAA). This study aims to quantify the type and severity of polyethylene damage from retrieved TAA prostheses. We hypothesized that polyethylene wear will be more extensive in TAAs that underwent revision (polyethylene and tibial and/or talar component) rather than reoperation (polyethylene exchange alone), and that wear would vary between implants based on extent of constraint.

Methods

This is a retrospective study of TAA patients (2007-2021) who underwent revision or reoperation following primary TAA with a symmetric bicondylar (SB) implant with more constraint (n = 25, Inbone II/Infinity) or an asymmetric bicondylar (AB) implant with less constraint (n = 30, Salto Talaris). Retrieved polyethylene inserts were examined microscopically to characterize wear patterns according to a standardized protocol. Two independent raters graded articular and backside surfaces in quadrants for 7 damage modes. We assessed associations between polyethylene wear pattern and severity with implant type, revision, and reoperation.

Results

Fifty-five TAAs underwent revision (n = 28) or reoperation (n = 27). The SB cohort had significantly greater overall polyethylene damage severity for one rater (P = .007), and greater damage severity in the medial anterior articular region (P = .019) than the AB for both raters. Revision TAAs had significantly greater overall damage severity than reoperations (P ≤ .036), with significantly greater damage severity in multiple articular-sided regions (P ≤ .048). Scratching (P ≤ .030) and pitting (P < .001) were also significantly greater in revision TAAs

Conclusion

Total ankle arthroplasties with primary SB implants exhibited greater overall polyethylene damage severity than AB implants. Thus, surgeons may want to consider polyethylene type when selecting an implant. In addition, revision was associated with greater polyethylene damage than reoperation. Clinical Relevance. This may suggest polyethylene damage severity increases with increased constraint. Furthermore, polyethylene damage severity is linked to TAA failure, indicating a more severe intraarticular process involving the polyethylene.