Evaluation of Total Ankle Arthroplasty Using Highly Crosslinked Ultrahigh-Molecular-Weight Polyethylene Subjected to Physiological Loading

Abstract

Background: Highly crosslinked polyethylene (HXLPE) was developed for its superior wear properties in comparison to conventional polyethylene (CPE). Concern over fatigue resistance has prevented widespread adoption of HXLPE for use in total ankle arthroplasty (TAA). The aim of this study was to determine whether HXLPE has sufficient fatigue strength for total ankle arthroplasty under simulated physiologically relevant motion profiles and loading in the ankle. Methods: Physiologic load and motion profiles representative of walking gait were incorporated into a computational model of a semiconstrained, fixed-bearing TAA to determine the loading state with highest stresses in the HXLPE bearing. Subsequent fatigue testing to 10 million cycles (Mc) at 5600 N was performed to assess bearing strength. Results: Peak stresses in the bearing were predicted at peak axial load and peak dorsiflexion during gait, occurring near heel off. All samples withstood 10 Mc of fatigue loading at that orientation without polyethylene bearing fracture. Conclusion: HXLPE had sufficient fatigue strength to withstand 10 Mc of loading at more than 5 times body weight at the point of peak stresses during simulated gait in total ankle arthroplasty. Clinical Relevance: HXLPE may be mechanically strong enough to withstand the in vivo demands of the ankle. Improvements in wear afforded by HXLPE can be obtained without compromising sufficient polyethylene strength properties in total ankle arthroplasty.

Effect of novel polyethylene insert configurations on bone-implant micromotion and contact stresses in total ankle replacement prostheses: a finite element analysis

“…Similarly, the maximum contact stress curves of the articular surfaces of the inserts of the four models exhibit similar trends, and the maximum surface stress increases with increasing axial load during the stance phase and reaches a peak during the gait period of 40%–50%, which is similar to the results of previous literature ( Bischoff et al, 2019 ). The inserts of models B and D, utilizing a continuous flexible layer design scheme, demonstrate lower stress levels during the swing phase ( Figure 6E ).…”

Investigating Material Performance in Artificial Ankle Joints: A Biomechanical Study

“…The finite element method (FEM) serves as a robust numerical technique that is extensively utilized for intricate numeric analyses under complex conditions and geometries [18]. It finds broad application in assessing ankle and foot models' performance under various loading and material conditions [19], as well as in evaluating the stability of prosthetic ankle joints [20]. Ankle joint designs often feature intricate geometries, posing challenges in deriving analytical solutions for stress distribution and optimal material selection.…”

“…Under impact loading, artificial ankle joints typically endure stress levels equal to five times the body's weight during walking [16,19], escalating to approximately ten times during running [21,22], and two to twelve times during jumping. The importance of utilizing UHMWPE elements in ankle joint manufacturing is evident, given their low pressure values compared to other elements, despite exhibiting higher displacement values, facilitating appropriate design and material selection under different loads.…”

Computational Model Validation of Contact Mechanics in Total Ankle Arthroplasty

“…With the advancements of modeling technologies, it is possible to leverage the accuracy and rigor allowed by the modeling techniques in cases where it may not be possible to achieve the same level of precision in the experiment. The validated computer modeling approach presented here can also be utilized to precisely capture the impact of surgical variabilities in a more insightful and less expensive way, instead of conducting experiments by deliberately introduced component positioning variations …”

“…Peak contact pressures and/or stresses in TJA can be used to estimate the potential for localized polyethylene damage leading to delamination or fracture. Advancement in polyethylene materials have improved its ability to withstand service loads, reducing the potential for localized damage. Contact area (or equivalently average contact pressure) are associated with potential for overall wear .…”