Preclinical Assessment Tools for Preventing Fretting-Corrosion within Modular Junctions of Total Joint Replacement - Fretting-corrosion in total joint arthroplasty (TJA) modular junctions can lead to implant failure and adverse local tissue reactions (ALTRs). ALTRs—mainly caused by fretting-corrosion products—can lead to catastrophic failures with a 3 to 5% prevalence in total hip arthroplasty. There is a large body of fretting-corrosion literature dating back to the 1980s. However, the rise in fretting-corrosion complications tells us that not all mechanisms of fretting-corrosion in modern TJA are known and that preclinical tests cannot predict when fretting-corrosion occurs in new designs. Thus, four critical barriers remain. 1) An incomplete understanding of the actual failure processes leading to ALTR; 2) Misleading preclinical testing strategies that do not consider the biological environment including inflammatory cells that can cause cell accelerated corrosion (CAC); 3) Insufficient material standards that do not eliminate microstructural preferential corrosion sites; 4) Neglecting surface topography in in vitro and in silico tests. The long-term goal is to increase TJA longevity by eliminating fretting- corrosion-induced ALTRs. Thus, this study aims to create comprehensive preclinical testing strategies and further elucidate the factors contributing to in vivo fretting-corrosion damage and ALTR in TJA. The central hypothesis is that the onset and progression of fretting-corrosion and ALTRs are 1) dependent on macro- and micro-surface geometry, manufacturing tolerances, and alloy microstructure, and 2) can be pre-clinically predicted by a combination of multi-scale finite element analysis (FEA), partial-slip fretting and corrosion tests under CAC conditions, and characterization of alloy microstructure to identify preferential corrosion sites. We will test our central hypothesis with three aims. Specific Aim 1: Identify factors dictating fretting onset and progression in primary TJA surgery and revision surgical interventions (ceramic heads and sleeves and dual mobility constructs). Specific Aim 2: Determine how implant design, bulk material, and alloy microstructure can enable indirect and direct cell accelerated corrosion (CAC) in modular junctions. Specific Aim 3: Determine how implant alloy microstructure can minimize the risk of material loss and ALTR under progressing fretting- corrosion and simulated CAC conditions. We will integrate the results from these individual studies to determine the total risk for ALTR by analyzing the 1) immune cell response within ALTR in periprosthetic tissues, 2) damage modes on the implant surfaces corresponding to the periprosthetic tissues, and 3) inputs to FEA and in vitro tests that are associated with these damage modes. The approach of retrieval analysis, finite element analysis, alloy characterization, fretting/corrosion tests, histopathology, and cell culture testing will lead to a better understanding of this significant clinical problem, better preclinical testing strategies, and implant alloy characterization protocols/specifications. The proposed work is innovative because these new tools will enable the improvement of scientific knowledge, technical preclinical testing capabilities, implant material standards, and clinical practice for predicting and monitoring fretting-corrosion and risk of ALTR.
