Is Fretting Corrosion at the Modular Junction of Revision Total Knee Arthroplasty Actually a Problem?

Abstract

Corrosion at modular junctions in total knee arthroplasty (TKA) implants is recognized, but its clinical relevance remains unclear. This study evaluated corrosion at modular stem-bore junctions and examined whether severity correlated with radiographic evidence of adverse local tissue reactions or osteolysis. We evaluated 196 retrieved modular stem and bore components from 98 revision TKA patients, including taper (n = 73) and threaded (n = 25) designs. The median time in situ was 24 months for taper and 15 months for threaded junctions (P = 0.052). The median age at explant was 66 years (interquartile range (IQR), 60.7 to 74.4), and 47% of patients were women. Periprosthetic joint infection (n = 49) and aseptic loosening (n = 29) were the most common indications for component explantation. Fretting corrosion at the modular junction was graded using the modified Goldberg Score (mGS) and quantified using an optical coordinate measuring machine. Radiographs were evaluated for changes around the modular junction. Statistical analyses included Mann-Whitney U-, Chi-Square, and Spearman's correlation tests. Taper junctions demonstrated significantly greater corrosion than threaded designs (P < 0.001). The median mGS for modular tapers was 4 for femoral components, 3 for femoral stems, and two for both tibial components and stems. Threaded junctions showed minimal damage across all interfaces with a median score of 1. Damage patterns included fretting wear, corrosion features, and dark deposits. Among cobalt-chromium (CoCr) femoral bore tapers with mGS of 4, median material loss was 0.56 mm³, while CoCr tibial bores with mGS 4 could not be quantitatively assessed due to technical constraints. The corresponding titanium alloy femoral and tibial stem tapers showed a median loss of 0.071 mm³, and 0.067 mm³, respectively. Corrosion severity did not correlate with localized radiographic findings or the indication for revision. In this study of retrieved modular TKA components, taper junctions exhibited significantly more corrosion than threaded junctions. However, corrosion severity was not associated with radiographic findings or etiology of failure. Corrosion products differed from those typically observed in THA, suggesting a distinct mechanism. Further research is required to clarify potential clinical implications.