The effect of trunnionosis on the risk of re-revision following femoral head exchange in hip arthroplasty.

Abstract

Fretting corrosion at modular junctions contributes to arthroplasty failure. Currently, no evidence-based guidelines are available regarding the acceptable level of trunnion corrosion that can occur <i>in vivo</i>. We aimed to examine the relationship between trunnion corrosion and risk of re-revision to assist surgeons with intraoperative decision making. Grading by 3 independent examiners of revised and re-revised head components was performed using a modified Goldberg corrosion scale. Samples were separated into low-grade (LG) and high-grade (HG) corrosion. Mechanical testing determined the relationship between corrosion severity and pull-off strength at the head-stem junction. 529 retrieved femoral heads were analysed. A positive association was detected between males and HG corrosion (OR 2.07; 95% CI, 1.45-2.94; <i>p</i> < 0.001). No difference between the survivorship of LG and HG heads was detected (<i>p</i>-value = 0.247). In the re-revised sample, the first implant had a time <i>in situ</i> that was on average 7.97 years longer (95% CI, 5.4-10.6) than that of the subsequent re-revised femoral head. Severe corrosion on the first head was associated with a 37.5 (95% CI, 4.00-1944) fold increase of HG on the subsequent head (<i>p</i> < 0.001). Femoral disassembly force had a positive correlation with stem taper corrosion grade (<i>p</i> = 0.001). A well-fixed stem with corrosion may remain <i>in situ</i>.