Corrosion and wear damage estimations for retrieved knee and hip implants

Predicting the lifetime and function of orthopedic implants requires learning from failures observed in retrieved implants. This study scored mechanical and corrosion damage based on optical microscopy (OM) for 135 trunnion parts of retrieved hip implants and 106 tibial baseplates of retrieved knee implants. We used scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy to categorize the damage types. This data was correlated with implant and patient factors. Fretting, third-body wear, tribocorrosion, and biofilms were observed. Mechanically assisted corrosion, e.g., tribocorrosion, was the dominant damage mode for both hip and knee implants. The knee implant damage strongly depended on the locking mechanism of the polyethylene insert on the tibial baseplate. For the trunnion part, infection prior to or at surgery was correlated with higher SEM damage scores. Inflammatory arthritis and cemented hip implants correlated with lower SEM damage scores of the trunnion. Damage scores decreased with patient age, and increased with patient weight, body mass index, and years of implantation.