• ABSTRACT
    • We measured wear and creep in conventional tibial inserts retrieved after total knee arthroplasty by using Raman spectroscopy. The Raman spectra of thirteen tibial inserts retrieved after total knee arthroplasty with a mean in vivo time of 34.3 months were confocally measured along their bearing subsurface, and then from bearing surface to backside after cutting. The amounts of creep, wear, and wear rate in the medial and lateral load zone were computed from the full-width at half-maximum of a selected Raman band as a characteristic parameter related to strain. In all retrievals, the strain was higher than that of pristine samples at the bearing subsurface, and we observed a correlation between full-width at half-maximum and body weight/body mass index in both load zones. The amount of total penetration, creep, and wear were 0.27 ± 0.21, 0.082 ± 0.031, 0.19 ± 0.18 mm in the medial load zone and 0.22 ± 0.18, 0.080 ± 0.040, 0.14 ± 0.14 mm in the lateral load zone, respectively. The amount of wear in both load zones was strongly correlated with the in vivo time. The wear rate in eleven retrievals excluding an extremely short excised sample was 0.055 ± 0.020 mm/year in the medial load zone and 0.041 ± 0.020 mm/year in the lateral load zone. Raman spectroscopy proved very useful in separating creep and wear components of thickness reduction, thus revealing the wear rate of the UHMWPE material.