RSA-measured femoral component migration
aseptic loosening, UKR cementless twin-peg, dislocation
HYDROXYAPATITE
Generally, we found low femoral component migration in all three groups with only TT and TR at 5-year follow-up above the precision limit (CR). This aligns with no revisions of femoral components for aseptic loosening, since the two revisions were related to one tibial component aseptic loosening and one bearing dislocation. Between 2 and 5 years, we did not see improved component fixation for neither the CLTP nor the CTP groups compared with the CSP group as reference. Although the CLTP and CTP femoral components were designed to be inserted at a higher flexion angle relative to the femoral bone, the flexion angle was similar in the three groups. However, we found increased migration in femoral components with a lower flexion angle.Theoretically, a twin-peg stabilize the UKR femoral component more than a single-peg and a few studies have also indicated this as an advantage. Mohammed et al. conducted a propensity-matched registry-based study comparing a matched group of 2834 patients with Oxford UKR cemented single-peg and 2834 patients with Oxford UKR cemented twin-peg femoral components using data from the National Joint Registry for England, Wales, Northern Ireland and Isle of Man [Reiner et al. compared the pullout force to failure between cemented single-peg and cemented twin-peg components in 12 human donor cadaver knees, which were randomized to cemented twin-peg in one knee and cemented single-peg in the other knee, and found higher pullout force to failure in the CTP group [Cementless Oxford UKR femoral components are inserted press-fit and the later fixation relies on osseointegration in the hydroxyapatite coating. Campi et al. reported higher RSA-measured migration of Oxford UKR cementless twin-peg than for cemented single-peg femoral components during the first 3 months and thereafter stabilization [Campi et al. presented 5-year migrations of the same patient cohort as in the study by Kendrick et al. [