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Published on: February 27, 2018
Late stabilization after initial migration in patients undergoing cemented total knee arthroplasty: a 5-year followup
Shaho Hasan1, Bart L Kaptein2, Perla J Marang-van de Mheen3
1Department of Orthopaedics, Leiden University Medical Center, Leiden, The Netherlands. S.Hasan@lumc.nl.
Background And Purpose:
In total knee arthroplasty (TKA), metal-backed (MBT) and all-polyethylene (APT) designs have shown comparable implant migration up to 2 years postoperatively using radiostereometric analysis (RSA). However, studies comparing mid-term migration of both designs are lacking. Furthermore, continuously migrating TKAs up to 2 years may continue to migrate or stabilize thereafter. Therefore, we compared 5-year migration of MBT and APT using either cruciate-stabilizing (CS) or posteriorstabilizing (PS) designs and specifically assessed migration profiles of continuously migrating TKAs beyond 2 years.
Patients And Methods:
The present study includes results from 2 randomized trials comparing migration of cemented MBT with APT of either CS (CS study, n = 59) or PS (PS study, n = 56) design. 2 surgeons performed all surgeries. We used a linear mixed model for the analyses.
Results:
The overall migration between MBT and APT TKAs was similar for either the CS or PS design over a 5-year period. In both studies combined, 9 implants showed continuous migration in the second postoperative year, of which 1 (APT-CS) was revised for instability, 4 (2 MBT-CS, MBT-PS, APT-PS) stabilized, and 4 (2 MBT-CS, APT-CS, MBT-PS) lacked 5-year data.
Interpretation:
Overall migration was similar between MBT and APT TKAs up to 5 years, for both the CS and PS design. 4 initially migrating TKAs stabilized between 2- and 5-year follow-up, stressing the need for longer-term followup to determine whether second-year continuous migration correctly predicts loosening.
