No early tibial tray loosening after surface cementing technique in mobile-bearing TKA

Controversy still exists regarding which cementation technique of the tibial component is preferable. Full cementation showed excellent long-term outcomes, and surface cementation with fixed-bearing designs provided excellent mid-term results. Concerns have been expressed about possible rotary forces to the tibial rotating platform, when the tibial stem remains cementless, with the risk of early loosening. The purpose of this study was to evaluate the rate of early loosening and radiolucency lines in 70 consecutive unidirectional rotating platform, posterior stabilized, total knee arthroplasties, using surface cementation. Multivariate analysis was performed to identify any correlations between early loosening or radiolucency lines and clinically relevant covariates: age, sex, BMI, follow-up time, cement penetration, radiolucencies, tibial slope, femoral flexion, frontal alignment, pre-operative and post-operative Knee Scores. The tibial plateau was divided into four zones in antero-posterior view and into two zones in lateral view, and the cement penetration was evaluated in each zone. The mean follow-up was 43 months (SD 14), and the average patients' age was 73 (SD 7). The Knee Score averaged 91 (SD 8) and the Function score 86 (SD 17) at last follow-up visit. The cement penetration was >2 mm in all zones. No early loosening was detected, but in five asymptomatic patients (7%) radiolucency was noted around the tibial stem. The presence of radiolucent lines was not correlated with any of the covariates. The rate of early loosening and radiolucency lines with mobile tibial tray and surface cementation is comparable to other studies using different cementation techniques or surface cementation combined with fixed platform total knee arthroplasties.