Effects of age and sex on patient-reported outcomes following total knee arthroplasty with a rotating bearing tibial platform design: A single-surgeon practice registry study

Abstract

Purpose: Younger female patients presenting with end-stage osteoarthritis may benefit from a rotating bearing (RB) knee (RBK) design in total knee arthroplasty (TKA). The aims of this study were to report on the clinical outcomes of a RB RBK, and investigate whether patient-reported outcome measures (PROMs) are influenced by age at surgery and sex, as well as the interaction between age and sex when controlled for general health, baseline knee function and laterality. Methods: PROMs including the European Quality of Life Five Dimension Five Level Scale (EQ-5D-5L), visual analogue scale (VAS) pain, and Oxford Knee Score (OKS) were retrieved from a consecutive cohort of patients receiving a primary TKA with a posterior stabilised (PS) RBK implant. Regression analysis was performed to test the interaction between age and sex on OKS at minimum 12 month follow-up. An imputed dataset was used for the analysis. Results: A total of 352 patients and 420 treatments were included for the cohort analysis. Baseline scores for the imputed dataset were 0.52 (SD 0.22) for the EQ-5D Index,and 22.3 (SD 8.5) for the OKS. Postoperative OKS (37.8, SD 9.4) was observed at an average follow-up of 2 years (range 1 - 6 years). Age at surgery, sex, or their interaction had no statistically discernible relationship with their OKS-post score, or with the probability of exceeding patient acceptable symptom state. Conclusions: PROMs were not influenced by age at surgery and sex, or the interaction between age and sex. However, the PS-RB design yielded good patient-reported outcomes for the overall cohort with low rates of complications.