Abstract
Objectives
This study examines variations in knee arthroplasty patient reported outcome measures according to patient age.
Methods
We analysed prospectively collected outcome data (OKS, Eq5D, satisfaction, and revision) on 2456 primary knee arthroplasty patients. Patients were stratified into defined age groups (< 55, 55–64, 65–74, 75–84, and ≥85 years). Oxford Knee Score and Eq5D were analysed pre-operatively, and postoperatively at 6 months and 2 years. Absolute scores and post-operative change in scores were calculated and compared between age groups. Satisfaction scores (0–100) were analysed at 6 months post-operatively. Linear, logistic and ordinal regression modelling was used to describe the association between age and outcomes, for continuous, binary and ordinal outcomes, respectively. Kaplan-Meier analysis was performed to describe revision rates at 2 years.
Results
Patients aged 65–85 years demonstrated better preoperative status than those aged under 65 (OKS, p=0.03; Eq5D, p=0.048), and over 85 years (OKS, p=0.03). Postoperatively, no significant difference in OKS or Eq5D was observed between age groups. Postoperative change in score showed a linear trend for a greater post-operative change in younger patients at 6-months and 2-years (p< 0.04). Overall satisfaction score was 84.9, but patient satisfaction was significantly lower in those aged < 55 years compared to all other age groups (78.1 Vs. 84.8, p=0.031). Cumulative overall 2-year revision rate was 1.3%.
Conclusion
This study demonstrates that good early outcomes, as measured by the OKS and Eq5D, can be anticipated following knee replacement regardless of the patient's age, although younger patients gain greater improvement. However, the lower satisfaction in those aged < 55 years is a concern and suggests that outcome is not fully encapsulated by the OKS and Eq5D alone. This raises the question as to whether the OKS alone is an appropriate measure of pain and function in the younger, more active population.
