KSSTA - 2026-07-22 - Journal Article
'Overall pain' is strongly associated with patient satisfaction: An item-level longitudinal analysis of the Oxford Knee Score in total and unicompartmental knee arthroplasty.
Tay ML, Rahardja R, Farrington WJ, Kawaguchi K, Young SW
Topics
Key Takeaway
OKS Question 1 ('overall pain') is the single strongest predictor of patient satisfaction after TKA and UKA, with ORs of 3.49–4.25 for TKA and 2.89–4.31 for UKA across all time points from 6 months to 15 years.
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Summary
This study used New Zealand Joint Registry data to determine which of the 12 OKS items most strongly predicts patient satisfaction after TKA and UKA across 15 years of follow-up. Logistic regression and ROC analysis identified Q1 ('overall pain') as the dominant predictor at every time point, with AUC 0.87–0.93 approaching that of the full 12-item OKS. PASS thresholds for the full OKS ranged from 33.5–39.5 depending on procedure and time point, while the Q1 PASS threshold was consistently 2.5 across both procedures.
Key Limitation
Registry-based satisfaction data is dichotomous and collected without standardized pain management or implant-specific stratification, preventing analysis of whether implant design, alignment philosophy, or analgesic protocol modifies the pain-satisfaction relationship.
Original Abstract
PURPOSE
While the Oxford Knee Score (OKS) is linked with patient satisfaction following knee arthroplasty, item-level associations are unknown. The primary aim of this study was to identify which of the 12 OKS questions were most strongly associated with satisfaction from early to 15-year follow-up to guide clinical practice towards improved patient-perceived outcomes. A secondary aim was to calculate Patient Acceptable Symptom State (PASS) thresholds to provide clinically meaningful benchmarks.
METHODS
A total of 9384 total knee (TKA) and 2424 unicompartmental knee arthroplasty (UKA) with OKS and dichotomised satisfaction scores in the New Zealand Joint Registry were included. Score associations and PASS thresholds up to 15 years were assessed using logistic regression and receiver operating characteristic (ROC) analyses.
RESULTS
Q1 'overall pain' demonstrated the strongest and most consistent association with satisfaction, with longitudinal consistency for both TKA (6 months: odds ratio (OR) 3.49; 5 years: OR 4.25; 10 years: OR 3.77; 15 years: OR 3.67; all p < 0.001 against the null hypothesis OR = 1) and UKA (6 months: OR 3.88; 5 years: OR 4.25; 10 years: OR 4.31; 15 years: OR 2.89, all p < 0.001). This question demonstrated good discriminatory performance, with AUC values approaching those of the full OKS and a composite score with the four strongest predictors (area under the curve [AUC] 0.87-0.93). PASS thresholds were 35.5 and 36.5 at 6 months, 34.5 and 39.5 at 5 years, 33.5 and 37.5 at 10 years, and 35.5 and 28.5 at 15 years for TKA and UKA, respectively. The PASS threshold for Q1 was 2.5 across procedures at all follow-up.
CONCLUSIONS
Despite OKS being a multidimensional instrument, overall pain was the item most strongly associated with satisfaction after knee arthroplasty, suggesting that pain-related symptoms may be more closely aligned with satisfaction than the other domains. PASS thresholds provide real-world benchmarks for clinical practice.
LEVEL OF EVIDENCE
Level IV, retrospective case series.