Correlation between Oxford knee score and satisfaction after unicompartmental knee arthroplasty

Abstract

To compare correlation between preoperative and postoperative Oxford knee scores and patient satisfaction after unicompartmental knee arthroplasty and to identify Oxford knee score threshold for different satisfactions. Totally 88 patients with unicompartmental knee arthroplasty were enrolled from January 2017 to June 2018, including 24 males and 64 females, aged from 52 to 77 years old with an average of (65.39±7.33) years old. All patients completed Oxford Knee Score Questionnaire and Satisfaction Questionnaire before operation and 6 months after operation. Correlation between Oxford knee score and satisfaction was analyzed by Spearman rank correlation test, the satisfaction degree was used as the gold standard, and ROC curves were drawn to judge the value of knee score on patient satisfaction before and after operation. Yoden index were used to explore its optimal threshold. There was no significant correlation between preoperative Oxford knee score and satisfaction before operation (r=-0.058, P>0.05) . There was a moderate positive correlation between postoperative Oxford knee score and satisfaction (r=0.51, P<0.05), it means that the higher Oxford knee score after surgery, the higher the patients satisfaction. The area under ROC curve for preoperative Oxford knee score was 0.55 [(95%CI (0.40, 0.70), P> 0.05 ], which had not significant difference; the area under ROC curve of postoperative Oxford knee joint score was 0.95 [(95%CI (0.90, 0.99), P<0.05 ], whichhadsignificantdifference. Whenpostoperative Oxfordknee score was 35.5, the sensitivity ofsatisfactionwas0.86, the specificity was1.00, andYodenindex wasthe largest (0.86), whichcouldbe usedasa threshold for judging patient satisfaction, and had significant differences. Preoperative Oxford knee score was poorly correlated with patient satisfaction after knee joint replacement. It was not correct in predicting patient satisfaction. Postoperative Oxford knee score was significantly correlated with patient satisfaction. Patients with a knee score of 35.5 or above may be considered satisfied with surgical outcome. At the same time, we confirm that Oxford knee score has the same threshold for evaluation of subjective satisfaction after total knee arthroplasty and unicompartmental knee arthroplasty.