Abstract
Aim
To investigate the validity of threshold values for the Oxford Hip and Knee Score (OHS and OKS) for treatment success 12 months after total knee or hip replacement.
Methods
Questionnaires were administered to patients undergoing total hip (THA) or knee (TKA) replacement before and 12 months after surgery alongside questions assessing key accepted aspects of treatment success (satisfaction, pain relief, functional improvement) to form a composite criterion of success and assessed using receiver operator characteristic (ROC) analysis. Thresholds providing maximum sensitivity and specificity for predicting treatment success were determined for the total sample and subgroups defined by pre-surgery scores.
Results
Data was available for 3203 THA and 2742 TKA patients. Applying the composite treatment success criterion, 52.7% of the TKA and 65.6% of the THA sample reported a successful treatment outcome. Accuracy for predicting treatment success was high for the OHS and OKS (both areas under curve 0.87). For the OHS a threshold value of 37.5 points showed highest sensitivity and specificity in the total sample, while for the OKS the optimal threshold was 32.5 points. Depending on pre-surgery scores optimal thresholds varied between 32.5 and 38.5 for the OHS and 28.5 and 35.5 for the OKS.
Conclusions
This is the first study to apply a comprehensive composite “success” anchor to the OHS and OKS in order to determine thresholds for successful treatment with total joint replacement. Compared to widely publicised postoperative satisfaction metrics, far fewer patients report success with our composite anchor.
