Introduction

The purpose of this study was to determine the influence of Central sensitization (CS) on the minimal clinically important difference (MCID) for Western Ontario and McMaster Universities Arthritis Index (WOMAC) score in patients who underwent Total Knee Arthroplasty (TKA) for knee osteoarthritis (OA).

Materials And Methods

A total of 422 patients who underwent TKA and completed a 2-year follow-up were enrolled in this study. CS was measured using the Central Sensitization Inventory (CSI). The WOMAC score was used to evaluate pre- and postoperative PRO. The measurement of the MCID was performed separately in the CS and non-CS groups using both the anchor-based method and the distribution method. The change difference method defined the MCID as the pre- and postoperative difference between the minimal-change group and the no-change group. In addition, the MCID was calculated using receiver operator characteristic (ROC) analysis. The percentage of MCID achievement in each group was also compared by applying the calculated MCID.

Results

According to the change difference method, the MCID for the WOMAC Total score was 22.1 points in the CS group and 13.2 in the non-CS group. The MCID using the ROC cut-off value was 29.5 for the WOMAC Total score in the CS group and 26.5 in the non-CS group. MCID achievement rates in WOMAC Pain, Function, and Total were all found to be significantly higher in the non-CS group through the change difference method and the ROC method (all p<0.05)

Conclusion

The MCID for the WOMAC score of CS patients following TKA was greater than that of non-CS patients. Furthermore, by applying their own MCID, CS patients showed a lower MCID achievement rate than non-CS patients.