Improvement in Central Sensitization Following Total Knee Arthroplasty Is Associated With Severe Preoperative Pain and Affects Postoperative Quality of Life: A Retrospective Study

ABSTRACT Objective Central sensitization (CS) is associated with quality of life (QOL) after total knee arthroplasty (TKA). However, how CS changes after TKA and whether these changes have clinical relevance remain unclear. Therefore, this study was conducted to identify changes in CS after TKA and to assess the clinical significance of these changes. Methods This retrospective study was conducted on 92 patients between January 2021 and May 2023. CS severity was quantified using the Central Sensitization Inventory (CSI). One year after TKA, the patients were divided into groups based on whether CS severity improved by ≥ 1 level (improved group) or did not improve (non‐improved group). The differences in preoperative and postoperative characteristics of patients in the two groups were analyzed. These characteristics included demographics, underlying diseases, physical examinations, and the Hospital for Special Surgery (HSS) knee score. QOL improvement was compared based on two different minimal clinically important changes (MIC) in the Short‐Form Health Survey (SF‐36). Continuous variables were compared using Student's t ‐test or the Mann–Whitney U ‐test. The chi‐squared test was used to compare categorical variables. Results The postoperative CS severity in patients was significantly lower compared to preoperative levels ( p < 0.001). The improved group exhibited a lower HSS knee pain score ( p < 0.001). Out of the eight SF‐36 scales, five showed significantly greater improvement in the improved group compared to the non‐improved group. The mean postoperative increases in scores for all eight SF‐36 scales exceeded the MIC in the improved group, whereas half of the scales fell below the MIC in the non‐improved group. Conclusions CS showed improvement after TKA, particularly in patients with more severe preoperative pain. This improvement appears to be correlated with the improvement in QOL after TKA.