LAUSR

OBJECTIVE This study aimed to explore whether preoperative angiotensin II type 2 receptor (AT2R) level in knee osteoarthritis (OA) patients was an independent risk factor for chronic post-surgical pain (CPSP) after total knee arthroplasty (TKA). METHODS A total of 220 patients who had undergone unilateral TKA were enrolled from October 2019 to January 2020. Quantitative sensory testing (QST), PainDETECT questionnaires (PD-Q), the Western Ontario McMaster Universities Osteoarthritis Index (WOMAC), the hospital anxiety and depression (HAD) and serum AT2R were collected preoperatively. The primary outcome was the incidence of CPSP, which was defined as the visual analogue scale (VAS) score ≥ 4 in the ipsilateral knee joint six months after operation. RESULTS The prevalence of CPSP was 13.6% (n = 30). Multiple logistic regression analysis showed that patients with higher AT2R level (OR: 1.007, 95% CI: 1.003-1.011) and PD-Q score (OR: 1.146, 95% CI: 1.008-1.298) before surgery had an increased risk of CPSP after surgery, and a combination of preoperative AT2R and PD-Q (Akaike information criterion: 147.2; area under receiver operating characteristic (ROC) curve: 0.890) was able to correctly classify 90.16% of patients into CPSP positive or negative groups. CONCLUSION Our findings suggest that patients with higher preoperative AT2R level are at increased risk of developing CPSP following TKA. AT2R may serve as a candidate predictor for phenotyping CPSP in OA patients.