Preoperative angiotensin II type 2 receptor is a predictor for developing chronic post-surgical pain after total knee...

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).

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.

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.

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.