Correlation Between Angiotensin Ⅱ Type 2 Receptor Level And Chronic Post-surgical Pain After Total Knee Arthroplasty

Objective The aim of our research is to observe the the correlation between preoperative angiotensin Ⅱ type 2 receptor（AT₂R）level and chronic post-surgical pain（CPSP）after total knee arthroplasty（TKA）.Methods We received a total of 120 patients with primary knee osteoarthritis who underwent unilateral knee arthroplasty under elective general anesthesia between May2019 and January 2020,no gender restriction,aged 45 to 70 years,BMI 18 to 30 Kg/m²,The American Society of Anesthesiologists（ASA）grade Ⅰ-Ⅲ.All patients had consistent anesthesia management and surgical procedures.The knee VAS score of all patients in the outpatient follow-up at 3 months after surgery were assessed as CPSP positive by VAS score greater than 3 during resting or（and）exercise,and the patients were set as the positive group（n=41）;CPSP was defined as negative with a VAS score of less than or equal to 3 at rest or（and）exercise,which was set as negative group（n=79）.Before induction of anesthesia,venous blood was drawn to measure the level of plasma AT₂R.Patient’s baseline characteristics（Sex,Age,BMI,ASA grade,knee osteoarthritis duration and K-L grade）;preoperative scales and pain-related variables（PD-Q score,WOMAC score,HAD score,PPT,quiet and exercise VAS score of knee joint）;intraoperative variables（propofol and remifentanil dosage,operation time,tourniquet usage time,bleeding volume）;postoperative 1d variables（quiet and exercise VAS score of knee joint,PPT and rescue analgesia）;quiet and exercise VAS score of knee joint at postoperative 3 months.Results The incidence of CPSP was 34.2%（n=41）.The univariate results showed that,compared with the negative group,the positive group had a higher preoperative plasma AT₂R level and a longer duration of knee osteoarthritis（P<0.05）.The preoperative VAS score during movement,PD-Q score,WOMAC score and 3 months postoperative VAS score of the positive group were significantly higher than those of the negative group,and PPT was significantly lower than that of the negative group（P<0.05）.There was no statistically significant difference in other indicators between the two groups.The multivariate binary logistic regression model was used for multivariate analysis while adjusting for any clinical factors（gender,BMI,HAD）which may influence CPSP and some factors（knee OA duration,preoperative serum AT₂R,preoperative VAS score,PD-Q score,WOMAC score,preoperative PPT）that have shown to be associated with CPSP in the univariate analysis（P<0.10）.The results of multivariate binary logistic regression showed that patients with high plasma AT₂R level（OR=2.610,95%CⅠ2.161～3.046,P<0.05）and PD-Q score（OR=2.341,95%CⅠ 1.670～3.016,P<0.05）before surgery had an increased risk of CPSP after surgery.There was a significant correlation between preoperative plasma AT₂R level and PD-Q score（P<0.05）.Conclusion Preoperative plasma AT₂R was independent risk factor of CPSP.The higher concentration of preoperative plasma AT₂R is,the higher risk of CPSP occurs.So concentration of preoperative plasma AT₂R has clinical value for the diagnosis of CPSP.