Rapid Skin Temperature Measurement is Valuable in Evaluating Inflammation and Functional Status After Total Knee Arthroplasty：A Case Control Study

Background: ： The skin temperature of the knee joint changes after total knee arthroplasty (TKA), and these changes are easy to detect and can be measured simply and accurately, but its significance is not clear. Methods: A total of 205 patients who underwent unilateral primary TKA were selected; the bilateral knee skin temperature, inflammatory indicators, pain score, knee range of motion (ROM) and quadriceps muscle strength of the patients were measured from preoperatively to 6 months postoperatively; and the relationships between the differential skin temperature and inflammatory and functional prognosis were analyzed. Results: The differential skin temperature was significantly correlated with the inflammatory index, pain score, ROM and muscle strength. A difference in skin temperature between the two sides of >0.52°C at 2 weeks after the operation suggested that the level of c-reactive protein increased (sensitivity 81.4%, specificity 39.8%) and affected the ROM at 2 weeks and 6 weeks after the operation, as well as the muscle strength at 6 weeks and 3 months after the operation. A difference in skin temperature of >2.15°C at 2 weeks after the operation suggested that the level of c-reactive protein increased by more than three times (sensitivity 90.9%, specificity 95.2%) and affected the ROM at 3 months and 6 months after the operation and muscle strength at 6 weeks and 3 months after the operation. Conclusion: The difference in the knee skin temperature between the operated side and contralateral side is closely related to functional recovery and the magnitude of increase in inflammatory indicators in patients after TKA. Skin temperature measurements can be used as references for predicting functional recovery and inflammatory indicators. Trial registration： Medical Ethics Committee of Affiliated Hospital of Qingdao University,QYFYKYLL2327945,2015-03-01