Objective To explore the application effect of modified installing method of high flexion rotating platform prosthesis trial model in double compartment knee arthroplasty.Methods A total of 20 patients(26 knees)with severe knee osteoarthritis admitted to Hebi People's Hospital from January 2021 to April 2022 and required double compartment knee arthroplasty were selected as the research subjects.Patients were divided into the control group(10 knees)and the observation group(16 knees)based on the installing method of high flexion rotating platform prosthesis trial model.The patients in the control group used the conventional installing method of high flexion rotating platform prosthesis test model(placing the tibial side test model,the femoral side test model and finally the pad test model),while patients in the observation group used the modified installing method of high flexion rotating platform prosthesis test model(matching the femoral test model,pad and tibial test model when the patient flexed 60° to 90°,and placing them together into the knee joint osteotomy groove).The intraoperative bleeding volume and surgical time of patients in the two groups were recorded.Before surgery,2 weeks after surgery and 18 months after surgery,the knee joint function of patients was evaluated by the American hospital for special surgery(HSS)scoring system,and the range of motion(ROM)of knee joint of patients was measured by protractor.Results The intraopera-tive bleeding volume of patients in the observation group was significantly less than that in the control group,and the surgical time was significantly shorter than that in the control group(P＜0.05).There was no statistically significant difference in preoperative HSS score and ROM of knee joint of patients between the two groups(P＞0.05).At 2 weeks and 18 months after surgery,the HSS score and ROM of knee joint of patients in the observation group were significantly higher than those in the control group(P＜0.05).Conclusion Compared with the conventional installing method of high flexion rotating platform prosthesis trial method,the modified installing method of high flexion rotating platform prosthesis trial model in double compart-ment knee arthroplasty for patients with severe knee osteoarthritis can effectively improve surgical efficiency,reduce intraopera-tive bleeding,improve knee function and increase ROM of knee joint.