Objective:To analyze the impacts of volume-based procurement(VBP) of artificial joints on the hospital costs for discharged patients who underwent total hip arthroplasty.Methods:The discharge data of 515 total hip replacement patients at a tertiary public hospital in Baise city was collected, comprising 353 cases pre-VBP (January 2021 to March 2022) and 162 cases post-VBP (April to October 2022). Data was analyzed using interrupted time series method. Between October to December 2022 and July to August 2023, one-to-one unstructured qualitative interviews were conducted with the director, doctors, and nurses of the orthopedic department, as well as staffs of the medical equipment department and the health insurance office. The aim was to gather insights about the implementation details of the VBP policy for artificial joint implants, VBP policy's impact on hospitalization costs and its underlying causes.Results:After the implementation of the VBP for artificial joint implants, the hospitalization expenses of surgical patients immediately dropped by 22 566 yuan ( P<0.001), but the change in the slope of the long-term trend was not statistically significant ( P=0.430). From the perspective of cost structure, the cost of disposable surgical materials decreased immediately by 26 889 yuan ( P<0.001), with a long-term trend slope change of -515 yuan per month ( P<0.001). Meanwhile, there were varying degrees of immediate increases in surgical treatment costs, non-surgical item treatment costs, and non-surgical disposable medical material costs ( P<0.05). Specifically, the long-term trend slope for surgical treatment costs and non-surgical disposable medical material costs decreased by -637 yuan per month and -372 yuan per month, respectively ( P<0.001). However, the long-term trend slope of non-surgical item treatment costs did not show statistical significance ( P=0.196). The out-of-pocket expenses immediately decreased by 7 195 yuan ( P<0.001), but the change in the slope of the long-term trend was not statistically significant ( P=0.550). The interview results showed that there were not much overall changes found in the use and surgeries of artificial joints after centralized procurement, but there were delivery delays, and the changes in some cost indicators of hospitalization expenses were also related to the reform of diagnosis related groups payment methods. Conclusions:The implementation of VBP effectively reduced the hospitalization cost for total hip arthroplasty patients, primarily by decreasing artificial joint cost. In addition, it optimized the cost structure, alleviated the financial burden on patients and saved medical insurance expenditures. Future initiatives should focus on improving the medical insurance payment reform to form a policy synergy, creating a cohesive policy framework that enhances the effectiveness of VBP policy, thereby facilitating the high-quality development of public hospitals and medical services.