Sports athletes easily get joint damage due to the high intensity of physical training and exertion. The treatment of joint injury caused by physical exercise is very important for competitive sports. Joint composition structure is complex and the knee joint is considered as an example in the full text and the application of CT imaging technology in the diagnosis and treatment of knee joint was studied, which a certain clinical significance for the treatment of joint injury of athletes. In this work it is proposed to establish a unified registration system and statistical coordinate system to achieve image fusion. Secondly, the optimization design of the fusion image algorithm based on the virtual projection CT data was carried out and the image was converted into the same coordinate system. Carry out the final image fusion. The X-ray image and CT image data were combined to obtain the absolute coordinates of the registration position and then the image was fused. Finally, the fusion medical imaging technology was applied in the diagnosis and treatment of knee joint injury. It can be seen through data collection and analysis on 21 cases of patients that the integration of medical imaging technology can diagnosis knee injury accurately, thereby reducing unnecessary surgery and improving the rehabilitation effect of patients.