Abstract: Objective To conduct a clinical study on the population of Sledge unicondylar knee arthroplasty(UKA), and provide a reference for accurately determining the size of the prosthesis and selecting a suitable prosthesis. Methods Total 159 patients with Sledge UKA from February 2016 to November 2017 were selected and the clinical data were retrospectively analyzed. The size distribution of femur and tibia in the prosthesis of UKA was analyzed. The basic data index(sex, age, BMI) of patients were recorded. According to the data, the best matching relationship between femoral and tibial prosthesis was analyzed. The influencing factors of UKA prosthesis were screened out to predict the accuracy of femoral prosthesis. Results Among the femoral prosthesis, 21.4% are medium size prosthesis, 62.8% are small size prosthesis, and 15.7% are ultra small size prosthesis. Among the tibial prostheses, large prosthesis accounted for 19.5%, medium prosthesis for 52.8%, and small prosthesis for 27.8%. The best matching scheme was follow:small size tibia matching super small size or small size femoral prosthesis, large and medium size tibia matching medium size femoral prosthesis. The age and BMI had no significant effect on the judgment and selection of femoral prosthesis(all P>0.05), but there were significant differences in gender and height(female), all P<0.05. The distribution of the related parameters of the UKA prosthesis in Sledge population was preliminarily established. According to the analysis of data, the accuracy rate of gender to select the size of femoral prosthesis before operation is increased by 88.1%, of which the accuracy rate of women combined with height is 95.0%. The accuracy rate of tibial prosthesis size is 78.6% when selecting and judging again during operation. Conclusion The size of femoral prosthesis can be predicted by preoperative height and gender in clinic. The distribution of sledge UKA prosthesis analyzed in this study has high accuracy in prediction and judgment, which can provide powerful guidance for accurate determination of prosthesis size during operation.