Objective:To explore the role of virtual reduction and design of 3D printed guide template in assisting reduction and internal fixation of comminuted patellar fractures.Methods:A retrospective study was conducted of 12 patients who had been treated for closed patellar fractures from March 2016 to April 2019 at Department of Orthopaedics, Jiangxi Provincial People's Hospital. They were 8 males and 4 females with an average age of 35.4 years (from 22 to 51). All their fractures were type 34-C3 (more than 3 fragments) according to the AO/OTA classification. Their preoperative CT data were imported into software Mimics to print a full patella, upper and lower halves of the patella, and a guide template for reduction. During operation, bone fragments were first temporarily fixated with a fine Kirschner wire after combined together with the assistance of reduction templates for upper and lower hemi-patellas. Next, the whole patella was precisely reset and definitely fixated using patellar ring ligation and tension band wire with the assistance of the reduction guide template for full patellar. Recorded were operation time, fluoroscopic frequency, and visual analogue scale (VAS), knee range of motion (ROM) and knee function B?stman scores at the last follow-up.Results:In this group of patients, operation time averaged 90 minutes (from 75 to 120 minutes), fluoroscopic frequency 4.5 times (from 3 to 8 times), follow-up duration 19 weeks (from 16 to 22 weeks), and fracture healing time 14 weeks (from 11 to 17 weeks). At their last follow-up, X-ray showed good patellar morphology, fine internal fixation positions and an average VAS pain scores of 0.3 (from 0 to 1), their knee joints could be fully straightened, their knee ROM averaged 130°(from 100° to 138°), and their knee B?stman scores 28.8 points (from 21 to 30 points), giving 9 excellent and 3 good cases.Conclusion:3D printed reduction guide templates can significantly improve the efficiency and quality of surgical reduction in comminuted patella fractures, enhancing fixation strength and facilitating early and full range exercise of the knee joint to achieve excellent recovery.