Objective:To compare the efficacy of 3D-printed guide plate assisted versus freehand placement of cannulated screws for the treatment of Sanders type II and III calcaneal fractures.Methods:A retrospective cohort study was conducted to analyze the clinical data of 29 patients with Sanders type II and III calcaneal fractures admitted to Chonggang General Hospital from June 2020 to October 2022. Among them, there were 18 males and 11 females, with an age range of 22-69 years [(40.1±11.5)years]. Nineteen patients were treated with individualized 3D-printed guide plate assisted placement of cannulated screws (3D-printed group) and 10 were treated with freehand placement of cannulated screws (freehand group). The surgical time, fluoroscopy times, postoperative 6-month calcaneal morphology (length, width, height, B?hler angle and Gissane angle), and American Orthopedic Foot and Ankle Society (AOFAS) ankle-hindfoot score and Maryland functional score assessed at 3, 6 months after operation and at the final follow-up were compared between the two groups. The incision healing and complications were observed.Results:The patients were followed up for 6-24 months [(11.3±2.5)months]. The surgical time and fluoroscopy times in the 3D-printed group were (53.4±9.1)minutes and (7.3±1.1)times, respectively, which were shorter than (90.2±16.0)minutes and (16.0±3.2)times in the freehand group (all P<0.01). At 6 months after operation, there was no significant difference in calcaneal length between the two groups ( P>0.05); the calcaneal width, height, B?hler angle and Gissane angle in the 3D-printed group [(34.0±1.8)mm, (47.2±1.6)mm, (27.8±1.0)°, (129.2±2.8)°] were superior than those in the freehand group [(37.5±2.0)mm, (43.0±2.7)mm, (25.8±1.5)°, (125.9±2.5)°] (all P<0.01). At 3, 6 months after operation and at the final follow-up, the values of AOFAS ankle-hindfoot score in the 3D-printed group [(72.2±2.3)points, (79.7±2.3)points, (86.5±4.4)points] were higher than those in the freehand group [(64.2±6.9)points, (73.4±4.2)points, (81.8±3.1)points] (all P<0.05); the values of Maryland score in the 3D-printed group [(71.4±7.7)points, (84.7±2.6)points, (91.5±2.5)points] were higher than those in the freehand group [(65.2±5.6)points, (79.1±3.8)points, (87.1±2.9)points] (all P<0.05). All surgical incisions were healed in stage I. In the 3D-printed group, there were no complications regarding infection, iatrogenic vascular or nerve injury, or fixation failure after surgery. In the freehand group, one patient with lateral sural cutaneous nerve injury was resolved spontaneously without specific treatment. Conclusion:Compared with freehand placement of cannulated screws, 3D-printed guide plate assisted placement of percutaneous placement has the advantages of shorter surgical time, fewer fluoroscopy times, lower reduction loss, better ankle joint function recovery, and less complications in treating Sanders type II and III calcaneal fractures.