Objective To compare the effectiveness of open reduction and internal fixation with plate and closed reduction and internal fixation with Kirschner wire (K-wire) in the treatment of intra-articular displaced calcaneal fractures in older children. MethodsA clinical data of 35 older children (37 feet) with intra-articular displaced calcaneal fractures who were admitted between November 2014 and November 2020 and met the selection criteria were retrospectively analyzed. Among them, 19 cases (20 feet) underwent open reduction and internal fixation with plate (plate group), and 16 cases (17 feet) underwent closed reduction and internal fixation with K-wire (K-wire group). There was no significant difference in gender, age, cause of injury, side and type of fracture, and time from injury to admission, and preoperative calcaneal Gissane angle and Böhler angle (P>0.05). The postoperative calcaneal Gissane angle, Böhler angle, complications, and fracture healing were compared between the two groups. The ankle function was evaluated based on the American Orthopedic Foot and Ankle Society (AOFAS) ankle-hindfoot scoring system. Results Incision necrosis occurred in 1 foot in the plate group after operation, which healed after symptomatic treatment; the other incisions in the two groups healed by first intention. All children were followed up 12-39 months (mean, 19 months). X-ray films showed that the fractures in both groups healed; the healing time was (2.65±0.71) months in the plate group and (2.24±1.38) months in the K-wire group respectively, with no significant difference (t=1.161, P=0.253). At last follow-up, the calcaneal Gissane angle and Böhler angle returned to normal; and the difference between pre- and post-operation in the two group was significant (P<0.05), but there was no significant difference between the two groups in the difference between before and after operation (P>0.05). In the plate group, the plate was removed at 11-22 months after operation (mean, 16.8 months). At last follow-up, the AOFAS ankle-hindfoot score in the plate group was 91.2±5.1, which was significantly higher than that in the K-wire group (86.9±6.1) (t=2.316, P=0.027). The ankle function was rated as excellent in 15 feet, good in 4 feet, and fair in 1 foot in the plate group, and excellent in 14 feet and good in 3 feet in the K-wire group, and the difference between the two groups was not significant (Z=1.712, P=0.092). ConclusionFor intra-articular displaced calcaneal fracture in older children, the open reduction and internal fixation with plate and closed reduction and internal fixation with K-wire can achieve good effectiveness, but the former has better recovery of ankle function.