Objective To investigate the short-term effectiveness of transverse antecubital incision in the treatment of failed closed reduction of Gartland type Ⅲ supracondylar humeral fractures (SHFs) in children. Methods Between July 2020 and April 2022, 20 children with Gartland type Ⅲ SHFs who failed in closed reduction were treated with internal and external condylar crossing Kirschner wire fixation through transverse antecubital incision. There were 9 boys and 11 girls with an average age of 3.1 years (range, 1.1-6.0 years). The causes of injuries were fall in 12 cases and fall from height in 8 cases. The time from admission to operation ranged from 7 to 18 hours, with an average of 12.4 hours. The healing of the incision and the occurrence of complications such as nerve injury and cubitus varus were observed after operation; the elbow flexion and extension range of motion after removing the gypsum, after removing the Kirschner wire, and at last follow-up were recorded and compared, as well as the elbow flexion and extension and forearm rotation range of motion at last follow-up between healthy and affected sides; the Baumann angle was measured on the X-ray film, and the fracture healing was observed. At last follow-up, the effectiveness was evaluated according to the Flynn elbow function evaluation criteria. ResultsAll incisions healed by first intention, and there was no skin necrosis, scar contracture, ulnar nerve injury, and cubitus varus. Postoperative pain occurred in the radial-dorsal thumb in 2 cases. The gypsum was removed and elbow flexion and extension exercises were started at 2-4 weeks (mean, 2.7 weeks) after operation, and the Kirschner wire was removed at 4-5 weeks (mean, 4.3 weeks). All the 20 patients were followed up 6-16 months, with an average of 12.4 months. The fracture healing time was 4-5 weeks, with an average of 4.5 weeks, and there was no complication such as delayed healing and myositis ossificans. The flexion and extension range of motion of the elbow joint gradually improved after operation, and there were significant differences between the time after removing the gypsum, after removing the Kirschner wire, and at last follow-up (P<0.017). There was no significant difference in the flexion and extension of the elbow joint and the forearm rotation range of motion between the healthy and affected sides at last follow-up (P>0.05). There was no significant difference in Baumann angle between the time of immediate after operation, after removing the Kirschner wire, and at last follow-up (P>0.05). According to Flynn elbow function evaluation standard, 16 cases were excellent and 4 cases were good, the excellent and good rate was 100%. Conclusion The treatment of Gartland type Ⅲ SHFs in children with failed closed reduction by internal and external condylar crossing Kirschner wire fixation through transverse antecubital incision has the advantages of complete soft tissue hinge behind the fracture for easy reduction and wire fixation, small incision, less complications, fast fracture healing, early functional recovery, reliable reduction and fixation, and can obtain satisfactory results.