Introduction <p>Proximal femoral osteotomy (PFO) with locking compression plates (LCPs) is effective for treating developmental dysplasia of the hip (DDH) in children. However, plate insertion or removal has a risk of postoperative femoral fractures. The goal of this study was to identify and analyse the association between postoperative femoral fractures after PFO and potential risk factors for these fractures.</p> Methods <p>Six patients with DDH and postoperative femoral fractures were retrospectively reviewed at our hospital from June 2014 to October 2020. There were 2 boys and 4 girls whose ages ranged from 2 to 8 years (mean 3 years and 8 months). The timing, circumstances, fracture location, and refixation method were recorded for all patients. Four patients sustained fractures after plate removal: 3 after a fall and 1 spontaneously. Moreover, 2 patients experienced fractures early postoperatively after open reduction and PFO. The mean follow-up time was 31.6 months (25–57 months).</p> Results <p>After 153 patients underwent open reduction and PFO at our institution, six (3.9%) experienced postoperative femoral fractures. In children who underwent implant removal, all fractures (n = 4/4) occurred at the osteotomy site, whereas in those with retained implants (<i>n</i> = 1/2), fractures occurred at the screw hole. Three fractures were treated with reduction under general anaesthesia and spica casting, and three were treated with ESIN.</p> Conclusions <p>Injuries from PFO, prolonged immobilization, or LCPs can result in postoperative femoral fractures in children with DDH. After PFO, the implants should be removed when solid union is achieved at the osteotomy site. Moreover, high-intensity activity should not be permitted until moderate or extensive remodelling at the osteotomy site is confirmed after plate removal. </p>