Fifty-six patients with developmental dysplasia of the hip were randomized to receive surgical treatment first simulated with either a 3D printed pelvic model or a 3D computed tomography generated pelvic model. The outcomes of interest included success rate, incidence of re-dislocation, operative time, length of stay, adverse events, limb and pelvic coordination scores, Majeed function scores and patient satisfaction scores, assessed 24 months post-operation. Results revealed significantly favourable success rate, length of stay, re-dislocation rate, patient satisfaction and operative time in the 3D printed group compared to the 3D computed tomography group. No significant differences in adverse events, Majeed function scores, or upper and lower limb coordination scores were observed between the two groups.