Paediatric orthopaedic surgery can be an unfamiliar and challenging field with the potential for devastating consequences. This article discusses late deformity associated with humeral supracondylar fractures and slipped capital femoral epiphysis (SCFE). Common complications include loss of fixation, mal-reduction, avascular necrosis and growth disturbance. Many cases result in reoperation and revision surgery associated with significant morbidity. We discuss the risk factors, aetiology, tips to avoid them and management options based on current evidence.