Osteosarcoma is the most common solid tumour of childhood. Chemotherapy has substantially improved survival, but surgical resection remains essential for cure. Limb-salvage surgery is now common and can be done for up to 85% of children with osteosarcoma. The main surgical challenge in children is how to reconstruct the limb after removal of the tumour. Knowledge of probable outcomes, risks, and benefits of each surgical option is essential for comparison of reconstruction with amputation, which is still the safest and most suitable option in some children.