Your orthopedic surgeon is the best one to advise you on this. Surgery to pin the bone is usually done if the fracture is displaced. This means the two ends of the bone have separated and no longer line up with each other. If there is a great deal of soft tissue injury around the joint, one or two screws are used to hold everything together until healing occurs.
In a growing child, care must be taken to preserve the growth plate. Screws can be placed through this area (sideways) but not across the plate. The screws can be metal (removed later) or bioabsorbable (dissolve and don’t require removal).
Sometimes the decision of how to stabilize the joint is based on how cooperative the child is. Children must keep their weight off the broken ankle for the first seven to 10 days. There is a risk that the bioabsorbable screws can break if loaded before bone growth and repair can take place. If that happens, then a second surgery is required. The dissolvable screws are replaced with metal screws. The cost and risk of problems increases with the second operation.