It’s families and situations like yours for which a new system was designed. A new, flexible and curved rod system can be inserted down through the bone to hold it in place while it heals. The rod or nail (as surgeons refer to it) is called the Nancy nail.
Once in place this nailing system placed opposing forces on the bone. Such forces reduce or correct the fracture and stabilize or hold in place the entire bone. Sometimes called elastic stable intramedullary nailing or ESIN, this system has been around for the last 20 years.
Ask your surgeon about this method of treatment. There may be some reason why your child wouldn’t qualify but if not, it’s an option worth considering.