There is a surgery that has been used in a small number of children with this condition. The two bones of the forearm are joined, or fused, together. The two forearms are connected into one bone. The new position of the forearm puts the hand in a position ready for a handshake or with the palm facing slightly downward.
Researchers followed up on six children who had this type of surgery. The surgery enabled the children to be able to use their hand to pick up objects and to hold items. Your niece's doctor can decide if this type of fusion will make a difference and help find a specialist.