How can you treat a broken hand?

Depends on fracture. Depends on fracture. Treatment can be anywhere from taping; to closed reduction and putting in a splint; to surgery with internal fixation. The treatment options should be discussed with your surgeon. And fyi, there are orthopedic surgeons who just do hand surgery if you are looking for an appropriate physician for consultation and treatment.
Splinting or casting. In the proper position is the single most important ting to treat a hand fracture. Finger and hand joints get stiff quiclky if poorly positioned. The immobilzation must offer a secure afe position that allows healing to ccur without prolonging recovery. Typically this is for a nondisplaced or displaced fracture that can be held stable. For unfixable or unstalbe fractures internal fixaiton is adde.