What to do if i have a broken wrist it is swollen when will i know if i need a cast?

Fractured wrist: Can be a hairline injury that nay only need a splint to a more complex injury. How do you know . Well short if completing a residency in orthopedic surgery or a fellowship in hand or a related field .... You won't .... But swelling is a sign if an injury the presence or absence of it does not affect typical decisions to cast or not unless u are talking about delaying a cast for it.