17 month old with right clavicle break. took him to an ortho and they are not putting a sling or brace on him. is it known for them to do that? if so why?

A "17 month old" child with a clavicular fracture which is not displaced will heal rapidly, whereas a brace or sling will present a nuisance to the child, with attempts to move the affected side, perhaps aggravating the fracture by displacing it , causing more serious injury. The pain of movement will restrict this process, allowing healing to proceed.

When possible fractures are treated by immobilization with casts or other methods. However, the clavicle doesn’t lend itself to such treatment and experience shows such fractures heal by initially thickening the fractured area as a form of “cast” followed by remodeling to normal size and shape after several months.