Hello. my friend broke his collar bone on a snowboarding trip. he wants to know why swelling/inflamation is somtimes good and sometimes bad. ?

Not certain of quest: If his fracture is recent (less than 6 weeks) swelling at this point is normal and part of the natural healing process. It will take him 10-12 weeks for the fracture to heal assuming he doesn't smoke. If the fracture is displaced about 15% can go onto a nonunion so generally recommend xray evaluation by an orthopedist. In this instance i would say swelling is normal unless an older injury.

Movement: Clavicle fractures will feel better with shoulder retraction, rest and ice untill they heal enough to be more stable. Motion will cause the bones to move and thus more inflammation. I suggest ice a few times a day, work on keeping the shoulders pulled back and not trying to do too much. Sometime these fractures require surgery to stabilize. See a shoulder specialist for appropriate options.