What is the most common treatment for a clavicle fractures?

Depends: Depends on the location of the fracture, displacement, shortening, etc. However the most common treatment remains, non operative treatment in a sling for a short period and watchful waiting.

Sling: Non-displaced clavicle fractures have a high rate of union, and are usually managed with sling for 6 weeks. Displaced fractures have a reasonable healing rate without surgery, but patients who have the fracture surgically stabilized feel better quicker, and have a quicker return to function. Surgery removes the possibility of healing with deformity, which may affect function.