Surgery is needed when the bone fragments of fracture clavicle are piercing the skin or with displaced fracture fragment with more than 1 cm of gap or overriding / shortening more than 1.5cm. Fracture on outer side end of clavicle  are most of the time separated because the  ligaments holding clavicle are injured  and opposing forces acting on either side of the fracture fragment from major neck muscles and weight of arm itself. With surgery the fracture fragments are brought together and held with plate and screws.