"Broken arms are routinely treated with surgery, but a randomized trial has found that many breaks can be allowed to heal on their own.
Researchers studied 231 patients admitted to British hospitals for displaced fractures of the
humerus, the bone that connects shoulder to elbow. A displaced fracture is one in which the bone is separated and out of its normal position.
The researchers randomly assigned 114 to surgery and 117 to simply immobilizing the arm in a sling. The study,
published in JAMA, followed patients for the next two years, examining them at regular intervals.
Over all, the surgical and nonsurgical groups had similar outcomes, with no difference on measures of pain and comfort. But heart, respiratory and other complications were more common in the surgery group"
http://well.blogs.nytimes.com/2015/03/13/letting-a-broken-arm-heal-without-surgery/?ref=health&_r=1