The pathology for broken collar bones was changing right as I took up mountain biking, and subsequently shattered my collarbone.<p>It was hotly debated at the hospital, if my specific case should be operated on or not. Each time I had a checkup, one doctor would say "wait and see" while the other was saying "I can't believe we didn't operate on this".<p>At any rate, the outcome was as good as if they had operated on it, according to the doc anyway. Nice of them to test it out on me!<p>More related to this though, I have broken both my collarbones, the first time I had little direction and just held my arm still for 2-3 months. It took forever to heal, and my arm atrophied significantly. The second time, similar severity. I was guided through rehab and I was back using my arm within the first month, very little atrophy.