I completely battered my collarbone back in the end of March. Impact pretty much exploded the bone, and there was only about 20mm left attached to the shoulder side. Unfortunately, the first hopsital i went to - Stafford - didn't have a clue, and the "Doctor" there said it was all fine and a perfectly uncomplicated break. Sent me home with a couple of co-codamol and a crap sling that didn't fit.
Two days later, I went to my local A&E who immediately threw away the Stafford X-ray and took two more. The doctor there said it was one of the most severe breaks he'd ever seen, said the two bones were nowhere near each other and desperately unlikely to heal on their own. So, of course, he sent me home with a sling and told me to come back in a week.
The next week I returned, and the X-rays showed the bone (sternum side) was now trying to pierce my skin. They operated about three days later, and reassured me by saying that "they hoped it wouldn't pierce the skin in the meantime. If it does, pop in to A&E".
The really short bit left on the shoulder side meant they couldn't pin it, so they had to tie it together with some special string. It's now healed, after a fashion, but my shoulder is in a different position, so I've had alot of neck pain and muscular issues as all the muscles are now doing different jobs. I spent my first few rides struggling with right hand corners, as my new shoulder meant my weight distribution was completely different.
From what I;ve heard/read, though, pinning isn't always the best option. Sometimes the pins/metal cause other problems - with nerves/muscles as others have mentioned - and don't feel that nice. Going by your X_ray, though, those two bones need to be alot nearer together. They look about as far apart as mine were....