Please talk about his injury in context........ It wasn't as simple as "a broken bone". It was a compound, displacement fracture of both lower leg bones. The bones broke through the skin. You have to factor in muscle and tissue damage. Plus resetting a fracture of that magnitude isnt as easy as putting a couple of plates and screws in. There is the possibility of his leg being shorter, bones aligned ever so slightly different etc. etc. There could be significant ramifications to his playing ability. It may cause other injuries. It may not. I am no Dr but those are some possibilities off the top of my head.
It's not as bad as you make it sound. "compound, displacement fracture" just means that it was two bones that broke, and they ripped through the skin. The two bones he broke very often break together. That is a bad break, but still corrected like any other fracture. cast and maybe pin/screw. The only additional problem could be an infection or like you said muscle/tissue damage, but we would have heard already if that was the case. Nothing is 100% but full recovery from this injury has a very good prognosis.
