An opinion? Clearly lacking in medical knowledge? Or maybe I can read articles, and apply my knowledge as a medical student to make logical inductions?
It's believed Lamela had a vertebral injury due to his torn muscle problems.
It is known Sandro tore his ACL.
Bone heals much faster than cartilage due to its remodeling capacity, and the fact it is vascular while cartilage is not. I have cited a very easy to read link for you should you choose to read up on the matter:
http://www.siumed.edu/~dking2/ssb/skeleton.htm#development
What a shitty manner of interacting with your fellow man it is to cunt someone off and then imply they do not have knowledge on a matter, when in truth it is you who are "clearly lacking" knowledge on said matter? Surely even you can comprehend the degree of deliberate ignorance this suggests?