I searched medhelp, wrong diagnosis and about.com for "major knee injuries" or "common soccer knee injuries" but they were all just lists. I did gather that probably the most severe would be a torn ACL or MCL, but they didn't really describe the pain or whether or not it would cause limping.
I'm trying to weave in symbols from greek mythology, most of all Orion and the Pleiades. Near the end of the story I would like him to be blinded (but not disfigured). Can normal assault and battery cause blindness? Once again I searched medhelp, wrongdiagnosis and about.com, as well as wikipedia for "causes of blindness". Most of them were degenerative or lifelong damage. I've read about tortures involving forcing the victim to stare at the sun, but this is supposed to be a fast, attacked in an alley type thing.
I also searched the little details archive for eye injuries and soccer injuries.