Fireboss opened a mandoor and stepped through onto uneven bottom and his weight was posted on his left knee twisting it. Initial x-ray report showed no injury but he was told not to work until he got an MRI that took 12 days to get and 3 more days to get the results. Notified on 6/3/13 that he had sustained an ACL strain with cartilage damage and needed to remain off work.