EE stated that as he was dismounting a D-11 Cat Dozer his knee locked up and made a popping sound. EE finished shift then went to his family DR where X-Rays were Negative. EE returned to Dr. and an MRI revealed some torn cartlidge. EE's first day off work will be 07/05/10 as the mines were shut down from 06/26/10 thru 07/05/10 due to vacation.