Employee was welding on K670 drag, crawling around inside of the drag on his knees. Went to get out of drag and his left knee was sore and hard to bend. Employee never missed any days from work due to this injury. Went to see a Dr and had an MRI on 11/8/2011. Will have surgery on his left knee around December 9, 2011 and will be off 1-4 weeks