Removing a cam roller from 72"" structure turned body to lay roller on ground, right knee hurt. Testing shows osteoarthritic changes, medial joint narrowing. EE was taken to ER on 4/30/19 released back to work, went to another ER & hasn't worked since 4/30/19. Prior knee Sx. Ask this be deemed an occ. Ill. not lost days due to no single event caused pain, history of knee problems.