We had the same problem as well. Had to take a really sound and good moving steer off.
You have to figure out how to get him to exercise. I haven't seen your steer, but I know what Optiflexx did to our steer. I didn't feel that it messed with his joint structure, it just tightened him up. I would compare it to what weight lifting will do to a persons flexibility.
We ended up using an exercise rack that we pulled behind a 4 wheeler and walked him really slow just to stretch him out. It helped, but he never went back to the way he was before.