A few years ago, one of our fatteners had osteochondritis dissecans, though it was a short lived problem in the sense that we only saw him going through his legs on two different days and both days the problem lasted only for a few hours. Around the same time, someone else did mention they'd seen one of our weaners not walking well once (when we weren't present), which presumably was the same weaner with the same problem.
The first day it happened, it looked similar to the way it does if someone stands behind you and pushes their knees into the back of your knees and you drop a bit. He just dropped through his knees a bit every now and then whilst walking. It didn't stop him playing.
The second day, he squeeled as well when it happened and he completely fell through his legs and dragged his backside over the ground for a few yards. That was in the evening and he was fine by morning. It was the last time we saw it, and everything was fine afterwards. He went for slaughter a month or two later without any further issues.