Passing a medical doesn’t necessarily mean that he has a clean bill of health. Just means the respective club is willing to risk any issues.
Also I recall Rosenior mentioning Oscar had a longstanding ankle issue I believe which probably isn’t helping when it comes to knee injuries as well
I guess the Bullard saga is evidence of that, but one would have thought if you are paying a 1 million loan fee, and his wages you would make sure.