I think you have some good advice about getting assistance above. The one thing to really bear in mind is that all of us, when flying, tend to some foot / leg / knee actions which are a bit unusual, in terms of twisting around seats or shuffling around the WC. That sort of injury needs rest plus exercise to strengthen the area around the knee and lower / upper legs without inflaming the meniscus itself.So he / you need to be careful to think through actions, and slow down so you he can think it through. Rushing around is bad news, and watch out for the swinging back pack!