I have had trouble with my knees for about 8 years now. It's called Deteration of the knee caps, during football practice both of my knee caps poped out of place, ever since that time my knee caps are not correctly inlined with the knee joints. Training is difficult but, it's even more difficult finding a dojo that will train me. to many teachers are afraid now adays in the states to train the disabled. so I have found ways to help myself, streching is #1, there are great supplements on the market that are great for muscle and bone health care, coral calcium is also great, doctors can't really do anything nowadays without taking your life away in some form.