HI Kingg, welcome to the board. According to the scores you received (determined by the World Health Organization) you have osteoporosis in all areas tested. Do you have any secondary health issues that could be causing the bone loss? Did your dr. discuss your scores and explain them to you? Discuss options? The good thing is that at your young age you have time to make changes that will improve your density. Diet, supplements and exercise help a lot although with your knee problem that part would have to wait. If you live in Europe, or any number of other countries you could try Protelos, strontium citrate, which is a prescription that is not not available in the USA.
The problem with your knee probably isn't a result of the osteo, unless you've experienced a fracture as a result of it. Have you injured you knee in the past? Nine months is a long time to treat pain without knowing the cause. Did they tell you what the problem with your knee was, maybe a torn ACL and not bone related?
Sorry for so many questions, but they help all of us help you. take care...phyllis