I'm sorry to hear this. I hope Erin's suggestions help.
I'm 52 - so lots older, but I was diagnosed with rhuematoid (sp?) arthritis at age 22. It really hasn't progressed to cause the issues it might have caused, so I'm very blessed there. It does cause some issues. It didn't help at all that I then broke my back at age 24. Arthritis loves to settle into formerly broken bones.
I would like to suggest one thing, although this may only help with rhuematoid arthritis, and I know that isn't the kind you have. Do try glucosamine. It REALLY helps me tremendously. I didn't try it until just a couple of years ago. I used nsaids, and that probably really exacerbated the condition, or caused other problems. I had to stop taking the nsaids because of side-effects, but then I found that I had arthritis in joints I didn't even realize I had.
I started taking the glucosamine, and now I feel almost as good as I felt on the nsaids.
I also take some other herbal anti-inflamatories and the like - boswellia, quercetin - actually I take a combo called COX 2 support. It is found in health food stores. Each store has its own label on it, but if you look at the ingredients, I think it is one product sold under all those different labels.
When I over-exert, or for some other reason if the pain gets beyond what the COX 2 support and glucosamine handle, I will take White Willow bark. That is what they make aspirin from, so it is actually in the nsaid family, but it doesn't give me the side effects of the actual nsaid drugs, and I only take it when the pain is worse than normal.
Rhuematoid arthritis is an auto-immune issue, so allergies often play a big role there. I have no idea if that is true with osteoarthritis or not. If your arthritis is exacerbated or caused at least in part by an allergic reaction, finding out what you are allergic to will really help you.
Again, I'm sorry you got this news.
Why is the ligament still a mess after three years? Have they given you some suggestions for helping the heal?