Hi, thanks very much for trying to help me. I'll answer your questions as best as I can -
1. Onset, usually gradually, but always after I've had my leg bent while sitting down, and have not been able to move it around very much - for example, sitting in the back seat of a car, or sitting in a lecture theatre.
There is often a 'background discomfort' in the knee. A sort of nagging pain that I can feel but is not particularly bothersome, and I keep it at bay by extending my leg. Sometimes this nagging pain will just dissappear for a while, and sometimes it will develop into this very severe sharp pain.
2. Pain increases sharply over about a ten second duration and then dies away again - usually because I've jumped out of my chair to move it around very quickly! I can't keep it flexed when the pain comes on as it's too painful. It started about two months ago and has been coming progressively more frequently.
3. No. No morning stiffness at all.
4. I can't think of any history of direct trauma. I've danced pretty regularly for the last 4 years, but have stopped in the last year due to time constraints - and there's no pain in my other knee whatsoever.
5.Yes, pain is localised to the knee joint. I have no problems walking, though going down stairs is sometimes painful - and I do feel like the knee feels unstable when walking downstairs. It's almost as if it feels like it's about to 'give way', but never actually does.
No patellar tenderness whatsoever, and no history of other medical condiitons.
Hope that helps - I'm sorry if I haven't given very clear explanations. It's a little hard to describe through writing! Thanks very much for your time and any help you can give me!