Ok well this is a niggling long lasting problem and I DO know I need to go see a physio about it and I DO plan on doing that probably in about 2 weeks when I have some time off work. With that said I'd be interested to hear if anyone has had a similiar injury or has any suggestions about what it might possibly be. For background... about 3 years ago I apparently semi-ruptured my quadriceps. It's a good while back so I can't remember the details exactly but I do remember being in a crutch for about 2 months and having to do physio everyday in order to get my leg to be able to lift of the ground. I also recall a doctor mentioning the words rupture and quadricep but saying that physio therapy was the best course of action. In particular if I lay with my leg stretched out straight it required extreme effort for a number of weeks to lift my leg even an inch of the ground, oh and hurt like hell at night making it extremely difficult to sleep. This happened because I was kicked a number of times in Thai Boxing and then my knee gave in during one session. Then I kept training like a muppet despite the growing sense of something going wrong, and ended up getting kicked hard twice in the exact place in 2 different sessions. I then hobbled around for about 2 weeks until I realised my inability to walk or lift one of my legs was getting worse instead of better. Anyhow, my leg eventually went back to normal (after physio for about 2 months) but I do recall once or twice a few months later when my knee completely gave way at random times almost as if there was no support during training. This was very infrequent but caused me to feel uneasy. Since I started to do BJJ however the issue has reoccured a couple of times and seems to be becoming more frequent. The last two times I found myself experiencing the same things that happened last time when my quadriceps were banjaxed (messed up). Namely a few days later my knee joint would feel very weak and when walking my knee would occasionally 'give way' causing me to sort of semi-fall every few steps. This has happened probably 3 times and has lasted each time for about a week. I am now seemingly back to normal but my knee still feels like something is not right and while I can run around and whatnot I am beginning to feel distinctly uneasy about it. In fact now I think about it when I pivoting on the knee as in doing sharp turns when running- it frequently feels like my knee is not enjoying it. Like I said at the beginning I do realise this is an issue for a physio and I am planning to see one to see what the heck is going on but I'd be interested to hear any similiar experiences and happy endings!!! Also any recommendations for exercises that might help would be good.