Hi, Thanks for writing in to us. The knee is a joint comprising bones, ligaments and menisci. It is held in position by the ligaments which do not allow the knee to get imbalanced. You might have injured any of the ligaments during your knee twist. Most of the time small ligament partial tears go unnoticed and not very painful. If you have been doing karate classes regularly, there is every possibility that the ligament injury if present might have increased further. Right now you should consult an orthopedician and confirm any possible ligament injury by clinical examination. He will give you necessary treatment with anti inflammatory medications. Hope this helps