About 5 years ago I injured my knee. I was working on some jewelery, dropped a tool, and tried to catch it by closing my knees. I was sitting too close to the working station and I hit my knee on the metal lockers below.
I went to the doctor and got some x-rays taken. It was determined that I had shifted the kneecap but there were no tears or damage to the kneecap. The doctor said that I should stretch the joint regularly and it should feel better within 6 months to a year. I have been doing that for the entire time.
I still feel constant pain, from moderate to severe. Sometimes my knee gives out and most of the time the joint feels weak. There is an almost cold burning sensation on the surface of the knee.
The strange thing is, while I am laying flat on my back and lift my legs straight up, I can only bend my left knee (the good one) slightly over 90* but I can extend my right knee (the bad one) to a 180* angle. I don't know if this is significant.