<s>[INST] i ve had a meniscus cleaning surgery 3 years ago and 2 years after the surgery I started having knee locking. when I try to straighten my leg i feel like an artery or a string is tightened and it hurts. The way i usually unlock it is by sitting down and bending and straightening the knee over and over till it gets unlocked. today its been locked for 12 hours now and i can t unlock it. What is the problem exactly and how can I fix it? [/INST] Hi, Avoid prolonged knee extension that is sitting in same position with your legs outstretched for long hours. As for the locking you can immediately use a hot pack for ten minutes and try to relax your muscles, what you are doing knee bending and straightening sounds perfectly fine. Hope I have answered your question. Let me know if I can assist you further. Shut Have, Physical Therapist or Physiotherapist </s>