I had ACL reconstruction last July 2011 along with meniscus tear repair this was my 2nd ACL repair on this knee and 4th meniscus tear on same knee - when getting off couch a few minutes ago I could not straighten my leg and have severe pain behind the knee?
Hi, I feel that the ACL reconstruction was done good but the only thing lacking here is the elasticity of the muscles around the knee. Since the muscles are not flexible it is leading to locking of the knee. I would advise you to look forward with two simple exercises.  One is walking reverse and second is using a rocket bottom board for proprioceptive neuromuscular stimulation for the internal structures of the knee. Hope this should help to avoid locking of the knee. Hope I have answered your query. Let me know if I can assist you further. Jay In Chat Doctor.