release. This started happening while I was in the hospital. I would get a chill and shiver. My knees would tighten up and then release. Well, one day, I got a chill, my knees tightened up but wouldn't release. This makes walking difficult and painful. I am still faithfully doing my exercises, and icing, but there is no change. Is there anything else I could be doing to help my muscles to release? The doctor said that the implants are perfectly aligned.