For the past six weeks I have been experiencing tightness in my right leg. I had a total knee replacement about six years ago. I have had two x-rays and they say everything is fine with the replacement. About once a week, within 30 seconds the leg muscles tighten up around the knee. I have had two instances that the whole leg will tighten up and I can not stand on it. During one of those times we ended up calling a ambulance because the pain was so bad. I have seen two orothepedic doctors, have been trying physical therapy for four weeks, and had another bad attack on Friday. Thank God for the pain pills, one of these spell may last several hours, cannot even lift my leg and need to use a walker. The next day I will be just fine. See the doctor again tomorrow