question: I had a TKR about 4 mo. ago. I recovered remarkably well with the ability to bend my knee to 122 degrees within 1 month post surgery. About a month ago I suddenly began hearing a sound like velco ripping open when straightening the knee from a sitting to standing position. I is a little painful when it happens and sometimes, depending on the position of the knee, it hurts badly. I had an appt with my OS today but they called and postponed it. Can you give me an idea what may be causing this?