Since the surgery, every night I have had muscle cramps that have woken me up. I figured out that since I still do not have have a perfect full extension, whenever my body's reflex to stretch: the TKR leg just cramps up. This is very annoying and prevents me from having a good nght of sleep. I have to stretch my leg in a controlled manner to avoid this discomfort, which does not happen when I sleep! My Family Doctor told me to take some calcium/magnesium vitamins to help with this. Not really any good results. But last night, after a day of a sore calf muscle I decided to take 1 Robaxacet before I went to bed with my regular nightly 1 percocet for pain. The Robaxacet has tylenol and a muscle relaxant. This was the best night I have had since the surgery. I do not know if it is the Robaxacet or just luck at this point, but I will try it again tonight to see if I have a repeat. Does anyone else have that problem? And what has your solution been?