You need to ask your doctor. There are so many variables and each individual is so different anyone could only guess and you might get a wrong answer. I would think if your doctor has said it's OK to take walks it would be OK to walk on the treadmill. I also know that due to my own surgeries running or walking on a hard surface feels like a pounding on the back of my head and starts a pain cycle. I try to stick to short walks on dirt or grass. There are lots of wonderful hiking trails where I live and I try and take advantage of them often. But with the temp outside at 5 degrees today I think a treadmill walk would be a good thing. Remember to ask your doctor first!