I can only tell you what I've read from looking around the internet. There is not alot of information on this but I have been unable to find leg and foot swelling as a normal side effect of this surgery. Pain, of course, is mentioned and infection but not leg swelling.
In this thread http://www.spine-health.com/forum/back-surgery-and-neck-surgery/swollen-feet-and-ankles one person mentions that his doctor sent him immediately to the ER when he experienced swelling because he might have a clot.
Given that I suggest that you contact your physician/hospital immediately and get their opinion on the next step. Good luck!
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