Numbness in the top of my foot?

I am 8 months out of a second L5-S1 fusion posterior with rods. I have had a previous anterior L5-S1 fusion that was broken due to a second car accident(first fusions was cause by a car accident). I am feeling better but not fully recovered, that will take a full year from surgery which has been my experience from the first surgery. The question that I have is: I am having numbness on top of my right foot which seemed to happen after sitting in front of the computer to long 60 minutes? Is this cause by a pinched nerve in my back? or just a pinched nerve in my foot? any body experience this before? My E-mail is HastsSB@aol.com Thanks, Jeff