When I saw this question I almost thought I might have posted it because I had the exact same issue a month ago. I have Blue Spruce and Maple roots tunneling under the sidewalk and invading my flower beds so I researched this very question. I ended up running the SawsAll right along the edge of sidewalk on both sides of walk. Used my longest wood toothed blade. 8 or 9 inches although I considered ordering a longer one. I know the roots will grow back so I intend to cut them once a month when I give my dog her heartworm pill. (Just to keep track). I'm sure that is more often than necessary but I do NOT want to have to dig up my entire flower bed again to rescue my plants from strangulation.
