My tibia didn't want to heal. I don't smoke, but did have a thing for soft drinks (phosphoric acid doesn't help at all with bone healing and calcium retention). I was also probably WAY too active, so the two broken ends were never very stable against each other even though there's a stick of titanium in there now.
Have you tried any kind of ultrasound to stimulate bone growth?
Oddly enough, they feature the pic of a motorcycle rider on the page...