Provided nothing is being done to your knee (i.e. you didn't say where the bone graft was coming from) on the same side, the Knee Walker is a great help especially in rooms like the kitchen where it is a real challenge getting things from the fridge over to the counter when on crutches. (Although I have to say I became quite a pro at stuffing things in the waistband of my sweatpants ... but that didn't work well with things like a gallon of milk
It works on carpeting too, although required a bit more effort to get going .. some even come with a basket on front for add'l space.
Be careful though .. I think I read on here that someone wiped out and needed an additional surgery to fix so you need to be careful and probably shouldn't let your kids near it ... can be pretty fast when you get going
Mine wasn't covered either ... and I think I paid around the same and I kept it for 2 months. I recommend the Turning Leg Caddy ... I know some are a little different and this one was better than the one they had in the local surgical supply store.