What dog have you got and what bones do you intend to grind?
My current dog chomps through fallow rib cages, shoulder blades and will pick the spine and pelvis clean. I don't give him the leg bones anymore as he can now shatter those into long shards. The Vizsla before had everything as she couldn't break the leg bones so just chewed them clean so less risk.
Mincing is easier and cleaner if your dog eats indoors though and I do mince whole chicken carcasses occasionally through a cheap Andrew James kitchen mincer. A bit harder work and messier but I've used a butcher's cleaver or small hand axe to chop up ribs, shoulders, spines quite easily but just time consuming and more mess which is why i pretty much just chop stuff into portion sizes and give them whole outdoors.