Hi- A lot of customers at the small pet store I work at use the Primal Raw Meaty Bones (they are beef marrow bones) and we have yet to have an issue. Perhaps trying the beef would be better. Them splintering like that is definitely concerning and I would not try to feed that bone again.
As for her arthritis, make sure she has comfortable things to lay on and I would definitely suggest a supplement like this one: http://www.chewy.com/dog/naturvet-arthrisoothe-gold-hip-joint/dp/48764
Also is she still getting excersized? Its kinda like how they tell humans that they need to continue to excersize to keep their joints from stiffening when they get older. I think continueing regular excersize for older dogs is a good idea to keep the joints mobile. Obviously only do what she can handle, but it should help. Was she a rescue? She seems young even for a pit to be having arthritis.
