The bone is three inches circumference at the joint and one-millimeter circumference at the tip. How might this bone support the front of an animal weighing one-hundred pounds? It runs with its legs below the body (I'm not sure what that's called). Its body structure is comparable to Earth animals such as leopard and mountain lions. It is a quadrupedal predatory animal that actively hunts prey. It must be able to run quickly. It hunts by chasing down prey, then jumping onto them and piercing the prey's hide with its feet spikes. If there are no possibilities of an animal running on such spikes I can always turn to the bipedal running idea. I have put a reference below.
The bone shaded in blue is a fusion of the phalanx and metacarpus bones.
This image used above is a poorly edited maned wolf skeleton (I suck at drawing complex anatomy)