1. Because of the presence of massive bone lamellae along the nail tract, it can be stated with assurance that, contrary to former belief, certain metal alloys introduced into bone do not prevent bone formation.
2. The new blood vessels in the connective tissue of the nail tract seem to be an increased blood supply, and, when carried across the fracture site, may be a factor in the better nutrition of the head. This interpretation was first suggested by Engel.
3. The nail causes the development of a fibrous-tissue cavity of considerable size, not unlike a bone cyst, which traverses the head and neck.
4. If the theory of the origin of the pigment granules is correct, the nail in its canal causes trauma to the surrounding spongiosa and bone lamellae.