By use of the spongiosa test it is possible to determine the suitability for transplantation of different types of bone grafts. The differences between autografts, homografts, and heterografts are fundamental, both in the manner in which they are incorporated and replaced and in the time required for this process. Autografts regenerate from their own power; homografts are dependent on the osteogenetic power of the host; and heterografts for the most part are enveloped for some time by connective tissue and consequently act, to a considerable extent, as a foreign body in relation to the host.

In the spongiosa test, the site which has the strongest regenerating powers, the spongiosa, acts as the host. It is able to replace each of the different types of graft by its own osteogenetic potency. The time required for replacement by homografts is twice as much as that required by autografts, that required by heterografts is three times as much. Homografts thus have considerable versatility, sometimes resembling autografts and sometimes heterografts.

The devitalization of autogenous grafts inhibits their incorporation, while devitalization of homogenous grafts may further the process of incorporation.

Macerated grafts also show a protein-bound intolerance. Grafts consisting of inorganic substance—that is, freed from protein—definitely favor callus formation.