As shown on the previous page in order to heal nonunion bone defects a bone cement needs to be both osteocoductive and osteoinductive.  In order for a material to be osteoconductive, all that is required is a vascularized matrix.  But to be osteoinductive the material must be seeded with cultured cells and treated with growth inducing chemicals or proteins.

    One material that is a promising substate for osteoblast transplantation is the poly (a-hydroxy esters).  These particular polymers are suitable because they hydrolyze into monomers that are nontoxic, and degrade at a constant rate.  With varying processing parameters the pore sizes, and degradation rate can be controlled.  It has been shown that osteoblasts cultured on these types of polymers grow well.  For example in the picture below a rat nonunion defect was treated with PGA scaffold that had osteoblasts seeded onto it.  Controls were made and it was shown that the nonunion defect healed with the polymer tissue composite but not with the controls.

    This is indicative of this  composite material being osteoinductive as this particular defect would not heal otherwise.
 

To learn more about other osteoinductive materials click here

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