INDUCTION IN-VIVO OF CARTILAGE GRAFTS FOR CRANIOFACIAL RECONSTRUCTION

In the craniofacial region, defects of cartilage structures are prefer ably reconstructed with autologous cartilage. Donor-site morbidity rel ated to the creation of a new defect elsewhere, and a lack of growth p otential of the graft-mandatory in children-have stimulated investigat ors to Sind other ways to generate new ''extra'' cartilage. Several bi omaterials have been tested as a matrix for the ingrowth of (peri)chon droblasts in experimental animals. In young (growing) rabbits we have developed a process of heterotopic cartilage induction with the use of a demineralized (bovine) bone matrix which is enfolded in a pedicled flap of ear perichondrium for at least three weeks. During this period the demineralized matrix is colonized by macrophages and polymorphonu clear cells which start a process of complete biodegradation of the ma terial. Simultaneously, the collagen matrix is invaded by mesenchymal cells, originating from the perichondrium and differentiating into cho ndroblasts and Inter, into chondrocytes forming the intel cellular sub stance. The developing, very young cartilage could be demonstrated as collagen type II, thus, hyaline cartilage. When applied with its adher ent perichondrium as a graft it merges easily with the more matured ho st cartilage and even appears to be capable of further growth. Therefo re, it seems suitable for the reconstruction of a cartilaginous defect in growing cartilaginous structures like the nasal septum or the lary nx.