EFFICACY OF PERICHONDRIUM AND A TRABECULAR DEMINERALIZED BONE-MATRIX FOR GENERATING CARTILAGE

A pedicled auricular perichondrial flap wrapped around trabecular demi neralized bovine bone matrix can generate an autologous cartilage graf t. In earlier experimental studies, it was demonstrated that this graf t could be used for nasal and cricoid reconstruction. It was assumed t hat the vascularization of the perichondrial flap was obligatory, but it was never proven that the flap should be pedicled. Moreover, for cl inical use, the dimensions of the auricle would set restrictions to th e size of the graft generated. Therefore, the possibility to generate cartilage with a composite graft of a fi ee perichondrial nap wrapped around demineralized bovine bone matrix, by using young New Zealand Wh ite rabbits, was studied. This composite graft was implanted at poorly (subcutaneously in the abdominal wall; n = 12), fairly (subcutaneousl y in the pinna; n = 12),and well-vascularized sites (quadriceps muscle ; n = 12). As a control, trabecular demineralized bovine bone matrix w as implanted without perichondrial cover. Half of these grafts (n = 6) were harvested after 3 weeks, and the remaining grafts (n = 6) after 6 weeks of implantation. In histologic sections of these grafts, the i ncidence of cartilage formation was scored. Furthermore, the amount of newly formed cartilage was calculated by computerized histomorphometr y. Trabecular demineralized bovine bone matrix without perichondrial c over demonstrated early resorption; no cartilage or bone was formed. I n demineralized bovine bone matrix wrapped in perichondrium, early car tilage formed after 3 weeks at well- and fairly vascularized sites. No cartilage could be detected in grafts placed at a poorly vascularized site after 3 weeks; minimal cartilage formed after 6 weeks. In summar y, the highest incidence of cartilage formed when trabecular demineral ized bovine bone matrix was wrapped either in a pedicled auricular per ichondrial flap or in a fi ee perichondrial flap, which was placed at a well-vascularized site. Second, a significantly higher percentage of the total area of the graft was cartilaginized at well-vascularized s ites after 3 weeks. The newly generated cartilage contained collagen t ype II and proteoglycans with hyaluronic acid binding regions, n;her e as collagen type I was absent, indicating the presence of hyaline cart ilage. This study demonstrates that new cartilage suitable for a graft can be generated by free perichondrial naps, provided that the site e lf implantation is well vascularized. Consequently, the size of such a graft is no longer limited to the dimensions of the auricle.