NASAL RECONSTRUCTION USING AN OSTEOCONDUCTIVE COLLAGEN GEL MATRIX

Background: Congenital malformations, granulomatous diseases, and trau ma can all cause destruction of the nasal structural framework, result ing in functional nasal obstruction and altered facial cosmesis. Curre nt methods of nasal reconstruction include cartilaginous and bony graf ts, Silastic implants, and homograft onlay materials. However, these t echniques have significant functional and cosmetic drawbacks and are n ot risk free. Native, isotonic, neutral-pH, space-filling type I colla gen gels have been shown to mediate total repair of critical-size calv arial defects in a rat model. These bioengineered collagen grafts prov ide a framework for rapid intramembranous ossification and osteoconduc tion of bone from the perimeter of a defect, resulting in total bony c overage. Objective: To evaluate a novel approach to nasal reconstructi on using a major defect of the bony nasal dor sum with a type I collag en gel matrix. Design: Sixteen retired male breeder Sprague-Dawley rat s were divided into control and experimental groups. The nasal bones w ere exposed through a dorsal incision and completely removed with a bo ne-cutting drill to the level of the mucosal membranes of the nasal ve stibule. Defects in the experimental animals were then implanted with 200 mu g of type I collagen gel, with control animals receiving no inl ay. After 6 weeks, the animals were examined with three-dimensional co mputed tomography before necropsy, at which time the defects were phot ographed, measured by planimetry, and sectioned for histologic analysi s. Results: Experimental defects were observed to manifest 100% surfac e area healing with a thin layer of bone using a type I collagen gel o steoconductive implant for nasal reconstruction. Conversely, control a nimals showed only a 5.7% (+/-3.7% SD) healing by area. Histologic sec tions of the collagen gel implant revealed restoration of the anatomy with a thin plate of immature bone spanning the defect in continuity w ith the cartilage of the nasal septum and with apparent preservation o f maxillonasalis suture lines. Conclusions: Native, isotonic, neutral- pH, space-filling collagen gels positively influenced the repair of la rge nasal defects, which showed minimal bone closure in untreated anim als. Their use in this role merits further investigation.