Ossification of newly generated cartilage from the perichondrium of auricular cartilage grafted in rabbit tympanic bullae.

Abstract

OBJECTIVE: This study was performed to evaluate the histologic changes in the regenerated cartilage in the previously established rabbit tympanic bullae obliteration model. DESIGN: Experimental study. SETTING: Tertiary otolaryngology care centre. METHODS: The histologic sections of grafted cartilage were examined 4 weeks and 2 and 4 months after surgery. MAIN OUTCOME MEASURES: The chondrogenesis and osteogenesis ratios indicated by the cross-sectional area ratios of the newly formed cartilage and bone to the originally grafted cartilage were calculated and compared. RESULTS: Remarkable neochondrogenesis from the perichondrium of grafted auricular cartilage was found shortly after surgery. New cartilage appeared from the preserved perichondrium at the end of 4 weeks. Some areas of rapid division, maturation, and hypertrophy of the chondrocytes in the new cartilage were noted 4 weeks to 2 months after surgery. A process resembling endochondral ossification by replacement of new cartilage with immature woven bone was observed 2 months postoperatively. The remodeling process that substituted the immature woven bone with mature lamellar bone was seen 4 months after grafting. The chondrogenesis and the osteogenesis ratios were significantly different at the ends of 4 weeks and 2 and 4 months (p < .05). CONCLUSION: The histologic changes in the regenerated cartilage in the tympanic bullae are similar to those in the healing process of bone fracture in the ossification process of cartilage and the remodeling process of bone tissue. In the clinical viewpoint, these findings may be potentially useful in the improvement of cartilage obliteration of mastoid cavity during cholesteatoma surgery.