Freezing procedures applied extensively or to deep regions have become popular in recent years, and so their effect on nasal cartilage adjacent to the oral cavity and on articular cartilage should be considered. The author discusses the clinical application of freezing techniques, after examining rabbits whose auricular cartilage was frozen.
Macroscopic findings were that the edema was the greatest on 3 days, the frozen region was covered with scabs in 1 week, these scabs began to desquamate in 3 weeks, and the frozen region was finally epithelized in 6 weeks, with hypertrophied elastic hardness.
Histologically, the epithelium recovered in 4-6 weeks after freezing. The edema and infiltration of the inflammatory cells were decreasing at 4 weeks, but were still found in some cases in 14 weeks. The cartilage of frozen area was stained less than nonfrozen area 12 hours after freezing, and the perichondrium was swollne before absorption of the cartilage started in 2 weeks.
In the peripheral region, fibroblasts were occasionally found in 1 day. In 5 days the perichondrium was hypertrophied about 2 mm from where the epithelium had become necrotic for freezing. New growth of the cartilage was seen in this region in 1 week. Destruction of the old cartilage and growth of new cartilage continued thereafter, the frozen region almost replaced by new cartilage in 8-14 weeks. The new cartilage was thicker than the old, and was irregular in form.
Growth of new irregular cartilage and destruction of the old was still occuring even in 14 weeks, and this suggests that clinical freezing procedures should be applied carefully to tissues near cartilage.