\s=b\Three hundred forty-two cases of laryngeal cancer were treated at the University of Michigan, Ann Arbor. One hundred ten supraglottic cancers and 150 glottic cancers were studied in depth. Conservation surgery was performed on 63 patients. Determinate two-year disease-free survival for glottic cancer was 90% in those irradiated primarily, 83% for those treated with vertical hemilaryngectomy, and 58% in the group that had total laryngectomy. Supraglottic cancers had a determinate survival rate at two years of 62% for those irradiated primarily, 80% for those treated with a supraglottic laryngectomy, and 62% when total laryngectomy was required. The cost of preserving the respiratory and sphincteric functions of the larynx in some cases amounted to the morbidity associated with a protracted hospital stay, altered deglutition, instances of a weak but functional voice, and the possibility of a permanent tracheostomy. Despite high recurrence rates of 30% to 40%, the overall determinate survival with salvage was an acceptable 80% for the conservation surgery group.

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\s=b\A canine animal model was developed to study the effects of cricoid resection on cricoid cartilage growth and subglottic lumen size. Twenty-four healthy, postweanling mongrel puppies, aged 5 to 7 weeks, were randomly divided into two groups. The first group, consisting of 13 puppies, underwent cricotracheal resection with primary anastomosis. A second group, consisting of 11 puppies, served as controls and did not have surgery. Animals from both groups were killed at age 13 weeks. Most of the animals, however, were allowed to mature to adulthood and were killed between age 26 to 28 weeks. Comparative histologic examinations of the laryngotracheal complexes of operated-on and control dogs showed uninterrupted cartilage growth at the anastomosis site after cricotracheal resection. There was no significant difference in the mean area of the cricoid lumen between the two groups when luminal area was adjusted for body weight.The results demonstrate that cricotracheal resection in this animal model does not interrupt cricoid luminal area or cricoid cartilage growth, and provides rationale for further investigation of cricoid resection with primary anastomosis in humans. Cricotracheal resection in growing puppies appears to be an excellent model for further studies in the surgical treatment of acquired subglottic stenosis in infants and children.

The acute and long-term effects of the anterior cricoid split on the subglottis of puppies intubated from 7 to 14 days are documented. The anterior cricoid split acutely increased the intralumenal cricoid surface area in puppies with intubation-induced airway injury. An intense inflammatory response with mucosal ulceration and granulation tissue is elicited by 14 days of intubation by using the canine model of induced subglottic stenosis developed by Supance et al. [19]. When animals intubated for 14 days underwent an anterior cricoid split on day 7, the airway appears essentially normal by day 14. The split cricoid cartilage maintained a 'U' configuration following the procedure. The region of deficient cartilage anteriorly is bridged by fibrous tissue with normal epithelium lining the lumenal surface. Splitting the cricoid cartilage anteriorly increased the intralumenal area and no long term complications resulted from the procedure. The mechanisms by which the anterior cricoid split expands the airway intralumenal area while maintaining airway support have been reviewed.