Substitution of the wall of the trachea by absorbable synthetic material

Synthetic, absorbable tissue proved to supply a valuable "interim support" for an orderly reconstruction of the wall of the trachea during the first three months following surgery. This is in general the result of experiments in which the use of implanted Polyglactin 910 as a substitute material for the tracheal wall of rats and rabbits was tested. Additionally the possibilities for satisfactory stabilization of the tracheal wall by means of Polydioxanon, another synthetic substance, which is absorbed more slowly, were investigated. The experiments were performed in a total of 30 rats and 70 rabbits. Initial attempts to substitute the entire circumference of the tracheal wall in the area of the neck by synthetics resulted in excessive difficulties post-surgically. Frequently substantial stenoses, obstructing respiration, developed. Consequently, patches of substitute material, covering more than half of the circumference of the trachea, were applied. The periods of survival of the animals ranged from one to 23 weeks. Following autopsy and macroscopical inspection, selected specimens were examined histologically by means of light microscopes and scanning electron microscopes. Evaluation of the samples showed progressive lining of the inner surface of the prosthetic patches with connective tissue and subsequent covering with squamous cell epithelium. On the average, approximately six weeks after surgery, ciliated columnar epithelium resembling normal respiratory mucosa developed. Gradually the synthetic fabric was replaced by dense connective tissue, which finally contained newly generated hyaline cartilage also. The very slow rate of dissolution of the polydioxanone material provided sufficient time for the formation of a new, stratified wall of the trachea, maintaining sufficient clearance in the tracheal lumen.