Tracheal reconstruction with perichondrial grafts.

Since 1972 a series of experiments (Skoog, Ohlsén & Sohn, 1972; 1975; Ohlsén, 1976) has been performed to elucidate the potential of perichondrial grafts to generate cartilage. In 1974 Sohn & Ohlsén demonstrated in rabbits that tracheal cartilage could be reconstructed from free perichondrial grafts. As these studies were carried out with an intact tracheal mucosa a series of experiments was conducted in rabbits, and reported in this paper, in which a tracheal section containing two cartiliages and the covering mucous membrane was removed and replaced with a free perichondrial graft taken from the ear. New cartilege formed in all animals. The reconstructed portion of trachea was partly covered by ciliated cells of normal appearance, partly by low epithelium with microvilli. These latter areas were mainly within the central parts of the regenerated mucosa. The use of perichondrial grafts for tracheal reconstruction was also studied in two series of dogs. In four dogs a tracheal section, consisting of two comlete cartilages with the covering mucosa, was completely removed. The circumferential defect was reconstructed by free perichondrial grafats from rib cartilage. They were placed on two fascial flaps which had been raised from the adjacent muscles, rotated into the defect and sutured for complete coverage. Regeneration of cartilage occurred in all dogs, producing a biologic framework. The lining of the reconstructed tracheal section was completely restored by epithelialization from the surrounding mucosa. Low epithelial cells were successively replaced by columnar ciliated cells typical of the respiratory tract. The morphological development of the regenerated epithelium was demonstrated by electron microscopy. The regenerated mucosa exhibited normal function by passing mucus across the reconstructed area. This was recorded by filming at low speed using Cardio-green as indicator. All the animals of this series developed tracheal stenosis within the reconstructed portion. Another experiment was therefore carried out in which four dogs were subjected to the same operative procedure. Postoperatively, however, during the phase of healing, a silicon tube was inserted and left in situ to maintain expansion of the reconstructed portion. By this means stenosis could be prevented with good regeneration of the mucosal lining.