Wound healing of cartilage structures in the head and neck region.

This study was performed to determine the various processes involved in the behaviour of hyaline cartilage during the wound healing period after trauma or surgery of vulnerable structures like the nasal septal cartilage and the cricoid. The results of different procedures (perpendicular and parallel to the cartilage surface) in young and young-adult animals were analyzed: septal incision at different locations (young-old), cricoid split (young-old), suturing cartilage, closing defects with autologous cartilage (young), biomaterials (young) and newly engineered cartilage in 4- and 24-week-old rabbits (series of ten animals). Cartilage of the young rabbit and child have similar hyaline cartilage with a varying distribution in thickness. Thinner areas are more susceptible to malformations. Incisions through younger cartilage give rise to some new cartilage formation covered by a new layer of perichondrium: through older, differentiated cartilage the incision causes superficial but permanent necrosis. Edges of cut cartilage mostly do heal by formation of fibrous junctions. This forms a weak spot, sensitive to deviations. The same fate goes for the healing between the autologous graft and the surrounding pre-existent cartilage. Trauma parallel to the surface, leads to inconsistent quantity of neocartilage. With ageing the wound healing and regenerative capacities decrease. In general, biomaterials are less accepted by the surrounding tissues and would impede further growth. Only newly engineered, and thus less differentiated (younger) cartilage of hyaline nature, appeared to be well accepted at the interface with the edges of a cartilage defect. There are indications that the release of growth factors might play a role in cartilage wound healing. In the child as well as the adult, wound healing of hyaline cartilage structures is incomplete, and surgery remains 'experimental' surgery. The clinical implications of gradual loss of the regenerative capacity of hyaline cartilage should be further investigated.