| I. INTRODUCTION AND HISTORICAL BACKGROUND
Cartilage gratis have gained increasing popularity in facial plastic surgery. Although in most areas of the face alloplasts are well accepted, their history as nasal grafts has been a problem. Possibly because of thinness of the nasal covering and the susceptibility of the nose to trauma and infections, alloplasts have become inflamed and are extruded in some patients early; in others, many years after implantation. Although the incidence of rejection of alloplasts may not he high, the severity of the reaction in the nose, and the subsequent scarring and tissue distortion has made each of these events a potential clinical disaster.
Host extrusion of cartilage grafts has not been a significant problem. Cartilage homografts are mildly antigenic when implanted in humans. They are generally well accepted by the host and undergo minimal resorption in the early years postimplantation.' There is some concern regarding their 10-year survival.' In comparison, cartilage autografts do not undergo any significant resorption over long periods of time and thus can be considered a permanent replacement graft.
Peer and Dupertius, two of the earlier pioneers of cartilage grafts, demonstrated that cartilage autografts survive as living tissue in the host. They also observed growth of these autografts when used in young hosts, though these results have not been duplicated by others."' Peer implanted septal cartilage autografts in humans. Microscopic studies after 3 years revealed the presence of chondrocytes and no visible evidence of resorption!' He made similar histologic observations on autogenous ear cartilage which had been implanted for 3 years and autogenous rib which had been implanted for 12 years. These studies showed no evidence of cartilage resorption." Gibson and Davis demonstrated that cartilage autografts showed some mild degree of erosion and resorption when the surface of the graft was cut. This process of erosion and resorption was of short duration and was complete within a few weeks of transplantation.
There are several factors which seem important in the survival of cartilage grafts. Infection or the presence of blood in the field increases the tendency for graft resorption." Elimination of a dead space in which blood or fluid accumulates is therefore important. The graft should be handled gently to avoid surface nicks which may increase resorption. Rib autografts have a tendency to warp, which is particularly evident when they are placed over the nasal dorsum.
The problem of warping was examined by Peer who diced cartilage to eliminate warping," however, this produced so much surface area that significant resorption occurred. Gibson and Davis advocated the technique of balanced cross-sectional carving which solved the problem of warping." Although perichondrium does seem to have protective properties, it does not seem necessary for survival and could increase the tendency for the graft to warp." "
It is not necessary for cartilage grafts to be in contact with adjacent cartilage for survival. It has generally been assumed that an adequate covering of soft tissue is important for survival of a cartilage graft. Cartilage autografts, however, seem to survive well under the thin covering of the nasal dorsum. Cartilage autografts are usually encapsulated with fibrous tissue which fixes them to the adjacent tissue, resulting in stabilization of the graft.'" previous page next page>> |
Aesthetics and Aging A New Paradigm
