Autologous Grafts

Autologous grafts have been the preferred choice for implants for nasal augmentation and reconstruction for more than a cen-tury.3 Many surgeons prefer to use the patient's own septal cartilage as the implant of choice for nasal reconstruction.4'5 This cartilage is particularly useful for tip support and tip augmentation. However, there is often a problem with availability. Alternative sources of autologous cartilage are the auricle and the rib.

There are essentially two types of cartilage for grafting: morphologic and hyaline. Septal cartilage is an example of morphologic cartilage. It has the advantage of maintaining its shape when transplanted. Rib, or costal, cartilage is an example of hyaline cartilage. Hyaline cartilage has a system of interlocking stresses inherent in its molecular structure. There is a balance of internal elastic forces that resist deforming. The protein core and the glycosamine side chain are responsible for this property. Parallel lines of force run through the periphery of the cartilage and counteract the effects of the internal forces. Once the cartilage block is cut, the stress forces on that side of the cartilage are relieved, but they no longer counteract on the opposite side of the graft. This can result in warping of the implant and can be a disadvantage of its use. A technique can be used to minimize warping by shaving only scant amounts from the periphery of the graft, such that the outer restraining forces are not unfettered.

Unlike bone, little remodeling of cartilage takes place in a normal state. Chondrocytes are not replaced during adult life. The ability of cartilage to regenerate remains questionable.

Cartilage does enjoy some immunologic privilege. Cartilage cells possess antigens of the major H-antigen system. Cartilage grafts are antigenic and feebly immunologic because of the matrix proteoglycan that protects the chondrocyte from the afferent arm of the immune response, thereby preventing attack by immunoglobulins. Thus, there is no immune response or biocompatibility problem. Cartilage grafts, as compared with bone grafts, have been reported to have lower absorption rate and lower metabolic requirements for survival.6 Resorption rates of septal cartilage grafts have been estimated as ranging from 12% to 50%.7 However, resorbed cartilage is often replaced by host fibrous tissue, making resorption clinically undetectable.

AUTOLOGOUS SEPTAL CARTILAGE GRAFTS

Septal cartilage onlay grafts can be used to correct moderate saddle depressions. Sessions and Stallings8 reported only 15% resorption after 1 year's experience with this technique. Gunter and Rohrich9 described an excellent technique of using septal cartilage as a frame graft and inserting autologous cartilage remnants underneath the frame to provide increased dorsal augmentation.

AUTOLOGOUS AURICULAR CARTILAGE GRAFTS

Autologous auricular cartilage grafts can be used when autologous septal cartilage is not available. Auricular cartilage has the disadvantage of requiring the use of a second surgical site. However, incisions can be made in the conchal cavum area with harvesting of the conchal cartilage bowl, which facilitates surgical access and is virtually undetectable when healed. Auricular cartilage can be contoured for use as onlay grafts; its curvature makes it extremely useful for reconstruction of the nasal valve.

In contrast to alloplastic implants, auricular cartilage does not have to be buried deeply in soft tissue. Unlike bone, it does not have to be positioned in direct contact with bone or nasal cartilage. Whether it is advantageous to maintain perichondrium on the surface of the autologous auricular cartilage is debatable. However, it does add a degree of stiffness to the cartilage. As a cautionary note, beyond the age of 45 to 50 years, auricular cartilage becomes more brittle and is easily fractured.

AUTOLOGOUS COSTAL CARTILAGE GRAFTS

Autologous costal cartilage is often used for augmentation of large dorsal nasal defects and for columellar struts. A disadvantage is that it requires a second surgical site and is accompanied by a significant degree of morbidity. Gunter et al.10 pointed out that the value of the rib as a donor site has been limited by difficulties with postoperative cartilage warping. Stabilizing the graft with longitudinal K-wire appears to eliminate warping and provides internal stabilization of the graft.

Excellent results can be obtained with the use of autogenous costal cartilage to reconstruct the nasal dorsum. Partial resorption is thought to be related to trauma. Smaller implants appear to be more vulnerable to absorption than larger implants. Pressure on the cartilage implant due to tight nasal skin or contracting scar did not seem to alter the behavior or increase the graft absorption rate.

AUTOLOGOUS BONE GRAFTS

The use of septal bone grafts has been reported (H. Smith, personal communication, New Haven, CT; 1993). Multiple small pieces of vomer and perpendicular plate were harvested and placed over the dorsum. Segments were 0.75 to 1.0 cm in length and approximately 2 mm in width. Smith reported on 25 cases with excellent results at 4 years follow-up, with no complications noted and no resorption detected.

Iliac crest grafts had frequently been used for nasal reconstruction when osseous material was required. However, this required a second surgical site that was often painful to patients. In addition, iliac bone grafts diminished in size over time and became more susceptible to fracture as the cancellous portion resorbed, leaving a partially collapsed cortex.

In recent years, split calvarium bone grafts have become popular. These grafts are a large source of material for grafting and have the further advantage of providing excellent structural support and a high level of tolerance.11 Although it does require a second surgical site, in contrast to iliac bone grafts, the calvarium bone graft is harvested from the same operative field as the rhinoplasty. Hardesty and Marsh11 demonstrated a difference in resorption between membranous bone such as frontoparietal calvarium and endochondral bone such as iliac crest. Powell and Riley12 reported resorption rates for calvarium bone within a range of 20 to 30%.

Calvarium bone appears to be an excellent choice for subtotal and total nasal defects and a reasonable alternative when sufficient cartilage is not available. However, it is not without drawbacks. These include increased surgical time and complexity, donor site morbidity, difficulty in shaping the graft, graft warpage, and resorption.13

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