No abstract

The use of implantable biomaterials has become an integral part of aesthetic and reconstructive surgery of the face. Metals are used for fracture fixation devices, whereas polymers are used primarily for bone or soft-tissue substitution. This review of the scientific literature examines the risks and complications of these materials. First, we present an overview of commonly used materials. Second, we address general considerations of toxicity relevant to all biomaterials. Third, we present data from a large number of clinical series on the incidence of complications for individual materials used in specific applications.

No abstract

These studies investigated the utility of calcium alginate as a biocompatible polymer matrix within which large numbers of chondrocytes could be held successfully in a three-dimensional structure and implanted. Further, the ability of chondrocyte-calcium alginate constructs to engraft and generate new cartilage was examined. Chondrocytes isolated from calf shoulders were mixed with a 1.5% sodium alginate solution to generate cell suspensions with densities of 0, 1.0, 5.0, and 10.0 x 10(6) chondrocytes/ml. The cell suspensions were gelled to create disks that were placed in subcutaneous pockets on the dorsums of nude mice. The alginate concentration and CaCl2 concentration used to make the disks also were varied. A total of 20 mice were implanted with 67 bovine chondrocyte-calcium alginate constructs. Samples with an initial cellular density of at least 5.0 x 10(6) chondrocytes/ml demonstrated gross cartilage formation 12 weeks after implantation. Cartilage formation was observed microscopically in specimens with a cellular density as low as 1.0 x 10(6) chondrocytes/ml. The histoarchitecture of the new cartilage closely resembled that of native cartilage. Cartilage formation was independent of CaCl2 concentration (15 to 100 mM) or alginate concentration (0.5% to 4.0%) used in gel polymerization.

These results suggest that the skeletal morphology of the face changes with age. This change in skeletal morphology may contribute to the appearance of the aging face.

The purpose of this study was to demonstrate the feasibility of using a fibrin glue polymer to produce injectable tissue-engineered cartilage and to determine the optimal fibrinogen and chondrocyte concentrations required to produce solid, homogeneous cartilage. The most favorable fibrinogen concentration was determined by measuring the rate of degradation of fibrin glue using varying concentrations of purified porcine fibrinogen. The fibrinogen was mixed with thrombin (50 U/cc in 40 mM calcium chloride) to produce fibrin glue. Swine chondrocytes were then suspended in the fibrinogen before the addition of thrombin. The chondrocyte/polymer constructs were injected into the subcutaneous tissue of nude mice using chondrocyte concentrations of 10, 25, and 40 million chondrocytes/cc of polymer (0.4-cc injections). At 6 and 12 weeks, the neocartilage was harvested and analyzed by histology, mass, glycosaminoglycan content, DNA content, and collagen type II content. Control groups consisted of nude mice injected with fibrin glue alone (without chondrocytes) and a separate group injected with chondrocytes suspended in saline only (40 million cells/cc in saline; 0.4-cc injections). The fibrinogen concentration with the most favorable rate of degradation was 80 mg/cc. Histologic analysis of the neocartilage showed solid, homogeneous cartilage when using 40 million chondrocytes/cc, both at 6 and 12 weeks. The 10 and 25 million chondrocytes/cc samples showed areas of cartilage separated by areas of remnant fibrin glue. The mass of the samples ranged from 0.07 to 0.12 g at 6 weeks and decreased only slightly by week 12. The glycosaminoglycan content ranged from 2.3 to 9.4 percent for all samples; normal cartilage controls had a content of 7.0 percent. DNA content ranged from 0.63 to 1.4 percent for all samples, with normal pig cartilage having a mean DNA content of 0.285 percent. The samples of fibrin glue alone produced no cartilage, and the chondrocytes alone produced neocartilage samples with a significantly smaller mass (0.47 g at 6 weeks and 0.46 g at 12 weeks) when compared with all samples produced from chondrocytes suspended in fibrin glue (p < 0.03). Gel electrophoreses demonstrated the presence of type II collagen in all sample groups. This study demonstrates that fibrin glue is a suitable polymer for the formation of injectable tissue-engineered cartilage in the nude mouse model. Forty million chondrocytes per cc yielded the best quality cartilage at 6 and 12 weeks when analyzed by histology and content of DNA, glycosaminoglycan, and type II collagen.

A retrospective review of clinical outcomes was performed to determine the clinical utility and morbidity associated with the use of porous polyethylene facial implants. Three hundred seventy implants were placed in 162 consecutive patients, in 178 operations performed in 11 years. The number of patients, the number of implants used, and the average follow-up period were categorized according to the cause of the deformity. The resultant distribution was as follows: acquired (tumor-related), 17 patients, 39 implants, and 30 months; congenital, eight patients, 31 implants, and 92 months; aesthetic, 39 patients, 97 implants, and 24 months; secondary posttraumatic, 48 patients, 139 implants, and 37 months; and acute trauma (internal orbit reconstruction), 50 patients, 64 implants, and 9 months. The distribution of implants according to location was as follows: frontal, 21; temporal, 30; internal orbit, 145; infraorbital rim, 28; malar, 58; paranasal, 29; nasal, 13; mandible, 24; and chin, 22. The combined average follow-up period per patient was 27 months (range, immediate postoperative period to 11 years). All implants were placed in the subperiosteal plane, and the majority were fixed with titanium screws. Antibiotics were administered perioperatively. No implants were extruded or migrated, formed clinically apparent capsules, or caused symptoms attributable to bioincompatibility. The overall reoperation rate was 10 percent (n = 16), which included operations to remove implants because of acute infections (2 percent, n = 3) or a late infection (1 percent, n = 1), to remove implants causing displeasing contours (2 percent, n = 3), and to improve contours (6 percent, n = 9). Porous polyethylene implants have biomaterial properties favorable for facial skeletal augmentation. Screw application of the implants to the skeleton allows precise predictable contouring, thus limiting the need for revisional surgical procedures.

No abstract