One-year survival of AlloDerm allogenic dermal graft and fat autograft in lip augmentation

Background: Although many methods for cosmetic lip augmentation are available, none represents an ideal solution. Objective: A quantitative analysis of surgical lip augmentation was undertaken comparing AlloDerm (Lifecell Corp., Branchburg, NJ) allogenic dermal graft and autologous fat injection with autologous fat injection alone. Methods: Horizontal stab incisions were made at the vermilion border in the lateral commissure of the lip. A tunnel connecting the incision was created with a canthal awl by use of blunt dissection along the vermilion border in a submucosal/supraorbicularis muscle plane. AlloDerm grafts were affixed to the end of the awl, pulled through the tunnel, and held in place with interrupted 4-0 chromic sutures. Fat was injected into the lips in a “string-of-pearls” fashion, with approximately 0.5 to 0.8 mL used per pass. Volume measurements were taken at 1 month, 3 months, and 1 year after operation. Results: Mean vermilion show was substantially increased at 1 month after surgery in both groups. At 3 months, mean vermilion show was unchanged in the AlloDerm/fat group but decreased 0.6 mm in the fat-only group. At 12 months, mean vermilion show had decreased 0.2 and 1.0 mm, respectively, for these 2 groups. Measurements of lateral lip projection in the AlloDerm/fat group demonstrated a sustained increase at 3 and 12 months. Conclusions: AlloDerm used with injected autologous fat appeared to result in a long-lasting increase in vermilion show and lateral lip projection. Future studies with quantitative analysis of surgical outcomes can be used to compare various allograft implantation techniques and identify the optimum technique for maximum volume maintenance. (Aesthetic Surg J 2002;22:349-354.)     

Pedunculated synovium grafts in articular cartilage defects in rabbits.

A rabbit model was used to assess the nature of healing tissues in hyaline cartilage defects and to compare the healing in defects treated with pedunculated synovium grafts to those in defects without synovial grafting. Both knees of 28 1-year-old rabbits were operated. A 3 x 2-mm cartilage defect that exposed cancellous bone was created in the non-weight-bearing area of each medial femoral condyle. Each right-knee defect was covered with a pedunculated synovial graft obtained from the same joint, and the left-knee defects were left uncovered as controls. Groups of rabbits were sacrificed at 3, 6, 12, and 24 weeks postsurgery. Sections from each knee were stained with hematoxylin-eosin and safranin O-fast green staining, and were immunohistochemically stained for type II collagen. The healing at each site was histologically scored, and the intensity of staining for type II collagen was graded. At 12 and 24 weeks, statistical comparisons of histological scores revealed significantly more hyaline cartilage tissue in the synovium-grafted defects. At 24 weeks, these same defects showed significantly more type II collagen. Thus, pedunculated synovium transplantation appears to hold promise as a method for repairing hyaline cartilage defects.     

Viability of crushed and diced cartilage grafts: a study in rabbits

OBJECTIVE: To investigate the effects of dicing and different degrees of crushing on cartilage graft viability and outcome in rhinoplasty. METHODS: Cartilage was harvested from both ears of 29 rabbits. For each animal, 6 cartilage pieces were prepared as follows and inserted into the paraspinal subcutaneous tissue: (1) left intact, (2) diced to approximately 1 x 1-mm pieces and then wrapped in oxidized regenerated cellulose, (3) slightly crushed, (4) moderately crushed, (5) significantly crushed, and (6) severely crushed. Animals were killed at 2, 5, and 10 months, and graft specimens were microscopically examined. RESULTS: As crushing intensity rose, cartilage viability decreased and more cartilage tissue was transformed to connective tissue. The intact and slightly crushed grafts showed significant chondrocyte proliferation. This decreased as crushing intensity increased, and the severely crushed and diced cellulose-wrapped grafts exhibited almost no peripheral chondrocyte proliferation. CONCLUSIONS: Slight crushing of a cartilage graft can produce outstanding graft material that forms softer nasal contours and fills defects well. However, severe crushing of cartilage grafts results in extensive necrosis and eventual reduction in graft volume. The use of oxidized regenerated cellulose to wrap diced cartilage grafts also tends to reduce clinical predictability owing to negative effects on cartilage viability and regeneration.     

Repair of the total tympanic membrane perforation: AlloDerm vs temporalis fascia

Objectives: Patients who require surgery for chronic otitis media with perforation and cholesteatoma frequently have scarce residual tympanic membrane or cholesteatoma adherently involving its entire undersurface. These situations prove poor for standard underlay tympanoplasty techniques. A novel technique is described that maximizes healing and minimizes complications of mucosalization and anterior blunting. The results are compared using Alloderm vs temporalis fascia as grafting materials. Fascia is used when available in primary cases, while AlloDerm has proven successful in revision cases or when delayed epithelialization can be expected.Methods: A retrospective review was performed on all otologic cases at a tertiary care public hospital from 1999 to 2003. Fifty-five cases where total reconstruction was required were included in the study. Simple underlay grafting cases were excluded. Data reviewed included preoperative diagnosis, intraoperative findings, grafting material used, surgical technique, postoperative healing, complications. The group of patients who underwent reconstruction using fascia were compared to those who underwent AlloDerm reconstruction.Results: The 2 groups of patients were similar in preoperative diagnosis, intraoperative findings, surgical technique, and postoperative healing. The AlloDerm group had a slightly higher postoperative perforation rate, likely due to pores within the AlloDerm itself. The closure rate in the Alloderm group was still high at 93%. Audiologic data is analyzed.Conclusions: Temporalis fascia and AlloDerm are both safe and highly effective grafting materials in the reconstruction of the total tympanic membrane perforation if used with the described technique.     

Nose and paranasal augmentation: autogenous, fascia, and cartilage

The up-to-date plastic surgeon should consider using augmentation rhinoplasty with relative frequency. In selected cases, for improving the face integrally, it is desirable to augment the paranasal area. In the author's hands, grafts of cartilage and fascia are the preferred tissues, based on the experience of many years. Fascia can be used alone or combined, and in the last few years we have used it alone quite often. A temporoparietal fascia graft has great versatility in the correction of a number of nasal deformities. A depressed nasal dorsum can be augmented by utilizing fascia grafts. A depressed nasal radix can be corrected successfully by utilizing fascia grafts. Submucosal placement of strips of fascia has proved to be an effective method of reconstructing the roof of the middle cartilaginous vault. For augmenting the nasal dorsum when it is a case of primary rhinoplasty, the author prefers the use of fascia alone, but if the patient is having a secondary rhinoplasty, then the graft of fascia and cartilage combined is preferred.     

Effects of human amniotic fluid on cartilage regeneration from free perichondrial grafts in rabbits.

After the chondrogenic potential of free grafts of perichondrium was shown in several experimental studies, perichondrium has been used to reconstruct cartilage tissue in various clinical situations. This study investigates the effects of human amniotic fluid on neochondrogenesis from free perichondrial grafts in a rabbit model. Since this fluid contains high concentrations of hyaluronic acid, hyaluronic acid-stimulating activator, growth factors, and extracellular matrix precursors during the second trimester, it may have a stimulating effect on neochondrogenesis. Perichondrial grafts, measuring 20 x 20 mm2 were obtained from the ears of 144 New Zealand young rabbits and were sutured over the paravertebral muscles. The rabbits were randomly divided into three groups with 48 rabbits per group. In group 1, 0.3 ml human amniotic fluid, and in group 2, 0.3 ml saline were injected underneath the perichondrial grafts. Group 3 formed the control group in which no treatment was given. Histologically, neochondrogenesis was evaluated in terms of cellular form and graft thickness at 2, 4, 6, and 8 weeks after surgery. In group 1, the mature cartilage was generated quickly and the cartilage plate in this group was significantly thick and extensive when compared with groups 2 and 3 at 8 weeks ( p<0.05 ANOVA). In conclusion, our study shows that human amniotic fluid enhances neochondrogenesis from free perichondrial grafts. The rich content of hyaluronic acid and growth factors possibly participate in this result.     

Tissue engineering of trachea-like cartilage grafts by using chondrocyte macroaggregate: experimental study in rabbits

Abstract:  Treatment and management of tracheal defects remain challenges in head and neck surgery. The purposes of this study were to explore a novel strategy to fabricate tissue-engineered trachea by using chondrocyte macroaggregate, and evaluate the feasibility of creating tracheal cartilage equivalents grown in the shape of cylindrical structure without scaffold. Chondrocytes from rabbit cartilage were expanded and seeded into a culture dish at high density to form mechanically stable chondrocyte macroaggregate. Once the chondrocyte macroaggregate was harvested by scrapping technique, it was wrapped around a silicon tube and implanted subcutaneously into the cell donor rabbit. Eight weeks later, specimens were harvested and analyzed for gross appearance, and histological, biochemical, and biomechanical properties. These values were compared with native rabbit cartilage. It was found that expanded chondrocytes could be harvested as a coherent cellular macroaggregate and could be fabricated into a tubelike graft. After in vivo implantation, cartilage-like tissue with cylindrical structure was regenerated successfully. Histological analysis showed engineered trachea cartilage consisted of evenly spaced lacunae embedded in a matrix rich in proteoglycans; type II collagen was also highly expressed in this engineered trachea cartilage. In a conclusion, based on the chondrocyte macroaggregate strategy, tracheal cartilage equivalents with cylindrical shape could be successfully reconstructed. This construct has advantages of high cell-seeding efficiency, good nutritional perfusion, and minimal inflammatory reaction, which provided a highly effective cartilage graft substitute and could be useful in many situations of trachea–cartilage loss encountered in clinical practice.     

Comparison of fresh autogenous with formalin preserved allogeneic bone grafts in rabbits

Summary A complete circumferential gap was produced in the diaphysis of the ulna in rabbits and the radius was left intact. The gap on the right side was filled with formalin preserved allogeneic (FPA) bone graft, and fresh autogenous bone taken from the right ulna was put into the gap on the left side. The gap was left untouched in a control group. Up to 8 weeks, the rate of union was slower in the FPA grafts compared with the autogenous grafts. Maximum fluorescence was seen at 10 to 16 weeks and was the same in both groups. These results indicate that osteoinduction occurs with normal bony repair in 80% of both groups, although the onset of healing is delayed in the FPA grafts.

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Résumé On a déterminé, chez le lapin, une perte de substance circonférentielle ostéo-périostique au niveau de la diaphyse des deux cubitus, tout en laissant intacts les radius. Du côté droit la perte de substance a été comblée par une allogreffe conservée dans la formaline (ACF) et du côté gauche par l'os autologue prélevé sur le cubitus opposé. Dans le groupe de contrôle la perte de substance a été laissée telle quelle. L'ACF a été préparée au froid, dans une solution de formaline à 5% dans du sérum physiologique, à un pH de 6.2–6.4, et utilisée après trois semaines de conservation. Les examens cliniques, radiologiques et histologiques réalisés ont montré qu'au début (jusqu'à la 8ème semaine) la consolidation était plus lente du côté de l'ACF que du côté où avait été placé l'autogreffe. La fluorescence maximale a été observée à la 10ème-16ème semaine et a paru identique dans les deux groupes de greffes. Ces résultats indiquent que l'ostéo-induction survient aussi bien dans les autogreffes que dans les ACF, mais qu'elle débute plus tardivement dans ce dernier cas. Une reconstruction osseuse normale a été constatée dans 80% des cas, alors qu'il n'y a eu aucune consolidation spontanée dans le groupe de contrôle.

     

Comparison of cadaveric pericardial,dermal, vein,and synthetic grafts for tunica albuginea substitution using a rat model

OBJECTIVE: To evaluate in an animal model the intermediate and long-term efficacy of cadaveric pericardium, dermis, vein and Gore-Tex per thousand as grafting materials for tunica albuginea substitution after plaque excision for Peyronie's disease. MATERIALS AND METHODS: The study comprised 100 male Sprague-Dawley rats (300-325 g) divided into five equal groups: group 1, sham-operated controls; and groups 2-5 which underwent wedge excision of the tunica albuginea and replacement with either cadaveric pericardium, dermis, vein or Gore-Tex grafts. Ten rats in each group had the cavernosal nerve stimulated electrically to assess erectile function at 4 months, and the remaining 10 rats at 6 months. After death the sampled tissues were fixed in 10% formalin, paraffin-embedded, and stained with Masson's trichrome and Verhoff's van Giesen for collagen and elastic fibres. RESULTS: Erectile function, assessed by cavernosal nerve stimulation, did not differ significantly in any of the groups (P > 0.05). The histological assessment of penile cross-sections showed minimal fibrosis surrounding the patch in the dermal and vein grafts, and moderate to severe fibrosis in the Gore-Tex graft at 4 and 6 months. In the pericardial graft there was a moderate degree of fibrosis at 4 months with only minimal fibrosis at 6 months. CONCLUSIONS: These results show that cadaveric pericardium allows complete penile expansion and is strong enough to withstand normal intracorporal pressures. There was minimal fibrosis in the pericardial, dermal and vein grafts, and moderate fibrosis in the Gore-Tex graft at 6 months. The pericardial graft is a satisfactory grafting material when used for tunica albuginea substitution, including the surgical management of Peyronie's disease.     

Comparison of angiogenic activities after urethral reconstruction using free grafts in rabbits

OBJECTIVE: To determine the most suitable type of graft-free penile skin grafts or mucosal grafts from bladder or buccal regions - for urethral reconstruction in an animal model, as evaluated on the basis of angiogenic activity. METHODS: Twenty-two male White New Zealand rabbits were randomly divided into four groups. In the control group (group O, n=4) a simple urethrotomy and closure was performed, whereas a ventral urethral defect was created in groups A, B, and C and then bridged using the following onlay patches: free penile skin (group A, n=6), buccal mucosal graft (group B, n=6), and bladder mucosal graft (group C, n=6). On the 21st postoperative day, the animals were sacrificed and the retrieved implants were subjected to macroscopic and microscopic analysis. The angiogenic activity was assessed with immunohistochemistry, using the anti-CD31 MoAb and the phosphatase antialkaline phosphatase procedure. The native vascularity of penile skin as well as buccal and bladder mucosa was assessed in rabbits from group O (n=3). Statistical analysis was performed using the one-way ANOVA. RESULTS: The angiogenesis in a magnification of x200 in groups O, A, B, and C was 34.1+/-4.1 (mean+/-SD), 61.7+/-6.4, 94.3+/-6.4, and 91.5+/-7.2 vessels per optical field, respectively. There were, statistically significant differences (p<0.001) between groups A and B and between groups A and C, but not (p>0.05) between groups B and C. The native vascularity of penile skin, buccal mucosa and bladder mucosa was 23.3+/-3.0, 24.6+/-3.7 and 17.0+/-2.6 vessels per optical field, respectively. CONCLUSION: The viability of mucosal grafts from bladder or buccal regions is better than that of a free penile graft because of higher angiogenic activity. Although the mucosal grafts showed the same angiogenic activity, the buccal mucosa graft is preferable because of its easier harvesting.     

Experimental study on pedicle fat grafts after laminectomy: comparison of pedicle fat and free fat grafts

Scar formation adherent to the dura and nerve roots causes recurrent symptoms following laminectomy. Free and pedicle fat grafts have been performed in low-back surgery as a preventive measure. An experimental study in rats was designed to compare pedicle fat grafts and free fat grafts after wide laminectomy, for efficacy in preventing scar formation and for effects on the spinal cord. The following results were obtained. 1) Dense scar formation over the dura and degeneration of the cord were seen at control laminectomy sites. 2) Free fat grafts, examined at 2 and 4 weeks postoperatively, showed death of portions of the graft, whereas pedicle fat grafts always demonstrated the presence of living fat. 3) At 4 months postoperatively, pedicle fat grafts were statistically superior to free fat grafts, which showed scarring over the dura and degeneration of the cord. In conclusion, pedicle fat grafts were more effective in preventing dural scar formation and protecting the cord than free fat grafts.     

The preparation of small dermal grafts

A fast, simple, and accurate method for preparation of dermal grafts by using the Mini Dermatome for removal of the subdermal fat and the epidermis is presented.     

Influence of hyaluronic acid on wound healing using composite porcine acellular dermal matrix grafts and autologous skin in rabbits

This study aims to explore the influence of hyaluronic acid (HA) on wound healing during xenogeneic porcine acellular dermal matrix (PADM) composite skin grafting. The results will facilitate the development of methods for improving graft contracture and poor elasticity of composite transplantation. Exogenous HA was added to composite PADM grafts and to thin autologous skin grafts during rabbit full‐thickness skin wound repair. The influence of HA on wound healing was evaluated according to its contracture rate and its expression of collagen types I and III. The possible mechanism was then explored based on HA metabolism and vascularisation in the skin graft. The results show that exogenous HA relieves graft contracture on rabbit wound surfaces, increases collagen I and III expression and decreases the ratio between collagen types. HA stimulates the generation of more CD44 receptors to strengthen its enzymolysis. The resulting metabolites promote the vascularisation of the wound surface, which are conducive for mitigating graft contracture, and further improve the composite grafting effect.