Prefabrication of mucosa-lined flaps: a preliminary study in the pig model

One-Step Laryngotracheal Reconstruction With Prefabricated Corticoperiosteal Flap

Large airway reconstruction is difficult and requires a flap that will mirror the tissue variety. The main challenge is to keep the reconstruction stable and prevent collapse. In this report, we present a laryngotracheal reconstruction with a buccal mucosa-prefabricated medial femoral condyle free flap, after chondroma excision in a 1-step procedure. Functional results are promising and were confirmed by endoscopy and computed tomography examination 12 months postoperatively. This reconstruction-with-prefabrication technique, among others, may be used in the reconstruction of different regions like craniofacial bone defects, apart from larynx and trachea.

Juvenile Swine Surgical Alveolar Cleft Model to Test Novel Autologous Stem Cell Therapies

Reconstruction of craniofacial congenital bone defects has historically relied on autologous bone grafts. Engineered bone using mesenchymal stem cells from the umbilical cord on electrospun nanomicrofiber scaffolds offers an alternative to current treatments. This preclinical study presents the development of a juvenile swine model with a surgically created maxillary cleft defect for future testing of tissue-engineered implants for bone generation. Five-week-old pigs (n=6) underwent surgically created maxillary (alveolar) defects to determine critical-sized defect and the quality of treatment outcomes with rib, iliac crest cancellous bone, and tissue-engineered scaffolds. Pigs were sacrificed at 1 month. Computed tomography scans were obtained at days 0 and 30, at the time of euthanasia. Histological evaluation was performed on newly formed bone within the surgical defect. A 1 cm surgically created defect healed with no treatment, the 2 cm defect did not heal. A subsequently created 1.7 cm defect, physiologically similar to a congenitally occurring alveolar cleft in humans, from the central incisor to the canine, similarly did not heal. Rib graft treatment did not incorporate into adjacent normal bone; cancellous bone and the tissue-engineered graft healed the critical-sized defect. This work establishes a juvenile swine alveolar cleft model with critical-sized defect approaching 1.7 cm. Both cancellous bone and tissue engineered graft generated bridging bone formation in the surgically created alveolar cleft defect.

The pig as an experimental model for clinical craniofacial research

The pig represents a useful, large experimental model for biomedical research. Recently, it has been used in different areas of biomedical research. The aim of this study was to review the basic anatomical structures of the head region in the pig in relation to their use in current research. Attention was focused on the areas that are frequently affected by pathological processes in humans: the oral cavity with teeth, salivary gland, orbit, nasal cavity and paranasal sinuses, maxilla, mandible and temporomandibular joint. Not all of the structures have an equal morphology in the pig and human, and these morphological dissimilarities must be taken into account before choosing the pig as an experimental model for regenerative medicine.

Reconstruction of the premaxilla: an option for mutilated bilateral clefts

The loss of the maxilla is a severe mutilation resulting from inadequate surgery of bilateral clefts of the lip and palate. It is usually associated with palatal fistulae, collapse of the maxillary segments, and limited facial growth.Functional rehabilitation can be achieved by reconstruction of the premaxilla with osteomucosal fibula grafts. Mucosal grafts are fixed to the fibula in a preliminary stage. The composite graft is transplanted to the maxilla 10 to 12 weeks later. Osteointegrated implants are placed 3 months later.The procedure was used in 7 patients, 1 holoprosencephaly and 6 with sequelae of bilateral clefts; mean age, 17.28 years, with a follow-up of 14 to 70 months.The mucosal grafts integrated successfully to the fibula in all the patients. The osteocutaneous graft achieved a solid maxillary arch in all the patients. Normal mastication was achieved with a prosthesis fixed to the osteointegrated implants. Facial proportions were greatly improved.

Complex nasal reconstruction

LEARNING OBJECTIVES

After studying this article, the participant should be able to: 1. Describe the goals of nasal reconstruction as they apply to extensive, complex defects that may also involve the adjacent lip or cheeks. 2. Understand the advantages and disadvantages of different options for reconstruction of lining, skeletal support, and skin cover. 3. Discuss current advances in complex nasal reconstruction, including microvascular reconstruction of lining and the three-stage forehead flap. 4. Understand the concepts of laminated and prelaminated flaps and their application in complex nasal defects.

SUMMARY

In this article, the authors review methods of reconstructing complex, multilayered nasal defects that may involve surrounding central facial structures. Different means of lining, skeletal support, and skin cover reconstruction are discussed. Emphasis is placed on newer, state-of-the art techniques and reinforcing basic principles.

Effects of subepithelial fibroblasts on epithelial differentiation in human skin and oral mucosa: heterotypically recombined organotypic culture model

The stratified squamous epithelia differ regionally in their patterns of morphogenesis and differentiation. Although some reports suggested that the adult epithelial phenotype is an intrinsic property of the epithelium, there is increasing evidence that subepithelial connective tissue can modify the phenotypic expression of the epithelium. The aim of this study was to elucidate whether the differentiation of cutaneous and oral epithelia is influenced by underlying mesenchymal tissues. Three normal skin samples and three normal buccal mucosa samples were used for the experiments. Skin equivalents were constructed in four ways, depending on the combinations of keratinocytes (cutaneous or mucosal keratinocytes) and fibroblasts (dermal or mucosal fibroblasts), and the effects of subepithelial fibroblasts on the differentiation of oral and cutaneous keratinocytes were studied with histological examinations and immunohistochemical analyses with anti-cytokeratin (keratins 10 and 13) antibodies. For each experiment, three paired skin equivalents were constructed by using single parent keratinocyte and fibroblast sources for each group; consequently, nine (3 x 3) organotypic cultures per group were constructed and studied. The oral and cutaneous epithelial cells maintained their intrinsic keratin expression. The keratin expression patterns in oral and cutaneous epithelia of skin equivalents were generally similar to their original patterns but were partly modified exogenously by the topologically different fibroblasts. The mucosal keratinocytes were more differentiated and expressed keratin 10 when cocultured with dermal fibroblasts, and the expression patterns of keratin 13 in cutaneous keratinocytes cocultured with mucosal fibroblasts were different from those in keratinocytes cocultured with cutaneous fibroblasts. The results suggested that the epithelial phenotype and keratin expression could be extrinsically modified by mesenchymal fibroblasts. In epithelial differentiation, however, the intrinsic control by epithelial cells may still be stronger than extrinsic regulation by mesenchymal fibroblasts.

Neovaginal construction with buccal mucosal grafts

Several surgical techniques have been designed to construct a neovagina that will be satisfying in appearance, function, and feeling when the vagina is congenitally absent. However, no method has yet been approved as a perfect solution. With the aim of solving the problems with conventional methods, the authors describe a new surgical technique that is simple and safe for treating vaginal agenesis. This technique consists of creating a mucosal lining of the neovaginal cavity using multiple full-thickness buccal mucosal patch grafts. Four patients with congenital absence of the vagina treated with this technique are presented. This surgical procedure created a mucus-providing lining inside the neovagina. Selecting the donor site in the oral region resulted in an inconspicuous donor-site scar. Histologically, the neovaginal lining was confirmed as mucosal, and the cream-colored viscous fluid found in the neovaginal cavity was confirmed as mucus. At a mean follow-up period of 15 months, the neovagina remained adequate in depth and width. All of the patients were interviewed to evaluate the function of the neovagina. Each patient reported having regular sexual intercourse and that the neovagina had felt normal to their partners. The encouraging results obtained in four cases suggest that this new technique deserves further application.

The radial free forearm flap--prelaminated versus non-prelaminated: a comparison of two methods

In the present work two methods of harvesting the RFFF (radial free forearm flap) are compared: the prelaminated fasciomucosal and the non-prelaminated fasciocutaneous version. The flaps were employed for intraoral reconstruction after radical oncological surgery of the oral cavity. In most cases a squamous cell carcinoma was the present malignant tumour. A total of 32 patients were included in the study, 16 in each group. The design was retrospective. Data were obtained by clinical follow up, chart review and compiled database. Analysis included the amount of shrinkage of the flaps during the follow-up period, early postoperative complications, following function improving operations and early and late donor site difficulties. Prelaminated fasciomucosal flaps showed a higher shrinkage rate than fasciocutaneous non-prelaminated flaps. Due to this circumstance the number of following function improving operations was higher in the prelaminated flap group. Early wound healing difficulties were also seen more often in the prelaminated flap group, whereas donor site problems occurred more frequently in the non-prelaminated group. Mucosal prelamination of the RFFF is a promising method for a most physiological reconstruction of intraoral defects resulting from tumour surgery. Postoperative shrinkage is a problem in prelaminated RFFF. Our aim is to improve the prelamination technique in order to prevent shrinkage. The almost complete absence of donor site difficulties in prelaminated RFFF may represent a solution to this common and yet unsolved problem.

Lining the mouth floor with prelaminated fascio-mucosal free flaps: clinical experience

Soft-tissue defects of the mouth floor need thin, foldable, and pliable tissues able to preserve local anatomy as well as chewing, phonation, and deglutition. The oral mucosa is made of a stratified, nonkeratinized, epithelium-secreting mucus, which lubricates the oral cavity and facilitates tongue movements. No flap exists that can reproduce the physiology of the oral mucosa better than the oral mucosa itself. Prefabrication of mucosal flaps may represent the best solution. Therefore, 10 consecutive cases of mouth floor cancer were treated with prelamination of the fascia antibrachialis with mucosal grafts obtained from the healthy cheek, and with subsequent transplantation 3 weeks later. A significant increase in mucosal graft surface was seen in all cases, with a mean size twice the original. All flaps healed uneventfully. Follow-up time ranged between 2-60 months (average, 26.6 months). Morphological and functional results were excellent. Tongue motility, speech intelligibility, and swallowing were reestablished in all treated cases. Mucosal prelamination of the forearm fascia is feasible and allows physiological reconstruction of oral cavity defects up to 6 x 4 cm.

Easy tissue expansion of prelaminated mucosa-lined flaps for cheek reconstruction in a canine model

In head and neck reconstruction, there is sometimes the need for a skin flap lined with mucosa. The object of this study was to determine whether small pieces of mucosa grafted onto the undersurface of a skin flap can be expanded in a reasonable time to provide the material required to reconstruct a full-thickness cheek defect as a free flap. The study consisted of two phases: prelamination and expansion of the flap, and vascularized free-tissue transfer of the flap. Six adult mongrel dogs were used. First, a 5 x 10-cm flap based on the saphenous vessels was elevated on the lower leg, and then four 1 x 2-cm pieces of mucosa harvested from the tongue were grafted onto the undersurface of the flap. A tissue expander (5 x 10 cm) was then placed under the flap, and the incision was closed primarily. The expanders were initially filled with just enough normal saline to obliterate dead space immediately after surgery. The expansion was continued twice weekly for 3 weeks until sufficient expansion was obtained. Two of six flaps were followed for an additional 6 weeks after the 3-week expansion period to observe whether additional mucosa could be obtained. After measurement of the mucosal area, each flap was transferred as free flap to reconstruct an iatrogenic cheek defect. The increase of mucosal surface area was compared with the original graft, and differences were analyzed using the paired t test. All flaps were successfully expanded without any complications. Histologic evaluation revealed that grafted mucosa took well without evidence of graft necrosis, and the intergraft area was covered with histiocytes. Angiography revealed well-defined vascular structures covering the entire area of the flap. The new mucosal area (23.5 +/- 2.4 cm2) was significantly larger than the original mucosal graft (8.7 +/- 0.9 cm2) (p < 0.001). The net increase of the mucosal area was 172.9 +/- 32.4 percent. The increase of mucosal area in two flaps, following a 6-week consolidation period after 3 weeks of expansion, was only slightly greater (25.9 +/- 1.3 cm2) than those without the consolidation period (22.3 +/- 1.8 cm2). This increase of the mucosal area appears to be related to the amount of expansion, and not to the length of the consolidation period. The flaps were successfully transferred as free flaps to reconstruct the full-thickness cheek defects without major complications. Although a staged operation to allow flaps to mature is needed, the present procedure has the advantages of providing a mucosa-lined flap and allowing primary closure of the donor site. The authors conclude that expansion of this flap has great potential in reconstructive surgery.

Prefabricated buccal mucosa-lined flap in an animal model that could be used for vaginal reconstruction

Congenital vaginal aplasia, gynecological tumor excision, and male-to-female sex surgery are three clinical conditions in which the plastic surgeon is involved in vaginal reconstruction. Skin-lined or skin-grafted local flaps are currently used, but for many reasons, keratinized skin is not the ideal lining for such a moist cavity because it leads to dryness, desiccation, maceration of the skin, and even hair growth in the cavity. The purpose of this study was to create a subcutaneous cavity lined with mucosa in an area with a predictable blood supply. The abdominal area supplied by the deep circumflex iliac vessels was chosen. Six minipigs were used. Strips of tongue buccal mucosa formed the lining; if additional tissue was required, it was taken from the mucosal aspect of the cheek. The mucosa was expanded by using multiple stab incisions. The mucosa was sutured onto the fascia supplied by the deep circumflex iliac vessels, and the skin incision was closed over a silicone sheet to prevent adhesion to the underlying mucosa. This was left for 1 week to allow the mucosa to take. The prefabricated fascial flap was rolled over a silicone stent and was closed longitudinally to form a cylindrical shape. The flap was placed in a subcutaneous pocket in the right inguinal area. The caudal end was left open and was sutured to the surrounding skin. The silicone stent was used to keep the cavity patent and to prevent adhesions in the early stage of the healing process. Regular digital examination was performed to assess patency and contour; endoscopy allowed assessment of mucosa viability. This method of producing a mucosa-lined flap may provide a solution to the difficult problem of vaginal reconstruction.

Prefabricated (expander) capsule-lined transposition and advancement flaps in reconstruction of lower eyelid and oral defects: an experimental study

In six pigs with prefabricated transposition flaps and six pigs with prefabricated advancement flaps, both flap types (lined with an expander capsule) were used to reconstruct wedge excisions of the lower eyelid or defects in the cheek/oral mucosa. The capsules replaced the conjunctiva in eyelid defects and the oral mucosa in cheek defects. Histopathologic studies were performed at 5 to 7 days, 9 to 10 days, 2 weeks, 3 to 4 weeks, and 2 and 3 months after flap reconstructions. Healing was rapid and uneventful, leading to restoration of the conjunctiva/eyelid and oral mucosa between 9 days and 2 weeks. The healing of the eyelid conjunctiva was somewhat faster than of the oral mucosa. The expander capsule acted as a conjunctival/ mucosal substitute, providing a temporary physical shield, an infectious barrier, and a matrix for epithelial regeneration. All reconstructions were successful except one oral reconstruction with early flap necrosis. Flaps lined with an expander capsule could improve and facilitate clinical reconstructions in the eyelid and oral cavity.

Neuromucosal prelaminated flaps for reconstruction of intraoral lining defects after radical tumor resection

To reconstruct intraoral lining defects after radical tumor resection by reinnervated vascularized mucosa, eight distal radial forearm flaps and two fibula flaps were prelaminated. Prelamination was performed by exposing the vascularized fascia, onto which the split distal end of a sural graft was fixed. The fascia and the sural nerve graft were covered by device-meshed mucosa or small full-thickness mucosa pieces. These structures again were covered by a Silastic sheet as large as the future flap, and the wound was closed by the elevated skin and subcutaneous tissue. Coverage by a Silastic sheet enabled mucosal spreading on the fascia, and the final flaps were thin, mucus-producing, and larger than the originally inserted mucosa. The 10 neuromucosal prelaminated flaps were harvested together with the inserted sural nerve graft after 8 to 10 weeks. During this time, the patient underwent radiotherapy and chemotherapy. Donor sites were closed directly by the preserved skin and subcutaneous tissue. Intraoral defects were reconstructed successfully by eight neuromucosal prelaminated distal radial forearm flaps and two neuromucosal prelaminated fibula flaps. The sural nerve grafts, inserted between the fascia and the mucosa, were coaptated eight times with the lingual nerve and two times with the inferior alveolar nerve. Intended reinnervation of the mucosa could already be proved clinically and histologically in the first two patients after 11 and 9 months. Preservation of skin and subcutaneous tissue considerably lowered donor-site morbidity. Neuromucosal prelamination enables reconstruction of intraoral lining defects by reinnervated mucus-producing tissue. Reconstruction of other mucosa-lined structures by this method seems feasible. Avoidance of skin islands for reconstruction lowers donor-site morbidity.