Cartilage regeneration in the rabbit nasal septum

Achieving Nasal Septal Cartilage In Situ Regeneration: Focus on Cartilage Progenitor Cells

The nasal septal cartilage plays an important role in preventing the collapse of the nasal bones and maintaining the appearance of the nose. In the context of inherent difficulties regarding septal cartilage repair and the shortage of cartilage graft resources for regeneration, tissue engineering, especially the in situ strategy based on scaffolds, has become a new prospect and become one of the most promising approaches. Given that it is difficult for chondrocytes to achieve directional migration and secrete matrix components to participate in tissue repair after cartilage injury, cartilage progenitor cells (CPCs), with great migratory ability and stem cell characteristics, have caught the attention of researchers and brought hope for nasal septal cartilage in situ regeneration. In this review, we first summarized the distribution, characteristics, isolation, and culture methods of nasal septal CPCs. Subsequently, we described the roles of migratory CPCs in cartilage regeneration. Finally, we reviewed the existing studies on CPCs-based cartilage tissue engineering and summarized the strategies for promoting the migration and chondrogenesis of CPCs so as to provide ideas for achieving nasal septal cartilage in situ regeneration.

A TGF-loading hydrogel scaffold capable of promoting chondrogenic differentiation for repairing rabbit nasal septum cartilage defect

Hydrogel-based tissue engineering has been widely used to repair cartilage injury. However, whether this approach can be applied to treat nasal septum cartilage defects remains unclear. In this study, three gelatin methacrylate-based scaffolds loaded with transforming growth factor (TGF)-β1 (GelMA-T) were prepared, and their effects on repair of nasal septum cartilage defects were examined. In vitro, the GelMA-T scaffolds showed good biocompatibility and promoted the chondrogenic differentiation of bone mesenchymal stem cells. Among three scaffolds, the 10% GelMA-T scaffold promoted chondrogenic differentiation most effectively, which significantly improved the expression of chondrocyte-related genes, including Col II, Sox9, and ACAN. In vivo, 10% GelMA-T scaffolds and 10% GelMA-T scaffolds loaded with bone mesenchymal stem cells (BMSCs; 10% GelMA-T/BMSCs) were transplanted into a nasal septum cartilage defect site in a rabbit model. At 4, 12, and 24 weeks after surgery, the nasal septum cartilage defects exhibited more complete repair in rabbits treated with the 10% GelMA-T/BMSC scaffold as demonstrated by hematoxylin & eosin, safranine-O, and toluidine blue staining. We showed that GelMA-T/BMSCs can be applied in physiological and structural repair of defects in nasal septum cartilage, providing a potential strategy for repairing cartilage defects in the clinic.

In Vitro and Ectopic In Vivo Studies toward the Utilization of Rapidly Isolated Human Nasal Chondrocytes for Single-Stage Arthroscopic Cartilage Regeneration Therapy

Nasal chondrocytes (NCs) have a higher and more reproducible chondrogenic capacity than articular chondrocytes, and the engineered cartilage tissue they generate in vitro has been demonstrated to be safe in clinical applications. Here, we aimed at determining the feasibility for a single-stage application of NCs for cartilage regeneration under minimally invasive settings. In particular, we assessed whether NCs isolated using a short collagenase digestion protocol retain their potential to proliferate and chondro-differentiate within an injectable, swiftly cross-linked and matrix-metalloproteinase (MMP)-degradable polyethylene glycol (PEG) gel enriched with human platelet lysate (hPL). NC-hPL-PEG gels were additionally tested for their capacity to generate cartilage tissue in vivo and to integrate into cartilage/bone compartments of human osteochondral plugs upon ectopic subcutaneous implantation into nude mice. NCs isolated with a rapid protocol and embedded in PEG gels with hPL at low cell density were capable of efficiently proliferating and of generating tissue rich in glycosaminoglycans and collagen II. NC-hPL-PEG gels developed into hyaline-like cartilage tissues upon ectopic in vivo implantation and integrated with surrounding native cartilage and bone tissues. The delivery of NCs in PEG gels containing hPL is a feasible strategy for cartilage repair and now requires further validation in orthotopic in vivo models.

In vivo efficacy of 3D-printed elastin-gelatin-hyaluronic acid scaffolds for regeneration of nasal septal cartilage defects

Nasal septal cartilage perforations occur due to the different pathologies. Limited healing ability of cartilage results in remaining defects and further complications. This study sought to assess the efficacy of elastin-gelatin-hyaluronic acid (EGH) scaffolds for regeneration of nasal septal cartilage defects in rabbits. Defects (4 × 7 mm) were created in the nasal septal cartilage of 24 New Zealand rabbits. They were randomly divided into four groups: Group 1 was the control group with no further intervention, Group 2 received EGH scaffolds implanted in the defects, Group 3 received EGH scaffolds seeded with autologous auricular chondrocytes implanted in the defects, and Group 4 received EGH scaffolds seeded with homologous auricular chondrocytes implanted in the defects. After a 4-month healing period, computed tomography (CT) and magnetic resonance imaging (MRI) scans were obtained from the nasal septal cartilage, followed by histological evaluations of new tissue formation. Maximum regeneration occurred in Group 2, according to CT, and Group 3, according to both T1 and T2 images with 7.68 ± 1.36, 5.44 ± 2.41, and 8.72 ± 3.02 mm2 defect area respectively after healing. The difference in the defect size was statistically significant after healing between the experimental groups. Group 3 showed significantly greater regeneration according to CT scans and T1 and T2 images. The neocartilage formed over the underlying old cartilage with no distinct margin in histological evaluation. The EGH scaffolds have the capability of regeneration of nasal cartilage defects and are able to integrate with the existing cartilage; yet, they present the best results when pre-seeded with autologous chondrocytes.

Morphological and Molecular Evaluation of the Tissue Repair following Nasal Septum Biopsy in a Sheep Model

OBJECTIVE

Nasal septal pathologies requiring surgical intervention are common in the population. Additionally, nasal chondrocytes are becoming an important cell source in cartilage tissue engineering strategies for the repair of articular cartilage lesions. These procedures damage the nasal septal cartilage whose healing potential is limited due to its avascular, aneural, and alymphatic nature. Despite the high incidence of various surgical interventions that affect septum cartilage, limited nasal cartilage repair characterizations have been performed to date.

METHODS

To evaluate the healing of the nasal septum cartilage perforation, a septal biopsy was performed in 14 sheep. Two and 6 months later, the tissue formed on the place of perforation was explanted and compared with the native tissue. Tissue morphology, protein and gene expression of explanted tissue was determined using histological, immunohistochemical and real-time quantitative polymerase chain reaction analysis.

RESULTS

Tissue formed on the defect site, 2 and 6 months after the biopsy was characterized as mostly connective tissue with the presence of fibroblastic cells. This newly formed tissue contained no glycosaminoglycans and collagen type II but was positively stained for collagen type I. Cartilage-specific genes COL2, AGG, and COMP were significantly decreased in 2- and 6-month samples compared with the native nasal cartilage. Levels of COL1, COL4, and CRABP1 genes specific for perichondrium and connective tissue were higher in both test group samples in comparison with native cartilage.

CONCLUSIONS

Newly formed tissue was not cartilage but rather fibrous tissue suggesting the role of perichondrium and mucosa in tissue repair after nasal septum injury.

Toward tissue-engineering of nasal cartilages

Nasal cartilage pathologies are common; for example, up to 80% of people are afflicted by deviated nasal septum conditions. Because cartilage provides the supportive framework of the nose, afflicted patients suffer low quality of life. To correct pathologies, graft cartilage is often required. Grafts are currently sourced from the patient's septum, ear, or rib. However, their use yields donor site morbidity and is limited by tissue quantity and quality. Additionally, rhinoplasty revision rates exceed 15%, exacerbating the shortage of graft cartilage. Alternative grafts, such as irradiated allogeneic rib cartilage, are associated with complications. Tissue-engineered neocartilage holds promise to address the limitations of current grafts. The engineering design process may be used to create suitable graft tissues. This process begins by identifying the surgeon's needs. Second, nasal cartilages' properties must be understood to define engineering design criteria. Limited investigations have examined nasal cartilage properties; numerous additional studies need to be performed to examine topographical variations, for example. Third, tissue-engineering processes must be applied to achieve the engineering design criteria. Within the recent past, strategies have frequently utilized human septal chondrocytes. As autologous and allogeneic rib graft cartilage is used, its suitability as a cell source should also be examined. Fourth, quantitative verification of engineered neocartilage is critical to check for successful achievement of the engineering design criteria. Finally, following the FDA paradigm, engineered neocartilage must be orthotopically validated in animals. Together, these steps delineate a path to engineer functional nasal neocartilages that may, ultimately, be used to treat human patients. STATEMENT OF SIGNIFICANCE: Nasal cartilage pathologies are common and lead to greatly diminished quality of life. The ability to correct pathologies is limited by cartilage graft quality and quantity, as well as donor site morbidity and surgical complications, such as infection and resorption. Despite the significance of nasal cartilage pathologies and high rhinoplasty revision rates (15%), little characterization and tissue-engineering work has been performed compared to other cartilages, such as articular cartilage. Furthermore, most work is published in clinical journals, with little in biomedical engineering. Therefore, this review discusses what nasal cartilage properties are known, summarizes the current state of nasal cartilage tissue-engineering, and makes recommendations via the engineering design process toward engineering functional nasal neocartilage to address current limitations.

Cartilage regeneration using decellularized cartilage matrix: Long-term comparison of subcutaneous and intranasal placement in a rabbit model

Autologous cartilage as donor tissue for various surgical reconstructions such as nasal septum regeneration is limited and associated with donor site morbidity. Our goal was to evaluate a new resorbable chondroconductive biomaterial made of decellularized porcine nasal septum cartilage compared with autologous native auricular cartilage as the gold standard. In order to examine the material and determine its long-term outcome further, we used subcutaneous implantation and septal implantation in an orthotopic rabbit model. In addition to non-seeded decellularized xenogenic cartilage, chondrocyte-seeded decellularized xenogenic cartilage was implanted as a septal replacement. After a three- or six-month period, the formation of newly synthesized cartilage extracellular matrix was evaluated immunohistochemically, whereas septal integrity and biocompatibility were evaluated histologically. The formation of the implanted neoseptum and form stability was analyzed by using 7-Tesla Magnetic Resonance Imaging. Good biocompatibility with no excessive rejection was demonstrated in all groups. Long-term stable and reliable septal reconstruction could be achieved in the study groups with or without cell seeding with autologous auricular chondrocytes. Autologous cell seeding was advantageous only with regard to septal perforations. Thus, cell seeding provides a benefit regarding long-term stability. However, because of slightly better biocompatibility, less pronounced septum deviation and the markedly lower effort involved, the non-seeded scaffold is favoured for possible clinical application.

The use of glass ionomer cement in the reconstructıon of the dorsal L-strut: an experımental study on rabbıts

OBJECTIVES/HYPOTHESIS

This experimental study in a rabbit model aimed to investigate the use of glass ionomer cement as a tissue adhesive on the dorsal L-strut.

STUDY DESIGN

Sixteen adult male New Zealand White rabbits were used. The rabbits were equally divided into two groups as the control and the study groups.

METHODS

The nasal septum was exposed through a superior approach. A graft was harvested preserving an L-strut cartilage. In the control group, a vertical incision was performed on the dorsal part of the L-strut to divide it into two cut ends, and the graft was sutured to the cut ends with 5-0 polydioxanone suture. In the study group, the reconstruction of the dorsal L-strut was made by fixing the graft to the cut ends with glass ionomer cement as the tissue adhesive. At 2 months, the rabbits were sacrificed. The nasal septum was removed for histopathological examination.

RESULTS

No foreign body giant cells or acute inflammation were determined in the rabbits. The study group had less pronounced chronic inflammation. Comparison of the groups revealed that parameters regarding vascularization, cartilage proliferation, and new cartilage cells were statistically significant different between the two groups (P = .010, P = .010, P = .028, respectively). More vascularization, cartilage proliferation, and new cartilage cells were seen in the study group.

CONCLUSIONS

Glass ionomer cement was effective for the reconstruction of the dorsal L-strut without any foreign body reaction, cartilage necrosis, or marked inflammation in rabbits, and it may be a potentially beneficial alternative to suture fixation.

Marine collagen scaffolds for nasal cartilage repair: prevention of nasal septal perforations in a new orthotopic rat model using tissue engineering techniques

Autologous grafts are frequently needed for nasal septum reconstruction. Because they are only available in limited amounts, there is a need for new cartilage replacement strategies. Tissue engineering based on the use of autologous chondrocytes and resorbable matrices might be a suitable option. So far, an optimal material for nasal septum reconstruction has not been identified. The aim of our study was to provide the first evaluation of marine collagen for use in nasal cartilage repair. First, we studied the suitability of marine collagen as a cartilage replacement matrix in the context of in vitro three dimensional cultures by analyzing cell migration, cytotoxicity, and extracellular matrix formation using human and rat nasal septal chondrocytes. Second, we worked toward developing a suitable orthotopic animal model for nasal septum repair, while simultaneously evaluating the biocompatibility of marine collagen. Seeded and unseeded scaffolds were transplanted into nasal septum defects in an orthotopic rat model for 1, 4, and 12 weeks. Explanted scaffolds were histologically and immunohistochemically evaluated. Scaffolds did not induce any cytotoxic reactions in vitro. Chondrocytes were able to adhere to marine collagen and produce cartilaginous matrix proteins, such as collagen type II. Treating septal cartilage defects in vivo with seeded and unseeded scaffolds led to a significant reduction in the number of nasal septum perforations compared to no replacement. In summary, we demonstrated that marine collagen matrices provide excellent properties for cartilage tissue engineering. Marine collagen scaffolds are able to prevent septal perforations in an autologous, orthotopic rat model. This newly described experimental surgical procedure is a suitable way to evaluate new scaffold materials for their applicability in the context of nasal cartilage repair.

Dealing with the overprojecting pinched tip

OBJECTIVE

When reshaping the pinched and/or pointed nasal tip, the use of cartilage grafting and internal sutures has been proven to be an excellent tool when the skin is not too thin. A new technique in tip aesthetics is presented. Its surgical applications are discussed.

STUDY DESIGN

A tip reshaping without cartilage grafting or internal stitching was performed on 355 patients with thin skin; 317 were female and 38 were male. The follow-up period ranged from 6 months to several years, with an average of 16 months.

METHODS

The closed approach was used. Parallel incisions on the alar cartilage have been made and alternate spicules of cartilage have been then excised to reduce the length of the arc of the cartilage and to reshape the tip.

RESULTS

The technique was effective in achieving aesthetic norms.

CONCLUSIONS

When dealing with a very thin skin, the pinched or pointed tip may sometimes need a different approach. The use of cartilage crafting or internal stitching for the reshaping of the tip, in those cases, is not obligatory.

Structural characteristics of septal cartilage and mucoperichondrium

AIM

During nasal septum surgery, elevation of mucoperichondrium from the anterior nasal septum may be more difficult than from the medial and posterior septum. This study aimed to evaluate any histological structural differences between the anterior and posterior nasal septum cartilage, mucoperichondrium and intervening tissue.

MATERIAL AND METHOD

Unilateral mucoperichondrial flap elevation without infiltration was performed, after nasal tip and dorsum decortication, in four patients undergoing open septorhinoplasty. Full-thickness samples, including cartilage and mucoperichondrium, were removed from the anterior and posterior nasal septum and examined under light and electron microscopy.

RESULTS

Light microscopy showed no difference between anterior and posterior septum specimens regarding perichondrial thickness and subperichondrial cell density. Demarcation between cartilage and perichondrium and between perichondrium and lamina propria was more regular in the posterior versus the anterior septum. Electron microscopy showed no difference in chondroblast activity at the two sites.

CONCLUSION

The observed tissue demarcation irregularities may explain the greater reported difficulty in elevating anterior versus posterior nasal septum mucoperichondrium. Immunohistochemical examination would further elucidate these interstructural connections.

Porcine cartilage model for simulation of nasal tip aesthetics and mechanics

BACKGROUND

The aesthetics of the human nose is highly dependent on the complex structure of the lower lateral cartilages (LLC). Understanding optimum shape and mechanical properties of the LLC is pivotal to achieving satisfactory results in nasal tip rhinoplasty.

OBJECTIVE

The authors introduce an ex vivo animal model to replicate the shape and mechanics of human nasal LLC as a tool for research and surgical education.

METHODS

Seven fresh pig heads were obtained from a local butcher shop. Nasal cartilage was harvested in a replicable manner and fashioned into appropriate shapes and dimensions based on the authors' human cadaver studies. Sutures were placed to approximate the cartilage pairs into appropriate human anatomical position.

RESULTS

The porcine cartilage model replicated analogous structures, including the medial crura and the lateral crura, with appropriate cephalic orientation and domal angles. The anterior-posterior dimensions of the medial crura, intermediate crura, and lateral crura were 4 mm, 6 mm, and 10 mm, respectively. Cartilage thickness was approximately 1 mm throughout the specimen. Cephalic orientation of the lateral crura was sculpted to 45°. The average angle of divergence was 54° and varied according to the physiological shape of the porcine nasal vault (range, 43-74°). Average interdomal distance was 13.3 mm (range, 9-18 mm), and average domal width was 6.2 mm (range, 5-7 mm).

CONCLUSIONS

This novel porcine model mimics human LLC and is inexpensive, easy to construct, and highly replicable. This model can be used as a valuable educational resource for training novice surgeons in the principles of nasal tip rhinoplasty. Additionally, our construct has broad applications in studying LLC geometry and mechanics.

Nasal septal abscess in children: from diagnosis to management and prevention

BACKGROUND

Nasal septal abscess (NSA) is an uncommon condition. It is a collection of pus in the space between the nasal septum and its overlying mucoperichondrium and/or mucoperiosteum. If left untreated, there are risks of intracranial complications, facial deformity, and delayed facial growth. There is no universally agreed consensus on the treatment of this condition. This study reviews evidence in the literature to determine its etiology, presentation, investigation, management options, and outcome.

METHOD

A structured review of the PubMed, EMBASE and the Cochrane Collaboration databases (Cochrane Central Register of Controlled Trials, Cochrane Database of Systemic Reviews) was undertaken, using the MeSH terms: nasal septum, nasal cartilage, trauma, hematoma, abscess, reconstructive surgery, rhinoplasty, pediatric, and children.

RESULTS

A total of 159 citations from 1920 to date were reviewed regarding nasal septal abscess, of which 81 articles were identified to be relevant to this review. No randomized controlled trials or systematic reviews were found in the Cochrane Collaboration database, PubMed or EMBASE. NSA is more common in children and in male. Nasal trauma and untreated septal hematoma are the leading cause. Staphylococcus aureus is isolated in up 70% of the cases. Clinically, nasal septal swelling, pain and tenderness, with purulent discharge are mostly evident. The immediate management of NSA is incision and drainage and antibiotic therapy. Recent studies suggest early septal reconstruction in children in order to prevent immediate and late facial deformity and nasal dysfunction. Autologous cartilage is the implant material of choice.

CONCLUSION

Nasal septal abscess is a serious condition that necessitates urgent surgical management in order to prevent potential life threatening complications. In the growing child, early reconstruction of destructed septal cartilage is essential for normal development of the midface (nose and maxilla).

Needle electrode-based electromechanical reshaping of rabbit septal cartilage: a systematic evaluation

Electromechanical reshaping (EMR) provides a means of producing shape change in cartilage by initiating oxidation-reduction reactions in mechanically deformed specimens. This study evaluates the effect of voltage and application time on specimen shape change using needle electrodes. Rabbit septal cartilage specimens (20 x 8 x 1 mm, n = 200) were bent 90 degrees in a precision-machined plastic jig. Optimal electrode placement and the range of applied voltages were estimated using numerical modeling of the initial electric field within the cartilage sample. A geometric configuration of three platinum needle electrodes 2 mm apart from each other and inserted 6 mm from the bend axis on opposite ends was selected. One row of electrodes served as the anode and the other as the cathode. Constant voltage was applied at 1, 2, 4, 6, and 8 V for 1, 2, and 4 minutes, followed by rehydration in phosphate buffered saline. Samples were then removed from the jig and bend angle was measured. In accordance with previous studies, bend angle increased with increasing voltage and application time. Below a voltage threshold of 4 V, 4 minutes, no clinically significant reshaping was observed. The maximum bend angle obtained was 35.7 ± 1.7 º at 8 V, 4 minutes.

Assessment of biphasic calcium phosphate to repair nasal septum defects in sheep

BACKGROUND

Saddle nose and septal perforations are among the most surgically challenging situations in nasal reconstruction. They require a significant volume of autologous graft and a complex surgical procedure. The aim of this study was to evaluate the biocompatibility of the biphasic calcium phosphate implant in the nasal septum and its ability to replace septal skeleton with unilateral or bilateral exposure.

METHODS

Thirty sheep underwent anterior nasal septum perforation. Only 20 septa were repaired with the implant exposed to nasal content on bilateral (group 2) and unilateral (group 3) sides. After 45 days of spontaneous cicatrization, the surface of new airway mucosa covering implants and the amount of closure were evaluated macroscopically. Light microscopy, histomorphometry, immunohistochemistry, and transmission electron microscopy were performed to assess soft-tissue growth and differentiation. Statistical analysis was performed by means of the Mann-Whitney test.

RESULTS

The mean rate of mucoperichondrial flap recovery of the implant was 66 percent in group 2 and 82 percent in group 3, and was significantly different from that of the control group (p < 10(-4)). The mean amount of closure was 32 and 64 percent, respectively (p < 10(-3)). The thickness of the perichondrium was greater than the control on both sides (p < 10(-4)). Vascularized soft tissues and bone formation invaded pores of implants. No pathologic inflammation was observed in submucosa. Moderately differentiated and well differentiated newly formed epithelium were the most frequent types observed, with good correlation between immunostaining and morphologic features.

CONCLUSION

These data suggest a good biocompatibility of biphasic calcium phosphate and its ability to repair the nasal septum in sheep.

Chicken sternal cartilage for simulated septal cartilage graft carving: a rhinoplasty educational model

BACKGROUND

In rhinoplasty, cartilage is often harvested from the nasal septum and meticulously carved into delicate grafts designed to reshape and strengthen the nasal osteocartilaginous framework. Proficiency at this task develops with experience in the clinical setting.

OBJECTIVE

The author offers a simulated educational model designed to provide rhinoplasty surgeons with increased preclinical experience in cartilage graft carving.

METHODS

This model relies on inexpensive, food-grade chickens, which may be purchased at any grocery store. Four whole chickens were dissected to expose and harvest the sternal (breast/keel) cartilage. A technique was developed for preparing the cartilage to approximate the shape and dimensions of human septal cartilage. Measurements were made to demonstrate similarities between the model material and the human septum.

RESULTS

The average weight of the chickens was 4.27 lb. The average cartilage height, length, and thickness were 2.36 cm, 6.13 cm, and 3.4 mm, respectively. This size compared favorably with typical septal harvest pieces, which had both heights and lengths of 2.5 cm and thicknesses of 3.25 mm. The author found that one sternal cartilage piece could be employed to carve two spreader grafts, a columellar strut graft, a tip graft, and two alar rim cartilage grafts. The performance of the avian cartilage was subjectively very similar to that of septal cartilage. Furthermore, two pieces of the sternal cartilage could be glued together and fastened within a model of a human skull to replicate the cartilaginous septum in situ. This construct was employed for demonstrations of actual septal cartilage harvest.

CONCLUSIONS

Carving septal cartilage into grafts is a difficult process. Precision and improved results increase with clinical experience on human patients, but this cadaveric avian (chicken) model provides an opportunity for simulated surgical training on a very similar tissue type at a very low cost. This model has the potential to improve human outcomes by providing increased practice opportunities in a procedure that requires precision and artistry for the formation of reproducible geometric graft shapes.

Viability of human septal cartilage after 1.45 microm diode laser irradiation

BACKGROUND AND OBJECTIVES

Chondrocyte viability following laser irradiation and reshaping has not been established for human nasal septal cartilage. Knowledge of the relationship between thermal injury and laser dosimetry is needed in order to optimize septal laser cartilage reshaping. The objective of this study was to determine the depth and width of thermal injury in human septal cartilage following laser irradiation.

STUDY DESIGN/MATERIALS AND METHODS

Excess fresh nasal septal cartilage sections from rhinoplasty or septoplasty operations were irradiated using a 1.45 microm diode laser 1.25-3.6 W (2.8 mm spot diameter) with 1 second fixed exposure time, and then at exposure times of 1-4 seconds for a fixed power of 1.25 W. An infrared camera recorded surface temperature profiles during irradiation, and the temperature data were incorporated into a rate process model to numerically estimate thermal damage. Calcein AM and ethidium homodimer-1 fluorescent dyes combined with confocal laser microscopy (CLM) were used to measure thermal damage.

RESULTS

CLM demonstrated clear demarcation between dead and living cells following irradiation. The extent of non-viable chondrocyte distributions increased with power and exposure time. The maximum depths of injury were 1,012 and 1,372 microm after 3.6 W 1 second and 1.25 W 4 seconds irradiation respectively. The damage predictions made by the rate process model underestimated thermal injury when compared with CLM measurements.

CONCLUSIONS

The assay system identified regions of non-viable chondrocytes in human septal cartilage and defined how thermal injury varies with dosimetry when using a 1.45 microm diode laser.

Simultaneous myringoplasty and septoplasty, and the use of nasal septal perichondrium

To investigate the more ideal graft for optimal repair of tympanic membrane perforation, we examined the use of septal perichondrium in myringoplasty. Twenty-five patients with ages ranging between 18 and 54 were included in this study. All had a persistent, symptomatic tympanic membrane perforation, and nasal obstruction. All patients were scheduled for myringoplasty by a transmeatal approach in combination with septoplasty under general anaesthesia. Twenty-three patients had intact graft material and had more than 5 dB HL improvement in conductive hearing thresholds at least three frequencies in the follow up period. An overall success rate of 92 and 92% was recorded in terms of hearing improvement and perforation closure, respectively. Nasal septal perichondrium is easily accessible, cost-effective, time saving, sufficiently large, and patient friendly as a graft material in myringoplasty and has a good chance of postoperative survival.

Short-term effects of perichondrium preservation on chondrocyte survival and chondrogenesis of auricular cartilage grafted in rabbit tympanic bullae

INTRODUCTION

Obliteration of the mastoid cavities with auricular cartilage is a frequently used method to minimize the open cavity problem in cholesteatoma surgery. However, the method of cartilage preparation and histopathologic changes of the grafted cartilage in patients receiving mastoid obliteration are rarely reported. Hence, the authors developed rabbit tympanic bulla obliteration with auricular cartilage as an animal model and studied the effects of perichondrium preservation on the grafted cartilage.

MATERIALS AND METHODS

Auricular cartilage with or without perichondrium was prepared and cut into small pieces to obliterate rabbit tympanic bullae. Four weeks after surgery, the viable chondrocyte ratio indicated by the number of viable chondrocytes divided by the total number of chondrocytes, the microvascular density shown by CD31-labeled vessels, and the chondrogenesis ratio represented by the ratio of the cross-sectional areas of the newly formed cartilage and the originally grafted cartilage were calculated and compared.

RESULTS

The viable chondrocyte ratio was 49.21 +/- 10.17% in the perichondrium-preserved group (n = 12) and 35.46 +/- 3.96% in the perichondrium-removed group (n = 12, p = 0.001). The CD31 microvascular density was significantly higher in the perichondrium-preserved group than in the perichondrium-removed group (167.77 +/- 15.83 vs. 77.17 +/- 19.67 microvessels/mm(2), p < 0.001). The chondrogenesis ratios were 27.58 +/- 12.44% in the perichondrium-preserved group and 0.45 +/- 0.63% in the perichondrium-removed group (p < 0.001).

CONCLUSION

Obliteration of tympanic bullae with perichondrium-preserved cartilage results in faster restoration of circulation, higher survival of chondrocytes and more cartilage regeneration than with perichondrium-removed cartilage.