Vascularization of engineered cartilage constructs in a mouse model.

Tissue engineering of cartilage tissue offers a promising method for reconstructing ear, nose, larynx and trachea defects. However, a lack of sufficient nutrient supply to cartilage constructs limits this procedure. Only a few animal models exist to vascularize the seeded scaffolds. In this study, polycaprolactone (PCL)-based polyurethane scaffolds are seeded with 1 × 10(6) human cartilage cells and implanted in the right hind leg of a nude mouse using an arteriovenous flow-through vessel loop for angiogenesis for the first 3 weeks. Equally seeded scaffolds but without access to a vessel loop served as controls. After 3 weeks, a transposition of the vascularized scaffolds into the groin of the nude mouse was performed. Constructs (verum and controls) were explanted 1 and 6 weeks after transposition. Constructs with implanted vessels were well vascularized. The amount of cells increased in vascularized constructs compared to the controls but at the same time noticeably less extracellular matrix was produced. This mouse model provides critical answers to important questions concerning the vascularization of engineered tissue, which offers a viable option for repairing defects, especially when the desired amount of autologous cartilage or other tissues is not available and the nutritive situation at the implantation site is poor.

Customized tissue engineering for ear reconstruction.

Tissue engineering (TE) of cartilage for reconstructive surgery has proven to be a promising option for obtaining tissue for 3D structures that results in minimal donor site morbidity. Technological advances in this area are important since many defects can only be treated with customized implants. Most TE strategies rely on the use of resorbable 3D scaffolds to guide the growing tissue, with each tissue requiring a specific scaffold that has precisely defined properties depending on the physiological environment. Rapid prototyping (RP) technologies allow the fabrication of scaffolds of various geometric complexities from a variety of materials and as composites, while even allowing the inner architecture of the object to be varied in a defined manner at any given location. Scaffolds can be manufactured using RP techniques directly from computer aided design (CAD) data sources, e.g. via an STL file. The combination of TE and RP serves as the basis for the production of customized implants, for example the cartilage ear framework, and provides new perspectives for autologous ear reconstruction.

Results of esophagogastroduodenoscopy in patients with oral squamous cell carcinoma--value of endoscopic screening: 10-year experience.

PURPOSE: Oral squamous cell carcinoma (OSCC) represents more than 90% of oral malignancies. Risk factors such as smoking and alcohol abuse can result in additional diseases, particularly of the upper gastrointestinal tract. The aim of the present study was to assess the synchronous pathologic changes of the upper gastrointestinal tract using endoscopy at the diagnosis of OSCC using a retrospective cohort study design. PATIENTS AND METHODS: The clinical records of 806 patients with OSCC from 1997 to 2007 were reviewed. Of the 806 patients, 570 (188 females and 382 males) with primary OSCC were identified. All patients underwent esophagogastroduodenoscopy at the initial tumor staging. The tumor stage was defined according to the International Union Against Cancer classification for head and neck malignancies. The clinical and histologic data were analyzed for probability using univariate and multivariate analyses. RESULTS: Of the 570 patients, 289 had limited and 281 advanced disease. A statistically significant association was found between the advanced and limited tumor stage for Barrett's esophagus with an odds ratio of 4.986 (95% confidence interval 1.370 to 27.360, P = .0061). Pathologic findings were observed in 169 patients. Additional risk factors for the development of secondary upper aerodigestive tract cancers were found in 103 patients. CONCLUSIONS: Esophagogastroduodenoscopy provides the opportunity to identify second malignancies, precancerous lesions, and risk factors and to obtain biopsies using one procedure. The results can be immediately integrated into the therapeutic concept of the primary disease. Although new imaging techniques have been available, esophagogastroduodenoscopy still plays a decisive role in the routine staging of OSCC.

Comparison of effective use of implanted vascular pedicles for skin flap prefabrication: an experimental study.

Thin, large, well-vascularized, and axial-pattern flaps are often desired in the clinical practice of defect reconstruction to maximize esthetic and functional results. Flap prefabrication based on the neovascularization development following vascular pedicle implantation allows surgeons to create such flaps as required. Using different types of implanted vascular pedicles, the aim of the study was to identify the most effective and suitable types of pedicles for clinical use. Five models of implanted vascular pedicles in Chinchilla Bastard rabbits were investigated as follows: model 1, arteriovenous (AV) pedicle with end ligation (minimal blood flow in the implanted vascular pedicle); model 2, AV pedicle with end anastomosis (new shunt formation between vein and artery stump for creating maximal blood flow in the implanted vascular pedicle); model 3, purely isolated arterialized venous loop; model 4, purely isolated arterial loop; model 5, AV pedicle with end anastomosis (similar to model 2) combined with flap expansion. These different types of vascular pedicles were implanted into a random-pattern abdominal skin flap as large as 8 x 15 cm. Neovascularization in the various prefabricated flaps was evaluated macroscopically, scintigraphically, microangiographically, and histologically. A total of 150 prefabricated flaps were investigated and randomly assigned to 5 models with 30 flaps each. Each model contained 5 groups of 6 flaps corresponding to the various retention times of 4, 8, 12, 16, and 20 days after vascular pedicle implantation. Six flaps were also designated to the control group. Neovascularization was best in model 5, followed by comparable results for models 2, 3, and 4, with the worst results found in model 1, especially for the time intervals of 8, 12, and 16 days. Twenty days remains the minimal length of time required for matured neovascularization in all models (P < 0.05). Models 2 and 3 both appear to be particularly promising for clinical application.

Management of facial necrotizing fasciitis.

Necrotizing fasciitis is a progressive, life-threatening, bacterial infection of the skin, the subcutaneous tissue and the underlying fascia, in most cases caused by ss-hemolytic group A streptococcus. Only early diagnosis and aggressive therapy including broad spectrum antibiotics and surgical intervention can avoid systemic toxicity with a high mortality rate. This uncommon disease generally occurs in the lower extremities and trunk, and only rarely affects the head and neck region. When located in the face necrotizing fasciitis is associated with severe cosmetic and functional restrictions due to the invasive infection and often to the necessary surgical treatment. Generally surgical intervention cannot be performed in the face as aggressively as in the extremities and trunk, since a lot of vital structures are found in a relatively small area. In the following article, we present the successful diagnostic and therapeutic management of an isolated facial necrotizing fasciitis as a consequence of a nasal bone fracture with a minor dermal cut.

Spontaneous bilateral necrosis of the tongue: a manifestation of giant cell arteritis?

Giant cell arteritis is a chronic vasculitis, which involves large- and medium-sized branches of the arteries originating from the aortic arch. This disease is a diagnostic challenge with a wide range of clinical symptoms and findings due to different affected vessels. Classic symptoms are temporally located headache, thickened temporal artery and jaw claudication. Furthermore, visual symptoms like diplopia or loss of vision can occur. The tongue has an excellent blood supply and ischemic ulceration due to giant cell vasculitis is usually unilateral and rarely described in literature. We present a patient with a spontaneous bilateral tongue necrosis and are convinced that this extraordinary case must be deemed to be a manifestation of giant cell arteritis, although it does not completly satisfy the usually used diagnostic criteria formulated by the American College of Rheumatology.

Extrusion forces of resorbable tacks and titanium screws in laryngeal chondrosynthesis.

Laryngotracheal trauma, partial laryngectomy and phonosurgery may necessitate reconstruction of the cartilaginous skeleton to ensure the quality of respiration and voice. The present report focuses on initial experience gained with a new resorbable material for plates and tacks that allows chondrosynthesis of the laryngeal skeleton. A comparison of the extrusion forces necessary to pull out the resorbable tacks versus conventional titanium screws and the degree of deformation until failure represent the experimental parameters of reconstruction quality under investigation. The PolyMax system (Synthes, Oberdorf, Switzerland) was used in a human cadaver dissection. Sixteen tacks with a diameter of 1.5 mm and sixteen titanium screws with a diameter of 1 mm were placed into the two wings of the thyroid cartilage. Extrusion forces and the degree of deformation occurring until mechanical failure of the device-body interface were measured for the two types of fixation systems. Results in N and mm were compared using a two-sided Wilcoxon test. Neither variable differed significantly between the two groups. However, within the two groups, the necessary strength to pull the tacks or the screws out of the cartilage varied markedly depending on both the inhomogeneous quality of cartilage and the degree of calcification. The PolyMax system with the tacks is recommended as an effective tool for reconstructing the cartilaginous skeleton of the larynx and the trachea with the inherent advantage of resorption as well as avoidance of a second surgery for material removal.

Clinical strategy in hereditary hemorrhagic telangiectasia.

BACKGROUND: Hereditary hemorrhagic telangiectasia (HHT) is a recurrent bleeding tendency caused by vascular malformations and preferentially involving the mucous membrane of the nose. The rhinological management of epistaxis is a challenge in which the frequency of bleeding has to be reduced without damage to the nasal mucosa, despite the fact that therapy necessarily has to be repeated. METHODS: The clinical course in 30 patients with HHT was monitored prospectively. Nasal mucosal efflorescences underwent Nd:YAG laser therapy at individually defined intervals, and the effect on the frequency and duration of bleeding was documented, as were adverse effects. RESULTS: No serious adverse effects (e.g., septal defects or synechiae) were observed as a consequence of therapy. During the course of laser therapy and ongoing compliance with nasal mucosal care instructions, the frequency of bleeding fell from "several times daily" to "every 2 weeks." CONCLUSION: In conjunction with Nd:YAG laser therapy, ongoing and consistent care of the nasal mucosa is a proven and effective treatment regimen in HHT. As an integral element in an interdisciplinary strategy for diagnosis and therapy, this regimen yields satisfactory quality of life while avoiding local complications.

Morphological changes of the posterior airway space after tongue base suspension.

OBJECTIVES/HYPOTHESIS: The objectives were 1) to demonstrate the efficacy of tongue base suspension with the Repose System in modifying the posterior airway space on the basis of morphological changes in the retrolingual space and 2) to determine the implications of this procedure for the treatment of obstructive sleep apnea syndrome on polysomnographic and psychometric data. STUDY DESIGN: A prospective, nonrandomized study. METHODS: Polysomnography was performed before as well as 3 and 12 months after surgery in patients undergoing tongue base suspension using the Repose System. To identify morphological changes in the posterior airway space, lateral cephalometric radiography and videoendoscopy of the pharynx were performed preoperatively and postoperatively. Twenty-eight male patients with obstructive sleep apnea syndrome were included in the study. A suspension suture anchored intraorally at the mandible was passed submucosally in the body of the tongue, with suture tightness adjusted individually. RESULTS: The posterior airway space was widened by at least 2 mm in 60% of cases. Daytime sleepiness improved subjectively in 67% of patients, and the respiratory disturbance index improved postoperatively in 55%. The correlation between posterior airway space widening and the improvements in daytime sleepiness and respiratory disturbance index was not significant. CONCLUSION: Surgical intervention in obstructive sleep apnea syndrome with the Repose System does not result in permanent anatomical change in the posterior airway space.

Flap prefabrication and prelamination with tissue-engineered cartilage.

In reconstructive surgery, the integration of tissue-engineered cartilage in a prefabricated free flap may make it possible to generate flaps combining a variety of tissue components, to meet the special requirements of particular defects. One aim of the present study was to investigate prefabrication of a microvascular free flap by implanting a vessel loop under a skin flap in a rabbit model. A second aim was to report on the authors' preliminary experiences in prelaminating prefabricated flaps with autologous tissue-engineered cartilage, in terms of matrix development, inflammatory reaction, and host-tissue interaction. The flap was prefabricated by implanting a vessel loop under a random-pattern abdominal skin flap. The tissue-engineered cartilage constructs were made by isolating chondrocytes from auricular biopsies. Following a period of amplification, the cells were seeded onto a non-woven scaffold made of a hyaluronic-acid derivative and cultivated for 2 weeks. One cell-biomaterial construct was placed beneath the prefabicated flap, and two additional constructs were placed subcutaneously and intramuscularly. In addition, a biomaterial sample without cells was placed subcutaneously to provide a control. All implanted specimens were left in position for 6 or 12 weeks. Neovascularization in the prefabricated flap and biomaterial construct was analyzed by angiography. After explantation, the specimens were examined by histologic and immunohistochemical methods. The prefabricated flaps showed a well-developed network of blood vessels between the implanted vessel loop and the original random-pattern blood supply. The tissue-engineered constructs remained stable in size and showed signs of tissue similar to hyaline cartilage, as evidenced by the expression of cartilage-specific collagen type II and proteoglycans. No inflammatory reactions were observed. The physiologic environment of the autologous rabbit model provided favorable conditions for matrix deposition and maturation of the cell-biomaterial constructs. These initial results demonstrated the potential of prefabricating an axial perfused flap, combined with tissue-engineered cartilage, thus creating functionally competent tissue components for reconstructive surgery with minimal donor-site morbidity.

A comparison between anterior and posterior monitoring of neuromuscular blockade at the diaphragm: both sites can be used interchangeably.

UNLABELLED: We present a novel site of monitoring neuromuscular blockade of the diaphragm at the patient's back. After the induction of anesthesia, 12 patients were orotracheally intubated. Two Ag/AgCl-electrodes were attached at the right seventh or eighth intercostal space between the midclavicular and anterior axillary line; two Ag/AgCl-electrodes were paravertebrally attached on the right side lateral to vertebrae T12-L1 or L1-2. Two Ag/AgCl-skin-electrodes were placed over the right thenar area for an electromyography recording of the adductor pollicis (AP) muscle, and two Ag/AgCl-skin-electrodes were used to stimulate the ulnar nerve. Onset and offset of neuromuscular blockade after rocuronium 0.6 mg/kg were determined, and significant differences between diaphragm and AP muscle and agreement between the two methods were determined. Mean maximum block was more than 96% at all sites. Lag time, onset 50, and onset time were not significantly different between the diaphragm and the AP. However, time to reach 25% of control twitch was significantly longer at the AP muscle than at the diaphragm (P < 0.001). The difference of the means and limits of agreement between the anterior and the posterior site of diaphragmatic monitoring were 0 +/- 11 s, 3 +/- 9 s, 0 +/- 19 s, and -2% +/- 5% for lag, onset 50, onset time, and peak effect, respectively, and -2 +/- 2 min for the time to reach 25% of control twitch of neuromuscular blockade. We conclude that anterior and posterior diaphragmatic monitoring can be used interchangeably to determine neuromuscular blockade after rocuronium. IMPLICATIONS: We present a novel site of monitoring neuromuscular blockade of the diaphragm at the patient's back, which shows good agreement with the conventional anterior site at the seventh or eighth intercostal space.