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OBJECTIVE Treatment of chondrosarcomas is grade based; intralesional curettage for grade 1 and resection for grade 2 or more. Currently used methods to determine grades before surgery are not highly accurate and create a dilemma for the surgeon. We have used a PET-CT combined with imaging to answer the following study questions: (1) Does SUVmax value from an 18F-FDG PET/CT correlate with the grade of chondrosarcoma? (2) Can a cutoff SUVmax value be used to differentiate between various grades of chondroid neoplasms with sufficient sensitivity and specificity? (3) Does SUVmax guide the clinician and add value to radiology in offering histologic grade-dependent management? METHODS SUVmax values of patients with suspected chondrosarcoma were retrospectively correlated with the final histology grade for the operated patients. Radiologic parameters and radiology aggressiveness scores (RAS) were reevaluated and tabulated. RESULTS Totally 104 patients with chondroid tumors underwent 18F-FDG PET/CT assessment. In total 73 had tissue diagnosis available as a pretreatment investigation. Spearman correlation indicated that there was a significant positive association between SUVmax and the final histology grading of chondroid tumors (correlation coefficient = 0.743; P

Made available in DSpace on 2021-06-25T12:22:05Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-09-22 Backgroud. Leishmaniasis is an infectious disease caused by protozoan of the genusLeishmaniathat can affect mucosal or cutaneous surfaces. It can manifest via buccal mucosa, associated with a skin lesion or as a secondary effect. Over the last 20 years, the number of cases of this disease is progressively increasing in Brazil. Therefore, the knowledge of this disease by health professionals is important in order to achieve a correct and early diagnosis, manly to prevent the deformities it may cause to the face.Case presentation. The aim of the present study was to report a case of mucocutaneous leishmaniasis with lesions on the palatine and pharyngeal mucosa in a patient with a previous report of rare lesions in the nasal mucosa and cartilage bone septal.Conclusions. We believe that the disclosure of such cases may be important for the correct and early diagnosis of these secondary injuries that may affect the oral mucosa. Univ Estadual Paulista, Araraquara Dent Sch, Dept Diag & Surg, UNESP, Araraquara, SP, Brazil UNESP, Oral Med Serv, Araraquara, SP, Brazil Univ Estadual Paulista, Araraquara Dent Sch, Dept Diag & Surg, UNESP, Araraquara, SP, Brazil UNESP, Oral Med Serv, Araraquara, SP, Brazil

Background Visual field deterioration caused by secondary empty sella after cabergoline therapy for prolactinoma is a rare event. Chiasmapexy is performed to treat empty sella syndrome. Although various materials have been used for the elevation of the optic chasm, the most appropriate material remains to be established. Here, we describe the efficiency of chiasmapexy for empty sella syndrome following dopamine agonist treatment and the utility of septal cartilage and sphenoidal sinus bone as materials for chiasmapexy. Case Description A 35-year-old male with a history of cabergoline therapy for prolactinoma presented with visual deterioration. His magnetic resonance imaging revealed optic chiasm herniation into the empty sella. Endoscopic endonasal transsphenoidal chiasmapexy was performed using septal cartilage and sphenoidal sinus bone as materials for elevating the chiasm. Visual function improved immediately after operation. Conclusions Chiasmapexy is an effective surgical method for treating visual deterioration caused by empty sella after cabergoline treatment. Endoscopic endonasal chiasmapexy with septal cartilage and sphenoidal sinus bone is a considerable option because it is minimally invasive and involves decreased risk of infection.

Both spin-echo (SE) and ultra-short echo (UTE) based MRI sequences were used on a 7 T µMRI system to quantify T2, T1ρ and T1 relaxation times from articular cartilage to the cartilage-bone interface on canine humeral specimens at 19.5 µm pixel resolution. A series of five relaxation-weighted images were acquired to calculate one relaxation map (T2, T1ρ or T1), from which the depth-dependent profiles were examined between the SE method and the UTE method, over the entire non-calcified cartilage and within the cartilage-bone interface. SE-based methods enabled the quantification of relaxation profiles over the noncalcified cartilage, from 0 µm (articular surface) to approximately 460 µm in depth (near the end of radial zone). Most of the cartilage-bone interface was imaged by the UTE-based methods, to a tissue depth of about 810 µm. Pixel-by-pixel calculation of the relaxation times between the independent SE and UTE methods correlated well with each other. A better understanding of the tissue properties reliably over the cartilage-bone interface region by a non-invasive MRI approach could contribute to the clinical diagnostics of trauma-induced osteoarthritis.

The repair and treatment of articular cartilage injury is a huge challenge of orthopedics. Currently, most of the clinical methods applied in treating cartilage injuries are mainly to relieve pains rather than to cure them, while the strategy of tissue engineering is highly expected to achieve the successful repair of osteochondral defects. Clear understandings of the physiological structures and mechanical properties of cartilage, bone and osteochondral tissues have been established, but the understanding of their physiological heterogeneity still needs further investigation. Apart from the gradients in the micromorphology and composition of cartilage-to-bone extracellular matrixes, an oxygen gradient also exists in natural osteochondral tissue. The response of hypoxia-inducible factor (HIF)-mediated cells to oxygen would affect the differentiation of stem cells and the maturation of osteochondral tissue. This article reviews the roles of oxygen level and HIF signaling pathway in the development of articular cartilage tissue, and their prospective applications in bone and cartilage tissue engineering. The strategies for regulating HIF signaling pathway and how these strategies finding their potential applications in the regeneration of integrated osteochondral tissue are also discussed.

Chitosan is a special material because of its nature as a natural polymer, which has been used for the preparation of safe and biocompatible scaffolds for tissue engineering and regenerative medicine. The development of advanced bioscaffolds using bioploymers such as chitosan in tissue engineering and regenerative medicine is a fast-growing multidisciplinary field of science and technology to restore defective and damaged organs. A large number of investigations have been carried out, employing chitosan and/or its derivatives, to develop advanced biomaterials to serve as suitable biological platforms for cell therapy and tissue regeneration. This chapter emphasizes various techniques used to produce chitosan-based biomaterials. The main focus is to provide insights into the blend of chitosan with other natural and synthetic polymers and figuring out their applications. Various chitosan-based biomaterials are discussed in terms of their applications for regeneration of multiple types of tissues such as bone, cartilage, cardiac, vascular, and neural tissues.

Cartilage-bone interface (CBI) is a complex structure which bears important information in pathophysiology of osteoarthritis (OA). While high-frequency ultrasound (US) has been widely used for the investigation of articular cartilage, 3D imaging of CBI using US is less commonly reported in this field. Here, we adopted a 3D high-frequency ultrasound imaging approach specifically for the investigation of CBI in human knee samples. Fifteen osteochondral disks from the tibial plateau of seven OA patients were prepared in vitro and scanned using both high-frequency US and micro-CT imaging. The 3D morphology of the tidemark was reconstructed and compared using an image registration approach between the two imaging modalities. Results showed that the 3D tidemark could be well registered between the two imaging methods with a mean surface discrepancy of 33.2±9.9 μm. Quantitative surface waviness/roughness parameter analysis showed significant correlations between the two imaging modalities. An intensity projected en face imaging was proposed to probe characteristic details of the CBI such as its perforations. This study provided evidence for the 3D high-frequency ultrasound as a nonionizing radiation imaging tool potentially useful to evaluate the change of CBI in basic research of join diseases including OA.

Tissue engineering with scaffolds provides novel prospects for bone/cartilage damage healing. Previous studies mainly focus on the development of physical/chemical property of scaffold and their efficiency on tissue regeneration. The biocompatibility and biodegradation of scaffold have been questioned with their rapidly increased application, since the ultimate clinical application requires biological safety and efficiency of biomaterials. After scaffolds are implanted in living organisms, excessive inflammatory response and foreign body reaction may compromise tissue healing outcomes, or eventually lead to the failure of regeneration. Further, scaffolds degradation and degraded derivatives may elicit immunogenic reaction, cause environmental change, influence encapsulated drug/growth factor release and cellular activity. Hence, the understanding of the degradation characteristics of various biomaterials is required as well. Non-invasive monitoring the fate of scaffolds inside the body needs to be explored for temporally and longitudinally optical observation. The review mainly aims to provide a retrospective summary and discussion of the biocompatibility, immune response and fate of scaffold in cartilage/bone tissue engineering. The continuing development of sophisticated biocompatible and biomimetic scaffolds will eventually lead to clinical application which can improve the quality of patients' care and life.

In order to engineer biomimetic osteochondral (OC) construct, it is necessary to address both the cartilage and bone phase of the construct, as well as the interface between them, in effect mimicking the developmental processes when generating hierarchical scaffolds that show gradual changes of physical and mechanical properties, ideally complemented with the biochemical gradients. There are several components whose characteristics need to be taken into account in such biomimetic approach, including cells, scaffolds, bioreactors as well as various developmental processes such as mesenchymal condensation and vascularization, that need to be stimulated through the use of growth factors, mechanical stimulation, purinergic signaling, low oxygen conditioning, and immunomodulation. This chapter gives overview of these biomimetic OC system components, including the OC interface, as well as various methods of fabrication utilized in OC biomimetic tissue engineering (TE) of gradient scaffolds. Special attention is given to addressing the issue of achieving clinical size, anatomically shaped constructs. Besides such neotissue engineering for potential clinical use, other applications of biomimetic OC TE including formation of the OC tissues to be used as high-fidelity disease/healing models and as in vitro models for drug toxicity/efficacy evaluation are covered. Highlights Biomimetic OC TE uses “smart” scaffolds able to locally regulate cell phenotypes and dual-flow bioreactors for two sets of conditions for cartilage/bone Protocols for hierarchical OC grafts engineering should entail mesenchymal condensation for cartilage and vascular component for bone Immunomodulation, low oxygen tension, purinergic signaling, time dependence of stimuli application are important aspects to consider in biomimetic OC TE

Background Cartilage elasticity changes with cartilage degeneration. Hence, cartilage elasticity detection might be an alternative to traditional imaging methods for the early diagnosis of osteoarthritis. Based on the wave propagation measurement, Shear wave elastography (SWE) become an emerging non-invasive elasticity detection method. The wave propagation model, which is affected by tissue shapes, is crucial for elasticity estimating in SWE. However, wave propagation model for cartilage was unclear. Methods This study aimed to establish a wave propagation model for the cartilage-bone structure. We fabricated a cartilage-bone structure, and studied the elasticity measurement and wave propagation by experimental and numerical Lamb wave method (LWM). Results Results indicated the wave propagation model satisfied the lamb wave theory for two-layered structure. Moreover, a near field region, which affects wave speed measurements and whose occurrence can be prevented if the wave frequency is larger than one critical frequency, was observed. Conclusion Our findings would provide a theoretical foundation for further application of LWM in elasticity measurement of cartilage in vivo. It can help the application of LWM to the diagnosis of osteoarthritis.

The connective tissue that links the bones of the mandible in the Australian lungfish, Neoceratodus forsteri, has been described as an intermandibular cartilage, and as such has been considered important for phylogenetic analyses among lower vertebrates. However, light and electron microscopy of developing lungfish jaws demonstrates that the intermandibular tissue, like the connective tissue that links the bones of the upper jaw, contains fibroblasts and numerous bundles of collagen fibrils, extending from the trabeculae of the bones supporting the tooth plates. It differs significantly in structure and in staining reactions from the cartilage and the bone found in this species. In common with the cladistian Polypterus and with actinopterygians and some amphibians, lungfish have no intermandibular cartilage. The connective tissue linking the mandibular bones has no phylogenetic significance for systematic grouping of lungfish, as it is present in a range of different groups among lower vertebrates.

In diarthrodial joints, the articular cartilage, calcified cartilage, and subchondral cortical and trabecular bone form a biocomposite - referred to as the osteochondral unit - that is uniquely adapted to the transfer of load. During the evolution of the osteoarthritic process the compositions, functional properties, and structures of these tissues undergo marked alterations. Although pathological processes might selectively target a single joint tissue, ultimately all of the components of the osteochondral unit will be affected because of their intimate association, and thus the biological and physical crosstalk among them is of great importance. The development of targeted therapies against the osteoarthritic processes in cartilage or bone will, therefore, require an understanding of the state of these joint tissues at the time of the intervention. Importantly, these interventions will not be successful unless they are applied at the early stages of disease before considerable structural and functional alterations occur in the osteochondral unit. This Review describes the changes that occur in bone and cartilage during the osteoarthritic process, and highlights strategies for how this knowledge could be applied to develop new therapeutic interventions for osteoarthritis.

[No abstract available]

Background There is a lack of understanding of the morphological characteristics of the cartilage-bone interface. Materials that are currently being used in tissue engineering do not adequately support the regeneration of bone and cartilage tissues. The present study aimed to explore the morphological characteristics of cartilage-bone transitional structures in the human knee joint and to design a biomimetic osteochondral scaffold based on morphological data. Methods Histology, micro-computed tomography (micro-CT), and scanning electron microscopy (SEM) were used to investigate the microstructure of the cartilage-bone transitional structures. Morphological characteristics and their distribution were obtained and summarized into a biomimetic design. A three-dimensional model of a biomimetic osteochondral scaffold was CAD designed. A prototype of the resulting subchondral bone scaffold was constructed by stereolithography using resin. Results Micro-CT revealed that subchondral bone presented a gradually changing structure from the subchondral to spongy bone tissue. The subchondral bone plate was more compact with ~20 % porosity compared with ~60 % porosity for the spongy bone. Histology and SEM showed that cartilage was stabilized on the subchondral bone plate by conjunctions, imbedding, interlocking, and binding forces generated by collagen fibers. Some scattered defects allow blood vessel invasion and nutritional supply. Conclusions The subchondral bone plate is not an intact plate between the cartilage and bone cavity, and some scattered defects exist that allow blood vessel invasion and nutritional supply. This characteristic was used to design an osteochondral scaffold. This could be used to construct an osteochondral complex that is similar to native bones.

Background: Through developmental and evolutionary time, organisms respond variably to their environment not only in terms of size and shape but also in terms of timing. Developmental plasticity can potentially act on various aspects of the timing of developmental events (i.e., appearance, cessation, duration, sequence). In this study, we address the developmental plasticity of median fin endoskeleton by using exercise training on newly-hatched Arctic charr (Salvelinus alpinus). Results: Developmental progress of cartilage formation (i.e., chondrification) in all fins is less influenced than ossification by an increase of water velocity. The most responsive elements, meaning those elements with greater onset plasticity owing to a water velocity increase, differ in terms of early versus late developmental events. The most responsive elements are those that chondrify and to a greater extent ossify later in the development. Conclusions: Plasticity is documented for the timing of appearance (i.e., onset) and the timing of transition from cartilage to bone (i.e., transitions of skeletal states) rather than the order of events within a sequence. Similarities of plastic response in developmental patterns could be used as a powerful criterion to strengthen the identification of phenotypic modules. Developmental Dynamics 241:1507–1524, 2012. © 2012 Wiley Periodicals, Inc.

Our long-term goal is to treat osteochondral lesions with bioengineered biphasic constructs. We have previously demonstrated that biphasic constructs, created in vitro with primary chondrocytes harvested from healthy joints and a porous calcium polyphosphate (CPP) substrate bone substitute, could successfully repair a focal defect in sheep joints. However, primary chondrocytes are limited in supply and cannot be used in engineering constructs large enough for clinical use. Thus, we developed a robust protocol to predifferentiate sheep bone marrow-derived stromal cells to chondrocytes on collagen-coated polytetrafluoroethane membrane inserts, and harvest the chondrocytes that develop and subsequently culturing these predifferentiated cells scaffold-free on the intended articulation surface of the CPP. Chondrocytes predifferentiated on membrane culture accumulated similar matrix as those in conventional pellet culture, but expressed less Col1a1 RNA. Membrane culture predifferentiated cells gave rise to a functionally superior hyaline cartilage tissue compared to pellet culture predifferentiated cells. Studies demonstrated that 2 weeks of membrane predifferentiation culture followed by 8 weeks of biphasic construct culture was the optimal culture period at which the compressive mechanical strength and the accumulation of extracellular matrix were maximized while avoiding tissue mineralization. This protocol will be used to generate implants for preclinical study to determine their ability to repair osteochondral lesions.

Summary Objective This review focuses on histomorphometry for assessing the pathological changes in various compartments of the joint including cartilage, bone and synovium in animal models of osteoarthritis (OA). Methods Different methodological approaches are presented concerning sampling, embedding, sectioning, staining, mounting of stained sections and measurement of histomorphometric parameters using automated and semi-automated methods. Notes are provided describing some methods in greater detail. Results Histomorphometry allows a significant gain of objectivity, accuracy and reproducibility in the quantification of the main histological parameters which best characterize OA in the affected joint (cartilage thickness (CT), chondrocyte size and density, cartilage fissure, proteoglycan (PG) content, subchondral bone plate thickness (SBPT), thickness of synovial living cell layer) in animal models. Conclusion Use of histomorphometry could contribute to a better quantification of histological differences between control and OA animals. Contributing also to the introduction of normative data, it is a major advantage for therapeutic assessments in experimental OA and particularly for the analytical comparison of the efficacy of disease modifying OA drugs (DMOAD).

Secondary malignancies arising from benign bone tumors are rare. Their recognition and diagnosis are difficult, and their slow growth and late recurrence require long-term follow-up. In this study, malignant transformation rates of various histological types of benign cartilage-forming bone tumors in large series were evaluated.Between 1986 and 2004, a retrospective analysis of 627 cartilage-forming benign bone tumors revealed that 32 patients had malignant transformation. Of the 32 patients, 14 had solitary osteochondromas, 10 had multiple osteochondromas, 6 had a solitary enchondroma, 1 had Ollier's disease, and 1 had Maffucci's syndrome. The patient with Ollier's disease had two chondrosarcomas, and one patient with multiple osteochondroma had three chondrosarcomas. The cases were included in the study only when complete clinical documentation, radiological records, and histological analyses were available.The rate of malignant transformation for cartilage-originating tumors was 5.1% (solitary osteochondromas 4.2%, multiple osteochondromas 9.2%, solitary enchondromas 4.2%). The average time between the initial diagnosis and malignant transformation was 9.8 years. The most common site of involvement was the proximal portion of the femur. The tumors generally were well differentiated. The mean follow-up period was 57.3 months. Five patients (15.6%) died of tumor recurrence or metastasis at an average of 20.6 months. One patient is alive with tumor at 104 months.Cartilage-forming benign bone tumors are rather prone to undergo malignant transformation. Although malignant transformation of a benign bone tumor is a rarely encountered situation, orthopedic surgeons should be cautious while following patients with a benign bone neoplasm. Early recognition and appropriate surgical treatment are required to achieve successful outcomes. The rate of local recurrence in secondary chondrosarcomas depends not only on adequate surgical treatment but also on the localization and histological grade.

Introduction Team-based learning (TBL) is an instructional strategy that promotes greater student engagement in the classroom. In TBL, scheduled class time is not used for lecturing. Rather, students are expected to master the basic facts and concepts of the subject matter before coming to class; in-class time is devoted to applying this knowledge to solve challenging problems with students' teams. This TBL module will enable students to describe the structural and functional characteristics of cartilage and bone, explain the cellular mechanisms responsible for their growth and maintenance, and interpret select clinical data related to disorders of these connective tissues. Moreover, students will be able describe the organization and function of the heart and vasculature, recognize and differentiate the different kinds of blood vessels, and relate the cardiovascular system's unique structural features to its function in health and disease. Methods The module consists of four documents: the Instructor's Guide, an individual readiness assurance test (IRAT), a group readiness assurance test (GRAT), and a group application exercise. Explanations of correct answers are provided with the IRAT and group application exercise documents. Prior to the TBL session, students are expected to complete an advanced preparation assignment consisting of textbook readings and laboratory work. Results This module has been administered five times to a total of 157 graduate students, with the cumulative mean scores being 77.0% for the IRAT, 95.9% for the GRAT, and 82.3% for the group application exercise, reflecting solid student understanding of the structure and function of cartilage-bone and cardiovascular system. Discussion These results show that TBL methodology is an effective strategy to teach graduate-level histology and that students do not require formal lectures to learn the material. Based on our experience, we believe that TBL offers learning outcomes comparable to lecture-based instruction but with greater clinical relevance.

We present a Near Infrared Spectroscopy (NIRS) based method for characterisation of biological tissue under mechanical load. In this study we measured NIR spectra of equine cartilage bone samples with simultaneous application of mechanical load. Our goal is to gain more information about the functional behaviour of cartilage tissue to support cartilage therapy.

Tissues that are intermediate between cartilage bone (chondroid, chondroid bone) or intermediate between dentine and enamel (cementum, enameloid) are discussed from evolutionary and developmental perspectives. The concept of scleroblasts as basic skeletal-forming cells is reviewed, as are the cellular concepts of modulation and metaplasia.

Trochlear dysplasia is an important anatomical abnormality in symptomatic patellar instability. Our study assessed the mismatch between the bony and cartilaginous morphology in patients with a dysplastic trochlea compared with a control group. MRI scans of 25 knees in 23 patients with trochlear dysplasia and in 11 patients in a randomly selected control group were reviewed retrospectively in order to assess the morphology of the cartilaginous and bony trochlea. Inter- and intra-observer error was assessed. In the dysplastic group there were 15 women and eight men with a mean age of 20.4 years (14 to 30). The mean bony sulcus angle was 167.9° (141° to 203°), whereas the mean cartilaginous sulcus angle was 186.5° (152° to 214°; p < 0.001). In 74 of 75 axial images (98.7%) the cartilaginous contour was different from the osseous contour on subjective assessment, the cartilage exacerbated the abnormality. Our study shows that the morphology of the cartilaginous trochlea differs markedly from that of the underlying bony trochlea in patients with trochlear dysplasia. MRI is necessary in order to demonstrate the pathology and to facilitate surgical planning.

SummaryObjectiveAn in vitro model was used to test the hypothesis that culture time and adjacent tissue structure and composition affected chondrogenesis and integrative repair in engineered cartilage.MethodEngineered constructs made of bovine calf chondrocytes and hyaluronan benzyl ester non-woven mesh were press-fitted into adjacent tissue rings made of articular cartilage (AC), devitalized bone (DB), or vital bone (VB) and cultured in rotating bioreactors for up to 8 weeks. Structure (light and electron microscopy), biomechanical properties (interfacial adhesive strength, construct compressive modulus), biochemical composition (construct glycosaminoglycans (GAG), collagen, and cells), and adjacent tissue diffusivity were assessed.ResultsEngineered constructs were comprised predominately of hyaline cartilage, and appeared either closely apposed to adjacent cartilage or functionally interdigitated with adjacent bone due to interfacial deposition of extracellular matrix. An increase in culture time significantly improved construct adhesive strength (P

Introduction: To evaluate the clinical outcome of cartilage-bone-transplantations of the knee in patients with different indications, we studied the clinical results of 45 patients with a follow-up of 24 months after operation. Patients and methods: 29 male and 16 female patients with a mean age of 37.7 yrs (16-58 yrs) were included. Indications for operation were osteochondritis dissecans (OD) (n=13), limited arthritis (n = 20), traumatic lesions (n = 5) and retropatellar lesions (n = 7). The results were evaluated by clinical score (McDermott Score [19]; preoperatively, and 3, 6,12, 24 months postoperatively), magnetic resonance imaging, and re-arthroscopy for most patients. Results: 42 of 45 patients judged the operation as successful. The mean score value of all patients raised from 66.3 pts (out of 100 pts) preoperatively to 92.7pts 24 months postoperatively. The results of the patients with circumscript arthritic lesions (62.9 pts. preoperatively vs. 91.5 pts. postoperatively) were comparable to those of the other patients. Conclusion: We conclude that cartilage-bone-transplantation of the knee is a valuable procedure to improve joint function not only after OD or trauma, but also in joints with local arthritic lesions on condition that there is an adequate quality of the donor site.

Both long and irregular bones tend to form via endochondral ossification and are referred to as cartilage bones. Based upon the hypothesis that bone grows and forms as a semi-deterministic/semi-chaotic system, it should be possible to accurately model the osteogenesis of cartilage bones using a stochastic simulation. A thorough review of the literature has been undertaken enabling the cell types and tissues to be identified and a set of simulation rules to be established. The operation of the simulation has been evaluated longitudinally, reporting bone and blood vessel structures as the simulation develops to completion with fusion of the epiphyses; the simulation variability has been assessed by repeat runs using the same default conditions; and the effect of independently modifying key simulation parameters has been studied. This is thought to be the first report of a stochastic simulation of cartilage bone osteogenesis. The developed structures accurately follow the growth and form of irregular cartilage bones such as the vertebrae or calcaneus. The future of the simulation is now dependent primarily upon its potential utility in the field of bone metabolism and disease.

For a long time, the Burkhardt’s saw-toothed cutter was the only biopsy instrument with which a nearly artifact-free bone cylinder could be gathered (Burkhardt 1956). The first experiments on cancellous bone healing were performed with the low-speed Burkhardt’s device. Tissue traumatization in the donor bed, however, was not acceptable for bone healing experiments. Diamond-coated instruments and the wet-grinding procedure had been developed specifically for experiments on the contact healing of cancellous bone (Draenert et al. 1981). Compared with the saw-toothed cutters, nearly no loss of tissue occurred (Fig. 6.1). The technology with respect to cartilage-bone grafts and biopsies (Draenert and Draenert 1987) was ready for application in the early 1980s and publication in 1987. During the evaluation, eight different cutter heads were tested in bovine ribs. As a result, the wet-grinding process using diamond-coated instruments turned out to be the only process to present a nearly atraumatic cylinder and bed, leaving bone and bone marrow of the graft and donor bed intact as well (Fig. 6.1). Those results were published later (Draenert et al. 2007).

Rodent Achilles tendons were subjected to midpoint tenotomy and allowed to recover for various times in situ before the operated tissue was removed, placed into a Millipore diffusion chamber, and inserted intraperitoneally into syngeneic hosts. Diffusion chambers were then removed at weekly intervals, such that the total time after the operation (i.e., time allowed to recover in situ plus time within the diffusion chamber) was up to 8 weeks, and examined histologically. Ectopic cartilage was produced within the diffusion chamber after a total of 4 weeks but only if the first 2 weeks of recovery were in situ. With increasing time, calcified cartilage, osteoid, and bone were also observed. Overall, the evidence suggests that the cartilage forms via a direct conversion from tendon tissue and that the bone may form as a result of differentiative changes of hypertrophic chondrocytes.

Experimental techniques to repair focal defects in articular cartilage involve replacing a small area of damaged cartilage with an artificial implant. An important consideration with these devices is the potential for cartilage to wear against the implant surface. To evaluate these implants and to screen for optimal materials and finishes, a method to quickly and accurately predict in vivo cartilage wear is required. Although pin-on-disc wear testers are frequently used to evaluate the wear of engineering materials, and multi-station test machines are available commercially for rapid testing, they have not often been used to test cartilage wear.Copyright © 2009 by ASME

The sections in this article are Overview Introduction Methods of Formation Electrospinning Self-assembly Phase Separation Nanofibrous Composite Scaffolds Inorganic Composites Surface Modification Factor Delivery Scaffolds Biological Effects of Nanofibers Attachment Proliferation Differentiation Migration Tissue Formation Connective Tissue Ligaments Cartilage Bone Neural Tissue Cardiovascular Tissue Cardiac Muscle Blood Vessel Liver Tissue Conclusion

The sections in this article are Introduction Nanofibrous Scaffolds Fabrication Methods for Nanofibrous Scaffolds Phase Separation Self-assembly Electrospinning The Electrospinning Process History Setup Mechanism and Working Parameters Properties of Electrospun Nanofibrous Scaffolds Architecture Porosity Mechanical Properties Current Development of Electrospun Nanofibrous Scaffolds in Tissue Engineering Evidence Supporting the Use of Nanofibrous Scaffolds in Tissue Engineering Nanofibrous Scaffolds Enhance Adsorption of Cell Adhesion Molecules Nanofibrous Scaffolds Induce Favorable Cell–ECM Interaction Nanofibrous Scaffolds Maintain Cell Phenotype Nanofibrous Scaffolds Support Differentiation of Stem Cells Nanofibrous Scaffolds Promote in vivo-like 3D Matrix Adhesion and Activate Cell Signaling Pathway Biomaterials Electrospun into Nanofibrous Scaffolds Natural Polymeric Nanofibrous Scaffolds Synthetic Polymeric Nanofibrous Scaffolds Composite Polymeric Nanofibrous Scaffolds Nanofibrous Scaffolds Coated with Bioactive Molecules Engineered Tissues using Electrospun Nanofibrous Scaffolds Skin Blood Vessel Cartilage Bone Muscle Ligament Nerve Current Challenges and Future Directions Conclusion

Bioreactors are essential in tissue engineering, not only because they provide an in vitro environment mimicking in vivo conditions for the growth of tissue substitutes, but also because they enable systematic studies of the responses of living tissues to various mechanical and biochemical cues. The basic principles of bioreactor design are reviewed, the bioreactors commonly used for the tissue engineering of cartilage, bone and cardiovascular systems are assessed in terms of their performance and usefulness. Several novel bioreactor types are also reviewed.

Most studies on articular cartilage properties have been conducted after detachment of the cartilage from the bone. In the present work we investigated the effect of detachment on collagen fiber architecture. We used one-dimensional 2 H double quantum filtered MRI on cartilage bone plugs equilibrated in deuterated saline. The quadrupolar splittings observed in the different zones were related to the degree of order and the density of the collagen fibers. The method is non-destructive, allowing for measurements on the same plug without the need for fixation, dehydration, sectioning and decalcification. Detachment of the radial from the calcified zone resulted in swelling of the cartilage plug in physiological saline and a concomitant decrease in the quadrupolar splitting. The effect of mechanical pressure on the 2 H quadrupolar splittings for the detached cartilage and for the calcified zone-bone plugs were compared with those of the same zones in the intact cartilage–bone plug. The splitting in the radial zone of the detached cartilage collapsed at much smaller loads compared to the intact cartilage–bone plug. The effect of the load on the size of the cartilage was also greater for the detached plug. These results indicate that anchoring of the cartilage to the bone through the calcified zone plays an important role in retaining the order of the collagen fibers. The water 2 H quadrupolar splitting in intact and proteoglycan-depleted cartilage was the same, indicating that the proteoglycans do not contribute to the ordering of the collagen fibers.

Analytical studies have shown that both blunt and shear stress are manifest at the tidemark that separates the calcified and uncalcified cartilage in the articular surface.1 This “essential lesion” of articular cartilage damage has subsequently been substantiated by cadaver and animal studies.2,3 The development of focal lesions of the articular surface is attributed to the progression of this essential deep lesion. Thus, the rationale behind osteochondral transfer is to replace the damaged cartilage bone unit with a healthy one.

As a very rapidly developing field of research, tissue engineering has been defined differently by many authors but one common aspect of its application is the study of the utilization of living cells to restore or create a lost or absent tissue structure or function (Fig. 1) [1,2,3].