Osseous Layer Research Articles

A One-Stone-Two-Birds Strategy for Osteochondral Regeneration Based on a 3D Printable Biomimetic Scaffold with Kartogenin Biochemical Stimuli Gradient.

Osteochondral defect (OCD) regeneration remains challenging because of the hierarchy of the native tissue including both the articular cartilage and the subchondral bone. Constructing an osteochondral scaffold with biomimetic composition, structure, and biological functionality is the key to achieve its high-quality repair. In the present study, an injectable and 3D printable bilayered osteochondral hydrogel based on compositional gradient of methacrylated sodium alginate, gelatin methacryloyl, and β-tricalcium phosphate (β-TCP), as well as the biochemical gradient of kartogenin (KGN) in the two well-integrated zones of chondral layer hydrogel (CLH) and osseous layer hydrogel (OLH) is developed. In vitro and subcutaneous in vivo evaluations reveal that apart from the chondrogenesis of the embedded bone mesenchymal stem cells induced by CLH with a high concentration of KGN, a low concentration of KGN with β-TCP in the OLH synergistically achieves superior osteogenic differentiation by endochondral ossification, instead of the intramembranous ossification using OLH with only β-TCP. The biomimetic construct leveraging KGN as the only biochemical inducer can facilitate cartilage and subchondral bone restoration in the in vivo osteochondral defect. This one-stone-two-birds strategy opens up a new facile approach for OCD regeneration by exploiting the biological functions of the bioactive drug molecule KGN.

Biomimetic Mineralization in External Layer of Decalcified Fish Scale

The mineralization process of the osseous layer, which is highly calcified in vivo, was successfully imitated by the immersion process of the decalcified fish scales in simplified simulated body fluid (SSBF). An alkali treatment was used to modify the native collagen in the decalcified Tilapia fish scale. After the alkali treatment, the mineralization was facilitated in SSBF. The XRD patterns and SEM-EDS observation results demonstrated that the externally-mineralized layers by the immersion process were highly similar to the osseous layer containing lower-crystalline hydroxyapatite, suggesting that the simple biomimetic precipitation process was developed.

Integrated gradient tissue-engineered osteochondral scaffolds: Challenges, current efforts and future perspectives.

The osteochondral defect repair has been most extensively studied due to the rising demand for new therapies to diseases such as osteoarthritis. Tissue engineering has been proposed as a promising strategy to meet the demand of simultaneous regeneration of both cartilage and subchondral bone by constructing integrated gradient tissue-engineered osteochondral scaffold (IGTEOS). This review brought forward the main challenges of establishing a satisfactory IGTEOS from the perspectives of the complexity of physiology and microenvironment of osteochondral tissue, and the limitations of obtaining the desired and required scaffold. Then, we comprehensively discussed and summarized the current tissue-engineered efforts to resolve the above challenges, including architecture strategies, fabrication techniques and in vitro/in vivo evaluation methods of the IGTEOS. Especially, we highlighted the advantages and limitations of various fabrication techniques of IGTEOS, and common cases of IGTEOS application. Finally, based on the above challenges and current research progress, we analyzed in details the future perspectives of tissue-engineered osteochondral construct, so as to achieve the perfect reconstruction of the cartilaginous and osseous layers of osteochondral tissue simultaneously. This comprehensive and instructive review could provide deep insights into our current understanding of IGTEOS.

Factors Contributing to Graft Matching in a Patellar Osteochondral Allograft Selection Model (211)

Objectives:Patellar osteochondral allograft (OA) transplantation has been shown to be a successful treatment in patients with isolated patellar cartilage injury. Currently, there is minimal guidance in anatomic and sizing factors that portend similar patellar surface topography. The most commonly utilized patellar sizing criteria to match the donor and recipient is radiographic tibial width. Our hypothesis is that specific patella anatomic factors will better predict surface topography matching. To our knowledge, no prior study has investigated the topography of the patella and what intrinsic factors of the graft and the recipient affect matching of the chondral and osseous layers between the graft and defect.Methods:Computed tomography (CT) images of the specimens were acquired and three-dimensional (3D) CT models of the patella were then created and exported into point-cloud models using a 3D reconstruction software program. Circular articular cartilage and subchondral bone defect models were created in each point-cloud model of the recipient patella with a diameter of 18 mm and 22.5 mm at 3 locations: the medial, central, and lateral portions of the patellar surface. Circular articular cartilage and subchondral bone graft models were created on all possible locations on the articular cartilage surface models of the donor patellae (Figure 1). The graft models were virtually placed on the surface of the defect model. Orientation of the graft model was adjusted so that its axis matched that of the defect site. Least distances between the graft and the defect articular surface models were calculated and were defined as the shortest distance from the point in question to the corresponding point in space. A mean value of the least distances was calculated for each position of the graft model. The mean least distance of subchondral bone surface in each point was calculated simultaneously. The graft model was then rotated 360° around the axis perpendicular to the articular cartilage surface in 1° increments, and the least distance of articular cartilage surface and the resulting least distance of subchondral bone surface were calculated at each rotating angle. This procedure was repeated for all points in the articular surface model of the donor patella. Step-off was then calculated as the least mean square difference between the defect and graft along the periphery. Stepwise linear regression was used for each defect location to analyze which variables predict degree of mismatch in millimeters.Results:A total of 16 patella were utilized in analysis. Comparison of cartilage least mean square distances between locations demonstrated that the lateral location had significantly less surface incongruity compared to the other two locations (vs medial: p = .0038, vs central: p = .0046). In addition, significant differences in subchondral bone distances were observed between the locations (lateral vs medial: p = .0007, lateral vs central: p < .0001, medial vs central: p < .0001) (Table 1). The associations of six anatomic and morphologic variables with cartilage mismatch, bone mismatch, and step-off for 18 mm and 22.5 mm defects are presented in Tables 2 and Table 3. All variables were analyzed as the difference in value between the recipient and donor. For both lesion sizes, cartilage step-off was the most susceptible to variable differences. Compared to the 18 mm defect group, the 22.5 mm defects were more affected (higher coefficients) by the same differences in variables. Differences in tibial width were associated mismatch for central lesions (eg. 22.5mm defect coefficient: -0.026, p < .001), while cartilage width was associated with mismatch for lateral lesions. (eg. 22.5 mm defect coefficient: -0.034, p < .023).Conclusions:Multiple clinically relevant factors were found to affect graft and defect chondral mismatch and to a lesser extent osseous mismatch. For all three locations at both defect sizes, step-off was the most susceptible to differences in patellar morphology between the donor and recipient. In addition, differences in tibial width, a commonly used metric for patellar graft matching, did not significantly predict chondral mismatch for lateral and medial sized lesions. These findings should be considered when selecting and preparing the graft in a patella osteochondral allograft procedure.

Factors contributing to graft matching in a patellar osteochondral allograft selection model

Objectives:When performing a patellar osteochondral allograft, the patellar allograft is harvested from a similar anatomic location as the defect. This approach assumes that graft will have similar topography to the patellar defect. However, to our knowledge, no prior study has investigated the topography of the patella and what intrinsic factors of the graft and the recipient affect mismatch of the chondral and osseous layers between the graft and defect.Methods:Three-dimensional (3D) computed tomography (CT) models of the patella were created and exported into point-cloud models using a 3D reconstruction program (Mimics, Materialise Inc., Leuven, Belgium). Circular articular cartilage and subchondral bone defect models were created in each model of the recipient patella (diameter=18mm) at 3 locations: medial, distal, and lateral. Articular cartilage and subchondral bone graft models were created on all possible locations on the articular cartilage surface models of the donor patellae. 3D surface topographies of the articular cartilage surface and resulting subchondral bone surfaces were compared between graft and defect models. The graft models were virtually placed on the surface of the defect model. Least distances, defined as the shortest distance from the point in question to the corresponding point in space, where a perfect congruent match would equal a least distance of 0.00mm for given data points on the simulated articular cartilage surface, were calculated. A mean value of the least distances was calculated for each position of the graft model and for the subchondral bone surface, simultaneously. The graft model was then rotated 360° around the axis perpendicular to the articular cartilage surface in 1° increments, and the least distance of articular cartilage surface and least distance of subchondral bone surface were calculated at each rotating angle. This procedure was repeated for all points in the articular surface model of the donor patella. The 3D model creation and geometry matching were performed using a custom-written program coded by in Microsoft Visual C++ with Microsoft Foundation Class programming environment (Microsoft Corp., Redmond, WA). Multivariate linear regression analysis was conducted in SPSS (v26, IBM, Armonk, NY).Results:Chondral and osseous mismatch between the graft and defect were analyzed. ANOVA analysis on the multivariate linear regressions found significant predictors of cartilage mismatch for medial (p=0.002), lateral (p=0.022), and central (p=0.001) defects when testing 5 variables. However, no predicting variables were identified for osseous mismatch for medial (p=0.099), lateral (p=0.703), and central (p=0.641) defects. Differences in tibia width (p=0.005), bone width (p=0.004), and medial cartilage length (p=0.003) were predictive of mismatch in medial defects. When evaluating lateral defects, no variables were found to significantly effect mismatch, However, in this lateral defect group, the collinearity assumption of the regression was violated, as the VIF for bone width and lateral length were over 10. For the central group, difference in bone width (p=0.037), difference in percent of patella that was medial facet (p=0.001), and difference in tibial width (p=0.006) were predictive of mismatch.Conclusions:Differences between graft and recipient tibia width, bone width, and size of the medial or lateral facet are significant predictors of mismatch in patella allograft selection.

Changes in Cartilage and Subchondral Bone of Femoral Trochlear Groove After Patellectomy in Growing Rabbits.

ObjectiveTo explore the effects of patellectomy on the bony and cartilaginous morphology of the trochlear groove in growing rabbits.MethodsForty‐eight 4‐week‐old New Zealand white rabbits were randomly assigned to two groups. The control group underwent a sham surgical procedure, whereas the patellectomy group underwent patella excision surgery. Half of the rabbits in each group were sacrificed 3 months postoperatively; the rest were sacrificed 6 months postoperatively. Hematoxylin and eosin staining was performed on collected samples. Measurements included the bony and cartilaginous sulcus angles of the trochlear groove. In addition, the thickness of the articular cartilage at the deepest sulcus position (central thickness) and at the mid‐position of the medial and lateral facets was measured and compared between groups.ResultsThree months after surgery, histological images revealed significant differences between the control group and the patellectomy group in cartilaginous sulcus angle (144.2° ± 1.5° vs 151.9° ± 2.4°, respectively; P < 0.001). No obvious difference in bony sulcus angle was found between the groups. Six months after surgery, significant between‐group differences were observed in cartilaginous sulcus angle (136.3° ± 2.5° in control group vs 160.7° ± 3.0° in patellectomy group, P < 0.001) and bony sulcus angle (136.2° ± 2.2° in control group vs 160.4° ± 2.6° in patellectomy group, P < 0.001). However, there were no significant intra‐group differences between cartilaginous and bony sulcus angles in either group. Three months after surgery, significant between‐group differences were detected in articular cartilage thickness at the three different positions (medial facet: 324.3 ± 14.0 μm in control group vs 391.7 ± 98.8 μm in patellectomy group, P = 0.029; central position: 362.1 ± 13.6 μm in control group vs 730.3 ± 76.8 μm in patellectomy group, P < 0.001; lateral facet: 324.6 ± 12.7 μm in control group vs 358.5 ± 38.7 μm in patellectomy group, P = 0.009). No between‐group differences in cartilage thickness were found at 6 months.ConclusionsAbnormal mechanical stress (patellectomy) during a rabbit's development can cause flattening of the femoral trochlear cartilage, followed by changes in the subchondral osseous layer. Abnormal mechanical stress is a crucial factor in the development of trochlear groove dysplasia.

Restoration of osteochondral defects by implanting bilayered poly(lactide-co-glycolide) porous scaffolds in rabbit joints for 12 and 24 weeks

BackgroundWith the ageing of the population and the increase of sports injuries, the number of joint injuries has increased greatly. Tissue engineering or tissue regeneration is an important method to repair articular cartilage defects. While it has recently been paid much attention to use bilayered porous scaffolds to repair both cartilage and subchondral bone, it is interesting to examine to what extent a bilayer scaffold composed of the same kind of the biodegradable polymer poly(lactide-co-glycolide) (PLGA) can restore an osteochondral defect. Herein, we fabricated bilayered PLGA scaffolds and used a rabbit model to examine the efficacy of implanting the porous scaffolds with or without bone marrow mesenchymal stem cells (BMSCs). The present manuscript reports the regenerative potential up to 24 weeks. MethodsThe osteochondral defect, 4 mm in diameter and 5 mm in depth, was created in the medial condyle of each knee in 23 rabbits. The bilayered PLGA scaffolds with a pore size of 100–200 μm in the chondral layer and a pore size of 300–450 μm in the osseous layer, seeded with or without BMSCs in the chondral layer, were then transplanted into the osteochondral defect of each knee. The osteochondral defect created in the same manner was untreated to act as the control. At 12 and 24 weeks postoperatively, condyles were harvested and analyzed using histology, immunohistochemistry, real-time polymerase chain reaction, and biomechanical testing to evaluate the efficacy of osteochondral repair. ResultsNo joint erosion, inflammation, swelling, or deformity was observed, and all animals maintained a full range of motion. Compared with the untreated blank group, the groups implanting the bilayered scaffolds with or without cells exhibited much better resurfacing, similar to the surrounding normal tissue. The histological scores of neotissues repaired by the scaffold with cells were closer to that of normal tissue. Although the biomechanical properties of neotissues were not as good as the normal tissue, no significant difference was found between the gene levels of neotissues repaired by the scaffold with or without cells and that of the normal tissue. The repair of the osteochondral defect tends to be stable 12 weeks after implantation. ConclusionsOur bilayered PLGA porous scaffold supports long-term osteochondral repair via in vivo tissue engineering or regeneration, and its effect can be further facilitated under the scaffold seeded with allogenic BMSCs. The translational potential of this articleThe bilayered PLGA porous scaffold can facilitate the repair of osteochondral defects and has potential for application in osteochondral tissue engineering.

Analysis of the Intrinsic Self-Organising Properties of Mesenchymal Stromal Cells in Three-Dimensional Co-Culture Models with Endothelial Cells.

Mesenchymal stem/stromal cells (MSCs) are typically characterised by their ability to differentiate into skeletal (osteogenic, chondrogenic and adipogenic) lineages. MSCs also appear to have additional non-stem cell functions in coordinating tissue morphogenesis and organising vascular networks through interactions with endothelial cells (ECs). However, suitable experimental models to examine these apparently unique MSC properties are lacking. Following previous work, we have developed our 3D in vitro co-culture models to enable us to track cellular self-organisation events in heterotypic cell spheroids combining ECs, MSCs and their differentiated progeny. In these systems, MSCs, but not related fibroblastic cell types, promote the assembly of ECs into interconnected networks through intrinsic mechanisms, dependent on the relative abundance of MSC and EC numbers. Perturbation of endogenous platelet-derived growth factor (PDGF) signalling significantly increased EC network length, width and branching. When MSCs were pre-differentiated towards an osteogenic or chondrogenic lineage and co-cultured as mixed 3D spheroids, they segregated into polarised osseous and chondral regions. In the presence of ECs, the pre-differentiated MSCs redistributed to form a central mixed cell core with an outer osseous layer. Our findings demonstrate the intrinsic self-organising properties of MSCs, which may broaden their use in regenerative medicine and advance current approaches.

Complex joint reconstruction and joint transplantation with the FLOCSAT concept-planning and surgical implementation

Cartilage defects in adult patients are so far incurable. Fresh osteochondral allograft (OCA) transplantation is based on the insertion of mature, living, mechanically sound hyaline cartilage into an osteochondral defect where it undergoes osseointegration. Intact hyaline cartilage of OCA does not cause immune reactions in the recipient. Many reports show that small OCA have good osseointegration and show good long-term results. These observations have been incorporated into the development of the fresh large (> 10 cm2) osteochondral shell allograft transplantation (FLOCSAT) concept, which is based on the following principles: 1) the thickness of the osseous layer should be kept as thin as possible (target < 6-8 mm) so that the transplant remains stable and fixable. This results in reduced segments of vascularization, simplified ossification and reduced immunogenic bone volume. 2) The bone surface is processed and enlarged (oscillating saw: pie crust technique, drill holes) and areas of sclerosis are simultaneously broken off. 3) Cell reduction and washing out of the bony layer with a pulsatile jet lavage. 4) Prevention of impaction and dessication: cartilage with its living chondrocytes are very sensitive to mechanical contusion and dessication. When introducing the transplant, the tissue must therefore be continually moistened and the pressure acting on the cartilage must be controlled. 5) Stable fixation: extensive uniplanar osteochondral transplants cannot be inserted by the press-fit method; therefore, fixation is carried out with small implants. In this publication we demonstrate how severe and complex posttraumatic or degenerative delayed problems can be solved using FLOCSAT.

Unique Structure and Mechanical Property of Dabryanus Scale

The structure and mechanical property of Dabryanus scale were investigated. Environmental Scanning Electron Microscopy (ESEM) and Transmission Electron Microscopy (TEM) were used to observe the scale structure. The scale has a discrete osseous layer which is composed of boat-like unit (due to the shape). The osseous layer is embedded into fibrillary layer, and the largest thickness ratio of osseous layer to fibrillary layer is about 7, much higher than those of other reported fish scales. Nanoindentation test was used to investigate mechanical property of the scale. Elastic modulus (Er) and hardness (H) of Dabryanus scale are much lower than those of other reported fish scales. Scale models were proposed and the principles of materials mechanics were used to analyze the mechanical properties of the Dabryanus scale. The boat-like unit in osseous layer makes the scale flexible while keeping a high thickness ratio of osseous layer to fibrillary layer, which increases the flexibility and protection capacity of the scale This study may provide new strategy for the design of flexible armor or flexible devices.

Development and Characterization of Chemical Cochleostomy in the Guinea Pig

Objectives: Creation of an atraumatic, hearing-preservation cochleostomy is integral to the future of minimally invasive inner ear surgery. Current techniques generally take 1 of 2 approaches: mechanical or thermal. The goal of this study was to develop and characterize a novel chemical approach to cochleostomy. Methods: Experimental animal study in which phosphoric acid gel (PAG) was used to decalcify the otic capsule in 25 Hartley guinea pigs. Five animals in each of 5 groups were studied: (1) mechanically opening the auditory bulla alone, (2) PAG thinning of the basal turn otic capsule, leaving endosteum covered by a layer of bone, (3) micro-pick manual cochleostomy, (4) PAG chemical cochleostomy, exposing the endosteum, and (5) combined PAG/micro-pick cochleostomy, with initial chemical thinning and subsequent manual removal of the last osseous layer. Preoperative and postoperative auditory brainstem responses and otoacoustic emissions were obtained at 2, 6, 10, and 16 kHz. Hematoxylin and eosin stained paraffin sections were compared. Results: Surgical and histologic findings confirmed that application of PAG provided reproducible local bone removal, and cochlear access was enabled. Statistically significant auditory threshold shifts were observed at 10 and 16 kHz following cochleostomy using PAG alone (group 4), and at 16 kHz using manual cochleostomy (group 3) ( P &lt; .05). No statistically significant postoperative auditory threshold shifts were observed in the other groups, including PAG thinning with manual completion cochleostomy (group 5). Conclusions: Hearing preservation cochleostomy can be performed in an animal model using a novel technique of thinning cochlear bone with PAG and manually completing cochleostomy.

Bilateral Double-Layered Patella: MRI Findings and Fusion with Multiple Headless Screws: A Case Report.

The double-layered patella (DLP) was first described by Buttner in 19251. It is a rare entity that is often associated with an autosomal recessive form of multiple epiphyseal dysplasia (MED) caused by a homozygous diastrophic dysplasia sulfate transporter (DTDST) gene mutation2-5, although COMP6 and COL9A27 deletions have also been reported to cause DLP. DLP is a relatively mild form of MED, and clinical findings are often limited to bilateral recurrent anterior knee pain and early-onset hip osteoarthritis (C653S homozygous DTDST gene)2 as well as mild brachydactyly and clubfoot deformity (R279W homozygous DTDST gene)8. If the soft-tissue interface between the anterior and posterior osseous layers in DLP is stable and allows for little motion, patients may be asymptomatic. In these cases, DLP is often discovered incidentally as part of a broader diagnostic evaluation for MED9. However, if the soft-tissue interface is unstable, considerable motion can occur between the two ossified layers, which can cause symptoms, particularly during knee extension. This can present as a sensation of locking, giving way, or subluxation2, or alternatively as painful clicking or a snapping sensation with flexion near 30° to 40° 10,11. There is very limited information regarding the surgical treatment of symptomatic DLP. In several prior reports, a good clinical outcome was achieved with debridement of the soft-tissue interface and fusion of the osseous layers with screws10-12. In a patient with DLP who had undergone unsuccessful soft-tissue stabilization (Ali-Krogius procedure13), Hinrichs et al. utilized a tibial tuberosity medialization addition to a second soft-tissue stabilization2. We present a case of symptomatic bilateral DLP in an adolescent who was treated with fusion with use of four headless screws. The patient’s parents were …

The effects of pore size in bilayered poly(lactide-co-glycolide) scaffolds on restoring osteochondral defects in rabbits

Bilayered porous scaffolds have recently attracted interest because of their considerable promise for repairing osteochondral defects. However, determination of optimal pore size in bilayered porous scaffolds remains an important issue. This study investigated the in vivo effects of pore size in bilayered scaffolds using a rabbit model of osteochondral defects. We fabricated five types of integrated bilayered poly(lactide-co-glycolide) (PLGA) scaffolds with different pore sizes in the chondral and osseous layers (50-100 µm, 100-200 µm, 200-300 µm, and 300-450 µm). A subset of bilayered scaffolds seeded with or without allogenic bone marrow mesenchymal stem cells (BMSCs) was implanted in rabbit osteochondral defects. All of the cell/scaffold composite constructs supported the simultaneous regeneration of articular cartilage and subchondral bone, but the best results were observed in cell-seeded PLGA scaffolds with 100-200 µm pores in the chondral layer and 300-450 µm pores in the osseous layer. Our study supports the concept that the effects of pore size on osteochondral repair should be taken into consideration during scaffold design for tissue engineering.

Engineering osteochondral constructs through spatial regulation of endochondral ossification

Chondrogenically primed bone marrow-derived mesenchymal stem cells (MSCs) have been shown to become hypertrophic and undergo endochondral ossification when implanted in vivo. Modulating this endochondral phenotype may be an attractive approach to engineering the osseous phase of an osteochondral implant. The objective of this study was to engineer an osteochondral tissue by promoting endochondral ossification in one layer of a bilayered construct and stable cartilage in the other. The top half of bilayered agarose hydrogels were seeded with culture expanded chondrocytes (termed the chondral layer) and the bottom half of the bilayered agarose hydrogels with MSCs (termed the osseous layer). Constructs were cultured in chondrogenic medium for 21days and thereafter were either maintained in chondrogenic medium, transferred to hypertrophic medium, or implanted subcutaneously into nude mice. This structured chondrogenic bilayered co-culture was found to enhance chondrogenesis in the chondral layer, appearing to help re-establish the chondrogenic phenotype that is lost in chondrocytes during monolayer expansion. Furthermore, the bilayered co-culture appeared to suppress hypertrophy and mineralization in the osseous layer. The addition of hypertrophic factors to the media was found to induce mineralization of the osseous layer in vitro. A similar result was observed in vivo where endochondral ossification was restricted to the osseous layer of the construct, leading to the development of an osteochondral tissue. This novel approach represents a potential new treatment strategy for the repair of osteochondral defects.

The layer concept: utilization in determining the pain generators, pathology and how structure determines treatment

The level of understanding of pain in the non-arthritic hip has made significant strides in the last couple of decades beginning with the discoveries of Reinhold Ganz, MD. However, even with the detection of subtle bony abnormalities, including femoroacetabular impingement, a clinician's ability to differentiate pain generators in the hip has been ambiguous. Deciphering the etiology of the pathology versus the pain generator is essential in prescribing the proper treatment. The Layer Concept developed by Dr. Bryan Kelly, is a systematic means of determining which structures about the hip are the source of the pathology, which are the pain generators and how to then best implement treatment. Four layers will be discussed in this article. Layer I, the osseous layer, Layer II, the inert tissue layer, Layer III, the contractile layer and Layer IV, the neuromechanical layer.

High Resolution Scanning Electron Microscope Examination of the Fish Scale: Inspiration for Novel Biomaterials

A Scanning Electron Microscopic study on the fish scale of Cyprinus carpio communis (freshwater carp), depicts remarkable structural and compositional characteristics which may be used as inspiration for novel biomaterial design. The fracture surface structure and sintered fish scale reveals an osseous layer on its dorsal side. It has a compact heterogeneous crystalloid-like structure of assorted shapes and sizes. The ventral side is made of orthogonally arranged mineralized needle like crystalloids template embedded in a fibrillary plate. Frozen scales revealed that this dorsal layer may contain high atomic number elements as it appeared bright with back scattered electron signals. The ventral side consists of collagen plates and a matrix, which are arranged orthogonally in a double-twisted, plywood-like structure. There are alternate crystalloid and matrix which are arranged orthogonally and forming 15-17 layers in between these two sides. This provides useful information of scale composition. Design features from the structure of the fish scale may be useful in the development of functional biomaterials, in various different fields including nano-composites, biopolymers and natural source of hydroxyapatite, used in applied therapeutic, pharmaceutical industries and semiconductor technology. The tolerance of the fish scale to high temperature and very low temperature cooling revealed unique characteristics for biomaterial fabrication. The orthogonally arranged ventral side plates of collagen embedded in proteoglycans may also prove to be a good source of scaffold material for cell culturing for tissue engineering.

Multimodality bonchoscopic imaging of tracheopathica osteochondroplastica

Results of a commercial optical coherence tomography system used as part of a multimodality diagnostic bronchoscopy platform are presented for a 61-year-old patient with central airway obstruction from tracheopathica osteochondroplastica. Comparison to results of white-light bronchoscopy, histology, and endobronchial ultrasound examination are accompanied by a discussion of resolution, penetration depth, contrast, and field of view of these imaging modalities. White-light bronchoscopy revealed irregularly shaped, firm submucosal nodules along cartilaginous structures of the anterior and lateral walls of the trachea, sparing the muscular posterior membrane. Endobronchial ultrasound showed a hyperechoic density of 0.4 cm thickness. optical coherence tomography (OCT) was performed using a commercially available, compact time-domain OCT system (Niris System, Imalux Corp., Cleveland, Ohio) with a magnetically actuating probe (two-dimensional, front imaging, and inside actuation). Images showed epithelium, upper submucosa, and osseous submucosal nodule layers corresponding with histopathology. To our knowledge, this is the first time these commercially available systems are used as part of a multimodality bronchoscopy platform to study diagnostic imaging of a benign disease causing central airway obstruction. Further studies are needed to optimize these systems for pulmonary applications and to determine how new-generation imaging modalities will be integrated into a multimodality bronchoscopy platform.

Surgical management of a double-layered patella: a case report

The double-layered patella (DLP) is a rare intra-articular disorder that in most cases is associated with multiple epiphyseal dysplasia (MED). The DLP usually consists of an anterior and a posterior layer with a cartilaginous interface between the two parts. In this article, we present a case of bilateral DLP of a 17-year-old female adolescent with MED, suffering clinical symptoms on her left knee. Upon clinical examination, a painful "snapping" of the patella at 30-40 degrees flexion of the left knee was evident and two osseous layers could be identified in standard radiographs. Arthroscopic examination revealed a transient cranial displacement of the posterior osteochondral layer at 30-40 degrees knee flexion that replaced beyond 40 degrees knee flexion with a visible jump. Surgical management in this case of DLP comprised open debridement of the soft tissue interface and fusion of the two osseous layers using double-threaded screws leading to an excellent outcome at 12 months follow-up.

Skull base tumors: assessment of intracranial extension

The skull base is one of the most complex regions of the human body. When tumors arise in this area, the close topographic relationship of soft tissue structures, often separated only by an osseous layer, generally necessitates sensitive diagnostic and complex therapeutic procedures.Different imaging modalities are used to examine lesions of the skull base, the most important of which is magnetic resonance imaging (MRI).There are two primary issues that must be addressed and tackled by the radiologist; first, the identity of the tumor which, by using both anatomic location and imaging characteristics, can lead to a best approximation of the diagnosis preoperatively. Second, the precise definition of the spread and extent of the lesion, which usually occurs by direct invasion to neighboring structures or to the bony skull base or by perineural extension along cranial nerves.This review article will discuss detection and diagnosis of intracranial extension of skull base tumors by different imaging modalities.

Influence of cartilage cap modelling on FEM simulation of femoral head stress

The present study reports on the finite element analysis (FEA) of the femoral head in a process of preparation for a program for the realistic simulation of correctional osteotomies of the proximal femur. While the material properties have been studied extensively, only few publications consider the influence of the cartilage layer geometry on FE stimulation of the hip joint. Various models of the femoral head with and without the cartilage layer are generated and analysed. On looking at the maximum surface stresses, we found a strong influence of the cartilage layer and the subchondral osseous layer on the magnitude of the von Mises equivalent stress. The model with an anatomically realistic cartilage layer and compact bone shows stresses of between 4 and 5.5 MPa, depending on the position of the joint, while the model with a concentric cartilage layer has a maximum von Mises stress of 0.8 MPa. Only on simulation of a "realistic" cartilage layer, with a maximum thickness at the "pole" and minimum thickness at the "equator" do the changes in stress distribution--determined by changes in the position of the femoral head--become visible. Owing to major artefacts and the inability to create a realistic cartilage layer, voxel-based models of the femur are not suitable for the simulation of the femoral head surface.