Revealing the complexity of meniscus microvasculature through 3D visualization and analysis.

Three-dimensional information is essential for a proper understanding of the healing potential of the menisci and their overall role in the knee joint. However, to date, the study of meniscal vascularity has relied primarily on two-dimensional imaging techniques. Here we present a method to elucidate the intricate 3D meniscal vascular network, revealing its spatial arrangement, connectivity and density. A polymerizing contrast agent was injected into the femoral artery of human cadaver legs, and the meniscal microvasculature was examined using micro-computed tomography at different levels of detail and resolution. The 3D vascular network was quantitatively assessed in a zone-base analysis using parameters such as diameter, length, tortuosity, and branching patterns. The results of this study revealed distinct vascular patterns within the meniscus, with the highest vascular volume found in the outer perimeniscal zone. Variations in vascular parameters were found between the different circumferential and radial meniscal zones. Moreover, through state-of-the-art 3D visualization using micro-CT, this study highlighted the importance of spatial resolution in accurately characterizing the vascular network. These findings, both from this study and from future research using this technique, improve our understanding of microvascular distribution, which may lead to improved therapeutic strategies.

Garnet-Based Solid-State Li Batteries with High-Surface-Area Porous LLZO Membranes.

Rechargeable garnet-based solid-state Li batteries hold immense promise as nonflammable, nontoxic, and high energy density energy storage systems, employing Li7La3Zr2O12 (LLZO) with a garnet-type structure as the solid-state electrolyte. Despite substantial progress in this field, the advancement and eventual commercialization of garnet-based solid-state Li batteries are impeded by void formation at the LLZO/Li interface at practical current densities and areal capacities beyond 1 mA cm-2 and 1 mAh cm-2, respectively, resulting in limited cycling stability and the emergence of Li dendrites. Additionally, developing a fabrication approach for thin LLZO electrolytes to achieve high energy density remains paramount. To address these critical challenges, herein, we present a facile methodology for fabricating self-standing, 50 µm thick, porous LLZO membranes with a small pore size of ca. 2.3 µm and an average porosity of 51%, resulting in a specific surface area of 1.3 µm-1, the highest reported to date. The use of such LLZO membranes significantly increases the Li/LLZO contact area, effectively mitigating void formation. This methodology combines two key elements: (i) the use of small pore formers of ca. 1.5 µm and (ii) the use of ultrafast sintering, which circumvents ceramics overdensification using rapid heating/cooling rates of ca. 50 °C per second. The fabricated porous LLZO membranes demonstrate exceptional cycling stability in a symmetrical Li/LLZO/Li cell configuration, exceeding 600 h of continuous operation at a current density of 0.1 mA cm-2.

3D visualization of the human anterior cruciate ligament combining micro-CT and histological analysis.

PURPOSE: The study aimed to obtain a comprehensive 3D visualization of knee specimens, including the cruciate ligaments and corresponding femoral and tibial bone insertions using a non-destructive micro-CT method. METHODS: Knee specimens were fixed in anatomical positions and chemically dehydrated before being scanned using micro-CT with a voxel size of 17.5 µm. RGBA (red, green, blue, alpha) transfer functions were applied to virtually colorize each structure. Following micro-CT scanning, the samples were rehydrated, decalcified, and trimmed based on micro-CT 3D reconstructions as references. Histological evaluations were performed on the trimmed samples. Histological and micro-CT images were registered to morphologically and densitometrically assess the 4-layer insertion of the ACL into the bone. RESULTS: The output of the micro-CT images of the knee in extension and flexion allowed a clear differentiation of the morphologies of both soft and hard tissues, such as the ACL, femoral and tibial bones, and cartilage, and the subsequent creation of 3D composite models useful for accurately tracing the entire morphology of the ligament, including its fiber and bundle components, the trajectory between the femur and tibia, and the size, extension, and morphology of its insertions into the bones. CONCLUSION: The implementation of the non-destructive micro-CT method allowed complete visualization of all the different components of the knee specimens. This allowed correlative imaging by micro-CT and histology, accurate planning of histological sections, and virtual anatomical and microstructural analysis. The micro-CT approach provided an unprecedented 3D level of detail, offering a viable means to study ACL anatomy.

Quantitative Evaluation of the 3D Anatomy of the Human Osseous Spiral Lamina Using MicroCT.

PURPOSE: The osseous spiral lamina (OSL) is an inner cochlear bony structure that projects from the modiolus from base to apex, separating the cochlear canal into the scala vestibuli and scala tympani. The porosity of the OSL has recently attracted the attention of scientists due to its potential impact on the overall sound transduction. The bony pillars between the vestibular and tympanic plates of the OSL are not always visible in conventional histopathological studies, so imaging of such structures is usually lacking or incomplete. With this pilot study, we aimed, for the first time, to anatomically demonstrate the OSL in great detail and in 3D. METHODS: We measured width, thickness, and porosity of the human OSL by microCT using increasing nominal resolutions up to 2.5-µm voxel size. Additionally, 3D models of the individual plates at the basal and middle turns and the apex were created from the CT datasets. RESULTS: We found a constant presence of porosity in both tympanic plate and vestibular plate from basal turn to the apex. The tympanic plate appears to be more porous than vestibular plate in the basal and middle turns, while it is less porous in the apex. Furthermore, the 3D reconstruction allowed the bony pillars that lie between the OSL plates to be observed in great detail. CONCLUSION: By enhancing our comprehension of the OSL, we can advance our comprehension of hearing mechanisms and enhance the accuracy and effectiveness of cochlear models.

Oriented Porous NASICON 3D Framework via Freeze-Casting for Sodium-Metal Batteries.

Sodium-metal batteries are promising candidates for low-cost, large-format energy storage systems. However, sodium-metal batteries suffer from high interfacial resistance between the electrodes and the solid electrolyte, leading to poor electrochemical performance. We demonstrate a sodium superionic conductor (NASICON) with an oriented porous framework of sodium aluminum titanium phosphate (NATP) fabricated by the freeze-casting technique, which shows excellent properties as a solid electrolyte. Using X-ray computed tomography, we confirm the uniform low-tortuosity channels present along the thickness of the scaffold. We infiltrated the porous NATP scaffolds with sodium vanadium phosphate (NVP) cathode nanoparticles achieving mass loadings of ∼3-4 mg cm-2, which enables short sodium ion diffusion path lengths. For the resulting hybrid cell, we achieved a capacity of ∼90 mAh g-1 at a specific current of 50 mA g-1 (∼300 Wh kg-1) for over 100 cycles with ∼94% capacity retention. Our study offers valuable insights for the design of hybrid solid electrolyte-cathode active material structures to achieve improved electrochemical performance through low-tortuosity ion transport networks.

Bilayer Dense-Porous Li7 La3 Zr2 O12 Membranes for High-Performance Li-Garnet Solid-State Batteries.

Li dendrites form in Li7 La3 Zr2 O12 (LLZO) solid electrolytes due to intrinsic volume changes of Li and the appearance of voids at the Li metal/LLZO interface. Bilayer dense-porous LLZO membranes make for a compelling solution of this pertinent challenge in the field of Li-garnet solid-state batteries (SSB). Lithium is thus stored in the pores of the LLZO, thereby avoiding i) dynamic changes of the anode volume and ii) the formation of voids during Li stripping due to increased surface area of the Li/LLZO interface. The dense layer then additionally reduces the probability of short circuits during cell charging. In this work, a method for producing such bilayer membranes utilizing sequential tape-casting of porous and dense layers is reported. The minimum attainable thicknesses are 8-10 µm for dense and 32-35 µm for porous layers, enabling gravimetric and volumetric energy densities of Li-garnet SSBs of 279 Wh kg-1 and 1003 Wh L-1 , respectively. Bilayer LLZO membranes in symmetrical cell configuration exhibit high critical current density up to 6 mA cm-2 and cycling stability of over 160 cycles at a current density of 0.5 mA cm-2 at an areal capacity limitation of 0.25 mAh cm-2 .

Multibody Computer Model of the Entire Equine Forelimb Simulates Forces Causing Catastrophic Fractures of the Carpus during a Traditional Race.

A catastrophic fracture of the radial carpal bone experienced by a racehorse during a Palio race was analyzed. Computational modelling of the carpal joint at the point of failure informed by live data was generated using a multibody code for dynamics simulation. The circuit design in a turn, the speed of the animal and the surface characteristics were considered in the model. A macroscopic examination of the cartilage, micro-CT and histology were performed on the radio-carpal joint of the limb that sustained the fracture. The model predicted the points of contact forces generated at the level of the radio-carpal joint where the fracture occurred. Articular surfaces of the distal radius, together with the proximal articular surface of small carpal bones, exhibited diffuse wear lines, erosions of the articular cartilage and subchondral bone exposure. Even though the data in this study originated from a single fracture and further work will be required to validate this approach, this study highlights the potential correlation between elevated impact forces generated at the level of contact surfaces of the carpal joint during a turn and cartilage breakdown in the absence of pre-existing pathology. Computer modelling resulted in a useful tool to inversely calculate internal forces generated during specific conditions that cannot be reproduced in-vivo because of ethical concerns.

Otosclerosis under microCT: New insights into the disease and its anatomy.

Purpose: Otospongiotic plaques can be seen on conventional computed tomography (CT) as focal lesions around the cochlea. However, the resolution remains insufficient to enable evaluation of intracochlear damage. MicroCT technology provides resolution at the single micron level, offering an exceptional amplified view of the otosclerotic cochlea. In this study, a non-decalcified otosclerotic cochlea was analyzed and reconstructed in three dimensions for the first time, using microCT technology. The pre-clinical relevance of this study is the demonstration of extensive pro-inflammatory buildup inside the cochlea which cannot be seen with conventional cone-beam CT (CBCT) investigation. Materials and Methods: A radiological and a three-dimensional (3D) anatomical study of an otosclerotic cochlea using microCT technology is presented here for the first time. 3D-segmentation of the human cochlea was performed, providing an unprecedented view of the diseased area without the need for decalcification, sectioning, or staining. Results: Using microCT at single micron resolution and geometric reconstructions, it was possible to visualize the disease's effects. These included intensive tissue remodeling and highly vascularized areas with dilated capillaries around the spongiotic foci seen on the pericochlear bone. The cochlea's architecture as a morphological correlate of the otosclerosis was also seen. With a sagittal cut of the 3D mesh, it was possible to visualize intense ossification of the cochlear apex, as well as the internal auditory canal, the modiolus, the spiral ligament, and a large cochleolith over the osseous spiral lamina. In addition, the oval and round windows showed intense fibrotic tissue formation and spongiotic bone with increased vascularization. Given the recently described importance of the osseous spiral lamina in hearing mechanics and that, clinically, one of the signs of otosclerosis is the Carhart notch observed on the audiogram, a tonotopic map using the osseous spiral lamina as region of interest is presented. An additional quantitative study of the porosity and width of the osseous spiral lamina is reported. Conclusion: In this study, structural anatomical alterations of the otosclerotic cochlea were visualized in 3D for the first time. MicroCT suggested that even though the disease may not appear to be advanced in standard clinical CT scans, intense tissue remodeling is already ongoing inside the cochlea. That knowledge will have a great impact on further treatment of patients presenting with sensorineural hearing loss.

Bone Regeneration in Load-Bearing Segmental Defects, Guided by Biomorphic, Hierarchically Structured Apatitic Scaffold.

The regeneration of load-bearing segmental bone defects remains a significant clinical problem in orthopedics, mainly due to the lack of scaffolds with composition and 3D porous structure effective in guiding and sustaining new bone formation and vascularization in large bone defects. In the present study, biomorphic calcium phosphate bone scaffolds (GreenBone™) featuring osteon-mimicking, hierarchically organized, 3D porous structure and lamellar nano-architecture were implanted in a critical cortical defect in sheep and compared with allograft. Two different types of scaffolds were tested: one made of ion-doped hydroxyapatite/ß-tricalcium-phosphate (GB-1) and other made of undoped hydroxyapatite only (GB-2). X-ray diffraction patterns of GB-1 and GB-2 confirmed that both scaffolds were made of hydroxyapatite, with a minor amount of ß-TCP in GB-1. The chemical composition analysis, obtained by ICP-OES spectrometer, highlighted the carbonation extent and the presence of small amounts of Mg and Sr as doping ions in GB-1. SEM micrographs showed the channel-like wide open porosity of the biomorphic scaffolds and the typical architecture of internal channel walls, characterized by a cell structure mimicking the natural parenchyma of the rattan wood used as a template for the scaffold fabrication. Both GB-1 and GB-2 scaffolds show very similar porosity extent and 3D organization, as also revealed by mercury intrusion porosimetry. Comparing the two scaffolds, GB-1 showed slightly higher fracture strength, as well as improved stability at the stress plateau. In comparison to allograft, at the follow-up time of 6 months, both GB-1 and GB-2 scaffolds showed higher new bone formation and quality of regenerated bone (trabecular thickness, number, and separation). In addition, higher osteoid surface (OS/BS), osteoid thickness (OS.Th), osteoblast surface (Ob.S/BS), vessels/microvessels numbers, as well as substantial osteoclast-mediated implant resorption were observed. The highest values in OS.Th and Ob. S/BS parameters were found in GB-1 scaffold. Finally, Bone Mineralization Index of new bone within scaffolds, as determined by micro-indentation, showed a significantly higher microhardness for GB-1 scaffold in comparison to GB-2. These findings suggested that the biomorphic calcium phosphate scaffolds were able to promote regeneration of load-bearing segmental bone defects in a clinically relevant scenario, which still represents one of the greatest challenges in orthopedics nowadays.

Tensile and Impact Toughness Properties of a Zr-Based Bulk Metallic Glass Fabricated via Laser Powder-Bed Fusion.

In the past few years, laser powder-bed fusion (LPBF) of bulk metallic glasses (BMGs) has gained significant interest because of the high heating and cooling rates inherent to the process, providing the means to bypass the crystallization threshold. In this study, (for the first time) the tensile and Charpy impact toughness properties of a Zr-based BMG fabricated via LPBF were investigated. The presence of defects and lack of fusion (LoF) in the near-surface region of the samples resulted in low properties. Increasing the laser power at the borders mitigated LoF formation in the near-surface region, leading to an almost 27% increase in tensile yield strength and impact toughness. Comparatively, increasing the core laser power did not have a significant influence. It was therefore confirmed that, for BMGs like for crystalline alloys, near-surface LoFs are more detrimental than core LoFs. Although increasing the border and core laser power resulted in a higher crystallized fraction, detrimental to the mechanical properties, reducing the formation of LoF defects (confirmed using micro-computed tomography, Micro-CT) was comparatively more important.

Quality control methods in musculoskeletal tissue engineering: from imaging to biosensors.

Tissue engineering is rapidly progressing toward clinical application. In the musculoskeletal field, there has been an increasing necessity for bone and cartilage replacement. Despite the promising translational potential of tissue engineering approaches, careful attention should be given to the quality of developed constructs to increase the real applicability to patients. After a general introduction to musculoskeletal tissue engineering, this narrative review aims to offer an overview of methods, starting from classical techniques, such as gene expression analysis and histology, to less common methods, such as Raman spectroscopy, microcomputed tomography, and biosensors, that can be employed to assess the quality of constructs in terms of viability, morphology, or matrix deposition. A particular emphasis is given to standards and good practices (GXP), which can be applicable in different sectors. Moreover, a classification of the methods into destructive, noninvasive, or conservative based on the possible further development of a preimplant quality monitoring system is proposed. Biosensors in musculoskeletal tissue engineering have not yet been used but have been proposed as a novel technology that can be exploited with numerous advantages, including minimal invasiveness, making them suitable for the development of preimplant quality control systems.

Case Report: Anterior Cruciate Ligament Calcification in a Patient With Chondrocalcinosis: Micro-Computed Tomography Presentation.

In this case report, an incidental postoperative diagnosis of anterior cruciate ligament (ACL) calcification, associated with calcification of posterior cruciate ligament (PCL) and lateral meniscus insertions, was made using micro-computed tomography (µCT) technology in a knee specimen obtained during a total knee replacement (TKR) surgery due to painful tri-compartmental osteoarthritis (OA) with chondrocalcinosis signs at preoperative X-ray. Anterior cruciate ligament calcification is an uncommon finding, and conventional X-ray and MRI are not so helpful in its identification. µCT scan, in contrast, is of interest because it provides highly spatial three-dimensional information with excellent visualization of bones and calcifications. The µCT technology used in this case report allowed us to perform a detailed analysis and a 3-D reconstruction of the calcium pyrophosphate dihydrate (CPPD) crystal deposition about the knee without the need to section the specimens into slice as performed in previous studies. The 3-D model obtained with µCT scan permits to gain more insight into the shape of the calcification within the fibers of the ligamentous structures of the joint.

Multiscale and multimodal X-ray analysis: Quantifying phase orientation and morphology of mineralized turkey leg tendons.

Fibrous biocomposites like bone and tendons exhibit a hierarchical arrangement of their components ranging from the macroscale down to the molecular level. The multiscale complex morphology, together with the correlated orientation of their constituents, contributes significantly to the outstanding mechanical properties of these biomaterials. In this study, a systematic road map is provided to quantify the hierarchical structure of a mineralized turkey leg tendon (MTLT) in a holistic multiscale evaluation by combining micro-Computed Tomography (micro-CT), small-angle X-ray scattering (SAXS), and wide-angle X-ray diffraction (WAXD). We quantify the interplay of the main MTLT components with respect to highly ordered organic parts such as fibrous collagen integrating inorganic components like hydroxyapatite (HA). The microscale fibrous morphology revealing different types of porous features and their orientation was quantified based on micro-CT investigations. The quantitative analysis of the alignment of collagen fibrils and HA crystallites was established from the streak-like signal in SAXS using the Ruland approach and the broadening of azimuthal profiles of the small and wide-angle diffraction peaks. It has been in general agreement that HA crystallites are co-aligned with the nanostructure of mineralized tissue. However, we observe relatively lower degree of orientation of HA crystallites compared to the collagen fibrils, which supports the recent findings of the structural interrelations within mineralized tissues. The generic multiscale characterization approach of this study is relevant to any hierarchically structured biomaterials or bioinspired materials from the µm-nm-Å scale. Hence, it gives the basis for future structure-property relationship investigations and simulations for a wide range of hierarchically structured materials. STATEMENT OF SIGNIFICANCE: Many fibrous biocomposites such as tendon, bone, and wood possess multiscale hierarchical structures, responsible for their exceptional mechanical properties. In this study, the 3-dimensional hierarchical structure, the degree of orientation and composition of mineralized tendon extracted from a turkey leg were quantified using a multimodal X-ray based approach combining small-angle X-ray scattering and wide-angle X-ray diffraction with micro-Computed Tomography. We demonstrate that hydroxyapatite (HA) domains are co-aligned with the nanostructure of mineralized tissue. However, the lower degree of orientation of HA crystallites was observed when compared to the collagen fibrils. The generic multiscale characterization approach of this study is relevant to any hierarchically structured biomaterials or bioinspired materials from the micrometer over the nanometer to the Angström scale level.

A microcomputed tomography analysis of bone tissue after vertical ridge augmentation with non-resorbable membranes versus resorbable membranes and titanium mesh in humans.

PURPOSE: Guided bone regeneration is a frequently used surgical procedure for hard tissue reconstruction when horizontal and or/vertical augmentation are needed. The treatment concept is based on the application of occlusive membranes like non-resorbable membranes or titanium mesh plus resorbable membranes. However, there are no studies comparing the microcomputed tomography results for bone obtained using these two procedures, and this was the purpose of the present study. MATERIALS AND METHODS: A total of 40 patients with vertical posterior bone mandibular atrophy were randomly assigned to group A (guided bone regeneration with titanium-reinforced polytetrafluoroethylene membrane and simultaneous implant placement) or group B (guided bone regeneration with titanium mesh and collagen membrane and simultaneous implant placement). Tissue biopsy specimens were obtained from augmented sites after 9 months for microcomputed tomography analysis of volume of interest. Bone volume (BV/TV), biomaterial volume (MatV/TV), soft tissue volume (StV/TV), trabecular thickness (TbTh), trabecular number (TbN) and trabecular separation (TbSp) were measured. The correlation between regenerated bone and native bone was also evaluated. STATA software (StataCorp, College Station, TX, USA) was utilised for statistical analysis (significance α = 0.05). RESULTS: In group A, the values of BV/TV, MatV/TV and StV/TV in regenerated bone were 28.8%, 8.9% and 62.4%, respectively. In group B, the values of BV/TV, MatV/TV and StV/TV were 30.0%, 11.0% and 59.0%, respectively. No statistical differences were found between the two groups for any of the variables (P < 0.05). In both groups, considerable differences were noted between regenerated and native bone (P > 0.05), with a slight correlation between the microcomputed tomography parameters that suggests that native bone influences the quality of regenerated bone. CONCLUSIONS: Based on microcomputed tomography analysis, both surgical approaches facilitated the obtention of approximately 30% of newly formed bone with the same microarchitecture. Native bone influences the quality and microarchitecture of the obtained bone, irrespective of the technique used.

Three-dimensional imaging and reconstruction of the whole ovary and testis: a new frontier for the reproductive scientist.

The 3D functional reconstruction of a whole organ or organism down to the single cell level and to the subcellular components and molecules is a major future scientific challenge. The recent convergence of advanced imaging techniques with an impressively increased computing power allowed early attempts to translate and combine 2D images and functional data to obtain in-silico organ 3D models. This review first describes the experimental pipeline required for organ 3D reconstruction: from the collection of 2D serial images obtained with light, confocal, light-sheet microscopy or tomography, followed by their registration, segmentation and subsequent 3D rendering. Then, we summarise the results of investigations performed so far by applying these 3D image analyses to the study of the female and male mammalian gonads. These studies highlight the importance of working towards a 3D in-silico model of the ovary and testis as a tool to gain insights into their biology during the phases of differentiation or adulthood, in normal or pathological conditions. Furthermore, the use of 3D imaging approaches opens to key technical improvements, ranging from image acquisition to optimisation and development of new processing tools, and unfolds novel possibilities for multidisciplinary research.

Assessment of the in vivo biofunctionality of a biomimetic hybrid scaffold for osteochondral tissue regeneration.

Chondral and osteochondral lesions represent one of the most challenging problems in the orthopedic field, as these types of injuries lead to disability and worsened quality of life for patients and have an economic impact on the healthcare system. The aim of this in vivo study was to develop a new tissue engineering approach through a hybrid scaffold for osteochondral tissue regeneration made of porous polyurethane foam (PU) coated under vacuum with calcium phosphates (PU/VAC). Scaffold characterization showed a highly porous and interconnected structure. Human amniotic mesenchymal stromal cells (hAMSCs) were loaded into scaffolds using pectin (PECT) as a carrier. Osteochondral defects in medial femoral condyles of rabbits were created and randomly allocated in one of the following groups: plain scaffold (PU/VAC), scaffold with hAMSCs injected in the implant site (PU/VAC/hAMSC), scaffold with hAMSCs loaded in pectin (PU/VAC/PECT/hAMSC), and no treated defects (untreated). The therapeutic efficacy was assessed by macroscopic, histological, histomorphometric, microtomographic, and ultrastructural analyses at 3, 6, 12, and 24 weeks. Histological results showed that the scaffold was permissive to tissue growth and penetration, an immature osteocartilaginous tissue was observed at early experimental times, with a more accentuated bone regeneration in comparison with the cartilage layer in the absence of any inflammatory reaction.

Three-Dimensional Micro-Computed Tomography of the Adult Mouse Ovary.

In the mouse ovary, folliculogenesis proceeds through eight main growth stages, from small primordial type 1 (T1) to fully grown antral T8 follicles. Most of our understanding of this process was obtained with approaches that disrupted the ovary three-dimensional (3D) integrity. Micro-Computed Tomography (microCT) allows the maintenance of the organ structure and a true in-silico 3D reconstruction, with cubic voxels and isotropic resolution, giving a precise spatial mapping of its functional units. Here, we developed a robust method that, by combining an optimized contrast procedure with microCT imaging of the tiny adult mouse ovary, allowed 3D mapping and counting of follicles, from pre-antral secondary T4 (53.2 ± 12.7 µm in diameter) to antral T8 (321.0 ± 21.3 µm) and corpora lutea, together with the major vasculature branches. Primordial and primary follicles (T1-T3) could not be observed. Our procedure highlighted, with unprecedent details, the main functional compartments of the growing follicle: granulosa, antrum, cumulus cells, zona pellucida, and oocyte with its nucleus. The results describe a homogeneous distribution of all follicle types between the ovary dorsal and ventral regions. Also, they show that each of the eight sectors, virtually segmented along the dorsal-ventral axis, houses an equal number of each follicle type. Altogether, these data suggest that follicle recruitment is homogeneously distributed all-over the ovarian surface. This topographic reconstruction builds sound bases for modeling follicles position and, prospectively, could contribute to our understanding of folliculogenesis dynamics, not only under normal conditions, but, importantly, during aging, in the presence of pathologies or after hormones or drugs administration.

Vascular Supply and Bone Marrow Concentrate for the Improvement of Allograft in Bone Defects: A Comparative In Vivo Study.

BACKGROUND: Surgical repair of critical-sized bone defects still remains a big challenge in orthopedic surgery. Biological enhancement, such as growth factors or cells, can stimulate a better outcome in bone regeneration driven by well-established treatments such as allogenic bone graft. However, despite the surgical options available, correct healing can be slowed down or compromised by insufficient vascular supply to the injured site. MATERIALS AND METHODS: In this pilot study, critical size bone defects in rabbit radius were treated with allograft bone, in combination with vascular bundle and autologous bone marrow concentrate seeded onto a commercial collagen scaffold. Microtomographical, histological and immunohistochemical assessments were performed to evaluate allograft integration and bone regeneration. RESULTS: Results showed that the surgical deviation of vascular bundle in the bone graft, regardless from the addition of bone marrow concentrate, promote the onset of healing process at short experimental times (8 wk) in comparison with the other groups, enhancing graft integration. CONCLUSION: The surgical procedure tested stimulates bone healing at early times, preserving native bone architecture, and can be easily combined with biological adjuvant.

Histological and histomorphometric analysis of bone tissue after guided bone regeneration with non-resorbable membranes vs resorbable membranes and titanium mesh.

BACKGROUND: Guided bone regeneration (GBR) allows to achieve vertical ridge augmentation whether with nonresorbable membranes or resorbable membranes with Ti-mesh, but till now no studies are published comparing histological and histomorphometrical outcomes of these two procedures. MATERIALS AND METHODS: Forty partially edentulous patients required vertical bone regeneration to place implants in the posterior mandible: 20 patients were randomly assigned to group A (Ti-PTFE); while 20 patients to group B (Collagen plus Ti-mesh). For both groups, graft material was a 50:50 mixture of autogenous bone and bone allograft. After 9 months, tissue biopsies were taken from augmented sites (regenerated bone ROI-1; native bone ROI-2) and undergone to histological and histomorphometric analysis. Percentages of bone tissue (B.Ar), biomaterial (Mat. Ar), and soft tissue (St.Ar) were measured; measurements of perimeters were calculated too. ROI-1 values were also compared to ROI-2 in both groups. RESULTS: Twenty-five samples were collected and analyzed consecutively: 13 in group A and 12 in group B. The mean B.Ar, Mat.Ar, and St.Ar were 39.7%, 8.6%, and 52.1% in group A; similar results were obtained in group B, with mean values of 42.1%, 9.6%, and 48.3%, respectively. No significant statistically differences were observed. Differences were observed between ROI-1 and ROI-2 in both group. Finally, bone structure index of ROI-1 and ROI-2 showed statistical differences. CONCLUSIONS: The preliminary results of this study suggest that GBR using nonresorbable membranes and Ti-mesh with resorbable membranes in combination with autogenous bone and bone allograft provide similar histological and histomorphometric results.