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Finite element (FE) simulations can be used to evaluate the mechanical behavior of human bone and allow for quantitative prediction of press-fit implant fixation. An adequate material model that captures post-yield behavior is essential for a realistic simulation. The crushable foam (CF) model is a constitutive model that has recently been proposed in this regard. Compression tests under uniaxial and confined loading conditions were performed on 59 human trabecular bone specimens. Three essential material parameters were obtained as a function of bone mineral density (BMD) to develop the isotropic CF model. The related constitutive rule was implemented in FE models and the results were compared to the experimental data. The CF model provided an accurate simulation of uniaxial compression tests and the post-yield behavior of the stress-strain was well-matched with the experimental results. The model was able to reproduce the confined response of the bone up to 15% of strain. This model allows for simulation of the mechanical behavior of the cellular structure of human bone and adequately predicts the post-yield response of trabecular bone, particularly under uniaxial loading conditions. The model can be further improved to simulate bone collapse due to local overload around orthopaedic implants.

With the advancement of aberration correction techniques, transcranial ultrasound imaging has exhibited great potential in applications such as imaging neurological function and guiding therapeutic ultrasound. However, the feasibility of transcranial imaging varies among individuals because of the differences in skull acoustic properties. To better understand the fundamental mechanisms underlying the variation in imaging performance, the effect of the structure of the porous trabecular bone on transcranial imaging performance (i.e., target localization errors and resolution) was investigated for the first time through the use of elastic wave simulations and experiments. Simulation studies using high-resolution computed tomography data from ex vivo skull samples revealed that imaging at large incidence angles reduced the target localization error for skulls having low porosity; however, as skull porosity increased, large angles of incidence resulted in degradation of resolution and increased target localization errors. Experimental results indicate that imaging at normal incidence introduced a localization error of 1.85 ± 0.10 mm, while imaging at a large incidence angle (40°) resulted in an increased localization error of 6.54 ± 1.33 mm and caused a single point target to no longer appear as a single, coherent target in the resulting image, which is consistent with simulation results. This first investigation of the effects of skull microstructure on transcranial ultrasound imaging indicates that imaging performance is highly dependent on the porosity of the skull, particularly at non-normal angles of incidence.

This study aims to investigate the feasibility of quantitative ultrasonic backscatter in evaluating human cortical and trabecular bone densities in vivo based on a head-down-tilt bed rest study, with 36 participants tested through 90 d of bed rest and 180 d of recovery. Backscatter measurements were performed using an ultrasonic backscatter bone diagnostic instrument. Backscatter parameters were calculated with a dynamic signal-of-interest method, which was proposed to ensure the same ultrasonic interrogated volume in cortical and trabecular bones. The backscatter parameters exhibited significant correlations with site-matched bone densities provided by high-resolution peripheral quantitative computed tomography (0.33|R|0.72, p0.05). Some bone densities and backscatter parameters exhibited significant changes after the 90-d bed rest. The proposed method can be used to characterize bone densities, and the portable ultrasonic backscatter bone diagnostic device might be used to non-invasively reveal mean bone loss (across a group of people) after long-term bed rest and microgravity conditions of spaceflight missions.

Objective The aim of this study was to compare the fractal dimensions (FDs) of peri-implant trabecular bone around 2-implant–supported overdentures with the FDs around 4-implant–supported overdentures at the time of implant placement (T0) and 1 year after placement (T1). Study Design Standardized regions of interest were chosen at sites mesial and distal to 60 mandibular implants: 20 in 2-implant–supported prostheses (group 1) and 40 in 4-implant–supported prostheses (group 2), for a total of 120 measurements. FD values were calculated by using ImageJ software with the box-counting method. Results The mean FD values of peri-implant bone were significantly lower at T1 than at T0 in both groups (P ≤ .001). Differences between the groups in the decrease in FD between T0 and T1 were mostly insignificant. Conclusions Within the limitations of this study, 2-implant and 4-implant–supported overdentures exhibited the same degree of reduction in peri-implant FD over time, suggesting similar risk of failure because FD is related to implant stability. Depending on the patient's residual ridge status and other factors, the 2-implant–supported overdenture may be preferred because it requires less surgery and is less costly.

Background Regenerex® is a porous titanium construct with a 3D interconnecting pore structure and biomechanical characteristics close to that of normal trabecular bone. This study aimed to compare the Regenerex (VR) to the non-interconnecting pore structure Porous Plasma Spray (VP) on tibial implants for total knee arthroplasty (TKA) at 5 years. Methods We enrolled and randomized 61 patients (mean age = 63(49–71) years, Female/Male = 35/26) who were planned for an uncemented Vanguard TKA (Biomet, Warsaw, Indiana, USA) to receive either a VR or a VP coated tibial component (31/29). We performed radiostereometric analysis (RSA) and Dual Energy X-ray Absorptiometry (DEXA) postoperatively, and at three, six, 12, 24 and 60 months with measurements of migration. In total 55 patients attended the 5-year follow-up. Results One patient died and four were reoperated during the 60-months period; none due to aseptic loosening. All reoperations were in the VR-group. The mean (range) 60-months MTPM was 1.4 mm (0.5–3.7) for the VP-group and 1.8 mm (0.4–4.9) for the VR-group (p = 0.8). The 24 to 60-months mean (range) MTPM was −0.3 mm (−5 to 1.24) in the VP-group and 0.2 mm (−0.4 to 3.5) in the VR-group (p = 0.8). Conclusion We did not find any statistically significant differences between the VP- and VR-group and both groups show recognizable migration. We will continue to follow the groups for years to come.

This study was performed to evaluate the effect of isotretinoin on tooth displacement and tissues related to induced tooth movement (ITM) in rats.Wistar rats were randomly divided into 4 groups: vegetable oil (O; n = 40), 7.5 mg/kg isotretinoin (I; n = 40), vegetable oil + ITM (OM; n = 44), and 7.5 mg/kg isotretinoin and ITM (IM; n = 39). After the daily application of the solutions for 30 days, an orthodontic appliance was installed to mesially displace the maxillary first right molar (30 cN) of rats in the OM and IM groups. The animals were killed 2, 7, 14, or 21 days after placement of the devices. The animals in the O and I groups did not undergo ITM but were killed simultaneously. The animals were examined for tooth displacement, the neoformation of mature collagen, bone and root resorption, the presence of hyalinized areas, and trabecular bone modeling by microcomputed tomography.There was no difference in tooth displacement, the number of osteoclasts, the presence of hyalinized areas, or trabecular bone among the O, I, OM, and IM groups across the periods tested (P 0.05). A lower percentage of mature collagen was found in the IM group than in the OM group on day 7 (P 0.05). A lower frequency of root resorption was found in the IM group than in the OM group on days 2 and 21 (P 0.05).Isotretinoin at 7.5 mg/kg decreased root resorption in rats subjected to ITM.

Artificial bone modelling has been done in recent times in order to replicate the mechanical properties and microstructure of the human cancellous and cortical bone. The applications of artificial bone models include bone grafting and testing of orthopaedic instruments. The recent developments in this field make the use of natural polymers and bio-compatible metals to manufacture porous structures replicating bone properties. The aim of this review is to consolidate the research efforts done in the field of making artificial bone models of the human trabecular bone by studying the material and manufacturing aspects of the process. The article reviews the bone models under the categories of polymers and composites and metal scaffolds. A combination of natural polymers along with a bio-compatible synthetic polymer and bio-ceramic reinforcement has proven to be a suitable candidate in replicating the mechanical properties of the bone while ensuring bio-compatibility. Three manufacturing techniques were reviewed with respect to the ability to replicate the bone microstructure. SLM is a potential candidate in terms of design flexibility and manufacturing accuracy. A direction to future research in extending the application of artificial bone models to the testing of dental implants has also been provided.

In recent years, machine-learning-based approaches have become of considerable interest to the efficient processing of short or limited data samples. Its so-called small data approach. This is due to the significant growth of new intellectual analysis tasks in various industries, which are characterized by limited historical data. These include Materials Science, Economics, Medicine, and so on. An effective processing of short datasets is especially acute in medicine. Insufficient number of vectors, significant gaps in the data collected during the supervision of patient’s treatment or rehabilitation, reduces the effectiveness or prevents effective intellectual analysis based on them. This paper presents a new approach to processing short medical data samples. The basis of the developed method is SVR with RBF kernel. The algorithmic implementation of the method in both operation modes is described. Experimental modeling on a real short data set (Trabecular bone data) is conducted. It contained only 35 observations. A comparison of the method with a number of existing machine learning methods is conducted. It is experimental established the highest accuracy of the method among those considered. The developed method has potential opportunities for wide application in various fields of medicine.

Dual-energy computed tomography (DECT) combines the advantages of conventional CT with the ability to detect bone marrow oedema (BMO), which was previously limited to magnetic resonance imaging (MRI). By analysing DECT virtual non-calcium (VNCa) maps, radiologists can improve the detection of subtle and occult fractures and approximate the acuity/healing of fractures of indeterminate age. This review highlights the role of DECT in the assessment of musculoskeletal trauma, particularly among elderly, post-menopausal women and those at risk for osteoporosis. DECT is especially useful in investigating trabecular bone predominant regions (e.g., vertebral bodies, pelvis, hip, and long bone metaphyses) for stress (i.e., fatigue or insufficiency) and fragility fractures. CT is often performed first due to its increased availability, especially in the emergency setting, shorter imaging duration, and possible patient contraindications to magnetic resonance imaging (MRI). By enabling BMO detection, DECT may have a role in triaging patients for definitive MRI assessment. Understanding the role of anatomical, pathological, and patient factors in image interpretation can improve radiologist adoption of DECT, increase diagnostic confidence, and improve patient management.

This study describes the mechanical properties of pure hydroxyapatite (HAp) and kaolin reinforced hydroxyapatite (K-HAp) produced from non-separated animal bones using compression pressure under different sintering regimes. The HAp microparticles were synthesized separately using a facile heat treatment method and reinforced with 15 wt% of beneficiated kaolin (HAp/15 wt% BK) using the sol–gel method. The HAp and K-HAp derived scaffolds were fabricated by cold pressing with a compaction pressure of 500 Pa. Next, the scaffolds were sintered at 900 °C, 1000 °C and 1100 °C with a 2 h dwell time in air atmosphere. Subsequently, the mechanical properties of the scaffolds were examined. The effect of sintering temperature and compaction pressure on the hardness and the compressive strength of the pure and reinforced HAp showed that at all points of measurement (with and without compaction pressure), the mechanical properties increased with an increase in sintering temperature, and the most significant mechanical properties were obtained at 1100 °C. The values of hardness at the maximum sintering temperature (1100 °C) are 0.93 and 1.09 GPa with and without the application of compaction pressure, respectively, for pure HAp-derived scaffolds and 0.74 and 0.78 GPa with and without the application of compaction pressure, respectively, for K-HAp-derived scaffolds. The compressive strength for K-HAp had the value of 7.84 MPa as compared with 0.69 MPa for the non-reinforced HAp matrix with the application of compaction pressure (500 Pa). The findings show that the mechanical properties of the synthesized kaolin reinforced HAp in relation to the scaffolds produced with the low compaction pressure of 500 Pa is suitable for human trabecular bone.

Calcium phosphate cements (CPCs) have been used to treat bone defects and support bone regeneration because of their good biocompatibility and osteointegrative behavior. Since their introduction in the 1980s, remarkable clinical success has been achieved with these biomaterials, because they offer the unique feature of being moldable and even injectable into implant sites, where they harden through a low-temperature setting reaction. However, despite decades of research efforts, two major limitations concerning their biological and mechanical performance hamper a broader clinical use. Firstly, achieving a degradation rate that is well adjusted to the dynamics of bone formation remains a challenging issue. While apatite-forming CPCs frequently remain for years at the implant site without major signs of degradation, brushite-forming CPCs are considered to degrade to a greater extent. However, the latter tend to convert into lower soluble phases under physiological conditions, which makes their degradation behavior rather unpredictable. Secondly, CPCs exhibit insufficient mechanical properties for load bearing applications because of their inherent brittleness. This review places an emphasis on these limitations and provides an overview of studies that have investigated the biological and biomechanical performance as well as the degradation characteristics of different CPCs after implantation into trabecular bone. We reviewed studies performed in large animals, because they mimic human bone physiology more closely in terms of bone metabolism and mechanical loading conditions compared with small laboratory animals. We compared the results of these studies with clinical trials that have dealt with the degradation behavior of CPCs after vertebroplasty and kyphoplasty.

International audience; Complications with bilateral sagittal split osteotomy (BSSO) can sometimes result from surgical inexperience. Our aim was to present a 3-dimensional printed mandibular model for BSSO training in a maxillofacial surgical education programme. A polymethacrylate mandibular model obtained from mandibular cone-beam computed tomographic (CT) images was designed and printed for use in training. Twenty-four residents were each asked to do a BSSO according to the Epker/Dal-Pont technique. The session was conducted as a simulation course with a final debriefing. A questionnaire before and after the test was filled in using a 10-point Likert scale to assess the participants' knowledge. The mandibular model provided a realistic way of handling the trabecular bone after cortical osteotomy, as well as in the splitting phase. Significant increases in knowledge and surgical skills were noted for all steps of the BSSO, particularly regarding the use of the piezoelectric device for osteotomy, and for management of wisdom teeth in the splitting zone (3.00 ±2.16 to 6.95 ±2.06 and 2.73 ±1.91 to 5.75 ±2.63, respectively; p1=0.0002 and p2=0.0003). We think that this is a valuable printed mandibular model for the development of surgical skills for BSSO in maxillofacial surgical residents.

Summary Background/Objective The microstructure of the subchondral trabecular bone, including the composition and distribution of plates and rods, has an important influence on the disease progression and mechanical properties of osteoarthritis (OA) and osteoporosis (OP). We aimed to determine whether differences in plates and rods influence the variations in the quantities and qualities of the subchondral trabecular bone between OA and OP. Materials and methods Thirty-eight femoral head samples [OA, n = 13; OP, n = 17; normal control (NC), n = 8] were collected from male patients undergoing total hip arthroplasty. They were scanned using microcomputed tomography, and subchondral trabecular structures were analysed using individual trabecular segmentation. Micro-finite element analysis (μFEA) was applied to assess the mechanical property of the trabecular bone. Cartilage changes were evaluated by using histological assessment. Analysis of variance was used to compare intergroup differences in structural and mechanical properties and cartilage degradation. Pearson analysis was used to evaluate the relationship between the trabecula microstructure and biomechanical properties. Results Compared with the OP and NC group, there was serious cartilage damage in the OA group. With respect to the microstructure results, the OA group had the highest plate and rod trabecular microstructures including number and junction density among the three groups. For the mechanical properties detected via μFEA, the OA group had higher stiffness and failure load than did the OP group. Pearson analysis revealed that compared with OP, OA had a higher number of microstructure parameters (e.g., rod bone volume fraction and rod trabecular number) that were positively correlated with its mechanical property. Conclusions Compared with OP, the OA subchondral bone has both increased plate and rod microarchitecture and has more microstructures positively related with its mechanical property. These differences may help explain the variation in mechanical properties between these bone diseases. The translational potential of this article Our findings suggested that changes in the plates and rods of the subchondral trabecular bone play a critical role in OA and OP progression and that the improvement of the subchondral trabecular bone may be a promising treatment approach.

Objectives Bone mineral density (BMD), as a gold standard determinant of osteoporosis, assesses only one of many characteristics contributing to the bone. Trabecular bone score (TBS) is applied to evaluate the microarchitecture of trabecular bone. A high body mass index (BMI) has been reported to have a positive correlation with BMD. However, the relation between BMI and TBS has remained unclear. Therefore, the aim of this study is to shed light on the associations between BMI, T-score, and TBS in postmenopausal women without a diagnosed underlying disease. Methods In this cross-sectional study, 1054 postmenopausal women were randomly recruited from the Department of Radiology, Isfahan University of Medical Sciences. Demographic characteristics and medical history of all subjects were collected from documents. TBS measurements for L1-L4 vertebrae were retrospectively performed by the TBS iNsight software using the dual X-ray absorptiometry (DXA) from the same region of spine of the subjects. The analysis was done to detect the correlation between TBS and BMI. Results A statistically significant negative correlation was found between TBS and BMI in patients with osteoporosis and low bone mass. In patients with normal T-scores, BMI was not significantly correlated to TBS (P > 0.05). Furthermore, there was a significant positive association between T-score and BMI. Conclusions Although a higher BMI had a protective effect against osteoporosis, higher BMI was associated with a lower TBS in patients with an abnormal T-score. However, BMI did not have a significant effect on TBS in patients with normal T-scores.

Background Although previous studies have measured general proximal forearm bone mineral density (BMD), no study has systematically mapped the 3-dimensional trabecular BMD of the proximal ulna. The aim of this study was to describe the 3-dimensional distribution of the trabecular bone density of the proximal ulna. We hypothesize a variable distribution of proximal ulna trabecular BMD depending on the region of interest (ROI). Methods Computed tomographic (CT) scans of 9 fresh-frozen cadaveric proximal ulna specimens with a mean age of 59.3 ± 8.1 years were studied. Each CT file was converted from DICOM to a QCT file that could be analyzed using QCT software (QCT Pro Version 6.1, Model 4 CT Calibration Phantom; MindWays Software Inc, Austin, TX, USA). The ROIs were defined as spheres of trabecular bone 3 mm in diameter located throughout the proximal ulna. Results ROIs proximal to the trochlear notch demonstrated higher BMD than ROIs distal to the trochlear notch. Furthermore, volar ROIs adjacent to the ulnohumeral joint tended to have higher BMD than dorsal ROIs. The highest BMD was found in the tip of the olecranon. Conclusion Hardware in fixation constructs for proximal ulnar fractures should be directed toward ROIs with the highest BMD to maximize purchase. Hardware should approach the ulnohumeral joint without penetrating the joint to capture trabecular bone with the highest BMD. The most important fixation in such a construct will be that which captures trabecular bone with maximum BMD proximal to the trochlear notch (eg, the tip of the olecranon).

Okara, despite being a soybean processing by-product, still holds many nutrients. Thus, considerable attention has been recently paid to its reuse. In this study, solid-state fermentation was performed using Ganoderma lucidum and Lentinus edodes. Antioxidant activity and bioactive compound levels in G. lucidum-fermented okara (GLFO) and L. edodes-fermented okara (LEFO) were assayed. Antiosteoporosis bioactivity was evaluated using an animal model. The results demonstrated that solid-state fermentation significantly improved the antioxidant activity and bioactive compound levels. Furthermore, GLFO and LEFO increased trabecular bone volume, although only the GLFO-treated group exhibited significantly improved trabecular separation compared with the bilateral ovariectomy-treated control group. GLFO-related outcomes were superior to those of LEFO. The results demonstrate that okara products are effective for treating postmenopausal osteoporosis in humans.

Introduction: In 2010, experts in osteoporosis and bone densitometry were convened by the Space Life Sciences Directorate at NASA Johnson Space Center to identify a skeletal outcome in astronauts after spaceflight that would require a clinical response to address fracture risk. After reviewing astronaut data, experts expressed concern over discordant patterns in loss and recovery of bone mineral density (BMD) after spaceflight as monitored by dual-energy X-ray absorptiometry (DXA) and quantitative computed tomography (QCT). The pilot study described herein demonstrates the use of QCT to evaluate absence of recovery in hip trabecular BMD by QCT as an indicator of a clinically actionable response. Methodology: QCT and DXA scans of both hips were performed on 10 astronauts: once preflight and twice postflight about 1 wk and 1 yr after return. If trabecular BMD had not returned to baseline (i.e., within QCT measurement error) in 1 or both hips 1 yr after flight, then another QCT hip scan was obtained at 2 yr after flight. Results: Areal BMD by DXA recovered in 9 of 10 astronauts at 1 yr postflight while incomplete recovery of trabecular BMD by QCT was evident in 5 of 10 astronauts and persisted in 4 of the 5 astronauts 2 yr postflight. Conclusion: As an adjunct to DXA, QCT is needed to detect changes to hip trabecular BMD after spaceflight and to confirm complete recovery. Incomplete recovery at 2 yr should trigger the need for further evaluation and possible intervention to mitigate premature fragility and fractures in astronauts following long-duration spaceflight.

Background: Baseball pitchers’ elbows are exposed to repeated overloading during the throwing motion, which causes bone structural changes such as bone sclerosis and osteophyte formation. They have been observed by clinical CT and MRI, while the bone microstructural change has not yet been studied in vivo. The aims of this study were to establish a method of imaging the elbow joint using second-generation high-resolution peripheral quantitative CT and to investigate the bone microstructural change in baseball pitchers’ dominant elbows. Methods: The subjects were 17 baseball pitchers. The elbow was fixed using a custom-made cast and scanned by second-generation high-resolution peripheral quantitative CT. The scan conditions were as follows: voxel size 60.7 μm, integration time 43 ms, scan length 30.6 mm, and total scan time 8 min. Volumetric bone mineral density (vBMD) and trabecular bone microstructure were analyzed in the 6.5-mm3 cubic regions set in the capitellum and trochlea, and the dominant and nondominant elbows were compared. Results: vBMD, bone volume fraction (BV/TV), and trabecular thickness (Tb.Th) at the capitellum were significantly higher in the dominant elbow than in the nondominant elbow. On the other hand, no parameters at the trochlea were significantly different. Conclusions: Higher vBMD accompanied by thicker trabecular bone was observed at the capitellum. These bone microstructural changes would reflect the valgus stress generated by the pitching motion in the elbow joint.

An expandable rigid PU foam can turns into complex shapes, with a shell like structure on the outside and honeycomb structure on the inside, which can be easily shaped to a vertebra form. The present study aims to determine whether expandable rigid polyurethane foam was an appropriate substitute for rigid block polyurethane foam to model the trabecular bone. Static compression tests were performed to determine compressive moduli and yield stresses on three polyurethane foam densities namely 0.16 g/cm3, 0.24 g/cm3 and 0.42 g/cm3. Morphology of the PU foams for all densities was also observed. The compressive modulus for 0.16 g/cm3 and 0.24 g/cm3 were found varied from 40 to 43 MPa and 83 to 92 MPa while yield stress ranged from 2.1 to 2.3 MPa and 3.4 to 4.8 MPa respectively. As for 0.42 g/cm3, the compressive modulus and yield stress varied from 240 to 256 MPa and 38 to 40 MPa. Based on these results, the compressive modulus and yield stress of 0.24 g/cm3 compared favourably with rigid block PU foam and human cadavers presented in the literatures. Hence, the findings of this study could potentially be used in developing a synthetic vertebral trabecular bone of paediatric spine for biomechanical testing. Keywords: Polyurethane foam, Synthetic spine, Trabecular bone, Compressive properties

Objective To better understand the pathogenesis of DISH, identifying early or pre-DISH lesions in the spine and investigating the relationship between spinal and extra-spinal manifestations of DISH. Material 44 skeletonized individuals with DISH from the WM Bass Donated Skeletal Collection. Methods For each vertebra, location, extension, point of origin and appearance of vertebral outgrowths were recorded. The size of the enthesophytes at the olecranon process, patella and calcaneal tuberosity was measured with digital callipers. Results At either end of the DISH-ankylosed segment, isolated vertical outgrowths arising from the central third of the anterior aspect of the vertebral body can usually be observed. These bone outgrowths show a well-organized external cortical layer, an internal structure of trabecular bone and usually are unaccompanied by or show minimal associated endplate degeneration. Analysis of the relationship between spinal and extra-spinal manifestations (ESM) suggests great inter-individual variability. No correlation between any ESM and the stage of spinal DISH was found. Conclusions Small isolated outgrowths represent the earliest stages of the spinal manifestations of DISH. The use of ESM as an indicator of DISH should be undertaken with great caution until the relationship between these two features is understood. Significance Improved accuracy of paleopathological diagnostic criteria of DISH. Limitations Small sample comprised of only individuals with DISH. Future research micro-CT analysis to investigate the internal structure of the spinal lesions. Analysis of extra-spinal enthesophytes in individuals with and without DISH to understand their pathogenesis and association with the spinal lesions in individuals with DISH.

Bone remodeling process has been widely investigated in the literature experimentally and theoretically, its biological process allows the microstructure continuous renewal over time and repairing damaged bones. In this work, a study of the biological function’s (fbio) effect on the bone remodeling process is made through the bone density evolution since it is one of the important parameters to control bone volume variation. The theoretical issue was discussed and simulated to show the bone volume fraction growth and the porosity evolution, comparing, and adjusting the results to behavior of experimental data. The biological bone remodeling process is modeled in terms of equations describing the activity of the Basic Multi-cellular Units (BMU). We use a model basing on Garcia Aznar’s model which can simulate damage repair. Simulation result concurs with experimental and clinical data: bone porosity decreases during time and keep decreasing as the biological factors increase. In addition, the apparent density (ρa) decreases as bone volume fraction increases. Indeed, we predict an intermediate zone, between cortical and trabecular bone, settled on rate of bone volume fraction. The governance of the bone density evolution will take into consideration the bone volume evolution during the youthful and the maturation phase with their saturation zone for adult in terms of growth.

Finite-element models are used to estimate numerically the distribution of bone mineral density (BMD) as a result of bone remodelling process from the loads applied. However, the effect of initial BMD distribution on trabecular-bone remodelling is still unknown. In this paper, the effect of initial density distributions as an input in the finite-element model on a structural-functional relationship of trabecular bone was investigated. A multi-material model representing a realistic density distribution was used based on the grey-scale value (GV) distribution and compared with a traditional single-material model. Different trabecular morphologies with density distributions were observed for these two material models. Similar character of the occurrence of density (in terms of element and volume fraction) of trabecular bone from a femur head were found, with the same highest number of elements in the density range from 1.25 to 1.35 g/cm3. These results indicate that previous simplified models using single-material properties for trabecular bone may not lead to considerable errors.

Background/purpose: Mini-implant screws are now routinely used as anchorage devices in orthodontic treatments. This study used synthetic bone models to investigate how the primary stability of an orthodontic mini-implant (OMI) as measured by resonance frequency (RF) is affected by varying cortical bone thickness and trabecular bone density. Materials and methods: Three synthetic cortical shells (thicknesses of 1, 2, and 3 mm) and three polyurethane foam blocks (densities of 40, 20, and 10 pound/cubic foot) were used to represent jawbones of varying cortical bone thicknesses and varying trabecular bone densities. Twenty-five stainless steel OMIs (2 × 10 mm) were sequentially inserted into artificial bone blocks to depths of 2, 4, and 6 mm. Five experimental groups of bone blocks with OMIs were examined by Implomates® RF analyzer. Statistical and correlation analyses were performed by Kruskal-Wallis test, Wilcoxon rank-sum test, and simple linear regression. Results: As trabecular bone density decreased, RF decreased; as cortical bone thickness decreased, RF also decreased. Simple linear regression analysis showed highly linear correlations between trabecular bone density and RF (R2 > 0.99; P 0.98; P

Roux's principle of bone functional adaptation postulates that bone tissue, and particularly trabecular bone tissue, responds to mechanical stimuli by adjusting (modeling) its architecture accordingly. Hence, it predicts that the new modeled trabecular structure is mechanically improved (stiffer and stronger) in line with the habitual in vivo loading direction. While previous studies found indirect evidence to support this theory, direct support was so far unattainable. This is attributed to the fact that each trabecular bone is unique, and that trabecular bone tissue tends to be damaged during mechanical testing. Consequently, a unique modeled trabecular structure can be mechanically tested only along one direction and a comparison to other directions for that specific structure is impossible. To address this issue, we have 3D printed 10 replicas of a trabecular structure from a sheep talus cropped along the 3 principal axes of the bone and in line with the principal direction of loading (denoted on-axis model). Next, we have rotated the same cropped trabecular structure in increments of 10° up to 90° to the bone principal direction of loading (denoted off-axis models) and printed 10 replicas of each off-axis model. Finally, all on-axis and off-axis 3D printed replicas were loaded in compression until failure and trabecular structure stiffness and strength were calculated. Contrary to our prediction, and conflicting with Roux's principle of bone functional adaptation, we found that a trabecular structure loaded off-axis tended to have higher stiffness and strength values when compared to the same trabecular structure loaded on-axis. These unexpected results may not disprove Roux's principle of bone functional adaptation, but they do imply that trabecular bone adaptation may serve additional purposes than simply optimizing bone structure to one principal loading scenario and this suggests that we still don't fully understand bone modeling in its entirety.

Background Healthy African-Americans are known to have greater bone mineral density and decreased risk of fracture when compared to Caucasians. In fact, comparisons of bone histomorphometry in healthy South African children and adults reveal greater cortical thickness in Black subjects as compared to White. How these differences are reflected in the bone of American children and young adults on dialysis is unknown. Methods Using tetracycline-labeled, iliac crest bone biopsies obtained in prior research protocols in pediatric and young adult dialysis patients, we compared trabecular and cortical parameters between non-Hispanic African-American subjects and non-Hispanic Caucasian subjects matched by age and gender. A linear regression model controlled for trabecular turnover and mineralization was used to further investigate the association of race with cortical thickness. Results The matched cohort consisted of 52 subjects-26 African-American and 26 Caucasian. Turnover, mineralization and volume parameters in trabecular bone did not show significant differences between racial groups. Characterizing subjects by renal osteodystrophy type did not show a statistically significant difference although Caucasian patients had double the prevalence of mineralization defects. Consistent with this was a trend toward better mineralization parameters in African-Americans including shorter osteoid maturation time and lower osteoid volume. A sub-cohort of patients with cortical measures demonstrated greater median (IQR) cortical thickness in African-Americans (541 μm [354, 694]) than in Caucasians (371 μm [336, 446], p = 0.08). In a linear regression model controlling for trabecular turnover and mineralization, African-American subjects had 36.2% (95% CI 0.28 to 85.1%, p = 0.048) greater cortical thickness as compared to White subjects. There was no significant difference in cortical porosity. Conclusions Although likely limited by sample size, our findings suggest that, similar to findings in populations of normal children, African-American race in pediatric and young adults on dialysis is associated with greater cortical thickness. Additionally, there was a trend toward greater mineralization defects in Caucasian children. Both findings require further exploration with larger patient samples in order to thoroughly explore these racial differences and the implications on CKD-MBD treatment.

The microarchitecture of bone tissue presents many features that could act as stress concentrators for the initiation of bone microdamage. This was first identified by John Currey in a seminal paper in 1962 in which he presented the mechanical and biological evidence for stress concentrations at the bone surface, within the bone through the action of stiffness differentials between architectural features including between lamellae, and at the level of the lacunar and canalicular walls. Those early observations set the stage to consider how microscopic damage to bone tissue might affect the properties of bone at a time when most in the scientific community dismissed microcracks in bone as artifact. Evidence collected in the nearly 60 years since those important initial observations suggest that some of these architectural features in bone tissue are more effective as crack arrestors than as crack initiators. Sites of higher mineralization in the bone matrix, particularly interstitial sites in both cortical and trabecular bone, may serve preferentially as locations for crack initiation, whereas those boundaries identified by Currey as both stress concentrators and stress arrestors are more effective at stopping cracks than at initiating them.

Summary Objective To determine the dual-energy computed tomography (DECT) attenuation properties of meniscal calcifications in calcium pyrophosphate deposition (CPPD) in vivo, and assess whether DECT was able to discriminate meniscal CPP deposits from calcium hydroxyapatite (HA) in subchondral and trabecular bone. Method Patients with clinical suspicion of crystal-related arthropathy (gout and/or CPPD) and knee DECT scans were retrospectively assigned to CPPD (n = 19) or control (n = 21) groups depending on the presence/absence of chondrocalcinosis on DECT. Two observers drew standardized regions of interest (ROI) in meniscal calcifications, non-calcified menisci, as well as subchondral and trabecular bone. Five DECT parameters were obtained: CT numbers (HU) at 80 and 140 kV, dual-energy index (DEI), electron density (ρe), and effective atomic number (Zeff). The four different knee structures were compared within/between patients and controls using linear mixed models, adjusting for confounders. Results Meniscal calcifications (n = 89) in CPPD patients had mean ± SD CT numbers at 80 and 140 kV of 257 ± 64 and 201 ± 48 HU, respectively; with a DEI of 0.023 ± 0.007, and ρe and Zeff of 140 ± 35 and 8.8 ± 0.3, respectively. Meniscal CPP deposits were readily distinguished from calcium HA in subchondral and trabecular bone (p ≤ 0.001), except at 80 kV separately (p = 0.74). Zeff and ρe both significantly differed between CPP deposits and calcium HA in subchondral and trabecular bone (p Conclusion This proof-of-concept study shows that DECT has the potential to discriminate meniscal CPP deposits from calcium HA in subchondral and trabecular bone in vivo, paving the way for the non-invasive biochemical signature assessment of intra- and juxta-articular calcium crystal deposits.

Due to difficulty assessing healing of distal radius fractures using conventional radiography, there is interest in using high resolution peripheral quantitative computed tomography (HR-pQCT) to track healing at the microarchitectural level. Unfortunately, the plaster-of-Paris and fiberglass casts used to immobilize fractures affect HR-pQCT measurements due to beam hardening, and increased noise. The challenge is compounded because casts have variable thickness, and an individual patient will often have their cast changed 2-3 times during the course of treatment. This study quantifies the effect of casts within a clinically relevant range of thicknesses on measured bone parameters at the distal radius, and establishes conversion equations to correct for systematic error in due to cast presence. Eighteen nonfractured participants were scanned by HR-pQCT in three conditions: no cast, plaster-of-Paris cast, and fiberglass cast. Measured parameters were compared between the baseline scan (no cast) and each cast scan to evaluate if systematic error exists due to cast presence. A linear regression model was used to determine an appropriate conversion for parameters that were found to have systematic error. Plaster-of-Paris casts had a greater range of thicknesses (3.2-9.5 mm) than the fiberglass casts (3.0-5.4 mm), and induced a greater magnitude of systematic error overall. Key parameters of interest were bone mineral density (total, cortical, and trabecular) and trabecular bone volume fraction, all of which were found to have systematic error due to presence of either cast type. Linear correlations between baseline and cast scans for these parameters were excellent (R2 > 0.98), and appropriate conversions could be determined within a margin of error less than a ±6% for the plaster-of-Paris cast, and ±4% for the fiberglass cast. We have demonstrated the effects of cast presence on bone microarchitecture measurements, and presented a method to correct for systematic error, in support of future use of HR-pQCT to study fracture healing.

Titanium implant failures are mainly related to stress shielding phenomenon and the poor cell interaction with host bone tissue. The development of bioactive and biomimetic Ti scaffolds for bone regeneration remains a challenge which needs the design of Ti implants with enhanced osseointegration. In this context, 4 types of titanium samples were fabricated using conventional powder metallurgy, fully dense, dense etched, porous Ti, and porous etched Ti. Porous samples were manufactured by space holder technique, using ammonium bicarbonate particles as spacer in three different ranges of particle size (100–200 μm, 250–355 μm and 355–500 μm). Substrates were chemically etched by immersion in fluorhydric acid at different times (125 and 625 s) and subsequently, were characterized from a micro-structural, topographical and mechanical point of view. Etched surfaces showed an additional roughness preferentially located inside pores. In vitro tests showed that all substrates were biocompatible (80% of cell viability), confirming cell adhesion of premioblastic cells. Similarly, osteoblast showed similar cell proliferation rates at 4 days, however, higher cell metabolic activity was observed in fully dense and dense etched surfaces at 7 days. In contrast, a significant increase of alkaline phosphatase enzyme expression was observed in porous and porous etched samples compared to control surfaces (dense and dense etched), noticing the suitable surface modification parameters (porosity and roughness) to improve cell differentiation. Furthermore, the presence of pores and rough surfaces of porous Ti substrates remarkably decreased macrophage activation reducing the M1 phenotype polarization as well M1 cell marker expression. Thus, a successful surface modification of porous Ti scaffolds has been performed towards a reduction on stress shielding phenomenon and enhancement of bone osseointegration, achieving a biomechanical and biofunctional equilibrium., This article is also dedicated to our dear friend and colleague Prof. Juan Jose Pavón, who prematurely passed away early in 2017, his dedication to his work, his students, his friends and family, will always be remembered. This work was supported by the Ministry of Economy and Competitiveness of Spain under the grant MAT2015-71284-P and of the Junta de Andalucía – FEDER (Spain) through the Project Ref. P12-TEP-1401. The authors would like to thank technician J. Pinto for assistance in micro-mechanical testing

The aim of this work was to determine how far the effects of micro-osteoperforations (MOPs) extend within bone by quantifying the damage caused and the short-term bony adaptations that occur in and around the injury site.With the use of a split-mouth design, 34 MOPs (Propel) were randomly placed in the mandibular furcal bone of 13 beagle dogs either 2 or 4 weeks before killing them. The control side received no treatment. Vickers hardness microindentation, microscopic computed tomography, and histologic analyses were performed to evaluate the bone surrounding the MOPs.Microfractures produced during insertion extended ∼0.6 mm from the MOP sites. Cortical and trabecular bone were significantly less dense on the experimental than on the control side up to 4.2 mm from the edge of the MOP, but side differences were small (5%) beyond 1.5 mm from the MOP. Experimental cortical bone was significantly softer than the control bone up to 0.8 mm from the MOP after 2 weeks of healing, and up to 0.5 mm from the MOP after 4 weeks of healing. Hematoxylin and eosin stained sections of cortical and trabecular bone showed small areas of woven bone within the MOP sites after 2 weeks, and acellular areas of bone extending ∼0.5 mm from the MOP. After 4 weeks of healing, there were greater amounts of woven bone, as well as early signs of lamellar bone, in and around the MOP sites. Markedly increased TRAP activity extending up to 2.5 mm from the MOP was evident after 2 weeks, but not after 4 weeks. Vital fluorescence staining showed diffuse bone deposition on the experimental side up to 1.5 mm from the MOP margin.When MOPs are performed in beagle dogs, demineralization is transient and healing of the injured area, as well as remineralization of bone affected by MOP placement, begins during the first 2 weeks. Although the transient effects extend farther, the principal effects extend only ∼1.5 mm from the MOP site.

Background and objective: There is a lack of quantitative measures of the quality of alveolar trabecular bone, an important factor in implantology. This study aimed to develop a method of objectively assessing the quality of trabecular bone by means of image processing and structural analysis of multidetector computed tomography images and to establish differences between tooth types and tooth presence/absence. Materials and methods: We analyzed 20 patients who underwent multidetector computed tomography to evaluate mandibular bone and tooth positioning. Image analysis included automatic segmentation of the mandible, obtainment of sections perpendicular to the dental arch, and structural analysis of the trabecular bone in each section. We calculated the ratio between the volume of bone and the total volume of the section, the thickness, the trabecular number, and the mean attenuation in Hounsfield units. We analyzed the differences among different tooth types (incisors, canines, premolars, and molars) and between present and absent teeth. Results: We found statistically significant differences between different tooth types and between sections in which teeth were present or absent. Incisors had a greater ratio of trabecular bone; the ratio of trabecular bone progressively decreased from the incisors to the canines, premolars, and molars. The ratio of trabecular bone was greater in sections in which teeth were absent than in those in which teeth were present. Conclusions: The method allows to quantify the structural properties of alveolar bone from multidetector computed tomography images. Our results provide an objective picture of the bone substrate that can be useful for planning and following up dental implant procedures. (C) 2019 SERAM. Published by Elsevier Espana, S.L.U. All rights reserved.

Background Bone lead measured via x-ray fluorescence (XRF) has been used for decades in health studies. A portable XRF device for bone lead measurement is gaining in popularity for its ease of use and shorter measurement times. Previous XRF devices have measured different bone types in order to sample both cortical and trabecular bone, in which lead has different half residence times. Objective The portable XRF uses lower energy to measure bone lead than previous devices, and, thus, only measures the surface of the bone. Because all bones have a cortical shell, we hypothesized that portable XRF bone lead measurements would be similar regardless of the bone measured. Methods This study tested differences in portable XRF bone lead measurements across different cortical and trabecular bones in measurements made on 31 cadavers. We also compared tissue thicknesses overlying different bones, which can impact portable XRF measurements. Results The correlation coefficients found between bones were higher (rho ~0.4) than previous K-shell XRF bone measurements in cortical and trabecular over the same range of values (rho~0.2). The concentrations were shown to vary non-significantly across different bones within individuals.

Osteogenesis imperfecta is a hereditary connective tissue disorder, resulting in low bone mass and high bone fragility. Dual-energy X-ray absorptiometry (DXA) and in adulthood also the trabecular bone score (TBS) are well established to assess bone health and fracture risk. The purpose of this investigation was to assess the usefulness of TBS in respect to different treatment regimes in children with osteogenesis imperfecta. Changes of areal bone mineral density (aBMD) and TBS using DXA scans of children treated with antiresorptive therapies were evaluated.DXA scans (aBMD, TBS) of 8 children with OI were evaluated. The scans were taken during a 1 yr period of treatment with bisphosphonates and during 1 yr pilot trial using denosumab. Changes of aBMD and TBS during both treatment regimens were compared.During bisphosphonate treatment aBMD increased about 6.2%, while TBS increased about 2.1%. The difference between aBMD and TBS before and after bisphosphonate treatment was not significant (p = 0.25). During denosumab treatment aBMD increased around 25.1%, while TBS increased 6.7%. The change of aBMD was significant (p = 0.007), as was the difference between aBMD and TBS (p0.001).Denosumab had a significant effect on both aBMD and TBS but was significantly more pronounced in aBMD. These results suggest a stronger effect of denosumab on cortical bone and the growth plate in comparison to bisphosphonates. Beside the lack of paediatric reference data and the small sample size, the results suggest TBS to be a useful tool for monitoring skeletal changes during development, growth, and antiresorptive therapy in children with OI.

Introduction: Trabecular bone score (TBS) provides indirect indices of trabecular microarchitecture and bone quality. Several studies have evaluated the influence of proton pump inhibitors (PPIs) on bone mass and geometric parameters, but no studies have evaluated the influence of PPIs on TBS. Methods: We reviewed the medical records of 1505 women aged 40–89 yr who had bone mineral density (BMD) examinations as a part of the medical diagnosis and disease prevention program and who did not have osteoporotic fractures or conditions that could affect bone metabolism. Among these, we identified 223 women with exposure to PPIs and selected the same number of age- and body mass index (BMI)-matched control patients. We compared TBS and BMD between the PPI exposure group and the control group and performed multivariate regression analyses to determine whether TBS and BMDs are associated with age, BMI, and PPIs exposure. We also examined whether TBS and BMDs are associated with PPIs exposure timing (current, recent, and past). Results: TBS and BMDs were significantly lower in the PPI exposure group than in the control group. In a multivariable linear regression analysis, TBS was significantly associated with age ( p p = 0.02). In addition, all BMDs were found to be significantly associated with age, BMI, and PPI exposure. Lower TBS was associated with current PPIs use ( p = 0.005), but not with recent or past PPIs usage. However, the influence of PPI exposure timing on the BMDs was not consistent between BMD measurement sites. Conclusions: This study found that TBS is lower in subjects with PPIs exposure than in controls. The association of lower TBS with current PPIs use suggests that trabecular bone quality could be affected early by PPIs, and but the effect might be reversible.

The present study reports the results of comparative structural and mechanical analysis of highly porous PEEK and UHMWPE biomimetic scaffolds and hybrid scaffolds with bulk “cortical”-like and porous “trabecular”-like layers. A technique for the manufacturing of hydrophilic porous PEEK and UHMWPE was proposed and successfully implemented to create novel bi-polymer hybrid biomimetic PEEK/UHMWPE scaffolds. Thermopressing of polymer-NaCl mixtures and further desalination and surface etching were applied to obtain PEEK and UHMWPE scaffolds, having porosity of more than 60 and 90% vol. and pore sizes of 1–40 μm and 80–700 μm, respectively, to imitate the structure of natural cortical and trabecular bone.

Microstructures with spatially-varying properties such as trabecular bone are widely seen in nature. These functionally graded materials possess smoothly changing microstructural topologies that enable excellent micro and macroscale performance. The fabrication of such microstructural materials is now enabled by additive manufacturing (AM). A challenging aspect in the computational design of such materials is ensuring compatibility between adjacent microstructures. Existing works address this problem by ensuring geometric connectivity between adjacent microstructural unit cells. In this paper, we aim to find the optimal connectivity between topology optimized microstructures. Recognizing the fact that the optimality of connectivity can be evaluated by the resulting physical properties of the assemblies, we propose to consider the assembly of adjacent cells together with the optimization of individual cells. In particular, our method simultaneously optimizes the physical properties of the individual cells as well as those of neighbouring pairs, to ensure material connectivity and smoothly varying physical properties. We demonstrate the application of our method in the design of functionally graded materials for implant design (including an implant prototype made by AM), and in the multiscale optimization of structures.

QCT is commonly employed in research studies and clinical trials to measure BMD at the proximal femur. In this study we compared two analysis software options, QCTPro CTXA and MIAF-Femur, using CT scans of the semi-anthropometric European Proximal Femur Phantom (EPFP) and in vivo data from 130 Chinese elderly men and women aged 60–80 years. Integral (Int), cortical (Cort) and trabecular (Trab) vBMD, volume, and BMC of the neck (FN), trochanter (TR), inter-trochanter (IT), and total hip (TH) VOIs were compared. Accuracy was determined in the 5 mm wide central portion of the femoral neck of the EPFP. Nominal values were: cross-sectional area (CSA) 4.9 cm2, cortical thickness (C.Th) 2 mm, CortBMD 723 mg/cm3 and TrabBMD 100 mg/cm3. In MIAF the so-called peeled trabecular VOI was analyzed, which excludes subcortical bone to avoid partial volume artefacts at the endocortical border that artificially increase TrabBMD. For CTXA uncorrected, so called raw cortical values were used for the analysis. QCTPro and MIAF phantom results were: CSA 5.9 cm2 versus 5.1 cm2; C.Th 1.68 mm versus 1.92 mm; CortBMD 578 mg/cm3 versus 569 mg/cm3; and TrabBMD 154 mg/cm3 versus 104 mg/cm3. In vivo correlations (R2) of integral and trabecular bone parameters ranged from 0.63 to 0.96. Bland–Altman analysis for TH and FN TrabBMD showed that lower mean values were associated with higher differences, which means that TrabBMD differences between MIAF and CTXA are larger for osteoporotic than for normal patients, which can be largely explained by the inclusion of subcortical BMD in the trabecular VOI analyzed by CTXA in combination with fixed thresholds used to separate cortical from trabecular bone compartments. Correlations between CTXA corrected CortBMD and MIAF were negative, whereas raw data correlated positively with MIAF measurements for all VOIs questioning the validity of the CTXA corrections. The EPFP results demonstrated higher MIAF accuracy of cortical thickness and TrabBMD. Integral and trabecular bone parameters were highly correlated between CTXA and MIAF. Partial volume artefacts at the endocortical border artificially increased trabecular BMD by CTXA, especially for osteoporosis patients. With respect to volumetric cortical measurements with CTXA, the use raw data is recommended, because corrected data cause a negative correlation with MIAF CortBMD.

Bone is a material that can be classified as a hierarchical structure, where the different structural levels can be identified from the microscale to macroscale. Multiscale models enable to model the material using homogenization techniques. In this work a innovative homogenization technique for trabecular bone tissue is proposed, which uses the fabric tensor concept and a bone phenomenological material law, linking the apparent density with the trabecular bone mechanical proprieties. The proposed methodology efficiently homogenize the trabecular bone highly heterogeneous medium, allowing to define its homogenized microscale mechanical properties and to reduce the analysis computational cost (when compared with classical homogenization techniques). The homogenization technique is combined with the natural neighbour radial point interpolation method (NNRPIM). The NNRPIM uses the natural neighbour mathematical concept to enforce the nodal connectivity and build the background integration mesh, required to numerically integrate the integro-differential elasticity equations. Furthermore, the NNRPIM uses the radial point interpolators technique to construct its interpolating shape functions. In order to verify the efficiency of the technique several examples are solved using a confined square patch of trabecular bone under compression. In the end, the results obtained with a classic homogenization technique and the proposed methodology are compared.

Objective The purpose of this study was to examine the effects of different implant neck designs on securing the quantity and quality of peri-implant hard tissue during the period of healing after implant placement. Materials and methods Three types of implants with different neck morphologies (no thread, a macro-thread, and a micro-thread) were placed in the femur and tibia of six adult male New Zealand white rabbits. After 3 and 8 weeks, animals were sacrificed and subjected to micro-computed tomography (CT) and histological assessments. Results All implants were clinically, radiographically, and histologically osseointegrated at the time of euthanasia. Micro-CT data revealed that the micro-thread design had a higher number and wider trabecular bone attachment than other implant designs after 3 and 8 weeks. The results of toluidine blue staining demonstrated that the percentages of bone-to-implant contact (%BIC) and new bone area (%NBA) were significantly higher with type C than with the other types after 3 weeks. After 8 weeks, the %NBA of type C was higher than that of type A. Conclusion Our results suggest that an implant with a micro-thread at the implant neck promotes faster osteogenesis and a greater amount of new bone around the implant.

Trabecular bone fractures heal through intramembranous ossification. It is a highly porous biological tissue with an open-celled cellular structure, which accounts for up to 20% until 60% of the bone mass in humans for healthy bone while about 80% for an osteoporosis case. In bone healing, there is very little callus formation, woven bone forms directly without a cartilage intermediary, and the woven bone is remodelled to form trabecular bone. Trabecular bone has less mineral and porosity percentages compared to the compact bone. Thus, the stress distributions around the screw were affected by the amount of the porosity within the trabecular bone. In bone healing mechanism, stability may speed up the bone healing process. The interface contact between external fixator pins and screws of internal fixator influence the fixation stability for bone healing. This study aims to investigate the amount of stress distribution on the around screw implant through the trabecular bone porosity condition under pull out loading. Finite element analysis is employed to simulate the stress distribution associated to the screw implant and cortical-trabecular interface As a result, the area of screw head is found to be yielded as the porosity of trabecular bone is considered.

Microcracking in trabecular bone is responsible both for the mechanical degradation and remodeling of the trabecular bone tissue. Recent results on trabecular bone mechanics have demonstrated that bone tissue microarchitecture, tissue elastic heterogeneity and tissue-level mechanical anisotropy all should be considered to obtain detailed information on the mechanical stress state. The present study investigated the influence of tissue microarchitecture, tissue heterogeneity in elasticity and material separation properties and tissue-level anisotropy on the microcrack formation process. Microscale bone models were executed with the extended finite element method. It was demonstrated that anisotropy and heterogeneity of the bone tissue contribute significantly to bone tissue toughness and the resistance of trabecular bone to microcrack formation. The compressive strain to microcrack initiation was computed to increase by a factor of four from an assumed homogeneous isotropic tissue to an assumed anisotropic heterogenous tissue.

Background osteochondritis dissecans (OCD) is an ancient disease with few well-described cases in paleopathological records. Here, we report a very rare case of OCD on both lateral femoral condyles and on the lateral condyle of the right tibia in an early medieval human skeleton. Methods macroscopic examination of the bone vestiges of a young male unearthed from a 6th–8th Lombard cemetery in the northeast Italy was perform. Results We observed a circular crater-like depression with well-defined smooth margins and exposure of the trabecular bone on both lateral femoral condyles and in the lateral condyle of the right tibia. The left tibia was fragmented and the lateral condyle was lacking. Findings are consistent with the diagnosis of multifocal juvenile osteochondritis dissecans of the knee. Conclusion Research in past and modern skeletal remains can contribute to define the nature and distribution of OCD.

The tissue-level Young's modulus of trabecular bone is important for detailed mechanical analysis of bone and bone-implant mechanical interactions. However, the heterogeneity and small size of the trabecular struts complicate an accurate determination. Methods such as micro-mechanical testing of single trabeculae, ultrasonic testing, and nanoindentation have been used to estimate the trabecular Young's modulus. This review summarizes and classifies the trabecular Young's moduli reported in the literature. Information on species, anatomic site, and test condition of the samples has also been gathered. Advantages and disadvantages of the different methods together with recent developments are discussed, followed by some suggestions for potential improvement for future work. In summary, this review provides a thorough introduction to the approaches used for determining trabecular Young's modulus, highlights important considerations when applying these methods and summarizes the reported Young's modulus for follow-up studies on trabecular properties.The spongy trabecular bone provides mechanical support while maintaining a low weight. A correct measure of its mechanical properties at the tissue level, i.e. at a single-trabecula level, is crucial for analysis of interactions between bone and implants, necessary for understanding e.g. bone healing mechanisms. In this study, we comprehensively summarize the Young's moduli of trabecular bone estimated by currently available methods, and report their dependency on different factors. The critical review of different methods with recent updates is intended to inspire improvements in estimating trabecular Young's modulus. It is strongly suggested to report detailed information on the tested bone to enable statistical analysis in the future.

This study compared the fractal dimension (FD) and radiomorphometric indices in the assessment of mandibular bone of patients with type 1 (T1 DM) and type 2 diabetes mellitus (T2 DM).Panoramic radiographs of 104 patients were evaluated to calculate FD, mandibular cortical width (MCW), panoramic mandibular index (PMI), and mandibular cortical index (MCI) in the mandible.No statistically significant differences were found in FD when T1 DM and T2 DM groups were compared with controls (P ≥ .168). Patients with T1 DM had significantly lower MCW (P .001) and PMI (P = .030) compared with controls. Patients with T2 DM had no significant differences in MCW (P = .228) or PMI (P = .137) compared with controls. No significant differences were observed between patients with T1 DM and those with T2 DM for FD, MCW, and PMI (P .05). In the T1 DM and T2 DM groups, there was a significant correlation between MCW and FD (P ≤ .011). No correlation was observed between FD and PMI in either the T1 DM group or the T2 DM group (P ≥ .142). No significant differences in MCI were observed between the DM groups and controls (P = .740) or between the T1 DM and T2 DM groups (P = 1.000).The cortical and trabecular bone architectures of patients with T1 DM and T2 DM were not different. Patients with T1 DM had lower cortical measurements compared with controls.

Summary Objective To examine associations between trabecular bone (TB) texture and magnetic resonance imaging (MRI)-defined osteophytes in finger joints without radiographic osteoarthritis (OA) using an augmented variance orientation transform (AVOT) method. Design In a cross-sectional study, associations of the TB texture and osteophytes were examined in 21 women with mean (standard deviation) age of 69.9 (5.3) from the Oslo Hand OA cohort. The AVOT was applied to distal and proximal TB regions selected on hand radiographs of the subjects. The regions were adjacent to 57 finger joints (24 distal and 33 proximal interphalangeal) without radiographic OA (Kellgren–Lawrence [KL] grade 0), without MRI-defined joint space narrowing (JSN), bone marrow lesions (BMLs), attrition, erosion, cysts, sclerosis, malalignment (all MRI grades 0) and without or only with mild synovitis (MRI grade 0 or 1). Bone texture parameters were calculated: mean fractal dimension (FD MEAN ), FDs in the horizontal (FD H ) and vertical (FD V ) directions, and along the roughest part (FD Sta ). Associations between the parameters categorized into groups using tertiles and osteophytes were evaluated using logistic regression adjusted for age. Results Lower FD Sta and FD V in the distal TB regions were associated with increased odds of MRI-defined osteophytes ( P Conclusions Lower mean roughness and lower roughness in vertical and roughest directions of the proximal TB texture are associated with MRI-defined osteophytes in finger joints without radiographic OA. These findings suggest that TB texture may be a useful marker for detecting early hand OA.

Vertebroplasty (VP) is a minimally invasive surgical procedure commonly used to relieve severe back pain associated with vertebral compression fractures. The poly(methyl methacrylate) bone cement used during this procedure is however presumed to facilitate the occurrence of additional fractures next to the treated vertebrae. A reason for this is believed to be the difference in stiffness between the bone cement and the surrounding trabecular bone. The use of bone cements with lower mechanical properties could therefore reduce the risk of complications post-surgery. While intensive research has been performed on the quasi-static mechanical properties of these cements, there is no data on their long-term mechanical properties. In the present study, the in vitro compressive fatigue performance as well as quasi-static mechanical properties of two commercially available acrylic bone cements – a low-modulus cement (Resilience®) and a standard cement (F20) from the same manufacturer – were determined. The quasi-static mechanical properties of the low-modulus and standard cements after 24 h of setting were in the range of other vertebroplastic cements (σ = 70–75 MPa; E= 1600–1900 MPa). F20 displayed similar mechanical properties over time in 37 °C phosphate buffered saline solution, while the mechanical properties of the Resilience® cement decreased gradually due to an increased porosity in the polymeric matrix. The standard cement exhibited a fatigue limit of approx. 47 MPa, whereas the low-modulus cement showed a fatigue limit of approx. 31 MPa. In summary, the low-modulus bone cement had a lower fatigue limit than the standard cement, as expected. However, this fatigue limit is still substantially higher than the stresses experienced by vertebral trabecular bone.

Background Approximately 16–24% of postmenopausal women are affected by vertebral fractures, negatively affecting their quality of life. Trabecular and cortical bones in vertebrae decline differently with age, thus having a distinct impact on vertebral failure loads. The purpose of this study was to investigate the effect of trabecular and cortical volumetric bone mineral density loss over time on estimated failure loads; and to evaluate the effect of sex and age. Method Fracture properties from a cohort of 82 patients were evaluated for L1–L3 vertebrae at baseline and 6th year using an image-based method that implements axial rigidity analysis. Cortical and trabecular volumetric bone mineral density were obtained, as well as their individual contribution to total failure load. Regression analyses were performed to determine the effect of age and sex on volumetric bone mineral density and failure loads. Findings Decline in trabecular and cortical volumetric bone mineral density, and failure load was sex-dependent (p ≤ 0.0095). Cortical and trabecular volumetric bone mineral density reduced 2.08 (g/cm3)/year and 2.02 (g/cm3)/year, respectively. A 1012 N difference in failure load, ~70% attributed to trabecular bone, was found between men and women of similar age. Over 6 years, this difference increased by 287 N. Areal bone mineral density measured by dual X-ray absorptiometry explained ~60% of the vertebral failure load. Interpretation Trabecular bone has a significantly greater effect than cortical bone on the structural integrity and load bearing capacity of vertebrae. This might lead to a higher incidence of fragility fractures in osteoporotic women. Our non-invasive, quantitative computed tomography image-based approach may improve prevention, monitoring, and management of fractures.

A 66 year-old woman with a disproportionate dwarfism and who bore seven children was discovered at the Middenbeemster archaeological site (The Netherlands). Three are perinates and show no macroscopic or radiological evidence for a FGFR3 mutation causing hypo-or achondroplasia. This mutation induces dysfunction of the growth cartilage, leading to abnormalities in the development of trabecular bone. Because the mutation is autosomal dominant, these perinates have a 50% risk of having been affected. This study determines whether trabecular bone microarchitecture (TBMA) analysis is useful for detecting genetic dwarfism. Proximal metaphyses of humeri were μCT-scanned with a resolution of 7–12 μm. Three volumes of interest were segmented from each bone with TIVMI© software. The TBMA was quantified in BoneJ© using six parameters on which a multivariate analysis was then performed. Two of the Middenbeemster perinates show a quantitatively different TBMA organization. These results and the family’s medical history suggest a diagnosis of genetic dwarfism for this two perinates. This study provides evidence to support the efficacy of μCT for diagnosing early-stage bone disease.

Architected UHMWPE 3D open-cell porous scaffolds simulating anisotropic trabecular bone tissue were designed and produced by a combination of 3D-printing, powder filling and hot molding, and final leaching. SEM investigations confirmed the high perfection of the struts and nodes in the open cell architecture with pore diameters in the range 0.7–3 mm. The scaffold surface texture was characterized by 250 μm asperities formed by templating of UHMWPE on the surface of PLA sacrificial 3D-printed matrix.