Subchondral Bone Region Research Articles

Histological and Histopathological Features of the Third Metacarpal/Tarsal Parasagittal Groove and Proximal Phalanx Sagittal Groove in Thoroughbred Horses with Racing History.

Information regarding the histopathology of the proximal phalanx (P1) sagittal groove in racehorses is limited. Twenty-nine cadaver limbs from nine Thoroughbred racehorses in racing/race-training underwent histological examination. Histological specimens of the third metacarpal/metatarsal (MC3/MT3) parasagittal grooves and P1 sagittal grooves were graded for histopathological findings in hyaline cartilage (HC), calcified cartilage (CC), and subchondral plate and trabecular bone (SCB/TB) regions. Histopathological grades were compared between (1) fissure and non-fissure locations observed in a previous study and (2) dorsal, middle, and palmar/plantar aspects. (1) HC, CC, and SCB/TB grades were more severe in fissure than non-fissure locations in the MC3/MT3 parasagittal groove (p < 0.001). SCB/TB grades were more severe in fissure than non-fissure locations in the P1 sagittal groove (p < 0.001). (2) HC, CC, and SCB/TB grades including SCB collapse were more severe in the palmar/plantar than the middle aspect of the MC3/MT3 parasagittal groove (p < 0.001). SCB/TB grades including SCB collapse were more severe in the dorsal and middle than the palmar/plantar aspect of the P1 sagittal groove (p < 0.001). Histopathology in the SCB/TB region including bone fatigue injury was related to fissure locations, the palmar/plantar MC3/MT3 parasagittal groove, and the dorsal P1 sagittal groove.

Alterations in compositional and cellular properties of the subchondral bone are linked to cartilage degeneration in hip osteoarthritis

ObjectiveThe subchondral bone is an emerging regulator of osteoarthritis (OA). However, knowledge of how specific subchondral alterations relate to cartilage degeneration remains incomplete. MethodFemoral heads were obtained from 44 patients with primary OA during total hip arthroplasty and from 30 non-OA controls during autopsy. A multiscale assessment of the central subchondral bone region comprising histomorphometry, quantitative backscattered electron imaging, nanoindentation, and osteocyte lacunocanalicular network characterization was employed. ResultsIn hip OA, thickening of the subchondral bone coincided with a higher number of osteoblasts (controls: 3.7±4.5 mm-1, OA: 16.4±10.2 mm-1, age-adjusted mean difference 10.5 mm-1 [95% CI 4.7 to 16.4], p<0.001) but a similar number of osteoclasts compared to controls (p=0.150). Furthermore, higher matrix mineralization heterogeneity (CaWidth, controls: 2.8±0.2 wt%, OA: 3.1±0.3 wt%, age-adjusted mean difference 0.2 wt% [95% CI 0.1 to 0.4], p=0.011) and lower tissue hardness (controls: 0.69±0.06 GPa, OA: 0.67±0.06 GPa, age-adjusted mean difference -0.05 GPa [95% CI -0.09 to -0.01], p=0.032) were detected. While no evidence of altered osteocytic perilacunar/canalicular remodeling in terms of fewer osteocyte canaliculi was found in OA, specimens with advanced cartilage degeneration showed a higher number of osteocyte canaliculi and larger lacunocanalicular network area compared to those with low-grade cartilage degeneration. Multiple linear regression models indicated that several subchondral bone properties, especially osteoblast and osteocyte parameters, were closely related to cartilage degeneration (R2 adjusted=0.561, p<0.001). ConclusionSubchondral bone properties in OA are affected at the compositional, mechanical, and cellular levels. Based on their strong interaction with cartilage degeneration, targeting osteoblasts/osteocytes may be a promising therapeutic OA approach. Data and materials availabilityAll data are available in the main text or the supplementary materials.

Mechanical response of local regions of subchondral bone under physiological loading conditions

Most fractures in the third metacarpal bone of equine athletes occur due to repeated cycles of high load magnitudes and are commonly generated during fast-training workouts. These repetitive loads may induce changes in the microstructure and mechanical properties that can develop into subchondral bone (SCB) injuries near the articular surface. In this study, we investigated the fatigue behaviour of local regions in SCB (near the articular surface i.e., 2 mm superficial SCB and the underlying 2 mm deeper SCB) under a simulated fast-training workout of an equine athlete. A fatigue test on SCB specimens was designed to simulate the fast-training workout, which comprised of repeated load cycles with varying load magnitude, representing the varying gait speed during a fast-training workout. The fatigue test was applied three times to each of the five cylindrical SCB specimens harvested from the left and right metacarpal condyles of five thoroughbred racehorses). All specimens completed at least one fatigue test. Three specimens completed all three fatigue tests with no visible cracks identified with Micro-CT scans. The other two specimens failed in the second fatigue test, and cracks were identified with Micro-CT scans in the various local regions. Using Digital Image Correlation (DIC) analysis, we found that in the local regions of all specimens, modulus decreased between load cycles corresponding to 68 and 93 MPa load magnitudes (equivalent to the fastest gallop speed). Wherein specimens that failed exhibited a greater decrease in modulus (in superficial SCB by 45.64 ± 5.66% and in deeper SCB by −36.85 ± 10.47% (n = 2)) than those not failed (in superficial SCB by −7.45 ± 14.62% and in deeper SCB by −5.67 ± 7.32% (n = 3)). This has provided evidence that the loads on SCB at galloping speeds are most likely to produce fatigue damage and that the damage induced is localised. Furthermore, one of the failed specimens exhibited a peak in the tensile strain rather than compressive strain in the superficial region with a rapid decrease in modulus. In addition, the superficial region of all specimens exhibited greater residual tensile strain than that of the deeper region.

Development of a method to investigate strain distribution across the cartilage-bone interface in guinea pig model of spontaneous osteoarthritis using lab-based contrast enhanced X-ray-computed tomography and digital volume correlation

ObjectiveStrain changes at the cartilage-bone interface play a crucial role in osteoarthritis (OA) development. Contrast-Enhanced X-ray Computed Tomography (CECT) and Digital Volume Correlation (DVC) can measure 3D strain changes at the osteochondral interface. Using lab-based CT systems it is often difficult to visualise soft tissues such as articular cartilage without staining to enhance contrast. Contrast-Enhancing Staining Agents (CESAs), such as Phosphotungstic Acid (PTA) in 70% ethanol, can cause tissue shrinkage and alter tissue mechanics. The aims of this study were, firstly, to assess changes to the mechanical properties of osteochondral tissue after staining with a PTA/PBS solution, and secondly, to visualise articular cartilage during loading and with CECT imaging in order to compare strain across the interface in both healthy and OA joints using DVC. DesignNanoindentation was used to assess changes to mechanical properties in articular cartilage and subchondral bone before and after staining. Hindlimbs from Dunkin-Hartley guinea pigs were stained with 1% PTA/PBS at room temperature for 6 days. Two consecutive CECT datasets were acquired for DVC error analysis. In-situ compression with a load corresponding to 2x body weight was applied, the specimen was re-imaged, and DVC was performed between the pre- and post-load tomograms. ResultsNanoindentation before and after PTA/PBS staining showed similar cartilage stiffness (p < 0.05), however, staining significantly decreased the stiffness of subchondral bone (∼9-fold; p = 0.0012). In severe OA specimens, third principal/compressive (εp3) strain was 141.7% higher and shear strain (γ) was 98.2% higher in tibial articular cartilage compared to non-OA (2 – month) specimens. A 23.1% increase in third principal stain strain and a 54.5% significant increase in the shear (γ) strain (p = 0.0027) was transferred into the mineralised regions of calcified cartilage and subchondral bone in severe OA specimens. ConclusionsThese results indicate the suitability of PTA in PBS as a contrast agent for the visualisation of cartilage during CECT imaging and allowed DVC computation of strain across the cartilage-bone interface. However, further research is needed to address the reduction in stiffness of subchondral bone after incubation in PBS.

Ultra-high field magnetic resonance imaging of the quadriceps tendon enthesis in healthy subjects.

Although enthesitis is a hallmark of several rheumatologic conditions, current imaging methods are still unable to characterize entheses changes because of the corresponding short transverse relaxation times (T2). A growing number of MR studies have used Ultra-High Field (UHF) MRI in order to assess low-T2 tissues e.g., tendon but never in humans. The purpose of the present study was to assess in vivo the enthesis of the quadriceps tendon in healthy subjects using UHF MRI. Eleven healthy subjects volunteered in an osteoarthritis imaging study. The inclusion criteria were: no knee trauma, Lequesne index = 0, less than 3h of sport activities per week, and Kellgren and Lawrence grade = 0. 3D MR images were acquired at 7T using GRE sequences and a T2* mapping. Regions of interest i.e., trabecular bone, subchondral bone, enthesis, and tendon body were identified, and T2* values were quantified and compared. Quadriceps tendon enthesis was visible as a hyper-intense signal. The largest and the lowest T2* values were quantified in the subchondral bone region and the tendon body respectively. T2* value within subchondral bone was significantly higher than T2* value within the enthesis. T2* in subchondral bone region was significantly higher than the whole tendon body T2*. A T2* gradient was observed along the axis from the enthesis toward the tendon body. It illustrates different water biophysical properties. These results provide normative values which could be used in the field of inflammatory rheumatologic diseases and mechanical disorders affecting the tendon.

AUTOMATIC SEGMENTATION AND BONE ARCHITECTURE ANALYSIS OF SUBCHONDRAL BONE IN THE MURINE PROXIMAL TIBIA: EVALUATION OF AN OPEN-SOURCE PIPELINE

µCT images are commonly analysed to assess changes in bone density and architecture in preclinical murine models. Several platforms provide automated analysis of bone architecture parameters from volumetric regions of interest (ROI). However, segmentation of the regions of subchondral bone to create the volumetric ROIs remains a manual and time-consuming task. This study aimed to develop and evaluate automated pipelines for trabecular bone architecture analysis of mouse proximal tibia subchondral bone.A segmented dataset involving 62 knees (healthy and arthritic) from 10-week male C57BL/6 mice were used to train a U-Net type architecture, with µCT scans (downsampled) input that output segmentation and bone volume density (BV/TV) of the subchondral trabecular bone. Segmentations were upsampled and used in tandem with the original scans (10µ) as input for architecture analysis along with the thresholded trabecular bone. The analysis considered the manually and U-Net segmented ROIs using two available pipelines: the ITKBoneMorphometry library and CTan (SKYSCAN). The analyses included: bone volume (BV), total volume (TV), BV/TV, trabecular number (TbN), trabecular thickness (TbTh), trabecular separation (TbSp), and bone surface density (BSBV).There was good agreement for bone measures between the manual and U-Net pipelines utilizing ITK (R=0.88-0.98) and CTan (R=0.91-0.98). ITK and CTan showed good agreement for BV, TV, BV/TV, TbTh and BSBV (R=0.9-0.98). However, a limited agreement was seen between TbN (R=0.73) and TbSb (R=0.59) due to methodological differences in how spacing is evaluated.This U-Net/ITK pipeline seamlessly automated both segmentation and quantification of the proximal tibia subchondral bone. This automated pipeline allows the analysis of large volumes of data, and its open-source nature may enable the standardization of stereologic analysis of trabecular bone across different research groups.

Open-source pipeline for automatic segmentation and microstructural analysis of murine knee subchondral bone.

A segmented dataset of μCT scans from 62 knees (healthy and arthritic) from 10-week male C57BL/6 mice was used to train a U-Net type architecture to automate segmentation of the subchondral trabecular bone. These segmentations were used in tandem with the original scans as input for microstructural analysis along with thresholded trabecular bone. Manually and U-Net segmented ROIs were fed into two available pipelines for microstructural analysis: the ITKBoneMorphometry library and CTan (SKYSCAN). Outcome parameters were compared between pipelines, including: bone volume (BV), total volume (TV), BV/TV, trabecular number (TbN), trabecular thickness (TbTh), trabecular separation (TbSp), and bone surface density (BSBV). There was good agreement for all bone measures comparing the manual and U-Net pipelines utilizing ITK (R = 0.88-0.98) and CTAn (R = 0.91-0.98). ITK and CTAn showed good agreement for BV, TV, BV/TV, TbTh and BSBV (R = 0.9-0.98). However, limited agreement was seen between TbN (R = 0.73) and TbSb (R = 0.59) due to methodological differences in how spacing is evaluated. Microstructural parameters generated from manual and automatic segmentations showed high correlation across all measures. Using the CTAn pipeline yielded strong R2 values (0.83-0.96) and very strong agreement based on ICC (0.90-0.98). The ITK pipeline yielded similarly high R2 values (0.91-0.96, except for TbN (0.77)), and ICC values (0.88-0.98). The automated segmentations yield lower average values for BV, TV and BV/TV (ranging from 14 % to 6.3 %), but differences were not found to be influenced by the mean ROI values. This integrated pipeline seamlessly automated both segmentation and quantification of the proximal tibia subchondral bone microstructure. This automated pipeline allows the analysis of large volumes of data, and its open-source nature may enable the standardization of microstructural analysis of trabecular bone across different research groups.

Osteochondral regenerative engineering: challenges, state-of-the-art and translational perspectives.

Despite quantum leaps, the biomimetic regeneration of cartilage and osteochondral regeneration remains a major challenge, owing to the complex and hierarchical nature of compositional, structural and functional properties. In this review, an account of the prevailing challenges in biomimicking the gradients in porous microstructure, cells and extracellular matrix (ECM) orientation is presented. Further, the spatial arrangement of the cues in inducing vascularization in the subchondral bone region while maintaining the avascular nature of the adjacent cartilage layer is highlighted. With rapid advancement in biomaterials science, biofabrication tools and strategies, the state-of-the-art in osteochondral regeneration since the last decade has expansively elaborated. This includes conventional and additive manufacturing of synthetic/natural/ECM-based biomaterials, tissue-specific/mesenchymal/progenitor cells, growth factors and/or signaling biomolecules. Beyond the laboratory-based research and development, the underlying challenges in translational research are also provided in a dedicated section. A new generation of biomaterial-based acellular scaffold systems with uncompromised biocompatibility and osteochondral regenerative capability is necessary to bridge the clinical demand and commercial supply. Encompassing the basic elements of osteochondral research, this review is believed to serve as a standalone guide for early career researchers, in expanding the research horizon to improve the quality of life of osteoarthritic patients affordably.

Using Radiomics to Detect Subtle Architecture Changes of Cartilage and Subchondral Bone in Chronic Lateral Ankle Instability Patients Based on MRI PD-FS Images

To use radiomics to detect the subtle changes of cartilage and subchondral bone in chronic lateral ankle instability (CLAI) patients based on MRI PD-FS images. A total of 215 CLAI patients and 186 healthy controls were included and randomly split into a training set (n=281, patients/controls=151/130) and an independent test set (n=120, patients/controls=64/56). They underwent ankle MRI examinations. On sagittal PD-FS images, eight cartilage regions and their corresponding subchondral bone regions were drawn. Radiomics models of cartilage, subchondral bone and combined cartilage and subchondral bone were built to differentiate CLAI patients from controls. A receiver operating characteristic curve (ROC) was used to assess the model's performance. In the test dataset, the cartilage model yielded an area under the curve (AUC) of 0.0.912 (95% confidence interval (CI): 0.858-0.965, p<0.001), a sensitivity of 0.859, a specificity of 0.893, a negative predictive value (NPV) of 0.848, and a positive predictive value (PPV) of 0.902. The subchondral bone model yielded an AUC of 0.837 (95% CI: 0.766-0.907, p<0.001), a sensitivity of 0.875, a specificity of 0.714, an NPV of 0.833, and a PPV of 0.778. For the combined model, the AUC was 0.921 (95% CI: 0.863-0.972, p<0.001), sensitivity was 0.844, specificity was 0.911, NPV was 0.836, and PPV was 0.915, whose AUC was higher than those of both the cartilage model and the subchondral bone model. The combined radiomics model achieved satisfying performance in detecting potential early architectural changes in cartilage and subchondral bone for CLAI patients.

Subchondral bone plate thickness is associated with micromechanical and microstructural changes in the bovine patella osteochondral junction with different levels of cartilage degeneration

The influence of joint degeneration on the biomechanical properties of calcified cartilage and subchondral bone plate at the osteochondral junction is relatively unknown. Common experimental difficulties include accessibility to and visualization of the osteochondral junction, application of mechanical testing at the appropriate length scale, and availability of tissue that provides a consistent range of degenerative changes. This study addresses these challenges.A well-established bovine patella model of early joint degeneration was employed, in which micromechanical testing of fully hydrated osteochondral sections was carried out in conjunction with high-resolution imaging using differential interference contrast (DIC) optical light microscopy. A total of forty-two bovine patellae with different grades of tissue health ranging from healthy to mild, moderate, and severe cartilage degeneration, were selected. From the distal–lateral region of each patella, two adjacent osteochondral sections were obtained for the mechanical testing and the DIC imaging, respectively. Mechanical testing was carried out using a robotic micro-force acquisition system, applying compression tests over an array (area: 200 μm × 1000 μm, step size: 50 μm) across the osteochondral junction to obtain a stiffness map. Morphometric analysis was performed for the DIC images of fully hydrated cryo-sections. The levels of cartilage degeneration, DIC images, and the stiffness maps were used to associate the mechanical properties onto the specific tissue regions of cartilage, calcified cartilage, and subchondral bone plate.The results showed that there were up to 20% and 24% decreases (p < 0.05) in the stiffness of calcified cartilage and subchondral bone plate, respectively, in the severely degenerated group compared to the healthy group. Furthermore, there were increases (p < 0.05) in the number of tidemarks, bone spicules at the cement line, and the mean thickness of the subchondral bone plate with increasing levels of degeneration.The decreasing stiffness in the subchondral bone plate coupled with the presence of bone spicules may be indicative of a subchondral remodeling process involving new bone formation. Moreover, the mean thickness of the subchondral bone plate was found to be the strongest indicator of mechanical and associated structural changes in the osteochondral joint tissues.

Insight into the potential pathogenesis of human osteoarthritis via single-cell RNA sequencing data on osteoblasts.

Osteoarthritis (OA) is the most common degenerative joint disease caused by osteoblastic lineage cells. However, a comprehensive molecular program for osteoblasts in human OA remains underdeveloped. The single-cell gene expression of osteoblasts and microRNA array data were from human. After processing the single-cell RNA sequencing (scRNA-seq) data, it was subjected to principal component analysis (PCA) and T-Stochastic neighbor embedding analysis (TSNE). Differential expression analysis was aimed to find marker genes. Gene-ontology (GO) enrichment, Kyoto encyclopedia of genes and genomes (KEGG) pathway enrichment analysis and Gene set enrichment analysis (GSEA) were applied to characterize the molecular function of osteoblasts with marker genes. Protein-protein interaction (PPI) networks and core module were established for marker genes by using the STRING database and Cytoscape software. All nodes in the core module were considered to be hub genes. Subsequently, we predicted the potential miRNA of hub genes through the miRWalk, miRDB and TargetScan database and experimentally verified the miRNA by GSE105027. Finally, miRNA-mRNA regulatory network was constructed using the Cytoscape software. We characterized the single-cell expression profiling of 4387 osteoblasts from normal and OA sample. The proportion of osteoblasts subpopulations changed dramatically in the OA, with 70.42% of the pre-osteoblasts. 117 marker genes were included and the results of GO analysis show that up-regulated marker genes enriched in collagen-containing extracellular matrix were highly expressed in the pre-osteoblasts cluster. Both KEGG and GSEA analyses results indicated that IL-17 and NOD-like receptor signaling pathways were enriched in down-regulated marker genes. We visualize the weight of marker genes and constructed the core module in PPI network. In potential mRNA-miRNA regulatory network, hsa-miR-449a and hsa-miR-218-5p may be involved in the development of OA. Our study found that alterations in osteoblasts state and cellular molecular function in the subchondral bone region may be involved in the pathogenesis of osteoarthritis.

Radiomics Feature Analysis of Cartilage and Subchondral Bone in Differentiating Knees Predisposed to Posttraumatic Osteoarthritis after Anterior Cruciate Ligament Reconstruction from Healthy Knees.

Objectives To introduce a new implementation of radiomics analysis for cartilage and subchondral bone of the knee and to compare the performance of the proposed models to classic T2 relaxation time in distinguishing knees predisposed to posttraumatic osteoarthritis (PTOA) after anterior cruciate ligament reconstruction (ACLR) and healthy controls. Methods 114 patients following ACLR after at least 2 years and 43 healthy controls were reviewed and allocated to training (n = 110) and testing (n = 47) cohorts. Radiomics models are built for cartilage and subchondral bone regions of different compartments: lateral femur (LF), lateral tibia (LT), medial femur (MF), and medial tibia (MT) and combined models of four compartments on T2 mapping images. The model performance of discrimination between patients and controls was illustrated with the receiver operating characteristic curve and compared with a classic T2 value-based model. Results The T2 value model of cartilage yielded moderate predictive performance in discerning patients and controls, with an AUC of 0.731 (95% confidence interval, 0.556–0.875) in the testing cohort, while the radiomics signature of cartilage and subchondral bone of different compartments demonstrated excellent performance, with AUCs of 0.864–0.979. Furthermore, the combined model reported an even better performance, with AUCs of 0.977 (95% confidence interval, 0.919–1.000) for the cartilage and 0.934 (95% confidence interval, 0.865–0.994) for the subchondral bone in the testing cohort. Conclusion The radiomics features of the cartilage and subchondral bone may be able to provide powerful tools with more sensitive detection than T2 values in differentiating knees at risk for PTOA after ACLR from healthy knees.

Treatment of Degenerative Disc Disease associated with Modic changes, with ozone therapy. A new therapeutic proposal.

Introduction.&#x0D; Modic Changes (MCs) represent signal changes in the vertebral endplate and subchondral bone region visualized on T1 and T2 weighted magnetic resonance images (MRI). Three types of MCs It have been identified (Types 1 to 3). Modic changes are commonly associated with low-back pain (LBP). &#x0D; In the last few years scientific papers have shown that one of the causes of MCs (fundamentally, the MCs type 1) is the infection caused by an anaerobic bacterium of very low virulence: Propionibacterium acnes (P. acnes). This bacterium resides on the human skin, oral cavity, intestinal tract, and external ear canal as normal flora. As a consequence of tooth brushing and endodontic-therapy, could invade the blood stream leading to transient bacteremia. The authors propose a treatment which consists of Amoxicillin-clavulanate (500 mg/125 mg) three times a day, at 8-hour intervals, for 90 days/100 days.&#x0D; Objectives.&#x0D; Ozone therapy could be the gold standard therapy for MC1 because ozone is a powerful anti-microbial, anti-inflammatory and analgesic agent, which regulates oxidative stress, immune system and oxygen metabolism. &#x0D; Materials and Methods &#x0D; Patients with LBP lasting 6 months or more and MC1 confirmed by MRI of lumbar spine L3/L4 or L4/L5 or L5/S1 and who responded with 5 or more points on the VAS scale were treated with three intradiscal sessions of ozone therapy and ten paravertebral sessions. &#x0D; Results.&#x0D; Patients who were treated with ozone therapy according to our treatment proposal showed a substantial improvement on VAS comparing the beginning and the end of the treatment. They show a significant difference in pain, and general condition. However, these results were not reflected on ODI scale, neither on the MRI but we could notice certain improvements.

Giant Intraosseous Cyst-Like Lesions of the Metacarpal Bones in Rheumatoid Arthritis.

The purpose of this study was to illustrate the clinical and imaging properties of giant intraosseous cyst-like lesions (GICLs) of the metacarpal bones extending beyond the central diaphysis in rheumatoid arthritis (RA) patients on magnetic resonance (MR) images. A keyword search was conducted to extract GICLs of the metacarpal bones out of MR reports in RA patients. There were nine GICLs extending from the subchondral bone region beyond the central diaphysis of the metacarpal bones on MR images in eight subjects with RA (seven females, one male). The age range was from 60 to 87 years with a median age of 65.5 years. The average disease duration was 13.1 years. As for the disease activity, one was low, six were moderate and one was high. None of the nine lesions were visible on radiography. The Steinbrocker stage distribution was as follows: I (n = 3), II (n = 2), and III (n = 3). Intraosseous cyst-like lesion of the metacarpal bones on MR images is a relatively rare manifestation in patients with long-standing RA. Although the lesion seems to be derived from subcortical bone break, it is not necessarily erosive in nature.

Fully automated algorithm for the detection of bone marrow oedema lesions in patients with axial spondyloarthritis – Feasibility study

In the present paper we propose an automated procedure for the detection of bone marrow oedema lesions in patients with axial spondyloarthritis (axSpA). The procedure is based on MRI examination of the sacroiliac joints of 30 patients with confirmed sacroiliitis in the course of axSpA (18 of patients were male, while 12 of patients were female; the mean age of patients was 28.8 ± 9.0 years, range from 18 to 45 years). The segmentation of the sacral and iliac bones is performed using U-Net-like architecture. The subchondral bone regions are found, where inflammatory changes are expected to appear. Convolutional classification architectures are trained to classify image voxels as either being within normal or inflammatory-changed areas. The deep learning-based classification of voxels is compared to a method based on statistical testing. The Dice coefficient for segmentation of subchondral bone was 0.84 (standard deviation 0.06). The sensitivity of the detection of inflammatory changes was 0.88. The specificity of the detection of inflammatory changes was 0.91. The discrepancy between sensitivity and specificity values achieved by the automated method and the human readers is attributed to “a satisfaction of search” phenomenon. After verification of the automated detections by human readers sensitivity and specificity increased to 0.95 and 0.96, respectively. The Spearman’s correlation coefficient between the volumes of lesions calculated manually and automatically is equal to 0.866 while the intraclass coefficient of correlation ICC(1,1) is equal to 0.947. The study demonstrates that an automated detection of inflammatory lesions with high precision of lesion volume assessment is feasible.The codes are freely available at the site:https://github.com/krzysztofrzecki/bone-marrow-oedema-detection.The data are freely available at the site:https://www.kaggle.com/krzysztofrzecki/bone-marrow-oedema-data.

Genetic expression differences of 11 beta-hydroxysteroid dehydrogenase in the bone microvascular endothelial cells derived from different regions of the human femoral head

Objective: To investigate the expression levels and activation differences of 11beta-hydroxysteroid dehydrogenase (11beta-HSD) gene in bone microvascular endothelial cells (BMECs) in different regions of human femoral head. Methods: Tissue specimens of femoral heads were obtained from hip arthroplasty carried out in China-Japan Friendship Hospital from January 2017 to June 2018. And the BMECs we isolated, purified, identified and cultured from different regions of the human femoral head: in the subchondral and cancellous bone regions. The BMECs from the two regions were intervened by hydrocortisone with a series of low concentration gradients (0, 0.03, 0.06, 0.10 mg/ml) respectively. The cell phenotype and functional status of BMECs and cell migration were detected by scratch experiments, and the angiogenesis in different regions of the femoral head was observed. The mRNA and protein expression of 11beta-HSD1, 11beta-HSD2 in BMECs were detected by real-time fluorescence quantitative polymerase chain reaction (RT-PCR) and Western-blot method, respectively. Results: With the increase of the concentration of hydrocortisone, the 11beta-HSD1 mRNA and protein expression of BMECs in the subchondral and cancellous bone regions of the femoral head increased significantly, and the 11beta-HSD1 mRNA and protein expression of BMECs in the subchondral bone region was significantly lower than those in cancellous bone region (all P<0.05). The 11beta-HSD2 mRNA and protein expression of BMECs in the cancellous bone region showed a slow decrease first and then increased slightly at 0.10 mg/ml, while the expression in the subchondral bone region was the opposite. The 11beta-HSD2 mRNA and protein expression of BMECs in subchondral bone region was slightly higher than those in cancellous bone region (all P<0.05), but there was no significant statistical difference between the two regions at 0.10 mg/ml (0.123±0.018 vs 0.126±0.021, 0.577±0.231 vs 0.609±0.174, t=1.380, 0.409, both P>0.05). At different times of the 0.06 mg/ml hydrocortisone intervention, there was no significant differences in scratch closure rate, the number of BMECs lumen, the number of buds and the length of tubule branches in different regions of the femoral head (all P>0.05). Conclusion: The 11beta-HSD expression of BMECs in different regions of human femoral head is significantly different. The 11beta-HSD1 is high-expressed, but 11beta-HSD2 is low-expressed in BMECs of the cancellous bone region, and those are opposite in the subchondral bone region, which helps to explain the pathological characteristics and pathogenesis of hormonal osteonecrosis.

Evaluation of impaired growth plate development of long bones in skeletally immature mice by antirheumatic agents.

Restriction of physical growth and development is a known problem in patients with juvenile idiopathic arthritis (JIA). However, the effect of medical treatment for JIA on skeletal growth in affected children has not been properly investigated. We, therefore, hypothesize that naproxen and methotrexate (MTX) affect endochondral ossification and will lead to reduced skeletal development. Treatment of ATDC5 cells, an in vitro model for endochondral ossification, with naproxen or MTX resulted in increased chondrogenic but decreased hypertrophic differentiation. In vivo, healthy growing C57BL/6 mice were treated with naproxen, MTX, or placebo for 10 weeks. At 15 weeks postnatal, both the length of the tibia and the length of the femur were significantly reduced in the naproxen‐ and MTX‐treated mice compared to their controls. Growth plate analysis revealed a significantly thicker proliferative zone, while the hypertrophic zone was significantly thinner in both experimental groups compared to their controls, comparable to the in vitro results. Micro‐computed tomography analysis of the subchondral bone region directly below the growth disc showed significantly altered bone microarchitecture in naproxen and MTX groups. In addition, the involvement of the PTHrP‐Ihh loop in naproxen‐ and MTX‐treated cells was shown. Overall, these results demonstrate that naproxen and MTX have a profound effect on endochondral ossification during growth plate development, abnormal subchondral bone morphology, and reduced bone length. A better understanding of how medication influences the development of the growth plate will improve understanding of endochondral ossification and reveal possibilities to improve the treatment of pediatric patients.

Noggin Inhibits IL-1β and BMP-2 Expression, and Attenuates Cartilage Degeneration and Subchondral Bone Destruction in Experimental Osteoarthritis.

Osteoarthritis (OA) is a chronic inflammatory and progressive joint disease that results in cartilage degradation and subchondral bone remodeling. The proinflammatory cytokine interleukin 1 beta (IL-1β) is abundantly expressed in OA and plays a crucial role in cartilage remodeling, although its role in the activity of chondrocytes in cartilage and subchondral remodeling remains unclear. In this study, stimulating chondrogenic ATDC5 cells with IL-1β increased the levels of bone morphogenetic protein 2 (BMP-2), promoted articular cartilage degradation, and enhanced structural remodeling. Immunohistochemistry staining and microcomputed tomography imaging of the subchondral trabecular bone region in the experimental OA rat model revealed that the OA disease promotes levels of IL-1β, BMP-2, and matrix metalloproteinase 13 (MMP-13) expression in the articular cartilage and enhances subchondral bone remodeling. The intra-articular injection of Noggin protein (a BMP-2 inhibitor) attenuated subchondral bone remodeling and disease progression in OA rats. We also found that IL-1β increased BMP-2 expression by activating the mitogen-activated protein kinase (MEK), extracellular signal-regulated kinase (ERK), and specificity protein 1 (Sp1) signaling pathways. We conclude that IL-1β promotes BMP-2 expression in chondrocytes via the MEK/ERK/Sp1 signaling pathways. The administration of Noggin protein reduces the expression of IL-1β and BMP-2, which prevents cartilage degeneration and OA development.

3D printing multiphasic osteochondral tissue constructs with nano to micro features via PCL based bioink

Osteochondral tissue has a complex graded structure where biological, physiological, and mechanical properties vary significantly over the full thickness spanning the subchondral bone region beneath the joint surface to the hyaline cartilage region at the joint surface. This presents a significant challenge for tissue-engineered structures addressing osteochondral defects. Advanced bioinks, together with 3D bioprinters, may present a unique solution to this problem. The objective of this research is to apply innovative bioinks, and integrate fused deposition modeling (FDM) 3D printing with a casting technique to fabricate novel osteochondral tissue constructs for improved bone marrow human mesenchymal stem cell (hMSC) functions. Specifically, a multiphasic construct with different layer geometries was designed. A polycaprolactone (PCL) based shape memory material which is comprised of polycaprolactone-triol, castor oil, and poly(hexamethylene diisocyanate) was used as the osteochondral matrix material for the first time. Nanocrystalline hydroxyapatite (nHA) was synthesized and printed into the subchondral bone layers and chondrogenic growth factors were fabricated into the cartilage layer. The results show that the 3D printed constructs with nHA and bioactive cues have improved mechanical properties and enhanced hMSC adhesion, growth, and differentiation. This study indicates that both mechanical properties and cell performance can be easily manipulated through the bioink and the investment casting process to achieve a spatially appropriate osteogenic and chondrogenic response in engineered osteochondral constructs.

The Significance of Osteoarthritis-associated Bone Marrow Lesions in the Knee.

Bone marrow lesions of the knee in patients with osteoarthritis (OA-BML) are an important clinical entity that may explain progressive pain, decreased quality of life, and impaired function. MRI of OA-BMLs demonstrates a region of subchondral bone with hyperintense marrow signal on T2-weighted images. Histopathology retrieval studies have demonstrated that these lesions correlate with microdamage of the trabecular bone, and subsequently, this leads to a vicious cycle of subchondral bone attrition, attempts at repair, pain, and progressive deformity. These lesions have also been linked to accelerated loss of adjacent articular cartilage and increases in the severity of knee pain, prompting patients to seek musculoskeletal care and treatment. Multiple studies have also correlated the presence of an OA-BML with an increased probability of seeking knee arthroplasty. Knowledge of these lesions is important in the context that knee OA is both a cartilage-based and bone-based disease. Further study of OA-BMLs may provide opportunities for early intervention and OA disease-modifying treatments.