Bone Sections Research Articles

Biofilm-Induced Bone Degradation in Osteomyelitis

Objectives: Osteomyelitis, marked by bone inflammation due to microbial infection, presents significant healthcare challenges. While the protective role of biofilm in bacterial immunity and persistence is well-documented, its direct impact on bone degradation in osteomyelitis remains inadequately characterized. This study aims to comprehensively examine the direct effects of biofilm-forming pathogens on human bone, providing new insights into the mechanisms of bone destruction in osteomyelitis. Methods: Bone sections were collected from patients undergoing total knee replacement surgery between January 2021 and December 2022 for this study at Sultan Qaboos University Hospital. Then samples were inoculated with Staphylococcus aureus to simulate in-vitro bone infection. We then used Raman spectroscopy and Scanning Electron Microscopy (SEM) for detailed analysis of the bacterial interaction with bone tissue. Results: SEM images depicted trabecular destruction caused by biofilm. Biofilm-forming pathogens contribute directly to bone exhibited by SEM images with marked trabecular destruction. Raman analysis showed a significant increase in the carbonate-phosphate ratio in inoculated samples (619%) compared to controls (47%). Mineral content decreased in inoculated samples, and the carbonate-to-amide I ratio reduced by 47% in inoculated and 80% in controls. The inoculated samples exhibited an 82% shift in collagen crosslinking compared to 72% in controls. Conclusion: This research enhances our comprehension of the mechanisms behind bone destruction in osteomyelitis and underscores the intricate role of biofilm in the disease's development. These findings highlight the importance of biofilm in bone degradation and its potential implications for managing infections.

Association of keel bone morphometry with keel bone damage and skeletal quality in the laying hen

ABSTRACT 1. The aim of this work was to identify a heritable keel bone phenotype with a correlation to keel bone damage and/or skeletal bone strength that could be easily measured in the living hen to aid selection to prevent welfare issues. 2. The scoring system used reflected the observed damage, keel bone dimensions and shape compared to traditional measurements of bone quality. 3. Increased keel bone damage was associated with poor humerus and tibia breaking strengths (p < 0.01). Bone damage was associated with higher whole keel density (p < 0.01) due to the effect of callus formation. 4. Keel bone depth and area was moderately heritable at indices of 0.32 and 0.40, respectively. Keel bone depth was genetically correlated with tibia (0.36) and humerus density (0.68) and keel bone area was correlated with humerus density (0.59). Deeper keel bones and those with larger areas had small, negative phenotypic correlations with keel bone damage (−0.07 and −0.11, respectively). The second principal component of keel bone shape represented the caudal section of the keel bone and cranial edge concavity. The third principal component represented the differences in the caudal tip of the keel bone, the concavity of the dorsal edge and convexity of the ventral edge. Heritability estimates were 0.44 and 0.39, respectively. 5. The results suggested that genetics contribute to morphometric traits. Hens with poorer skeletal quality are likely to accumulate more damage. Some of the traits may be a predictor of damage, although mid keel depth or concavity may simply reflect the effect of damage or deviation.

In situ metabolomic analysis of osteonecrosis of the femoral head (ONFH) using MALDI MSI.

Osteonecrosis of the femoral head (ONFH) is a common orthopedic disease characterized by disability and deformity. To better understand ONFH at molecular level and to explore the possibility of early diagnosis, instead of diagnosis based on macroscopic spatial characteristics, a matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI MSI) method was developed for ONFH disease for the first time. The most challenging step for ONFH MSI is to deal with human bone tissues which are much harder than the other biological samples studied by the reported MSI studies. In this work, the MSI sectioning method of hard bone tissues was established using tender acids and a series of test criteria. Small-molecule metabolites, such as lipids and amino acids, were detected in bone sections, realizing the in situ detection of spatial distribution of biometabolites.By comparing the distribution of metabolites from different regions of normal femoral head, ONFH bone tissue (ONBT), and adjacent ONFH bone tissue (ANBT), the whole process of femoral head from normal stage to necrosis was monitored and visualized at molecular level. Moreover, this developed MSI method was used for metabolomics study of ONFH. 72 differential metabolites were identified, suggesting that disturbances in energy metabolism and lipid metabolism affected the normal life activities of osteoblasts and osteoclasts. This study provides new perspectives for future pathological studies of ONFH.

Impact of Freeze-dried Corticocancellous Bone Allograft Combined with Enamel Matrix Derivative in the Treatment of Critical-sized Calvarial Bone Defects: An Animal Study.

This study compared the quality and quantity of newly formed bone in rabbits' critical-sized calvarial defects filled with enamel matrix derivative (EMD) combined with freeze-dried bone allograft (FDBA) vs FDBA alone. A total of 24 adult male white New Zealand rabbits were included. In each rabbit, three bone defects with a diameter of 8 mm were created on the calvarium bone; the first defect was left untreated, while the second was filled with FDBA, and the third was filled with EMD + FDBA. Twelve rabbits were randomly euthanized after a month, and the remaining 2 month postsurgery. Bone sections were histologically evaluated by hematoxylin and eosin and vascular endothelial growth factor (VEGF), alkaline phosphatase (ALP), osteoprotegerin (OPG), and receptor activator of NF-kappaB (RANK) immune-histochemical staining. An improvement in the newly formed bone percentage was found in the defects filled with EMD + FDBA in comparison with FDBA and control defects at 1 month and 2 months postsurgery. Additionally, the expression of VEGF, ALP, OPG, and RANK showed highly significant differences in the defects filled with EMD + FDBA compared to the FDBA and control ones at 1 month postsurgery (p = 0.001). Meanwhile, VEGF and ALP expression showed a significant decrease in defects filled with EMD + FDBA compared to the FDBA and control ones (p = 0.001), while OPG and RANK expression showed non-significant differences between treated groups at 2 months postsurgery. Enamel matrix derivative combined with FDBA has a synergistic effect on bone formation and graft substitution. This combination accelerates the expression of VEGF, ALP, OPG, and RANK. The combination of EMD and FDBA accelerates and ameliorates the quality of newly formed bone, aiding in maxillofacial reconstruction. How to cite this article: Zakri RN, Grawish ME, Mowafey B, et al. Impact of Freeze-dried Corticocancellous Bone Allograft Combined with Enamel Matrix Derivative in the Treatment of Critical-sized Calvarial Bone Defects: An Animal Study. J Contemp Dent Pract 2024;25(5):424-431.

A 72-year-old Woman with Dyspnea and Thrombocytosis

&lt;p&gt;原發性血小板增多症的臨床表徵並不典型且早期診斷不易，往往多數病人於診斷前已發生動靜脈血栓形成及出血併發症。本個案一位72歲女性，有高血壓及胃食道逆流病史並按時門診追蹤服藥，五天前注射新冠疫苗後，呼吸喘、乾咳併胸悶至診所就醫未改善，於急診初步診斷急性支氣管炎。入院後感心悸且胸悶，藉由病史詢問、檢驗及理學檢查，顯示心肌酵素正常但心電圖呈現陣發性心室上心搏過速，安排冠狀動脈血管攝影攝影後排除急性心肌梗塞，但呼吸急促未見好轉呈現低血氧，經胸腔電腦斷層為肺栓塞。疑似新冠疫苗後引起的免疫併發症，直到右手食指及中指末梢腫、痛且發紺症狀出現，筆者再次重新檢視病史資料，發現血小板異常，透過骨髓穿刺切片是發現巨核細胞（megakaryocyte）增生，病理報告判斷為骨髓增生性腫瘤，基因檢測結果為JAK2V617F 突變，最後確診是原發性血小板增多症併發肺栓塞，接受Hydroxyurea合併口服抗凝血劑治療，症狀改善且血小板數值趨於穩定。藉此案例分享提醒當發現病人有不明血栓產生時須考慮將相關血液疾病列入鑑別診斷，期能及早發現疾病，掌握治療時機。&lt;/p&gt; &lt;p&gt;&amp;nbsp;&lt;/p&gt;&lt;p&gt;The clinical symptoms of essential thrombocythemia are not typical and early diagnosis is difficult.Most patients have arteriovenous thrombosis and bleeding complications before diagnosis. In this case, a 72-year-old woman had a history of hypertension and gastroesophageal reflux and was taking medication regularly at the outpatient clinic. After being injected with the COVID-19 vaccine five days ago, her breathing, dry cough, and chest tightness did not improve when she went to the clinic. She was initially diagnosed with acute bronchitis in the emergency department. After being admitted to the hospital, she felt palpitations and chest tightness. The medical history, examination and physical examination showed that myocardial enzymes were normal, but the electrocardiogram showed Parox-ysmal supraventricular tachycardia. Coronary angiography was arranged to rule out acute myocardial infarction, but the shortness of breath persisted with hypoxemia, and the computed tomography of the chest showed pulmonary embolism. Immune complications caused by the COVID-19 vaccine were suspected, symptoms of swelling, pain and cyanosis appeared in the distal part of the right index fin-ger and middle finger appeared. The author re-examined the medical history data and found abnormal platelets. Through bone marrow aspiration and sectioning, megakaryocyte hyperplasia was found. Pa-thology report determined that the patient suffered from myeloproliferative neoplasm, and the genetic test result was the JAK2V617F mutation. The patient was finally diagnosed with essential thrombocythe-mia complicated by pulmonary embolism. She was treated with Hydroxyurea combined with oral an-ticoagulants. The symptoms improved and the platelet level stabilized. This case serves as a reminder that when a patient is found to have unknown thrombosis, related blood diseases must be considered in the differential diagnosis, so that the disease can be detected early and proper treatments can be pro-vided.&lt;/p&gt; &lt;p&gt;&amp;nbsp;&lt;/p&gt;

Retrospective isotope analysis of ancient remains to distinguish between tamed and wild animals

The origin and process of the domestication of wild animals have long fascinated scientists. However, there are no reliable methods to distinguish between tamed and wild animals. Here, we present a new method to identify tamed and wild juvenile brown bears (Ursus arctos) using retrospective isotope analysis of the femur. We used femurs from the nine bear cubs and the tibia from one domesticated dog excavated from the Nijibetsu Shuwan Kumaokuriba site, Hokkaido Islands, Japan (late 19th century–1939 AD). These bears were potentially tamed by indigenous Ainu people, and the domesticated dog was used as a reference of a tamed animal. We subdivided these bones into 10 sections along the growing axis, extracted collagen and measured the stable nitrogen isotope ratios (δ15N). The bone sections of the domesticated dog had constant δ15N values that were as high as that of salmon, suggesting that tamed animals exclusively consumed a marine diet fed to them by the Ainu. Notably, two of nine brown bear cubs showed a temporal elevation of δ15N to the similar isotope ratios of the dog tibia, which is unlikely to occur in the wild condition, strongly suggesting that they were tamed and fed by the Ainu people.

MANAGEMENT OF AVASCULAR NECROSIS THROUGH PANCHTIKTA KSHEER BASTI: PILOT STUDY

Avascular necrosis is the death of bone tissue due to a lack of blood supply. Also called osteonecrosis, it can lead to tiny breaks in the bone and cause the bone to collapse. The process usually takes months to years. A broken bone or dislocated joint can stop the blood flow to a section of bone.

EPSTI1 promotes osteoclast differentiation and bone resorption by PKR/NF-κB signaling

BackgroundEpithelial stromal interaction 1 (EPSTI1) plays an important role in M1 macrophages, which induce osteoclastogenesis. One recent genome-wide association study (GWAS) involving 426,824 individuals has shown that EPSTI1 is strongly associated with osteoporosis (P < 5E-8). Therefore, we speculate that EPSTI1 participates in the modulation of osteoporosis through osteoclastogenesis. The roles of EPSTI1 in osteoclastogenesis and bone resorption remain unclear. MethodsFemur specimens were collected from osteoporotic patients and control patients. Immunofluorescence staining was used to detect the expression of EPSTI1 and signaling pathways. The osteoclastic potential of RAW264.7 cells with Sh-EPSTI1 lentivirus infection was tested using tartrate-resistant acid phosphatase (TRAP) staining, western blotting, and quantitative reverse transcription polymerase chain reaction (qRT-PCR). Western blotting was also used to examine signaling pathways. ResultsIn this study, EPSTI1 was found to be significantly increased in tartrate-resistant acid phosphatase positive (ACP5+) osteoclasts of bone sections from osteoporotic patients. Next, we identified EPSTI1 as a positive regulator of osteoclastogenesis and osteoclast differentiation capability. Diminished EPSTI1 expression resulted in reduced osteoclastic resorption. Mechanistically, EPSTI1-driven osteoclastogenesis was regulated by NF-κB pathway, which was mediated by the phosphorylation of protein kinase R (p-PKR). Furthermore, EPSTI1 participating in the modulation of osteoporosis via PKR/NF-κB pathway was also verified in the bone samples of osteoporotic patients. ConclusionsCollectively, our findings suggest that EPSTI1 may regulate osteoclast differentiation and bone resorption through PKR/NF-κB pathway and in vivo experiments are needed to further verify EPSTI1 as the therapy target for osteoporosis.

A Comparative Analysis on the Histomorphometric Pattern of Various Segments of Adult Male Long Bones: Forensic Implication

Abstract Background: Human bone analysis is a useful tool in assessing and identifying skeletal remains. To make this easier, newer and modified approaches have often being documented. Aims and Objectives: The aim of this study is to analyze the histomorphometric features of various bone segments and its relevance in forensic case diagnosis. Materials and Methods: The human bones used were that of cadaveric bone samples harvested from three adult male Nigerians. The proximal, midshaft and distal segments of the femur, tibia, and humerus were utilized for the study. The bone sections were subjected to processing using Frost’s rapid manual preparation of ground sections techniques. Histomorphometric evaluation studied the number of primary osteons, secondary osteons, and osteon fragments, as well as the Haversian canal diameter (HCD). Results: The primary osteons, secondary osteons, osteon fragments, and HCD in each of the segments of the long bones show that the F values are less than the F critical for an alpha level of 0.05. This shows that there is no statistically significant (P &gt; 0.05) variation in the histomorphometric pattern for the various segments of the bones studied. Again differences in the haversian canal diameter of the various segments of the long bones shows statistically significant variation (P&lt; 0.05) among the long bones investigated. Conclusion: These findings have laid to rest the challenges with using the only available bone fragment for forensic case investigation as no notable variations exist across various segments.

Poly(Ethylene Glycols) to Facilitate Celloidin Removal for Immunohistochemical Studies on Archival Human Brain and Temporal Bone Sections.

Pathology repositories worldwide store millions of celloidin-processed human brain and temporal bone (TB) sections vital for studying central nervous system diseases and sensory organs. However, accessing these sections for modern molecular-pathological research, like immunohistochemistry, is hindered by the challenge of removing celloidin without damaging tissue. In this study, we explored the use of polyethylene glycols (PEGs), a class of non-hazardous, ethylene glycol oligomers, combined with an improved section mounting technique, to gently and effectively dissolve celloidin from sections archived for up to 40 years. Optimizing our protocol involved exploring celloidin dissolution kinetics in PEGs of varying molecular weights and terminations, as well as different temperatures. Low molecular weight PEGs, particularly PEG 200, were the most efficient celloidin solvent. Nuclear magnetic resonance (NMR) spectroscopy of celloidin-PEG 200 dissolution products revealed no chemical alterations, suggesting pure solvation without chemical modification. Because the solvation of celloidin in PEG was inhibited by proteins, we further developed a protein-free mounting protocol allowing complete celloidin removal in 30 to 60 minutes by immersing in PEG 200. In summary, our approach overcomes major methodological hurdles, rendering decades-old archival celloidin sections viable for immunohistochemical and other molecular biological techniques, while enhancing safety and workflow efficiency.

Assessing the Efficacy of Tragal Pumping in a Novel Tympanostomy Tube-Rat Model.

Tragal pumping (TP) is a practice of pushing on the tragus to raise pressure within the external auditory canal and is a commonly recommended adjunctive maneuver believed to facilitate the introduction of ototopical medications into the middle ear cavity via a tympanostomy tube. To investigate the efficacy of TP in the penetration of eardrops into the middle ear cavity via tympanostomy tube, we established the novel tympanostomy tube-rat model. We investigated the histology of the middle ear to determine the efficacy in moving fluid into the middle ear. Prospective controlled animal study. Animal laboratory in a university hospital. Ten rats were recruited, and a tympanostomy tube insertion and green dye eardrops into outer ears were performed on bilateral ears. TP was performed only on 1 ear and was not applied on the other ear in each rat. Green dye in a middle ear cavity in hematoxylin and eosin-stained temporal bone sections was evaluated by blinded experts in microscopic anatomy (staining grade) and by using Image J software (staining level). The results of these 2 methods were statistically validated. The staining grade (P < .001) and the staining level (P < .001) were significantly higher in the ears which we applied TP than in the control ears. The results of 2 methods were significantly and positively correlated (r = .898, P < .001). Our results showed that the TP accelerate the penetration of eardrops into the middle ear cavity in the tympanostomy tube-rat model.

Bone of contention: Intra-element variability in remodelling of human femora based on histomorphometric and isotope analyses.

The volume of human carbon (δ13C) and nitrogen (δ15N) isotope data produced in archaeological research has increased markedly in recent years. However, knowledge of bone remodelling, its impact on isotope variation, and the temporal resolution of isotope data remains poorly understood. Varied remodelling rates mean different elements (e.g., femur and rib) produce different temporal signals but little research has examined intra-element variability. This study investigates human bone remodelling using osteon population density and the relationship with carbon and nitrogen isotope data at a high resolution, focusing on variation through femoral cross-sections, from periosteal to endosteal surfaces. Results demonstrate considerable differences in isotope values between cross-sectional segments of a single fragment, by up to 1.3‰ for carbon and 1.8‰ for nitrogen, illustrating the need for standardised sampling strategies. Remodelling also varies between bone sections, occurring predominantly within the endosteal portion, followed by the midcortical and periosteal. Therefore, the endosteal portion likely reflects a shorter period of life closer to the time of death, consistent with expectations. By contrast, the periosteal surface provides a longer average, though there were exceptions to this. Results revealed a weak negative correlation between osteon population density and δ15N or δ13C, confirming that remodelling has an effect on isotope values but is not the principal driver. However, a consistent elevation of δ15N and δ13C (0.5‰ average) was found between the endosteal and periosteal regions, which requires further investigation. These findings suggest that, with further research, there is potential for single bone fragments to reconstruct in-life dietary change and mobility, thus reducing destructive sampling.

Osteostaticytes: A novel osteoclast subset couples bone resorption and bone formation

BackgroundOsteomyelitis (OM) is an inflammatory condition of bone characterized by cortical bone devascularization and necrosis. Dysregulation of bone remodelling is triggered by OM. Bone remodelling is precisely coordinated by bone resorption and formation via a reversal phase. However, the cellular and molecular mechanisms underlying bone remodelling failure after osteomyelitis remain elusive. MethodsTo elucidate the cellular and molecular mechanism underlying bone healing after osteomyelitis, we employed single-cell RNA sequencing (scRNA-seq) to depict the atlas of human cortical bone in normal, infected and reconstructed states. Dimensionality reduction by t-stochastic neighbourhood embedding (t-SNE) and graph-based clustering were applied to analyse the detailed clusters of osteoclast lineages. After trajectory analysis of osteoclast lineages over pseudotime, real-time PCR and immunofluorescence (IF) staining were applied to identify marker gene expression of various osteoclast lineages in the osteoclast induction model and human bone sections, respectively. The potential function and communication of osteoclasts were analysed via gene set enrichment analysis (GSEA) and CellChat. The chemotactic ability of mesenchymal stem cells (MSCs) and osteoclast lineage cells in various differentiation states was determined by transwell assays and coculture assays. The effects of various osteoclast lineages on the osteogenic differentiation potential of MSCs were also determined by using this coculture system. A normal mouse tibia fracture model and an osteomyelitis-related tibia fracture model were generated via injection of luciferase-labelled Staphylococcus aureus to verify the relationships between a novel osteoclast lineage and MSCs. Then, the infection was detected by a bioluminescence imaging system. Finally, immunofluorescence staining was used to detect the expression of markers of MSCs and novel osteoclast lineages in different remodelling phases in normal and infected bone remodelling models. ResultsIn this study, we constructed a cell atlas encompassing normal, infected, and reconstructed cortical bone. Then, we identified a novel subset at the earlier stage of the osteoclast lineage that exhibited increased expression of IDO1, CCL3, and CCL4. These IDO1highCCL3highCCL4high cells, termed osteostaticytes (OSCs), were further regarded as the reservoir of osteoclasts in the reversal phase. Notably, OSCs exhibited the highest chemotactic activity, surpassing other lineage subsets. We also discovered that cells at the earlier stage of the osteoclast lineage play a significant role in recruiting mesenchymal stem cells (MSCs). Finally, the data revealed that OSCs might be positively related to the occurrence of bone MSCs and the contribution of bone remodelling. ConclusionCollectively, our findings revealed a novel stage (OSC) within the osteoclast lineage, potentially representing elusive bone reversal cells due to its increased chemotactic ability towards MSCs and potential contribution to bone remodelling. This study provides valuable insights into the intricate mechanisms of the reversal phase during bone remodelling and unveils potential therapeutic strategies for diseases associated with bone uncoupling. Translational potential of this articleThis study identified a new subset, referred to as IDO1(plus symbol) CCL3(plus symbol) CCL4(plus symbol) osteostaticytes which displayed the highest chemotactic activity among all osteoclast lineages and may serve as reversal cells in bone remodelling. These findings offer new insights and insights for understanding bone reversal-related diseases and may serve as novel therapeutic targets for conditions such as osteomyelitis and delayed bone healing.

Optimization of Formic Acid-Formalin-Based Decalcification Protocol for Rat Calvarial Bone Histology

Decalcification is crucial in histological processing, particularly for studying mineralized tissues like bone. The choice of decalcification method can significantly impact the quality of histological sections and the preservation of tissue morphology. This study aims to establish a standardized protocol for decalcifying rat calvarial bone using a formic acid-formalin-based decalcification solution. The protocol was systematically optimized and evaluated based on various parameters, including decalcification time, formic acid concentration, and tissue integrity preservation. The decalcification process was evaluated through comprehensive assessments, including gross physical examination, chemical analysis, and radiographic imaging techniques. Our result demonstrated that the 10% formic acid concentration proved most effective for decalcifying rat calvarial bone samples within eight days, excelling in mineral content removal while preserving specimen structural integrity. In contrast, the 5% concentration failed to complete decalcification within ten days, and the 15% compromised sample quality within eight days. Histological analyses confirmed the efficacy of the 10% formic acid concentration in maintaining tissue integrity and achieving optimal staining quality. The standardized protocol presented in this study provides an effective and reliable approach for achieving consistent and high-quality histological sections of rat calvarial bone. An ideal decalcification agent should effectively remove calcium salts, preserve structural integrity and molecular components, facilitate rapid yet minimally damaging decalcification, and ensure ease of handling for laboratory personnel. Further exploration of its applicability to different bone types or species is recommended to broaden its research utility.

Biomechanical analysis of plate versus K-wire fixation for metacarpal shaft fractures with wedge-shaped bone defects

BackgroundMetacarpal shaft fracture is a common type of hand fracture. Numerous studies have explored fixing transverse fractures in the midshaft of the metacarpal bone. However, this section of the metacarpal bone is often susceptible to high-energy injury, resulting in comminuted fracture or bone loss. In such cases, wedge-shaped bone defects can develop in the metacarpal shaft, increasing the difficulty of performing fracture fixation. Notably, the research on this type of fracture fixation is limited. This study compared the abilities of four fixation methods to fix metacarpal shaft fractures with wedge-shaped bone defects.MethodsIn total, 28 artificial metacarpal bones were used. To create wedge-shaped bone defects, an electric saw was used to create metacarpal shaft fractures at the midshaft of each bone. The artificial metacarpal bones were then divided into four groups for fixation. The bones in the first group were fixed with a dorsal locked plate (DP group), those in the second group were fixed with a volar locked plate (VP group), and those in the third group were fixed by combining dorsal and volar locked plates (DP + VP group), and those in the fourth group were fixed with two K-wires (2 K group). Cantilever bending tests were conducted using a material testing machine to measure yielding force and stiffness. The four groups’ fixation capabilities were then assessed through analysis of variance and Tukey’s test.ResultsThe DP + VP group (164.1±44.0 N) achieved a significantly higher yielding force relative to the 2 K group (50.7 ± 8.9 N); the DP group (13.6 ± 3.0 N) and VP group (12.3 ± 1.0 N) did not differ significantly in terms of yielding force, with both achieving lower yielding forces relative to the DP + VP group and 2 K group. The DP + VP group (19.8±6.3 N/mm) achieved the highest level of stiffness, and the other three groups did not differ significantly in terms of stiffness (2 K group, 5.4 ± 1.1 N/mm; DP group, 4.0 ± 0.9 N/mm; VP group, 3.9 ± 1.9 N/mm).ConclusionsThe fixation method involving the combined use of dorsal and volar locked plates (DP + VP group) resulted in optimal outcomes with respect to fixing metacarpal shaft fractures with volar wedge bone defects.

Radiation attenuation characterization of some biological samples by using the Klein–Nishina formula

Radiation has beneficial applications in medicine and nuclear sciences, but it can also be harmful due to its ionizing properties. So, radiation usage has a significant role in different research fields. In the present study, the Klein–Nishina (K–N) approach was used to evaluate the electronic and energy-transfer cross sections of Water, bone, adipose, soft, long, breast, brain and skin tissues. Compton mass attenuation coefficients (CMAC) and Compton mass energy transfer coefficients (CMACtr) were determined in the energy range 0.284–15 MeV. Different methods, based on the effective charge, were used to determine the parameters of the materials for the energy range. The cross sections were firstly calculated for elements that made up the materials. The investigated parameters of the materials were then determined using the relevant cross sections in the energy range. The results were compared with each other and some possible results from the literature. Klein–Nishina electronic cross sections, Compton mass attenuation coefficients and Compton mass energy transfer coefficients of the studied materials were decreased with increasing γ-ray energy like the elements. A good agreement was observed for CMACs and CMACtrs based on Zeff1/A and Zeff3/A (Diff. ≤ 16.4%) for Bone Compact. In addition, a comparison with the literature was done for CaCO3 in CMAC for some photon energies. The maximum difference (%) between used methods and literature was observed as ≤ 19.0%. The reported data should be useful using the gamma rays in Compton scattering energy region.

Validation of compositional MRI from a histological standpoint: Advantages of three-dimensional T1ρ mapping for quantitative evaluation of articular cartilage

PurposeWe aimed to investigate the relationship between quantitative evaluation by compositional MRI, including T1ρ, and histological and macroscopic assessments, to verify the validity of compositional MRI, and examine the relationship between compositional MRI evaluation reconstructed in three dimensions (3D) and histological and visual assessments. MethodTwenty-seven patients with knee osteoarthritis underwent T1ρ and T2 magnetic resonance imaging (MRI). Histological and gross tissue evaluations were performed on the excised bone sections of total knee arthroplasty. Semi-quantitative histological evaluation of tissue changes were assessed by measuring the optical density of digitally captured safranin O-stained and Collagen type II antibody-stained paraffin sections. Macroscopic cartilage severity was determined on a 5-grade scale (G0–G5). T1ρ and T2 values (3D and 2D), and their correlation with each of these parameters were investigated. Results3D T1 ρ is negatively correlated with histological evaluations and positively correlated with visual assessments. Only 3D T1ρ values correlated with histological quantitative evaluation (Safranin-O staining; r = −0.53, P = 0.014, Collagen type II antibody staining; r = −0.60, P = 0.019). 2D T1ρ and 3D, 2D T2 values did not correlate with histological evaluation results. Macroscopic cartilage severity grade correlated with all T1ρ and T2 values (3D T1ρ; r = 0.61, P < 0.001, 2D T1ρ; r = 0.52, P < 0.001, 3D T2; r = 0.33, P = 0.045, 2D T2; r = 0.41, P = 0.01). Conclusions3D T1ρ mapping reflects the changes in the molecular structure of the cartilage matrix that occur in arthropathic changes and may be an effective tool for detecting cartilage degeneration.

Young osteocyte-derived extracellular vesicles facilitate osteogenesis by transferring tropomyosin-1

BackgroundBone marrow mesenchymal stem cells (BMSCs) can undergo inadequate osteogenesis or excessive adipogenesis as they age due to changes in the bone microenvironment, ultimately resulting in decreased bone density and elevated risk of fractures in senile osteoporosis. This study aims to investigate the effects of osteocyte senescence on the bone microenvironment and its influence on BMSCs during aging.ResultsPrimary osteocytes were isolated from 2-month-old and 16-month-old mice to obtain young osteocyte-derived extracellular vesicles (YO-EVs) and senescent osteocyte-derived EVs (SO-EVs), respectively. YO-EVs were found to significantly increase alkaline phosphatase activity, mineralization deposition, and the expression of osteogenesis-related genes in BMSCs, while SO-EVs promoted BMSC adipogenesis. Neither YO-EVs nor SO-EVs exerted an effect on the osteoclastogenesis of primary macrophages/monocytes. Our constructed transgenic mice, designed to trace osteocyte-derived EV distribution, revealed abundant osteocyte-derived EVs embedded in the bone matrix. Moreover, mature osteoclasts were found to release osteocyte-derived EVs from bone slices, playing a pivotal role in regulating the functions of the surrounding culture medium. Following intravenous injection into young and elderly mouse models, YO-EVs demonstrated a significant enhancement of bone mass and biomechanical strength compared to SO-EVs. Immunostaining of bone sections revealed that YO-EV treatment augmented the number of osteoblasts on the bone surface, while SO-EV treatment promoted adipocyte formation in the bone marrow. Proteomics analysis of YO-EVs and SO-EVs showed that tropomyosin-1 (TPM1) was enriched in YO-EVs, which increased the matrix stiffness of BMSCs, consequently promoting osteogenesis. Specifically, the siRNA-mediated depletion of Tpm1 eliminated pro-osteogenic activity of YO-EVs both in vitro and in vivo.ConclusionsOur findings suggested that YO-EVs played a crucial role in maintaining the balance between bone resorption and formation, and their pro-osteogenic activity declining with aging. Therefore, YO-EVs and the delivered TPM1 hold potential as therapeutic targets for senile osteoporosis.Graphical abstract

Space invaders: Reassessing the histology of hyperostosis frontalis interna.

Hyperostosis frontalis interna (HFI) is a human skeletal lesion characterized by nodules of hyperplastic bone and thickening of the frontal bone's inner surface. Despite its prevalence in the general population and its long history of observation-it is one of the most frequently observed pathologies in gross anatomy laboratories-HFI's etiology and pathogenesis remain poorly understood. This is largely due to the lack of a thorough survey of its histology across the various stages of its development. Our study has three major aims: (1) assess HFI histology from incipient to advanced lesions; (2) elucidate lamellar and trabecular structure in HFI; and (3) clarify impacts/roles of the dura mater in HFI. Sections of nondecalcified bone provide evidence for two different categories of lesions: (1) stratum lesions, characterized by lamellar-based overall thickening of the internal table, and (2) eruptive lesions, characterized by nodular formations of initially lamellar bone that appear to form the bulk of bone mass in advanced stages. Sections of nondecalcified bone also suggest that for both lesion types, HFI growths begin as deposits of lamellar bone, which are later remodeled into woven bone deposits; our data do not support the hypothesis that lesions begin as a "diploization" of cortical bone as suggested by prior studies. Trichrome-stained sections provide evidence that growing lesions erode through and engulf the dura mater, effectively destroying this tissue layer as they grow laterally and inwardly. Our results indicate possible avenues of research to better understand the root causes of this disorder.

Homogenized finite element analysis of distal tibia sections: Achievements and limitations

High-resolution peripheral quantitative computed tomography (HR-pQCT) based micro-finite element (μFE) analysis allows accurate prediction of stiffness and ultimate load of standardised (∼1 cm) distal radius and tibia sections. An alternative homogenized finite element method (hFE) was recently validated to compute the ultimate load of larger (∼2 cm) distal radius sections that include Colles' fracture sites. Since the mechanical integrity of the weight-bearing distal tibia is gaining clinical interest, it has been shown that the same properties can be used to predict the strength of both distal segments of the radius and the tibia. Despite the capacity of hFE to predict structural properties of distal segments of the radius and the tibia, the limitations of such homogenization scheme remain unclear. Therefore, the objective of this study is to build a complete mechanical data set of the compressive behavior of distal segments of the tibia and to compare quantitatively the structural properties with the hFE predictions. As a further aim, it is intended to verify whether hFE is also able to capture the post-yield strain localisation or fracture zones in such a bone section, despite the absence of strain softening in the constitutive model.Twenty-five fresh-frozen distal parts of tibias of human donors were used in this study. Sections were cut corresponding to an in-house triple-stack protocol HR-pQCT scan, lapped, and scanned using micro computed tomography (μCT). The sections were tested in compression until failure, unloaded and scanned again in μCT. Volumetric bone mineral density (vBMD) and bone mineral content (BMC) were correlated to compression test results. hFE analysis was performed in order to compare computational predictions (stiffness, yield load and plastic deformation field pattern) with the compressive experiment. Namely, strain localization was assessed based on digital volume correlation (DVC) results and qualitatively compared to hFE predictions by comparing mid-slices patterns.Bone mineral content (BMC) showed a good correlation with stiffness (R2 = 0.92) and yield (R2 = 0.88). Structural parameters also showed good agreement between the experiment and hFE for both stiffness (R2 = 0.96, slope = 1.05 with 95 % CI [0.97, 1.14]) and yield (R2 = 0.95, slope = 1.04 [0.94, 1.13]). The qualitative comparison between hFE and DVC strain localization patterns allowed the classification of the samples into 3 categories: bad (15 sections), semi (8), and good agreement (2).The good correlations between BMC or hFE and experiment for structural parameters were similar to those obtained previously for the distal part of the radius. The failure zones determined by hFE corresponded to registration only in 8 % of the cases. We attribute these discrepancies to local elastic/plastic buckling effects that are not captured by the continuum-based FE approach exempt from strain softening. A way to improve strain localization hFE prediction would be to use longer distal segments with intact cortical shells, as done for the radius. To conclude, the used hFE scheme captures the elastic and yield response of the tibia sections reliably but not the subsequent failure process.