Joint Region Research Articles

Experimental study on exterior precast concrete beam-to-CECFST column joints with wet connections under cyclic loading

Concrete-encased concrete-filled steel tube (CECFST) structural system has gained popularity in recent years due to its several advantages over conventional structures. Additionally, precast technology has become an effective way of improving construction efficiency and environmental performance. Therefore, it is essential to investigate the structural behaviour of precast concrete (PC) beam-to-CECFST column joints to ensure their optimal performance in applications. In this regard, this paper presents an experimental study of 4 precast exterior joints subjected to lateral cyclic loading. The study investigated the effect of replacing normal concrete with steel fibre-reinforced concrete at the joint region and the presence of axial load on PC composite joints. Based on the test results, cyclic load-carrying resistance, failure modes and crack patterns of the PC specimens were recorded and analysed. In addition, a Digital Image Correlation (DIC) system was adopted to show the crack evolution of joint specimens and calculate shear strains of concrete encasement at the joint region. Further comparisons were conducted in terms of ductility, energy dissipation, stiffness and strength degradation to investigate the joint performance. Finally, existing American and European design code provisions were modified and used to predict joint shear strength. Their predictions were reasonably close to the test results.

Investigation on effect of ECC coverage condition on seismic behavior of beam-column joint

There is a renewed interest around the world to do fundamental research on novel materials to enhance the overall response of structures under seismic loading. Engineered cementitious composite (ECC) is a special class of concrete with good ductility, which is widely adopted in engineering structures. In this paper, the seismic behavior of beam-column joints incorporated with ECC materials is numerically and experimentally investigated. A database containing available related test results in literature is collected and analyzed to investigate the relations between ECC coverage area and failure characteristics. An interior and an exterior beam-column joint with ECC adopted in the joint region are prepared and tested in this study. The effect of ECC coverage area on the overall joint seismic response is analyzed through a validated finite element model. A modified strength hierarchy analysis is proposed and conducted to consider the application of ECC on the joint. Based on the analytical investigation, the weakest structural element in the joint region is found. The strength hierarchy analysis results have a good correlation with the experimental failure pattern, which shows a potential application as a preliminary analysis to evaluate ECC joint failure mechanisms under seismic loading.

Computed Tomographic Evaluation of the Sagittal Ridge of the Third Metacarpal Bone in Young Thoroughbred Racehorses: A Longitudinal Study.

Metacarpophalangeal joint region pain is a common cause of lameness in racehorses. Radiological abnormalities in the sagittal ridge (SR) of the third metacarpal bone have been associated with joint effusion, lameness and reduced sales prices. The aims were to describe computed tomographic (CT) appearance of the SR in racehorses, and to document the progression of these findings over three assessments. Forty yearlings were enrolled at the first examination (time 0). Re-examinations were performed twice, approximately six months apart on 31 (time 1) and 23 (time 2) horses, respectively. Computed tomographic examinations of both metacarpophalangeal regions were performed with the horses in a standing position. Computed tomographic reconstructions were analysed subjectively and objectively. The mean Hounsfield Unit values (Hus) of eight radial segments and location, size and shape of hypoattenuating lesions were recorded. Mean Hus at time 1 were higher than at time 0. There was no difference between mean HU at times 1 and 2. The mean HU values of the dorsal half were higher in the right forelimbs and in fillies. Hypoattenuation was identified in 33/80 (41.3%) limbs at time 0, in 22/62 (35.5%) limbs at time 1 and in 14/46 (30.4%) limbs at time 2. All hypoattenuations were located in the dorsodistal aspect of the SR. The most common shapes were hypoattenuating lesions elongated proximodistally and those extending towards trabecular bone. An increase in attenuation of the SR occurred in the first six months of training. Hypoattenuating lesions could decrease in size and could resolve during early training. In this population, these lesions were not associated with lameness.

Cyclic behaviour of precast beam-column connections with shear key and hybrid rebar coupler: An experimental study

The current work attempts to examine the cyclic behaviour of the proposed shear key based precast beam-column wet connections. The configurations consist of shear keys, fiber reinforced composites and interface treatment between beam & column. The rebar continuity between the precast beam and column was established using hybrid rebar couplers. Six precast specimens and one monolithic joint were cast and tested under reversed cyclic loading. The seismic performance of the connections was assessed and discussed in terms of hysteretic behaviour, stiffness and strength degradation, damage tolerance, displacement ductility, energy dissipation characteristics, and joint principal tensile stresses. The strength enhancement, dissipated energy, stiffness retention of precast specimens was similar to monolithic specimen. The crack patterns revealed the influence of stiffness of coupler in the plastic hinge region with shifting of cracks next to coupler and joint region. Also, the presence of fiber reinforced composites, shear key and interface treatment in the connection region exhibited controlled cracking in the plastic hinge region and restricted the joint shear failure. The obtained results were validated through ACI 374.1–05 requirements criteria, which shows the acceptable seismic behaviour. The findings obtained from this study demonstrated the integrity of proposed beam-column connections against seismic forces and could achieve emulative design philosophy.

Evaluating structural strength and vibrational characteristics of silicon carbide incorporated adhesively bonded single lap joints

The adhesive bonding approach is widely used in assembling of spars, stringers, ailerons, flaps, and rudders in aircraft. The present research investigated the impact of silicon carbide (SiC) nanoparticle inclusion on the shear and free vibrational behaviour of adhesively bonded single lap joints (SLJ). The shear test results showed that the inclusion of 1.5 wt.% SiC in the epoxy resin enhanced the shear behaviour of adhesively bonded SLJ. Furthermore, the failure surfaces of adhesively bonded SiC-reinforced SLJ were examined using a field emission scanning electron microscope (FESEM). The microstructural investigation of the failure surface demonstrated that the development of rougher surfaces, plastic void enlargement, and formation of shear bands in the joint region had improved adhesion among GFRP adherends. Thus, the SiC-incorporated adhesively bonded SLJ had predominant cohesive failures. Meanwhile, the SiC-free lap joint had an adhesive failure due to lower adhesion. The vibrational results avowed that 1.5 wt.% SiC-incorporated adhesively bonded SLJ has higher natural frequencies. Results also affirmed that higher wt.% SiC-incorporated joint had better modal damping values due to nanoparticle accumulation, which increased the interaction between glass fiber reinforced polymer (GFRP) adherends.

Mechano Growth Factor E Peptide Improves Degenerative Meniscus by Promoting the Proliferation and Migration of Meniscus Cells

This study aimed to examine the effect of the Mechano growth factor E peptide on meniscus repair, which is critical for restoring knee joint function. Meniscal cells harvested from the inner and outer regions of knee joints from patients with osteoarthritis were subjected to Mechano growth factor E peptide treatment to investigate alterations in cell morphology and their effect on cell colony formation. The effect of Mechano growth factor E peptide treatment on cell migration was evaluated using a transwell system, while polymerase chain reaction was utilized to assess the effect of Mechano growth factor E peptide treatment on the mRNA expression level of COL1A1 or COL2A1, which encode for key collagen types. The reparative effect of the Mechano growth factor E peptide on the meniscus was evaluated using a rabbit meniscal defect model and complemented with hematoxylin and eosin staining. We found that Mechano growth factor E peptide administration augments meniscal cell proliferation, migration, and collagen synthesis, thereby enhancing in vivo meniscus repair. This study examined the capacity of the Mechano growth factor E peptide to ameliorate meniscal injury by promoting meniscal cell proliferation and migration.

Association Between Temporomandibular Joint Disorders and Metastatic Breast Cancer—A Mapping Review

Aim: The authors of the present study speculate that metastasis of breast cancer cells to the temporomandibular joint (TMJ) region mimics classical signs and symptoms of temporomandibular disorders (TMD). The aim of this mapping review was to investigate the association between metastatic breast cancer (MBC) and TMD. Materials and Methods: The focused question was, “Is there an association between MBC and TMD?” Indexed databases (PubMed/Medline, EMBASE, OVID, Scopus, Google Scholar, and Web of Science) were electronically searched up to and including March 2022. These databases were searched using different combinations of the following keywords: cancer, carcinoma, temporomandibular disorders, temporomandibular joint, disc displacement disorder, nociception, and tumor. Original clinical studies that meet the inclusion criteria were included. The risk of bias (RoB) was assessed using the Joanna Briggs Institute Critical Appraisal Checklist for case reports. The structure of this current evidence-based review was tailored to primarily condense the relevant information. Results: Fifteen case reports were selected after screening the retrieved records from the electronic search. Fifteen out of 16 patients were women aged between 32 and 78 years. All patients were diagnosed with MBC, and most presented with adenocarcinoma. The symptoms identified in patients with TMD included: (a) preauricular pain; (b) preauricular swelling; (c) limited mouth opening; and (d) malocclusion. Fourteen of the included studies had a low RoB, while one had a moderate RoB. Conclusion: Based on the currently available evidence, a direct association between TMD and MBC or vice versa cannot be established. Routine visits to medical and oro-dental healthcare providers can contribute toward early diagnosis and management of TMD and MBC.

Using ultrasound shear wave elastography to characterize peripheral nerve mechanics: a systematic review on the normative reference values in healthy individuals.

Ultrasound shear wave elastography (SWE) is an emerging non-invasive imaging technique for peripheral nerve evaluation. Shear wave velocity (SWV), a surrogate measure of stiffness, holds promise as a biomarker for various peripheral nerve disorders. However, to maximize its clinical and biomechanical value, it is important to fully understand the factors that influence nerve SWV measurements. This systematic review aimed to identify the normal range of SWV for healthy sciatic and tibial nerves and to reveal the factors potentially affecting nerve SWV. An electronic search yielded 17 studies eligible for inclusion, involving 548 healthy individuals (age range, 17 to 72 years). Despite very good reliability metrics, the reported SWV values differed considerably across studies for the sciatic (1.9-9.9 m/s) and tibial (2.3-9.1 m/s) nerves. Factors such as measurement proximity to joint regions, limb postures inducing nerve axial stretching, and transducer alignment with nerve fiber orientation were associated with increased SWV. These findings suggest regional-specific nerve mechanical properties, non-linear elastic behaviour, and marked mechanical anisotropy. The impact of age and sex remains unclear and warrants further investigation. These results emphasize the importance of considering these factors when assessing and interpreting nerve SWE. While increased SWV has been linked to pathological changes affecting nerve tissue mechanics, the significant variability observed in healthy nerves highlights the need for standardized SWE assessment protocols. Developing guidelines for enhanced clinical utility and achieving a comprehensive understanding of the factors that influence nerve SWE assessments are critical in advancing the field.

Metabolomic profiles of cartilage and bone reflect tissue type, radiography-confirmed osteoarthritis, and spatial location within the joint

Osteoarthritis is the most common chronic joint disease, characterized by the abnormal remodeling of joint tissues including articular cartilage and subchondral bone. However, there are currently no therapeutic drug targets to slow the progression of disease because disease pathogenesis is largely unknown. Thus, the goals of this study were to identify metabolic differences between articular cartilage and subchondral bone, compare the metabolic shifts in osteoarthritic grade III and IV tissues, and spatially map metabolic shifts across regions of osteoarthritic hip joints. Articular cartilage and subchondral bone from 9 human femoral heads were obtained after total joint arthroplasty, homogenized and metabolites were extracted for liquid chromatography-mass spectrometry analysis. Metabolomic profiling revealed that distinct metabolic endotypes exist between osteoarthritic tissues, late-stage grades, and regions of the diseased joint. The pathways that contributed the most to these differences between tissues were associated with lipid and amino acid metabolism. Differences between grades were associated with nucleotide, lipid, and sugar metabolism. Specific metabolic pathways such as glycosaminoglycan degradation and amino acid metabolism, were spatially constrained to more superior regions of the femoral head. These results suggest that radiography-confirmed grades III and IV osteoarthritis are associated with distinct global metabolic and that metabolic shifts are not uniform across the joint. The results of this study enhance our understanding of osteoarthritis pathogenesis and may lead to potential drug targets to slow, halt, or reverse tissue damage in late stages of osteoarthritis.

Numerical Analysis of Hybrid Fibre-Reinforced Concrete Beam-Column Joint

Beam-column joint is the most vulnerable location of a moment-resisting reinforced concrete frame structure. The joint region experiences the maximum shear stress both in vertically and horizontally which is generated due to the shear transfer mechanism from the adjoining beams and columns. The shear capacity and bond stress capacity are the two major factors affecting the strength of a joint core in RC structure. An important discovery recently is the ductile behaviour of the whole structure under repeated loading. The behaviour of the concrete beyond elastic limit which is in the concrete hardening zone can drastically influence the ductility of the concrete. The non-linear stress-strain behaviour after the onset of the initial crack and up to ultimate compressive strength plays an important role in improving ductility. Beyond the ultimate compressive strength, concrete will undergo softening which is neglected in this study as once concrete reaches ultimate stress it is unsafe for service. This material ductility can be fulfilled with the application of high-strength fibres with ductile behaviour. However, the hybridization of two or more fibres can incorporate two different characteristics of the fibre used. The use of ordinary-grade of concrete moreover reduces the shear-resisting capacity of the joint. A hybrid mix of hooked-end steel fibre with basalt fibre and crimpled steel fibre with polypropylene fibre are used with a volume fraction of 1% to 1.4% of the concrete. In this study, ordinary M25 grade concrete and fibre mixed M25 grade concrete is employed under static and cyclic loading. The laboratory tests are also conducted to evaluate the compressive strength, split-tensile strength, and flexural strength of the hybrid mix fibre-reinforced concrete at the age of 28th days. Five full-scale models of the beam-column joint are designed as per the Bureau of Indian Standards. Numerical models of concrete and steel reinforcement are developed. Numerical analysis is carried out using finite element software ANSYS-v21. The behaviours of the beam-column joint are observed under static as well as cyclic loading. Crack patterns, first crack load, initial displacement, ultimate load, and ultimate displacement are observed under static conditions. And under cyclic loading, hysteresis load vs displacement, energy dissipation, and stiffness degradation are observed. The hybridization of hooked steel with basalt fibre gives better results in mechanical strengths and the hybrid effect of crimpled steel with polypropylene fibre gives better results in mechanical strengths. And also under numerical study, the above specimens show an improvement in energy dissipation capacity. Keywords beam-column joint, hybrid fibre reinforced concrete, numerical concrete model, ANSYS, static, reverse cyclic, energy dissipation, stiffness, crack

Conservative management of a fracture of the greater trochanter of the femur in an adult horse

SummaryAn 8‐year‐old Warmblood cross mare was presented for further investigation of an acute‐onset lameness of the right hindlimb. Three weeks prior to presentation, the horse was found markedly lame at walk following a fall during exercise. The horse was initially managed with field rest, but the lameness persisted. A marked right hindlimb lameness at trot graded 5/10 was confirmed. Atrophy of the right gluteal musculature was evident, and palpation over the region of the right coxofemoral joint provoked a pain reaction. Nuclear scintigraphy revealed a diffuse area of increased radiopharmaceutical uptake in the right femoral head, neck and greater trochanter. Radiographs identified a complete, slightly displaced fracture of the base of the greater trochanter of the right femur. Ultrasound examination of the proximal femur demonstrated an irregularity of the caudolateral bone surface of the greater trochanter, extending along its attachment to the femur; this was consistent with the radiological findings. On re‐examination, after 9 months of stable rest, the horse was found to be sound when trotted in a straight line on the hard surface. Follow‐up two and a half years after the initial incident reported the horse to be nonlame and at its previous level of work.

Application of panoramic radiographs in the diagnosis of temporomandibular disorders.

To evaluate the feasibility of temporomandibular disorder (TMD) diagnosis with panoramic radiography, and provide standardized data for artificial intelligence-assisted diagnosis by measuring the differences in the condylar and mandibular ramus heights. A total of 500 panoramic radiographs (219 male and 281 female participants) of healthy individuals were examined. The panoramic machine compatible measurement software, SCANORA 5.2.6, was used to measure the bilateral condylar height and mandibular ramus height, and SPSS 27.0 was used to calculate the left- and right-side differences in condylar height and mandibular ramus height of healthy individuals. Magnetic resonance images of the temporomandibular joint region obtained from 46 outpatients in the Stomatology Department were selected along with their corresponding panoramic radiographs. The left- and right-sided differences were measured and compared with the magnetic resonance imaging results. The measurement data are expressed as mean ± standard deviation (mm). t Tests were used to analyze data from healthy male and healthy female groups. The findings revealed that while there was no significant difference (P > .05) in the height of the condyle between men and women, there was a significant difference (P < .05) in the height of the mandibular ramus. In healthy population, the difference in height between the left and right condyle was 1.09 ± 0.99 mm. The difference in height of mandibular ramus in men was 1.26 ± 0.85 mm and that in women was 1.19 ± 0.87 mm. For the diagnosis of TMD, the sensitivity of panoramic radiographs was 94.74% (36/38), specificity was 75.00% (6/8), and diagnostic accuracy was 91.30% (42/46). The height of the right and left lateral condyles was not identical in healthy individuals, resulting in a discernible height discrepancy. In addition, the height of the mandibular ramus varied. By considering the left-right lateral height differences identified in this study along with clinical examination, it is possible to employ this metric as a preliminary screening tool for patients with TMD. Further, the use of panoramic radiographs for initial TMD screening is both viable and significant.

Portal Placement for Hip Arthroscopy

Hip arthroscopy is a well-established technique that has become a mainstay in the repair of bony and ligamentous injuries when conservative methods fail to return adequate joint mobility and function. The technique has both diagnostic and therapeutic utility and its use as a minimally invasive orthopedic surgery continues to advance. Several studies have suggested that arthroscopic surgical management has more favorable outcomes in certain circumstances when compared to hip-specific conservative measures. The approach to establishing adequate sites for portal placement is dependent upon recognizing the pertinent anatomy of the surgical site. At the same time, the operator must be mindful of the desired views once access to the joint space has been obtained. Proper visualization of the desired joint region is critical to reducing the conversion into inherently riskier total hip arthroplasties (THAs). Additionally, the neurovascular landscape of the groin presents technical challenges with the procedural approach that requires significant skill to avoid injuring vital structures in the area. Acetabular labral tears are frequently repaired with this type of operative management as techniques and approaches become more refined. Here, we present the case of a 24-year-old female who is undergoing an arthroscopic anterior labral repair, highlighting both the anatomical landmarks and the access points for portal placement used in the procedure.

Microwave joining of copper pipes using selective microwave hybrid heating process: Simulation and experimental study

High thermal conductivity of copper poses serious challenges in its joining in conventional welding techniques leading to development of alternate welding techniques. Microwave welding is one such newly developed joining technique that use selective microwave hybrid heating (SMHH). The joining of the copper pipes using SMHH has not been explored in existing literature. The present paper attempts the microwave joining of copper pipes using SMHH. The exposure time required for joining copper pipes using SMHH was predicted by COMSOL Multiphysics software. The joining was attempted at the predicted exposure time using a novel cavity design inside a conventional microwave oven. The copper pipes have been successfully joined at temperature and exposure period of 1080ºC and 720 s respectively and was in good agreement with the predicted values i.e., 708 s. Scanning electron microscopy (SEM) revealed good metallurgical bonding between the base metal and joint interface. The presence of columnar grains has been observed at heat affected zone (HAZ) using electron back scattered diffraction (EBSD). EBSD analysis revealed randomly arranged grains with mixed modes of planes inside the base metal. The occurrence of high angle grains (HAGs) along with high dislocation density in base metal resulted in the improvement in the mechanical properties as revealed in grain average misorientation (GAM) maps. The maximum value of microhardness has been observed at the joint region (105 ± 7 Hv) followed by base metal and HAZ i.e. (97 ± 5 Hv) and (89 ± 8 Hv) respectively owing to the existence of fine grain of copper (µm) and carbide formation.

Effect of tool rotational speed on friction stir spot welds of AZ31B Mg alloy to AISI 304 stainless steel

Abstract AZ31B Mg alloy were welded to AISI 304 stainless steel (which is a very challenging task because of their huge different chemical and physical features) by friction stir spot welding (FSSW) at different tool rotation speeds (700, 1000, and 1300 rpm) while keeping other conditions the same. Welds were evaluated and compared by examining their cross-sectional geometry, XRD pattern, tensile shear strength, fracture way and area. From cross-sections of welds, it was obtained that joining area expanded when speed was enhanced and the weld made through 1300 rpm had the largest one. Therefore, weld fabricated with the highest speed of 1300 rpm displayed the biggest tensile shear load of 3741 N while that manufactured with the lowest speed of 700 rpm possessed the lowest of 2430 N. All welds showed tensile shear type fracture and fracture occurred from the hooking regions where joining took place. From the fracture joint region, the weld of 700 rpm had the smallest joined area, whereas that of 1300 rpm showed the biggest. Higher speed produced a stronger joint, which agreed with a bigger bonding area and broken joint region. Also, joint became more ductile with increasing speed. Some phases were detected in joints.

Effect of Different Step-Lap Joints on the Natural Frequencies of Different Adhesively Bonded Metallic Materials: A Numerical Study

Due to their many applications' benefits, adhesively bonded joints are widely utilized in nearly every industry, including space, marine, automotive, and aeronautics. Since unpredicted loadings may cause resonance in the structures, an accurate prediction of the bonded joints' dynamic characteristics is crucial. Therefore, in this study, modal analysis was performed on the two-, three-, four- and double-step adhesively bonded lap joints of Aluminum (Al), Copper (Cu), and Mild steel (Ms) materials with Epoxy Araldite adhesive. Ansys commercial program was utilized to analyze it numerically. The results showed that modeling the bonding region of single lap joints as two-, three-, and four-step adhesively bonded lap joints has no significant effect on the natural frequencies. This modeling has a minor incremental effect on the natural frequencies. However, Double-step lap joints were found to cause a considerable reduction in natural frequencies compared to not only single lap joints but also two-, three-, and four-step adhesively bonded lap joints. Double-step bonding caused a decrease of 8.82%, 8.57%, and 8.73% for Al-Al, Cu-Cu, and Ms-Ms. In general, in all models, the best increase or decrease in terms of natural frequencies was found to be Cu-Cu adhesively lap joints.

Cyclic behavior of UHPC corner beam-column joints under bi-directional bending

Design codes contain special provisions for anchorage lengths of flexural reinforcement and amount of transverse reinforcement in beam-column joints, to safeguard against joint failure and possible structural collapse. However, those stipulations could lead to congested joints with construction problems such as segregation. This study leverages experimental testing of eight corner beam-column joints under constant axial and cyclic bi-directional bending loads. In addition to being one of few on corner joints under a complex and practical loading, the study’s main aim is to evaluate the effectiveness of ultra-high-performance concrete (UHPC) as a joint fill in lieu of normal strength concrete (NSC). Brittle failure, either by pure shear or shear combined with yielding of beam reinforcement occurred in all NSC joints and varied in shape and intensity depending on the column depth-to-beam longitudinal bar diameter (hc ⁄db) ratio and spacing of transverse beam/column reinforcement. Ductile failure characterized by the yielding of beam reinforcement and plastic hinge at the beam-joint interface occurred in all UHPC joints and was independent of the two aforementioned variables. The application of UHPC in the joint region resulted in increasing the joint ultimate strength by 27.6–54.8%, energy dissipation by 24–163%, and stiffness by 20 to 50%, compared to NSC joints. Such results were obtained when no transverse reinforcement is used in the joint, and only half transverse reinforcement is used in the beam/column members, and with hc ⁄db relaxed to 38% of the code recommended ratio, highlighting the advantages of UHPC joints. Predictions of ACI-ASCE 352R code were found to be overly unconservative and in need of future improvement.

Study of Prevalence of Temporomandibular Disorders among Undergraduate Students

Temporo-mandibular joint function has been extensively studied for more despite extensive investigation, the complicated etiology of TMJ dysfunction has remained a mystery for more than a century. Temporomandibular disorder (TMD) is a sub - class of painful orofacial conditions characterized by complaints of pain in the region of the temporomandibular joint (TMJ), difficulty concentrating craniocervicofacial muscles, especially mastication muscles, limitations of mandibular movement, and the presence of articular clicking. Emotional stress, occlusal interferences, tooth loss, postural deviation, muscles of mastication neuromuscular both internal and external dysfunction anomalies in Temporo-mandibular joint anatomy, and the multiple interrelationships between these factors all contribute to the complicated etiology of TMD.Aim: Determine the prevalence of temporomandibular joint disorder between college students. The sample for this sectional potential study consisted of 691 college students (339 male and 352 female). Self-reported questionnaires were used to determine the incidence and severity of TMJ disorders. By virtue of the quantity and frequency of notable replies, the rankings were upgraded to an intensity ranking. Results:56.6% of students reported some level of TMD, including 39.7% with mild TMD, 12.2% with moderate TMD, and 4.6% with severe TMD. Historically, no significant correlation between gender and TMD severity was observed.Conclusion: This student population exhibited a high prevalence of TMD; however, the majority of cases were mild. The statistical significance of the association between TMD severity and gender is no longer proven. Despite having TMD. The students had little knowledge of their conditions.

Mast cell tumour‐associated osteolysis in a Shiba dog

AbstractA 13‐year‐old, female Shiba dog presented with elevation of the right pelvic limb and swelling of the thigh. The right pelvic limb was severely swollen, and subcutaneous haemorrhaging was observed. Radiographs showed bone resorption in the stifle joint region. Fine‐needle aspiration cytology of the stifle was consistent with a mast cell tumour. Computed tomography was performed, and the affected limb was amputated. The histo‐pathological diagnosis was mast cell tumour, and the femur and tibia were found externally lysed with an internal invasion of tumour cells. The safety margins were secured, but the tumour had infiltrated the lymph nodes. Hence, the patient was treated with chemotherapy. There was no tumour recurrence or metastasis for 201 days after surgery, but the patient died. To our knowledge, no case of osteolysis due to mast cell tumour has been reported, making this a very rare case.

SUBCHONDRAL MICROCHANNEL NETWORK CHANGES IN EARLY OSTEOARTHRITIS

Articular cartilage (AC) and subchondral bone (SB) are intimately intertwined, forming a complex unit called the AC-SB interface. Our recent studies have shown that cartilage and bone marrow are connected by a three-dimensional network of microchannels (i.e. cartilage-bone marrow microchannel connector; CMMC), which differ microarchitecturally in number, size and morphology depending on the maturation stage of the bone and the region of the joint. However, the pathological significance of CMMC is largely unknown. Here, we quantitatively assessed how CMMC microarchitecture relates to cartilage condition and regional differences in early idiopathic osteoarthritis (OA).Two groups of cadaveric female human femoral heads (intact cartilage vs early cartilage lesions) were identified and biopsy-based high-resolution micro-CT imaging was used. Subchondral bone (SB) thickness, CMMC number, maximum and minimum CMMC size, and CMMC morphology were quantified and compared between the two groups. The effect of joint region and cartilage condition on each dependent variable was examined.The number and morphology of CMMCs were influenced by the region of the joint, but not by the cartilage condition. On the other hand, the minimum and maximum CMMC size was modified by both joint location and cartilage condition. The smallest CMMCs were consistently found in the load bearing region (LBR) of the joint. Compared to healthy subjects, the size of the microchannels was increased in early OA, most notably in the non-load bearing region (NLBR) and the peripheral rim (PR) of the femoral head. In addition, subchondral bone thinning was observed in early OA as a localized event associated with areas of partial chondral defect.Our data suggest an enlargement of the SB microchannel network and a collective structural deterioration of the SB in early idiopathic OA.