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Seminars in Ultrasound, CT, and MR Jun 2007The temporomandibular joint (TMJ), also known as the mandibular joint, is an ellipsoid variety of the right and left synovial joints forming a bicondylar articulation....
The temporomandibular joint (TMJ), also known as the mandibular joint, is an ellipsoid variety of the right and left synovial joints forming a bicondylar articulation. The common features of the synovial joints exhibited by this joint include a fibrous capsule, a disk, synovial membrane, fluid, and tough adjacent ligaments. Not only is the mandible a single bone but the cranium is also mechanically a single stable component; therefore, the correct terminology for the joint is the craniomandibular articulation. The term temporomandibular joint is misleading and seems to only refer to one side when referring to joint function. Magnetic resonance imaging has been shown to accurately delineate the structures of the TMJ and is the best technique to correlate and compare the TMJ components such as bone, disk, fluid, capsule, and ligaments with autopsy specimens.
Topics: Dental Occlusion; Humans; Joint Capsule; Ligaments, Articular; Magnetic Resonance Imaging; Mandibular Condyle; Masseter Muscle; Pterygoid Muscles; Sphenoid Bone; Synovial Fluid; Synovial Membrane; Temporal Bone; Temporal Muscle; Temporomandibular Joint; Temporomandibular Joint Disc
PubMed: 17571700
DOI: 10.1053/j.sult.2007.02.002 -
Progress in Molecular Biology and... 2017Matrix metalloproteinases (MMPs) are zinc-dependent enzymes. These enzymes play a critical role in the destruction of articular cartilage in rheumatoid arthritis (RA),... (Review)
Review
Matrix metalloproteinases (MMPs) are zinc-dependent enzymes. These enzymes play a critical role in the destruction of articular cartilage in rheumatoid arthritis (RA), osteoarthritis (OA), psoriatic arthritis (PsA), and the spondyloarthropathies. MMP gene expression is upregulated in these synovial joint pathologies in response to elevated levels of proinflammatory cytokines and soluble mediators such as tumor necrosis factor-α, interleukin-1 (IL-1), IL-6, IL-17, and interferon-γ. These molecules are capable of activating the mitogen-activated protein kinase and Janus kinase/signal transducers and activators of transcription (JAK/STAT) pathways by binding the cytokine to their respective receptors on immune cells, macrophages, chondrocytes, synoviocytes, and osteocytes leading to increased synthesis of MMPs. Biologic drugs and/or small-molecule inhibitors designed to block cytokine to cytokine receptor interactions or to selectively inhibit JAKs have clinical efficacy in RA, PsA, and ankylosing spondylitis which correlated with a reduction in MMPs. Although there are currently no OA-selective drugs, it is likely that such a drug would have to reduce MMP gene expression to have clinical efficacy.
Topics: Animals; Humans; Joints; Matrix Metalloproteinases; Models, Biological; Synovial Membrane
PubMed: 28662824
DOI: 10.1016/bs.pmbts.2017.03.003 -
Wiley Interdisciplinary Reviews.... 2012The synovial joint contains synovial fluid (SF) within a cavity bounded by articular cartilage and synovium. SF is a viscous fluid that has lubrication, metabolic, and... (Review)
Review
The synovial joint contains synovial fluid (SF) within a cavity bounded by articular cartilage and synovium. SF is a viscous fluid that has lubrication, metabolic, and regulatory functions within synovial joints. SF contains lubricant molecules, including proteoglycan-4 and hyaluronan. SF is an ultrafiltrate of plasma with secreted contributions from cell populations lining and within the synovial joint space, including chondrocytes and synoviocytes. Maintenance of normal SF lubricant composition and function are important for joint homeostasis. In osteoarthritis, rheumatoid arthritis, and joint injury, changes in lubricant composition and function accompany alterations in the cytokine and growth factor environment and increased fluid and molecular transport through joint tissues. Thus, understanding the synovial joint lubrication system requires a multifaceted study of the various parts of the synovial joint and their interactions. Systems biology approaches at multiple scales are being used to describe the molecular, cellular, and tissue components and their interactions that comprise the functioning synovial joint. Analyses of the transcriptome and proteome of SF, cartilage, and synovium suggest that particular molecules and pathways play important roles in joint homeostasis and disease. Such information may be integrated with physicochemical tissue descriptions to construct integrative models of the synovial joint that ultimately may explain maintenance of health, recovery from injury, or development and progression of arthritis.
Topics: Animals; Arthritis; Biological Transport; Female; Humans; Joints; Male; Mice; Models, Biological; Peptide Hydrolases; Proteomics; Rats; Synovial Fluid; Systems Biology
PubMed: 21826801
DOI: 10.1002/wsbm.157 -
Developmental Dynamics : An Official... Apr 2017Here we review studies identifying regulatory networks responsible for synovial, cartilaginous, and fibrous joint development. Synovial joints, characterized by the... (Review)
Review
Here we review studies identifying regulatory networks responsible for synovial, cartilaginous, and fibrous joint development. Synovial joints, characterized by the fluid-filled synovial space between the bones, are found in high-mobility regions and are the most common type of joint. Cartilaginous joints such as the intervertebral disc unite adjacent bones through either a hyaline cartilage or a fibrocartilage intermediate. Fibrous joints, which include the cranial sutures, form a direct union between bones through fibrous connective tissue. We describe how the distinct morphologic and histogenic characteristics of these joint classes are established during embryonic development. Collectively, these studies reveal that despite the heterogeneity of joint strength and mobility, joint development throughout the skeleton utilizes common signaling networks via long-range morphogen gradients and direct cell-cell contact. This suggests that different joint types represent specialized variants of homologous developmental modules. Identifying the unifying aspects of the signaling networks between joint classes allows a more complete understanding of the signaling code for joint formation, which is critical to improving strategies for joint regeneration and repair. Developmental Dynamics 246:262-274, 2017. © 2016 Wiley Periodicals, Inc.
Topics: Animals; Cartilage, Articular; Gene Regulatory Networks; Humans; Joint Capsule; Joints; Morphogenesis; Regeneration; Signal Transduction
PubMed: 27859991
DOI: 10.1002/dvdy.24472 -
Current Osteoporosis Reports Feb 2015Synovial joint morphogenesis occurs through the condensation of mesenchymal cells into a non-cartilaginous region known as the interzone and the specification of... (Review)
Review
Synovial joint morphogenesis occurs through the condensation of mesenchymal cells into a non-cartilaginous region known as the interzone and the specification of progenitor cells that commit to the articular fate. Although several signaling molecules are expressed by the interzone, the mechanism is poorly understood. For treatments of cartilage injuries, it is critical to discover the presence of joint progenitor cells in adult tissues and their expression gene pattern. Potential stem cell niches have been found in different joint regions, such as the surface zone of articular cartilage, synovium, and groove of Ranvier. Inherited joint malformations as well as joint-degenerating conditions are often associated with other skeletal defects and may be seen as the failure of morphogenic factors to establish the correct microenvironment in cartilage and bone. Therefore, exploring how joints form can help us understand how cartilage and bone are damaged and develop drugs to reactivate this developing mechanism.
Topics: Homeostasis; Humans; Joints; Morphogenesis; Organogenesis
PubMed: 25431159
DOI: 10.1007/s11914-014-0247-7 -
Biomechanics and Modeling in... Oct 2020Joints enable the relative movement between the connected bones. The shape of the joint is important for the joint movements since they facilitate and smooth the...
Joints enable the relative movement between the connected bones. The shape of the joint is important for the joint movements since they facilitate and smooth the relative displacement of the joint's parts. The process of how the joints obtain their final shape is yet not well understood. Former models have been developed in order to understand the joint morphogenesis leaning only on the mechanical environment; however, the obtained final anatomical shape does not match entirely with a realistic geometry. In this study, a computational model was developed with the aim of explaining how the morphogenesis of joints and shaping of ossification structures are achieved. For this model, both the mechanical and biochemical environments were considered. It was assumed that cartilage growth was controlled by cyclic hydrostatic stress and inhibited by octahedral shear stress. In addition, molecules such as PTHrP and Wnt promote chondrocyte proliferation and therefore cartilage growth. Moreover, the appearance of the primary and secondary ossification centers was also modeled, for which the osteogenic index and PTHrP-Ihh concentrations were taken into account. The obtained results from this model show a coherent final shape of an interphalangeal joint, which suggest that the mechanical and biochemical environments are crucial for the joint morphogenesis process.
Topics: Algorithms; Computer Simulation; Humans; Hydrostatic Pressure; Joints; Morphogenesis; Osteogenesis; Stress, Mechanical; Synovial Membrane
PubMed: 31863216
DOI: 10.1007/s10237-019-01277-4 -
Annals of the Royal College of Surgeons... Oct 2020Synovial chondromatosis is a rare benign condition. It most commonly affects the large joints. Presentation in the temporomandibular joint is rare. Our case was an...
Synovial chondromatosis is a rare benign condition. It most commonly affects the large joints. Presentation in the temporomandibular joint is rare. Our case was an incidental radiological finding and not diagnosed immediately, highlighting the ease with which conditions such as this can be missed, particularly in asymptomatic patients. Only 45% of patients with synovial chondromatosis show radiographic changes. Findings as significant as ours are unusual. An increased professional awareness of the radiological signs of synovial chondromatosis would be beneficial to improve diagnosis and prognosis for patients.
Topics: Chondromatosis, Synovial; Humans; Male; Middle Aged; Temporomandibular Joint
PubMed: 32588651
DOI: 10.1308/rcsann.2020.0125 -
The Anatomical Record Sep 1994Making a durable joint requires adapting the one present at birth to its subsequent mechanical usage and then maintaining it. The total loads on a joint's momentarily... (Review)
Review
Making a durable joint requires adapting the one present at birth to its subsequent mechanical usage and then maintaining it. The total loads on a joint's momentarily loaded area plus the size of that area determine the unit loads on its articular cartilage and subchondral bone. Given those facts, this model suggests the following. For adaptation: As is true for bone, a threshold range of unit loads that could turn cartilage modeling ON would lie below this tissue's microdamage threshold. When a joint's unit loads rose to that modeling threshold, chondral modeling would begin enlarging the momentarily loaded area to reduce and keep the unit loads on it below the microdamage thresholds of the bone and cartilage supporting that area. For maintenance: Maintenance activities would control the stiffness of cartilage and bone, which would also affect a joint's momentarily loaded area. These activities would usually repair whatever microdamage normally arises in those tissues, and could modify their microdamage thresholds too. In children, modeling and maintenance in bone and cartilage would function effectively. In adults chondral modeling becomes ineffective, but maintenance activities in bone and cartilage would remain effective, and likewise for modeling in the subchondral bone. This model assigns special importance in joint design to the stiffness of bone, cartilage, and ligament (as distinguished from their strength), to the typical largest unit loads applied to them by a subject's usual weekly physical activities, and to their microdamage.
Topics: Age Factors; Biomechanical Phenomena; Bone Development; Bone Remodeling; Cartilage; Humans; Joints; Models, Biological
PubMed: 7810906
DOI: 10.1002/ar.1092400102 -
The International Journal of... 2008Synovial (diarthrodial) joints are employed within the body to provide skeletal mobility and have a characteristic structure adapted to provide a smooth almost... (Review)
Review
Synovial (diarthrodial) joints are employed within the body to provide skeletal mobility and have a characteristic structure adapted to provide a smooth almost frictionless surface for articulation. Pathologies of the synovial joint are an important cause of patient morbidity and can affect each of the constituent tissues. A common feature of these pathologies is degenerative changes in the structure of the tissue which is mediated, at least in part, by proteolytic activity. Most tissues of the synovial joint are composed primarily of extracellular matrix and key pathological roles in the degeneration of this matrix are performed by metalloproteinases such as matrix metallproteinases (MMPs) and a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS). However, other proteases such as cathepsin K are likely to play an important role, especially in bone turnover. In addition to the cleavage of structural proteins, proteolytic activities are employed to regulate the activity of other proteases, growth factors, cytokines and other inflammatory mediators. Proteases combine to form complex regulatory networks, the correct functioning of which is required for tissue homeostasis and the imbalance of which may be a feature of pathology. A precise understanding of the proteases involved in these networks is required for a true understanding of the associated pathology.
Topics: Humans; Joints; Models, Biological; Peptide Hydrolases; Synovial Membrane
PubMed: 18339575
DOI: 10.1016/j.biocel.2008.01.024 -
Veterinary Journal (London, England :... Apr 2017The maintenance of joint homeostasis is integral to joint health. Knowledge of the influence of exercise on joint homeostasis is not only relevant for determining... (Review)
Review
The maintenance of joint homeostasis is integral to joint health. Knowledge of the influence of exercise on joint homeostasis is not only relevant for determining sustainable levels of equine athletic training, but also for the study of early development of osteoarthritis or cartilage repair in animal models. This review provides an overview of findings derived from in vivo studies and postmortem analyses investigating exercise effects on various joint tissue components in the horse, supplemented where appropriate with data from small animal models. The concept of joint homeostasis and possible methods to quantify this are also discussed, with special attention to the potential benefits and pitfalls of biomarker analysis in synovial fluid. The main conclusion is that biomechanical loading in the form of deliberate exercise has a major influence on the delicate homeostatic balance within the tissues constituting the diarthrodial joint and on their interactions, which is crucial for proper and durable joint function. The amount and intensity of exercise can have a lasting effect on tissue characteristics in juvenile animals, but affects joint homeostasis in mature animals and can affect the delicate balance between physiologic adaptation and development of pathology. Biomarkers in synovial fluid can be helpful in assessing joint homeostasis, but their use and interpretation require caution and are often far from straightforward.
Topics: Animals; Biomarkers; Homeostasis; Horses; Joints; Physical Conditioning, Animal; Synovial Fluid
PubMed: 28392152
DOI: 10.1016/j.tvjl.2017.03.004