The synovium, also called the synovial membrane, is the soft tissue that lines the spaces of diarthrodial joints, tendon sheaths, and bursae.
The synovium is wheresynovial fluidis produced, the substance that lubricates and nourishes the cartilage and bones inside the joint capsule.
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Synovium Anatomy
The synovium is a special type of connective tissue located in articulated joints like the knees and elbows. The synovium lines the entire inner surface of the joint, except where the joint is lined withcartilage. The synovium is made up of an outer layer (subintima) and an inner layer (intima).
The subintima consists of intra-articular (within the joint) vessels, such as blood vessels and lymphatic vessels, and nerves. The cells of the intima are called synoviocytes. There are two types of synoviocytes, type A (macrophage-derived) and type B (fibroblast-derived). Underneath the layer of synoviocytes, there is either adipose tissue or fibrous tissue.
Synovium Function
In the joints, the synovium’s purpose is the production of synovial fluid and the maintainance of the volume of fluid inside the joint. It also acts as a seal around the joint cavity to keep the fluid inside.
The synovium and cartilage are both parts of the joint. The synovium, however, produces fluid that helps protect the cartilage, while the cartilage helps protect and cushion the bones.
Synovial Fluid
Loss of synovial fluid can have a number of causes, including rheumatoid arthritis, normal aging, and lack of exercise.
The Synovium in Rheumatoid Arthritis
As rheumatoid arthritis progresses, the inflamed synovium invades anddestroys the cartilage and boneof the joint. The surrounding muscles, ligaments, and tendons that support and stabilize the joint become weak and unable to work normally. These effects lead to the joint pain and joint damage typically seen in people with rheumatoid arthritis.Understanding what happens to synovium in rheumatoid arthritis helps you to understand symptoms and disease severity.
Treatments to Target Inflamed Synovium - Are They Coming?
Researchers have been interested in developing tissue-specific treatments for rheumatoid arthritis. Potential drugs could target the synovium with increased efficacy and decreased systemic toxicity. If research into this process succeeds, imaging agents could be delivered directly to the synovium, allowing for an assessment of active synovitis in multiple joints. Although advancements have been made in this area, a specific synovial receptor has yet to be discovered.
Frequently Asked Questions
The function of synovial fluid is to provide cushioning for the bones that make up your joints. It is an essential component for joint movement and is produced within the synovium. Analyzing the color and thickness of synovial fluid can help a doctor diagnose issues with the joints, such as osteoarthritis and gout.
8 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Redondo ML, Christian DR, Yanke AB.The role of synovium and synovial fluid in joint hemostasis. In: Yanke A, Cole B, eds. Joint Preservation of the Knee. Cham, Switzerland: Springer. 2019;57-67.Mathiessen A, Conaghan PG.Synovitis in osteoarthritis: current understanding with therapeutic implications.Arthritis Res Ther.2017;19(18):1-9. doi:10.1186/s13075-017-1229-9National Library of Medicine.Synovial fluid analysis.Yap HY, Tee SZ, Wong MM, Chow SK, Peh SC, Teow SY.Pathogenic role of Immune cells in rheumatoid arthritis: implications in clinical treatment and biomarker development. Cells. 2018;7(10). doi:10.3390/cells7100161Ostrowska M, Maśliński W, Prochorec-Sobieszek M, Nieciecki M, Sudoł-Szopińska I.Cartilage and bone damage in rheumatoid arthritis. Reumatologia. 2018;56(2):111-120.Ouboussad L, Burska AN, Melville A, Buch MH.Synovial tissue heterogeneity in rheumatoid arthritis and changes with biologic and targeted synthetic therapies to inform stratified therapy. Front Med (Lausanne). 2019;6:45. doi:10.2174/1874312901105010115Hospital for Special Surgery (HSS).Synovitis.MedlinePlus.Synovial Fluid Analysis.Additional ReadingAmerican College of Rheumatology.Medication Guides.Mathiessen A, Conaghan PG.Synovitis in osteoarthritis: current understanding with therapeutic implications. Arthritis Res Ther. 2017;19(1):18. doi:10.1186/s13075-017-1229-9Smith MD.The normal synovium. Open Rheumatol J. 2011;5:100-6.
8 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Redondo ML, Christian DR, Yanke AB.The role of synovium and synovial fluid in joint hemostasis. In: Yanke A, Cole B, eds. Joint Preservation of the Knee. Cham, Switzerland: Springer. 2019;57-67.Mathiessen A, Conaghan PG.Synovitis in osteoarthritis: current understanding with therapeutic implications.Arthritis Res Ther.2017;19(18):1-9. doi:10.1186/s13075-017-1229-9National Library of Medicine.Synovial fluid analysis.Yap HY, Tee SZ, Wong MM, Chow SK, Peh SC, Teow SY.Pathogenic role of Immune cells in rheumatoid arthritis: implications in clinical treatment and biomarker development. Cells. 2018;7(10). doi:10.3390/cells7100161Ostrowska M, Maśliński W, Prochorec-Sobieszek M, Nieciecki M, Sudoł-Szopińska I.Cartilage and bone damage in rheumatoid arthritis. Reumatologia. 2018;56(2):111-120.Ouboussad L, Burska AN, Melville A, Buch MH.Synovial tissue heterogeneity in rheumatoid arthritis and changes with biologic and targeted synthetic therapies to inform stratified therapy. Front Med (Lausanne). 2019;6:45. doi:10.2174/1874312901105010115Hospital for Special Surgery (HSS).Synovitis.MedlinePlus.Synovial Fluid Analysis.Additional ReadingAmerican College of Rheumatology.Medication Guides.Mathiessen A, Conaghan PG.Synovitis in osteoarthritis: current understanding with therapeutic implications. Arthritis Res Ther. 2017;19(1):18. doi:10.1186/s13075-017-1229-9Smith MD.The normal synovium. Open Rheumatol J. 2011;5:100-6.
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
Redondo ML, Christian DR, Yanke AB.The role of synovium and synovial fluid in joint hemostasis. In: Yanke A, Cole B, eds. Joint Preservation of the Knee. Cham, Switzerland: Springer. 2019;57-67.Mathiessen A, Conaghan PG.Synovitis in osteoarthritis: current understanding with therapeutic implications.Arthritis Res Ther.2017;19(18):1-9. doi:10.1186/s13075-017-1229-9National Library of Medicine.Synovial fluid analysis.Yap HY, Tee SZ, Wong MM, Chow SK, Peh SC, Teow SY.Pathogenic role of Immune cells in rheumatoid arthritis: implications in clinical treatment and biomarker development. Cells. 2018;7(10). doi:10.3390/cells7100161Ostrowska M, Maśliński W, Prochorec-Sobieszek M, Nieciecki M, Sudoł-Szopińska I.Cartilage and bone damage in rheumatoid arthritis. Reumatologia. 2018;56(2):111-120.Ouboussad L, Burska AN, Melville A, Buch MH.Synovial tissue heterogeneity in rheumatoid arthritis and changes with biologic and targeted synthetic therapies to inform stratified therapy. Front Med (Lausanne). 2019;6:45. doi:10.2174/1874312901105010115Hospital for Special Surgery (HSS).Synovitis.MedlinePlus.Synovial Fluid Analysis.
Redondo ML, Christian DR, Yanke AB.The role of synovium and synovial fluid in joint hemostasis. In: Yanke A, Cole B, eds. Joint Preservation of the Knee. Cham, Switzerland: Springer. 2019;57-67.
Mathiessen A, Conaghan PG.Synovitis in osteoarthritis: current understanding with therapeutic implications.Arthritis Res Ther.2017;19(18):1-9. doi:10.1186/s13075-017-1229-9
National Library of Medicine.Synovial fluid analysis.
Yap HY, Tee SZ, Wong MM, Chow SK, Peh SC, Teow SY.Pathogenic role of Immune cells in rheumatoid arthritis: implications in clinical treatment and biomarker development. Cells. 2018;7(10). doi:10.3390/cells7100161
Ostrowska M, Maśliński W, Prochorec-Sobieszek M, Nieciecki M, Sudoł-Szopińska I.Cartilage and bone damage in rheumatoid arthritis. Reumatologia. 2018;56(2):111-120.
Ouboussad L, Burska AN, Melville A, Buch MH.Synovial tissue heterogeneity in rheumatoid arthritis and changes with biologic and targeted synthetic therapies to inform stratified therapy. Front Med (Lausanne). 2019;6:45. doi:10.2174/1874312901105010115
Hospital for Special Surgery (HSS).Synovitis.
MedlinePlus.Synovial Fluid Analysis.
American College of Rheumatology.Medication Guides.Mathiessen A, Conaghan PG.Synovitis in osteoarthritis: current understanding with therapeutic implications. Arthritis Res Ther. 2017;19(1):18. doi:10.1186/s13075-017-1229-9Smith MD.The normal synovium. Open Rheumatol J. 2011;5:100-6.
American College of Rheumatology.Medication Guides.
Mathiessen A, Conaghan PG.Synovitis in osteoarthritis: current understanding with therapeutic implications. Arthritis Res Ther. 2017;19(1):18. doi:10.1186/s13075-017-1229-9
Smith MD.The normal synovium. Open Rheumatol J. 2011;5:100-6.
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