What is synovitis?
Synovitis is an inflammatory disease affecting the synovial membrane (or synovium), the tissue that lines the interior of the joints. Following the inflammatory stimulus, the membrane produces a greater quantity of synovial fluid, causing a thickening of its wall and a swelling of the joint.
Synovitis can also affect other structures adjacent to the synovium, belonging to the joint ( arthrosynovitis ) or to the tendinous formations ( tenosynovitis ). The causes that determine the onset can be different (infections, traumas ...); furthermore, it can occur in association with arthritis, gout and lupus.
Synovitis can be acute (due to trauma or infectious factors) or chronic (due to diseases such as tumor proliferation or rheumatoid arthritis).
In short: anatomical structures and joint functions
The synovial fluid fills the joint cavity: it is produced by the vascularized synovial membrane that secretes the liquid by plasma filtration (in the synovitis the joint swells due to the collection of synovial fluid).
The synovial fluid is also contained within the synovial bags ; the function of these anatomical elements is to protect the structures between which they are interposed (bones, tendons and muscles): they reduce the friction between the bones, allow free movements, determine a better distribution of the load and the stresses to which the joints are subjected .
Synovial fluid is also contained within the synovial sheaths, anatomical structures that line the tendons to reduce friction from rubbing along their course
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Symptoms
To learn more: Symptoms Synovitis
The symptomatology common to all forms of synovitis includes swelling (swelling) associated with local pain, serous joint effusion and limitation or even impossibility to perform movements of the affected joint. The area affected by synovitis appears to be swollen, hot (due to increased blood flow, caused by inflammation) and painful (for example, in the case of the knee especially in an attempt to extend the leg). In case of infection, the skin of the knee could also be tense and reddened. In the case of chronic progression of the pathology, the synovial membrane can thicken and erode the underlying bone, causing further pain and degenerative changes, sometimes the appearance of inflammatory nodules.
Causes
What causes synovitis?
The causes that determine the synovitis are different: violent traumas, slight or repeated, rheumatic diseases (example: gout), local infections or general infectious diseases (example: rheumatic fever), metabolic disorders, lupus, arthrosis, rheumatoid arthritis, synoviomas (tumors of the synovial membrane).
The forms of acute synovitis are due to traumas or secondary to infectious diseases (for example: septicopemia, cerebrospinal meningitis, scarlet fever, abdominal typhus etc.) and can be exudative: the inflammatory fluid infiltrates the thickness of the membrane and collects in the joint cavity mixing with the synovial fluid.
The forms of chronic synovitis can be of bacterial nature (syphilis, tuberculosis) or due to particular conditions; they can cause degeneration of the joint, suffering of articular cartilage and osteoarthritis.
The consequence of synovitis is inflammation of the tendon related to the affected joint, which tends to become chronic and degenerate.
Diagnosis
The diagnosis of synovitis begins with the patient's detailed medical history and continues with the medical examination, which allows the identification of the general clinical features of the inflammation (heat, redness and swelling). In some cases, to reach a definitive and more precise diagnosis, the specialist can make use of imaging diagnostics (X-rays, magnetic resonance imaging or computerized axial tomography) and? ™ arthroscopy . The analysis of the aspirated synovial fluid allows to confirm or exclude various common diseases, such as traumatic or rheumatoid arthritis, arthrosis, gout and arthritis.
Synovial fluid analysis
The examination of synovial fluid is a diagnostic procedure widely used in clinical practice related to diseases of the musculoskeletal system. The analysis subjects the viscous and transparent fluid secreted by the synovial membrane to a clinical investigation, to define a diagnosis quickly, at low cost and in an unequivocal manner; it also provides indications on the inflammatory or non-inflammatory nature of the joint effusion through a simple leukocyte count, and allows to formulate hypotheses on any septic forms, which, in any case, require a microbiological confirmation.
No special preparations are required prior to collection. The skin above the joint is disinfected and usually a local anesthetic is injected. Using a thin needle, the doctor takes a liquid sample for analysis; the latter includes the culture of the fluid when the infection is a possible diagnosis (the infectious factors / pathogenic bacteria responsible for the primary disease are found) and the examination of the microcrystals to diagnose gout (relevant in the rheumatology field: the discovery of the crystals of in fact, monosodium urate and calcium pyrophosphate allows instant diagnosis of gout and pseudogout).
The analysis of synovial fluid is often able to provide useful elements for diagnostic and therapeutic purposes: the examination can be useful for assessing the evolution of joint disease, or for verifying the effects of therapy.
The chemical-physical characteristics of the synovial fluid are representative of quantity, viscosity, appearance and color (clarity, presence of blood and / or pus):
Macroscopic characters found in the synovial fluid | |||
Color | Appearance | Viscosity | Synovial fluid |
Light yellow | Transparent | preserved | Not inflammatory |
Dark yellow | turbid | Reduced | Inflammatory |
Greenish-yellow | Purulent or milky | Variable | Septic |
Microscopic investigations of the synovial fluid include: leukocyte count, the cytological formula of the cells possibly present in the liquid, the microbiological examination and the observation of the fresh preparation (a liquid drop is deposited on a glass slide and observed with an optical microscope for search for the presence of cells, crystals etc.).
To confirm the diagnosis of synovitis it is possible to proceed with histological analysis by needle-biopsy in order to study the characteristics of the synovial membrane under the microscope.
Synovitis: Care and Conservative and Surgical Therapies "
