Synovial fluid (including synovial fluid or synovial fluid ) is a viscous , stringy, clear body fluid in joints . It is formed by the synovial membrane , the inner layer of the joint capsule , and forms a sliding film on the joint surfaces. The term goes back to Paracelsus and is derived from the Greek syn "together with" and the Latin ovum "egg", as it resembles egg white in consistency and appearance.
- Hyaluronic acid
- Fat droplets
- 2.5% proteins (1.9% albumin , 0.9% globulins )
- Glucose and glycosaminoglycans , which are responsible for the different viscosity depending on the load
- 94% water
- 0.5% mucins
- detached cells of the synovial membrane of the joint capsule and immune cells
The exchange of fluids and thus the nutrition of the articular cartilage is maintained by alternating loading and unloading of the articular cartilage. As a result of this change, the spongy cartilage tissue is “saturated” and nourished by the synovia. If a joint is immobilized for a long time , but also if it is overloaded, cartilage damage occurs as a result of nutritional disorders .
When there are changes in the joints, be it due to an injury, an inflammatory disease or due to wear and tear, the body reacts with increased production of synovial fluid (joint hydrops ). From the outside, this is noticeable as a swelling of the joint. The tactile findings make it possible to differentiate between a swelling of the joint capsule and an effusion . If the synovia is produced in excess, its composition changes. The normally highly viscous, clear, yellow liquid becomes watery, sometimes cloudy due to cell abrasion or darkened in color due to hemorrhage ( hemarthrosis ). It can then no longer perform its normal functions, and the addition of blood even makes the synovia aggressive towards the cartilage. In veterinary medicine this is also known as joint bile .
If the increased synovial fluid produced remains clear and does not show any abnormalities in the laboratory results , it is referred to as an irritant shower . This occurs quite often after injuries, osteoarthritis or after operations on the joint, of course it hinders function and can overstretch the joint capsule. If the effusion becomes too large, the joint must be punctured . This may only be done under sterile conditions, otherwise there is a risk of pyarthrosis in the joints . The laboratory analysis of the liquid obtained can provide information on the underlying disease. Inflammatory processes, for example in rheumatoid arthritis , can be detected, as well as disorders of uric acid metabolism in gout .
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