Synovial fluid is the fluid washing the inside of the joint, secreted by the synovium - the cells of the joint lining.

Joint fluid

Enclosing the articulating part of the knee joint is a water-tight capsule made of a strong fibrous material lined on the inside with a thin layer of secretory cells.

A simple explanation of the term 'water on the knee'.



Effect of Tibial Plateau Fracture on Lubrication Function and Composition of Synovial Fluid. Ballard BL et al. J Bone Joint Surg Am. 2012 May 16; 94(10): e64.

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