- 1. It provides a smooth gliding surface and reduces forces of compression during weight-bearing or muscle action. The coefficient of friction is equal to “ice on ice”. The surface of the cartilage is not perfectly smooth and shows fine undulations, which are filled with synovial fluid. In fact, the fibrous capsule is extremely porous and absorbs synovial fluid in the resting condition. When the joint is compressed, the fluid is squeezed out of the cartilage [wiki].
- 2. It regulates the growth of epiphysis.
The fibrous capsule consists of cells and an interlacement of collagen fibers. The surface is cell free and composed essentially of a network of fine fibers. The cells are arranged in three layers, from superficial to deep:
- 1. Superficial layer: it consists of flattened cells, placed parallel with the articular surface.
- 2. Intermediate layer: the cartilage cells are rounded and arranged in longitudinal rows.
- 3. Deep layer: it consists of calcified matrix. Here cartilage cells die and are replaced by bones.
Monitoring and Evaluation of Biomaterials and their Performance in vivo. http://dx.doi.org/10.1016/B978-0-08-100603-0.00004-3
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During growth the cartilage cells of the intermediate layer proliferate by mitosis and grow away from the advancing bones. Once growth is over, the number of cells in the fibrous capsule slowly decreases throughout life in relation to the amount of intercellular substance.