fibrous joint

joined by fibres

cartilaginous joint

joined by cartilage

synovial joint

have a joint cavity

articular cartilage

dense, translucent connective tissue. virtually isolated structure lacking blood vessels, lymphatic channels, neurological innovation. functions - distribute joint loads, minimise friction.

composition of cartilage.

chondrocytes, collagen (15-22%), proteoglycan (4-7%), water (60-85%).

collagen

out abundant protein in the body. found in articular cartilage, bone, skin, meniscus & intervertebral discs. high in tensile strength but weak and buckles easily in compression. is anisotropic.

proteoglycan (PGs)

a large protein-polysaccharide molecule. for stability, binding and regulating movement of molecules within the structure.

cartilage behaviours

forces at joint surface may vary from almost 0 to more than ten times bodyweight. the response of articular cartilage to load is viscoelastic. creep and stress relaxation.

viscoelastic creep

a slow time-dependant progressively increasing deformation that follows a rapid initial deformation. the compressive viscoelastic behaviour is primarily caused by the flow of interstitial fluid and the frictional drag associated with the flow.

stress relaxation

a constant deformation with a rapid, high initial stress followed by a slow, progressive decreasing stress required to maintain deformation.

permeability of articular cartilage

porous (the ability for air or fluid to pass through a material). permeability (the ease in which a fluid can flow through a porous material). articular cartilage is porous but has very low permeability.