Articular cartilage Flashcards
Composition of articular (Hyaline) cartilage? (5)
- Water
- PG
- Collagen 2
- Cells
- Non collagenous proteins
2 Functions of type 2 collagen?
- Cartilagenous framework
2. Tensile strength
Water makes up what percentage of articular cartilage?
65-80%
Function of the PG? (2)
Attract water Compressive strength (aggrecan)
What do the chondrocytes produce? (3)
Collagen
PG
Enzymes
Name the 3 zones of articular cartilage?
Superficial
Intermediate
Deep
Tidemark
Features of the superficial zone of cartilage? (3)
- Collagen arranged parallel (slip and slide)
- Lowest amount of PG
- Highest concentration of collagen
Features of the intermediate zone? (3)
- Oblique/disorganised fibres
- higher PG content
- Thickest layer with round chondrocytes
Features of the deep Layer/ Basal layer? (3)
- Collagen fibres arranged perpinduclar (squash zone)
- Highest amount of PG
- Round chondrocytes arranged in columns
What is the tidemark?
Deep to basal layer and separates articular cartilage from deeper cartilage (remnant of endochondral ossification)
2 sources of nourishment for articular cartilage?
- From synovial fluid
2. Subchondral bone
By which process does cartilage produce ATP>
Glycolysis
Response of articular cartilage to physiological (normal) stress? (2)
Stimulates matrix synthesis
Inhibits chondrolysis
Repetitive loading ie mod running leads to what 2 changes?
Increase in cartilage thickness
Change in PG content
Forms of joint lubrication? (5)
- Elastohydrodynamic
- Boundary (Slippery surfaces) (Main)
- Boosted (fluid entrapment)
- Hydrodynamic
- Weeping
Mechanisms of wear? (5)
- Adhesion
- Abrasion
- Third body
- Fatigue
- Transfer
What happens to the composition of cartilage with ageing?
- Water
- Modulus
- Chondrocytes
- GAG
- PG
- Collagen
- AGE
- Decreased
- Increased (less elastic)
- Less but larger
- Increased keratin:chondroitin ratio
- Increased decorin, decreased size
- Increased cross linking/brittleness
- Increased
What happens to the composition of cartilage with OA?
- Water
- Modulus
- Chondrocytes
- GAG
- PG
- Collagen
- AGE
- Increased
- Decreased
- Cells cluster
- Increased chondroitin:keratin ration
- PG unbound from hyaloronate
- Disorganised collagen
- Accumulation thought to lead to OA in knee and ankle
Healing of deep lacerations in cartilage? Through the tidemark
Leads to fibrocartilage healing
Heals with Type 1 collagen
Healing of superficial lacerations?
Chondrocyte proliferation but no healing (avascular)
Can be treated with abrasive arthroplasty
