Peggers Super Summaries – Basic Sciences Bone
Articular Cartilage Overview
ZONES – need to be able to draw
1. Lamina
2. Superficial
3. Middle
4. Deep
5. Tide mark – between calcified and non calcified cartilage
6. Calcified
CONTAINS
 Chondrocytes
 Extracellular matrix
o Water – 75%
o Collage type 2 - 10-20%
o Proteoglycan – 10-15% - need to be able to draw
FUNCTION
 Joint lubrication
 Shock absorption
LOADING
 Increase creep to equilibrium
 Cartilage needs to be loaded to filter water and nutrients
Articular Cartilage
OVERVIEW
 Avascular aneural alymphatic
CONTENTS
 ECM
o 75% water
 Type 2 collagen 60% dry weight
 Proteoglycans
 Aggrecans
 Hyaluronan
 Cells
o Chondrocytes 5%
Peggers Super Summaries – Basic Sciences Bone
LAYERS
 Superficial zone
o Highest water and collagen content lamina splendens
 Transitional
o Prosteoglycans
 Radial
o Perpendicular collagen
 Tidemark
 Calcified
o Hydroxyapatite crystals anchor
collagen to bone
o Type 10 collagen
COLLAGEN
 Formation
o mRNA helps modify polypeptide chains
o Golgi apparatus packs pro collagen and secretes into ECM
o Crosslinking of pro collagen forms collagen
 Types
o 2 collagen – 90% of cartilage
o 6 collagen – helps shear increases in OA
o 9 collagen – forms collagen PG complexes
o 11 – collagen regulates diameter of fibrils
ULTRASTRUCTURE
Peggers Super Summaries – Basic Sciences Bone
FUNCTION
 Biomechanics
o Biphasic and Anisotrophic – different mechanical properties
depending on load direction
 Viscoelastic undergoing creep
 Stress relaxation decreases stress with constant load
 Lubrication
o Boundary – mono-layer on surface
o Fluid film – thin layer increasing separation
OSTEOARTHRITIS CHANGES
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
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Increase water content up to 90%
Disruption of collagen-proteoglycan matrix
Increase chondroitin/karatin sulphate ratio
Chondrocytes increase in size and decrease in number
Collagen unchanged
TREATMENT
 Non operative
o Physiotherapy to maintain ROM, muscle and diffusion of synovial
fluid
o Oral glucosamine
o Intra-articular injection LEOPOLD et al 2003 no difference between
hyaluronic and steroids
 Operative
o Microfracture – for fibrocartilage formation
o Autograft (mosaicplasty taking cartilage from non WB area)
o Allograft from stem cells and GF
 FGF
 IGF1
 BMPs
 PGDF