Found in intervertebral discs and tendon-ligament insertions
Elastic Cartilage
Type 2 Collagen
Found in ear auricle, epiglottis, and meniscus
β£
Function of cartilage?
Lubrication - extremely low coefficient of friction (0.002), 30 times better than arthroplasty
Participates in fluid film lubrication through boosted and weeping mechanisms
Shock absorption
β£
Properties of cartilage?
Avascular, aneural, alymphatic, and non-immunogenic
β£
DRAW structure of cartilage.
"Arcades of Beninghoff"
Zone 1 = lamina splendens: Parallel fibers with 1-3 cell-thick layer of flattened chondrocytes. Has macrophage-like features, high water content. Collagen exceeds proteoglycan to resist shear stresses
Zone 2 = Oblique fibers
Zone 3 = Vertical. Proteoglycan greatly exceeds collagen (for compression), minimal water content, abundant chondrocytes
Tidemark - Cell-free zone marking boundary between uncalcified and calcified cartilage
Contains hyaluronic acid, link proteins, core protein, chondroitin and keratan sulfate (Remember as KC: K is nearer to HA)
Withstands COMPRESSION forces
β£
Difference between knee, ankle, and shoulder cartilage?
Shoulder - Thicker superficial layer for shear stress resistance (thinner transitional and radial layers)
Ankle - Thicker radial/deep layer for compressive stress resistance
β£
What is the difference in biomechanical properties of fibrocartilage and hyaline cartilage? What are the implications?
Fibrocartilage shows poorer biomechanical properties - exhibits less stress relaxation and creep
This results in greater force transmission to the subchondral bone, leading to subchondral bone damage
β£
What is synovium?
Composed of 2 layers
Intimal lining: 2-3 cell layers deep, contains synovial cells that produce synovial fluid. Has no basement membrane.
Subintima lining: Contains fibroblasts, blood vessels, immune cells, and macrophages. Plays an important role in inflammatory arthritis
β£
What are the cells in synovium and their function?
Type A = macrophages
Type B = fibroblast-like cells that produce synovial fluid
Type C = intermediate cells
β£
What is synovial fluid and its 3 characteristics?
What it is? A dialysate of blood plasma without clotting factors, RBC or Hb. Contains hyaluronate and plasma proteins
β£
3 Characteristics
Non-newtonian: shear stress not proportionate to shear rate - leads to pseudoplasticity and thixotropicity
Pseudoplastic: Less viscous with increased rate; undergoes shear thinning (becomes less viscous as movement increases)
Due to alignment of HA molecules as shear rate increases
Thixotropic: Less viscous with time at constant shear rate; undergoes shear thinning with time at constant shear rate (e.g., when walking at constant speed, fluid becomes less viscous over time)
β£
What happens to synovial fluid in RA? Difference in OA?
Enzymatic degradation of Hyaluronic Acid leads to loss of non-newtonian properties, resulting in less effective lubrication
In contrast, in OA, HA remains intact and maintains its non-newtonian properties
π
The beginning of wisdom is this: Get wisdom, and whatever you get, get insight. Proverbs 4:7