2.5 Cartilage Ageing Flashcards
Cartilage review
Cartilage is made up of specialized cells called chondrocytes. These chondrocytes produce large amounts of extracellular matrix composed of collagen fibres (mostly collagen type II), proteoglycans (mostly aggrecan), and elastin fibers.
- Proteoglycans are CHARGED molecules
- This draws cations (e.g., sodium) into the cartillage
- Water follows this salt gradient and enters the cartilage - cartilage swells
- The cartilage does not burst, as the collagen type II fibers resist this swelling
Much like a balloon filled with water, you can compress it in any direction and it will return to its original shape.
Cartilage is avascular and aneural. Condrocytes maintain the cartilage.
NOTE: cartilage does not turn into bone, however it does act as a scaffold for bone growth.
What is the TLDR of the cartilage ageing lecture?
Cartilage ageing is complex, but we know that OA is NOT an inevitable consequence of aging. Instead, aging increases the risk of OA.
OA (synonymous with DJD) is not well defined: it is a group of disorders with a common end stage - progressive and permanent deterioration of articular cartilage. We know that its progression is strongly influenced by ageing
there is:
- idiopathic OA: etiology is highly debated (age, mechanical overuse, and/or genetics)
- secondary OA: explained by known medical condition or specific cause (obesity, trauma, OCD, etc.)
both involve a homeostatic imbalance: anabolism < catabolism; this coupled with poor regenerative capacity (avascular) leads to the progression of OA
Important facts about OA in the horse, dog, and cat:
Horse:
- OA is the most common spontaneous joint disease in horses
- can develop in young horses and foals, but also compounded by age (Mangalarga Marchador) foals predisposed
- OA exacerbated by intense exercise
Dog:
- common in greyhounds and large/giant breeds
- 20% adults (>1y), 80% geriatric (>8y)
Cat:
- common radiographic finding in older cats
- likely underestimated
