OA Flashcards
What are the risk factors for OA?
- obesity
- occupation, sports, trauma
- genetics, age, gender (non-modifiable)
What is the prevalence of osteoporosis in Canadians?
1 in 10 (3 million)
Why are females more likely to get OA?
- because of pregnancy
- babies suck the calcium out of the bones
What joints are affected from most to least?
- spine
- hip
- hand
- knee
What systemic factors affect joint vulnerability contribute to OA progression?
- increased age
- female gender
- racial/ethnic factors
- genetic susceptibility
- nutritional factors
What are some intrinsic joint vulnerabilities that can contribute to OA?
- previous damage
- bridging muscle weakness
- increasing bone density
- malalignment
- proprioceptive deficiencies
What is primary OA?
- idiopathic cause
- localized OA = 1-2 joints affected
- generalized OA = 3+ joint affected
What is secondary OA?
- known cause
- RA
- trauma
- disease
- obesity
Cartilage is made by ______________.
chondrocytes
What are the 2 macromolecules made by chondrocytes?
Type II collagen - provides tensile strength
Aggrecan - negatively change glycosamioglycans
- blocks the inactive DDR-2 receptor
- electrostatic repulsion gives cartilage in compressive stiffness
What are the degrading enzymes produced by chondrocytes?
Matrix metalloproteinases 13 - breaks down type II collagen
ADAMTS 4 and 5 - break down aggrecan
We used to think that OA was just a “wear and tear” disease.
We now know:
- mechanical wear/trauma acts as catalyst starting disease process
- actually cartilage damage is a chemically-mediated disease process
- complex cellular mechanisms cause increase catabolic and stunted anabolic mechanisms of cartilage
Describe the cartilage breakdown cycle in OA.
- Cartilage damage stimulates chondrocytes activity
- Chondrocytes produce ADAMTS-5 which breaks down aggrecan
- DDR-2 receptor is now exposed and activates MMP-13
- MMP-13 and activated DDR-2 begins destroying collagen
- Destruction of collagen signals for more ADAMTS-5 to be made
Will increased levels of MMP-13 destroy collagen?
No, not unless the DDR-2 receptor is exposed from aggrecan degradation
What are the pro-inflammatory cytokines associated with OA?
IL-1
IL-6
TNF alpha
IF gamma
