Topic 5: Joint Disease Flashcards
(34 cards)
What are some functions of synoviocytes?
- phagocytose dead/dying tissue
- secrete synovial fluid
- maintain homeostasis within joint
What are some functions of the synovial membrane?
- produce lubricin and hyaluronic acid (maintains integrity of AC)
- nutrient exchange
What are the functions of AC?
- frictionless motion
- even distribution of joint load
- disperse energy from loading
What are the properties of AC?
- avascular –> no inflammatory response
- aneural –> no source of pain
- alymphatic
- hypocellular –> low density of chondrocytes
What type of inflammation is OA?
dysregulated para-inflammation
What is the onset age of OA?
50-60yrs
What types of problems occur as a result of OA?
synovitis, alterations of joint capsule, degeneration of menisci and ligaments, AC breakdown, osteophyte formation, subchondral bone oedema + swelling
Role of synovium in OA
- decreased levels of HA and lubricin
- decreased cartilage protecting factors and increased degradation factors
- synovial inflammation precedes structural changes
Role of AC in OA
- over-expression of degradation enzymes
- fibrillation
Role of biomechanical influences in OA
- mal-alignment: abnormal load distribution
- loss of mensical tissue: alterations in load transmission, increased peak load stresses
- cartilage lesions: exposure of sub-chondral bone
- joint instability and ligament laxity: increased translation
Role of obesity in OA
adipokines - pro-inflammatory
Role of age-related changes in OA
- increased SASP secretion
- oxidative stress/damage
- decreased growth factors
- increased AGE formation (advanced glycation end-product)
Inducers of OA
Endogenous
- cell-derived alarmins
- tissue-derived metabolites
- ECM-derived
- AGEs
Sensors of OA
PRRs
- osteocytes and chondrocytes in sub-chondral bone
- tissue-resident macrophages
- synoviocytes
- chondrocytes
Effectors of OA
- AC chondrocytes
- tissue-resident macrophages and mast cells
- fibroblasts in ligament capsule
- osteocytes and chondrocytes in sub-chondral bone
- synoviocytes
Clinical features of OA
- crepitus
- decreased muscle strength
- joint instability
- deformities - genu varus/valgum
- pain in joint
- loss of ROM
- joint enlargement
Pathology of OA
- cartilage loss - decreased matrix material produced
- cartilage softening –> cracking, flaking, fibrillation, fissuring –> exposure of subchondral bone –> eburnation
- sunchondral cysts
- local muscle weakness
What is the onset age of RA?
25-50 years
What is the gender bias of RA?
females 2.5:1
What is an antigen?
cause immune response to produce antibodies
What is an antibody?
immunoglobulins, specific, adaptive immune system
What is an auto-antigen?
endogenous, body attacks self
Aetiology of RA
- Rh factors produce (auto-antibodies that react with immunoglobulins)
- immune complexes lodge in walls of synovial joints and blood vessels and attract immune cells
Inducers of RA
- endogenous - genetic factors
- PAMPs and DAMPs - cell-derived alarmins (Rh factors), tissue-derived inducers, pathogen-derived alarmins
- exogenous: microbial (PAMPs, virulence factors), non-microbial (allergens, irritants)
