Osteoarthritis Flashcards
Osteoarthritis
Chronic irreversible degenerative disease of articular cartilage
Common morbidity in elderly
Most frequent reason for restricted physical activity
Not inevitable and does not affect all people
Primary and secondary OA
Primary most common form
Found mainly in knee joint
Rare in people under 40
Secondary OA is often caused by trauma and can occur in any joint
Cause of OA
50% of variation in susceptibility explained by genetic factors, 50% by environmental factors
Loss of balance between anabolic and catabolic processes
Positive correlation with BMI but not necessarily due to weight. May be inflammatory response (adipocytes)
Cartilage
Aneural (cannot feel) Avascular (no blood supply) Sparsely populated with cells Mostly water (75%) and collagen II, large and small proteoglycans Aggrecan is large PG
Function of cartilage
No weight on cartilage when sat down Weight increases and water is squeezed out Aggrecan sucks water back in Water required for cartilage resilience Loss of aggrecan associated with OA
MMPs and aggrecanase
Matrix metalloproteinases and aggrecanase attack aggrecan and collagen
Breakdown normally balanced by resynthesis
Meniscus
Rests between tibial plateau and femoral condyl
Involved in load transmission, shock absorption and lubrication
Meniscal damage correlated with increased OA incidence
Damage identified in 60% of older humans
Inflammatory balance
Pro-inflammatory IL-1 and TNF-alpha promote catabolic and inhibit anabolic processes (promote breakdown)
Anti-inflammatory IL-4, 10 and 13 inhibit pro-inflammatory cytokines and reduce protease production. Increase tissue inhibitors of metalloproteinase (TIMP)
OA treatment
Dealing with symptoms but not curing
Anti-inflammatories
Joint replacement surgery
Neutralisation of IL-10 and TNF-alpha is emerging approach.
