week 4: osteoarthritis Flashcards
define osteoarthritis
- progressive collection of pathological changes in a synovial joint
- often associated with wieght bearing/overused joints
obvious signs of OA
loss of articular cartiliage, pain, loss of ROM, and soft tissue defects, deformity
when is the peak onset of OA?
- peak onset is 50-60
- 9.3 % of the poulation have it
clinical signs of OA
- pain in affected joint
- stiffness after inactiivty
- joint enlargment
- limitied ROM
- muscle inhibition
- joint instability
- deformities
pathological signs of OA?
cartiliage loss
subchondral sclerosis
subchrondral cysts
synovitis and inflammation
osteophytes (excess bone growth)
local muscle weaknes and impairment
what are the 3 areas we see OA degradation?
cartiliage
bone
joint capsule and ligaments
how is cartiliage degraded?
- excess forces or normal forces applied to an inadequatly controlled joint leads to cartiliage loss
- leads to abnormal turnover and chrondocyte activity
- chrondocytes release cytokines that release damaging enzymes (MMP’s), leading to further degradation
-cartiliage leads to being composed of more water, degraded materials and less cells to maintain the tissue - can increase apoptosis, increased phagocytosis and cell mediators
end result:
- cartiliage softening
- crackling
- fibrilation
- pieces sloughing off
- bone starts to become articulating surface (eburntion)
how is bone affected
subchondral scelrosis (scarring)
- bone starts to become articulating surface
- causes microfractures in subchrondal bone (bone underneath cartiliage)
subchrondral cysts:
- synovial fluid goes into fractures causing synovial cysts
synovitis and inflammation:
- angeogenitis + fibroplasia (granulation tissue) invades synovium
development of osteophytes (excess bone growth)
- inflammatory stimmulation fo bone growth
- osteoblast actiivty is a side effect of enzymes
- can limit ROM and increase pain
tracbecular bone distibution of loading is affected
how ar joint capsule and ligaments affected?
- loss of caritilage decreases size of joint capsule
- ligaments become slack making joint unstable, and decreased control of joint
- can also lead to further abnormal forces being applied ot the joint
risk factors of OA
wieght:
- increases chance of OA
- eg. by 4x in knee if BMI is 30-35
obesity:
- changes in mechanical stress across joint
- joint alignment influences distribution of load
- on articular cartiliage
- on other tissues of wieght bearing joints
- leading to OA
ateology (casues)
primary:
- not known
- ageing
secondary:
- trauma
- anotomical
- inflammatoy
- nueropathic
- hameophillia
- heredity (collagen predisposition)
why do ppl experience nociception with OA
experience becuase of
- alteration in shape
- ostephytic growth
- joint instability
- loss of ROM
- mechanically sensitised nociceptors
nociception in their bone:
- high interosseous pressure in subchondral bone
- impaoired venous system
nociception due to inflammation/synovitis:
- chemical meidators sensitise nociceptive fibres in mild situations
- can be ongoin due to angiogenesis
where does swelling occur with OA
- bony swelling occurs at joint margin, due to cartiliage and bone outgrowths at joint margin
- may be synovitis (inflammation)
what is crepitis
- course crepitations
- due to roughening of joint surfaces, bone growth
- it is when the joint does not have smooth movement
treatments?
- pharma
- physio
pharma: paracetamol
physio: movement and excercise, surrounding joints by strong muscles