pathology Flashcards
what is osteoarthritis
Most common form of joint disease. Results from damage to articular cartilage induced by an interaction of genetic, metabolic and biochemical factor, leading to an inflammatory response affecting cartilage, subchondral bone, ligaments, menisci, synovium and capsules
what is the pathogenesis of osteoarthritis
- ageing and biochemical stress
- primary = insidious, no overt cause, age related
- secondary = predisposing condition, excess/inappropriate weight bearing, deformity, injury, systemic conditions
what is cartilage made of
water, organic extracellular matrix components, mainly type 2 collagen and aggrecan or other proteoglycans
what is the pathogenesis of osteoarthritis
structural changes include surface fibrillation and ulceration with loss of cartilage that exposes underlying bone to stress, producing microfractures and cysts leading to abnormal sclerotic subchondral bone and overgrowths at joint margins, called osteophytes
what mechanisms can cause osteoarthritis
- abnormal stress and loading
- obesity
- matrix degradation
- tissue inhibitors metalloproteinases
- osteoprotegerin, RANK and RANK ligand
- aggrecanase
- inflammatory mediator release
- growth factors
- cell derived and/or cartilage breakdown products
what are clinical features of oesteoarthritis
Causes mechanical pain with movement and/or loss of function
Early OA is rarely symptomatic unless accompanied by a joint effusion while advanced radiological and pathological OA is not always symptomatic
what are symptoms of osteoarthritis
- joint pain with movement and/or weight bearing
- short lived morning joint stiffness
- functional limitations
pathogenically what are the features of osteoarthritis
early
- damage to cartilage
- clusters of chondrocytes
- small fissures in cartilage
- fibrillation
late
- cartilage is completely worn away- bone on bone
- subchondral cysts
- surface becomes “polished” - eburnation
- remodelling to cope with stress
- formation of osteocytes
what are signs of osteoarthritis
crepitus restricted movement bony enlargement joint effusion and variable levels of inflammation bony instability and muscle wasting
what characterises inflammatory arthritis
synovial inflammation
what are the 3 main subgroups of inflammatory arthritis
rheumatoid arthritis
spondyloarthritis
crystal arthritis
what are tests for osteoarthritis
Plain radiographs show: Loss of joint space, Osteophytes, Subarticular and subchonral cysts
CRP might be slightly elevated
what is rheumatoid arthritis
A chronic systemic inflammatory disease, characterised by symmetrical, deforming, peripheral polyarthritis
what does rheumatoid arthritis present with
- symmetrical swollen, painful, stiff small joints of hands and feet worse in the morning
what are early signs of rheumatoid arthritis
- inflammation, symmetrical
- look for tenosynovitis or bursitis
- no joint damage
what are later signs of rheumatoid arthritis
- joint damage
- deformity
- ulnar deviation and flexion of the wrists and fingers
- boutonnieres and swan neck deformities of fingers or z deformity of thumbs
what are clinical correlations of rheumatic arthritis
- vague systemic features: malaise, fever
- generalised musculoskeletal pain
- symmetrical: swollen, warm, painful, limited movement in the morning and after inactivity
- small joint involvement before big joint involvement
what is the progression of rheumatic arthritis
- Joint swelling. Decreased range of movement. Joint fusion (ankylosis)
- Associated involvement of tendons and ligaments
- Unstable, very limited ROM
- Synovial herniation - cysts
- Joint effusion
what is the immunology of rheumatoid arthritis
- Autoimmune inflammation triggered
- CD4+T helper cells may be critical
- Cytokine production results from initiation of inflammation:
IFNg activates macrophages and synovial cells
IL-17 recruits neutrophils
TNF and IL-1 stimulate production of proteases from synoviam
RANKL expressed on activated T cells stimulates bone reabsorption
what is panes formation
type of extra growth in your joints that can cause pain, swelling, and damage to your bones, cartilage, and other tissue
what are some extra-articular manifestations of rheumatic arthritis
- nodules: elbows, lungs, cardiac…
- small vessel vasculitis
- ocular: keratoconjunctivitis
- lungs: pleural disease, interstitial fibrosis, bronchiolitis
- cardiac: pericarditis
what is crystal arthropathies: gout
typically presents with monoarthropathy with severe joint inflammation. >50% occur in the metatarsophalangeal joint of the big toe
how is hyperurucaemia synthesised
From purine catabolism
Reflects abnormal purine metabolism
how is hyperurucaemia excreted
Renal filtration
Reabsorbed in proximal tubule
Limited excretion from distil tubule
what can cause hyperuraeceamia
- usually idiopathic
- known enzyme defect - HGPRT deficiency
- increased cell turnover
what are clinical manifestations of gout
- unclear how crystals end up in joint
- causes secondary degenerative changes in joint
