Joint Pathology Flashcards
Articular/hyaline cartilage is comprised of
chondrocytes (build and break down matrix), type II collagen (matrix) with GAGs, water (70% by weight)
What is the role of chondrocytes in articular cartilage?
build and break down matrix (collagen type II)
Deep in articular cartilage, collagen fibres are oriented __________ whereas close to the surface they are oriented ___________
perpendicular; parallel (holds everything together)
GAGs are _________ charged
negatively; they repel each other but are held together by collagen
Perfusion of articular cartilage occurs by
compression/decompression w/exercise bc it is avascular
Synovial capsule is comprised of
dense connective tissue
Synovium lines the
joint space, except where there is cartilage; attached to the capsule
Synovial fluid is made up of
plasma filtrate with extra slippery hyaluronic acid produced by the synovium
T/F Synovium is an epithelium
False; it has no epithelial cells, a BM, or desmosomes, etc. It’s more like a dense layer of cellular connective tissue allowing for easy diffusion
Type A synoviocytes
macrophage-like; phagocytes that set off inflammatory reactions
Type B synoviocytes
fibroblast-like; produce hyaluronic acid for lubrication
What is osteoarthritis?
Wear & Tear’ arthritis; degeneration of the joint cartilage that occurs in hard-working joints: hips, knees, hands; or previously injured joints
What causes osteoarthritis?
‘Focal disease of joint cartilage causing it to break down; involves enzymes (collagenases, MMPs) activated from cartilage (layed down by chondrocytes) and cytokines (IL-1) from synovial cells
What are the S&S of osteoarthritis?
Deep achy pain in joints that gets worse with use; reduced ROM of joints; crepitus; osteophytes (Hebbidins nodes at DIPs and Bouchard’s nodes at PIPs); slow, insidious onset; no systemic symptoms
What is the tx for OA?
physio, pain relief & anti-inflams, joint replacement
What is rheumatoid arthritis?
Autoimmune inflammatory arthritis with systemic involvement - can also affect skin, blood vessels, heart, lungs; progressive disease (good chance of being disabled if un-tx for 10yrs +)
What is the cause of RA?
Autoimmune reaction to an unknown antigen; perhaps a viral infection; in genetically suceptible individuals (MHC alleles)
What are the S&S of RA?
Often polyarthritis starts symmetrically in small joints of hands and/or feet (oligo/few or polyarthritis/lot) and progresses to destroy them - DIPs often spared; warm, swollen, tender joints; swelling is rubbery/doughy due to pannus and mononuclear infiltrate; morning stiffness for 1hr+ that eases with activity; systemic symptoms like rheumatoid nodules usually in places of friction eg elbows, fever (cytokines), weight loss, anaemia; destruction and deformity of joints (eg swan neck deformity with fixed hyperextension of PIPs and fixed flexion of DIPs)
What is the tx of RA?
Immune-modulating disease-modifying anti-rheumatic drugs
What is gout?
metabolic disease (not a pimary inflammatory disorder) caused by too much uric acid in the body; acute inflammation in a single joint due to crystallization of uric acid (eg big toe = podagra)
What causes gout?
high uric acid levels; Inflammatory reaction to uric acid cystals precipitating and crystallizing in joints especially those with low pH, fibrous tissue and nucleating agents that are cooler and poorly perfused, especially following alcohol, dehydration, or high-purine diet; crystals activate inflammatory cells, synovial cells, and complement; can progress to chronic, disabling tophaceous gout if left untreated involving multiple joints and recurrent inflammation that can cause damage and pannus formation, as well as tophi (urate deposition in other soft tissues, articular cartilage, capsule, etc.), nephropathy, and kidney stones
What are the S&S of gout?
Can be asymptomatic for 20-30 years then often starts in big toe; acutely inflammed joint that is very painful, often not accompanied by systemic symptoms like fever (would be cause for concern of tophi infection or septic arthritis); may present with tophi if chronic; spontaneous onset of excruciating pain, swelling, heat, and redness, classically in the big toe in early morning
What are the risk factors for gout?
Obesity, rich diet (high purines), high alcohol intake, hypertension, metabolic syndrome; associated with risk of T2DM/insulin resistance, hypertension, heart disease; prevalence is higher in men and increases with age and post-menopause; abnonormalities in uric acid metabolism - increased intake or production of uric acid or reduced excretion through the kidneys; genetics and ethnicity (pacific islanders)
What is the tx for gout?
Anti-inflams, urate-lowering therapy, lifestyle changes