Arthritis and IJD Flashcards
What is arthritis?
Any disorder that affects joints with symptoms of pain and swelling
What is the difference between hyaline, elastic and fibrocartilage?
Hyaline cartilage provides a smooth surface for gliding action at joints
Elastic cartilage is flexible
Fibrocartilage resists strong forces of compression and tension.
What is the superficial zone of the osteochondral unit?
CLosest to the articular cartilage, the superficial zone is made up of type 2 collagen parallel to the joint surface and flattened chondrocytes.
HIgh conc. collagen low conc. protoglycans.
Has the highest water content.
What is the middle zone of the osteochondral unit?
Thickest layer predominantly spheroid cells embedded in the ECM. Large diameter collagen fibres are arranged obliquely.
Higher conc. of protoglycans.
Provides transition between shearing force of superficial layer and compressive force on deeper layers.
What is the deep zone of the osteochondral unit?
Lowest cell density with spheroid chondrocytes perpendicular to the surface.
High largest diameter collagen fibers and highest PG content.
Perpendicular arrangement of collagen fibers distributes the load and resists compression.
What is the tide mark of the osteochondral unit?
Boundary between uncalcified and calcified cartilage, free of cells, that progresses towards the surface with age.
What is the calcified cartilage zone of the osteochondral unit?
Anchored to subchondral bone by hydroxyapatite crystals, provides a barrier to diffusion from blood vessels supplying the bone.
What is the cell and matrix composition of cartilage?
Cells = chondrocytes inside acuna
Matrix = Ground substance and fibres
What are the ground substance and fibres of the cartilage matrix?
ground substance = hyaluronic acid, chondroitin and keratin sulphate
Fibres = types 2 collagen and elastin.
How are cells in the cartilage supplied?
Supplied by diffusion, fluid flow generated by compression or articular and flexion of elastic cartilage.
Explains poor regenerative capacity.
How do superficial articular cartilage lacerations heal?
Little to no ability to heal due to avascularity, so no stem cells available for new cartilage formation. Instead, filling of defect relies on chondrocyte proliferation.
How do deep articular cartilage lacerations heal?
If crosses the tidemark:
Deep enough to involve subchondral bone, which is vascular, hence allows hematoma to form bring influx of cells. No hyaline cartilage formed, new fibrocartilage formed from undifferentiated marrow mesenchymal cells.
What is the clinical relevance of deep articular cartilage laceration healing?
Arthroscopic operation of micro fracture treats small areas of full cartilage loss by creating holes in subchondral bone so that a fibrocartilage scar is produced. Only temporary and for very young patients with bad arthritis.
how does articular cartilage respond to normal physiological stress?
Responds in anabolic way, stimulates matrix synthesis and inhibits chondrolysis.
How does articular cartilage respond to the stress of moderate running?
Increased cartilage thickness and proteoglycan content.
How does articular cartilage respond to excess stress?
Suppressed matrix synthesis and promotes chondrolysis.
How does articular cartilage respond to immobilization?
Cartilage thinning and softening with proteoglycan loss.
how does cartilage change with aging compared to OA?
In aging the water content is decreased making collagen brittle.
In OA water content is increased making cartilage more susceptible to tear and injuries.
What is Erythema?
Swelling and redness around a joint.
What is podagra?
Exacerbation of gout at greater toe MTP joint.
What is cellulitis?
Infection of the skin and subcutaneous fat most commonly by staphylococcal and streptococcal species.
How are chondrocytes affected by infection?
Chondrocytes are fragile with infections as bacterial toxins released cause chondrocyte death which can rapidly destroy the joint.
What is an abscess? How do you treat it?
A confined infection often with puss under pressure causing pain. Does Not respond to abx very well as lack of penetration into joint cavity.
Incision and drainage.
What the timeframe for acute monoarthritis history?
Inflammation of a single joint present for less than 2/52 however acute presentation typically lasting 24/48 hours before presentation.
acronym for differential of acute monoarthritis?
GRASP the differential:
Gout
Reactive
Autoimmune/arthritic
Septic
Pseudogout