tutorial 2 - bone & joint disease Flashcards
What are the 3 key components of a normal joint?
Cartilage, synovium, supporting ligaments/joint capsule
What are the 4 key causes of painful joints (arthritis)?
- Gout/gouty arthritis
- Osteoarthritis
- Rheumatoid Arthritis
- Septic Arthrtis
What is the most common type of joint disease?
Osteoarthritis
What has the strongest association with OA?
Advancing age
Which joints are most affected by osteoarthritis?
weight bearing joints - knee, hips, lumbar spine, etc.
What is the pathogenesis of osteoarthritis?
Altered chondrocyte homeostasis with overactivity of degrading enzymes. This leads to a decrease in proteoglycans and type II collagen, resulting in degradation of cartilage
What are the effects of OA on the joint space, as seen on xray?
Narrowing of the joint space
What are the 5 key pathological changes seen with osteoarthritis?
- Fibrillation of cartilage
- eburnation (ivory bone)
- sclerosis
- subcondral cysts
- Osteophytes
What is cartilage fibrillation?
Process that occurs in OA where chondrocytes proliferate and then die causing fraying of the cartilage surface
What is eburnation?
In OA, a bone end that is devoid of cartilage getting polished by the grinding action of bone on bone.
What is bone sclerosis in OA?
When bone underneath areas of lost cartilage become more dense, likely to compensate for changes in weight distribution
What are subchondral cysts?
In OA, small cysts that form in the head of the bone when fluid is forces into cracks in the bony surface and become surrounded by a fibrous capsule.
What are osteophytes?
Mushroom shaped bony outgrowths that develop at the margins of articulating bones in OA
What is the name for osteophytes of the distal interphalangeal joints in osteoarthritis?
Heberden nodes
What is the name for osteophytes of the proximal interphalangeal joints in osteoarthritis?
Bouchard nodes
What are the treatments for OA?
Physiotherapy, analgesia, modified activity, joint replacement
Which joints tend to be involved in rheumatoid arthritis?
small joints of hands, feet, wrists, elbows, ankles, knees
What are the 2 most common antibodies present in patients with RA?
Rheumatic Factor (RF), Anti Cyclic Citrullinated Peptides (Anti CCPs)
What gene is related to susceptibility to RA?
HLA (human leukocyte antigen) gene
What environmental factors can exacerbate or initiate the autoimmune response in rheumatoid arthritis?
Smoking, infection
What activates the initial inflammatory synovitis in patients with RA?
Antigen bound to MHC is presented to T helper cells, which produced cytokines to recruit macrophages and plasma cells to the synovium
What are the role of activated and lymphocytes and macrophages in the pathogenesis of RA?
They produce TNF which stimulates proliferation of fibroblasts, synovial cells and chondrocytes which proliferate and secrete proteolytic enzymes that destroy cartilage. Also, T cells activated osteoclasts leading to bone resorption
What is the term for the chronically inflamed, thickened synvovium in RA?
Pannus
What cells activated osteoclasts triggering bone resorption in RA?
T cells
What is the role of citrullination of proteins in the RA pathogenesis?
Proteins are citrullinated, making them foreign to the immune system, meaning they are attacked by lymphocytes.
What is the role of TNF in RA pathogenesis?
It is released from activated macrophages and stimulates chondrocytes and synovial cells to secrete proteases which destroy cartilage
What are the components of the pannus?
thickened synovium, granulation tissue, fibrosis, inflammatory cells
What is the term for bone end fusion, as seen in rheumatoid arthritis?
Ankylosis
What are some of the systemic complications of RA?
anaemia of chronic inflammation, fatigue, weight loss, subcutaneous rheumatoid nodules
What are the typical hand deformities seen in RA?
Radial deviation of wrist, ulnar deviation of the fingers,
What finger joint deformities are seen in RA?
Boutonnière deformity, Swan neck deformity
What are the classes of pharmacological RA treatments?
NSAIDs, DMARDs, glucocorticoids
What is osteomyelitis?
Inflammation of the bone marrow
What is pyogenic osteomyelitis?
When a pyogenic bacteria infects the bone shaft resulting in pus production and increased pressure inside the bone.
What is the involucrum in osteomyelitis?
New bone laid down under the periosteum and over the dead bone underneath
What is the sequestrum in osteomyelitis?
Dead bone resulting from pressure in the marrow or loss of blood supply
What leukocyte will be prevelant in histology of osteomyelitis?
Neutrophils
What is gout?
Arthritis initiated by deposition of urate crystals within and around joints
What is primary gout?
Gout caused by excess uric acid of an unknown cause
What is secondary gout?
Gout caused by conditions that lead to increased production of uric acid or decreased excretion of uric acid
What is acute gout?
When urate crystals precipitate within the joint triggering an acute inflammatory reaction.
Why does gout usually occur in peripheral joints?
Because the synovial fluid has a lower temperature, making it easier for the crystals to precipitate
What joint is most commonly affected by gout?
First metatarsophalangeal joint (great toe)
What is the pathogenesis of chronic gout?
With repeated attacks of acute gout, urate crystals eventually deposit in the synovial membrane creating tophi. This triggers a chronic inflammatory reaction causing pannus formation and bone destruction.
What are the findings upon aspiration of synovial fluid in a patient with septic arthritis?
Cloudy, yellow, contains bacteria, neutrophils
