Pathoma - MSK - Joints Flashcards
Describe the basic premise behind osteoarthritis
Progressive degeneration of articular cartilage
Most often due to “wear and tear”
Major risk factors of osteoarthritis
Age (#1), obesity, trauma
Most commonly affected joints by osteoarthritis
Weight-bearing joints (hips, lower lumbar spine, knees)
DIPs and PIPs
Often asymmetric joint involvment
Describe progression of joint stiffness throughout the day in osteoarthritis
Joint stiffnes in the morning that worsens during the day
Clinical features of osteoarthritis
Osteophytes (bone spurs) - classically in DIP (Heberden nodes) and PIP (Bouchard nodes)
Joint space narrowing
Disruption of cartilage that lines the articular surface
Eburnation of the subchondral bone (polishing of bone from bone rubbing against bone)
Synovial fluid non-inflammatory (WBC < 2000)
Treatment of osteoarthritis
Acetaminophen (does not treat inflammation), NSAIDs, intra-articular glucocorticoids
Describe the basic premise behind rheumatoid arthritis as well as classic joint findings
Autoimmune disease leading to joint inflammation
Synovitis leads to formation of pannus (inflammed granulation tissue) - which causes:
- Joint fusion (ankylosis)
- Joint deviation
- Destruction of articular cartilage
Common associations/risk factors of rheumatoid arthritis
HLA-DR4
Female
Smoking
Rheumatoid factor
Inflammatory synovial fluid
What is rheumatoid factor?
IgM autoantibody aginst the Fc portion of IgG
Describe progression of joint stiffness throughout the day in rheumatoid arthriti
Morning stiffness that improves with activity
Most commonly affected joints in rheumatoid arthritis
PIPs, wrists (radial deviation), elbows, ankles, and knees
DIP is usually spared
Symmetric involvment
What are 3 characteristics of seronegative spondyloarthropathies?
Lack of rheumatoid factor (“seronegative”)
Axial skeleton involvment (“spondlyo-“)
HLA-B27 association
What are the seronegative spondyloarthritises?
PAIR:
Psoriatic arthritis
Ankylosing spondylitis
Inflammatory bowel disease (IBD)
Reactive arthritis (Reiter syndrome)
What joints are most often involved in psoriatic arthritis?
Axial and peripheral joints
DIPs of hands and feet are most commonly affected (“sausage fingers or toes”)
Joints most commonly affected in ankylosing spondylitis?
Sacroiliac joints and spine
Fusion of vertebrae = bamboo spine
Common extra-articular manifestation of ankylosing spondylitis
Uveitis and aortitis (weakened walls may lead to dilation and aortic regurgitation)
Think of pandas:
They eat bamboo - bamboo spine
Racoon eyes - uveitis
Clumsy climbing up weak trees causing branches to bend - aortitis (bent branch looks like aortic arch)
Classic triad of Reactive arthritis
Aka Reiter syndrome:
Can’t see, can’t pee, can’t climb a tree
Conjunctivitis, urethritis, arthritis
Most common infections that precede Reiter syndrome
Chlamydia or GI infections (Shigella, Salmonella, Yersinia, Campylobacter)
Most common causes of septic arthritis
N. gonorrhoeae - young adults; most common cause
Staph. Aureus - older children and adults; 2nd most common cause
Is most gout caused by underexcretion or overproduction of uric acid?
Under-excretion (90%) of patients
What are common causes of uric acid over-production?
Lesch-Nyhan syndrome - X-linked deficiency of HGPRT
Increased cell turnover - Leukemia, myeloproliferative disorders, tumor lysis syndrome
Why does alcohol precipitate gout attacks?
Alcohol competes with uric acid for kidney secretion
Describe gout crystals vs. Caclium pyrophosphate dihydrate (CPPD) crystals (aka pseudogout)
Gout crystals - needle-shaped crystals with negative birefringence under polarized light (yellow under parallel light, blue under perpindicular light)
CPPD crystals - rhomboid-shaped crystals with positive birefringence under polarized light (blue under parallel light)
