Joint Pathology Flashcards
What type of collagen makes up articular cartilage? Which type of nerve innervates it?
- type II collagen
- lacks nerve endings! (therefore pathology of just the articular cartilage will not be painful)
What is degenerative joint disease? What are the three main risk factors? Is it mainly systemic or localized?
- osteoarthritis
- progressive deterioration of articular cartilage due to wear and tear
- risk factors: old age, obesity, trauma
- not entirely systemic; usually affects hip, lumbar spine, knees, and the DIP and PIP joints of fingers
How do patients with degenerative joint disease typically present? What are some complications?
- patients are usually 65+ and complain of joint stiffness in the morning that WORSENS and becomes painful during the day with use
- (joint stiffness that improves with use indicates rheumatoid arthritis)
- when the cartilage wears away and bone rubs against bone, we get eburnation (polishing) of the subchondral bone and osteophyte (bony outgrowth/swelling) formation
What is rheumatoid arthritis? What is the hallmark feature of this disease? Is it mainly systemic or localized?
- a chronic, systemic autoimmune disease
- hallmark: synovitis, resulting in pannus formation (inflamed granulation tissue)
- although systemic, it mainly affects the wrists, elbows, ankles, knees, PIP and MCP joints of fingers (bilateral, symmetrical involvement)
- the DIPs are usually spared
How do patients with rheumatoid arthritis typically present?
- patients are usually between 40 and 60 and complain of symmetrical joint stiffness in the morning that IMPROVES with activity
- (movement squeezes the inflammatory debris out of the joint, relieving some of the pressure and pain)
- (joint stiffness that worsens as the day goes on indicates degenerative joint disease)
- systemic symptoms also present (fever, malaise, etc.)
What are some symptoms and complications of rheumatoid arthritis?
- ankylosis (fusion) of the affected joints, osteopenia, baker cyst, vasculitis, fever, malaise, weight loss (don’t forget it’s a systemic disease)
- complications: anemia and secondary amyloidosis
- the ankylosis is due to the contracting nature of the myofibrils present in the pannus/inflamed granulation tissue
What would you expect to find in the serum of a patient with rheumatoid arthritis? In the synovial fluid?
- serum: IgM and IgA antibodies against the Fc portion of IgG (this is called rheumatoid factor) + anti-cyclic citrullinated peptide antibodies (anti-CCPs, ACPAs)
- 50-80% of patients will have one or the other or both
- (anti-CCPs are more specific than RF for RA)
- synovial fluid: large amounts of neutrophils and proteins
What percentage of rheumatoid arthritis risk is associated with genetics? Which specific gene?
- about 50% is due to genetics
- HLA-DR4
- (there is a shared epitope in patients with RA at HLA-DR beta 1 at residues 70-74, with a positively charged residue at 71)
What is seronegative spondyloarthropathy? Which gene is is associated with? What are the three major types?
- diseases that affect the axial skeleton and sacroiliac joints (“spondylo”) and that lack rheumatoid factor (hence the seronegative)
- associated with HLA-B27
- an “auto-inflammatory” disease rather than an auto-immune one
- ankylosing spondyloarthritis, Reitier syndrome (reactive arthritis), and psoriatic arthritis (also, colitic arthritis and acute anterior uveitis)
Which joints are usually involved in ankylosing spondyloarthritis? What happens to these joints over time? What can patients present with?
- (a type of seronegative spondlyoarthropathy)
- involves the sacroiliac joints and spine
- the vertebrae fuse over time (ankylosis), giving rise to “bamboo spine”
- patients may present with lower back pain, unilateral uveitis, enthesitis, and aortitis (aortitis can increase the risk of aneurysm; an aneurysm at this location increases the risk for aortic regurgitation)
What is Reiter syndrome? When is classically seen?
- (a type of seronegative spondlyoarthropathy)
- a combo of arthritis, urethritis, and conjunctivitis (“can’t see, can’t pee, can’t climb a tree”)
- classically arises in young male adults after a GIT (Campylobacter jejuni, salmonella, shigella, etc.) or chlamydia (C. trachomatis) infection
- AKA ‘reactive arthritis’
- can be due to an inflammatory reaction in response to infection at a distant site (so the organism is actually in the joint)
What is psoriatic arthritis? What is the most severe form known as?
- (a type of seronegative spondlyoarthropathy)
- arthritis of axial and peripheral joints, especially the DIP joints (results in nail changes, very common) and feet
- this is a complication of psoriasis (10% of cases)
- most severe and progressive form is arthritis mutilans
What is the most common agent of infectious arthritis in infants? In children? adults?
- infants and very young children: S. aureus, group B strep, H. influenzae
- young adults: N. gonorrhoeae (most common), S. aureus
- older adults: S. aureus
- (the agent is usually bacterial; S.aureus is the most common cause; septic arthritis)
- usually due to hematogenous or traumatic route
How do patients with infectious arthritis typically present?
- with a warm, erythematous painful joint that is limited in motion (onset is sudden)
- (usually involves a single joint - 90% of cases involve the knee)
- systemic signs of infection may also be present (fever, increased WBC, increased ESR)
What is gout? What is it due to? Which joint is most commonly affected?
- deposition of MSU (monosodium urate) crystals in tissues (especially in the joints)
- due to hyperuricemia (elevated uric acid levels)
- very commonly affects the podagra (the MTP joint of the big toe)
