Joints Flashcards
What is a joint?
Connection between two bones
How do joints provide structural strength?
Solid joints are tightly connected (eg cranial sutures)
What are synovial joints?
They have a joint space to allow for motion
What is the articular surface of adjoining bones in a synovial joint made of?
hyaline cartilage (type II collagen) that is surrounded by a joint capsule
What facilitates smooth motion of the synovial joint?
Synovium lining the joint capsule secretes fluid rich in hyaluronic acid to lubricate the joint and facilitate smooth motion.
What is osteoarthritis?
Progressive degeneration of articular cartilage; most common type of arthritis
What is the most common type of arthritis?
osteoarthritis
What is osteoarthritis most often due to?
wear and tear
What is the major risk factor for osteoarthritis?
Age
In whom is osteoarthritis common?
after 60 years
In addition to age, what are some additional risk factors for osteoarthritis?
obesity and trauma.
What joints are affected by osteoarthritis?
a limited number of joints (oligoarticular); hips, lower lumbar spine, knees, and the distal interphalangeal joints (DIP) and proximal interphalangeal joints (PIP) of fingers are common sites
What is the classic presentation for osteoarthritis?
joint stiffness in the morning that worsens during the day
What are the pathologic features for osteoarthritis?
1) Disruption of the cartilage that lines the articular surface; fragments of cartilage floating in the joint space are called joint mice 2) Eburnation of the subchondral bone 3) Osteophyte formation (reactive bony outgrowths); classically arises in the DIP (Heberden nodes) and PIP (Bouchard nodes) joints of the lingers
What are Heherden nodes?
Osteophyte formation in distal interphalangeal joints
What are Bouchard nodes?
Osteophyte formation in proximal interphalangeal joints
What is rheumatoid arthritis?
Chronic, systemic autoimmune disease
In whom does rheumatoid arthritis classically arise?
in women of late childbearing age
What is rheumatoid arthritis associated with?
HLA-DR4
What is rheumatoid arthritis characterized by?
involvement of joints
What is the hallmark for rheumatoid arthritis?
synovitis leading to formation of a pannus (inflamed granulation tissue).
What does rheumatoid arthritis lead to?
destruction of cartilage and ankylosis (fusion) of the joint
What are the clinical features for rheumatoid arthritis?
1) Arthritis with morning stiffness that improves with activity 2) Fever, malaise, weight loss, and myalgias 3) Rheumatoid nodules 4) Vasculitis 5) Baker cyst 6) Pleural effusions, lymphadenopathy, and interstitial lung fibrosis
For rheumatoid arthritis, describe the arthritis that is seen clinically?
Symmetric involvement of PIP (proximal interphalangeal joints) joints of the fingers (swan-neck deformity), wrists (ulnar deviation), elbows, ankles, and knees is characteristic; DIP (distal interphalangeal joints) is usually spared (unlike osteoarthritis)
What is a difference between the arthritis seen in rheumatoid arthritis and osteoarthritis?
In rheumatoid arthritis the DIP is usually spared unlike osteoarthritis
For rheumatoid arthritis, what is seen on x-ray?
Joint-space narrowing, loss of cartilage, and osteopenia
What are rheumatoid nodules?
They are a central zone of necrosis surrounded by epithelioid histiocytes; arise in skin and visceral organs
What is vasculitis?
Multiple organs may be involved.
What is Baker cyst?
swelling of bursa behind the knee
What are the laboratory findings for rheumatoid arthritis?
1) IgM autoantibody against Fc portion of IgG (rheumatoid factor); marker of tissue damage and disease activity 2) Neutrophils and high protein in synovial fluid
What are the complications for rheumatoid arthritis?
anemia of chronic disease and secondary amyloidosis
What are the seronegative spondyloarthropathies?
1) Ankylosing spondylarthritis 2) Reiter syndrome 3) Psoriatic arthritis
What characterizes seronegative spondyloarthropathies?
It?s a group of joint disorders characterized by 1) Lack of rheumatoid factor 2) Axial skeleton involvement 3) HLA-B27 association
What does ankylosing spondylarthritis involve?
the sacroiliac joints and spine.
In whom does ankylosing spondylarthritis arise?
in young adults, most often male
How does ankylosing spondyloarthritis present?
with low back pain; involvement of vertebral bodies eventually arise leading to fusion of the vertebrae - bamboo spine
What are the extra-articular manifestations for ankylosing spondylarthritis?
They include uveitis and aortitis (leading to aortic regurgitation)
What is reiter syndrome characterized by?
the triad of arthritis, urethritis, and conjunctivitis.
In whom does Reiter syndrome arise?
in young adults (usually males) weeks after a GI or Chlamydia trachomatis infection
Psoriatic arthritis is seen in whom?
10% of cases of psoriasis.
What does psoriatic arthritis involve?
axial and peripheral joints; DIP joints of the hands and feet are most commonly affected, leading to sausage fingers or toes
What is infectious arthritis?
Arthritis due to an infectious agent, usually bacterial
What are the causes for infectious arthritis?
1) N. gonorrhoeae 2) S. aureus
What is the most common cause for infectious arthritis overall?
N. gonorrhoeae (its seen in young adults)
What is the 2nd most common cause of infectious arthritis overall?
S. aureus, and is seen in older children and adults
What does infectious arthritis classically involve?
It classically involves a single joint, usually the knee
What does infectious arthritis present as?
a warm joint with limited range of motion; fever, increased white count, and elevated ESR are often present
What is gout?
Deposition of monosodium urate (MSU) crystals in tissues, especially the joints
What is gout due to?
hyperuricemia; related to overproduction or decreased excretion of uric acid
Where is uric acid derived from?
purine metabolism
What excretes uric acid?
It is excreted by the kidney
What is the most common cause of gout?
Primary gout is the most common form;
What is the etiology of hyperuricemia?
it is unknown
What is secondary gout seen with?
1) Leukemia and myeloproliferative disorders 2) Lesch-Nyhan syndrome 3) Renal insufficiency
How does leukemia and myeloproliferative disorders lead to gout?
Increased cell turnover leads to hyperuricemia
How does Lesch-Nyhan syndrome lead to gout?
X-linked deficiency of hypoxanthine-guanine phosphoribosyltransferase (HGPRT) (which is the salvage pathway); presents with mental retardation and self-mutilation
How does renal insufficiency lead to gout?
decreased renal excretion of uric acid
How does gout present?
as exquisitely painful arthritis of the great toe (podagra)
Why does gout present as podagra?
- MSU crystals deposit in the joint, triggering an acute inflammatory reaction.
What may precipitate gout?
Alcohol or consumption of meat may precipitate arthritis.
What does chronic gout lead to?
1) development of tophi 2) renal failure
In gout, what happens in the development of tophi?
white, chalky aggregates of uric acid crystals with fibrosis and giant cell reaction in the soft tissue and joints
In gout, why is there renal failure?
Urate crystals may deposit in kidney tubules (urate nephropathy).
What are the laboratory findings for gout?
include hyperuricemia; synovial fluid shows needle-shaped crystals with negative birefringence under polarized light
What is pseudogout?
It resembles gout clinically, but is due to deposition of calcium pyrophosphate dihydrate (CPPD); synovial fluid shows rhomboid-shaped crystals with weakly positive birefringence under polarized light
What is dermatomyositis?
Inflammatory disorder of the skin and skeletal muscle
What is the etiology for dermatomyositis?
some cases are associated with carcinoma (e.g., gastric carcinoma)
What are the clinical features for dermatomyositis?
1) Bilateral proximal muscle weakness; distal involvement can develop late in disease. 2) Rash of the upper eyelids (heliotrope rash); malar rash may also be seen. 3) Red papules on the elbows, knuckles, and knees (Grotton lesion)
What are the laboratory findings for dermatomyositis?
1) Increased creatinine kinase 2) Positive ANA and anti-Jo-l antibody 3. Perimysial inflammation (CD4+ T cells) with peritascicular atrophy on biopsy
For dermatomyositis, what is seen on biopsy?
Peritascicular atrophy
What is the treatment for dermatomyositis?
corticosteroids.
What is polymyositis?
Inflammatory disorder of skeletal muscle
What does polymositis resemble?
dermatomyositis clinically, but skin is not involved
For polymositis, what is seen on biopsy?
endomysial inflammation (CD8+ T cells) with necrotic muscle fibers is seen on biopsy
