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Flashcards in Bone/rheuma Deck (14):
1

osteonecrosis (avascular necrosis

hip pain, decreased range of motion, and underlying sickle cell disease,
- occurs due to impaired blood supply to a segment of bone.
- femoral head is the most common location, although other bones may be affected.
- Conditions associated with osteonecrosis include the following:

1. Sickle cell disease leads to thrombotic occlusion of arteries. Embolic occlusion (fat emboli, decompression sickness) can also cause osteonecrosis.
2. Injury to the vessel wall (vasculitis) causes impaired blood supply (eg, systemic lupus
3. High-dose corticosteroid therapy and alcoholism are also associated with osteonecrosis of the femoral head
presents with chronic, progressive groin and hip pain that is exacerbated by weight bearing.

Physical examination reveals restricted movement in the affected joint, with no swelling, erythema, or warmth in the surrounding area

Microscopic analysis of the wedge-shaped zone of affected bone is notable for dead bony trabeculae (empty lacunae) and fat necrosis.

2

Trochanteric bursitis

- sharp, intermittent pain at the lateral hip and thigh - Pain is increased with pressure on the affected hip (eg, lying on the side) and with walking.

3

Osteoarthritis

- causes pain during activity that is relieved by rest.
- Joint instability and crepitus may be present.

4

Septic arthritis

- acute onset of pain in the joint.
- Physical examination shows swelling, erythema, and warmth

5

rheumatoid arthritis (RA)

- affect the smaller joints of the hand and wrist.
- causes morning stiffness, spongy synovitis, and joint deformities.
- Bilateral pain, stiffness, and deformity of the proximal interphalangeal and metacarpophalangeal joints -
- Morning stiffness, tenderness, and edema of the affected joints predominate early in this disease
- Later, osteopenia, erosions, and joint space narrowing lead to decreased range of motion and deformities (eg, swan neck, ulnar deviation).
- Patients can also develop rheumatoid nodules, firm, nontender, subcutaneous nodules that occur at pressure points such as the elbows or forearms
- due to failure of immune tolerance, with development of an autoreactive immune response directed against joint components (eg, type II collagen, citrullinated vimentin).

- CD4+ T-helper cells become activated by these self-antigens and release cytokines that promote chronic inflammatory synovitis.
- CD4+ T cells also induce B cells to synthesize rheumatoid factor and anti-citrullinated protein antibodies (ACPAs).

- Rheumatoid factor is an antibody (typically IgM) specific for the Fc component of IgG.

Rheumatoid factor binds circulating IgG and ACPAs bind modified self-proteins, forming immune complexes that deposit on the synovium and cartilage. These complexes activate complement in those locations, contributing to chronic inflammation and joint destruction.

5

CREST syndrome.

Anticentromere antibodies

6

systemic lupus erythematosus-like disease

Deficiency of complement components C1, C2, and C4 leads to increased susceptibility

7

Henoch-Schönlein purpura (HSP),

most common small vessel vasculitis in childre - classically affects boys 2-10 years old, and is often preceded by viral or streptococcal upper respiratory infections
- Symptoms of HSP generally develop a few weeks after the associated illness resolves
- hypothesized that antigen from the infection stimulates production of IgA antibodies and that IgA-containing immune complexes then deposit on vessel walls, inducing an inflammatory reaction.
- IgA-mediated leukocytoclastic (hypersensitivity) vasculitis.
- seen most prominently in the following organ systems:
1. Gastrointestinal tract: Intermittent severe abdominal pain is common in HSP. Vasculitis within the GI tract may result in upper and lower GI bleeding (hematemesis and bloody diarrhea, respectively) as well as bowel wall edema. Patients with HSP also have an increased risk of intussusception
2. Kidneys: Renal involvement in HSP is identical to that seen in IgA nephropathy (Berger disease), a condition characterized by IgA leukocytoclastic vasculitis limited to the kidney. Both diseases cause mesangial proliferation and crescent formation.
3. Skin: HSP classically causes "palpable purpura" on the buttocks and lower extremities. These lesions may begin as urticarial papules or plaques and subsequently evolve into purpura. The cutaneous findings in HSP result from leukocytoclasis of cutaneous vessels.
4. Joints: Self-limited migratory arthralgias and arthritis are most commonly seen in the large joints of the lower extremities (ankle and knee joints), possibly because of their dependent nature.

8

Kawasaki disease

Swollen lymph nodes and red eyes
high fevers, strawberry tongue, perioral erythema and fissuring, and periungual desquamation

9

synovitis

- acute joint pain, swelling, and erythema with restricted range of motion,
- Acute undiagnosed synovitis, especially when accompanied by fever or leukocytosis, represents a true emergency and warrants an expedited evaluation
- Potential causes include septic arthritis (gonococcal, nongonococcal), crystal arthropathy (eg, gout), hemarthrosis, or rheumatic disease
- Delayed diagnosis of septic arthritis may lead to loss of the joint and long-term disability, and may be fatal
- best evaluated with diagnostic arthrocentesis and synovial fluid analysis

-Gross inspection may assist the diagnosis, with purulent or cloudy fluid suggesting an infectious or inflammatory process.
- Fluid should be sent for crystal analysis, cell count, Gram stain, and culture. Blood cultures should also be drawn if septic arthritis is suspected.

10

Gout

- monosodium urate crystals that appear as needle-shaped negatively bifringent crystals.

11

Pseudogout

caused by calcium pyrophosphate dihydrate crystals that appear as rhomboid-shaped positively bifringent crystals.

12

reactive arthritis

- non-gonococcal Urethritis, conjunctivitis, and mono- or oligoarticular arthritis constitute the classic triad

- This seronegative (rheumatoid factor-negative) spondyloarthropathy most commonly affects patients age 20-40 and is associated with HLA-B27.

- Symptoms generally manifest 1-4 weeks following a primary infection causing urethritis or enteritis and are caused by an autoimmune reaction initiated by the infecting pathogen.

- Skin findings include keratoderma blennorrhagicum (hyperkeratotic vesicles on the palms and soles) and circinate balanitis (serpiginous annular dermatitis of the glans penis).

- Axial involvement, including sacroiliitis, may occur in about 20% of cases.

Preceding infection: chlamydia (GU), salmonella, shigella, yersinia, campy, c. Difficle (enteritis)
- msk: asymmetric oligoarthritis, enthesiti, dactylitis

13

syphilis.

Tabes dorsalis- tertiary

Secondart maculopapular or pustular (but not vesicular) rash that can involve the palms and soles; it is generally associated with polyarthritis (mono-arthritis is very rare).