Infectious Joint Pathologies Flashcards
What populations are affected by septic arthritis?
- immunocompromised
- children
How do microorganisms get into joints?
- hematogenous
- direct
In a patient with pneumonia, how would microorganisms get into a joint causing septic arthritis?
hematogenous
In a child with a soft tissue infection, how would microorganisms get into a joint causing septic arthritis?
hematogenous
In a patient with osteomyelitis, how would microorganisms get into a joint causing septic arthritis?
direct
What is the etiology of septic arthritis?
bacterial infection
- S aureus
- H. influenza
- gonococcal infection in sexually active adults
- E. coli
What is the most common infectious organism to cause septic arthritis?
S. aureus
What are the clinical manifestations of septic arthritis?
- acutely red, swollen joint
- mono-arthrotic
- favours LE
- joint (intracapsular) effusion (soft tiss. swelling) distorts fat folds
What locations are most commonly affected by septic arthritis?
lower extremity (knee & hip)
(hand - often due to human bite)
What are the radiographic characteristics of septic arthritis?
- rapid loss of jt. space
- loss of subchondral white line
- aggressive bone destruction
- osseous ankylosis (late stage)
What is the radiographic latency period for septic arthritis?
- 7-10 days in extremities
- 21 days in spine
(this is for any infectious process)
What is the first confirmatory radiographic finding for septic arthritis?
loss of subchondral white line
How long would it take to see loss of subchondral white line in the hip joint?
7-10 days
Regarding septic arthritis, once a joint becomes infected, what is the guaranteed outcome for this joint?
destruction leading to long-term sequela (eg. subluxations)
What are the relevant lab findings for septic arthritis?
- ^ESR/CRP
- normal alk phos
- HLA-B27 neg.
- RF neg.
- synovial biopsy: normal uric acid (DDx gout); purulent exudate
What are the possible treatments for septic arthritis?
- antibiotic therapy
- aspiration (decompress jt.)
- jt. irrigation
- decrease motion & weight bearing
- joint replacement (or may end in ankylosis)
What are the etiologies of fungal arthritis?
- often complication of neoplasia or immunocompromise (HIV/AIDS, chemotherapy)
- Candida species (yeast infection)
- TB
What is often the primary site of involvement of fungal arthritis?
lung
Fungal arthritis in the spine presents similar to ____
Pott’s Dz
How does fungal arthritis appear radiographically?
Same as septic (bacterial) arthritis, highly destructive
What are the possible treatments for fungal arthritis?
- very difficult (usually already immunocompromised)
- anti-fungal drugs are toxic to other tissues, especially liver
What is the etiology of Lyme disease?
Spirochete infection (borrelia burgdorferi) transmitted by Ixodes tick
What age group is affected by Lyme disease?
any age
When do Ixodes ticks feed?
May-July during nymph (feeding) stage
When does stage 1 of Lyme disease occur?
3-5 days post-bite
When does stage 2 of Lyme disease occur?
weeks to months following skin lesion
When does stage 3 of Lyme disease occur?
months to years post-infection
What are the clinical manifestations of stage 1 of Lyme disease?
- erythema chronicum migrans (Bullseye rash)
- fever & malaise
- fatigue, headache & brain fog
- arthralgias
- lymphadenopathy
- cough
- meningeal irritation
- migratory myalgia (diffuse, achy)
- testicular swelling
What is the medical term for a bullseye rash?
erythema chronicum migrans
What inflammatory cells would be found in a patient with Lyme disease?
chronic inflammatory response: lymphocytes & plasma cells
What are the clinical manifestations of stage 2 of Lyme disease?
- migratory MSK pain
- cardiac & neurologic abnormalities
- transient & migratory jt. pain
What are the clinical manifestations of stage 3 of Lyme disease?
- > 50% have arthralgia & severe arthritis
- swollen jts (especially knee)
- neuro effects: tingling, paresthesia, encephalomyelitis, dementia
- skin manifestations
Histopathology of joints affected by Lyme disease are similar to what other pathology?
RA
(synovial mem. undergoes hypertrophy w/ mononuclear infiltrate)
What clinical manifestations, if experienced by a patient with Lyme disease, will be permanent?
neurologic effects:
- tingling
- paresthesia
- encephalomyelitis
- dementia
How is Lyme disease diagnosed?
Antibody titers (IgM & IgG) if Lyme disease is suspected
(not usually done)
What is the treatment for Lyme disease?
Antibiotics
- early: tetracycline or erythromycin
- Late stage: long-term, high dose antibiotics
At what stage of Lyme disease is treatment most effective?
Stage 1
Loss of the subchondral white line is indicative of ____
septic arthritis
