Infectious Joint Pathologies

Question 1

What populations are affected by septic arthritis?

Answer 1

• immunocompromised
• children

Question 2

How do microorganisms get into joints?

Answer 2

• hematogenous
• direct

Question 3

In a patient with pneumonia, how would microorganisms get into a joint causing septic arthritis?

Answer 3

hematogenous

Question 4

In a child with a soft tissue infection, how would microorganisms get into a joint causing septic arthritis?

Answer 4

hematogenous

Question 5

In a patient with osteomyelitis, how would microorganisms get into a joint causing septic arthritis?

Answer 5

direct

Question 6

What is the etiology of septic arthritis?

Answer 6

bacterial infection
- S aureus
- H. influenza
- gonococcal infection in sexually active adults
- E. coli

Question 7

What is the most common infectious organism to cause septic arthritis?

Answer 7

S. aureus

Question 8

What are the clinical manifestations of septic arthritis?

Answer 8

• acutely red, swollen joint
• mono-arthrotic
• favours LE
• joint (intracapsular) effusion (soft tiss. swelling) distorts fat folds

Question 9

What locations are most commonly affected by septic arthritis?

Answer 9

lower extremity (knee & hip)

(hand - often due to human bite)

Question 10

What are the radiographic characteristics of septic arthritis?

Answer 10

• rapid loss of jt. space
• loss of subchondral white line
• aggressive bone destruction
• osseous ankylosis (late stage)

Question 11

What is the radiographic latency period for septic arthritis?

Answer 11

• 7-10 days in extremities
• 21 days in spine
  (this is for any infectious process)

Question 12

What is the first confirmatory radiographic finding for septic arthritis?

Answer 12

loss of subchondral white line

Question 13

How long would it take to see loss of subchondral white line in the hip joint?

Answer 13

7-10 days

Question 14

Regarding septic arthritis, once a joint becomes infected, what is the guaranteed outcome for this joint?

Answer 14

destruction leading to long-term sequela (eg. subluxations)

Question 15

What are the relevant lab findings for septic arthritis?

Answer 15

• ^ESR/CRP
• normal alk phos
• HLA-B27 neg.
• RF neg.
• synovial biopsy: normal uric acid (DDx gout); purulent exudate

Question 16

What are the possible treatments for septic arthritis?

Answer 16

• antibiotic therapy
• aspiration (decompress jt.)
• jt. irrigation
• decrease motion & weight bearing
• joint replacement (or may end in ankylosis)

Question 17

What are the etiologies of fungal arthritis?

Answer 17

• often complication of neoplasia or immunocompromise (HIV/AIDS, chemotherapy)
• Candida species (yeast infection)
• TB

Question 18

What is often the primary site of involvement of fungal arthritis?

Answer 18

lung

Question 19

Fungal arthritis in the spine presents similar to ____

Answer 19

Pott’s Dz

Question 20

How does fungal arthritis appear radiographically?

Answer 20

Same as septic (bacterial) arthritis, highly destructive

Question 21

What are the possible treatments for fungal arthritis?

Answer 21

• very difficult (usually already immunocompromised)
• anti-fungal drugs are toxic to other tissues, especially liver

Question 22

What is the etiology of Lyme disease?

Answer 22

Spirochete infection (borrelia burgdorferi) transmitted by Ixodes tick

Question 23

What age group is affected by Lyme disease?

Answer 23

any age

Question 24

When does stage 1 of Lyme disease occur?

Answer 24

3-35 days post-bites

Question 25

When does stage 2 of Lyme disease occur?

Answer 25

weeks to months following skin lesion

Question 26

When does stage 3 of Lyme disease occur?

Answer 26

months to years post-infection

Question 27

What are the clinical manifestations of stage 1 of Lyme disease?

Answer 27

- erythema chronicum migrans (Bullseye rash) - fever & malaise - fatigue, headache & brain fog - arthralgias - **lymphadenopathy** - cough - meningeal irritation - **migratory myalgia** (diffuse, achy) - testicular swelling

Question 28

What is the medical term for a bullseye rash?

Answer 28

erythema chronicum migrans

Question 29

What inflammatory cells would be found in a patient with Lyme disease?

Answer 29

chronic inflammatory response: lymphocytes & plasma cells

Question 30

What are the clinical manifestations of stage 2 of Lyme disease?

Answer 30

- migratory MSK pain - cardiac & neurologic abnormalities - transient & migratory jt. pain

Question 31

What are the clinical manifestations of stage 3 of Lyme disease?

Answer 31

- >50% have arthralgia & severe arthritis - swollen jts (especially knee) - neuro effects: tingling, paresthesia, encephalomyelitis, dementia - skin manifestations

Question 32

Histopathology of joints affected by Lyme disease are similar to what other pathology?

Answer 32

RA (synovial mem. undergoes hypertrophy w/ mononuclear infiltrate)

Question 33

What clinical manifestations, if experienced by a patient with Lyme disease, will be permanent?

Answer 33

neurologic effects: - tingling - paresthesia - encephalomyelitis - dementia

Question 34

How is Lyme disease diagnosed?

Answer 34

Antibody titers (IgM & IgG) if Lyme disease is suspected (not usually done)

Question 35

What is the treatment for Lyme disease?

Answer 35

Antibiotics - early: tetracycline or erythromycin - Late stage: long-term, high dose antibiotics

Question 36

At what stage of Lyme disease is treatment most effective?

Answer 36

Stage 1