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Flashcards in Bone and Joint Infection Deck (26):
1

Septic Arthritis
1. 3 main causes

1. Bacterial (10% of pts presenting w/ acute pain)
2. Viral- acute, often multi-joint
3. Fungal- chronic, usually monoarticular

2

Septic Arthritis
1. Mortality if untreated?
2. Morbidity?

1. 10-30%
2. up to 50% w/ permanent loss of function

3

1. Who can get septic arthritis?
2. Risk Factors (8)

1. anyone
2. Age>80, prosthetic joint, recent joint surgery, IV drug use, endocarditis, immunosuppression/chronic disease, joint disease: RA, OA, Gout, skin infection/ulcer

4

3 ways Septic Arthritis can occur

1. Hematogenous spread
2. Direct inoculation (via trauma or surgery)
3. Spread of infection from contiguous source (bone)

5

Pathogenesis of Septic Arthritis

1. Synovial tissue that lines the joint space is normally leaky
2. Acute inflammatory response/ infiltrate
3. This causes synovial effusion and cartilage degradation

6

Septic Arthritis: Presentation
1. Onset
2. Number of joints
3. Symptoms
4. Exam

1. hours-days
2. mono-articular
3. pain, swelling, warmth, loss of function, fevers (not if you're immunosuppressed)
4. Tenderness, limited ROM/painful, effusion, redness

7

Differential Diagnosis of Septic Arthritis (7)

1. Crystal induced disease
2. Rheumatoid Arthritis
3. Osteoarthritis
4. Systemic Lupus Erythematous (SLE)
5. Reiter's and other reactive arthritides
6. Rheumatic Fever
7. Other Rheumatological disease

8

Septic Arthritis: Bacterial Causes
1. What is it most often?
2. What could it also be?
3. When does 2 become more common?

1. Gram +: Staph (30-65%, esp aureus); Strep (20-25%)
2. Gram Negatives: E. Coli, H. flu, Neisseria, Pseudomonas
3. IV drug use, immunocompromised, elderly

9

Septric Arthritis Diagnosis
1. What is the most important test?
2. What is seen early on X-ray?
3. Late?

1. Diagnostic Tap
2. Early: soft tissue swelling
3. Late: loss of joint space, erosive and destructive changes

10

Synovial Fluid Analysis in Septic Arthritis
1. What increases the likelihood of septic arthritis?
2. What specifically increases the likelihood of septic arthritis?
3. If a patient has low PMNs? can you rule out septic arthritis?

1. higher synovial WBCs
2. PMN >90%
3. NO;

11

Diagnosis of Septic Arthritis
1. How useful is the Gram Stain?
2. Culture?
3.Blood culture?

1. diagnostic in only 50%, but good bc rare false positives
2. 80-90% diagnostic; non-gonococcal arthritis
3. positive about 50% of the time

12

Treatment of Septic Arthritis (2)

1. Drainage (daily aspirations, surgical drainage, more important with larger/prosthetic joints)
2. Empiric, then driven by clinical background

13

3 Other common causes of infectious arthritis

Gonococcal arthritis
Lyme arthritis
Viral arthritis

14

Gonococcal Arthritis
1. Who commonly gets it?
2. What is it a form of?

1. most common in sexually active individuals; usually under 30 y/o
2. disseminated gonococcal infection (DGI)

15

DGI
1. how common is it?
2. which gender is more likely to get it?
3. What is it associated with?
4. Other risk factors?

1. 0.5-3% of gonococcal infections
2. women
3. menstruation/pregnancy
4. same as other STDs: more partners, IV drug use, lower SES

16

DGI
1. what causes it?
2. Classic Triad
5. Other common symptoms

1. result of occult bacteremia
2. Dermatitis (numerous painless, non-pruritic macules, papules, pustular lesions)
3. Tenosynovitis (most common in hands, wrists, fingers, 2/3s of pts)
4. Migratory polyarthalgia or arthritis
5. Fevers, malaises

17

DGI- Septic Joint
1. How common is it?
2. How many joints?
3. Which joints?

1. less common, can occur w/ or w/o DGI
2. usually monoarticular
3. knees, wrist, ankles

18

Gonococcal arthritis- Diagnosis
1. What must be done?
2. Gram stain
3. Culture
4. What is the best method?

1. diagnostic tap
2. only 25% positive for G neg diplococci
3. only 50% positive
4. PCR, either of synovial fluid or from mucosal sites of original infection

19

Osteomyelitis
1. Define
2. Is it acute or chronic?
3. Ways of getting it

1. inflammation of bone and marrow (infection)
2. Acute vs Chronic (considered chronic when sequelae are present)
3. Hematogenous vs Contiguous

20

Osteomyelitis: Hematogenous spread
1. Who gets hematogenous spread?
2. Where?
3. What bacteria are found there?

1. children, growing bones
2. Vertebral bodies
3. monomicrobial

21

Osteomyelitis: Contiguous Spread
1. What are some risk factors?
2. What bacteria are there?

1. DM, ischemic ulcers, decubitus ulcers, trauma/ surgery
2. Polymicrobial

22

Osteomyelitis Presentation
1. Acute
2. Chronic
3. What 2 sites present as just pain in acute?

1. Gradual onset of symptoms over days-weeks; pain, erythema, swelling, tender, fevers/rigors,
2.pain, erythema, swelling, sinus tracts, large ulcers
3. hip, vertebrae

23

Typical Osteomyelitis Pathogens

Staph
Strep
Enterococcus
Gram negative rods (pseudo, e coli, enterobacter)

24

Diagnosis of Osteomyelitis
1. 3 imaging modalities?
2. Which is the best? why?
3. When is it not the best?
4. What are the 3 nuclear studies?

1. X-ray, MRI, CT
2. MRI- good sens and spec; good negative predictive value;
3. when hardware is present?
4. Triple phase bone scan, Gallium scan, WBC scan

25

Osteomyelitis Diagnosis
1. What is a common easy test?
2. If it is positive in a DM foot ulcer, what futher testing is needed?

1. steel probe to bone test
2. none

26

Osteomyelitis Culture
1. How good is wound swab and deep wound cultures?
2. How good is percutaneous needle biopsy?
3. How good is a bone biopsy?

1. poor correlation w/ diagnosed organism
2. poor correlation w/ diagnosed organism
3. best method for specimen collection; yields positive cx 87% of the time