Bone and Joint Infections

Question 1

Osteomyelitis (Presentation)

Answer 1

• DEEP BONE PAIN and LOCALIZED TENDERNESS over the involved area of the bone
• poor wound healing
• +/- erythema and edema
• +/- fever, malaise, myalgia, weight loss

Question 2

Cellulitis

Answer 2

• acute with s/s of inflammation (erythema, edema, warmth, tenderness

Question 3

Best Initial Test (Osteomyelitis)

Answer 3

X-ray

Question 4

Test for Osteomyelitis

Answer 4

1. X-ray: BEST INITIAL TEST( periosteal elevation, bone erosions). Negative x-ray doesn’t exclude OM. Negative for 2 weeks
2. MRI: MOST EFFECTIVE test for diagnosis of osteomyelitis. Detect early infection
3. Bone scan: Non-specific (maybe positive in metastatic disease, fracture). Obtain if MRI is contraindicated
4. ESR , CRP: Non-specific. Usually elevated ( ESR > 70). May suggest the diagnosis. Obtained for monitoring RESPONSE to Rx, DURATION of Rx
5. Blood culture: Positive only in 50% of patients
6. Bone biopsy: MOST ACCURATE TEST to identify microorganisms and guide the therapy

Question 5

Tx (Osteomyelitis)

Answer 5

• Empiric therapy should be broad-spectrum: Vancomycin IV + Ciprofloxacin IV (or Piperacillin/tazobactam IV)
• Follow ESR to determine (1) response to the treatment and (2) duration of the therapy (usually 6-12 weeks)
• Usually need surgical debridement
• Delay antibiotics (if possible until culture results are available)

Question 6

Septic arthritis: facts

Answer 6

• Infection of the synovium
• Risk factors: degenerative joint (osteoarthritis, rheumatoid arthritis) or artificial joint
• Most common pathogen: S. aureus, disseminated N. gonorrhea (young sexually active adults)

Question 7

Septic arthritis: presentation

Answer 7

• Acute onset (hours-days)
• Rapidly increasing joint pain (ONE JOINT) at rest and with motion
• Joint swollen, warm, tender and red
• LIMITED ROM (passive and active), unable to ambulate
• (+/-) fever

Question 8

Best Initial Test: Septic Arthritis

Answer 8

Joint Aspiration (synovial analysis)

Question 9

WBC in synovial fluids analysis

Answer 9

• 1 - 2,000 WBCs&raquo_space;> normal
• 2,000 - 20,000 WBCs&raquo_space;> inflammation w/o infection (gout, pseudo-gout)
• > 50,000 WBCs (esp. w/ neutrophils > 80%)&raquo_space;> infection

Question 10

Tests for septic arthritis

Answer 10

1. Synovial fluids aspiration: MOST USEFUL INITIAL test. WBC is > 50,000 cells with > 80% PMNs (1-2,000 WBC is normal, 2,000-20,000 is inflammatory arthritis like gout). Obtain Gram stain and culture
2. ESR/ CRP: Non-specific and often elevated
3. X-ray: Not useful , r/o fx , OM
4. MRI: Not useful (shows effusion)
5. BC: Positive in 50%
6. NAAT for GC: If GC arthritis is suspected (Gonorrhea)

Question 11

Septic Arthritis (TX)

Answer 11

• Start with Vanco IV&raquo_space; f/u cultures» may switch to PO 1st gen. cephalosporin when improvement ( if staph sensitive)
• If GC- Ceftriaxone 2 gm IV or IM» may switch to PO 3rd gen. cephalosporin when improvement
• Usually duration - 3- 4 weeks
• Joint drainage and “wash out” should be performed