PANCE Blueprint Musculoskeletal (8%)

• Fever, restriction of movement of involved extremity or refusal to bear weight

Acute osteomyelitis is most commonly seen in children with S. aureus as the most common organism

• Sickle cell disease - Salmonella is pathognomonic

Chronic osteomyelitis is most common in adults secondary to open injury of bone and surrounding soft tissue

• S. aureus is the most common organism (80%)
• Staph epidermidis in prosthetic joints
• Gram-negative pseudomonas in IVDU
• Pasteurella seen in cases caused by cat/dog bites
• Mycobacterium TB seen in vertebral involvement (Potts DZ)

Diagnose with bone aspiration = gold standard

• X-ray triad: demineralization, periosteal reaction, bone destruction (lags behind symptoms 7-10 days); MRI shows changes before XR
• Labs: CRP elevated for 4-6 weeks, WBC and ESR high in most cases
• Definitive diagnosis = blood culture or by needle aspiration/bone biopsy

Treatment: IV antibiotics for 4-6 weeks and at least 2 weeks of IV antibiotics

• Newborn (<4 months) - Group B Strep - nafcillin or oxacillin + 3rd gen cephalosporin
• > 4 months S. aureus - MSSA - Nafcillin + Ancef MRSA - Vancomycin or Linezolid
• Sickle cell - Salmonella - 3rd gen cephalosporin or FQ (Cipr)
• Puncture wound - Pseudomonas - Cipro or levofloxacin

• A single, swollen, warm, painful joint that is tender to palpation + constitutional symptoms  (fever, sweats, myalgia, malaise, pain)
• MC = knee, and hip
• Caused by: hematogenous spread, direct inoculation, contiguous spread
• S. aureus is most common (40-50%); N. gonorrhea in sexually active young adults, streptococci; pseudomonas in IVDU
• Diagnose with arthrocentesis: joint fluid aspirate for definitive diagnosis (WBC > 50,000 primarily PMNs)
• WBC > 1000 is positive in pt with prosthetic joints

Treatment is based on gram stain- 2-4 week course of antibiotics  + arthrotomy with joint drainage

• Staph aureus = Vanco/nafcillin (Vanco or Clindamycin if PCN allergic)
• Gonorrhea = ceftriaxone
• IVDU = Cipro/Levaquin