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Arab Board Orthopedic Surgery Clinical study materials
Arab Board Orthopedic Surgery Clinical study resources

Arab Board Orthopedic Surgery Clinical: Musculoskeletal Infection and Metabolic Bone Disease

Arab Board Orthopedic Surgery Clinical · Work through your exam, one topic at a time.

All guide sections

Musculoskeletal Infection and Metabolic Bone Disease

Principles of Musculoskeletal Infection

Candidates must understand osteomyelitis (acute vs chronic), septic arthritis, prosthetic joint infection (PJI), and soft tissue infections (necrotizing fasciitis). Know risk factors (diabetes, immunosuppression), pathophysiology (bacterial adhesion, biofilm), diagnosis (labs, imaging, cultures), and treatment (antibiotics, surgical debridement).

Key Concepts

  • Acute osteomyelitis: Most common in children (hematogenous, metaphysis). Staph aureus most common. Symptoms: fever, bone pain, reluctance to move limb. Diagnosis: blood cultures, MRI. Treatment: IV antibiotics (4-6 weeks), surgical drainage if abscess.
  • Chronic osteomyelitis: Cierny-Mader classification (anatomic type, host status). Requires surgical debridement of necrotic bone and antibiotics.
  • Septic arthritis: Emergency; joint aspiration for cell count, Gram stain, culture. Treatment: IV antibiotics and urgent irrigation and debridement.
  • Prosthetic joint infection: Diagnosis with MSIS criteria; treatment: DAIR, one-stage or two-stage exchange.
  • Metabolic bone disease: Osteoporosis (DEXA scan, T-score ≤ -2.5), osteomalacia (vitamin D deficiency), Paget's disease (increased alkaline phosphatase, bone pain, deformities), hyperparathyroidism (brown tumors, subperiosteal resorption).

Traps

  • Septic arthritis: Must be diagnosed and treated urgently to prevent joint destruction.
  • Osteomyelitis: Chronic osteomyelitis may be culture-negative; need bone biopsy.
  • Paget's disease: Elevated ALP with normal calcium/phosphate; risk of osteosarcoma.
  • Osteoporosis: Treat with bisphosphonates, calcium, vitamin D; assess fracture risk (FRAX).

Worked Example

A 60-year-old diabetic patient presents with a swollen, red, hot knee and fever. Joint aspiration shows 50,000 WBCs with 90% neutrophils. Diagnosis: septic arthritis. Rule of thumb: Septic arthritis is a surgical emergency; perform urgent arthroscopic or open irrigation and debridement, and start IV antibiotics. Delay leads to cartilage destruction.