Osteomyelitis and Joint Infections Overview

Osteomyelitis and Joint Infections

• Definition: Osteomyelitis is an inflammation of the bone and marrow caused by infection.
• Types:
  • Pyogenic Osteomyelitis: Bacterial infection.
  • Tuberculous Osteomyelitis: Mycobacterium tuberculosis infection.
  • Septic Arthritis: Infection within a joint.
  • Non-Infectious Arthritis: Immune-mediated joint damage without direct infection.

Pyogenic Osteomyelitis

• Transmission:
  • Hematogenous: Spread through the bloodstream.
  • Direct Extension: From nearby infections.
  • Trauma: Injury to the bone.
• Pathogenesis:
  • Commonly affects long bones: Especially around growth plates where blood flow is slower.
  • Acute Phase: Bacteria enters and proliferates in the metaphysis (ends of long bones).
  • Chronic Phase: Leads to:
    • Sequestrum: Necrotic bone.
    • Involucrum: New bone surrounding necrosis.
    • Cloaca: Draining sinuses.
• Complications:
  • Septicemia (blood poisoning).
  • Bacterial arthritis.
  • Pathological fractures.
  • Amyloidosis (build-up of abnormal proteins).

Tuberculous Osteomyelitis

• Less common than pyogenic osteomyelitis.
• Usually secondary to tuberculosis in other parts of the body, like the lungs.
• Pathology:
  • Granulomatous inflammation.
  • Caseation (necrotic tissue).
• Commonly affects lower thoracic and lumbar vertebrae: Known as Pott's Disease.
• Complications:
  • Vertebral collapse.
  • Spinal cord compression.
  • "Cold" abscesses (without acute inflammation).

Septic Arthritis

• Infection spreads to joints:
  • Hematogenously: Through the bloodstream.
  • Direct Extension: From osteomyelitis.
  • Trauma: Injury to the joint.
• Common pathogens:
  • Gonococcal bacteria: Often affects single joints.
  • Brucella: May cause chronic arthritis.
• Complications:
  • Progressive joint destruction.
  • Fibrosis.
  • Ankylosis (joint fusion).

Non-Infectious Arthritis

• Types:
  • Rheumatoid arthritis: Autoimmune disease affecting joints.
  • Spondyloarthropathies: Examples include ankylosing spondylitis.
• Key feature: Immune-related joint damage without direct infection.