Osteomyelitis: Bone Infection Lecture Notes

Definition and Overview

• Osteomyelitis is a bone infection caused by the growth of microorganisms, typically bacteria, in bone and bone marrow.
• Microorganisms can enter the bone in two primary ways:
  1. Open wound: Infections can occur through open fractures, exposure to dirt, water, air, or through sores/soft tissue infections.
  2. Hematogenous spread: Microorganisms travel through the bloodstream from another infection site to the bone.

Causes and Risk Factors

• Open Wounds:
  • Exposure due to open fractures.
  • Diabetic patients with foot sores.
  • Presence of orthopedic implants (e.g., plates, screws, knee replacements).
• Hematogenous Spread: Occurs when bacteria from another infection travel through the blood to the bone.

Pathophysiology

• The infection can lead to:
  • Pain and loss of function.
  • Formation of pus (abscess).
  • Dead bone.

Diagnosis

• Imaging:
  • X-rays: Osteomyelitis isn’t visible for several days.
  • MRI or bone scans: Show the infection earlier than X-rays.
• Blood Work:
  • Elevated white blood cell count.
  • High erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) levels indicate infection and are monitored during treatment.

Treatment

• Treatment varies based on several factors:
  • Affected bone and location of the infection.
  • Presence of abscess or dead bone.
  • Patient age and other individual factors.
• Surgical Intervention:
  • Removal of infected bone and soft tissue.
  • Irrigation to remove bacteria and pus.
  • Infected bone sent for lab analysis to determine bacterial culture and sensitivity to antibiotics.
• Antibiotic Therapy:
  • Empirical treatment initiated before lab results based on common organisms causing similar infections.
  • IV antibiotics usually required for several weeks.
  • Adjustments made once culture results are available for targeted antibiotic therapy.

Monitoring and Follow-Up

• Continuous monitoring of lab values (ESR, CRP) to assess treatment efficacy.
• Adjust treatment plans based on changes in lab values and patient response to therapy.