Lecture

OSTEOMYELITIS
Definition:
 Osteo- derived from the Greek word osteon meaning bone, myelo meaning marrow and –it is meaning inflammation, simply means an infection of the bone or bone marrow that results in inflammation, necrosis and formation of new bone.
Types:
1. Acute osteomyelitis
- Bone infection develops within two weeks of an initial infection, injury or the onset of the underlying disease.
2. Sub-acute osteomyelitis
- Bone infection develops within one to two months of an initial infection, injury or the onset of the underlying disease.
3. Chronic osteomyelitis
- - Bone infection develops within two months or more of an initial infection, injury or the onset of the underlying disease.
Classification:
1. Hematogenous
- Through bloodstream
- Blood borne spread of infection
- Involves rich red marrow
- In children and infants: the long bone

2. Contagious focus
- Extension from adjacent tissue infection

3. Direct infection to the bone or exogenous
- Microbes gain entry to the bone through open fractures, penetrating wounds, or contamination in surgical procedure
- Implanted items may also cause infection
Etiology:
Osteomyelitis is caused by:
 Contiguous spread
 Blood borne organisms
 Open wounds
Most common causative agent: Staphylococcus aureus

Risk factors:
 Gender(male)
 Poorly nourished
 Elderly
 Children
 Obese
 Patients who have impaired immune system
 Patients with chronic illnesses (e.g. Diabetes, rheumatoid arthritis)
 Patients receiving long tern corticosteroid therapy or other immunosuppressive agents

Anatomy and physiology:

Bone
Each long bone consists of a central shaft called the diaphysis, and the two ends, each called an epiphysis. A thin layer of articular cartilage covers the end of the epiphyses where the bone articulates with other bones. A long bone that is still growing has an epiphyseal plate, and the diaphysis. The epiphyseal plate is the site of growth in