Pathogenesis (disease development)
In circa 80% of cases, osteomyelitis occurs after trauma (injury)/fracture (bone fracture) or surgery (exogenous form). In circa 20%, it is the endogenous form of osteomyelitis, in which pathogen seeding from an existing focus of inflammation occurs (hematogenous form).
In osteomyelitis, infection of the bone by bacteria occurs. These occupy regions of avital tissue and necrotic bone and form the so-called biofilm there. This biofilm offers the bacteria protection against the body’s own defense cells and antibiotics. The most common pathogens (about 75%) are Staphylococcus aureus and coagulase-negative staphylococci. However, ß-hemolytic A streptococci, other bacteria (Actinomyces, anaerobes, enterococci, Haemophilus influenzae type b, mycobacteria tuberculosis), viruses and fungi are also possible pathogens.
In children younger than three months of age with osteomyelitis or septic arthritis (severe joint inflammation), the pathogens are Streptococcus agalactia in approximately 50% of cases, followed by Staphylococcus aureus (22%) and Escherichia coli (18%).
Etiology (Causes)
Disease-related causes
Infectious and parasitic diseases (A00-B99).
- Existing foci of inflammation that may lead to hematogenous bacteremia (pathogen seeding through the bloodstream)
Injuries, poisonings, and other sequelae of external causes (S00-T98).
- Injuries with skin involvement
Other causes
- Operations on the bones
Systemic risk factors
- Old people
- Newborns
- Nutrition
- Malnutrion (malnutrition)
- Consumption of stimulants
- Tobacco (smoking)
- Malignant neoplasms, unspecified.
- Diabetes mellitus (diabetes)
- Immune disorders, unspecified
- Hepatic insufficiency (liver weakness)
- Renal insufficiency (kidney weakness)
- Respiratory insufficiency (“respiratory weakness”).
- Medications: Immunosuppression due to chemotherapy
Local risk factors
- Extensive scarring
- Chronic lymphedema at the affected region
- Chronic venous insufficiency (CVI)
- Macroangiopathy (vascular changes, in the large and larger arteries of the body).
- Neuropathy (collective term for many diseases of the peripheral nervous system).
- Radiation fibrosis
- Vasculitis (vascular inflammation) of small vessels.
