Type:
Educational Exhibit
Keywords:
Infection, Education, Diagnostic procedure, PET-CT, Nuclear medicine conventional, MR, Nuclear medicine, Musculoskeletal bone
Authors:
S. Barreto 1, M. McGrath2, M. Mohammed2; 1Syracuse, NY/US, 2SYRACUSE/US
DOI:
10.26044/ecr2019/C-3331
Background
OM occurs due to hematologic spread(most common route),
contiguous spread from a an adjacent soft tissue infection(Figure 1) or by direct inoculation during surgery or trauma.
Inciting infection of the bacteria creates an inflammatory process with resultant resorption of bone.
Staphylococcus aureus is the most common pathogen responsible for hematogenous OM.
Microorganism inoculation of bone causes alterations in pH and increased capillary permeability; leading to regional edema,
leukocyte recruitment,
cytokine release,
tissue breakdown,
decreased oxygen tension,
increased local pressure,
small vessel-thrombosis and bone deterioration(1).
The infection spreads from within the medullary cavity through the Haversian and Volkmann canals into the subperiosteal space and then to the periosteum and adjacent soft tissues(1).
Hematogenous OM is most commonly in children and involves the most vascularized regions of the bone(Figure 2).
The lower extremities are most commonly affected,
particularly the femur and tibia(2).
In long bones,
the metaphysis is highly vascular and often the focus of infection,
with the developing vascular supply of the long bones affecting spread of disease(Figure 3)(2,3).
The growing periosteum is composed of two layers,
an outer fibrous periosteum and an inner highly vascular layer called the cambium; which can be another focus for infection (2).
In the spine,
discitis is exclusively a disease of children(Figure 4),
while osteomyelitis-discitis complex(Figure 5) is more common in the adult population; this is likely due to the differing vascular supply of the vertebral body and disc in different age groups (Figure 6)(4).
Acute OM is defined as disease process lasting less than 2 weeks.
Incidence of acute OM is 8-10 per 100,000 in developed countries and up to 80 per 100,000 in developing countries(2).
OM is termed chronic when symptoms last greater than 6 months and/or in the presence of necrotic bone,
which usually takes 10 days to be formed(1,2).
Subacute OM lasts longer than 2 weeks,
with little or no symptoms of infection.
Subacute and chronic OM are most commonly in the adult population.