Acute Osteomyelitis (Greater Than 18 Months)

  • Etiology: hematogenous spread from asymptomatic or symptomatic bacteremia, infection starts in marrow space with significant edema with proliferation of excess WBC and bacterial growth and through bony canals the infected fluid permeates outward and elevates the periosteum, most commonly Staphylococcus aureus or Salmonella in sickle cell disease
  • Imaging: most commonly occurs at metaphysis and metaphyseal equivalents (apophyses, areas at the junction of bone and cartilage in flat bones) both of which are highly vascular with slow blood flow, physis is relative barrier for spread of infection from approximately 18 months of age until physeal closure, infection can spread into joint space / subperiosteal space / soft tissues / diaphysis of bone, most common regions involved are extremities and pelvis, continuous periosteal reaction, deep soft tissue edema, lack of extra osseous soft tissue mass
  • Complications: subperiosteal abscess, intramedullary abscess
  • Clinical: multicentric in 10%

Radiology Cases of Acute Osteomyelitis (Greater Than 18 Months)

Radiograph and nuclear medicine bone scan of osteomyelitis of the femur
AP radiograph of the pelvis was unremarkable. Nuclear medicine bone scan shows increased radiotracer uptake in the left femoral head and neck and proximal femur.
CT and MRI of osteomyelitis of the rib
Axial CT without contrast of the chest (above) shows bilateral axillary adenopathy and soft tissue swelling over the left lateral chest wall and associated rib destruction. Coronal T2 MRI of the chest (below left) shows a high signal intensity fluid collection between the skin and the ribs with surrounding edema. Axial T1 MRI with contrast of the chest (below right) shows extensive enhancement of the left ribs and surrounding muscle.