Osteomyelitis

Osteomyelitis is an infection involving bone, caused by bacteria in most cases. It may be severe, and it may affect any bone. The pathogen may enter the bone directly (non-hematogenous osteomyelitis), usually after trauma or wounds, or from the blood (haematogenous osteomyelitis).

Imaging

Conventional radiography may not visualise pathology in the first 2 weeks of the disease. If the symptoms have lasted <2 weeks, CT or MRI is indicated. If it has lasted more than 2 weeks, radiography is sufficient and will show osteolysis, periosteal reaction, and bone destruction.

Osteonecrosis

Osteonecrosis, also called avascular necrosis, refers to ischaemic necrosis of bone caused by impaired blood supply. It may affect any part of the bone but most commonly the knee and femoral head. It's most common in children and adolescents.

Imaging

MRI is the main imaging modality in the evaluation of osteonecrosis.