Role of various imaging modalities
The selection of a diagnostic imaging method is based on the risk-benefit ratio, especially in pediatric practice.
- Radiography: In the early stages (acute process), radiographs may be normal, but the method is essential for ruling out other pathologies (fractures, Perthes disease). In subacute courses, periosteal reaction and metaphyseal radiolucent foci (Brodie abscess) can be detected. The chronic process is characterized by osteosclerosis, destruction, and new bone formation.
- Ultrasound (US): Optimal for detecting joint effusion (septic arthritis), subperiosteal, and soft tissue abscesses. It is also used for ultrasound-guided fluid aspiration.
- Computed tomography (CT): Has limited application in children due to high radiation exposure.
- Magnetic resonance imaging (MRI): Possesses maximum sensitivity and specificity. Whole-body MRI is effective for detecting multifocal lesions.
- Radionuclide diagnostics (scintigraphy): With 99mTc-MDP shows increased radioactivity in the affected bone in the early stages, but has low specificity.
MRI semiotics of osteomyelitis
Magnetic resonance imaging is the gold standard for diagnosis.
Acute osteomyelitis manifests as bone marrow edema. T1-weighted images show low signal intensity, while T2 and STIR show high signal intensity. When the growth plate is involved, widening of the physeal plate and a high-intensity T2 signal along it are identified.
Abscesses (intraosseous, subperiosteal, soft tissue) appear as fluid collections (low T1, high T2 signal). Following intravenous gadolinium administration, the abscess walls actively enhance with contrast.
Chronic osteomyelitis is characterized by cortical thickening and the rim sign: a zone of fibrosis with low signal on all sequences surrounding the active infection (high T2 signal). Breakthrough of a bone abscess into soft tissues with fistula formation is possible.
Contrast administration combined with fat suppression significantly increases the accuracy of detecting complications and helps differentiate granulation tissue from an abscess.
Features in children and adults
The patterns of development and course of osteomyelitis depend on the patient's age.
Children: Infection more frequently affects healthy bones (predominantly long tubular bones) via hematogenous seeding. Acute hematogenous osteomyelitis begins in the metaphysis due to abundant blood supply. Because the periosteum is loosely attached in children, subperiosteal abscesses frequently form. In newborns, metaphyseal vessels communicate with the growth plate, which sharply increases the risk of joint involvement (septic arthritis).
Adults: Spontaneous infections are rare. The disease typically develops against the background of prior trauma, surgical procedures (presence of implants), or immunosuppression. The hematogenous route of infection in adults more frequently leads to the development of vertebral osteomyelitis (spine involvement).
Non-bacterial forms and related syndromes
Multifocal non-suppurative forms of bone inflammation exist, presenting with periods of exacerbation and remission.
- Chronic recurrent multifocal osteomyelitis (CRMO): Occurs in children, predominantly affecting the metaphyses of tubular bones. Cultures are negative. Whole-body MRI reveals bone marrow edema, periostitis, and signs of transfysitis.
- SAPHO syndrome: Characteristic of adults (30–50 years). Includes synovitis, acne, pustulosis, hyperostosis, and osteitis. Most commonly affects the anterior upper chest wall (sternoclavicular, sternocostal joints) and the spine.
- Garré sclerosing osteomyelitis: A chronic form affecting the mandible in children. Characterized by dense edema and non-suppurative ossifying periostitis.
Briefly: answers to topical questions
What complications can develop after osteomyelitis in children?
The following complications may develop after osteomyelitis in children:
- Chronification of infection — untreated acute osteomyelitis can progress to a chronic form.
- Bone destruction — untreated acute osteomyelitis can cause destruction of bone tissue and spread to surrounding tissues.
- Septic arthritis — infection can spread to the joints.
- Growth plate injury and growth arrest (growth arrest) — in osteomyelitis near the growth plate in patients with immature skeletons, prolonged follow-up is required.
- Chondrolysis — occurs in later stages of infection when the growth plate is affected.
- Fistula formation (sinuses) — in chronic osteomyelitis, abscesses can break through the cortical layer into soft tissues with the formation of fistulous tracts.
The rim sign on MRI in chronic osteomyelitis: like a "castle wall", fibrosis (low signal) protects surrounding tissues from the active inflammation inside (high T2 signal).
Class and exam questions
Why is contrast administered in MRI for osteomyelitis?
Gadolinium administration with fat suppression allows clear differentiation of a true abscess (only the walls enhance) from granulation tissue and edema zones.
Why can radiography be normal in acute osteomyelitis?
In the first days of the disease, bone destruction and periosteal reaction are not yet pronounced. X-rays during this period are mainly needed to rule out other causes of pain, such as fractures.
What is the value of ultrasound in musculoskeletal infections?
Ultrasound excellently visualizes joint effusion and subperiosteal fluid collections, and allows targeted diagnostic aspiration.
What else to study on this topic
- MRI findings in septic arthritis and its differential diagnosis
- Specifics of the imaging appearance of vertebral osteomyelitis in adults
- Diagnosis of necrotizing fasciitis and gas gangrene
- The role of whole-body MRI in SAPHO syndrome and CRMO
- Differential diagnosis of bone infections and neoplastic processes
Master the entire topic in the "Diagnostic Radiology" course
This is a summary. The course covers everything tested in classes and exams.
- Complete study guide on "Imaging of osteomyelitis" and 2,199 more pages of the subject
- Assignments and quizzes after every topic — just like in a colloquium
- AI tutor answers questions on the topic anytime
- 10 video lessons on the subject
Other topics in the "Musculoskeletal System" section
Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.