Lower leg radiography

Tibial and fibular shaft fractures

Diaphyseal fractures of the lower leg bones have a number of clinical and radiographic features that depend on the patient's age and the mechanism of injury.

• Toddler's fracture (Toddler’s fracture): This is a non-displaced fracture of the middle or lower third of the tibial shaft. In children, it is often occult on standard AP and lateral views, but is better visualized on oblique views. The main symptom is that the child refuses to bear weight on the leg. If there are no other suspicions, repeat radiography is routinely unnecessary. A follow-up radiograph in a week will show periosteal reaction and sclerosis along the fracture line.
• Stress fractures (march fractures): Typical for children aged 10–15 years under high physical exertion. They are localized predominantly in the upper third of the tibia.
• Isolated tibial shaft fractures: Characterized by a reduced healing and remodeling capacity. It is important to remember that due to the pull of the long flexors with an intact fibula, there is a high risk of varus deformity.
• Isolated fibular fractures: Rare (result of a direct blow). Important rule: In case of a proximal fibular fracture, radiography of the ankle joint must be ordered. This is necessary to rule out Maisonneuve fracture (Maisonneuve fracture) — a pronation-lateral rotation (PLR) stage 3 injury, in which a high spiral fracture is combined with disruption of the distal tibiofibular syndesmosis.

Assessment of the proximal lower leg and knee joint

When analyzing the anteroposterior radiograph, the fibula serves as the landmark for the lateral side. The cortical layers of the tibial plateau should be sharp and sclerotic.

There is an important evaluation rule: if a perpendicular line is dropped downward from the lateral femoral condyle, it should meet the edge of the tibial plateau. The plateau is allowed to protrude laterally beyond this line by a maximum of 5 mm. Exceeding this value indicates a high probability of a lateral plateau fracture (depression resulting from forced valgus deviation).

To confirm an intra-articular fracture, the lateral radiograph is performed using a horizontal beam. This allows visualization of liphemarthrosis — fluid stratification, where bone marrow fat accumulates on top of blood in the suprapatellar pouch.

Severe distal lower leg injuries

The distal lower leg is frequently affected in high-energy trauma. This includes the pilon fracture (Pilon fracture).

It occurs due to high axial loading (axial loading). Radiographs reveal a severe comminuted fracture of the distal tibial metaepiphysis with destruction of the articular surface (plafond). Treatment requires open reduction and internal fixation: fragments are fixed with screws to the lateral metaphysis and the articular surface, which typically remains attached to the fibula.

Stage 4 PLR injuries are also distinguished. On the lateral radiograph, they manifest as an isolated posterior malleolus fracture. The main diagnostic sign of this stage is the absence of a lower-third fibular fracture, while the medial column and tibiofibular syndesmosis are invariably injured.

Salter-Harris growth plate injuries

In children, fractures frequently involve the physis (growth plate). The Salter-Harris classification includes five types:

1. Type I (Slip, 5%): Isolated epiphysiolysis without fracture of the adjacent bone. The line passes through the hypertrophic zone.
2. Type II (Above, 75%): The line splits the physis and extends into the metaphysis, shearing off a fragment (frequently seen at ages 10–16 due to shearing forces).
3. Type III (Lower, 10%): The line crosses the physis and runs vertically through the epiphysis. Always intra-articular (frequently the distal tibia).
4. Type IV (Through, 10%): Vertical fracture through the metaphysis, physis, and epiphysis. Also intra-articular.
5. Type V (Ruined, <1%): Crush injury to the growth plate. Results in growth arrest and bone deformity.

Types III and IV fractures require evaluation using CT. Displacement of more than 2 mm is an indication for precise surgical reduction.

Class and exam questions

What else to study on this topic

• Biomechanics of fragment fixation in surgical treatment of pilon fractures
• Radiographic anatomy of accessory ossification centers of the ankle joint in children
• MRI diagnosis of osteochondral lesions of the talar dome
• The role of CT in evaluating transitional fractures of the distal lower leg
• Mechanism of development of pronation-lateral rotation (PLR) injuries

Other topics in the "Musculoskeletal System" section

Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.