From the Guidelines
The diagnosis for the patient is an undisplaced fracture of the distal fibula with a Salter-Harris 1 component, as evidenced by the bone marrow edema and linear region of low signal extending from the physis distally. The patient's presentation is consistent with a fracture, and the imaging findings support this diagnosis. According to the American College of Radiology Appropriateness Criteria 1, radiographs are the initial imaging study of choice for patients with acute trauma to the ankle, and the OAR criteria have a high sensitivity for detecting ankle fractures.
Key Findings
- Bone marrow edema of the distal fibula
- Linear region of low signal extending from the physis distally
- Minimal bone marrow edema superior to the physis
- Intact ankle joint alignment (mortise)
- No evidence of ligament damage
- Surrounding structures, including ligaments, tendons, and joints, appear normal The Salter-Harris 1 component of the fracture involves the growth plate, which requires careful management to prevent future growth disturbances 1. However, the intact ankle alignment is a positive prognostic factor.
Recommended Imaging
- Radiographs, including anteroposterior, lateral, and mortise views, are the initial imaging study of choice 1
- Weight-bearing radiographs, if possible, can provide important information about fracture stability 1
- Special views, such as the axial Harris-Beath view or Broden view, may be necessary in certain cases, such as suspected calcaneal fractures or lateral process fractures of the talus 1
From the Research
Diagnosis of Bone Marrow Edema of the Distal Fibula
The diagnosis for a patient with bone marrow edema of the distal fibula, a linear region of low signal extending from the physis (growth plate) distally, and minimal bone marrow edema superior to the physis, suggestive of an undisplaced fracture with a Salter-Harris 1 component, can be considered based on the following evidence:
- The patient's symptoms and imaging findings are consistent with a Salter-Harris type I fracture of the distal fibula, which is a common injury in children 2, 3, 4.
- However, studies have shown that not all lateral ankle injuries in children are Salter-Harris type I fractures, and some may be ligament injuries or sprains 5, 6.
- A systematic review of the literature found that the incidence of Salter-Harris type I fractures in children with lateral ankle injuries ranged from 0-57.5%, while the incidence of ATFL injuries and osteochondral avulsions was higher in recent series 6.
- MRI examinations have been shown to be useful in diagnosing occult growth plate fractures and distinguishing them from ligament injuries or sprains 5.
Imaging Findings
The imaging findings of bone marrow edema of the distal fibula, a linear region of low signal extending from the physis (growth plate) distally, and minimal bone marrow edema superior to the physis, are consistent with a Salter-Harris type I fracture of the distal fibula 2, 3, 4.
- However, these findings can also be seen in ligament injuries or sprains, and further evaluation with MRI or other imaging modalities may be necessary to confirm the diagnosis 5, 6.
Treatment
The treatment for a patient with a diagnosed Salter-Harris type I fracture of the distal fibula typically involves orthopedic reduction and immobilization in a plaster device 3.
- However, studies have shown that children with fractures detectable only by MRI had a comparable recovery with those with sprains when treated with a removable ankle brace and self-regulated return to activities 5.
- The need for correct diagnosis and treatment is stressed by the risk for late problems, such as growth disturbance and joint problems, especially when there is fracture through the medial malleolus 4.