From the Guidelines
For a 14-year-old male with a suspected Salter-Harris type 1 fracture of the distal fibular physis, MRI alone is sufficient and spaced X-rays are not necessary. MRI provides superior visualization of the growth plate injury, soft tissue damage (including the ATFL and CFL ligaments), and any occult fractures that may not be visible on plain radiographs, as it is the reference standard for ligamentous injury and assessment of stability 1. The MRI will clearly show physeal widening, bone marrow edema, and ligamentous injuries, allowing for comprehensive assessment of both bony and soft tissue structures.
In cases of suspected growth plate injuries where initial X-rays appear normal, MRI is the preferred advanced imaging modality as it avoids radiation exposure while providing detailed information about the injury 1. This is particularly important in adolescents with open growth plates where accurate diagnosis impacts treatment decisions and monitoring for potential growth disturbances. According to the American College of Radiology, MRI can help exclude Salter 1 fractures in the pediatric population and evaluate ligament and tendon injuries that can occur without fracture on radiography 1.
Key benefits of using MRI in this context include:
- High-resolution evaluation of tendons and ligaments to distinguish between tendinopathy, sprain, and partial or complete tears 1
- Ability to detect bone bruise and adjacent soft-tissue edema, which have a higher association with acute ligamentous injuries and tendon abnormalities 1
- Avoidance of radiation exposure, which is especially important in pediatric patients
- Comprehensive assessment of both bony and soft tissue structures, allowing for accurate diagnosis and treatment planning.
If the MRI confirms a growth plate injury, follow-up should include clinical assessment and possibly a single follow-up X-ray at 4-6 weeks to ensure proper healing, rather than multiple spaced X-rays. This approach prioritizes the patient's quality of life, minimizes radiation exposure, and ensures accurate monitoring of the injury's progression.
From the Research
Diagnostic Approach for Suspected Salter-Harris Type 1 Fracture
- The diagnosis of a Salter-Harris type 1 fracture, particularly in the context of a suspected injury to the distal fibular physis, can be challenging when the growth plate is not visible on initial x-ray 2.
- Magnetic Resonance Imaging (MRI) has been shown to be useful in evaluating pediatric growth plate injuries, including those that are not visible on conventional radiographs 3.
Role of MRI in Diagnosing Growth Plate Injuries
- MRI allows for the direct visualization of cartilage and can improve the evaluation of growth plate injuries, potentially altering the Salter-Harris classification or staging 3.
- Studies have demonstrated that MRI can detect occult fractures not visible on radiographs and may result in a change in patient management 3.
Specific Considerations for Distal Fibular Physis Injuries
- In cases of suspected Salter-Harris type 1 fracture of the distal fibula, MRI evidence suggests that sprains may be more common than previously thought, with a significant proportion of patients having ligamentous sprains and/or bony contusions rather than growth plate fractures 4, 5.
- The clinical diagnosis of Salter-Harris type 1 fracture of the distal fibula (SH1DF) may be incorrect in a high percentage of cases, with MRI identifying alternative pathologies such as ligamentous sprains and bony contusions 5.
Implications for Diagnostic and Treatment Strategies
- Given the potential for MRI to identify alternative pathologies and the low incidence of Salter-Harris type 1 fractures in radiograph-negative lateral ankle injuries, a spaced x-ray series may not be necessary in addition to an MRI for diagnosing growth plate injuries 4, 5.
- The use of MRI in the diagnostic workup can help guide treatment strategies, potentially reducing the need for unnecessary immobilization and promoting earlier return to activities 4.