From the Guidelines
For a 14-year-old male with a suspected Salter-Harris type 1 fracture of the distal fibular physis with an invisible growth plate on x-ray, MRI is the best diagnostic imaging modality to use, as it can directly visualize physeal injuries and detect bone marrow edema, cartilage damage, and soft tissue injuries simultaneously. This recommendation is based on the most recent and highest quality study, which suggests that MRI is the reference standard for ligamentous injury and assessment of stability, particularly important in athletes 1. The study highlights that MRI can help exclude Salter 1 fractures in the pediatric population 1, which is crucial in this case.
When considering the diagnosis of a potential Salter-Harris type 1 fracture, it is essential to prioritize the imaging modality that provides the most comprehensive evaluation of the suspected fracture and associated ligamentous structures. Key benefits of using MRI include:
- Direct visualization of physeal injuries that may not be apparent on standard radiographs
- Detection of bone marrow edema, cartilage damage, and soft tissue injuries simultaneously
- Avoidance of radiation exposure, which is particularly important in pediatric patients
- Comprehensive evaluation of both the suspected fracture and the associated ligamentous structures
In contrast, spaced x-rays may not provide the same level of detail and may not be suitable for diagnosing physeal injuries, especially when the growth plate is invisible on initial x-rays. The patient should be immobilized in a removable boot or splint with weight-bearing restrictions to prevent further injury until imaging is completed 1.
From the Research
Diagnostic Imaging Modalities for Salter-Harris Type 1 Fracture
- Spaced x-rays and Magnetic Resonance Imaging (MRI) are two diagnostic imaging modalities that can be used to diagnose a potential Salter-Harris type 1 fracture of the distal fibular physis.
- However, the evidence suggests that MRI is a more reliable modality for diagnosing Salter-Harris type 1 fractures, especially in cases where the growth plate is not visible on x-ray 2, 3.
Limitations of X-rays
- X-rays may not be able to detect Salter-Harris type 1 fractures, especially in cases where the growth plate is not visible 2, 3.
- A study found that only 3.0% of children with clinically suspected Salter-Harris type 1 fractures had MRI-confirmed fractures, while 80.0% had ligament injuries and 22.0% had isolated bone contusions 3.
Advantages of MRI
- MRI can detect ligament injuries and bone contusions that may not be visible on x-ray 2, 3.
- A study found that MRI-confirmed Salter-Harris type 1 fractures were rare in children with radiograph-negative lateral ankle injuries, and that these children most commonly had ligament injuries (sprains) 3.
- Another study found 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 3.
Clinical Diagnosis and Treatment
- The physical examination is unreliable in determining the location of the distal fibular physis, with a study finding that pediatric emergency medicine physicians were unable to accurately identify the distal fibular physis on physical examination 4.
- A study found that emergency physicians were more likely to diagnose Salter-Harris type 1 fractures than orthopedic physicians, but that few fractures were missed 5.
- The treatment of suspected Salter-Harris type 1 fractures should include immobilization and referral for orthopedic evaluation, regardless of the final diagnosis 5.