From the Guidelines
For a 14-year-old male with a suspected Salter-Harris type 1 fracture of the distal fibular physis, an MRI is the best diagnostic approach, as it offers superior visualization of soft tissue and cartilage, allowing for the detection of subtle physeal injuries not apparent on plain radiographs. The initial X-ray did not show a visible growth plate abnormality, but the patient's symptoms, such as tenderness over the lateral malleolus and ligamentous structures, warrant further investigation. According to the American College of Radiology 1, MRI is the reference standard for ligamentous injury and assessment of stability, particularly important in athletes. MRI can also help exclude Salter 1 fractures in the pediatric population 1.
The use of spaced X-rays may not be sufficient, as they lack sensitivity for non-displaced Salter-Harris I fractures, which are characterized by separation through the growth plate without visible displacement on X-ray. In contrast, MRI provides high-resolution evaluation of the tendons and ligaments, allowing distinction between tendinopathy, sprain, and partial or complete tears. Key benefits of MRI in this context include:
- Detection of ligamentous injuries, including sprains, partial tears, and complete tears, which can occur without fracture on radiography 1
- Evaluation of the associated ligamentous structures, such as the anterior talofibular ligament (ATFL) and calcaneofibular ligament (CFL)
- Assessment of bone bruise and adjacent soft-tissue edema, which have been shown to have a higher association with acute ligamentous injuries and tendon abnormalities 1
Given the importance of proper diagnosis and management in adolescents with open growth plates, an MRI is essential to prevent growth disturbances that could lead to angular deformities or leg length discrepancies. Treatment would depend on MRI findings, but typically involves immobilization for 3-4 weeks for non-displaced fractures.
From the Research
Diagnostic Approach for Suspected Salter-Harris Type 1 Fracture
- The diagnosis of a Salter-Harris type 1 fracture of the distal fibular physis can be challenging, especially when the growth plate is not visible on initial X-ray 2, 3.
- Magnetic Resonance Imaging (MRI) can be useful in diagnosing Salter-Harris type 1 fractures, as it can detect occult growth plate fractures and ligament injuries that may not be visible on X-ray 2, 3.
- A study found that only 3.0% of children with clinically suspected Salter-Harris type 1 fractures of the distal fibula had MRI-confirmed fractures, while 80.0% had ligament injuries and 22.0% had isolated bone contusions 3.
- Another study found that the clinical diagnosis of Salter-Harris type 1 fracture was incorrect in 100% of cases, and instead, MRI identified ligamentous sprains and/or bony contusions in almost 90% of patients 2.
Comparison of Imaging Modalities
- Computed Tomography (CT) imaging may be necessary for evaluating growth plate fractures of the distal tibia, as it can provide more accurate information about the fracture and articular surface involvement compared to conventional radiographs (CR) 4.
- However, CT imaging may not be necessary for all cases, and the decision to use CT should be made on a case-by-case basis, taking into account the severity of the injury and the need for accurate diagnosis 4.
- MRI is a useful imaging modality for evaluating ligament injuries and occult growth plate fractures, and can provide valuable information for diagnosis and treatment planning 2, 3.
Treatment and Management
- The treatment and management of suspected Salter-Harris type 1 fractures of the distal fibular physis should be based on the diagnosis and severity of the injury, as well as the presence of any ligament injuries or other complications 5, 6.
- A removable ankle brace and self-regulated return to activities may be a suitable treatment approach for children with radiograph-negative lateral ankle injuries, regardless of whether they have a fracture or a sprain 3.
- Early closed reduction and fixation may be necessary for displaced Salter-Harris type 1 fractures of the distal fibula, to prevent complications such as premature physeal closure and growth disturbance 5.