What is the risk of using spaced x-rays versus Magnetic Resonance Imaging (MRI) to diagnose a suspected Salter-Harris type 1 fracture of the distal fibular physis in a 14-year-old male with a right lateral ankle injury, where the growth plate is not visible on initial x-ray and there is concern for injury to the Anterior Talofibular Ligament (ATFL) and Calcaneofibular Ligament (CFL)?

From the Guidelines

For a 14-year-old male with a suspected Salter-Harris type 1 fracture of the distal fibular physis, I strongly recommend obtaining an MRI rather than spaced X-rays to minimize the risk of delayed diagnosis and improper treatment. The primary concern in this case is the potential for growth plate injury, which may not be visible on initial X-ray, and the associated risk of ligamentous injuries, such as damage to the Anterior Talofibular Ligament (ATFL) and Calcaneofibular Ligament (CFL) 1.

Key Considerations

• MRI provides immediate, detailed visualization of the growth plate injury without radiation exposure, which is particularly important in pediatric patients.
• Spaced X-rays (taken 7-10 days apart) can eventually show healing or widening of the physis, but they delay diagnosis and potentially proper treatment.
• The main risk of spaced X-rays is that this delay could lead to improper healing, growth disturbance, or chronic instability if a significant injury is present.
• Additionally, spaced X-rays expose the patient to radiation twice.

Diagnostic Accuracy

MRI can immediately detect physeal widening, bone bruising, and associated soft tissue injuries, including ATFL and CFL damage noted in this patient's examination 1. This comprehensive assessment allows for appropriate treatment planning from the outset. Although MRI is more expensive and may require sedation in some pediatric patients, the benefit of accurate, timely diagnosis outweighs these considerations in cases where growth plate injuries are suspected but not visible on initial radiographs.

Clinical Implications

The use of MRI in this context is supported by the American College of Radiology, which recommends MRI as the reference standard for ligamentous injury and assessment of stability, particularly in athletes 1. In summary, the risk of using spaced X-rays versus MRI to diagnose a suspected Salter-Harris type 1 fracture of the distal fibular physis in a 14-year-old male with a right lateral ankle injury is significant, and MRI is the preferred diagnostic modality due to its ability to provide immediate, detailed visualization of the growth plate injury and associated soft tissue injuries without radiation exposure.

From the Research

Risk of Using Spaced X-rays versus MRI

The risk of using spaced x-rays versus Magnetic Resonance Imaging (MRI) to diagnose a suspected Salter-Harris type 1 fracture of the distal fibular physis in a 14-year-old male with a right lateral ankle injury can be assessed by considering the following points:

• The Salter-Harris classification of growth plate injuries aids in estimating both the prognosis and the potential for growth disturbance 2.
• Displaced Salter-Harris Type I Distal Fibula Fractures can be treated operatively, and anatomic reduction and fixation of the displaced fracture can result in excellent outcomes 3.
• MRI evidence suggests that sprains may be more common than previously thought in skeletally immature children with isolated lateral ankle injuries without radiograph-visible fractures 4, 5.
• A study found that none of the 18 patients had evidence of fibular growth plate injury on MR imaging, and patients often had more than one abnormal finding on MRI, including ligamentous sprains and bony contusions 4.
• Another study found that only 3.0% of children with clinically suspected Salter-Harris type I fracture of the distal fibula demonstrated MRI-confirmed SH1DF, and 80.0% had ligament injuries 5.

Diagnostic Accuracy

The diagnostic accuracy of spaced x-rays versus MRI can be compared as follows:

• Spaced x-rays may not be able to detect growth plate injuries or ligamentous sprains, which can lead to misdiagnosis and inappropriate treatment.
• MRI can detect growth plate injuries, ligamentous sprains, and bony contusions, providing a more accurate diagnosis and guiding appropriate treatment.
• A study found that the clinical diagnosis of SH1DF was incorrect in 100% of cases, and MRI identified ligamentous sprains and/or bony contusions in almost 90% of patients 4.

Treatment Implications

The treatment implications of using spaced x-rays versus MRI can be considered as follows:

• If a growth plate injury is suspected, MRI can provide a more accurate diagnosis and guide appropriate treatment, including operative treatment if necessary 3.
• If a ligamentous sprain is diagnosed, treatment can focus on immobilization and rehabilitation, rather than operative treatment 4, 5.
• A 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 5.