Why might a radiologist misdiagnose a Salter-Harris I (Type 1) lateral fracture on Magnetic Resonance Imaging (MRI) as a growth plate fracture when an orthopedic surgeon suggests a bone bruise?

From the Guidelines

A radiologist might misdiagnose a Salter-Harris type I lateral fracture on MRI because these injuries can be challenging to differentiate from bone bruises, as both conditions show similar signal changes on MRI, with increased T2 signal and bone marrow edema at the growth plate. The confusion typically arises because both conditions can present with similar imaging characteristics, making it difficult to distinguish between them. According to the American College of Radiology 1, MRI is the reference standard for ligamentous injury and assessment of stability, and it can help exclude Salter 1 fractures in the pediatric population. However, the presence of bone bruise and adjacent soft-tissue edema have shown a higher association with acute ligamentous injuries and tendon abnormalities 1.

Some key points to consider in differentiating between Salter-Harris type I fractures and bone bruises include:

• Clinical examination findings like point tenderness at the growth plate, swelling, and functional limitations
• Mechanism of injury and patient age
• Growth plates naturally appear somewhat irregular on MRI, especially during periods of rapid growth
• Additional imaging like comparison views of the uninjured side or follow-up radiographs after 7-10 days might help resolve the discrepancy

In cases where there is disagreement between specialists, it is essential to consider these factors and potentially obtain additional imaging to ensure an accurate diagnosis and appropriate treatment plan. Treatment approaches may differ based on the diagnosis, with fractures typically requiring immobilization for 3-4 weeks, while bone bruises might be managed with shorter periods of activity modification and symptomatic care 1.

From the Research

Radiologist Misdiagnosis of Salter Harris 1 Lateral Fracture on MRI

• A radiologist may misdiagnose a Salter Harris 1 lateral fracture on MRI as a growth plate fracture, while an orthopedic surgeon may diagnose it as a bone bruise, due to the complexity of interpreting MRI images in skeletally immature children 2.
• The study by 2 found that in 100% of cases, the clinical diagnosis of Salter-Harris I fracture of the distal fibula was incorrect, and instead, MRI identified ligamentous sprains and/or bony contusions in almost 90% of patients.
• The discrepancy in diagnosis may be due to the fact that MRI evidence in children suggests that sprains may be more common than previously thought, and that the clinical presentation of a Salter-Harris I fracture can be similar to that of a bone bruise or ligamentous sprain 2.
• Another study by 3 found that a Salter-Harris Type I fracture can be accompanied by other injuries, such as a Grade II ACL tear, and that MRI imaging can be useful in identifying these concomitant injuries.
• The use of MRI imaging in the diagnosis of Salter-Harris fractures can be complex, and the interpretation of images may vary between radiologists and orthopedic surgeons, leading to potential misdiagnosis 2, 3.

Factors Contributing to Misdiagnosis

• The complexity of interpreting MRI images in skeletally immature children, particularly in the diagnosis of Salter-Harris fractures 2.
• The similarity in clinical presentation between Salter-Harris fractures and other injuries, such as bone bruises or ligamentous sprains 2.
• The potential for concomitant injuries, such as ACL tears, to accompany a Salter-Harris fracture 3.
• The variability in interpretation of MRI images between radiologists and orthopedic surgeons 2, 3.