Limping is a common presenting symptom in young children. Clinical examination backed up by laboratory analysis, standard radiography, and/or ultrasound may fail to determine the diagnosis, and limping may prove persistent, requiring repeated consultation. Magnetic resonance imaging (MRI) can suggest the etiology or provide welcome reassurance when normal. We advocate the use of MRI in cases of persistent unexplained limping in young children. The study hypothesis was that coronal short TI inversion recovery (STIR) MRI has good negative predictive value (NPV) in unexplained limping in children under 6 years of age.

Coronal STIR MRI sequences were analyzed in 130 children younger than 6 years (84 boys, 46 girls) during the period April 2007 to May 2017. They extended from the lower thoracic spine down to the feet. Agreement was analyzed between the radiologist's initially suggested diagnosis and the pediatric orthopedic specialist's final diagnosis.

Overall, 49 scans were normal (37.7%) and 81 abnormal (62.3%). The mean age at MRI was 32.3 months. Coronal STIR MRI had 98% NPV. There was 99.2% agreement between the radiologist's diagnosis and the final diagnosis.

The recently reported contribution of STIR MRI in bone and joint infections was extended to unexplained limping.

First-line MRI with coronal STIR sequences improved the diagnostic efficacy, thanks to its speed and relative lack of movement artifacts.