Residual Symptoms of Occult Pediatric Ankle Injuries: MRI-Diagnosed Bone Bruising

Aims: To define the nature of non-radiographically evident injuries of the ankle and hindfoot in children who exhibited persistent pain, swelling and refusal to bear weight after 6 weeks of immobilisation.
Methods: Ten children (7 boys, 3 girls; age range 5 to10 years) were included in the study. They presented with normal plain radiographs after an acute traumatic ankle injury. They were all immobilised for 6 weeks. The detection of residual symptoms and signs indicated the need of a limited magnetic resonance imaging (MRI). It revealed bone bruising localized to the hindfoot in all cases. Bone bruises were classified according to anatomical location and whether they were solitary lesions or were combined with other soft tissue injuries.
Results: From a total of 10 cases, 6 were unifocal, 3 of them were localized to the talus and 3 to the calcaneus, while in 4 multifocal cases bone bruising involved all the bones of the hindfoot. All cases were associated with a varying degree of soft tissue injuries including signs of ankle and subtalar joint effusion, but there was no evidence of ligamentous injuries in our patients. The total period of immobilisation reached 3 months for unifocal bone bruises and 4 months for multifocal lesions. In all cases, a prolonged recovery period exceeding 2 months followed before return to normal activities including sports. The long-term follow-up ranged from 2 to 5 years. No complications were detected.
Conclusion: A limited MRI examination is indicated in children with residual symptoms following acute ankle injuries. Bone bruising localized to the hindfoot was the “occult” bone lesion diagnosed in all our cases. This study indicates that bone bruising or contusion should be classified as a distinct clinical entity best visualized on MRI with fat suppression.