Case 14

The chondro-osseus junction is a weak part of the bone during infancy and shearing forces disrupt the immature areas and not the adjacent cartilaginous physis. This AP view demonstrates the typical "bucket handle" fracture of the proximal metaphysis of the left tibia. The injury generally requires shearing forces not produced in accidental trauma. The injury can be produced when limbs flail during shaking. Other mechanisms of trauma to consider include twisting, jerking or pulling mechanisms. This infant had no history of prior injury and no explanation for this injury. The finding is suspicious for child abuse.

It is unusual to see subperiosteal new bone formation with a classic metaphyseal lesion (CML). This makes it difficult to estimate the time frame in which the fracture may have occurred. In this radiograph, there is a finding of new bone formation evident near the CML. This suggests healing that is likely 7–10 days in progress. Although this range is just an estimate, this further adds to the suspicion of abuse because it is an "older" fracture in combination with an acute fracture of the humerus.

The presence of solely subperiosteal new bone formation, even just unilateral new bone formation without a metaphyseal fracture, could be normal in an infant. However, this infant has a metaphyseal lesion and this is not normal.

A bone scan should not be used to diagnose a classic metaphyseal lesion. The metaphyseal area normally has high bone turnover, and therefore, is an expected hot spot for tracer absorption.