Purpose or Case Report: Traumatic lesions to the sternum are uncommon, especially in the pediatric population. Sternal fractures require significant force to occur due to the greater thorax elasticity in children compared to adults. Sternal segment dislocation is extremely rare with only 13 cases reported in the literature. We report a case of traumatic sternal segment dislocation in a 3-year-old girl.

After falling on a pole, a 3-year-old girl presented chest pain increased by Valsalva and low-grade fever for few days. Her parents brought her to the hospital when she experienced a painful thoracic crisis with the development of a presternal lump. Ultrasonography showed an acoustic shadowing calcified mass representing the first sternal segment being dislocated and rotated at almost 90 degrees. CT showed dislocation with horizontal alignment of the first sternal segment and an undisplaced fracture line in the middle of this segment. There was soft tissue swelling but no repercussion on mediastinal structures. A bone scintigraphy was ordered to exclude any infectious process surimposed and was normal. Conservative management was elected. X-rays 2 months later showed partial remodeling of the sternum. Ten months after the initial trauma, patient remained asymptomatic. CT showed partial osteolysis of the first sternal segment compatible with osteonecrosis.

The main cause of sternal dislocation is direct trauma to chest wall. The sternal body is composed of 4 segments which begin to ossify early in childhood. The manubrium is rigidly attached to both the first ribs and clavicles, providing relative elasticity of other sternal segments. The first sternal segment is the most common dislocated segment. Patient usually presents with limited chest pain and anterior chest wall deformation. The diagnosis of sternal segment dislocation is based on history and physical exam. Imaging studies are useful to confirm the diagnosis. The sternal segment may be minimally dislocated initially, but can continue its rotation for about 2 weeks. Fragment gain stability at 90 degrees rotation. According to the review of the 13 published cases, both operative and conservative treatments show similar outcome.
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Conclusions: Sternal segment dislocation in childhood is rare. Successful conservative management with remodeled sternal segment within few months may suggest that operative management may be reserved for severe or persistent symptoms.