Case 23

A 2-month-old baby girl presented to the emergency department with a 3-day history of swelling of her left leg. Her mother denied any history of trauma. The baby cried when her left leg was moved but otherwise was doing well, so the mother thought to wait before bringing her in. When the grandmother saw the baby’s swollen leg, she brought her to the emergency department immediately. On physical examination, her left leg appeared swollen (Images 23a and 23b). X-rays are shown (Images 23c and 23d). https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9780429170423/e1d751c1-a9c7-4bb9-9d59-53742c84031a/content/fig23a.jpg"/> https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9780429170423/e1d751c1-a9c7-4bb9-9d59-53742c84031a/content/fig23b.jpg"/> https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9780429170423/e1d751c1-a9c7-4bb9-9d59-53742c84031a/content/fig23c.jpg"/> https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9780429170423/e1d751c1-a9c7-4bb9-9d59-53742c84031a/content/fig23d.jpg"/>

What do the images show?

What imaging studies are important to further evaluate this baby?

52The left leg is swollen as compared to the right side and the skin is taut from the swelling. A close-up photo shows bruises of the left leg. A fracture was suspected and thus x-rays of the legs were obtained. They show an acute oblique displaced fracture of the left tibia. There is also a metaphyseal corner fracture or classic metaphyseal lesion (CML) of the distal left tibia.

In children less than 2 years old, a skeletal survey needs to be obtained when physical abuse is suspected. The skeletal survey for this infant showed a total of 30 fractures at different stages of healing that included multiple CMLs and posterior rib fractures, both of which are highly specific for child abuse. ¹ A magnified x-ray of her distal right femur and proximal right tibia showed a CML of the distal right femur and a CML of the proximal right tibia. Diaphyseal fractures such as the tibia fracture in this infant occur four times more commonly than CMLs, but the CML has a greater specificity for abuse. The CMLs occur most often in infants less than 6 months old. They result from the flailing of the extremities during violent shaking. They could also result when a child’s extremity is grabbed and yanked forcefully or twisted. The distal femur as in this child is a common site for CML, which is a strong indicator for abuse. Thus this region should be carefully evaluated with high-detail skeletal radiographs in all cases of suspected infant abuse. ²