A 15-month-old boy is brought to the emergency department due to refusal to stand. Earlier today, the patient fell from a standing height after tripping on toys. The event was witnessed by several employees at the day care that he has been attending for a week. He cried initially but was consoled and continued playing. At home, however, he was unwilling to walk or bear weight on his right leg. The patient has met appropriate growth parameters and developmental milestones. Weight and height are at the 75th percentile. Temperature is 37.7 C (99.9 F). The patient is sitting comfortably in his mother's lap. The abdomen is soft with no organomegaly. The right distal tibia is slightly edematous compared with the left. Palpation over the right distal tibia elicits crying. Skin examination shows scattered bruises on the bilateral knees and lower legs. The radiograph is shown in the image below:
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In addition to leg immobilization, which of the following is the best next step in evaluation of this patient?
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Spiral fractures of the distal tibia can be seen in ambulatory children age ≤3 and are known as toddler's fractures. These fractures typically result from a twisting injury during a low-impact fall in the early walking years.
A thorough history is essential during initial evaluation because nonaccidental trauma must be considered if the mechanism does not match the injury or if a spiral fracture occurs in a nonambulatory child. However, this patient's fall after tripping is typical for a toddler's fracture, and the location of his bruising (eg, scattered bruises on the bilateral knees and lower legs) is common in early walkers as they stumble while walking (in contrast, bruises on the face, neck, torso, and buttocks are more commonly associated with physical abuse).
Tibial fractures present with pain, limp, and/or refusal to bear weight. Pain elicited with ankle dorsiflexion or twisting of the knee and ankle in opposite directions is characteristic. Fracture site tenderness and leg swelling may also be present. Anteroposterior and lateral radiographs may be normal initially but usually show a hairline fracture, as seen in this patient. Treatment involves immobilization and pain control with no additional workup.
(Choice A) Bone marrow evaluation is performed for suspected leukemia, which can present with bruising and bone pain. However, this patient has acute symptoms after a fall and a fracture line on x-ray that is consistent with the mechanism of injury.
(Choice B) Calcium, phosphorus, and parathyroid hormone levels are part of the evaluation for rickets. Although fractures can occur with severe rickets, x-ray findings include bowing of the tibia and widening of the epiphyseal plates, which are not seen in this patient.
(Choice C) Collagen type 1 mutation is seen in osteogenesis imperfecta, which often presents with easy bruising and multiple fractures after minimal or no injury. In contrast, this patient's fracture and bruising on the knees/shins are in an expected location for a toddler learning to walk.
(Choice D) MRI can detect osteomyelitis in a patient with fever, as well as bony tenderness, warmth, and swelling. This patient's lack of fever and x-ray findings make infection unlikely.
Educational objective:
Toddler's fractures, or spiral tibial fractures, are seen in children during the first few years of walking. Injury typically occurs following a twisting motion during a minor fall. Spiral fractures may be suspicious for nonaccidental trauma if the history is inconsistent or if the child is not yet ambulatory.