The Case
A six year old male presents to the ED after sustaining an injury in a trampoline. There were definitely more than one child in the trampoline, and they were playing “popcorn,” where one child lays down, and several others bounce them up and down by jumping in a circle around the supine child. He landed awkwardly after being bumped by an adjacent jumper, and immediately felt pain in his right knee and upper shin. In the ED XRays were obtained. Both images are courtesy of Radiopedia and Dr Andrew Dixon.
The Diagnosis
This is a proximal tibial metaphysical fracture. Note the lucency in the AP view and the cortical disruption in the lateral view. Sometimes we call these “trampoline fractures” given the common mechanism of injury. They are seen more commonly in preschool and grade school aged children (age 3 to 9 years). When children land, a transverse metaphyseal fracture occurs when excessive valgus or varus stress is applied across the knee. Per Radiopedia, “the fracture is thought to occur when a second, usually heavier individual causes the jumping surface to recoil upwards as the unsuspecting victim is descending. The combined excessive load is thought to produce the characteristic fracture.”
I’d be remiss if I forgot to show this wonderful diagram from Mubarak et al, which depicts every Pediatric Emergency Medicine Physician’s nightmare injury scenario.
Management
Proximal tibial fractures are very painful – certainly more so than a toddler’s fracture. Children may need breakthrough pain management with oxycodone or oral morphine in addition to a base of ibuprofen. Children should be immobilized in a long leg posterior splint with copious padding. These are also fractures that benefit from earlier orthopedic involvement. If the fracture is open, you are concerned about compartment syndrome or vascular compromise, if there is a Salter Harris III or IV pattern, or if it extends into the joint in any way call ortho from the ED. Otherwise after splinting they can be seen within 1 week. Patients will generally recover without incident but will need 4 to 6 weeks of long leg casting.
