CITW 11: The Bouncing Baby

CITW 11: The Bouncing Baby

Welcome back to another Clinical Image of the Week from the case files of the Brown EM Residency!

HPI: A 2-year old boy presents after being “bounced” by his 12-year old brother in a “bouncyhouse” at a birthday party.  He had the immediate onset of knee pain and refused to weight bear on his right leg.  He has never had an injury before and has no prior medical problems.

VS: HR 140 (crying), BP 94/50, RR 40, SpO2 98%, T 98.8

PE: Agitated and screaming whenever you enter the room.  Apparent right knee effusion, but no erythema.  He will not tolerate ROM well, but you note that he flexes his right hip when his parents lower his feet to the floor to avoid putting his right foot down.  It is difficult to assess for point tenderness due to patient agitation.

X-rays are obtained of the right hip, femur, knee and tib/fib:

Screen Shot 2015-11-28 at 11.43.26 AM Screen Shot 2015-11-28 at 11.43.41 AM Screen Shot 2015-11-28 at 11.43.55 AM

What’s the Diagnosis?

 Transverse Fracture of the Tibial Metaphysis (aka: Trampoline Fracture)

https://i2.wp.com/image.slidesharecdn.com/longbonefinal-131212104304-phpapp02/95/long-bone-6-638.jpg?resize=456%2C344

We actually didn’t see this fracture and would have probably discharged the patient, until an astute radiologist pointed it out for us.

From 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 which is most often seen in children 2 to 5 years of age” (1).

We were surprised to learn that Orthopedics actually wanted to cast it.

If you suspect it:

  1. Get an X-ray – 2 view.  Stress radiographs are a thing of the past.
  2. Look at the tibial epiphyseal line: a recent German study in 2014 showed that there is more anterior tilt when there is a trampoline fracture (1).

Image 1: Normal angle

Fig-1-Two-year-old-girl-with-a-normal-left-tibia-on-two-views-The-anterior-tilt-angle

Image 2: Trampoline Fracture

1-s2.0-S0720048X14002496-gr3

3. Examine distal pulses – The popliteal artery is “tethered” to the proximal tibia just below the physis, making artery laceration or thrombosis a risk (higher rates in proximal tibial fractures than distal femur fractures); also the trifurcation of the popliteal artery happens here.  “Have the same level of suspicion for vascular injury as you would with a knee dislocation” (3)

4. How do you manage it?

  • Ortho consult is recommended for: metaphyseal fracture, open fracture (of course), tubercle avulsion, intra-articular extension, neurovascular compromise (4)
  • Closed cast is standard of care for these, for 6 weeks
  • It’s not uncommon to have growth disturbance cause by these fractures (up to 25%), with the affected tibia growing longer than the non-affected
  • 1 week follow-up with ortho recommended & NWB

Hop to it!

The contents of this case were deliberately altered to protect the identity of the patient. All content in this report are for educational purposes only. The patient consented to the use of these images.

Resident Reviewer: Dr. Ross
Faculty Reviwer: Dr. Tubbs

See you next week!

Sources:

(1): http://radiopaedia.org/articles/trampoline-fracture

(2): The anterior tilt angle of the proximal tibia epiphyseal plate: A significant radiological finding in young children with trampoline fractures. European Journal of Radiology Volume 83, Issue 8, August 2014, Pages 1433–1436

(3):Journal of the American Academy of Orthopaedic Surgeons, Issue: Volume 23(9), September 2015, p 571–580

(4): http://www.uptodate.com/contents/proximal-tibial-fractures-in-children#H12

One thought on “CITW 11: The Bouncing Baby

  1. Cool case Jon! In the cross table, you can really appreciate that effusion as well, notably in the suprapatellar region as well. That would raise my suspicion (at least) for an occult fracture with possible intraarticular extension.

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