Imaging Case of the Week 150 Answer

The left ankle x-rays, at the outset, look like a simple medial malleolar fracture with significant soft tissue swelling around the ankle. However, upon close inspection of the fracture, there is a serious injury pattern that necessitates an urgent orthopaedic referral from the ED.

The AP view shows a short oblique fracture of the medial malleolus. There are also two linear fracture fragments close to the medial malleolus as well as a small avulsion fracture near the tip of the malleolus. In addition to this, the medial ankle joint space is widened, suggesting a deltoid ligament injury.

Comminuted medial malleolus fractureThe mortise view shows minimal widening of the tibio-fibular clear space, with the width being about 7mm. Normally, this space should be less than 6mm. The tibio-fibular clear space is measured 1cm above the joint line between the lateral border of the posterior tibia and the medial border of the fibula.

syndesmotic injuryThe lateral view does not reveal any obvious posterior malleolar fracture.

A left knee x-ray was obtained to rule out a higher fibular fracture and it revealed a proximal fibular fracture, suggesting a Maisonneuve injury.

Left knee AP viewLeft knee lateral view

CT scan of the ankle done as a part of pre-op work up showed a syndesmotic injury, a comminuted medial malleolar fracture, a medial malleolar tip fracture with associated deltoid ligament avulsion, and a posterior malleolar fracture. The lateral malleolus was intact.

Coronal CT left ankleCoronal CT left ankle 2

This patient underwent ORIF of the medial malleolar fracture and the syndesmotic injury.

Further details on Maisonneuve fracture can be found here.

Any patient with a fracture or ligament injury to the medial ankle should have the entire leg x-rayed to rule out a proximal fibular fracture.

 

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2 thoughts on “Imaging Case of the Week 150 Answer

  1. With a fracture to the distal fibula, wouldn’t pain at the fracture site be the clue something else is going on apart from the ankle pain due to the distal fracture

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    • Hi Mark,

      There is no fracture of distal fibula in this case. In case your question was regarding the proximal fibular fracture, patient may not complain of pain there at all as ankle fracture with gross swelling etc can act as a distracting injury.

      Thank You.
      Prathibha

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