Missed Fractures III

How do you rip off the lateral process of your talus? 

This post is part III in our “missed fractures” series. Welcome back! 

To use non-medical terms, the talar process is a wedge-shaped prominence on the talar bone, which makes up part of the ankle joint. This is the area of concern with 15-year-old Luke, who was snowboarding yesterday at Vail Mountain Resort in Colorado. 

Luke is now complaining of pain with range of motion in his left ankle, and he reports tenderness with palpation about 1 cm below his lateral malleolus (ankle bone). Luke’s mom tells you that she thinks his complaints of pain and limping are dramatic because he has a test at school tomorrow and there was no fall or trauma event at the ski resort yesterday. 

However, there is some bruising and swelling around Luke’s ankle, so an x-ray is ordered. (See photo above on the left.) Anything there? 

No, there are no visible fractures. But what is the pretest probability in this case? Very high! High enough to get a CT. The CT image on the right vividly shows that the lateral process of Luke’s talus has been torn off. 

Talar process fractures are frequently missed: 33-41% of them are overlooked initially. They are difficult to diagnose because they mimic sprain injuries. However, if they are missed on the initial exam, chronic inflammation and pain may develop, along with non-union of the bone and arthritis of the ankle joint. 

If there is < 2 mm displacement of the talar process from the talus bone, patients need 6 weeks of immobilization and no weight-bearing on the affected extremity. If there is > 2 mm of displacement, surgical intervention is needed. 

In conclusion, let’s answer our initial question. There must be high suspicion for a talar process fracture when tenderness is present just below the lateral ankle bone, an x-ray is negative, and the patient was recently snowboarding. This is a classic snowboarder’s fracture. You really only get it snowboarding or some other mechanism where you land a significantly high jump with your feet immobilized in very slight internal rotation (can you think of how this would occur other than with snowboarding?). That is how you rip off the lateral process of your talus. When the mechanism is there, don’t stop with an x-ray. Get a CT!