Ankle Injury- Weber B

Nice oblique fracture of the distal fibula that extends between the anterior and posterior tib-fib syndesmotic ligaments (level of the yellow marker).  So we already know it's a trans-syndesmotic fracture = Weber B or Supination Ext Rotation (SER) Lauge Hansen. 

Next our eyes should be looking for evidence of an injury at the medial mortise, bony AND/OR ligamentous.  I don't see a fracture at the typical location at the medial mal (blue line).  But I would say that the medial clear space is prominent compared to the superior joint space (should be equidistant).  Might be nice to do some more testing....

As for the lateral, we can see the oblique nature of the distal fib fracture extending between the ant and post tib-fib ligaments with some mild offset at the cortex (red arrows).  Always try to look through the tibia at the fibular contour on lateral radiograph, might the most conspicuous view of the fracture. 

Also look for that posterior mal fx, which is typically vertical oriented through the posterior margins of the joint (blue line). 

As for the further testing of the medial ankle stability, you can recommend gravity stress views to see if that deltoid ligament is still hanging on.  

Even though there is upper limits of normal widening and it's possibly partially injured, it's not radiographically disrupted until 6 mm. These is enough structural integrity to call this stable. 
Stage 2 Weber B (SER) - Stable.  

The Blown-Up Version of the same SER mechanism below. Stage 4 Weber B - Unstable

Just like the picture but without the blood spurts!

If you look through the jumbled bones, you can see the posterior mal fracture on the lateral (arrow at the superior margin of the fracture line)

More discussion about the Weber classifications in the article below!

https://radiologyassistant.nl/musculoskeletal/ankle/weber-and-lauge-hansen-classification