Review Question - QID 4896

This patient has anteromedial marginal impaction seen on CT scans. This is characteristic of a supination-adduction ankle fracture (Figure D).

In the Lauge-Hansen classification, ankle fractures are classified into supination-adduction (SA), supination-external rotation, pronation-abduction, pronation-external rotation. Certain considerations exist when treating SA fractures with marginal impaction: (1) An anteromedial approach will aid in visualizing and reducing the impaction (instead of standard medial approach). (2) Disimpaction of the articular fragment and possibly bone grafting of the resulting defect may be necessary rather than simple percutaneous fixation.

McConnell et al. reviewed marginal plafond impaction in supination adduction injuries. Supination-adduction injuries comprised 5% of 500 fractures (44 fractures), and 42% (8 fractures) of these had marginal impaction.

Illustration A is another example of a SA fracture depicting vertical fracture of the medial malleolus in association with marginal impaction of the plafond (arrow). Illustration B is an axial CT showing increased density at the level of the subchondral bone, characteristic of anteromedial marginal impaction. Illustration C is a coronal CT showing showing articular depression of the impacted segment and tibiotalar incongruity.

Incorrect Answers:
Answer 1: Figure A shows a pronation-abduction ankle fracture.
Answer 2: Figure B shows a talar body fracture.
Answer 3: Figure C shows a pronation-external rotation ankle fracture
Answer 5: Figure E shows a supination-external rotation ankle fracture.
Marginal impaction is not characteristic of these injuries.