In five years, approximately 800 ankle fractures were seen at the authors' institution, forty-four (5 percent) of which were of the supination-adduction pattern. Nineteen of these injuries had displaced vertical medial malleolus fractures, of which eight (42 percent) showed marginal impaction of the tibial plafond. All eight patients underwent open reduction and internal fixation with elevation of the impacted articular component and had good to excellent functional outcome with no arthritis on radiograph at the time of the most recent follow-up. The index of suspicion of marginal impaction of the tibial plafond should be high when treating supination-adduction pattern ankle fractures with displaced medial malleolus.