The indications for stabilization of the posterior malleolus (Volkmann triangle) while fixing ankle fractures are controversially discussed. Detailed descriptions of possible obstacles to reduction are scarce. The following case describes the difficulty of reduction of the posterior malleolus caused by interposition of the flexor digitorum longus tendon. The fracture line of the posterior malleolus passed in an atypical manner vertically to the posterior-medial tibial margin with direct contact to the anatomical pathway of the tendon. The impaction of the tendon was already present in the computed tomography (CT) scan taken preoperatively but the tendon hindering malleolar reduction was first realized during surgery after several unsuccessful attempts at repositioning.