Acute posterior dislocation of the sternoclavicular (SC) joint is rare but can lead to life-threatening vascular injuries of the mediastinum; however, diagnosis is difficult and the injury can be initially overlooked so that surgical treatment is delayed. Although a variety of different treatment modalities have been published, the ideal fixation technique has not yet been identified. We report the case of a patient suffering from a locked posterior SC joint dislocation caused by a skiing accident. The injury was treated by transarticular endobutton fixation. This article describes the technique and highlights its advantages and disadvantages in comparison to previously published treatment options.