Posterior malleolar fractures are relatively common and usually result from rotational ankle injuries. Although treatment of associated lateral and medial structures is well established, several controversies exist in the management of posterior malleolus fractures. We performed a systematic review of the current published data with regard to the diagnosis, management, and prognosis of posterior malleolus fractures. A total of 33 studies (8 biomechanical and 25 clinical) with >950 patients were reviewed. The outcome of ankle fractures with posterior malleolar involvement was poor; however, the evidence was not enough to prove that the size of the posterior malleolus affects the outcome. Significant heterogeneity was noted in the cutoff size of the posterior malleolar fragment in determining management. The outcome was related to other factors, such as fracture displacement, congruency of the articular surface, and residual tibiotalar subluxation. Indirect evidence showed that large fracture fragments were associated with fracture dislocations and ankle instability and, thus, might require surgical fixation. We have concluded that the evidence to prove that the size of the posterior malleolar affects the outcome of ankle fractures is not enough, and the decision to treat these fractures should be determined by other factors, as stated previously.