A systematic review of posterior pilon variant fractures

Abstract

Posterior pilon variant ankle fractures (PPVF) are a unique subtype of posterior malleolar fractures which have been a source of controversy and confusion in recent years. There has not been a thorough literature review previously written on the topic. Database searches of PubMed and Embase were conducted from inception until June 2023. The key words included "pilon variant," "posterior pilon variant," and "posterior pilon" fractures. Outcomes were evaluated by union time, rates of delayed union, nonunion, malunion, and complication. A total of 15 articles relevant to surgical repair of pilon variant fractures were included in the literature review. The unique mechanism of injury has been reported to involve both rotational and axial forces, leading to involvement of the posterior and medial aspects of the distal tibia. Pilon variant fractures can be suspected by several characteristics on radiographs and have a high confirmation rate via CT images. Multiple systems have been proposed to classify this fracture pattern, but there is no consensus on the ideal classification system. Surgically, direct fixation has shown better short-term clinical outcomes versus indirect fixation or no fixation. PPVF have a distinct fracture pattern involving the posterior and medial columns of the distal tibial plafond, and results from a mechanism intermediate to rotational and axial forces. These fractures are more severe than tri-malleolar fractures due to increased rates of articular impaction and incongruity. Future classification systems should focus on joint surface area and the tibial pilon column involved to avoid confusion with less severe posterior malleolar fractures.

Keywords: Ankle fracture; Pilon variant; Posterior malleolar fracture; Posterior pilon; Posterior pilon variant; Tri-malleolar fracture.

Fig. 1

Prisma flowchart for systematic review process.

Fig. 2

A cross-sectional representation of the Zhang et al Classification System (Zhang et al. Medicine (2019) 98:3). The illustrations are a cross section of the distal aspect of the right tibia and fibula. Orientation and location of cross section are indicated in the lower left corner. Zhang type 1, 2a, and 2b are fractures involving only the posterior malleolus, with more severe subtypes indicating a greater degree of fragmentation. Type 3a involves a single fracture fragment that exits from the anteromedial aspect of the tibia, anterior to the anterior colliculus of the medial malleolus. Type 3b is the most severe, with an additional fracture line through the intercollicular groove, separating the anterior colliculus of the medial malleolus from the posterior fragment that is composed of the posterior malleolus and the posterior colliculus of the medial malleolus. Reference illustration indicating the level of the cross section created with BioRender.com.