Pathoanatomy and Associated Injuries of Posterior Malleolus Fracture of the Ankle.

Abstract

We present a classification system that progresses in severity, indicates the pathomechanics that cause the fracture and therefore guides the surgeon to what fixation will be necessary by which approach. The primary posterior malleolar fracture fragments were characterized into 3 groups. A type 1 fracture was described as a small extra-articular posterior malleolar primary fragment. Type 2 fractures consisted of a primary fragment of the posterolateral triangle of the tibia (Volkmann area). A type 3 primary fragment was characterized by a coronal plane fracture line involving the whole posterior plafond. In type 1 fractures, the syndesmosis was disrupted in 100% of cases, although a proportion only involved the posterior syndesmosis. In type 2 posterior malleolar fractures, there was a variable medial injury with mixed avulsion/impaction etiology. In type 3 posterior malleolar fractures, most fibular fractures were either a high fracture or a long oblique fracture in the same fracture alignment as the posterior shear tibia fragment. Most medial injuries were Y-type or posterior oblique fractures. This fracture pattern had a low incidence of syndesmotic injury. The value of this approach was that by following the pathomechanism through the ankle, it demonstrated which other structures were likely to be damaged by the path of the kinetic energy. With an understanding of the pattern of associated injuries for each category, a surgeon may be able to avoid some pitfalls in treatment of these injuries. Level III, retrospective comparative series.