Pilon fractures

Last evidence check Nov 2013

Two main classifications are used, which use different criteria for grouping. A new CT-based classification from Bristol builds on the work of Tournetta and offers important new insights.

Ruedi/Allgower classification

Ruedi and Allgower described three groups based on the size and displacement of articular fragments:


I - no comminution or displacement of joint fragments


II - some displacement but no comminution or impaction


III - comminution and/or impaction of the joint surface

AO classification

The AO long bone group universal classification of fractures groups distal tibia fractures as 43. The first sub-grouping is on the degree of cntinuity between diaphysis and metaphysis:

ao a

AO group A - extra-articular fracture

ao b

AO group B - partial articular fracture

ao c

AO group C - complete articular fracture

There are sub-classifications of each of these groups - the most important being the group C fractures:

Both Martin (1997) and Swiontowski (1997) found moderate reproducibility at the A-B-C level but it was poorer at the subgroup level.

Luk (2013) compared pilon fracture types in patients with and without an intact fibula. When the fibula was intact, 58% of fractures were partial articular type B. When the fibula was fractured, nearly 70% were type C complete articular fractures and over half were type C3, the most comminuted.

Topliss classification

Topliss et al (2005) re-examined the anatomy of pilon fractures based on plain radiography and CT. The paper should be read in detail - important points include:


sagittal fracture family

posterior coronal fracture family

anterior coronal fracture family


post coronal
ant coronal


post coronal2
ant coronal2

Topliss compared the reproducibility of their grouping with division into AO "B" and "C" groups. The Topliss classification was more reproducible, especially in the hands of Topliss herself, although no statistical analysis is provided. A diagram summarising fracture alignments is provided, which implies very few fracture lines in intermediate positions between the coronal and sagittal families - it would be valuable to reproduce this in a different data set.

Tang (2012) proposed a four-column classification which has some similarities to the Topliss classification but omits central fragments. The authors describe how this influences surgical approach but the data do not clarify this and the classification may need some further development to make a distinct contribution to decision making.