Evaluation of distal tibia slope in pilon fractures after surgical fixation

Alteration of sagittal alignment during fracture fixation directly impacts ankle motion in dorsiflexion and plantarflexion. Previously research measured the anterior distal tibia angle (ADTA) in a normal healthy population. The null hypothesis for this study is that ADTA is restored to normal range following unstable pilon fractures. The aim of this study is to identify the range of the ADTA in distal tibia fractures after surgical fixation, compared to a previously published normal population.

A retrospective review of operative distal tibia fractures (AO/OTA classification 43A and 43C - 43B were excluded due to lower likelihood of fracture changing the ADTA) was performed. ADTA on lateral radiograph was measured as the angle relative to the tibia shaft.

100 patients with post-operative radiographs that met inclusion criteria were analyzed. The average ADTA was 6.9° (⌠=4.62°) with a maximum slope of 19.2° (i.e. anterior orientation) and a minimum of -3.3° (i.e. posterior orientation). The uninjured population had an average ADTA of 6.0° (range -2.0°-14°, ⌠=3.0°).

This analysis shows the average distal tibia sagittal alignment in the post-surgical group is similar to a normal, uninjured population. Large alterations in ADTA would directly impact the ankle in the plane of motion (i.e. negative ADTA would decrease ankle dorsiflexion). Considering ADTA as an objective intra-operative parameter optimizes sagittal plane alignment.