The goal of open reduction and internal fixation (ORIF) of bimalleolar ankle fractures is to reconstitute ankle anatomy. The most commonly used radiological parameters to assess adequacy of reduction are talocrural angle (TCA), medial clear space (MCS), tibiofibular overlap (TFO) and tibiofibular clear space (TFCS). There is little research about the radiological outcomes of surgery in bimalleolar fractures. We aimed at assessing the adequacy of ORIF and the factors involved in anatomical restoration (specifically time to surgery), postoperatively and at follow-up.

TCA, MCS, TFO and TFCS were measured in preoperative and postoperative radiographs of 107 bimalleolar ankle fractures and in 83 follow-up radiographs, accounting for a total of 297 radiographs and 1182 measurements. Preoperative radiographs were categorized according to Danis-Weber classification. For all included cases, basic demographic data, dates of radiographs and surgery, and type of fixation used were acquired. Variables associated with postoperative and follow-up total anatomical reconstitution (i.e., when the four assessed radiological parameters were normalized), normalization of each radiological parameter, and improvement in the number of normalized radiological parameters were identified through univariable Cox regression analysis.

In our sample, 23.8% of the ankle fractures in postoperative radiographs and 28% in follow-up radiographs achieved a complete anatomical restoration. Type C fractures (hazard ratio [HR]=0.1, 95% confidence interval [CI]=0.02–0.7, P=0.021) were associated with lower chances of total anatomical reconstitution. The use of reconstruction plates (HR=0.1, 95% CI=0.03–0.7, P=0.014) and one third tubular plates (HR=0.2, 95% CI=0.03–0.8, P=0.026) decreased the chances of improving the number of normalized radiological parameters. Waiting days until surgery impaired total anatomical reconstitution (HR=0.8, 95% CI=0.6–0.9, P=0.012) and also reduced the chances of improving the number of normalized radiological parameters (HR=0.9, 95% CI=0.9–1.0, P=0.045).

The radiological results for the treatment of bimalleolar fractures are time sensitive, and surgery should thus be performed as soon as possible, using adequate fixation materials, in order to achieve a better restoration of ankle anatomy.

IV, retrospective study.