The utilization of intraoperative contralateral ankle images for syndesmotic reduction.

Abstract

To evaluate the variability in ankle syndesmotic morphology on contralateral ankle fluoroscopic images and the reductions obtained utilizing these images. A retrospective cohort study was performed at a level one trauma center including 46 adult patients undergoing operative fixation of malleolar ankle fractures that also had anteroposterior (AP) and lateral fluoroscopic images of the uninjured contralateral ankle intraoperatively. Contralateral and post-fixation fluoroscopic images were used to measure the tibiofibular clear space (TFCS) as a proportion of the superior clear space (SCS) on mortise images and the posterior tibiofibular distance (PTFD) as a proportion of the lateral superior clear space (LSCS) on lateral images. Differences between contralateral and post-fixation ankle measurements were compared between those patients with syndesmotic injuries and those without (control group). The mean TFCS/SCS and PTFD/LSCS ratios measured on contralateral ankle images were 1.2 (95% confidence interval (CI) 1.1 to 1.3; range 0.7 to 1.8) and 1.8 (95% CI 1.5 to 2; range 0.5 to 3.4). The mean difference between the contralateral and post-fixation TFCS/SCS and PTFD/LSCS in patients with and without syndesmotic fixation was 0.07 vs. 0.13 (F-ratio 0.3, p = 0.5) and -0.2 vs 0.5 (F ratio 5.2,  p= 0.02). Contralateral syndesmotic measurements varied widely and the utilization of these images allowed for syndesmotic reductions with similar measurements. Intraoperative contralateral ankle images should be considered to assess syndesmotic reduction.