X-ray assessment of syndesmotic malredcution following ankle fracture

Abstract

Objective To evaluate diagnostic efficacy of various X-ray films for syndesmotic malreduction following ankle fracture.Methods Thirty-one patients with ankle fracture combined with injury to the distal tibiofibular syndesmosis from August 2012 to August 2014 were reviewed in this study.They were 27 males and 4 females,24 to 56 years of age (mean,35.7 years).At diagnosis,all the patients took anterioposterior,lateral and mortise X-ray films,and bilateral CT scan (2 mm slice,512 × 512 matrix) of the ankle.Tibiofibular space (APTCS) and tibiofibular overlap (APTFO) were measured on the anterioposterior films,fibular posterior transfer (FPT) was measured on the lateral films,mortise widening on the mortise films,and distance from fibular anterior-posterior edge to syndesmosis (G value) were measured on the CT scans.Comparisons were conducted between the X-ray films to evaluate their diagnostic efficacy for syndesmotic malreduction,with G value as a golden standard.Results Of the 31 patients,9 were diagnosed with syndesmotic malreduction.There were significant differences in APTFO and FPT values between the malreduction patients and anatomical reduction ones (P ＜ 0.05) but no significant difference in APTCS (t =-1.328,P =0.194).Judged by the G value as the golden standard,APTCS had a sensitivity of 81.8％,a specificity of 55.6％,a false positive rate of (FPR) 44.4％,and a false negative rate (FNR) of 18.2％.For APTFO,the above-mentioned rates were 81.8％,66.7％,40.0％ and 18.2％.The above diagnostic indexes for FPT were 100％,77.8％,22.2％ and 0,and for mortise widening were 90.9％,75.0％,9.1％ and 25.0％ respectively.Conclusions Compared with CT scanning,APTCS on the anterioposterior films may have a higher false positive rate in diagnosis of syndesmosis malreduction while FPT on the lateral films may have a better diagnostic sensitivity.However,X-ray films are not capable enough of diagnosing syndesmosis malreduction. Key words: Ankle fracture; Fractures, bone; Radiography; Syndesmosis malreduction