踝关节骨折术后下胫腓联合复位不良的X线评估

X-ray assessment of syndesmotic malredcution following ankle fracture

目的 评估不同X线投照体位对下胫腓联合复位不良的诊断作用.方法 纳入2012年8月至2014年8月踝关节骨折合并下胫腓联合损伤术后患者共31例,男27例,女4例;年龄24～56岁,平均35.7岁.所有患者均在就诊时摄踝关节正、侧位及踝穴位X线片,并行双侧踝关节CT检查（扫描层厚为2 mm,图像分辨率为512×512 matrix）.在正位X线片上测量下胫腓联合间隙（APTCS）、下胫腓联合重叠（APTFO）,侧位X线片上测量腓骨后移距离（FPT）,踝穴位X线片上测量内外侧踝穴等宽,CT上测量腓骨前后缘相对下胫腓联合切迹的距离.以CT判定下胫腓联合复位不良（G值）为“金标准”,判定不同X线投照体位的诊断效能.结果 31例患者中共9例患者诊断为下胫腓联合复位不良.复位不良患者的APTFO、FPT与正常复位患者比较差异有统计学意义（P＜0.05）.复位不良患者的APTCS与正常复位患者比较差异无统计学意义（t=-1.328,P=0.194）.以CT的G值为诊断复位不良诊断的“金标准”,APTCS诊断复位不良的敏感性为81.8％,特异性为55.6％,假阳性率为44.4％,假阴性率为18.2％.APTFO诊断复位不良的敏感性为81.8％,特异性为66.7％,假阳性率为40.0％,假阴性率为18.2％.FPT诊断复位不良的敏感性为100％,特异性为77.8％,假阳性率为22.2％,假阴性率为0.内外侧踝穴等宽诊断复位不良的敏感性为90.9％,特异性为75.0％,假阳性率为9.1％,假阴性率为25.0％.结论 相对于CT诊断的G值标准,踝关节正位X线片上APTCS对下胫腓联合复位不良的诊断假阳性率较高,踝关节侧位X线片上FPT对下胫腓联合复位不良具有较好的诊断敏感性.但上述影像学诊断方法仍具有一定的局限性.

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.