不同跖屈角度对踝三角韧带损伤X线诊断的影响

目的 评估踝关节不同跖屈角度对踝三角韧带损伤X线诊断的影响,提高踝三角韧带损伤诊断的准确率.方法 自2010年2月至2010年12月收治踝关节旋后-外旋型骨折患者24例,均为腓骨远端骨折但无内踝骨折.所有患者外翻应力下分别取中立位0°、跖屈位15°、30°、45°拍摄踝穴位X线片,并行患侧踝关节MRI检查.对不同跖屈角度下四组患者X线片内侧踝穴宽度(medial clear space,MCS)及胫距上关节宽度(superior clear space,SCS)进行测量.测量结果采用单因素方差分析LSD-t检验,分别以(1)MCS≥4 mm,且MCS＞ SCS,(2)MCS≥5 mm,且MCS＞ SCS作为踝三角韧带损伤X线诊断的标准,踝关节MRI检查结果作为诊断“金标准”,进行诊断性试验研究.结果 外翻应力下踝关节中立位0°、跖屈位15°、30°、45°时,MCS测量结果分别为(4.10±0.79)mm、(4.55±0.72)mm、(4.99±0.56)mm、(5.71 +0.86)mm,组间比较差异有统计学意义(P＜0.05)；SCS测量结果分别为(3.56±0.41)mm、(3.50±0.43)mm、(3.71±0.44)mm、(3.93±0.51)mm,组间比较差异无统计学意义(P＞0.05)；以MCS≥4 mm,且MCS＞SCS作为诊断标准时,中立位0°、跖屈位15°、30°、45°时,出现假阳性率分别为50.0％、66.7％、88.9％、94.4％.以MCS≥5 mm,且MCS＞ SCS作为诊断标准时,中立位0°、跖屈位15°、30°、45°时,出现假阳性率分别为5.6％、11.1％、38.9％、77.8％.结论 不同跖屈角度是影响踝三角韧带损伤X线诊断的重要因素,随着踝关节跖屈角度增加,踝三角韧带损伤X线诊断的假阳性率亦随之升高.

Influence of different plantar flexion angle on X-ray diagnosis of deltoid ligament injury

Objective To improve the accuracy of X-ray diagnosis of the deltoid ligament injury by evaluating the influence of plantar flexion on the diagnosis.Methods Twenty-four patients with ankle supination-extemal rotation fracture which was distal fibula fracture but no medial malleolus fracture were treated from February 2010 to December 2010.All the patients were taken Mortise radiograph with the ankle in four positions of plantar flexion(0°,15°,30° and 45°)applied with rotational stress and the deltoid ligament injury was identified with MRI.The medical clear space(MCS)and the superior clear space(SCS)on each radiograph were measured.The results were tested by a one-way analysis of variance model(ANOVA),based on the following criteria:(1)the MCS≥ 4 mm and MCS ＞ SCS,or when MCS≥5 mm and MCS ＞SCS.The MRI examination was taken as the "gold standard" to compare the influence of X-ray diagnosis of the deltoid ligament injury with different plantar flexions and different standards.Results The average MCS in four positions of plantar flexion(0°,15°,30°,and 45 °)with rotational stress were(4.10 ±0.79)mm,(4.55 ±0.72)mm,(4.99 ±0.56)mm and(5.71 ±0.86)ram,with statistical difference(P ＜0.05).The average SCS in four positions of plantar flexion(0°,15°,30°,and 45°)were(3.56 ±0.41)mm,(3.50 ±0.43)mm,(3.71 +0.44)mm and(3.93 ±0.51)mm,with no statistical difference in the four groups(P ＞0.05).With the MSC≥4 mm and MSC ＞ SCS as the diagnostic criteria,the prevalence of false-positive findings of deltoid injury based on the ratio with the four positions of plantar flexion(0°,15°,30° and 45°)were 50.0％,66.7％,88.9％ and 94.4％ respectively.With the MSC≥5 mm and MSC ＞SCS as the diagnostic criteria,the prevalence of false-positive findings of deltoid injury based on the ratio with the four positions of plantar flexion(0°,15°,30° and 45°)were 5.6％,11.1％,38.9％ and 77.8％ respectively.Condusions Different plantar flexion angle is an important factor for X-ray diagnosis of deltoid ligament injury of the ankle joint.The prevalence of false-positive findings of deltoid injury increases with the increase of plantar flexion.