后踝骨块占胫骨穹窿比例的X线和CT三维重建结果的相关性研究

Correlation between plain radiographs and three-dimensional reconstruction on measurements of proportion of posterior malleolar fragments to tibial plafond

目的探讨累及穹窿的后踝骨块占胫骨穹窿比例的X线和CT三维重建结果的相关性。方法回顾性分析2013年6月至2014年12月手术治疗的27例累及胫骨穹窿的后踝骨折患者资料，男10例，女17例；年龄15-70岁，平均48．9岁；三踝骨折14例，双踝骨折11例，单纯后踝骨折2例；Lauge—Hansen分型：旋后外旋型22例，旋前外旋型1例，旋前外展型2例，未纳入分型系统2例；AO／OTA分型：B型22例，C型3例，未纳入分型系统2例；Haraguchi分型：Ⅰ型15例，Ⅱ型12例；三角韧带深层断裂2例；下胫腓联合损伤3例。在侧位X线片上测量后踝骨块上穹窿宽度和余下穹窿宽度，计算后踝骨块上穹窿宽度与总穹窿宽度的比值；建立三维CT重建模型，测量后踝骨块上穹窿面积和余下穹窿面积，计算后踝骨块上穹窿面积与总穹窿面积的比值，评价这两个比值的相关性。结果27例患者的后踝骨块上穹窿宽度与总穹窿宽度比值为11．86％-52．24％，平均31．10％；后踝骨块上穹窿面积与总穹窿面积比值为5．86％-35．22％，平均20．13％；后踝骨块上穹窿宽度与总穹窿宽度的比值和后踝骨块上穹窿面积与总穹窿面积的比值无相关性（r=0．350，P=0．073）。结论对累及胫骨穹窿的后踝骨折的病例，通过X线片测量和计算后踝骨块上穹窿宽度与总穹窿宽度的比值不能代表CT三维重建测量和计算的后踝骨块上穹窿面积与总穹窿面积的比值，且通过X线片测量和计算高估了后踝骨块占总穹窿的比例。根据X线片评估累及穹窿的后踝骨块占胫骨穹窿比例不能作为临床判断是否需要固定后踝骨块的可靠依据。

Objectivev To investigate the- correlation between plain radiographs and three-dimensional reconstruction on measurements of proportion of posterior malleolar fractures to tibial plafond. Methods From June 2013 to Dec. 2014, data of 27 patients with posterior malleolar fractures involving the tibial plafond who had undergone surgical treatment were retrospectively analyzed. There were 10 males and 17 females. The mean patient age was 48.9 years （range, 15-70 years）. There were 14 cases of trimalleolar fracture, 11 of bimalleolar fracture and 2 cases with only posterior malleolar fracture. According to the Lauge-Hansen classification system, there were 22 cases of supination-external rotation, 1 of pronation-external rotation, 2 of pronation-abduction and 2 of unclassified type. According to the AO/OTA classification system, there were 22 cases of B, 3 of C and 2 of unclassified type. According to the Haraguchi classification system, there were 15 cases of type I and 12 of type II. There were 2 cases with the deep deltoid ligament disrupted and 3 cases with the inferior tibiofibular syndesmosis injury. The width of the posterior plafond fragment （PPF） and the remaining plafond fragment （RPF） were measured on the lateral plain radiograph. After 3D reconstruction was established, the area of the PPF and the RPF was measured. The width ratio of the PPF and the total plafond fragment （TPF） and the area ratio of the PPF and the TPF were calculated. Results The width ratio of the PPF and the TPF was 31.10% （range, 11.86%-52.24%）, the area ratio of the PPF and the TPF was 20.13% （range, 5.86%-35.22%） and the correlation coefficient （r） between the width ratio of the PPF and the TPF and the area ratio of the PPF and the TPF was no statistically significant （r=0.350, P= 0.073）. Concusion The width ratio of the PPF and the TPF could not represent the area ratio of the PPF and the TPF in the patients with the posterior malleolar fracture who＇s fracture line involved the plafond, and the ratio could be overrated in the lateral X- rays measurements. According to the plain radiographs, the evaluation of the proportion of posterior malleolar fragments to tibial plafond could not be as a reliable criterion for internal fixation of the posterior malleolar fragments.