Zhang Yu, Qin Xiaodong, Song Lijun, Li Xiang
Department of Trauma, the First Affiliated Hospital of Nanjing Medical University and Jiangsu Province Hospital, 300 Guangzhou Road, Nanjing, 210029, China.
BMC Musculoskelet Disord. 2018 Apr 19;19(1):123. doi: 10.1186/s12891-018-1994-x.
For a distal tibial spiral fracture combined with a non-displaced posterior malleolar fragment (PMF), we proposed a hypothesis that the treating surgeon could assess the size of the PMF to determine the need for stabilizing that structure first before rodding the tibia.
Fifty 3-D models (22 females) of combined distal tibial and posterior malleolar fractures from one trauma center were reconstructed. In each case, a virtual tibial intramedullary nail (vIM nail) with three distal anteroposterior (AP) locking screws (S, S and S, the number indicating the distance from the screw to the nail tip) were inserted into the center of the tibial canal and ended on top of the distal tibial physeal scar. Contact between the screws and the PMF was defined as causing PMF displacement. The relationship between PMF secondary displacement and traumatic anatomic factors (the fragment area and height of the PMF) was explored. Then, the parameters were justified by analyzing intraoperative radiographs of 35 cases treated by nail with single locking screw (S) design.
In the analog experiment, multiple logistic regression analysis revealed that the height of the PMF could confidently predict the risk of fragment displacement (S: odds ratio [OR] 1.18, 95% confidence interval [CI] 1.06-1.32; S: OR 1.15, 95% CI 1.05-1.27). Regarding the height of the PMF, the receiver operating characteristic established a cut-off value of 31.2 mm for preliminary fixation of the fragment with 88.89% sensitivity and 88.89% specificity. In the operation group the nail stopped on the top of distal tibial physeal scar, no PMF secondary displacement occurred when the PMF height was less than 31.2 mm. However, the incidence of secondary displacement was 93.33% when the height of the PMF exceeded 31.2 mm.
When the distal tibial physeal scare was set as the limit of nail insertion depth, the height of the PMF could be used as a reliable reference predicting the risk of PMF secondary displacement caused by distal anteroposterior locking screw.
对于胫骨干骺端螺旋骨折合并无移位的后踝骨折块（PMF），我们提出一个假设，即治疗医生可以评估PMF的大小，以确定在对胫骨进行髓内钉固定之前是否需要先对该结构进行稳定固定。
重建了来自一个创伤中心的50例胫骨干骺端和后踝联合骨折的三维模型（22例女性）。在每种情况下，将一枚带有3枚远端前后（AP）锁定螺钉（S、S和S，数字表示螺钉到钉尖的距离）的虚拟胫骨髓内钉（vIM钉）插入胫骨髓腔中心，并止于胫骨干骺端瘢痕上方。螺钉与PMF之间的接触被定义为导致PMF移位。探讨了PMF继发移位与创伤性解剖因素（PMF的骨折块面积和高度）之间的关系。然后，通过分析35例采用单锁定螺钉（S）设计的髓内钉治疗患者的术中X线片对这些参数进行验证。
在模拟实验中，多因素logistic回归分析显示，PMF的高度能够可靠地预测骨折块移位的风险（S：比值比[OR]1.18，95%置信区间[CI]1.06 - 1.32；S：OR 1.15，95% CI 1.05 - 1.27）。就PMF的高度而言，受试者工作特征曲线确定骨折块初步固定的截断值为31.2 mm，灵敏度为88.89%，特异度为88.89%。在手术组中，髓内钉止于胫骨干骺端瘢痕上方，当PMF高度小于31.2 mm时，未发生PMF继发移位。然而，当PMF高度超过31.2 mm时，继发移位的发生率为93.33%。
当将胫骨干骺端瘢痕作为髓内钉插入深度的界限时，PMF的高度可作为预测远端前后锁定螺钉导致PMF继发移位风险的可靠参考指标。
