Cheng Yong-Zhong, Yin Xiao-Dong, Chen Yang, Wang Chao-Lu, Liu Guang-Wei, Shi Chang-Long, Huang Xiao-Yu, Chen Yi-Li, Chen Hong-Ying, Wang Xiong-Wei, Zhao Ji-Yang
The First Department of Trauma, Wangjing Hospital, China Academy of Chinese Medical Sciences, Beijing 100102, China.
Beijing Key Laboratory of Bonesetting Technology of Traditional Chinese Medicine, Beijing 100102, China.
Zhongguo Gu Shang. 2024 Dec 25;37(12):1196-201. doi: 10.12200/j.issn.1003-0034.20230702.
To explore weight-bearing stability of Pilon fracture fixed by external fixator.
Six ankle bone models (right side) and 4 pairs (8 ankle cadaver specimens) were selected. Pilon fracture model was prepared by using the preset osteotomy line based on Ruedi Allgower Pilon fracture type. Pilon fracture model was built by using a minimally invasive osteotomy. After ankle bone model and cadaver specimen model were fixed with external fixator, axial load was carried out on mechanical loading machine. After ankle bone model and cadaver specimen model were fixed with external fixator, axial load was carried out on mechanical loading machine. Axial loads of 150, 300 and 450 N were applied to ankle bone model, and displacements of fibula fracture blocks, lateral tibia fracture blocks and medial tibia fracture blocks in three-dimensional space (X, Y and Z axes) were recorded by dynamic capture instrument. Axial loads of 300, 600 and 900 N were applied to ankle cadaver model fixed by external fixator. X-ray films of Pilon fracture cadaver model fixed by external fixator under different loading conditions were taken. The anterior tibial angle, tibial malleolar point angle, talus shift value, talus tilt angle, lateral malleolar shift value, lateral malleolar shift value, medial malleolar separation shift value and articular surface step displacement value were measured under different loads by digimizer software.
After 150, 300 and 450 N axial loads were applied to Pilon fracture models fixed by external fixator, no loosening or fracture of external fixator was observed, and no loosening, fracture or irreversible plastic deformation of Kirschner needle were observed. The displacement values of fibular fracture pieces on X-axis(around) were 0.032 (-0.022, 0.269), 0.061 (-0.002, 0.427), 0.212(-0.016, 1.223) mm, and the displacement values on Y-axis(above and below) were 0.002(-0.031, 0.103), 0.051(-1.133, 0.376), 0.128 (-1.394, 0.516) mm, and displacement values on Z-axis (front and rear) were -0.003 (-0.130, 0.171), 0.137 (-0.076, 0.433), 0.030(-0.487, 0.478) mm;the displacement values of lateral tibial fractures on X-axis were 0.000(-0.108, 0.027), 0.083(-0.364, 0.050), -0.121(-0.289, 0.165) mm, and displacement values on Y-axis were -0.009(-0.200, 0.025), -0.179(-0.710, 0.084), -0.257(-0.799, 0.027) mm, and displacement values on Z-axis were 0.112(-0.024, 0.256), 0.157(-0.068, 0.293), -0.210(-0.035, 0.430) mm;the displacement values of medial tibial fracture block on X-axis were -0.010(-0.060, 0.013), -0.165(-0.289, 0.056), -0.181(-0.395, 0.013) mm, and the displacement values on Y-axis were -0.036(-0.156, 0.007), -0.104(-0.269, 0.178), -0.245(-0.380, -0.011) mm, and displacement values on Z-axis were -0.005(-0.372, 0.189), -0.012 (-1.774, 0.380), 0.200 (-1.963, -0.540) mm. After 300, 600 and 900 N axial loads were applied to Pilon fracture cadaverous models fixed with external fixators, there were no significant difference in anterior tibial angles, angles of malleolar points of tibia, oblique angles of talus, fracture steps, shift values of talus, lateral shift values of lateral malleolus, lateral shift values of medial malleolus, lateral shift values of medial malleolus between under different loading conditions and those without loading (>0.05). No loosening or fracture of external fixator as a whole, loosening, fracture or irreversible deformation of Kirschner needle at the local fixed fracture end occurred.
The early weight-bearing external fixator could maintain stability of fracture end and ankle joint, and the maximum weight is not more than 300 N. In clinical practical application, material characteristics of the implant and type of fracture should be selected.
探讨外固定器固定Pilon骨折的负重稳定性。
选取6个踝关节骨模型（右侧）和4对（8个踝关节尸体标本）。基于Ruedi Allgower Pilon骨折类型，采用预设截骨线制备Pilon骨折模型。通过微创截骨构建Pilon骨折模型。将踝关节骨模型和尸体标本模型用外固定器固定后，在机械加载机上进行轴向加载。对踝关节骨模型施加150、300和450 N的轴向载荷，并用动态捕捉仪记录腓骨骨折块、胫骨外侧骨折块和胫骨内侧骨折块在三维空间（X、Y和Z轴）的位移。对用外固定器固定的踝关节尸体模型施加300、600和900 N的轴向载荷。拍摄外固定器固定的Pilon骨折尸体模型在不同加载条件下的X线片。用digimizer软件在不同载荷下测量胫骨前角、胫骨踝点角、距骨移位值、距骨倾斜角、外踝移位值、外踝移位值、内踝分离移位值和关节面台阶位移值。
对用外固定器固定的Pilon骨折模型施加150、300和450 N轴向载荷后，未观察到外固定器松动或骨折，也未观察到克氏针松动、骨折或不可逆塑性变形。腓骨骨折块在X轴（左右）的位移值分别为0.032（-0.022，0.269）、0.061（-0.002, 0.427）、0.212（-0.016, 1.223）mm，在Y轴（上下）的位移值分别为0.002（-0.031, 0.103）、0.051（-1.133, 0.376）、0.128（-1.394, 0.516）mm，在Z轴（前后）的位移值分别为-0.003（-0.130, 0.171）、0.137（-0.076, 0.433）、0.030（-0.487, 0.478）mm；胫骨外侧骨折在X轴的位移值分别为0.000（-0.108, 0.027）、0.083（-0.364, 0.05）、-0.121（-0.289, 0.165）mm,在Y轴的位移值分别为-0.009（-0.200, 0.025）、-0.179（-0.710, 0.084）、-0.257（-0.799, 0.027）mm，在Z轴位移值分别为0.112（-0.024, 0.256）、0.15（-0.068, 0.293）、-0.210（-0.035, 0.430）mm；胫骨内侧骨折块在X轴位移值分别为-0.010（-0.060, 0.013）、-0.165（-0.289, 0.056）、-0.181（-0.395, 0.013）mm，在Y轴位移值分别为-0.036（-0.156, 0.007）、-0.104（-0.269, 0.178）、-0.245（-0.380, -0.011）mm，在Z轴位移值分别为-0.005（-0.372, 0.189）、-0.012（-（此处原文有误，推测为-1.774）, 0.380）、0.200（-1.963, -0.540）mm。对用外固定器固定的Pilon骨折尸体模型施加300、600和900 N轴向载荷后，不同加载条件下与未加载时相比，胫骨前角、胫骨踝点角、距骨倾斜角、骨折台阶、距骨移位值、外踝外侧移位值、内踝外侧移位值、内踝外侧移位值差异均无统计学意义（P>0.05）。外固定器整体未出现松动或骨折，局部骨折端固定处克氏针未出现松动、骨折或不可逆变形。
早期负重外固定器可维持骨折端及踝关节的稳定性，最大负重不超过300 N。临床实际应用中，应根据植入物材料特性及骨折类型进行选择。
