中文摘要：

目的：通过生物力学及有限元分析法，了解大块后踝骨折不同程度复位对胫距关节接触情况的影响。方法：从收集的16具标本中随机选取6具成人新鲜小腿一足标本。用DDL试验机按照中立位、背屈100和跖屈15°的不同加载力度，并通过Tek—Scan关节压敏片相关法分析正常状态、后踝骨折、1mm台阶、2mm台阶、1mm间隙、2mm间隙时，胫距关节的接触面积、接触压强和峰值压强。构建踝关节三维有限元模型，并模拟相关生物力学工况。结果：正常胫距关节中立位500N时接触面积为（4．94±0．67）cm2，胫距关节的接触力度为加载力度的（83．4±2．7）％。后踝骨折固定1mm间隙时，预设加载均无统计学意义；1mm台阶时，仅跖屈15°加载时差异有统计学意义（P〈0．05）；2mm台阶和2mm间隙时，在多种预设加载下差异均有统计学意义（P〈0．05）。有限元分析的趋势结果与相关生物力学研究一致。结论：对于大块后踝骨折应尽量解剖复位。如存在复位困难，也应该将骨折块移位控制在1mm台阶和2mm间隙以内，如此可基本恢复踝关节的接触协调性。

英文摘要：

Objective： To observe the influence of hunk posterior malleolus fracture （PMF） on contact area of tibiotalar joint （＇ITJ） by biomechanical study and finite element analysis （FEA）. Methods： Six fresh adult cadaveric calf-foot specimens were selected randomly, then fixed the specimens on the DDL test machine and placed Tek-Scan ankle joint pressure testing slices after cut-off posterior ankle joint capsule. After that, the loading test was carried out in neutral position, dorsiflexion 10° and plantar flexion 15°, and the contact area, pressure and peak of TYJ at the normal condition, PMF, lmm and 2 mm step fixation, lmm and 2 mm gap fixation were measured and analyzed. Also, a FEA model of ankle joint was established and corre- lated data of the biomechanical study were evaluated. Results： The contact area of TI＇J at 500N neutral po- sition was （4.94±0.67） cm2 and the contact pressure of TYJ was （83.4±2.7）% of the total loading. A signifi- cant difference wasn＇t noted in lmm gap fixation and noted in lmm step fixation only at 15° plantar flex- ion （P〈0.05）. But, there was a significant difference at 2mm gap and 2mm step fixation of PMF （P〈0.05）. And the result of FEA was conformed to the biomechanical study. Conclusion： Surgeons should try to re- duce the hunk PMF anatomically, if really can＇t, fracture fragments displacement should be limit within lmm step and 2mm gap, so which can recover the contact concordant of ankle-joint.