[Biomechanical comparison of three kinds of fixation instruments for calcaneal osteotomy].

To compare the biomechanical characteristics of self-made nickel-titanium shape memory alloy stepped plate with calcaneal plate and cannulated compression screws in fixing calcaneal osteotomy.Calcaneal osteotomy was operated on 6 fresh-frozen lower limbs collected from donors. Then three kinds of fixation materials were applied in random, including the self-made nickel-titanium shape memory alloy stepped plate (group A), calcaneal plate (group B), and cannulated compression screws (group C). Immediately after fixation, axial loading of 20-600 N and 20 N/s in speed was introduced to record the biomechanical data including maximum displacement, elastic displacement, and maximum load. Then fatigue test was performed (5 Hz in frequency and repeat 3 000 times) and the same axial loading was introduced to collect the biomechanical data. Finally, the axial compression stiffness before and after fatigue test were calculated.There was no significant difference in the axial compression stiffness between pre- and post-fatigue test in each group ( P>0.05). However, the axial compression stiffness was significant higher in group A than that in groups B and C both before and after fatigue test ( P<0.05). No significant difference was found between group B and group C ( P>0.05).Self-made nickel-titanium shape memory alloy stepped plate is better than calcaneal plate and cannulated compression screws in axial load stiffness after being used to fix calcaneal osteotomy.通过与跟骨内移钢板、空心拉力螺钉比较，探讨自行设计的镍钛形状记忆合金阶梯钢板固定跟骨截骨的生物力学特性。.取 6 具自愿捐赠的新鲜足部标本，于跟骨处行截骨处理后，随机选择内固定顺序，行镍钛记忆合金阶梯钢板（A 组）、跟骨内移钢板（B 组）、空心拉力螺钉（C 组）固定。固定后行生物力学测试，首先给予 20～600 N 载荷，速度 20 N/s，记录最大位移、弹性位移、最大负荷。随后进行疲劳试验（频率 5 Hz，循环 3 000 次），再给予相同载荷并记录以上指标。计算疲劳试验前、后轴向压缩刚度。.组内比较：3 组疲劳试验前、后轴向压缩刚度比较，差异均无统计学意义（ P>0.05）。组间比较：疲劳试验前、后，A 组轴向压缩刚度均明显大于 B、C 组，比较差异有统计学意义（ P<0.05）；B、C 组间比较差异无统计学意义（ P>0.05）。.镍钛记忆合金阶梯钢板固定跟骨截骨模型后，其抗轴向压缩能力优于跟骨内移钢板及空心拉力螺钉。.