胸椎半侧骨骺加压矫形钉最大拔出力的实验研究

Research of the peak force of pullout about different thoracic hemiepiphyseal compression staples in animal

目的通过山羊半侧骨骺加压矫形钉拔出力的测定,评价不同材料或同一材料不同型号矫形钉的初始稳定性。方法根据6具2～3个月龄山羊胸椎 T_6～T_(11)节段椎体标本的测量数据,设计1种齿间距离为10.0 mm 的不锈钢矫形钉和3种原始齿间距离分别为5.0、6.5、8.0 mm 记忆合金矫形钉。选其中4具标本,每具截成 T_6～T_7、T_8～T_9、 T_(10)～T_(11)三个脊柱功能单位(FSU),重新分配,在每个 FSU 双侧先后置入不锈钢矫形钉和记忆合金矫形钉,分成4组:不锈钢钉组、5.0 mm 记忆合金钉组、6.5 mm 记忆合金钉组、8.0 mm 记忆合金钉组,通过858型生物力学实验机测定矫形钉的最大拔出力。结果 4组矫形钉的最大拔出力均值分别为:不锈钢钉组(20.62±9.15)N,5.0 mm 记忆合金钉组(74.18±8.81)N,6.5 mm 记忆合金钉组(51.28±5.44)N,8.0 mm 记忆合金钉组(39.13±7.54)N,组间比较存在显著性差异(P<0.01);不锈钢钉组最大拔出力小于其他组。结论不同材料的矫形钉初始抗拔出性能不同,记忆合金矫形钉的抗拔出性能优于不锈钢矫形钉。同时,记忆合金矫形钉的抗拔出性能也因其设计不同而不同,原始齿尖距离越小,所需最大拔出力越大。

Objective To evaluate the initial dislocation resistance of the pullout force of different material or different type of goats thoracic hemiepiphyseal compression staples. Methods According to the measuring anatomic data of thoracic vertebra（T6 -T11 ） specimens in goats（ age 2 -3 months）, we designed stainless steel staple whose original distances between two opened prone were 10 mm and three kinds of shape memory alloy （SMA） staples whose original distances between two opened prone were respectively 5.0,6. 5 and 8. 0 mm. Four specimens were used and each was cut into three functional spinal units （FSU） of T6 - T7 ,T8 -T9 and T10 -T11, then FSU were redistributed. Stainless steel staples and SMA staples were implanted into both sides of FSU. There were four groups ： group I was stainless steel staples, group Ⅱ was SMA of 5. 0 mm. grouplll was SMA of 6. 5 mm. groupiv was SMA of 8.0 mm. The peak force of pullout in each FSU was measured on 858 biomechanical test machine. Results The peak force of group Ⅰ was （ 20. 62 ± 9. 15 ） N, group Ⅱ was （74. 18 ± 8. 81 ） N, group Ⅲ was （ 51.28 ± 5.44 ） N, group IV was （ 39. 13 ±7. 54）N. It is found that there were statistically different between all groups （P 〈 0. 05 ）. The peak force values of group I were lowest than others. Conclusions Differences of the initial dislocation resistance in different materials. SMA staples exhibit higher pullout force. Meanwhile, the pullout forces were also different between SMA staples, the smaller original distance the higher peak force of pullout.