山羊胸椎半侧骨骺加压矫形钉体外力学测试研究

Mechanical test in vitro of thoracic hemiepiphyseal compression staples in goats

目的：设计符合我国山羊椎体的胸椎半侧骨骺加压矫形钉，对其进行力学测试。方法：根据10具2—3个月龄山羊脊柱标本的椎体测量结果，应用记忆合金材料设计3种型号矫形钉并分成3组：I组5mm、11组6．5mm、111组8mm，通过脊柱三维运动实验机测定最大回复力。同时选4具标本，每具截成T6～T7，偈～四，T10-T11三个脊柱功能单位（FSU），随机分配，在每个FSU双侧先后植入3种矫形钉，测定其最大拔出力。结果：5mm组、6．5mm组、8mm组矫形钉的最大回复力分别为138．73±12．05N、119．65±16．34N和96．95±18．27N，两两比较存在统计学差异（P〈0．05）。最大拔出力分别为：74．18±8．81N、51．28±5．44N和39．13±7．54N，组间比较存在显著性差异（P〈0．05）。结论：记忆合金胸椎半侧骨骺加压矫形钉的最大拔出力与最大回复力成正相关，二者与两齿之间的原始齿间距离成反相关。

Objective： To design thoracic hemiepiphyseal compression staples that fit with the size of goat vertebra in China and evaluate the staples with mechanical test. Methods： According to the results of anatomic data of thoracic spine vertebra in 10 goats （ age 2-3 months）, three types of staples made of shape memory alloy were designed and divided into 3 groups ： group 1 （5mm）, group 11 （6.5mm）, groupm （8mm）. The experiment was designed to evaluate the maximum recovery stresses of staples with a spinal 3D test machine. Meanwhile, 4 specimens were used and each was cut into three functional spinal units （FSU） of T6-T7, TS-T9 and T10-T11. Then the staples were randomly implanted into both sides of each FSU. The peak force of pullout in each FSU was also measured. Results： The maximum recovery stresses and the peak force of pullout of the thoracic he- miepiphyseal compression staples in 3 groups were as follows： 5ram group： 138.73±12.05N, 74.18 ± 8.81N; 6.5mm group： 119.65±16.34N, 51.28 ± 5.44N ; 8mm group ： 96.95 ± 18.27N, 39.13 ± 7.54N. Significant statistical difference was found between all groups （P 〈 0.05 ）. Conclusion ： There was a positive correlation between the maximum recovery stresses and the peak force of pullout of thoracic hemiepiphyseal compression staples. Both the maximum recovery stresses and the peak force of pullout were negatively related to the original distance between two opened prone.