正常与脱位2种牵引状态下山羊颈椎蠕变模型的建立及比较

目的 建立正常和脱位2种牵引状态下山羊颈椎蠕变模型,并比较其蠕变差异.方法 16头健康山羊随机分为正常组(正常颈椎牵引)和脱位组(人为制作颈椎脱位状态下牵引),用特制的牵引装置固定山羊,在1 h内每隔30 s测量1次各组在5、10、15、20、25、30 kg重量牵引时的颈椎相对轴向位移,然后作牵引重量-时间-位移关系图,最后比较两组各个牵引重量下位移的组间差异.结果 在1 h内,随着牵引重量的增加和时间的推移,正常组和脱位组的快速弹性蠕变的时间范围分别为7～28 min和3～13 min,继之出现缓慢的蠕变,但脱位组蠕变持续时间长,最后进入稳态蠕变期.脱位组在各个牵引重量下相对轴向位移均大于正常组,差异有统计学意义(P＜0.05);除牵引重量15 kg外,其余牵引重量下两组相对应变振幅(减去增加牵引重量前的基数后)差异均有统计学意义(P＜0.05).不同重量持续牵引下,正常组的相对应变振幅依次递减,而脱位组先减少再增加然后再减少.结论 该牵引装置可获得有效可靠的山羊颈椎蠕变模型.与正常状态比较,山羊颈椎脱位状态蠕变量更大,但更容易过度牵引.

The biomechanical comparison of cervical traction for normal and dislocated cervical spine model in goats

Objective To investigate the creep property of cervical vertebrae in goats with normal or dislocated cervical spine in traction.Methods Sixteen health adult goats were randomly divided into the normal group and the dislocated group,and immobilized with a special traction device.The relative axial range of motion(ROM) was recorded per 30 s in either group with 5,10,15,20,25,30 kg traction weight for the construction of the relation curve of the weight-time-displacement.Results Within 1 hour,the time range of rapid elastic creep was 7~28 min and 3~13 min in normal group and dislocation group,respectively.A slow creep period was followed in both groups,which lasted longer in the dislocation group,and ended up into the elastic relaxation.The relative axial ROMs in dislocation group were significantly larger than those in normal group under sustained traction of different weights(P<0.05).There were significant differences in relative strain amplitude between the two groups under all traction weights except for 15 kg(P<0.05).Under sustained traction of different weights,the relative strain amplitude in normal group progressively decreased,while a temporary elevation was revealed in its reduction in the dislocation group.Conclusion An effective and reliable cervical spine creep model is constructed on goat.The high creep deformation of cervical spine in dislocation status suggesting a vulnerability of excessive traction.