不同程度耻骨联合分离对骨盆后环应力分布影响的生物力学研究

目的 评价不同程度耻骨联合分离对骨盆后环应力分布的影响.方法 8具完整骨盆及近侧1/3股骨标本,用夹具将其固定于双足站立骨盆中立位,在CSS-44020生物力学试验机上加载至600 N.将应变片粘贴于骶髂关节两侧、骶骨前方和髂骨后侧选定的38个位点,应用WS3811型数字式应变仪依次测量完整骨盆、耻骨联合分离1 cm、2 cm和2.5 cm时选定位置的应变值.结果 骨盆皮质骨在600 N范围内呈弹性变形,在耻骨联合完整以及不同程度分离时,两侧对应位点应变值无明显差异(P＞0.05).在耻骨联合完整时,骨盆弹性形变较大的位点分布在髂股弓走形上,耻骨联合分离后髂股弓后外侧位点应变值增加较大;骶股弓轴线位点应变值逐渐减小.结论 完整骨盆环垂直负荷的传导途径与骶股弓走形近似,在耻骨联合分离时,骨盆后环传导的垂直负荷向后外侧再分布.

Biomechanical study of the influence of different degrees of pubic symphysis diastasis on stress distribution of the posterior pelvic ring

Objective To evaluate the effect of different degrees of pubic symphysis diastasis on the stress distribution of posterior pelvic ring. Methods Eight embalmed pelvis and articulated proximal 1/3 of the femurs were harvested for this study. The samples were positioned as both legs standing straight and loaded to 600 N on the on the CSS-44020 biomechanical machine. The strain gages were adhered to 38 sites distributed symmetrically on the two sides of sacroiliac joint, anterior sacrum and posterior ilium. The strain gages were connected to WS3811 digital strainometer to record strain changes of the intact pelvic ring and at 1,2, 2.5 cm of pubic symphysis diastasis. Results Elastic changes occurred in the cortical bone of the pelvis under 600 N load. The symmetrical sites had similar strain changes without significant difference in the intact pelvic ring and at 1,2, 2.5 cm of pubic symphysis diastasis ( P ＞0.05 ). The sites with more strain changes were distributed on the iliofemoral arch in the intact pelvis.The strain changes were increased significantly frona the posterolateral sites to the iliofemoral arch. But the strain changes on the iliofemoral arch were decreased significantly during pubic symphysis diastasis.Conclusion The conduction of vertical load runs along the sacrofemoral arch in the intact pelvic ring and redistributes posterolaterally during pubic symphysis diastasis.