长骨纵向缺损对其扭转刚度和应力分布影响

Effect of a longitudinal defect in a long bone on its torsional stiffness and stress distribution

为研究临床上开窗对长骨力学性质的影响,建立了一个股骨中段的外侧皮质带有矩形缺损的力学模型;采用有限元方法,计算了骨缺损的宽度为股骨外径(D)0.1～0.3倍、长度为股骨外径1～5倍时,股骨的扭转刚度和应力分布.计算结果表明:骨缺损长度为D时,对股骨扭转刚度和剪应力分布的影响较小;骨缺损长度从2D增至4D时扭转刚度急剧减小,而且剪应力的最大值位于骨缺损中心.研究认为临床骨科手术中长骨开窗的尺寸应控制在小于3D～4D,且术后应避免长骨承受扭转力的作用.

In order to make clear how the longitudinal defects affect a long bone, a mechanical model of a femur mid-diaphysis with a rectangular defect in the exterior cortex is developed. The influences of the defect on the torsional stiffness and the stress distribution are calculated and analyzed by finite element method. The defect widths range from one-tenth of the femur outer diameter (0.1D) to 0.3D, and defect lengths range from 1D to 5D. It is shown that the defects with a length of 1D have little influence on the femur torsional stiffness or stress distribution. The torsional stiffness decreases most dramatically as the defect length increases from 2D to 4D. Shear flow reversal peaks at the center of the defect for defects longer than ID. The results show that the defect size should be limited and the patient should avert tortional load after operation.