Hipp J A, Edgerton B C, An K N, Hayes W C
Department of Orthopaedic Surgery, Charles A. Dana Research Institute, Beth Israel Hospital, Boston, MA 02215.
J Biomech. 1990;23(12):1261-8. doi: 10.1016/0021-9290(90)90383-e.
Finite element models were used to predict the structural consequences of transcortical holes through long bones loaded in torsion. Several parameters were investigated including hole size, anelastic behavior of the bone, cortical wall thickness, cortical wall symmetry, curvature along the bone's long axis and the axial length of the defect. Finite element model predictions of percent intact bone strength were compared to experimental data for sheep femora with transcortical drill holes loaded to failure in torsion. Hole size was expressed as hole diameter divided by the outer bone diameter. Linear finite element model predictions were in conservative agreement with the experimental data for large hole sizes. A transcortical hole with a diameter 50% of the outer bone diameter reduced the torsional strength by 60%. However, the linear models predict a 40% drop in strength for small holes whereas in vitro data suggest that small holes have no significant effect on strength. Models which represent non-linear anelastic behavior in bone overpredicted torsional strengths. Asymmetric cortical wall thickness and long bone bowing have minor effects, while the length of an elongated defect strongly influences the torsional strength. Strength reductions are greatest for bones with thin cortical walls.
有限元模型被用于预测在承受扭转载荷的长骨上经皮质钻孔后的结构后果。研究了几个参数，包括孔径、骨的滞弹性行为、皮质骨壁厚、皮质骨壁对称性、沿骨长轴的曲率以及缺损的轴向长度。将有限元模型预测的完整骨强度百分比与在扭转载荷下直至破坏的带有经皮质钻孔的绵羊股骨的实验数据进行比较。孔径表示为孔径除以骨外径。对于大孔径，线性有限元模型预测结果与实验数据保守一致。直径为骨外径50%的经皮质钻孔会使抗扭强度降低60%。然而，线性模型预测小孔径时强度会下降40%，而体外数据表明小孔径对强度无显著影响。表示骨非线性滞弹性行为的模型高估了抗扭强度。皮质骨壁厚不对称和长骨弯曲的影响较小，而细长缺损的长度对抗扭强度有强烈影响。皮质骨壁薄的骨强度降低最为显著。
