D'Lima D D, Chen P C, Kessler O, Hoenecke H R, Colwell C W
Scripps, La Jolla, CA, USA.
Mol Cell Biomech. 2011 Jun;8(2):123-34.
The menisci are important biomechanical components of the knee. We developed and validated a finite element model of meniscal replacement to assess the effect of surgical fixation technique on contact behavior and knee stability. The geometry of femoral and tibial articular cartilage and menisci was segmented from magnetic resonance images of a normal cadaver knee using MIMICS (Materialise, Leuven, Belgium). A finite element mesh was generated using HyperWorks (Altair Inc, Santa Ana, CA). A finite element solver (Abaqus v6.9, Simulia, Providence, RI) was used to compute contact area and stresses under axial loading and to assess stability (reaction force generated during anteroposterior translation of the femur). The natural and surgical attachments of the meniscal horns and peripheral rim were simulated using springs. After total meniscectomy, femoral contact area decreased by 26% with a concomitant increase in average contact stresses (36%) and peak contact stresses (33%). Replacing the meniscus without suturing the horns did little to restore femoral contact area. Suturing the horns increased contact area and reduced peak contact stresses. Increasing suture stiffness correlated with increased meniscal contact stresses as a greater proportion of tibiofemoral load was transferred to the meniscus. A small incremental benefit was seen of simulated bone plug fixation over the suture construct with the highest stiffness (50 N/mm). Suturing the rim did little to change contact conditions. The nominal anteroposterior stiffness reduced by 3.1 N/mm after meniscectomy. In contrast to contact area and stress, stiffness of the horn fixation sutures had a smaller effect on anteroposterior stability. On the other hand suturing the rim of the meniscus affected anteroposterior stability to a much larger degree. This model emphasizes the importance of the meniscus in knee biomechanics. Appropriate meniscal replacement fixation techniques are likely to be critical to the clinical success of meniscal replacement. While contact conditions are mainly sensitive to meniscus horn fixation, the stability of the knee under anteroposterior shear loads appeared to be more sensitive to meniscal rim fixation. This model may also be useful in predicting the effect of biomaterial mechanical properties and meniscal replacement shape on knee contact conditions.
半月板是膝关节重要的生物力学组成部分。我们开发并验证了一个半月板置换的有限元模型，以评估手术固定技术对接触行为和膝关节稳定性的影响。股骨和胫骨关节软骨以及半月板的几何形状是使用MIMICS（Materialise公司，比利时鲁汶）从一具正常尸体膝关节的磁共振图像中分割出来的。使用HyperWorks（Altair公司，加利福尼亚州圣安娜）生成有限元网格。使用有限元求解器（Abaqus v6.9，Simulia公司，罗德岛州普罗维登斯）计算轴向加载下的接触面积和应力，并评估稳定性（股骨前后平移过程中产生的反作用力）。半月板角和周边边缘的自然和手术附着情况使用弹簧进行模拟。全半月板切除术后，股骨接触面积减少了26%，同时平均接触应力（36%）和峰值接触应力（33%）相应增加。不缝合半月板角进行半月板置换对恢复股骨接触面积作用不大。缝合半月板角可增加接触面积并降低峰值接触应力。随着缝合刚度的增加，半月板接触应力也增加，因为更大比例的胫股负荷转移到了半月板上。与最高刚度（50 N/mm）的缝合结构相比，模拟骨栓固定有微小的增量益处。缝合半月板边缘对接触情况改变不大。半月板切除术后，名义前后刚度降低了3.1 N/mm。与接触面积和应力不同，半月板角固定缝线的刚度对前后稳定性的影响较小。另一方面，缝合半月板边缘对前后稳定性的影响程度要大得多。该模型强调了半月板在膝关节生物力学中的重要性。合适的半月板置换固定技术可能对半月板置换的临床成功至关重要。虽然接触情况主要对半月板角固定敏感，但膝关节在前后剪切载荷下的稳定性似乎对半月板边缘固定更为敏感。该模型也可能有助于预测生物材料力学性能和半月板置换形状对膝关节接触情况的影响。
