探讨股骨中下段骨折后内/外翻畸形愈合对膝关节应力分布与接触面积影响的生物力学研究。

选取正常成年男性志愿者，进行下肢CT薄层扫描和膝关节MRI成像，利用Mimics软件将CT和MRI图像配准后进行三维重建，建立一个正常下肢模型。在正常模型的基础上对骨和软组织进行位置调整，分别建立股骨中下段骨折残留3°、5°、10°内/外翻畸形愈合模型。然后在有限元分析软件Abaqus中计算畸形愈合对膝关节内外侧间室von Mises应力与接触面积。

成功建立了正常人下肢及膝关节模型，其形态结构基于下肢CT和MRI重建，与真实膝关节高度相似，并在其基础上建立了股骨远端1/3内/外翻畸形愈合模型。正常中立位内侧胫骨软骨的接触面积与最大应力是244.36 mm²，0.64 mpa，外侧则是196.25 mm²，0.76 mpa。与正常中立位相比，随着正常中立位至股骨内翻角度10°，内侧胫骨软骨接触面积与最大应力增大至264.61 mm²，1.16 mpa，相应的胫骨平台外侧逐渐减小至31.32 mm²，0.35 mpa。而随着正常中立位至股骨外翻10°，内侧平台软骨接触面积与最大应力逐渐减小至24.58 mm²，0.27 mpa，外侧胫骨软骨则逐渐增大至215.46 mm²，2.08 mpa。与正常中立位模型对比时，内侧软骨下骨应力，半月板应力大小与分布范围随着内翻程度增大逐渐增大，随着外翻程度增大逐渐减小。外侧软骨下骨与半月板变化趋势则与之相反。

股骨内外翻畸形对膝关节间室接触面积和应力分布有明显影响。股骨手术应尽力避免残留内外翻畸形，应早期治疗避免膝关节周围结构损伤，进而延缓膝关节炎的进展。

To investigate the biomechanical effects of varus/valgus deformities after middle and lower femoral fracture on the stress distribution and contact area of knee joint.

A normal adult male volunteer was selected to undergo thin-slice CT scanning of lower extremities and MRI imaging of knee joints. After registration of CT and MRI images by Mimics software, a normal lower limb model was established. On the basis of the normal model, the position of bone and soft tissue was adjusted, and the models of 3, 5 and 10 degree of varus/valgus deformities of middle and lower femur fracture were established respectively.

The models of normal lower extremities was successfully established. Their morphological structure was highly similar to those of the real knee joints. On the basis of them, the models of varus/valgus deformities of distal femur were established.The contact area and maximum stress of medial tibial cartilage in normal neutral position was 244.36 mm² and 0.64 mpa, while that of lateral was 196.25 mm² and 0.76 mpa. Compared with the normal neutral position, with the angle from normal neutral position to 10° of varus, the contact area and maximum stress of medial tibial cartilage increased to 264.61 mm² and 1.16 mpa, and the lateral tibial plateau gradually decreased to 31.32 mm² and 0.35 mpa. With the normal neutral position to 10° of valgus, the contact area and maximum stress of medial plateau cartilage gradually decreased to 24.58 mm² and 0.27 mpa, while that of lateral plateau cartilage increased to 215.46 mm² and 2.08 mpa.Compared with the normal neutral model, the maximum stress of medial subchondral bone, the maximum stress and distribution of meniscus increased with the increase of varus degree, and decreased with the increase of valgus degree. The variation trend of the lateral subchondral bone and meniscus was opposite.

The varus/valgus deformity of femur has a significant effect on the contact area and stress distribution of knee joint compartment. In the operation of femur, we should try our best to avoid residual varus/valgus deformity, and early treatment should be carried out to avoid the injury of the structure around the knee joint, so as to delay the progress of knee arthritis.