Delp S L, Maloney W
Department of Biomedical Engineering, Northwestern University, Chicago, IL.
J Biomech. 1993 Apr-May;26(4-5):485-99. doi: 10.1016/0021-9290(93)90011-3.
We have developed a three-dimensional biomechanical model of the human lower extremity to study how the location of the hip center affects the moment-generating capacity of four muscle groups: the hip abductors, adductors, flexors, and extensors. The model computes the maximum isometric force and the resulting joint moments that each of 25 muscle-tendon complexes develops at any body position. Abduction, adduction, flexion, and extension moments calculated with the model correspond closely with isometric joint moments measured during maximum voluntary contractions. We used the model to determine (1) the hip center locations that maximize and minimize the moment-generating capacity of each muscle group and (2) the effects of superior-inferior, anterior-posterior, and medial-lateral displacement of the hip center on the moment arms, maximum isometric muscle forces, and maximum isometric moments generated by each muscle group. We found that superior-inferior displacement of the hip center has the greatest effect on the force- and moment-generating capacity of the muscles. A 2 cm superior displacement decreases abduction force (44%), moment arm (12%), and moment (49%), while a 2 cm inferior displacement increases abduction force (20%), moment arm (7%) and moment (26%). Similarly, a 2 cm superior displacement decreases flexion force (27%), moment arm (6%), and moment (22%), while inferior displacement increases all three variables. Anterior-posterior displacement alters the moment-generating capacity of the flexors and extensors considerably, primarily due to moment arm changes. Medial-lateral displacement has a large effect on the moment-generating capacity of the adductors only. A 2 cm medial displacement decreases adduction moment arm (20%), force (26%) and moment (40%). These results demonstrate that the force- and moment-generating capacities of the muscles are sensitive to the location of the hip center.
我们开发了一个人体下肢的三维生物力学模型，以研究髋关节中心的位置如何影响四个肌肉群（髋外展肌、内收肌、屈肌和伸肌）产生力矩的能力。该模型计算了25个肌肉-肌腱复合体在任何身体位置产生的最大等长力和由此产生的关节力矩。用该模型计算的外展、内收、屈曲和伸展力矩与最大自主收缩时测量的等长关节力矩密切相关。我们使用该模型来确定：（1）使每个肌肉群产生力矩的能力最大化和最小化的髋关节中心位置；（2）髋关节中心的上下、前后和内外位移对每个肌肉群的力臂、最大等长肌力和最大等长力矩的影响。我们发现，髋关节中心的上下位移对肌肉产生力和力矩的能力影响最大。向上位移2厘米会使外展力降低44%、力臂降低12%、力矩降低49%，而向下位移2厘米会使外展力增加20%、力臂增加7%、力矩增加26%。同样，向上位移2厘米会使屈曲力降低27%、力臂降低6%、力矩降低22%，而向下位移会使所有这三个变量增加。前后位移会显著改变屈肌和伸肌产生力矩的能力，主要是由于力臂的变化。内外位移仅对内收肌产生力矩的能力有很大影响。向内位移2厘米会使内收力臂降低20%、力降低26%、力矩降低40%。这些结果表明，肌肉产生力和力矩的能力对髋关节中心的位置很敏感。
