Zhang Rui, Ji Qiaoli, Luo Gang, Xue Shuliang, Ma Songsong, Li Jianqiao, Ren Lei
Key Laboratory of Bionic Engineering, Ministry of Education, Jilin University , Changchun , The People's Republic of China.
Key Laboratory of Bionic Engineering, Ministry of Education, Jilin University, Changchun, The People's Republic of China; School of Mechanical, Aerospace and Civil Engineering, University of Manchester, Manchester, United Kingdom.
PeerJ. 2017 Jan 12;5:e2857. doi: 10.7717/peerj.2857. eCollection 2017.
The ostrich is a highly cursorial bipedal land animal with a permanently elevated metatarsophalangeal joint supported by only two toes. Although locomotor kinematics in walking and running ostriches have been examined, these studies have been largely limited to above the metatarsophalangeal joint. In this study, kinematic data of all major toe joints were collected from gaits with double support (slow walking) to running during stance period in a semi-natural setup with two selected cooperative ostriches. Statistical analyses were conducted to investigate the effect of locomotor gait on toe joint kinematics. The MTP3 and MTP4 joints exhibit the largest range of motion whereas the first phalangeal joint of the 4th toe shows the largest motion variability. The interphalangeal joints of the 3rd and 4th toes present very similar motion patterns over stance phases of slow walking and running. However, the motion patterns of the MTP3 and MTP4 joints and the vertical displacement of the metatarsophalangeal joint are significantly different during running and slow walking. Because of the biomechanical requirements, osctriches are likely to select the inverted pendulum gait at low speeds and the bouncing gait at high speeds to improve movement performance and energy economy. Interestingly, the motions of the MTP3 and MTP4 joints are highly synchronized from slow to fast locomotion. This strongly suggests that the 3rd and 4th toes really work as an "integrated system" with the 3rd toe as the main load bearing element whilst the 4th toe as the complementary load sharing element with a primary role to ensure the lateral stability of the permanently elevated metatarsophalangeal joint.
鸵鸟是一种高度善于奔跑的双足陆地动物，其跖趾关节永久性抬高，仅由两个脚趾支撑。尽管已经对行走和奔跑的鸵鸟的运动学进行了研究，但这些研究大多局限于跖趾关节以上。在本研究中，在半自然环境中，从两只选定的合作鸵鸟在双支撑（慢走）到站立期奔跑的步态中收集了所有主要趾关节的运动学数据。进行统计分析以研究运动步态对趾关节运动学的影响。MTP3和MTP4关节的运动范围最大，而第4趾的第一趾关节的运动变异性最大。在慢走和奔跑的站立阶段，第3和第4趾的趾间关节呈现非常相似的运动模式。然而，在奔跑和慢走过程中，MTP3和MTP4关节的运动模式以及跖趾关节的垂直位移存在显著差异。由于生物力学要求，鸵鸟可能在低速时选择倒立摆步态，在高速时选择弹跳步态，以提高运动性能和能量经济性。有趣的是，从慢到快的运动过程中，MTP3和MTP4关节的运动高度同步。这强烈表明，第3和第4趾实际上作为一个“集成系统”工作，第3趾作为主要承重元件，而第4趾作为辅助负载分担元件，其主要作用是确保永久性抬高的跖趾关节的侧向稳定性。
