Zhang Rui, Ji Qiaoli, Han Dianlei, Wan Haijin, Li Xiujuan, Luo Gang, Xue Shuliang, Ma Songsong, Yang Mingming, Li Jianqiao
Key Laboratory of Bionic Engineering, Ministry of Education, Jilin University, Changchun, P.R. China.
PLoS One. 2018 Feb 28;13(2):e0191986. doi: 10.1371/journal.pone.0191986. eCollection 2018.
In ostriches, the toes are the only body parts that contact loose sand surfaces. Thus, toe interphalangeal joint motions may play vital biomechanical roles. However, there is little research on ostrich phalangeal joint movements while walking or running on sand. The results from the three-dimensional motion track analysis system Simi Motion show that gait pattern has no significant effect on the key indicators (angles at touch-down, mid-stance, lift-off and range of motion) of the toe joint angles. The motion of the toe phalanges when walking and running on sand is basically the same. The ground medium is the key factor that changes the toe postures adopted by ostriches during the stance phase in slow to fast locomotion. The 3rd toe and the 4th toe are connected by the interphalangeal ligament, and the motions of the MTP3 and MTP4 joints are highly synchronized on a loose sand substrate. The 3rd toe and 4th toe are coupled to maintain static balance in slow locomotion and dynamic balance in fast locomotion. In addition, the gait pattern has a marked effect on the range of forward displacement of the toenail (YTN). The ostrich toenail plays an important role in preventing slip and provides traction at push-off in a sandy environment. The metatarsophalangeal joint plays an important role in energy saving during fast locomotion on loose sand substrates. Simulation reveals that the particle velocity field, particle force field and sand particle disturbance in the running gait are denser than those in the walking gait.
在鸵鸟中，脚趾是唯一接触松散沙地表面的身体部位。因此，趾间关节的运动可能起着至关重要的生物力学作用。然而，关于鸵鸟在沙地行走或奔跑时趾关节运动的研究很少。三维运动轨迹分析系统Simi Motion的结果表明，步态模式对趾关节角度的关键指标（着地、支撑中期、离地时的角度以及运动范围）没有显著影响。鸵鸟在沙地行走和奔跑时趾骨的运动基本相同。地面介质是在慢速到快速运动的站立阶段改变鸵鸟所采用趾部姿势的关键因素。第三趾和第四趾通过趾间韧带相连，在松散沙地表面，第三跖趾关节（MTP3）和第四跖趾关节（MTP4）的运动高度同步。第三趾和第四趾相互配合，以在慢速运动中保持静态平衡，在快速运动中保持动态平衡。此外，步态模式对趾甲向前位移的范围（YTN）有显著影响。鸵鸟的趾甲在防止滑倒方面起着重要作用，并在沙地环境中蹬地时提供牵引力。跖趾关节在松散沙地表面快速运动时的节能方面起着重要作用。模拟显示，奔跑步态中的颗粒速度场、颗粒力场和沙粒扰动比行走步态中的更密集。
