Phalangeal joints kinematics in ostrich (Struthio camelus) locomotion on sand

Abstract

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.

Metric variation in the postcranial skeleton of ostriches,Struthio(Aves: Palaeognathae), with new data on extinct subspecies

“…Pedal digit III supports the majority of the load (Schaller et al, 2011) and its (plantar) flexion provides the main propulsion force (Hutchinson, 2004;Smith et al, 2006). The metatarso-phalangeal III/1 joint acts as a shock absorber and elastic energy storage (Rubenson et al, 2011;Schaller et al, 2011) and its action differs between walking and running on a solid substrate (Zhang et al, 2017) but not on sand (Zhang et al, 2018), which supports our hypothesis that the unique foot proportions in S. spatzi evolved as an adaptation to the rugged landscapes of northwestern Africa.…”

Comparison between the kinematics for kangaroo rat hopping on a solid versus sand surface

“…In a study of zebra-tailed lizard running, stride length decreased by 15% on the granular versus solid substrate, and the limb posture shifted from a digitigrade to a plantigrade position on solid versus granular substrate, respectively [2,4]. In ostriches, the kinematics of the toe joints were different while running on sand versus solid substrates, with a greater range of motion on the sand surface [5]. In a study using a hopping robot [6], the optimal strategy to achieve the highest height in a landing-jumping task was found to include a time delay between landing and push-off to avoid the transients associated with the relaxation of the granular media into a compacted state.…”

Study on bio-inspired feet based on the cushioning and shock absorption characteristics of the ostrich foot

“…Histology and scanning electron microscopy showed the collagen fiber bundles in the proximal MTP were mainly wavy-type and likely involved in energy storage and shock absorption, those in the middle MTP were straight-type and mainly acted to change the force direction, but those in the distal MTP were not consistently arranged [ 30 ]. Significant differences in locomotion patterns were found between running and slow walking in the MTP joint of ostriches, but not in the interphalangeal joint of the 3rd or 4th toe [ 31 – 33 ]. Moreover, the 3rd toe as the main load-bearing element whilst the 4th toe as the complementary load-sharing element really worked as an “integrated system”, which primarily ensured the lateral stability of the permanently-elevated MTP joint [ 26 , 32 , 33 ].…”

“…Significant differences in locomotion patterns were found between running and slow walking in the MTP joint of ostriches, but not in the interphalangeal joint of the 3rd or 4th toe [ 31 – 33 ]. Moreover, the 3rd toe as the main load-bearing element whilst the 4th toe as the complementary load-sharing element really worked as an “integrated system”, which primarily ensured the lateral stability of the permanently-elevated MTP joint [ 26 , 32 , 33 ].…”