title: Phalangeal joints kinematics during ostrich (Struthio camelus) locomotion.
abstract: 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.
authors.affiliation: Key Laboratory of Bionic Engineering, Ministry of Education, Jilin University , Changchun , The People's Republic of China.
authors.forename: Rui
authors.initials: R
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Bionic Engineering, Ministry of Education, Jilin University , Changchun , The People's Republic of China.
authors.forename: Qiaoli
authors.initials: Q
authors.lastname: Ji
authors.affiliation: Key Laboratory of Bionic Engineering, Ministry of Education, Jilin University , Changchun , The People's Republic of China.
authors.forename: Gang
authors.initials: G
authors.lastname: Luo
authors.affiliation: Key Laboratory of Bionic Engineering, Ministry of Education, Jilin University , Changchun , The People's Republic of China.
authors.forename: Shuliang
authors.initials: S
authors.lastname: Xue
authors.affiliation: Key Laboratory of Bionic Engineering, Ministry of Education, Jilin University , Changchun , The People's Republic of China.
authors.forename: Songsong
authors.initials: S
authors.lastname: Ma
authors.affiliation: Key Laboratory of Bionic Engineering, Ministry of Education, Jilin University , Changchun , The People's Republic of China.
authors.forename: Jianqiao
authors.initials: J
authors.lastname: Li
authors.affiliation: 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.
authors.forename: Lei
authors.initials: L
authors.lastname: Ren
keywords: Locomotion; Metatarsophalangeal joint; Ostrich; Phalangeal joints; Toes