title: Hip joint contact force in the emu (Dromaius novaehollandiae) during normal level walking.
abstract: The emu is a large, (bipedal) flightless bird that potentially can be used to study various orthopaedic disorders in which load protection of the experimental limb is a limitation of quadrupedal models. An anatomy-based analysis of normal emu walking gait was undertaken to determine hip contact forces for comparison with human data. Kinematic and kinetic data captured for two laboratory-habituated emus were used to drive the model. Muscle attachment data were obtained by dissection, and bony geometries were obtained by CT scan. Inverse dynamics calculations at all major lower-limb joints were used in conjunction with optimization of muscle forces to determine hip contact forces. Like human walking gait, emu ground reaction forces showed a bimodal distribution over the course of the stance phase. Two-bird averaged maximum hip contact force was approximately 5.5 times body weight, directed nominally axially along the femur. This value is only modestly larger than optimization-based hip contact forces reported in literature for humans. The interspecies similarity in hip contact forces makes the emu a biomechanically attractive animal in which to model loading-dependent human orthopaedic hip disorders.
authors.affiliation: Department of Orthopaedics and Rehabilitation, University of Iowa, Iowa City, IA, USA.
authors.forename: Jessica E
authors.initials: JE
authors.lastname: Goetz
authors.forename: Timothy R
authors.initials: TR
authors.lastname: Derrick
authors.forename: Douglas R
authors.initials: DR
authors.lastname: Pedersen
authors.forename: Duane A
authors.initials: DA
authors.lastname: Robinson
authors.forename: Michael G
authors.initials: MG
authors.lastname: Conzemius
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Baer
authors.forename: Thomas D
authors.initials: TD
authors.lastname: Brown
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D001835:Body Weight / Q000502:physiology; D020312:Dromaiidae / Q000033:anatomy & histology / Q000502:physiology*; D005684:Gait / Q000502:physiology; D006621:Hip Joint / Q000033:anatomy & histology / Q000502:physiology*; D006801:Humans; D008297:Male; D023421:Models, Animal; D053580:Muscle Strength / Q000502:physiology*; D016138:Walking / Q000502:physiology*