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 laboratoryhabituated 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 lowerlimb 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.

Comparative intralimb coordination in avian bipedal locomotion

“…In all, the translational movements of the hindlimb are more restricted to fore-aft motion in grounddwellers. This is a principle already known for large terrestrial birds (Rubenson et al, 2007;Goetz et al, 2008) and cursorial mammals (Hildebrand, 1988), and it imparts longer relative stride lengths, as segment length can be translated more straightforward into stride length. In consequence of greater relative body width in jackdaws compared with ground-dwelling species (Gatesy, 1999a), the mean femoral abduction angle is greater in jackdaws.…”

“…This holds also true for other small and medium-sized birds (up to the size of a chicken) investigated so far (Cracraft, 1971;Dagg, 1977;Manion, 1984;Muir et al, 1996;Verstappen et al, 2000). However, within Aves, motion of the intertarsal joint is clearly size-dependent, with large ratites showing nearly no motion in the joint during stance (Rubenson et al, 2007;Goetz et al, 2008;Schaller et al, 2009).…”

“…So far, available data on large Struthioniformes (Abourachid and Renous, 2000;Rubenson et al, 2007;Goetz et al, 2008;Schaller et al, 2009;Smith et al, 2010) suggest that across the entire class Aves, it is mainly body size, leading to a differing degree of crouch and elongation of relative distal limb length, that constrains the kinematic pattern (Gatesy and Pollard, 2011) (A.S., B. M. Kilbourne and M.S.F., unpublished). Looking at small species exhibiting rather similar intralimb proportions, a consistent pattern of intralimb coordination can be observed, supporting the initial hypothesis.…”

Forelimb muscle activity during equine locomotion

“…Individual muscle forces also have been determined, albeit for a smaller selection of animals, using detailed muscle-actuated models of the limbs (e.g. Anderson and Pandy, 2001;Goetz et al, 2008;Harrison et al, 2010;van Antwerp et al, 2007). Some studies have also evaluated the contributions of individual muscles to the angular accelerations of the joints and the acceleration of the whole-body centre of mass, but to our knowledge these analyses have been performed only for locomotion in humans (Anderson and Pandy, 2003;Anderson et al, 2004;Liu et al, 2006;Pandy and Andriacchi, 2010) and cats (van Antwerp et al, 2007).…”

Guineafowl with a twist: asymmetric limb control in steady bipedal locomotion

“…Birds are predominantly studied moving forward over level ground at relatively constant speeds in both kinematic (Cracraft, 1971;Jacobson and Hollyday, 1982;Muir et al, 1996;Gatesy and Biewener, 1991;Gatesy, 1999a;Abourachid, 2000Abourachid, , 2001Reilly, 2000;Verstappen et al, 2000;Rubenson et al, 2007;Nyakatura et al, 2012;Provini et al, 2012;Stoessel and Fischer, 2012) and kinetic (Clark and Alexander, 1975;Alexander et al, 1979;Roberts et al, 1998;Hancock et al, 2007;Goetz et al, 2008;Nudds et al, 2010;Rubenson et al, 2011;Andrada et al, 2013Andrada et al, , 2014 analyses. Compared with the uniformity of locomotion on a treadmill or straight trackway, the inherent variability of unsteady behaviors is much more difficult to characterize.…”