Contact stress distributions on the femoral head of the emu (Dromaius novaehollandiae)

Troy, Karen L.; Brown, Thomas; Conzemius, Michael G.

doi:10.1016/j.jbiomech.2009.07.017

Cited by 15 publications

(14 citation statements)

References 15 publications

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“…joint. ABAD excursions during maneuvers were extremely small (less than 8 deg across all six trials shown), as expected given interaction between the proximal femur and the pelvic antitrochanter (Hutchinson and Gatesy, 2000;Hertel and Campbell, 2007;Troy et al, 2009). However, contrary to the assertion that the antitrochanter prevents femoral long-axis mobility by acting as a lock (Hertel and Campbell, 2007), we document significant hip LAR in maneuvering guineafowl.…”

Section: A Predominant Role For Larsupporting

confidence: 71%

“…Likewise, analyses of joint rotation are usually restricted to flexion/extension (FE) angles (Sigmund, 1959;Cracraft, 1971;Rylander and Bolen, 1974;Jacobson and Hollyday, 1982;Manion, 1984;Gatesy, 1990;Gatesy, 1999;Johnston and Bekoff, 1992;Abourachid and Renous, 2000;Reilly, 2000;Verstappen et al, 2000;Ellerby and Marsh, 2010;Smith et al, 2010;Nyakatura et al, 2012). Given the relatively small transverse component of the ground reaction force during forward locomotion (Clark and Alexander, 1975;Main and Biewener, 2007;Troy et al, 2009), inverse dynamic studies normally emphasize net FE joint moments as well (Roberts, 2001;Roberts and Scales, 2004;Daley et al, 2007;Rubenson and Marsh, 2009;Andrada et al, 2013b). Our current perception of bird hind limbs thus remains deeply rooted in the erect paradigm.…”

Section: Introductionmentioning

confidence: 99%

“…Given avian joint geometry, ABAD may be a less likely candidate than LAR. At the hip, the projecting pelvic antitrochanter likely limits femoral abduction (Hutchinson and Gatesy, 2000;Hertel and Campbell, 2007;Troy et al, 2009), whereas the body constrains femoral adduction. ABAD at the bicondylar knee and intertarsal (ankle) joints would tend to disarticulate one condyle and cause instability.…”

Section: Introductionmentioning

confidence: 99%

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Long-axis rotation: a missing degree of freedom in avian bipedal locomotion

Kambic

Roberts

Gatesy

2014

Journal of Experimental Biology

106

191

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Ground-dwelling birds are typically characterized as erect bipeds having hind limbs that operate parasagittally. Consequently, most previous research has emphasized flexion/extension angles and moments as calculated from a lateral perspective. Three-dimensional (3D) motion analyses have documented non-planar limb movements, but the skeletal kinematics underlying changes in foot orientation and transverse position remain unclear. In particular, long-axis rotation of the proximal limb segments is extremely difficult to measure with topical markers. Here, we present six degree of freedom skeletal kinematic data from maneuvering guineafowl acquired by markerbased XROMM (X-ray Reconstruction of Moving Morphology). Translations and rotations of the hips, knees, ankles and pelvis were derived from animated bone models using explicit joint coordinate systems. We distinguished sidesteps, sidestep yaws, crossover yaws, sidestep turns and crossover turns, but birds often performed a sequence of blended partial maneuvers. Long-axis rotation of the femur (up to 38 deg) modulated the foot's transverse position. Longaxis rotation of the tibiotarsus (up to 65 deg) also affected mediolateral positioning, but primarily served to either re-orient a swing phase foot or yaw the body about a stance phase foot. Tarsometatarsal long-axis rotation was minimal, as was hip, knee and ankle abduction/adduction. Despite having superficially hinge-like joints, birds coordinate substantial long-axis rotations of the hips and knees to execute complex 3D maneuvers while striking a diversity of non-planar poses.

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Section: A Predominant Role For Larsupporting

confidence: 71%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Long-axis rotation: a missing degree of freedom in avian bipedal locomotion

Kambic

Roberts

Gatesy

2014

Journal of Experimental Biology

106

191

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“…Troy, Brown & Conzemius (2009) assumed that only the IFE, ITM, ITCR and PIFML muscles (homologous to ours) would resist hip adduction in their simplified emu model, but our analysis reveals that several more hip abductors exist, namely the IL, ILFB, FCM/L and CFP muscle groups (Table 4; Figs. 14 and 15).…”

Section: Discussionmentioning

confidence: 86%

Musculoskeletal modelling of an ostrich (Struthio camelus) pelvic limb: influence of limb orientation on muscular capacity during locomotion

Hutchinson

Rankin

Rubenson

et al. 2015

PeerJ

193

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We developed a three-dimensional, biomechanical computer model of the 36 major pelvic limb muscle groups in an ostrich (Struthio camelus) to investigate muscle function in this, the largest of extant birds and model organism for many studies of locomotor mechanics, body size, anatomy and evolution. Combined with experimental data, we use this model to test two main hypotheses. We first query whether ostriches use limb orientations (joint angles) that optimize the moment-generating capacities of their muscles during walking or running. Next, we test whether ostriches use limb orientations at mid-stance that keep their extensor muscles near maximal, and flexor muscles near minimal, moment arms. Our two hypotheses relate to the control priorities that a large bipedal animal might evolve under biomechanical constraints to achieve more effective static weight support. We find that ostriches do not use limb orientations to optimize the moment-generating capacities or moment arms of their muscles. We infer that dynamic properties of muscles or tendons might be better candidates for locomotor optimization. Regardless, general principles explaining why species choose particular joint orientations during locomotion are lacking, raising the question of whether such general principles exist or if clades evolve different patterns (e.g., weighting of muscle force–length or force–velocity properties in selecting postures). This leaves theoretical studies of muscle moment arms estimated for extinct animals at an impasse until studies of extant taxa answer these questions. Finally, we compare our model’s results against those of two prior studies of ostrich limb muscle moment arms, finding general agreement for many muscles. Some flexor and extensor muscles exhibit self-stabilization patterns (posture-dependent switches between flexor/extensor action) that ostriches may use to coordinate their locomotion. However, some conspicuous areas of disagreement in our results illustrate some cautionary principles. Importantly, tendon-travel empirical measurements of muscle moment arms must be carefully designed to preserve 3D muscle geometry lest their accuracy suffer relative to that of anatomically realistic models. The dearth of accurate experimental measurements of 3D moment arms of muscles in birds leaves uncertainty regarding the relative accuracy of different modelling or experimental datasets such as in ostriches. Our model, however, provides a comprehensive set of 3D estimates of muscle actions in ostriches for the first time, emphasizing that avian limb mechanics are highly three-dimensional and complex, and how no muscles act purely in the sagittal plane. A comparative synthesis of experiments and models such as ours could provide powerful synthesis into how anatomy, mechanics and control interact during locomotion and how these interactions evolve. Such a framework could remove obstacles impeding the analysis of muscle function in extinct taxa.

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“…Hutchinson and Gatesy () noted the antitrochanter's function as a physical limit to femoral abduction during stance and locomotion and is thus likely loaded in both compression and shear. In contrast, Hertel et al () and Troy et al () suggested the antitrochanter functions as a sliding surface against the femoral neck, and experiences little compression during stance and locomotion. Prior to skeletal maturity, the avian antitrochanter attaches to the laterally oriented growth plate surfaces on the ilial‐ischial junction, and is comprised of a hyaline cartilage core and a fibrocartilaginous articular surface.…”

Section: Discussionmentioning

confidence: 99%

Articular soft tissue anatomy of the archosaur hip joint: Structural homology and functional implications

Tsai

Holliday

2014

Journal of Morphology

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Archosaurs evolved a wide diversity of locomotor postures, body sizes, and hip joint morphologies. The two extant archosaurs clades (birds and crocodylians) possess highly divergent hip joint morphologies, and the homologies and functions of their articular soft tissues, such as ligaments, cartilage, and tendons, are poorly understood. Reconstructing joint anatomy and function of extinct vertebrates is critical to understanding their posture, locomotor behavior, ecology, and evolution. However, the lack of soft tissues in fossil taxa makes accurate inferences of joint function difficult. Here, we describe the soft tissue anatomies and their osteological correlates in the hip joint of archosaurs and their sauropsid outgroups, and infer structural homology across the extant taxa. A comparative sample of 35 species of birds, crocodylians, lepidosaurs, and turtles ranging from hatchling to skeletally mature adult were studied using dissection, imaging, and histology. Birds and crocodylians possess topologically and histologically consistent articular soft tissues in their hip joints. Epiphyseal cartilages, fibrocartilages, and ligaments leave consistent osteological correlates. The archosaur acetabulum possesses distinct labrum and antitrochanter structures on the supraacetabulum. The ligamentum capitis femoris consists of distinct pubic- and ischial attachments, and is homologous with the ventral capsular ligament of lepidosaurs. The proximal femur has a hyaline cartilage core attached to the metaphysis via a fibrocartilaginous sleeve. This study provides new insight into soft tissue structures and their osteological correlates (e.g., the antitrochanter, the fovea capitis, and the metaphyseal collar) in the archosaur hip joint. The topological arrangement of fibro- and hyaline cartilage may provide mechanical support for the chondroepiphysis. The osteological correlates identified here will inform systematic and functional analyses of archosaur hindlimb evolution and provide the anatomical foundation for biomechanical investigations of joint tissues.

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Contact stress distributions on the femoral head of the emu (Dromaius novaehollandiae)

Cited by 15 publications

References 15 publications

Long-axis rotation: a missing degree of freedom in avian bipedal locomotion

Long-axis rotation: a missing degree of freedom in avian bipedal locomotion

Musculoskeletal modelling of an ostrich (Struthio camelus) pelvic limb: influence of limb orientation on muscular capacity during locomotion

Articular soft tissue anatomy of the archosaur hip joint: Structural homology and functional implications

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