Hip bone trabecular architecture shows uniquely distinctive locomotor behaviour in South African australopithecines
University of the Witwatersrand, Johannesburg, Gauteng, South Africa Journal of Human Evolution
(Impact Factor: 3.73).
03/1999; 36(2):211-32. DOI: 10.1006/jhev.1998.0267
Cancellous bone retains structural and behavioural properties which are time and strain-rate dependent. As the orientation of the trabeculae (trajectories) follows the direction of the principal strains imposed by daily loadings, habitual postural and locomotor behaviours are responsible for a variety of trabecular architectures and site-specific textural arrangements of the pelvic cancellous network. With respect to the great ape condition, the human trabecular pattern is characterized by a distinctive ilioischial bundle, an undivided sacropubic bundle, and a full diagonal crossing (approximately 100 degrees) over the acetabulum between the ilioischial and the sacropubic bundles. Advanced digital image processing (DIP) of hip bone radiographs has revealed that adolescent and adult South African australopithecines retained an incompletely developed human-like trabecular pattern associated with gait-related features that are unique among the extant primates.
Available from: Kristi Lewton
- "The pelvis is a critical link in the hindlimb locomotor system, as the muscles of propulsion attach to it and forces from the limb are transmitted through it to the trunk. In biological anthropology, the pelvis has been at the center of a critical debate regarding the evolution of bipedal behaviors in fossil hominins and how the pelvis adapted to this novel form of primate locomotion (Reynolds, 1931; Dart, 1949; Le Gros Clark, 1955; Day, 1973; Lovejoy et al. 1973, 2009; Brain et al. 1974; McHenry, 1975; Ashton et al. 1981; Berge, 1984; Rak & Arensburg, 1987; Rak, 1991; Fleagle & Anapol, 1992; Rosenberg, 1992; Ruff, 1995, 2010; Macchiarelli et al. 1999; Marchal, 2000; Haeusler, 2002; Lovejoy, 2005; Weaver & Hublin, 2009; Kibii et al. 2011). While many studies have correlated pelvic anatomy with locomotor behavior (Ashton et al. 1981; Berge, 1984; Ward, 1991; Fleagle & Anapol, 1992; Anemone, 1993; MacLatchy & Bossert, 1996; MacLatchy , 1998), a lack of understanding of pelvic biomechanics (i.e. "
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ABSTRACT: The pelvis is a critical link in the hindlimb locomotor system and has a central role in resisting loads associated with locomotion, but our understanding of its structural biomechanics is quite limited. Empirical data on how the pelvis responds to the loads it encounters are important for understanding pelvic adaptation to locomotion, and for testing hypotheses regarding how the pelvis is adapted to its mechanical demands. This paper presents in vitro strain gauge data on a sample of monkey and ape cadaveric specimens (Macaca, Papio, Ateles, Hylobates), and assesses strain magnitudes and distributions through the bones of the pelvis: the ilium, ischium and pubis. Pelves were individually mounted in a materials testing system, loads were applied across three hindlimb angular positions, and strains were recorded from 18 locations on the pelvic girdle. Peak principal strains range from 2000 to 3000 με, similar to peak strains recorded from other mammals in vivo. Although previous work has suggested that the bones of the pelvis may act as bent beams, this study suggests that there are likely additional loading regimes superimposed on bending. Specifically, these data suggest that the ilium is loaded in axial compression and torsion, the ischium in torsion, the pubic rami in mediolateral bending, and the pubic symphysis is loaded in a combination of compression and torsion. Compressive strains dominate the pelves of all species representatives. Shear strains change with limb position; hip flexion at 45 ° induces smaller shear strains than mid-stance (90 °) or hip extension (105 °). The pelvic girdle is a complex structure that does not lend itself easily to modeling, but finite element analyses may prove useful to generate and refine hypotheses of pelvic biomechanics.
© 2015 Anatomical Society.
Available from: Sue M Black
- "The pelvic girdle represents a key junctional complex for the transfer of weight from the head, trunk and upper extremities to the lower limb (Cunningham and Black, 2009a; Tardieu et al., 2013), therefore it should be an important focus for biomechanical and osteological research. However, the extant literature which describes pelvic bone structure is primarily restricted to phylogenetic studies concentrating on the differences between Homo sapiens and other primate species (Macchiarelli et al., 1999; Martin on-Torres, 2003; Volpato et al., 2008), with emphasis typically placed on iliac shape and structure. These studies focus almost exclusively on the trabecular patterns of the adult ilium and typically neglect to consider juvenile bone development. "
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ABSTRACT: Despite the importance of the human pelvis as a weight-bearing structure, there is a paucity of literature that discusses the development of the juvenile innominate from a biomechanical perspective. This study aims to add to the limited body of literature pertaining to this topic through the qualitative analysis of the gross architecture of the human ischium during the juvenile period. Macro-radiographs of 55 human ischia ranging from 28 intra-uterine weeks to 14 years of age were examined using intensity-gradient color mapping to highlight changes in gross structural morphology with increasing age. A clear pattern of maturation was observed in the juvenile ischium with increasing age. The acetabular component and ramus of the ischium consistently displayed low bone intensity in the postnatal skeletal material. Conversely the posterior body of the ischium, and in particular the ischial spine and lesser sciatic notch, exhibited increasing bone intensity which first arose at 1–2 years of age and became more expansive in older cohorts. The intensity patterns observed within the developing juvenile ischium are indicative of the potential factors influencing the maturation of this skeletal element. While the low intensity acetabular fossa indicates a lack of significant biomechanical interactions, the posterior increase in bone intensity may be related to the load-bearing nature of the posterior ischium. Clin. Anat., 2014. © 2014 Wiley Periodicals, Inc.
Available from: Meir M Barak
- "trabecular bone structures preserved in fossils. Several studies used vertebrae , pelvic bones  , the femoral head  and metacarpal bones  of extinct hominins   , primates  and horses  to infer locomotor behaviors. The inferences made by these studies, which relied on the assumption that primary trabecular orientation correlates to the direction of joint loading, are therefore supported by the dynamic response of trabecular bone shown here. "
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ABSTRACT: This study tests Wolff's law of trabecular bone adaptation by examining if induced changes in joint loading orientation cause corresponding adjustments in trabecular orientation. Two groups of sheep were exercised at a trot, 15 min/day for 34 days on an inclined (7°) or level (0°) treadmills. Incline trotting caused the sheep to extend their tarsal joints by 3-4.5° during peak loading (P<0.01) but has no effect on carpal joint angle (P=0.984). Additionally, tarsal joint angle in the incline group sheep were maintained more extended throughout the day using elevated platform shoes on their forelimbs. A third "sedentary group" group did not run but wore platform shoes throughout the day. As predicted by Wolff's law, trabecular orientation in the distal tibia (tarsal joint) were more obtuse by 2.7 to 4.3° in the incline group compared to the level group; trabecular orientation was not significantly different in the sedentary and level groups. In addition, trabecular orientations in the distal radius (carpal joint) of the sedentary, level and incline groups did not differ between groups, and were aligned almost parallel to the radius long axis, corresponding to the almost straight carpal joint angle at peak loading. Measurements of other trabecular bone parameters revealed additional responses to loading, including significantly higher bone volume fraction (BV/TV), Trabecular number (Tb.N) and trabecular thickness (Tb.Th), lower trabecular spacing (Tb.Sp), and less rod-shaped trabeculae (higher structure model index, SMI) in the exercised than sedentary sheep. Overall, these results demonstrate that trabecular bone dynamically adjusts and realigns itself in very precise relation to changes in peak loading direction, indicating that Wolff's law is not only accurate but also highly sensitive.
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