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.
"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. "
"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. "
"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. "
[Show abstract][Hide abstract] 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.
Bone 08/2011; 49(6):1141-51. DOI:10.1016/j.bone.2011.08.020 · 3.97 Impact Factor
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