[Morphogenesis of the femoral diaphysis in humans: significance of function and evolution].
The obliquity of the femoral diaphysis, measured by the bicondylar angle, permits the adducted position of the knee in humans. The presence of a high femoral bicondylar angle has been a hallmark of hominid bipedality, but its pattern of development has not been documented. We have observed radiographic and skeletal data on the development of this angle. The two samples exhibit a pattern of a bicondylar angle of 0 degrees at birth and then a steady average increase in the angle through infancy and into the juvenile years. These data establish a high degree of potential for plasticity in the development of this angle and the direct association of a bipedal locomotion with the developmental emergence of a human femoral bicondylar angle. We show that the obliquity angle, which occasionally appears in some non-human primates, is not homologous to the human condition. As this angle is an epigenetic functional feature in modern humans, we suggest that it developed following a change in infantile locomotor behaviour of the early australopithecines and was not the result of a genomic change.
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URA 1137 CNRS, Laboratoire d'Anatomie Comparée, Muséum National d'Histoire Naturelle, Paris, France.
D000293:Adolescent; D002648:Child; D018483:Diaphyses / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000254:growth & development*; D005269:Femur / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000254:growth & development*; D006801:Humans; D007231:Infant, Newborn; D008124:Locomotion / Q000502:physiology; D009024:Morphogenesis; D011859:Radiography
Morphogénèse de la diaphyse fémorale chez l'homme: signification fonctionnelle et évolutive.