How is sagittal balance acquired during bipedal gait acquisition? Comparison of neonatal and adult pelves in three dimensions. Evolutionary implications

摘要: Abstract We compare adult and intact neonatal pelves, using a pelvic sagittal variable, the angle of sacral incidence, which presents significant correlations with vertebral curvature in adults plays an important role balance trunk on lower limbs. Since lumbar develops children association gait acquisition, we expect change this during growth, could contribute to acquisition balance. To understand mechanisms underlying evolution human bipedalism, also measure incidence hominid fossils. Forty-seven landmarks were digitized 50 19 pelves. used three-dimensional model pelvis (DE-VISU program), calculates related functional variables. Cross-sectional data from newborns show that increases becomes negatively correlated sacro-acetabular distance. During ontogeny, sacrum curved, tends sink down between iliac blades as wedge moves backward plane relative acetabula, thus contributing backwards displacement center gravity trunk. A chain links degree slope is tightly linked lordosis. describe showing coordinated changes occurring column bipedalism infancy. In australopithecine Sts 14 AL 288-1, Homo erectus Gona pelvis, reaches mean values humans. Discussing incomplete pelves Ardipithecus ramidus, Australopithecus sediba Nariokotome boy, suggest how linkage spine observed humans have emerged evolution.