Study of the three-dimensional orientation of the labrum: its relations with the osseous acetabular rim

Abstract Understanding the three-dimensional orientation of the coxo-femoral joint remains a challenge as an accurate three-dimensional orientation ensure an efficient bipedal gait and posture. The quantification of the orientation of the acetabulum can be performed using the three-dimensional axis perpendicular to the plane that passes along the edge of the acetabular rim. However, the acetabular rim is not regular as an important indentation in the anterior rim was observed. An innovative cadaver study of the labrum was developed to shed light on the proper quantification of the three-dimensional orientation of the acetabulum. Dissections on 17 nonembalmed corpses were performed. Our results suggest that the acetabular rim is better represented by an anterior plane and a posterior plane rather than a single plane along the entire rim as it is currently assumed. The development of the socket from the Y-shaped cartilage was suggested to explain the different orientations in these anterior and posterior planes. The labrum forms a plane that takes an orientation in between the anterior and posterior parts of the acetabular rim, filling up inequalities of the bony rim. The vectors V L , V A2 and V P , representing the three-dimensional orientation of the labrum, the anterior rim and the posterior rim, are situated in a unique plane that appears biomechanically dependent. The three-dimensional orientation of the acetabulum is a fundamental parameter to understand the hip joint mechanism. Important applications for hip surgery and rehabilitation, as well as for physical anthropology, were discussed

Evolution de la fonction obstétricale chez les hominoïdes (analyse morphométrique tridimensionnelle de la cavité pelvienne chez les espèces actuelles et fossiles)

La cavité pelvienne est le lieu de passage du fœtus lors de l accouchement. Cette fonction naturelle est considérée comme un processus dangereux suite à la réorganisation du pelvis au cours de l évolution. Nous avons donc étudié la cavité pelvienne par l analyse procustéenne, une méthode de morphométrie géométrique. Notre but est de décrire les trois détroits obstétricaux des premiers représentants hominidés dont la cavité pelvienne a pu être reconstituée : les Australopithèques (AL288-1 et Sts 14). Les analyses d un Homo erectus (KNM-WT 15000), d un Homo neanderthalensis (Kébara 2) et d un Homo sapiens (Cro magnon) nous éclairent quant à l évolution de la mécanique obstétricale. Notre étude révèle que les primates non humains subissent leurs propres contraintes obstétricales, qui ne seraient donc pas une spécificité humaine. La variabilité pelvienne humaine est importante et les modèles pelviens, partagés par toutes les populations. Ces mêmes modèles se retrouvent aussi bien chez les hommes que chez les femmes. L étude d une population de femmes pathologiques mortes en couches démontre que d autres facteurs que les parois osseuses sont plus déterminants quant à l issue de l accouchement. Les cavités pelviennes fossiles intègrent la variabilité humaine et s en distinguent par un aplatissement postérieur caractéristique. Les résultats obtenus nous amènent à remettre en cause le dilemme obstétrical et à suggérer une adaptation réussie de la cavité pelvienne à la bipédie et à l encéphalisation grâce à plusieurs mécaniques obstétricales sur lesquelles la posture maternelle peut influerThe pelvic cavity is the passage of the foetus during the childbirth. This natural function is considered a dangerous process following the modification of the pelvis during the evolution. We studied the pelvic cavity by the procrustes analysis, a method of geometrical morphometrics. The aim of this study is to describe the inlets of the first Hominids, Australopithecus (AL288-1 and Sts 14). The analyses of Homo erectus (KNM-WT 15000), Homo neanderthalensis (Kébara 2) and of Homo sapiens (Cro Magnon) enlighten us about the evolution of obstetrical mechanics. Our results reveal that the nonhuman primates undergo their own obstetrical constraints, which could not be a human specificity. The variability of the human pelvis is important and the different pelvic patterns are shared by all populations. The same patterns are found among men as well as women. The study of pathological women dead in bed shows that other factors influence more the process of childbirth than the pelvic bones. The fossil pelvic cavities are distributed among modern human variability and are characterized by a posterior flatness. Our research compromises the issue of the obstetrical dilemma and suggests that the pelvic cavity had a successful adaptation to bipedy and encephalisation thanks to several obstetrical mechanics which might be influenced by the maternal posturePARIS-Museum Hist.Naturelle (751052304) / SudocSudocFranceF

Jean-Louis Heim (1937-2018)

Grimaud D., Boë Louis-Jean, Dunand Françoise, Gonthier Erik, Bouhallier July. Jean-Louis Heim (1937-2018). In: Bulletin de la Société préhistorique française, tome 115, n°3, 2018. pp. 618-619