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The acquisition of habitual bipedal locomotion, which resulted in numerous modifications of the skeleton was a crucial step in hominid evolution. However, our understanding of the inherited skeletal modifications versus those acquired while learning to walk remains limited. We here present data derived from X-rays and CT scans of quadrupedal adult humans and compare the morphology of the vertebral column, pelvis and femur to that of a bipedal brother. We show how a skeleton forged by natural selection for bipedal locomotion is modified when used to walk quadrupedally. The quadrupedal brother is characterised by the absence of femoral obliquity, a very high anteversion angle of the femoral neck, a very high collo-diaphyseal angle and a very reduced lordosis. The differences in the pelvis are more subtle and complex, yet of functional importance. The modification of the ischial spines to an ischial ridge and the perfectly rounded shape of the sacral curvature are two unique features that can be directly attributed to a quadrupedal posture and locomotion. We propose a functional interpretation of these two exceptional modifications. Unexpectedly, the quadrupedal brother and sister show a greater angle of pelvic incidence compared to their bipedal brother, a trait previously shown to increase with learning to walk in bipedal subjects. Moreover, the evolution from an occasional towards a permanent bipedality has given rise to a functional association between the angle of pelvic incidence and the lumbar curvature, with high angles of incidence and greater lumbar curvature promoting stability during bipedal locomotion. The quadrupedal brother and sister with a high angle of incidence and a very reduced lordosis thus show a complete decoupling of this complex functional integration.

The discovery of the nearly complete Plio-Pleistocene skeleton StW 573 Australopithecus prometheus from Sterkfontein Member 2, South Africa, has intensified debates as to whether Sterkfontein Member 4 contains a hominin species other than Australopithecus africanus. For example, it has recently been suggested that the partial skeleton StW 431 should be removed from the A. africanus hypodigm and be placed into A. prometheus. Here we re-evaluate this latter proposition, using published information and new comparative data. Although both StW 573 and StW 431 are apparently comparable in their arboreal (i.e., climbing) and bipedal adaptations, they also show significant morphological differences. Surprisingly, StW 431 cannot be unequivocally aligned with either StW 573 or other hominins from Sterkfontein commonly attributed to A. africanus (nor with Paranthropus robustus and Australopithecus sediba). This finding, together with considerations about the recent dating of Plio-Pleistocene hominin-bearing sites in South Africa and palaeoecological/palaeoclimatic conditions, raises questions whether it is justified to subsume hominins from Taung, Makapansgat and Sterkfontein (and Gladysvale) within a single taxon. Given the wealth of fossil material and analytical techniques now available, we call for a re-evaluation of the taxonomy of South African Plio-Pleistocene hominins. Such an endeavour should however go beyond the current (narrow) focus on establishing an A. africanus-A. prometheus dichotomy.

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The functional linkage between pelvis and spine remained long hidden to science. Here, we recount the history of research that led in 1992 to the discovery of the "angle of sacral incidence" by the team of G. Duval-Beaupere. This angle, formed between a ray from the hip joint center to the superior sacral surface and the perpendicular to the sacral surface, was later called pelvic incidence. Specific to each individual, pelvic incidence is tightly correlated with the degree of lumbar lordosis. It is each individual's "signature" for an efficient sagittal balance since it represents the sum of two positional parameters, sacral slope and pelvic tilt. The simultaneous experimental determination of the trunk line of gravity permitted Duval-Beaupere's team to elucidate the conditions of an efficient sagittal balance of the trunk on the lower limbs. We present an in vivo EOS study of eight spino-pelvic parameters describing the sagittal balance in 131 adults. We observe a chain of correlations between the six angular parameters and discuss the functional significance of these results. We show that pelvic incidence increases and lumbar lordosis develops when the infant learns to walk, leading to a correlation between these parameters. This process of association between pelvis and spine might have acquired a solid genetic basis during hominid evolution by natural selection acting on both pelvis and spine. We suggest that this process of functional integration was only possible in the context of bipedal locomotion becoming permanent and stereotyped, expressed by a relatively invariant, periodic walking cycle. Anat Rec, 300:912-931, 2017. © 2017 Wiley Periodicals, Inc.

A comparative study of the hip joint in hominids has important implications for physical anthropology, as new insights could provide additional information for documenting changes associated with the acquisition of habitual bipedalism in the human lineage. In the literature, changes in the shape of both the proximal femur and the acetabular region in hominids have been investigated; however, few analyses have studied joint congruence and even fewer have attempted to quantify the degree of correspondence between the three-dimensional orientations of the two joint components. In humans, the hip joint has a lower degree of correspondence in a bipedal posture than would be expected for such a key joint. Because natural selection is dependent on inherited structure and trade-offs between several functions, it has been suggested in a previous study that the lower degree of correspondence might be partly due to the phylogenetic history of our species. In order to test this hypothesis, an extend sample of hominids was analysed. Our results show that joint architecture changes substantially according to the locomotor behaviour of the taxon considered. In orangutans, the considerable mobility of the lower limbs is ensured in part by a shallow acetabulum and a wide femoral neck-shaft angle. In contrast, the hip joint of gorillas has to support heavy loads and thus needs stability: a deep acetabulum and a narrow femoral neck-shaft angle were observed. Finally, our results provided evidence that the highest congruence between the three-dimensional orientations of the two joint components in all the studied genera, i.e. Homo, Pan, Gorilla and Pongo, was obtained in a quadrupedal posture, further suggesting that the shape of the human hip joint is constrained by its quadrupedal ancestry.

Acetabular cup orientation (inclination and anteversion) is a fundamental topic in orthopaedics and depends on pelvis tilt (positional parameter) emphasising the notion of a safe range of pelvis tilt. The hypothesis was that pelvic incidence (morphologic parameter) could yield a more accurate and reliable assessment than pelvis tilt. The aim was to find out a predictive equation of acetabular 3D orientation parameters which were determined by pelvic incidence to include in the model. The second aim was to consider the asymmetry between the right and left acetabulae. Twelve pelvic anatomic specimens were measured with an electromagnetic Fastrak system (Polhemus Society) providing 3D position of anatomical landmarks to allow measurement of acetabular and pelvic parameters. Acetabulum and pelvis data were correlated by a Spearman matrix. A robust linear regression analysis provided prediction of acetabulum axes. The orientation of each acetabulum could be predicted by the incidence. The incidence is correlated with the morphology of acetabula. The asymmetry of the acetabular roof was correlated with pelvic incidence. This study allowed analysis of relationships of acetabular orientation and pelvic incidence. Pelvic incidence (morphologic parameter) could determine the safe range of pelvis tilt (positional parameter) for an individual and not a group.

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

The functional linkage between pelvis and spine remained long hidden to science. Here, we recount the history of research that led in 1992 to the discovery of the "angle of sacral incidence" by the team of G. Duval-Beaupère. This angle, formed between a ray from the hip joint center to the superior sacral surface and the perpendicular to the sacral surface, was later called pelvic incidence. Specific to each individual, pelvic incidence is tightly correlated with the degree of lumbar lordosis. It is each individual's "signature" for an efficient sagittal balance since it represents the sum of two positional parameters, sacral slope and pelvic tilt. The simultaneous experimental determination of the trunk line of gravity permitted Duval-Beaupère's team to elucidate the conditions of an efficient sagittal balance of the trunk on the lower limbs. We present an in vivo EOS study of eight spino-pelvic parameters describing the sagittal balance in 131 adults. We observe a chain of correlations between the six angular parameters and discuss the functional significance of these results. We show that pelvic incidence increases and lumbar lordosis develops when the infant learns to walk, leading to a correlation between these parameters. This process of association between pelvis and spine might have acquired a solid genetic basis during hominid evolution by natural selection acting on both pelvis and spine. We suggest that this process of functional integration was only possible in the context of bipedal locomotion becoming permanent and stereotyped, expressed by a relatively invariant, periodic walking cycle. Anat Rec, 300:912-931, 2017. © 2017 Wiley Periodicals, Inc.

From an evolutionary perspective, the functional morphologic characteristics of the knee joint are of ancient origin. Human knee kinematics is complex, with an asymmetry of femoral rollback on the tibia between the medial and lateral compartments. Hominids share a common evolutionary history with all living tetrapods relative to the development of these knee morphologic asymmetries. During mammal evolution, the lateral compartment of the knee presented a greater polymorphism than the medial one. Also some important bony changes occurred in the knee joint. The double insertion of the human lateral meniscus is unique among all living mammals, corresponding to a restriction of the rotation movements of the knee and thus of meniscal mobility (our ability to fully extend the knee during gait). During human knee ontogeny, by eight weeks, which marks the end of the embryonic period, the meniscus is clearly defined. At this time, the lateral meniscus already has a double insertion on the tibial plateau. Then, no major shape modification is observed during prenatal and postnatal development. At no time does the lateral meniscus appear to have a discoid shape. All these elements support the thesis that discoid meniscus can be considered as a character reversion, an atavism.

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 non-embalmed 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 VL, VA2 and VP, 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.

Taxinomie, taxionomie, ou taxonomie ? Nous exposons ici l’etymologie de ce mot, qui lui donne son sens et impose l’orthographe « taxinomie » et nous racontons son histoire tres erratique. Des le depart le botaniste Candolle, l’inventeur de ce mot, en proposa une orthographe erronee « taxonomie ». Redressee par les dictionnaires clairvoyants, elle fut de nouveau malmenee par un usage sauvage et ne cessera de l’etre par la suite. Francais de culture greco-latine, nous nous devons de connaitre la veritable origine de ce mot et donc sa bonne orthographe. Les anglophones quant a eux ignorent le plus souvent cette culture, ce qui ne les empeche pas d’imposer leur orthographe erronee de cet important concept. Le mot taxonomie existe bien en francais mais, conformement a son etymologie, signifie tout autre chose : le traitements des ifs. Si l’Academie a tres rapidement corrige l’orthographe erronee du mot taxologie, en imposant taxilogie avec force raison, pourquoi une pareille inertie de la part de la communaute scientifique concernee pour son mot frere taxinomie ?

The importance of the sacral pelvic incidence (SPI) in relation to individual variations of sagittal spinal curvature has become well-recognised. We attempted to determine the relationship between SPI and acetabular orientation. The three-dimensional coordinates of 47 homologous points were observed on 51 adult anatomical pelvises (26 female and 25 male). The reference vertical plane was Lewinnek's anterior pelvic plane. 10 angular parameters and 11 linear parameters were defined and calculated. These were expressed both in absolute value (in millimetres) and in “acetabular unit” (relative to the mean value of the right and left acetabular rays). Mean values of the parameters were calculated for all pelvises and according to gender. There were two dominant parameters: the “sacral slope” and the “V pubic angle”. “Acetabular tilting” was primarily dependant on the “sacral slope” and its intermediary on the “SPI”, while “acetabular anteversion” dependent on the “V pubic angle” via the “angle of prow”. It is recommended that positioning of the acetabular cup in total hip arthroplasty relates to anatomical parameters, and to the global sagittal balance of the pelvi-spinal unit.

In fossil hominins we must reconstruct behavior, including locomotion, largely from preserved skeletal features. The interpretation of such features has been controversial in some cases because we do not understand their true functional significance. One way to explore this issue is to examine both normal and abnormal modern human growth in clinical cases to see what affects the locomotor skeleton and what appears to be of genetic and epigenetic origin. These results can then be used to interpret fossils.

Purpose of the study. - Implantation of total hip arthroplasties raises several important questions concerning the relationship between the orientation of the lumbosacral joint and the acetabular-femoral joint; in other words, between the position of the patients trunk and the orientation of the acetabula. To elucidate better these complex relationships, we conducted a morphometry study on a sample of 51 dry pelves: pelv 26 female and 25 mate specimens. Material et methods. - Three-dimensional coordinates of 47 homologous points were recorded for each pelvis. Data were then processed with De-Visu, a graphic visualization software. Seven parameters were compared: sacral slope, sacral incidence, and five parameters quantifying the three-dimensional orientation of the acetabula. Results. - The graphic modelization enabled an integral 3-D visualization of each pelvis. The sagittal view enabled simultaneous visualization of the sacrum, the sacroiliac joints, the acetabula, and their alignments, as well as the variability of their spatial relation. The position reference chosen to simulate the upright position aligned the anterior iliac spines and the superior pubic point. This position was found pertinent because the mean value of the sacral slope (41.8 degrees) and the sacral incidence (54 degrees) were not different from published series. The sacral slope was the most strongly correlated with the acetabular parameters. It exhibited a positive correlation with sagittal acetabular slope (r = 0.59) and acetabular inclination (r = 0.59). It exhibited a negative correlation with acetabular anteversion (R = 0.45). The correlation with the sagittal acetabular slope was very strong for anteversion (r = 0.92), and rose with acetabular inclination (r = -0.66). The angle formed by the two acetabular axes was highly variable (37 degrees). The correlation between this angle and inclination was very high in mates (r = -0.88) and non-significant in females. There was however a very strong correlation with anteversion in females (r = -0.74) which was non-significant in mates. This contrasting finding was related to the wide spread of the inclination values in mates and anteversion values in females. Discussion. - We demonstrated a new sagittal parameter: the acetabular incidence. The summit of this angle is the center of the acetabulum. The sides are the pelvic thickness and the acetabular axes. This parameter was negatively correlated with the sacral incidence. It account simultaneously for the sagittal position of the sacrum in relation to the acetabula and for the degree of acetabular anteversion and inclination. We have demonstrated that the geometric sum of these two angles, sacral incidence and acetabular incidence, is equivalent to the sacro-acetabular angle demonstrated by Lazennec and Saillant. These authors showed that the sacro-acetabular angle is the sum of two positional parameters, the sacral. slope and the sagittal acetabular tilt (or slope). The three angles - sacral incidence, acetabutar incidence, sacro-acetabular angle - are anatomic angles which do not vary with the pelvic position. (C) 2008 Elsevier Masson SAS. Tous droit reserves.

Reliability and reproducibility of two radiological pelvic parameters are tested: thickness (length of the segment defined by the middle of the upper endplate of the sacrum to the middle of the bi-coxo-femoral axis) and pelvic incidence (angle defined by the perpendicular line to the centre of the upper endplate of the sacrum and the thickness line). These two parameters provide a pelvis description and assess the relation between pelvis and spinal curves. The anatomical reliability of these radiological parameters was not achieved. The values of these two parameters from X-ray versus direct measurement on 12 anatomical specimens are compared. The direct measurement was performed by means of an electromagnetic Fastrak system (Polhemus society) providing 3D position of anatomical landmarks and allowing to measure the incidence and the thickness. These parameters were also measured from sagittal X-ray. Their values were compared. Incidence: the paired t-test and the variance ratio test were not statistically significant and a highly significant positive correlation existed between anatomical and radiological values (r=0.98; P

The hip joint is a very stable diarthrosis that connects the acetabular region to the proximal femur. This joint occupies a central place in the human locomotor system as it plays an important role...

Three different human femoro-tibial characters are selected as functionally relevant and derived hominid characters: femoral bicondylar angle, shape of the femoral distal epiphysis, and the tibial insertion of the lateral meniscus. The timing and mode of formation of these characters are investigated during human ontogeny and are shown to differ considerably. The available hominid fossils (Australopithecus afarensis and early Homo) are interpreted in the light of this ontogenetic analysis with the conclusion that, during hominid evolution, different modes of selection of these features must have occurred. In modern humans, the femoral bicondylar angle proves to be an epigenetic functional feature, which develops during early childhood growth. It is present in all australopithecines and we suggest that it developed following a change in their locomotor behavior and not upon a genomic change: the early practice of bipedal walking, with adducted knee joints, in the locomotor repertoire of infant australopithecines, was sufficient to promote this angle. Later in hominid evolution, the knee joint evolved from having a single insertion of the lateral meniscus on the tibia to a double one. While Australopithecus afarensis exhibits a single insertion, early Homo clearly exhibits a double insertion of the lateral meniscus on the tibia. The double insertion restricts the mobility of the meniscus on the tibial plateau, indicating a habitual practice of full extension movements of the knee joint. Among modern humans, the posterior insertion of the lateral meniscus appears early in fetal life. Consequently in early Homo, this new selected feature developed directly as a result of a genomic change. The derived shape of human distal femoral epiphysis includes a prominence of the lateral lip of the femoral trochlea, an elliptical profile of the lateral condyle, and an anteroposterior lengthening of the epiphysis. Analysis of human fetal and neonatal distal epiphyses shows that the prominence of the lateral lip of the trochlea arises before any use, and thus appears to be genetically determined. However, the postnatal development of this joint shows that this feature is also modified epigenetically by use. It is argued that the hominid femoro-patellar joint would have been reshaped following the process of genetic assimilation (Waddington [1942] Nature 3811:563-565). The prominence of the lateral lip of the femoral trochlea was probably selected following a two-staged process-first epigenetic, then genetic. Far from being a Lamarckian explanation, this concept applies precisely to adaptive characters that are induced by an external stimulus during a single lifetime and are replaced through natural selection by genetically based equivalent characters. The nature of the structures involved in the studied features is shown to be an important parameter determining their mode of development and selection.

Did the first hominids have a short developmental period similar to that of the great apes or a longer period closer to that of modern humans? Evidence from studies on dental and facial growth favors the first point of view. Additional evidence presented in this report is provided by a morphogenetic analysis of the lower limb. Some morphological modifications undergone by the human femur during infantile and adolescent growth are shown to be excellent markers of different developmental stages. The angular remodelling of the femoral diaphysis, which results in femoral bicondylar angle, is a marker of infancy, while the reshaping of the distal femoral epiphysis is a marker of adolescence. This reshaping of the bony epiphysis consists of the strong projection of the external lip of the femoral trochlea, the increase of the radius of curvature of the external condyle, and the anteroposterior lengthening of the whole epiphysis. The growth spurt in linear dimensions of the femur, characteristic of human adolescence, is shown to be associated with qualitative changes of the distal femoral epiphysis engendered by the late closure of the distal epiphysis. The femur of the first hominids (Australopithecus afarensis) shows only features of infantile growth, whereas characters of both precocious and later growth are typical of later hominids (Homo). The absence of the derived epiphyseal features in Australopithecus would be linked to their early epiphyseal closure and short adolescent growth period; their presence in Homo would have been promoted by their delayed epiphyseal closure and prolonged adolescent growth period. The transition from Australopithecus to Homo appears to have involved a heterochronic process of time hypermorphosis (Gould, [1977], Ontogeny and Phylogeny [Cambridge: Harvard University Press]) in which the size of the femur increases, the epiphysis is modified, and the period of peripubertal growth is prolonged. The shape of the distal epiphyses of KNM-WT 15000, an immature Homo erectus (Brown et al. [1985] Nature 316:788–792), lies clearly within the range of modern human adolescents. In contradiction to Smith's ([1993] in A. Walker and R. Leakey [eds.]: The Nariokotome Homo erectus Skeleton [Cambridge: Harvard University Press], pp. 195–220) hypothetical reconstruction of life span of Homo erectus, we infer that a growth spurt had begun with Homo erectus but was probably less pronounced and of shorter duration than in modern humans. Our findings on the femur are consistent with studies of the growth on the hominid pelvis (Berge [1996] in LF Marcus, M Corti, A Loy, G Naylor, and DE Slice [eds.]: Advances in Morphometrics [Chicago: Plenum Publishing Corp.], pp. 441–448). It is suggested that the lengthening of the adolescent growth period, from Australopithecus to Homo, would have been also associated with the shape changes of the pelvis and with the lengthening of the lower limbs. Am J Phys Anthropol 107:163–178, 1998. © 1998 Wiley-Liss, Inc.

Did the first hominids have a short developmental period similar to that of the great apes, or a longer period closer to that of modern humans? Some morphological modifications undergone by the human femur during growth are shown to be excellent markers of different developmental stages. The femur of the first hominids (Australopithecus afarensis) shows only features of infantile growth, whereas characters of both infantile and adolescent growth are typical of later hominids (Homo). In the first australopithecines the period of peripubertal growth would have still been short. The prolongation of the adolescent period appears to be a characteristic of Homo.

The obliquity of the femoral diaphysis accounts for the valgus position of the human knee joint and reduces bending moments in the frontal plane. A high angle of obliquity is considered a hallmark of hominid bipedality, but its functional importance has rarely been identified correctly. A biostatic investigation of the knee joint in various realistic positions unveils resultant joint forces which do not deviate greatly from the long axis of the femoral shaft. This is due to the length of the femur and to the shortness of the human foot. The flat epiphyseal suture is more or less perpendicular to these joint forces, and the equal size of the femoral condyles reflects the even distribution of forces between them. In great apes the resultant forces acting in the knee joint vary considerably in dependence on the degree of flexion and rotation of the knee joint. The resultant joint force may be in line with the femur shaft or diverge. The epiphyseal surfaces offer facets to all joint forces found in the course of the study. Due to the pronounced varus position of the knee joint, the joint itself and the adjacent part of the femur are under medially concave bending moments, which lead to higher compressive forces at the medial than at the lateral condyle. The enlarged medial condyle allows the distribution of medially displaced joint forces over a relatively large area, and the elliptic cross-section yields high bending resistance in the frontal plane. A human-like angle of obliquity is present in the early australopithecines, the values being mostly within the range of variation of children. The valgus position of the australopithecine knee joint is considered to be a functional, and epigenetic consequence of habitual bipedality. It is particularly pronounced because of the short length of the femur and the great bitrochanteric width.

A common problem in the quantification of the orientation of the femoral neck is the difficulty to determine its true axis; however, this axis is typically estimated visually only. Moreover, the orientation of the femoral neck is commonly analysed using angles that are dependent on anatomical planes of reference and only quantify the orientation in two dimensions. The purpose of this study is to establish a method to determine the three-dimensional orientation of the femoral neck using a three-dimensional model. An accurate determination of the femoral neck axis requires a reconsideration of the complex architecture of the proximal femur. The morphology of the femoral neck results from both the medial and arcuate trabecular systems, and the asymmetry of the cortical bone. Given these considerations, two alternative models, in addition to the cylindrical one frequently assumed, were tested. The surface geometry of the femoral neck was subsequently used to fit one cylinder, two cylinders and successive cross-sectional ellipses. The model based on successive ellipses provided a significantly smaller average deviation than the two other models (P < 0.001) and reduced the observer-induced measurement error. Comparisons with traditional measurements and analyses on a sample of 91 femora were also performed to assess the validity of the model based on successive ellipses. This study provides a semi-automatic and accurate method for the determination of the functional three-dimensional femoral neck orientation avoiding the use of a reference plane. This innovative method has important implications for future studies that aim to document and understand the change in the orientation of the femoral neck associated with the acquisition of a bipedal gait in humans. Moreover, the precise determination of the three-dimensional orientation has implications in current research involved in developing clinical applications in diagnosis, hip surgery and rehabilitation.

In humans, the hip joint occupies a central place in the locomotor system, as it plays an important role in body support and the transmission of the forces between the trunk and lower limbs. The study of the three-dimensional biomechanics of this joint has important implications for documenting the morphological changes associated with the acquisition of a habitual bipedal gait in humans. Functional integration at any joint has important implications in joint stability and performance. The aim of the study was to evaluate the functional integration at the human hip joint. Both the level of concordance between the three-dimensional axes of the acetabulum and the femoral neck in a bipedal posture, and patterns of covariation between these two axes were analysed. First, inter-individual variations were quantified and significant differences in the three-dimensional orientations of both the acetabulum and the femoral neck were detected. On a sample of 57 individuals, significant patterns of covariation were identified, however, the level of concordance between the axes of both the acetabulum and the femoral neck in a bipedal posture was lower than could be expected for a key joint such as the hip. Patterns of covariation were explored regarding the complex three-dimensional biomechanics of the full pelvic-femoral complex. Finally, we suggest that the lower degree of concordance observed at the human hip joint in a bipedal posture might be partly due to the phylogenetic history of the human species.

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 non-embalmed 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.

The presence of a femoral bicondylar angle consistently and significantly greater than 0" has been a hallmark of hominid bipedality, but its pattern of development has not been documented. We have therefore compiled cross-sectional data on the development of the articular bicondylar angle for a clinical sample of modern humans and of the metaphyseal bicondy- lar angle for two Recent human skeletal samples, one predominantly Euro- pean in origin and the other Amerindian. All three samples exhibit a pattern of a bicondylar angle of 0" at birth and then a steady average increase in the angle from late in the first year postnatal, through infancy, and into the juvenile years. The two skeletal samples reach low adult values by approxi- mately 4 years postnatal, whereas the clinical sample with a lowered activity level appears to attain consistent adult values slightly later (approximately 6 years postnatal). In addition, two modern human individuals, one nonambu- latory and the other minimally ambulatory, show no and little development, respectively, of a bicondylar angle. These data, in conjunction with clinical and experimental observations on the potential and form of angular changes during epiphyseal growth, establish a high degree of potential for plasticity in the development of the human bicondylar angle and the direct association of a bipedal locomotion and (especially) posture with the developmental emer- gence of a human femoral bicondylar angle. o 1994 Wiley-Liss, Inc.

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.

In traditional as well as in geometric morphometric studies, the shape of the pelvis is often quantified after the reassembly of the two hip bones and the sacrum. However, on dry bones, the morphology of the cartilaginous tissues that form the two sacroiliac joints and the pubic symphysis before death remains unknown, leading to potential inaccuracies and errors during the reassembly process. A protocol was established to investigate the effects of reassembly on the quantification of pelvis shape. The shape of fresh pelves obtained after dissection, in which the three bones are in an anatomically relevant position, was compared with the shape of different reassemblies based on the individual dry bones of the same individuals. Our results demonstrated a significant effect of the reassembly. Variation in the reassembly process is likely related, first, to the complete absence of cartilaginous tissues on dry bones and, second, to the morphology of the sacroiliac joint which, in vivo, allows physiological movements, resulting in different potential positions of the two sacroiliac surfaces relative to one another. However, the artificial variation introduced by the reassembly process appears small compared with the biological variation between the different individuals.

Summary. — So as to analyse the ontogeny of the bicondylar angle of the human femur, associated with the adduction of the knees in humans, we studied twenty-five X-rays of the femurs of children, ranging from 0 to 13 years. The sample exhibits a pattern of no bicondylar angle at birth and then a steady increase in the angle through infancy in direct association with the acquisition of walking. The angle development corresponds to a morphogenetic process which exclusively affects the diaphysis and is independent of the growth of the distal epiphysis. We show that the obliquity angle of the femur, which occasionally appears in some non human primates, is not homologous of the human one., Résumé. — Afin d'analyser l'ontogenèse de l'angle bicondylaire du fémur humain, qui permet la position adductée des genoux chez l'homme, nous avons étudié 25 radiographies des fémurs d'enfants de 0 à 13 ans. Nos résultats montrent que cet angle est nul chez le nouveau-né et qu'il apparait en lien avec l'apprentissage de la marche. La formation de cet angle correspond à un phénomène morphogénétique exclusivement diaphysaire, indépendant de la croissance de l'épiphyse distale. Nous montrons que l'angle d'obliquité fémorale, qui apparait occasionnellement chez certains primates non humains, n'est pas homologue de celui que l'on observe chez l'homme., Tardieu Christine. L'angle bicondylaire du fémur est-il homologue chez l'homme et les primates non humains ? Réponse ontogénétique. In: Bulletins et Mémoires de la Société d'anthropologie de Paris, Nouvelle Série. Tome 5 fascicule 1-2, 1993. pp. 159-168.

The developing fetus is protected from external environmental influences by maternal tissues. However, these structures have a limited elasticity, such that the fetus must grow in a confined space, constraining its size at the end of pregnancy. Can these constraints modify the morphology of the fetal skeleton? The intensity of these constraints increases between 5 months and birth, making it the most appropriate period to address this question. A sample of 89 fetal femora was analyzed, and results provide evidence that during this period, the tor- sion of the femoral shaft (quantified by means of a new three-dimensional method) increases gradually. Two explanations were considered: this increase could signal effects of constraints induced by the intrauterine cavity, developmental patterning, or some combination of these two. Different arguments tend to support the biomechani- cal explanation, rather than a programming pattern for- mation. Indeed, the identification of the femur as a first degree lever, created by the hyperflexion of the fetal lower limbs on the pelvis, could explain the increase in femoral shaft torsion during prenatal life. A comparison with fem- ora of infants is in accordance with this mechanical inter- pretation, which is possible through bone modeling/remod- eling. Although genetic and epigenetic mechanisms may regulate timing of fetal development, our data suggest that at birth, the fetal skeleton also has an intrauterine mechanical history through adaptive bone plasticity. Am J Phys Anthropol 000:000-000, 2011. V C 2011 Wiley-Liss, Inc.

During hominin evolution, an increase in the femoral bicondylar angle was the initial change that led to selection for protuberance of the lateral trochlear lip and the elliptical profile of the lateral condyle. No correlation is found during ontogeny between the degree of femoral obliquity and of the prominence of the lateral trochlear lip. Might there be a relationship with the elliptical profile of the lateral condyle? On intact femoral diaphyses of juvenile humans and great apes, we compared the anteroposterior length of the lateral and medial sides of the distal metaphysis. The two diaphyseal pillars remain equal during postnatal growth in great apes, while the growth of the lateral pillar far exceeds that of the medial pillar in humans. Increase in bicondylar angle is correlated with disproportionate anteroposterior lengthening of the lateral pillar. The increased anteroposterior length of the lateral side of the metaphysis would contribute to increasing the radius of the curvature of the lateral condyle, but not to the projection of the lateral trochlear lip. The similar neonatal and adult femoro-patellar joint shape in humans prompted an assessment of the similarity during growth of the entire neonatal and adult epiphyses. We showed that the entire epiphysis undergoes drastic changes in proportions during postnatal growth. Finally, we emphasize the need to distinguish the cartilaginous phenotype and the ossified phenotype of the distal femoral epiphysis (and of any epiphysis) during postnatal growth. This crucial distinction applies to most postcranial bones, for they almost all develop following the process of endochondral ossification.

The aim of this study was to assess pelvic asymmetry (i.e. to determine whether the right iliac bone and the right part of the sacrum are mirror images of the left), both quantitatively and qualitatively, using three-dimensional measurements. Pelvic symmetry was described osteologically using a common reference coordinate system for a large sample of pelvises. Landmarks were established on 12 anatomical specimens with an electromagnetic Fastrak system. Seventy-one paired variables were tested with a paired t-test and a non-parametric test (Wilcoxon). A Pearson correlation matrix between the right and left values of the same variable was applied exclusively to values that were significantly asymmetric in order to calculate a dimensionless asymmetry index, ABGi, for each variable. Fifteen variables were significantly asymmetric and correlated with the right vs. left sides for the following anatomical regions: sacrum, iliac blades, iliac width, acetabulum and the superior lunate surface of the acetabulum. ABGi values above a threshold of +/- 4.8% were considered significantly asymmetric in seven variables of the pelvic area. Total asymmetry involving the right and the left pelvis seems to follow a spiral path in the pelvis; in the upper part, the iliac blades rotate clockwise, and in the lower part, the pubic symphysis rotates anticlockwise. Thus, pelvic asymmetry may be evaluated in clinical examinations by measuring iliac crest orientation.

We analysed 51 adult pelvises (25 women, 26 men) by the software DE-VISU, conceived by one of us, J. Hecquet. It allows the description of the pelvis as the keystone of the articular system linking vertebral column, pelvis and lower limbs. The variations of the sagittal pelvic parameter, 'angle of incidence' (mean 54 degrees), allow us to predict individual variation in sagittal spine curves. The extreme values of incidence (32 degrees-76 degrees) correspond to pathological situations. This angle was discovered by radiological observations. We elucidated the morphological components of this angle: a high angle of incidence, associated with a strong lumbar curvature, is correlated to a strong sacral slope, a curved sacrum, a low position of the sacrum in relation to iliac crests. A low angle of incidence, associated with a weak lumbar curvature, is correlated to a weak sacral slope, a rectilinear sacrum, a high sacral position in relation to iliac crests. The performances of the software DE-VISU gave results far superior to those we obtained by geometric morphometry. It benefits from previous studies and publications of the authors on rachis, pelvis and lower limb. Ability to represent each pelvic joint, particularly the two coxo-femoral joints, was crucial. Calculation of centres, radii, directional axes and covering arches of the acetabula allowed us to quantify the parameters of their three-dimensional orientation. We put in light for the first time these parameters. The angles of acetabular anteversion, inclination and covering arch revealed their high variations. These parameters establish the relationship between pelvis and mechanical axes of lower limbs through the femoral angles: angle of anteversion of the femoral neck, cervico-diaphyseal angle and bicondylar angle. DE-VISU introduced for the first time a,systemic analysis' of the pelvis: it is no longer considered as an isolated object but as a piece of an integrated articular system.

The authors performed a biometric analysis of the femoral patellar groove in fetus and compared their findings with those observed in adults. Forty-four formalin-preserved fetuses were studied (13-38 weeks). Digitalized images were used to obtain measurements (alpha angle of the groove, trochlear slopes thetaL and thetaM). A comparison of means of independent samples between our series and adults was performed. For each angle of the distal epiphysis (alpha, thetaL, thetaM) there was no significant difference between this fetal series and adults. This is the first biometry of the fetal patellar groove. The morphology of the lower femur appears to be the same in fetus and adults. The results of this study suggest that the anatomic characteristics of the patellar groove could have been integrated into the genome during the course of evolution. This would be in favor of a genetic origin of patellar groove dysplasia.

Two angles effectively describe the upper femur geometry: The neck shaft angle (NSA) and anteversion (AV). AV and NSA decrease from birth until they reach their adult values, but little work has focused on in-utero life. Our aim was to determine if and how AV and NSA change through the fetal life. Eighty-seven femurs from 44 formalin preserved fetuses were sampled to achieve a biometry. Correlation tests and linear regression showed that AV was highly correlated with age: AV increases during the second half of gestation. No conclusion can be given concerning NSA. It is speculated that these changes may be caused by mechanical stresses.

Pelvis and spinal curves were studied with an angular parameter typical of pelvis morphology: pelvic incidence. A significant chain of correlations between positional pelvic and spinal parameters and incidence is known. This study investigated standards of incidence and a predictive equation of lordosis from selective pelvic and spinal individual parameters. One hundred and forty nine (78 men and 71 women) healthy adults, aged 19-50 years, with no spinal disorders, were included and had a full-spine lateral X-ray in a standardised upright position. Computerised technology was used for the measurement of angular parameters. Mean-deviation section of each parameter and Pearson correlation test were calculated. A multivariate selection algorithm was running with the lordosis (predicted variable) and the other spinal and pelvic parameters (predictor variables), to determine the best sets of predictors to include in the model. A low incidence (44 degrees ) decreased sacral-slope and the lordosis is flattened. A high incidence (62 degrees ) increased sacral-slope and the lordosis is more pronounced. Lordosis predictive equation is based on incidence, kyphosis, sacral-slope and +/-T9 tilt. The confidence limits and the residuals (the difference between measured and predicted lordosis) assessed the predicted lordosis accuracy of the model: respectively, +/-1.65 and 2.41 degrees with the 4-item model; +/-1.73 and 3.62 degrees with the 3-item model. The ability of the functional spine-pelvis unit to search for a sagittal balance depended both on the incidence and on the variation section of the other positional parameters. Incidence gave an adaptation potential at two levels of positional compensation: overlying state (kyphosis, T9 tilt), underlying state (sacral slope, pelvic tilt). The biomechanical and clinical conditions of the standing posture (as in scoliosis, low back pain, spondylisthesis, spine surgery, obesity and postural impairments) can be studied by comparing the measured lordosis with the predicted lordosis.

Results of a study of the femoral bicondylar angle in adult and juvenile humans and great apes are presented. These results raise the question of whether or not the measurement reference of this angle is valid. This is because humans and great apes have a very different growth process of the distal epiphyseal suture of the femur during the period between birth and adulthood. The approximately 3 million years old juvenile femoral diaphyses attributed to Australopithecus afarensis (AL 333-110 and AL 333-111) were also studied. These specimens show an insertion of the diaphysis into the epiphysis of the simplified type typical of modern humans. This region is more convoluted in nonhuman anthropoids. Pelvifemoral interrelations are investigated through both longitudinal and cross-sectional radiographic studies of 23 human children. Growth changes in bicondylar and collo-diaphyseal angles, total femoral and femoral neck lengths, and interacetabular distance are correlated with age and to each other. These results are used to demonstrate the distinctive features of the Australopithecus afarensis fossil, AL 288–1.

The current biomechanical interpretation of the chimpanzee's bipedal walking argues that larger lateral and vertical displacements of the body center of mass occur in the chimpanzee's “side-to-side” gait than in the human striding gait. The evolutionary hypothesis underlying this study is the following: during the evolution of human bipedalism one of the necessary changes could have been the progressive reduction of these displacements of the body center of mass. In order to quantitatively test this hypothesis, it is necessary to obtain simultaneously the trajectories of the centers of mass of the whole body and of the different body parts. To solve this problem, a new method of three-dimensional analysis of walking, associated with a volumetric modelling of the body, has been developed based on finite-element modelling. An orthogonal synchrophotographic device yielding four synchronous pictures of the walking subject allows a qualitative analysis of the photographic sequences together with the results of their quantitative analysis. This method was applied to an adult man, a 3-year-old girl and a 9-year-old male chimpanzee. Our results suggest that the trajectory of the body center of mass of the human is distinguished from that of the chimpanzee not by a lower movement amplitude but by the synchronization of the transverse and vertical displacements into two periodic curves in phase with one another. The non-human primate uses its repertoire of arboreal movements in its bipedal terrestrial gait, provisionally referred to as a “rope-walker” gait. We show that the interpretation of a “side-to-side” gait is not applicable to the chimpanzee. We argue that similarly this interpretation and the initial hypothesis presuppose a basic symmetric structure of the gait, in relation to the sagittal plane of progression, similar to the human one. This lateral symmetry of the right and left displacements of the center of gravity, in phase with the right and left single supports of walking, is probably a very derived feature of the human gait. We suggest that low lateral and vertical displacements of the body center of mass are not indicative of a progressive bipedal gait and we discuss the new evolutionary implications of our results. © 1993 Wiley-Liss, Inc.

Le but de notre etude etait d’evaluer deux parametres morphometriques pelviens. Les fiabilites et reproductibilites de deux parametres morphometriques pelviens, l’Epaisseur (distance entre le milieu du plateau superieur du sacrum et le milieu de l’axe bi-coxo-femoral) et l’Incidence (angle entre la perpendiculaire appliquee au centre du plateau superieur du sacrum et l’Epaisseur) etaient evaluees en comparant leur mesure anatomique et radiologique. Materiel et methode La mesure 3D de 12 pieces anatomiques etait realisee avec un systeme electromagnetique Fastrak. La mesure radiologique des parametres etait effectuee sur une radiographie de profil. Le coefficient d’agrandissement etait 1,113, une analyse statistique etait realisee. Resultat L’incidence, les comparaisons de moyennes et de variances (anatomie versus radiologie) n’etaient pas significatives ; une correlation positive tres significative existait entre mesure anatomique et radiologique (r = 0,98 ; p Discussion Le manque de fiabilite de la distance radiologique, Epaisseur, est imputable aux conditions techniques de la radiographie. L’incidence, angle radiologique, est fiable. Conclusion En pratique clinique, cette technique pourrait valider la mesure radiologique de la seule Incidence comme indice personnel precis de la morphologie pelvienne.

Resume Nous proposons un schema evolutif des caracteres de l'articulation du genou des primates catarhiniens actuels et des primates hominoides fossiles. Nous avons etudie les fossiles plio-pleistocenes appartenant aux genres Australopithecus et Homo et les fossiles miocenes: Oreopithecus bambolii, Paidopithex rhenanus, Pliopithecus vindobonensis. L'etat plesiomorphe de catarhinien, initiant notre schema, fait l'objet d'une hypothese, qui semblerait confirmee par une etude phylogenetique recente concernant le femur des primates platyrhiniens.

The author lay down a morphofunctional scheme of analysis of Catarhine Primates knee-joint and apply it to fossils hominids. This analysis leads to the distinction of two groups among plio-pleistocène hominids : — a modern group, Homo, — a more primitive group, Australopithecus. I propose an evolutive interpretation of these results and a contribution to the taxonomy of fossil hominids, particulary the fossils from Afar (Ethiopia)., Une grille d'analyse morphofonctionnelle de l'articulation du genou des Primates catarhiniens a été établie, que nous avons appliquée aux Hominidés fossiles. Cette analyse nous permet de distinguer deux groupes au sein des Hominidés plio pleistocènes, un groupe moderne rattaché au genre Homo et un groupe plus primitit rattaché au genre Australopithecus. Nous proposons une interprétation évolutive de ces résultats et apportons une certaine contribution à la taxinomie des Hominidés fossiles, en particulier ceux du gisement de l'Afar en Ethiopie., Tardieu Christine. L'articulation du genou des Primates catarhiniens et Hominidés fossiles. Implications phylogénétique et taxinomique. In: Bulletins et Mémoires de la Société d'anthropologie de Paris, XIII° Série. Tome 10 fascicule 3, 1983. pp. 355-372.

International audience; The authors performed a biometric analysis of the femoral patellar groove in fetus and compared their findings with those observed in adults. Forty-four formalin-preserved fetuses were studied (13-38 weeks). Digitalized images were used to obtain measurements ([alpha] angle of the groove, trochlear slopes [theta]L and [theta]M). A comparison of means of independent samples between our series and adults was performed. For each angle of the distal epiphysis ([alpha], [theta]L, [theta]M) there was no significant difference between this fetal series and adults. This is the first biometry of the fetal patellar groove. The morphology of the lower femur appears to be the same in fetus and adults. The results of this study suggest that the anatomic characteristics of the patellar groove could have been integrated into the genome during the course of evolution. This would be in favor of a genetic origin of patellar groove dysplasia.

International audience; We performed a biometric analysis of the femoral trochlear groove in the fetus and compared our findings with those observed in adults. We studied 44 formalin-preserved fetuses (13–38 weeks) and used digitized images to obtain measurements (a angle of the groove, trochlear slopes ?L and ?M). A comparison of means between our series and adults was achieved. For each angle of the distal epiphysis (a, ?L, ?M) there was no significant difference between our fetal series and adults. This is the first biometric study of fetal trochlea. The morphology of the lower femur appears to be the same in the fetus and the adult.