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Wang Y, Liang W, Chen Y, Li S, Ji H, Feng Z, Ma D, Zhong S, Ouyang J, Qian L. Sex-specific bone and muscular morphological features in ischiofemoral impingement: A three-dimensional study. Clin Anat 2023; 36:1095-1103. [PMID: 36905221 DOI: 10.1002/ca.24036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Revised: 02/14/2023] [Accepted: 02/22/2023] [Indexed: 03/12/2023]
Abstract
The study aimed to investigate how hip bone and muscular morphology features differ between ischiofemoral impingement (IFI) patients and healthy subjects among males and females. Three-dimensional models were reconstructed based on magnetic resonance imaging images from IFI patients and healthy subjects of different sexes. Bone morphological parameters and the cross-sectional area of the hip abductors were measured. The diameter and angle of the pelvis were compared between patients and healthy subjects. Bone parameters of the hip and cross-sectional area of the hip abductors were compared between affected and healthy hips. The comparison results of some parameters were significant for females but not males. For females, the comparison results of pelvis parameters showed that the anteroposterior diameter of the pelvic inlet (p = 0.001) and intertuberous distance (p < 0.001) were both larger in IFI patients than in healthy subjects. Additionally, the comparison results of hip parameters showed that the neck shaft angle (p < 0.001) and the cross-sectional area of the gluteus medius (p < 0.001) and gluteus minimus (p = 0.005) were smaller, while the cross-sectional area of the tensor fasciae latae (p < 0.001) was significantly larger in affected hips. Morphological changes in IFI patients demonstrated sexual dimorphism, including bone and muscular morphology. Differences in the anteroposterior diameter of the pelvic inlet, intertuberous distance, neck shaft angle, gluteus medius, and gluteus minimus may explain why females are more susceptible to IFI.
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Affiliation(s)
- Yining Wang
- Department of Anatomy, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
- Guangdong Provincial Key Laboratory of Digital Medicine and Biomechanics, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
- Guangdong Engineering Research Center for Translation of Medical 3D Printing Application, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
- National Virtual and Reality Experimental Education Center for Medical Morphology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
- National Experimental Education Demonstration Center for Basic Medical Sciences, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
- National Key Discipline of Human Anatomy, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China, Guangzhou, China
| | - Wenjie Liang
- Department of Anatomy, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
- Guangdong Provincial Key Laboratory of Digital Medicine and Biomechanics, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
- Guangdong Engineering Research Center for Translation of Medical 3D Printing Application, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
- National Virtual and Reality Experimental Education Center for Medical Morphology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
- National Experimental Education Demonstration Center for Basic Medical Sciences, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
- National Key Discipline of Human Anatomy, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China, Guangzhou, China
| | - Yanjun Chen
- Department of Medical Imaging, The Third Affiliated Hospital, Southern Medical University, Guangzhou, China
| | - ShaoLin Li
- Department of medical imaging, The Fifth Affiliated Hospital, Sun Yat-Sen University, Zhuhai, Guangdong, China
| | - Hongli Ji
- Department of General Surgery, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Zhengkuan Feng
- Department of Anatomy, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
- Guangdong Provincial Key Laboratory of Digital Medicine and Biomechanics, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
- Guangdong Engineering Research Center for Translation of Medical 3D Printing Application, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
- National Virtual and Reality Experimental Education Center for Medical Morphology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
- National Experimental Education Demonstration Center for Basic Medical Sciences, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
- National Key Discipline of Human Anatomy, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China, Guangzhou, China
| | - Dong Ma
- Department of Anatomy, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
- Guangdong Provincial Key Laboratory of Digital Medicine and Biomechanics, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
- Guangdong Engineering Research Center for Translation of Medical 3D Printing Application, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
- National Virtual and Reality Experimental Education Center for Medical Morphology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
- National Experimental Education Demonstration Center for Basic Medical Sciences, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
- National Key Discipline of Human Anatomy, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China, Guangzhou, China
| | - Shizhen Zhong
- Department of Anatomy, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
- Guangdong Provincial Key Laboratory of Digital Medicine and Biomechanics, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
- Guangdong Engineering Research Center for Translation of Medical 3D Printing Application, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
- National Virtual and Reality Experimental Education Center for Medical Morphology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
- National Experimental Education Demonstration Center for Basic Medical Sciences, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
- National Key Discipline of Human Anatomy, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China, Guangzhou, China
| | - Jun Ouyang
- Department of Anatomy, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
- Guangdong Provincial Key Laboratory of Digital Medicine and Biomechanics, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
- Guangdong Engineering Research Center for Translation of Medical 3D Printing Application, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
- National Virtual and Reality Experimental Education Center for Medical Morphology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
- National Experimental Education Demonstration Center for Basic Medical Sciences, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
- National Key Discipline of Human Anatomy, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China, Guangzhou, China
| | - Lei Qian
- Department of Anatomy, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
- Guangdong Provincial Key Laboratory of Digital Medicine and Biomechanics, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
- Guangdong Engineering Research Center for Translation of Medical 3D Printing Application, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
- National Virtual and Reality Experimental Education Center for Medical Morphology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
- National Experimental Education Demonstration Center for Basic Medical Sciences, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
- National Key Discipline of Human Anatomy, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China, Guangzhou, China
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Grunstra NDS, Betti L, Fischer B, Haeusler M, Pavlicev M, Stansfield E, Trevathan W, Webb NM, Wells JCK, Rosenberg KR, Mitteroecker P. There is an obstetrical dilemma: Misconceptions about the evolution of human childbirth and pelvic form. AMERICAN JOURNAL OF BIOLOGICAL ANTHROPOLOGY 2023; 181:535-544. [PMID: 37353889 PMCID: PMC10952510 DOI: 10.1002/ajpa.24802] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2023] [Revised: 05/27/2023] [Accepted: 06/11/2023] [Indexed: 06/25/2023]
Abstract
Compared to other primates, modern humans face high rates of maternal and neonatal morbidity and mortality during childbirth. Since the early 20th century, this "difficulty" of human parturition has prompted numerous evolutionary explanations, typically assuming antagonistic selective forces acting on maternal and fetal traits, which has been termed the "obstetrical dilemma." Recently, there has been a growing tendency among some anthropologists to question the difficulty of human childbirth and its evolutionary origin in an antagonistic selective regime. Partly, this stems from the motivation to combat increasing pathologization and overmedicalization of childbirth in industrialized countries. Some authors have argued that there is no obstetrical dilemma at all, and that the difficulty of childbirth mainly results from modern lifestyles and inappropriate and patriarchal obstetric practices. The failure of some studies to identify biomechanical and metabolic constraints on pelvic dimensions is sometimes interpreted as empirical support for discarding an obstetrical dilemma. Here we explain why these points are important but do not invalidate evolutionary explanations of human childbirth. We present robust empirical evidence and solid evolutionary theory supporting an obstetrical dilemma, yet one that is much more complex than originally conceived in the 20th century. We argue that evolutionary research does not hinder appropriate midwifery and obstetric care, nor does it promote negative views of female bodies. Understanding the evolutionary entanglement of biological and sociocultural factors underlying human childbirth can help us to understand individual variation in the risk factors of obstructed labor, and thus can contribute to more individualized maternal care.
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Affiliation(s)
- N. D. S. Grunstra
- Department of Evolutionary Biology, Unit for Theoretical BiologyUniversity of ViennaViennaAustria
- Mammal CollectionNatural History Museum ViennaViennaAustria
| | - L. Betti
- School of Life and Health SciencesUniversity of RoehamptonLondonUK
| | - B. Fischer
- Department of Evolutionary Biology, Unit for Theoretical BiologyUniversity of ViennaViennaAustria
| | - M. Haeusler
- Institute of Evolutionary MedicineUniversity of ZurichZurichSwitzerland
| | - M. Pavlicev
- Department of Evolutionary Biology, Unit for Theoretical BiologyUniversity of ViennaViennaAustria
| | - E. Stansfield
- Department of Evolutionary Biology, Unit for Theoretical BiologyUniversity of ViennaViennaAustria
| | - W. Trevathan
- School for Advanced ResearchSanta FeNew MexicoUSA
| | - N. M. Webb
- Institute of Evolutionary MedicineUniversity of ZurichZurichSwitzerland
- Institute of Archaeological Sciences, Senckenberg Centre for Human Evolution and PalaeoenvironmentEberhard‐Karls University of TübingenTübingenGermany
| | - J. C. K. Wells
- UCL Great Ormond Street Institute of Child Health, Population, Policy and Practice Research and Teaching ProgrammeChildhood Nutrition Research CentreLondonUK
| | - K. R. Rosenberg
- Department of AnthropologyUniversity of DelawareNewarkDelawareUSA
| | - P. Mitteroecker
- Department of Evolutionary Biology, Unit for Theoretical BiologyUniversity of ViennaViennaAustria
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3
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Stansfield E, Fischer B, Grunstra NDS, Pouca MV, Mitteroecker P. The evolution of pelvic canal shape and rotational birth in humans. BMC Biol 2021; 19:224. [PMID: 34635119 PMCID: PMC8507337 DOI: 10.1186/s12915-021-01150-w] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Accepted: 09/09/2021] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND The human foetus typically needs to rotate when passing through the tight birth canal because of the complex shape of the pelvis. In most women, the upper part, or inlet, of the birth canal has a round or mediolaterally oval shape, which is considered ideal for parturition, but it is unknown why the lower part of the birth canal has a pronounced anteroposteriorly oval shape. RESULTS Here, we show that the shape of the lower birth canal affects the ability of the pelvic floor to resist the pressure exerted by the abdominal organs and the foetus. Based on a series of finite element analyses, we found that the highest deformation, stress, and strain occur in pelvic floors with a circular or mediolaterally oval shape, whereas an anteroposterior elongation increases pelvic floor stability. CONCLUSIONS This suggests that the anteroposterior oval outlet shape is an evolutionary adaptation for pelvic floor support. For the pelvic inlet, by contrast, it has long been assumed that the mediolateral dimension is constrained by the efficiency of upright locomotion. But we argue that the mediolateral elongation has evolved because of the limits on the anteroposterior diameter imposed by upright posture. We show that an anteroposteriorly deeper inlet would require greater pelvic tilt and lumbar lordosis, which compromises spine health and the stability of upright posture. These different requirements of the pelvic inlet and outlet likely have led to the complex shape of the pelvic canal and to the evolution of rotational birth characteristic of humans.
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Affiliation(s)
- Ekaterina Stansfield
- Department of Evolutionary Biology, Unit for Theoretical Biology, University of Vienna, Djerassiplatz 1, 1030, Vienna, Austria.
| | - Barbara Fischer
- Department of Evolutionary Biology, Unit for Theoretical Biology, University of Vienna, Djerassiplatz 1, 1030, Vienna, Austria
| | - Nicole D S Grunstra
- Department of Evolutionary Biology, Unit for Theoretical Biology, University of Vienna, Djerassiplatz 1, 1030, Vienna, Austria
- Konrad Lorenz Institute for Evolution and Cognition Research, Martinstrasse 12, 3400, Klosterneuburg, Austria
- Mammal Collection, Natural History Museum Vienna, Burgring 7, 1010, Vienna, Austria
| | - Maria Villa Pouca
- Faculty of Engineering of University of Porto (FEUP), Rua Dr. Roberto Frias, s/n, 4200-465, Porto, Portugal
- Institute of Science and Innovation in Mechanical and Industrial Engineering (INEGI/LAETA), Rua Dr. Roberto Frias, 400, 4200-465, Porto, Portugal
| | - Philipp Mitteroecker
- Department of Evolutionary Biology, Unit for Theoretical Biology, University of Vienna, Djerassiplatz 1, 1030, Vienna, Austria.
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Haeusler M, Grunstra ND, Martin RD, Krenn VA, Fornai C, Webb NM. The obstetrical dilemma hypothesis: there's life in the old dog yet. Biol Rev Camb Philos Soc 2021; 96:2031-2057. [PMID: 34013651 PMCID: PMC8518115 DOI: 10.1111/brv.12744] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Revised: 05/06/2021] [Accepted: 05/10/2021] [Indexed: 12/17/2022]
Abstract
The term 'obstetrical dilemma' was coined by Washburn in 1960 to describe the trade-off between selection for a larger birth canal, permitting successful passage of a big-brained human neonate, and the smaller pelvic dimensions required for bipedal locomotion. His suggested solution to these antagonistic pressures was to give birth prematurely, explaining the unusual degree of neurological and physical immaturity, or secondary altriciality, observed in human infants. This proposed trade-off has traditionally been offered as the predominant evolutionary explanation for why human childbirth is so challenging, and inherently risky, compared to that of other primates. This perceived difficulty is likely due to the tight fit of fetal to maternal pelvic dimensions along with the convoluted shape of the birth canal and a comparatively low degree of ligamentous flexibility. Although the ideas combined under the obstetrical dilemma hypothesis originated almost a century ago, they have received renewed attention and empirical scrutiny in the last decade, with some researchers advocating complete rejection of the hypothesis and its assumptions. However, the hypothesis is complex because it presently captures several, mutually non-exclusive ideas: (i) there is an evolutionary trade-off resulting from opposing selection pressures on the pelvis; (ii) selection favouring a narrow pelvis specifically derives from bipedalism; (iii) human neonates are secondarily altricial because they are born relatively immature to ensure that they fit through the maternal bony pelvis; (iv) as a corollary to the asymmetric selection pressure for a spacious birth canal in females, humans evolved pronounced sexual dimorphism of pelvic shape. Recently, the hypothesis has been challenged on both empirical and theoretical grounds. Here, we appraise the original ideas captured under the 'obstetrical dilemma' and their subsequent evolution. We also evaluate complementary and alternative explanations for a tight fetopelvic fit and obstructed labour, including ecological factors related to nutrition and thermoregulation, constraints imposed by the stability of the pelvic floor or by maternal and fetal metabolism, the energetics of bipedalism, and variability in pelvic shape. This reveals that human childbirth is affected by a complex combination of evolutionary, ecological, and biocultural factors, which variably constrain maternal pelvic form and fetal growth. Our review demonstrates that it is unwarranted to reject the obstetrical dilemma hypothesis entirely because several of its fundamental assumptions have not been successfully discounted despite claims to the contrary. As such, the obstetrical dilemma remains a tenable hypothesis that can be used productively to guide evolutionary research.
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Affiliation(s)
- Martin Haeusler
- Institute of Evolutionary MedicineUniversity of ZurichWinterthurerstrasse 190Zürich8057Switzerland
| | - Nicole D.S. Grunstra
- Konrad Lorenz Institute (KLI) for Evolution and Cognition ResearchMartinstrasse 12Klosterneuburg3400Austria
- Department of Evolutionary BiologyUniversity of ViennaUniversity Biology Building (UBB), Carl Djerassi Platz 1Vienna1030Austria
- Mammal CollectionNatural History Museum ViennaBurgring 7Vienna1010Austria
| | - Robert D. Martin
- Institute of Evolutionary MedicineUniversity of ZurichWinterthurerstrasse 190Zürich8057Switzerland
- The Field Museum1400 S Lake Shore DrChicagoIL60605U.S.A.
| | - Viktoria A. Krenn
- Institute of Evolutionary MedicineUniversity of ZurichWinterthurerstrasse 190Zürich8057Switzerland
- Department of Evolutionary AnthropologyUniversity of ViennaUniversity Biology Building (UBB), Carl Djerassi Platz 1Vienna1030Austria
| | - Cinzia Fornai
- Institute of Evolutionary MedicineUniversity of ZurichWinterthurerstrasse 190Zürich8057Switzerland
- Department of Evolutionary AnthropologyUniversity of ViennaUniversity Biology Building (UBB), Carl Djerassi Platz 1Vienna1030Austria
| | - Nicole M. Webb
- Institute of Evolutionary MedicineUniversity of ZurichWinterthurerstrasse 190Zürich8057Switzerland
- Senckenberg Research Institute and Natural History Museum FrankfurtSenckenberganlage 25Frankfurt am Main60325Germany
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5
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Audenaert EA, Duquesne K, De Roeck J, Mutsvangwa T, Borotikar B, Khanduja V, Claes P. Ischiofemoral impingement: the evolutionary cost of pelvic obstetric adaptation. J Hip Preserv Surg 2021; 7:677-687. [PMID: 34548927 PMCID: PMC8448428 DOI: 10.1093/jhps/hnab004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/28/2020] [Revised: 01/06/2021] [Accepted: 01/13/2021] [Indexed: 12/29/2022] Open
Abstract
The risk for ischiofemoral impingement has been mainly related to a reduced ischiofemoral distance and morphological variance of the femur. From an evolutionary perspective, however, there are strong arguments that the condition may also be related to sexual dimorphism of the pelvis. We, therefore, investigated the impact of gender-specific differences in anatomy of the ischiofemoral space on the ischiofemoral clearance, during static and dynamic conditions. A random sampling Monte-Carlo experiment was performed to investigate ischiofemoral clearance during stance and gait in a large (n = 40 000) virtual study population, while using gender-specific kinematics. Subsequently, a validated gender-specific geometric morphometric analysis of the hip was performed and correlations between overall hip morphology (statistical shape analysis) and standard discrete measures (conventional metric approach) with the ischiofemoral distance were evaluated. The available ischiofemoral space is indeed highly sexually dimorphic and related primarily to differences in the pelvic anatomy. The mean ischiofemoral distance was 22.2 ± 4.3 mm in the females and 29.1 ± 4.1 mm in the males and this difference was statistically significant (P < 0.001). Additionally, the ischiofemoral distance was observed to be a dynamic measure, and smallest during femoral extension, and this in turn explains the clinical sign of pain in extension during long stride walking. In conclusion, the presence of a reduced ischiofemroal distance and related risk to develop a clinical syndrome of ischiofemoral impingement is strongly dominated by evolutionary effects in sexual dimorphism of the pelvis. This should be considered when female patients present with posterior thigh/buttock pain, particularly if worsened by extension. Controlled laboratory study.
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Affiliation(s)
- E A Audenaert
- Department of Orthopedic Surgery and Traumatology, Ghent University Hospital, Corneel Heymanslaan 10, Ghent 9000, Belgium.,Department of Trauma and Orthopedics, Addenbrooke's Hospital, Cambridge University Hospitals NHS Foundation Trust, Hills Road, Cambridge CB2 0QQ, UK.,Department of Electromechanics, Op3Mech Research Group, University of Antwerp, Groenenborgerlaan 171, Antwerp 2020, Belgium.,Department of Human Structure and Repair, Ghent University, Corneel Heymanslaan 10, Ghent 9000, Belgium
| | - K Duquesne
- Department of Human Structure and Repair, Ghent University, Corneel Heymanslaan 10, Ghent 9000, Belgium
| | - J De Roeck
- Department of Human Structure and Repair, Ghent University, Corneel Heymanslaan 10, Ghent 9000, Belgium
| | - T Mutsvangwa
- Division of Biomedical Engineering, University of Cape Town, Anzio Rd, Observatory, Cape Town 7925, South Africa
| | - B Borotikar
- Symbiosis Center for Medical Image Analysis, Symbiosis International University, Lavale, Mulshi District, Pune 412115, India.,Laboratory of Medical Information Processing (LaTIM), UMR 1101, INSERM, Avenue Foch 12, 29200 Brest, France
| | - V Khanduja
- Department of Trauma and Orthopedics, Addenbrooke's Hospital, Cambridge University Hospitals NHS Foundation Trust, Hills Road, Cambridge CB2 0QQ, UK
| | - P Claes
- Department of Human Genetics, KU Leuven, Herestraat 49, 3000 Leuven, Belgium.,Medical Imaging Research Center, University Hospitals Leuven, Herestraat 49, 3000 Leuven, Belgium.,Department of Electrical Engineering, ESAT/PSI, KU Leuven, Herestraat 49, 3000 Leuven, Belgium.,Murdoch Children's Research Institute, Melbourne, Flemington Road, Parkville Victoria 3052, Australia
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6
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Predicting pelvis geometry using a morphometric model with overall anthropometric variables. J Biomech 2021; 126:110633. [PMID: 34388538 DOI: 10.1016/j.jbiomech.2021.110633] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Revised: 06/13/2021] [Accepted: 07/05/2021] [Indexed: 11/24/2022]
Abstract
Pelvic fractures have been identified as the second most common AIS2+ injury in motor vehicle crashes, with the highest early mortality rate compared to other orthopaedic injuries. Further, the risk is associated with occupant sex, age, stature and body mass index (BMI). In this study, clinical pelvic CT scans from 132 adults (75 females, 57 males) were extracted from a patient database. The population shape variance in pelvis bone geometry was studied by Sparse Principal Component Analysis (SPCA) and a morphometric model was developed by multivariate linear regression using overall anthropometric variables (sex, age, stature, BMI). In the analysis, SPCA identified 15 principal components (PCs) describing 83.6% of the shape variations. Eight of these were significantly captured (α < 0.05) by the morphometric model, which predicted 29% of the total variance in pelvis geometry. The overall anthropometric variables were significantly related to geometrical features primarily in the inferior-anterior regions while being unable to significantly capture local sacrum features, shape and position of ASIS and lateral tilt of the iliac wings. In conclusion, a new detailed morphometric model of the pelvis bone demonstrated that overall anthropometric variables account for only 29% of the variance in pelvis geometry. Furthermore, variations in the superior-anterior region of the pelvis, with which the lap belt is intended to interact, were not captured. Depending on the scenario, shape variations not captured by overall anthropometry could have important implications for injury prediction in traffic safety analysis.
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7
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Fischer B, Grunstra NDS, Zaffarini E, Mitteroecker P. Sex differences in the pelvis did not evolve de novo in modern humans. Nat Ecol Evol 2021; 5:625-630. [PMID: 33767411 DOI: 10.1038/s41559-021-01425-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Accepted: 02/24/2021] [Indexed: 01/31/2023]
Abstract
It is commonly assumed that the strong sexual dimorphism of the human pelvis evolved for delivering the relatively large human foetuses. Here we compare pelvic sex differences across modern humans and chimpanzees using a comprehensive geometric morphometric approach. Even though the magnitude of sex differences in pelvis shape was two times larger in humans than in chimpanzees, we found that the pattern is almost identical in the two species. We conclude that this pattern of pelvic sex differences did not evolve de novo in modern humans and must have been present in the common ancestor of humans and chimpanzees, and thus also in the extinct Homo species. We further suggest that this shared pattern was already present in early mammals and propose a hypothesis of facilitated variation as an explanation: the conserved mammalian endocrine system strongly constrains the evolution of the pattern of pelvic differences but enables rapid evolutionary change of the magnitude of sexual dimorphism, which in turn facilitated the rapid increase in hominin brain size.
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Affiliation(s)
- Barbara Fischer
- Department of Evolutionary Biology, Unit for Theoretical Biology, University of Vienna, Vienna, Austria.
| | - Nicole D S Grunstra
- Department of Evolutionary Biology, Unit for Theoretical Biology, University of Vienna, Vienna, Austria.,Konrad Lorenz Institute for Evolution and Cognition Research, Klosterneuburg, Austria.,Mammal Collection, Natural History Museum Vienna, Vienna, Austria
| | - Eva Zaffarini
- Department of Cell Biology and Anatomy, University of Calgary, Calgary, Alberta, Canada
| | - Philipp Mitteroecker
- Department of Evolutionary Biology, Unit for Theoretical Biology, University of Vienna, Vienna, Austria.,Konrad Lorenz Institute for Evolution and Cognition Research, Klosterneuburg, Austria
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8
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Biomechanical trade-offs in the pelvic floor constrain the evolution of the human birth canal. Proc Natl Acad Sci U S A 2021; 118:2022159118. [PMID: 33853947 DOI: 10.1073/pnas.2022159118] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Compared with most other primates, humans are characterized by a tight fit between the maternal birth canal and the fetal head, leading to a relatively high risk of neonatal and maternal mortality and morbidities. Obstetric selection is thought to favor a spacious birth canal, whereas the source for opposing selection is frequently assumed to relate to bipedal locomotion. Another, yet underinvestigated, hypothesis is that a more expansive birth canal suspends the soft tissue of the pelvic floor across a larger area, which is disadvantageous for continence and support of the weight of the inner organs and fetus. To test this "pelvic floor hypothesis," we generated a finite element model of the human female pelvic floor and varied its radial size and thickness while keeping all else constant. This allowed us to study the effect of pelvic geometry on pelvic floor deflection (i.e., the amount of bending from the original position) and tissue stresses and stretches. Deflection grew disproportionately fast with increasing radial size, and stresses and stretches also increased. By contrast, an increase in thickness increased pelvic floor stiffness (i.e., the resistance to deformation), which reduced deflection but was unable to fully compensate for the effect of increasing radial size. Moreover, larger thicknesses increase the intra-abdominal pressure necessary for childbirth. Our results support the pelvic floor hypothesis and evince functional trade-offs affecting not only the size of the birth canal but also the thickness and stiffness of the pelvic floor.
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Berger SM, Griffin JS, Dent SC. Phenotypes and pathways: Working toward an integrated skeletal biology in biological anthropology. Am J Hum Biol 2020; 33:e23450. [PMID: 32511865 DOI: 10.1002/ajhb.23450] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Revised: 04/01/2020] [Accepted: 05/17/2020] [Indexed: 01/02/2023] Open
Affiliation(s)
- Steph M Berger
- Department of Anthropology, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Jacob S Griffin
- Department of Anthropology, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Sophia C Dent
- Department of Anthropology, University of North Carolina, Chapel Hill, North Carolina, USA
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