title: A validated method for modeling anthropoid hip abduction in silico.
abstract: OBJECTIVE
  The ability to reconstruct hip joint mobility from femora and pelves could provide insight into the locomotion and paleobiology of fossil primates. This study presents a method for modeling hip abduction in anthropoids validated with in vivo data.
  
  
  METHODS
  Hip abduction simulations were performed on a large sample of anthropoids. The modeling approach integrates three-dimensional (3D) polygonal models created from laser surface scans of bones, 3D landmark data, and shape analysis software to digitally articulate and manipulate the hip joint. Range of femoral abduction (degrees) and the abducted knee position (distance spanned at the knee during abduction) were compared with published live animal data.
  
  
  RESULTS
  The models accurately estimate knee position and (to a lesser extent) angular abduction across broad locomotor groups. They tend to underestimate abduction for acrobatic or suspensory taxa, but overestimate it in more stereotyped taxa. Correspondence between in vivo and in silico data varies at the specific and generic level.
  
  
  CONCLUSIONS
  Our models broadly correspond to in vivo data on hip abduction, although the relationship between the models and live animal data is less straightforward than hypothesized. The models can predict acrobatic or stereotyped locomotor adaptation for taxa with values near the extremes of the range of abduction ability. Our findings underscore the difficulties associated with modeling complex systems and the importance of validating in silico models. They suggest that models of joint mobility can offer additional insight into the functional abilities of extinct primates when done in consideration of how joints move and function in vivo. Am J Phys Anthropol 160:529-548, 2016. © 2016 Wiley Periodicals, Inc.
authors.affiliation: Center for Advanced Study of Human Paleobiology, Department of Anthropology, George Washington University, Washington, DC, 20052.|Department of Anatomy, Howard University College of Medicine, Washington, DC, 20059.|Department of Pathology and Anatomical Sciences, University of Missouri School of Medicine, Columbia, MO, 65212.
authors.forename: Ashley S
authors.identifier: http://orcid.org/0000-0001-8444-0553
authors.initials: AS
authors.lastname: Hammond
authors.affiliation: Department of Anthropology, University of Arkansas, Fayetteville, AR, 72701.
authors.forename: J Michael
authors.initials: JM
authors.lastname: Plavcan
authors.affiliation: Department of Pathology and Anatomical Sciences, University of Missouri School of Medicine, Columbia, MO, 65212.
authors.forename: Carol V
authors.initials: CV
authors.lastname: Ward
mesh_terms: D000818:Animals; D000885:Anthropology, Physical; D003198:Computer Simulation; D005260:Female; D005580:Fossils; D006621:Hip Joint / Q000033:anatomy & histology* / Q000502:physiology*; D008124:Locomotion / Q000502:physiology; D008297:Male; D011323:Primates / Q000033:anatomy & histology* / Q000502:physiology*; D016059:Range of Motion, Articular / Q000502:physiology*; D015203:Reproducibility of Results
keywords: hip joint mobility; in vivo; limb postures; model validation; primate locomotion