title: First metatarsophalangeal joint motion in Homo sapiens: theoretical association of two-axis kinematics and specific morphometrics.
abstract: BACKGROUND
  The metatarsal head and proximal phalanx exhibit considerable asymmetry in their shape and geometry, but there is little documentation in the literature regarding the prevalence of structural characteristics that occur in a given population. Although there is a considerable volume of in vivo and in vitro experiments demonstrating first metatarsal inversion around its longitudinal axis with dorsiflexion, little is known regarding the applicability of specific morphometrics to these motions.
  
  
  METHODS
  Nine distinctive osseous characteristics in the metatarsal head and phalanx were selected based on their location, geometry, and perceived functional relationship to previous studies describing metatarsal motion as inversion with dorsiflexion. The prevalences of the chosen characteristics were determined in a cohort of 21 randomly selected skeletal specimens, 19 of which were provided by the anatomical preparation office at the University of California, San Diego, and two of which were in the possession of one of us (M.D.).
  
  
  RESULTS
  The frequency of occurrence of each selected morphological characteristic in this sample and the relevant summary statistics confirm a strong association between the selected features and a conceptual two-axis kinematic model of the metatarsophalangeal joint.
  
  
  CONCLUSIONS
  The selected morphometrics are consistent with inversion of the metatarsal around its longitudinal axis as it dorsiflexes.
authors.affiliation: Borrego Medical Foundation, Thermal, CA, USA. Durrant.Michael@gmail.com
authors.forename: Michael N
authors.initials: MN
authors.lastname: Durrant
authors.forename: Tucker
authors.initials: T
authors.lastname: McElroy
authors.forename: Lara
authors.initials: L
authors.lastname: Durrant
mesh_terms: D001696:Biomechanical Phenomena; D006801:Humans; D008682:Metatarsal Bones / Q000033:anatomy & histology* / Q000502:physiology; D008683:Metatarsophalangeal Joint / Q000502:physiology*; D016059:Range of Motion, Articular / Q000502:physiology*; D050277:Toe Phalanges / Q000033:anatomy & histology* / Q000502:physiology