title: In vivo three-dimensional analysis of hindfoot kinematics.
abstract: BACKGROUND
  Knowledge of normal bone motion of the foot is important for understanding the gait as well as for various pathologies; however, the pattern of 3D motion is not completely understood. The aim of this study was to quantify the in vivo motion of the tibiotalar joint, talocalcaneal joint, and talonavicular joint in normal adult feet using a noninvasive (e.g., nonsurgical) measurement technique.
  
  
  METHODS
  CT images were taken of both feet of ten normal young adults (six males, four females) in neutral, plantarflexion, and dorsiflexion positions of the ankle joint, from which 3D virtual models were made of each mid-hind foot bones. The 3D bone motion of these models was calculated using volume merge methods in three major planes. These data were used to analyze the relationship between the motion of the ankle joint and each other joint.
  
  
  RESULTS
  Tibiotalar rotation was observed in dorsiflexion, abduction, and eversion during maximal dorsiflexion of the ankle joint. Talocalcaneal and talonavicular rotation was very small because the ankle joint motion was limited to the sagittal plane. Tibiotalar rotation was also observed in plantarflexion and adduction during maximal plantarflexion of the ankle joint, and talocalcaneal rotation was very small. Talonavicular rotation was observed in plantarflexion and inversion. The motion of the x-axis and the z-axis of tibiotalar joint, and the x-axis and the y-axis of the talonavicular and talocalcaneal joint were associated with the ankle motion.
  
  
  CONCLUSIONS
  Bone motion could be easily and accurately calculated using volume merge methods more effectively than it could with other methods.
  
  
  CONCLUSIONS
  The data elucidates the baseline segmental motion for comparison with symptomatic subjects which could help us to better understand pathokinematics of various foot and ankle pathologies.
authors.affiliation: Department of Orthopaedics, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, Japan.
authors.forename: Kan
authors.initials: K
authors.lastname: Imai
authors.forename: Daisaku
authors.initials: D
authors.lastname: Tokunaga
authors.forename: Ryota
authors.initials: R
authors.lastname: Takatori
authors.forename: Kazuya
authors.initials: K
authors.lastname: Ikoma
authors.forename: Masahiro
authors.initials: M
authors.lastname: Maki
authors.forename: Hiroki
authors.initials: H
authors.lastname: Ohkawa
authors.forename: Akiko
authors.initials: A
authors.lastname: Ogura
authors.forename: Yoshiro
authors.initials: Y
authors.lastname: Tsuji
authors.forename: Nozomu
authors.initials: N
authors.lastname: Inoue
authors.forename: Toshikazu
authors.initials: T
authors.lastname: Kubo
mesh_terms: D000328:Adult; D000843:Ankle Joint / Q000502:physiology*; D001696:Biomechanical Phenomena; D005260:Female; D005528:Foot / Q000502:physiology*; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D016059:Range of Motion, Articular / Q000502:physiology*; D013380:Subtalar Joint / Q000502:physiology; D013628:Talus / Q000502:physiology