title: Load response of the tarsal bones in patients with flatfoot deformity: in vivo 3D study.
abstract: BACKGROUND
  The objective of this study was to evaluate the bone rotation of each joint in the hindfoot and compare the load response in healthy feet with that in flatfeet by analyzing the reconstructive three-dimensional (3D) CT image data during weightbearing.
  
  
  METHODS
  CT scans of 21 healthy feet and 21 feet with flatfoot deformity were taken in non-load condition followed by full-body weightbearing load condition. The images of the hindfoot bones were reconstructed into 3D models. The volume merge method in three planes was used to calculate the position of the talus relative to the tibia in the tibiotalar joint, the navicular relative to the talus in talonavicular joint, and the calcaneus relative to the talus in the talocalcaneal joint.
  
  
  RESULTS
  The talar position difference to the load response relative to the tibia in the tibiotalar joint in a flatfoot was 1.7 degrees more plantarflexed in comparison to that in a healthy foot (p = 0.031). The navicular position difference to the load response relative to the talus in the talonavicular joint was 2.3 degrees more everted (p = 0.0034). The calcaneal position difference to the load response relative to the talus in the talocalcaneal joint was 1.1 degrees more dorsiflexed (p = 0.0060) and 1.7 degrees more everted (p = 0.0018).
  
  
  CONCLUSIONS
  Referring to previous cadaver study, regarding not only the cadaveric foot, but also the live foot, joint instability occurred in the hindfoot with load in patients with flatfoot.
  
  
  CONCLUSIONS
  The method used in this study might be applied to clinical analysis of foot diseases such as the staging of flatfoot and to biomechanical analysis to evaluate the effects of foot surgery in the future.
authors.affiliation: Department of Orthopaedics, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, Japan.
authors.forename: Masamitsu
authors.initials: M
authors.lastname: Kido
authors.forename: Kazuya
authors.initials: K
authors.lastname: Ikoma
authors.forename: Kan
authors.initials: K
authors.lastname: Imai
authors.forename: Masahiro
authors.initials: M
authors.lastname: Maki
authors.forename: Ryota
authors.initials: R
authors.lastname: Takatori
authors.forename: Daisaku
authors.initials: D
authors.lastname: Tokunaga
authors.forename: Nozomu
authors.initials: N
authors.lastname: Inoue
authors.forename: Toshikazu
authors.initials: T
authors.lastname: Kubo
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D002111:Calcaneus / Q000503:physiopathology; D005260:Female; D005413:Flatfoot / Q000503:physiopathology*; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D013639:Tarsal Bones / Q000503:physiopathology*; D016474:Weight-Bearing / Q000502:physiology; D055815:Young Adult