title: Weight-bearing three-dimensional computed tomography analysis of the forefoot in patients with flatfoot deformity.
abstract: BACKGROUND
  The recent classifications for posterior tibial tendon dysfunction (PTTD) stage II are based on forefoot deformity, but there is still no consensus regarding a detailed explanation of the clinical condition. The purposes of this study were to clarify the clinical condition of flatfoot deformity using three-dimensional (3D) computed tomography (CT) imaging under loading on both healthy and flat feet and to compare 3D movement of the forefoot in response to load.
  
  
  METHODS
  Ten volunteers and 10 PTTD stage II patients with symptomatic flatfoot deformity were examined. CT scans of 20 healthy and 20 flat feet were performed under non-loading and full weight-bearing conditions. Images of the tibia and foot arch bones (talus, calcaneus, navicular, and first and fifth metatarsal bones) were reconstructed into 3D models. Rotations of individual tarsal bone or metatarsal bone were described by the Eulerian angles.
  
  
  RESULTS
  Compared with healthy feet, flat feet experienced plantarflexion of the fifth metatarsal bone relative to the first metatarsal bone under loading conditions. We defined this phenomenon as synonymous with forefoot varus on the coronal plane.
  
  
  CONCLUSIONS
  The results of this study have clarified part of the clinical condition of the forefoot in flatfoot deformity and may have applications in basic research of the staging advancement and substage classification of PTTD.
authors.affiliation: Department of Orthopaedics, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Japan.
authors.forename: Naoki
authors.initials: N
authors.lastname: Yoshioka
authors.affiliation: Department of Orthopaedics, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Japan. Electronic address: kazuya@koto.kpu-m.ac.jp.
authors.forename: Kazuya
authors.initials: K
authors.lastname: Ikoma
authors.affiliation: Department of Orthopaedics, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Japan.
authors.forename: Masamitsu
authors.initials: M
authors.lastname: Kido
authors.affiliation: Department of Orthopaedics, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Japan.
authors.forename: Kan
authors.initials: K
authors.lastname: Imai
authors.affiliation: Department of Orthopaedics, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Maki
authors.affiliation: Department of Orthopaedics, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Japan.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Arai
authors.affiliation: Department of Orthopaedics, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Japan.
authors.forename: Hiroyoshi
authors.initials: H
authors.lastname: Fujiwara
authors.affiliation: Department of Orthopaedics, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Japan.
authors.forename: Daisaku
authors.initials: D
authors.lastname: Tokunaga
authors.affiliation: Department of Orthopedic Surgery, Rush University Medical Center, United States.
authors.forename: Nozomu
authors.initials: N
authors.lastname: Inoue
authors.affiliation: Department of Orthopaedics, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Japan.
authors.forename: Toshikazu
authors.initials: T
authors.lastname: Kubo
mesh_terms: D000328:Adult; D000368:Aged; D001696:Biomechanical Phenomena; D005260:Female; D005413:Flatfoot / Q000145:classification / Q000175:diagnosis / Q000503:physiopathology*; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D008875:Middle Aged; D016059:Range of Motion, Articular / Q000502:physiology*; D013639:Tarsal Bones / Q000000981:diagnostic imaging / Q000503:physiopathology*; D014057:Tomography, X-Ray Computed / Q000379:methods*; D016474:Weight-Bearing / Q000502:physiology*; D055815:Young Adult