title: Three-dimensional analysis of tarsal bone response to axial loading in patients with hallux valgus and normal feet.
abstract: BACKGROUND
  Patients with hallux valgus present a variety of symptoms that may be related to the type of deformity. Weightbearing affects the deformities, and the evaluation of the load response of tarsal bones has been mainly performed using two-dimensional plane radiography. The purpose of this study was to investigate and compare structural changes in the medial foot arch between patients with hallux valgus and normal controls using a computer image analysis technique and weightbearing computed tomography data.
  
  
  METHODS
  Eleven patients with hallux valgus and eleven normal controls were included. Computed tomograms were obtained with and without simulated weightbearing using a compression device. Computed tomography data were transferred into a personal computer, and a three-dimensional bone model was created using image analysis software. The load responses of each tarsal bone in the medial foot arch were measured three-dimensionally and statistically compared between the two groups.
  
  
  RESULTS
  Displacement of each tarsal bone under two weightbearing conditions was visually observed by creating three-dimensional bone models. At the first metatarsophalangeal joint, the proximal phalanges of the hallux valgus group showed significantly different displacements in multiple directions. Moreover, opposite responses to axial loading were also observed in both translation and rotation between the two groups.
  
  
  CONCLUSIONS
  Weightbearing caused deterioration of the hallux valgus deformity three-dimensionally at the first metatarsophalangeal joint. Information from the computer image analysis was useful for understanding details of the pathology of foot disorders related to the deformities or instability and may contribute to the development of effective conservative and surgical treatments.
authors.affiliation: Department of Physical Therapy, Sapporo Medical University School of Health Sciences, Japan. Electronic address: wkota@sapmed.ac.jp.
authors.forename: Kota
authors.initials: K
authors.lastname: Watanabe
authors.affiliation: Department of Orthopaedic Surgery, Sapporo Medical University School of Medicine, Japan.
authors.forename: Yasutoshi
authors.initials: Y
authors.lastname: Ikeda
authors.affiliation: Department of Musculoskeletal Biomechanics and Surgical Development, Sapporo Medical University, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Suzuki
authors.affiliation: Department of Orthopaedic Surgery, Sapporo Medical University School of Medicine, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Teramoto
authors.affiliation: Department of Orthopaedic Surgery, Sapporo Medical University School of Medicine, Japan.
authors.forename: Takuma
authors.initials: T
authors.lastname: Kobayashi
authors.affiliation: Department of Orthopaedic Surgery, Sapporo Medical University School of Medicine, Japan.
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Suzuki
authors.affiliation: Department of Orthopaedic Surgery, Sapporo Medical University School of Medicine, Japan.
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Yamashita
mesh_terms: D000328:Adult; D000368:Aged; D001696:Biomechanical Phenomena; D016022:Case-Control Studies; D005260:Female; D006215:Hallux Valgus / Q000503:physiopathology* / Q000601:surgery; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D008683:Metatarsophalangeal Joint / Q000503:physiopathology; D008875:Middle Aged; D013639:Tarsal Bones / Q000502:physiology*; D014057:Tomography, X-Ray Computed; D016474:Weight-Bearing / Q000502:physiology*
keywords: Foot; Hallux valgus; Image analysis; Kinematics; Three-dimensional; Weightbearing computed tomography