title: Graft shape affects midfoot correction and forefoot loading mechanics in lateral column lengthening osteotomies.
abstract: BACKGROUND
  Adult acquired flatfoot deformity is characterized by midfoot abduction and collapse of the medial longitudinal arch. Lateral column lengthening osteotomies primarily correct the abduction deformity, but the effects of graft shape on deformity correction and forefoot loading are unclear. Therefore, the purpose of this study was to demonstrate the effect of graft shape and taper on deformity correction and forefoot loading mechanics in a cadaveric flatfoot model.
  
  
  METHODS
  Flatfoot deformity was simulated in 18 cadaveric specimens. A lateral column lengthening osteotomy was performed using a triangular, trapezoidal, and rectangular graft for each specimen. During each testing condition, talonavicular joint angles and forefoot plantar pressures were measured.
  
  
  RESULTS
  Each graft shape corrected abduction and dorsiflexion deformity at the talonavicular joint. Coronal plane correction was affected by graft shape, and the less tapered trapezoidal and rectangular grafts overloaded the lateral forefoot compared to the intact condition. The more tapered triangular graft did not cause a lateral shift in forefoot pressures. Forefoot plantar pressures were strongly correlated with talonavicular abduction correction (R (2) = .473, P < .001).
  
  
  CONCLUSIONS
  Graft shape had no effect on the correction of talonavicular abduction or dorsiflexion but did influence coronal plane motion and forefoot loading mechanics. Also, overcorrecting the abduction deformity was predictive of increased lateral plantar pressures.
  
  
  CONCLUSIONS
  Although overcorrection of the abduction deformity at the midfoot remains the primary determinant of lateral forefoot overload, utilizing a graft with a larger taper may lower the incidence of lateralized forefoot pressure following correction.
authors.affiliation: Department of Biomechanics, Hospital for Special Surgery, New York, NY, USA baxterj@hss.edu.
authors.forename: Josh R
authors.initials: JR
authors.lastname: Baxter
authors.affiliation: Department of Foot and Ankle Surgery, Hospital for Special Surgery, New York, NY, USA.
authors.forename: Constantine A
authors.initials: CA
authors.lastname: Demetracopoulos
authors.affiliation: Department of Foot and Ankle Surgery, Hospital for Special Surgery, New York, NY, USA Orthopedic Department, Hospital Israelita Albert Einstein, São Paulo, Brazil.
authors.forename: Marcelo Pires
authors.initials: MP
authors.lastname: Prado
authors.affiliation: Department of Biomechanics, Hospital for Special Surgery, New York, NY, USA.
authors.forename: Susannah L
authors.initials: SL
authors.lastname: Gilbert
authors.affiliation: Department of Foot and Ankle Surgery, Hospital for Special Surgery, New York, NY, USA Department of Orthopaedic Surgery, Mahidol University, Bangkok, Thailand.
authors.forename: Theerawoot
authors.initials: T
authors.lastname: Tharmviboonsri
authors.affiliation: Department of Foot and Ankle Surgery, Hospital for Special Surgery, New York, NY, USA.
authors.forename: Jonathan T
authors.initials: JT
authors.lastname: Deland
mesh_terms: D000328:Adult; D000368:Aged; D002102:Cadaver; D005260:Female; D005413:Flatfoot / Q000601:surgery*; D005531:Foot Deformities, Acquired / Q000601:surgery*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010027:Osteotomy / Q000379:methods*
keywords: biomechanics; flatfoot deformity; lateral column lengthening; plantar pressures