title: Biomechanical assessment of flexible flatfoot correction: comparison of techniques in a cadaver model.
abstract: BACKGROUND
  Options for surgical correction of acquired flexible flatfoot deformity involve bone and soft-tissue reconstruction. We used an advanced cadaver model to evaluate the ability of key surgical procedures to correct the deformity and to resist subsequent loss of correction.
  
  
  METHODS
  Stage-IIB flatfoot deformity was created in ten cadaver feet through ligament sectioning and repetitive loading. Six corrective procedures were evaluated: (1) lateral column lengthening, (2) medial displacement calcaneal osteotomy with flexor digitorum longus transfer, (3) Treatment 2 plus lateral column lengthening, (4) Treatment 3 plus "pants-over-vest" spring ligament repair, (5) Treatment 3 plus spring ligament repair with use of the distal posterior tibialis stump, and (6) Treatment 3 plus spring ligament repair with suture and anchor. Correction of metatarsal dorsiflexion and of navicular eversion were quantified initially and periodically during postoperative cyclic loading.
  
  
  RESULTS
  Metatarsal dorsiflexion induced by arch flattening was initially corrected by 5.5° to 10.6°, depending on the procedure. Navicular eversion was initially reduced by 2.1° to 7.7°. The correction afforded by Treatments 1, 3, 4, 5, and 6 exceeded that of Treatment 2 initially and throughout postoperative loading. Inclusion of spring ligament repair did not significantly enhance correction.
  
  
  CONCLUSIONS
  Under the tested conditions, medial displacement calcaneal osteotomy with flexor digitorum longus tendon transfer was inferior to the other evaluated treatments for stage-IIB deformity. Procedures incorporating lateral column lengthening provided the most sagittal and coronal midfoot deformity correction. Addition of spring ligament repair to a combination of these three procedures did not substantially improve correction.
  
  
  CONCLUSIONS
  An understanding of treatment effectiveness is essential for optimizing operative management of symptomatic flatfoot deformity. This study provides empirical evidence of the advantage of lateral column lengthening and novel information on resistance to postoperative loss of correction.
authors.affiliation: Orthopedic Surgery, Clinica Alemana de Santiago, Vitacura 5951, Santiago, Chile.
authors.forename: Diego H
authors.initials: DH
authors.lastname: Zanolli
authors.affiliation: Department of Orthopaedic Surgery, Duke University Medical Center, P.O. Box 2950, Durham, NC 27710.
authors.forename: Richard R
authors.initials: RR
authors.lastname: Glisson
authors.affiliation: Department of Orthopaedic Surgery, Duke University Medical Center, P.O. Box 2950, Durham, NC 27710.
authors.forename: James A
authors.initials: JA
authors.lastname: Nunley
authors.affiliation: Department of Orthopaedic Surgery, Duke University Medical Center, P.O. Box 2950, Durham, NC 27710.
authors.forename: Mark E
authors.initials: ME
authors.lastname: Easley
mesh_terms: D000328:Adult; D000368:Aged; D001696:Biomechanical Phenomena / Q000502:physiology; D005260:Female; D005413:Flatfoot / Q000503:physiopathology / Q000601:surgery*; D005528:Foot / Q000503:physiopathology / Q000601:surgery*; D006801:Humans; D008023:Ligaments, Articular / Q000503:physiopathology / Q000601:surgery; D008297:Male; D008875:Middle Aged; D019637:Orthopedic Procedures / Q000379:methods*; D010027:Osteotomy / Q000379:methods; D013709:Tendon Transfer / Q000379:methods; D016896:Treatment Outcome