title: Evaluation of first metatarsal head declination through a modified distal osteotomy in hallux rigidus surgery. A cadaveric model.
abstract: BACKGROUND
  First metatarsal osteotomies have been described for treatment of hallux rigidus. Most of these techniques result in declination of the first metatarsal head through shortening of the metatarsal and transfer metatarsalgia may result. Our objective was to evaluate the declination effect of a distal metatarsal osteotomy when different angulations and lateral translations are applied.
  
  
  METHODS
  A cadaveric study was conducted performing a modified distal oblique osteotomy, which produces head declination while limiting shortening. Several transverse inclination angles (0-10-20-30-40°) were used. Thereafter, plantar translation of the metatarsal head was registered at different lateral displacements (1, 3, 5mm).
  
  
  RESULTS
  Twenty-two specimens were included. Three feet were operated on with a 0° of angulation in the transverse plane, 6 with 10°, 5 with 20°, 5 with 30°, and 3 with 40°. Head declination significantly increased with higher angulation and with greater lateral translations (p<0.001), but the interrelationship between these two variables did not achieve statistical significance (p=0.597). In regards to angulation, significant differences in head declination were found between 0° (0.1-0.7 mm), 10°-20° (0.5-1.2mm) and 30°-40° (1.3-2.4mm). The metatarsal sesamoid joint was compromised when the osteotomy was performed at a 40° inclination angle.
  
  
  CONCLUSIONS
  Metatarsal head declination is determined by the inclination angle of the oblique limb of the osteotomy and lateral displacement of the metatarsal head. Our results suggest that the effect of lateral displacement is an independent factor from angulation. The latter may impact surgery planning and may improve clinical outcome by selecting a safer inclination angle when lateral displacement of the metatarsal head is being considered.
  
  
  METHODS
  Level II-A, systematic review with homogeneity of cohort studies.
authors.affiliation: Unidad de Pie y Tobillo, Departamento de Cirugía Ortopédica y Traumatología, Hospital Clinic, Universitat de Barcelona, Barcelona, España. Electronic address: asuncion@clinic.ub.es.
authors.forename: Jordi
authors.initials: J
authors.lastname: Asunción
authors.affiliation: Unidad de Pie y Tobillo, Departamento de Cirugía Ortopédica y Traumatología, Hospital Clinic, Universitat de Barcelona, Barcelona, España.
authors.forename: Daniel
authors.initials: D
authors.lastname: Poggio
authors.affiliation: Fellowship de Cirugía de Pie y Tobillo, Universitat de Barcelona, Barcelona, España.
authors.forename: Manuel J
authors.initials: MJ
authors.lastname: Pellegrini
authors.affiliation: Fellowship de Cirugía de Pie y Tobillo, Universitat de Barcelona, Barcelona, España.
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Melo
authors.affiliation: Laboratory of Biostatistics & Epidemiology (Universitat Autònoma de Barcelona), Biostatistics and Data Management Platform, IDIBAPS (Hospital Clinic), Barcelona, Spain.
authors.forename: José
authors.initials: J
authors.lastname: Ríos
mesh_terms: D002102:Cadaver; D020859:Hallux Rigidus / Q000601:surgery*; D006801:Humans; D008682:Metatarsal Bones / Q000601:surgery*; D008683:Metatarsophalangeal Joint / Q000601:surgery*; D010027:Osteotomy / Q000379:methods*
keywords: Cadaver; Hallux limitus; Hallux rigidus; Inclination angle; Osteotomy; Surgery