title: A new method for achieving compression in hindfoot arthrodesis.
abstract: BACKGROUND
  When performing hindfoot arthodeses, one goal of fixation is often to achieve compression across the joint. Traditional lag screws are applied eccentrically, providing compression more on the edge of the fusion. A new technique, using a post in one bone and a lag screw through the post to the other bone, may offer better compression across more of the joint.
  
  
  METHODS
  There are three parts to this study comparing a post-and-screw construct to traditional lag screws. Synthetic bone models, representative of the talonavicular joint, were created and assessed for biomechanical measures of compression. Next, the post-and-screw construct was tested in cadavers, under conditions representing early weight bearing after arthrodesis surgery. Finally, 18 patients who had a talonavicular fusion with a post-and-screw construct with one surgeon were compared to the previous 18 patients fixed with traditional screws.
  
  
  RESULTS
  In the synthetic bone model, the post-and-screw construct brought the centre of compression closer to the centre of the joint, suggesting compression was less eccentric. Neither traditional screws nor the post-and-screw construct were sufficiently strong to resist early weight bearing forces in cadaver specimens. In the clinical comparison, four patients had a painful nonunion when fixed with traditional screws, compared to none in the post-and-screw construct.
  
  
  CONCLUSIONS
  A post-and-screw construct spreads the forces of compression more uniformly across an arthrodesis, even when placed eccentrically. Although not all the biomechanical measures were superior, the post-and-screw construct achieved higher levels of successful fusion in patients. This technology may offer improved outcomes in some clinical scenarios and deserves further study.
  
  
  METHODS
  Level 3.
authors.affiliation: Department of Orthopaedic Surgery, Columbia University Medical Center, 622 West 168th St, PH 11th floor, New York, NY, 10032, USA. jkg2101@columbia.edu.
authors.forename: Justin
authors.initials: J
authors.lastname: Greisberg
authors.affiliation: Department of Orthopaedic Surgery, Columbia University Medical Center, 622 West 168th St, PH 11th floor, New York, NY, 10032, USA.
authors.forename: J Turner
authors.initials: JT
authors.lastname: Vosseller
authors.affiliation: Department of Orthopaedic Surgery, Columbia University Medical Center, 622 West 168th St, PH 11th floor, New York, NY, 10032, USA.
authors.forename: Chris
authors.initials: C
authors.lastname: Ferry
authors.affiliation: Department of Orthopaedic Surgery, Columbia University Medical Center, 622 West 168th St, PH 11th floor, New York, NY, 10032, USA.
authors.forename: Calvin
authors.initials: C
authors.lastname: Nash
authors.affiliation: Department of Orthopaedic Surgery, Columbia University Medical Center, 622 West 168th St, PH 11th floor, New York, NY, 10032, USA.
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Gardner
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001174:Arthrodesis / Q000379:methods*; D001858:Bone Nails; D001863:Bone Screws; D002102:Cadaver; D005260:Female; D005528:Foot / Q000601:surgery*; D005534:Foot Diseases / Q000601:surgery*; D006801:Humans; D008297:Male; D008875:Middle Aged; D008953:Models, Anatomic; D011312:Pressure; D013639:Tarsal Bones / Q000601:surgery; D013640:Tarsal Joints / Q000601:surgery*; D016474:Weight-Bearing
keywords: Arthrodesis; Compression; Fusion; Talonavicular