title: In vitro comparison of wire and plate fixation for midline sternotomies.
abstract: BACKGROUND
  The incidence of severe sternal wound complications in high-risk cardiac patients presents a significant need for more stabile sternal fixation techniques after median sternotomy procedures. Rigid metal plates, a potential alternative to wire fixation, are thought to promote faster sternal healing by reducing motion at the wound site. The goal of this study was to compare the stability provided by commercially available sternal plates with standard wires using an in vitro model.
  
  
  METHODS
  Lateral distraction tests were conducted on bisected polyurethane sternal models fixed with either a standard 7 wire configuration (n = 5) or a 3 plate configuration (n = 3). To assure controlled loading, the sternal models were attached to a computer-controlled test machine by a novel tethering system that distributes the total force (180N) equally to eight locations on the sternum. Stability was defined as the ability to restrict sternal separation at seven locations along the midline quantified using digital image analysis.
  
  
  RESULTS
  Our results indicate that rigid plate fixation significantly reduced lateral motion relative to wire fixation. The lower sternal region most noticeably benefited from plate fixation as the splaying observed for wire fixation was reduced.
  
  
  CONCLUSIONS
  Under these loading conditions, plating increased stability at the midline compared to wires; this increased stability may facilitate the recovery of high-risk patients undergoing cardiac operation. To enhance in vitro testing methods, future studies should incorporate additional in vivo loading conditions applied to the sternum. Alternate plating configurations should also be examined to further increase stability.
authors.affiliation: Department of Biomedical Engineering, Worcester Polytechnic Institute, University of Massachusetts Medical Center, Worcester, Massachusetts, USA.
authors.forename: Shruti
authors.initials: S
authors.lastname: Pai
authors.forename: Najmuddin J
authors.initials: NJ
authors.lastname: Gunja
authors.forename: Erin L
authors.initials: EL
authors.lastname: Dupak
authors.forename: Nicole L
authors.initials: NL
authors.lastname: McMahon
authors.forename: Timothy P
authors.initials: TP
authors.lastname: Roth
authors.forename: Janice F
authors.initials: JF
authors.lastname: Lalikos
authors.forename: Raymond M
authors.initials: RM
authors.lastname: Dunn
authors.forename: Nicola
authors.initials: N
authors.lastname: Francalancia
authors.forename: George D
authors.initials: GD
authors.lastname: Pins
authors.forename: Kristen L
authors.initials: KL
authors.lastname: Billiar
mesh_terms: D001696:Biomechanical Phenomena; D001860:Bone Plates; D001864:Bone Wires; D006348:Cardiac Surgical Procedures / Q000295:instrumentation* / Q000379:methods*; D004867:Equipment Design; D008954:Models, Biological; D013249:Sternum / Q000503:physiopathology / Q000601:surgery*; D013536:Suture Techniques; D016896:Treatment Outcome