title: Unicortical PEEK inset locking fixation for metacarpal fractures: a biomechanical study.
abstract: OBJECTIVE
  There are numerous constructs employed in the treatment of metacarpal fractures with varying degrees of success. While plate fixation commonly involves dorsal application of a bicortical non-locking plate, there has been recent exploration of other fixation options including unicortical locked plating. The purpose of this study was to evaluate the biomechanical integrity of a polyetheretherketone (PEEK) inset locking plate and, in doing so, compare it to standard plate fixation (utilizing a clinically proven bicortical non-locking titanium plate) in a simulated porcine metacarpal fracture model.
  
  
  METHODS
  Reproducible mid-shaft fractures were created in porcine second metacarpals. The fractured specimens were reduced and plated with either a bicortical non-locking plate or a unicortical locking plate with a PEEK locking design. Constructs were then loaded to failure in the same fashion as performed to create the fracture. Peak load was measured as the apex on the load-to-failure deflection curve. Stiffness was calculated as the linear slope on the load-to-failure deflection curve. Data were analyzed via Student's t test.
  
  
  RESULTS
  Unicortical locking constructs failed at 344 ± 119 N, while bicortical non-locking constructs were found to fail at 277 ± 101 N (p = 0.19). The unicortical locking constructs demonstrated a stiffness of 80 ± 36 N/mm compared with the bicortical non-locking constructs (69 ± 36 N/mm) although again the difference was not found to be statistically different (p = 0.49).
  
  
  CONCLUSIONS
  Based on this study, a locked plating construct using a polymer mechanism provides an interesting new locking fixation method for small bone fractures and with our limited number of specimens tested, provided at least a similar strength and rigidity profile in comparison with bicortical fixation in the treatment of metacarpal fractures.
authors.affiliation: Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, Virginia Commonwealth University, P.O. Box 980153, Richmond, VA 23298-0153, USA. cmudrick@mcvh-vcu.edu
authors.forename: Colin A
authors.initials: CA
authors.lastname: Mudrick
authors.forename: John R
authors.initials: JR
authors.lastname: Owen
authors.forename: Jennifer S
authors.initials: JS
authors.lastname: Wayne
authors.forename: Jonathan E
authors.initials: JE
authors.lastname: Isaacs
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D001860:Bone Plates; D005593:Fracture Fixation, Internal / Q000295:instrumentation / Q000379:methods*; D050723:Fractures, Bone / Q000503:physiopathology / Q000601:surgery*; D006801:Humans; D050279:Metacarpal Bones / Q000293:injuries* / Q000503:physiopathology / Q000601:surgery; D013552:Swine