title: Biomechanical Comparison of 2 Methods of Intramedullary K-Wire Fixation of Transverse Metacarpal Shaft Fractures.
abstract: OBJECTIVE
  To determine the relative importance of intramedullary wire (IMW) diameter and IMW number in conferring stability to a metacarpal fracture fixation construct. Our research hypothesis was that the stiffness of IMW fixation for metacarpal shaft fractures using a single 1.6-mm-diameter (0.062-in) wire would be greater than three 0.8-mm-diameter (0.031-in) wires.
  
  
  METHODS
  Our study compared the biomechanical stiffness between one 1.6-mm K-wire and three 0.8-mm K-wires in a composite, fourth-generation, biomechanical metacarpal construct under cantilever testing to treat transverse metacarpal shaft fractures. Six composite bone-wire constructs were tested in each group using constant-rate, nondestructive testing. Stiffness (load/displacement) was measured for each construct.
  
  
  RESULTS
  All constructs demonstrated a linear load-displacement relationship. Wires were all tested in their elastic zone. The mean stiffness of the 1-wire construct was 3.20 N/mm and the mean stiffness of the 3-wire construct was 0.76 N/mm. These differences were statistically significant with a large effect size.
  
  
  CONCLUSIONS
  The stiffness of IMW fixation for metacarpal shaft fractures using a single 1.6-mm-diameter wire was significantly greater than using three 0.8-mm-diameter wires.
  
  
  CONCLUSIONS
  When IMW fixation is clinically indicated for the treatment of metacarpal fractures, the increased stiffness of a single large-diameter construct provides more stability in the plane of finger flexion-extension.
authors.affiliation: Department of Orthopaedic Surgery, University of Missouri-Kansas City, Kansas City, MO.
authors.forename: Stephen V
authors.initials: SV
authors.lastname: Hiatt
authors.affiliation: Department of Civil and Mechanical Engineering, University of Missouri-Kansas City, Kansas City, MO.
authors.forename: Mark T
authors.initials: MT
authors.lastname: Begonia
authors.affiliation: Department of Civil and Mechanical Engineering, University of Missouri-Kansas City, Kansas City, MO.
authors.forename: Ganesh
authors.initials: G
authors.lastname: Thiagarajan
authors.affiliation: Section of Hand Surgery, Division of Orthopaedic Surgery, Children's Mercy Hospitals and Clinics, Kansas City, MO. Electronic address: rlhutchison@cmh.edu.
authors.forename: Richard L
authors.initials: RL
authors.lastname: Hutchison
mesh_terms: D001864:Bone Wires; D002102:Cadaver; D005594:Fracture Fixation, Intramedullary / Q000295:instrumentation*; D050723:Fractures, Bone / Q000601:surgery*; D006801:Humans; D050279:Metacarpal Bones / Q000293:injuries*; D016059:Range of Motion, Articular; D016474:Weight-Bearing
keywords: K-wires; Metacarpal; fracture; internal fixation; intramedullary wires