title: Stability of the distal phalanx fracture - A biomechanical study on the importance of the nail and the influence of fixation by crossing Kirschner wires.
abstract: With respect to the stability of displaced distal-phalanx fracture, the relevance of nail loss and the biomechanical effects of fixation using crossed Kirschner wires have not been investigated. The present study aimed to determine whether the nail or the type of fixation contributes to stabilizing distal-phalanx fracture.
  
  
  
  In 48 specimens (fingers), a model of the comminuted fracture of the distal phalanx (AO type A3) was created by resecting a 1-mm osseous segment from the distal phalanx. Specimens were assigned to one of four groups, depending on whether the fracture was accompanied with nail loss, and whether the fracture fixation employed a single Kirschner wire or a crossing of two Kirschner wires. Each specimen was subjected to either a bending or a torsion test.
  
  
  
  Regardless of the fixation form, the mean peak bending and torsion forces were higher for the specimens with the nail intact. Furthermore, these forces were also higher in specimens which had received fixations based on the Kirschner wires, compared to those specimens which had received fixations based on a single Kirschner wire. The highest mean peak torque 1.39 (0.12) N·m was found for the specimens with no nail loss and fixation using two crossed Kirschner wires, while the lowest mean peak torsion 0.46 (0.02) N·m was found for specimens with nail loss and fixation using a single Kirschner wire.
  
  
  
  Our results suggest that the nail can provide additional stability for comminuted fractures of the distal phalanx after fixation. Furthermore, when nail loss occurs, fixation using two crossed Kirschner wires can provide significantly more stability than fixation using single Kirschner wire.
authors.affiliation: Department of Orthopedics, Shanghai Sixth People's Hospital (East Campus), 222 West No. 3 Huanhu Road, Shanghai 201306, PR China. Electronic address: wahaa1987@163.com.
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.affiliation: Orthopedics Institute, Medical College of Soochow University, 708 Renmin Road, Suzhou, Jiangsu 215006, PR China. Electronic address: 13988992@qq.com.
authors.forename: Jia
authors.initials: J
authors.lastname: Yu
authors.affiliation: Department of Orthopedics, Shanghai Jiaotong University Affiliated of Sixth People's Hospital, 600 Yishan Road, Shanghai 200233, PR China. Electronic address: fancunyi888@163.com.
authors.forename: Cun-Yi
authors.initials: CY
authors.lastname: Fan
authors.affiliation: Department of Orthopedics, Shanghai Jiaotong University Affiliated of Sixth People's Hospital, 600 Yishan Road, Shanghai 200233, PR China. Electronic address: liushensjtu@126.com.
authors.forename: Shen
authors.initials: S
authors.lastname: Liu
authors.affiliation: Department of Orthopedics, Shanghai Jiaotong University Affiliated of Sixth People's Hospital, 600 Yishan Road, Shanghai 200233, PR China.
authors.forename: Xianyou
authors.initials: X
authors.lastname: Zheng
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001696:Biomechanical Phenomena; D001858:Bone Nails; D001864:Bone Wires; D002102:Cadaver; D005260:Female; D005383:Finger Injuries / Q000601:surgery*; D050278:Finger Phalanges / Q000293:injuries / Q000601:surgery; D005593:Fracture Fixation, Internal / Q000379:methods*; D018460:Fractures, Comminuted / Q000601:surgery*; D006801:Humans; D008297:Male; D008875:Middle Aged
keywords: Biomechanical study; Distal phalanx fracture; Kirschner wire fixation; Nail; Stability