title: Biomechanical comparison of dorsal nail plate versus screw and K-wire construct for extra-articular distal radius fractures in a cadaver bone model.
abstract: OBJECTIVE
  The purpose of the study was to compare the biomechanical stability of distal radius fracture fixation with 2 new implants, the DNP (Hand Innovations LLC, Miami, FL), a dorsal locked hybrid of nail and plate, and the XSCREW (Zimmer, Freiburg, Germany), an implant combining a cannulated screw and K-wires, in a cadaver bone distal radius fracture model.
  
  
  METHODS
  Eight pairs of fresh-frozen cadaver radii were used. To simulate an extra-articular distal radius fracture, a 5-mm volar open wedge osteotomy was made. Axial loads of 10 to 100 N and torque loads of -1.5 to 1.5 Nm were applied by a testing machine to the intact radii and to the radii after each device was fixed as recommended by the manufacturer. One thousand cycles in torque and failure tests were performed.
  
  
  RESULTS
  With a median of 136.0 N/mm, the axial stiffness of XSCREW-fixed specimens was higher than that of DNP-fixed specimens, with a median of 69.5 N/mm, but differences were not statistically significant. With a median of 0.163 Nm/ degrees , the torque stiffness of XSCREW-fixed specimens was significantly higher than that of DNP-fixed specimens, with a median of 0.068 Nm/ degrees . The XSCREW-group reached 33% of the axial stiffness and 49% of the torque stiffness of the intact radii, and the DNP-group reached 14% of the axial stiffness and 20% of the torque stiffness of the intact radii.
  
  
  CONCLUSIONS
  In this human cadaver bone biomechanical study, the XSCREW provided more stability than the DNP in torque stiffness but not in axial stiffness.
authors.affiliation: Center for Trauma and Orthopaedic Surgery, University Medical Center, Mainz, Germany. dklitscher@aol.com
authors.forename: Daniela
authors.initials: D
authors.lastname: Klitscher
authors.forename: Isabella
authors.initials: I
authors.lastname: Mehling
authors.forename: Lukas
authors.initials: L
authors.lastname: Nowak
authors.forename: Tobias
authors.initials: T
authors.lastname: Nowak
authors.forename: Pol M
authors.initials: PM
authors.lastname: Rommens
authors.forename: Lars P
authors.initials: LP
authors.lastname: Müller
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001696:Biomechanical Phenomena; D001860:Bone Plates; D001863:Bone Screws; D001864:Bone Wires; D002102:Cadaver; D005260:Female; D005593:Fracture Fixation, Internal / Q000295:instrumentation*; D006801:Humans; D008297:Male; D011474:Prosthesis Design; D011475:Prosthesis Failure; D011859:Radiography; D011885:Radius Fractures / Q000000981:diagnostic imaging / Q000601:surgery*; D018709:Statistics, Nonparametric; D013314:Stress, Mechanical; D019415:Torque