title: Biomechanical comparison of locking versus nonlocking volar and dorsal T-plates for fixation of dorsally comminuted distal radius fractures.
abstract: OBJECTIVE
  The purpose of this study was to gain insight into the effect of plate location and screw type for fixation of extra-articular distal radius fractures with dorsal comminution (Orthopaedic Trauma Association Type 23-A3.2).
  
  
  METHODS
  Sixteen pairs of cadaver radii were randomized to four plating configurations: dorsal locking, dorsal nonlocking, volar locking, and volar nonlocking. A standard 1-cm dorsal wedge osteotomy was used. Cyclic axial loads were applied for 5000 cycles. Stiffness and fragment displacement were recorded at 500 cycle-intervals. Pre- and postcyclic loading radiographs were analyzed. An axial load to failure test followed and construct stiffness and failure strength recorded. Biomechanical data were analyzed using a two-way analysis of variance (P < 0.05). Failure modes were descriptively interpreted.
  
  
  RESULTS
  Cyclic testing data revealed no difference between constructs at any interval. Within all construct groups, displacement that occurred did so within the first 500 cycles of testing. Pre- and postcyclic loading radiographic analysis showed no differences in construct deformation. Load to failure testing revealed no differences between groups, whereas volar constructs approached significance (P = 0.08) for increased failure strength. Dorsal constructs failed primarily by fragment subsidence and fragmentation, whereas volar constructs failed by plate bending.
  
  
  CONCLUSIONS
  No difference in all measured biomechanical parameters supports equivalence between constructs and surgeon discretion in determining operative method. Minimal fragment displacement and construct deformation during physiological testing support previous data that early postoperative motion can be recommended. Fragment displacement that occurs does so in the early periods of motion.
authors.affiliation: Department of Orthopaedic Surgery, Balboa Naval Medical Center-San Diego, 34800 Bob Wilson Drive, San Diego, CA 92134-5000, USA. joseph.gondusky@med.navy.mil
authors.forename: Joseph S
authors.initials: JS
authors.lastname: Gondusky
authors.forename: Joseph
authors.initials: J
authors.lastname: Carney
authors.forename: Jonathan
authors.initials: J
authors.lastname: Erpenbach
authors.forename: Claire
authors.initials: C
authors.lastname: Robertson
authors.forename: Andrew
authors.initials: A
authors.lastname: Mahar
authors.forename: Richard
authors.initials: R
authors.lastname: Oka
authors.forename: Michael
authors.initials: M
authors.lastname: Thompson
authors.forename: Michael
authors.initials: M
authors.lastname: Mazurek
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001860:Bone Plates; D001863:Bone Screws; D002102:Cadaver; D019245:Compressive Strength; D003198:Computer Simulation; D055119:Elastic Modulus; D019544:Equipment Failure Analysis; D005260:Female; D005593:Fracture Fixation, Internal / Q000295:instrumentation*; D018460:Fractures, Comminuted / Q000503:physiopathology* / Q000601:surgery*; D006801:Humans; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D011474:Prosthesis Design; D011885:Radius Fractures / Q000503:physiopathology* / Q000601:surgery*; D013718:Tensile Strength; D014954:Wrist Injuries / Q000503:physiopathology / Q000601:surgery