Volar versus dorsal locking plates with and without radial styloid locking plates for the fixation of dorsally comminuted distal radius fractures: A biomechanical study in cadavers.
OBJECTIVE
To compare the stability and stiffness of dorsal and volar fixed-angle distal radius constructs in a cadaveric model.


METHODS
A locking distal radius system was used in a combination of a dorsal and styloid plate (group 1), a single volar plate (group 2), and a combination of a volar and styloid plate (group 3) configuration. In addition a single volar 3.5-mm steel locking plate was used in group 4. Each construct was tested on 6 fresh-frozen radii with simulated unstable dorsally comminuted extra-articular distal radius fractures. Specimens were tested on a material testing machine with an extensometer and subjected to axial compression fatigue and load-to-failure testing.


RESULTS
No construct failed in fatigue testing of 250 N for 5,000 cycles. Two specimens in each group were tested for 20,000 cycles without failure. The plastic deformation in the double-plate groups was lower compared with the single-plate groups, although the difference was not statistically significant. Group 1 had the highest and group 4 the lowest failure load and stiffness, respectively. The differences between group 1 and the other groups, except failure load compared with group 3, were statistically significant. Groups 2 and 3 had a significantly higher load to failure and group 3 had a significantly higher stiffness compared with group 4.


CONCLUSIONS
All constructs offer adequate stability with minimal deformation on fatigue testing under physiologic conditions. Dorsal fixed-angle constructs are stiffer and stronger than volar constructs. The addition of a styloid plate to a volar plate did not significantly improve stability in this model of simulated extra-articular dorsal comminution loaded in axial compression.
Blythe
Murray
M
Fremantle Orthopaedic Unit, University of Western Australia, Fremantle, Western Australia, Australia.
Stoffel
Karl
K
Jarrett
Paul
P
Kuster
Markus
M
D000368:Aged; D000369:Aged, 80 and over; D001860:Bone Plates; D002102:Cadaver; D005260:Female; D005593:Fracture Fixation, Internal / Q000295:instrumentation*; D018460:Fractures, Comminuted / Q000601:surgery*; D006801:Humans; D008297:Male; D008422:Materials Testing; D008875:Middle Aged; D011474:Prosthesis Design; D011885:Radius Fractures / Q000601:surgery*; D016474:Weight-Bearing