Stability of volar locking plate systems for AO type C3 fractures of the distal radius: biomechanical study in a cadaveric model.
BACKGROUND
The purpose of the present study was to compare the relative stability of five volar locking plates (all of which are available for the treatment of intraarticular fractures of the distal radius) under loading conditions simulating the physiological forces that occur during early active mobilization.


METHODS
Five plating techniques were applied to surgically simulated AO type C3.2 distal radius fractures in formalin-fixed cadavers. The specimens were tested with a servohydraulic materials testing machine with 250 N of axial compression load for 3000 cycles. After cyclic loading, the specimens were loaded until they demonstrated failure in axial compression. The five fixation systems studied included a DRV locking plate (group 1), a Stellar plate (group 2), an Acu-Loc plate (group 3), AO Locking Distal Radius System 2.4 (group 4); and a Matrix SmartLock plate (group 5).


RESULTS
None of the plate fixations tested failed during the cyclic loading. Group 2 had a higher elastic limit than groups 4 and 5. There were no significant differences among the five groups for the failure load. Failure occurred at the distal portion of the fixation system, at the ulnar side locking pin, or the locking screw was bent (groups 1, 2, 3); the ulnar side locking screw was broken (groups 3, 4); the locking screw became loose (group 4); and the ulnar side locking screw was uncoupled from the screw hole (group 5).


CONCLUSIONS
All of the five volar plate fixation systems provided sufficient stability to permit 3000 repeated motions of the digits after surgery for AO type C3 distal radius fractures.
Kamei
Shuzo
S
Department of Orthopaedic Surgery, Dokkyo Medical University School of Medicine, Shimotsuga-gun, Tochigi, Japan.
Osada
Denju
D
Tamai
Kazuya
K
Kato
Nakayuki
N
Takai
Morimitsu
M
Kameda
Masahiro
M
Nohara
Yutaka
Y
D000368:Aged; D000369:Aged, 80 and over; D001860:Bone Plates; D002102:Cadaver; D019544:Equipment Failure Analysis; D006801:Humans; D057072:Intra-Articular Fractures / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D011885:Radius Fractures / Q000601:surgery*; D016474:Weight-Bearing; D014955:Wrist Joint / Q000601:surgery*