Volar fixed-angle plating of distal radius fractures: screws versus pegs--a biomechanical study in a cadaveric model.
OBJECTIVE
The purpose of this biomechanical study was to determine whether a multidirectional fixed-angle plate with locking screws or with locking pegs in the distal fragment would optimize fixation of Orthopaedic Trauma Association (OTA) type A3 distal radius fractures.


METHODS
Eight pairs of fresh-frozen human distal radii were used. Extra-articular distal radius fractures were created and stabilized with a multidirectional volar fixed-angle plate. The radii were randomized into 2 matched-paired groups. The distal fragment in Group I was stabilized with 7 locking screws. The distal fragment in Group II was fixed with 7 locking pegs. The proximal fragment in both groups was fixed with 3 screws. The specimens were tested under torsion and axial compression during static and cyclic tests. Finally, load-to-failure tests were performed under torsion.


RESULTS
After 1000 cycles, 99% of the median torsional stiffness remained in the group using screws, whereas only 76% of the median stiffness under torsion remained in the group using pegs (P = 0.018). Under axial compression, median stiffness remained at 93% in the group using screws after 1000 cycles compared with a median of 0% in the group using pegs (P = 0.018).


CONCLUSIONS
This biomechanical study showed a statistically significant difference between the locking screw and locking smooth peg configuration with regard to stiffness of the constructs after 1000 cycles. The use of locking screws as opposed to smooth locking pegs for OTA type A3 extra-articular distal radius fractures optimizes construct stability.
Department of Trauma and Orthopaedic Surgery, University Medical Center of the Johannes Gutenberg-University of Mainz, Mainz, Germany. mehling@unfall.klinik.uni-mainz.de
Isabella
I
Mehling
Daniela
D
Klitscher
Andreas P
AP
Mehling
Tobias E
TE
Nowak
Werner
W
Sternstein
Pol M
PM
Rommens
Lars P
LP
Müller
D000368:Aged; D000369:Aged, 80 and over; D001696:Biomechanical Phenomena; D001858:Bone Nails; D001860:Bone Plates; D001863:Bone Screws; D002102:Cadaver; D019544:Equipment Failure Analysis; D005260:Female; D005593:Fracture Fixation, Internal / Q000295:instrumentation / Q000379:methods*; D006801:Humans; D008297:Male; D055595:Mechanical Phenomena; D008875:Middle Aged; D011475:Prosthesis Failure; D011885:Radius Fractures / Q000601:surgery*