Mechanical properties of 18 different AO bone plates and the clamp-rod internal fixation system tested on a gap model construct.
OBJECTIVE
To compare the stiffness and strength of AO bone plates (DCP, LC-DCP, VCP, RCP, and LP) and the Clamp-Rod Internal Fixation System (CRIF).


METHODS
In vitro.


METHODS
12 individual implants of 18 plate dimensions and four sizes of CRIF, each corresponding to 2.0, 2.4/2.7, 3.5, or 4.5 mm screw sizes.


METHODS
Implant-constructs of each plate and CRIF were created using Canevasit rods as a bone substitute in an unstable gap fracture model. Six implant-constructs of each type were tested under single cycle four-point bending loading, and six were tested under single cycle torsional loading until permanent plastic deformation occurred.


RESULTS
Torsional stiffness and yield load of the DCP were always significantly greater than the CRIF within the same group. Bending properties of the 2.0 DCP were not significantly different to the 2.0 CRIF. The 2.7 DCP had significantly higher bending values than the 2.7 CRIF. The bending stiffness of the 3.5 DCP and 4.5 DCP was significantly less than their CRIF counterparts. While the bending yield load of the 3.5 DCP was significantly greater than the 3.5 CRIF, the bending yield load of the 4.5 DCP was significantly less than the 4.5 CRIF.


CONCLUSIONS
A weakness was found in the torsional resistance of the CRIF constructs compared to the DCP constructs.


CONCLUSIONS
Bone holding power and applied screw torque should be considered when using the CRIF system in clinical application.
Clinic of Veterinary Surgery, Ludwig-Maximilians-University Munich, Germany. Klaus.Zahn@chir.vetmed.uni-muenchen.de
K
K
Zahn
R
R
Frei
D
D
Wunderle
B
B
Linke
K
K
Schwieger
B
B
Guerguiev
O
O
Pohler
U
U
Matis
D000818:Animals; D001696:Biomechanical Phenomena; D001860:Bone Plates / Q000592:standards / Q000662:veterinary*; D001863:Bone Screws / Q000592:standards / Q000662:veterinary*; D018786:Bone Substitutes; D019245:Compressive Strength; D004285:Dogs; D005593:Fracture Fixation, Internal / Q000379:methods / Q000662:veterinary*; D050723:Fractures, Bone / Q000601:surgery / Q000662:veterinary*; D016268:Internal Fixators / Q000592:standards / Q000662:veterinary*; D013314:Stress, Mechanical; D013718:Tensile Strength; D014102:Torsion Abnormality
D018786:Bone Substitutes