Mechanical comparison of 3.5 mm broad dynamic compression plate, broad limited-contact dynamic compression plate, and narrow locking compression plate systems using interfragmentary gap models.
OBJECTIVE
To compare (1) pullout properties between 3.5 mm cortical and locking screws, and (2) mechanical properties and gap displacements between the 3.5 mm broad limited-contact dynamic compression plate (LC-DCP), broad dynamic compression plate (DCP), and narrow locking compression plate (LCP), during axial loading of plate-stabilized diaphyseal fragments with an interfragmentary gap.


METHODS
In vitro mechanical testing of implanted polyurethane foam (PUF) hollow cylinders that simulated compact or osteopenic diaphyseal bone.


METHODS
(1) Five cortical and locking screws and (2) 4 PUF-plate constructs for each plate type; using high- and low-density (0.8 and 0.32 g/cm(3)) cylinders.


METHODS
(1) Screws were completely extracted at 5 mm/min. (2) Plated constructs were axially compressed at 300 N/s for 10 cycles from 5 to 355 N to determine gap displacement during physiologic loading, followed by single cycle increasing load to failure.


RESULTS
Pullout properties were not different between screw types. All plate constructs had yield loads over 3 times trotting loads. Gap closure occurred with LC-DCP and DCP constructs, but not LCP constructs. LCP construct properties were most similar to LC-DCP and DCP construct properties in the low-density model.


CONCLUSIONS
All plate systems sustained physiologic limb loads. Only LCP constructs maintained some gap integrity, although LC-DCP and DCP screws were placed in neutral position.


CONCLUSIONS
The LCP system is more likely than LC-DCP and DCP systems, with neutrally positioned screws, to maintain a planned interfragmentary gap, although gap strains range from 0% to 15% across the 2 mm gap during a trot load.
Uhl
Justin M
JM
JD Wheat Veterinary Orthopedic Research Laboratory, School of Veterinary Medicine, University of California-Davis, Davis, CA, USA.
Seguin
Bernard
B
Kapatkin
Amy S
AS
Schulz
Kurt S
KS
Garcia
Tanya C
TC
Stover
Susan M
SM
D000818:Animals; D001696:Biomechanical Phenomena; D001860:Bone Plates / Q000662:veterinary*; D001863:Bone Screws / Q000662:veterinary*; D005593:Fracture Fixation, Internal / Q000379:methods / Q000662:veterinary*; D050723:Fractures, Bone / Q000601:surgery / Q000662:veterinary*; D008422:Materials Testing / Q000379:methods / Q000662:veterinary*; D013718:Tensile Strength