In vitro cyclic biomechanical properties of an interlocking equine tibial nail.
OBJECTIVE
To determine cyclic biomechanical properties of gap osteotomized adult equine tibiae stabilized with an equine interlocking nail (EIN).


METHODS
In vitro experimental biomechanical investigation.


METHODS
Thirteen adult equine cadaveric tibiae.


METHODS
Adult equine tibiae with transverse, midshaft, 1-cm gap osteotomies, stabilized with an equine interlocking nail, underwent cyclic biomechanical testing in vitro under axial compression, 4-point bending, and torsion. Different specimens were subjected to different load levels that represented estimated in vivo loads at 2 Hz for 740,000 cycles. Fatigue life and gap strain were calculated.


RESULTS
Compression and bending, but not torsional, fatigue life were longer than time necessary for bone healing. Compressive, but not bending or torsional, gap strains were small enough to be compatible with fracture healing by primary bone formation. Gap strains for compressive, bending, and torsional loads were compatible with indirect, or secondary, bone formation.


CONCLUSIONS
Further modification should be made to the equine interlocking nail to increase bending stiffness and torsional fatigue life.


CONCLUSIONS
The stainless steel equine intramedullary interlocking nail is unlikely to provide appropriate long-term stability for fracture healing in adult equine tibiae without modifications in the nail design and material.
McDuffee
L A
LA
Department of Veterinary Anatomy, Physiology and Cell Biology, School of Veterinary Medicine, University of California, Davis, USA.
Stover
S M
SM
Taylor
K T
KT
D000818:Animals; D001696:Biomechanical Phenomena; D001858:Bone Nails / Q000662:veterinary*; D006736:Horses / Q000293:injuries* / Q000601:surgery*; D013978:Tibial Fractures / Q000601:surgery / Q000662:veterinary*