Summary

The locking compression plate (LCP) supports biologicalosteosynthesis by functioning as an internal fixator,rather than as a full or limited contact bone plate whichmust be adequately contoured and affixed directly tothe bone for stable internal fixation of the fracture. Inorder to help justify the use of the LCP in our veterinarypatients, in vitro biomechanical testing was performedcomparing the LCP to the conventional limited contactdynamic compression plate (LC-DCP) in canine femurs.We hypothesized that the LCP construct would be atleast as stiff under bending and torsional loads as theLC-DCP. The LCP and LC-DCP were applied over a20-mm osteotomy gap to contralateral bones withineach pair of 14 femora. Non-destructive four-pointbending and torsion, and cyclical testing in torsion wereperformed. The constructs were then loaded to failure intorsion. In medial-lateral and lateral-medial structuralbending, significant differences were not found betweenthe LCP and LC-DCP, however, at the gap, the LCP constructwas stiffer than the LC-DCP in lateral-medialbending. Significant differences in behaviour over timewere not noted between the plate designs during cyclicaltesting. When loading the constructs to failure in internalrotation, the LC-DCP failed at a significantlylower twist angle (P = .0024) than the LCP. Based onthe similar performance with loading, the locking compressionplate is a good alternative implant for unstablediaphyseal femoral fracture repair in dogs.