A Biomechanical Comparison of Unilateral and Bilateral String-Of-Pearls Locking Plates in a Canine Distal Humeral Metaphyseal Gap Model
Hurt, Richard J.
McLaughlin, Ron M.
CommitteeElder, Steven H.
Humeral fractures in veterinary patients are challenging to stabilize. This study is a biomechanical in vitro comparison of the performance of two locking plate constructs used to stabilize a canine distal humeral metaphyseal gap model. Two groups of canine cadaveric humeri were prepared. One group consisted of a unilateral medially placed locking plate (UNI). The second group consisted of bilateral locking plates (BI). Constructs were tested in torsion and axial compression. The UNI constructs had significantly lower stiffness in torsion and axial compression than the BI group. However, UNI constructs had a significantly higher ultimate strength than BI constructs. All UNI constructs failed by bending of the transcondylar screw and SOP plate. All BI constructs failed by axial pullout of the distal most screws. The clinical significance is that in stabilizing canine supracondylar humeral fractures as modeled here, both the UNI model and the BI model demonstrated biomechanical advantages.