Preclinical Cyclic Testing of Adjunctive Fixation of the Humeral Epicondyle in a Lateral Condylar Fracture Model: Ex Vivo Comparison of a Locking Plate versus a Light-curable Composite.

OBJECTIVE: To compare the mechanical performance under cyclic loading of a biocompatible light-curable composite formed from two traizine-trione resin monomers and hydroxyapatite construct (AdhFix) against a standard locking plate used as adjunctive epicondylar stabilization in a simulated lateral condylar humeral fracture model. STUDY DESIGN: Cadaveric biomechanical assessment. MATERIALS AND METHODS: Paired canine cadaver humeri were used to simulate lateral condylar humeral fractures. All constructs were stabilized with a transcondylar 4.5 mm cortical screw placed in lag fashion. Adjunctive fixation was then applied in a within-cadaver comparison: One humerus received a light-curable composite construct incorporating 2.7 mm cortical screws, while the contralateral humerus received a 2.7 mm locking plate. Specimens were subjected to 95,000 cycles of axial compressive loading between 20 and 130 N. Groups were compared for displacement and construct dynamic stiffness (p < 0.05). Terminal monotonic testing was then performed until failure. RESULTS: There was no mechanical failure in either group during cyclic testing. There were no statistically significant differences between groups in construct dynamic stiffness, displacement, or yield point in terminal monotonic testing. CONCLUSION: Cyclic testing support the use of AdhFix as adjunctive fixation in humeral condylar fractures.