Presented: Yes
Presented at: SUNY Upstate Medical University, Department of Orthopedic Surgery 34th Annual Alumni Day, Syracuse, NY, June 2014

Authors: Anton M Kurtz, MD; Fredrick W Werner, MME, PE; R Bruce Simpson, MD
Author Affiliations: SUNY Upstate Medical University

Introduction: This study compared the failure properties of a broad 3.5 mm plate with standard small fragment and large fragment plates used to secure length unstable humerii.

Methods / Materials: Three constructs were tested, a nine-hole narrow 4.5-mm locking compression plate (LCP), a 12-hole 3.5-mm LCP, and a 12-hole curved broad LCP, each secured with non-locking screws to composite humerii with 1-cm defects simulating comminution (n=6 in each group). All constructs were then tested in axial loading to failure.

Results: Average peak force was significantly different between the 3.5 mm LCP construct (1340 N) and 3.5 mm curved broad LCP construct (2215 N) (P=0.001), and between the 3.5 mm LCP and 4.5 mm LCP constructs (1890 N) (P=0.007). No significant difference in peak force was found between the 3.5 mm curved broad LCP and 4.5 mm LCP constructs (P=0.11). No significant difference in linear stiffness was found between any of the plating constructs (P>0.65). The yield point was significantly different between the 3.5 mm LCP construct (830 N) and the 3.5 mm curved broad LCP construct (1535 N) (P=0.001), and between the 3.5 LCP and 4.5 LCP constructs (1355 N) (P=0.001). No significant difference was found between the 3.5 mm curved broad and 4.5 mm LCP constructs (P=0.09).

Discussion / Conclusion: The results corroborate those of similar recent studies comparing small and large fragment constructs. The broad 3.5 mm implant appears to offer a similar mechanical profile to the large fragment implant under axial loads.