Mechanical Evaluation of 2.7-Versus 3.5-mm Plating Constructs for Midshaft Clavicle Fractures

Objectives: This study compares the mechanical performance of 2.7- and 3.5-mm plating constructs for the treatment of midshaft clavicle fractures. Methods: Twenty-four synthetic clavicles were randomly divided into four treatment groups-Synthes 2.7-mm cold-worked calcaneal reconstruction plate with 6 (CRP6) or 8 bicortical screws (CRP8); Synthes 3.5-mm LCP reconstruction plate (RP; and Synthes 3.5-mm LCP precontoured superior-anterior clavicle plate (PCRP). All clavicles were plated, a wedge-shaped inferior cortical defect was created, and testing was performed using a cantilever bending model to determine bending stiffness and yield point for each construct. Results: Bending stiffness for the 3.5-mm PCRP construct was markedly higher when compared with the other three constructs, whereas the 3.5-mm RP construct was markedly stiffer than both of the 2.7-mm CR constructs. The yield point for the 3.5-mm PCRP construct was greater than the other three constructs; however, the yield point for the 2.7-mm CRP with six screws and with eight screws was higher than the 3.5-mm RP construct. The amount of displacement required to reach the yield point was highest for the 2.7-mm CRP with six screws. and this was markedly higher than the values for the other three constructs. Discussion: The 3.5-mm plates demonstrated increased bending stiffness compared with the 2.7-mm plates. Despite the lower resistance to bending forces, the cold-worked 2.7-mm plate exhibited a markedly higher yield point and required markedly more superior to inferior displacement to initiate plastic deformation when compared with the 3.5-mm LCP RP.

Automated summary

This study compared the mechanical performance of 2.7- and 3.5-mm plating constructs for midshaft clavicle fractures, with the 3.5-mm plates showing increased bending stiffness. Despite lower resistance, the cold-worked 2.7-mm plate exhibited a higher yield point and required more displacement to initiate deformation.