Anteroinferior 2.7-mm versus 3.5-mm plating of the clavicle: A biomechanical study

Lower patient satisfaction and high rates of plate prominence has led to the use of lower profile, smaller plates in the treatment of midshaft clavicle fractures. Specifically regarding the use of 2.7mm reconstruction plates, there lacks biomechanical comparison to its more robust 3.5mm counterpart. This study was designed to compare the mechanical properties of anteroinferior plate fixation on a clavicle fracture model using either 2.7mm or 3.5mm reconstruction plates.

Forty-eight synthetic left clavicles were divided into two groups based on the type of fixation: 3.5mm or 2.7mm pelvic reconstruction plate fixed in the anteroinferior position. Fixation was tested on AO/OTA 15B1.3 transverse midshaft fractures. Each specimen underwent the following three mechanical tests: axial compression, torsion, and four-point bending.

Significant differences were observed in axial (p=0.016) and torsional (p=0.00097) stiffness between the two groups. The average bending rigidity (EI) was found to be significantly lower for the 2.7-mm plates as compared to the 3.5-mm plates (p=0.03). The loading scenarios performed in the mechanical tests did not lead to failure of any implants.

While our results show clear mechanical superiority of 3.5-mm reconstruction plates over 2.7-mm plates, superior results in the clinical setting may not necessarily translate. With exceptional mechanical strength also noted for the 2.7mm plate, well above the biomechanical properties of an intact clavicle, these results may obviate the need for robust plates in general.