Superior versus Anteroinferior Plating of the Clavicle Revisited: A Mechanical Study

Abstract

OBJECTIVES: This study was designed to compare bone-implant stiffness of two fixation techniques on a sawbone model of a clavicle fracture. METHODS: Twenty-four preosteotomized synthetic left clavicles (Sawbones Worldwide, Vashon, WA) were divided into four groups based on type of fixation: standard 3.5-mm pelvic reconstruction plate in the superior position; standard 3.5-mm pelvic reconstruction plate in an anteroinferior position; 3.5-mm locking pelvic reconstruction plate in a superior position; and a 3.5-mm locking pelvic reconstruction plate in an anteroinferior position. Three nondestructive cyclic mechanical tests were performed in random order: axial, torsion, and four-point bend. RESULTS: No significant difference was found in axial (P = 0.61) or torsional stiffness (internal rotation, P = 0.46 or external rotation, P = 0.49) among all groups. No significant difference occurred in bending rigidity (four-point bending test) with type of plate (P = 0.41), but when the plate was placed anteroinferiorly, bending rigidity was significantly higher (P < 0.001) than in the superior position. CONCLUSION: Placing the plate anteroinferiorly on the clavicle provides a more stable construct in terms of bending rigidity with no detriment in axial and torsional stiffness compared with placing the plate superiorly. We believe that anteroinferior plating is preferred as a result of the increase in bending rigidity together with other advantages, including avoidance of neurovascular compromise, the use of longer screws, and decreased hardware prominence.