Lateral clavicle fractures: grid pattern arrangement of screws in the lateral fracture fragment reduces the cut-out

Abstract

Introduction

Lateral clavicle fractures often need to be stabilized by a plate osteosynthesis and due to the acting high forces a cut-out of the screws of the lateral fracture fragment can occur. New plates enable to place anterior screws in addition to the screws placed from the top of the clavicle. This experimental in-vitro study will determine whether they have a substantial biomechanical effect.

Materials and methods

In synthetic bones, lateral clavicle fractures were created and stabilized in 4 different groups: In Group A, a lateral clavicle plate was fixed with 3 screws in the lateral fracture fragment. In group B, the same type of plate was fixed with additionally two screws from anterior in the lateral fragment. In group C, a coraco-clavicular banding was added to the fixation method of group B. A similar plate from another company was used in group D with a screw fixation method comparable to group A. In a material testing machine, the specimens were loaded by dynamic and static tests. The mode of failure and pull-out forces were analyzed.

Results

In the dynamic testing phase, five specimens failed already in group A and B, whereas in group C 11 specimens survived the cyclic tests. Lateral fractures and screw cut-out appeared in the static tests mostly in group A and B. In contrast, in group C, ten of eleven specimens failed by a medial fracture at the plate end. No significant differences were determined in-between groups for the displacement recorded by the optical system, even, when group A revealed the highest values of the groups A-C. In group D, the specimens showed an early screw cut-out of the lateral fracture fragment, and all failed during the dynamic testing phase.

Conclusions

The use of additional screws from anterior led in a significant lower cut-out and higher biomechanical stability at the lateral clavicle regarding axial tensile forces. From a biomechanical point of view, plates for stabilization of lateral clavicle fractures with additional screw holes from anterior and restoring the cc-bands is favorable to standard plates with screws from the top of the clavicle only.