Analysis of fixation methods for vertical shear fractures of the medial malleolus

Abstract

Objective: To evaluate 4 different fixation methods used to treat vertical shear fractures of the medial malleolus.

Methods: Eighty polyurethane models of the distal tibia were osteotomized in a reproducible manner to create a vertical shear fracture of the medial malleolus. Twenty specimens were then randomly assigned to 1 of 4 fixation groups. Two fixation groups used a neutralization plate, whereas 2 groups were screw-only constructs. Ten of the specimens in each group were then randomly assigned to undergo either offset axial or offset transverse loading.

Results: The construct using a neutralization plate with 2 screws in the distal fragment exhibited greater stiffness in offset axial loading compared with the screw-only constructs placed an equivalent distance from the tibial plafond. All specimens in the group with the properly applied neutralization plate exhibited elastic deformation, whereas the majority of the specimens in all other groups showed residual displacement or catastrophic failure of the construct.

Conclusion: Fixation of vertical shear fractures of the medial malleolus with a properly applied neutralization plate offers a significant mechanical advantage over screw-only constructs.