The effect of wire plane tilt and olive wires on proximal tibia fracture fragment stability and fracture site motion

To analyze the effect of the tilt angle relationship between the crossed wire plane and the bone axis on the stiffness of fine wire external fixation, load-deformation behavior was compared across different tilt angles (0°, 10°, and 20°) of the plane containing crossed smooth or olive wires under identical conditions of central axial compression, medial compression-bending, posterior compression-bending, posteromedial compression-bending, and torsion. Stiffness values were calculated from the load-deformation and torque-angle curves. A tilt angle of 20° with olive wires provided significantly greater stiffness compared to smooth wires at any angle in any loading condition (p<0.05). A tilt angle of 20° with olive wires was also significantly more stiff than a tilt angle of 0° with olive wires in any loading condition. In torsion, olive wires with 10° and 20° tilt were not significantly different, while in posterior bending olive wires with 10° tilt were significantly stiffer than olive wires with 0° or 20° tilt. With smooth wires, tilting the wire plane caused a decrease in stiffness in posterior bending, posteromedial bending, and torsion. Overall, the use of olive wires in conjunction with tilting the wire plane enhances the fixation stiffness for proximal tibia fractures while allowing more options for wire configurations that avoid neurovascular and musculotendinous structures, and wounds.