Transfixion wire positioning within the bone: an option to control proximal tibia external fixation stiffness

Area of Science:

• Orthopedic biomechanics
• Surgical fixation techniques

Background:

• External fixation of proximal tibia fractures often faces limitations in achieving optimal stiffness.
• Current wire configurations may not adequately address sagittal plane stability.

Purpose of the Study:

• To evaluate the impact of different wire positioning strategies on the stiffness of proximal tibia external fixation.
• To investigate methods for increasing sagittal bending stiffness in external fixation constructs.

Main Methods:

• A composite tibia model in an external fixation frame was subjected to various loading conditions (axial compression, bending, torsion).
• Load-deformation and torque-angle data were analyzed to calculate stiffness for each wire configuration.
• Tested configurations included variations in wire placement within the proximal tibia.

Main Results:

• A specific configuration—two wires 1 cm posterior and one wire 1 cm anterior in the coronal plane—demonstrated significantly higher stiffness.
• This configuration showed superior performance in posterior, posteromedial, and torsional loading compared to others.
• The optimal positioning increased stiffness predominantly in the sagittal plane.

Conclusions:

• A novel wire positioning strategy enhances proximal tibia external fixation stiffness, particularly in the sagittal plane.
• This finding offers a method to better control and improve the stability of external fixation constructs.
• Provides a biomechanical rationale for optimizing wire placement in proximal tibia external fixation.