Optimization of a Patient-Specific External Fixation Device for Lower Limb Injuries

Area of Science:

• Orthopedic biomechanics
• Biomaterials engineering
• Additive manufacturing

Background:

• External fixation devices are crucial for bone fracture treatment, offering alignment and stability.
• Increasing trauma and aging populations drive demand for advanced fixation solutions.
• Current external fixators face design challenges due to patient-specific anatomy and defect variability.

Purpose of the Study:

• To develop a methodology for designing personalized, lightweight external fixator devices using additive manufacturing.
• To optimize external fixator design for improved fit, functionality, strength, stiffness, and reduced weight.

Main Methods:

• Data acquisition and Computer Tomography (CT) imaging for patient-specific geometry.
• Computer-Aided Design (CAD) for personalized modeling.
• Weight reduction techniques: imposed predefined patterns and topology optimization.
• Finite element analysis (FEA) with full factorial design of experiments to evaluate materials (PLA, ABS, Polyamide) and thicknesses (3-6 mm).

Main Results:

• Topology optimization combined with polylactic acid (PLA) and 4 mm thickness resulted in the optimal external fixator.
• This optimal design maximized strength and stiffness while significantly minimizing weight.
• FEA validated the superior performance of the topology-optimized PLA fixator.

Conclusions:

• A robust methodology for personalized external fixator design and additive manufacturing is presented.
• Topology optimization offers a superior approach for weight reduction in external fixation devices.
• The study identifies optimal material (PLA) and thickness (4 mm) for high-performance, custom-designed external fixators.