Tip Design for Safety of Steerable Needles for Robot-Controlled Brain Insertion

Area of Science:

• Neurosurgery
• Biomedical Engineering
• Medical Device Design

Background:

• Neurosurgical needle insertion is limited by rigid probes, restricting trajectories.
• Flexible bevel-tipped needles offer curvilinear paths but require careful design for brain tissue safety.
• Balancing steering asymmetry with a rounded tip is crucial for safe brain needle insertion.

Purpose of the Study:

• To develop a safe and effective bevel-tipped brain needle design.
• To optimize needle parameters (gauge, bevel angle, fillet radius) for brain tissue compatibility.
• To evaluate the performance and safety of the novel needle design.

Main Methods:

• Finite-element simulations modeled needle insertion and rotation in brain tissue.
• Brain tissue was simulated as a hyperelastic, linear viscoelastic material.
• Safety thresholds for strain, strain rate, and stress were established and applied to design parameters.

Main Results:

• A prototype needle (1.66 mm diameter, 10° bevel angle, 0.25 mm fillet radius) was selected.
• Simulations identified safe operating parameters and velocity envelopes.
• In vivo porcine model showed no significant difference in tissue trauma or hemorrhage compared to a standard biopsy needle.

Conclusions:

• A general design methodology for safe bevel-tipped brain needles was established.
• The design balances steering capability with brain tissue safety thresholds.
• Further research is needed to refine safety thresholds for optimal clinical application.