Mechanics of dynamic needle insertion into a biological material

Area of Science:

• Biomechanics
• Biomaterials Science
• Medical Device Engineering

Background:

• Needle-based procedures often involve tissue layer transitions, leading to complex rupture events with significant forces and deformations.
• Understanding these rupture mechanics is crucial for improving procedural safety and efficacy.

Purpose of the Study:

• To describe the mechanics of needle-induced tissue rupture events.
• To analyze the effect of insertion velocity on needle force, tissue deformation, and work during rupture.
• To model rupture events using fracture mechanics principles.

Main Methods:

• Utilized the J integral method from fracture mechanics to model rupture as sudden crack extensions.
• Employed a nonlinear viscoelastic Kelvin model to predict tissue deformation and rupture force relationships at varying velocities.
• Conducted experiments on multilayered porcine cardiac tissue to validate analytical predictions.

Main Results:

• Increasing needle insertion velocity reduces rupture force by enhancing the energy release rate.
• Tissue deformation and work asymptotically approach minimum values at higher velocities.
• Optimal benefits from increased velocity are achievable at a finite rate inversely proportional to tissue relaxation time.

Conclusions:

• Needle insertion velocity is a critical parameter influencing tissue rupture mechanics.
• The study provides a predictive model for rupture behavior, aiding in the design and use of needle-based instruments.
• Experimental validation confirms the theoretical framework, offering insights into safe and efficient tissue manipulation.