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The Magnet-Actuated Craniofacial (MAC) Distraction System: Magnetic Coupling Modeling.
Mohammed A Fouda1, David Dostal2, Caitlin E Hoffman3
1Department of Neurological Surgery, New York-Presbyterian Hospital, Weill Cornell Medicine, 525 E 68thSt, New York, NY, 10065, USA. Maf4023@med.cornell.edu.
Annals of Biomedical Engineering
|June 26, 2026
Summary
A novel Magnet-Actuated Craniofacial (MAC) distraction system offers a fully-internalized solution for craniofacial abnormalities. This innovative design overcomes limitations of external ports, improving patient outcomes and reducing complications in distraction osteogenesis.
Area of Science:
- Biomedical Engineering
- Craniofacial Surgery
- Medical Device Design
Background:
- Craniofacial distraction osteogenesis (DO) effectively treats craniofacial abnormalities but current systems have external ports increasing infection and failure risks.
- External ports in DO systems pose sociopsychological burdens and risks of premature device removal.
- The Magnet-Actuated Craniofacial (MAC) distraction system is a fully-internalized alternative to eliminate external ports.
Purpose of the Study:
- To optimize the magnetic coupling efficiency of the novel Magnet-Actuated Craniofacial (MAC) distraction system.
- To evaluate different magnetic coupling configurations for transdermal torque transmission.
- To assess the performance of the MAC system across variable separation distances.
Main Methods:
- A 3D magnetostatic finite element modeling (FEM) framework was employed for optimization.
- Compared traditional coaxial dipole coupling with a U-shaped, flux-guided magnetic circuit.
- Parametric analyses quantified torque-angle behavior, torsional stiffness, and axial forces up to 11.5 mm separation.
Main Results:
- Coaxial dipole configuration showed significant torque and force decay with increased separation.
- The U-shaped, flux-guided architecture demonstrated a six-fold increase in peak torque and five-fold improvement in torsional stiffness.
- Clinically relevant torque and forces were maintained at larger separation distances with the U-shaped design.
Conclusions:
- Magnetic actuation limitations are design-dependent, not inherent.
- Flux-guided magnetic circuit engineering enables robust, precise, and predictable transdermal torque transmission.
- The MAC system's design supports the feasibility of fully-internalized, magnetically-actuated craniofacial distraction.
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