The magnet-actuated craniofacial (MAC) distraction system: preclinical surgical feasibility in a cadaveric model

Craniofacial distraction osteogenesis (DO) is an established technique for the management of complex craniosynostosis but remains limited by the morbidity associated with external activation ports, including infection, wound breakdown, CSF leakage, and mechanical failure. The magnet-actuated craniofacial (MAC) distraction system was developed to eliminate externalized activation components by enabling fully internalized, contactless, noninvasive actuation. The authors of this study aim to evaluate the surgical feasibility, mechanical reliability, and positional stability of the MAC system in a cadaveric human cranial model.

The MAC system was subjected to comprehensive preclinical biomedical and mechanical engineering validation, including finite element analysis, benchtop force-torque testing, magnetic coupling characterization, and assessment of back-drivability resistance and torque-limiting safety features. Following validation, the system was implanted in preserved cadaveric human heads. Devices were placed in a parasagittal coronal configuration. After a latency period, distraction was performed at a rate of 1 mm/day for 10 days, followed by a simulated 60-day consolidation period. CT imaging was performed at predefined intervals to assess device position, distraction distance, and positional stability.

Preclinical testing demonstrated that the MAC system maintained structural integrity under loads exceeding those expected during craniofacial distraction, with a minimum factor of safety of 3 and no evidence of material yielding or mechanical instability. In the cadaveric model, device implantation was surgically feasible without anatomical conflict. An average distraction of 6-9 mm was achieved with controlled, incremental advancement. No device migration, hardware loosening, or unintended back-drivability was observed during active distraction or consolidation. The device maintained the achieved distraction distance at the end of the consolidation period.

This cadaveric feasibility study demonstrates that a fully internalized MAC distraction system can achieve controlled, stable cranial vault distraction without the need for external activation ports. The MAC system exhibited reliable mechanical performance, positional stability, and resistance to back-drivability under anatomically relevant conditions. These findings support further in vivo investigation of biological responses, long-term durability, and clinical safety prior to translation to pediatric craniofacial surgery.