Magnetic Bone Transport Nail Actuation
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Solution Overview
Problem
Current bone transport systems, particularly those using external fixation, can cause infections and are poorly tolerated by patients, necessitating a fully implantable solution that effectively displaces bone segments for regeneration without invasive mechanisms.
Innovation Solution
An intramedullary bone transport nail with a magnetic driver actuated by an external magnetic field, which rotates a threaded rod to translate a transport carriage assembly within the nail, allowing for non-invasive and controlled displacement of a middle bone segment to bridge bone gaps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If external fixation systems are used for bone transport, then bone segments can be displaced for regeneration, but infection risk increases and patient tolerance deteriorates
Solution Approach 1:
The transport carriage is nested within the intramedullary nail, with the carriage moving along the internal channel of the nail. This nested configuration allows the transport mechanism to be fully implantable, eliminating external pins and wires that cause infection, while maintaining the bone transport function.
Solution Approach 2:
The patent replaces traditional mechanical external fixation systems with an internal magnetic actuation system. Magnets embedded in the carriage interact with externally applied magnetic fields to drive transport, eliminating the need for external pins and wires that penetrate skin and bone, thereby reducing infection risk.
2Object-affected harmful factors
If a fully implantable transport nail is used, then patient tolerance improves, but device complexity increases
Solution Approach 1:
The intramedullary nail serves multiple functions: it provides structural support for bone healing, contains an internal channel for carriage movement, and works with the magnetic actuation system. This multi-functionality reduces the need for separate external fixation devices, simplifying the overall treatment system despite the implantable design.
Solution Approach 2:
The magnetic actuation system allows for non-invasive control of the transport carriage. The external magnetic field can be applied through the skin to move the carriage without requiring surgical intervention or complex mechanical linkages, reducing device complexity while maintaining full implantability.
3Ease of operation
If a threaded rod and magnetic driver system is used to actuate the carriage, then non-invasive control is achieved, but manufacturing precision requirements increase
Solution Approach 1:
The magnetic field acts as an intermediary between the external actuator and the internal threaded rod. The magnetic driver converts external magnetic field movements into rotational motion of the threaded rod, which then translates into linear movement of the carriage. This intermediary mechanism allows non-invasive control while using well-established threaded engagement principles that are manageable with standard manufacturing tolerances.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution provides a less invasive, effective means for bone regeneration across gaps, reducing infection risks and improving patient tolerance by using a magnetic actuation system to drive axial movement of the transport carriage assembly within the nail, facilitating bone growth between fragments.
Implementation Method 1
a magnetic driver configured to be non-invasively actuated by a moving magnetic field, the magnetic driver coupled to the threaded rod such that rotation of the magnet drives rotation of the threaded rod
Data Source
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AI summary
An intramedullary bone transport nail configured for axial bone segment transport by an externally applied magnetic field includes a nail body defining an internal chamber that extends along a longitudinal axis of the intramedullary bone transport nail; locking portions for locking the respective ends of the nail body in first and second bone fragments of a long bone, respectively; and a transport carriage assembly that is arranged in an axially movable manner within the internal chamber of the nail body and has a radially oriented aperture for accommodating a transport bone segment screw for fixing a middle bone segment of the long bone to the bone transport carriage. The nail body defines an elongated longitudinal opening to allow a desired range of axial motion of the transport bone segment screw as the transport carriage assembly moves axially by rotation of a threaded rod affixed to a magnetic driver and engaged with a threaded block affixed to the nail body. Rotation of the threaded rod is achieved by application of torque to the magnetic driver by a rotating external magnetic field.