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US 10,743,794 B2Granted
Devices and methods for non-invasive implant length sensing
AssigneeNuVasive Specialized Orthopedics, Inc.
InventorScott Pool
Life of this patent
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Abstract
A device for the non-invasive sensing of the length of an implantable medical device includes an implantable medical device having first and second portions moveable relative to one another and a layer of resistive material disposed on one of the first and second portions. A contact is disposed on the other of the first and second portions, the contact being in sliding contact with the layer of resistive material upon relative movement between the first and second portions. A circuit is configured to measure the electrical resistance along a path including a variable length region of the layer of resistive material and the contact. The electrical resistance can then be converted into a length.
Claims27
A device comprising:
- a distraction rod configured for complete subcutaneous implantation, the distraction rod comprising:
- a first conductive portion comprising:
- a first end configured for attachment to bone, and a second end having at least a portion of a first conductive surface disposed thereon;
- a second conductive portion comprising:
- a hollow portion configured to telescopically receive the first conductive portion therein, the hollow portion further comprising a second conductive surface disposed on an interior surface thereof, the second conductive surface separated from the first conductive surface by a dielectric tube, forming a variable capacitor therewith having a capacitance corresponding to an amount of overlap between the first conductive surface and the second conductive surface and configured to change as the first conductive portion is moved relative to the second conductive portion wherein the first conductive portion and the second conductive portion are telescopically moveable relative to one another along a longitudinal axis of the distraction rod;
- a resonant coil, a first end of the resonant coil electrically coupled to the first conductive portion, and a second end of the resonant coil electrically coupled to the second conductive portion forming a resonant LC circuit with the variable capacitor formed between the first conductive portion and the second conductive portion;
- and
- a rotatable permanent magnet located within the second conductive portion operatively coupled to a lead screw dimensioned to be received by a threaded nut of the first conductive portion, the lead screw configured to impart relative movement between the first conductive portion and the second conductive portion upon a rotation of the rotatable permanent magnet;
- a drive coil operatively coupled to a signal generator and configured to communicate with the resonant coil wherein the capacitance is formed between the first conductive surface and the second conductive surface when the drive coil communicates with the resonant coil, the capacitance corresponding to a resonant frequency of the distraction rod;
- and
- a frequency analyzer operatively coupled to the drive coil and configured to detect a resonant frequency of the distraction rod, wherein the resonant frequency changes as the amount of overlap between the first conductive portion and the second conductive portion changes, the detected resonant frequency thereby corresponding to a dimension of the distraction rod, with the frequency analyzer configured to at least one of:
- determine and display the dimension of the distraction rod.
9 more elements
A device comprising:
- a distraction rod configured for complete subcutaneous implantation, the distraction rod comprising:
- a conductive housing comprising:
- a hollow portion and a first conductive surface disposed on a surface of the hollow portion;
- a conductive rod comprising a hollow segment and a second conductive surface, the conductive rod disposed at least partially within the hollow portion
- of the conductive housing, the second conductive surface separated from the first conductive surface by a dielectric tube, forming a variable capacitor therewith and having a capacitance corresponding to an amount of overlap between the first conductive surface and the second conductive surface, the amount of overlap and the capacitance configured to change as the conductive housing is moved relative to the conductive rod;
- a resonant coil electrically coupled at a first end to the conductive housing and at a second end to the conductive rod forming a resonant LC circuit with the variable capacitor formed between the first conductive surface and the second conductive surface;
- and
- a rotatable permanent magnet located within the conductive housing and operatively coupled to a lead screw dimensioned to be received by a threaded nut of the conductive rod, the lead screw configured to impart relative movement between the conductive housing and the conductive rod upon a rotation of the rotatable permanent magnet;
- a drive coil operatively coupled to a signal generator and configured to communicate with the resonant coil wherein the capacitance formed between the amount of overlap between the first conductive surface of the conductive housing and the second conductive surface of the conductive rod when the drive coil communicates with the resonant coil, corresponds to a resonant frequency of the distraction rod;
- and
- a frequency analyzer operatively coupled to the drive coil and configured to detect the resonant frequency of the distraction rod, the resonant frequency detected by the frequency analyzer thereby corresponding to a dimension of the distraction rod, with the frequency analyzer configured to at least one of:
- determine and display the dimension of the distraction rod.
9 more elements
Dependencies are inferred from the claim text.