System and method for dynamically stimulating bone growth

• US 10,292,831 B2
• Filed: 03/19/2016
• Issued: 05/21/2019
• Est. Priority Date: 03/20/2015
• Status: Active Grant

• Current Assignee: Intelligent Implants Limited
• Original Assignee: Intelligent Implants Limited
• Inventors: Zellmer, Erik, Murphy, Rory
• Primary Examiner(s): Woodall, Nicholas W
• Application Number:
  US15/075,152
• Publication Number:
  US 20160270927A1
• Time in Patent Office: 1,158 Days
• CPC Class Codes: A61B 2562/0219 Inertial sensors, e.g. accelerometers, gyroscopes, tilt switches
• CPC Class Codes: A61B 5/0031 Implanted circuitry
• CPC Class Codes: A61B 5/0538 invasively, e.g. using a catheter
• CPC Class Codes: A61B 5/4504 Bones A61B5/4547 takes precedence
• CPC Class Codes: A61B 5/4566 Evaluating the spine A61B5/4561 takes precedence
• CPC Class Codes: A61B 5/686 Permanently implanted devices, e.g. pacemakers, other stimulators, biochips A61B5/6861 takes precedence
• CPC Class Codes: A61B 5/7225 Details of analog processing, e.g. isolation amplifier, gain or sensitivity adjustment, filtering, baseline or drift compensation A61B5/30, A61B5/316 take precedence; transformers for specific applications H01F38/00; amplifiers H03F
• CPC Class Codes: A61F 2/28 Bones joints A61F2/30
• CPC Class Codes: A61F 2/44 for the spine, e.g. vertebrae, spinal discs
• CPC Class Codes: A61F 2/4455 for the fusion of spinal bodies, e.g. intervertebral fusion of adjacent spinal bodies, e.g. fusion cages intervertebral discs A61F2/442
• CPC Class Codes: A61F 2/4465 having a circular or kidney shaped cross-section substantially perpendicular to the axis of the spine
• CPC Class Codes: A61F 2/482 Electrical means
• CPC Class Codes: A61F 2002/2821 Bone stimulation by electromagnetic fields or electric current for enhancing ossification
• CPC Class Codes: A61F 2002/30187 D-shaped or half-disc-shaped
• CPC Class Codes: A61F 2002/30593 hollow
• CPC Class Codes: A61F 2002/30622 Implant for fusing a joint or bone material
• CPC Class Codes: A61F 2002/30668 Means for transferring electromagnetic energy to implants
• CPC Class Codes: A61F 2002/3067 for data transfer
• CPC Class Codes: A61F 2002/469 electrical
• CPC Class Codes: A61N 1/326 for promoting growth of cells, e.g. bone cells
• CPC Class Codes: A61N 1/3787 : from an external energy source

Abstract

A system and method for electrical stimulation in an orthopedic implant that includes at least one implantable component with an implant body, a plurality of electrodes, and implant circuitry is effective to convert an external wireless power transmission to an electrical current and effective to control the plurality of electrodes; and at least one non-implant with a power source, and transmitter circuitry to generate the electromagnetic field that couples with the implant circuitry.

Claims

1. A system for electrical stimulation in an orthopedic implant comprising:

at least one implantable component that comprises;

a spinal cage implant body,

a set of at least three electrodes conductively isolated from the implant body and exposed at a set of distinct electrode sites on the implant body, and

implant circuitry that comprises implant receiver circuitry effective to convert an electromagnetic field to an electrical current and implant control circuitry configured to control current flow of the set of electrodes, wherein each of the set of electrodes is conductively coupled to the implant control circuitry and is conductively isolated from each of the remaining electrodes in the set of electrodes; and

at least one non-implant that comprises;

a power source, and

transmitter circuitry to generate the electromagnetic field that couples with the implant receiver circuitry.

2. The system of claim 1, the control circuitry is configured to update the polarity of an electrode and magnitude of the electrical current flowing through the electrode in the set of electrodes.

3. The system of claim 2, wherein the electrode is set as a cathode in a first stimulation mode state of the control circuitry and as an anode in a second stimulation mode state of the control circuitry.

4. The system of claim 1, wherein the set of electrode sites are exposed on external surfaces of the spinal cage implant body and implant circuitry is integrated within the structure of the spinal cage.

5. The system of claim 1, wherein the implant control circuitry is additionally configured to selectively operate in an impedance monitoring mode;

wherein, when in an impedance monitoring mode, the control circuitry is configured to measure the impedance between a set of electrodes and generate an impedance profile.

6. The system of claim 5, wherein the implant circuitry additionally selectively operates in a diagnostics mode configured to verify power status, electrode status, and communication status.

7. The system of claim 5, wherein the implant control circuitry is configured to update the polarity of an electrode and the magnitude of the electrical current flowing through the electrode based in part on the impedance profile.

8. The system of claim 7, wherein the implant circuitry comprises implant communication circuitry configured to wirelessly transmit at least the impedance profile to the non-implantable component.

9. The system of claim 1, wherein the conductive coupling to each of the at least three electrodes are individually drivable between at least three states that include anode, cathode, and passive.

10. The system of claim 1, wherein a set of logic inputs from the implant control circuitry is conductively coupled to each electrode of the set of electrodes through an end stage gate system.

11. The system of claim 1, wherein the electrode sites are conductively coupled to the implant control circuitry directly.

12. The system of claim 1, wherein at least two electrode sites have differing geometry.

13. The system of claim 1, further comprising of at least one electrode that is electrically coupled to the implant control circuitry as a dedicated anode;

and wherein the at least one electrode is positioned at the posterior region of the implant.

14. The system of claim 1, further comprising a second set of electrodes that are conductively coupled and controlled simultaneously by the implant control circuitry.

15. The system of claim 1, wherein the configuration of the implant control circuitry to control current flow is further configured to control frequency and duty cycle of the current flow.

16. The system of claim 1, further comprising:

bone growth monitoring circuitry conductively coupled to the set of electrodes, the bone growth monitoring circuitry configured to measure the impedance between a set of electrodes.

17. The system of claim 16, wherein the bone growth monitoring circuitry is configured to drive alternating current signals between pairs of electrodes.

18. The system of claim 16, wherein the plurality of electrodes are conductively coupled to the bone growth monitoring circuitry through a set of multiplexers and demultiplexers, the bone growth monitoring circuitry configured to cycle through a set of impedance checks where the bone growth monitoring circuitry selectively measures impedance between at least two electrodes of the set of electrodes.

19. The system of claim 1, further comprising:

impedance measurement circuitry conductively coupled to the set of electrodes, the bone growth monitoring circuitry configured to measure the impedance between a set of electrodes.

20. The system of claim 19, further comprising:

wherein the impedance measurement circuitry comprises;

an alternating current signal generator,

a demultiplexer system with an input connected to the alternating current signal generator, a set of controllably selected outputs connected to each of the set of electrodes, and an output selection control that is connected to a first control signal input of the implant circuitry, wherein the demultiplexer system connects the input to only one selected output based on the first control signal, and

a multiplexer system with inputs connected to each electrode of the set of electrodes, the multiplexer system having an output signal driven by any one electrode of the set of electrodes, wherein the implant circuitry has a second control signal to the an input selection control of the multiplexer system, wherein the output signal is connected to a voltage measurement input of a processor for impedance measurement; and

wherein the impedance measurement circuitry, when in an impedance measurement mode, is configured to cycle through pairs of electrodes selected from set of electrodes, wherein in each cycle the impedance measurement circuitry drives alternating current through a first selected electrode of the set of electrodes and measures voltage from a second electrode selected by the multiplexer system.

21. The system of claim 1, wherein the implant receiver circuitry comprises an antenna aligned coplanar along the posterior surface of the spinal cage structure.

22. A system for a spinal fusion cage with electrical stimulation capabilities comprising:

an implantable component comprising;

a non-conductive spinal cage structure;

a plurality of electrodes integrated into the spinal cage structure, wherein the electrodes are exposed at a set of distinct electrode sites on the surface of the spinal cage structure,

implant receiver circuitry with a receiver for wirelessly transmitted power,

implant control circuitry conductively coupled to the plurality of electrodes, the implant control circuitry configured to control polarity and stimulation magnitude of at least three electrodes independently,

bone growth monitoring circuitry conductively coupled to the plurality of electrodes and electrically configured to selectively measure impedance between at least two pairs of electrodes; and

implant communication circuitry configured to transmit implant operating data.

23. The system of claim 22, wherein each of the plurality of electrodes can be selectively switched between acting as an anode or as a cathode.

24. The system of claim 22, further comprising a non-implantable component that comprises a power source and transmitter circuitry that generates a wireless power signal receivable by the implant receiver circuitry.