Spinal probe with tactile force feedback and pedicle breach prediction

Patent metadata

Field	Value
Publication number	US-9549744-B2
Application number	US-201013378597-A
Country	US
Kind code	B2
Filing date	Jun 15, 2010
Priority date	Jun 16, 2009
Publication date	Jan 24, 2017
Grant date	Jan 24, 2017

Abstract

A spinal probe comprises a handle, a shaft coupled to the handle and a force sensor to detect forces applied to a tip of the shaft. A controller that executes a predictive algorithm to predict whether or not the tip of the shaft is going to breach a cortex of a pedicle based on the detected forces. The controller may be embedded within the spinal probe or external within a computer or other device coupled to the probe by a data acquisition component.

First claim

The invention claimed is:

1. A spinal probe comprising:
a handle;
a shaft coupled to the handle;
a force sensor configured to detect one or more forces applied to a tip of the shaft in a plane orthogonal to the shaft; and
a controller configured to:
compare the one or more forces to a control limit, and
provide an alert to a user indicating that the tip of the shaft is predicted to breach a cortex of a pedicle of a patient based on the one or more forces exceeding the control limit.

2. The spinal probe of claim 1 , wherein the control limit comprises a patient-specific control limit, and the controller is configured to calculate the patient-specific control limit based on data that indicates a bone density of the pedicle and that was collected by the controller during initial insertion of the shaft into the pedicle of the patient.

3. The spinal probe of claim 1 ,
wherein the force sensor is configured to detect a plurality of axial component forces in a plane orthogonal to the tip and a moment around the shaft of the probe, and
wherein, to compare the one or more forces to the control limit and provide the alert to the user based on the one or more forces exceeding the control limit, the controller is configured to:
compute a radial force based on the detected axial component forces,
compute the control limit as a function of the variance of the moment over time, compare the computed radial force to the control limit, and
provide the alert based on the radial force exceeding the control limit.

4. The spinal probe of claim 1 , wherein the force sensor is axially-mounted on the shaft.

5. The spinal probe of claim 1 , where the spinal probe has a size and a shape of a pedicle awl.

6. The spinal probe of claim 1 , wherein the force sensor is configured to detect forces at the tip of the shaft in six degrees of freedom comprising forces along x, y, and z axes relative to the shaft as well as corresponding moments around the axes, wherein the z axis is parallel to the shaft and the x and y axes are in the plane orthogonal to the shaft.

7. The spinal probe of claim 1 , wherein the force sensor is configured to detect at the tip of the shaft forces along x and y axes and a moment around a z axis relative to the shaft of the sensor, wherein the z axis is parallel to the shaft and the x and y axes are in the plane orthogonal to the shaft.

8. The spinal probe of claim 1 , further comprising a plurality of cylindrical brackets to axially mount the force sensor onto the shaft.

9. The spinal probe of claim 1 , wherein the force sensor comprises a load cell.

10. The spinal probe of claim 1 , wherein the force sensor comprises one or more strain gauges.

11. The spinal probe of claim 1 , wherein the force sensor is embedded within the handle of the spinal probe.

12. The spinal probe of claim 1 , further comprising a wireless transmitter configured to output a wireless signal carrying data representative of the detected forces.

13. The spinal probe of claim 1 , further comprising a removable sleeve mounted axially with the shaft and configured to remain in place within a hole formed by the spinal probe after removal of the spinal probe.

14. The spinal probe of claim 1 , further comprising a printed circuit board having a microcontroller configured to output the sensed force as a digital signal.

15. The spinal probe of claim 1 , wherein the shaft comprises a hollow sensing shaft having a solid sensing tip.

16. The spinal probe of claim 15 , wherein the sensing tip is enclosed by a hollow shell of the sensing shaft.

17. The spinal probe of claim 16 , wherein the hollow sensing shaft encompasses the entire length of the shaft from the tip up to the handle.

18. The spinal probe of claim 16 , wherein the hollow sensing shaft is constructed from carbon fiber and the sensing tip is constructed from steel or titanium.

19. The spinal probe of claim 15 , wherein the force sensor comprises one or more strain gauges mounted in the sensing tip.

20. The spinal probe of claim 1 , wherein the control limit is based on a 95% confidence interval of the mean of successful pedicle tract procedures.

21. The spinal probe of claim 20 , wherein the controller is configured to provide the alert when the one or more forces exceed the 95% confidence interval.

22. The spinal probe of claim 1 , wherein the controller is configured to determine an exponentially weighted moving average of the one or more forces detected by the force sensor, wherein the control limit is based on the exponentially weighted moving average.

23. The spinal probe of claim 22 , wherein the exponentially weighted moving average is not based on input data from previous successful pedicle tract procedures or different patients.

24. The spinal probe of claim 22 , wherein the controller is configured to sample the detected forces to determine the exponentially weighted moving average and compare the sampled forces to the control limit in response to an initial force meeting or exceeding −20 lbf.

25. A method of operation of a spinal probe comprising:
a handle;
a shaft coupled to the handle;
a force sensor mounted within the spinal probe; and
a controller within the spinal probe, the method comprising:
detecting, with the force sensor, one or more forces applied to a tip of the shaft in a plane orthogonal to the shaft during a spinal surgery;
comparing, by the controller within the spinal probe, the one or more forces to a control limit; and
providing, by the controller, an alert to a user indicating that the tip of the shaft of the spinal probe is predicted to breach a cortex of a pedicle of a patient based on the one or more forces exceeding the control limit.

26. The method of claim 25 , wherein providing the alert comprises outputting an audible alert.

27. The method of claim 25 , wherein providing the alert comprises outputting a visual alert.

28. The method of claim 25 , wherein the control limit comprises a patient-specific control limit, the method further comprising:
collecting, by the controller, data that indicates a bone density of the pedicle during initial insertion of the shaft into the pedicle of the patient; and
calculating, by the controller, the patient-specific control limit based on the collected data that indicates the bone density of the pedicle.

29. The method of claim 25 ,
wherein detecting the one or more forces comprises, detecting, with the force sensor, a plurality of axial component forces in a plane orthogonal to the tip and a moment around the shaft of the probe, the method further comprising:
computing, by the controller, a radial force based on the detected axial component forces; and
computing, by the controller, the control limit as a function of a variance of the moment over time as the probe is inserted,
wherein comparing the one or more forces to the control limit comprises comparing, by the controller, the computed radial force to the control limit, and
wherein providing the alert comprises providing, by the controller, an alert based on the radial force exceeding the control limit.

30. The method of claim 25 , further comprising:
sampling, by the controller, the detected forces to determine the exponentially weighted moving average; and
comparing, by the controller, the sampled forces to the control limit in response

Assignees

• Pommer Timothy J
• Polly Jr David W
• Nuckley David J
• Gustafson Evan M
• Ledonio Charles Gerald Tan
• Erdman Arthur G
• Univ Minnesota

Inventors

• Pommer Timothy J
• Polly Jr David W
• Nuckley David J
• Gustafson Evan M
• Ledonio Charles Gerald Tan
• Erdman Arthur G

Classifications

• A61B5/407

  Evaluating the spinal cord (for locating the epidural space A61B5/4896) · CPC title

• A61B5/6849

  in combination with a needle set · CPC title

• A61B2562/0247

  Pressure sensors · CPC title

• A61B5/6843

  Monitoring or controlling sensor contact pressure · CPC title

• A61B2562/046

  in a matrix array · CPC title