Multi-axis, programmable spine testing system

• US 20070161872A1
• Filed: 12/01/2006
• Published: 07/12/2007
• Est. Priority Date: 12/03/2005
• Status: Active Grant

• Current Assignee: University of Tennessee Research Foundation (University of Teesside)
• Original Assignee: University of Tennessee Research Foundation (University of Teesside)
• Inventors: Kelly, Brian, DiAngelo, Denis
• Granted Patent: US 7,895,899 B2
• Time in Patent Office: Days
• US Class Current: 600/300
• CPC Class Codes: A61B 2017/00707 Dummies, phantoms; Devices simulating patient or parts of patient
• CPC Class Codes: A61B 2017/00725 Calibration or performance testing
• CPC Class Codes: A61B 2090/064 for measuring force, pressure or mechanical tension
• CPC Class Codes: A61B 5/1126 using a particular sensing technique
• CPC Class Codes: A61B 5/4504 Bones A61B5/4547 takes precedence
• CPC Class Codes: A61B 5/4514 Cartilage
• CPC Class Codes: A61B 5/4528 Joints A61B5/4533, A61B5/4538 take precedence
• CPC Class Codes: A61B 5/4561 Evaluating static posture, e.g. undesirable back curvature A61B5/1116 takes precedence
• CPC Class Codes: A61B 5/4566 Evaluating the spine A61B5/4561 takes precedence
• CPC Class Codes: A61B 90/06 Measuring instruments not otherwise provided for
• CPC Class Codes: A61F 2/442 Intervertebral or spinal discs, e.g. resilient non-disc-shaped intervertebral inflatable pockets A61F2/441; non-disc-shaped intervertebral fusion implants A61F2/4455
• CPC Class Codes: A61F 2/468 Testing instruments for artificial joints for testing non-implantable prostheses A61F2/76
• CPC Class Codes: A61F 2002/4666 for measuring force, pressure or mechanical tension
• CPC Class Codes: G01N 2203/0089 Biorheological properties
• CPC Class Codes: G01N 2203/0246 Special simulation of "in situ" conditions, scale models or dummies
• CPC Class Codes: G01N 3/08 by applying steady tensile or compressive forces G01N3/28 takes precedence
• CPC Class Codes: G01N 3/22 by applying steady torsional forces G01N3/26, G01N3/28 take precedence
• CPC Class Codes: G01N 3/24 by applying steady shearing forces G01N3/26, G01N3/28 take precedence
• CPC Class Codes: G09B 23/306 comprising real biological tissue
• CPC Class Codes: G09B 23/32 with moving parts

Abstract

A biomechanical system for testing a coupled joint is provided. The coupled joint has a fixed first end and a moving second end within the testing system. The testing system includes a servo actuation system operatively connected to the moving end. The system is able to impart at least four degrees of freedom to the moving end of the coupled joint. The testing system also includes a first force sensor disposed between the servo actuation system and the moving end of the coupled joint for sensing applied load, and a second force sensor disposed at the fixed end of the coupled joint for sensing transmitted load. The system also includes a controller for selectively directing input signals to the servo actuation system in order to apply selected forces and/or motions to the moving end of the coupled joint. The coupled joint may be a cervical spine specimen.

Claims

1. A system for testing a coupled joint, the coupled joint mounted within the system to have a fixed end and a moving end, comprising:

an actuation system operatively connected to the moving end of the coupled joint for imparting at least four degrees of freedom, the four degrees of freedom comprising a first translational degree of freedom along a first translational axis, a second translational degree of freedom along a second translational axis, the first and second translational axes forming a first plane of motion, a first rotational degree of freedom about a first rotational axis orthogonal to the first plane of motion, and a second rotational degree of freedom about a second rotational axis orthogonal to the first rotational axis and moving within the first plane of motion;

a first force sensor disposed between the actuation system and the moving end of the coupled joint for sensing applied force; and

a controller for applying selected forces, motions, or combinations thereof, to the moving end of the coupled joint within the four degrees of freedom.

2. The system of claim 1, wherein the controller receives input signals in order to apply the selected forces, motions, or combinations thereof to the moving end of the coupled joint within the four degrees of freedom.

3. The system of claim 2, further comprising a second force sensor disposed at the fixed end of the coupled joint for sensing transmitted force.

4. The system of claim 3, wherein the input signals to the controller comprise force signals sent from the first force sensor and the second force sensor.

5. The system of claim 3, wherein the input signals to the controller comprise motion signals.

6. The system of claim 5, wherein the motion signals to the controller comprise at least one of velocity and position.

7. The system of claim 6, wherein the motion signals to the controller are sent from encoders.

8. The system of claim 3, wherein the input signals to the controller comprise at least one of pressure, force or strain signals from a sensor affixed to the coupled joint.

9. The system of claim 4, wherein the two translational degrees of freedom comprise a first degree of freedom along a first horizontal axis, and a second degree of freedom along a second vertical axis.

10. The system of claim 4, wherein the controller, the input signals, and the actuation system are part of a control system.

11. The system of claim 5, wherein the actuation system is a servo system, a stepper motor system, a hydraulic system, a pneumatic system, or a magnetically driven system.

12. The system of claim 2, wherein the input signals are sent in response to at least one of pressure, force, motion, strain and pressure.

13. The system of claim 6, wherein the actuation system comprises:

a first rotary actuator for imparting rotation to the coupled joint about the first rotational axis; and

a second rotary actuator for imparting rotation to the coupled joint about the second rotational axis.

14. The system of claim 13, wherein the first and second rotary actuators operatively interact orthogonally through a gimbal connection.

15. The system of claim 14, wherein the first and second rotary actuators provide rotation up to at least 180°

.

16. The system of claim 13, wherein the actuation system further comprises:

a first linear actuator for imparting translation to the coupled joint along the first horizontal axis; and

a second linear actuator for imparting translation to the coupled joint along the second vertical axis.

17. The system of claim 16, wherein the first linear actuator and the second linear actuator each provide travel of about 200 mm to about 700 mm.

18. The system of claim 2, wherein the coupled joint is a spinal specimen comprising at least one spinal motion segment unit.

19. The system of claim 18, wherein the spinal specimen comprises at least a portion of a cervical spine, a thoracic spine, a lumbar spine, or combinations thereof.

20. The system of claim 18, wherein the spinal motion segment unit is either a model or a cadaveric sample.

21. The system of claim 18, wherein the spinal specimen further comprises a spinal implant.

22. The system of claim 4, wherein the first and second force sensors each define a six-axis sensor.

23. The system of claim 3, wherein:

the testing system further comprises a frame for supporting the coupled joint, with the frame defining a volume for receiving the coupled joint; and

the testing system volume is capable of receiving coupled joints of varying lengths.

24. The system of claim 23, wherein:

the coupled joint is supported within the frame in a vertical orientation; and

the system further comprises a lower clamping fixture for releasably supporting the fixed end of the coupled joint, and an upper clamping fixture for releasably supporting the moving end of the coupled joint.

25. The system of claim 2, wherein the first translational degree of freedom originates along a first horizontal axis, and the second translational degree of freedom originates along a second vertical axis.

26. The system of claim 25, wherein the actuation system imparts six degrees of freedom to the moving end of the coupled joint, the six degrees of freedom comprising:

the first translational degree of freedom originating along a first horizontal axis, and the second translational degree of freedom originating along a second vertical axis, the first horizontal axis and the second vertical axis defining the first plane of motion;

a third translational degree of freedom originating along a third horizontal axis orthogonal to the first horizontal axis, the second and third translational axes forming a second plane of motion;

the first rotational degree of freedom residing about a first rotational axis that lies within the first plane of motion and is parallel to the first horizontal axis;

the second rotational degree of freedom residing about the second rotational axis that is orthogonal to the first rotational axis and moves within the second plane of motion; and

a third rotational degree of freedom about the third rotational axis orthogonal to the second rotational axis and moving within a plane orthogonal to the second rotational axis.

27. A system for testing a coupled joint, the coupled joint mounted within the system to have a fixed end and a moving end, comprising:

a control actuation system operatively connected to the moving end of the coupled joint for imparting at least four degrees of freedom;

a first force sensor disposed between the actuation system and the moving end of the coupled joint for sensing applied force;

a second force sensor disposed at the fixed end of the coupled joint for sensing transmitted force; and

a controller for selectively directing input signals to the control actuation system in order to simultaneously apply selected forces and motions to the moving end of the coupled joint such that a loading pattern is provided that correlates to a human physiologic response.

28. A system for testing a coupled joint, the coupled joint mounted within the system to have a fixed end and a moving end, comprising:

a control actuation system operatively connected to the moving end of the coupled joint for imparting six degrees of freedom, the six degrees of freedom comprising three substantially orthogonal translation axes in a Cartesian coordinate system, and three rotational axes;

a first force sensor disposed between the control actuation system and the moving end of the coupled joint for sensing applied force; and

a controller for selectively directing input signals to the control actuation system in order to apply selected forces, motions, or combinations thereof, to the moving end of the coupled joint within the six degrees of freedom.

29. The system of claim 28, wherein:

the three orthogonal translation axes comprise a first translational degree of freedom along a first translational axis, a second translational degree of freedom along a second translational axis, and a third translational degree of freedom along a third translational axis;

a first plane of motion is formed by the first and second translational axes;

a second plane of motion is formed by the second and third translational axes; and

the three rotational axes comprise a first rotational degree of freedom about the first translational axis, a second rotational degree of freedom about the second translational axis, and a third rotational degree of freedom about the third translational axis.

30. The system of claim 29, wherein:

the first translational axis and the third translational axis are each substantially horizontal;

the second translational axis is substantially vertical;

the first rotational degree of freedom resides about a first rotational axis that lies within the first plane of motion and is parallel to the first horizontal axis;

the second rotational degree of freedom resides about the second rotational axis and is orthogonal to the first rotational axis and moves within the second plane of motion; and

the third rotational degree of freedom resides about the third rotational axis orthogonal to the second rotational axis and moves within a plane orthogonal to the second rotational axis.

31. The system of claim 29, wherein:

the first translational axis and the third translational axis are each substantially horizontal;

the second translational axis is substantially vertical;

the first rotational degree of freedom resides about the second rotational axis and is orthogonal to the first rotational axis and moves within the second plane of motion;

the second rotational degree of freedom resides about a first rotational axis that lies within the first plane of motion and is parallel to the first horizontal axis; and

the third rotational degree of freedom resides about the third rotational axis orthogonal to the second rotational axis and moves within a plane orthogonal to the second rotational axis.