INTEGRATED POSITION AND PARAMETER SENSING FOR THE MUSCULARSKELETAL SYSTEM

• US 20100332152A1
• Filed: 06/29/2010
• Published: 12/30/2010
• Est. Priority Date: 06/30/2009
• Status: Active Grant

• Current Assignee: Howmedica Osteonics Corp. (Stryker Corporation)
• Original Assignee: OrthoSensor, Inc (Stryker Corporation)
• Inventors: Stein, Marc
• Granted Patent: US 9,301,720 B2
• Time in Patent Office: Days
• US Class Current: 702/41
• CPC Class Codes: A61B 5/4509 Bone density determination
• CPC Class Codes: A61B 5/4528 Joints A61B5/4533, A61B5/4538 take precedence
• CPC Class Codes: A61B 5/6846 specially adapted to be brought in contact with an internal body part, i.e. invasive
• CPC Class Codes: A61B 5/6878 Bone
• CPC Class Codes: A61B 5/7239 using differentiation including higher order derivatives
• CPC Class Codes: A61B 8/15 Transmission-tomography

Abstract

A measurement system for capturing a transit time, phase, or frequency of energy waves propagating through a propagation medium is disclosed. The measurement system comprises a sensing module (200) and an insert dock (202). The sensing module (200) includes a load sensing platform (121), an accelerometer (122), and sensing assemblies (123). In one embodiment, a force or load applied by the muscular-skeletal system is measured. The force or load is applied to the sensing assembly (123). The accelerometer (122) generates motion data. The motion data includes acceleration data. The force or load measured by sensing assembly (123) in combination with the motion data captured by the accelerometer (122) is used to calculate a total force or load. A second accelerometer can be used to provide reference position information. The sensing assemblies (123) comprise a transducer (304), an elastic or compressible propagation structure (305), and a second transducer (314).

Claims

1. A sensing module comprising:

a sensing assembly coupled to a muscular-skeletal system; and

at least one accelerometer where a force measurement includes force data from the sensing assembly and motion data from the at least one accelerometer.

2. The sensing module of claim 1 where the accelerometer acquires motion data in a vector quantity.

3. The sensing module of claim 2 where the accelerometer measures a direction and magnitude of acceleration.

4. The sensing module of claim 3 further including a second accelerometer coupled to the muscular-skeletal system to measure acceleration and establish a reference point.

5. The sensing module of claim 4 where the sensing assembly measures a transit time, frequency, or phase of an acoustic signal through a medium and where a change in force applied by the muscular-skeletal results in a change in length of the medium.

6. The sensing module of claim 5 where an integer number of energy waves propagates in the medium.

7. The sensing module of claim 6 further including a propagation tuned oscillator in positive closed-loop feedback coupled to the sensing assembly to sustain emission, propagation, and detection of energy waves in the medium.

8. The sensing module of claim 7 where the sensing assembly comprises:

a first transducer;

a waveguide where the first transducer couples to the waveguide at a first location; and

a second transducer coupled to the waveguide at a second location where the waveguide corresponds to the medium and where the propagation tuned oscillator couples to the first and second transducers.

9. A sensing module, comprising:

a load sensing platform to receive loading;

an accelerometer to produce motion data comprising acceleration data;

a sensing assembly to measure a force; and

a processor to

determine load data on the load sensing platform,

estimate a total force based on the load data and motion data.

10. The module of claim 9 where the sensing assembly comprises a compressible propagation structure, where the length of the propagation structure corresponds to an applied force thereto, and where the length of the propagation structure is measured.

11. The module of claim 9, further including a second accelerometer, where the first accelerometer is on a first bone to provide first acceleration data, and the second accelerometer is on a second bone to provide second acceleration data, together used as a vector sum to determine effective motion.

12. The module of claim 9, where the sensing assembly comprises an elastic or compressible propagation structure between a first transducer and a second transducer.

13. The module of claim 9, where the load sensing platform comprises a top steel plate coupled to a lower printed circuit board (PCB) by way of spring retainer, disc spring, and spring post.

14. The module of claim 9, where the accelerometer includes single-axis and multi-axis structures to detect magnitude and direction of the acceleration.

15. The module of claim 9, where the sensing assembly is positioned, engaged, attached, or affixed to load bearing contact surfaces having mechanical supports to provide proper balancing of load bearing contact surfaces.

16. The module of claim 9, further comprising a transceiver to transmit a level and a direction of the applied force to a receiving station.

17. The module of claim 9, where the processor is a state machine, pre-programmed logic, electronic circuitry, or a micro-controller.

18. A method of measuring a force comprising the steps of:

applying a force or load to a load sensing platform;

determining length changes to sensing assemblies;

acquiring motion data from an accelerometer; and

estimating total load and forces based on the load data, length changes, and motion data.

19. The method of claim 18 further including a step of assessing balance and stability of a prosthetic component in view of the total load forces.

20. The method of claim 18 further including a step of measuring a transit time, frequency, or phase corresponding to length changes of the sensing assemblies