Prosthetic component for monitoring synovial fluid and method

• US 8,707,782 B2
• Filed: 02/27/2012
• Issued: 04/29/2014
• 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, Chase, Andrew U., Henson, Philip, Burkhard, Natalie, Keggi, John, Bonnheim, Noah
• Primary Examiner(s): THOMPSON, JEWEL VERGIE
• Application Number:
  US13/406,523
• Publication Number:
  US 20120220839A1
• Time in Patent Office: 792 Days
• Field of Search: 733/790.1, 606/102, 600/424
• US Class Current: 73/379.01
• CPC Class Codes: A61B 5/14507 specially adapted for measuring characteristics of body fluids other than blood devices for taking samples of body liquids A61B10/0045
• CPC Class Codes: A61B 5/1455 using optical sensors, e.g. spectral photometrical oximeters
• 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

Abstract

A prosthetic component suitable for long-term implantation is provided. The prosthetic component includes electronic circuitry and sensors to measure a parameter of the muscular-skeletal system. The prosthetic component comprises a first structure having at least one support surface, a second structure having at least one feature configured to couple to bone, and at least one sensor. The electronic circuitry and sensors are hermetically sealed within the prosthetic component. One or more sensors can be used to monitor synovial fluid in proximity to the joint to determine joint health. The prosthetic component includes a transmissive region. One or more optical sensors are mounted in proximity to the transmissive region. Periodic measurements of the synovial fluid are measured through the transmissive region. The measurements can include color and turbidity of the synovial fluid. The color and turbidity data can be compared against known data to determine joint status.

Claims

1. A prosthetic component comprising:

at least one optical sensor; and

electronic circuitry coupled to the optical sensor where the electronic circuitry is housed in the prosthetic component and where the at least one optical sensor and electronic circuitry is configured to monitor synovial fluid in proximity to the prosthetic component.

2. The prosthetic component of claim 1 where the at least one optical sensor comprises:

at least one light emitting diode; and

a photo-diode array.

3. The prosthetic component of claim 2 where light from the light emitting diode is configured to be received by a photo-diode.

4. The prosthetic component of claim 3 where light from the light emitting diode is configured to illuminate synovial fluid in proximity to the prosthetic component.

5. The prosthetic component of claim 1 where the optical sensor is configured to measure color of synovial fluid.

6. The prosthetic component of claim 5 where the optical sensor is configured to measure a relative contribution of red, green, and blue colors.

7. The prosthetic component of claim 6 where the optical sensor is configured to ratiometrically compare each color contribution with a sum of a calibration value.

8. The prosthetic component of claim 1 where the optical sensor is configured to measure turbidity of synovial fluid.

9. The prosthetic component of claim 5 where the optical sensor is configured to ratiometrically compare a sum of relative contribution of red, green, and blue colors to three times the calibration value.

10. A method of long-term joint monitoring comprising the steps of:

housing electronic circuitry and one or more sensors in a prosthetic component;

periodically measuring a characteristic of synovial fluid in proximity to the prosthetic component; and

comparing measurements of the synovial fluid.

11. The method of claim 10 further including a step of measuring a color of the synovial fluid.

12. The method of claim 11 further including the steps of:

comparing the color of the synovial fluid to a known color range; and

determining if an infection is present.

13. The method of claim 12 further including the steps of:

measuring the relative contributions of red, green, and blue colors; and

ratiometrically comparing each color contribution to a sum of the relative contributions.

14. The method of claim 12 further including a step of determining a rate of change in color.

15. The method of claim 12 further including a step of measuring temperature or pH.

16. A method of long-term joint monitoring comprising the steps of:

housing electronic circuitry and one or more sensors in a prosthetic component; and

periodically measuring turbidity of synovial fluid in proximity to the prosthetic component.

17. The method of claim 16 further including the steps of:

comparing the turbidity of the synovial fluid to a predetermined turbidity range; and

determining if an infection is present.

18. The method of claim 17 further including the steps of:

comparing the turbidity to previous turbidity measurements; and

determining a rate of change in turbidity.

19. The method of claim 18 further including a step of wirelessly transmitting data to a remote system.

20. The method of claim 19 further including a step of receiving light through a transmissive region of the prosthetic component.