INTERVERTEBRAL FUSION REMOTE MONITORING DEVICE

Abstract

Disclosed is an invasive intervertebral fusion cage, the intervertebral fusion cage including: a vibration sensor; and a frame configured to support surrounding tissues used to create a bone fusion process; wherein the vibration sensor is integral with the frame in order to measure the mechanical vibrations the vibrations arising from the medium consisting of the frame, the surrounding tissues and/or the fusionned bone, and wherein the intervertebral fusion cage does not include a vibration excitation transducer. Also disclosed is a remote medical monitoring device including a receiver for receiving data from an intervertebral fusion cage, reflecting the mechanical vibrations of a medium and a calculator computing from the received data a medium indicator by: determining at least one vibration pattern of the received data; comparing the at least one vibration pattern with at least one reference model; generating a medium indicator in function of the comparing step.

Claims

1. An invasive intervertebral fusion cage (10), said intervertebral fusion cage (10) comprising: a) at least one vibration sensor (11); and b) a frame (13), configured to support surrounding tissues (20) used to create a bone fusion process; wherein the vibration sensor (11) is integral with the frame (13) in order to measure mechanical vibrations, said vibrations arising from the medium consisting of the frame (13), the surrounding tissues (20) and/or the fusionned bone, and wherein the intervertebral fusion cage does not comprise a vibration excitation transducer.

2. An intervertebral fusion cage (10) according to claim 1, wherein it comprises: a) a computer-readable data carrier storing data acquired by the vibration sensor; and b) a wireless interface for transmitting said stored data to an external device.

3. An intervertebral fusion cage (10) according to claim 1, wherein it is configured to be placed in an initial position between two vertebrae (L1, L2).

4. An intervertebral fusion cage (10) according to claim 1, wherein it comprises at least one or at least two hollow or empty holes (12) arranged to allow bone fusion process between the two vertebrae.

5. An intervertebral fusion cage (10) according to claim 1, wherein said intervertebral fusion cage comprises at least one support element to control the space between the two vertebrae.

6. An intervertebral fusion cage (10) according to claim 1, wherein said intervertebral fusion cage comprises only one sensor.

7. An intervertebral fusion cage (10) according to claim 1, wherein said intervertebral fusion cage comprises an accelerometer, or wherein the sensor is an accelerometer.

8. An intervertebral fusion cage (10) according to claim 1, further comprising a sensor actuator allowing the vibration sensor to emit mechanical or ultrasound waves when activated by said sensor actuator.

9. An intervertebral fusion cage (10) according to claim 1, further comprising an actuator wherein the vibration sensor information is used to control the said actuator allowing the emission of mechanical or ultrasound waves according to a closed loop or open loop control system.

10. A remote medical monitoring device comprising: a) a receiver for receiving data from an intervertebral fusion cage, reflecting the mechanical vibrations of a medium consisting of the frame, the surrounding tissues (20) and/or the fusionned bone; and b) a calculator computing from the received data a medium indicator (MI) by: i. determining at least one vibration pattern (VP) of said received data; ii. comparing said at least one vibration pattern (VP) with at least one reference model; iii. generating a medium indicator (MI) comprising: a data related to the progress of the bone fusion process; and/or a density of a bone; and/or a thickness of a bone layer; and/or a stiffness of a bone layer; and/or; a stiffness of the intervertebral fusion cage, said stiffness allowing deducing a physical integrity information of said cage.

11. The monitoring device according to claim 10, wherein the calculator generates an offset indicator of the migration of the intervertebral fusion cage.

12. The monitoring device according to claim 10, wherein it comprises a computer-readable data carrier storing data acquired by the receiver.

13. The monitoring device according to claim 10, wherein the reference model comprises: a) at least one reference vibration patterns; and/or b) an intervertebral fusion cage propagation model; and/or c) at least a vibration pattern previously determined.

14. A medical system comprising an intervertebral fusion cage (10) according to claim 1, and a medical monitoring device, the medical monitoring device comprising: a receiver for receiving data from an intervertebral fusion cage, reflecting the mechanical vibrations of a medium consisting of the frame, the surrounding tissues (20) and/or the fusionned bone; and a calculator computing from the received data a medium indicator (MI) by: i. determining at least one vibration pattern (VP) of said received data; ii. comparing said at least one vibration pattern (VP) with at least one reference model; iii. generating a medium indicator (MI) comprising: a data related to the progress of the bone fusion process; and/or a density of a bone; and/or a thickness of a bone layer; and/or a stiffness of a bone layer; and/or; a stiffness of the intervertebral fusion cage, said stiffness allowing deducing a physical integrity information of said cage; wherein the medical system comprises an interface which activates the transmission of vibration data measured into the intervertebral fusion cage in order to be received by the medical monitoring device.

15. A monitoring method for assessing the position of an intervertebral cage or monitoring a bone fusion comprising: a) receiving data from an intervertebral fusion cage, comprising a vibration sensor (11); and a frame (13) comprising at least two sides configured to support surrounding tissues (20) used to create a bone fusion process; wherein the vibration sensor (11) is arranged within the frame (13) in order to measure mechanical vibrations, said vibrations arising from the medium consisting of the frame, the surrounding tissues (20) and/or the fusionned bone, b) computing from the received data a medium indicator (MI) by determining at least one vibration pattern (VP) of said received data; comparing said at least one vibration pattern (VP) with a reference model; generating a medium indicator (MI) in function of the comparing step; c) displaying the medium indicator.

16. An intervertebral fusion cage (10) according to claim 2, wherein it is configured to be placed in an initial position between two vertebrae (L1, L2).

17. An intervertebral fusion cage (10) according to claim 2, wherein it comprises at least one or at least two hollow or empty holes (12) arranged to allow bone fusion process between the two vertebrae.

18. An intervertebral fusion cage (10) according to claim 3, wherein it comprises at least one or at least two hollow or empty holes (12) arranged to allow bone fusion process between the two vertebrae.

19. An intervertebral fusion cage (10) according to claim 2, wherein said intervertebral fusion cage comprises at least one support element to control the space between the two vertebrae.

20. An intervertebral fusion cage (10) according to claim 3, wherein said intervertebral fusion cage comprises at least one support element to control the space between the two vertebrae.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0212] FIG. 1 is a drawing of the intervertebral fusion cage according to one embodiment of the present invention.

[0213] FIG. 2 is a drawing of the intervertebral fusion cage according to one embodiment between two vertebrae.

[0214] FIG. 3 is a cross-sectional view of the intervertebral fusion cage between two vertebrae and surrounded internally and externally by a bone grafting material according to one embodiment of the present invention.

[0215] FIG. 4 is a cross-sectional view in the direction of the AA axis of the intervertebral fusion cage surrounded internally and externally by a bone grafting material.

[0216] FIG. 5 is a drawing of the intervertebral fusion cage according to one embodiment of the present invention between two vertebrae.

[0217] FIG. 6 is a graph of the vibration response measured by the vibration sensor in function of the frequency.

[0218] FIG. 7 is a graph of the frequency of the two resonant frequencies in function of the Young's Modulus of the bone grafting material.

[0219] FIG. 8 is a graph of the frequency of two resonant frequencies in function of the intervertebral fusion cage migration along the x-axis of FIG. 5.

[0220] FIG. 9 is a graph of the frequency of two resonant frequencies in function of the intervertebral fusion cage migration along the y-axis of FIG. 5.

[0221] FIG. 10 is a graph of a time history from an accelerometer signal embedded in the intervertebral fusion cage.

REFERENCES

[0222] 10Intervertebral fusion cage [0223] 11Vibration sensor [0224] 12Empty hole of the intervertebral fusion cage [0225] 13Frame [0226] 20Surrounding tissues [0227] L1Vertebrae [0228] L2Vertebrae [0229] F1First resonant frequency [0230] F2Second resonant frequency

EXAMPLES

[0231] The present invention is further illustrated by the following examples.

[0232] In said example, the vibration pattern chosen was the resonant frequency.

Example 1: Measuring of the at Least One Resonant Frequencies

[0233] Materials and Methods

[0234] Material

[0235] An intervertebral fusion cage according to the present invention is implemented in a simulator simulating vibration. The simulator allows generating vibrations which can occurred between the human vertebrae. In this example, the intervertebral fusion cage is externally and internally surrounded by a bone grafting material.

[0236] According to one setup, the bone grafting material Young's modulus has been set to 1 GPa, which corresponds to a fusion bone completion.

[0237] The migration of the implant has been set to 0 mm.

[0238] Methods

[0239] During the simulation, the frequencies and the vibration responses were measured by the vibration sensor.

[0240] Results

[0241] The vibration response measured is illustrated on FIG. 6. It can be seen that the vibration response of the bone grafting material is increased at two specific frequencies: around 4800 Hz (F2) and 3500 Hz (F1). For the other frequencies, the vibration response is sensibly the same for a spectrum of frequency from 2000 Hz to 5000 Hz.

[0242] The resonant frequencies are so 4800 Hz and 3500 Hz.

Example 2: Bone Fusion Process Impact on Resonant Frequencies

[0243] Materials and Methods

[0244] Material

[0245] A medical device according to the present invention was used in a simulator simulating vibration which can be caused between the human vertebrae.

[0246] Methods

[0247] The migration of the implant has been set to 0 mm.

[0248] The Young's modulus of the bone grafting material has been ranging from 50 MPa (no bone fusion) to 1000 MPa (fusion bone completion).

[0249] Results

[0250] The calculated resonant frequencies for each bone grafting material's Young's modulus are illustrated on FIG. 7. Both resonant frequencies increase with a progression of the fusion process. Both resonant frequencies could be considered for bone fusion monitoring.

Example 3: Cage Displacement Impact on Resonant Frequencies

[0251] Materials and Methods

[0252] Material

[0253] According to one example, a medical device according to the present invention is implemented in a simulator simulating vibrations. The vibrations generated are preferably in the same range of those caused between the human vertebrae.

[0254] Methods

[0255] The Young's modulus of the bone grafting material has been set to 50 MPa (no bone fusion).

[0256] The position of the implant has been moved from its initial position according to the x or they axis illustrated on FIG. 5.

[0257] Results

[0258] The calculated resonant frequencies when the cage has been displaced along the x axis are illustrated on FIG. 8 and the calculated resonant frequencies when the cage has been displaced along the y axis are illustrated on FIG. 9.

[0259] Both resonant frequencies present a sensitivity to a displacement of the implant in the x or y direction. After their implantation into the user body, when there is still no bone fusion, the present invention allows checking the position of the intervertebral fusion cage and calculating the migration of said intervertebral fusion cage around its initial position.

[0260] As it can see on FIGS. 8 and 9, the bone grafting material comprises two resonant frequencies. Both resonant frequencies have not the same evolution when the migration of the implant is varying. The resonant frequency F2 cannot be used to monitor the migration of the implant.

[0261] By using the two resonant frequencies F1 and F2, the medical monitoring system is able to calculate at least two indicators. The first indicator corresponds to the Young's modulus of medium related to the progress of the bone fusion process. The second indicator corresponds to the offset indicator of the intervertebral fusion cage.