US007182736 B2
`
`(12) United States Patent
`Roy et al.
`
`(10) Patent No.:
`(45) Date of Patent:
`
`US 7,182,736 B2
`*Feb. 27, 2007
`
`(54) APPARATUS AND METHOD FOR
`ASSESSING LOADS ON ADJACENT BONES
`
`(56)
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`(75) Inventors: Shuvo Roy, Cleveland, OH (US);
`Aaron J. Fleischman, University
`Heights, OH (US); Edward C. Benzel,
`Gates Mills, OH (US); Lisa Ferrara,
`Cleveland Heights, OH (US)
`(73) Assignee: Cleveland Clinic Foundation,
`Cleveland, OH (US)
`
`(*) Notice:
`
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 309 days.
`
`This patent is Subject to a terminal dis
`claimer.
`(21) Appl. No.: 10/769,823
`
`(22) Filed:
`
`Feb. 2, 2004
`
`(65)
`
`Prior Publication Data
`US 2004/O186396 A1
`Sep. 23, 2004
`Related U.S. Application Data
`(63) Continuation of application No. 09/939,331, filed on
`Aug. 24, 2001, now Pat. No. 6,706,005.
`(60) Provisional application No. 60/228,166, filed on Aug.
`25, 2000.
`
`(51) Int. Cl.
`(2006.01)
`A6B 5/7
`(2006.01)
`A6 IB 5/103
`(52) U.S. Cl. ...................................................... 600/587
`(58) Field of Classification Search ................ 600/587,
`600/594, 300; 435/174, 176, 177, 180, 181;
`436/518, 524,528,531; 424/178.1; 530/402,
`530/815, 810-812; 623/16, 17
`See application file for complete search history.
`
`
`
`28 J2
`
`6/1995 Kovacevic et al.
`5,425,775 A
`5,456,724 A 10, 1995 Yen et al.
`
`(Continued)
`
`OTHER PUBLICATIONS
`
`IEEE Transactions on Biomedical Engineering, vol. 47, No. 1, Jan.
`2000 “A Portable Microsystem-Based Telemetric Pressure and
`Temperature Measurement Unit', Bernd B. Flick and Reinhold
`Orgimeister.
`& 8
`Med. Eng. Phys. vol. 19, No. 6, pp. 539-549, 1997 Comparison of
`Loads on Internal Spinal Fixation Devices Measured in Vitro and in
`Vivo”. A. Rohlmann, G. Bergmann, F. Graichen and U. Weber.
`(Continued)
`Primary Examiner Max F. Hindenburg
`Assistant Examiner—Brian Szmal
`(74) Attorney, Agent, or Firm Tarolli, Sundheim, Covell &
`Tummino LLP
`
`(57)
`
`ABSTRACT
`
`An apparatus (10) that utilizes microelectromechanical sys
`tems (MEMS) technology to provide an in vivo assessment
`of loads on adjacent bones (24 and 26) comprises a body
`(34) for insertion between the adjacent bones. At least one
`sensor (42) is associated with the body (34). The sensor (42)
`generates an output signal in response to and indicative of a
`load being applied to the body (34) through the adjacent
`bones (24 and 26). A telemetric device (40) is operatively
`coupled with the sensor (42). The telemetric device (40) is
`operable to receive the output signal from the sensor (42)
`and to transmit an EMF signal dependent upon the output
`signal. According to various aspects of the invention, the
`sensor comprises a pressure sensor (42), a load cell (320),
`and/or at least one strain gauge (142).
`
`13 Claims, 8 Drawing Sheets
`
`Abbott
`Exhibit 1012
`Page 001
`
`

`

`US 7,182,736 B2
`Page 2
`
`U.S. PATENT DOCUMENTS
`Hershberger et al.
`Lesinski et al.
`Yuan et al.
`Keogh et al. ............... 435,174
`Elvin et al.
`Yuan et al.
`Perusek
`Simpson
`Ishikawa et al.
`Roy et al. ................... 600,594
`Guice et al. ................ 600/300
`
`11, 1995
`T. 1996
`12, 1998
`7, 1999
`3, 2000
`3, 2000
`5, 2000
`1, 2002
`9, 2002
`3, 2004
`1, 2002
`
`ck
`
`5,470,354
`5,531,787
`5,843,082
`5,925,552
`6,034,296
`6,036,693
`6,059,784
`6,342,074
`6,447,448
`6,706,005
`2002fOO 10390
`
`OTHER PUBLICATIONS
`Journal of Microelectromechanical Systems, vol. 9, No. 1, Mar.
`2000, A Miniature Pressure System With a Capacitive Sensor and a
`Passive Telemetry Link for Use in Implantable Applications,
`Stavros Chatzandroulis, Dimitris Tsoukalas and Peter A. Neukomm.
`“Introduction to MEMS, M. Mehrehany and S. Roy.
`Spine vol. 25, No. 20, pp. 2595-2600 “Real-Time in Vivo Loading
`in the Lumbar Spine” “Part 1. Interbody Implant: Load Cell Design
`and Preliminary Results”, Eric H. Ledet, MS, Barton L. Sachs, MD,
`John B. Brunski, PhD, Charles E. Gatto, MD, and Peter S. Donzelli,
`PhD.
`* cited by examiner
`
`Abbott
`Exhibit 1012
`Page 002
`
`

`

`U.S. Patent
`
`Feb. 27, 2007
`
`Sheet 1 of 8
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`US 7,182,736 B2
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`
`
`Fig.1
`
`Abbott
`Exhibit 1012
`Page 003
`
`

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`U.S. Patent
`
`Feb. 27, 2007
`
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`US 7,182,736 B2
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`Abbott
`Exhibit 1012
`Page 004
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`

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`U.S. Patent
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`Feb. 27, 2007
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`Sheet 3 of 8
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`US 7,182,736 B2
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`Abbott
`Exhibit 1012
`Page 005
`
`

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`U.S. Patent
`
`Feb. 27, 2007
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`Abbott
`Exhibit 1012
`Page 006
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`

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`U.S. Patent
`
`Feb. 27, 2007
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`Sheet S of 8
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`US 7,182,736 B2
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`Abbott
`Exhibit 1012
`Page 007
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`U.S. Patent
`
`Feb. 27, 2007
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`Sheet 6 of 8
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`US 7,182,736 B2
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`Abbott
`Exhibit 1012
`Page 008
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`Abbott
`Exhibit 1012
`Page 009
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`U.S. Patent
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`Feb. 27, 2007
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`Sheet 8 of 8
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`US 7,182,736 B2
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`
`Abbott
`Exhibit 1012
`Page 010
`
`

`

`1.
`APPARATUS AND METHOD FOR
`ASSESSING LOADS ON ADJACENT BONES
`
`US 7,182,736 B2
`
`RELATED APPLICATIONS
`
`This application is a continuation of U.S. patent applica
`tion Ser. No. 09/939,331, filed Aug. 24, 2001 now U.S. Pat.
`No. 6,706,005 which claims priority from U.S. Provisional
`Patent Application Ser. No. 60/228,166, filed on Aug. 25,
`2000, the subject matter of which is incorporated herein by
`reference.
`
`10
`
`TECHNICAL FIELD
`
`The present invention relates to an apparatus and method
`for assessing loads on adjacent bones, and is particularly
`directed to an apparatus and method for providing an in vivo
`assessment of loads on adjacent bones to be fused together.
`
`15
`
`BACKGROUND OF THE INVENTION
`
`25
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`30
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`45
`
`It is known to use Surgical procedures to stabilize a
`fractured bone or repair a problematic interaction of adjacent
`bones. For example, spinal Surgery is frequently performed
`to stabilize a problematic portion of the spine and relieve
`pain. Often, the vertebrae in the problematic portion of the
`spine are fused together with a bone graft in order to achieve
`the stabilization. Because the bone fusion takes time (six
`months or more on average), spinal implants (often referred
`to as fixation instrumentation). Such as rods, clamps, and
`plates, are typically implanted and used to secure the ver
`tebrae while the fusion of the bone graft takes place.
`During the months while the arthrodesis is occurring, it is
`desirable to monitor the progress of the bony incorporation,
`or bone-ingrowth, of the graft. Known methods for exam
`35
`ining the bony incorporation include radiographic evalua
`tion, magnetic resonance imaging, and computerized tomog
`raphy. All of these techniques provide a Snapshot of the
`progress of the bony incorporation, but do not provide
`accurate, continuous, real-time information to the patient
`40
`and physician. Without the ability to accurately and con
`tinuously assess the bony incorporation, pseudoarthrosis
`(non-healed bone fusion) may occur unbeknownst to the
`physician. Such pseudoarthrosis may cause post-operative
`pain for the patient and necessitate additional Surgery. If the
`fusion progress could be assessed continuously or on-de
`mand during the post-operative period by assessing the loads
`on the fixation instrumentation, it may be possible to appro
`priately time additional Surgery or even avoid additional
`Surgery.
`In a related manner, it is also desirable to assess the
`biomechanical performance of implanted spinal fixation
`instrumentation during the post-operative period while bone
`fusion is occurring. Both in vitro and in vivo biomechanical
`testing of fixation instrumentation has been done in the past,
`but with limited success. Current in vitro testing of fixation
`instrumentation typically subjects cadaveric vertebrae and
`implantable instrumentation to various axial and torsional
`loading parameters on a hydraulic testing apparatus. Unfor
`tunately, the use of non-living cadaveric tissue can introduce
`significant error into the test data.
`Previous attempts at in vivo biomechanical testing of
`spinal fixation instrumentation have been done primarily
`using animals (quadrapeds), but some limited testing has
`been done with humans. In one of the in vivo human tests
`performed to date, sensors that were placed on the implanted
`spinal instrumentation utilized wires to carry data percuta
`
`50
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`55
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`60
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`65
`
`2
`neously (through the skin) from the sensors to a data
`monitoring unit outside the human body. The use of wires or
`other type of electrical or optical connection extending
`through the skin provides a significant risk of infection and
`is not suitable for long-term testing as there is a high risk of
`wire breakage.
`Another problem encountered with the in vivo testing that
`has been done is failure of a sensor, Such as a strain gauge,
`or the sensor wiring which has been known to break,
`corrode, or debond within four months of in vivo implan
`tation. While attempts have been made to use telemetry to
`transmit data from sensors implanted in transcranial appli
`cations to an external monitoring device, a need exists for an
`implantable, telemetered sensor arrangement for spinal or
`other orthopedic applications that could survive a minimum
`of a year.
`Microelectromechanical systems, or MEMS, refers to a
`class of miniature electromechanical components and sys
`tems that are fabricated using techniques originally used in
`the fabrication of microelectronics. MEMS devices, such as
`pressure sensors and strain gauges, manufactured using
`microfabrication and micromachining techniques can
`exhibit Superior performance compared to their convention
`ally built counterparts and are resistant to failure due to
`corrosion, etc. Further, due to their extremely small size,
`MEMS devices can be utilized to perform functions in
`unique applications, such as the human body, that were not
`previously feasible using conventional devices.
`
`SUMMARY OF THE INVENTION
`
`The present invention is an apparatus for providing an in
`Vivo assessment of loads on adjacent bones. The apparatus
`comprises a body for insertion between the adjacent bones.
`At least one sensor is associated with the body. The at least
`one sensor generates an output signal in response to and
`indicative of a load being applied to the body through the
`adjacent bones. At least one telemetric device is operatively
`coupled with the at least one sensor. The least one telemetric
`device is operable to receive the output signal from the at
`least one sensor and to transmit an electromagnetic field
`(EMF) signal dependent upon the output signal.
`In accordance with one embodiment of the invention, the
`body comprises an implant for helping the adjacent bones to
`fuse together. The implant comprises a bone graft. In accor
`dance with another embodiment of the invention, the body
`comprises a fusion cage for insertion between an adjacent
`pair of vertebrae. In accordance with yet another embodi
`ment, the body comprises a prosthetic device for preserving
`motion between adjacent bones.
`According to various features of the invention, the at least
`one sensor comprises a pressure sensor, a load cell, and/or at
`least one strain gauge.
`According to another aspect of the present invention, an
`apparatus for providing an in vivo assessment of loads on
`adjacent bones comprises a body for insertion between the
`adjacent bones and sensor means for sensing a load being
`applied to the body through the adjacent bones. The sensor
`means generates a corresponding output signal in response
`to and indicative of a sensed load. First circuit means is
`operatively coupled with the sensor means for receiving the
`output signal from the sensor means. The first circuit means
`includes antenna means for receiving energy to power the
`first circuit means and the sensor means and for transmitting
`an EMF signal dependent upon the output signal.
`In according with another feature of the invention, the
`apparatus further comprises second circuit means for trans
`
`Abbott
`Exhibit 1012
`Page 011
`
`

`

`3
`mitting energy to power the first circuit means and the sensor
`means and for receiving the EMF signal. The second means
`is disposed remote from the first circuit means.
`According to yet another aspect of the present invention,
`an apparatus for providing an in vivo assessment of loads on
`and motion of one or more bones comprises a member for
`placement adjacent a bone and at least one sensor associated
`with the member. The at least one sensor generates an output
`signal in response to and indicative of a load being applied
`to the member through the bone. At least one telemetric
`device is operatively coupled with the at least one sensor.
`The at least one telemetric device is operable to receive the
`output signal from the at least one sensor and to transmit an
`EMF signal dependent upon the output signal.
`According to various embodiments of the present inven
`tion, the member comprises an implant for helping adjacent
`bones fuse together, such as a fusion cage, a fixation plate,
`and/or a bone graft. Alternatively, the member comprises a
`prosthetic device for preserving motion between adjacent
`bones.
`According to still another aspect of the present invention,
`an apparatus for providing an in vivo assessment of loads on
`and motion of one or more bones comprises at least one
`sensor attached to a bone. The at least one sensor generates
`an output signal in response to and indicative of a load on the
`bone. At least one telemetric device is operatively coupled
`with the at least one sensor. The at least one telemetric
`device is operable to receive the output signal from the at
`least one sensor and to transmit an EMF signal dependent
`upon the output signal.
`The present invention also provides a method for in vivo
`assessing the loads on adjacent bones to be fused together.
`According to the inventive method, a body for insertion
`between the adjacent bones is provided. The body is instru
`mented with at least one sensor for sensing a load on the
`body and for generating an output signal indicative of a
`sensed load. At least one telemetric device is operatively
`coupled with the at least one sensor to receive the output
`signal and to transmit an EMF signal dependent upon the
`output signal. The body is implanted between the adjacent
`bones. The EMF signal from the at least one telemetric
`device is then monitored.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`The foregoing and other features of the present invention
`will become apparent to those skilled in the art to which the
`present invention relates upon reading the following descrip
`tion with reference to the accompanying drawings, in which:
`FIG. 1 is a perspective view of a portion of a human spine
`illustrating an apparatus for providing an in vivo assessment
`of loads on adjacent bones in accordance with the present
`invention;
`FIG. 2 is a side view, taken in section, illustrating the
`apparatus of FIG. 1;
`FIG. 3 is a sectional view of a component of the apparatus
`shown in FIG. 2;
`FIG. 3A is a view similar to FIG. 3 illustrating an alternate
`construction of the component;
`FIG. 4 is a perspective view taken along line 4–4 in FIG.
`3:
`FIG. 5 is a plan view taken along line 5–5 in FIG. 3;
`FIG. 6 is a schematic block diagram of the apparatus for
`providing an in vivo assessment of loads on adjacent bones;
`FIG. 7 is a side view, similar to FIG. 2, illustrating an
`apparatus for providing an in vivo assessment of loads on
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`4
`adjacent bones constructed in accordance with a second
`embodiment of the present invention;
`FIG. 8 is a sectional view, similar to FIG. 3, showing a
`component of the apparatus of FIG. 7:
`FIG. 9 is a side view, similar to FIG. 2, illustrating an
`apparatus for providing an in vivo assessment of loads on
`adjacent bones constructed in accordance with a third
`embodiment of the present invention;
`FIG. 10 is a side view, similar to FIG. 2, illustrating an
`apparatus for providing an in vivo assessment of loads on
`adjacent bones constructed in accordance with a fourth
`embodiment of the present invention;
`FIG. 11 is a side view, similar to FIG. 2, illustrating an
`apparatus for providing an in vivo assessment of loads on
`adjacent bones constructed in accordance with a fifth
`embodiment of the present invention;
`FIG. 12 is a side view, similar to FIG. 2, illustrating an
`apparatus for providing an in vivo assessment of loads on
`adjacent bones constructed in accordance with a sixth
`embodiment of the present invention;
`FIG. 13 is a perspective view, similar to FIG. 1, of a
`portion of a human spine illustrating an apparatus for
`providing an in vivo assessment of loads on adjacent bones
`in accordance with a seventh embodiment of the present
`invention;
`FIG. 14 is an enlarged view illustrating a component of
`the apparatus of FIG. 13;
`FIG. 15 is a side view, similar to FIG. 2, illustrating an
`apparatus for providing an in vivo assessment of loads on
`adjacent bones constructed in accordance with an eighth
`embodiment of the present invention;
`FIG. 16 is a side view, similar to FIG. 2, illustrating an
`apparatus for providing an in vivo assessment of loads on
`adjacent bones constructed in accordance with a ninth
`embodiment of the present invention;
`FIG. 17 is a perspective view of a component of the
`apparatus of FIG. 16; and
`FIG. 18 is a schematic block diagram of another compo
`nent of the apparatus of FIG. 16.
`
`DESCRIPTION OF EMBODIMENTS
`
`The present invention relates to an apparatus and method
`for providing an in Vivo assessment of loads on adjacent
`bones. As representative of the present invention, FIG. 1
`illustrates several cervical vertebrae in a human spine and an
`apparatus 10 for providing an in vivo assessment of loads on
`adjacent cervical vertebrae to be fused together. It should be
`understood that the apparatus 10 could be used to assess
`loads and motion in other regions of the human spine.
`Further, it should also be understood that basic concept of
`the apparatus 10 could be used to assess loads on and motion
`of bones in other areas of the human body such as, for
`example, hip and knee joints, as well as loads on and motion
`of cartilage, muscles, ligaments, and tendons associated with
`various bones.
`Cervical vertebrae C2-C7, identified by reference num
`bers 20–30, respectively, are shown in FIG.1. A discectomy
`has been performed to remove a problematic intervertebral
`disc (not shown) between two vertebrae (indicated by ref
`erence numbers 24 and 26). The removal of the disc leaves
`an intervertebral space 32 (FIG. 2) between the vertebrae 24
`and 26. The intervertebral space 32 is to be filled with a body
`of bone graft material. In the illustrated embodiment, the
`body of bone graft material is an autograft 34 harvested from
`the patient undergoing the discectomy, but the body of bone
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`Abbott
`Exhibit 1012
`Page 012
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`5
`graft material could alternatively be an allograft, heterograft,
`or a graft made of a synthetic, biocompatible material.
`Prior to insertion of the autograft 34 into the space 34
`between the vertebrae 24 and 26, a small passage (not
`shown) is drilled into the cancellous bone in the interior of
`the autograft. A transducer assembly 40 placed into the
`interior of the autograft 34 through a small cannula (not
`shown). To place the transducer assembly 40 into the
`autograft 34, the transducer assembly is first loaded into one
`end of the cannula, and the end of the cannula is then
`inserted into the passage in the autograft. Morselized can
`cellous bone may also be placed into the cannula to protect
`the transducer assembly 40 and to assist in moving the
`transducer assembly from the end of the cannula into the
`interior of the autograft 34. Following placement of the
`transducer assembly 40 inside the autograft 34, the cannula
`is removed. The passage may then be filled with additional
`morselized cancellous bone to close and seal the passage.
`The transducer assembly 40 comprises a pressure sensor
`42 and a telemetric device 44. The transducer assembly 40
`is encased in a shell 46 made of a biocompatible metal. Such
`as titanium, or other Suitable biocompatible material. As
`may be seen in FIG. 3, a portion of the shell 46 has a recess
`48 defining a thin wall section 50 that is responsive to
`external pressure. Inside the shell 46, a pair of spacers 52
`separate the transducer assembly 40 from the shell.
`The illustrated pressure sensor 42 is of a known configu
`ration and is made using known micromachining processes,
`microfabrication processes, or other suitable MEMS fabri
`cation techniques. Pressure sensors of this type are com
`30
`mercially available from Motorola, Inc. of Schaumburg, Ill.
`and TRW Novasensor of Fremont, Calif. It should be
`understood that any pressure sensor that meets the biocom
`patibility and size requirements (less than two mm) may be
`used.
`The illustrated pressure sensor 42 is a piezoresistive
`device, but it should be understood that other types of
`pressure sensors. Such as a piezoelectric and capacitive
`sensors, could be substituted. As best seen in FIG. 4, the
`pressure sensor 42 comprises a Substrate 60, a sensing
`diaphragm 62, a plurality of patterned resistors 64, and a
`plurality of bond pads 66, two of which are associated with
`each of the resistors.
`The substrate 60 has upper and lower surfaces 67 and 68,
`respectively, and is made of silicon, but could alternatively
`be made of another suitable material. The substrate 60 has a
`well region 70 that extends between the upper and lower
`surfaces 67 and 68 and that is formed using a conventional
`microfabrication and bulk micromachining processes
`including lithography and etching. The sensing diaphragm
`62, which extends across the well region 70, is also made of
`silicon and is defined by the lithography and etching pro
`cesses. The resistors 64 and the bond pads 66 are formed
`from a metal layer that is deposited, patterned, and etched in
`a known manner on the lower surface 68 of the substrate 60.
`The resistors 64 could also be formed by doping the silicon
`using boron, phosphorus, arsenic, or another Suitable mate
`rial to make it highly conductive. The resistors 64 are
`positioned along the edges of the sensing diaphragm 62 to
`detect strain in the sensing diaphragm caused by pressure
`differentials.
`The telemetric device 44 in the transducer assembly 40
`comprise an electronics module 80 (FIG. 3) and an antenna
`82. The electronics module 80 is operatively coupled to the
`pressure sensor 42 by the bond pads 66 in a manner not
`shown. As shown in the block diagram of FIG. 6, the
`electronics module 80 comprises an integrated circuit. It is
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`contemplated that an application specific integrated circuit
`(ASIC) could be designed to incorporate the electronics
`module 80 and the antenna 82.
`The integrated circuit includes an RF-DC converter/
`modulator 84 and a voltage regulator 86 operatively coupled
`between the antenna 82 and the pressure sensor 42. The
`integrated circuit further includes a microprocessor 88
`operatively coupled between the pressure sensor 42 and the
`RF-DC converter/modulator 84. To protect the circuitry of
`the electronics module 80, the electronics module may be
`coated with a soft polymeric film, Such as parylene or
`polydimethylsiloxane (PDMS), or a biocompatible epoxy.
`The antenna 82 may be fabricated on the substrate of the
`pressure sensor 42 using known micromachining or micro
`fabrication techniques, or may alternatively be fabricated
`separately and joined with the pressure sensor. The antenna
`82 comprises a spiral-shaped coil 90 (FIG. 5) of metal
`deposited over an oxide layer 92 (FIG. 3). A layer of doped
`polysilicon 94 underneath the oxide layer establishes an
`electrical connection between a contact 96 in the center of
`the coil 90 and one of two contacts 98 outside the coil. The
`contacts 98 of the antenna 82 outside of the coil 90 are
`operatively coupled with the electronics module 80 in a
`manner not shown. For protection purposes, the antenna 82
`may be coated with a soft polymeric film, Such as parylene
`or PDMS, or a biocompatible epoxy.
`Before the shell 46 of the transducer assembly 40 is sealed
`shut, in a manner not shown, to encapsulate the transducer
`assembly, the interior of the shell is filled with a silicone gel
`100, sol-gel, or other suitable material that is dielectric and
`biocompatible. The properties of the gel 100 allow it to
`transmit pressure exerted against the thin section 50 of the
`shell 46 uniformly against the sensing diaphragm 62 of the
`pressure sensor 42, while isolating the electrical components
`and circuitry of the transducer assembly 40 from any cor
`rosive media.
`The shell 46 containing the transducer assembly 40 is then
`packaged within a biomolecular coating 102. Exposing the
`shell 46 to solutions containing desired biomolecules, such
`as collagen or hyaluronan, leads to monolayer coating of the
`outer surface of the shell 46. Alternatively, the outer surfaces
`of the shell 46 may be coated with thin layers of a soft
`biocompatible material, such as parylene or PDMS.
`FIG. 3A illustrates an alternate configuration for the
`transducer assembly 40, indicated by the suffix “a”. The
`difference between the transducer assembly 40 of FIG.3 and
`the transducer assembly 4.0a of FIG. 3A is that the shell 46
`has been omitted. The transducer assembly 40a is simply
`coated with a biocompatible polymeric film 104, such as
`parylene or PDMS, or a biocompatible epoxy. The trans
`ducer assembly may then also packaged within a biomo
`lecular coating 102a, as described above.
`Returning now to the first embodiment of the present
`invention, when the transducer assembly 40 is positioned
`inside the autograft 34 as described above, the autograft is
`ready to be inserted into the intervertebral space 32 between
`the vertebrae 24 and 26. Insertion of the autograft 34 into the
`intervertebral space 32 involves a distraction procedure
`known in the art.
`After the autograft 34 has been inserted between the
`vertebrae 24 and 26, a spinal fixation implant 120 (FIG. 1)
`is connected to the cervical vertebrae 22, 24, and 28 to
`stabilize the vertebrae 20–30 while the autograft 34 fuses the
`adjacent vertebrae 24 and 26 together. According to the
`illustrated embodiment, the implant 120 comprises a modi
`fied version of the DOCTM Ventral Cervical Stabilization
`System (hereinafter referred to as the “DOCTM system
`
`Abbott
`Exhibit 1012
`Page 013
`
`

`

`US 7,182,736 B2
`
`10
`
`15
`
`7
`122), available from the DePuy/AcroMed division of
`Johnson & Johnson, described in U.S. Pat. Nos. 5,843,082
`and 6,036,693. It should, however, be understood that the
`implant 120 could be any type of implanted orthopedic
`instrumentation or device.
`The DOCTM system 122 includes a plurality of plates 124
`that are anchored to the vertebrae by screws 126 and
`interconnected by first and second rods 128 and 130. A
`platform 132 also extends between the rods 128 and 130 and
`is secured to the rods by setscrews 134. The platform 132 is
`positioned over the inserted autograft 34.
`A second transducer assembly 140, comprising a plurality
`of strain gauges 142 and a second telemetric device 144, is
`mounted to the DOCTM system. The second telemetric
`device 144 is constructed like the telemetric device
`described above and comprises a second electronics module
`146 and a second antenna 148, both of which are shown only
`schematically in FIG. 2. The second electronics module 146
`is located on a first side of the platform 132 facing toward
`the autograft 34, while the second antenna 148 is located on
`an oppositely disposed second side of the platform 132.
`The second electronics module 146 has the basic con
`struction as the electronics module 80 in the transducer
`assembly 40 illustrated in FIG. 6. The second electronics
`module 146 comprises an integrated circuit that is opera
`tively coupled to the second antenna 148 on the second side
`of the platform 132 in manner not shown. To protect its
`circuitry, the second electronics module 146 may be coated
`with a soft polymeric film, such as parylene or PDMS, or a
`biocompatible epoxy.
`As may be seen in FIG. 1, the second antenna 148 is larger
`in overall size than the antenna 82 in the transducer assem
`bly 40, but has the same basic configuration and construc
`tion. The second antenna 148 may be fabricated using
`known MEMS fabrication or micromachining techniques, or
`any other conventional microelectronic fabrication process.
`The second antenna 148 comprises a spiral-shaped coil of
`metal deposited over an oxide layer. A layer of doped
`polysilicon underneath the oxide player establishes an elec
`trical connection between a contact in the center of the coil
`and a contact outside the coil. For protection purposes, the
`antenna 82 may be coated with a soft polymeric film, such
`as parylene or PDMS, or a biocompatible epoxy.
`In accordance with the apparatus 10, the first and second
`rods 128 and 130 of the DOCTM system 122 are instru
`mented with the plurality of strain gauges 142. The Strain
`gauges 142 may be commercially available devices, such as
`those produced by microelectronics Suppliers such as Vishay
`Inc. and MicroMeasurements Inc., or may be custom-fab
`ricated by a foundry. Two of the strain gauges 142 are
`secured to the first rod 128 above and below, respectively,
`the platform 132. The strain gauges 142 are operatively
`coupled to the second electronics module 146 by electrical
`leads in the form of metal traces 150 deposited on the
`Surface of an insulating film (not shown) covering the first
`rod 128 and the side of the platform 132. Alternatively, the
`electrical ends could be insulated wires threaded through the
`inside of the rod 128 to make contact. For protection
`purposes, the strain gauges 142 and the electrical traces 150
`may be coated with a soft polymeric film, Such as parylene
`or PDMS, a biocompatible epoxy, or a monolayer of bio
`molecular coating.
`Similarly, another two strain gauges 142 are secured to the
`second rod 130 above and below, respectively, the platform
`132. These two strain gauges 142 are also operatively
`coupled to the second electronics module 146 by electrical
`leads in the form of metal traces 150 deposited on the
`
`8
`surface of the second rod 130 and the side of the platform
`132. Again, the Strain gauges 142 and the electrical traces
`150 associated with the second rod 130 may be coated with
`a soft polymeric film, such as parylene or PDMS, or a
`biocompatible epoxy.
`The apparatus 10 further includes an external (meaning it
`is located outside of and/or remote from the patient’s body)
`readout/power supply unit 160 (FIG. 6) having an integrated
`antenna 162. The readout/power supply unit 160 contains
`circuitry known in the art and therefore not described in any
`detail. The readout/power supply unit 160 may be a hand
`held device or a larger piece of equipment found at a
`physicians office. The readout/power supply unit 160 could
`also be a device worn by the patient.
`The readout/power supply unit 160 is operable to transmit
`electrical energy and receive data through the antenna 162 as
`described further below. Further, the readout/power supply
`unit 160 is able to display and store the received data.
`Following implantation of the instrumented autograft 34
`and the instrumented DOCTM system 122 into the spine as
`described above, the apparatus 10 can be used to provide an
`in vivo assessment of the bony incorporation of the
`autograft, and thus the fusion of the autograft and the
`vertebrae 24 and 26, as well as the biomechanical perfor
`mance of the DOCTM system. The readout/power supply unit
`160 transmits electrical energy in the form of an electro
`magnetic field (EMF) signal, or more specifically a radio
`frequency (RF) signal, through the ante