IDENTIFICATION AND LOCATING TRANSPONDER FOR IMPLANTS

Abstract: A passive transponder (28) may be encoded with a binary number or code of 64 bits or more and then associated with or mounted to virtually any implant intended for implantation in a human including temporary implants such as drug release implants (130) and organ displacement devices (134). After implantation, the transponder's code may be conveniently read with a hand-held electromagnetic reader (34) which may merely be brought within proximity of the transponder (28). The encoded transponder (28) may thus be read in a non-invasive procedure and without the use of any sophisticated or potentially harmful medical equipment or technology such as X-rays. Where the position of the implant in the human changes over time, or is otherwise unknown to attending medical personnel, the transponder and implant can be located by using a strength of signal indicator on the electromagnetic reader (34). The information encoded in the transponder may simply be a tag for locating the implant, or may correspond to patient demographics and implant data to aid in tracking the implant and patient for medical as well as legal reasons.

Description: IDENTIFICATION AND LOCATING TRANSPONDER FOR IMPLANTS Cross Reference to Related Applications This application is a continuation-in-part of copending application Serial No. 08/375,811 filed on 01/20/95, which is a continuation-in-part of: Serial No. 07/938,833 filed on 08/31/92; and Serial No. 08/221,706 filed on 04/01/94, which is a continuation of Serial No. 934,785 filed 08/24/92, now U.S. Patent No. 5,300,120. The disclosures of all of the foregoing are incorporated herein by reference. Background and Summary of the Invention With the advance of medical technology, there are a number of medical prostheses and devices which are im- plantable in humans for re-constructive and/or cosmetic purposes. These include breast implants; penile im- plants; musculature and other soft tissue implants; pace makers; valves; artificial joints and limbs such as knees, shoulders, legs, fingers, etc.; pins; screws; plates; rods; nails and other braces and supports. In order to ensure the continued safety and health of pa- tients receiving these implants, the Safe Medical Device Act of 1990 has been enacted which dictates that manufac¬ turers of Class III implantable medical devices institute a device registry for tracking of their devices, notifi¬ cation of patients, and otherwise monitoring these im- plants after they have been placed in a patient. Compli¬ ance with this Act has been proposed through a method of tracking which requires the surgeon who implants the device to complete and return a form or card with patient demographic data and implant data to the manufacturer or to a third party registry service. This method requires careful accumulation of data by a surgeon or his staff as well as secure inventory control procedures in order to ensure that the data is properly associated with the correct implant. Additionally, there is a risk of loss of the data entirely resulting from misdirected or lost communications. Furthermore, access to this data can be impeded in the event of an emergency situation or other circumstances which interfere with a patient's ability to recall or report the proper information which medical personnel may then use to access the registry and data contained therein. The issues described above with respect to more permanent types of medical prosthesis and devices are very similar for devices temporarily implanted for therapeutic and other purposes, including drug release implants and organ displacement devices. An example of a drug release implant is an implant for releasing a birth control drug over a period of time, such as six months or a year. An organ displacement device is a device which is implanted into a patient, either before or after the device has been inflated with a filler material, to separate healthy organs from diseased or otherwise afflicted organs which are undergoing therapeutic treatment, such as radiation therapy. As with permanently implanted medical prosthesis and devices, temporary implants are subject to rejection, infection, and a host of other medical complications. For temporary implant patients, the ready availability of information relating to the temporary implant and the medical procedure utilized would be very helpful in treating the patient as well as in tracking and monitoring the patients progress. In emergency situations, access to this data may well be critical to proper diagnosis and treatment, especially if a disorder relating to the temporary implant is what causes the medical emergency. There have been some suggestions in the prior art of marking the implants themselves with, for example, a radiopaque marker or other marker which contains the information relating to the implant. Ideally, this data could then be viewable by X-ray or some other non-inva- sive manner. However, there are difficulties with these prior art approaches. First of all, a breast implant with a radiopaque marker would at least partially obscure or mask tissue which is desired to be viewed in order to detect artifacts relating to tumors or the like for diag¬ nosing cancer. Obviously, this is highly undesirable as the incidence of breast cancer presents a significant risk to many females. Additionally, repeated exposure to X-ray is not generally considered healthful or desirable and represents at least an added inconvenience entailing some degree of expense to recall or access the implant data. Therefore, radiopaque markers have not been viewed as a suitable long-term solution to this problem. In order to solve these and other problems in the prior art, and in order to provide a convenient, fool proof marker associated with or secured to the implant itself, and yet readable in a non-invasive manner, the inventors herein have succeeded in designing and developing an implant which incorporates a passive transponder which may be encoded and subsequently accessed with a hand held electromagnetic reader in a quick and inexpensive procedure. The passive transponder may be secured to the implant by any convenient means. For example, in a breast implant, the multi-layered shell for the implant may be laminated around the transponder to thereby be permanently and securely fixed to the implant. The transponder may be laminated in the sidewall of the shell, or between layers which comprise the seal patch which is applied to the shell to seal the mandrel opening. Similarly, the transponder may be laminated onto the surface of most other implants in an unobtrusive location. In some other implants, the transponder may be inserted into a hole or inlay and sealed in place. Other acceptable methodologies for associating the transponder with the implant include utilizing a non-absorbable "string and basket" tether or by locating the transponder according to an "adjacent site" standard. This adjacent site may be in very close proximity to the implant or in a standardized location that may be device specific. As passive transponders are commercially available in a cylindrical shape sized at 2 mm in diameter and 11 mm in length, the patient will not sense any discom¬ fort or even the presence of the transponder. Also, the transponder may be encoded with any suitable encoding scheme. A commercially available transponder presently provides for the storage of up to 64 binary bits of data. This data capacity may accommodate the direct storage of much, if not all, of the information desired to be re¬ corded and maintained in a device registry. Furthermore, the storage capacity of the transponder is expected to be increased as further development occurs over time. Al¬ ternately, a number, collection of numbers, combination of numbers and letters, or other indirect code may be stored which after reading may be used to access a data bank which itself contains the desired information. Of course, if information is directly stored in the implant, it becomes immediately available upon reading the tran¬ sponder. This provides ready access to information in emergency situations. However, with the widespread availability, accessibility, and use of computers over telecommunications networks including telephone lines, it is not generally considered to be unduly limiting to provide that the code read from the transponder be then used to access an appropriate data bank in order to ob- tain the patient demographics, manufacturer's name, date of manufacture, surgeon's name, date of implantation, etc. A companion hand held electromagnetic reader is also commercially available which emits a low frequency magnetic field to activate the passive transponder and thereby cause it to transmit its encoded data to the reader. With this particular commercial device, no bat¬ tery or other source of electrical power need be included in the passive transponder. This further reduces the size required for the transponder and renders it particu- larly suitable to this application. Moreover, in the case of implants that are susceptible to movement within the patient over a period of time, or where the attending medical personnel are uncertain as to the position of the implant within the patient's body, the electromagnetic reader can be utilized for locating the transponder and implant by monitoring the strength of signal indicator provided with the reader. While the principal advantages and features of the present invention have been described above, a more com- plete and thorough understanding of the invention may be attained by referring to the drawings and description of the preferred embodiment which follow. Brief Description of the Drawings Figure 1 is a perspective view of a breast implant containing a passive transponder with a hand held reader in position to read the encoded data contained therein; Figure 2 is a partial cross-sectional view of the transponder as laminated between the multiple layers of a seal patch for a breast implant; Figure 3 is a perspective view of a pectoralis muscle implant with a passive transponder mounted there- in; Figure 4 is a perspective view of a soft chin im¬ plant with passive transponder mounted therein; Figure 5 is a perspective view of a rigid chin implant with a passive transponder mounted therein; Figure 6 is a perspective view of a nipple trans¬ plant with a passive transponder mounted therein; Figure 7 is a perspective view of an otoplasty implant with a passive transponder mounted therein; Figure 8 is a perspective view of a penile im- plant, surgically implanted, with a passive transponder mounted therein; Figure 9 is a top view of a pace maker with a pas¬ sive transponder mounted thereon; Figure 10 is a top view of a heart valve with a passive transponder mounted to the edge thereof; Figure 11 is a perspective view of a total knee joint prosthesis with a passive transponder mounted thereon; Figure 12 is a perspective view of a shoulder ar- throplasty system with a passive transponder mounted therein; Figure 13 is a partial cross-sectional view of a passive transponder inlaid into and below the surface of an implant; Figure 14 is a perspective view of a femoral fixa¬ tion system implanted in a femur with a passive trans¬ ponder mounted thereto; Figure 15 is a perspective view of an orthopedic nailing system with a passive transponder mounted there¬ in; Figure 16 is a perspective view of a finger joint prosthesis with a passive transponder mounted therein; Figure 17 is a perspective view of a craniomaxil- lofacial plating system with a passive transponder mount¬ ed therein; Figure 18 is a perspective view of still another plating system with a passive transponder mounted there¬ in; Figure 19 is a partial cross-sectional view of a typical implant with a passive transponder mounted within a cored hole drilled therein; Figure 20 is a perspective view of a drug release implant with a passive transponder affixed thereto; and Figure 21 is a partially cutaway view of an organ displacement device with a passive transponder mounted therein. Detailed Description of the Preferred Embodiment As shown in Figure 1, a breast implant 20 has been implanted in a female's breast 22 and includes a silicone shell 24 inflated with an appropriate fill material 26. At the posterior side of the implant 20 is shown the transponder 28 which has been laminated between adjacent layers 30, 32 of the shell 24. Transponder 28 may be any passive transponder such as a Trovan Model ID100 avail¬ able from Electronic Identification Systems Ltd. of Santa Barbara, California. This particular transponder is designed to be environmentally independent and suitable for operation while being directly submerged in liquids. Furthermore, it may be read spherically from any direc- tion through most materials, and including most impor¬ tantly those materials comprising implants for the human body. The transponder may be directly encoded with 64 binary bits or more of data to provide almost one tril- lion possible different code combinations. The limit of data recorded is a function of the further progress and development of electronic memory technology. It is anticipated that FDA approval will be forthcoming for its use as part of the invention disclosed and claimed herein. A hand held reader 34 is also shown in Figure 1 and may be a Trovan Model LID500, or other suitable de¬ vice. Its principle of operation includes emitting a low frequency magnetic field for activating the passive tran- sponder 28. As such, transponder 28 has no power source and instead derives the energy needed for its operation from the magnetic field generated by the reader 34. This permits the transponder 28 to have a virtually unlimited life span. The hand held reader 34 is shown connected to a decoder controller 36 which accesses a data bank 38 in response to the detected code contained within transpond¬ er 28 to thereby access such data which has been stored corresponding to transponder 28. Alternately, as men¬ tioned above, the hand held reader 34 may be used to ac- cess the code contained within transponder 28 and then other means used to access a data bank for the retrieval of the desired information. Such means might include the use of a telephone and modem to access a registry con¬ tained in a geographically centrally located site. As shown in Figure 2, the transponder 28 may be laminated between adjacent layers 40, 42 of the seal patch 44 which is commonly used to seal the mandrel open¬ ing 46 in a shell 48 of a breast implant 50. For other implants, convenient mounting locations may be readily determined with due consideration given to avoiding dis- comfort to the patient as well as optimizing readability of the transponder with the hand held reader. As shown in Figure 3, a pectoralis muscle implant 52 may conveniently have a passive transponder 54 con- tained therein. The passive transponder 54 may be molded in place, or a hole or inlay drilled for placement of the implant, after which the implant surface may then be refinished. As shown in Figures 4 and 5, a soft chin implant 56 or a hard chin implant 58 may also have a passive transponder 60, 62 mounted therein. As shown in Figure 6, a nipple implant 64 has a passive transponder 66 mounted internally. In all of these transplants, the mounting of the passive transponder is achieved to pro- vide minimal discomfort or sensation to the patient, as well as to avoid interference with the cosmetic appear¬ ance of the implant. As shown in Figure 7, an otoplasty implant 68 may have a passive transponder 70 mounted therein. As shown in Figure 8, a penile implant 72 may have a passive transponder 74 mounted therein. As shown in Figure 9, a pace maker 76 may also have a passive transponder 78 mounted either on its sur¬ face or below the protective metal casing thereof. The inventors have found that reading of the passive tran- sponder by the hand held reader may be achieved even when the transponder is obscured by metallic surfaces. As shown in Figure 10, a heart valve 80 may have a passive transponder 82 mounted to its edge in order to avoid interference with the operability thereof, or fixation thereof. As shown in Figures 11 and 12, a total knee joint prosthesis 84 or a shoulder prosthesis 86, either one of which includes a majority of parts made from titanium or the like, may also conveniently carry a passive trans- ponder 88, 90. As shown in Figure 13, the passive transponder 92 may be placed within a trough 94 or the like and covered with a sealant 96 so that the surface of the transponder 98 is uninterrupted and smooth as is desirable in many transponders. As shown in Figures 14 and 15, a femoral fixation implant 100, or an orthopedic nailing system 102 may conveniently have a passive transponder 104, 106 inlaid therein. As shown in Figure 16, a finger joint prosthe- sis 108 may also have a passive transponder 110 located in a position which does not interfere with the movable joint portion 112 of the prosthesis 108. As shown in Figures 17 and 18, a craniomaxillofacial plating system 114 or any other plating system 116 may also conveniently include a passive transponder 118, 120. As an alterna¬ tive to the inlay mounting shown in Figure 13, a hole 122 may be drilled in any convenient location of an implant 124 and the passive transponder 126 inserted therein and sealed in place by sealer 128, with the outer surface of sealer 128 being finished to provide a smooth surface on implant 124, as shown in Figure 19. A passive transponder may also be utilized with implants intended for temporary implantation in humans including, but not limited to, drug release implants and organ displacement devices. As shown in Figure 20, a drug release implant 130 may have a transponder 132 mounted thereto in such a manner that transponder 132 does not interfere with the controlled release of a drug from the implant 130. The transponder 132 may contain a code relating to information such as the date of implantation, the type of drug contained in the implant 130, and the date when the implant 130 should be removed or replaced. As shown in Figure 21, an organ displacement device 134 may have a passive transponder 136 affixed to the interior surface of the device such that the transponder 136 does not interfere with the inflation or deflation of the organ displacement device 134, or with the therapeutic process for which the device 134 is being used. In this case, the passive transponder 136 may contain a code relating to information such as the date of implantation and the particular type of organ displacement device, as well as information pertaining to the history of the therapy undergone by the patient in which the organ displacement device is implanted. Although all of the implants mentioned above have been described as having a passive transponder mounted to the interior or the exterior of the particular device, other acceptable methodologies for associating the transponder with the implants are available. Examples of these alternative methods include utilizing a non- absorbable string and basket tether or by locating the transponder according to an adjacent site standard. In the case of utilizing the adjacent site standard, the site may be in close proximity to the implant or in a standardized location that may be device specific. In addition to utilizing a passive transponder in conjunction with an implant to identify the particular implant and retrieve data relating to the implant and patient, the passive transponder can also be utilized to locate the particular implant in cases where the implant is susceptible to movement within the patient's body over a period of time, or where the attending medical personnel are otherwise uncertain as to the position of the implant within the patient's body. For example, where a drug release implant is implanted into a patient for several months or years, the implant may move from the position in the patient's body where the implant was originally placed. Hence, the particular location of the implant must be ascertained before the implant can be removed. Similarly, an organ displacement device may be susceptible to movement within a patient's body during the period of time between successive therapeutic treatments. Because these devices may be inflated in situ after implantation but prior to a therapeutic treatment, and then deflated thereafter, the precise location of the organ displacement device, as well as an inflation/deflation valve associated therewith, must be ascertained prior to performing these procedures, as well as prior to removal of the device. In these cases, the passive transponder associated with an implant can be utilized to locate the specific position of the implant in the patient's body. By utilizing an electromagnetic reader having a strength-of- signal meter, the reader can be used to externally scan over a portion of the patient's body where the implant is generally expected to be located. By referring to the strength-of-signal meter on the electromagnetic reader, the specific location of the implant can be ascertained. This specific location will correspond to the location on the patient's body where the electromagnetic reader generated the strongest read signal. In other words, as the electromagnetic reader approaches the external position of the body that corresponds to the internal location of the implant and transponder, the strength of the read signals generated by the electromagnetic reader, and indicated thereon, will increase. As the reader moves away from this external position of the body, the strength of the read signals will decrease. In this manner, the electromagnetic reader and transponder can be utilized to find an implant. Where the transponder is used in this manner for the purpose of subsequently locating the position of the implant in the patient's body, the transponder may be encoded with a simple code or tag solely for this purpose, or may additionally be encoded to identify particular information about the implant and patient, as described above. As disclosed herein, a wide variety of implants made of all sorts of material may conveniently include a passive transponder which may be implanted, and then read by the hand held reader. This compatibility and ease of operation permits the use of a passive transponder with virtually any implant. The inventors have disclosed herein a representative sample of such implants. Howev¬ er, the scope of the present invention is broad enough to encompass any implant presently known to the inventors herein. There are various changes and modifications which may be made to the invention as would be apparent to those skilled in the art. However, these changes or modifications are included in the teaching of the disclo¬ sure, and it is intended that the invention be limited only by the scope of the claims appended hereto.

Claims: What Is Claimed Is: 1. An implant intended for temporary human implantation, said implant including a transponder associated therewith so that said transponder is im¬ planted as said implant is implanted, said transponder having means for being encoded with a unique identifier so that said transponder may be readily identified after implantation by reading said unique identifier. 2. The implant of Claim 1 wherein said tran¬ sponder has means for its unique identifier to be read with a non-invasive protocol. 3. The implant of Claim 2 wherein said tran¬ sponder has means for its unique identifier to be read electromagnetically. 4. The implant of Claim 3 wherein said tran¬ sponder has means for being energized by a remote reader thereby obviating a need for a battery to be contained in said transponder. 5. The implant of Claim 1 wherein said unique identifier is a binary number having up to 64 bits. 6. The implant of Claim 1 wherein said implant is a drug release implant. 7. The implant of Claim 1 wherein said implant is an organ displacement device. 8. The implant of Claim 1 wherein said tran¬ sponder is mounted to said implant. 9. An implant intended for temporary human implantation, said implant including a transponder associated therewith so that said transponder is implanted as said implant is implanted, said transponder having means for being encoded with a tag so that said tag may be read after implantation to locate said transponder. 10. The implant of Claim 9 wherein said tran¬ sponder has means for its tag to be read remotely. 11. The implant of Claim 10 wherein said tran¬ sponder has means for its tag to be read electro¬ magnetically. 12. The implant of Claim 11 wherein said tran¬ sponder has means for being energized by a remote reader thereby obviating a need for a battery to be contained in said transponder. 13. The implant of Claim 10 wherein said tag is a unique tag so that said transponder may be readily identified after implantation by reading said tag. 14. The implant of Claim 9 wherein said tran¬ sponder is mounted to said implant. 15. The implant of Claim 9 wherein said tag is a binary number. 16. The implant of Claim 15 wherein said binary number corresponds to a profile of data contained in an external data base. 17. The implant of Claim 9 wherein said implant is a drug release implant. 18. The implant of Claim 9 wherein said implant is an organ displacement device. 19. A method for identifying an implant adapted for temporary implantation in a human, said method comprising the steps of: associating a transponder with said implant; encoding said transponder with a unique tag so that said transponder may be readily identified; and contemporaneously implanting said implant and said transponder in a human. 20. The method of Claim 19 wherein the step of associating includes the step of physically securing said transponder to said implant so that said implant and transponder are implanted in physical proximity with each other. 21. The method of Claim 19 wherein the step of associating includes the step of affixing said transponder to said implant. 22. A method for locating an implant adapted for implantation in a human, said method comprising the steps of: associating a transponder with said implant; encoding said transponder with a tag so that said tag may be read to locate said transponder; and implanting said implant and said transponder in a human. 23. The method of Claim 22 wherein the step of- associating includes the step of physically securing said transponder to said implant so that said implant and transponder are implanted in physical proximity with each other. 24. The method of Claim 22, further comprising the steps of: externally scanning at least a portion of said human with a remote reader to generate read signals; and determining a location of said human that corresponds to a strongest read signal generated by said remote reader. 25. A method for locating an implant implanted in a human, said implant having a transponder associated therewith, said method comprising the steps of: externally scanning at least a portion of said human with a remote reader to generate read signals; and determining a location of said human that corresponds to a strongest read signal generated by said remote reader.

Inventors: BELSEY ELIZABETH MARY, KNAPP TERRY R, BELSEY, ELIZABETH, MARY, KNAPP, TERRY, R.
Applicants: LIPOMATRIX INC, LIPOMATRIX INCORPORATED
Application year: 1996
Main classification: A61F2
IPC codes: A01K11, A61B5, A61B17, A61B19, A61F2, A61M37, H04B1