Tissue growth control apparatus and method

• US 4,314,554 A
• Filed: 07/16/1979
• Issued: 02/09/1982
• Est. Priority Date: 07/16/1979
• Status: Expired due to Term

• Current Assignee: Wilson Greatbatch
• Original Assignee: Wilson Greatbatch
• Inventors: Greatbatch, Wilson
• Primary Examiner(s): Cohen, Lee S.
• Application Number:
  US06/057,744
• Time in Patent Office: 939 Days
• Field of Search: 128/82.1, 128/207.21, 128/419 F, 128/419 B, 128/419 C, 128/419 P, 128/419 R, 128/420 R
• US Class Current: 604/20
• CPC Class Codes: A61B 17/58 for osteosynthesis, e.g. bone plates, screws , setting implements or the like A61B17/14, A61B17/16 take precedence
• CPC Class Codes: A61F 2002/2821 Bone stimulation by electromagnetic fields or electric current for enhancing ossification
• CPC Class Codes: A61N 1/08 Arrangements or circuits for monitoring, protecting, controlling or indicating for external stimulators A61N1/3603; for implantable neurostimulators A61N1/36128; for heart stimulators A61N1/37; for defibrillators A61N1/3925
• CPC Class Codes: A61N 1/205 for promoting a biological process
• CPC Class Codes: A61N 1/326 for promoting growth of cells, e.g. bone cells
• CPC Class Codes: A61N 1/372 Arrangements in connection with the implantation of stimulators

Abstract

A method and apparatus for providing germicidal and healing treatment of tissue such as bone wherein an electrode of silver or like material is applied to a living tissue site to be healed, initially a direct voltage is applied to the electrode of a polarity driving the electrode as an anode to release silver ions to create a germicidal environment at the site, and thereafter a direct voltage of opposite polarity is applied to the electrode driving it as a cathode to stimulate healing of the tissue at the site. The apparatus is implanted in the body of a patient, and in one embodiment a battery is connected through a switch to the electrode and a reference electrode, the switch initially connecting the electrode as an anode and thereafter changeable by an external operator such as a magnet to connect the electrode as a cathode. In another embodiment, another electrode and an element cooperate with the treating electrode to form a galvanic couple with the treating electrode to create a germicidal environment and a predetermined time thereafter the arrangement changes to a biogalvanic couple with body fluid to cause healing of the tissue. In either embodiment a wave shaping circuit can be operatively associated with the treating electrode to facilitate external monitoring of the apparatus when implanted.

Claims

1. Apparatus for implantation in a patient for providing germicidal and healing treatment of tissue such as bone comprising:

(a) an electrode of silver adapted to be operatively connected to a living tissue site to be healed;

(b) another electrode adapted to be connected to a location spaced from the site to be healed;

(c) a source of direct voltage having positive and negative polarity output terminals;

(d) switching means operatively connected to said electrodes and to said terminals of said source, said switching means having a first state wherein said silver electrode is connected to said positive terminal and said other electrode is connected to said negative terminal once during an initial portion of the time during which said silver electrode is operatively connected to the tissue site and a second state wherein said silver electrode is connected to said negative terminal and said other electrode is connected to said positive terminal once during the remaining portion of the time during which said silver electrode is operatively connected to the tissue site, said switching means including means enabling said switching means to be operated by operator means positioned external to said patient at a location so as to be operatively associated with said switching means for selectively and non-invasively changing the states of said switching means; and

(e) means for enclosing said source, said switching means, any portion of said silver electrode not in operative contact with said tissue site to be healed, and any portion of said other electrode not in operative contact with said location spaced from the site to be healed, said enclosing means being of human body reaction free material thereby permitting said apparatus to be implanted in the body of the patient;

(f) whereby when said switching means is in said first state current flow is in a direction relative to said silver electrode causing silver ions to be released to create a germicidal environment at the tissue site and when said switching means is in said second state current flow is in an opposite direction causing healing of tissue at the site.

2. Apparatus according to claim 1, wherein said switching means comprises a pair of single pole double throw magnetic reed switches and wherein said operator means comprises a magnetic element operatively associated with said switches for selectively changing the states of said switches.

3. Apparatus according to claim 1, wherein said direct voltage source comprises a battery.

4. Apparatus according to claim 3, wherein said battery is of the lithium-halogen type.

5. Apparatus according to claim 1, wherein said silver electrode comprises a silver wire adapted to be inserted in the tissue site.

6. Apparatus according to claim 1, further including first electrical resistance means connected between said positive source terminal and said switching means and second electrical resistance means connected between said negative source terminal and said switching means, said second resistance means having a magnitude significantly greater than the magnitude of said first resistance means whereby the magnitude of current flow during healing of tissue is significantly less than the magnitude of current flow during germicidal treatment.

7. Apparatus according to claim 1, further including wave shaping means operatively associated with said silver electrode for causing the electrical current flow relative to said silver electrode to have a waveform which is readily discernible by external patient monitoring apparatus.

8. A method of providing germicidal and healing treatment of tissue such as bone comprising the steps of:

(a) providing apparatus comprising an electrode of silver adapted to be operatively connected to a living tissue site to be healed, another electrode adapted to be connected to a location spaced from the site to be healed, a source of direct voltage having positive and negative polarity output terminals, switching means operatively connected to said electrodes and to said terminals of said source, said switching means having a first state wherein said silver electrode is connected to said positive terminal and said other electrode is connected to said negative terminal once during an initial portion of the time during which said silver electrode is operatively connected to the tissue site and a second state wherein said silver electrode is connected to said negative terminal and said other electrode is connected to said positive terminal once during the remaining portion of the time during which said silver electrode is operatively connected to the tissue site, and means for enclosing said source, said switching means, any portion of said silver electrode not in operative contact with said tissue site to be healed, and any portion of said other electrode not in operative contact with said location spaced from the site to be healed, said enclosing means being of human body reaction free material whereby said apparatus is implantable in the body of a patient;

(b) implanting said apparatus in the body of a patient in neighboring relation to the tissue site to be healed including applying said silver electrode to the site and applying said other electrode to a location in the body spaced from the site to be healed;

(c) providing operator means having an operative association with said switching means for non-invasive and selective changing of the states of said switching means; and

(d) placing said operator means at a position external to the body of a patient at a location providing said operative association and operating said operator means to apply to said silver electrode for a predetermined time and once while said silver electrode is applied to the tissue site a d.c. voltage of a positive polarity causing current flow in one direction to drive said silver electrode as an anode and release ions to create a germicidal environment at the site and then to apply to said silver electrode after said predetermined time and once while said silver electrode is applied to the tissue site a d.c. voltage of opposite polarity causing current flow in the opposite direction to drive said silver electrode as a cathode to stimulate healing of tissue at the site.

9. A method according to claim 8, wherein said step of applying a d.c. voltage of opposite polarity to stimulate healing is performed for a length of time significantly greater than said step of applying d.c. voltage to create the germicidal environment.

10. A method according to claim 8, further including limiting the magnitude of current flow in said opposite direction during healing to a magnitude significantly less than the magnitude of current flow in said one direction creating the germicidal environment.

11. In combination with implantable apparatus for providing germicidal and healing treatment of tissue such as bone comprising a treating electrode of a material which creates a germicidal environment and promotes healing of tissue in response to current flow relative to the electrode, the germicidal or healing mode being determined by a characteristic of said current flow, and means for applying voltage to said electrode to cause said current flow:

wave shaping means operatively connected to said voltage applying means and to said treating electrode for causing the electrical current flow relative to said treating electrode to have a waveform which is readily discernible by external patient monitoring apparatus for determining non-invasively continued operation of said apparatus when implanted and the germicidal or healing treatment mode of operation of said apparatus.

12. The combination according to claim 11, wherein said wave shaping means comprises:

(a) switching means connected between said voltage applying means and said treating electrode for alternately connecting and disconnecting said voltage applying means to said treating electrode; and

(b) control means connected in controlling relation to said switching means for opening and closing said switching means.

13. The combination according to claim 12, wherein said control means includes timing means for controlling the relative time durations of opening and closing of said switching means.

14. A method of monitoring the operation of apparatus implanted in a patient for healing treatment of tissue such as bone including a treating electrode of a material which promotes healing of tissue in response to current flow relative to the electrode, the treating electrode being applied to a tissue site to be healed and another electrode in a current flow path including the treating electrode being applied to a location spaced from the site to be healed, and means for applying voltage to the treating electrode for causing the electrical current flow relative to the treating electrode, said monitoring method comprising:

(a) shaping the waveform of the electrical current relative to the treating electrode to have a waveform which is readily discernible by external patient monitoring apparatus; and

(b) detecting the shaped waveform non-invasively by means of monitoring apparatus external to the body of a patient and responsive to the shaped waveform.

15. The method according to claim 14, wherein said step of shaping the waveform comprises periodically connecting and disconnecting the voltage applying means to the treating electrode.

16. The method according to claim 15, wherein the connecting and disconnecting is performed at a rate of about once per second.

17. The method according to claim 16 wherein the time duration of the connecting is about twice the time duration of the disconnecting.