WO2001064030A1

WO2001064030A1 - Implantation

Info

Publication number: WO2001064030A1
Application number: PCT/IB2001/000283
Authority: WO
Inventors: Herman Booyens; Michael Edward Thomas; Paul Wilhelm Richter
Original assignee: Csir
Priority date: 2000-03-02
Filing date: 2001-03-01
Publication date: 2001-09-07
Also published as: AU2001235899A1

Abstract

An artefact (10) suitable for body implantation is provided. The artefact (10) includes an implant (12) for implanting into soft tissue of the body of a subject, and anchor means (14) associated with the implant (12), for inhibiting migration of the implant through or out of the body. The anchor means (14) comprises or consists of a bioactive material.

Description

IMPLANTATION

THIS INVENTION relates to implantation. In particular, it relates to

an artefact suitable for body implantation, and to a method of anchoring an

artefact in the body of a subject.

The Applicant is aware of medical implants which are generally

composed of or encapsulated in materials which could be described as

biotolerant, bioinert or biocompatible. The Applicant is also aware of

identification tags for implantation in animals. While the medical implants and

identification tags may be tolerated in a body, body cells do not neccessarily

attach directly to the implanted material. Typically, the implanted object is

accomodated by the growth of tissue as an interface or capsule around the

implant, in the body of the subject. As a result, implant migration is possible with

time, which is undesirable. One approach used to inhibit the migration of

implanted objects is to provide the implanted objects with anti-migration formations. However, this approach is not always successful, particularly if it is

intended that the implanted object remain in the body of the subject for a

prolonged period of time.

According to one aspect of the invention, there is provided an artefact suitable for body implantation, the artefact including

an implant for implanting into soft tissue of the body of a

subject; and

anchor means associated with the implant, for inhibiting

migration of the implant through or out of the body, the anchor means comprising

or consisting of a bioactive material.

In this specification, the term "bioactive material" is intended to

mean a material which is not only biocompatible but which also elicits a biological

response when implanted in living tissue so that the living tissue will directly attach to and form a bond with a surface of the material. The bioactive material

can be non-resorbable, partially resorbable or fully resorbable, and typically

comprises or consists of calcium, phosphates, and/or carbonates.

Examples of suitable bioactive materials are ceramics and cements

based on calcium phosphates including hydroxyapatite and tri-calcium phosphate, glasses and glass ceramics based on a soda-silica-calcia-phosphate system, and

composite materials which include at least one bioactive component or material

and typically a different biocompatible material, such as hydroxyapatite- polyethylene composites. The bioactive component of such a composite material may define exposed bioactive surface sites.

The bioactive material of the anchor means may be porous. The

porous bioactive material may have micropores up to about 1 00 μm in size, and

macropores up to about 3 mm in size.

In one embodiment of the invention, the anchor means is in the form

of an anchor body attached to the implant. The anchor body may be attached to

the implant by mechanical means, adhesive means, or the like and may be of

monolithic construction. The artefact may include attachment means attaching

the anchor body to the implant.

In another embodiment of the invention, the anchor means is in the

form of a hollow capsule or cage which holds the implant captive. If desired, the

capsule may be configured to allow the implant to resorb or release components

slowly from the capsule into the body. For purposes of assembly or charging, the

capsule may have an aperture through which the implant can be inserted. Thus,

the capsule may include closure means for the aperture. The closure means may be of a biocompatible polymer, e.g. in the form of a plug of a biocompatible

polymer.

In a further embodiment of the invention, the anchor means is in the

form of a coating of a bioactive material which covers at least part of the implant. Such a coating can for example be applied to the implant by flame or plasma spraying, or by biomimetic means.

In yet another embodiment of the invention, the anchor means is in

the form of a cast body of a settable bioactive material, such as a bone cement,

cast so that the cast body at least partially covers the implant.

In yet a further embodiment of the invention, the anchor means is

defined by exposed bioactive surface sites provided on an exterior surface of the

implant, e.g. where the implant is a flexible biocompatible polymer or has an outer

surface defined by a biocompatible polymer with the anchor means being defined

by exposed hydroxyapatite particles or features embedded in the polymer.

The anchor means may also comprise a converted surface layer of

the implant, with the converted surface layer thus being of bioactive material, and

the remainder of the implant being of unconverted material or a non-bioactive

material . The converted surface layer may be that obtained by treating material

of the implant, at the implant surface, thereby to render it bioactive. Conversion

of the surface layer of the implant may be effected by chemical, thermal or other

means.

The anchor body may define a circular outline for the artefact in at

least one view, thus allowing the artefact to be implanted in a subject by means

of a syringe or the like. The artefact may be generally elongate and the anchor body may be cylindrical, e.g . circular cylindrical.

The implant may be an animal marker, e.g. a transponder. Instead,

the implant may be a sensor for sensing one or more body conditions. Further examples of implants which can be positioned and anchored by means of the

artefact of the invention include a pharmaceutical substance, a body of living cells, and a radioactive substance.

The anchor body may be adapted to inhibit migration of the artefact

due to the shape or configuration of the anchor body. For example, the anchor body may define anchoring formations such as recesses, apertures, slots,

projections, barbs or the like to limit movement of the anchor body relative to

surrounding body tissue in use during initial tissue attachment. The anchor body

may also be adapted to facilitate suturing it temporarily in place in a subject, at

least until the anchor body becomes anchored through tissue attachment and

bonding to the surface of the anchor body.

According to a second aspect of the invention, there is provided a method of anchoring an artefact in the body of a subject, the method including

locating an artefact as hereinbefore described in a desired location in soft

tissue of the body of the subject; and allowing soft tissue of the body to attach to and form a bond with the

anchor means of the artefact, thereby to anchor the artefact in the body in the

desired location in the body of the subject.

The method may include temporarily anchoring the artefact in the

body, to enable the soft tissue of the subject to attach to and form a bond with

the anchor means of the artefact over a period of time. Temporarily anchoring

the artefact may include temporarily suturing the artefact in place, e.g. with a

suture which breaks down or resorbs over time.

The location of the artefact may be effected by injecting the artefact

into the soft tissue of the subject, e.g. with a syringe or the like. Instead, the

artefact may be inserted surgically by making an incision in the soft tissue.

The invention will now be described, by way of example, with

reference to the accompanying diagrammatic drawings, in which

Figure 1 shows a three dimensional view of one embodiment of an artefact

suitable for body implantation in accordance with the invention;

Figure 2 shows a three dimensional view of another embodiment of an

artefact suitable for body implantation in accordance with the invention; and

Figure 3 shows a longitudinally sectioned view of yet another embodiment

of an artefact suitable for body implantation in accordance with the invention. Referring to Figure 1 of the drawings, reference numeral 10 generally indicates an artefact in accordance with the invention suitable for body implantation.

The artefact 10 includes an implant, in the form of an elongate

transponder 1 2. The transponder 1 2 is a conventional transponder used for marking an animal.

The artefact 10 also includes anchor means, in the form of an anchor

body 1 4 of hydroxyapatite. The anchor body 1 4 defines an essentially cylindrical

outer surface 1 6 and a passage 1 8 extending longitudinally through the anchor

body 1 4. A plurality of anchoring formations, in the form of recesses 20 is

provided in the outer surface 1 6, thereby to roughen the outer surface 1 6.

The transponder 1 2 is located inside the passage 1 8 and is

adhesively attached to the anchor body 1 4 by means of an adhesive (not shown) .

In end view, the artefact 1 0 is circular cylindrical in outline, having

a diameter of about 4 mm to 5 mm.

In use, the artefact 1 0 is placed in a desired location in the soft

tissue of a subject, such as an animal, by means of a syringe. The roughened

outer surface 1 6 of the anchor body 1 4 serves to limit movement of the anchor

body 1 4 relative to the surrounding soft tissue of the subject during initial tissue attachment, thereby inhibiting migration of the artefact 10 through or out of the

subject. The anchor body 14, being of hydroxyapatite and thus bioactive, allows

the soft tissue of the subject to attach thereto and to form a bond therewith,

thereby to anchor the artefact 1 0 in the desired location in the subject.

Referring to Figure 2 of the drawings, another embodiment of an

artefact suitable for body implantation is generally indicated by reference numeral

30. The artefact 30 is similar to the artefact 1 0, and unless otherwise indicated,

the same reference numerals used in relation to the artefact 10 are used to

indicate the same or similar parts of features.

Unlike the anchor body 1 4 of the artefact 1 0, the artefact 30 has an

anchor body 32 which is longitudinally spaced from the transponder 1 2 and

attached to the transponder 1 2 by way of attachment means in the form of a

wire 34 imbedded in the transponder 1 2 and the anchor body 32.

Two passages 36, 38 extend through the anchor body 32.

In use, the artefact 30 is typically inserted surgically by making an incision in the soft tissue of the body of a subject , and locating the artefact 30

in the soft tissue of the subject. The passages 36, 38 can be used to suture the

artefact 30 in position temporarily, allowing the soft tissue of the body of the

subject enough time in which to attach to and form a bond with the anchor body

32. The suturing is typically done using a suture which degrades or resorbs over time, so that eventually the artefact 30 is anchored in place by the soft tissue of

the subject having attached to and formed a bond with the anchor body 32.

Referring to Figure 3 of the drawings, reference numeral 40 generally

indicates yet another embodiment of an artefact suitable for body implantation,

in accordance with the invention. Again, the artefact 40 is similar to the artefact

1 0, and unless otherwise indicated, the same reference numerals used before are used to indicate the same or similar parts or features.

The artefact 40 has an anchor body 42 which is in the form of a

hollow capsule. The anchor body 42 is shaped and dimensioned to receive the

transponder 1 2 fully and with a snug fit. A plug 44 of a biocompatible polymer

plugs an aperture in one end of the anchor body 42. The aperture in the end of

the anchor body 42 is used to assemble the artefact 40, whereafter the plug 44

is inserted .

The anchor body 42 also has a circular cylindrical outer surface 1 6

and can thus be inserted by means of a syringe or the like into the soft tissue of

the body of a subject, similar to the artefact 10.

It is an advantage of the artefact 10, 30, 40, as illustrated, that it

includes anchor means of a bioactive material, allowing soft tissue of a living

subject to attach thereto and form a bond therewith, thus inhibiting migration of the artefact through or out of the subject, even when the artefact has been in the

body of the subject for a prolonged period of time.

Claims

CLAIMS:

1 . An artefact suitable for body implantation, the artefact including

an implant for implanting into soft tissue of the body of a subject; and

anchor means associated with the implant, for inhibiting

or consisting of a bioactive material.

2. An artefact as claimed in claim 1 , in which the bioactive material

includes a ceramic or cement based on a calcium phosphate.

3. An artefact as claimed in claim 1 or claim 2, in which the bioactive

material includes a glass or a glass ceramic based on a soda-silica-calcia-

phosphate system.

4. An artefact as claimed in any one of the preceding claims, in which

the bioactive material is a composite material of at least one bioactive material

and a different biocompatible material.

5. An artefact as claimed in any one of the preceding claims, in which

the bioactive material is porous.

6. An artefact as claimed in claim 5, in which the bioactive material has micropores up to 1 00 μm in size.

7. An artefact as claimed in claim 5 or claim 6, in which the bioactive

material has macropores up to 3 mm in size.

8. An artefact as claimed in any one of the preceding claims, in which

the anchor means is in the form of an anchor body of monolithic construction

attached to the implant.

9. An artefact as claimed in claim 8, in which the anchor body defines

a circular outline for the artefact in at least one view, thus allowing the artefact

to be implanted in a subject by means of a syringe.

1 0. An artefact as claimed in claim 8 or claim 9, in which the anchor

body is adapted to inhibit migration of the artefact due to the shape or

configuration of the anchor body.

1 1 . An artefact as claimed in any one of claims 1 to 7 inclusive, in which

the anchor means is in the form of a hollow capsule or cage which holds the

implant captive.

1 2. An artefact as claimed in any one of claims 1 to 7 inclusive, in which

the anchor means is in the form of a coating of the bioactive material which

covers at least part of the implant.

1 3. An artefact as claimed in any one of claims 1 to 7 inclusive, in which

the anchor means is in the form of a cast body of a bioactive material, cast so

that the cast body at least partially covers the implant.

1 4. An artefact as claimed in any one of claims 1 to 7 inclusive, in which

the anchor means is defined by exposed bioactive surface sites provided on an

exterior surface of the implant.

1 5. An artefact as claimed in any one of claims 1 to 7 inclusive, in which

the anchor means comprises a converted surface layer of the implant, the

converted surface layer thus being of bioactive material, and the remainder of the

implant being of unconverted or non-bioactive material.

1 6. A method of anchoring an artefact in the body of a subject, the

method including locating an artefact as claimed in any one of claims 1 to 1 5

inclusive in a desired location in soft tissue of the body; and allowing soft tissue of the body to attach to and form a bond

with the anchor means of the artefact, thereby to anchor the artefact in the

desired location in the body of the subject.

1 7. A method as claimed in claim 1 6, which includes temporarily

anchoring the artefact in the body, to enable the soft tissue of the subject to

attach to and form a bond with the anchor means of the artefact over a period

of time.

1 8. An artefact as claimed in claim 1 , substantially as herein described

and illustrated.

1 9. A method as claimed in claim 1 6, substantially as herein described

and illustrated .

20. A new artefact or a new method, substantially as herein described .