WO1992015252A1

WO1992015252A1 - Surgical implant for the stabilization of soft-tissue and devices for insertion, displacement and removal of said implant

Info

Publication number: WO1992015252A1
Application number: PCT/SE1992/000152
Authority: WO
Inventors: Pål Svedman
Original assignee: Principal Ab
Priority date: 1991-03-07
Filing date: 1992-03-09
Publication date: 1992-09-17
Also published as: SE9100686D0

Abstract

A surgical implant for the stabilisation of soft tissue comprises at least one hook-shaped fastening element (1) and at least one thread element (6) fixed thereto. The fastening element may, for instance, consist of one or more hooks. An implant unit comprising the above implant and fixing means, as well as devices for insertion, displacement and removal of the implant are also disclosed.

Description

SURGICAL IMPLANT FOR THE STABILIZATION OF SOFT-TISSUE

AND DEVICES FOR INSERTION, DISPLACEMENT

_AN_{D REM}OVAL OF SAID IMPLANT

The present invention relates to implants which are intended to be used in surgery for increasing the tensile strength in connective-tissue structures substantially parallel to the skin surface, primarily in the subcutis and in the superficial fascial layers, but also indirectl in the overlying dermis, as well as devices for the inser tion, displacement and removal of the implant. In an ope¬ ration, the sagging tissues are initially stretched, and the surplus, if any, is cut away (e.g. in face-lifting, operations for facial paresis, and plastic surgery on the breasts or the abdomen). Then, the stretched, but still sagging and weakened, connective-tissue structures are supplemented with and stabilised by implants which are atraumatically introduced by tunnelling into the intact subcutis. Thus, weakened tissue is stabilised, thereby promoting reshaping, compression and contraction. Usually the implants are not degraded in the tissue.

Living tissue is composed of cells that are kept together by connective tissue that is rich in fibres. The connective tissue usually constitutes a firm struc- ture which, in surgery, is used as attachment in connec¬ tion with suturing. The dermis consists of dense connec¬ tive tissue which passes into the subcutis as an uneven, thin, less dense layer, from which bands run substantiall vertical to the skin surface (retinacula spaced apart about 2-5 mm) to an underlying connective-tissue layer extending outwards substantially parallel to the skin (th fascia superficialis, usually one centimetre or so below the dermis). On some body parts (e.g. the stomach and the hips), this fascia is well-developed and additional bands here continue into the outer muscle fascia which consti¬ tutes a dense, firm connective-tissue layer. On other bod parts, the fascia superficialis is part of the outer muscle fascia. The dermis, the retinacula and the fascial structures keep the intermediate fat cells as well as ves¬ sels and nerves in place, and fix the dermis to the under¬ lying muscle. The implant according to the invention is intended to be used under the dermis in subcutis tissue and fascial tissue down to the muscles.

Surgical reshaping of soft tissues is performed by stretching sagging tissues, cutting away any surplus and suturing the skin and sometimes also deeper soft tissues. In patients with paresis in the facial nerve, soft tissues and skin in the face become loose, and in surgical recon¬ struction fascia grafts taken from the patient's own tis¬ sue is used in the subcutis to achieve increased tensile strength and maintain a shortened state of the soft tis- sues. However, this graft is disadvantageous in that it may be perceived as a thickening of the skin. In addition, the graft may gradually be degraded in the tissue and lose its strength. The prior art does not encompass any implants which obviate these inconveniences. In face-lifting, also deeper soft tissues have to be surgically manipulated and sectioned to be subsequently shortened and sutured to a layer of the subcutis. In this technique, however, the scalpel, scissors and pointed or incisive suture needle is used in or close to the facial nerve, which is sometimes damaged where it runs compara¬ tively superficially in the cheek. A suture may yield owing to cutting or insufficient blood supply within the closed suture loop. Such inconveniences may be a late effect of the operation, and contribute to renewed sagging of the soft tissues.

One object of the present invention is to provide a simple surgical implant and an implant unit increasing the tensile strength in connective-tissue structures substan¬ tially parallel to the skin surface primarily in the sub- cutis and the superficial fascial layers but also indi¬ rectly in the overlying dermis, wherein both the implant and the implant unit can be positioned in the tissue with- out any risk of damaging larger vessels, nerves, or speci fic organs.

Another object of the invention is to provide a device for the insertion, displacement and removal of the implant.

Yet another object of the invention is to provide a device for removal of an existent implant.

A further object of the invention is to provide a method for inserting, displacing or removing the implant by means of the above devices.

According to the invention, these and other objects are achieved by a surgical implant comprising a thread with fastening elements for the stabilisation of soft tis sue, an implant unit comprising the implant and one or more fixing means, and devices for the insertion, dis¬ placement and removal of the implant, as recited in the appended claims.

The invention will be described in more detail below with reference to the accompanying drawings, in which Figs 1-4 illustrate different embodiments of a hook which is part of the implant according to the invention, Fig. 5 illustrates a thread, a hook being fixed to one end of the thread and a cutting needle being fixed to the other end, Figs 6A, 6B and 7 illustrate a mode of fixing the thread to the hook,

Figs 8-10 illustrate a device for insertion and dis¬ placement of the thread and the hook element of the implant in an intact subcutis, Figs 11A and 11B illustrate the device with inserted implant,

Figs 12A-12C illustrate the device of Figs 11A and 11B, the hook having been pushed out into a position wher it can engage the tissue, Fig. 13 illustrates the hook when hooked onto the connective-tissue retinacula of the subcutis, the device for insertion having been disengaged from the implant and being about to be removed from the tissue,

Figs 14-17 illustrate different embodiments of the fixing means of the implant unit, which consist of screw devices.

Fig. 18 illustrates a device that can be used for permitting an implant thread to turn between the two points of attachment in the tissue.

Figs 19-20 illustrate how the invention can be used in face-lifting,

Figs 21A and 2IB illustrate a device used for remov¬ ing the thread and the hook element of the implant when required, and

Fig. 22 illustrates such a removal from the soft tis sues of the face after a previously performed face-lift. Fig. 1 shows a simple embodiment of the implant according to the invention, which consists of a thread 6 and a hook 1. The cross-section of the hook 1 is rectan¬ gular, providing a maximum area of application against the hook concavity. The cross-section of the hook may also be oval, as in Fig. 2, or circular. As shown in Fig. 1, the free end portion 2 of the hook is tapering, but not cut¬ ting. An end portion 3 of the hook that is closest to the thread is perfectly rectangular to provide a secure attachment when introduced with the aid of forceps or the like. The cross-section of this end portion may also have the shape of an equilateral or inequilateral triangle. A round portion 4 between the hook and the thread consists of a tube which provides an attachment for the thread 6. How the thread can be attached is described in more detail in connection with Figs 6A, 6B and 7. Fig. 3 shows a double hook 7. In the example, the angle between the hooks is 180°. Alternatively, another angle may be used. Fur¬ ther, the hook or hook element may be folded during inser- tion in the tissue and expand after insertion. This is illustrated in Fig. 4, where the hook element is folded at 9 and maintained in this position by means of a spring 10. After implantation, the expansion can be triggered by mechanical means. The unit can optionally be made of a material with a memory for two different three-dimensiona structures, the hook shape being triggered e.g. at body temperature. Unlike the embodiments described above, the embodiment in Fig. 5 includes a cutting needle 11 arrange at the otherwise free thread end of the implant. This needle can be used for conducting the thread through appropriate cartilage or bone structure. The size and the deformability of the hook depend on the particular application and the material employed. The distance between the end portions 2 and 3 of the hook is, as shown in Fig. 1, preferably 2-6 mm. This distance may be up to 10 mm in special applications unrelated to facia operations. The cross-sectional diameter of the hook usually is 0.4-1.0 mm. The deformability is determined by the force required for the hook to yield and be reshaped. This force is 1.33 kg/N for a titanium hook having a cross-sectional diameter of 0.60 mm, but may, when the cross-section is rectangular, be as low as 0.1 kg/N.

The length of the thread is 100-400 mm, and its dia¬ meter is 0.10-0.30 mm. For example a titanium thread with a diameter below 0.30 mm is flexible when used in the tis sue. The titanium thread is mechanically stretched in pro duction in order to minimise its extensibility, before it is fixed to the hook of the implant. After being thus stretched, a thread with a diameter of 0.22 mm breaks whe the applied force amounts to 1.80 kg/N. An important con¬ structional detail resides in the fact that the hook yields and is extended before the thread breaks, and a hook with a cross-sectional diameter of 0.-6 mm is thus suitably employed together with a 0.22 mm diameter thread.

Alternatively, the hook 1 can be formed with a weake ed portion, preferably in its concave part. Figs 6 and 7 illustrate an attachment between the round portion 4 and the thread 6. Figs 6A and 6B show the round portion 4 of the hook and a titanium thread 6 inserted therein. Fig. 7 shows how a compressive force f urges the tubular wall 12 into the titanium thread which thus is compressed within an area 13 of the thread 6. The tensile strength of the attachment exceeds that of the hook.

The portion 4 not only serves as an attachment for the thread 6 to the hook 1, but is also essential when th implant is displaced and removed, as will be described in more detail below. It is especially preferred that the free end of the hook in all the above embodiments is so designed that it cannot cut or pierce any tissue structures of importance. Thus, the hook usually should not be cutting or pointed in a manner that enables it to pass through firmer soft tis- sues, such as the dermis, the fascia, or vessels. It is, however, conceivable to have a cutting hook which is then employed in operations on other body parts than the face, e.g. the abdomen. To prevent cutting, the contact area with the tissue should in all possible uses exceed that of a conventional suture. The hook is applied with a certain pulling force in the longitudinal direction of the thread, and the hook design therefore should ensure that the con¬ tact area with the tissue is at its maximum, at least within the maximally curved portion of the hook. For the same reason, it is essential that the hook is so designed that it cannot slip out of the tissue. The two end por¬ tions of the hook beyond its curvature should therefore be substantially parallel. Further, the amount of tissue enclosed within the hook concavity, and consequently the number of connective-tissue bands, should be as large as possible without rendering the hook unwieldy to position or perceptible to the patient once it has been positioned. This means that the two end portions of the hook should be parallel and also have a certain length in order to enclose more tissue and provide a stable attachment in the tissue. The implant and the implant unit according to the i vention should be made of an inert material which neithe gives rise to an immunological reaction nor sustains an infection. Preferably, the implant and the implant unit are therefore made entirely of titanium, which is an ine and well-tried clinical jaw and joint implant which, in addition, is radiopaque. Also other metals may, however, be used, such as stainless steel. The implant thread can alternatively be made of a non-degradable thread materia The hook may be U-shaped and have a round, oval or rectangular cross-section. Preferably, the hook is non- cutting, and its free end can be tapering, angular or rounded. At the other end, the thread is fixed. Two or more hooks may be differently configured along a common axis, and the hook shape cannot be assumed until after activation. To employ a fastening element in the form of a hook has many advantages compared with the use of the closed loop of a suture. The tissue contained within the hook ends can swell freely out of the opening of the hoo which minimises the risk of any negative effects on the local blood supply. Further, the hook may have a much larger contact area with the tissue than a suture of the same length. Compared with a commonly employed suture, e.g. of a thickness of 3-0, (diameter: 0.22 mm, rounded surface regarded as flat), the hook surface is 3-7 times larger. As a result, the risk of cutting through the tis¬ sue is reduced, as is the risk of pressure-induced damage to the tissue. Further, this construction provides maximu contact with existing connective-tissue structures and, consequently, maximum stability of the hook attachment in the soft tissue.

With the aid of a special device, the thread and the hook element of the implant can be introduced into intact subcutis, passed into the tissue, displaced and removed from the tissue in a controlled manner without causing any appreciable damage. To this end, the device is rounded at the end which penetrates into the tissue. The rounded end may have different shapes so as to mini¬ mise the damage caused, as stated in the prior art (6. Ozcan, S. Shenaq, B. Baldwin, M. Spira. The trauma of suction assisted lipectomy cannula on flap circulation in rats. Plast Reconstr. Surg 88, 250-258, 1991).

A preferred embodiment of the inventive device for insertion of the thread and the hook element of the im¬ plant into the subcutis will be described in more detail below with reference to Figs 8-13, which illustrate such device. Thus, the device is made up of an inner, circular and tubular unit 14, as shown in Figs 8 and 9. In Fig. 10, the unit 14 is threaded into an outer casing 20 which is formed with a rounded end 20' and a rectangular slit 21 which allows the passage of the hook 1 of the implant. In this embodiment, the casing 20 is a surgical cannula which, owing to its rounded end 20', can be tunnelled int the subcutis without damaging tissue in the way that occurs when cutting with a scalpel or a needle, or pierc¬ ing with a pointed needle. The outer diameter of the cas- ing should be about 1 mm wider than that of the hook to be inserted. The hollow unit 14 (Fig. 8) is outwardly thread¬ ed at the end 16 and is formed with a slit 17 which can be closed when the end piece 15 is maximally screwed in. The end 16 is formed with a cylindrical opening 18, and the interior of the unit 14 consists of a cavity 19, as shown in Figs 9A and 9B. The opening 18 permits the passage of the thread of the implant and is adapted to accommodate the portion 4 of the hook in such a way as to permit rota¬ tion (Fig. 1). It is essential that the round portion 4 constitutes an extension of one end portion of the hook, i.e. that it projects outwardly of the free end portion 2 of the hook, in order not to interfere with the rotational movements.

In Figs 10A and 10B, the unit 14 is threaded into the casing or cannula 20 which is formed with internal threads corresponding to the external threads of the unit 14. The unit 14 can at most be rotated through 180° from the posi- tion shown in Fig. 10B, and in this process becomes dis¬ placed away from the end 20' of the casing. In the outer casing 20, there is a throughgoing screw 22 cooperating with a groove or slit 23 which runs obliquely through 18 of the circumference of the tube 14, as shown in Fig. IO When the unit 14 is in the, position shown in Fig. 10B, t screw 22 has reached the end of the slit 23, further rot tion in the same direction being thus prevented. However the unit 14 may if necessary be rotated back towards the end 20' of the casing. A visible marking on the outer wa of the casing 20 may indicate to the surgeon whether the hook is in countersunk or projecting position. The con¬ structional detail of the screw 22 and the slit 23, the latter running obliquely about the tube 14 through 180° the circumference of the tube, can optionally replace th external threads of the unit 14 and the internal threads of the casing 20. Fig. 10D shows a detail of the rounded end of the casing, including a rectangular slit 21 allow ing access for the hook of the implant. In Figs 11-12, the thread and the hook element of t implant have been positioned in the device. In Fig. 11A, the implant is completely countersunk in the casing. The rounded portion 4 of the hook 1 is placed in the opening 18 which in turn is at a maximum distance from the slit 21. The thread has been taken through the cavity 19 of t unit and locked in stretched position in the opening 17 tightening of the screw 15, thus clamping the thread 6 a 8. In Fig. 12A, the device has been tunnelled bluntly in the tissue, and the hook 1 has been pushed out so as to engage the tissue. This has been achieved by rotating th unit 14 through 180° relative to the casing. Thus, the hook is moved via the portion 4 in the opening 18 towards the opening 21, as shown in Fig. 12B. The hook is guided into place by the walls 13 of the casing 20 which have been given a suitable shape, e.g. with thickened portions as shown in Fig. 12B, in this area so as to guide the hoo into place in the opening 21. If the hook is to be attach ed elsewhere in the tissue, the unit 14 is rotated back at the same time as the device is inserted a bit further. Then, the hook will again be in the position shown in Fig. 11A. If need be, the device including the countersunk implant can be withdrawn from the tissue. In Fig. 13, the hook 1 of the implant engages tissue 24. The thread 6 of the implant runs freely at 8, and the device for insertion is about to be removed from the tissue. Fig. 13 may also illustrate a first step in the removal of a previously positioned implant. Then, one returns to the step illu¬ strated in Fig. 11A before removing the implant from the tissue. The thus-described device according to the inven¬ tion is but one of several embodiments which all are based on a protected insertion of the thread and the hook ele- ment of the implant where use is made of a blunt, cannula- like instrument which causes miminum damage to the tissue, and where the hook cannot be introduced into the tissue in a known place, also in relation to the cannula end, until the position is considered to be optimal. This is the only way to completely avoid areas with important vessels and nerves or important organ structures. It is further required that the implant can be reintroduced into the cannula without damaging the tissue. This is necessary to enable the implant to be repositioned or withdrawn from the tissue.

The means for guiding the implant to the desired position (i.e. the threaded ends 15 and 16 with corre¬ sponding threads in the outer casing, the slit 23 and the screw 22 in the illustrated embodiment), can be designed in various ways. The important thing is that the hook of the implant is guided out of the outer casing and can be locked in the desired position. Such modifications fall within the scope of the invention.

The device for insertion and displacement of the thread and the hook element of the implant (see further below) is preferably of disposable type and made of rigid plastic. Thus, the device can be delivered with the im¬ plant in place so as to be ready for use.

The invention further provides an implant unit com¬ prising the above implant and a fixing means for fasteni the free end of the thread in more solid tissue, such as bone or cartilage.

Figs 14-17 illustrate different embodiments of the fixing means. In Figs 14A and 14B, the fixing means is a double screw. The maximum cross-sectional diameter usall is 3-7 mm. An outer screw 25 serves as an attachment in bone via suitable threads 30. An inner screw 26 is adapt to cooperate with the outer screw 25. Advantageously, th inner screw can be loosened without interfering with the bone attachment. Recesses 27 provide a hold for a screw- driver. In Fig. 14C, the threads 6 of the implant are ke in place after tightening of the screw 26. Fig. 15 shows an attachment with two double screws enabling identifica tion and removal of a specific thread without loosening the other threads from their attachments. The threads 6 run in the recess 28 in the screw 25. Figs 16-17 show another fixing means comprising two cylindrical units 32 with a central recess for the screw 26 and a recess 28 f the threads 6. The maximum cross-sectional diameter of t double screw usually is 3-7 mm. The units 32 can be inte connected by flexible rods 33 and be attached to cartila or bone by suture - suitably in titanium - via the loops 34. Instead of the screw attachment, use can be made of tubular element (not shown) which, via a loop, is fixed cartilage or bone by suture material. The tube, which ma accommodate several threads, can be compressed so as to lock the threads. In surgery, all these implant componen are covered with fascia and subcutaneous tissue after securing the attachment. Typically, this attachment is t be stabilised in bone or cartilage in a manner to cause minimal elevation above the plane of the tissue such tha it cannot be felt by the patient. The double-screw devices or tubular elements are fixed in bone or cartilage. Since several threads usually are required, two fixing points are provided. In a later adjustment, one may thus identify the thread which is to be adjusted without slackening any of the others. Another possibility is to lock the thread by compressing the sur¬ rounding tubes. This connection to bone or cartiladge pro vides a stable attachment for several implants.

Figs 18A and 18B illustrate another implant compo- nent, which may be regarded as an optional supplement to the above fixing means. This component is made up of a screw 35 and a loop 36. The recess 27 provides a hold for a screwdriver. The maximum cross-sectional diameter usual¬ ly is 3-5 mm. The component is screwed into bone outside the straight line between the hook and the screw attach¬ ments of the implant. The thread 6 is taken through the loop 36, and is thus given another direction than the one indicated by the shortest distance between the points of attachment. To remove an existent implant without major surgery, use can be made of an instrument of the type shown in Figs 21A and 21B, which illustrate a preferred embodiment of such an instrument for removing the thread and the hook element of the implant from the tissue. The instrument 39 has a tubular shape and comprises a rounded end 41 and a longitudinal slit 40. The length of the instrument is 100-200 mm, and its outer diameter is 2-4 mm. Preferably, the instrument is made of stainless steel.

The slit is designed to suit the size of the implant, and the end to be inserted in the tissue has a tapering shape to push aside any scar tissue remaining from a pre¬ vious operation.

A preferred mode of application of the invention in face-lifting is illustrated step by step in Fig. 19. An incision between the corner of the mouth and the ear is shown in Fig. 19A, and Fig. 19B shows how the dermis and part of the subcutis have been lifted via an incision at the ear, as shown in Fig. 20. In Fig. 19C, the device for insertion of the thread and the hook element of the implant has been tunnelled into the tissue. The area in the cheek where the facial nerve can be damaged has been safely passed without cutting. Two screw devices have bee bored and screwed into the bone structure in front of the ear. In Fig. 19D, the deeper soft tissues have been sur¬ gically shortened, this shortening being maintained by a few sutures. The use of the implant makes it possible to completely avoid any surgery of the deep front portions o the cheek, thereby further minimising the risk of damage. The hook has been fixed in the soft tissues, and the device for insertion of the implant has been removed. The thread of the implant has been tightened in a manner cor- responding to the tightening previously achieved in the deeper tissue, and the thread has been fixed in the two hook attachments in this position. Fig. 20 illustrates ho at least three implants are commonly used for one half of the face. In Fig. 19E, the operation is completed. The skin surplus has been cut away, and the skin edges have been joined by sutures. The implants increase the tensile strength in the connective-tissue structures substantiall parallel with the skin surface, primarily in the subcutis and the superficial fascial layers, but also indirectly i the overlying dermis. This stabilises the reconstruction and permits secondary adaption of the skin, inter alia by contraction.

Fig. 20 illustrates different positions of the screw attachments of the implant. In Fig. 20A, the attachment 25 is the bone in arcus zygomaticus, and in Fig. 20B, two cylinders with screw attachments 32 have been sutured to the front part of the cartilage of the external ear by means of titanium thread. In. Fig. 20C, screw attachments 25 have been bored into the scull bone behind and above the ear. The attachments can be provided both in front of and behind the incision in the skin 37, and do not affect the cohesiveness of the skin. Fig. 22 shows how the tubular instrument 39 is used for removing the hook and the thread element of the im¬ plant after a face-lift. The skin is incised at the ear i an existent scar to uncover the screw attachments 25 and the threads 6. The thread 6 to be removed is identified and loosened without affecting the attachments of the others. The slit 40 of the tubular instrument is placed over the thread 6 and rotated into the tissue, guided by the thread. In Fig. 22B, the end 41 of the instrument engages the hook 1. In Fig. 22C, the movement of the instrument 39 has been continued, now entraining the implant. A 5-mm incision is made on the mucous-membrane side of the cheek, and the instrument and the implant are withdrawn through the incision and removed. In this central part of the cheek, there are no important struc¬ tures that can be damaged, and this operation is regarded as safe. In addition, it will leave no visible scars.

The hook and the thread element of the implant can also be made of degradable materials. For instance, the hook can be made of starch optionally manipulated by bond¬ ing chemical side groups to the main molecule in order to delay the degradation of the starch. Alternatively, the hook can be made of collagen. The thread can be degradable and e.g. be made of polyglycolic acid or catgut. The hook and the thread element of the implant may contain chemical groups acting on the tissue. The thread, which always is flexible, may also be a tubular element, optionally with open pores in its walls, and may be con¬ nected to an implanted injection box. A solution contain- ing a growth factor can be injected into the box and be distributed via the pores to the tissue surrounding the tubular element. In this manner, the formation of connec¬ tive tissue can be actively stimulated.

The main advantages of the present invention are that the implant can be positioned without any risk of damage to major vessels, nerves or specific organs and does not cause any such damage when positioned, the implant can be inserted in the subcutis and be positioned and displaced without causing any damage, the implant unit provides stable attachments in the tissue and does not cut through it, the length of the implant can be adjusted in a simple and reliable manner by subsequent surgery, the implant unit can be localised in the tissue with the aid of X-ray, and the implant can be removed in its entirety by minor surgery.

Claims

1. Surgical implant for the stabilisation of tissue, c h a r a c t e r i s e d in that it comprises at least one hook-shaped fastening element (1) and at least one thread element (6) connected thereto.

2. The implant of claim 1, c h a r a c t e r i s ¬ e d in that the hook-shaped fastening element is U-shaped.

3. The implant of claim 1 or 2, c h a r a c t e r ¬ i s e d in that the free end portion (2) of the hook- shaped fastening element is blunt, and that the cross-sec¬ tion of the fastening element is rectangular, round or oval.

4. The implant of any one of the preceding claims, c h a r a c t e r i s e d in that the fastening element (1) is folded by mechanical, chemical or electric means so as to be in a folded state when brought into engagement with the tissue, and is caused to expand in situ into engagement with the tissue, or is expanded at a certain temperature.

5. The implant of any one of the preceding claims, c h a r a c t e r i s e d in that it in addition com¬ prises one or more needles (11).

6. Implant unit, c h a r a c t e r i s e d in that it comprises the implant of any one of claims 1-4, as well as at least one fixing means (25, 26, 32).

7. The unit of claim 6, c h a r a c t e r i s ¬ e d in that the fixing means consists of one or more screws (25, 26, 32) or one or more compressible tubular elements.

8. Device for the insertion, displacement or removal of the implant of any one of claims 1-4, c h a r a c ¬ t e r i s e d in that it comprises an inner, hollow unit (14) adapted to accommodate the implant; a blunt, outer casing (20) to form the inner cavity containing the im- plant; and means (15-18, 21-23) for guiding the implant t the correct position.

9. The device of claim 7, c h a r a c t e r i s ¬ e d in that the means for. guiding the implant to the cor rect position comprises means (22, 23) for controlling th rotational movements of the inner, hollow unit in the outer casing, as well as means (15, 17) for locking the inner unit in relation to the casing.

10. Device for removal of a previously made implant according to any one of claims 1-4, c h a r a c t e r ¬ i s e d in that it comprises a tubular instrument (39) which is formed with a slit (40) for guiding the implant.

11. Method for inserting, displacing or removing the implant of any one of claims 1-4, c h a r a c t e r i s e d in that the implant is guided to or removed from a position in the tissue by means of the device set forth i any one of claims 8-10.