WO2010100287A1

WO2010100287A1 - Barrier for implantation into bone, in particular for vertebroplasty

Info

Publication number: WO2010100287A1
Application number: PCT/EP2010/052927
Authority: WO
Inventors: Danica Cervincova; Andreas Reindl; Mark Taylor; Jochen Borris; Michael Thomas; Frank Kniep; Dirk Hornscheidt; Thammo Weise
Original assignee: Somatex Medical Technologies Gmbh
Priority date: 2009-03-06
Filing date: 2010-03-08
Publication date: 2010-09-10

Abstract

The invention relates to a barrier for implantation into bone, in particular for vertebroplasty, the barrier having a bag (123) and at least one filling hole (126) to which a feeding device (121) for feeding a filler medium (119) is attachable, a closure apparatus (125) being provided on or in the filling hole (126) which closes or clogs automatically after completion of a filling of the bag (123) with filler medium (119).

Description

Barrier for implantation into bone, in particular for vertebroplasty

The invention relates to a barrier for implantation into bone, in particular for vertebroplasty, the barrier having a bag and at least one filling hole to which a feeding device for feeding a filler medium is attachable.

A barrier for receiving bone cement used in percutaneous kyphoplasty operations is known from US 2006/0217736 A1. This barrier is made of a resorbable material and has a filling hole on which a feeding device is provided. Once this barrier has been inserted into a cavity within a vertebral body that is to be filled, the barrier is filled with bone cement via the feeding device. The collapsed barrier expands until the cavity in the vertebral body is completely filled with bone cement. Subsequently, the feeding device is removed from the barrier bag. This arrangement has the disadvantage that bone cement may escape again from the barrier if the feeding device is separated from the barrier at a time when the bone cement has not yet cured. Waiting for the bone cement to cure would prolong the duration of the surgical operation and lead to an undefined point of separation between the barrier and the feeding device, on account of the partially cured bone ce- ment.

A barrier made of a resorbable material which is closed after filling with a bone cement within the vertebral body is known from WO 2006/112941 A1. In this example, the closing of the barrier is proposed to be realised by means of heat or via a bonding agent. Although this development of the barrier has the advantage that the filling hole is suggested to be closed at an early stage, when the bone cement has not yet completely cured, this configuration has, on the other hand, the disadvantage that the creation of such a closure is time-consuming and that, moreover, the introduction of heat or additional bonding material represents a further disadvantage. In addition, bone cement may escape until the closure of the filling hole is completed.

It is, therefore, an objective of the invention, to create a barrier for implantation into bone, in particular for vertebroplasty, which prevents filler medium from escaping during and after the filling operation, so that the barrier is realised in a leakage-free manner.

This objective is achieved according to the invention by means of a barrier having the characteristics of claim 1. Other advantageous configurations and developments are mentioned in the other, dependent claims.

The configuration of a barrier according to the present invention which has a closure apparatus that automatically closes or clogs during a transient interruption of the filling operation and/or subsequent to a completion of the filling operation with filler medium, in particular bone cement, has the advantage of permitting the realisation of a leakage-free arrangement. Thus, leakage of the filler medium, in particular bone cement, during or after the filling operation is prevented. The configuration of the barrier according to the invention with an automatically closing or clogging closure apparatus permits the utilisation of both low-viscosity and high-viscosity media as well as both slowly curing and rapidly curing bone cements. The automatically closing closure apparatus may in addition reduce the duration of a surgical operation, as the feeding device for feeding the filler medium may be removed immediately after completion of the filling of the barrier with the filler medium. Thus it is possible, by means of the barrier with the automatically closing closure apparatus, to prevent leakage formation in veins, in vessels, in the spinal channel of the intervertebral disc or in the paravertebral space.

According to a preferred configuration of the invention, an inward-turned portion is designed to be provided on the filling hole of the barrier, said inward-turned portion extend- ing at least partially into the interior of the bag and the passageway thereof being capable of closing after completion of the filling operation with the filler medium. Due to this arrangement of an inward-turned portion within the bag, it is possible for the passageway of the inward-turned portion to become progressively constricted, as the fill level of the filler medium increases. The filler medium progressively presses against the inward-turned portion and closes it as the filling operation is being completed. This has the advantage that after detaching or disengaging of the feeding device from the barrier, a leakage-free closure is created.

The inward-turned portion provided in the interior of the bag preferably has an outlet that is beak-shaped or slot-shaped when in an inactive position. This may ensure, on the one hand, an easy inflow of the filler medium into the bag, while enabling, on the other hand, an automatic closing of the outlet due to the beak-shaped or slot-shaped configuration thereof, since the end portions of the outlet are in tight contact with each other.

Furthermore, the configuration of the inward-turned portion is preferably designed to be disposed immediately adjacent to the filling hole, which has a round or a conical cross- section or any other cross-section suitable for receiving a feeding device and which turns into a slot-shaped outlet, a cross-section taper being provided between the filling hole and the slot-shaped outlet. Thus the automatic closing effect may be additionally assisted.

According to a further, alternative configuration of the invention, a taper directed towards the interior of the bag is designed to be provided on the filling hole. Even a slightly tapered portion on the filling hole is sufficient for the filling hole to clog rapidly. This permits a simplified configuration of the closure apparatus.

In an alternative configuration of the invention, the closure apparatus is designed to close automatically as soon as a pressure difference between an outside of the filling hole and an interior of the bag moves towards zero or the pressure in the interior of the bag is higher than the pressure present at the outside of the filling hole. Such a closure apparatus equally allows an automatic closing without any intervention from outside, said closing being controllable via the working pressure applied for feeding the filler medium to the barrier. As long as the filling operation is performed, the working pressure present on an outside of the filling hole is higher than the pressure in an interior of the bag. As soon as the working pressure present on the outside of the filling hole drops, for example because no further filler medium is being fed, the pressure in the interior of the bag becomes equal to, or higher than, the outside pressure, whereupon the closure apparatus closes automatically.

This closure apparatus, functioning according to the principle of pressure difference, is preferably realised in the form of a non-return valve inserted into the filling hole of the bag. This allows a simple design configuration and, additionally, assures a rapid closing of the filling hole so as to guarantee a leakage-free configuration. - A -

The non-return valve preferably comprises a valve member accommodated within a cage which is preferably realised in the form of a ball valve and, when in a closing position, closes a valve seating formed in particular on the cage. Thus it is possible to create a non-return valve, consisting, by way of example, of merely two components, and which closes automatically and reliably on account of the internal pressure present within the bag.

In an advantageous configuration, the closure apparatus, which functions according to the principle of pressure difference, is realised in the form of a diaphragm extending over the entire cross-section within the filling hole and having at least one longitudinal slot. This allows an opening of the preferably flexible diaphragm, as pressure is exerted by the filler medium on the outside of the filling hole. As soon as the pressure difference moves towards zero, this longitudinal slot closes automatically, preventing the filler medium from escaping from the bag via the filling hole. Preferably, a cruciform slot is designed to be provided which comprises for example four resilient diaphragm elements or lid-shaped members.

In a further advantageous configuration of the closure apparatus functioning according to the principle of pressure difference, said closure apparatus is provided in the form of lid- shaped closing members which extend over the entire cross-section within the filling hole. In particular, cusp-shaped closure members are provided which open if the flow of the filler medium is directed towards the interior of the bag and close if the flow is directed in the opposite direction. This configuration represents an alternative arrangement differing from the above-mentioned, slotted diaphragm. Preference is again given to elastic materials working by analogy with the principle that has been described above in connection with the diaphragm having at least one longitudinal slot.

In a further advantageous configuration of the closure apparatus functioning according to the principle of pressure difference, said closure apparatus is provided in the form of a reticulate diaphragm in which the width between meshes may be widened when exposed to a pressure increase. This arrangement is in addition accompanied by the operative principle of an increased surface area. On account of the presence of pressure during the filling operation with a filler medium, the reticulate diaphragm may undergo an increase in surface area which leads to a greater width between meshes so that a flow of the filling material therethrough is enabled. As the pressure drops, the mesh width is returned to a smaller size or is completely closed, so that a leakage-free arrangement is again created.

In a further alternative configuration of the closure apparatus functioning according to the principle of pressure difference, said closure apparatus is provided in the form of an elastic rubber lip which is spread apart to permit the feeding of a filler medium, contacting an outer periphery of the feeding device in a medium-tight manner, and which closes the filling hole after the feeding device has been disengaged. This configuration permits that the closure apparatus may be created without using any other components.

According to a further preferred configuration of the closure apparatus, an annular locking member is designed to be provided in the filling hole of the bag, a closure member being insertable into said locking member in order to close said filling hole. This makes it possible that once the closing, by means of a locking effect occurring between the closure member and the annular locking member, has been completed, a self-closing closure apparatus is provided.

Once the filling operation has been completed, the closure member applied to the annular locking member is preferably transferred into a locking position by means of a slide. The rest of the filler medium remaining in the feeding device may thus be transferred into the bag, after which a leakage-free closure may be created on the barrier. After the disen- gagement of the feeding device from the barrier, the closure member remains on the locking member, whereby again a leakage-free arrangement is created.

According to a further, preferred configuration of the invention, the bag is designed to be made of such a material, in particular a plastic material, that the bag is stretchable by a ratio of up to 400 %. This has the advantage that only a relatively small initial size of the barrier is required, thus enabling an easier insertion thereof via the feeding device. Despite the small initial size, it is possible to use the barrier in order to fill, and reliably seal, a space corresponding to as much as 400 % of the initial bag volume.

According to a preferred configuration of the invention, the bag is designed to be made of a resorbable material. The degree of resorption may be selected for the bag in accor- dance with a particular application.

According to a further preferred configuration of the invention, the bag is designed to be at least partially perforated. The filler medium may thus be caused to selectively escape. It is possible, for example, to define individual zones or regions for the escaping of filler medium. At the same time, it is possible, via the size of the perforation holes, to achieve a controlled escaping of filler medium within one such region.

According to another preferred embodiment, the bag is provided with protrusions on its exterior surface that help anchor the bag in its expanded state. An independent inventive aspect relates to an apparatus for expanding bone structures, in particular for the vertebroplastic treatment of fractured vertebrae. The apparatus can be used in a beneficial manner together the barrier disclosed hereinbefore and in the detailed description of the invention hereinafter.

An apparatus for expanding fractured vertebral bodies which has a drive member extending along an axis from a proximal end to a distal end of said apparatus is known from WO 2005/110259 A1. This drive member is guided within an insertion sleeve. At its distal end, said drive member has a widening device the proximal end of which abuts on the distal end of said insertion sleeve and the distal end of which is applied on an end piece mounted on said drive member. The widening device comprises at least one elastically deformable, tab-shaped member which expands as a working stroke is performed. For this purpose, a distance between the distal end of the insertion sleeve and the end piece is reduced, causing the elastically deformable, tab-shaped member to expand, forming a semicircle in a plane perpendicular to the longitudinal axis of the drive member. The deformable, elastic, tab-shaped members have the disadvantage, however, of not being sufficiently stiff, due to the flat, tab-shaped configuration thereof, so that an expanded position will not be stable. An outermost point of curvature may become displaced in one direction or the other along the extension of the longitudinal axis. Thus, it may not be possible, or only partially be possible, to exert the forces necessary for expanding the vertebral bodies.

It is therefore an object of the second invention to provide a widening apparatus which allows an easy and safe handling during the surgical operation as well as the transmission of great forces for the expansion of a bone structure.

This object is achieved by an apparatus for expanding bone structures, which uses a widening device in which the expansion member has at least two shanks and at least one expansion portion and in which said at least one expansion portion is provided as the central portion in the expansion member and is configured with inherent stiffness, provides the advantage that on actuating the widening device it is thus possible to transmit an increased expansion force to the bone structure in order to widen it. Moreover, due to the disposition and configuration of the at least two shanks and the expansion portion as a central portion, the expansion height and the widening direction may be adaptable according to a particular application. Due to the stiffened configuration of the expansion portion an enlarged contact surface is created on the bone structure to be expanded, thus preventing concentrated load application so as to avoid additional damage to the bone structure. According to a preferred configuration of the second invention, the at least one expansion portion of the widening device is designed to be expandable by reducing a distance between a distal and a proximal shaft end. Thus it is possible to actuate the widening device by a movement that consist in simply pulling or pushing a grip. This makes it possible, moreover, to create an apparatus having a very small diameter.

According to a further preferred configuration of the second invention, at least one stiffening member is designed to be disposed on at least one shank, in adjacent relation to said shank on one side or on both sides thereof, between a distal and a proximal shaft end of the widening device and the at least one expansion portion, and on actuating the widen- ing device at least one expansion portion is designed to be expandable in a controlled manner, in particular parallel to a longitudinal axis. Due to this arrangement of at least one stiffening member it is possible to achieve a controlled expansion movement of the expansion portion, as said stiffening member is disposed adjacent to the shank and therefore participates in the expansion movement. Thus it is possible to exert an influ- ence on the expansion portion. The at least one expansion portion is preferably designed to be expanded parallel to the longitudinal axis of the widening device. It may thus be achieved that once a fractured vertebral body, for example, has completely been expanded, the expansion portion contacts the fractured vertebral body with the largest possible surface in order to transmit a greatest possible force. Between the shank and the shaft portion of the widening device, a first buckling point is preferably provided. Between the shank and the connecting land portion another buckling point is preferably formed. Due to this arrangement, the expansion member, which consists for example of two shanks, may be provided with two defined buckling points and the shank portions lying therebetween may have a geometry permitting an inherently stiffened configuration. Thus, an expansion member that consists of two shanks may, for example, have a trapezoidal geometry as it assumes its expanded condition. Furthermore, additional buckling points may alternatively be provided between the first and the other buckling point. In this case, the elastically deformable member comprises several shanks. Depending on the number of buckling points, the elastically deformable member may then for example have a polygonal, deflected outer contour.

The first buckling point between the shank and the shaft portion of the widening device is preferably formed by two land portions formed by an intermediary buckling opening. Due to this opening in the buckling point a bending may occur without material change, as the shaft portion preferably has a slight curvature in the transition zone leading to the shank and a bending would necessitate an upsetting deformation in the lowermost region of the curvature. By means of this opening in the buckling region of the first buckling point, a plastic deformation of the land portions may be prevented. Since this configuration includes at least one additional stiffening member, the reduced load-bearing strength of the land portions may be compensated by means of the stiffening members. Preferably, a frusto-conical wall portion is provided in the buckling opening, whereby due to the enlarged perimeter of the opening on the outside of the widening device, which is preferably formed in the shape of a sleeve, a reduced notch effect will occur at the defined buckling point.

According to a further, preferred configuration of the second invention, at least one recess is provided between the shank and the expansion portion in order to form the other buckling point, said recess reducing the width of the shank and preferably extending from the longitudinal edge to the longitudinal central axis of the elastically deformable member. Said recess serves for forming the defined buckling point or serves as a buckling joint and reduces an upsetting deformation of the material on the periphery of the buckling point. In addition, the disposition of the recess, which is preferably provided on both sides of the expansion member along the longitudinal central axis thereof, has the advantage that a continuous contact surface is created therebetween, so as to enable or maintain a large-surface contact on the vertebral bodies. Alternatively, to form the other buckling point, a buckling opening might be provided, said opening being limited by the land portions provided laterally along the longitudinal edges of the shanks. The stiffening member has a recess for diameter reduction, situated preferably in the region of the other buckling point, which by analogy with the recess on the shank, is formed and oriented in such a way as to form the other buckling point. This recess of the other buckling point is therefore disposed point-symmetrically to the recess of the first buckling point on the stiffening member. This is particularly true of cases in which only one stiffening member is provided between the shaft portion and the expansion portion.

The at least one stiffening member corresponding to the shank has a first buckling point located in the transition zone leading to the shaft portion and another buckling point located in the transition zone leading to the expansion portion. Thus, defined buckling points are created between the shaft portion and the expansion portion, by analogy with the arrangement and integration of the shank, such that the stiffening member is deflected and expanded concurrently with the shank. Thus a stiffening of the shank and an increased transmission of ferees are achieved.

Furthermore, the stiffening member is preferably provided with a recess located on the first buckling point, extending from a longitudinal edge towards the longitudinal central axis of the stiffening member and disposed on the stiffening member opposite a longitu- dinal edge of the shank. Thus, a bending within the elastic range may take piace in an easy and simple manner such that during the expansion of the shank a restricted guidance by the stiffening member occurs, supporting the expansion movement of the shank.

The other buckling point between the stiffening portion and the expansion portion is preferably formed by analogy with the first buckling point, wherein the recess is located on an opposite side, such that the deflection of the stiffening member relative to the expansion member in the other direction is equally facilitated.

According to another preferred configuration of the second invention, a hole with an open rim is designed to be provided in the transition zone leading from the shank and the adjacent stiffening member to the shaft portion. Thus a notch effect may be prevented and the risk of tear on account of the stresses occurring during the expansion of the shank and the stiffening member extending parallel thereto may be prevented.

Furthermore, the holes with open rims are designed to be equally provided in the transition zone leading from the shank and the adjacent stiffening member to the expansion portion. Thus it is possible, for each shank, to create identical conditions in the transition zone leading to the shaft portion and the expansion portion.

Preferably, two opposing, elastically deformable members are designed to form a sleeve and to expand in opposed directions in a plane perpendicular to the longitudinal axis of the widening device. The shanks and the stiffening members are preferably formed by means of cuts realised in the sleeve, such that the round outer contour of the widening device in a starting position is maintained. Thus the shanks, the expansion portion as well as the stiffening members are formed as one piece and are integral with the sleeve wall.

According to a further, preferred configuration of the second invention, an energy storing member is applied to at least one expansion portion of the widening device, permitting to actuate said at least one expansion portion in the widening direction. Thus it is possible, for example, once an interlock on a widening device or an interlock that is connected to a widening device has been released, to enable a power-assisted or automatic expansion by means of the energy storing member. The energy storing member may be in the form of a pressure spring, for example, or of some other elastically expandable member.

According to a further, alternative configuration of the second invention, a drive member is applied to at least one expansion portion of the widening device, said drive member being operated electrically, pneumatically or hydraulically. Said drive member may be realised as a driving gear, a sliding mechanism, or the like. In a further, alternative configuration of the second invention, the at least two shanks accommodating at least one expansion portion are formed of a material that is more elastic as compared to the expansion portion. This permits to achieve an elastic deformation of the shanks and at the same time a concerted expansion of the expansion portion.

The invention, as well as other advantageous embodiments and developments thereof, will be described and explained in the following with reference being made to the examples shown in the drawings. The characteristics issuing from the description and the drawings may be applied according to the present invention either individually or as a plurality of features taken in any combination. In the drawings:

Figures 1a to d are schematic views of individual steps of an operation method using the barrier of the present invention,

Figures 2a to c are schematic views of a first embodiment of the barrier according to the invention provided with a closure device,

Figures 3a to c are schematic views of an alternative embodiment of the closure device differing from Figures 2a to c,

Figures 4a to c are schematic views of an alternative embodiment of the closure device differing from Figures 2a to c,

Figures 5a to c are schematic views of an alternative embodiment of the closure device differing from Figures 2a to c,

Figures 6a and b are schematic views of an alternative embodiment of the closure device differing from Figures 2a to c,

Figures 7a and b are schematic views of an alternative embodiment of the closure device differing from Figures 2a to c,

Figures 8a and b are schematic views of an alternative embodiment of the closure device differing from Figures 2a to c.

Figure 9 is a schematic view of an apparatus according to the present invention prior to the expansion of a fractured vertebral body;

Figure 10 is a schematic view of an apparatus according to the present invention during the expansion of a fractured vertebral body; Figure 11a is a schematic side view of a widening device in a starting position;

Figure 11 b is a perspective view of the widening device according to Figure 3a in a working position;

Figure 12a is a schematic side view of an alternative widening device in a starting position;

Figure 12b is a perspective view of the widening device according to Figure 4a in a working position, and

Figure 12c is a perspective view of an alternative widening device according to Figures 4a and 4b.

Figures 1 a to 1 d schematically show a minimally invasive operation technique in the form of individual working steps illustrating the augmentation of a fractured vertebral body and the subsequent vertebroplasty. In the course of this procedure, the barrier 111 formed according to the present invention is used.

According to this method of operation, a fractured vertebral body according to Figure 1a is designed to be prepared for a subsequent expansion operation. For this purpose, a cannula 112 is inserted, for example through the pedicle. Then the fractured region of the vertebral body may be treated by means of a drill, which is not shown. After this, an apparatus 114 for expanding vertebral bodies is used in order to reduce the vertebral body so as to restore a planned height of the vertebral body. This is done with the help of an widening device or an expansion member having elastically deformable members which may assume the depicted, widened position. After the expansion, or reduction, of the vertebral body, a cavity 116 is formed within the fractured vertebral body. A filler medium 119, in particular bone cement, is introduced into said cavity 116 by means of an injection apparatus 118 so as to completely fill said cavity 116 with said filler medium 119. The injection apparatus 118 comprises at least one feeding device 121 and a barrier 111 disposed on the distal end thereof and which is introduced into the cavity 116 via the cannula 112. Subsequently, by means of the feeding device 121 of the injection apparatus 118 the filler medium 119 is introduced into the interior of the barrier 111 , which widens according to Figure 1c until the cavity 116 is completely filled, as is shown in Figure 1 d. Next, the feeding device 121 is separated from the barrier 111 and the cannula 112 is removed. The components remaining within the vertebral body, i.e. the barrier 111 and the filler medium 119, serve to fix and stiffen the fragile, osteoporotic or fractured vertebral body in the expanded position. The patients may thus obtain an immediate reduction of pain and recover a better posture and, consequently, an amelioration in their quality of life.

Thus, a method for augmentation of a fractured vertebral body comprises the steps of:

- Inserting a cannula 112, for example through the pedicle.

- Optionally treating a fractured region of the vertebral body by means of a drill.

- Expanding the vertebral body by means of apparatus 114 in order to reduce the vertebral body so as to restore a planned height of the vertebral body.

o Expansion is preferably done with the help of a widening device or an expansion member having elastically or plastically deformable members which may assume the depicted, widened position.

- Forming a cavity 116 within the fractured vertebral body after the expansion, or reduction, of the vertebral body.

- Introducing a filler medium 119, preferably bone cement, into said cavity 116 by means of an injection apparatus 118 so as to completely fill said cavity 116 with said filler medium 119. The injection apparatus 118 comprises at least one feeding device 121 and a barrier 111 disposed on the distal end thereof and which is introduced into the cavity 116 via the cannula 112.

- Introducing the filler medium 119 into the interior of the barrier 111 by means of the feeding device 121 of the injection apparatus 118. As a result, the barrier 111 widens according to Figure 1c until the cavity 116 is completely filled, as is shown in Figure 1d.

- Separating the feeding device 121 from the barrier 111 and

- Removing the cannula 112.

Details of a preferred apparatus 114 and a preferred widening device are disclosed in Figures 9 to 12.

Figures 2a to 2c schematically show different views of a first configuration of the barrier 111 according to the present invention. The barrier 111 comprises a bag 123 which encloses an interior 124 for holding the filler medium 119. The interior 124 is accessible via a filling hole 126 arranged in the bag 123, said filling hole being adjoined by an in- ward-turned portion 127 which extends into the interior 124. Preferably, the inward-turned portion 127 is formed as an integral part of the filling hole 126. Alternatively, the inward- turned portion 127 may also be designed to be joined to the filling hole 26 by bonding or welding. The filling hole 126 preferably has a region into which the feeding device 121 or the distal end thereof is insertable so as to be joined with the filling hole 126 by positive and/or non-positive connection. This first region is adjoined by a cross-section taper 128. Then, the cross-section of the passageway 129 of the inward-turned portion 127 changes in such a way that it turns into a slot-shaped outlet 131. This slot-shaped outlet 131 is beak-like, with two flat edge portions contacting each other in a planiform manner so as to close the slot-shaped outlet 131 when no filler medium is flowing through the passageway 129.

The outlet 131 is preferably located in a central region of the interior 124 of the bag 123. This makes it possible, that after the inflow or the introduction of a filler medium 119 into the interior 124 the filler medium 119 may also reach the region of the cross-section taper 128 and that, as the bag 123 progressively fills with the filler medium 119, the cross- section taper 128 is subject to constriction and at the same time a compressive force is exerted on the edge portion of the slot-shaped outlet 131 , so that after the detaching of the feeding device 121 from the filling hole 126 the closure apparatus 125 is caused to close automatically. Due to the configuration according to the invention a leakage-free closure apparatus 125 is created which closes automatically the moment no further filler medium 119 is introduced into the bag 123 or a predefined degree of filling has been reached. Said inward-turned portion 127 is preferably made of the same material as the bag 121. This may involve the utilisation of resorbable materials or other materials. The relationships between size and thickness of the bag 123 as depicted in Figures 2a to 2c are merely exemplary. Different sizes may be provided for differently sized cavities 116 and corresponding geometries.

The inward-turned portion shown in Figures 2b and 2c may also be realised in a considerably shorter form.

In another preferred embodiment, not shown, the filling hole 126 may be designed to be provided with a taper which extends into the interior 124 and is realised short, forming what might be considered a tapering rim of the filling hole 126. This preferred configuration also permits a rapid, automatic clogging of the filling hole. Figures 3a to 3c show an alternative embodiment of a closure apparatus 125 for the barrier 111 permitting a leakage-free removal of the feeding device 121 leading to the barrier 111.

This closure apparatus 125 is realised in the form of a non-return valve. This non-return valve is comprised, for example, of two components: a cage 133 having a valve seating 134 immediately adjacent thereto and a valve member 136 which contacts the valve seating 134 when in a seated position. The valve member 136 is preferably realised in the form of a ball valve and is lodged within the cage 133. The non-return valve is inserted into the filling hole 126 and is fixedly retained therein. As filler medium 119 is fed via the feeding device 121 , the non-return valve opens so as to permit access of the filler medium 119 to the interior 124 of the bag 123. As soon as the pressure on an outside of the filling hole 126 drops, or the pressure difference between the interior 124 of the bag 123 and the outside of the filling hole 126 moves towards zero or is equal to zero, the valve member 36 is automatically brought back to the valve seating 134 so that the closure apparatus 125 closes. So, this closure apparatus 125 functions according to the principle of a pressure difference before and behind the filling hole 126.

Figures 4a to 4c show an alternative configuration of the closure apparatus 125. This closure apparatus 125 functions equally according to the principle of a pressure difference before and behind the filling hole 126, or before and behind the closure apparatus 125. This closure apparatus 125 is realised in the form of a diaphragm 141 extending over the entire diameter of the filling hole 126. The diaphragm 141 has at least one longitudinal slot 142 which permits the filler medium 119 to pass through the longitudinal slot 142 and enter the interior 124 of the bag 123 when the pressure before the closure apparatus 125 is at an increased level. The moment the pressure in the interior 124 is equal to, or higher than, the pressure outside the interior 124, the longitudinal slot 142 of the diaphragm 141 will close. This situation occurs as the feeding device 121 is being detached from the barrier 111 , such that again a leakage-free closure is provided on the barrier 111 which locks and prevents leakage of the filler medium 119 from the bag 123. As an alternative to the longitudinal slot 142, a cruciform slot or other slotted configura- tions may be provided.

Figures 5a to 5c show an alternative configuration of a closure apparatus 125 differing from the closure apparatus 125 according to Figures 4a to 4c. Instead of a slotted diaphragm 141 , the closure apparatus 125 has cusp-shaped closure members 144 which open if a pressure on the outside is higher than in the interior 124 and which automati- cally close if the pressures present on the outside of the filling hole 126 and in the interior 124 are equal or if the pressure in the interior 124 is higher. By way of example, four symmetrically assigned closure members 144 may be provided.

Figures 6a and 6b show another alternative configuration of the closure apparatus 125.

This closure apparatus 125 comprises a reticulate diaphragm 146 that extends equally over the entire cross-section within the filling hole 126. Said reticulate diaphragm 146 or perforated film allows a widening of the individual meshes 147 during the filling operation with a filler medium 119, so that the filler medium 119 may flow through the reticulate diaphragm 146. As soon as the pressure difference is no longer present, the mesh size of the reticulate diaphragm 146 returns to its initial state and prevents the filler medium 119, in particular bone cement, from escaping to the outside through the filling hole 126.

Figures 7a and 7b show a further alternative configuration of a closure apparatus 125. In this embodiment, an annular locking member 151 is inserted into the filling hole 126, said locking member being preferably attached by means of a non-detachable connection such as bonding, clamping, welding or the like. Alternatively, the locking member 151 may be inserted into the filling hole 126 in such a way as to be replaceable. Through the filling hole 26 of the annular locking member 151 , the filler medium 119 may be introduced into the interior 124 of the bag 123. When the filling operation is almost entirely completed, a closure member 144 is proximally inserted into the feeding device 121. Subsequently, the closure member 152 is pushed towards the locking member 151 by means of a slide 153 such that the closure member 144 and the locking member 151 get caught on each other so as to completely close the filling hole 126. Thus, a leakage-free configuration of the barrier 111 has again been created.

Figures 8a and 8b show a further alternative configuration of a closure apparatus 125. The closure apparatus 125 comprises a rubber lip 156 which is elastically configured. For fiiiing the barrier 111 with the filler medium 119, the rubber lip 156 is spread apart and the end of the feeding device 121 is inserted into the bag 123 through the spread-apart rubber lip 156. The rubber lip 156 fits tight around the outer periphery of the feeding device 121. After completion of the filling operation, the feeding device 121 is detached from the filling hole 126 and the rubber lip 156 closes the spread-apart opening. Thus, a closure apparatus 125 is created which closes automatically after the feeding device 121 has been detached.

All of the above-mentioned closure apparatuses 125 have the advantage of being leakage-free during and after the filling operation with a filler medium 119, in particular bone cement. Figure 9 shows an apparatus 211 for expanding bone structures and, by way of example, for expanding fractured vertebral bodies 212. The apparatus 211 corresponds to apparatus 114 of Figure 1.

Said apparatus 211 comprises a grip 214 by means of which a widening device 217 is converted, via a drive member 216, from a starting position 218 into a working position

219 for widening the vertebral bodies 212, as represented in Figure 10. The widening device 217 abuts on a distal end of the drive member 216 whereat an end piece 221 is provided. The proximal end of the widening device 217 is applied to an insertion sleeve

222 that surrounds the drive member 216. The drive member 216 is disengageably connected to the grip 214. The drive member may be arranged as a flexible rod or flexible tube, as a Bowden cable or the like.

This apparatus 211 is used in particular in minimally invasive surgical operation techniques in the fields of kyphoplasty and also vertebroplasty. For this purpose, the fractured vertebral body is first probed by means of a cannula 224. Then a cutter may be inserted via the cannula in order to remove the fractured parts from within the vertebral body. Afterwards, the apparatus 211 according to the present invention is inserted via the cannula 224. By actuating the grip 214 the widening device 217, including the elastically deformable expansion members 226 thereof, is caused to expand. In doing so, an expansion force is conveyed to the vertebral body in such a way as to achieve a reduction of the vertebral body. In order to facilitate this reduction, the patient may be placed in a sagging position. After completion of the reduction, the apparatus 211 is removed and the cavity created within the vertebral body is filled with bone cement.

The widening device 217, which is only diagrammatically shown in Figures 9 and 10, is schematically represented to a larger scale in a starting position 218 in Figure 11 a, and is schematically represented to a larger scale in a working position 219 in Figure 11 b.

The widening device 217 consists of a tube-shaped or sleeve-shaped main body or a sleeve 231. Said sleeve 231 is slipped upon the drive member 216. In order to convert the widening device 217 from a starting position 218 into a working position 219, a distance between a proximal end 232 and the distal end 233 of the widening device 217 is reduced. This causes the elastically deformable expansion members 226 to expand in a plane perpendicular to the longitudinal axis 234 of the drive member 216. In the embodiment shown the widening device 217 comprises two opposing, elastically deformable expansion members 226. It should be understood that the widening device 217 may have only one elastic expansion member 226 or may have several elastically deformable expansion members 226. The elastically deformable expansion members 226 comprises two shanks 236 extending between a shaft portion 237 and an expansion portion 238. The expansion portion 238 in turn connects the two shanks 236. The shanks 236 have a cross-section in the form of a quarter circle. This provides a stiffening of the shanks 236 along said cross-section.

A stiffening member 241 is provided adjacent to the shank 236. This stiffening member 241 preferably extends along a longitudinal edge 242 of the shank 236 and is applied on the shaft portion 237 as well as on the expansion portion 238. In this embodiment, a stiffening member 241 is provided on each shank 236 on both sides thereof, respectively. It should be understood that it is equally possible to have only one stiffening member 241 that may be provided on only one shank 236 of the elastically deformable member 226. The number of stiffening members 241 may vary in accordance with a particular application.

As seen in cross-sectional view, the stiffening members 241 are configured in an almost rectangular shape, providing a very slight curvature due to the curvature of the wall of the sleeve 231.

Between the shaft portion 237 and the shank 236, a first buckling point 244 is formed. Said buckling point comprises a buckling opening 246 which has a bore edge 247 that is configured in a frusto-conical shape. The smaller conical surface thereof is oriented towards the longitudinal central axis 234. Because of the radial extension of the buckling opening 246, the shank 236 is connected with the shaft portion 237 via land portions 248. These land portions 248 form a articulation which makes it possible to avoid a plastic deformation in the region of the land portions 248 when the elastic members 226 are expanded.

The shank 236 is connected to the expansion portion 238 via another buckling point 244. Said other buckling point 244 is formed by two opposing recesses 252 oriented from the longitudinal edge 242 towards the longitudinal central axis 253. This leads to a reduction in diameter which facilitates a bending of a contact surface 255 from the vertebral body. The contact surface 255 extends over the entire elastically deformable member 226, preferably in a continuous manner, in order to allow a large-surface contact during the expansion of the vertebral body.

For the purpose of stiffening the shanks 236 and of expanding the shanks 236 with greater force and orienting them, the stiffening members 241 are configured in a parallel way. These stiffening members 241 assume a guiding in the form of a parallelogram or a parallel guiding and assume part of the supporting force. At the first buckling point 244 and the other buckling point 51 , the stiffening members 241 have respective recesses 252 that are oriented point-symmetrically with respect to one another. In said other buckling point 244, the orientation of the recess is identical with that in the shank 236. In the first buckling point 244, the recess 252 is point-symmetrical with the recess 252 of the other buckling point 244. It can thus be achieved that the central portions of the stiffening members 241 and the longitudinal edges of the shanks 236 are oriented substantially parallel to each other.

In the transition zone between the land portions 248 and the stiffening member 241 leading to the shaft portion 237, a hole 258 with an open rim is provided. Said hole serves for reducing the notch effect and tear initiation at the transitions toward the individual elements. Such holes 258 with open rims are provided at those locations in the sleeve 231 at which a cut serving to form the deformable member in the sleeve 231 terminates. Therefore, a hole 258 with an open rim is also provided, for example, between two stiffening members 241 at the transition leading toward the shaft portion 237.

Through the arrangement of the stiffening members 241 , the expansion of the widening device 217 can be achieved in such a way that for example the expansion portion 238 is oriented parallel to the longitudinal axis 234, which makes it possible to achieve a defined expansion movement. This expansion is further favoured by the fact that the elastic member 226 is symmetrically configured with respect to the shanks 236 and the neighbouring stiffening members 241.

Alternatively, the lengths of the shanks and, accordingly, the stiffening members 241 may be designed in such a way as to differ from one another. The elastically deformable member 226 may furthermore be designed to comprise three or more shanks arranged adjacent to one another and preferably connected to an expansion portion 238. The stiffening members 241 accordingly present an analogous structure and an analogous disposition.

In order for the widening device 217 to be positioned in a defined manner relative to the insertion sleeve 222 and/or the grip 214, a retainer 261 permitting a location in correct positional arrangement is provided. Said retainer 261 may be provided as a recess with an open rim. It is also possible to have a depression provided in the end portion of the tube-shaped or sleeve-shaped widening device 217, such that a bolt or pin of the insertion sleeve 222 may engage therewith in order to ensure a rotationally safe accommodation of the widening device 217 relative to the drive member 216 and/or to the grip 214. Thus it is possible to ensure in a simple manner a defined orientation of the widening device 217 after its insertion into the cannula 224. The drive member 216 may furthermore preferably be designed to present a taper in the region of the widening device 217 which may serve as a reservoir for bone particles that may become detached in the course of the expansion.

For locating the position of the widening device 217, a guiding mark or scale may be provided on the grip 214. Furthermore, a guiding mark may advantageously be provided between the grip 214 and the shaft in order to make it possible to assess the direction in which the widening device works. This is of particular importance if there exist only two expansion portions working in opposite directions, as is the case in the present embodiment. The grip 214 may additionally be provided with a lever or with a mechanism permit- ting the widening device to be actuated and expanded in an easier manner. In addition, suitable locking devices, such as bayonet lockings, may preferably be provided in the connection zone between the grip 214 and the drive member 216 as well as the cannula 224 in order to prevent detaching or unintentional twisting.

In order to assist the expansion movement of the expansion portions 238, the widening device 217 may be designed to be exposed to a bias, such that a lower expansion force needs to be applied than in cases where the starting position has a sleeve-shaped cross- section. This might be realised by providing an expansion portion 238 having a starting position which - rather than being in the form of a sleeve-shaped cross-section - is configured in such a way that the expansion portion 238 is already at least slightly elevated relative to the driving member 216, whereby said bias is created.

The widening device 217 is preferably made of nitinol. Other materials generally referred to as surgical materials may equally be used.

Figures 12a and 12b show an alternative configuration of a widening device 217 differing from the embodiment according to Figures 11a and 11b. As far as the coinciding features are concerned, fully extensive reference is made to Figures 11a and 11 b as well as to their alternative embodiments. In the following, only the differences will be described in greater detail.

In this widening device 217 the two shanks 236 disposed between the expansion portion 238 and the ends 32, 33 of the widening device 217 are each realised in the form of two shanks 236 arranged in pairs with respect to each other. Thus it is possible to achieve the same expansion effect as with the embodiment according to Figures 11a and 11b. The two shanks 236 arranged in pairs with respect to each other may correspond, in this embodiment, to the stiffening member 241 in Fig. 11b. In this embodiment, the expansion portion 238 stretches not merely between the two buckling points 244 but has an extension portion 264 that prolongs the expansion portion 238 on one side or, in particular, on both sides. This permits to create a prolonged contact surface along the longitudinal axis 234 of the widening device 217.

Preferably, the expansion portion 238 with its extension portions 264, and together with the shanks 236 arranged in pairs, may be disposed in a starting position 218 in which, as shown in Fig. 12a, the cross-section assumes the shape of a sleeve.

Figure 12c shows another alternative configuration of a widening device 217 differing from the embodiment according to Figures 11a and 11 b. This widening device 217 corre- sponds basically to the embodiment according to Figures 11a and 11 b, to which reference is made, the expansion portion 238 being in addition provided with extension portions 264. These extension portions 264 may respectively be attached to the expansion portion 238. Alternatively, one single extension portion 264 may be provided in the region of the expansion portion 238 and attached thereto. This permits to achieve the same advantages as with the embodiment according to Figure 12b.

List of reference nummerals

111 barrier

112 cannula 114 apparatus

116 cavity

118 injection apparatus

119 filler medium 121 feeding device 123 bag

124 interior

125 closure apparatus

126 fiiiing hole

127 inward-turned portion 128 cross-section taper

129 passageway

131 outlet

133 cage

134 valve seating 136 valve member

141 slotted diaphragm

142 slot

144 closure member

146 reticulate diaphragm 147 meshes

151 locking member 153 slide

156 rubber lip

211 apparatus

212 vertebral bodies 214 grip

216 drive member

217 widening device

218 starting position

219 working position 221 end piece

222 insertion sleeve

224 cannula

226 elastic deformable expansion members

231 sleeve 232 proximal end

233 distal end

234 longitudinal axis

236 shanks

237 shaft portion 238 expansion portion

241 stiffening members

242 longitudinal edge 244 buckling point 246 buckling opening 247 bore edge

248 land portions 251 another buckling point

252 recess

253 central axis 255 surface 258 hole 261 retainer 264 extension portions

Claims

1. A barrier for implantation into bone, in particular for vertebroplasty, which has a bag (123) and at least one filling hole (126) to which a feeding device (121 ) for feeding a filler medium (119) is attachable, characterised in that a closure apparatus (125) is provided on or in said filling hole (126) which closes or clogs automatically after completion of a filling of the bag (123) with filler medium (119).

2. The barrier of claim 1 , characterised in that an inward-turned portion (127) is provided on the filling hole (126), said inward-turned portion extending at least partially into an interior (124) of the bag (123) and the passageway (129) thereof closing or clogging automatically after completion of the filling operation with the filler medium (119).

3. The barrier of claim 2, characterised in that the inward-turned portion (127) has an outlet (131 ) that is turned towards the interior (124) of the bag (123) and is beak-shaped or slot-shaped when in an inactive working position.

4. The barrier of claim 2 or 3, characterised in that the inward-turned portion (127), starting from a preferably round filling hole (26), turns into the slot-shaped outlet (131 ), a cross-section taper (28) being provided between the filling hole (126) and the slot-shaped outlet (131 ).

5. The barrier of claim 1 , characterised in that a taper directed towards the interior of the bag (123) is provideϋ on the filling hole (126).

6. The barrier of claim 1 , characterised in that the closure apparatus (125) closes automatically as soon as a pressure difference between an outside of the filling hole (126) and the interior (124) of the bag (123) moves towards zero or the pressure in the interior (124) of the bag (123) is higher than the pressure present at the outside of the filling hole (126).

7. The barrier of claim 6, characterised in that the closure apparatus (125) is realised in the form of a non-return valve which is provided in the filling hole (126).

8. The barrier of claim 7, characterised in that the closure apparatus (125) has at least one valve member (136) accommodated within a cage (133) which, when in a closing position, preferably closes a valve seating (134) formed on the cage (133).

9. The barrier of claim 6, characterised in that the closure apparatus (125) is realised in the form of a diaphragm (141 ) extending over the entire cross-section within the filling hole (126) and comprising at least one longitudinal slot (142), preferably a cruciform slot.

10. The barrier of claim 6, characterised in that the closure apparatus (125) is provided in the form of closure members (144) which have a lid-shaped, preferably cusp-shaped, form and which open and close the filling hole (126).

11. The barrier of claim 6, characterised in that the closure apparatus (125) is realised in the form of a reticulate diaphragm (146) in which the width between meshes (147) may be increased under exposure to a pressure rise due to the filler medium (119) that is to be fed.

12. The barrier of claim 1 , characterised in that the closure apparatus (125) is real- ised in the form of an elastic rubber lip (156) which may be spread apart to permit the feeding of the filler medium (119) and which surrounds an outer periphery of the feeding device (121 ) contacting it in a medium-tight manner, and which closes the filling hole (126) after the feeding device (121 ) has been detached from the spread-apart rubber lip (156).

13. The barrier of claim 1 , characterised in that the closure apparatus (125) has an annular locking member (151 ) which is disposed in the filling hole (126) of the bag (123) and into which a closure member (152) is insertable in order to close said filling hole (126).

14. The barrier of claim 13, characterised in that the closure member (152) may be positioned in a locking position with the locking member (151 ) by means of a slide

(153).

15. The barrier of any of the preceding claims, characterised in that the bag (123) is made of such a material, in particular a plastic material, that the bag is stretch- abie by a ratio of up to 400 %.

16. The barrier of any of the preceding claims, characterised in that the bag (123) is made of a resorbable material.

17. The barrier of any of the preceding claims, characterised in that the bag (123) is at least partially perforated.

18. The barrier of any of the preceding claims, characterised in that the bag (123) is provided with protrusions on its exterior surface that help anchor the bag in its expanded state.

19. A method of augmenting a fractured vertebra) body comprising the steps of;

Inserting a cannula into a fractured vertebral body;.

Expanding the vertebral body in order to reduce the vertebral body so as to restore a planned height of the vertebral body;

- Forming a cavity within the fractured vertebral body;

Introducing a filler medium into said cavity using an injection apparatus so as to completely fill said cavity with said filler medium, wherein said injection apparatus comprises at least one feeding device and a barrier according to claims 1 to 18 disposed on the distal end thereof;

- Introducing the filler medium into the interior of the barrier by using a feeding device of the injection apparatus;

Separating the feeding device from the barrier; and

Removing the cannula.

20. The method of claim 19, further including the step of treating a fractured region of the vertebral body by means of a drill after the step expanding the vertebral body and prior to introducing a filter medium into said cavity.