DEVICE FOR ATTACHING A FLAT BAND ON A BONE PART

Abstract

A device for attaching a flat and flexible band on at least one bone part, comprising the band having two end portions, a rigid base body crossed by an opening, and a retaining part that can be inserted in the opening. The retaining part is at least partially in the shape of a squeezable wedge comprising a central bore for passage of the end portions facing the flexible band, the bore having a transverse cross-section that can be deformed between a first cross-section for free passage of the end portions when the part has not been inserted in the opening and a second cross-section for locking the end portions by compression when the part is entirely or substantially entirely inserted in the opening.

Description

The present invention relates to a device for attaching a flat and flexible band on at least one bone part.

It also relates to a method for attaching a flat and flexible band using such a device.

It has a particularly important but not exclusive application in the consolidation of the vertebral column and, in particular, in the union of two vertebrae in cases of damage.

It is known that the intervertebral discs may be subject to compression, herniation, or arthritic intervertebral degeneration.

To manage the patients, there are techniques that require a surgical intervention.

A first technique involves replacement of the damaged disc with an intervertebral disc prosthesis. Such a replacement procedure is difficult for the surgeon to perform and poses a risk of loosening under the effect of the considerable shearing forces that arise in particular when the prosthesis is in the position of maximum flexion.

A second technique involves performing intervertebral arthrodesis, an operation by which the two vertebrae adjacent to the damaged disc can be fused. This blocks the degeneration of the disc, on account of the suppression of any mobility between the two vertebrae concerned.

Such a technique entails the use of a device for stabilizing the two vertebrae, said device generally having screws which are intended to be screwed into the vertebrae and connected to each other by a rigid connection member. It is thus possible to avoid excessive mechanical stresses being applied to the intervertebral disc.

Here again, there are disadvantages in particular in requiring screwing into the vertebrae, which is a structurally aggressive operation that weakens the vertebrae concerned, or which is in fact impossible if said vertebrae are in a poor condition and/or are insufficiently wide at the attachment region.

Another technique involves the use of hooks. This approach, however, is a very delicate one, since the operating surgeon must not touch the spinal cord, in order to avoid paralyzing the patient. These are also risks of the hooks slipping and/or of the hooks coming loose.

The present invention aims to make available a device which serves for attachment on a bone part and which is better than the previously known devices in terms of meeting the demands that arise in practice, especially as it is not limited to attaching at least two bone parts to each other, it permits greater flexibility, it avoids any intrusion into the bone, and it poses no risk of slipping and/or of losing tension on the vertebrae, all this at a low cost and/or at less cost than with the devices of the prior art.

It also has the advantage of permitting easy handling of the flexible band, allowing the latter to be easily placed around the bone parts by the surgeon.

To this end, the invention proposes in particular a device for attaching a flat and flexible band on at least one bone part, comprising said band having two end portions, a rigid base body with a through-opening, and a retaining component that is insertable in said opening, characterized in that the retaining component is at least partially in the shape of a squeezable wedge comprising a central bore for passage of said opposite end portions of the flexible band, said bore having a cross section that is deformable between a first cross section for free passage of the end portions when the component has not been inserted in the opening, and a second cross section for blocking said end portions by compression when the component is entirely or substantially entirely inserted in the opening.

In advantageous embodiments, use is also made of one or more of the following arrangements:

• • With the base body extending about an axis, the opening has a first longitudinal cross section that is an isosceles trapezoid or substantially an isosceles trapezoid in a first axial plane with a first angle at the base a, and the retaining component has a second longitudinal cross section that is an isosceles trapezoid or substantially an isosceles trapezoid in said first axial plane with a second angle at the base b>a.

Substantially trapezoidal means a cross section of geometric shape in which the sides of the trapezoid have a periphery inscribed within a trapezoid but are not necessarily linear or formed by a straight line (by being toothed, for example).

• • The retaining component comprises two opposite longitudinal end walls, each of the longitudinal end walls being provided with a continuous slit which is arranged on a portion of said wall, is open to the bore and opens out on the upper face of the component.

The slits or cuttings promote the squeezing of the component during its introduction with force into the opening, while at the same time permitting from the outset a bore that is as wide as possible, which makes it easier for the ends of the band to be introduced and passed through before compression.

• • The inner face of the opening and the outer peripheral face of the component comprise means for pre-connection to each other by snap-fit action.

These means for pre-connection have a role as non-return means permitting preliminary assembly of the device, for example to avoid the various elements of the device coming apart in a transporting package and then having to be looked for and put together by the surgeon at the time of the intervention.

• • The inner face of the opening of the body and the outer peripheral face of the component have means constituting a system for blocking the component with respect to the body when the component is inserted in the opening.
  • The bore and the component each have a longitudinal plane of symmetry, respectively defining two opposite inner longitudinal faces for the opening and two opposite outer peripheral longitudinal faces for the component, each opposite face having at least one portion provided with at least one tooth or rib for fastening and blocking the component with respect to the body when the component is inserted in the opening.

These fastening means permit preliminary positioning in the alignment of the elements with respect to each other, which will allow them to be compressed easily by ancillary gripping forceps of a design known to a person skilled in the art.

They likewise constitute a non-return system that prevents disassembly of the component and of the body when the component is inserted in the body.

• • The outer peripheral longitudinal faces of the component are at least partly inclined with respect to the plane of symmetry in order to give the wedge shape.
  • The bore has a cross section of oblong shape and has two opposite main walls, at least one main wall comprising, on its inner face, at least one inwardly protruding transverse rib. Advantageously, it comprises two opposite ribs which are offset in height.
  • The protruding transverse rib is situated in the upper longitudinal part of the bore.
  • The bore and the retaining component are of shapes that are designed to cooperate by friction on at least one of their opposite parts in the direction perpendicular to the first longitudinal plane when the component is inserted in the opening.
  • The component has a core hollowed out by the bore, of general oblong shape, comprising two opposite inclined main walls forming the wedge and two end walls extending about an axis, of which the faces are arranged to cooperate longitudinally with a corresponding recessed part of the opening, the thickness of the junctions between main walls and end walls being reduced and designed to permit the deformation by squeezing in the transverse direction without deformation in the longitudinal direction during insertion of the component in the opening.

Such an arrangement allows the component to deform in one plane, in the desired direction of wedging, while maintaining an excellent guiding capacity without deformation/expansion in the other plane perpendicular to the first one.

Advantageously, the end walls extending about an axis are each provided with at least one transverse slit along part of its height to promote squeezing.

• • The base body is made of titanium, the retaining component is made of polymer, and the flexible band is a polymer braid.

The invention also relates to a method for attaching a flat and flexible band on at least one bone part, comprising said band provided with two end portions, a rigid base body with a through-opening, and a retaining component that can be inserted into said opening, characterized in that, with the retaining component being in the shape of a squeezable wedge comprising a central bore for passage of said opposite end portions of the flexible band, an end portion of the band is introduced into the opening and into the bore, the component being connected partially (beforehand or subsequently) in the opening, the band is passed around the bone part, the other end portion is passed through the opening and the bore, thus forming a loop for gripping said bone part, the loop is tightened to the desired size by pulling on the two end portions, and said component is inserted with force into the opening, deforming the bore in order to obtain a position in which said end portions are blocked by compression in the bore, the component then being deformed plastically.

Advantageously, at least two adjacent vertebrae are joined together in the case of an arthrodesis procedure.

To do this, an end portion of the band is passed through the base body and the component, the flat band is placed around the two vertebrae (or forms a loop with the rest of the band around the vertebrae), and the other end portion is passed through the opening and the bore, the vertebrae are brought closer by pulling on the ends, and the attachment is blocked by inserting the component with force into the body in the desired position, before cutting off the excess end positions of the band.

The invention will be better understood on reading the following description of embodiments given hereinbelow as non-limiting examples.

The description makes reference to the accompanying drawings, in which:

FIGS. 1A and 1B are perspective views of a device according to an embodiment of the invention, before insertion (FIG. 1A) and after complete insertion (FIG. 1B) of the retaining component into the base body.

FIG. 2 is a perspective view of the retaining component from FIG. 1.

FIGS. 2A, 2B and 2C are, respectively, the cross section IIA-IIA from FIG. 2 (FIG. 2A), the plan view before insertion (FIG. 2B) and after insertion (FIG. 2C) of the component from FIG. 2.

FIG. 3 is a longitudinal axial cross-sectional view of a component according to another embodiment of the invention.

FIG. 4 is a perspective view of the base body from FIG. 1.

FIG. 4A is a cross-sectional view along IVA-IVA from FIG. 4.

FIG. 4B is a plan view of the body from FIG. 4.

FIG. 5 shows schematically, and in profile, a device according to FIG. 1 in place on two adjacent vertebrae.

FIG. 6 is a schematic and perspective top view showing a component with a slit according to another embodiment of the invention.

FIGS. 1A and 1B show a device 1 for attaching a flat and flexible band 2 on at least one bone part 3.

The band 2 is, for example, made of braided polyester, for example polyester with a thickness of 1 to 3 mm and a width of 6 mm, and has a loop 4 for attachment on the bone part 3, for example on a transverse or spinous process of a vertebra.

The loop 4 is formed by bringing together the two end portions 2′ and 2″ of the band.

The device 1 comprises a rigid base body 5, for example made of titanium, although it can also be made of rigid plastic material.

The body 5 extends about an axis 6. It is of a substantially parallelepipedal or cuboid shape with edges 7 which, for example, are rounded, for example with a widened upper part 8 and a transversely narrowed lower part 9 in order to form two lateral recesses 10 that will allow it to be gripped by the jaws of ancillary forceps.

It is provided with a through-opening 11 which has a substantially oblong cross section and which will be explained in detail with reference to FIGS. 4 to 4B.

The device 1 moreover comprises a component 12 which serves to retain the band 2 and which is made of plastic material, for example, and is at least partially wedge-shaped, that is to say with a prismatic or substantially prismatic shape, as will be explained in detail with reference to FIGS. 2 and 2A to 2C.

The component 12 has a bore 13 running through it for the passage of the ends 2′, 2″ of the band, said bore 13 having a cross section that is deformable between a first cross section S1 for the free passage of the end portions when the component 12 is not inserted with real compression in the opening (FIG. 1A), and a narrowed cross section S₂ for blocking the end portions by compression when the component is inserted fully in the opening 11 (FIG. 1B).

With reference to the FIGS. 2, the component 12 has a first central part 14 with a horizontal cross section that is rectangular or substantially rectangular, and with a longitudinal vertical cross section (along the section plane II_A-II_A) with a shape that is an isosceles trapezoid or substantially an isosceles trapezoid with walls 15 symmetrical with respect to the longitudinal plane P, with the periphery uniformly toothed on the outside (teeth 16).

The teeth 16 (for example seven in number) are formed by longitudinal ridges of triangular shape, of which the vertices are directed upward or are horizontal, with an acute angle (imbricated).

The lower teeth or the lower tooth of the component and the one or more upper teeth of the opening of the body form a means of pre-connection to each other by a snap-fit action.

The component 12 moreover has two end parts 17 of semicylindrical or substantially semicylindrical shape having walls of oval cross section which are symmetrical with respect to the section plane II_A-II_A 18, the oval configuration of which is directed outward and, as will be seen, is designed to cooperate with opposite walls of the opening 11.

As is shown in FIGS. 2 and 2B, the walls 15 and 17 of the component 12 are solid and have no discontinuity.

The trapezoidal cross section has an angle at the base b (with respect to the small base of the trapezoid).

The angle between the walls 15 (corresponding to 2b—180°) is preferably between 10 and 30°.

More precisely, with reference to FIGS. 2B and 2C, the bore 13 has a horizontal cross section of oblong shape, like a cat's tongue, which will deform between a sectional shape S1 (FIG. 2B) and a sectional shape S2 narrowed at the middle (FIG. 2C).

The bore 13 comprises two opposite plane main walls 19, each comprising, on their inner face, a transverse rib 20, said transverse ribs 20 being mutually offset in height and having a square or rectangular cross section terminating in a fine bevel at the ends thereof, which will permit better blocking of the ends 2′, 2″ after insertion, the distance d between the two end edges 19 of the members before compression permitting free passage of said ends of the band 2.

The dimensions of the bore 13 are generally adapted to those of the band.

In particular, the distance d and the length of the bore along the section plane P are chosen such that the two ends of the band are placed flat on each other. Indeed, any offset between the ends of the band is detrimental to correct clamping of the band in the device 1.

In practice, the distance d is slightly greater than twice the thickness of the band, and the length of the bore is slightly greater than the width of the band.

In the embodiment more particularly described here, the component 12 thus has a core 21 that is hollowed out by the bore 13 formed by the first central part 14 and the end parts 17.

It has the opposite main walls 15, of which the outer face is inclined and forms the wedge connected by the two rounded end walls 17 which are designed to cooperate with the opening by friction, which will be described below.

The thickness e of the junctions 22 between main walls and end walls 17 is smaller (for example twice as thin) in order to permit the deformation by squeezing in the transverse direction (arrow 23) without deformation in the longitudinal direction (arrow 24) during the insertion of the component into the opening (cf. FIG. 2C).

FIG. 3 shows, in cross section, another embodiment of a component 25, of which the main walls 26 have only one tooth 27 at the bottom end 28 (small base of the trapezoid) on their outer face 29 and a single rib 30, in the upper part 31 ( 9/10 of the height for example) on their inner face 32 of the bore 33.

FIGS. 4, 4A and 4B show the base body 5 used with the component 12.

It is substantially parallelepipedal and has the through-opening 11.

The latter has two inner main longitudinal portions 34 which are symmetrical with respect to the axial plane perpendicular to the plane 35 (axial plane of the section IVA-IVA), having a trapezoidal longitudinal cross section with an angle to the base a, with teeth 36 or recesses of shapes complementing those of the outer faces of the walls 15 of the component, of identical or similar number (cf. FIG. 4A).

The invention is not limited to this embodiment and covers all means of complementary shapes provided on the inner face of the opening 11 and on the outer face of the component 12 for ensuring the pre-connection of the component and of the body or else a blocking of the component in the body.

The opening moreover has two end walls 37 which are designed to cooperate at least partially with the outer face of the walls 17 of the component by being of complementary shape, that is to say, in the embodiment more particularly described, with a half circular or half oval inner cross section.

Still in this described embodiment, the end walls are joined to the main walls by intermediate walls 38 which are of a curved shape and make up for the thicknesses of walls, which will leave recesses 39 (see FIG. 1B) after insertion.

We will now describe, more particularly with reference to FIGS. 1A, 1B and FIG. 5, how bone parts 40 and 41 of two vertebrae 42, 43 are fixed to each other by the device according to the embodiment more particularly described.

Having passed the band in a loop formation around the two bone parts 40 and 41, the surgeon introduces the end portions 2 and 2′ into the opening 11 of the body, then into the bore 13, and/or simultaneously into both if they are already pre-connected (summarily) to each other.

The body and the component are then moved toward the two bone parts using a known type of clamping tool, in the direction of arrow 44. The friction between the ends is sufficient to pre-position the device with the loop and at the desired distance.

Once the desired position has been obtained by the operator, the latter then inserts the component with force into the body in such a way as to bring the upper face 45 of the component flush with that 46 of the body, by pressing on the recesses 10.

This insertion by force causes the plastic or permanent deformation of the component.

The teeth of the component and of the body are then in engagement with each other and form a blocking system or non-return system that opposes their disassembly.

It has been found that a component made of polymer material does not damage the band and that a body made of titanium increases the efficiency of the clamping action.

The excess end parts are then cut off and the patient's back is closed.

FIG. 6 shows another embodiment of a component 47 according to the invention, of which the two end walls 17 moreover each comprise a slit 48 along a height h₁ less than the height H of the component, for example between 0.5 and 0.8 H.

Each slit 48 extends through the corresponding wall 17 and opens out on the upper face 45 of the component 47, which will permit tightening of the component (arrow 49) when it is wedged in the opening of the body.

The two slits 48 make it possible to guide the deformation of the component 47 and to avoid the risks of torsion or twisting of the component when it is inserted into the body.

Thus, the component has solid or continuous walls or else at most two walls having a slit, these two walls being opposite each other.

As will be appreciated, and as is also apparent from the above, the present invention is not limited to the embodiments more particularly described. Instead, it includes all variants thereof, in particular those in which all the elements are made of titanium or, by contrast, of a biocompatible plastic.

Claims

1. A device for attaching a flat and flexible band on at least one bone part, comprising said band having two end portions, a rigid base body with a through-opening, and a retaining component that is insertable in said opening, wherein the retaining component is at least partially in the shape of a squeezable wedge comprising a central bore for passage of said opposite end portions of the flexible band, said central bore having a cross section that is deformable between a first cross section for free passage of the end portions when the component has not been inserted in the opening, and a second cross section for blocking said end portions by compression when the component is entirely or substantially entirely inserted in the opening.

2. The device as claimed in claim 1, wherein, with the base body extending about an axis, the opening has a first longitudinal cross section that is an isosceles trapezoid or substantially an isosceles trapezoid in a first axial plane with a first angle a at the base, and the retaining component has a second longitudinal cross section that is an isosceles trapezoid or substantially an isosceles trapezoid in said first axial plane with a second angle b at the base, wherein second angle b is greater that first angle a.

3. The device as claimed in claim 1, wherein the retaining component comprises two main opposite longitudinal walls and two opposite longitudinal end walls, each of the longitudinal end walls being provided with a continuous slit which is arranged on a portion of said wall, is open to the bore and opens out on the upper face of the component.

4. The device as claimed in claim 1, wherein the inner face of the opening and the outer peripheral face of the component comprise means for pre-connection to each other by snap-fit action.

5. The device as claimed in claim 1, wherein the inner face of the opening of the body and the outer peripheral face of the component have means constituting a system for blocking the component with respect to the body when the component is inserted in the opening.

6. The device as claimed in claim 4, wherein the bore and the component each have a longitudinal plane of symmetry, respectively defining two opposite inner longitudinal faces for the opening and two opposite outer peripheral longitudinal faces for the component, each opposite face having at least one portion provided with at least one tooth or rib for fastening and blocking the component with respect to the body.

7. The device as claimed in claim 1, wherein the bore has a cross section of oblong shape and has two opposite main walls, at least one main wall comprising, on its inner face, at least one inwardly protruding transverse rib.

8. The device as claimed in claim 6, wherein the protruding transverse rib is situated in the upper longitudinal part of the bore.

9. The device as claimed in claim 1, wherein the bore and the retaining component are of shapes that are designed to cooperate by friction on at least one of their opposite parts in the direction perpendicular to the first longitudinal plane when the component is inserted in the opening.

10. The device as claimed in claim 1, wherein the component has a core hollowed out by the bore, of general oblong shape, comprising two opposite inclined main walls forming the wedge and two end walls extending about an axis, of which the faces are arranged to cooperate longitudinally with a corresponding recessed part of the opening, the thickness of the junctions between main walls and end walls being reduced in order to permit the deformation by squeezing in the transverse direction without deformation in the longitudinal direction during insertion of the component into the opening.

11. The device as claimed in claim 1, wherein the base body is made of titanium, the retaining component is made of polymer, and the flexible band is a polymer braid.

12. A method for attaching a flat and flexible band on at least one bone part, said band provided with two end portions, a rigid base body with a through-opening, and a retaining component that is insertable into said opening, wherein the retaining component being in the shape of a squeezable wedge comprising a central bore for passage of said opposite end portions of the flexible band, the method comprising: introducing an end portion of the band into the opening and into the bore, the retaining component being connected partially in the opening;passing the band around the bone part, and passing the other end portion the opening and the bore, thus forming a loop for gripping said bone parttightening the loop to the desired size by pulling on the two end portionswherein said retaining component is inserted with force into the opening, deforming the bore in order to obtain a position in which said end portions are blocked by compression in the bore, the component then being deformed plastically.