HK1150737B - Member for dynamic stabilisation of vertebrae - Google Patents

Description

The invention relates to the field of dynamic stabilization of vertebrae.

The invention relates in particular to a dynamic stabilizer of adjacent vertebrae, designed to cooperate with at least two sets of spinal connections which can be implanted on a vertebra.

Generally, dynamic stabilizers are intended to realign the vertebrae with respect to each other while reducing stress on the joint facets and intervertebral discs by allowing certain movement of the vertebrae.

We know of earlier art of such dynamic stabilizing elements.

In particular, international patent application WO2004/024011 contains a dynamic linking element consisting at least in part of a polymer material support and two rods: a first rod substantially coaxial with the support and a second rod formed by spires surrounding the first rod, the said spires being at least partially engulfed in the support.

International patent application WO2005/087121 also contains a flexible connecting element consisting of a cable at least partially surrounded by a polymer sheath, the cable being at least one elastic thread coaxial with that sheath.

Document US 2004/0143264 A1 discloses a dynamic stabiliser with the characteristics defined in the preamble to claim 1.

Conventional connector assemblies include a bone anchorage medium arranged to receive the dynamic stabilizer. The attachment of the dynamic stabilizer to the anchorage medium is accomplished by means of a complementary closure piece. Thus, the dynamic stabilizer is maintained between the bone anchorage medium and the closure piece. The dynamic stabilizer is maintained fixed on the anchorage medium by means of which the dynamic stabilizer is usually achieved. The stabilizer element is usually pressed against the bone, which is in contact with the socket.

In order to secure the nut to the dynamic stabilizing element and thus to enable the latter to be held on the anchorage, it is usual to provide a rigid protective ring between the nut and the dynamic stabilizing element, since the presence of a protective ring between the nut and the dynamic linking element prevents the latter from being plastically deformed by the tightening operation.

This configuration, however, requires adjustment of the length of the stabilizing element and the precise positioning of the protective rings on the dynamic stabilizing element in accordance with the position of the means of anchorage, which can lead to lengthy and tedious installation of dynamic stabilizing elements.

The purpose of the invention is in particular to overcome the disadvantage described above by proposing a stabilizing element which can be quickly positioned on the anchorages while ensuring the elastic or at least flexible behaviour desired between the anchorages.

To this end, and in a first aspect, the invention concerns a dynamic stabilizing element for vertebrae as claimed 1.

The presence of a rigid anchorage sheath ensures and maintains the tightness of the dynamic stabilizer on the anchorage means while allowing for stretching, compression and bending movements by the presence of spaces between the rigid areas of the anchorage sheath.

The mounting sheath thus formed protects the flexible part of the stabilizing element at any point along its length, while retaining the bending, deflecting and/or compression properties of the latter element conferred by the structure of the rod itself.

The rigid areas are preferably spaced less than the nominal contact area defined by the clamping device with the dynamic stabilizer.

The element fitted with such a sheath has the advantage of being able to be quickly installed on the anchorages fixed to the vertebrae, since the distance between the rigid zones means that the clamping means is essentially in contact with the rigid zones.

Depending on the particular configuration, the rigid zones consist of separate rings spaced less than the length of the contact zone.

In another configuration, the fastening sheath consists of a helical band comprising spires extending around the rod along a substantially coaxial axis with the longitudinal axis of the connecting rod, these spires forming the rigid areas of the fastening sheath.

The dynamic stabilization element has the advantage of having means of holding the mounting bracket on the rod between the rigid areas of the mounting bracket.

The dynamic stabilization element is also provided with compression-damping rings, each ring being interlaced between two adjacent rigid areas of the fastening sheath.

Thus, when the dynamic stabilizing element is made by moulding the elastic material around the cable, the elastic material for the envelope is distributed in the openings formed in the sheath, i.e. the spacing between the rigid areas.

The presence of lights reinforces the function of holding the overhanging parts of the enclosure (extensions). This configuration is particularly advantageous when the fastening sheath is formed by separate rings.

Depending on the specific configuration of the dynamic stabilizing element, the rigid zones are equidistant from each other.

To improve the overall strength, the free ends of the dynamic stabilizer are fitted with a rigid tip, which is fixed to the ends of the cable, preferably by welding or stamping.

The invention relates to a binding element comprising at least one dynamic stabilizing element as described above, the binding element being extended by at least one rigid rod. Depending on the intended application, it may be advantageous to provide a rigid rod at the extension of one or both ends of the rod of the extended dynamic stabilizing element.

In another respect, the invention relates to a spinal attachment system comprising at least two implantable spinal connection assemblies, at least two assemblies being connected by a dynamic stabilizing element as described above.

Other objects and advantages of the invention will be shown in the following description, made with reference to the attached drawings, in which: Figure 1 shows a partial perspective view of a spinal fastening system comprising a dynamic stabilizing element in one configuration of the invention supported by two implantable connecting assemblies; Figure 2 shows a partial schematic view of a side of the dynamic stabilizing element of the invention which is in contact with means of clamping connecting assemblies; Figure 3 shows a partial cross-sectional view of the dynamic stabilizing element of Figure 2 in axis III-III; Figure 4 shows a dynamic stabilizing element in a second configuration of the invention; Figures 5a,Figures 6a and 6b respectively illustrate a schematic view of a dynamic stabilizer according to a third configuration of the invention, with and without its shell; Figure 7 illustrates a view of a dynamic stabilizer according to a fourth configuration of the invention, which is without its shell; Figures 8a and 8b respectively illustrate a schematic view of a dynamic stabilizer according to a fifth configuration of the invention, without and with its shell; and Figure 9 illustrates a view of a dynamic stabilizer according to a sixth configuration of the invention,which is represented without its envelope.

In relation to Figures 1 to 3, a dynamic stabilizer 1 of adjacent vertebrae is described. The dynamic stabilizer 1 is intended to be held along the vertebrae by means of at least two implantable spinal connection sets 2.

A connection set 2 shall normally itself comprise a bony anchorage 3 arranged to accommodate the dynamic stabiliser 1 and a means 4 to secure the dynamic stabiliser 1 to the said anchorage 2.

In the embodiment described, anchorage 3 consists of a threaded section 30 for anchorage in the vertebra, topped by a U-shaped head 31 for receiving the dynamic stabilizer 1, the bottom of the U defining a receiving area for the dynamic stabilizer 1.

The clamping medium 4 of dynamic stabilizer 1 in head 3 consists of a nut or screw-forming element intended to be housed in a clearance cavity in the closing chamber 32. When housed in the cavity of closing chamber 32, clamping medium 4 is supported against dynamic stabilizer 1, clamping said element against the U-bottom of the head 31.

It is obvious that the configuration of the anchorages is given as an example and that the invention is not limited to such a configuration. In particular, it may be expected that head 31 is a separate part of the anchorages 3, of the type of a connector itself conventional in back-connection systems.

The dynamic stabilizer 1 is a rod 5 extending along a longitudinal A axis, which consists of a cable 6 surrounded by a sheath 7 of elastic material, which provides the flexibility to allow the vertebrae to be dynamically linked together.

The coupling element 1 also has a fastening sheath 8 comprising 9 rigid zones 9 arranged successively in succession, these rigid zones 9 being spaced sufficiently far apart to allow, in particular, a bending movement of the said rod 5.

In the method described, the fastener 8 consists of 10 independent and separate rings fixed on the casing 7. This is obviously a special case, as the fastener 8 can be arranged in any other way to form rigid spaced areas, such as a helical sheath (Figure 9).

As shown above, the rod 5 is placed in the bottom of the U of the head 31 of anchorage 3 and then held fixed in it by the clamping device 4 which comes into contact by supporting the rod 5. The clamping device 4 defines, with the rod 5, a contact zone 11.

In order to ensure that the clamping force of the clamping means 4 is primarily applied to the rings 10, the distance between the rings 10 is determined to be less than the nominal length of the contact zone 11. Thus, the rod 5 does not require a specific placement on the connecting assemblies, the clamping means of each connecting assembly exerting pressure mainly on the rings 10 regardless of their position on the rod 5.

Figure 2 illustrates an example of such a rod configuration where, for ease of understanding, only the clamping means 4 of three sets of connections have been represented. In this example, rod 5 comprises 10 rings with a length of 5 millimeters. These rings 10 are arranged on the wrapper 7 of rod 5, at a regular distance from each other. Each ring 10 is spaced with the adjacent rings at a distance of 2 millimeters. The clamping means 4 are represented in a noticeably circular shape. The contact face of the clamping means 4 with the correction axis 1 has a circular 5 millimetre outer fixation.

The rings 10 and by extension the fastening sheath 8 are kept locked on the casing 7 because, during the manufacture of the dynamic stabilizing element 1, the material which subsequently forms the casing 7 flows into the spaces formed between the cable and the rings 10 and the rings 10 are then kept apart from each other and blocked by radial bulges 12 of the casing 7 formed between the said rings (Figure 3).

The presence of the plastic bulges 12 has a double advantage: first, as we have seen, the bulges 12 allow the rings to be trapped, preventing them from sliding on the casing 7.

In an advantageous configuration, the rings 10 have lights 14 (Figure 4). The presence of these lights improves the holding of the rings 10 on the rod 5.

Figure 2 shows all the possibilities for positioning the clamping means 4 on the rod 5. The first clamping means (located on the leftmost part of the rod) is arranged overlapping two adjacent rings 100, 101 of the rod 5. This first clamping means therefore has a contact surface covering portions of two adjacent rings 100, 101 and the space 110 between the two rings 100, 101. Due to their stiffness, the clamping force is exerted on the rings 100, 101. The second clamping means (central clamping means) is entirely in contact with a right ring of the rod 5 (ring 102). The clamping force exerted by the third central clamping means therefore applies to the exo-ring concerned. The means of clamping (spacing) is therefore only partially exerted on the ring 103, 104 and 104.

The means of attachment 4 so arranged provide a sufficient grip and hold of the rod 5 on the means of anchorage 3.

Moreover, and advantageously, the free ends 15, 16 of the dynamic stabilizing element 1 are fitted with a rigid tip 17, 18 respectively.

Depending on the particular configuration, one or more rings are mounted sliding on the rod 5.

Figures 1 to 4 illustrate a dynamic stabilizing element comprising a fastening sheath 7 whose rigid zones 9 are of equal length and equidistant from each other. It is obviously obvious that the invention is not limited to such a configuration and that rigid zones with different dimensions and/or rigid zones with spacing which may differ from one ring to another (not shown) may be envisaged, provided that the distance between each ring must remain less than the nominal length of the contact zone.

In addition, it may be expected that the dynamic stabilizing element 1 is extended at least at one end by a rigid element (Figure 5b and Figure 5c), which may itself be extended by another dynamic stabilizing element 1 (Figure 5a), so as to form a hybrid bonding element 100 providing both an osteosynthetic bond and a dynamic bond. In particular, the bonding element 100 of Figure 5a is provided with two parts 1, 1 providing a dynamic bond connected by a part providing an osteosynthetic bond 50. The bonding element 100 of the limit 5b illustrates a bonding element 50 50 50 which provides a synthetic bond and a dynamic bonding element 1.

In the previously described embodiment, the mounting sheath 8 is formed by 10 rings, each of the 10 rings having 20 end faces perpendicular to the longitudinal A-axis of the rod 5. In order to improve the torsion resistance of the dynamic linkage element 1 it is advantageous to provide for rings 10 configured to have 20 end faces inclined respectively with respect to the longitudinal A-axis of the rod 5, with the 20 end faces of each ring 10 arranged parallel to each other (Figures 6a and 6b).

In Figure 6b, the ends of 20 are shown flat, and it is obvious that this is a special case, since the ends of each ring 10 may have any surface, as shown by example in Figure 7.

Helical rings 10 (Figures 8a and 8b) may also be provided. This configuration of the fastener 8 allows the compression and extension properties of the dynamic linker 1 to be improved.

The invention is described in the foregoing as an example.It is understood that the tradesman is able to make different variations of the invention without leaving the invention which is defined by the claims.

Claims (10)

1. A dynamic stabilization element (1) for vertebrae able to cooperate with at least two connection implantable assemblies (2), with each connection assembly comprising a means (3) for anchoring into a vertebra adapted for receiving the dynamic stabilisation member (1), and a means (4) for clamping the dynamic stabilisation element (1) on said anchoring means (3), with the dynamic stabilization element (1) comprising a rod (5) extending along a longitudinal axis and including a cable (6) provided with a casing (7) made of an elastic material, with the dynamic stabilization element comprising a fastening sheath (8) including rigid areas (9) spaced from each other and surrounding the rod (5), and rings for damping a movement of the element (1) positioned respectively between two adjacent rigid areas (9) of the fastening sheath, characterised in that the damping rings are constituted by radial bulges (12) of the casing.
2. A dynamic stabilization element (1) according to claim 1, characterized in that the rigid areas (9) are spaced from one another by a distance smaller than the nominal length of a contact area (11) defined by the clamping means (4) with the dynamic stabilization element (1).
3. A dynamic stabilization element (1) according to claim 1 or claim 2, characterized in that the rigid areas (9) consist of separate rings (10).
4. A dynamic stabilization element (1) according to claim 1 or claim 2, characterized in that the fastening sheath consists of a helical strip comprising turns extending around the rod (5) along an axis substantially coaxial with the longitudinal axis of said rod, with said turns forming the rigid areas of the fastening sheath.
5. A dynamic stabilization element (1) according to any one of the preceding claims, characterized in that the rigid zones (9) comprise one or more ports (14) to facilitate the attachment of the fastening sheath on the casing (7).
6. A dynamic stabilization element (1) according to any one of the preceding claims, characterized in that the rigid zones (9) are equidistant from each other.
7. A dynamic stabilization element (1) according to any one of the preceding claims, characterized in that it comprises means for holding the fastening sheath on the rod (5), with the means for holding the fastening sheath being formed by the damping rings.
8. A dynamic stabilization element (1) according to any one of the preceding claims, characterized in that it comprises rigid end-pieces (17, 18) attached to each end (15, 16) of the cable.
9. A connecting element comprising at least one dynamic stabilization element (1) according to any one of the preceding claims, with the dynamic stabilization element (1) being extended by at least one rigid rod.
10. A spinal fastening system comprising at least two spinal connection implantable assemblies (2), with the at least two assemblies being connected by a dynamic stabilization element (1) according to any one of claims 1 to 9.