MX2011003284A - Anchoring device for lumbar vertebrae. - Google Patents

Abstract

Described is an anchoring device for lumbar vertebrae characterised by mechanical essays of tension, flexo-compression, flexion and anterior flexion, and which comprises a flat element (for example a polyamide belt 6/6) with a close path in the shape of a figure eight with an upper loop and a lower loop, with the purpose of reducing the ailment of the facet arthrosis present in human beings. In addition, the present device supports its innovation under Engineering and medical interdisciplinary studies.

Description

"ANCHORAGE DEVICE FOR LUMBAR VERTEBRAS FIELD OF THE INVENTION The present invention is related to the techniques used in the design of prostheses, devices and implants that are used for the support and reinforcement of the spine; and particularly, it is associated with a device for securing lumbar vertebrae, constituted by a flat element made of a biocompatible material.

BACKGROUND OF THE INVENTION Low back pain is a common symptom caused by multiple and varied etiologies, its incidence in developed countries is so high that 80% of adults over 40 suffer at least one episode of low back pain throughout their lives. Low back pain is the most frequent reason for consultation due to musculoskeletal involvement, and the first cause of work disability.

Although it has been attributed to lumbar intervertebral discs as the main cause of low back pain, it is also recognized that facet arthrosis is a significant cause of low back pain. In this sense, facet arthrosis is produced by the normal wear of the cartilage of the facet joint. In youth, that cartilage is thick and absorbs the load that supports the joint, but it is losing thickness as the years pass.

Likewise, facet arthrosis comprises a series of alterations of the vertebral set, the final result of which is the degeneration of the mobile segment.

Today, there are numerous devices and / or techniques used to treat this condition, such as Roy-Camille plates, which are very rigid and do not allow adaptation to the lumbar lordosis properly.

For its part, another group of devices that have been used to address this condition are: arrangements in the form of "eight" by means of a rope of synthetic material called DACRON, wires, meshes and screws as fixation systems or segmental stabilization in the spine, occupied in some cases to reduce any condition in the lower back.

With respect to surgical grade stainless steel wires, it can be mentioned that they have been used to achieve a wide variety of functions such as a tension band that captures and fixes posterior elements within the human vertebral column. Also, the wires are used to fix and immobilize bone graft in the receptor area.

The stainless steel wire is placed on the back of the human spine between the spinous processes. It is worth mentioning that the most used arrangements with the wires are in the form of "eight" and their ends are tied in different ways according to the load support that they must resist, however, a problem with these wires has been that the handling to do The mooring is extremely complicated since, due to its circular cross-sectional shape, it slips from the hands of the surgeon.

Another important point to mention is that invasive surgeries in the spine take on average 4 hours and depend on the skill of the surgeon, and in some cases, such as placement of spacers, require up to 8 hours. It is important to mention that the previous techniques can damage the interspinous and supraspinatus ligaments at the time of being invaded by the surgeon, in addition to the interspinous and supraspinatus ligaments do not tend to regenerate, so the above weakens the vertebral structure.

In summary, there is a need for new devices that help reduce the suffering of facet arthrosis, and additionally, it is necessary to reduce the times of surgical intervention so that this type of operation is easier using low cost materials.

BRIEF DESCRIPTION OF THE INVENTION To solve the problems raised, an anchoring device for lumbar vertebrae has been developed as an alternative for clamping and cerclage in the posterior part of the lumbar spine. The device is placed in the spinous processes and does not damage the interspinous or supraspinatus ligaments, which represents a great advantage over the techniques and wires of the previous art.

Particularly, the present invention relates to an anchoring device that stabilizes the lumbar vertebrae comprising a flat element with a closed path in the form of "eight", defining an upper loop and a lower loop, wherein the upper loop surrounds the apophysis spinous of a superior vertebra and the inferior curl surrounds the spinous process of a inferior vertebra, with which, in its position of use the flat element pierces: i) a first hole provided in the interspinous ligament above said upper vertebra; ii) a second orifice and a third hole located in the interspinous ligament that exists between said superior and inferior vertebrae; Y, iii) a fourth hole provided in the interspinous ligament that exists below the lower vertebra.

One of the advantages of the present invention is that, during its placement, the interspinous ligament is not removed and, being flat, it is easier to manipulate and therefore shortens the time of the operation. The device is made of a biocompatible material such as polyamide (6/6).

BRIEF DESCRIPTION OF THE FIGURES The novel aspects that are considered characteristic of the present invention are set forth with particularity in the appended claims. However, the invention itself, together with other objects and advantages thereof, will be better understood in the following detailed description of certain preferred embodiments thereof, when read in conjunction with the accompanying drawings, in which: Figures 1A and 1B show two photographs of stainless steel wires of the prior art in the form of eight and different moorings used for placement in the spine.

Figure 2 shows a device for the anchoring of lumbar vertebrae constructed in accordance with a preferred embodiment of the invention.

Figure 3 shows a photograph of the lumbar segment of a pig vertebral column as an experimental modeling element of the device showing the orifices that are pierced by the device of the present invention.

Figures 4A and 4B show a pair of photographs illustrating the manner in which the device of the present invention is placed in the lumbar section of the spine.

Figure 5 shows the experimental assembly for evaluating the behavior of the anchoring device of the present invention.

Figure 5A shows the experimental assembly for evaluating the behavior of the anchoring device of the present invention in a tension test.

Figure 5B shows the experimental assembly of the lumbar segment of the pig column without the placement of the belt to evaluate the biomechanical behavior in the tension test.

Figure 5C shows the experimental assembly of the lumbar segment of the pig column with the placement of the belt to evaluate the biomechanical behavior in the tension test.

Figure 6 shows the flexo-compression forces considered to evaluate the performance of the device of the present invention.

Figure 6A shows the mechanism of shearing injury of the lumbar segment of the pig column after the flexo-compression test.

Figures 7A and 7B show certain angles measured in the flexion test, Figure 7A being a lumbar column segment without the device and Figure 7B the column segment with the device.

Figures 8A and 8B show the applied forces and the angles measured in the previous flexion test for both a lumbar segment, without the device placed as well as with the device placed.

DETAILED DESCRIPTION OF THE INVENTION As mentioned, the present invention relates to an anchoring device for fastening lumbar vertebrae, so in order to contextualize the invention and its advantages over the prior art, it is important to refer to figures 1A and 1B , they show a series of stainless steel wires 1 surgical grade, arranged in the form of "eight", and with different types of ties, which depend on the degree of load to be borne by them once placed between the vertebrae. As mentioned, the difficulty of using these types of steel wires 1 is that they slip due to bodily fluids and making the "eight" shape requires a lot of skill on the part of the surgeon.

Having explained the prior art, reference is made to Figure 2 which shows an embodiment of the device 10 of the present invention that worked for the purposes thereof, consisting of a flat element 11 with a clamping head 20 and a strip 30 toothed that is inserted in the clamping head 20 to be attached to it, in the manner of a belt, similar to what is used to fasten electric cables. The material of the device of the present invention is a material biocompatible; understood as biocompatible material as the property of certain materials that can remain permanently integrated within the organism and that do not induce rejection and / or allergic or inflammatory reactions.

Now, in Figure 3 is shown a photograph of a lumbar segment of column 51 where the hole 11 located between the lumbar vertebrae L1 and L2 is observed (terminology well known to those skilled in the art), also, the holes are observed 12 and 13 located in the interspinous ligament of the vertebrae L2 and L3, and the orifice 14 made in the interspinous ligament located in the vertebrae L3 and L4. The holes 11, 12, 13 and 14 will be pierced by the device 10.

Figures 4A and 4B show the assembly of the device 10 inserted into the holes shown in Figure 3, forming an upper loop 15 in the vertebra L2 and a lower loop 16 in the vertebra L3, which anchor these lumbar vertebrae to solve the problems of facet arthrosis.

It is convenient to mention that the fastening or anchoring between the spinous processes can be done with the device of the present invention, either in the form of "eight" as illustrated or in "O".

The present invention is further illustrated by the following examples which are provided solely to explain the present invention in greater detail, without these in any way limiting the scope thereof.

EXAMPLES In order to evaluate the anchoring device of the present invention, an experimental assembly was designed to evaluate tension, flexion-compression, flexion and anterior flexion in a lumbar segment of a pig vertebral column.

Figure 5 shows the assembly 50, with the lumbar section of spine 51, clamped between the two jaws (aluminum plates) 52 and 53 for subjecting it to certain mechanical tests as will be described below, where the device 10 was placed between the vertebrae L3 and L4, forming an eight.

Examples 1 to 4 Stress tests The test of tension of the porcine lumbar segments consisted in applying axially a tension force (FT) as shown in Figure 5A, the application of this force (FT) was in the upper aluminum cup 52 as seen in the figure 5A. To make a comparison, a lumbar segment of a pig column without the device of the present invention was used as shown in Figure 5B and three segments with the device 10 of the present invention assembled as shown in Figure 5C, the behavior of lumbar segment tension with and without the device is summarized in Table 1.

TABLE 1.

Stress test results According to Table 1, the results obtained show the biomechanical behavior of the porcine lumbar segments under the tension test where parameters according to the segmental stabilization were obtained with the device of the present invention under an axial load of tension (FT) and taking this test to the limit, it is important to mention that this level of load value in humans is not expected to be present under natural conditions, except in extreme cases due to accidents or performing certain exercises, which makes it possible for the present invention can be used in human applications, specifying that reference parameters under natural conditions are not taken to limit values.

Examples 5 and 6 Flexo-compression tests Figure 6 shows the experimental assembly described above and the compression force (Fe) applied, whereby a bending moment (M) is produced in the upper jaw 52, the tension produced in this test is indicated with the arrows 55 and 56 on the back of the lumbar segment. The nomenclature L1 to L5 represents the lumbar vertebrae, where the device was placed in vertebrae L3 and L4. Table 2 shows the results obtained in examples 5 and 6.

TABLE 2 Flexo-compression test results.

TABLE 2 (continued).

Flexo-compression test results.

According to table 2, the results obtained show the biomechanical behavior of porcine lumbar segments under the flexo-compression test denoting parameters according to the segmental stabilization with the device of the present invention under this type of test, pushing it to the limit. It is important to mention that the union with the device of the present invention between the spinous processes of L3-L4 did not present any alteration and that the parts adjacent to this area were damaged due to a mechanism of injury called shearing as shown in the figure 6A which is a real photograph of the experimental design 50 using the lumbar portion 51 of a pig column using the device 10 of the preferred embodiment of the present invention.

With reference to Figures 7A and 7B, they indicate the angles measured in the flexion of the column segment without belt (Figure 7A) and using a belt (Figure 7B), the use of the device 10 is observed which allowed a reduction of around of 7o with respect to the segment where it was not used, which proves an acceptable behavior that in practice is translated, as a novel alternative, since it does not allow any movement in the region where it is placed and the movement decreases by 36.84% of the segment to be flexed as seen in Figure 7B, combined to decrease the affection of facet arthrosis and the ease of manipulating the device of the present invention in a suitable manner.

Figures 8A and 8B show the results of anterior bending in a lumbar segment of the column where the angles measured without the device are observed as with the device of the present invention.

Table 3 shows the average results of the angles 0AEL and T? according to the force (FT) applied, in the specimens without belt.

TABLE 3 Table 4 shows the average results of the angles T ???. Y ?? according to the force (FT) applied (specimens with belt).

TABLE 4 In general, this trial allowed to evaluate the biomechanical behavior of porcine lumbar specimens with the interspinous cerclage between the spinous processes of L2-L4 and to understand the evaluation of how a human lumbar spine could behave in the reduction of the facet arthrosis condition with the placement of the device of the present invention.

Although certain preferred embodiments of the present invention have been described and exemplified, it should be emphasized that numerous modifications to it are possible, such as the materials of the device, length, thickness, etc. Therefore, the present invention should not be considered as restricted except by what is required by the prior art and by the scope of the appended claims.

Claims (4)

1. An anchor device for lumbar vertebrae characterized in that it comprises: a flat element with a closed path in the form of eight with an upper loop and a lower loop, wherein the upper loop surrounds the spinous process of an upper vertebra and the lower loop surrounds the spinous process of a lower vertebra, where, in its position of use, the planar element passes i) a first hole provided in the interspinous ligament that is located above the upper vertebra, ii) a second orifice and a third hole located in the upper vertebra, the interspinous ligament that exists between said vertebrae; and, iii) a fourth hole located in the interspinous ligament below the lower vertebra.

2. An anchoring device for lumbar vertebrae, according to claim 1, further characterized in that the flat element comprises a clamping head and a toothed strip that is inserted in the clamping head to be held thereto.

3. An anchoring device for lumbar vertebrae, according to claim 1 or 2, further characterized in that the flat element is made of a biocompatible material.

4. An anchoring device for lumbar vertebrae, according to any of claims 1 to 3, further characterized in that said flat element is a polyamide 6/6 belt.