KR20020059359A - Improved disc prosthesis - Google Patents

Abstract

The present invention provides a spinal disc implant comprising two side walls spaced apart in parallel by the front wall and the rear wall to form an interior space. The side wall forms an elliptic bend connecting the front wall and the rear wall. The front wall is curved and the rear wall may be curved or straight. These walls include circular or oval openings. The upper and lower edges of the implant include multiple gears to extend therefrom and engage adjacent vertebrae. The implant is made of a biocompatible metal such as titanium or an alloy thereof, wherein the first side and the second side are inclined from the second end to the first end. The inner space includes a porous hydroxyapatite block for filling this inner space. The porous hydroxyapatite matrix helps the prosthesis to be integrated with the spinal structure by allowing the prosthesis to proliferate into small holes.

Description

Disk prosthesis {IMPROVED DISC PROSTHESIS}

Various types of spinal prostheses have been proposed in the art for implantation into spinal disc space after surgical removal of damaged or diseased discs. These devices fall into three broad categories. One of them involves the use of flexible synthetic materials to mimic the compressibility of human spinal discs. For example, U.S. Patent 5.171.281 (Parsons) discloses a disk spacer claiming that it can have mechanical properties similar to a normal disk by varying the hardness of the elastomeric material in the nucleu and annulus. Is disclosed. U.S. Patent 5.192.326 (Bao Ye) discloses a prosthetic disc formed from various hydrogel beads having at least 30% water content. According to this, a semi-permeable thin film that allows the flow of fluid into and out of the prothetic nucleus covers the beads. U.S. Patent 5.071.437, issued to Steffi, proposes another type of flexible implant. This patent includes a rigid flat top and bottom where an elastomeric core made of polyolefin rubber is sandwiched. U. S. Patent 5.002.576, Perman, discloses an embodiment modified from the foregoing.

Another type of prosthesis is to mimic the shape of a natural spinal disc. For example, US Pat. No. 4.714.469 (Kenna) discloses a spinal implant that fills the space between the vertebrae by replacing discs between adjacent vertebrae using predetermined thicknesses and shapes. Such implants include a porous coating on their surface. US Patent 4.459.766, issued to Butner-Janz, discloses a metal disk in a prosthesis that includes two concave end plates that are symmetrical with each other and are provided with a partition member in the middle. Similarly, U. S. Patent No. 5.314.477, issued to Orca, discloses a disc prosthesis comprising two plates separated by a circular cap and a cylindrical base constructed junction that strengthens the connection between the vertebrae.

Recently, the inventor has received a patent for a prosthetic intervertebral disc considering the shape and anatomy of the space to be filled by the prosthetic device (US Patent 5.865.845). This device is an improvement over the conventional device, but could not be applied to all shapes or all applications. In addition, experience in its use indicates that there is an increasing demand for more precise connection to surrounding tissue in the spinal column. Accordingly, there is a need for an improved spinal implant that can improve disk replacement by making conventional spinal implants easier.

The present invention relates to artificial biocompatible synthetic spinal prosthesis, particularly to metal prosthesis intervertebral discs.

1 is a perspective view of a spinal disc implant of the present invention.

Figure 2 is a plan view of the spinal disc implant of Figure 1;

Figure 3 is a side view of the spinal disc implant of Figure 1;

4 is a front view of the spinal disc implant of FIG.

5 is a schematic cross-sectional view of the gear of the implant shown in FIG.

6 is a plan view of a portion of the gear on the top surface of the implant.

Fig. 7 is a cross sectional view of the implant of Fig. 1 along lines 7-7 before the central opening is drilled or the gear is machined.

The object of the present invention can be achieved by overcoming the disadvantages of the prior art and by providing a spinal disc implant comprising an implant of a metal body comprising an anterior space formed between the front wall and the rear wall and two side walls. have. Each of the side walls forms an arcuate bend connecting one end of the front wall and one end of the rear wall. In addition, each wall includes at least one opening, and the upper and lower surfaces of the two side walls include a plurality of gears extending therefrom to engage adjacent vertebral bodies. The sidewall of the implant is inclined in height to the anterior wall to the posterior wall; The front and rear walls are not provided with gears and have a height similar to a portion of the side wall adjacent to the front and rear walls. The implant is made of a metal such as titanium and its alloys, the first side and the second side being inclined from the connection between the rear wall and the side wall to the connection between the front wall and the rear wall. The inner space includes a porous hydroxyapatite block in the form of being pressed or bonded to the inner space or spirally coupled to the inner space to fill the inner space. The porous hydroxyapatite substrate helps the prosthesis to be integrated with the spinal structure by allowing the bone to proliferate into small pores.

Other objects, features and advantages of the present invention will be more clearly understood by the following detailed description with reference to the accompanying drawings.

1 shows a spinal disc implant 10 of the present invention. The implant 10 generally comprises a D-shaped body 12 with a central opening 14. The implant further comprises an upper and lower surface 16, 18 with a gear 19 or other gripping means on each surface. The implant 10 includes a front wall 20, a rear wall 22, and first and second side walls 24, 26 connected to each other. The rear wall 22 is straight, and the front wall 20 and the side walls 24 and 26 are curved. The openings or holes 28 formed in the wall are elliptical, but may be square, circular, or rectangular. 1 has holes or openings 28 in the center of the rear wall 18 and in the center of the front wall 20. As shown in FIG. The implant 10 is provided with a total of six openings or holes 28, like the center of each sidewall 24, 26, the connection between each sidewall 24, 26 and the front wall 20. An opening or hole 28 is provided. Gears 19 are provided on the top and bottom surfaces of the side walls 24 and 26, but not on the top and bottom surfaces of the front and back walls 20, 22. The upper and lower surfaces 30, 32 of the rear wall 22 are notches 34, 36 that provide a structure that engages a gripping tool (not shown) to assist in the replacement of the implant 10 in the spaces between the vertebrae. ). The space defined by the central opening (shown in detail in FIG. 2) 14 is filled with biological elements or components that help induce the growth of bone and cartilage to the surface of the implant in the space defined by the gear 19.

Gears 19 (FIGS. 1 and 5) consist of four steep pyramids of steep slope having a height of about 0.08 ". As shown in FIG. 2, the sidewalls 24 and 26 of the implant 10 are shown in FIG. They are arranged in a straight line downwards across the top and bottom surfaces 16 and 18. The pyramid surfaces of each gear 119 form an angle of 45 ° with respect to the vertical line. Or by some casting process.

A major feature of the present invention is its geometric suitability for its environment. 1 and 3, the implant 10 is inclined from the rear wall 22 to the front wall 20. In this configuration, the implant 120 is inserted between adjacent spinal bodies (not shown) when the spinal column is in an upright position. The exact angles formed at the vertices formed by the top and bottom surfaces change depending on the position of the disk. For example, in the lumbar region of the spinal column, the opposing face adjacent to the vertebral body forms an angle in the range of about 0 ° to 20 °. Likewise, the vertebral body associated with the first and second surfaces 16, 18 of the implant 10 has a limited radius of curvature, and the implant 10 has a curvature similar to the space between the vertebrae. This is consistent with the dome shape of the vertebral body surface.

The implant 10 is made of pure titanium or an alloy thereof and is anodized to make it more inert and increase its biocompatibility. The implant 10 is manufactured by bar stock, tube, or molding, and is made of titanium powder using powder metallurgy. The dimensions of the implant 10 vary with insertion of the implant in the spinal column. For example, in the lumbar region of the spinal column, the vertebral body is larger than the vertebral body in the thoracic region. Thus, the implant used in the thoracic region is smaller than the implant in the lumbar region. Likewise, the lower lumbar intervertebral disc replacement is larger than the upper replacement. For example, an implant sized for implantation between the third and fourth lumbar vertebrae has a length of about 2.7 cm, a width of 2.5 cm, and a height of 2 cm in the anterior direction and a 1.3 cm in the rear. It is inclined to have a height. Those skilled in the art adopt a general dimensional implant 10 and then adapt the implant 10 to a space already occupied by the spinal plate of the measurement requiring replacement. Accordingly, the present invention includes implants with varying angles and dimensions that allow for implantation in spinal cords of different levels.

The shape and curvature of the implant 10 provide several advantages. In the lumbar region of the spinal column, the disc and the vertebral body are supported at an angle that forms curvature or lordosis of the lumbar spine. Positioning the implant 10 in parallel or on the same side is not physiologically and anatomically acceptable. The natural disc in the lumbar spine is wider in the anterior than the posterior. Thus, the disc replacement implant 10 of the present invention is wider in the rear than in the front. This reproduces the natural anatomical curvature of the spinal column.

In addition, the implant of the present invention considered the anatomical surface of the end plate or the lower surface of the spinal body in which the lower surface of the implant 10 is seated. The end plates are made of very small bones in the circumferential direction, but the bones are designed to become thinner toward the middle part. The thin part takes the form of a dome and belongs to the central part of the fluid stress of the end plate. This form mimics the second curvature of the disc implant of the present invention. The second arch corresponding to the dome in the vertebral body provides a mechanism for keeping the cage in place and preventing its slipping or ejection. Gears 19 disposed on the top and bottom portions of the sidewalls 24 and 26 of the implant 10 hold the vertebral body and then cause a mechanical interface between the end plate of the vertebral body and the prosthesis.

In addition, the implant 10 optionally includes an insert of synthetic bone material, such as a porous hydroxyapatite or other substrate equivalent thereto. The synthetic bone material is INTERPORE ProOsteon 500 of porous coralline hydroxyapatite manufactured by Interpore Cross International of Irvine, California. The porous synthetic bone material is supported in place by press insertion (or friction) or in place by a set screw (not shown) on the side of the implant 10. In addition, the porous synthetic bone allows independent placement of the implant 10 in the intervertebral disc space without bone implantation. This reduces mortality and complexity, which has been reported to be about 21% in relation to patient bone grafts. It also eliminates the need for the use of allogeneic grafts that would lead to the transmission of disease or the addition of cost.

The implant 10 provides a non-segmental disc prosthesis that can be provided in a variety of sizes depending on the size required for a particular lumbar region; As a miniature cage using an endoscopic technique for minimally penetrating chuck cycles, it can be provided in small sizes for cervical and thoracic vertebrae.

During a transplant, the surgeon exposes the hernia or damaged disk and then removes it. The spinal disc implant 10 (optionally including the central core of the porous synthetic bone) is inserted into the tool; Such a tool grasps the implant 10 to allow the surgeon to insert the implant into the space between the vertebrae formed by the adjacent vertebral body from which the damaged or altered disk has been removed. Since the implant 10 is located on the vertebral body, its transverse curvature coincides with the dome shape of the vertebral body. At the same time, the anterior position with respect to the posterior creates an appropriate angle between the vertebrae to help restore the natural anatomical curvature of the human spine. Once implanted, the implant 10 aids in osointegration in two different ways. The gear 19 grips the vertebral body to form an irregular surface that allows bone tissue to grow around and around the gear 20. In addition, the presence of porous synthetic bone segments allows bone tissue to grow in pores, thereby allowing the implant to settle in place without restoring the bone graft orallograft. The advantages of the implant 10 of the present invention are that (1) the pattern of the gear is different from the conventional disc, and (2) the end plate of the vertebral body in a more anatomical form compared to the conventional disc. And (3) provided implants can be used in the lumbar spinal column. However, small forms used for the cervical and thoracic spine may also be used as part of the present invention.

The present invention has been described with reference to the preferred embodiments, and is not limited thereto, and one of ordinary skill in the art should recognize that various modifications and changes can be made to the present invention without departing from the appended claims.

Claims (12)

A biocompatible metal implant having a front wall, a rear wall, and two side walls extending therebetween to form a D-shaped interior space, Each side wall forms an arcuate bend connecting one end of the front wall and one end of the rear wall; Each wall includes at least one opening, and the upper and lower surfaces of the two sidewalls include a plurality of gears extending therefrom to engage adjacent vertebral bodies; The implant is made of a biocompatible metal; The height of the side wall is inclined from the rear wall to the front wall; And no gears on the upper and lower surfaces of the front wall and the rear wall, the metal implant having a height similar to a portion of the side wall adjacent to the front and rear walls. The metal implant of claim 1, wherein the height of the rear wall is 11 mm to 15 mm and the height of the front wall is 8 mm to 12 mm. 3. The metal implant of claim 2 wherein the height difference between the front and back walls of the implant is 3 mm. The metal implant of claim 1, wherein the back wall of the implant has a notch at its upper and lower edges. The metal implant of claim 1, wherein the biocompatible metal body is titanium or an alloy thereof. 6. The metal implant of claim 5, wherein the interior space comprises a porous hydroxyapatite block shaped to be supported by the implant in the interior space. The metal implant of claim 1, wherein the top and bottom surfaces of the implant are bent to engage the domed surface of an adjacent end plate of the vertebrae into which the implant is inserted. 8. The metal implant of claim 7, wherein the upper and lower edges of the implant are convexly curved to engage a surface of an adjacent end plate of the vertebrae into which the implant is inserted. In a biocompatible metal implant to replace a diseased spinal disc, A D-shaped body; The body includes a curved front wall, a straight rear wall, and a pair of spaced sidewalls connecting the front wall and the rear wall; The side wall comprises a plurality of gears on its upper and lower surfaces; The front wall and the rear wall do not include gears, and are less than twice the height of the gears and have the same height as the gears of the side walls; The rear wall includes a notch on its upper and lower edges for engaging the insertion mechanism; And the side wall is inclined from the front wall to the rear wall such that the height of the front wall exceeds the rear wall height by about 3 mm. 10. The metal implant of claim 9, wherein the height of the front wall is between 8 mm and 12 mm and the height of the rear wall is between 11 mm and 15 mm. 11. The metal implant of claim 10, wherein said biocompatible material is titanium or an alloy thereof. 12. The metal implant of claim 11, wherein the implant includes a plurality of openings spaced about the circumference thereof.