Intervertebral nucleus prosthesis and surgical procedure for implanting the same.

The invention relates to an intervertebral nucleus prosthesis whose Task is the mobility in the area of ​​a disc again produce. This mobility is physiologically by the Nucleus generated the considered mechanical joint element of the vertebral bodies can be.

Physiologically, the nucleus of a substantially spherical, not formed stretchable, but deformable body like a bullet is inserted between two Wirbelendflachen, and substantially in the center, and the movements in the form of tilt, rotation and the shift possible.

The Wirbelendflachen in turn by concentric layers of fibers surrounded, referred to as annulus and contain the fibers of one layer to be crossed diagonally.

In this arrangement, the nucleus, which is actually a move is malleable but not stretchable capsule, the hydrophilic with a, filled jelly-like substance is (mucopolysaccharides) in the diffraction of Spine forward or backward even backwards or forward, which movement of the nucleus through the rear and anterior fibers of the annulus and through different longitudinal bands is limited.

In a lateral tilt of the spine shifting stretches of Nucleus the fibers on the convex side. The shift is in this case by the intervertebral ligaments limited.

During a rotation of the spine the intervertebral disc with Shear forces applied.

The nucleus, which is a hydrophilic body has at rest a certain osmotic pressure. Under load, the nucleus loses Water. The thickness of the disc decreases as the pressure again is reduced, rehydration occurs.

The pathological conditions that the reciprocal movements disrupt various vertebral bodies are essentially overloading or excessive and frequent exposure or natural aging processes.

With too strong, too frequent or prolonged exposure does not occur, the rehydration and thus, the pressure applied to the Nucleus the various concentric layers of the annulus forming fibers exerts no longer be built, so that does not play well this pressure more the role of the provision in the movements. In this case occurs Instability and an accompanying osteoarthritis.

The object of the invention, the development of this instability characterized to prevent a nucleus prosthesis is inserted, the implant can take place in vivo and known with less trauma than does Prostheses of this kind hitherto been possible.

These known prostheses, examines the principles below are showing drawbacks that can be understood by the mutual movements and the role of the nucleus in these movements knows.

These disadvantages occur both during use and during Substituting these known implants.

First, it has been simply proposed the intervertebral discs causes Remove, located in the traumatized area. Then you have a bony grafting used, some with and some without osteosynthesis.

The achieved thereby blocking two adjacent vertebral bodies However, only the loads on the spinal discs of the immediately transmitted adjacent vertebral bodies, the burdened excessively and were damaged quickly, the problem is thus only shifted and not solved been.

It continues to have a complete spinal disc prosthesis proposed including both annulus and nucleus.

This practice has the major drawback that performing a full Removing the damaged disc is necessary and that the then introduced total prosthesis between two adjacent vertebral bodies must become.

For both phases of this operation it is necessary to the common Vertebral longitudinal strips cut, namely the anterior longitudinal ligament (LVCA) and the posterior longitudinal ligament (LVCP), so that the natural Movements of the spine can not restore these lost thus to Reliability a.

To avoid these disadvantages, in the present Invention assumes that a nucleus prosthesis is inserted, without resecting the entire intervertebral disc. In the se manner can be by replacing the nucleus already the development of the instability limit, which is the cause of the deterioration.

The nucleus prosthesis allows without damaging the annulus or the Longitudinal bands (LVCA and LVCP) by the displacement of the replaced nucleus exert pressure on the annulus, and therefore it during movement of the Spine to stretch so that it restores the equilibrium position.

The center of rotation, which has been restored in this way is actually remains flexible and able to be different to the Bending movements forwards and backwards of stretching movements and adjust lateral tilt movements.

The nucleus prosthesis of the present invention consists of one or several balls hard, smooth and non-oxidizing and freely are arranged in the interior of a solid retainer, which in turn non-oxidizing is. This prosthesis can be accommodated in the volume which, after the removal of the nucleus between two Wirbelendflächen is free.

1 shows a plan view of a vertebral body with the respective positions of the nucleus, the annulus and the front and rear Longitudinal bands.

Figure 2 is a perspective view of a vertebral body and shows the annulus and the nucleus surrounded by him, of the to Vertebrae supports.

Figure 3 is a perspective schematic view of a check- diametrically cut annulus showing the concentric, intersecting Fiber layers.

Figures 4 and 5 are schematic side views of two adjacent vertebrae at a flexion movement forward or rear.

Figure 6 is a schematic front view of two adjacent Vertebrae during a lateral flexion of the spine.

Figure 7 is a top view of a vertebral body at a Rotational movement.

Figures 8, 9 and 10 are schematic views from the side, of top and front of a nucleus prosthesis with a single bullet.

Figure 11 is a schematic, longitudinal sectional view of exemplary along line AA in FIG. 8

Figures 12, 13 and 14 are schematic views from above, from front and from a nucleus prosthesis with several balls page.

Figures 15, 16 and 17 are schematic views from above, from front and from the side of a nucleus prosthesis with a Damping device.

Figures 1 and 2 show good an intervertebral plane formed is by a plurality of concentric layers of intersecting fibers 1 and 2, clearly visible in Figure 3, and in the center of each of the Nucleus 3 is arranged, while on the outside of the anterior longitudinal ligament (LVCA) 4 and the posterior longitudinal ligament (LVCP) 5 are arranged.

Figures 4 and 5 show the compression forces generated by the Nucleus 3 applied to the concentric Annuluslagen, namely in each case on the outer side of the bending angle in bending forward or backwards.

The nucleus 3 exerts in the same way a pressure on the rings From annulus, on the outside of the angle of inclination seit1ichen (Figure 6).

Each of these displacements of the nucleus 3 represents a return to the Equilibrium safely.

At a rotation in a horizontal plane, it is the joint capsules 6 that lie along a fictive circle on the outside, the enable circular displacement and the rotational movement of the limit (Figure 7), the nucleus 3 is thereby subjected to shear forces.

Thus, the nucleus plays a role in all of these cases, a And the motion damper is during this movement the return to the Equilibrium safely. It can be seen from the consequences which are established, when the nucleus is altered.

It can be seen therefrom, too, that a restoration of the mutual movements adjacent vertebral bodies already achieved can be that one uses a nucleus prosthesis, the implant means a very great surgical advantage.

The existing surgical techniques leads the surgical Vertebral fusion to a permanent fusion of adjacent Vertebrae arranged on either side of the damaged disc. To this end, the disc is completely removed.

When the fusion of two vertebrae is achieved by arthrodesis, then the problems of degeneration on the adjacent discs wear (up or down) exceeded, these problems nor the Strength of the vertebral block thus generated can be increased.

However, if the merger succeeds, what is the reason for frequent Failures, and which leads to a continuation of the complaints, then one often nachoperieren very difficult.

In the case of implantation of a total prosthesis of the intervertebral disc has to found that this is a complicated and difficult surgical The method makes it necessary to give requires a large opening to the Remove natural disc and to be able to use the full denture.

This includes the need to cut through and the displacement large abdominal vessels (aorta and vein) and the nerve bundle of Sexual organs.

In this case, the risk of large vessel bleeding that is difficult to results are catching.

This can also lead to serious sexual problems: impotence and retrograde ejaculation.

In addition, the total resection of the disc leads to a Destruction of the entire annulus, and the front and rear Intervertebral longitudinal strips 4 and 5, which create serious Instability risks.

There is also in this case no return, it remains only the Way a spinal fusion with the disadvantages described above.

The inventive nucleus prosthesis has none of these disadvantages on. It enables the damaged nucleus in both the form and the function to be replaced. It is suitable, the degeneration of the to stop disc characterized in that it stabilizes this again.

The surgical implantation procedure is extremely simple.

Initially, the implantation can be performed endoscopically. they is quickly and gently.

In case of failure you can by removing the nucleus prosthesis restore the original state.

It is not connected with vascular risk, nor with risks the sexual organs.

It actually, endoscopically satisfies an opening between two bring vertebral body through the annulus through which just big enough is to reach the injured nucleus and to remove and to then introduce the same way the artificial nucleus, the automatically centered in the original chamber, followed by the Aperture created closed by a seam.

Regardless of that, this intervention is fast, can the Faserk6rper, which is only slightly damaged by the incision is spontaneously recover quickly and virtually painless. The front and posterior longitudinal ligaments are traumatized in any way, so that the ability to restore original motion of the spine.

The simple implantation of these nucleus prosthesis and the fact that no risks occur in this engagement, resulting in their Application is always appears when primary or secondary Intervertebral disc injury have occurred, namely already at the first Occurrence of the disease before definitive damage of bone and Joints occur.

The nucleus prosthesis consists essentially of at least one movable body 8, of a solid, non-oxidising, bio-compatible Material, which can move in two axes of a plane (For example, a stainless steel ball or a ball made of titanium), the Volume is matched to that of the biological nucleus. This portable Body or this ball B is described in a recorded hereinafter referred to as cage Body 7 mounted, a housing 14 includes (by way of example in Figure 11 shown) which consists of a lightweight, strong, non-oxidizing and biocompatible material (eg, titanium), said housing 14 a mass 15 includes a material having a minimum Coefficient of friction (for example polyethylene). Inside is located a receiving space for the movable body or the ball 8, it is in caught this receiving space, however freely around its center rotatably and so mounted that they on both sides opposite (top and bottom) of the cage 7 emerges in the form of a spherical cap, the amount of which about 1/10 of the diameter of the movable body or the ball 8 corresponds, which value does not have to be strictly adhered to.

The volume of the cage 7, which receives the mobile body 8 is, for its part as closely as possible adapted to the volume of the biological nucleus, is of course contemplated that the cage 7 as storage for the ball 8 must serve. Thus, the prosthesis can position itself, she is so possible always to be found in the anatomical position, thus the restore natural movement between two vertebrae.

The ball 8 overlapping cage 7 can in plan view (Figure 8) a have more or less arcuate shape in symmetrical with respect a transverse midplane. In cross section (Figure 10), the cage preferably the shape of a trapezoid, the small end face of the Ends of the more or less curved shape accommodates.

This trapezoidal front oriented backward asymmetry of Cage 7 causes a rotation thereof between the two Vertebrae is avoided if the thus formed, the artificial nucleus (ball 8) receiving the prosthesis moves.

In an alternative shown in Figures 12, 13 and 14 Embodiment, the cage 7, which in cross-section substantially the Shape of an isosceles trapezium (Figure 13), a plurality of identical Balls 8 (Figure 14) record that on the outside of a common fictional touch plane on both sides of the horizontal center plane of the cage are arranged. The balls are located on both sides of the cage at 7 the three corners of an equilateral triangle.

To increase comfort, the cage 7 can in accordance with the Embodiments of Figures 15, 16 and 17 of two identical Individual bodies 10, 11 are made, the test, not oxidized and biocompatible are formed and have the form of an isosceles trapezium. They are arranged so that their parallel perpendicular to the base surfaces standing along the center lines extending center planes substantially parallel to each other and that the large base faces of trapezoidal individual bodies 10 and 11 in substantially the same vertical plane.

The two thus-formed individual bodies are mutually connected by two resilient bearing members 12 and 13 which perpendicularly to the center planes of the individual bodies 10 and 11 extend and close to the end are arranged a major axis, which in turn have a common tangent forms of the sets of balls 8, which in each outer side of the Overall arrangement are arranged so that the balls of the three corners disposed of an isosceles triangle, which in turn on opposite sides of the assembly in opposite direction point.

If a prosthesis is used according to the figures 8 to 17, then it is understood that immediately after the insertion into the Cavity of the nucleus prosthesis, the role of the biological nucleus accepts and the intersecting fibers of the annulus at a lateral sets or at a movement forward or backwards under tension and thereby produces a return to the equilibrium position. The fast one Engagement, which is necessary for the insertion, avoids any Traumatisierungsrisiken and leads to a rapid healing of the only necessary opening.

The final selection of the proposed models, all the same advantages in terms of onset and with regard to the have physiological results, is due to the clinical Results over time result.

Of course, the cage 7, which a ball 8 or more Balls 8 contains and for the above multiple embodiments have been proposed without departure from the invention Thoughts have other equivalent forms, it is only important he overlaid the ball or balls 8 that they are freely rotatable in him and that its volume is matched to the volume which after removal the biological nucleus is available.

The described nucleus prosthesis can all above Embodiments described spontaneously in the anatomical environment take their own position, so that all the natural movements between can be restored two vertebrae (lateral inclination, Tilt forward and backward rotation). The conical shape (in Trapezoidal cross-section) of the cage 7 facilitates the shift in the Wirbelendflächen level while preventing the rotation of the cage about its central axis, as well as the sinking of the implant in the Wirbelendflächen.