Rod element for linking bone anchor elements, and stabilisation device with such a rod element

The invention relates to a rod-shaped element for the application in spinal or trauma surgery, a stabilizing device with such a rod-shaped element and a manufacturing method of such a rod-shaped element.

From EP 0669109 B1 a stabilization device is to Stabilizing adjacent vertebrae known that two uniaxial Pedicle screws and a tape includes that in the Receiving portions of the pedicle screws via a respective clamping screw is fixed and which one reared on the tape Support member includes in the form of a pressure-resistant body. These However, the stabilization device is not torsion. The use of mono-axial pedicle screws further limited the application of this stabilizer. A similar Stabilizer in place of mono-axial Pedicle polyaxial pedicle screws are used is known from EP 1188416 A1.

From US 6,162,223 is a fixation device for a hinge, eg for a wrist or knee, known in of a connected at its ends with bone anchoring elements Fixation rod is in two parts, the two parts of the fixation rod via a flexible coupling member are connected and wherein said fixation rods and Coupling part are mounted outside the body. The side facing ends of the two parts of the fixation rod are hemispherical shaped and push each other to such a Type of joint to simulate that by the freedom of movement the flexible coupling part is limited. The known fixing device is due to their complex and voluminous Structure for use in the spine unsuitable.

From US 2003/0109880 A1 is a dynamic stabilization device vertebra known that a first and a second in fluidized to anchoring screw each with a receiving part for inserting a spring connecting the screws and includes such a spring. The spring itself is as a whole in The form of a coil spring with closely adjacent turns by formed kind of a tension spring and is clamping screws in the receiving parts fixed. There is in this case however, the danger that the spring because of its elasticity to the pressure of Clamping screw and thus evades the fixation between the Bone screw and the spring is loosened.

The object of the invention, a rod-shaped element for the connecting to stabilization and movement control of each other provide vertebrae or bones, which simply and compact, easy to handle and versatile is coupled with high safety in use. Further it is an object of the invention, a dynamic stabilization device with a compact design that such a rod-shaped used element, and a manufacturing method for the provide rod-shaped element.

The object is solved by a rod-shaped element according to the Claim 1, a dynamic stabilization device according to the patent claim 10 and a method for producing a such a rod-shaped element according to the patent claim 12th

Further developments of the invention are specified in the subclaims.

The invention has the advantage that the rod-shaped element axial forces, bending and torsional forces receives, and with the known polyaxial or monoaxial bone screws usable and securely fix with these. The rod-shaped element is particularly suitable for use in the Stabilizing and movement control of contiguous Vertebrae in the intervertebral disc defects of varying severity suitable. These properties are in the preparation of simple way by changing the dimension of the rod-shaped element to realize.

give Further features and advantages of the invention from the description of embodiments using the Characters.

Of the figures:<dl tsize="8"><dt>Fig. 1</dt><dd>a diagrammatic perspective view the stabilization device according to the invention with the rod-shaped Element in a first application;</dd><dt>FIG. 2</dt><dd>a perspective view of rod-shaped element according to a first embodiment;</dd><dt>3a</dt><dd>a side view of the rod-shaped Element according to the first embodiment;</dd><dt>3B</dt><dd>a sectional view of the rod-shaped Element according to the first embodiment; </dd><dt>FIG. 4a</dt><dd>a perspective view of the connection between the rod-shaped element and bone anchoring elements;</dd><dt>Figure 4b</dt><dd>a sectional view of the connection between the rod-shaped element and Bone anchoring elements;</dd><dt>Fig. 5</dt><dd>a side view of the rod-shaped Element according to a second embodiment;</dd><dt>Fig. 6</dt><dd>a side view of the rod-shaped Element according to a third embodiment;</dd><dt>Fig. 7</dt><dd>rotated by 90 ° Side View the rod-shaped member of Fig. 6 according to the third embodiment;</dd><dt>Fig. 8</dt><dd>a perspective view of rod-shaped element by a fourth embodiment;</dd><dt>Fig. 9</dt><dd>a side view of the rod-shaped Elements of FIG. 8;</dd><dt>Fig. 10</dt><dd>a sectional view of the rod-shaped Element according to a fifth embodiment;</dd><dt>Fig. 11</dt><dd>the operation of the invention Stabilizing device with the rod-shaped element according to the fourth Embodiment, in a first state;</dd><dt>Fig. 12</dt><dd>a side view of the rod-shaped Elements of FIG. 11 in the first State;</dd><dt>Fig. 13</dt><dd>a perspective view of the invention stabilizer with the rod-shaped element according to the fourth embodiment in a second state;</dd><dt>Fig. 14</dt><dd>a side view of the rod-shaped Elements of FIG. 13 in the second State;</dd><dt>Fig. 15</dt><dd>a second application example of the Stabilizer;</dd><dt>Fig. 16</dt><dd>a third application example of the Stabilizer;</dd><dt>Fig. 17</dt><dd>a fourth of Anwendungseispiel Stabilizer;</dd><dt>Fig. 18a</dt><dd>a perspective view of a fifth embodiment of the rod-shaped member;</dd><dt>Fig. 18b</dt><dd>a side view of the fifth embodiment with dashed lines shown hidden lines;</dd><dt>Fig. 18c</dt><dd>a rotated to Fig. 18b by 90 ° Side View the fifth embodiment;</dd><dt>Fig. 18d</dt><dd>a section of the fifth embodiment perpendicular to the core axis the elastic portion;</dd><dt>Fig. 19a</dt><dd>a perspective view of a sixth embodiment of the rod-shaped member;</dd><dt>Fig. 19b</dt><dd>a side view of the sixth embodiment;</dd><dt>Fig. 19c</dt><dd>a section of the sixth embodiment along the rod axis;</dd><dt>Fig. 20a</dt><dd>an illustration of the lower portion of Figure 19c. and</dd><dt>Fig. 20b</dt><dd>a perspective view of Head portion 134 of Fig. 20a</dd></dl>

As shown in FIG. 1 can be seen, the stabilizing device comprises in a first application, a rod-shaped element 1, and two pedicle screws 2, 3, the rod-shaped element on the are connected together. The pedicle screws 2, 3 are in the pedicles of two adjacent vertebrae 4, 5, between where a damaged disc is 6, anchored.

The inventive rod-shaped element 1 is integrally formed. According to a first embodiment includes, as in shown Fig. 2, 3a and 3b, one is first of its end over a predetermined length extending first rigid Section 7, and from its second end via a predetermined length extending second rigid section 8 and a provided between the rigid sections 7, 8 elastic portion 9 of predetermined length, wherein all Sections have the same outside diameter. By the rod-shaped Member further extends a coaxial bore 10 with predetermined diameter. The elastic portion 9 is as Coil spring with turns 11 with a predetermined pitch educated. The height of the turns 11 of the elastic portion 9 in the direction of the longitudinal axis A of the rod-shaped element, the diameter of the coaxial bore 10, the thickness of the the coils 11 determined in the radial direction, and the pitch are selected so that a desired stiffness against axial forces, bending forces and torsional forces on shaped element 1 act, is achievable.

As shown in FIG. 1, FIG. 4a and FIG. 4b can be seen, has a pedicle screw 2, 3 of the stabilization device in a known Manner a threaded shank 12 with a bone thread and a substantially cylindrical receiving part 13 with a U-shaped recess 15 for inserting the rod-shaped element on. To fix the rigid sections 7, 8 in the receiving part 13 are screwed into a known manner into the receiving part Female screw 14 is provided. Preferably, the pedicle screws are designed as polyaxial screws. The axial length and the diameter of the rigid sections 7, 8 of the rod-shaped Element 1 is dimensioned such that the rod-shaped element 1 with its rigid sections 7, 8 with the pedicle screws 2, 3 is connected. corresponds to the length of the rigid sections 7, 8 thus at least approximately to the diameter of the female screw, which is provided for fixing the rod-shaped element. In receiving portions 13 'of a pedicle screw 20, in which the rod-like element is not inserted from above, but is laterally inserted into an opening 21, the length the rigid portion also at least approximately to the diameter a fuser 14, the rod-shaped element Receiving part 13 'fixed.

In the example of the stabilization device shown in Fig. 1 is the length of the elastic portion 9 of the rod-shaped Element 1 is selected such that it essentially corresponds to the distance between the pedicle screws 2, 3 in the unloaded condition the disc 6 corresponds. The elastic portion 9 but may be shorter or longer.

The rod-shaped element 1 is of a biocompatible material, such as titanium or a biocompatible plastics material, however, no or low elastomer properties has formed.

In operation, first the pedicle screws 2, 3, 20 in the Pedicle screwed adjacent vertebrae and then shaped element 1 with its rigid portions 7, 8 each in one of the receiving portions 14 of the pedicle screws 2, 3, 20 is inserted. After the positioning of the vertebrae 4, 5 each other and the adjustment of the pedicle screws 2, 3, 20 relative to the rod-shaped element, the rigid portions 7, 8 'is fixed in the receiving parts 13,. 13 The positioning the vertebrae 4, 5 to each other is carried out in an application so that the elastic section 9 of the rod-shaped element 1 in unloaded state of the disc 6 is in rest position. Under load act on the vertebrae and the ligaments limited forces on the disc 6. The rod-shaped element 1 via the elastic portion 9, the multi-axis motion the vertebrae relative to each other, thus preventing the action of excessively large forces on the intervertebral disc. Thus, the degeneration process of slightly or moderately defective Disc to be stopped. Alternatively, depending on the indication already in the unloaded state of the spine via the Stabilization device a predetermined distraction of made vertebrae in order to relieve the intervertebral disc. alternative can bone screws laterally directly into the vertebral bodies be anchored.

In the second embodiment shown in FIG. 5, a rod-like member 100 as in the first embodiment the rigid sections 7, 8 and an integrally with them connected between the rigid portions 7, 8 lying elastic Portion 90 in the form of a coil spring. Of the Difference to the first embodiment is that the Diameter of the elastic portion 90 is greater than the Diameter of the rigid sections 7, 8. This is a higher Stiffness compared to the stiffness of the rod-shaped Element obtained according to the first embodiment. The operation is as in the first embodiment.

In Figures 6 and 7, a rod-shaped element 101 to a third embodiment shown. This differs from the rod-shaped elements 1, 100 of the previous Embodiments in that between the rigid portions 7, 8 provided elastic portion 900 to two 180 ° staggered concave to the rod axis toward molded Areas 901 having. The length L of the areas 901 in Direction of the rod axis is at a maximum equal to the length of the elastic Portion 901 and the radius of curvature is such that the turns of the helical spring are not broken. By this training is the elastic section 900 in a Direction B perpendicular Fitted formed to the rod axis A and thus has a lower rigidity in this direction. In order to is given an oriented stiffness that for certain applications is appropriate.

The operation is as for the first and second embodiments with the only difference that the rod-shaped element 101 circumferentially oriented in the pedicle screws fixed can be. By choosing the dimensions of the spring portion can accurately select a desired stiffness and be adjusted.

In a fourth, in Figures 8 and 9 embodiment , the rod-shaped element 102 is a resilient through cylindrical portion 902 coaxially extending therethrough Core 110 which has a certain bending elasticity. The diameter of the core 110 is dimensioned so that the core 110 held after insertion into the bore 10 in registration in these is. The core is preferably made of the same material as the rod-shaped element, but it can also consist of a flexible Plastic.

In a modification of the core 110 is integral with the rigid Sections 7, 8 and with the turns of the coil spring of the elastic portion 902 connected.

The core 110 causes a higher bending stiffness of the rod-shaped Element 102 as compared with the first embodiment. Thus, in this embodiment, a stiffness similar to the the rod-shaped element 100 of the second embodiment, which has the larger diameter of the elastic portion, be achieved. The bending stiffness is further characterized by Selecting the diameter and / or material of the core can be adapted. For example, a shape memory alloy having the well-known property of superelasticity are used.

The operation takes place as in the previous embodiments shown. In contrast to the previous embodiments, however, is a compression or extension of the flexible section dimensionally 902 in the axial direction, and a twist reduced. There are then preferably only flexion admitted what for certain applications an advantage is.

In a fifth, in Fig. 10 shown embodiment, the rod-shaped element 103, the rigid sections 7, 8 and elastic section 9 as in the first embodiment.

In the preferably coaxial bore 10 is a tension member 112, such as a wire, is provided on the fixing elements, such as clamping screws 13, to the rigid portions 7, is attached. 8 In operation, therefore, a bias voltage of elastic section 9 are generated.

The features of the described embodiments are each other combined. For example, also the rod-shaped Element of the second embodiment, a core and / or molded Sections to achieve an oriented stiffness have. In a modification of the third embodiment is the elastic portion formed Fitted evenly in one place or there are a plurality of circumferentially equally spaced concave molded portions provided in a obtain certain stiffness in defined directions.

In a further embodiment, the rod includes a plurality of rigid Sections with several each intervening elastic Portions, so that a plurality of pedicle screws in this way with each other partly rigid and partly elastically can be connected.

In a further embodiment is around the elastic section a coating or a protective sheath made of a biocompatible provided material, so that no tissue or blood vessels access or other body material between the turns can thereby be injured or the function may affect the rod-shaped element.

In a further embodiment, instead of polyaxial screws Monoaxial or provided it is for the Stabilization means a combination of a polyaxial screw and a monoaxial or combinations of several these screws are used. Also, the use of hooks instead of bone screws is also conceivable. In another Embodiment, the rigid portions and / or the elastic Section curved.

Figures 11 to 17 show preferred applications of the invention Stabilization device with the rod-shaped Element. In the stabilization device of FIGS 11 to 14 is the rod-shaped element according to the fourth embodiment used which has the core 110th The stabilization device is used, for example, if a slightly are supported or moderately defective intervertebral disc 6 to and exposure to harmful forces on the intervertebral disc be avoided by limiting movement of the vertebrae should. The rod-shaped element 102 is rigid in the axial direction and allowed neither a compression nor an extension in the axial Direction. Flexion at an angle α to Rod axis, which is for example up to ± 8 °, however, possible.

Fig. Figure 15 shows the application of the stabilization device with the rod-shaped element in a fusion of two vertebrae 4, 5 by means of a rigid element 200, for example, a titanium cylinder, after removal of the natural disc. Here is a higher stiffness of the rod desired, to a sufficient To achieve movement limitation. The minor However, possibility of movement of the vertebrae to each other is compared to exclusively rigid connection advantageous because of the increased cyclic partial loading bone growth is excited and the ossification therefore faster progresses.

Fig. Figure 16 shows the application of the dynamic stabilization device as a flexible end of a long segment fusion, in the more, in the example shown three vertebrae 5, 5 ', 5' 'each other be fused via rigid elements 200 and posterior are connected via a rigid rod 300th The Andes last vertebra 5 of the merged chain adjacent natural Disc 6, and the next vertebrae 4 are above average Loads, which in a higher wear the disc 6 lead. This neighboring segment before unusual Movements, thereby protecting increased loads, the stabilization device as RLD provided. The rod 300 has in this embodiment, a rigid section 308, of such a size is that this three pedicle screws 2, 2 ', 2' 'are connected can, adjacent thereto, the elastic portion 309 provided and at the end again a rigid section 307 to Connect with the pedicle screw. 3

Fig. Figure 17 shows the use of the rod-shaped element 1 in a Stabilization device according to an external fixator for Stabilizing eg bones. Bone parts 30, 31 are via bone screws 32, for example via a connecting element 33 with a rigid rod 34 and an inventive rod-shaped element 1 are connected, stabilizes.

In an inventive manufacturing process for the rod-shaped Element is in a first step, a rigid rod a desired diameter from a body-compatible Material, such as titanium provided. subsequently at a portion between the ends of the rod , it means Milling the elastic portion 9, 900, 902 in the form of a generates coil spring. The passing through the spring section Core 110 is then, if desired, drilled out, whereby the bar prepared according to the first embodiment is.

For generating the rod according to the fourth embodiment, the core 110 either left or a separate core subsequently inserted.

For generating the rod according to the second embodiment, as starting material, a rod having a diameter corresponding to the Diameter of the desired elastic portion 90 corresponds, provided. Thereafter, the helical spring produced by milling. Then, the rigid end portions 7, 8 turned to the desired diameter.

For manufacturing the rod according to the third embodiment, at points of the elastic portion, which in 180 ° circumferentially are offset from each other in a range Distant, so as to produce an oriented sidecut.

A further embodiment is shown in Figs. 18a to 18d shown. In this embodiment, the core 120 is designed such that it at least in a part of the elastic Portion 9 in the plane perpendicular to the rod axis a rectangular cross-section (see FIG. 18). The rectangular Cross-section is as shown in Fig. 18d is shown, with one long side 120a and one short side 120b formed. As shown in FIG. 18b, the core 120 thereby preferably in the areas located at an inserted core 120 are in the rigid portions 7, 8 a to the internal diameter the bore 10 adapted round cross-section, so that a fixing of the bar as in the above Embodiments is guaranteed. The attachment can be used to Example by a transversely-running through a bore 122 extending pin can be achieved.

The rectangular design of the core 120 in the area of the elastic portion 9 is a large bending rigidity in the direction of the long side 120a of the rectangular section and a lower flexural rigidity in the direction the short side 120b of rectangular cross section generated. ever can, after alignment of the core 120 for certain applications increased mobility in one direction and one in the Relation to restricted mobility in the direction are made possible perpendicular to this. Compared to the embodiments wherein no core or a wire in the bore are provided, while the tensile and compressive strength elevated. Furthermore, the torsional stiffness can be obtained by selecting a suitable core set.

In order to achieve the effect described, the portion of the must Core does not necessarily have a rectangular cross-section, but also other cross-sectional shapes, such as a oval cross-section, a substantially rectangular cross-section with partially concave or convex shaped sides or even a substantially triangular cross-section may vary be selected for desired properties. Is important, that the cross section in two mutually perpendicular axes (or at least in two different directions) in the plane perpendicular to the rod axis different dimensions. This are directional bending stiffness achieved.

The core 120 may, in this embodiment as in the other Embodiments (from the geometry dependent) again either formed integrally with the rod or separately formed be and used in these. A combination of this Core 120 with the other embodiments, it is possible to the properties of the rod-shaped element to the respective requirements adapt.

In the embodiment shown in FIGS. 19A to 19C and Fig. 20a is provided a special attachment for the core. As shown in Fig. 19c, closes in the rigid sections 7, 8 each in the direction of the free end the rod-shaped element to the bore 10 a coaxial these disposed second bore 10a, 10b. In the illustrated Embodiment, the rigid sections 7, 8 both sides of the elastic portion 9 is formed symmetrically, therefore in the following with reference to FIG. 20a, only the portion is described eighth

In the second bore 10b is adjacent to a bore 10 Head receiving portion 131 is provided, which in the direction perpendicular to having the axis of the second bore 10b has an outer diameter, the substantially to the inner diameter of the second Hole 10b corresponds. The head receiving portion consists of two Shells 131a, 131b, in the direction of the axis of the bore 10 are arranged and each enclose a cavity 133, substantially the shape of a in the direction of the axis of the having bore 10 straight ball. In the faces of the Shells 131a, 131b are coaxial with the second bore 10b bores provided 132a and 132b, the diameter of the Cavity 133 increases towards the respective end face and some is greater than the diameter of the core 130th

The outer diameter of the core 130 is substantially smaller than the inner diameter of the bore 10. The the rigid section 8 facing the end of the core 130 is provided with an external thread 137 provided, the one with a female thread 138 in a bore Head portion 134 cooperates. The head portion 134 is shown in Fig. 20b shown. It consists of two substantially hemispherical Halves 134a and 134b which composed a substantially comprise spherical outer surface with a diameter, is greater than the smallest diameter of the bore 132b, and is smaller than the smallest diameter of the cavity 133rd The provided with the outer thread-free end of the core 130 is passed through the bore 132b and into the cavity 133 in the arranged halves 134a and 134b screwed the head part 134, cooperating as nut and lock nut.

The other free end of the core 130 is in the rigid section 7 taken in a similar manner. Depending on how far the head portions 134 on the two free ends of the core 130 are screwed, are the head portions 134 on the inner sides the head receiving parts 131, which faces the bore 10 are located at the free ends of the second holes 10a, 10b facing inner sides or reject to these inner sides each game to something.

In this embodiment, by forming the spherical the head members 134 in cooperation with the substantially spherical shape of the head receiving parts 131, the headboards 134 slide into the head receiving parts 131st In an acting external bending stress is thus a bending load of Core 130 preventing small deflections. By screwing of the head portions 134, so these core-side on the insides of the head receiving parts 131 and to the core facing away lie inside of the head receiving parts 131, a tensile or pressure boosting for the rod-shaped element can be achieved. By sided game of the headers 134 in the receiving parts 131 can be adjusted so that an effect of the Core until a certain lengthening of or shortening of the Outer area of ​​the rod-shaped element occurs.

In FIGS. 19 to 20a is exemplified that the Receiving parts 131 with screws 135 in the second bores 10a, 10b are fixed; however, it is for example also possible for fastening lateral screws as with other Embodiments or press-fit connection between the head receiving parts provide and second bores.

Furthermore, combinations of parts of these embodiments possible with other embodiments.