KR20070023556A - Rod-shaped Implant Element for the Application in Spine Surgery or Trauma Surgery and Stabilization Device with such a Rod-shaped Implant Element - Google Patents

Abstract

A rod-shaped implant element for connecting at least two bone fixation elements 2, 3 each comprising a fixation portion 21, 21 ′ fixed to the bone and a receiving member 22, 22 ′ connected to the rod-shaped implant element Is provided. This rod-shaped implant element includes a longitudinal axis A; At least one stiff portion (4; 61) of at least one first length having a shape co-operating with the receiving members (22, 22 ') and a shape received within the receiving members (22, 22'); A second length flexible portion (8; 65; 71) located adjacent to the rigid portion; A bore extending along the longitudinal axis and extending through the rigid portion and the flexible portion (9; 66; 67); And a core 12 received in the bore, having two opposing ends, wherein at least one end of the core is free to move within the bore when the flexible portion expands and contracts in the longitudinal axis direction.

Bone, fixation, stabilization, rod, implant, core

Description

Rod-shaped Implant Element for the Application in Spine Surgery or Trauma Surgery and Stabilization Device with such a Rod-shaped Implant Element

1 shows a known bone stabilization device in a neutral position of the motor segment of the spine.

FIG. 2 shows the bone stabilization device of FIG. 1 in a curved position. FIG.

3 shows the bone stabilization device of FIG. 1 in an extended position.

4 is a side view of a known rod-shaped implant element.

Fig. 5 is a side view when a bending force is applied to the known rod-shaped implant element.

6 is a side view of a first embodiment of a rod-shaped implant element.

FIG. 7 is a longitudinal cross-sectional view taken along the longitudinal axis of the rod-shaped implant element of FIG. 6. FIG.

8 is a cross-sectional view of the core of the rod-shaped implant element.

9 is a perspective view of one embodiment of a stabilization device with rod-shaped implant elements according to the present invention.

10 is a cross-sectional view of the stabilization device of FIG. 9.

11 is a side view of a second embodiment of a rod-shaped implant element.

12 is a cross-sectional view of the rod-like implant element according to the second embodiment.

FIG. 13 is a cross-sectional view of the rod-shaped implant element of FIG.

14 is a cross-sectional view of the rod-like implant element according to the third embodiment.

15 is a side view of the rod-shaped implant element of FIG. 14.

16 is a cross-sectional view of the rod-like implant element according to the fourth embodiment.

17 is a side view of the rod-shaped implant element of FIG. 16.

The present invention relates to a rod-shaped implant element applied in spinal surgery and / or trauma surgery. The rod-shaped implant element includes a rigid portion and a flexible portion adjacent to the rigid portion. A bore extends through the rigid portion and the flexible portion, and the core is accommodated in the bore. At least one end of the core is free to move in the bore. The invention also relates to a stabilization device having the rod-like implant element.

In the past, various studies have been conducted on devices for stabilizing the spine while allowing some degree of movement between adjacent spines in case of intervertebral defects.

EP 0 669 109 B1 discloses a stabilization device for stabilizing adjacent thoracic vertebrae. This device can partially relieve stress in the damaged intervertebral disc and intervertebral joint. The device includes a strap secured in the receiving member of each pedicle screw by two pedicle screws and a clamping screw. The device also includes a support element mounted on the strap to act as a pressure resistor. However, the stabilization device does not provide torsional stiffness and therefore does not provide guidance and guidance stability of the spinal segment of motion.

US Pat. No. 6,162,223 discloses a joint fixation device such as, for example, a wrist or knee joint. The apparatus according to the embodiment of the patent

A flexible coupler having an elongated coil spring with two clamps at both ends and a flexible cable or a flexible rod extending through the flexible coupler and fixed to the clamp are included. This joint fixation is not suitable for use in the spine because of its complex configuration and bulkiness.

US patent application US 2003/0220643 A1 discloses a stretchable element for use in a device for preventing complete elongation between the upper and lower vertebral bodies. The stretchable element may, for example, consist of an elastic cord or a spring.

US patent application US 2003/0191470 A1 discloses an implant device having a rod member which is curved at the center when the patient bends the spine. The curved portion may be configured as a straight rod having various cross-sectional shapes or a non-linear rod having a portion bent in a U shape to one side of the axis.

Dynamic stabilization devices are particularly suitable for the treatment of partially degenerated intervertebral discs. Intervertebral discs should relieve stress to aid recovery. If the nucleus of the intervertebral disc is not damaged, the intervertebral disc is rigid (stiffness of about 500-1500 N / mm) in the axial direction of the spine.

1-5 show spinal stabilization devices for the treatment of known degenerated intervertebral discs. Two pedicle screws 2, 3 are fixed to the vertebrae 20, 30 adjacent to the degenerated intervertebral disc 40. The nucleus of the degenerated intervertebral disc 40 is intact. The pedicle screws 2, 3 are connected via a rod-shaped implant element 100 having a helical spring shape 101 and two rigid parts 102, 103. The two rigid portions have a function of connecting the pedicle screws 102 and 103. 1 shows the neutral position of the pedicle screw spaced apart by a distance x. If the patient bends the spine, the distance changes. In the bent state of the spine shown in FIG. 2 or in the unbalanced state of the spine shown in FIG. Increase by about 1.5 mm or decrease by about 0.5 mm relative to x.

Thus, in order to stretch the flexible portion of the rod-shaped implant element as needed, the flexible portion must have low rigidity or high flexibility in the direction of the longitudinal axis 104. However, when the flexible part 101 has a low rigidity in the axial direction, it has a low rigidity with respect to the bending force and a low rigidity with respect to the shear force F as shown in FIG. Bending deformation occurs. This problem occurs not only when using metal springs but also when using flexible parts made of other elastic materials such as elastomers.

German patent DE 103 48 329 C1 has an elongated rod having a first rigid portion intended to be connected to a bone fixation element, a second rigid portion intended to be connected to a second bone fixation element, and a flexible portion integrally extending between these two rigid portions. Implant elements are disclosed. The rod-shaped implant element has a coaxial bore extending therethrough and a core received within the bore. The core is fixed so as not to slide in the bore.

The international patent WO 2004/105577 discloses a spinal stabilization system having one or more flexible elements with one opening or slit in the wall. The flexible element consists of a first rod and a second rod, the second rod being fitted, for example, by indentation into the bore of the first rod.

However, these flexible rod-shaped implants do not solve the problem because bending deformation or kinking occurs when they have sufficient flexibility in the axial direction.

Accordingly, an object of the present invention is a rod-shaped implant element having an axial stiffness which allows the bone fixation element to be relatively moved along the axial direction and at the same time prevents or reduces bending deformation in the direction transverse to the axial direction To provide a stabilizing device for a bone or spine having the same rod-like implant element. The rod-shaped implant element should be easy to manufacture, easy to adjust and use.

This object is achieved by a rod-shaped implant element according to claim 1 and a stabilization device according to claim 12. Further feature configurations are disclosed in the dependent claims.

The rod-shaped implant element and stabilization device can be expanded in the axial direction to allow relative movement between the bone fixing elements, and at the same time has the advantage of preventing bending deformation or torsional deformation. In particular, the rod-shaped implant element is suitable for the treatment of partially degenerated spinal elements.

Further advantages of the present invention will become more clearly understood from the following description of the embodiments described with reference to the accompanying drawings.

As shown in FIGS. 6 to 13, the stabilization device according to the invention comprises two pedicle screws 2, 3 interconnected by a rod-shaped implant element 1 and a bi-rod implant element 1. do.

The rod-shaped implant element 1 according to the first embodiment of the present invention comprises a first rigid portion 4 extending from the first end 5 by a predetermined length, and a second extending portion 7 extending from the second end 7 by a predetermined length. And a flexible part 8 extending between the second rigid part 6 and the first and second rigid parts 4 and 6 by a predetermined length. The outer diameters of these first and second rigid portions and the flexible portion are the same. A coaxial bore 9 having a predetermined inner diameter is penetrated inside the rod-shaped implant element. The flexible part 8 consists of a spiral slot opening 10 extending radially from the surface to the coaxial bore 9 and windings 11 of a predetermined pitch formed thereby. The side surface of the said spiral opening can be comprised in linear form or inclined form. The inner diameter of the coaxial bore 9 for determining the height in the longitudinal axis A direction of the rod-shaped implant of the winding part 11 of the flexible part 8, the thickness in the radial direction of the winding part 11, and the winding. The negative pitch is chosen to be dimensioned to have a certain stiffness with respect to the axial stretching force acting on the rod-shaped implant element 1. One skilled in the art can easily change the dimensions without performing more experiments than necessary.

The rod-shaped implant element 1 is made of a biocompatible material such as titanium, stainless steel or nitinol.

In particular, as shown in FIG. 7, the rod-shaped implant element 1 further comprises a core 12. The core is substantially cylindrical, the length is shorter than the length of the rod-shaped implant element, the diameter is smaller than the inner diameter of the coaxial bore 9, and is free to slide freely in the axial direction within the coaxial bore 9. The length of the core 12 is at least equal to the length of the flexible part 8. In the illustrated embodiment, the core 12 extends through the flexible portion 8 and a part of the first and second rigid portions 4, 6.

The length of the core 12 is selected such that the length of the core 12 does not contact the end of the rigid portion when the flexible portion 8 is pressed. The core 12 is made of a material having rigidity capable of countering the bending force or more of the rigidity of the flexible portion 8 of the rod-shaped implant element. The core 12 is preferably made of a biocompatible polymer or metal material having rigidity greater than that of the flexible part 8. The core 12 is constrained in the coaxial bore 9 by two closure members 13, 14 provided at both ends 5, 7 of the rod-shaped implant element. The closure members 13 and 14 have a shape for closing the coaxial bore 9 and are fixed to the rigid portion by, for example, screwing or pressing.

In the preferred embodiment shown in FIG. 8, the core 12 is coated with a coating 15 of a material which is capable of low friction sliding against the inner wall of the coaxial bore 9. The coating is made of polyethylene (PE), teflon or other material that reduces friction, for example. As an example of the coating material, a high molecular weight polyethylene of UHM WPE type having a molecular weight of 2 × 16 ⁶ to 10 × 10 ⁶ is used. The thickness of the coating 15 is chosen so that the coating does not wear out completely during the continuous use of the rod-shaped implant element.

As shown in FIGS. 9 and 10, the length of the flexible portion 8 of the rod-shaped implant element 1 is in its neutral position when the pedicle screws 2, 3 are fixed to the adjacent portion of the spine. The length is chosen such that the length essentially corresponds to the distance between the two pedicle screws. Each pedicle screw of the stabilization device has a fixing portion (21, 21 ') having a bone screw for fixing the pedicle screw to the bone and an essentially cylindrical receiving member for receiving the rod-shaped implant element (1). 22, 22 '). 9 and 10, the first pedicle screw 2 is provided with a receiving member 22 having a U-shaped recess 23. The U-shaped recess is open to the upper side (opposite side of the fixing part) of the receiving member for introducing the rigid portion 4 of the rod-shaped implant element from the upper side. The receiving member 22 'of the pedicle screw 3 has two openings 24 instead of a U-shaped recess for inserting the other rigid portion 6 of the rod-shaped implant element. The rod-shaped implant element 1 is fixed in the receiving members 22, 22 ′ by an inner screw 25 which is screwed from the upper side of the receiving member.

In particular, as shown in FIG. 10, the pedicle screws 2, 3 have a head 26 which can adjust the angular position of the receiving member relative to the fixing part by turning in the receiving members 22, 22 ′. It is designed with multi-axis screw. The head 26 is fixed in position by a pressure member 27 that exerts pressure on the head when the inner screw 25 is tightened.

In the example of the stabilization device shown in FIGS. 9 and 10, the length of the rigid portions 4, 6 is at least approximately the diameter of the fixing element 25 which fixes the rod-shaped implant element in the receiving members 22, 22 ′. It is desirable to construct a matching length. As shown in FIG. 10, the diameter of the second rigid portion 6 can be reduced so that it can be easily inserted into the opening 24 of the receiving member. In this case, the coaxial bore 9 does not extend to the second end 7 so that the strength of the second rigid portion 7 has sufficient strength to be clamped by the inner screw 25 in the receiving member 22 ′.

In use, the pedicle screws 2, 3 are first fixed to the adjacencies of the vertebrae. Next, the rod-shaped implant element 1 is inserted into the receiving members 22 and 22 ', and the inner screw 25 is tightened to fix it. The flexible portion 8 of the rod-shaped implant element has axial stiffness to allow about 1.5 mm elongation and about 1.5 mm compression relative to the neutral position. During curvature and extension of the spine, bending forces are applied to the rod-shaped implant elements to flex the flexible portion. However, since the rigidity of the core 12 is greater than the rigidity of the flexible portion 8, the core 12 resists the bending force, and as a result, the rod-shaped implant element is not entirely curved. Thus, the rod-shaped implant element provides guidance and guidance stability.

At least one end of both ends of the core 12 should be able to move freely in the bore 9 to allow for stretching of the rod-shaped implant element.

11 to 13 show a second embodiment of a rod-shaped implant. The rod-shaped implant element 50 of the second embodiment differs from the rod-shaped implant element 1 of the first embodiment in that one end of the core 12 is fixed to the rigid portion. The same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted. One rigid portion (rigid portion 6 in this embodiment) of the rigid portions 4, 6 is provided with a bore 51 extending in the direction transverse to the longitudinal axis A. As shown in FIG. The bore 51 is formed at a position spaced apart from the second end 7 by a predetermined distance. One end of the core 12 is provided with a thickened section 53. The diameter of this thick part is slightly smaller than the inner diameter of the bore 9 so that the thick part 53 can easily enter the bore 9. The lateral bore 54 is formed in the rear portion at a position spaced a predetermined distance from the free end of the core. The core 12 is secured in the bore 9 by pins 55 which are inserted into the bores 51 and 54 when the core is inserted into the rod-shaped implant element. In this case, since the core 12 cannot slide out of the bore 9, it is not necessary to block the bore 9.

The length of the core 12 is such that it extends over at least the full length of the flexible portion 8.

In addition, in this embodiment, the core 12 may be coated with a coating that promotes sliding in the bore.

The state of use of the rod-like implant element is the same as that of the first embodiment.

14 and 15 show a third embodiment of a rod-shaped implant element according to the invention. The rod-shaped implant element of the third embodiment differs in design of the flexible portion from the rod-shaped implant element of the first and second embodiments. The rod-shaped implant element 60 includes a first rigid portion 61 adjacent to the first end 62, a second rigid portion 63 adjacent to the second end 64, and the first rigid portion 61 and the second rigid portion ( The flexible part 65 located between 63 is provided. The first rigid portion 61 and the second rigid portion 63 have a longitudinal coaxial bore 66. Since the flexible part 65 is also provided with a coaxial bore 67, it is substantially tubular. Both free ends of the flexible part 65 are connected to each free end of the first and second rigid parts. The outer diameter of the flexible portion 65 is reduced from the first diameter at both ends to the second diameter at the center portion to promote stretching. The rigid portion is made of a body compatible rigid material, for example titanium, like the first embodiment. The flexible part is made of a body compatible elastomer. The flexible part is fixed to the rigid part by, for example, vulcanization.

Similar to the first embodiment, the cores 12 are provided in the bores 66 and 67 having a length that can freely slide in the bore. The free ends 62, 64 of the rigid portion are closed with a closure member 68, 69 to prevent the core from sliding out of the bore.

The usage state of the rod-shaped implant element of the third embodiment is the same as that of the first and second embodiments. Instead of the expansion and contraction of the helical springs of the first and second embodiments, the elastomer of the flexible part 65 performs expansion and contraction here.

16 and 17 show a fourth embodiment in which the third embodiment is modified. The rod-shaped implant element 70 of this embodiment differs only from the shape of the flexible portion 71 from that of the rod-shaped implant element 60 of the third embodiment of FIGS. 14 and 15. The diameter of the flexible part 71 changes from the 1st diameter of both ends to the 2nd diameter of the center. The second diameter is larger than the first diameter. The rod-shaped implant element of this type is particularly suitable when the rigidity is larger than that of the third embodiment, and thus the amount of stretching is small. The use state is the same as the use state of the above-described embodiment.

This embodiment is adaptable. In particular, it is possible to combine the elements of each embodiment. Each part of the above-described plurality of embodiments can be combined, and such a combination has been contemplated.

In a modification, it is possible to add a reinforcing member acting as a core to the inside of the core. For example, a metal reinforcing member that can increase the rigidity of the core can be provided inside the core made of a biocompatible polymer. This reinforcement member can be provided only in the length of a part of core (for example, only in a center part).

The rod-shaped implant element may be provided with a plurality of rigid portions and flexible portions. The diameter of the flexible part can be the same as or different from the diameter of the rigid part. If necessary, a plurality of reduced diameters can be formed in the core to reduce the rigidity. The core may be composed of a hollow body. In addition, the shape of the core does not need to be cylindrical, and for example, it may be configured as a rectangular cross section so as to provide directional bending rigidity. In addition, the outer surface of the core can be subjected to a special surface treatment such as polishing to reduce the frictional force. The core is secured to one end of the rigid part by any means including, for example, screwing or bonding.

The stabilization device may be provided with other bone fixation means, for example a single screw or a hook.

The present invention can provide a rod-shaped implant element capable of relatively moving the bone fixation element along the axial direction and at the same time preventing or reducing bending deformation in the direction transverse to the axial direction.

Claims (12)

To the rod-shaped implant element for connecting at least two bone fixation elements 2 and 3, each comprising a fixing portion 21, 21 'fixed to the bone and a receiving member 22, 22' connected to the rod-shaped implant element. In The rod-shaped implant element, Longitudinal axis (A); At least one stiff portion (4; 61) of at least one first length having a shape co-operating with the receiving members (22, 22 ') and a shape received within the receiving members (22, 22'); A second length flexible portion (8; 65; 71) located adjacent to the rigid portion; A bore extending along the longitudinal axis and extending through the rigid portion and the flexible portion (9; 66; 67); And A core 12 having two opposing ends, received in the bore; And at least one end of the core is freely movable within the bore when the flexible portion is stretched in the longitudinal axis direction. 2. The rod-shaped implant element according to claim 1, wherein the bending stiffness of the core (12) is greater than the bending stiffness of the flexible portion (8; 65; 71). The rod-shaped implant element according to claim 1 or 2, characterized in that the surface of the core (12) is coated with a material which promotes sliding. 4. The rod-shaped implant element according to claim 3, wherein the material is a plastic material such as polyethylene or teflon. The rod-shaped implant element according to any one of claims 1 to 4, wherein the core is made of stainless steel, titanium, nitinol or rigid plastic material. 6. The rod-shaped implant element according to any one of claims 1 to 5, wherein the core has a portion with reduced bending stiffness relative to the other portion. 7. The rod-shaped implant element according to one of the preceding claims, wherein the entirety of the core (12) is free to move in the bore in the direction of the longitudinal axis (A). 8. A rigid length part (6; 63) of claim 1, wherein the flexible part (8; 65; 71) has two opposing ends and is of a first length. The rigid part (4; 61) is adjacent to the first end, and the rigid part (6; 63) of the third length is adjacent to the second end. The rod-shaped implant element according to any one of claims 1 to 8, wherein the rigid portion and the flexible portion are formed of a continuous single member. 10. The flexible portion (8) according to one of the preceding claims, characterized in that the flexible portion (8) comprises an outer surface and a spiral slot opening (10) formed on the outer surface, the slot extending radially inward. Rod implant element. 10. The rod-shaped implant element according to any one of the preceding claims, wherein the flexible portion (65; 71) is formed of an elastomer. Bone anchors 21, 21 ′, receptacles 22, 22 ′, and rod-shaped implant elements 1, 50; 60; 70, respectively, adapted to be fixed to bones. A stabilizing device for bone, in particular a spine, having at least two bone fixation elements (2, 3) comprising: said rod-shaped implant element is connected to said bone fixation element.

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