Height-adjustable implant to be inserted between vertebral bodies and corresponding handling tool

ES 2 249 757 T5

DESCRIPTION

Height-adjustable implant for placement between dorsal vertebrae and manipulation tool.

The present invention relates to a height adjustable implant for placement between dorsal vertebrae.

An implant known, for example, from document DE 196 22 827 A1, has a first and second bushings, so that the second bush has an external thread, being fixed in rotation by means of a longitudinal section in the first bush and capable of axial displacement, and that, in its longitudinal section, which protrudes from the first bushing, is surrounded by a nut engaged in the external thread. By turning the nut, the second bush moves out of the first bush. For displacement of the nut, a rod-shaped hand tool is engaged with its free end in a recess in the outer periphery of the nut. By moving the tool vasculation in a plane that runs perpendicular to the longitudinal axis of the implant, the nut will be forced to rotate in a segment that will correspond to the tool's angle of vasculation. The tool will then be removed from the nut, and the process described will be repeated until the implant is of the required height. During the turning movement of the nut, the first bushing must not turn, so it must usually be fixed with another additional tool. The height adjustment in the implant of known type therefore requires the application of a long time and several devices. Furthermore, a relatively large operating opening is required in order to be able to carry out the indicated manipulations without hindrance.

A height adjustable implant is known from US 2003 / 045877A, according to the introductory part of claim 1.

Document DE 100 65 232 A1 shows in Figures 2-8 an implant (10), adjustable in height, for its placement between dorsal vertebrae, which has a first and a second sleeve-shaped parts (2), (3) , so that the second bushing part (3) has an external thread (6) which is positioned in a longitudinal section on the first bushing part (2) in a rotationally fixed and axially displaceable manner, that is to say , by the collaboration of the guide groove (8) with the pins (9), and in its longitudinal section that protrudes from the first bushing-shaped part (2) it is enclosed within a nut (4) coupled to the external thread (6), which has a toothed ring (7).

Publication JP 2-261446 shows an implant with height adjustment capacity for placement between dorsal vertebrae with two implant pieces (9), (14), the height adjustment capacity of which is guaranteed by an external thread (10) arranged in the implant part (14), in which a longitudinal adjustment ring (19) having a bevel gear tooth is fitted. The latter is fixed on the first sleeve-shaped part with a stop that acts axially (20) with the length adjustment ring (19) of the nut, which limits the displacement of the length adjustment ring (19), it is that is, of the nut, in the longitudinal direction.

Starting from this, it is an objective of the present invention to provide an implant and manipulation tool with which placement in the dorsal column is facilitated.

This objective is solved by the object of claim 1.

According to claim 1, the nut has a toothed ring, that is to say it is in the form of a toothed ring. With the aid of a tool with an appropriately shaped element, for example a drive gear, the height of the implant can be adjusted so that no vasculating movements have to be performed with the manipulation tool. In addition, it is not necessary to carry out multiple investments of the tool. On the contrary, the same and only position can be maintained during the entire height adjustment process, which considerably simplifies the operation and the time necessary for it.

In a preferred arrangement, the nut supports the toothed ring on its underside facing the first bushing. The drive of the nut can take place, in this case, by means of a drive gear, the axis of rotation of which runs perpendicular to the axis of rotation of the nut. Reversal of the rotational movement of the shaft, as would be the case in a drive sprocket with axis directed parallel to the axis of rotation of the nut, is not necessary, so that the compact construction in general is favored, and they are reduced manufacturing complications.

In order to guarantee the rotational fixing of the first bushing, a threaded hole is arranged in it in which a manipulation tool that operates the nut can be fixed. Unlike implants of the type known to date, only a single tool is necessary, both for actuating the nut and for fixing the first sleeve.

In the implant known from DE 196 22 827 A1, the nut is supported by the movement of the second sleeve on the front face of the first sleeve facing towards it. Otherwise, the nut is not attached to the first bushing. The height of the known implant can therefore only be increased but cannot be reduced, that is, the second sleeve cannot be inserted into the first sleeve. On the contrary, in the implant, according to the present invention, the nut is fixed with conjugate axial drive coupling, also in axial direction in the first sleeve, so that it is possible to increase and also decrease the

ES 2 249 757 T5 implant height. This last maneuver may be necessary, for example, when, after implant placement, too great an adjustment height has been set.

In the invention, both bushings have windows opening at their respective ends directed towards each other, arranged axially, so that the surrounding sections arranged between two adjacent windows are arranged axially displayable in the window of the other bush. Contrary to the arrangement in which the two bushings are concentrically coupled to each other, this has the advantage of requiring a smaller amount of material and that the implant is generally lighter. In addition, a larger internal space is available that can be filled with bone material or the like. By coupling both bushings, one with the other, in the form of a comb, a fixation against rotation is finally ensured on both sides.

Preferably, to support the implant on a dorsal vertebra, a radially widened front plate is provided. In a preferred arrangement, it is a detached piece detachably attached. The appropriate face plate can then be used in any individual case, for example a plate with a plane running obliquely relative to the median longitudinal axis of the implant. If the front plate is fixed with the aid of a quick connection to the bushing, on the one hand, a more secure retention on the bushing and, on the other, a possibility of easy replacement is guaranteed. The simple embodiment, from the point of view of manufacture and assembly, according to the invention provides that near the front face an annular groove is arranged in the inner wall of the bushing, in which the projections formed on the lower face can be engaged. from the front plate.

The manipulation tool for the implant of the type described has, according to claim 10, a gear wheel associated with the nut. Preferably, there is a retaining device for fixation of the implant on the manipulation tool. The toothed wheel is arranged such that its axis runs perpendicular to the axis of the toothed ring when driving the nut. It is not necessary, as explained above, the reversal of the rotational movement of the drive shaft. According to a particularly interesting embodiment for saving space and ease of service, it is envisaged that the toothed ring is arranged on the front face of a tube section, and that the tube section is traversed by a rod whose free end projects of the tube section, and can be threaded into the threaded hole of the first bushing. The coaxial arrangement of the tube section and the rod allows a compact handling tool and simplified operation.

The present invention will be explained below, based on the attached drawings, in which:

Figure 1 shows a partially sectioned perspective view of an implant with a first sleeve and a second sleeve arranged in the first and capable of axial displacement, so that the second sleeve is arranged in its insertion position, Figure 2 shows the implant of figure 1 with the second sleeve partially inserted, figure 3 shows a perspective view of the first sleeve, Figure 4 shows a perspective view of the second movable sleeve, Figure 5 shows a nut that can be used to drive the first sleeve, Figure 6 shows a front plate that can be attached to a sleeve, and Figure 7 shows a tool for manipulating the implant.

The implant shown in the figures has, as main parts, a first sleeve (1), a second sleeve (2) and a nut (3). The bushing (2) is provided with an external thread (4) that extends substantially over its entire length. Both bushings (1), (2) have windows (6) that open into their front faces (5a), (b), facing each other in the assembly state and running axially. The surrounding sections (7a), (7b), which exist between two adjacent windows, are in the windows (6) of the other of the bushings (1), (2), with axial displacement capacity. In this case, the play between the surrounding sections (7a, b) is provided in such a way as to guarantee a play-free seating of both parts of the bush, one inside the other, and an easy sliding capacity. The sleeve pieces (1,2) have approximately equal wall thickness and the same inside diameter, that is, the surrounding sections (7b) of the second sleeve piece (2) lie either on the outer periphery or on the inner periphery of the bushing (1). The axial length of the window (6) or of the peripheral sections (7a, b) has dimensions such that, in the maximum entry situation of the sleeve (2), between the front face (5a, b) of a peripheral section (7a, b) and the base (8) of a bushing (1,2), there is an axial gap (9).

For the height adjustment or for the introduction and extraction of the part (2) of the bush, the nut (3) is available, which comprises both parts of the bush (1,2). This is connected to the first sleeve with axial and rotary fixation. The internal faces that comprise both bushing pieces (1,2) have an upper longitudinal section with an internal thread (10) and a connecting longitudinal section (13) that is thread-free. In this, an annular groove (14) is made. The nut (3) is therefore arranged on the bushing (1), in such a way that only the thread-free longitudinal section (13) comprises the peripheral section (7a) of the bushing (1) and that the

ES 2 249 757 T5 internal thread (10) is coupled with external thread (4) of bushing (2). Near the front face (5a) of a peripheral section (7a), a projection (15) extending over the entire width of the latter has been formed with a circular sector structure, which engages in the annular groove ( 14) from the nut. The nut (3) can therefore rotate in the bushing (1), but is fixed therein in both axial directions. The face directed towards the free ends of the peripheral section (7b) of the nut (3) supports a toothed ring (17) that runs coaxially to the median longitudinal axis (16) of the implant. The ring gear (17) forms a single piece with the nut (3), for example, by milling. It is intended to adjust the nut (3) with the help of another tool that has not been described in detail by displacement by turning, and in this way to produce the displacement of the bushing (2) with respect to the bushing (1), outwards or into the latter, that is, adjusting it to the height of the implant.

The front faces (18) that move away from the free ends of the peripheral sections (7a, b) support a front plate (19) which is arranged radially on the periphery of the bushings (1,2) outwards. The front plates (19) can be fixed with the help of a removable type quick clamping element in the bushings (1,2). For this purpose, an annular groove (20) is found on the internal face of the bushings (1,2) in the vicinity of their front faces (18), in which retaining projections (23) arranged in the faces of the face plate directed towards the face faces (18a, b). The retention projections (23) are formed in a skirt (24) that surrounds a central opening (21) of the front plate (19). On the edge (25) of the skirt (24), several recesses (26) are arranged in the peripheral direction and with regular distribution. The periphery sections (27) disposed between the recesses (26) support the retention projections (23). The peripheral sections (27) can be moved slightly radially inward elastically, so that the attachment or detachment of the front plate (19) is facilitated. On the external faces (28) of the front plates (19), there is a ring (29) provided with projections pointed in the direction of the longitudinal axis (16). These are intended for insertion fixation of the implant into a vertebra.

Two openings (30) have been arranged in the peripheral sections (7a). The openings (30), as well as the central opening (21) of the face plates (19), are intended to be filled with bone material, bone cement or the like. In one of the peripheral sections (7a), a radially directed threaded hole (33) is located near the nut (3). This acts to fix the handling tool described below.

As can be seen in figure 7, said tool is essentially constituted by a rod (34) which, at one end, has a handle (35) and which, at the other end, has a threaded section (36). The area remote from the thread section (36) of the rod (34) is coaxially surrounded by a rotating bushing (37). The end of the rotating bushing (37) directed to the knob (35) supports a knurled wheel (38) and the opposite end a toothed ring (39). This is manufactured in a similar way to that of the nut (3), by pressing the front face of the bushing. The axial movement of the bushing (37) in the direction of the handle (35) is limited by a stop flange (39).

For the height adjustment of the implant, for example, starting from the situation shown in figure 1, the molecular tool will be rotated with its thread section (36) engaged in the threaded hole (33). The threaded ring (39) is coupled with the toothed ring (17) in a similar way to a drive by means of a toothed ring, that is, the axis of the toothed ring (39) runs substantially perpendicular to the axis of the toothed ring (17 ). The knurled wheel (38) rests, in this case, on the stop flange (29).

After the implant has been placed with the aid of the manipulation tool via an operating opening in the spine, the rotary sleeve (37) will be moved to adjust the implant to a greater height by turning the knurled wheel. (38). When it comes to the external thread (4) of the bushing (2) and the internal thread (10) of the nut (3) with right-hand threads, the nut (3) must be turned in the direction of the arrow (40) and the knurled wheel must be turned in the direction of the arrow (43). To release the manual manipulation tool from the implant, this thread section (36) will be separated by twisting the handle (35) out of the threaded hole (33). Since the bushing (37) and rod (34) can rotate, it is not necessary to hold the rotatable bushing fixed during outward threading of the thread section (36). The setting of the relative position adjusted between both bushings (1,2) can be carried out with the help of different means. A simple possibility consists of threading into the threaded hole (33) provided with a certain point (not shown).

List of designations (1) First bushing (2) Second bushing (3) Nut (4) External thread (a, b) Front faces a, b (6) Window

ES 2 249 757 T5 (7a, b) Peripheral section (-a- = first bushing;

-b- = second bushing) (8) Base (9) Axial clearance (10) Internal thread (13) Longitudinal section (14) Annular groove (15) Projections (16) Middle longitudinal axis (17) Toothed ring (18) Face face (19) Face plate (20) Annular groove (21) Opening (23) Retaining boss (24) Skirt (25) Edge (26) Recess (27) Peripheral section (28) External face (29) Ring with pointed projections (30) Opening (33) Threaded hole (34) Rod (35) Handle (36) Threaded section (37) Threaded bushing (38) Knurled wheel (39) Stop flange (40) Arrow (43) Arrow.