DE20116410U1 - Surgical instrument - Google Patents

Description

A 56 297 u Aesculap AG & Co. KG

&zgr; - 279 Am Aesculap-Platz

26 September 2001 78532 Tuttlingen

SURGICAL INSTRUMENT

The invention relates to a surgical instrument for inserting a vertebral replacement body, with at least one holding element for holding the vertebral replacement body in an application position, with at least one locking element assigned to the at least one holding element, wherein the at least one holding element in the application position limits the vertebral replacement body in at least one degree of freedom of its movement relative to the at least one holding element and wherein the at least one locking element can be brought into engagement with the vertebral replacement body in the application position such that all other degrees of freedom of movement of the vertebral replacement body relative to the at least one holding element that are not limited by the at least one holding element are limited by the at least one locking element.

Due to severe injuries to the spine or as a result of partial resection of a vertebral body, it may be necessary to replace the original vertebral body in whole or in part with a vertebral replacement body. To facilitate such an operation, surgical instruments are used to hold the vertebral replacement body and insert it between adjacent vertebrae of the spine. It is particularly important that the vertebral replacement body is connected to the instrument during insertion in such a way that

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is that it is held securely and at the same time forces can be transmitted.

An instrument of this type is known, for example, from WO 01/19295. In order to insert an implant, a part of it is placed on two pins arranged on an arm in the longitudinal direction of the arm, whereby the arms can be rotated with the pins arranged on them. Locking projections arranged transversely on the pins engage in corresponding recesses in the implant part after the arms have been rotated, so that its degrees of freedom of movement relative to the pins or to the arm are completely limited.

However, this insertion instrument, which is primarily optimized for an intervertebral implant, is only partially suitable for inserting a vertebral replacement body. In particular, it is often disadvantageous that the arms have to be pivoted to lock the implant on the instrument.

It is therefore an object of the present invention to improve a surgical instrument of the type described above in such a way that it can be connected to a vertebral replacement body particularly easily while maintaining at least the same stability.

This object is achieved according to the invention in a generic surgical instrument in that the at least one

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locking element is movable relative to at least one holding element.

Unlike the instrument known from WO 01/19295, the holding element and the locking element are completely separate in their function. The holding element only serves to hold the vertebral replacement body, whereas the locking body only serves to limit the remaining degrees of freedom of movement of the vertebral replacement body relative to the holding element. The relative mobility of the two elements to one another allows the holding element to be optimized in its holding function, whereby it does not have to be moved in any way to lock the vertebral replacement body to the holding element. For this purpose, the locking element can be moved separately from the holding element and thus establish a connection with the vertebral replacement body and also release it again due to its movement.

It is particularly advantageous if the at least one holding element comprises a receptacle with a guide for introducing the vertebral replacement body in a predetermined plane. In this way, at least one degree of freedom of movement of the vertebral replacement body relative to the holding element can be determined by the holding element itself. Furthermore, the guide makes it easier to pick up the vertebral replacement body using the holding element.

According to a preferred embodiment of the invention, it can be provided that the guide is a linear guide for introducing the

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Vertebral replacement body in a predetermined insertion direction. This makes it even easier to pick up the vertebral replacement body with the holding element. In addition, two degrees of freedom of movement of the vertebral replacement body relative to the holding element can be restricted.

The vertebral replacement body can be picked up from the holding element particularly easily if the holder is essentially U-shaped.

In order to limit the degrees of freedom of movement of the vertebral replacement body relative to the holding element in the desired manner and to increase the stability of the connection between the holding element and the vertebral replacement body, it can be advantageous if the receptacle has a stop and if the stop is arranged parallel to the predetermined plane to limit a movement of the vertebral replacement body transverse to the plane.

It is particularly advantageous if the stop includes a partially semi-circular projection. This can be manufactured particularly easily and offers optimal support of the vertebral replacement body on the holding element.

In order to set a desired lordosis angle or to enable the vertebral replacement body to be adapted to adjacent vertebral bodies, it is advantageous if at least one holding element is arranged so that it can rotate. In this case, rotation can be provided around any spatial axis.

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It is advantageous if an angular position of the at least one holding element can be fixed. If the holding element is tilted by a certain angle, for example relative to another holding element of the instrument, this tilt can also be maintained during the insertion of the vertebral replacement body.

A particularly secure and simple fixation is possible if, according to a preferred embodiment of the invention, a conical screw connection is provided for fixing the angular position.

Particularly good guidance and handling of the vertebral replacement body during insertion is possible if two holding elements are provided.

In principle, the locking element could perform any movement relative to the holding element. Preferably, the at least one locking element can be moved linearly. This significantly simplifies the design and manufacturing effort for the instrument, because linear movements of the locking element can be implemented particularly easily.

The number of required locking elements can be minimized if the at least one locking element can be moved in a direction that is linearly independent of the direction of insertion of the vertebral replacement body relative to the at least one holding element. With such a design, one locking element in conjunction with

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with the holding element in order to restrict all degrees of freedom of movement of the vertebral replacement body relative to the holding element.

Preferably, the at least one locking element is movable transversely to a plane defined by the at least one holding element. This enables the locking element to be brought into engagement with the vertebral replacement body transversely to the plane and thus restricts all degrees of freedom of movement of the same.

In principle, it would be conceivable to move the locking element directly. Preferably, however, a drive device is provided for moving the at least one locking element. The drive device makes it possible to move the locking element in a simple manner, in particular even if it is arranged on the holding element in a way that is difficult to access, for example.

It is particularly advantageous if the drive device comprises a drive element for the at least one locking element for converting a rotary movement of an actuating element of the drive device into a linear movement of the at least one locking element. This makes it easy to move the locking element, for example when it is arranged at the end of an endoscopic instrument, for example by rotating a rotatable actuating element outside of a human body, whereby the locking element simultaneously performs a linear movement.

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A particularly simple construction is obtained when the drive device comprises an eccentric drive. For example, an eccentric pin can be arranged on the locking element or on the actuating element or on another part of the drive device.

However, it is particularly advantageous if the eccentric drive comprises an eccentric pin arranged on the actuating element and engaging in an eccentric receptacle of the at least one locking element. In this way, a rotation of the eccentric pin rotating with the actuating element can be converted directly into a linear movement of the locking element.

In a further preferred embodiment of the invention, the drive device can comprise a gear transmission. With gear transmissions, which are easy to manufacture, linear movements can be converted into rotary movements and vice versa, for example, with any arrangement of the locking element relative to the holding element. Angular transmissions are also conceivable, so that rotary movements can in turn be converted into rotary movements.

Preferably, the at least one locking element is toothed. This has the advantage, particularly in the case of a drive device designed as a gear transmission, that the locking element can be directly

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can be driven, for example by a gear or a rack or other toothed drive elements.

The locking element can basically be toothed transversely to its longitudinal axis or longitudinally. However, it is advantageous if the at least one locking element is provided with teeth at an angle to its longitudinal axis. This makes it easy to implement movements transversely to the longitudinal axis of the locking element. This can be necessary, for example, if the locking element is to be movable in a direction that forms at least one linearly independent component in relation to a guide of the holding element for receiving the vertebral replacement body.

The instrument is particularly easy to manufacture if the at least one locking element comprises a substantially cylindrical pin. A corresponding receptacle, which is provided, for example, on the vertebral replacement body for engagement with the locking element, is then also particularly easy to manufacture. In particular, a simple bore is sufficient.

In principle, a connection between the locking element and the vertebral replacement body could be designed in various ways. It is extremely advantageous if the at least one locking element protrudes from the at least one holding element when it is in engagement with the vertebral replacement body. The locking element can therefore be moved in such a way that it protrudes from the holding element when engaging in or with the vertebral replacement body, which in turn

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may also mean that it can be completely or at least partially retracted into the holding element when the locking element is disengaged from the vertebral replacement body.

In order to secure the at least one locking element in its respective position, it can be advantageous if at least one securing element is provided. The securing element can act directly on the locking element, but also indirectly, for example by securing a position of an actuating element and/or a specially provided drive direction.

It is particularly advantageous if the at least one securing element comprises a spring-loaded ball pressure piece. This means that the position of the locking element is immediately noticeable to the user of the instrument. To release the respective position, the locking element must be moved over a pressure point of the ball pressure piece. In addition, with the appropriate design, several positions of the instrument can be secured, for example when the locking element is engaged with the vertebral replacement body or is completely disengaged.

According to a further preferred embodiment of the invention, a fluid channel can be provided for filling a vertebral replacement body having a cavity with a fluid. Such a fluid channel associated with the instrument facilitates the insertion of flexible vertebral replacement bodies in particular, since these must

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After insertion between adjacent vertebral bodies, it is filled with a filling material and thus stabilized.

The fluid channel can be arranged on the instrument in various ways. It is particularly advantageous if the fluid channel can be detachably connected to the at least one holding element. In this way, the fluid channel is fixed directly adjacent to the vertebral replacement body held on the holding element, which enables a particularly stable connection between the fluid channel and the vertebral replacement body during filling.

In order to prevent the fluid channel from becoming detached from the vertebral replacement body, a fluid channel locking device for fixing the fluid channel to the at least one holding element can advantageously be provided on the at least one holding element.

The fluid channel locking device can enable the fluid channel to be fixed in various ways. According to a preferred embodiment of the invention, however, it is advantageous if the fluid channel locking device comprises a fluid channel holding member that is movable relative to the at least one holding element for clamping the fluid channel to the at least one holding element. In particular with an elastic fluid channel, for example a plastic hose, it is important to apply metered holding forces. This is particularly possible with a movable fluid channel holding member that clamps the fluid channel to the holding element.

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In principle, the instrument can be designed in any way. For example, it can be designed in the shape of a pair of pliers, so that when two holding elements are provided, they move away from each other like scissors when the instrument is spread open. According to a preferred embodiment of the invention, the instrument comprises a parallel spreader and the at least one holding element is arranged at a free end of the parallel spreader. This allows adjacent vertebral bodies to be moved away from each other in parallel using the instrument, especially when a vertebral replacement body is held on the instrument using the holding elements.

The following description of preferred embodiments of the invention serves to explain in more detail in conjunction with the drawing. They show:

Figure 1: A side view of an insertion instrument during insertion of a vertebral replacement body;

Figure 2: a perspective view of a holding element of the instrument;

Figure 3: a view in the direction of arrow A in Figure 2;

Figure 4: a partially sectioned view in the direction of arrow B in Figure 2;

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Figure 5: a view taken in the direction of arrow C in Figure 3; Figure 6: a view taken in the direction of arrow D in Figure 3; Figure 7: a sectional view taken along line 7-7 in Figure 3;

Figure 8: a sectional view similar to Figure 7 with a disengaged locking pin;

Figure 9: a sectional view taken along line 9-9 in Figure 4;

Figure 10: a view similar to Figure 9 with a hose clamp pin disengaged from the fluid channel;

Figure 11: a sectional view taken along line 11-11 in Figure 3;

Figure 12: a partial, partially broken away view similar to Figure 6 of a modified embodiment of an instrument;

Figure 13: a sectional view taken along line 13-13 in Figure 12; Figure 14: a sectional view taken along line 14-14 in Figure 12;

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Figure 15: a partial, partially broken away view similar to Figure 6 of a third embodiment of an instrument;

Figure 16: a sectional view taken along line 16-16 in Figure 15.

Figure 1 shows an insertion instrument, designated overall by the reference numeral 20, for inserting, for example, a flexible vertebral replacement body implant 22 between two adjacent vertebral bodies 24 and 25, which comprises a parallel forceps 26 with free ends that can be moved apart in parallel, on each of which a holding element 28 or 29 is arranged in a parallel protruding manner.

The implant 22 comprises a rotationally symmetrical, accordion-like foldable sleeve 30, to the free ends of which a disc-shaped end plate 34 or 35 made of titanium is attached, which is provided with three mandrels 32 projecting in the direction of one of the adjacent vertebral bodies 24 or 25, each of which carries a ring flange 36 or 37 projecting in the direction of the sleeve 30, the outer diameter of which is smaller than that of the end plates 34 and 35.

The parallel pliers 26 comprise two parallel arms 38 and 39, which can be connected by means of a scissor mechanism 40 and can thus be moved parallel to one another or away from one another. Each arm 38 has two free ends, one of which is connected to a holding element 28 or 29 and the other to one of two adjacent

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is connected to pivotably mounted branches 42 and 43, respectively, whereby the arms 38 and 39 can be moved by pivoting the branches 42 and 43 relative to one another. By means of a locking device 44 in the form of a locking screw, the branches 42 and 43, which are spread apart by means of two leaf springs 46 and 47, can be fixed in their maximally spread apart position, whereby the two holding elements 28 and 29 are simultaneously fixed at a predetermined distance from one another.

The two holding elements 28 and 29 are essentially identical. The holding element 29, which can be clamped to the arm 39 via a conical screw connection 49, is described in more detail below as an example. A sleeve 52 provided with an external hexagon 50 and an external thread 51 and rotatably mounted on the holding element 29 is screwed to the free end of the arm 38 provided with an internal thread 53, whereby a clamping is achieved by means of a frustoconical clamping element 54 drilled through in the longitudinal direction in conjunction with a clamping surface 55 which widens conically in the direction of the holding element 29 and which essentially adjoins the internal thread 53 pointing away from the holding element 29.

The holding element 29 itself is designed essentially mirror-symmetrically. It comprises a gripping jaw 57 provided with a U-shaped implant receptacle 59 for receiving the implant 22, in which the implant receptacle 59 is provided with a holding projection extending approximately over a third of the thickness of the gripping jaw 57.

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jump 61 which extends into the implant receptacle 59. It serves for positive engagement in a corresponding recess 133 of the ring flange 37.

A spacer element 63, which is essentially cuboidal in its outer contour, extends in the direction of the conical screw connection 49 from the gripping jaw 57, which is, however, only approximately two thirds the width of the holding jaw 57. An approximately trapezoidal bearing block 65 is arranged transversely on this, which is arranged approximately transversely to the longitudinal axis of the arm 39. The spacer element 63 is provided on both sides with an elongated recess 66 or 67, which reduces the width of the spacer element to approximately two thirds the width of the gripping jaw 57.

Parallel to the longitudinal axis of the arm, a bearing shaft 69 is rotatably mounted on the bearing block 65, passing through the recess 67, said bearing shaft having a head 71 of larger diameter which rests on the side of the bearing block 65 facing the arm 39. The other end of the bearing shaft 69 is provided with an eccentric pin 73 which projects in the direction of its longitudinal axis and has approximately half the diameter of the bearing shaft 69. The eccentric pin engages in a transverse groove 76 of a locking pin mounted in a through hole 75 of the gripping jaw 57 which runs in the direction of expansion of the instrument 20, so that the locking pin is moved linearly back and forth in the through hole 75 when the bearing shaft 69 rotates. Its two extreme positions are shown in Figures 7 and 8.

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In Figure 7, the locking pin 79 projects beyond the holding jaw 57 and into a locking element receptacle 80 designed as a bore, which is provided on the end plate 35 of the implant 22. In Figure 8, the locking pin 79 is in its second extreme position completely sunk within the holding jaw 57 and disengaged from the end plate 35.

In order to fix the bearing shaft 69, the head 71 of the bearing shaft 69 is provided with two hemispherical securing recesses 82 and 83, which are arranged approximately radially opposite one another on the head 71. A headless screw 89 is screwed into a bore 87 of the bearing block 65, which runs transversely to the longitudinal axis of the bearing shaft 69 and has an internal thread 85 on one side. This screw can be used to set the preload of a spring 91 pressing against a ball 93. Figure 11 shows the ball 93 partially immersed in the securing recess 83. In this way, the position of the bearing shaft and thus the position of the locking pin 79 is secured by means of the ball 93 preloaded with the spring 91, which together form a ball pressure piece, for both extreme positions of the locking pin 79 explained in connection with Figures 7 and 8.

In extension of the arm 39, the entire gripping jaw 57 is provided with a longitudinal opening 94, which also passes through the retaining projection 61. A hose 96 is passed through this, which is connected to a corresponding opening on the ring flange 37 of the end plate 35.

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of the implant 22. The other end of the tube 96 is led out of the arm 39 at the side and can be connected to a cement syringe 98. In this way, the flexible shell 30 of the implant 22 can be filled with bone cement via the tube 96 and the implant can be modeled into a desired shape.

In order to prevent the hose 96 from coming loose from the implant 22, a further bearing shaft 68 is arranged in the second recess 66 of the spacer element 63 in a similar manner to the bearing shaft 69 and is also secured in its extreme positions by a headless screw 88, a spring 90, a ball 92 and two radially opposite securing recesses 100 and 101 of a head 70 of the bearing shaft 68. A transverse bore 102 is arranged on the gripping jaw 57 adjacent to the spacer element 63 transversely to the locking element receptacle 81 and the longitudinal opening 94 such that a hose clamping pin 104 slidably mounted within the transverse bore 102 with a cylindrical clamping surface 106 adapted to the outer diameter of the hose 96 can clamp the hose 96 approximately on a quarter of its circumference. The hose clamp pin 104 has a groove 108 running parallel to the locking element holder 81 and opening in the direction of the bearing shaft 68, into which an eccentric pin 110 protruding from the bearing shaft in its longitudinal direction is inserted. The latter has a diameter approximately half the size of the bearing shaft 68 and is arranged laterally offset from the axis of symmetry of the bearing shaft 68.

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A rotation of the bearing shaft leads to a linear movement of the hose clamp pin 104 in the transverse bore 102 due to the arrangement of the eccentric pin 110, so that in a first extreme position the clamping surface 106 rests against the hose 96, as shown in Figure 9, and clamps the hose 96 in the longitudinal opening 94. To release the hose, the bearing shaft 68 is rotated approximately 180°, so that in a second extreme position, as shown in Figure 10, the eccentric pin 110 is at the maximum distance from the hose 96. The latter can be attached and removed again, for example, before filling the implant 22 or after the filling and hardening of the bone cement filled into the shell 30 has been completed.

The holding element 29 is essentially identical to the holding element 28, whereby the holding element 28 has only a single bearing shaft 112, since no device for clamping a tube is required on this. However, a locking pin 78 is provided in an analogous manner for engaging with the end plate 34 of the implant 22. An angular position of the bearing shaft 112 is possible by means of a ball pressure piece 114 as described in connection with Figure 11.

The use of the instrument 20 when inserting the implant 22 is explained in detail below.

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First, the implant 22 with its two end plates 34 and

35 into the gripping jaws 56 and 57. Through the ring flanges

36 and 37, the implant can only move in the direction of the U-shaped implant receptacles 58 and 59. However, the implant 22 can rotate in the gripping jaws 56 and 57. Only one degree of freedom of movement of the implant 22 is limited by this. For the final and defined fixation of the implant 22 to the instrument 20, the two bearing shafts 69 and 112 are rotated by means of a tool (not shown) that can be rotated into corresponding tool receptacles of the heads 71 and 113, designed as hexagon sockets 117 and 118 respectively. By rotating the bearing shafts, the two locking pins 78 and 79 are each moved in the direction of the end plates 34 and 35 and, provided the end plates 34 and 35 are correctly positioned and inserted into the gripping jaws 56 and 57, they engage in the locking element receptacles 80 and 81. In this position shown in Figure 3, all degrees of freedom of movement of the implant 22 relative to the instrument 20 are restricted. Movement in the direction of the longitudinal axis of the implant is prevented by the design of the end plates 34 and 35 with the ring flanges 36 and 37 arranged thereon; rotation and removal of the implant 22 from the gripping jaws 56 and 57 is made impossible by the locking pins 78 and 79 engaging with the end plates.

With the parallel pliers 26, the two end plates 34 and 35 can be brought to the desired distance from each other and by means of the conical

·· III*!

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Use screw connections 48 and 49 to determine and fix the desired inclinations of the holding jaws 56 and 57 relative to each other.

The implant 22 fixed to the instrument 20 can now be inserted between two adjacent vertebral bodies 24 and 25 and by spreading the parallel forceps 26 the mandrels 32 and 33 penetrate into the vertebral bodies 24 and 25 respectively and thus form an anchorage of the implant 22 in the bone.

The flexible sleeve 30, which was previously connected to the filling opening 97 of the implant 22 and the cement syringe 98 via the hose 96, is filled with bone cement using the cement syringe 98 after the implant 22 has been finally positioned. Once the bone cement has hardened, the instrument 20 is removed from the implant 22 by rotating the bearing shafts 69 and 112 back to their original position, in which the locking pins 78 and 79 disappear completely within the holding jaws 56 and 57, as shown in Figure 8. The instrument 20 can now be pulled off the implant 22 and remains between the adjacent vertebral bodies 24 and 25.

Two alternative embodiments are explained in connection with Figures 12 to 14 and 14 to 16.

The essentially identical instruments differ only in their design with regard to the movement of the locking pins 78 and 79. Therefore, identical reference numerals are used with

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the additional letters A or B are used. The design shown in connection with Figures 12 and 13 comprises a bearing shaft 69 A, which does not have an eccentric pin at one end, but rather a gear 120 A, which meshes with a locking pin 79 A having a rack-like toothing 122 A. In this case, a rotation of the bearing shaft 69 A is converted into a linear movement of the locking pin 79 A by a rack drive.

To limit the movement of the locking pin 79 A, the bearing shaft 69 A is provided with a transverse bore 124 A with an internal thread into which a screw 126 A is screwed, the head 127 A of which, in conjunction with the recess 67 A, forms a limit stop for a rotary movement of the bearing shaft 69 A. This prevents the locking pin 79 A from falling out of the through-bore 75 A. In addition, the movement path of the locking pin 79 A is limited.

In a further alternative embodiment shown in Figures 15 and 16, a locking pin 79 B is arranged within an oblique bore 130 B so as to be movable in its longitudinal direction, which is arranged in a plane that runs parallel to the two bearing shafts 68 B and 69 B and intersects the longitudinal axis of the bearing shafts 68 B and 69 B at an angle of approximately 45°. The bearing shaft 69 B is in turn provided with a gear 120 B, which extends further in the direction of the bearing shaft 69 B than the gear 120 A, which is provided with a toothing 122 B of a locking

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locking pin 79 B. The toothing 122 B is also attached to the locking pin 79 B at an angle of approximately 45° with respect to the longitudinal axis of the bearing shaft 69 B. Such a transverse toothing enables a movement in the longitudinal direction of the inclined bore 130 B due to a rotation of the bearing shaft 69 B. To limit a movement of the locking pin 79 B, as explained in connection with Figure 14, a screw 126 B is screwed into a transverse bore 124 B provided with an internal thread through the bearing shaft 69 B.

With the locking pin 79 B, all degrees of freedom of movement of the implant 22 relative to the instrument 20 can be limited, because the transverse bore 124 B runs in a direction that is linearly independent of the direction through the implant receptacle 59.

Claims (29)

1. Surgical instrument for inserting a vertebral replacement body, with at least one holding element for holding the vertebral replacement body in an application position, with at least one locking element assigned to the at least one holding element, wherein the at least one holding element in the application position limits the vertebral replacement body in at least one degree of freedom of its movement relative to the at least one holding element and wherein the at least one locking element can be brought into engagement with the vertebral replacement body in the application position such that all further degrees of freedom of movement of the vertebral replacement body relative to the at least one holding element that are not limited by the at least one holding element are limited by the at least one locking element, characterized in that the at least one locking element ( 78 , 79 ; 79 A; 79 B) is movable relative to the at least one holding element ( 28 , 29 ). 2. Instrument according to claim 1, characterized in that the at least one holding element ( 28 , 29 ) comprises a receptacle ( 58 , 59 ) with a guide ( 60 , 61 ) for introducing the vertebral replacement body ( 22 ) in a predetermined plane. 3. Instrument according to claim 2, characterized in that the guide comprises a linear guide ( 60 , 61 ) for inserting the vertebral replacement body ( 22 ) in a predetermined insertion direction. 4. Instrument according to one of claims 2 or 3, characterized in that the receptacle ( 58 , 59 ) is substantially U-shaped. 5. Instrument according to one of claims 2 to 4, characterized in that the receptacle ( 58 , 59 ) has a stop ( 60 , 61 ) and that the stop ( 60 , 61 ) is arranged parallel to the predetermined plane for limiting a movement of the vertebral replacement body ( 22 ) transverse to the plane. 6. Instrument according to claim 5, characterized in that the stop comprises a partially semi-annular projection ( 60 , 61 ). 7. Instrument according to one of the preceding claims, characterized in that the at least one holding element ( 28 , 29 ) is arranged to be rotatable. 8. Instrument according to one of the preceding claims, characterized in that an angular position of the at least one holding element ( 28 , 29 ) can be fixed. 9. Instrument according to claim 8, characterized in that a conical screw connection ( 48 , 49 ) is provided for fixing the angular position. 10. Instrument according to one of the preceding claims, characterized in that two holding elements ( 28 , 29 ) are provided. 11. Instrument according to one of the preceding claims, characterized in that the at least one locking element ( 78 , 79 ; 79 A; 79 B) is linearly movable. 12. Instrument according to one of the preceding claims, characterized in that the at least one locking element ( 78 , 79 ; 79 A; 79 B) is movable in a direction linearly independent of the insertion direction of the vertebral replacement body ( 22 ) relative to the at least one holding element ( 28 , 29 ). 13. Instrument according to one of the preceding claims, characterized in that the at least one locking element ( 78 , 79 ; 79 A; 79 B) is movable transversely to a plane defined by the at least one holding element ( 28 , 29 ). 14. Instrument according to one of the preceding claims, characterized in that a drive device (68, 72; 69, 73; 69A, 120A, 122A; 69B, 120B, 122B) is provided for moving the at least one locking element ( 78 , 79 ; 79A ; 79B ). 15. Instrument according to claim 14, characterized in that the drive device ( 68 , 72 ; 69 , 73 ; 69A , 120A , 122A ; 69B , 120B , 122B ) comprises a drive element ( 72 , 73 ; 120A ; 120B ) for the at least one locking element ( 78 , 79 ; 79A ; 79B ) for converting a rotary movement of an actuating element ( 68 ; 69 ; 69A ; 69B ) of the drive device ( 68 , 72 ; 69 , 73 ; 69A , 120A , 122A ; 69B , 120B , 122B ) into a linear movement of the at least one locking element ( 78 , 79 ; 79A ; 79B ). 16. Instrument according to one of claims 14 or 15, characterized in that the drive device comprises an eccentric drive ( 68 , 72 ; 69 , 73 ). 17. Instrument according to claim 16, characterized in that the eccentric drive ( 68 , 72 ; 69 , 73 ) comprises an eccentric pin ( 72 ; 73 ) arranged on the actuating element ( 68 , 69 ) and engaging in an eccentric receptacle ( 76 ; 77 ) of the at least one locking element ( 78 ; 79 ). 18. Instrument according to one of the preceding claims, characterized in that the drive device comprises a gear transmission ( 120 A, 122 A; 120 B, 122 B). 19. Instrument according to one of the preceding claims, characterized in that the at least one locking element ( 79 A; 79 B) is toothed. 20. Instrument according to one of the preceding claims, characterized in that the at least one locking element ( 79 B) is provided with teeth ( 122 B) obliquely to its longitudinal axis. 21. Instrument according to one of the preceding claims, characterized in that the at least one locking element comprises a substantially cylindrical pin ( 78 , 79 ; 79A ; 79B ). 22. Instrument according to one of the preceding claims, characterized in that the at least one locking element ( 78 , 79 ; 79 A; 79 B) protrudes from the at least one holding element ( 28 , 29 ) when it is in engagement with the vertebral replacement body ( 22 ). 23. Instrument according to one of the preceding claims, characterized in that at least one securing element ( 92 , 93 ; 114 ) is provided for securing the at least one locking element ( 78 , 79 ) in its respective position. 24. Instrument according to claim 23, characterized in that the at least one securing element comprises a spring-loaded ball pressure piece ( 92 , 93 ; 114 ). 25. Instrument according to one of the preceding claims, characterized in that a fluid channel ( 96 ) is provided for filling a vertebral replacement body ( 22 ) having a cavity with a fluid. 26. Instrument according to claim 25, characterized in that the fluid channel ( 96 ) is detachably connectable to the at least one holding element ( 29 ). 27. Instrument according to one of claims 25 or 26, characterized in that a fluid channel locking device ( 104 ) for fixing the fluid channel ( 96 ) to the at least one holding element ( 29 ) is provided on the at least one holding element ( 29 ). 28. Instrument according to claim 27, characterized in that the fluid channel locking device comprises a fluid channel holding member ( 104 ) movable relative to the at least one holding element for clampingly connecting the fluid channel ( 96 ) to the at least one holding element ( 29 ). 29. Instrument according to one of the preceding claims, characterized in that the instrument ( 20 ) comprises a parallel spreader ( 26 ) and that the at least one holding element ( 28 , 29 ) is arranged at a free end of the parallel spreader ( 26 ).