PLACEHOLDER FOR SPINE SURGERY

Description

[0001] The invention relates to a spacer for spinal surgery, comprising an upper support with an upper bearing surface and a lower support with a lower bearing surface, the relative position of which is changeable, wherein both the upper and the lower bearing surfaces each have a first and a second sub-surface which touch at an edge in a closed state of the spacer, and an expansion device with which the bearing surfaces can be changed in their lateral extension by laterally drifting apart the first and second sub-surfaces between a minimum lateral extension and a maximum lateral extension, as well as in their vertical distance between a minimum height and a maximum height of the spacer, so that the spacer can be adjusted between a closed and an expanded state.

[0002] Degeneration of spinal segments in the human spine is the cause of spinal problems, often accompanied by severe pain. It is a very common condition affecting a large number of patients, frequently of advanced age, and leading to permanent impairments. It manifests in a variety of ways. Among the most frequent forms is intervertebral disc degeneration, the "wear and tear" of the cartilaginous tissue of the disc, resulting in misalignment. Another common form is osteoporosis, the breakdown of the internal structure (cancellous bone) of the bone, particularly in the vertebrae, making them brittle and consequently leading to endplate fractures and vertebral body collapse.

[0003] Treatment includes surgical procedures – by removing at least parts of a degenerated spinal segment and / or by implanting space-holding implants in place of a removed intervertebral disc or segment, or for internal support by implantation into or in place of a vertebral body.

[0004] To avoid large wounds and thus greater pain and blood loss, microscopic or endoscopic procedures are used in surgery, including spinal surgery, wherever possible to access the affected area through a small incision. Direct, minimally invasive surgical access to the human spine from the dorsal side (i.e., from the patient's back) is simple, quick, and safe. To minimize damage to the innervation of the intrinsic back muscles during the surgical approach, a unilateral approach is preferred.

[0005] Implants should be compact and adapted to the access route during their insertion into their site of action in a patient's spine, but should be "unfoldable" or expandable to the required size at the site of action itself.

[0006] Such space-retaining implants – or spacers – for spinal surgery can replace an intervertebral disc or a disc segment. When the spacer is used as a disc replacement, it serves as an intervertebral implant for the interbody fusion of vertebrae. This intervertebral implant, which represents the most common application of the spacer described here and is also called a "cage," must act as a spacer at its point of application while simultaneously providing support – in this case, between two adjacent vertebral bodies.

[0007] In principle, the use of the spacers described here is also possible for the complete or partial replacement of a vertebral body. In the case of complete replacement, the spacer acts as a spacer, while in the case of partial replacement, it serves to augment (i.e., restore), support, or stabilize the vertebral body within the vertebral body itself (spondyloplasty). Even a spacer used for complete or partial replacement of a vertebral body must act as a spacer at its site of application while simultaneously providing support—in this case, either in place of the vertebral body or within the vertebral body itself.

[0008] There are intervertebral disc implants, i.e., placeholders for spinal surgery used as disc replacements, whose height can be adjusted: Such intervertebral disc implants are known, for example, from DE 44 16 605 C1, US 5,554,191 A, or FR 2 719 763 A1. These intervertebral disc implants have in common that, after implantation, two arms of the implant are spread apart by spacers. These spacers are inserted longitudinally between the arms and slide along inclined planes, which are designed as flat surfaces. Depending on the depth of insertion of the spacer, the arms are spread apart to varying degrees.This results, on the one hand, in a change in the angle of the support surfaces of the two arms, which were formerly parallel to each other (i.e., in the closed state), for the adjacent vertebral bodies, and simultaneously leads to an asymmetrical change in the height of the intervertebral implant. For the adjustment of the spacer elements, centrally located screw spindles are generally used in known intervertebral implants of this type, with respect to the symmetry of the implant.

[0009] In contrast, US 2014 / 0039622 A1 and EP 2 777 630 A1 describe spacers for spinal surgery that can be expanded laterally and vertically in a simultaneous movement. This simultaneous expansion in both lateral and vertical directions is achieved by spreading the upper and lower supports using two opposing, preferably pyramidal wedges that run on a centrally mounted screw spindle. US 2005 / 0124989 A1 also describes an expandable spacer that can be expanded laterally and vertically simultaneously.

[0010] US Patent 2017 / 209282 A1 concerns a neurosurgical and orthopedic fixation system, a placeholder for spinal surgery, with upper and lower supports with corresponding contact surfaces and an expansion device that adjusts the contact surfaces in their lateral extension and in their vertical distance between a minimum and a maximum height. The system is designed such that the lateral expansion must be completed first before the horizontal expansion can begin.

[0011] US 2018 / 098860 A1 describes an "intervertebral scaffold system," a placeholder for spinal surgery that requires an external expansion device. It contains support struts and connecting elements between the struts, which are folded in the closed state and unfolded using the external expansion device, which inserts a spacer into the placeholder for this purpose.

[0012] Currently used spacers for spinal surgery are expandable either laterally or vertically (i.e., in only one direction). Other spacers with a single drive unit are expandable both laterally and vertically, but only simultaneously and proportionally. A third group of spacers described so far can be expanded sequentially using separate expansion mechanisms, either with two drives or with two strictly sequential expansion movements, where the completion of the first movement is a prerequisite for the start of the second. However, these are technically very complex to manufacture or are designed in such a way that they do not provide a contact surface.

[0013] Spacers that can only be expanded in one direction, for example, only vertically, are either too large for a truly minimally invasive procedure if—when used as an intervertebral implant—they inherently possess the lateral expansion necessary to support the vertebral endplate of the upper vertebral body and the vertebral endplate of the lower vertebral body to prevent collapse. Conversely, if spacers that can only be expanded in one direction, for example, only vertically, are as compact as required for their insertion into place using minimally invasive surgery, they only support partial surfaces of the vertebral endplate and the vertebral endplate during their vertical expansion and can therefore easily collapse. This risk also exists, in principle, when used as a total or partial vertebral body replacement—in this case, from the other side of the vertebral endplate.originating from the vertebral endplate - although by no means as pronounced.

[0014] Even state-of-the-art intervertebral spacers that are expandable in both directions simultaneously do not eliminate this risk. This is because, from the outset, they must also expand vertically during their lateral expansion, thus exerting a significant supporting effect even before they have reached their full necessary lateral extent to do so without the risk of collapsing into the vertebral endplate and / or the vertebral endplate. Furthermore, in currently common spacers that expand laterally and vertically simultaneously, the upper and lower supports are spread apart into two sections, creating an unsupported area in the middle. These spread sections then collapse at the edges of the vertebral endplate or endplate, as they now only provide very localized support in these areas.

[0015] A placeholder as described in the publication DE 10 2017 211 185 A1, which can be expanded laterally and vertically one after the other via a screw spindle but by means of separate expansion mechanisms, can be used as a partial or complete vertebral body replacement as described in the publication, but as an intervertebral implant in place of the intervertebral disc or disc segment does not offer the necessary support.

[0016] All placeholders described in the prior art are designed with a straight implantation or access route in mind and are "bulky" for non-straight implantation or access routes. However, if the placeholder is used as an intervertebral implant, it should ideally be insertable from the dorsal-median or para-median side and lie symmetrically and neutrally to the dural sac (from approximately the second lumbar vertebra distally) or the spinal cord (up to approximately the second lumbar vertebra), i.e., ventral to the vertebral canal, without passing through the vertebral canal, in order to avoid damaging the neurological structures contained within it.

[0017] The present invention therefore aims to provide and further develop a placeholder for spinal surgery of the type mentioned above, which overcomes the aforementioned problems. In particular, a placeholder for spinal surgery is to be described that is compact and minimally invasive and can be used in corresponding stabilization procedures, such as minimally invasive vector lumbar interbody fusion (MIS-VLIF), and which is preferably also easily implantable via a non-straight implantation path, which can develop the necessary lateral contact surface at the site of action to fulfill its support function, and with which a desired vertical distance, such as the vertical distance between two vertebral bodies, can be set safely and without risk of collapse.The placeholder should also take into account the biokinematic requirements of its use and support a natural function of the spine in the best possible way by considering the functional anatomy of the movement segment to be stabilized.

[0018] Furthermore, appropriate procedures for implanting the spacer in a patient's spine should be specified.

[0019] The problem is solved according to the invention by the teaching of claim 1. Further advantageous embodiments and developments of the invention are set forth in the dependent claims.

[0020] A placeholder for spinal surgery comprises an upper support with an upper contact surface and a lower support with a lower contact surface, the relative position of which is adjustable. Both the upper and lower contact surfaces each have a first and a second sub-surface, which touch at an edge when the placeholder is closed.

[0021] "Each a first and a second sub-surface" should be read as "each at least one first and one second sub-surface." In principle, a further subdivision of the support surfaces is also possible: In a specific embodiment, both the first and the second sub-surface could be further subdivided into two sub-surfaces each, resulting in four sub-surfaces of the upper or lower support surface, respectively. However, dividing the upper or lower support surface into more than two sub-surfaces each leads to a potentially more complex internal structure of the placeholder.

[0022] The closed state of the spacer is that in which both its lateral and vertical dimensions are at their minimum. In this state—that is, as small and compact as possible—which is the insertion state of the spacer, the spacer is inserted into its position in the spinal region through a minimal opening in the patient's back.

[0023] In this closed state, the upper and lower supports are at a minimal distance from each other. The same applies to the first and second surfaces of the upper and lower supports, respectively, which typically touch along an edge in the closed state, as this minimizes the lateral extent of the placeholder. However, it is not necessary for the two edges to actually be in physical contact: the term "touch" should therefore also encompass the two edges lying side by side with a very small distance, typically less than 1 mm, and at most less than 2 mm. The edge where the two surfaces touch (or along which they lie side by side with a very small distance) does not have to be straight, but can take any shape.

[0024] The spacer for spinal surgery also includes an expansion device that allows the lateral extent of the contact surfaces to be adjusted by laterally drifting the first and second sub-surfaces of the upper and lower contact surfaces apart, up to a maximum drift amount between a minimum and a maximum lateral extent. The vertical distance between the upper and lower contact surfaces can also be adjusted between a minimum and a maximum height of the spacer (since the upper and lower contact surfaces simultaneously represent the upper and lower boundaries of the spacer), thus allowing the spacer to be set between a closed and an expanded state. After implantation into the patient's spine, the vertical direction runs approximately parallel to the spine or parallel to a direction running from caudal to cranial.The lateral movement of the sub-surfaces, however, occurs perpendicular to this, i.e., horizontally.

[0025] To achieve expansion in the simplest way possible after the spacer has been moved to its point of action in the patient's spine, the expansion device contains a single drive; that is, the execution of the expansion, and thus both the change in the lateral extension of the contact surfaces and the change in the vertical distance of the contact surfaces, is achieved via one and the same drive: For this purpose, the surgeon, for example, always operates the same actuating element in a linear fashion, which in turn operates an expansion mechanism that does not have to be linear or not continuously linear.

[0026] A significantly more complicated design, but still conceivable, is an expansion device with separate drives for changing the lateral expansion and the vertical distance.

[0027] The expansion device thus changes both the relative position of the upper and lower contact surfaces, as well as the lateral extension of both surfaces. The term "expanded state," without any further specification, denotes the maximally expanded state. It may be desirable or advantageous to set a partially expanded state: for example, if, after implantation of the spacer, it is not initially intended to have the full vertical distance and / or the contact surface the full lateral extension, a partially expanded state can be set in a specific embodiment. Advantageously, each of these partially expanded states can be locked in place; however, a "retraction" or "re-folding" can also be achieved by a high degree of self-locking in the expansion device, such as a threaded connection.

[0028] The adjustment of the state between a closed and an expanded state is generally continuous, particularly if partially expanded states are not to be maintained for extended periods. Such continuous adjustability, or continuous change in lateral extent and vertical distance, is advantageous but not essential.

[0029] Furthermore, the placeholder according to the invention is preferably also expanded

[0030] The condition can be reset to a closed state - also called insertion state - thus allowing for easy replacement in case of dissatisfaction of the surgeon or the patient with the result.

[0031] According to the invention, the placeholder is characterized in that the expansion device is configured to perform the change in lateral extension and vertical distance in two independently and freely definable movement patterns encoded in the placeholder by means of a single drive.

[0032] In the placeholder according to the invention, the progression of changes in lateral expansion and the progression of changes in vertical distance during expansion are thus freely definable and encoded within one and the same conceptual structure. This means that for each lateral expansion of the upper and lower support surfaces between the minimum and maximum lateral expansion, a desired vertical distance between the upper and lower support surfaces can be set within a range between a minimum height and a maximum height of the placeholder.

[0033] This means that neither the ratio between the change in lateral extension and the change in vertical distance needs to be kept constant, nor do the movements need to be carried out sequentially or by separate expansion mechanisms or devices.

[0034] Preferably, the placeholder according to the invention comprises a physical representation of a flow chart of the change in lateral expansion to change the vertical distance during its expansion. This can be expressed, for example, in the form of freeform surfaces in the interior or on the inner surfaces or edges of the upper and lower supports, or, for example, on spacer elements used for this purpose which are used as sliding surfaces, in the (freely determinable) form of elongated holes used as sliding holes, or in rotatable structures with different tooth pitches.

[0035] Advantageously, in a spacer according to the invention, the ratio of the change in lateral extension to the change in vertical distance will change repeatedly, either in sections or continuously, during its expansion. Preferably, the change in lateral extension and the change in vertical distance are at least partially separated in time, such that after its insertion, for example, into an intervertebral disc space of a patient's spine where the disc has previously been removed, the spacer, inserted in its closed state, first undergoes lateral expansion to provide a sufficiently wide contact surface for the subsequent, parallel change in the vertical distance between the two vertebral bodies.

[0036] For example, lateral expansion in relation to linear drive can be described as a disproportionate expansion, and thus as a non-linear enlargement, of the effective contact areas, in which initially large changes in lateral expansion take place, while a vertical expansion starting in the middle and thus a change in the vertical distance then proceeds linearly or vice versa.

[0037] It is also conceivable that the lateral expansion and the vertical expansion are realized disproportionately and independently of each other via a common linear drive.

[0038] The method used to modify the lateral extent of the bearing surfaces to change their vertical distance can therefore be adapted to the intended use, the specific problems of the patient, and also the wishes of the treating surgeon. A series of placeholder models can be created that represent frequently used configurations, all operating on the same principle, but differing, for example, in the shape of the freeform surfaces and / or the shape of the elongated holes used as gliding holes.

[0039] The use of freeform surfaces and / or elongated holes used as sliding holes also offers the possibility of fixing or stabilizing certain states in a simple way by temporarily reducing the vertical distance again through the shaping of the freeform surfaces and / or the elongated holes used as sliding holes, thus achieving a metastable state.

[0040] Furthermore, the placeholder according to the invention is preferably also resettable from an expanded state to a closed state - also called insertion state - so that the lateral extension of the upper and lower support surfaces can be reduced from a maximum extension back to a minimum extension and the vertical distance of the upper and lower support surfaces can be reduced from a maximum height back to a minimum height by operating the drive of the expansion device in the opposite direction.

[0041] In a preferred embodiment, the first and second partial surfaces of the upper and lower support surfaces have an interlocking structure at the edge where they touch in the closed state, designed in such a way that it allows the first and second partial surfaces to drift apart laterally during expansion, and in the expanded state a lateral gap running perpendicular to the direction of lateral drift through the upper and lower support surfaces has a gap width that is smaller than the maximum amount of drift.

[0042] The interlocking structure of the first sub-surface of the upper support surface is aligned with the interlocking structure of the second sub-surface of the upper support surface: The interlocking structure of the first and second sub-surfaces should therefore interlock when closed.

[0043] Preferably, they interlock as precisely as possible – according to a lock-and-key principle. The same applies to the interlocking structure of the first sub-surface of the lower support surface and the interlocking structure of the second sub-surface of the lower support surface. However, the corresponding structures of the sub-surfaces of the upper and lower support surfaces do not have to be identical or similar. Identical or similar structures are advantageous, however, because then the expansion behavior of the upper support surface on the vertebral body endplate of the upper vertebral body and of the lower support surface on the vertebral body endplate of the lower vertebral body is identical or similar when the spacer is used as an intervertebral implant.

[0044] To allow (and not hinder) lateral drifting apart—that is, lateral sliding in opposite directions—of the first and second surfaces, the interlocking structures must be designed in such a way that they cannot become entangled during this lateral drifting. Ideal structural forms for such interlocking structures include, for example, a toothed pattern, a zigzag pattern, or a corrugated pattern, although none of these structures need to be perfectly regular. The shape of an "ideal" interlocking structure ultimately depends on the mapping rule governing the lateral drifting.

[0045] Lateral drifting apart preferably occurs through sliding apart: In a tooth structure, for example, this means that the areas of the interlocking structure of the edges of the first and second sub-surfaces slide apart in the areas of the edges aligned parallel to the lateral drift direction, which further reinforces the grip that the bearing surface continues to provide even when drifting apart.

[0046] The width of a lateral gap that forms during drift is smaller, or ideally significantly smaller, than the maximum amount of drift. The lateral gap is the "imaginary" gap that would form between the first and second sub-surfaces of the upper or lower support surface along the entire length of the support surface, perpendicular to the lateral drift direction, if straight edges were placed along the furthest "protruding" areas of the interlocking structure.

[0047] When the spacer is used as an intervertebral disc implant, it exerts pressure on and supports the vertebral body above and below it, replacing the intervertebral disc. While straight edges of the first and second surfaces create a lateral gap as they drift apart from the outset, the width of which quickly reaches a point where support for the endplate of the upper vertebral body and the endplate of the lower vertebral body in the central region can no longer be guaranteed, the interlocking structures according to the invention offer sufficient support even at their maximum lateral extension. The interlocking structures of such spacers according to the invention thus significantly increase the effective support of the contact surfaces in the expanded state compared to spacers according to the prior art.

[0048] The smaller openings that form instead of a continuous lateral gap allow for bone ingrowth and support it by increasing the surface area along which such ingrowth can occur. This improves the interface between bone and implant, which promotes the healing of the implant or the integration of such a spacer into the spine.

[0049] The main use of the spacer described here relates to its application as an intervertebral spacer, also called a cage or interbody spacer, to be implanted in place of the intervertebral disc or in place of parts of the intervertebral disc: For this purpose, the properties of the contact surfaces of this spacer according to the invention are most important.

[0050] Nevertheless, further uses of the spacer according to the invention are possible as partial or complete vertebral body replacement or also for stiffening a vertebral body with a bone filler in the sense of spondyloplasty: In this case, the adjustable spacer is implanted into the vertebral body after opening the cortical bone structure to stiffen the vertebral body in the case of fractures or osteoporosis and then filled.

[0051] In a preferred embodiment of the placeholder according to the invention, the gap width of the lateral gap is zero even in the expanded state. This is very easily achieved by using a tooth structure, as can be readily seen in the figures. However, many other structural shapes are conceivable that result in the gap width of the lateral gap being zero even in the expanded state: A waveform with an amplitude greater than half the maximum drift amount, for example, also fulfills the condition.

[0052] In a particularly preferred embodiment, both the upper and lower supports of the placeholder are shaped such that, during lateral expansion, the interlocking structure of the first sub-surface slides on a support structure in the part of the support belonging to the second sub-surface, and the interlocking structure of the second sub-surface slides on a support structure in the part of the support belonging to the first sub-surface. This provides the support surfaces of the placeholder with additional stability during their lateral expansion.

[0053] The spacer according to the invention, with a lateral gap extending through both the upper and lower contact surfaces and a gap width that is (significantly) smaller than the maximum drift of the lateral extension of these contact surfaces, and with an expansion device capable of executing changes in lateral extension and vertical distance in two independent and freely definable movement patterns, describes a minimally invasively implantable spacer that can develop the necessary size of the contact surface at the site of action to fulfill its support function and with which a desired vertical distance, such as the vertical distance between two vertebral bodies, can be set safely and without risk of collapse. It takes into account the biokinematic requirements of its application and optimally supports natural spinal function by improving sagittal balance.

[0054] It offers a significantly larger effective support surface than prior art placeholders that are inserted dorsally, in particular a significantly more functionally distributed contact area with an improved footprint and optimal press-fit (i.e., better "anchoring" in the spine due to its shape, the pressure exerted, and its distribution). The placeholder according to the invention takes into account the biologically derivable optimal expansion behavior through a freely definable expansion profile of the change in lateral extent, i.e., its expansion in width, which is preferably initiated first after the placeholder is moved to its site of action, and the change in vertical distance, i.e., its expansion in height, which is preferably initiated somewhat later or subsequently, although this is controlled by the same drive mechanism.The placeholder according to the invention combines several properties that are generally required of a placeholder for implantation in the spine.

[0055] The essence of the invention is therefore also an expansion mechanism that allows lateral and vertical expansion to be configured independently of each other, even though it only has one drive for realizing the expansion. The expansion mechanism of the placeholder allows the two expansion qualities to be technically defined or encoded in the placeholder in their sequence and in any desired relative proportion.

[0056] In a preferred embodiment of the placeholder or the placeholders described above, the expansion device for adjusting the placeholder between the closed and the expanded state includes a screw spindle with a screw head with which the change in lateral expansion as well as the vertical distance can be controlled.

[0057] In this configuration, the screw spindle is the essential element of the expansion device's drive mechanism. Its screw head allows access to the screw spindle with a tool that supports minimally invasive surgery. The screw head can have any shape and design that allows the externally inserted tool to engage it, thereby initiating and controlling the rotation of the screw spindle and thus controlling changes in both lateral and vertical expansion.

[0058] The axis of the screw spindle does not need to run centrally or in the middle of the placeholder. Rather, it can assume any position, preferably perpendicular to the direction of lateral extension. It can be positioned such that the screw head of the screw spindle is more easily accessible after the placeholder is inserted into its operating position than for placeholders according to the prior art, which require a central position for such a drive element. In this embodiment, the screw spindle of the drive moves along a rotating axis that changes its position, i.e., as a technically realized centrode or gyroscopic orbit.

[0059] The expansion of the spacer can be carried out in the simplest way by means of the screw spindle, if it in turn is part of a wedge mechanism or a mechanism based on the principle of wedge and counter-wedge, with which the change of the lateral expansion as well as the vertical distance of the bearing surfaces is operated simultaneously.

[0060] In significantly more advantageous embodiments, however, the rotation of the screw spindle allows the spacer to expand in such a way that the change in lateral extent and vertical distance can be achieved in two ways. The movement patterns are independent of each other and freely definable. In particular, in an advantageous embodiment, it allows at least partial or complete separation of the changes in lateral extension and vertical distance from each other with regard to their interrelated sequence.

[0061] In a specific embodiment of the placeholder, it exhibits no symmetries along any lateral section plane along an axis parallel to the axis of the screw spindle. A parallel alignment also includes a position on the axis of the screw spindle.

[0062] In a particularly preferred embodiment of the placeholder according to the invention, its expansion device further comprises a movable spacer element. Such a spacer element separates two movable parts in such a way that relative movement of the two parts to each other can only occur along predetermined paths or only within predetermined areas. Such a spacer element can be a cam or have a cam-like shape, but can also assume other, more specific geometric forms. However, the movable mounting of the spacer element in each of the two movable parts is essential.

[0063] In this case, this spacer element is mounted at a position on the spacer element, preferably at a first end, so as to be laterally rotatable about a movable axis, which is displaceable along the screw spindle by means of a threaded nut integrated into the movable axis and running on a thread of the screw spindle (which is therefore an external thread), wherein the movable axis is arranged running directly or indirectly in an upper elongated hole in the first partial surface of the upper support and in a lower elongated hole in the first partial surface of the lower support.

[0064] "Directly arranged in a slot" means that the axis runs directly in the slot, "indirectly arranged in a slot" means that an element connected to the axis runs in the slot.

[0065] The spacer element is furthermore rotatably mounted about a fixed axis, which is laterally fixed in the second surface of the upper support and in the second surface of the lower support. This fixed axis is preferably located in its central region. However, it is also possible to arrange the fixed axis at a second end of the spacer element. A non-fixed axis is also an option.

[0066] Finally, the spacer element is mounted at a first and / or a second end, sliding freely on an upper three-dimensional sliding surface below the first and / or the second partial surface of the upper support, and on a lower three-dimensional sliding surface above the first and / or second partial surface of the lower support, wherein the upper three-dimensional sliding surface and the lower three-dimensional sliding surface are shaped relative to each other such that the first and / or second end of the spacer element assumes a defined position on both the upper and the lower three-dimensional sliding surface for every rotation angle of the spacer element about the fixed axis, the absolute position of which and the corresponding position of the movable axis in the correspondingly shaped elongated holes determine the lateral extent of the spacer, and the distance between the upper and the lower three-dimensional sliding surfaces in the closed state determines the height of the spacer.

[0067] A three-dimensional sliding surface is a surface formed in three-dimensional space which - as already explained above - in a preferred embodiment is freely shaped in such a way that it, or that it in combination with another three-dimensional sliding surface and / or the shape of the elongated hole used as a sliding hole, depicts the lateral and vertical movement.

[0068] In a further particularly preferred embodiment of the placeholder according to the invention, its expansion device comprises a movable spacer element that is movable along the screw spindle and has (at least) four guide elements, each of which is displaceable in a first upper elongated hole and / or under a first upper guide sliding surface in the first partial surface, and in a second upper elongated hole and / or under a second upper guide sliding surface of the second partial surface of the upper support, and in a first lower elongated hole and / or on a first lower guide sliding surface of the first partial surface, and in a second lower elongated hole and / or on a second lower guide sliding surface of the second partial surface of the lower support. In this embodiment, the spacer element itself has upper and lower preferably three-dimensional sliding surfaces.The upper and lower sliding surfaces on the spacer element are shaped relative to each other, and the elongated holes and / or guide sliding surfaces in each of the sub-surfaces of the upper and lower supports are shaped and arranged such that, for a defined position that the spacer element occupies on the screw spindle, the corresponding position of the guide elements in the appropriately shaped elongated holes and / or guide sliding surfaces determines the lateral extent of the spacer and the distance between the upper and lower sliding surfaces on the spacer element at a contact edge and / or at a position of the upper and lower guide sliding surfaces of the upper and lower supports associated with the position of the spacer element, and determines the height of the spacer.Guide sliding surfaces are special sliding surfaces designed to handle not only the vertical positioning (and thus the degree of vertical expansion of the placeholder) but also the lateral positioning (and thus the degree of lateral expansion of the placeholder).

[0069] Preferably, here too, shaping elements on the upper and / or the lower three-dimensional sliding surface and / or the shaping of the elongated hole enable a relative fixation of special, predetermined positions.

[0070] Furthermore, in one variant of this embodiment of the placeholder according to the invention for changing the vertical distance, a combination of the shaping of the sliding surfaces on the spacer element and a shaping on an inside of the upper and lower support is possible.

[0071] In a third particularly preferred embodiment of the placeholder according to the invention, its expansion device further comprises a movable double pair of spacer elements, each of which is laterally rotatable about a movable axis at a specific position on each spacer element of the double pair. The movable axes are arranged on a threaded nut and are displaceable along the threaded spindle by means of the threaded nut running on a thread of the screw spindle. Furthermore, the first spacer element of the double pair is laterally rotatable about a fixed axis, which is laterally fixed in the first partial surface of the upper support and in the first partial surface of the lower support. The second spacer element of the double pair is laterally rotatable about a fixed axis, which is laterally fixed in the second partial surface of the upper support and in the second partial surface of the lower support.

[0072] A double pair of spacer elements is therefore a pair consisting of a first spacer element and a second spacer element, wherein the first and second spacer elements each comprise an upper spacer element directed towards the upper support and a lower spacer element directed towards the lower support, which move together (i.e. parallel to each other around the same axis positions).

[0073] The threaded nut running on the thread of the screw spindle is designed in such a way that it includes sliding surfaces or a double toggle lever structure for the first and second partial surface of the upper support and for the first and second partial surface of the lower support, which are freely sliding on guide sliding surfaces of the first and second partial surface of the upper support and on guide sliding surfaces of the first and second partial surface of the lower support.

[0074] The angular position between the first spacer element and the second spacer element then determines the lateral extent of the placeholder, and a distance between the upper and lower sliding surfaces or a position of the double toggle structure at a contact edge (and thus also an opening angle of the toggle structure) and / or at a position of the upper and lower guide sliding surfaces of the upper and lower support assigned to the position of the threaded nut determines the height of the placeholder.

[0075] Furthermore, it is particularly advantageous if the placeholder, which contains a threaded spindle as an essential element of the expansion device's drive, is designed such that this threaded spindle has a thread on its second half that runs counter to a thread on the first half of the threaded spindle, and the expansion device comprises a first spacer element or a first pair of spacers that utilizes the first half of the threaded spindle and a second spacer element or a second pair of spacers that utilizes the second half of the threaded spindle. The respective dexterity of the thread on the threaded spindle depends on how the corresponding spacer element or pair of spacers is mounted relative to the axis of this threaded spindle.

[0076] The first and second spacer element or pair of spacer elements are each assigned first and second upper and lower three-dimensional sliding surfaces and corresponding upper and lower elongated holes and / or guide sliding surfaces. Optionally, one or two first and one or two second movable axes, as well as one or two first and one or two second fixed axes, are also assigned to each spacer element or pair of spacer elements.

[0077] A placeholder designed in this way allows for a two-sided expansion and support function, which increases the stability of the placeholder and prevents it from "tipping over". The first and second halves of the screw spindle and their respective associated elements do not need to be symmetrical to each other.

[0078] It is particularly advantageous, however, if in a spacer with a first and a second spacer element or double pair of spacer elements, the first and second spacer elements or double pair of spacer elements are designed and arranged in a mirror-image fashion. The spacer can then have an axis of symmetry that runs perpendicular to the axis of the screw spindle. Such mirror-image operation enables particularly high stability, especially when the spacer is inserted centrally into the intervertebral disc space between two vertebral bodies as an intervertebral implant and expanded there.

[0079] Alternatively, it is also possible that in a placeholder with a first and a second distance element or double pair of distance elements, the first and the second distance element or double pair of distance elements are designed and arranged in the same direction relative to each other.

[0080] In a placeholder with a first and a second spacer element, a screw spindle used as a drive element can be subjected to tension in order to guide the spacer elements towards each other during expansion. However, it can also be subjected to compression in order to guide the spacer elements away from each other during expansion.

[0081] In a particularly preferred embodiment of the placeholder according to the invention, its screw spindle has a guide structure between the first and second halves and / or between the first and second spacer elements or double pair of spacer elements, which is rotatably mounted in a retaining element but not laterally displaceable in its position, wherein the retaining element is movably, in particular vertically movable, but again not laterally displaceable in its position, mounted in the upper and lower supports. This serves to center the expansion device with respect to the supports.

[0082] The placeholder according to the invention can be maximally customized in one embodiment: The shape and position of the three-dimensional sliding surfaces and the shape and position of the elongated hole and / or the guide sliding surfaces are designed according to an individually required expansion behavior. Such a placeholder can be individually manufactured on request according to the properties required by the patient or the behavior preferred by the surgeon: For this purpose, examination data of the patient are first recorded, which includes both geometric data of the patient's existing problem and data characterizing the spinal material, such as local bone density and fragility. In addition, the treating surgeon can specify further requirements that he deems necessary for the best possible surgical procedure and for optimal function.From this data, an optimal size of the placeholder in the closed and expanded states, and, if necessary, an optimal interlocking structure and an optimal movement pattern for changes in lateral expansion and vertical distance between the upper and lower contact surfaces are determined independently. This leads to a physical coding of the placeholder, such as the shaping of freeform surfaces as sliding surfaces and the shaping of elongated holes as sliding holes. This type of individual determination of the optimal placeholder for the patient and / or surgeon can also be the content of a dedicated planning unit or corresponding computer program.

[0083] A placeholder specifically optimized for minimally invasive implantation has a kidney-shaped (or bean-shaped) form when viewed from above. Such a placeholder therefore has at most one lateral axis of symmetry, which runs parallel to the direction of its lateral extension.

[0084] The kidney-shaped or bean-shaped form simplifies implantation in an arc-shaped implantation pathway for a ventrally transverse implantation for transforaminal interbody fusion.

[0085] However, such a shape is not necessary for an oblique but straight implantation into the intervertebral disc space.

[0086] Partial surgical resection of the facet joint (facetettotomy) results in an arc-shaped implantation path with an implantation tunnel approximately 8 mm high and 13 mm wide. Biokinematic analyses indicate that implant heights between 7 and 14 mm are required for interbody fusion of the lumbar spine.

[0087] In one embodiment, the placeholder according to the invention has a minimum height of 7 mm or greater in the closed state and a maximum height of 14 mm or less in the expanded state, as well as a lateral extension, i.e., an extension parallel to the direction of lateral drift, of 13 mm or greater in the closed state. Preferably, it also has a lateral extension of 25 mm or less in the expanded state, but larger lateral extensions in the expanded state are also possible.

[0088] Preferably, a series of placeholders according to the invention are available that can accommodate different height ranges. For example, a small model of the placeholder is advantageous, allowing a minimum height of 7 mm and a maximum height of 11 mm, as is a large model of the placeholder, allowing a minimum height of 9 mm and a maximum height of 14 mm. Both the small and large models of the placeholder are available in kidney-shaped or, in principle, cuboid shapes. All models are also available with various adjustment levels for the lateral extent and vertical distance.

[0089] In summary, the placeholder according to the invention takes into account the technical requirement resulting from a biokinematic analysis of the intended surgical fusion of two lumbar vertebrae, taking into account the following simultaneously: The possible surgical approach and the resulting space constraints. The functional anatomy of the segment of movement to be stabilized. The possible directions of movement during the implantation procedure within the surgical approach. The optimal implant size according to biokinematic criteria.

[0090] The placeholder according to the invention, in its various embodiments, is preferably made of titanium: Titanium is one of the materials particularly preferred in surgery due to its durability and good biocompatibility, and the mechanics of the placeholder described here allow all its parts to be made of titanium. However, a ceramic version or a version with polymers of the polyetherketone (PEK) group, such as polyetheretherketone (PEEK) or polyetherketone kotone (PEKK), is also possible.

[0091] In a method according to the invention, the spacer, which is used as an intervertebral implant, is inserted minimally invasively between the endplate of the upper vertebral body and the endplate of the lower vertebral body in place of the intervertebral disc after removal of the disc (by means of facetotomy), such that the adjusting element of the spacer's expansion device, in a specific embodiment the screw spindle with its screw head, remains accessible with a tool. Once the spacer is in the desired position, the screw spindle is continuously rotated by the tool via the screw head. The spacer preferably expands laterally first to provide the largest possible corresponding support for the endplate of the upper vertebral body and the endplate of the lower vertebral body, thus preventing collapse or delayed sintering.Subsequently, in addition to continuing the lateral expansion, the vertical expansion of the placeholder is initiated by continuing to rotate the screw spindle. In a preferred embodiment, this vertical expansion can also be continued after the lateral expansion is already complete, i.e., after the placeholder has reached its maximum lateral extension—again by continuing to rotate the screw spindle in the same direction until the maximum height of the placeholder is reached. In extreme cases, the vertical expansion can also begin only after the lateral expansion is complete.The tool is then removed from the wound opening, and the spacer remains firmly in place (in place of the intervertebral disc) between the vertebral body endplate of the upper vertebral body and the vertebral body endplate of the lower vertebral body, which are now supported at the correct distance from each other by the expanded spacer.

[0092] There are now various possibilities to advantageously elaborate and further develop the teaching of the present invention and / or to combine the embodiments described above – as far as possible. For this purpose, reference should be made, on the one hand, to the claims subordinate to claim 1 and, on the other hand, to the following explanation of the exemplary embodiments of the invention with reference to the drawing.

[0093] They show: the Fig. 1a - 1d a first embodiment of a placeholder according to the invention for spinal surgery in the closed state and in the expanded, i.e., open and raised, state; the Fig. 2a und 2b a second embodiment of a placeholder according to the invention for spinal surgery in the closed state and in the expanded state; the Fig. 3a - 3c a third embodiment of a placeholder according to the invention for spinal surgery in the closed state, in the open state and in the expanded, i.e. open and raised state; the Fig. 4 a fourth embodiment of a placeholder according to the invention for spinal surgery in the closed state; the Fig. 5a - 5c an interior view of the fourth embodiment of a placeholder according to the invention in the closed state, in the open state and in the expanded, i.e., open and raised, state; the Fig. 6a - 6c a fifth embodiment of a placeholder according to the invention for spinal surgery in the closed state, in the open state and in the expanded, i.e., open and raised, state; the Fig. 7a - 7c an interior view of the fifth embodiment of a placeholder according to the invention in the closed state, in the open state and in the expanded, i.e., open and raised, state; the Fig. 8a - 8c a sixth embodiment of a placeholder according to the invention for spinal surgery in the closed state, in the open state and in the expanded, i.e., open and raised, state; the Fig. 9a - 9c A top view of the sixth embodiment of a placeholder according to the invention in the closed state, in the open state and in the expanded, i.e., open and raised, state; the Fig. 10 an exploded view of the sixth embodiment of a placeholder according to the invention; the Fig. 11a - 11c an interior view of the sixth embodiment of a placeholder according to the invention in the closed state, in the open state and in the expanded, i.e., open and raised, state; the Fig. 12a - 12c a seventh embodiment of a placeholder according to the invention for spinal surgery in the closed state, in the open state and in the expanded, i.e., open and raised, state; the Fig. 13a - 13d an interior view of the seventh embodiment of a placeholder according to the invention in the closed state, in the open state, in the open and partially raised state, and in the expanded, i.e., fully open and raised, state; the Fig. 14 a top view of the seventh embodiment of a placeholder according to the invention; the Fig. 15a und 15b a perspective view of the seventh embodiment of a placeholder according to the invention; the Fig. 16a - 16c An eighth embodiment of a placeholder according to the invention for spinal surgery in the closed state, in the open state and in the expanded, i.e., open and raised, state in a perspective view; the Fig. 17a - 17c An interior view of the eighth embodiment of a placeholder according to the invention in the closed state, in the open state, and in the expanded, i.e., fully opened and raised, state in a perspective view; the Fig. 18a - 18d A ninth embodiment of a placeholder according to the invention for spinal surgery in the closed state, in the open state, in the expanded (i.e., open and raised) state, and in the expanded and locked state in a perspective view; the Fig. 19a - 19d An interior view of the ninth embodiment of a placeholder according to the invention in the closed state, in the open state, in the expanded (i.e., open and raised) state, and in the expanded and locked state in a top view; the Fig. 20a - 20d An interior view of the ninth embodiment of a placeholder according to the invention in the closed state, in the open state, in the expanded (i.e., open and raised) state, and in the expanded and locked state in a perspective view; the Fig. 21a - 21c a tenth embodiment of a placeholder according to the invention for spinal surgery in the closed state, in the open state and in the expanded, i.e. open and raised, state in a side view and a top view; the Fig. 22a - 22c An interior view of the tenth embodiment of a placeholder according to the invention in the closed state, in the open state and in the expanded, i.e., open and raised, state in a perspective view; the Fig. 23a - 23c An interior view of the tenth embodiment of a placeholder according to the invention in the closed state, in the open state and in the expanded, i.e., open and raised, state in a top view and a side view; the Fig. 24a - 24c A further interior view of the tenth embodiment of a placeholder according to the invention in the closed state, in the open state and in the expanded, i.e., open and raised, state in a perspective view: the Fig. 25a - 25c An eleventh embodiment of a placeholder according to the invention for spinal surgery in the closed state, in the open state and in the expanded, i.e., open and raised, state in a perspective view; the Fig. 26a - 26d An interior view of the eleventh embodiment of a placeholder according to the invention in the closed state, in the open state, in the expanded (i.e., open and raised) state, and in the expanded and locked state in a perspective view; the Fig. 27a und 27b two variants of implanting the spacer in a function as an intervertebral body implant.

[0094] The Fig. 1a - 1d Figure 1 shows a first embodiment of a placeholder 10 according to the invention for spinal surgery in two perspective views each in the closed state and in the expanded, i.e., open and raised, state, which comprises an upper support 20 with an upper support surface 21 and a lower support 22 with a lower support surface 23, the relative position of which is changeable, wherein the upper 21 as well as the lower support surface 23 each have a first 21-1, 23-1 and a second partial surface 21-2, 23-2, which touch each other at an edge 24-1, 24-2, 25-1, 25-1 in a closed state of the placeholder 10.The placeholder also includes an expansion device 30, with which the support surfaces 21, 23 can be changed in their lateral extension by laterally drifting apart the first 21-1, 23-1 and second sub-surface 21-2, 23-2 up to a maximum drift amount 54 between a minimum lateral extension 52 and a maximum lateral extension 53, as well as in their vertical distance between a minimum height 50 and a maximum height 51 of the placeholder 10, so that the placeholder 10 can be adjusted between a closed and an expanded state.

[0095] To achieve expansion in the simplest possible way after the spacer 10 has been placed at its point of action in the patient's spine, the expansion device 30 includes a single drive; that is, the expansion, and thus both the change in the lateral extension of the contact surfaces 21, 23 and the change in the vertical distance, are achieved via one and the same drive. This drive has as its essential element a screw spindle 31, by means of which the expansion of the spacer 10 can be carried out. In this first embodiment of a spacer 10 according to the invention, the screw spindle 31 is part of a wedge mechanism, or more precisely, a mechanism based on the principle of a wedge and counter-wedge, with which the change in the lateral extension as well as the vertical distance of the contact surfaces 21, 23 is carried out simultaneously and in a mutually dependent manner – in the same ratio to each other.

[0096] Two imaginary right pyramids stand at a defined distance, apex to apex, mirroring each other in such a way that their two heights lie on a common straight line. Two opposing, materially formed lateral edges of each pyramid create the wedges that change the spatial position of a common counter-wedge (∇ Nabla) when the pyramids approach each other.

[0097] The spacer can be used as a spinal implant in the sense of a spacer or intervertebral implant to replace an intervertebral disc, or in the sense of a vertebral body replacement to replace a vertebral body, or also in the sense of augmenting a vertebral body within the vertebral body itself (spondyloplasty).

[0098] The first 21-1, 23-1 and the second partial surface 21-2, 23-2 of the upper 21 and the lower support surface 23 have an interlocking structure 26 in the form of interlocking teeth at the edge 24-1, 24-2, 25-1, 25-1 where they touch in the closed state. This structure is designed such that, during expansion, it allows the first 21-1, 23-1 and the second partial surface 21-2, 23-2 to drift apart laterally, and in the expanded state, a lateral gap 27 extending perpendicular to the direction of lateral drift through the upper 21 and the lower support surface 23 has a gap width 55 that is smaller than the maximum drift amount 54.

[0099] In the Fig. 2a und 2b A second embodiment of a placeholder 10 according to the invention for spinal surgery is shown in a perspective view in the closed and expanded states. This placeholder 10 again comprises an upper support 20 with an upper support surface 21 and a lower support 22 with a lower support surface 23, the relative position of which is changeable, wherein the upper 21 as well as the lower support surface 23 each have a first 21-1, 23-1 and a second partial surface 21-2, 23-2 which, in a closed state of the placeholder 10, touch at an edge 24-1, 24-2, 25-1, 25-1.The placeholder also includes an expansion device 30, with which the support surfaces 21, 23 can be changed in their lateral extension by laterally drifting apart the first 21-1, 23-1 and second sub-surface 21-2, 23-2 up to a maximum drift amount 54 between a minimum lateral extension 52 and a maximum lateral extension 53, as well as in their vertical distance between a minimum height 50 and a maximum height 51 of the placeholder 10, so that the placeholder 10 can be adjusted between a closed and an expanded state.

[0100] In this second embodiment of the placeholder 10 according to the invention, the first 21-1, 23-1 as well as the second partial surface 21-2, 23-2 of the upper 21 as well as the lower support surface 23 have a wave-like interlocking structure 26 at the edge 24-1, 24-2, 25-1, 25-1 where they touch in the closed state. This structure is also designed such that, during expansion, it allows the first 21-1, 23-1 and the second partial surface 21-2, 23-2 to drift apart laterally, and in the expanded state, a lateral gap 27 extending perpendicular to the direction of lateral drift through the upper 21 as well as the lower support surface 23 has a gap width 55 that is significantly smaller than the maximum drift amount 54.In the closed state of the placeholder 10, the interlocking structures of the first and second partial surfaces of the upper as well as the lower support surfaces show an interlocking according to the "key-lock principle" over the entire length of the placeholder, so that in the closed state the upper as well as the lower support surface can be perceived as a continuous surface.

[0101] The expansion device 30 of this second embodiment of the placeholder 10 according to the invention is now also configured to perform the change in lateral extension and vertical distance in two independent and freely definable movement patterns, but by means of a single drive. For this purpose, the expansion device of the placeholder 10 comprises a movable spacer element 34, which is movable along the screw spindle 31 by rotating the screw head 32 and has four guide elements 42 in the form of mushroom-head bolts, each of which is displaceable in a first upper elongated hole 38 in the first partial surface 21-1 and in a second upper elongated hole 38 of the second partial surface 21-2 of the upper support 20, and in a first lower elongated hole 39 of the first partial surface 23-1 and in a second lower elongated hole 39 of the second partial surface 23-2 of the lower support 22.

[0102] The spacer element 34 itself has upper and lower three-dimensional sliding surfaces 40, 41 which are shaped relative to each other on the spacer element 34, and the elongated holes 38 in each of the partial surfaces of the upper and lower support are shaped and arranged such that, for a defined position that the spacer element 34 assumes on the screw spindle 31, the corresponding position of the guide elements 42 in the form of the mushroom-head bolt in the correspondingly shaped elongated holes 38, 39 determines the lateral extent of the placeholder 10 and the distance between the upper 40 and the lower three-dimensional sliding surface 41 on the spacer element 34 at a contact edge 43 of the upper 20 and the lower support 22, respectively, determines the height of the placeholder 10. Since in this embodiment the inside of the upper and lower supports 20, 22 also has a shape, the contact edge 43 "moves" during the expansion of the placeholder.

[0103] The expansion device 30 comprises a first spacer element 34-1, which utilizes the first half of the screw spindle and a second spacer element 34-2, which utilizes the second half of the screw spindle 31, wherein first and second upper and lower three-dimensional sliding surfaces and corresponding upper 38 and lower elongated holes 39 are assigned to the first 34-1 and second spacer element 34-2, respectively.

[0104] This second embodiment of the placeholder 10 according to the invention therefore works with a wedge and counter-wedge principle, but by sliding the supports formed on the inner sides on the sliding surfaces of the wedges and the mushroom heads arranged thereon, which can slide as guide elements 42 in elongated holes 38, 39 in the partial surfaces 21-1, 21-2, 23-1, 23-2 of the upper and lower supports 20, 22, the previously fixed ratio of lateral to vertical expansion when using a wedge and counter-wedge principle is broken, so that the wedges act as corresponding spacer elements 34-1, 34-2.

[0105] The bearing surfaces within the nablas and deltas (due to their spatial extent and shape) can glide along tracks that follow the expansion in width and height. Even if the wedges and the inner surfaces of the bearings have flat sliding surfaces, thus achieving a linear change in the vertical distance, the sequence of lateral expansion is independently determined by the configuration of the elongated slot. This allows for non-linear expansion, such that initially rapid lateral expansion occurs, while upon reaching a certain vertical distance (and – when used as an intervertebral implant – upon the build-up of a certain pressure on the spacer by the upper and lower vertebral bodies), only minimal lateral expansion takes place, and finally, the last stage of the change in vertical distance can occur without any further change in lateral expansion.

[0106] The Fig. 3a - 3c Figure 1 shows a third embodiment of a placeholder 10 according to the invention for spinal surgery in the closed state, in the open state and in the expanded, i.e., opened and raised state, each in perspective views.

[0107] This third embodiment of the placeholder 10 according to the invention functions essentially like the second embodiment and is therefore also described by the second embodiment at the relevant points. However, it has three special features in which it differs from the second embodiment: Placeholder 10 does not have an interlocking structure at the edge 24-1, 24-2, 25-1, 25-1, where the first 21-1, 23-1 and the second sub-surface 21-2, 23-2 of the upper 21 and the lower support surface 23 touch. This results in a lateral gap 27 during expansion, which can also be referred to here as the median or intermediate gap, the width 55 of which corresponds to the maximum drift 54 ​​of the lateral extension of the upper 21 and lower support surfaces 23.The elongated holes 38, 39, in which the mushroom-shaped guide elements, arranged on the wedge-shaped spacer elements, slide, are shaped such that initially a linear change in the lateral extent occurs up to a maximum drift value 54. During this time, a linear change in the lateral position of the partial surfaces of the respective bearing surfaces, and thus in the lateral extent of the placeholder, begins. Then, a linear change in the vertical distance or vertical stroke continues, while the lateral extent remains constant. Both the change in lateral extent and the change in vertical distance occur linearly, but offset from each other. The algorithm of this sequence is encoded in the shape of the elongated holes. The placeholder 10 has a kidney-shaped form and is therefore particularly suitable for implantation along an arc-shaped implantation path.

[0108] In the Fig. 4 A fourth embodiment of a placeholder 10 according to the invention for spinal surgery in the closed state is shown, of which the Fig. 5a - 5c show an interior view in the closed state, in the open state and in the expanded state, i.e., opened and raised.

[0109] The fourth embodiment of the placeholder according to the invention for spinal surgery also comprises an upper support 20 with an upper support surface 21 and a lower support 22 with a lower support surface 23, the relative position of which can be changed, wherein the upper 21 as well as the lower support surface 23 each have a first 21-1, 23-1 and a second partial surface 21-2, 23-2 which touch each other at an edge 24-1, 24-2, 25-1, 25-1 in a closed state of the placeholder 10.The placeholder also includes an expansion device 30, with which the lateral extension of the support surfaces 21, 23 can be changed by laterally drifting apart the first 21-1, 23-1 and second sub-surface 21-2, 23-2 of the support surfaces 21, 23 up to a maximum drift amount 54 between a minimum lateral extension 52 and a maximum lateral extension 53, as well as in their vertical distance to each other between a minimum height 50 and a maximum height 51 of the placeholder 10, so that the placeholder 10 can be adjusted between a closed and an expanded state.

[0110] And in this fourth embodiment of the placeholder 10 according to the invention, the first 21-1, 23-1 as well as the second partial surface 21-2, 23-2 of the upper 21 as well as the lower support surface 23 have an interlocking structure 26 in the form of interlocking teeth at the edge 24-1, 24-2, 25-1, 25-1 where they touch in the closed state. This structure is designed in such a way that, during expansion, it allows the first 21-1, 23-1 and the second sub-surface 21-2, 23-2 to drift apart laterally, and in the expanded state, a lateral gap running perpendicular to the direction of lateral drift through the upper 21 as well as the lower support surface 23 has a gap width that is smaller than the maximum drift amount: In this case, the gap width in the central area of ​​the support surfaces 21, 23 is zero; only in the edge areas of the support surfaces does a true lateral gap still occur.

[0111] The expansion device 30 of the fourth embodiment of the placeholder 10 according to the invention further comprises a movable spacer element 34, which differs from the spacer elements described so far: It is laterally rotatable at a position on the spacer element 34 about a movable axis 36, which is displaceable along the screw spindle 31 by means of a threaded nut integrated into the movable axis 36 and running on a thread 33 of the screw spindle 31, wherein the movable axis 36 is indirectly arranged to run in an upper elongated hole 38 in the first partial surface 21-1 of the upper support 20 and in a lower elongated hole 39 in the first partial surface 23-1 of the lower support 22. The spacer element is also laterally rotatable about a fixed axis 37, which is laterally fixed in the second sub-surface 21-2 of the upper support 20 and in the second sub-surface 23-2 of the lower support 22.

[0112] Furthermore, the spacer element is freely slidable at a first and / or a second end on an upper three-dimensional sliding surface 40 below the first 21-1 and / or the second partial surface 21-2 of the upper support 20, and on a lower three-dimensional sliding surface 41 above the first 23-1 and / or the second partial surface 23-2 of the lower support 22, wherein the upper three-dimensional sliding surface 40 and the lower three-dimensional sliding surface 41 are shaped relative to each other such that the first and / or second end of the spacer element 34 assumes a defined position on the upper 40 as well as on the lower three-dimensional sliding surface 41 for every rotation angle of the spacer element 34 about the fixed axis 37, the absolute position of which and the corresponding position of the movable axis 36 in the correspondingly shaped elongated holes 38.39 the lateral extent of the placeholder 10 and the distance between the upper 40 and the lower three-dimensional sliding surface 41 in the closed state determines the height of the placeholder 10.

[0113] In this fourth embodiment of the placeholder 10 according to the invention, the expansion device 30 comprises a first spacer element 34-1, which utilizes the first half 31-1 of the screw spindle, and a second spacer element 34-2, which utilizes the second half 31-2 of the screw spindle 31. The first 34-1 and second spacer element 34-2 are associated with first 40-1, 41-1 and second upper and lower three-dimensional sliding surfaces 40-2, 41-2, respectively, as well as first and second movable axes 36-1, 36-2, respectively, and first and second fixed axes 37-1, 37-2, respectively, and corresponding upper 38-1, 38-2 and lower elongated holes 39-1, 39-2.

[0114] The fourth embodiment of the placeholder 10 according to the invention again has a kidney-shaped form and is therefore particularly suitable for implantation along an arc-shaped implantation path. After being placed at its site of action, this placeholder can then be expanded in a mirror-image fashion using the spacer elements, which is very advantageous if, for example, it has been placed in a central position in place of the intervertebral disc between two vertebral bodies and a uniform pressure is to be exerted over the entire central area during expansion.

[0115] The position and shape of the elongated holes and the three-dimensional sliding surfaces of the fourth embodiment are designed such that a non-linear lateral expansion and a linear vertical expansion occur.

[0116] The Fig. 6a - 6c Figure 1 shows a fifth embodiment of a placeholder 10 according to the invention for spinal surgery in the closed state, in the open state and in the expanded, i.e., open and raised, state – again in a perspective view, while in the Fig. 7a - 7c An interior view of the fifth embodiment of a placeholder 10 according to the invention is shown in the closed state, in the open state and in the expanded, i.e. open and raised, state - in the same perspective view.

[0117] For this fifth embodiment of the placeholder 10 according to the invention, what has been said for the fourth embodiment applies, however, it differs from this fourth embodiment in the following special features: The spacer element 34 or the spacer elements 34-1, 34-2 are realized by means of cams, the ends of the cams being slidably mounted on three-dimensional sliding surfaces 41-1, 41-2. The first 21-1, 23-1 as well as the second partial surface 21-2, 23-2 of the upper 21 as well as the lower bearing surface 23 have an interlocking structure 26 in the form of interlocking teeth at the edge 24-1, 24-2, 25-1, 25-1 where they touch in the closed state. This structure continues - partly periodically, partly at irregular intervals - over the entire length of the upper 21 as well as the lower support surface 23 and is designed in such a way that, in the event of expansion, it allows the first 21-1, 23-1 and second sub-surface 21-2, 23-2 to drift apart laterally.However, the structure of the interlocking teeth extends over the entire lateral width of the spacer 10 in the closed state, so that even in the expanded state no lateral gap is created, i.e. the gap width of an imaginary lateral gap perpendicular to the direction of lateral drifting apart is zero. Moreover, the upper 20 and the lower support 22 are shaped in such a way that the interlocking tooth structure 26 of the first partial surface 21-1, 23-1 on a support structure 44 in the part of the support 20, 22 belonging to the second partial surface 21-2, 23-2, and the interlocking tooth structure 26 of the second partial surface 21-2, 23-2 on a support structure 44 in the part of the support 20, 22 belonging to the first partial surface 21-1, 23-1, can slide against each other even more stably and securely during lateral drifting apart during the expansion of the spacer 10. The fifth embodiment of the placeholder 10 according to the invention has a broadly cuboid shape in its top view, albeit with rounded corners. It is therefore particularly suitable for a straight implantation path 70; however, its use on an arcuate implantation path 70 is not precluded due to its rounded corners. The screw spindle 31, used as the central drive element, is located in an edge region in all states of the placeholder 10. This facilitates actuation of the screw spindle 31 by means of a tool engaging the screw head 32, provided the placeholder 10 is appropriately positioned at its point of action ventrally in front of the vertebral canal of the spine.A closer look at the internal structure of the fifth embodiment of the placeholder 10 according to the invention reveals that the position of the cams 34-1, 34-2 relative to the axis of the screw spindle 31 is approximately 20° in the closed state of the placeholder 10, approximately 70° in the initially laterally open state of the placeholder, and approximately 100° in the expanded, i.e., open and raised, state. The change in the vertical distance, and thus the vertical stroke, therefore occurs relatively quickly at the end of the expansion of the placeholder as the cams 34-1, 34-2 slide over a short but steeply rising section of the three-dimensional sliding surfaces 40-1, 40-2, 41-1, 41-2.

[0118] In the Fig. 8a - 8c is a sixth embodiment of a placeholder 10 according to the invention for spinal surgery in the closed state, in the open state and in the expanded, i.e. open and raised state, each in a perspective view, in the Fig. 9a - 9c a top view of the sixth embodiment of a placeholder 10 according to the invention in the closed state, in the open state and in the expanded, i.e. open and raised, state; in the Fig. 10 an exploded view of the sixth embodiment of a placeholder 10 according to the invention and in the Fig. 11a- 11c An interior view of the sixth embodiment of a placeholder 10 according to the invention is shown in the closed state, in the open state and in the expanded, i.e., open and raised state.

[0119] This sixth embodiment of the placeholder 10 according to the invention is described in relation to the fifth embodiment except for the following special features: The first 21-1, 23-1 and the second sub-surface 21-2, 23-2 of the upper 21 and the lower support surface 23 exhibit an irregularly interlocking structure 26 along the entire length of the upper 21 and the lower support surface 23 at the edge 24-1, 24-2, 25-1, 25-1 where they touch in the closed state. This structure is also designed such that it allows the first 21-1, 23-1 and second sub-surface 21-2, 23-2 to drift apart laterally during expansion. Although the interlocking structure 26 does not extend over the entire width of the support surfaces 21, 23 in the closed state of the placeholder 10, no lateral gap is created here either in the expanded state; the gap width of an imaginary lateral gap perpendicular to the direction of lateral drifting apart is therefore zero.Here too, the upper 20 and the lower support 22 are shaped such that the interlocking structure 26 of the first partial surface 21-1, 23-1 on a support structure 44 in the part of the support 20, 22 belonging to the second partial surface 21-2, 23-2, and the interlocking tooth structure 26 of the second partial surface 21-2, 23-2 on a support structure 44 in the part of the support 20, 22 belonging to the first partial surface 21-1, 23-1, can slide against each other even more stably and securely during lateral drifting apart during the expansion of the spacer 10. The sixth embodiment of the spacer 10 according to the invention has a kidney-shaped or arc-shaped form on one side in its top view, while the shape on the other side is, in the broadest sense, cuboid with rounded corners.It is therefore particularly suitable for an arc-shaped implantation pathway 70, since the otherwise "abrasive" side of the placeholder 10 is specifically designed in an arc shape; however, its use on a straight implantation pathway 70 is not excluded.

[0120] Both in the exploded view of the Fig. 10 as well as in the views of the inner workings of the Fig. 11a - 11c In the sixth embodiment, the two-part design of the screw spindle 31 with a right-hand thread on its first half 31-1 and a left-hand thread on its second half 31-2 is very clearly visible.

[0121] The screw spindle 31 of this sixth embodiment of a placeholder according to the invention has a guide structure 45 between its first 31-1 and second half 31-2, which is rotatably mounted in a retaining element 46 but not laterally displaceable in its position, wherein the retaining element 46 is movably, in particular vertically movable, but again not laterally displaceable in its position, mounted in the upper 20 and the lower support 22, and thus centers the expansion device with respect to the supports.

[0122] The Fig. 12a - 12c Finally, a seventh embodiment of a placeholder 10 according to the invention for spinal surgery is shown in a perspective view in the closed state, in the open state, and in the expanded state (i.e., opened and raised). Fig. 14 is a top view and in the Fig. 15a und 15b two further perspectives - compared to the Fig. 12a-12c More detailed views of the seventh embodiment of a placeholder 10 according to the invention are shown in the closed state.

[0123] Here too, for the description of the seventh embodiment, reference is first made to the description of the sixth embodiment of the placeholder 10 according to the invention, from which it differs in the following points: The seventh embodiment of the placeholder 10 according to the invention again has a purely kidney-shaped form and is therefore particularly suitable for implantation on an arc-shaped implantation path 70. As shown in the interior views of the seventh embodiment of a placeholder according to the invention, Fig. 13a bis 13d As can be seen in the closed state with the cams 34-1, 34-2 serving as spacers at an angle of approximately 25° to the axis of the screw spindle 31, in the open state with the cams 34-1, 34-2 at an angle of approximately 65° to the axis of the screw spindle 31, in the open and partially raised state with the cams 34-1, 34-2 at an angle of approximately 110° to the axis of the screw spindle 31, and in the expanded, i.e., fully open and raised state with the cams 34-1, 34-2 at an angle of approximately 120° to the axis of the screw spindle 31, this embodiment is the one that combines the various features of the invention to the greatest advantage:

[0124] In addition to the interlocking structure 26 of the sub-surfaces 21-1, 23-1, 21-2, 23-2 with the support of bearing structures 44 in the supports 20, 22 of the respective other sub-surface 21-2, 23-2, 21-1, 23-1 and thus a secure sliding during the change of the lateral extent as well as a prevention of a continuous lateral gap 27, a kidney-shaped shape for use in an arc-shaped implantation path 70, an arrangement of the screw spindle 31 in the edge region of the placeholder 10 and the use of two spacer elements 34-1, 34-2 in the form of cams that operate in a mirror image, wherein the screw spindle 31 in turn has a guide structure 45 between its first 31-1 and second half 31-2, which is rotatably mounted in a retaining element 46 but not laterally displaceable in its position is, and the retaining element 46 is only vertically movable in the upper 20 and in the lower support 22,This seventh embodiment of the placeholder 10 according to the invention shows an expansion device 30 that executes the change in lateral extension and vertical distance in two independently and freely defined movement patterns – which are varied several times during the expansion – by means of a single drive: This is implemented with non-linear, curved sliding surfaces or "displacement surfaces" that resemble the articulating surfaces of the vertebral joints, as well as correspondingly shaped elongated holes used as sliding holes.

[0125] In the Fig. 16a - 16c An eighth embodiment of a placeholder 10 according to the invention for spinal surgery is shown in a perspective view in the closed state, in the open state, and in the expanded state, i.e., opened and raised. Fig. 17a - 17c show a corresponding and also perspective interior view of the eighth embodiment.

[0126] This placeholder 10 in turn comprises an upper support 20 with an upper support surface 21 and a lower support 22 with a lower support surface 23, the relative position of which can be changed, wherein the upper 21 as well as the lower support surface 23 each have a first 21-1, 23-1 and a second sub-surface 21-2, 23-2, which touch each other at an edge 24-1, 24-2, 25-1, 25-1 in a closed state of the placeholder 10. The placeholder also includes an expansion device 30, with which the lateral extension of the support surfaces 21, 23 can be changed by laterally drifting apart the first 21-1, 23-1 and second sub-surface 21-2, 23-2, as well as in their vertical distance between the upper 21 and the lower support surface 23, so that the placeholder 10 can be adjusted between a closed and an expanded state.

[0127] This eighth embodiment of the placeholder according to the invention again follows a wedge principle described in the first three embodiments, but in a modified form: The movable spacer elements 34-1, 34-2 again have a wedge shape, which, however, is not solely responsible for changing the vertical distance between the upper 20 and the lower support 22. Rather, the movable spacer elements 34-1, 34-2 comprise guide elements 42 on their side surfaces for this purpose.These guide elements in turn slide in upper and lower guide sliding surfaces 38, 39 which are arranged under the upper partial surfaces 21-1, 21-2 of the upper support 20 and on the lower partial surfaces 23-1, 23-2 of the lower support 22 (i.e. directed inwards and, from a perspective that "on" reflects an outer position, then also "under" the lower partial surfaces 23-1, 23-2), so that the guide elements 42 arranged on the spacer elements 34-1, 34-2 can slide in these upper and lower guide sliding surfaces 38, 39.

[0128] The guide sliding surfaces 38, 39 are designed – in contrast to the upper and lower, preferably three-dimensional, sliding surfaces 40, 41 mentioned in other embodiments at approximately similar positions – such that they fully accommodate the lateral positioning, i.e., their shape is very sharply defined and accurately reflects both the lateral and vertical movements. The expansion device 30 of this eighth embodiment can thus execute the change in lateral extension and vertical distance in two independent and freely definable movement patterns using a single drive: The lateral and vertical movements can be freely encoded in the guide sliding surfaces 38, 39 by means of appropriate shaping. Further (sliding) surfaces of the spacer elements 34-1, 34-2 support this movement pattern.

[0129] Unlike the wedge-shaped spacer elements of the first three embodiments, the spacer elements 34-1 and 34-2 move on a screw spindle 31 from the inside (to achieve a closed state) to the outside, i.e., away from each other, to achieve an expanded state. In the closed state, the two wedge-shaped spacer elements 34-1 and 34-2 rest against a guide structure 45, which is also arranged on the screw spindle 31. A retaining element 46 on the screw spindle 31 ensures the correct positioning of the guide structure 45 relative to the screw spindle. Moving structures in lateral elongated slots in the partial surfaces 21-1, 21-2, 23-1, and 23-2 ensure the correct positioning of the guide structure 45 relative to the upper support 20 and the lower support 22.

[0130] In this eighth embodiment of the placeholder 10 according to the invention, the first 21-1, 23-1 as well as the second partial surface 21-2, 23-2 of the upper 21 as well as the lower support surface 23 have an interlocking structure with additional support structures 44 at the edge 24-1, 24-2, 25-1, 25-1 where they touch in the closed state. This interlocking structure is also designed in such a way that, during expansion, it allows the first 21-1, 23-1 and the second sub-surface 21-2, 23-2 to drift apart laterally, and in the expanded state, a lateral gap 27 running perpendicular to the direction of lateral drift through the upper 21 as well as the lower support surface 23 has a gap width 55, which is significantly smaller than the maximum drift amount 54 - in the case of this eighth embodiment, it is virtually non-existent and therefore zero.In the closed state of the placeholder 10, the interlocking structures of the first and second sub-surfaces of the upper as well as the lower support surfaces show an interlocking according to the "key-lock principle" over the entire length of the placeholder, so that in the closed state the upper as well as the lower support surface can be perceived as a continuous surface.

[0131] The Fig. 18a - 18d Figure 9 shows a ninth embodiment of a placeholder 10 according to the invention for spinal surgery in the closed state, in the open state, in the expanded (i.e., open and raised) state, and in the expanded and locked state in a perspective view. Fig. 19a - 19d is an interior view of the ninth embodiment in the closed state, in the open state, in the expanded (i.e., open and raised) state, and in the expanded and locked state shown in a top view and the Fig. 20a -20d The interior view of the ninth embodiment is shown again in a perspective view.

[0132] In this ninth embodiment, the number of movable spacer elements 34-11, 34-12, 34-21, 34-22 was doubled compared to the fourth to seventh embodiments. Each spacer element 34-11, 34-12, 34-21, 34-22 acts as a double pair, which is laterally rotatable about a fixed axis 37 in the first partial surface 21-1, 23-1 of the upper 20 and lower support 22 or in the second partial surface 21-2, 23-2 of the upper 20 and lower support 22, and about a movable axis 36-11, 36-12, 36-21, 36-22 which is arranged on a threaded nut 35-1, 35-2, wherein the threaded nut 35-1, 35-2 can slide on the screw spindle 31 from the inside (to realize a closed state) to the outside, i.e. away from each other, to realize an expanded state.

[0133] The position of the threaded nut 35-1, 35-2 on the screw spindle 31, via the corresponding angular position of the spacer element double pairs 34-11, 34-12, 34-21, 34-22, achieves the lateral extension of the placeholder 10, and the special shape of the threaded nut 35-1, 35-2, which for this purpose has sliding surfaces 40, 41 that can slide on guide sliding surfaces 38, 39 in the first 21-1, 23-1 and second partial surfaces 21-2, 23-2 of the upper 20 and lower support 22, achieves the vertical extension of the placeholder 10.

[0134] Again, a retaining element 46 on the screw spindle 31 ensured the correct positioning of the entire expansion device 30 to the upper 20 and lower support 22.

[0135] In the Fig. 21a - 21c A tenth embodiment of a placeholder 10 according to the invention for spinal surgery is shown in a side view and a top view in the closed state, in the open state and in the expanded, i.e. open and raised, state. Fig. 22a - 22c show an interior view of the corresponding states of the tenth embodiment in a perspective view, which Fig. 23a - 23c An interior view of the corresponding state of the tenth embodiment, each in a top view and a side view. In the Fig. 24a - 24c A further interior view of the respective states of the tenth embodiment is shown in a perspective view.

[0136] This tenth embodiment initially corresponds in its structure to the ninth embodiment. However, the vertical extension is not achieved by a threaded nut 35-1, 35-2 comprising sliding surfaces, but rather the threaded nut 25-1, 25-2 here each comprises a toggle lever structure 57, which is located in corresponding guide structures on the undersides of the partial surfaces 21-1, 21-2, 23-1, 23-2 of the upper 20 and lower 22 support: The position of the threaded nut 35-1, 35-2 on the screw spindle 31 determines the position of the toggle lever structure 57, its opening angle and thus the vertical extension of the placeholder 10.

[0137] The tenth embodiment also features an interlocking structure designed in such a way that, during expansion, it allows the first 21-1, 23-1 and second sub-surface 21-2, 23-2 to drift apart laterally, and in the expanded state, a lateral gap 27 running perpendicular to the direction of lateral drift through the upper 21 as well as the lower support surface 23 between the first 21-1, 23-1 and second sub-surface 21-2, 23-2 has a gap width 55, which is significantly smaller than the maximum drift amount 54.

[0138] The Fig. 25a - 25c Figure 10 shows an eleventh embodiment of a placeholder 10 according to the invention for spinal surgery in the closed state, in the open state, and in the expanded state (i.e., opened and raised) in a perspective view. Fig. 26a - 26d An interior view of the eleventh embodiment of a placeholder 10 according to the invention is shown in a perspective view in the closed state, in the open state, in the expanded state (i.e., open and raised state), and in the expanded and locked state.

[0139] This eleventh embodiment of a placeholder according to the invention again comprises movable spacer elements 34-1, 34-2, which move in opposite directions on the screw spindle 31: In a closed state of the placeholder 10, these spacer elements 34-1, 34-2 are adjacent to a guide structure 45 with a retaining element 46 inside the placeholder 10. During the expansion of the placeholder 10, these spacer elements 34-1, 34-2 move away from each other outwards.The eleventh embodiment operates according to a combination of a wedge principle with guidance through appropriately shaped elongated holes 38, 39 (which determine the course of the lateral expansion), in which guide elements 42 (here in the form of mushroom-head bolts) of the spacer elements 34-1, 34-2 slide, as well as additional sliding surfaces 40, 41 under the partial surfaces 21-1, 21-2, 23-1, 23-2 of the upper 20 and lower support 22 and, optionally, also in the elongated holes 38, 39 themselves, by which the course of the vertical expansion of the placeholder 10 is determined.

[0140] The eleventh embodiment also features an interlocking structure of the first 21-1, 23-1 and second sub-surfaces 21-2, 23-2 of the upper 20 and lower support 22.

[0141] This eleventh embodiment of a placeholder 10 according to the invention shows a particularly stable embodiment of such a placeholder 10.

[0142] All embodiments are designed so that the placeholders can be implanted in a simple manner and then expanded accordingly, but they also allow the corresponding reverse process if necessary: ​​They can be closed again by a corresponding movement of the screw spindle 31 in the opposite direction of rotation and are therefore easier to remove from the patient's spine.

[0143] In the Fig. 27a und 27b Two variants of the implantation of the spacer in a function as an intervertebral body implant are shown: The Fig. 27a Figure 1 shows an arc-shaped implantation pathway 70 of a kidney-shaped placeholder 10 according to the invention into an intervertebral disc space between two vertebral bodies 61 of a vertebra 60 of a patient's spine. A vertebra 60 comprises a vertebral body 61 and a vertebral arch 62, which in turn includes transverse processes 64, spinous processes 65, and articular processes 66. Inside the vertebral canal 63 is the vertebral canal 63, which must not be damaged under any circumstances, as neural structures run through it. Fig. 27b In contrast, a straight implantation path 70 of a placeholder 10 with a cuboid base shape is shown in this intervertebral disc space.

[0144] This comparison reveals Fig. 27a und 27b It is easily recognizable that a minimally invasive, arc-shaped implantation route 70 – as well as a minimally invasive, straight implantation route 70 – passes through the vertebral arch 62, the arc-shaped implantation route 70 of the Fig. 27a However, it largely avoids the spinal canal 63, whereas a straight implantation path 70, as in the Fig. 27b shown, running dangerously close to spinal canal 63.

[0145] Furthermore, the kidney-shaped placeholder 10, which was implanted via the arc-shaped implantation path 70, can be inserted very easily and symmetrically into the intervertebral disc space ventrally, whereas a straight implantation path 70 leads to an asymmetrical position of the placeholder 10 in the intervertebral disc space.

[0146] The Fig. 27a This also makes it clear once again that a kidney-shaped placeholder 10 according to the invention is significantly easier to move to its site of action via an arc-shaped implantation path 70 compared to a cuboid-shaped placeholder 10 according to the invention.

[0147] The procedure for implanting the spacer 10 via the arcuate or straight implantation path 70 has already been described above.

[0148] Finally, it should be particularly emphasized that the above-mentioned

[0149] The exemplary embodiments serve only to describe the claimed teaching and do not limit it to these exemplary embodiments. In particular, the exemplary embodiments described above could be combined with one another, where possible. The numerous exemplary embodiments of the placeholder 10 shown here demonstrate a selection of the use of the features of the invention, both individually and in combination. As shown here, each feature alone already fulfills the object of the present invention. The combination of the features of the invention then results in an additional benefit.

Claims

1. Placeholder (10) for spinal surgery, which comprises: - an upper support (20) with an upper support surface (21) and a lower support (22) with a lower support surface (23), the relative position of which to one another can be changed, wherein the upper (21) as well as the lower support surface (23) in each case has a first (21-1, 23-1) and a second sub-surface (21-2, 23-2), which touches an edge (24-1, 24-2, 25-1, 25-1) in a closed state of the placeholder (10), and - an expansion device (30), by means of which the support surfaces (21, 23) can be varied in their lateral extension by a lateral drifting apart of the first (21-1, 23-1) and second sub-surface (21-2, 23-2) up to a maximum drift amount (54) between a minimum lateral extension (52) and a maximum lateral extension (53) as well as in the vertical distance between a minimum height (50) and a maximum height (51) of the placeholder (10), so that the placeholder (10) can be adjusted between a closed and an expanded state, - characterised in that the expansion device (30), containing a single drive, is configured to carry out the change in the lateral extension and the vertical distance in two movement courses which are independent of one another and freely definable and coded in the placeholder, but by means of this single drive, by means of operation of always the same adjusting element, wherein the coding of the movement courses in the placeholder (10) is achieved by free-form surfaces as three-dimensional sliding surfaces or guide sliding surfaces on the inner sides or edges of the upper (20) and lower (22) supports, on spacer elements used inside and serving as sliding surfaces, in elongated holes used as sliding holes with freely determinable shape or in rotatable structures with different tooth spacing.

2. Placeholder according to claim 1, whose expansion device (30) remains inside a volume spanned by the upper (21) and lower support surfaces (23) both in the closed and in the expanded state.

3. Placeholder according to claim 1 or 2, characterised in that the first (21-1, 23-1) as well as the second sub-surface (21-2, 23-2) of the upper (21) as well as the lower support surface (23) comprise an interengaging structure (26) on the edge (24-1, 24-2, 25-1, 25 -1), at which they touch in the closed state, which is designed in such a way that, in the event of an expansion, it permits a lateral drifting apart of the first (21-1, 23-1) and second sub-surfaces (21-2, 23-2), and, in the expanded state, a lateral gap (27) running perpendicular to the direction of the lateral drifting apart through the upper (21) and the lower support surface (23) has a gap width (55), which is smaller than the maximum drift amount (54) and bigger or equal zero.

4. Placeholder according to claim 3, the upper (20) and the lower support (22) of which are shaped in such a way that, during the lateral drifting part, the interengaging structure (26) of the first sub-surface (21 -1, 23-1) slides mounted on a support structure (44) in the part of the support (20, 22) associated with the second sub-surface (21-2, 23-2) and the interengaging structure (26) of the second sub-surface (21-2, 23-2) slides mounted on a support structure (44) in the part of the support (20, 22) associated with the first sub-surface (21-1, 23-1).

5. Placeholder (10) according to any one of claims 1 to 4, wherein the expansion device (30) for setting the placeholder (10) between the closed and the expanded state contains a screw spindle (31) with a screw head (32), by means of which the change in the lateral extension as well as the vertical distance can be controlled.

6. Placeholder (10) according to claim 5, which has no symmetries along an axis, which runs parallel to the axis of the screw spindle (31), in any lateral cutting plane.

7. Placeholder (10) according to claim 5 or 6, the expansion device (30) of which further comprises a movable spacer element (34), - which is mounted in a position on the spacer element (34) so as to be laterally rotatable about a movable axis (36), which can be displaced along the screw spindle (31) by means of a threaded nut (35) which is integrated into the movable axis (36) and runs on a thread (33) of the screw spindle (31), wherein the movable axis (36) is arranged running directly or indirectly in an upper elongated hole (38) in the first sub-surface (21-1) of the upper support (20) and in a lower elongated hole (39) in the first sub-surface (23-1) of the lower support (22), - which is further laterally rotatable about a fixed axis (37), which is mounted in the second sub-surface (21-2) of the upper support (20) and in the second sub-surface (23-2) of the lower support (22) in a laterally positionally invariable manner, and - which is mounted on a first and / or a second end in a freely sliding manner on an upper three-dimensional sliding surface (40) below the first (21-1) and / or the second sub-surface (21-2) of the upper support (20) and on a lower three-dimensional sliding surface (41) above the first (23-1) and / or the second sub-surface (23-2) of the lower support (22), wherein the upper three-dimensional sliding surface (40) and the lower three-dimensional sliding surface (41) are shaped with respect to one another such that the first and / or second end of the spacer element (34) assumes a defined position on the upper (40) as well as on the lower three-dimensional sliding surface (41) for each angle of rotation of the spacer element (34) about the fixed axis (37), the absolute position of which and the corresponding position of the movable axis (36) in the correspondingly shaped elongated holes (38, 39) determines the lateral extension of the placeholder (10) and the distance of which between the upper (40) and the lower three-dimensional sliding surface (41) from each other in the closed state determines the height of the placeholder (10).

8. Placeholder (10) according to claim 5 or 6, the expansion device (30) of which further comprises a movable spacer element (34), - which can be moved along the screw spindle (31) and has four guide elements (42), which are in each case displaceable in a first upper elongated hole and / or below a first upper guide sliding surface (38) in the first sub-surface (21-1) and in a second upper elongated hole and / or below a second upper guide sliding surface (38) of the second sub-surface (21-2) of the upper support (20) and in a first lower elongated hole and / or on a first lower guide sliding surface (39) of the first sub-surface (23-1) and in a second lower elongated hole and / or on a second lower guide sliding surface (39) of the second sub-surface (23-2) of the lower support (22), - wherein the spacer element (34) comprises upper and lower, preferably three-dimensional, sliding surfaces (40,41), and - wherein the upper sliding surface (40) and the lower sliding surface (41) on the spacer element (34) are shaped in respect to one another, and the elongated holes and / or guide sliding surfaces (38, 39) are shaped and arranged in each of the sub-surfaces of the upper and lower supports in such a way that, for a defined position, which the spacer element (34) assumes on the screw spindle (31), the corresponding position of the guide elements (42) in the correspondingly shaped elongated holes and / or guide sliding surfaces (38, 39) determines the lateral extension of the placeholder (10) and the distance of which between the upper (40) and lower sliding surfaces (41) from one another on the spacer element (34) at a touching edge (43) and / or at a position of the upper (38) and lower guide sliding surfaces (39) of the upper (20) and of the lower support (22), associated with the position of the spacer element (34), determines the height of the placeholder (10).

9. Placeholder (10) according to claim 5 or 6, the expansion device (30) of which further comprises a movable double pair of spacer elements (34-11, 34-12), - which is mounted in a position on each spacer element (34-11, 34-12) of the double pair in each case in a laterally rotatable manner about a movable axis (36-11, 36-12), wherein the movable axes (36-11, 36-12) are arranged on a threaded nut (35), and can be displaced along the screw spindle (31) by means of the threaded nut (35) running on a thread (33) of the screw spindle (31), - wherein the first spacer element (34-11) of the double pair is laterally rotatable about a fixed axis (37), which is mounted in the first sub-surface (21-1) of the upper support (20) and in the first sub-surface (23-1) of the lower support (22) in a laterally positionally invariable manner, and the second spacer element (34-12) of the double pair is laterally rotatable about a fixed axis (37), which is mounted in the second sub-surface (21-2) of the upper support (20) and in the second sub-surface (23-2) of the lower support (22) in a laterally positionally invariable manner, and - wherein the threaded nut (35) running on the thread (33) of the screw spindle (31) is designed in such a way that it comprises sliding surfaces (40, 41) or a double toggle lever structure (57) for the first (21 -1) and second sub-surfaces (21 -2) of the upper support (20) and for the first (23-1) and second sub-surfaces (23-2) of the lower support (22), which are mounted in a freely sliding manner on guide sliding surfaces (38) of the first (21-1) and second sub-surfaces (21 -2) of the upper support (20) and on guide sliding surfaces (39) of the first (23-1) and second sub-surfaces (23 -2) of the lower support (22), - and the angular position between the first spacer element (34-11) and the second spacer element (34-12) determines the lateral extension of the placeholder (10) and a distance of the upper (40) and lower sliding surface (41) relative to one another or a position of the double toggle lever structure (57) at a touching edge (43) and / or at a position of the upper (38) and lower guide sliding surfaces (39) of the upper (20) and of the lower support (22) associated with the position of the threaded nut (35) determines the height of the placeholder (10).

10. Placeholder (10) according to any one of claims 7 to 9, wherein the screw spindle (31) comprises a thread (33) on its second half (31-2), which runs in the opposite direction to a thread (33) on the first half (31-1) of the screw spindle (31), and the expansion device (30) comprises a first spacer element (34-1) or a first double pair of spacer elements, which uses the first half (31-1 ) of the screw spindle, and a second spacer element (34-2) or a second double pair of spacer elements, which uses the second half (31-2) of the screw spindle (31), wherein first (40-1, 41-1) or second upper and lower three-dimensional sliding surfaces (40-2, 41-2) and corresponding upper (38-1, 38-2) and lower elongated holes (39-1, 39-2) and / or guide sliding surfaces are associated with first (34-1) and second spacer element or double pair of spacer elements (34-2).

11. Placeholder (10) according to any one of claims 7 to 10, having a first and a second spacer element or double pair of spacer elements, wherein the first (34-1) and the second spacer element (34-2) or double pair of spacer elements are designed and arranged working in a mirror-inverted manner with respect to one another, or wherein the first (34-1) and the second spacer element (34-2) or double pair of spacer elements are designed and arranged working in opposite directions to one another.

12. Placeholder (10) according to claim 10 or 11, the screw spindle (31) of which comprises a guide structure (45) between the first (31-1) and the second half (31-2) and / or between the first (34-1) and the second spacer element (34-2) or double pair of spacer elements, which is mounted in a retaining element (46) so as to be rotatable but laterally not displaceable in its position, wherein the retaining element (46) is mounted movably, in particular vertically movably, but in turn is laterally not displaceable in its position in the upper support (20) and in the lower support (22).

13. Placeholder (10) according to any one of claims 7 to 12, wherein the shape and position of the three-dimensional sliding surfaces (40-1, 40-2, 41-2, 41-2) and the shape and position of the elongated hole (38-1, 38-2, 39-1, 39-2) and / or the guide sliding surfaces are designed according to an individually required expansion behaviour.

14. Placeholder (10) according to any one of claims 1 to 13, which, in a top view, has a kidney-shaped form.

15. Placeholder (10) according to any one of claims 1 to 14, which has a minimum height (50) of greater than or equal to 7 mm in the closed state and a maximum height (51) of less than or equal to 14 mm in the expanded state and a lateral extension (52, 53) of greater than or equal to 13 mm in the closed state.