WO2010136860A1 - A toolkit for implanting a vertebral support - Google Patents

Abstract

A toolkit for easily implanting a vertebral support device, in particular an interlaminar prosthesis, through a minimally invasive surgical access. In an exemplary embodiment, the toolkit comprises a vertebral distractor (10) that has a means for creating and maintaining a predetermined distraction between two adjacent vertebrae (21a/b), and a means for maintaining the edges 29' and 29" of a minimally invasive approach tissue cut (29) at an open position, thus stabilizing it against elastic return of the tissues (20). In a preferred exemplary embodiment, a distractor is used which comprises a couple (30) of levers (31a/b), that are movable about a hinge (15) and that can be locked at a predetermined position, and whose end have a couple of distraction portions (33a/b) adapted to be inserted between spinous processes (23a/b), such that by spreading apart levers (31a/b) the distraction of the two vertebrae (21a/b) can be obtained.

Description

TITLE A TOOLKIT FOR IMPLANTING A VERTEBRAL SUPPORT

DESCRIPTION Field of the invention The present invention relates to a toolkit for implanting a prosthesis, in particular an intervertebral support device, for example an interlaminar or an interspinous vertebral support device. The toolkit is adapted to apply an implant by a minimally invasive approach.

Background of the invention Discal diseases are known which cause a reduction of the intervertebral space, and therefore cause pain and other troubles to the patients. Many types of prostheses or vertebral support devices are also known for maintaining an adequate distance between adjacent vertebrae, without excessively limiting the loss of spinal mobility. In particular, interspinous support devices are arranged between the spinous processes of the vertebrae, whereas interlaminar support devices are placed within a space between the laminae of the two vertebrae.

For example, Fig. 1 and 2 show an interlaminar prosthesis 1 that is also described in WO2004/084743 and in WO2005/044118, and comprises: - a front portion 11 to be located into a space between the laminae 22a/b of two adjacent vertebrae 21a/b, to reduce intervertebral stress on a disc 26; - a rear portion 12, which is arranged for most of its extension between the spinous processes 23a/b; the rear portion has an upper face 13 that is adapted to firmly engage with the junction 27 between laminae 22a and spinous processes 23a of upper vertebra 21a, in order to provide a suitable anatomical gap between the vertebrae, i.e. in order to space vertebrae 21a/b by actuating the spinous processes. The support device is made of a material that is adapted to locally ensure spinal mobility.

Prosthesis 1 is effective only if it is pushed as forward as possible inside interlaminar space 24. However, if it approaches the spinal channel too closely, nervous tissue 25 could be damaged, which makes it critical to implant prosthesis 1.

Before implanting either an interlaminar or an interspinous vertebral support device between two adjacent vertebrae 21a/b, a distraction of respective spinous processes 23a/b must be carried out, overcoming the return forces that are exerted by the ligaments 26 and by other neighbouring tissues. Intervertebral distraction devices are known that are bulky instruments, and make it difficult an access and visibility of the interspinous space 28, through which the support device must be inserted, and of the recess 24-28 where the support device must be located. Furthermore, an operation carried out with such known distraction devices is particularly invasive. A vertebral distraction device of this kind is disclosed in WO2007/085909.

The region of the spinous processes in which vertebral distraction force has to be exerted must be chosen such that the two adjacent vertebrae

21a/b translate with respect to each other during the distraction a movement, whereas the two adjacent vertebrae must be prevented from rotating with respect to each other. The rotation would cause, in fact, a further compression of disc 26 front portion. For this reason, the jaws of a vertebral distraction device must be applied in a position as anterior as possible of the spinous processes 23a/b.

Furthermore, the known intervertebral distraction devices are arranged in a central region of interspinous space 28, therefore a too small space of manoeuvre is left, which complicates the introduction of the interlaminar prosthesis.

Furthermore, the skin and the muscular tissue that surrounds the access aperture tend to return to its starting position, which makes it even more difficult to create a minimally invasive access to the intervertebral recess.

US2002165550 relates to an implant for introduction into a disc space between two vertebrae, as well as to a technique and to a toolkit to provide a fusion of such vertebrae. The toolkit comprises a tool having a shaped insert that can be put into an intervertebral space for testing whether sufficient amount of material has been removed from the intervertebral space in order to insert the implant. The shaped inserts may have various sizes for assisting the surgeon to choose the correct sizes of the implant.

WO2006/135889 relates to interspinous implants, as well as to systems and toolkits that include such implants, and to procedures to apply such implants. In particular, a distraction device is described for spacing apart or distracting the spinous processes of two adjacent vertebrae before applying the implant, comprising a couple of levers that have a means for assisting a measurable and/or fine distraction. A gauge device is also described for measuring the interspinous space before introducing the implant, to properly select implant size. The gauge device comprises longitudinal indentations or markers on at least one central portion, which can be viewed under fluoroscopy. Furthermore, the gauge device allows determining up to which rate the distraction has to be made.

Summary of the invention It is therefore a feature of the present invention to provide a toolkit for implanting a vertebral support device, such as an interlaminar or an interspinous support device, which allows creating and maintaining a vertebral distraction, and at the same time allows a thorough visibility and an easy access of the interlaminar space in which the prosthesis has to be implanted. It is, furthermore, a feature of the present invention to provide such a toolkit, which is adapted to perform the implant by a minimally invasive approach whose size is less than that is required by prior art instruments.

It is also a feature of the present invention to provide a toolkit that comprises an instrument for maintaining the tissues that surround the minimally invasive approach aperture at an open position.

It is still a feature of the present invention to provide such a toolkit which allows removing a smaller amount of tissues with respect to what has to be removed with prior art instruments.

It is a particular feature of the present invention to provide such a toolkit for implanting an interlaminar vertebral support device of the type described in WO2004/084743 and in WO2005/044118 by a minimally invasive approach.

These and other features are achieved by a toolkit for implanting a vertebral support device in a space between two adjacent vertebrae of a patient, in particular by a minimally invasive approach, through a, incision that is defined by a first and a second cut edges facing the two adjacent vertebrae, the two adjacent vertebrae having an interspinous space, which is defined by respective spinous processes of the two adjacent vertebrae, wherein the toolkit comprises a vertebral distractor for causing and/or maintaining a predetermined vertebral distraction of the two adjacent vertebrae, the vertebral distractor comprising: a couple of mutually rotatably hinged levers, the levers being rotatable with respect to each other between a first, i.e. approached position, and a second, i.e. spaced-apart position; the levers having respective distraction portions in use adapted to engage with the spinous processes to distract them until a predetermined distraction is reached;

- a distraction means for moving the levers between the first and second position, and for causing, in use, the vertebral distraction; - first and second retraction means adapted to keep the edges in a mutually spaced-apart position, whose main feature is that the first retraction means is adapted to keep one of the edges in an open position and comprises respective retraction portions of the levers, and that said second retraction means is adapted to keep the other of the edges at an open position and comprise a reverse pliers that is provided with:

- a first load arm that has an embracing portion adapted to engage with a embracing portion of one of the levers; a second load arm that has a retraction portion, such that, by actuating the reverse pliers, the first and second retraction means shift from a closed position to a spread-apart position to cause, in use, the edges to open, whereas the distraction portions keep the spinous processes at a spaced-apart position.

This way, after a minimally invasive approach has been made, the skin, the muscular tissue, the ligaments, and other tissues, are prevented from elastically return to their original position, which would hinder the passage of the prosthesis and of the instruments for implanting the prosthesis.

In particular, the retraction portions of the levers and the retraction portion of the reverse pliers maintain open the aperture between the tissues, and create a tubular entrance channel to the interspinous space to allow positioning the prosthesis up to an interlaminar position, whereas the distraction portions maintains the spinous processes in a spaced-apart state.

Preferably, the embracing portion is a groove that is made in a seat of the threaded hole and/or in a seat that is integral to the other lever.

The embracing portion of one of the levers is adapted to engage with the embracing portion of the first load arm by a joint selected from the group comprised of:

- a prismatic joint; - a prismatic joint that is associated with a means that is adapted to prevent the embracing portion of one of the levers and the first load arm from longitudinally sliding with respect to each other when the reverse pliers is in a spaced-apart position, preferably a rack;

- a hinge; - a fixed joint;

- a combination thereof.

In particular the retraction portions of the levers and the retraction portion of the second load arm extend along respective curved surfaces, in particular along respective cylindrical surfaces, such that the retraction portion of the second load arm and the retraction portions of the levers cooperate to form a substantially tubular introduction space for the prosthesis. This way, it is ensured that also minimally invasive, minimum size passageways are and remain accessible.

Advantageously, said vertebral distractor comprises a reversible and self- locking means for maintaining the predetermined distraction of the spinous processes.

Advantageously, the distraction means for causing and/or maintaining the vertebral distraction comprise a couple of teeth that respectively extend from the retraction portions of the levers, the teeth adapted to be inserted into the interspinous space according to a direction that is substantially parallel to the mid-sagittal plane of the patient. In particular, the teeth have respective oppositely convex portions.

Advantageously, said levers have respective intermediate portions at an angle greater than 45° with respect to the first retraction means, such that the intermediate portions extend along a plane at an angle with respect to the mid- sagittal plane of the patient and a thorough visibility and access to the space between the two adjacent vertebrae is provided to an operator. This way, a prosthesis introduction passageway is available that is wider than the passageways obtainable by the prior art distraction devices, in order to assist better the work of the surgeon and to achieve a safer operation.

Preferably, the angle between the plane, along which the intermediate portions extend, and the first retraction means is greater than 75°; in particular this angle is a substantially right angle. The width of the passageway, which is allowed by the vertebral distractor according to the invention, makes it possible to exploit at best an experimentally observed synergistic effect that exists between the compression exerted by the spinous processes against the prosthesis, when it is implanted, and the inwardly directed pneumatic forces caused by the spine movements. Such synergistic effect assists properly the application of the prosthesis, so that the nervous tissue within the spinal channel is less likely to be damaged.

In particular, the distraction means for moving the levers between the first and second position, and the reversible and self-locking means comprise a threaded rod that engages: a through threaded hole that is made at one of the levers, in particular the threaded hole made through a housing that is rotatably arranged about an axis, said axis perpendicular to the plane in which the levers extend; - a housing that is integral to the other lever, the housing being selected from the group comprised of:

- a further threaded hole adapted to engage with the threaded rod;

- a blind hole that presents an abutment surface to a distal end of the threaded rod;

In particular, a manoeuvre portion is provided at one end of the threaded rod. Advantageously, said teeth have such a position and such a shape that the teeth engage respective regions of the spinous processes proximate to the transition zones between the spinous processes and respective laminae of the adjacent vertebrae, whereby the movement of the adjacent vertebrae, which takes place during the distraction of the adjacent vertebrae, is a substantially translational relative movement. This way, a further compression of the front portions of the disc between the two vertebrae is prevented, i.e. of the portion of the disc opposite to the spinous processes with respect to the sagittal mid- plane of the patient. Advantageously, the reverse pliers comprises a reversible block means for blocking it in a spaced-apart position. The block means comprises preferably:

- a toothed member integrally arranged at a load arm of the reverse pliers;

- a blocking tooth integral with a rotatable block element whose rotation axis is integral to the other load arm of the reverse pliers.

Preferably, the load arms comprise respective gripping portions that are shaped like scissor finger bows.

According to another aspect of the invention, a toolkit is provided for implanting a vertebral support device in a space between two adjacent vertebrae of a patient, the two adjacent vertebrae having an interspinous space, which is defined by respective spinous processes of the two adjacent vertebrae, the toolkit comprising:

- a vertebral distractor comprising: a couple of distraction elements adapted to be inserted into the interspinous space; a means for bringing the distraction elements from an introduction mutual distance to a distraction mutual distance that is greater than the introduction mutual distance, and vice-versa, such that a predetermined vertebral distraction is created between the spinous processes of the two adjacent vertebrae by bringing the distraction elements to the distraction mutual distance; the main feature of this toolkit is that it comprises, furthermore, an interspinous spacer that has a spacer portion adapted to be inserted between the spinous processes when the vertebral distraction has been created between the two adjacent vertebrae, the interspinous spacer having a nominal size that corresponds to a distance between the spinous processes.

This way, the distraction is maintained even after the distraction elements of the couple have been extracted from the interspinous space. The interspinous vertebral spacer is mounted before removing the vertebral distractor, by means of which the vertebral distraction has been previously created. In other words, the invention provides a tool that has the sole function of maintaining the vertebral distraction, which is distinct from the instrument that creates the vertebral distraction. The convex portion of this cross section is preferably a conical cross section, in particular it may be selected from the group comprised of: an elliptic arc; a parabolic arc. In this case, the interspinous vertebral spacer may comprise a rod that serves as a handle, and is substantially parallel to the convex surface of the monoaxially bent portion.

The vertebral spacer can be arranged in a peripheral position between the spinous processes. This way, once the vertebral distractor has been removed, a prosthesis introduction passageway remains available, said passageway wider than if the vertebral distractor were left in its own position, which assists the work of the surgeon and provides for a safer operation.

Furthermore, the interspinous vertebral spacer according to the invention is much less cumbersome than the prior art distraction devices. Once inserted between the spinous processes after adjacent vertebral distraction, the vertebral spacer enables the surgeon to withdraw the vertebral distractor; this way a more thorough visibility and an easier access is obtained to the implant region.

As previously described, the vertebral distractor is mounted between the spinous processes in such a position that the relative movement of the adjacent vertebrae during the distraction is substantially a translational movement. If the vertebral spacer were located at a peripheral position of the interspinous space, upon removal of the vertebral distractor the region where the distracting force is exerted would move towards this peripheral position, which would create a bending moment. However, the system consisting of an intervertebral disk and two adjacent vertebrae has a viscoelastic behaviour, and the prosthesis is implanted in a relatively short time, whereby the vertebrae do not have time enough to appreciably rotate and to further compress the front portion of the disc. In other words, after removal of the vertebral distractor, the relative position of the vertebrae changes very slowly, and no significant relative rotation takes place during the time that is needed for implanting the prosthesis between the adjacent vertebrae.

Preferably, the vertebral distractor has the shape of a reverse pliers, which comprises: - a couple of reciprocally hinged levers;

- a couple of teeth that are integral to respective ends of respective load arms, the couple of teeth adapted to be inserted into the interspinous space; a reversible block means of a relative position of the two levers.

In particular, the spacer portion is a monoaxially bent spacer portion, comprising: a couple of substantially planar support device elements, each support device element having a support device surface to provide a support device to a respective spinous process of a respective adjacent vertebra, the support device surfaces having a mutual distance responsive to the nominal size, - a convex introduction end, the introduction end providing a radius between said walls support device elements of the couple.

Advantageously, the toolkit comprises a plurality of interspinous spacers of different nominal sizes.

Preferably, the nominal size is selected from the group comprised of: 8, 10, 12, 14 and 16 mm. Such sizes fit the dimension of the interspinous space of patients of any size and age.

The toolkit can comprise furthermore, surgical tools selected from the group comprised of:

- a pincers for removing a ligament; - a measuring device for measuring the interlaminar space, preferably comprising a plurality of gauges associated with a gauge placing means for placing the gauges within the interlaminar housing, preferably comprising a rod that has an end adapted to engage with a housing of said gauges; a gripper for application of the prosthesis; - a tapping means for compressing the prosthesis into the interlaminar recess, said tapping means preferably comprising one or more rods in use connected to an end portion that conformed according to a face exposed in use at the rear portion of the prosthesis;

- a synthetic ligament; - a guiding means for the synthetic ligament;

- a combination of the above surgical instruments.

In particular, in case of lumbar applications, the gauges have nominal size selected from the group comprised of: 8, 10, 12, 14 and 16 mm. Such gauges allow to suitably select the size of the prosthesis to be implanted.

The synthetic ligament is used for provide a plastic replacement of the supraspinous fibrous complex (supraspinous plastic or augmentetion) that it is necessary if, after the implant, the superspinous ligament and the articular capsule allow an excessive local spinal mobility, which is a possible cause of micro-instability and/or of kyphotization of the spine where the operation is effected.

Brief description of the drawings

The invention will be made clearer with the following description of exemplary embodiments thereof, exemplifying but not limitative, with reference to the attached drawings wherein: figure 1 is a perspective view of the interlaminar vertebral support device described in PCT WO2005/044118;

- figure 2 shows a cross sectional view of an implant of the above prosthesis between two lumbar vertebrae; - figure 3 is a perspective view of a vertebral distractor according to the invention, comprising a couple of levers for distracting two adjacent vertebrae and a reverse pliers for keeping the tissues surrounding a minimally invasive approach at an open position;

- figures 4, 5, 6 show three steps of a minimally invasive approach for implanting an interlaminar prosthesis, by means of the device of Fig. 3; figure 7 shows a conventional interspinous vertebral distractor; figure 8 shows an interspinous vertebral spacer that comprises a fixed vertebral spacing element, according to the invention, which can be used in association with the vertebral distractor of Fig. 7; - figure 9 shows a Rongeur gripper for removing the interspinous ligament and for creating a subligamentous interspinous recess;

- figures 10A and 10B show a gauge for measuring the height of the interlaminar space; - figure 12 shows a device for pushing the prosthesis into the interlaminar housing;

- figure 13 shows a couple of devices for guiding a synthetic ligament that serves for maintaining the prosthesis in its position. Description of preferred exemplary embodiments

With reference to Figs. 3 and 5, a vertebral distractor 10 is described that belongs to a toolkit for implanting a vertebral support device according to the invention; in particular distractor 10 is adapted to implant an interspinous intervertebral support device by a minimally invasive approach 29 into the body 50 of a patient, through an incision of a tissue 20. Vertebral distractor 10 has a portion 30 that comprises a couple of levers 31a/b, which are reciprocally constrained by a hinge 15 and comprise retraction portions 32a/b arranged at respective ends. Preferably curved and convex opposite respective distraction teeth 33a/b extend from ends 32a/b. Couple 30 of levers is adapted to cause a vertebral distraction of two adjacent vertebrae (Fig. 2 21a, 21b), whose spinous processes 23a/b are shown in Fig. 4. Distraction teeth 33a/b are adapted to be inserted between spinous processes 23a/b, when couple 30 of levers of vertebral distractor 10 is closed (Fig. 4). In order to open/close couple 30 of levers, i.e. in order to adjust the angle between levers 31a/b about hinge 15, thus controlling the vertebral distraction, a screw threaded rod 34 is provided which engages two threaded holes 35a/b of respective housings 36a/b integral to respective levers 31a/b. Hole 35a is a through hole, and housing 36a can preferably rotate about an axis that is perpendicular to the plane along which the two levers extend; hole 35b is a blind hole and offers an abutment surface to one end of threaded rod 34. A manoeuvre head 38, which is integral with the opposite end of threaded rod 34, allows rotating rod 34, which causes a self-locking relative rotation of threaded rod 34 and housing 36 and, therefore, causes couple of levers 30 of vertebral distractor 10 to close or open. When couple of levers 30 is in use, the plane where intermediate portions 37a/b extend is at an angle with respect to the mid-sagittal plane of the patient, in this case, it is at a right angle. This way, the visibility and the access to interlaminar space 24 (Fig. 2) are not hindered. As shown in Figs. 5 and 6, in order to retract and to maintain open the tissues that form or are adjacent to edges 29', 29" of a minimally invasive approach incision 29, in particular the skin and the muscular tissue, couple of levers 30 is associated with a reverse pliers 40, which is shown in more detail in Fig. 3, and is described below. The combination of couple of levers 30 and of reverse pliers 40 forms distractor 10 of the toolkit according to the invention. Reverse pliers 40 comprises two load arms 41a/b that are constrained to each other by means of a hinge 44. Load arm 41a is adapted to engage with two corrugated grooves 39a/b that are provided externally at housings 36a/b of two levers 31a/b (Fig. 3). In particular, a longitudinal sliding of load arm 41a of reverse pliers 40 with respect to couple 30 of levers is hindered (Figs. 5 and 6) by engagement of a rack arm 42 with corresponding engagement teeth of corrugated grooves 39a/b, not shown. At the end of the other load arm, 41b, a retraction portion 43 is arranged which, in an exemplary embodiment described herein, can rotate about an axis perpendicular to the plane where arms 41a/b extend, owing to a hinge 51.

Retraction portion 43 has a concave side that is adapted to face retraction portions 32a/b, which also have a concave portion that correspondingly is adapted to face retraction portion 43, as well as it has a convex side that, in use, is adapted to push against edge 29", and similarly retraction portions 32a/b have a convex portion that, in use, is adapted to push against edge 29" of minimally invasive approach 29 (Figs. 5 and 6), which has been obtained made by incision of tissue 20. By opening reverse pliers 40, edge 29" is spaced apart from edge 29' and brought and/or maintained in an open position (Fig. 6) by retraction portion 43. At the same time, retraction portions 32a/b maintain edge 29' in its actual position, at the height of spinous processes 23a, b.

Reverse pliers 40 comprises also load arms 45a/b whose handgrip is preferably shaped like scissor finger bows; load arm 45a has, furthermore, a protruding toothed part 47 that faces load arm 45b. Teeth 53 of the protruding part can engage a locking tooth 48 for reversibly locking gripper 40 in a prefixed position. This is possible since locking tooth 48 is the end of a lever 49 that is pivotally arranged about an axis integral to load arm 41b. In an alternative embodiment, load arm 41a could be locked against one of the two levers of couple 30 of levers by a hinge or a fixed joint. In this case, couple 30 of levers and reverse pliers 40 of vertebral distractor 10 of the toolkit according to the invention would be integral to each other. Intermediate portions 37a/b of levers 31a/b (Fig. 3) are connected to retraction portions 32a/b that in turn support device teeth 33a/b. Retraction portions 32a/b extend along semi cylindrical and convexly opposed surfaces to retraction portion 43 of reverse pliers 40. Therefore, retraction portion 43 and retraction portions 32a/b, in a maximum mutually spaced-apart position form a tubular channel for introducing the prosthesis by means of suitable instruments, as described hereinafter.

In the closed position, retraction portion 43 can be contained between retraction portions 32a/b, thus achieving a compact size, that is ideal for use for introduction into minimally invasive approach incision 29. With reference to Fig. 7, according to another aspect, a conventional type interspinous vertebral distractor 80 is described that comprises two levers 81a/b that are hinged at a fulcrum 82, and are provided with a couple of teeth- shaped distraction elements 83a/b at respective ends, which are therefore adapted to be inserted into space 28 between spinous processes 23a/b (Fig. 2) to cause a predetermined vertebral distraction. The vertebral distraction is applied by a toothed block that is provided with a slide 85 that is slidingly arranged with slack within a longitudinal groove 86 of a load arm 87b of lever 81b; a tooth 79 of slide 85 can engage in a lock position a rod 89 that is transversally arranged within groove 86. The opposite end of slide 85 is connected via a hinge 88 to load arm 87a of lever 81a; slide 85 can be unlocked by rotating the slide about hinge 88. Interspinous vertebral distractor 80 comprises also a couple of springs 78 that are arranged between load arms 84a/b of levers 81a/b and tend to close levers 81a/b.

With reference to Fig. 8, a vertebral spacer 90 according to the invention is described, which comprises a spacer portion 91 that is adapted to be introduced between spinous processes 23a/b when adjacent vertebrae 21a/b have to be distracted. Interspinous spacer 90 has a nominal size 99 that corresponds to the distance between spinous processes 23a/b when interspinous spacer 90 engages with two spinous processes 23a/b. In the represented embodiment, spacer portion 91 is axially bent, and comprises a couple of substantially plane and mutually parallel support elements 93a/b, each having a support surface 97a/b that supports a respective spinous process 23a/b of a respective adjacent vertebra 21a/b when interspinous spacer 90 is arranged between two spinous processes 23a/b. Distance 99 between support device surfaces 97a/b defines the nominal size of interspinous spacer 90.

A convex introduction end 92 works as a connection member between support elements 93a/b and assists the introduction of spacer portion 91 between spinous processes 23a/b. This convex end comprises an arch that subtends an angle that is smaller than 180°. The opposite end of spacer portion 91 is integral to a handle 95, for example by a welded connection. Handle 95 consists of a cylindrical rod that has a handgrip 96 that comprises a rubber hollow cylinder, and is therefore adapted to be forced about an end portion of the handle, thus obtaining a connection that avoids mutual rotation and translation in normal use conditions of interspinous vertebral spacer 90.

The toolkit comprises preferably five interspinous spacers whose nominal sizes are 8, 10, 12, 14 and 16 mm.

Fig. 9 shows a conventional rounger or rongeur-type pincers for removing a ligament, which belongs to the toolkit according to the invention.

Before implanting the interlaminar prosthesis, a step of measuring the target interlaminar space is provided. The measurement is carried out by placing into the interlaminar space one or more gauges, for examples gauges 120 of Fig. 10A, which have preferably respective nominal sizes of 8, 10, 12, 14, 16 mm, corresponding to respective interlaminar prosthesis sizes. Gauge 120 is brought into the interlaminar region by a rod 121 , as shown in Fig. 10B, which has a manoeuvre end equipped with a handgrip 122, and an opposite threaded end 123 adapted to engage with a threaded blind hole 124 of gauge 120. A first trial arrangement of the prosthesis within the interlaminar housing is carried out by means of the gripper by application 130, which consists of two levers 131a/b that are connected by a hinge 135. Gripping ends 132a/b of levers 131a/b are a conformation suitable for holding an interlaminar prosthesis, in particular the prosthesis which is disclosed in WO2004/084743 and in WO2005/044118 (Figs. 1 and 2). A reversible lock means is provided for reversibly locking the gripper by application 130 at a predetermined opening, that comprises a branch 132 of lever 131a that faces lever 131b, and has a toothed surface 133 whose teeth can engage a surface of lever 131b, thus mutually blocking two levers 131 a/1 b; the block can be removed carrying out on manoeuvre portions 134a/4b.

Once the interlaminar prosthesis has been placed within the interlaminar housing 24 (Fig. 2), the interlaminar prosthesis is compressed and pushed forward by means of a pushing device 140, which is shown in Fig. 12. Device 140 has a handle 141 , which is provided with a handgrip 142 for holding the device, by means of a soft surface layer made of a material, such as rubber, and/or by means of a knurled surface. A tool extends from an end 143 of the handle, and comprises a rectilinear stem 144 and a portion 145 that has a shape which fits the rear face of the interlaminar support device, in particular of the prosthesis that is disclosed in WO2004/084743 and in WO2005/044118 (Figs. 1 and 2).

With reference to Fig. 1 ,3, a couple of devices is described for guiding an artificial ligament (indicated as 27 in Fig. 2), which serves for keeping prosthesis 1 in its position. Each guiding device has a handle 151 , with a handgrip for holding the device, by a surface layer of soft material, such as rubber, and/or a knurled surface. A tool, which comprises a straight stem 153 and a right-handed helix 154a or a left-handed helix 154b, extends from an end 152 of the handle.

The foregoing description of specific embodiments of the toolkit according to the invention, and of its mode of use will so fully reveal the invention according to the conceptual point of view, so that others, by using the prior art, will be able to modify and/or adapt for various applications such embodiments without further research and without parting from the invention, and it is therefore to be understood that such adaptations and modifications will have to be considered as equivalent to an exemplary specific embodiment. The means and the materials to realise the different functions described herein could have a different nature without, for this reason, departing from the field of the invention. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation.

Claims

1. A toolkit for implanting a vertebral support device (1) in a space (24,28) between two adjacent vertebrae (21a/b) of a patient, in particular by a minimally invasive approach, through an incision (29) that is defined by a first and a second cut (20) edges (29', 29") facing said two adjacent vertebrae (21a/b), said two adjacent vertebrae having an interspinous space (28), which is defined by respective spinous processes (23a/b) of said two adjacent vertebrae (21a/b), wherein said toolkit comprises a vertebral distractor (10) for causing and/or maintaining a predetermined vertebral distraction of said two adjacent vertebrae (21a/b), said vertebral distractor (10) comprising:

- a couple of mutually rotatably hinged levers (31 a, 31b), said levers being rotatable with respect to each other between a first, i.e. an approached position, and a second, i.e. a spaced-apart position; said levers having respective distraction portions (33a, 33b) in use adapted to engage with said spinous processes (23a,23b) to distract them until a predetermined distraction is reached;

- a distraction means (38,34,35a/b) for moving said levers (31a/b) between said first and said second position, and for causing, in use, said vertebral distraction;

- a first and a second retraction means (32a, 32b; 43) adapted to keep said edges (29', 29") in a mutually spaced-apart position, characterised in that said first retraction means is adapted to keep said first edge (29') in an open position and comprises respective retraction portions (32a, 32b) of said levers (31a/b), and in that said second retraction means is adapted to keep said second edge (29") at an open position and comprises a reverse pliers (40) that is provided with: - a first load arm (41a) that has an embracing portion (42) adapted to engage with an embracing portion (39a/b) of one of said levers (31a/b); a second load arm (41b) that has a retraction portion (43), such that, by actuating said reverse pliers (40), said first and said second retraction means (43; 32a, 32b) shift from a closed position to a spread- apart position to cause said edges (29'.29"), in use, to open, whereas the distraction portions (33a/b) keep the spinous processes (23a/b) at a spaced-apart position.

2. A toolkit according to claim 1 , wherein said embracing portion (39a/b) of one of said levers (31a/b) is adapted to engage with said embracing portion (42) of said first load arm (41a) by a joint selected from the group comprised of: - a prismatic joint;

- a prismatic joint that is associated with a means (42), in particular a rack, that is adapted to prevent said embracing portion (39a/b) of one of said levers (31a/b) and said first load arm (41a) from longitudinally sliding with respect to each other when said reverse pliers (40) is in a spaced- apart position;

- a hinge;

- a fixed joint;

- a combination thereof.

3. A toolkit according to claim 1 , wherein said retraction portions (32a/b) of said levers (31a/b) and said retraction portion (43) extend along , respective curved surfaces, in particular along respective cylindrical surfaces, such that said retraction portion (43) and said retraction portions (32a/b) of said levers (31a/b) cooperate to form a substantially tubular introduction space for said prosthesis (1).

4. A toolkit according to claim 1 , wherein said vertebral distractor (10) comprises a reversible and self-locking means (38, 34,35a/b, 36a, 36b) for maintaining said predetermined distraction of said spinous processes (23a/b).

5. A toolkit according to claim 1 , wherein said distraction means for causing and/or maintaining said vertebral distraction comprises a couple of teeth

(33a/b) that respectively extend from said retraction portions (32a,32b) of said levers (31a/b), said teeth (33a/b) adapted to be inserted into said interspinous space (28) according to a direction that is substantially parallel to the mid-sagittal plane of said patient, in particular said teeth (33a/b) having respective oppositely convex portions.

6. A toolkit according to claim 1 , wherein said levers (31a/b) have respective intermediate portions (37a/b) at an angle greater than 45° with respect to said first retraction means (32a, 32b), such that said intermediate portions (37a/b) extend along a plane at an angle with respect to the mid-sagittal plane of said patient and a thorough visibility and access to said space (24,28) between said two adjacent vertebrae (21a/b) is provided to an operator.

7. A toolkit according to claim 6, wherein said angle between said plane, along which said intermediate portions (37a/b) extend, and said first retraction means (32a, 32b) is greater than 75°, in particular said angle is a substantially right angle.

8. A toolkit according to claim 5, wherein said teeth (33a/b) have a position and a shape such that said teeth (33a/b) engage respective regions of said spinous processes (23a/b) proximate to the transition zones (27) between said spinous processes (23a/b) and respective laminae (22a/b) of said adjacent vertebrae (21a/b), whereby during said distraction of said adjacent vertebrae (21a/b), a substantially translational relative movement of said adjacent vertebrae (21a/b) takes place.

9. A toolkit for implanting a vertebral support device in a space between two adjacent vertebrae (21a/b) of a patient, said two adjacent vertebrae having an interspinous space (28), which is defined by respective spinous processes (23a/b) of said two adjacent vertebrae (21a/b), said toolkit comprising: - a vertebral distractor (80) comprising: a couple of distraction elements (83a/b) adapted to be inserted into said interspinous space (28); - a means for bringing said distraction elements (83a/b) from a introduction mutual distance to a distraction mutual distance that is greater than said introduction mutual distance, and vice-versa, such that a predetermined vertebral distraction is created between the spinous processes (23a/b) of said two adjacent vertebrae (21a/b) by bringing said distraction elements (83a/b) to said distraction mutual distance, characterised in that it comprises furthermore:

- an interspinous spacer (90) that has a spacer portion (91) adapted to be inserted between said spinous processes (23a/b) when said vertebral distraction has been created between said two adjacent vertebrae (21a/b), said interspinous spacer (90) having a nominal size (99) that corresponds to a distance between said spinous processes

(23a/b). such that said distraction is maintained after said distraction elements (83a/b) of said couple have been extracted from said interspinous space (28).

10. A toolkit according to claim 9, wherein said spacer portion (91) is a axially bent spacer portion, comprising: a couple of substantially planar support device elements (93a/b), each of said support device elements (93a/b) having a support device surface (97a/b) to provide a support device to a respective spinous process (23a/b) of a respective adjacent vertebra (21a/b), said support device surfaces (97a/b) having a mutual distance (99) responsive to said nominal size, a convex introduction end (92), said introduction end (92) providing a radius between said support device elements (93a/b) of said couple.

11. A toolkit according to claim 9, comprising a plurality of said interspinous spacers (90) each having a respective value of said nominal size (99).

12. A toolkit according to claim 9, wherein said nominal size (99) is selected from the group comprised of: 8, 10, 12, 14 and 16 mm.

13. A toolkit according to claims 1 or 9, comprising, furthermore, a surgical tool selected from the group comprised of:

- a gripper for removing a ligament (110); a measuring device for measuring the interlaminar space (24), in particular a measuring device comprising a plurality of gauges (120) that are associated with a gauge placing means for placing said gauges (120) within said interlaminar recess, in particular a gauge placing means comprising a rod (121) that has an end (122) adapted to engage with a housing (123) of said gauges, said gauges (120) having in particular nominal size selected from the group comprised of: 8, 10, 12, 14 and 16 mm; a gripper (130) for applying a prosthesis; - a push means (140) for compressing the prosthesis into the interlaminar housing (24), said push means comprising a proximal rod portion (141) and a distal head portion (142) that is adapted to engage with a face (12) of said prosthesis (1) that in use is exposed posteriorly;

- a synthetic ligament; - guiding means (150a, 150b) for said synthetic ligament;

- a combination of the above surgical instruments.