Interspinous device

Abstract

The invention relates to an interspinous device (1) for treating degenerative diseases of the spine, comprising a control shaft (3) and two retractor members (7a, 7b) arranged between two driving members (13a, 13b), said retractor members and driving members being movable along a longitudinal direction of the control shaft (3). Said device (1) further comprises a control member (11), apt to maintain said retractor members (7a, 7b) distanced from each other in the absence of loads, and two pairs of fins (17a, 17a') and (17b, 17b'). The fins comprise connecting means for connection to said driving members (13a, 13b) and said retractor members (7a, 7b), whereby the translation of the driving members and retractor members causes rotation and / or translation of said fins. By virtue of the cooperation between these elements forming the device (1), said fins can assume, by means of rotation of the control shaft (3), three different configurations.

Description

[0001] “Interspinous device” DESCRIPTION

[0002] Technical Field

[0003] The present invention relates to the field of intervertebral prostheses.

[0004] More particularly, the present invention relates to an interspinous device, i.e., a device that can be implanted, by means of surgery, between the spinous processes of a pair of adjacent, preferably lumbar, vertebrae.

[0005] Background Art

[0006] Interspinous devices are used to treat certain degenerative diseases of the spine, particularly those diseases involving the lumbar vertebrae.

[0007] Such prostheses are implanted in the space between the spinous processes of two adjacent vertebrae in order to keep the spinous processes at a predetermined distance.

[0008] This makes it possible to reduce the loads transmitted between adjacent vertebrae and, therefore, the loads to which the intervertebral disc is subjected, thereby relieving pain or other symptoms.

[0009] In addition, said interspinous devices can be used to facilitate the process of arthrodesis, which is the process of fusion of vertebral segments, in order to stabilize the movements of the spine.

[0010] Many of the interspinous devices currently used have shapes and sizes that make them suitable for implantation by minimally invasive percutaneous endoscopic surgery.

[0011] Interspinous devices currently known in the field comprise a main body, which is essentially cylindrical in shape, and two pairs of fins associated with the main body in such a way as to assume a first configuration of closing of the fins, in which the radial size of the device is minimal, and a second operating configuration in which the fins are spread apart and are apt to abut on the spinous processes of two adjacent vertebrae.

[0012] In order to be able to switch between the first closing configuration and the second opening configuration, connecting means for connection between the fins and the main body are provided, which allow a rotational and / or translational movement of the fins with respect to the main body of the interspinous device.

[0013] To achieve such a result, currently known and used interspinous devices have kinematic mechanisms characterized by considerable internal mechanical complexity.

[0014] For example, document W02016088058 describes an interspinous device for intervertebral arthrodesis comprising a main body configured to be inserted between two adjacent spinous processes. The device described therein further comprises two pairs of fins, provided, at one end thereof, with gear teeth and configured to rotate about an axis substantially orthogonal to a longitudinal direction of the main body and translate along the longitudinal direction of the main body.

[0015] Specifically, according to the teachings of the aforementioned document, in order to move from a position of minimum space requirement in which the fins are closed and arranged closely along the main body, to a second operating position in which the fins are spread apart and apt to abut on the spinous processes of two adjacent vertebrae, the rotation of the fins is achieved by acting on a threaded control shaft, the threaded portions of which interact with the gear teeth of the fins.

[0016] As is known, the presence of gears requires high precision of assembly and makes this device particularly complex not only from a construction point of view, but also from a percutaneous insertion point of view, making it particularly complicated to maneuver during surgery for inserting it.

[0017] Document WO2011141869, instead, discloses an interspinal retractor device in which wings are arranged to center and stabilize the device in a correct intervertebral position. Said wings are linked to a pair of sliders by means of a linkage system comprising a series of link rods.

[0018] By acting onto a threaded control shaft of the device, it is possible to achieve translation of the sliders along the longitudinal axis of the control shaft. The movement of the sliders causes the connecting rods to oscillate and the corresponding wings to rotate, thus allowing the interspinal device to assume different configurations.

[0019] Such a device, too, providing for the use of a linkage system as highlighted above is, mechanically speaking, particularly complex and not easy to assemble.

[0020] Another drawback of currently known interspinous devices lies in the fact that the complexity of their construction does not allow for devices smaller than a certain size, whereby use of such devices is limited almost exclusively to adult patients or patients of small build.

[0021] A purpose of the present invention is therefore to overcome the drawbacks of prior art by providing an interspinous device that is simple from a construction point of view, especially as far as the kinematic mechanisms allowing movement of the fins between the closing configuration and the operating configuration are concerned.

[0022] Another object of the present invention is to provide an interspinous device such that it enables the manufacturing of small-sized devices so as to make the device suitable even for patients who are children or have a small build.

[0023] A still further object of the present invention is to provide an interspinous device that allows precise movement of the fins, so as to guarantee correct and optimal positioning of the interspinous device between the spinous processes and stabilizing of said device.

[0024] These and other objects are achieved with an interspinous device as claimed in the appended claims.

[0025] Summary of Invention

[0026] The interspinous device for treating degenerative diseases of the spine according to the invention comprises a main body apt to be implanted into the space between the spinous processes of two adjacent vertebrae in order to provide corresponding support.

[0027] Said main body in turn comprises a control shaft. Preferably, said control shaft has a first threaded portion and a second threaded portion that are longitudinally distanced from each other and juxtaposed to each other, more preferably proximal to a first end and a second end of the shaft, respectively. The control shaft further comprises a control portion shaped so as to allow engagement with an appropriate actuating tool, so that, by acting onto the control shaft by means of the actuating tool, it is possible to control rotation of the control shaft about an axis extending along the longitudinal direction of the shaft.

[0028] The interspinous device according to the invention further comprises a first driving member and a second driving member, which are associated with the two opposite ends of the control shaft, respectively, and are movable along a longitudinal direction of said control shaft.

[0029] According to a preferred embodiment of the invention, said driving members comprise a sleeve having a threaded hole apt to engage with the first and second threaded portions of the control shaft, respectively, in order to enable, by means of the rotation of the control shaft, the first and second driving members to get closer to each other.

[0030] In addition, said interspinous device comprises a first retractor device and a second retractor device that are distanced from each other along the longitudinal direction and are associated with said control shaft in such a way as to be able to slide axially along the longitudinal direction of the control shaft.

[0031] Preferably, said retractor members are arranged between the two driving members.

[0032] Advantageously, according to the invention, said retractor members define a coupling of the male-female type that prevents them from rotating relative to each other.

[0033] Preferably, said first retractor member comprises a sleeve having female guiding portions and said second retractor member comprises a sleeve and anti-rotation male elements configured to slide axially in the female guiding portions when said retractor members are brought axially towards each other.

[0034] Even more preferably, said female guiding portions comprise guiding grooves provided on the first retractor member and said male elements provided on the second retractor member comprise anti-rotation blades.

[0035] Advantageously, according to the invention, said interspinous device further comprises control members, preferably arranged between the two retractor members and comprising elastic means.

[0036] Preferably, said control members are configured to keep the retractor members distanced from each other, in the absence of a load, and to allow said members to get closer to each other in the presence of a compression force.

[0037] Preferably, said elastic means of the control members comprise a spring, which is arranged substantially centrally and coaxially with the control shaft.

[0038] In addition, said interspinous device comprises two pairs of fins, which can slide relative to the control shaft along the longitudinal direction.

[0039] Each pair of fins comprises first connecting means for connection to the driving members, so that the fins are rotatable about respective rotation axes orthogonal to the longitudinal direction of the control shaft, and second connecting means for connection to the retractor members.

[0040] According to a preferred embodiment of the present invention, said first connecting means, provided between the pairs of fins and the retractor members, comprise rotation pins capable of engaging corresponding rotation seats provided on said fins and on said driving members, in order to allow, by translation of the driving members along the longitudinal direction, rotation of said fins about the orthogonal axes.

[0041] According to a preferred embodiment of the present invention, said second connecting means, provided between the pairs of fins and the retractor members, comprise a connection of the sliding pin-guide type, in which the retractor members have seats apt to receive sliding pins and the fins have guide portions apt to receive said sliding pins.

[0042] Preferably, the guiding portions provided on the fins comprise each at least one curved slot. Advantageously, the arrangement and the interaction between the elements forming the interspinous device of the present invention allow the interspinous device to assume at least three different configurations. At first, the interspinous device is in a first configuration or closing configuration, in which the two driving members are at the two ends of the control shaft, the two retractor members are kept distanced from each other thanks to the provision of the control members, and the two pairs of fins are closed, i.e., said pairs of fins are distanced from each other along the longitudinal direction and are substantially aligned to the control shaft.

[0043] In this configuration, the interspinous device assumes a macroscopically cylindrical shape having a preferably oval cross-section which is essentially constant along the longitudinal direction of the device, whereby the transverse space requirement of the device are minimum and such as to allow endoscopic insertion thereof between the spinous processes. After positioning the interspinous device between the spinous processes of the vertebrae concerned, rotation of the control shaft is obtained by acting onto the control shaft by means of the actuating tool.

[0044] By continuing to rotate the control shaft, the two driving members, in a threaded engagement with the threaded portions of the control shaft, get closer to each other, while the two retractor members remain in their position of maximum distance from each other by virtue of the thrust exerted by the control member. Therefore, the rotation of the control shaft causes, at first, the first driving member to get closer to the first retractor member, and the second driving member to get close to the second retractor member. This getting closer, in cooperation with the first connecting means, provided between the pairs of fins and the driving members, and the second connecting means, provided between the pairs of fins and the retractor members, allows the fins to rotate so as to assume a second, closing configuration, in which the fins are spread apart with respect to the control shaft and are distanced from each other along the longitudinal direction of the shaft.

[0045] By continuing to rotate the control shaft, the first driving member comes in contact with the first retractor member and the second driving member comes in contact with the second retractor member.

[0046] When the compression force exerted by the two driving members onto the two retractor members exceeds the force exerted by the control member onto the two retractor members, then said retractor members are pusher against each other by the respective driving members.

[0047] Accordingly, the two pairs of fins - constrained both to the driving members by means of the first connecting means and to the retractor members by means of the second connecting means - translate towards each other, remaining in the spread apart position, until they get close to each other on the respective opposite faces of the spinous processes in order to provide corresponding support.

[0048] A third configuration or retaining configuration is thus obtained, by virtue of which the spinous processes are clamped between the two pairs of fins, thereby fixing the interspinous device to the spine.

[0049] In addition, according to a preferred embodiment of the invention, said pairs of fins have, near their distal ends (distal to the control shaft when the fins are in their second and third configurations), an engaging portion shaped so as to penetrate the cortical tissue of the spinous processes.

[0050] Preferably, said engaging portion of the fins comprises one or more engaging teeth.

[0051] This allows said fins, during the third, retaining configuration, to clamp the spinous processes, thereby increasing the degree of stabilization of the interspinous device on the spine and making the device particularly suitable for those treatments requiring spinal arthrodesis.

[0052] Finally, according to a preferred embodiment of the invention, said control shaft comprises two groove portions and said first and second retractor devices comprise end stop elements cooperating with the groove portions of the control shaft. Said end stop elements are apt to slide in the respective groove portions provided on the control shaft in order to limit the travel of said retractor members.

[0053] Said end stop elements comprise end stop pins configured to be received in corresponding seats provided on said first and second retractor members.

[0054] The solution described above makes it possible to obtain a mechanically simple interspinous device, whose operation is based neither on the use of gears complex to manufacture nor on the use of link rods.

[0055] At the same time, the easy operation mechanics of said device allows to manufacture smallsized devices, thus making such device suitable not only to minimally invasive surgery, but also for insertion thereof into a seat other than the lumbar region and for treatment of patients of small build, typically of childhood patients.

[0056] The interspinous device according to the invention thus makes it possible to overcome the drawbacks of the interspinous devices of known type, while guaranteeing higher reliability thanks to its constructionally simple principle of operation.

[0057] Brief Description of Drawings

[0058] Further advantages and features of the present invention will become evident from the following detailed description of a preferred embodiment of the invention, given by way of non-limiting example with reference to the annexed drawings, in which:

[0059] Fig.l is a schematic perspective and exploded view of an interspinous device made according to the present invention;

[0060] Fig.2 is a front plan view of the interspinous device of Figure 1, shown in a first, closing configuration;

[0061] Fig.3 is a longitudinal sectional view of the interspinous device of Figure 2;

[0062] Fig.4 is a front plan view of the interspinous device of Figure 1, shown in a second, opening configuration;

[0063] Fig.5 is a longitudinal sectional view of the interspinous device of Figure 4;

[0064] Fig.6 is a longitudinal sectional view of the interspinous device, according to the invention, shown in a third, retaining configuration.

[0065] Description of Embodiments

[0066] In the ensuing description of a preferred embodiment of an interspinous device, reference will be made to an interspinous device sized and shaped to be inserted between the spinous processes of a pair of lumbar vertebrae in a minimally invasive manner, preferably by means of a latero-lateral approach, in order to lock such spinous processes at a predetermined distance constant over time and such as to ensure the arthrodesis process.

[0067] Although the interspinous device described in this embodiment is especially suitable for endoscopic operations at the lumbar level, this embodiment should not be interpreted as limiting and the interspinous device according to the invention might be used for being positioned in a different tract of the spine.

[0068] Furthermore, said interspinous device could be used as a simple retractor device, when fusion of vertebral segments is not required.

[0069] Referring to Figure 1, in the illustrated embodiment, the interspinous device 1 comprises a main body 1’ apt to be implanted into the space between the spinous processes of two adjacent vertebrae in order to provide corresponding support.

[0070] Said main body 1’ comprises in turn a control shaft 3, which has a mainly longitudinal development in which a first end 3’ and a second end 3” are defined.

[0071] Said control shaft 3 comprises, close to its first end 3’, a shaped control portion 3a allowing engagement with an appropriate actuating tool (not shown) suitable for making the control shaft 3 rotate about an axis extending along the longitudinal direction of said control shaft 3. As is known, said shaped control portion 3a can be made as a head with a polygonal crosssection and provided with an internally threaded axial cavity.

[0072] As is known, said actuating tool can be a surgical instrument made as a driving wrench or screwdriver.

[0073] Preferably, said interspinous device 1 has at least a flattened portion 4 along the longitudinal direction of the device itself, so that a tool (not shown) useful for inserting it prevents it from rotating while the control shaft 3 is being actuated.

[0074] Said control shaft 3 comprises a first threaded portion 3b and a second threaded portion 3c which are longitudinally distanced from each other and juxtaposed to each other, proximal to the first end 3’ and the second end 3” of the control shaft 3, respectively.

[0075] Said interspinous device 1 further comprises a first retractor member 7a and a second retractor member 7b, which are arranged distanced from each other along the longitudinal direction of the control shaft 3 and are associated with said control shaft 3 in such a way as to be able to slide axially along said longitudinal direction.

[0076] The first retractor member 7a and the second retractor member 7b define a coupling of the male-female type that prevents said retractor members from rotating relative to each other. In the embodiment shown in Figure 1, the first retractor member 7a comprises a sleeve 8a provided with female guiding portions, whereas the second retractor member 7b comprises a sleeve 8b and anti-rotation male elements extending axially near an end of said second retractor member 7b.

[0077] Still referring to the illustrated embodiment, the female guiding portions comprise diametrically opposite guiding grooves 10a extending axially over the sleeve of the first retractor member 7a.

[0078] The male elements, in the illustrated embodiment, comprise a pair of diametrically opposite anti -rotation blades 10b on the sleeve 8b of the second retractor member 7b. In the illustrated embodiment, the anti-rotation blades 10b are made as a single piece with the sleeve 8b of the second retractor member 7b.

[0079] When said retractor members 7a, 7b are brought closer to each other axially, the antirotation blades 10b of the second retractor member 7b slide axially in the guiding grooves 10a of the first retractor member 7a in order to prevent said two retractor members 7a, 7b from rotating relative to each other.

[0080] Alternatively, said retractor members 7a and, 7b may comprise mechanisms and configurations other than those shown and known to the person skilled in the art, and such as to prevent the retractor members from rotating relative to each other.

[0081] Moreover, the control shaft 3 comprises two groove portions 3d and 3e and the retractor members 7a and 7b comprise end stop pins 5a and 5b, arranged transversely to the longitudinal direction of the control shaft 3 and apt to slide within the respective groove portions 3d and 3e.

[0082] Said end stop pins 5a and 5b, which are received in corresponding seats provided on the first and second retractor members, respectively, and are constrained to move within the grooves 3d and 3e, limit the longitudinal travel of said retractor members along the control shaft 3.

[0083] The interspinous device 1 further comprises control members 11 comprising elastic means arranged between the first retractor ember 7a and the second retractor member 7b and configured to maintain said first and second retractor members 7a, 7b in a state in which they are distanced from each other, in the absence of a load.

[0084] In the illustrated embodiment, said elastic means comprise a spring 11, arranged substantially centrally and coaxially with the control shaft 3, and interposed between the retractor members 7a and 7b.

[0085] Said spring 11 has the function of maintaining the retractor members 7a and 7b distanced from each other in the absence of a load and to allow said retractor members to get closer to each other in the presence of a compression force.

[0086] The interspinous device 1 further comprises a first driving member 13a and a second driving member 13b associated proximally to the first end 3’ and the second end 3” of the control shaft 3, respectively, in such a way that said first and second retractor members 7a, 7b are positioned between said first and second driving members.

[0087] In the illustrated embodiment, the first driving member 13a comprises a sleeve provided with a threaded hole apt to engage with the corresponding threaded portion 3b of the control shaft 3. The second driving member 13b in turn comprises a sleeve provided with a threaded hole apt to engage with the corresponding threaded portion 3 c of the control shaft 3.

[0088] The presence of said threaded holes makes it possible, by rotating the control shaft 3 by means of the actuating tool, to bring the first and second driving members 13a, 13b closer to the first and second retractor members 7a, 7b, respectively.

[0089] Said interspinous device 1 further comprises a first pair of fins 17a, 17a' and a second pair of fins 17b, 17b' capable of translating along the longitudinal direction of the control shaft 3 and of rotating about corresponding rotation axes orthogonal to the longitudinal direction of the control shaft 3.

[0090] The interspinous device 1 further comprises first connecting means, provided between the two pairs of fins 17a, 17a' and 17b, 17b' and the driving members 13, 13b, said first connecting means comprising rotation pins 15a, 15b capable of engaging corresponding rotation seats 18a, 18b provided on said fins and said driving members in order to allow, by means of translation of the driving members along the longitudinal direction, rotation of said fins about the orthogonal axes.

[0091] The interspinous device 1 further comprises second connecting means, provided between the two pairs of fins 17a, 17a' and 17b, 17b' and the retractor members 7a, 7b, said second connecting means comprising a connection of the sliding pin-guide type, wherein the retractor members have seats 20a, 20b apt to receive sliding pins 9a, 9b and the fins have guiding portions apt to receive said sliding pins.

[0092] In the illustrated embodiment, the first connecting means are defined by two seats 22a, 22b provided in each of the driving members 13a, 13b, said seats being apt to house the corresponding rotating pins 15a, 15b.

[0093] In the illustrated embodiment, the second connecting means are defined by at least one guiding slot 24a, 24b provided on each of the fins and substantially curved, and by the corresponding sliding pins 9a, 9b provided on the retractor members 7a, 7b.

[0094] Advantageously, the arrangement and interaction between the elements described above make it possible for the interspinous device 1, by means only of the rotation of the control shaft 3, to assume at least three different configurations, without having to resort to constructive solutions that are particularly complex or imply using a high number of components.

[0095] Referring to Figures 2 - 6, there are shown in detail the configurations that the interspinous device 1 can assume.

[0096] Referring to Figures 2 and 3, the interspinous device 1 is shown in a first configuration, called closing configuration, in which the driving members 13a and 13b are proximal to the two ends 3’ and 3” of the control shaft 3 and the retractor members 7a and 7b, arranged between the driving members 13a, 13b and more inwards with respect to the longitudinal direction of the control shaft 3, are maintained distanced from each other by the action of the spring 11 which is in its stretched position.

[0097] In this configuration, the two pairs of fins 17a, 17a' and 17b, 17b', because of the geometry of the slots present on the fins themselves, are closed, i.e., they are substantially aligned with the control shaft 3.

[0098] Therefore, in its first configuration the interspinous device 1 assumes a macroscopically cylindrical shape, with a cross-section that is substantially oval and constant over the longitudinal direction of the device 1, whereby the transverse space requirement of the device are minimum and such as to allow the endoscopic insertion of the device between the spinous processes.

[0099] After positioning the interspinous device 1 between the spinous processes of the vertebrae concerned, it will be possible to shift to a second, opening configuration and then to a third, retaining configuration, by acting onto the shaped control portion 3a by means of the actuating tool and by controlling the rotation of the control shaft 3.

[0100] As shown in Figure 4, by rotating the control shaft 3 the driving members 13a and 13b, engaged in a threaded engagement with the respective threaded portions 3b and 3c of the control shaft 3, get closer to each other, while the retractor members 7a and 7b remain in their position of maximum distance from each other by virtue of the thrust exerted by the spring 11.

[0101] Therefore, as can be seen from Figure 5, the rotation of the control shaft 3 causes, at first, the first driving member 13a to get closer to the first retractor member 7a and the second driving member 13b to get closer to the second retractor member 7b.

[0102] This getting closer enables the rotation pins 15a and 15b, to which the fins 17a, 17a', 17b, 17b' are hinged, to translate towards the center of the control shaft 3, and forces the sliding pins 9a and 9b, constrained to the retractor members 7a and 7b, which have remained in their position of maximum distance from each other, to slide within the corresponding curved slots 24a, 24b of the fins.

[0103] Such combination of movements of the rotation pins 15a and 15b and the sliding pins 9a and 9b in cooperation with the geometry of the slots 24a, 24b provided on the fins causes the two pairs of fins 17a, 17a' and 17b, 17b' to rotate about the corresponding rotation pins 15a and 15b, so as to cause opening of the fins 17a, 17a' and 17b, 17b' with respect to the control shaft 3.

[0104] A second configuration, or opening configuration is thereby obtained, in which the fins 17a, 17a' and 17b, 17b' are spread apart relative to the control shaft 3 and are distanced from each other along the longitudinal direction of the control shaft 3.

[0105] This configuration is maintained until the driving members 13a and 13b, by means of the translational movement along the control shaft 3, come in contact with the corresponding retractor members 7a and 7b.

[0106] Indeed, by continuing to rotate the control shaft 3, the driving members 13a and 13b move forward along the control shaft, and at some time they come in contact with the retractor members 7a and 7b and push said retractor members against each other, until they overcome the force of the spring 11 arranged between the retractor members to keep them spaced apart from each other.

[0107] Accordingly, as shown in Figure 6, the fins 17a, 17a' and 17b, 17b', constrained both to the driving members 13a and 13b and the retractor members 7a and 7b, while maintaining the position assumed in the opening configuration, get closer to each other, sliding along the longitudinal direction of the control shaft 3.

[0108] In this way, the fins 17a, 17a' and 17b, 17b' abut on the opposite faces of the two spinous processes (not shown) of the vertebrae concerned.

[0109] A third configuration, or retaining configuration, is thereby obtained, thanks to which the interspinous device 1 becomes fixed and stabilized in the seat located between the spinous processes of adjacent vertebrae.

[0110] According to the illustrated embodiment, said fins 17a, 17a', 17b, 17b' have, preferably, one or more engaging teeth 19, provided near a distal end of said fins (distal to the control shaft 3 when said fins are in their second and third configurations) and shaped so as to penetrate the cortical tissue of the spinous processes.

[0111] It is therefore evident that the interspinous device 1 of the present invention makes it possible to ensure, thanks to simple kinematic systems, an effective locking of the spinous processes such as o facilitate the arthrodesis process, if required by the treatment.

[0112] It will be apparent to the person skilled in the art that the embodiment described above in detail should in no way be taken as limiting, and that several variations and modifications are possible without thereby departing from the scope of the invention as defined by the appended claims.

Claims

CLAIMS1. Interspinous device (1) for treating degenerative diseases of the spine, comprising a main body (L) apt to be implanted into the space between the spinous processes of two adjacent vertebrae in order to provide corresponding support, said main body in turn comprising a control shaft (3); said interspinous device (1) being characterized in that it comprises: a first driving member (13a) and a second driving member (13b) associated with a first end (3’) and a second end (3”) of the control shaft (3), respectively, and being movable along a longitudinal direction of said control shaft (3); a first retractor member (7a) and a second retractor member (7b), associated with said control shaft (3) and distanced from each other along the longitudinal direction of the control shaft (3) and arranged in such a way as to be able to axially slide along said longitudinal direction, wherein said first (7a) and second (7b) retractor members are arranged between said first and second driving members (13a, 13b); control members (11) comprising elastic means arranged between said first and second retractor members (7a, 7b) and configured to maintain said first and second retractor members (7a, 7b) in a condition in which said first and second retractor members (7a, 7b) are distanced from each other in the absence of a load; a first pair of fins (17a, 17a') and a second pair of fins (17b, 17b') slidable relative to the control shaft (3) along the longitudinal direction, each pair of fins comprising first connecting means for connection to said first and second driving members (13a, 13b) in such a way as to be rotatable about respective rotation axes orthogonal to the longitudinal direction of the control shaft (3), and second connecting means for connection to said first and second retractor members (7a, 7b), wherein said pairs of fins are configured to assume a first, closing configuration in which said pairs of fins are distanced from each other along the longitudinal direction and assume a configuration of minimum space requirement for facilitating the percutaneous insertion of the device (1), a second, opening configuration in which said pairs of fins are distanced from each other along the longitudinal direction and are spread apart with respect to the control shaft (3), and a third, retaining configuration in which said pairs of fins are close to each other along the longitudinal direction and abut on the respective opposite faces of the spinous processes in order to provide corresponding support.

2. Interspinous device (1) according to claim 1, wherein said control shaft (3) comprises a first threaded portion (3b) and a second threaded portion (3c) longitudinally distanced from each other and juxtaposed to each other, proximal to the first end (3’) and the second end (3”) of the control shaft (3), respectively, and a control portion (3a) shaped so as to be allowed to be engaged by a corresponding actuating tool apt to cause the control shaft (3) to rotate about an axis extending along the longitudinal direction.

3. Interspinous device (1) according to claim 1 or 2, wherein said first and second driving members (13a, 13b) comprise a sleeve having a threaded hole apt to engage with the first and second threaded portions (3b, 3c) of the control shaft (3), respectively, in order to enable, by means of the rotation of the control shaft (3), the first and second driving members (13a, 13b) to get closer to the first and second retractor member (7a, 7b), respectively.

4. Interspinous device (1) according to any of the preceding claims, wherein said elastic means comprise a spring arranged substantially centrally and coaxially with said control shaft (3) and interposed between said first and second retractor members (7a, 7b) to maintain said members distanced from each other in the absence of a load and to allow said members to get closer to each other in the presence of a compression force.

5. Interspinous device (1) according to any of the preceding claims, wherein said first connecting means provided between said pairs of fins (17a, 17a', 17b, 17b') and said first and second driving members (13a, 13b) comprise rotation pins (15a, 15b) capable of engaging corresponding rotation seats (18a, 18b) provided on said fins and on said driving members, in order to allow, by translation of the driving members along the longitudinal direction, rotation of said fins about axes orthogonal to the longitudinal direction.

6. Interspinous device (1) according to any of the preceding claims, wherein said second connecting means provided between sad pairs of fins (17a, 17a', 17b, 17b') and said first and second retractor members (7a, 7b) comprise a connection of the sliding pin-guide type, wherein said retractor members (7a, 7b) comprise corresponding seats (20a, 20b) apt to receive sliding pins (9a, 9b) and said fins comprise guiding portions (24a, 24b) apt to receive said sliding pins, and wherein said guiding portions are shaped so as to allow, by translation along the longitudinal direction, shifting of said fins from the closing configuration to the opening configuration.

7. Interspinous device (1) according to claim 6, wherein said guiding portions of the fins (17a, 17a', 17b, 17b') each comprise at least one curved slot.

8. Interspinous device (1) according to any of the preceding claims, wherein said control shaft (3) comprises two groove portions (3d, 3e), and wherein said first and second retractor members (7a, 7b) comprise end stop elements (5a, 5b) of said members apt to slide within the respective groove portions (3d, 3e) provided on the control shaft (3) in order to limit the travel of said retractor members (7a, 7b).

9. Interspinous device (1) according to claim 8, wherein said end stop elements (5a, 5b) comprise end stop pins configured to be received in corresponding seats provided on said first and second retractor members (7a, 7b), respectively.

10. Interspinous device (1) according to any of the preceding claims, wherein said fins (17a, 17a', 17b, 17b') comprise an engaging portion (19) provided near a distal end of said fins and shaped so as to penetrate the cortical tissue of the spinous processes in order to provide corresponding support, and wherein said distal end of the fins is distal to the control shaft (3) when said fins are in their second and third configurations.

11. Interspinous device (1) according to claim 10, wherein said engaging portion (19) of the fins comprises one or more engaging teeth.

12. Interspinous device (1) according to any of the preceding claims, wherein said first retractor member (7a) and said second retractor member (7b) define a coupling of the malefemale type that prevents said retractor members from rotating relative to each other.

13. Interspinous device (1) according to claim 12, wherein said first retractor member (7a) comprises a sleeve (8a) having female guiding portions (10a), and wherein said second retractor member (7b) comprises a sleeve (8b) and anti-rotation male elements (10b), wherein said male elements are configured to slide axially within the female guiding portion when said retractor members are axially brought closer to each other.

14. Interspinous device (1) according to claim 13, wherein said male elements (8b) comprise anti-rotation blades extending axially near a distal end of said second retractor member (7b), and in which said female guiding portions (10a) comprise guiding grooves provided on the first retractor member (7a).

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