NZ553062A - Inter-spinal implant - Google Patents

Abstract

(Not all items noted are shown in the selected drawing). The disclosure relates to an intervertebral implant (1) provided with a central axis (2); comprising two U-shaped insertion parts (3, 4) which are arranged on top of each other in an axial manner in relation to the central axis (2) and which comprise base surfaces (15) which are oriented counter to each other, respectively a first and a second lateral surface (18, 19), respectively a ventral and a dorsal lateral surface (20, 21) and respectively an opposition surface (17) comprising a channel (13) which is used to receive the spinous processes (32) of two adjacent vertebral bodies (33, 34); an intermediate piece (5) which can be inserted in a transversal manner on the central axis (2) between the base surfaces (15).; The intermediate piece (5) comprises two bearing surfaces (16) which can be placed on the base surfaces (15), and each bearing surface comprises a first three-dimensional structure (22a); and each of the base surfaces (15) comprises a second three-dimensional structure which can engage with the first three-dimensional structure (22a), such that the insertion pieces (3; 4), when the first and second structures (22a; 22b) are engaged, can be detachably fixed to the intermediate piece (5) which is parallel to the central axis (2).; The insertion pieces (3, 4) comprise, respectively, on the same lateral surface (18, 19), connecting means (23) which are used to secure the insertion pieces (3; 4) to the gripping elements (43) of a surgical instrument (35) and the first and the second structures (22a, 22b) can be engaged, respectively disengaged, only by the lateral surface (18, 19) comprising the connecting means (23).

Description

2093/PCT 20.12.2006 553062 INTER-SPINAL IMPLANT The invention refers to an inter-spinal implant.

Such inter-spinal implants serve as spacers for two adjacent vertebral bodies in a defective inter-vertebral disk, which would otherwise reduce the distance between the vertebral bodies. Thanks to the re-increased distance the bevel joints are also decompressed.

An inter-spinal implant of this kind is known from the FR 2 7176 675 by Taylor. This known implant comprises two rigid inserts capable of being fastened to the spina! process of the vertebra! bodies and an elastic centre piece between them. The inserts have at their base surfaces barbed hook-like appendices which are cast into the elastic centre piece and hold the inserts together with the centre piece. The disadvantage of this known implant is that during the implantation the already fully pre assembled implant is inserted between the spinal processes, so that the adjacent vertebral bodies must occasionally be widely distracted.

An inter-spinal prosthesis of this kind is further known is from the WO 03/015645 by Mathieu. This known inter-spinal prosthesis comprises two elements with appendices set on the spinal processes of the vertebral bodies to be treated and on a centre piece firmly connected to the processes of a part, so that each part must be inserted laterally, meaning from the other side of the spinal column.

The invention intends to offer a remedy for this situation or to at least provide the public with a useful alternative. The task underlying the invention is to create an inter-spinal implant that can be inserted and fastened into the inter-spinal space only from one side and between two spinal processes of adjacent vertebral bodies to be treated.

The invention provides an inter-spinai implant with a central axis comprising A) two U-shaped inserts set over each other with respect to the central axis and with opposing base surfaces, each with a first and a second Jateral side surface, a ventral 553062 2 (followed by page 2a) and dorsal side surface arid a juxtaposition surface having a channel to receive the spinal processes of two adjacent vertebral bodies; B} a centre piece introducibie across the central axis between the base surfaces, where C) the centre piece presents contact surfaces suitable for matching with the base surfaces, and each of the contact surfaces is provided with a first tri-dimensionat structure; and D) each of the base surfaces presents a second tri-dimensiona! structure which can be made to engage with the first tri-dimensional structure so that the inserts are, after engaging the first and second structures, fastened in a detachable manner to the centre piece parallel to the centra! axis, wherein E) the inserts each present, on the same lateral side surface, connecting means to fasten the inserts to the gripping elements of a surgical instrument; and F) the first and second structures can be engaged or disengaged only by the lateral side surface fitted with the connecting means.

The advantages secured by the invention are essentially to be seen in the fact that thanks to the implant according to the invention: - it becomes possible to use an implant with a one-sided access, thus rendering the operating process less invasive; It becomes possible to distract the two adjacent vertebral bodies directly with the implant, which allows better control; - A shorter operating time is possible due to the mentioned advantages. in a particular form of embodiment, the first and the second structures are conformed in parallel and in a form-locking manner to a transversal axis set across the central axis and crossing the ventral and the dorsal lateral surfaces.

The first and second structures can be conformed in parallel and in a form-locking manner to the central axis.

In another form of embodiment the inter-spinal implant comprises locking means whereby the first and second structures can be held engaged across the central axis. 553062 2a (followed by page 3) This secures the centre-piece toward sliding out. Thanks to the automatic locking means, an operation is no longer needed.

The locking means can be conformed in a detachable fashion.

In a further form of embodiment, the first structures each comprise at least one male dove tail guide, and the second structures each at least one female dove tail guide with a longitudinal axis set across the central axis. These dove tail guides allow a free from play assembly of the three parts, so that after the implantation the motions of the adjacent vertebral bodies are dampened by the elastic centre piece.

The male and female dove tail guides may exhibit longitudinal axes (26) extending across the transversal axis. This ensures a one-sided insertion of the inserts and of the centre piece. 553062 -> 3 in another form of embodiment, the locking means comprise screws that can be screwed into the inserts (3;4) and blocked against shifting by inserting the male dove tail guides into the female dove tail guides. The advantage of this embodiment is in the detachable configuration of the locking means.

In a further form of embodiment, the female dove tail guides are closed toward the lateral side surfaces are left without connecting means. This means that like a locking means only one screw need to be turned into each dove tail guide.

In another form of embodiment, the mail and female dove tail guides taper off toward the lateral side surfaces of the implant that are not fitted with connecting means. This facilitates the insertion of dove tail guides into the female dove tail guides. The longitudinal axis of the dove tail guides may be curved. The curvature of the dove tail guides allows inserting the centre-piece through a rotating gripping lever, whereby the space required for the introduction can be heid to a minimum.

The longitudinal axis of the dove taii guides may alternatively also be straight. The advantage of this embodiment is that the dove tail guides are easy to manufacture.

In another form of embodiment the inter-spinal implant is capable of being elasticaily deformed. The modular construction of the inter-spinal implant makes it possible to insert centre pieces of different height and stiffness, so as to adapt the inter-spinal implant to the anatomy in an optimal manner. in yet another form of embodiment, the inter-spinal implant presents a progressive spring characteristic curve. The progressive spring characteristic curve ensures an adequately large elastic resilience at only a small motion of the spring, in case of shock-loads, this aiso allows preventing overloads on the vertebral bodies or on the intervertebral disk lying in the inter-vertebral space.

The locking means can be conformed in a self-acting snap-in form that allows a simpler assembly of the implant. Each female dove tail guide can be provided with a recess and each male dove tail guide can be provided with a spring element (30) with a snap-in 553062 4 action in a corresponding cavity, so that the locking means exhibit a particularly simple design.

The invention and further developments of the invention will in the following be explained in yet greater detail by using partially simplified representations of several forms of embodiment.

The Figures show: Fig. 1 a perspective view of a form of embodiment of the inter-spina! implant according to the invention; Fig. 2 a perspective view of the centre piece together with the second insert of the form of embodiment of the inter-spinal implant according to the invention shown in Fig. 1; Fig. 3 a perspective view of a form of embodiment of the inter-spinal implant according to the invention shown in Fig. 1; Fig. 4 a view of the form of embodiment of the inter-spinal implant according to the invention shown in Fig. 3; Fig. 5 a topside view of the form of embodiment of the inter-spinal implant according to the invention shown in the figures 3 and 4; Fig. 6 an enlarged cross-section according to the circle A in Fig. 4; Fig. 7 a perspective view of the two inserts of a form of embodiment of the inter-spinal implant according to the invention during the implantation; Fig. 8 a perspective view of a form of embodiment of the inter-spinal implant according to the invention during the insertion of the centre piece; 553062 Fig. 9 a perspective view of the two inserts of a form of embodiment of the instrument and Fig. 10 an enlargement of the circle if in Fig. 9.

The implant 1 shown in the Figures 1 and 2 comprises essentially two U-shaped inserts 3;4 set across the central axis of the inter-spinal implant 1, and a centre piece 5 set between them. The inserts 3;4 are set with respect to a centre plane 6 set orthogonally to the longitudinal axis 2 so that the crossbars 7 of the two inserts 3.4 are set up parallel to the central plane 6 and the free extremities 11 ;12 of the sidebars 9:10 are pointing away from the central plane 6.

A channel delimited by two sidebars 9;10 and a crossbar 7;8 of an insert 3;4 is adapted to receive a spinal process of a vertebral body, whereby the inserts 3:4 are inserted into the inter-spinal inter-vertebral space so that the crossbars 7;8 are set between the spinal processes of two adjacent vertebral bodies. The channel axes 14 of the channels 13 are set across the centre axis 2 in a front-to-rear direction, meaning that they run parallel to a transversal axis 49 that crosses the ventral and the dorsal side surface 20:21 of the inter-spinal implant 1. The centre piece 5 is inserted between the base surfaces 15 of the crossbars 7 facing each other, whereby the resting surfaces 16 of the centre piece 5 come to rest on the base surfaces 15 of the crossbars 7. The inserts 3;4 comprise lateral side surfaces 18; 19 set externally on the sidebars 9; 10, one each ventral side surface 20 set across the same, and one each dorsal side surface 21 and contact surface 17 fitted with one each channel 13, respectively. In order to receive the gripping elements 43 of a surgical instrument 35 (Figures. 7 to 10), connecting means 23 are provided on the second lateral side surfaces 19.

The first and the second structures 22a;22b are set on each contact surface 16 of the centre piece 5 and on each base surface 15 of the inserts 3:4. The first and second structures 22a;22b are configured as dove tail guides with one each male dove tail guide 24 on the contact surfaces 16 of the centre piece (Fig. 2) and one each female dove tail guide 25 on the base surface 15 of the inserts 3;4, respectively, and are 553062 6 capable of connecting the inserts 3:4 with the centre piece 5 in a detachable manner. The male and female dove taii guides 24;25 exhibit a longitudinal axis 26 (Fig. 2) set across the central axis 2 and lying in the central plane 6 (Fig. 2). Moreover, the dove tail guides 24;25 are oriented so that the longitudinal axis 26 (Fig, 2) runs across the channel axes 14. The female dove tail guides 25 are closed toward the first lateral side surfaces 18 of the inserts 3;4 and open toward the second lateral side surfaces 19, so that the male dove tail guides 24 can be introduced from the second lateral side surfaces 19 of the inserts 3;4 into the female dove tai! guides 25. The male dove tail guides 24 are shorter than the female dove tail guides 25, so that if the centre piece 5 is inserted between the inserts 3;4, one each screw 40 can be screwed into the boreholes 47 in the sidebars 10 between the rear extremity 39 (Fig. 2) of the male dove taii guide 24 fitted with a rise 41 and into the second lateral side surface 19 of the two inserts 3:4, respectively. The screw 40 acting like a locking means 29 closes the female dove tail guide 25, so that the rise 41 on the rear extremity 39 of the male dove taii guide 24 rests on the screw 40. Thanks to the male dove taii guides 24, which are secured by the screws 40 in the closed female dove tail guides toward shifting in both directions, the two inserts 3;4 are, after the two screws 40 have been screwed in, blocked with respect to the centre piece 5. The sidebars 10 are conformed with recesses 50, so that the head of the screws 40 are sunk into the recesses 50 and do not project beyond the dorsal side surfaces 21 of the inserts 3;4.

Grooves 42 are provided, in parallel to the channel axes 14. on the lateral side surfaces 18; 19 of the two inserts 3:4. The grooves 42 are open on the dorsal side surfaces 21 and dosed on the ventral side surfaces 20 and serve to receive the gripping elements 43 of a surgical instrument 35 (Fig. 9).

The form of embodiment of the inter-spinal implant 1 shown in the Figures 3 through 5 differs from the form of embodiment shown in the Figures 1 and 2 by the fact that the locking means 29, the male and the female dove taii guides 24; 25 and the recesses for the gripping elements of a surgical instrument 35 (Fig. 7) are conformed in a different manner. The locking means 29 essentially comprise a spring element 30 capable of being snapped into a recess 31, which is, in the form of embodiment pictured here, conformed like a leaf spring fastened to the centre piece 5. The recess 31 is set on the 553062 7 female dove tail guide 25, and exhibits, in a direction parallel to the longitudinal axis 26 of the clove tail guides 24;25, a length L sized so that the field element 30 snaps into the recess 31 when, at the time of pushing it in between the inserts 3;4 across the central axis 2, the centre piece 5 has reached its final position with respect to the inserts 3;4. In the form of embodiment pictured here, the centre piece 5 is held firm in his position by the closed female dove tail guides 25 acting in a direction toward the first lateral side surfaces 18, and by the spring element 30 acting in a direction toward the second lateral side surfaces 19.

The dove tail guides 24 are conformed so that their longitudinal axis 26 (Fig. 5) is curved. In order to also fasten the inserts 3;4, after the inter-spinal implant 1 has been implanted, in a direction parallel to the base surfaces 15 with respect to the centre piece 5, Socking means 29, which are capable of being snapped into each other, are provided between each of the two male dove tail guides 24 and each of the two female dove tail guides 25.

Moreover, some first oval recesses 27 coming from the dorsal side surfaces 21 and penetrating into the sidebars 10, and second oval recesses 27 coming from the second side surfaces 19 - which are set on the right side, if viewed from the dorsal side - and penetrating into the sidebars 10 are provided on the inserts 3;4. In the form of embodiment pictured here, the first and second oval recesses 27;28 are - if viewed from the dorsal side - inserted into the right-hand sidebars 1 of the two inserts 3;4. These first and second oval recesses 27;28 are suitable for receiving the gripping elements of a surgical instrument 35 (Fig. 7).

As illustrated in Fig. 6, the locking means 29 essentially comprise a spring element 30 capable of being snapped into a recess 31, which is, in the form of embodiment pictured here, conformed like a leaf spring fastened to the centre piece 5, The recess 31 is set up on the female dove taii guide 25, and exhibits in a direction parallel to the longitudinal axis 26 of the dove tail guides 24;25 a length L sized so that the field element 30 snaps into the recess 31, when at the time of pushing it in between the inserts 3;4 across the central axis 2, the centre piece has reached his final position 553062 8 relative to the inserts 3;4. In the form of embodiment pictured here, the centre piece 5 is held in position by the closed female dove taii guides 25 acting in the direction of the first lateral side surfaces 18, and by the spring element 30 acting in the direction of the second lateral side surfaces 19.

The Figures 7 and 8 serve to explain the following operating process to carry out the implanting of the inter-spinal implant 1: a) Producing a one-sided incision at the vertebral bodies to be treated 33;34: b) Distracting the vertebral bodies to be treated 33;34 by using a tongue (not shown) capable of passing through the lateral incision and coming into contact with the spinal processes 32 of the two vertebral bodies 33;34; c) Introducing the two inserts 3;4 by passing a holding tongue 36 (Figures t through 10) through the lateral incision whereby, in the form of embodiment of the inter-spinaf prosthesis shown here, the inserts 3:4 are introduced from the right side in the direction of the arrow A into the intermediate spaces between the spinal processes 32 of the two vertebral bodies to be treated 33;34. For this purpose, the free extremities of the holding tongue 36 are anchored in the oval recesses 27;28 (Fig. 3) or in the grooves 42 (Fig. 1), so that the two inserts 3;4 can be pushed, with their first lateral side surfaces 18 facing forward, into the intermediate space of the spinai processes 32 d) introducing the centre piece 5 from the side, by using the gripping lever 37 (Figures. 7 and 8) or passing through the access channel 44 (Figures. 9 and 10); e) generating an initial stress on the centre piece 5 by slightly distracting the two inserts 3;4 with the holding tongue 36; f) releasing the fastening of the free extremities of the holding tongue 36 from the two inserts 3;4; g) removing the holding tongue 36; and h) Closing the incision.

The Figures. 9 and 10 show a form of embodiment of the surgical instrument 35 which is suitable for the form of embodiment of the inter-spinal implant i shown in the Figures. 1 and 2. The gripping elements 43a;43b are fitted at their free extremities with rises 45 553062 9 which can made to engage with the grooves 42 on the lateral side surfaces 18; 19 of the inserts 3;4.

After carrying out the process step d), the screws 40 are pushed through the openings 46 parallel to the channel axes 14 and into the sidebars 10 of the inserts 3;4. tn the form of embodiment of the surgical instrument shown in the Figures 7 and 8, according to the process step d), the centre piece 5 is pushed between the inserts 3:4 not by passing through an access channel 44 but by using a gripping lever 37, so that the following process steps must be carried out after the process step c): d') introducing a gripping lever 36 through the lateral incision, while the centre piece 5 is gripped in the front end of the gripping lever 37; d") introducing the centre piece 5 between the inserts 3;4 from the side, by using the gripping lever 37. to simplify the execution of this step, the gripping lever 37 can be carried on the holding tongue 36 by a hinge 38 (Fig. 8) in a rotating manner; e) generating an initial stress on the centre piece 5 by slightly distracting the two inserts 3;4 with the holding tongue 36: f) removing the holding tongue 36; and g) releasing the attachment of the free ends of the holding tongue 36 from the two inserts 3;4:, h) removing the holding tongue 36; and i) closing the incision.

Claims (18)

553062 10 PATENT CLAIMS

1. inter-spinai impiant with a central axis comprising A) two U-shaped inserts set over each other with respect to the central axis and with opposing base surfaces, each with a first and a second lateral side surface, a ventral and dorsal side surface and a juxtaposition surface having a channel to receive the spinal processes of two adjacent vertebral bodies; B) a centre piece introducible across the central axis between the base surfaces, where C) the centre piece presents contact surfaces suitable for matching with the base surfaces, and each of the contact surfaces is provided with a first tri-dimensional structure; and D) each of the base surfaces presents a second tri-dimensional structure which can be made to engage with the first tri-dimensional structure so that the inserts are, after engaging the first and second structures, fastened in a detachable manner to the centre piece parallel to the central axis, wherein E) the inserts each present, on the same lateral side surface, connecting means to fasten the inserts to the gripping elements of a surgical instrument; and F) the first and second structures can be engaged or disengaged only by the lateral side surface fitted with the connecting means.

2.) Inter-spinal implant according to claim 1, wherein the first and second structures are conformed in a form-iocking manner parallel to a transversal axis set across the central axis and crossing the ventral and dorsal side surfaces.

3.) inter-spinal implant according to claim 1 or 2, wherein the first and second structures are conformed in a form-locking manner parallel to the central axis.

4.) Inter-spinal implant according to any one of claims 1 to 3, wherein if comprises locking means by which the first and second structures can be held engaged across the central axis.

5. Inter-spinal implant according to ciaim 4, wherein the e. 553062. n

6.) Inter-spinal implant according to any one of claims 1 to 5; wherein the first structures each comprise at least one male dove tail guide and the second structures each comprise at least one suitable dove tail guide with one longitudinal axis running across the central axis,

7.} Inter-spinal implant according to claim 6, wherein the male and female dove tail guides have longitudinal axes running across the transversal axis.

8.) Inter-spinal implant according to claim 6 or 7, wherein the locking means comprise screws that can be screwed into the inserts, whereby the male dove tail guides can be blocked toward shifting in the female dove taii guides.

9.) inter-spinal implant according to any one of claims 6 to 8, wherein the female dove tail guides are closed toward the lateral side surfaces that do not have connecting means,

10.) Inter-spinal implant according to any one of claims 6 to 9, wherein the male and the female dove tail guides are tapered toward the lateral side surfaces of the implant that do not have connecting means.

11.) Inter-spinal implant according to any one of claims 6 to 10, wherein the longitudinal axis of the dove tail guides is curved.

12.) Inter-spinal implant according to any one of claims 6 to 10, wherein the longitudinal axis of the dove tail guides are straight.

13.) inter-spinai implant according to any one of claims 1 to 12, wherein it is eiastically deformabie.

14. Inter-spinal implant according to claim 13, wherein it presents a progressive characteristic curve of the springpNTEiesTUAt 553062 12.

15.) Inter-spinal implant according to any one of claims 4 to 7 or 9 to 14, wherein the locking means are conformed in a self-acting snap-in manner.

16.) Inter-spina! implant according to claim 15, wherein a recess is provided on each female dove tail guide, and that a spring element, which is capable of being snapped into the relative recess, is provided on each male dove tail guide.

17.) Inter-spinal implant substantially as herein described with reference to the accompanying Figures 1 to 10.

18. Inter-spinal implant as claimed in any one of claims 1 to 16 substantially as herein described with reference to the accompanying Figures 1 to 10. ' Or H2! .