Source: https://patents.google.com/patent/EP0999796B1/en
Timestamp: 2020-01-18 20:42:57
Document Index: 338574446

Matched Legal Cases: ['art 11', 'art 12', 'art 13', 'art 11', 'art 12', 'art 11', 'art 13', 'arts 11', 'art 12', 'art 13', 'art 12', 'art 12', 'art 12', 'art 13', 'art 12', 'art 14', 'art 14', 'art 13', 'art 12', 'art 21', 'art 12', 'art 12', 'art 14', 'art 14', 'art 11', 'arts 13', 'arts 13', 'art 41', 'art 11']

EP0999796B1 - Implant, in particular front cervical plate - Google Patents
EP0999796B1
EP0999796B1 EP98940342A EP98940342A EP0999796B1 EP 0999796 B1 EP0999796 B1 EP 0999796B1 EP 98940342 A EP98940342 A EP 98940342A EP 98940342 A EP98940342 A EP 98940342A EP 0999796 B1 EP0999796 B1 EP 0999796B1
EP98940342A
EP0999796A1 (en
1997-07-28 Priority to FR9709579 priority Critical
2000-05-17 Publication of EP0999796A1 publication Critical patent/EP0999796A1/en
2003-04-16 Publication of EP0999796B1 publication Critical patent/EP0999796B1/en
The invention concerns a plate (10, 10) designed to be fixed by means of a bone fixing screw (30) to two vertebrae. The invention is characterised in that the plate comprises two elements (10, 10) each including at least one hole (111) for a bone fixing screw (20), each of the elements capable of sliding relative to the other in a direction bringing them closer to or spacing them from the vertebrae relative to each other. Said elements are provided with means (141, 30) for limiting the mutual sliding travel between them to block said elements in a given mutual position. The invention is in particular applicable to cervical plates to be implanted from the front.
The present invention relates generally to fixation systems for osteosynthesis of the spine, and relates in particular to a new plate called plate cervical, intended to secure in a particular way to minus two cervical vertebrae.
Bone fusion techniques at the cervical level are well known and commonly practiced in indications such as degenerative spine, hernias discs or more generally various cases of trauma or tumors.
These techniques are based on the principle of discectomy (i.e. removing a disc), simple or multiple, possibly associated with a corporectomy (removal of a vertebral body), also simple or multiple;
The spaces left free by such ablations are usually filled with bone grafts cut to desired dimensions.
On this subject, we know that to be able to obtain a merger bone from a graft, it is necessary that it is subjected to a state of compressive stresses. This compression is generally obtained by a slight oversized graft, associated with distraction intraoperative between the cervical bone structures adjacent.
Document FR-A-2 728 454 describes an implant in accordance with the preamble of claim 1.
Document US-A-5 616 142 already discloses a implant with a solid plate in two parts sliding, each of which has holes for screws anchoring in two adjacent vertebrae.
This full plate allows to contain the materials introduced between the two vertebrae, such as blocks hydroxyapatite, bone grafts or bone substitutes.
Furthermore, the ability of both parties to sliding one relative to the other allows adaptation easily at different spacings between vertebrae.
This known plate is however disadvantageous in that that it presents a risk of play between the two parties, which can facilitate accidental loosening of the screws.
In addition, this possibility of sliding makes the implant unable to maintain a desired spacing between the two vertebrae in the longitudinal direction of the spine, so that the initial compression of the graft bone may be affected, with consequent poor quality or speed of fusion, or even a fusion totally defective.
The present invention aims to overcome these drawbacks of the state of the art and to propose an implant, usable in particular as anterior cervical plate, of which installation is significantly simplified and in which can take advantage of a plate in two sliding elements to establish and maintain compression of bone grafts introduced between two vertebrae on which the implant comes to anchor.
Thus the present invention provides an implant for osteosynthesis of the spine, comprising a plate intended for be fixed with two bone fixation screws vertebrae such as cervical vertebrae, especially by anterior approach, characterized in that the plate has two elements each comprising at least one hole for a bone fixation screw, each of the elements being likely to slide relative to each other in a direction corresponding to a merger or a distance of the vertebrae from each other, and said elements being provided with means for limiting the mutual sliding stroke between these and to block said elements in a given mutual position.
Preferred, but not limiting, aspects of the implant according to the invention are as follows:
the two elements are arranged head to tail.
each element comprises a first end part comprising the hole or holes for bone fixation screws, and a second end part having an oblong opening whose major axis defines the direction of sliding, said opening being traversed by a projecting element integral with a part other element.
each projecting element consists of a screw constituting one of said locking means.
said intermediate part of each element is located in the extension and in continuity of said. first terminal part.
said second end part of each element is offset in height with respect to said first end part and to said intermediate part, so as to cover the intermediate part of the other element.
each element further comprises a narrower connecting part between its intermediate part and its second end part.
said connecting parts of the two elements each delimit part of a through passage of the plate.
said through passage is oblong and has at its base a peripheral shoulder.
said shoulder is beveled.
the implant also comprises at least one auxiliary anchoring screw engaged in said through passage.
the connecting part of each element defines at least one shoulder capable of cooperating with the second end part or with the intermediate part of the other element, so as to define a sliding stop for the two elements.
each bone fixing screw comprises an intermediate thread intended to cooperate with a corresponding thread provided in the hole for associated screw.
each bone fixation screw comprises a generally conical contour head and provided with a plurality of branches separated by interstices of generally axial orientation, the conicity of the head being capable of locking the screw against the friction rotation of said head in the associated hole.
said head has a groove capable of cooperating with an internally projecting part formed in the associated hole, in order to produce an axial blocking.
The invention also provides a set of implants, characterized in that it comprises a plurality of implants as defined above, with plate elements with different numbers of holes for fixing screws bone and different screw hole orientations, and a plurality of bone fixation screws, and in that the different plate elements are visually differentiated.
Other aspects, aims and advantages of the present invention will appear better on reading the following detailed description of preferred embodiments thereof, given by way of example and made with reference to the appended drawings, in which:
FIG. 1 is an overall perspective view of a cervical implant according to the invention,
FIG. 2 is a perspective view of the implant in the absence of the bone fixation screws,
FIG. 3 is an exploded perspective view of the entire implant of FIG. 1,
FIG. 4 is a perspective view, on an enlarged scale, of part of a bone fixing screw usable with the implant of FIGS. 1 to 3,
FIG. 5 is a perspective view of part of the implant and of a bone fixation screw according to another embodiment, before screwing the screw into a vertebra,
FIG. 7 is a perspective view of an implant according to FIGS. 1 to 3 supplemented by an intermediate screw, and
FIG. 8 is a perspective view, in another orientation, of the implant of FIG. 7.
With reference to the drawing, and first of all to Figures 1 to 3, an implant forming an anterior plate has been shown cervical spinal surgery, which includes two identical plate elements 10, 10 able to cooperate with bone anchor screws.
Each plate element includes a terminal part 11 for bone anchoring, an intermediate part 12 of guide, an intermediate connecting part 13 and a guide end portion 14.
Part 11, shaped like a thin plate of contours rounded, side by side two through openings 111 generally circular, inside which is formed a locking net 1111, these openings 111 being intended to each receive a screw 20 for anchoring bone 20.
The intermediate part 12 extending in the extension of part 11, over a narrower width, and has a threaded through bore 121.
The connecting part 13 is generally straight and significantly narrower than parts 11 and 12, in extending in the extension of a lateral edge of said part 12. This part 13 has a region 131 located in the extension of part 12 in terms of height, and a region 132 raised compared to region 131. A first transverse offset 1311 marks the end of the region 131 opposite part 12, while a second transverse offset 1321 marks the end of the region 132 on the side of part 12.
It will be observed here that the lower region 131 of the connecting part 13 has, on the inside, a width more important than region 132, being delimited by a base interior face 1313 and by a face intermediate bevel 1312 joining the face 1313 to the inner face of region 132. As shown in particularly Figure 3, this particular profile adopted by the interior of region 131 extends by two quarters in the circle, on the side of part 12 and on the side of part 14.
Part 14 is located, in terms of height, in the extension of the upper region 132 of the part 13, and has a width identical to that of part 12. It ends with a semicircular end face, and is crossed by an oblong opening 141 whose major axis is on the longitudinal axis of the plate element 10. This opening 141 is entirely surrounded by a step in hollow 142.
As shown in particular in Figure 4, each screw 20 bone anchor mainly includes a threaded rod 21 intended to penetrate a cervical vertebra, and a larger head 23 in which an imprint is made 24 hexagon socket for a screwing tool. He is by elsewhere provided for at the transition between the threaded part 21 and the head 23, a thread 22 of pitch which is substantially internal to that of the thread 21, extending over a height very limited and intended to cooperate with the net 1111 provided in the associated opening 111 of the plate element, for purposes explained later.
Finally, the screw 20 has in the region of its tip a concave recess 25 with sharp edges, intended to facilitate the attack of the bone material by the nets.
Finally, the implant according to the invention has two other screw 30, each having a short threaded portion 31 allowing it to be screwed into an associated bore 121 of the plate element 10, freely crossing the opening oblong 141 of the other plate element 10, and a head 32 having a groove for screwing, and the width of which is very slightly less than the width between the opposite steps provided around said opening 141.
The mounting of the two plate elements 10, 10 is carried out by placing these two elements head to tail, and by placing the end portion 14 of each above the intermediate part 12 on the other.
The two screws 30 are then put in place through the respective openings 141 and screwed into the bores 121, without blocking them.
It is understood that from this moment, the two plate elements 10, 10 are secured to one another while retaining a single degree of freedom in sliding between two stops in the axial direction. The course of this sliding, indicated at d in FIG. 2, is defined in particular by the length of the oblong openings 141, and is chosen to be equal to a few millimeters, for example two millimeters. It will be observed here that the end of travel stops of this mutual sliding are defined not only by the ends of the oblong openings 141 against which the screws 30 come to bear, but possibly, in the opposite direction, by the coming into abutment of the shoulders 1311, 1321 of each element 10, described above, respectively against the faces facing the intermediate part 12 and the end part 14 of the other element 10.
We also observe that, during the assembly of the two plate elements 10, 10, we define in the region central plate thus obtained a through passage oblong in the axial direction, designated by the reference 150, which is jointly defined by the intermediary parties connecting 13, 13 of the two elements 10, 10. This passage has in its base region an oblique shoulder continuous device defined jointly by the faces 1312 provided on the two plate elements, which narrows the section of said passage, for purposes explained below.
The placement by the surgeon is done by introducing first of all, in the intervertebral space located between the two cervical vertebrae in which the implant must to be anchored, bone grafts intended, ultimately, for bone fusion between the two vertebrae.
Then, the implant being previously prepared in inserting the four bone anchor screws 20 into their four respective openings 111, the surgeon screws them in pairs in two adjacent vertebrae.
During this operation, the two plate elements 10, 10 can either be mutually blocked using the screw 30 in a maximum distracted position (position of Figure 2), either free to slide one relative to the other.
At the end of the tightening of the bone anchor screws 20, the intermediate nets 22 of these are able to cooperate with 1111 threads provided in their openings respective 111 to ensure their blocking at the bottom of the net, and thus avoid their loosening.
Then, the screws 30 being loosened if necessary, the surgeon performs with an appropriate tool a approximation of the vertebrae, which has the effect of compressing bone grafts and facilitate the taking of these grafts. During this movement, the two elements of plate 10, 10 slide relative to each other. When the degree of compression required is. reached, the whole is held in this position and the two screws 30 are tightened to block the cervical plate in this position for ensuring lasting compression of the grafts.
Note here that, thanks to the double overlap of the two plate elements 10, on the one hand between the part intermediate 12 of one and the terminal part 14 of each other and, in reverse and at a distance, between the part intermediate 12 on the other and the end portion 14 of one, we finally get a plate with a excellent rigidity, especially with regard to bending.
We will also observe here, as shown in particularly Figures 1 and 3, that the bone anchor screws 20 can be oriented at an angle to the normal to the general plane of the cervical plate 10, 10.
More specifically, it can be provided that the openings through 111 of the elements 10 have their inclined axes, either towards the outside of the plate, or towards the inside, and both in its longitudinal direction and in its transverse direction, to adapt the orientation of the rods threaded 21 of the screws 20 to the bone configuration of the patient.
This inclination can typically be understood, in one direction or the other, between 0 ° and 15 °.
In practice, the surgeon is offered different sets of plates with different numbers and / or different inclinations of the openings 111.
It should be noted here that the screws 20 with intermediate thread 22, in cooperation with screw holes 111 provided with a associated net 1111, can be used not only with two-part plates according to this invention, but more generally in any kind of implant intended to be crossed by a bone anchor screw.
Figures 5 and 6 illustrate another form of realization of the anchor screws, designated in 20 '.
These screws include, in addition to the bone thread 21 and the recess 25, a hollow head 23 ′ of circular section and slightly frustoconical, the outside diameter of which is close to that of the threaded part. The taper of the head 23 'is such that its section decreases from its end external to the threaded rod 21,
This cylindrical head has four branches 26 regularly spaced in circumferential direction, which are separated by axially oriented interstices 27.
Each branch has a groove on its external face circumferential 261, and a hooking tooth 262 is thus defined between said groove and the free end of the head.
The head also has, in a non-visible manner, a impression for screwdriving tools planned in the region of root of the four branches 26.
Furthermore, the openings 111 provided in the plate elements 10 for receiving the screws 20 have no plus a net, but a step, indicated in 1112 in the figure 5, provided at the base of the respective opening 111, the axial dimension is substantially equal to that of the groove 261 of each of the branches, and which projects towards the inside.
The screw 20 'is put in place by screwing into the bone and, as it progresses, the head 23 'will engage in the opening 111, the branches 26 then deforming elastically inward, under the effect of stress exerted by the step 1112, until this last one come to stay intimately in each of the four grooves 261.
Furthermore, the dimension and the taper angle of the head 23 'and the dimension of each associated opening 111 are such that at the end of tightening, the friction force between the outer surface of the head and the wall of the associated opening 111 is sufficient to avoid the loosening of the bone fixation screw 20 '.
The embodiment illustrated in Figures 5 and 6 is advantageous in that at the end of assembly, the face external of each screw 20 ′ is substantially flush with the outer face of part 11 of plate 20, which reduces the overall size of the assembly.
Referring now to Figures 7 and 8, we have illustrated the case where the cervical plate implant described above is completed by a screw, schematically represented in 40, which is intended to penetrate into the bone graft placed between the two vertebrae, being placed in place through passage 150 defined by the two plate elements 10 during their assembly.
Such a screw comprises a rod 41, the thread of which has not been represented for the sake of simplification, and a larger head 42, provided with a six-point hollow imprint sides for screwing tool.
The overall diameter of the threaded rod 41 is less than the minimum width of the passage (at the base regions 131 of the connecting parts 13 of the elements 10), while the diameter of its head is larger than its maximum width (at the level of the regions 132 of said parts 13).
In this way, the head 42 of the screw 40 may not protrude outward from the outer contour of the assembled plate 10, 10, as shown in FIG. 5.
This figure also shows that the threaded part 41 has in the vicinity of its tip a recess 43 facilitating the attack on the nets.
The addition of such a screw 40 improves the mechanical cohesion of the whole, bone growth taking place with the threads of this screw.
In addition, depending on the length of the oblong passage 150, one can plan to have two 40 screws in it or even more.
It will also be observed that the head 41 of the screw 40 has a base portion 411 in the form of a portion of sphere, which allows the screw 40 to be easily inclined compared to normal to the general plane of the plate, so as to adapt to the configuration of the space intervertebral receiving bone grafts. The angulation possible can for example reach 20 °.
Naturally, the different components of the implants described above are made of a biocompatible material such as a titanium alloy or stainless steel.
Of course, the present invention is by no means limited to the embodiments described and shown, but the person skilled in the art will be able to bring there any variant or modification according to his spirit.
In particular, a number of screws can be provided bone anchor 20 different from two per element 10.
In addition, the surgeon is preferably offered a box comprising a set of a plurality of implants and anchor screw, with plate elements 10 presenting by example 1, 2 3 or 4 holes 111 for fixing screws, and plate elements with different orientations of these holes 111 with respect to the general plan of part 11 elements.
In the box, these different elements 10 are by example differentiated by color codes or the like.
Implant for osteosynthesis of the spine, comprising a plate (10, 10) capable of being fixed to two vertebrae, such as cervical vertebrae, with the aid of bone fixation screws (20), comprising two elements (10, 10), each including at least one hole (111) capable of receiving a bone fixation screw (20), each of the elements being able to perform sliding relative to the other in a direction corresponding to a closing together or distancing of the said elements relative to one another, characterized in that the said elements are provided with means (141, 30) capable of blocking the said elements in any mutual position in the course of the said sliding.
Implant according to Claim 1, characterized in that the two elements (10, 10) are arranged head to foot.
Implant according to one of Claims 1 and 2, characterized in that the two elements (10, 10) are identical.
Implant according to one of Claims 2 and 3, characterized in that each element includes a first end part (11) including the hole or holes (111) for bone fixation screws (20), and a second end part (14) having an oblong opening (141) whose main axis defines the direction of sliding, the said opening being traversed by a projecting element (30) integral with an intermediate part (12) of the other element.
Implant according to Claim 4, characterized in that each projecting element consists of a screw (30) constituting one of the said blocking means.
Implant according to one of Claims 4 and 5, characterized in that the said intermediate part (12) of each element is situated in the extension and continuation of the said first end part (11).
Implant according to Claim 6, characterized in that the said second end part (14) of each element is situated offset in height relative to the said first end part (11) and to the said intermediate part (12) in such a way as to cover the, intermediate part of the other element.
Implant according to one of Claims 5 to 7, characterized in that each element additionally comprises a narrower joining part (13) between its intermediate part (12) and its second end part (14).
Implant according to Claim 8, characterized in that the said joining parts (13, 13) of the two elements each delimit part of a through-passage (150) of the plate.
Implant according to Claim 9, characterized in that the said through-passage (150) is oblong and has at its base a peripheral shoulder (1312).
Implant according to Claim 10, characterized in that the said shoulder (1312) is bevelled.
Implant according to one of Claims 1 to 11, characterized in that it additionally comprises at least one auxiliary anchoring screw (40).
Implant according to one of Claims 8 to 12, characterized in that the joining part (13) of each element defines at least one shoulder (1321, 1311) able to cooperate with the second end part (14) or with the intermediate part (12) of the other element, in such a way as to define a limit stop for the sliding of the two elements.
Implant according to one of Claims 1 to 13, characterized in that each bone fixation screw (20) includes an intermediate thread (22) intended to cooperate with a corresponding thread (1111) provided in the hole for the associated screw.
Implant according to one of Claims 1 to 13, characterized in that each bone fixation screw (20') includes a head (23') of generally frustoconical contour and provided with a plurality of branches (26) which are separated by interstices (27) of generally axial orientation, the conicity of the head being able to block the screw against rotation by means of the friction of the said head in the associated hole (111).
Implant according to Claim 15, characterized in that the said head (23') has a groove (261) able to cooperate with an inwardly projecting part (1112) formed in the associated hole (111) for producing axial blocking.
Implant according to one of Claims 1 to 16, characterized in that at least some of the holes (111) for bone fixation screws have an axis not perpendicular to a general plane of the plate.
Set of implants, characterized in that it comprises a plurality of implants according to one of Claims 1 to 17, with plate elements which have different numbers of holes for bone fixation screws and different orientations of holes for screws, and a plurality of bone fixation screws, and in that the different plate elements are visibly differentiated.
EP98940342A 1997-07-28 1998-07-27 Implant, in particular front cervical plate Not-in-force EP0999796B1 (en)
EP0999796A1 EP0999796A1 (en) 2000-05-17
EP0999796B1 true EP0999796B1 (en) 2003-04-16
EP98940342A Not-in-force EP0999796B1 (en) 1997-07-28 1998-07-27 Implant, in particular front cervical plate
AU2003252174A1 (en) * 2002-07-24 2004-02-09 Nas Spine, Inc. Compressible fixation apparatus for spinal surgery
BR112015003749A2 (en) * 2012-08-23 2017-07-04 Synthes Gmbh bone fixation system
2000-08-09 GBC Gb: translation of claims filed (gb section 78(7)/1977)
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