FR2869215A1 - Rod maintaining device for spinal column osteosynthesis, has pedicle screws, cover, set screws and rod that are firmly and rigidly integrated with respect to each other, while being self-centered, where rod is placed across hollow body - Google Patents

Abstract

The device has pedicle screws (20), a cover (30), set screws (43) and a rod (B) that are firmly and rigidly integrated with respect to each other, while being self-centered. The rod is placed across a hollow body (1) when all the pedicle screws are implanted on vertebra, by making the rod to pass into all slots (11, 12) of the body. The set screws are screwed through an opening (3) of the body when the rod is positioned.

Description

DEVICE FOR MAINTAINING A BAR OR THE LIKE FOR OSTEOSYNTHESIS

SPINAL

  The present invention relates to devices for maintaining a bar or the like for spinal osteosynthesis, and more particularly devices of the "multiaxial" or "polyaxial" type positioning type.

  Such a holding device is already known, in particular from US-A-5 466 237 and US-A-5 474 555.

  The devices described in these documents comprise essentially a fixing screw comprising at least one bone-screwing fixation rod having a distal end and a proximal end and defining a first axis, a shoulder head comprising two faces, a first face of support for the bar and a second convex face substantially hemispherical, the two first and second faces meeting a junction section defined substantially in a plane, a spacer defining a second axis, the two ends of this spacer being respectively connected to the distal end of the fixation rod and at the apex of the second hemispherical face of the shoulder head, the cross section of the spacer in a plane perpendicular to the second axis being smaller than the junction section, and a connecting piece substantially in the form of "U", the distance separating internally the two branches of u "U" being at least equal to the thickness of the bar to be maintained, the inner face of the base of the "U" having a concave hemispherical shape complementary to the second convex hemispherical face of the shoulder head, the piece of connection comprising a through-hole according to a third axis formed in its base, the section of this through-hole being greater than the cross section of the spacer and lower than the connecting section, the fixing screw and the connecting piece being mounted in cooperating with each other so that the spacer is located in the through-hole and that the second hemispherical face of the shoulder head is located in the interior space delimited by the two branches of the U "A device such that described above is satisfactory in terms of its therapeutic application, but has disadvantages due to its relatively complex design which makes relatively it is easy for the Practitioner to manipulate for its implantation, especially as regards the means for maintaining the bar in the "U" connection piece.

  Thus, the present invention aims to provide a device for maintaining a bar or the like for spinal osteosynthesis, which largely overcomes, in particular, the disadvantages mentioned above devices of the prior art.

  More specifically, the subject of the present invention is a device for holding a bar or the like for spinal osteosynthesis, characterized in that it comprises: E a hollow body of substantially cylindrical general shape defining an axis, this hollow body comprising two first and second openings respectively at its first and second ends, the portion of the inner surface of the body bordering the second opening having a substantially frustoconical shape whose small base coincides with this second opening, E two longitudinal slots parallel to the axis of the body made in the wall of the body being diametrically opposed, the two said longitudinal slots opening at the first end of the body and having, firstly a length, along the axis of the body, less than the height of the body, and on the other hand a width at least equal to the section of the bar to be maintained, É a pedicle screw, this screw comprises ant: * a shoulder head shaped into a first spherical zone delimited by two substantially parallel planes, the center of this first spherical zone being located between said two planes and its diameter being smaller than the internal section of the body, and * a screw rod having a bone thread, the maximum section of this screw rod being smaller than the section of the second opening, said screw rod being integral with the shoulder head so that its axis is substantially perpendicular to said two planes and passes substantially through the center of the first spherical zone, the pedicle screw being positioned in the body so that the screw shank passes through the second opening and the shoulder head is located in the cylindrical interior volume of the body, an elastically deformable hood defining a cavity in the form of a second spherical zone open on a third opening, said second spherical zone being complementary to the first spherical zone, the center of this second spherical zone being located between the two planes which delimit it, the outer face of the bottom of the cap opposite the third opening being substantially flat, the outer lateral surface of the cap comprising two consecutive parts, a first portion limited by the outer face of the bottom of the cover and substantially complementary to the inner surface of the body, and a second portion of a substantially frustoconical shape complementary to the frustoconical portion of the inner surface of the body, said cover being mounted on said shoulder head and in the hollow body so that the third opening and the outer face of the bottom of the cap are respectively turned towards the second and first ends of the body, the height of the cap being greater than the distance separating the bottom slots and the second end of the body so that the bar mounted across the body through the two slots comes to rest on the outer face of the bottom of the hood, and E means for applying a bearing force between the body and the bar when, through the two slots, this last rests on the outer face of the bottom of the hood, to keep it in force against the bottom of said hood.

  Other features and advantages of the invention will emerge in the course of the following description given with reference to the accompanying drawings for illustrative but not limiting purposes, in which: FIG. 1 represents, in a partial longitudinal sectional view, the schematic diagram of a preferred embodiment of the device according to the invention, for maintaining a bar or the like for spinal osteosynthesis, FIGS. 2 and 3 show, respectively in plan view and in section, an embodiment of one of the elements constituting the device according to the invention, in this case the hood, FIG. 3 being a cross-section III-III in FIG. 2, and FIG. 4 showing a cavalier perspective view and partly in section, of a embodiment of another constituent element of the device according to the invention, in this case the substantially cylindrical body.

  It is first of all specified that, in the figures, the same references designate the same elements, whatever the figure on which they appear and whatever the form of representation of these elements. Similarly, if elements are not specifically referenced in one of the figures, their references can be easily found by referring to another figure.

  It is also stated that the figures essentially represent a single preferred embodiment of the object according to the invention, but that there may be other embodiments that meet the definition of this invention.

  It is furthermore specified that, when, according to the definition of the invention, the object of the invention comprises "at least one" element having a given function, the embodiment described may comprise several of these elements. Conversely, if the embodiment of the object according to the invention as illustrated has several elements of identical function and if, in the description, it is not specified that the object according to this invention must obligatorily comprise a number particular of these elements, the object of the invention may be defined as comprising "at least one" of these elements.

  Lastly, it is specified that, when, in the present description, an expression alone defines, without specific specific reference to it, a set of structural characteristics, [for example E = 1 (p, z, s, ...) ], these characteristics can be taken, for the definition of the object of the protection requested, when it is technically possible, either separately, [for example s, and / or z, and / or p,

  .], either in total and / or partial combination, [eg 1 (, z, p), and / or E (s, i), and / or E (t, p), and / or E (s, p)]. The present invention relates to a device for holding a bar B or the like for spinal osteosynthesis, an embodiment of which is schematically illustrated in the four figures.

  This device comprises a hollow body 1, an enlarged scale illustration of which is given in FIG. 4, which has a generally substantially cylindrical shape and which, as a result, defines an axis 2.

  This hollow body, comparable to a sleeve, has two first 3 and second 4 openings respectively at its first 5 and second 6 ends, the portion 7 of its inner surface 56 bordering the second opening 4 having a substantially concave frustoconical shape whose small base coincides with this second opening 4.

  It further comprises two longitudinal slots 11, 12 parallel to the axis 2 of the hollow body 1 made in the wall of the body being substantially diametrically opposed, these two longitudinal slots opening at the first end 5 of the body and having a share a length, taken in the direction given by the axis 2 of the body, less than the height of the body, and secondly a width at least equal to the section of the bar B to maintain so that it can be slipped into these two slots.

  The device also comprises, with reference to FIG. 1, a pedicle screw 20 which comprises a shoulder head 21 shaped as a first spherical zone delimited by two or substantially parallel planes, the center 22 of this first spherical zone being located between these two planes and its diameter being smaller than the inner section of the body.

  The screw further comprises a screw rod 23 carrying a bone thread 24 well known in itself and advantageously self-tapping, the maximum section of this screw rod being smaller than the section of the second opening 4 of the hollow body and the rod screw being secured to the shoulder head 21 so that its axis 25 is substantially perpendicular to the two planes defining the first spherical zone and passes substantially through the center 22 of this first spherical zone.

  As illustrated in Figure 1, the pedicle screw 20 is positioned in the hollow body so that its rod 23 passes through the second opening 4 and the shoulder head 21 is located in the cylindrical internal volume of the body.

  The device also comprises, with reference to FIGS. 1, 2 and 3, a cover 30 with elastic deformation defining a cavity in the form of a second spherical zone 31 at least open on a third opening 32, this second spherical zone 31 being complementary to the first spherical zone 21, the cavity 31 of the hood 30 being defined so that its center 36 is located between the two planes which delimit it.

  The cover is further arranged so that the outer face 33 of its bottom opposite the third opening 32, is substantially flat or equivalent in its general form, that its outer lateral surface 34 has two consecutive portions 37, 38, a first part 37 limited by the outer face 33 of the bottom of the cover and substantially complementary, as shown in Figure 1, the inner surface 56 of the hollow body 1, and a second portion 38 of a substantially frustoconical complementary shape of the frustoconical portion 7 of the inner surface of the body.

  With its structural features described above, the cover 30 is mounted on the shoulder head 21 and in the hollow body 1 so that the third opening 32 and the outer face 33 of the bottom of the cover are respectively turned towards the second 6 and the first 5 ends of the body.

  It is further necessary that the height of the hood is greater than the distance separating the bottom 13, 14 of the slots 11, 12 and the second end 6 of the body, so that the bar B mounted across the body through the two slots come to rest on the outer face 33 of the bottom of the cover and can not rest on the bottom 13, 14 of these slots.

  Finally, the device comprises means 40 for applying a pressing force between the hollow body 1 and the bar B when, passing through the two slots, the latter rests on the outer face 33 of the bottom of the cover, to hold it in position. force against the bottom of this hood.

  According to a preferred embodiment, these means 40 for applying a pressing force between the hollow body 1 and the bar B consist on the one hand, by the fact that the portion 41 of the inner surface 56 of the hollow body bordering the first opening 3 is of cylindrical shape of revolution and comprises a first thread 42, and secondly, by a needle screw 43 or the like comprising a central core 44 having a second thread 45 complementary to the first thread 42, so that said needle screw is adapted to be screwed into the first thread and that the penetrating end 46 of the central core 44 comes into contact with the bar B when, passing through the two slots, the latter rests on the outer face 33 of the bottom of the cover 30 .

  Advantageously, the set screw 43 comprises a head 55 integral with the emergent end 47 of the central core 44, and the device further comprises a skirt-sleeve 48 whose inner face 49 has a cross section at least equal to the cross section. the outer face 50 of the portion of the hollow body located at its first end 5, and means 51 for securing an edge 52 of this sleeve skirt 48 with the needle screw head 55 so that when the needle screw is screwed into the first thread 42, the sleeve skirt 48 surrounds the outer face 50 of the portion of the body located at its first end 5.

  This skirt-sleeve 48 makes it possible to prevent the wall portions of the hollow body 1 which are separated by the two slots 11, 12 from diverging when the screw 43 is screwed into the threaded part 41 in force.

  In a possible and industrially interesting embodiment, these means 51 for securing an edge 52 of the sleeve skirt 48 with the needle screw head 55 are constituted, as illustrated in FIG. 1, by a flange 53 secured to said edge 52 of the skirt-sleeve and a circular or equivalent groove 54 formed at the periphery of the needle screw head, this groove having a shape complementary to that of the flange so that the latter is adapted to be clipped into the groove.

  As mentioned before, the cover 30 is elastically deformed.

  In a preferred embodiment, as represented in FIGS. 1 to 3, the cover 30 consists of a part comprising a base 60 substantially defined in a base plane 61, in which an axial through-hole 62 is formed, the base 60 constituting the bottom of the hood, and a plurality of tabs 63, 64, ....

  These lugs are secured substantially regularly on the outer edge 65 of the base 60 being substantially perpendicular to the base plane 61 to define the open spherical cavity 31 defined above, the inner face 66 of each lug defining a portion of this spherical cavity 31 and thus having a curvature complementary to that of the first spherical zone 21.

  In addition, the outer face of each leg comprises two parts, Figure 3, a first portion substantially cylindrical complementary to the inner surface 56 of the body 1 and a second portion 69 bordering the free end 70 of the leg of a substantially frustoconical complementary frustoconical portion 7 of the inner surface of the body bordering the second opening 4.

  The device according to the invention is used in substantially the same way as devices of the same type of the prior art, for example to achieve osteosynthesis between two or more consecutive vertebrae or not.

  Firstly, the practitioner makes assemblies of hollow body 1, covers 30 and pedicle screws 20 as previously described and illustrated in FIG. 1, so that the frustoconical wall portion 69 of each cover fits in congruence with the frustoconical portion 7 of the inner surface 56 of the associated hollow body.

  The practitioner then places at least one pedicle screw in the bone body of each vertebra to be connected, by means of an ancillary screw-type or similar cooperating with, for example, a slot 26 made on the free face of the head of shoulder of the pedicle screw, passing the ancillary through the through hole 62 defined in the base 60 constituting the bottom of the cover 30.

  The screwing of the pedicular screws in the vertebrae is done through the bone threading carried by the screw rods, which is further advantageously chosen self-tapping.

  In this position, the body 1 and the associated cap 30 of each assembly can pivot freely relative to the pedicle screw 20 in a corner cone at the vertex of a value (3, as shown in FIG. 1, the value ( 3 of this angle depending on the section of the opening 4 and that of the screw rod.

  It should be noted that one of the advantages of the device according to the invention lies in the fact that it makes it possible to choose, for a given body 1, a pair of "pedicle screws 20 and cover 30" among several possible, to obtain a desired value f3 of the pivot angle.

  When all the pedicle screws are thus implanted in the vertebrae, the Practitioner places a bar B across the hollow bodies by passing it through all the slots 11, 12 of these bodies which can easily orient themselves, because of their possibility. pivoting in the value angle [3.

  The bar B has thus been positioned, the practitioner screws all the needle screws 43 by the first opening 3 of each body 1 until the plunging ends 46 of the central cores of these screws come into contact with the bar B firmly. , and even anchoring, while pressing it against the outer face 33 of the bottom of the hood 30.

  The force transmitted by the bar to the cowling favors the conical engagement of the frustoconical surfaces 69 and 7, which causes the flexible tabs 63, 64, ... to tighten on the spherical zone of the shoulder head 21.

  The following elements, namely: the hollow body 1, the pedicle screws 20 (shoulder heads 21 and screw rods 23), the covers 30, the needle screws 43 and the bar B, are all firmly and rigidly secured to one another. others, while automatically self centering. The vertebrae are thus firmly held fixed relative to each other to obtain, in a manner known per se, their osteosynthesis.

Claims (5)

  1. Device for holding a bar (B) or the like for spinal osteosynthesis, characterized in that it comprises: E a hollow body (1) of substantially cylindrical general shape defining an axis (2), this body comprising two first (3) and a second (4) openings respectively at its first (5) and second (6) ends, the portion (7) of the inner surface (56) of the body bordering the second opening (4) having a shape substantially frustoconical whose small base coincides with this second opening, E two longitudinal slots (11, 12) parallel to the axis (2) of the body (1) formed in the wall of the body being diametrically opposed, the two said longitudinal slots opening at the first end (5) of the body and having, firstly a length, along the axis (2) of the body, less than the height of the body, and secondly a width at least equal to the section of said bar (B) to be maintained, É a pedicle screw (2 0), this screw comprising: * a shoulder head (21) shaped as a first spherical zone delimited by two substantially parallel planes, the center (22) of this first spherical zone being situated between these two said planes and its diameter being less than the inner section of the body, and * a screw rod (23) bearing a bone thread (24), the maximum section of this screw rod being smaller than the section of the second opening (4), said screw rod being integral with the shoulder head (21) so that its axis (25) is substantially perpendicular to said two planes and passes substantially through the center (22) of the first spherical zone, the pedicle screw (20) being positioned in the body so that the screw rod (23) passes through the second opening (4) and the shoulder head (21) is located in the cylindrical internal volume of the body, E a cap (30) with elastic deformation defining a shaped cavity second spherical zone (31) open on a third opening (32), said second spherical zone (31) being complementary to the first spherical zone (21), the center (36) of this second spherical zone being located between two planes which delimit it, the outer face (33) of the bottom of the cover opposite the third opening (32) being substantially flat, the outer lateral surface (34) of the cover (30) comprising two consecutive parts (37, 38), a first portion (37) limited by the outer face (33) of the bottom of the cover and substantially complementary to the inner surface (56) of the body (1), and a second portion (38) of a substantially frustoconical shape complementary to the frustoconical portion (7) of inner surface of the body, said cover (30) being mounted on said shoulder head (21) and in the hollow body (1) so that the third opening (32) and the outer face (33) ) from the bottom of the hood respectively turned to the second (6) and first (5) ends of the body, the height of the hood being greater than the distance separating the bottom (13, 14) of the slots (11, 12) and the second end (6) of the body so that the bar (B) mounted across the body through the two slots comes to rest on the outer face (33) of the bottom of the hood, and E means (40) for applying a bearing force between the body (1) and the bar (B) when, through the two slots, the latter rests on the outer face (33) of the hood bottom, to maintain it in force against the bottom of said hood.   2. Device according to claim 1, characterized in that the means (40) for applying a bearing force between the body and the bar when, passing through the two slots, the latter rests on the bottom of the hood, are constituted by the portion (41) of the inner surface (56) of the body (1) bordering the first opening (3), this part being of cylindrical shape of revolution and having a first thread (42), and by a needle screw ( 43) comprising a central core (44) having a second thread (45) complementary to said first thread (42), so that said needle screw is adapted to be screwed into said first thread and that the penetrating end (46) of the central core (44) comes into contact with the bar (B) when, through the two slots, the latter rests on the outer face (33) of the bottom of the cover.   3. Device according to claim 2, characterized in that said set screw (43) comprises a head (55) integral with the emergent end (47) of the central core (44), a skirt-sleeve (48). whose inner face (49) has a section at least equal to the section of the outer face (50) of the part of the body situated at its first end (5), and means (51) for securing an edge ( 52) of said sleeve skirt (48) with the needle screw head (55), so that when the needle screw is screwed into the first thread (42), said sleeve skirt (48) surrounds the outer face (50) of the portion of the body located at its first end (5).   4. Device according to claim 3, characterized in that the means (51) for securing an edge (52) of said skirt-sleeve (48) with the needle screw head (55) are constituted by a flange (53) secured to said edge (52) of the sleeve skirt and by a groove (54) made at the periphery of the needle screw head, said groove having a shape complementary to that of the collar so that this collar is capable of being snapped into said groove.   5. Device according to one of claims 1 to 4, characterized in that said elastically deformable cover (30) consists of a part having a base (60) substantially defined in a base plane (61), in which an axial through-hole (62) is formed, said base (60) constituting the bottom of the cap, and a plurality of tabs (63, 64, ...), said tabs being secured substantially regularly on the outer edge (65). ) of the base (60) and being substantially perpendicular to the base plane (61) for delimiting said open spherical cavity (31), the inner face (66) of each lug defining a portion of said spherical cavity (31) and having a curvature complementary to that of the first spherical zone (21), the outer face of each lug having two parts, a first substantially cylindrical portion (68) complementary to the inner surface (56) of the body (1) and a second portion (69) bordering the free end (70) of the tab of a substantially frustoconical shape complementary to the frustoconical portion (7) of the inner surface of the body bordering the second opening (4).