(19)
(11)EP 2 996 591 B1

(12)EUROPEAN PATENT SPECIFICATION

(45)Mention of the grant of the patent:
04.11.2020 Bulletin 2020/45

(21)Application number: 14734227.3

(22)Date of filing:  24.04.2014
(51)International Patent Classification (IPC): 
A61B 17/70(2006.01)
(86)International application number:
PCT/IB2014/060979
(87)International publication number:
WO 2014/184694 (20.11.2014 Gazette  2014/47)

(54)

ORTHOPEDIC IMPLANT KIT

ORTHOPÄDISCHES IMPLANTAT-SET

KIT D'IMPLANT ORTHOPÉDIQUE


(84)Designated Contracting States:
AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

(30)Priority: 13.05.2013 WO PCT/IB2013/053892

(43)Date of publication of application:
23.03.2016 Bulletin 2016/12

(60)Divisional application:
19152109.5 / 3505111
20196814.6
20196821.1

(73)Proprietor: Neo Medical SA
1096 Villette (CH)

(72)Inventor:
  • BEYER, Morten
    DK-8840 Rødkærsbro (DK)

(74)Representative: Grosfillier, Philippe 
ANDRE ROLAND S.A. P.O. Box 5107
1002 Lausanne
1002 Lausanne (CH)


(56)References cited: : 
EP-A1- 2 522 287
CN-U- 202 446 242
US-A1- 2006 111 712
US-A1- 2011 263 945
US-B2- 7 967 821
WO-A2-2009/114422
US-A1- 2005 192 570
US-A1- 2006 111 715
US-A1- 2013 012 999
  
      
    Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention).


    Description

    Field of invention



    [0001] The present invention relates to orthopedics and more precisely to orthopedic items such as pedicle screws, rods and spine cages. The invention also relates to instruments which are used for manipulating those items.

    Background



    [0002] US 2013/0012999 discloses an orthopedic implant kit comprising several items, in particular a pedicle screw fixed to a mounting tube made of two half-shells which can be easily disassembled.

    [0003] Pedicle screws of the prior art can be divided in two main groups:
    • Mono-axial screws: _The direction of the screw main axis is fixed with respect the screw head;
    • Poly-axial screws: The orientation of the screw main axis can be freely modified with respect to the screw head.


    [0004] When implanting a pedicle screw into a bone several steps are needed. For almost each of those steps a dedicated instrument is used.

    [0005] WO2009/114422 A2 discloses a derotation instrument with reduction functionality.

    General description of the invention



    [0006] An objective of the present invention is to reduce the number of items which are required for manipulating and fixing an orthopedic implant (pedicle screw, nut, rod, etc...).

    [0007] Another objective is to reduce the number of instruments for manipulating those items.

    [0008] Another objective is to facilitate the handling of the instruments.

    [0009] Those objectives are met with the orthopedic screw extender as in the claims.

    [0010] Described here is an orthopedic implant kit comprising a lockable poly-axial screw, a tissue dilatation sleeve, a screw driver, a screw extender, a rod, rod-reduction means, a set screw driver, a torque limiting mechanism and a screw releasing instrument.

    [0011] The lockable poly-axial orthopedic screw comprises a head and a threaded portion which form two separate elements, fixed to each other but each element may be independently oriented along a specific direction. The threaded portion may, for instance, rotates around the screw head and may adopt several possible orientations. More precisely, the threaded portion may be oriented anywhere within a conical volume, the top of the cone corresponding to the contact point between the head and the threaded portion.

    [0012] The screw furthermore comprises a locking element which, when activated, suppresses the relative movement between the threaded portion and the head. This configuration is named "mono-axial" because the threaded portion may be oriented along a single (fixed) axis with respect to the head.

    [0013] According one embodiment the locking element is a clip having a U-shape. In this case the head and the threaded portion contains cavities which are adapted to receive the branches of the U-shape clip.

    [0014] Preferably, in the mono-axial mode the head may still freely rotate around its own axis, with respect to the threaded portion. Such a mechanism may be obtained with a U-shape clip and with an annular groove located around the upper part of the threaded portion. In this case the branches of the clip are sliding within the annular groove.

    [0015] In another variation the screw head contains at least one longitudinal relief, such as a groove or a ridge, which is dimensioned in a way as to receive a corresponding relief, such as a ridge or a groove, which is located within the distal end of a screw extender.

    [0016] In another variation the screw comprises a concave seat located in the proximal end of the threaded portion and a corresponding convex shape located at the distal part of the screw head. This configuration reduces the screw length and increases the strength and the rigidity of the system.

    [0017] The screw extender according to the invention comprises a hollow cylindrical body made of two half tubes separated by two opposite longitudinal slots having an open end towards the cylindrical body distal part, this later one being dimensioned to receive and hold a screw head. The cylindrical body furthermore comprises an internal threaded part.

    [0018] According to one embodiment the cylindrical body is made of a single piece and the distal part is radially expandable by its own elasticity, in such a way as to allow an easy clipping and subsequent releasing of a screw head.

    [0019] To facilitate its radial expansion, the screw extender may include expanding means, for instance an internal rotatable tube which, when rotated pushes away the two half tubes from each other.

    [0020] In a preferred embodiment the internal part of the cylindrical body distal end contains at least one relief, such as a ridge or a groove, which is dimensioned to be received within the longitudinal relief of a screw head which includes a corresponding relief, as mentioned previously. With this configuration it hinders the distal part of the half tubes to separate from each other by its own elasticity thus making a very strong attachment between the screw extender and the screw head. An additional benefit is that the relative rotation between the screw head and the cylindrical body is avoided.

    [0021] In a preferred embodiment a rod reduction instrument is located within the cylindrical body. Advantageously the rod reduction instrument is essentially made of a shaft with a threaded distal part which is the counterpart of the cylindrical body internal threaded part. So when it is rotated within the cylindrical body the shaft may move along the cylindrical body main axis.

    [0022] In another embodiment a set screw driver is (also or alternatively) located within said cylindrical body. In this case also, the set screw driver may also essentially be made of a shaft with a threaded distal part.

    [0023] Advantageously the set screw driver comprises a torque limiting mechanism.

    [0024] In one embodiment this mechanism includes a breakable pin and a thread free rotatable shaft. The pin is laterally crossing the rotatable shaft and its ends are fixed within the threaded rotatable shaft. The threaded and the threaded free shafts are rotatably linked to each other but when a certain torque is reached the pin breaks and each shaft may freely rotates with respect to the other shaft.

    [0025] In another embodiment a screw releasing instrument is (also or alternatively) located within said cylindrical body.

    [0026] Advantageously the screw releasing instrument is essentially made of a shaft with a threaded distal part.

    [0027] In a particularly interesting embodiment, the same shaft with a threaded distal part is used for the rod reduction instrument (and potential sponylolisthesis), the set screw driver and the screw releasing mechanism.

    [0028] The tissue dilatation sleeve described here comprises a flexible conical part which is adapted to be temporarily fixed to the distal part of an instrument such as a screw extender as defined in the previous claims.

    [0029] In one example the conical part is made of several longitudinal flexible blades having each a substantially triangular shape.

    Detailed description of the invention



    [0030] The invention will be better understood in the following part of this document, with non-limiting examples illustrated by the following figures:

    Figure 1 shows an implant kit according to the invention

    Figure 2 shows an example of a lockable poly-axial pedicle screw according to the invention

    Figures 3A to 3C are cross-sections and partial cut views of the screw of figure 2

    Figure 4 represents different views (complete and partial) of the screw of figure 2

    Figure 5 shows the distal part of a screw extender according to the invention, together with the screw of figure 2

    Figure 6 is a cross section of the screw extender distal part

    Figure 7 is a global view of a screw extender with a screw

    Figures 8A to 8C represent the positioning of the rod in the screw head, rod reduction and the tightening of the set screw

    Figures 9A to 9C illustrate the release of the screw with respect to the screw extender

    Figure 10 shows a screw extender which includes a mechanism for laterally expanding the screw extender distal part

    Figure 11 is another representation of the screw extender of figure 10

    Figure 12 shows another embodiment of a pedicle screw according to the invention

    Figures 13A to 13C show different views of a rotatable shaft which is used in a rod reduction instrument, a set screw driver and a screw releasing instrument

    Figures 14 and 15 illustrate a torque limiting mechanism

    Figures 16 and 17 show the use of a tissue dilatation sleeve

    Figures 18 to 38 show a procedure using an implant kit according to the invention


    Numerical references used in the figures



    [0031] 

    1. Pedicle screw

    2. Head

    3. Set screw

    4. Threaded portion

    5. Locking element

    6. Screw extender

    7. Rod

    8. Multi-use instrument upper part

    9. Tissue dilatation sleeve

    10. Torque driver

    11. Head passage

    12. Threaded portion passage

    13. Branch

    14. Cylindrical body

    15. Slot

    16. Cylindrical body distal part

    17. Ridge

    18. Groove

    19. Screw extender internal threaded part

    20. Multi-use instrument lower part

    21. Conical part

    22. Blade

    23. Half tube

    24. Screw driver

    25. Handle

    26. Multi-use instrument (Rod reduction /Set screw driver/screw release)

    27. Rod inserting instrument

    28. Breakable pin

    29. Lateral pin

    30. Circular groove

    31. Puncturing needle/Guide wire

    32. Concave screw top

    33. Convex upper half ball



    [0032] The examples below more precisely relate to a thoracolumbar fusion system consisting of pedicle screws and rods combined with single use instruments. A typical pedicle screw system consists of the screw implants and the instruments for placing the screws.

    [0033] Figure 1 shows an example of an implant kit. This kit contains a tissue dilatation sleeve 9, a handle 25, a rod 7, a rod inserting instrument 27, a shaft 26 which can be used as a rod reduction instrument and/or a set screw driver and/or a screw releasing instrument, a pedicle screw 1, a screw extender 6 and a screw driver 24.

    [0034] The lockable poly-axial screw 1 illustrated in particular in figures 2 to 4 includes a head 2 and a threaded portion 4. Figure 2 also shows a set screw 3 which may be fixed to the head after the insertion of a rod 7. The screw 1 furthermore comprises a locking element 5 having a U-shape. When the locking element 5 is fully inserted in the screw head 2 the orientation of threaded portion 4 is blocked with respect to the head 2. Inversely, when the locking element is retrieved, the threaded portion 4 can be freely oriented with respect to the screw head 2.

    [0035] The lockable poly-axial screw may therefore be transformed into a mono-axial screw, thus allowing having mono-axial and poly-axial capability in the same product. A blocking system defined previously allows the surgeon to choose if he/she wants to use the screw in mono-axial or poly-axial mode. As mentioned mono-axial capability is achieved by pushing the locking element (clip) 5 and poly-axial capability is achieved by removing the clip 5. The clip 5 is just an example of a blocking system; other technical solutions can also be imagined such as a pin.

    [0036] Preferably, in the mono-axial mode the head may still freely rotate around its own axis, with respect to the threaded portion. Such a mechanism may be obtained with a U-shape clip and with an annular groove located around the upper part of the threaded portion. In this case the branches of the clip are sliding within the annular groove.

    [0037] Any orientation of the axis can be considered when the mono-axial is used, i.e. the screw axis and the screw head may be oriented along different directions.

    [0038] Figures 5 to 7 represent the attachment of a pedicle screw 1 to the distal end 16 of a screw extender 6, by inserting the screw head 2 within the distal end 16. In this operation the head 2 is guided with a plurality of ridges 17 located within the distal end 16 and grooves located on the head 2. With such a system the screw head is better retained within the screw extender 6.
    Any suitable material can be used for the screw extender 6(plastic, polymer, metal, etc...).

    [0039] Figures 8A to 8C represent the positioning of the rod 7 in the screw head 2, a rod reduction and the tightening of the set screw 3 in the screw head 2.
    The multi-use instrument 26 (see also figures 13A to 13B) is defined by an upper part 8 and a lower (threaded) part 20.
    The rod 7 may be pushed downwards by rotating the multi-use instrument 26 within the cylindrical body 14.
    After the rod insertion within the head 2, the set screw 3 is fixed to the head 2 by further rotating the multi-use instrument 26.

    [0040] The multi-use instrument 26 is also provided with a torque limiting mechanism (see figures 14 and 15). When the set screw 3 is fixed within the head 2 and the multi-use instrument 26 further rotated, the torque increases, up to a point where the pin 28 breaks. A further rotation of the multi-use instrument 26 has therefore no more effect on the set screw 3. From that point the further rotation of the multi-use instrument 26 only induces a downwards pressure on the screw head 2. The screw 1 is therefore progressively separated from the screw extender (see figures 9A to 9C).

    [0041] This screw releasing mechanism from an instrument offers the possibility to release the screw 1 from the screw extender without laterally expanding the screw extender 6.
    It should be mentioned at this stage that this mechanism is not limited to the release of pedicle screws. Any other item may be used.
    To summarize, the same instrument 26 can be used for rod reduction, for fixing a set screw to a screw head and for releasing a screw from a screw extender.

    [0042] It should be underlined that the invention is not limited to this triple use of the same instrument. A double use is also comprised, for instance rod-reduction and fixation of the screw set to the screw head.

    [0043] Figures 10 and 11 show an alternative solution to attach a pedicle screw to an screw extender, by rotating an inside tube (not illustrated) the half-tubes 23 are expanded by their own elasticity. This allows a screw to be inserted and fixed to it by for example clamping the outer surface around the screw. The same principle can be used as an alternative to detach the screw extender from a screw.

    [0044] The clamping system also achieves part of its rigidity, by resting on support surfaces on the screw head.

    [0045] Figure 12 shows a concave screw top 32, inside a convex upper half ball 33, allowing the rod 7 and the set screw 3 to be set lower in the screw head 2, thus decreasing the total build height, and increasing the strength and rigidity of the system.

    [0046] Figures 16 and 17 represents a tissue dilatation sleeve 9 containing four triangular flexible blades 22 intervened into each other and forming a cone 21. The cone 21 is mounted at the tip of a screw extender 6, with a tear off spiral. This allows the tissue to be pushed aside as the screw extender 6 is inserted into a body. Once in place, the surgeon may remove the sleeve 9 while the screw extender remains in the body. Any suitable number of blades can be used for forming the cone.

    [0047] Figures 18 to 38 show a procedure using the items which have been previously presented.

    [0048] In a first step (figures 18 and 19) two puncturing guide wires 31 are positioned in the spine.
    A first screw extender 6 with a screw 1 attached and surrounded by a dilatation sleeve is then inserted through the tissue (figures 20 and 21), and along the guide wire 31. The screw extender 6 is rotated and/or pushed.
    A similar operation is carried out with a second screw extender 6 and screw 1 (figures 22 and 23).
    A screw driver 24 is inserted within the screw extender 6. Its distal end is introduced within the upper part of the screw threaded portion 4. The screws 1 are then rotated and enter the vertebrae (figures 24 and 25).
    The tissue dilatation sleeves 9 are removed (figures 26 to 28).
    A rod inserting instrument 27 with a rod 7 at its end is transversally crossing the tissue (figures 29 and 30).
    The rod 7 is positioned above the screw head 2 (figure 32) and the multi-use instrument 26 is introduced within the screw extender 6, to such an extent that the set screw 3 is positioned above the rod 7, in line with the screw head 2 (figures 31 and 32).
    Figures 33 to
    36 show the rod placement within the screw heads 2 and the fixation of the set screw 3 within the screw head 2.
    Figures 37 and 38 illustrate the screw release from the screw extender 6 and the screw 1, the rod 7 and the screw set 3 in their definitive location.

    [0049] The invention is of course not limited to those illustrated examples.
    The screw extender according to the invention may be used with mono-axial, poly-axial or lockable poly-axial screws.


    Claims

    1. An orthopedic screw extender (6) for an implant kit, said screw extender (6) comprising a hollow cylindrical body (14) made of two half tubes (23) separated by two opposite longitudinal slots (15) having an open end towards the cylindrical body distal part (16), said distal part (16) being dimensioned to receive and hold a screw head (2), wherein said cylindrical body (14) comprises an internal threaded part (19), and a screw releasing instrument (26) located within the cylindrical body (14), wherein the distal part (16) of the screw extender (6) is configured such that the screw releasing instrument (26) can progressively separate the screw head (2) by downward pressure on the screw head (2) to move the screw head (2) in a direction of a main axis of the cylindrical body (14) until separated from said distal part (16) without laterally expanding the screw extender (6).
     
    2. Screw extender (6) according to claim 1 wherein the internal part of said distal end (16) includes at least one relief, including at least one of a ridge (17) and a groove, which is dimensioned to be received within at least one of a longitudinal relief and a groove of a screw head (2).
     
    3. Screw extender (6) according to anyone of claims 1 to 2 further comprising a rod reduction instrument (8) which is located within said cylindrical body (14).
     
    4. Screw extender (6) according to claim 3 wherein said rod reduction instrument is part of the screw releasing instrument (26) and is essentially made of a shaft with a threaded distal part (20).
     
    5. Screw extender (6) according to anyone of claims 1 to 4 further comprising a set screw driver (26) which is part of the screw releasing instrument (26) which is located within said cylindrical body (14).
     
    6. Screw extender (6) according to claim 5 wherein said set screw driver (26) is essentially made of a shaft with a threaded distal part (20).
     
    7. Screw extender (6) according to claim 5 or 6 wherein said set screw driver (26) comprises a torque limiting mechanism (10, 28).
     
    8. Screw extender (6) according to claim 7 wherein said torque limiting mechanism includes a breakable pin (28) and a thread free rotatable shaft (10), said breakable pin (28) laterally crossing said thread free rotatable shaft (10).
     
    9. Screw extender (6) according to claim 5 wherein said screw releasing instrument (26) is essentially made of a shaft with a threaded distal part (20).
     
    10. Screw extender (6) according to claim 9 further comprising a single shaft with a threaded distal part (20) which forms the essential part of said rod reduction instrument (8), said set screw driver (26) and said screw releasing instrument (26).
     
    11. Screw extender (6) according to any one of claims 1 to 8, wherein the cylindrical body (14) is made of a single piece forming a full cylindrical part at a proximal part of the cylindrical body (14).
     
    12. Screw extender (6) according to claim 5 or 6 wherein said set screw driver (26) comprises a torque limiting mechanism including a breakable pin (28) and a thread free rotatable shaft (10), said breakable pin (28) laterally crossing said thread free rotatable shaft (10) and the rod reduction instrument (8).
     


    Ansprüche

    1. Orthopädische Schraubenverlängerung (6) für ein Implantat-Kit, wobei die Schraubenverlängerung (6) einen hohlen zylindrischen Körper (14) umfasst, der aus zwei Rohrhälften (23) hergestellt ist, die durch zwei gegenüberliegende Längsschlitze (15) getrennt sind und ein offenes Ende zu dem distalen Teil (16) des zylindrischen Körpers hin haben, wobei der distale Teil (16) so bemessen ist, dass er einen Schraubenkopf (2) aufnimmt und festhält, wobei der zylindrische Körper (14) einen inneren Gewindeteil (19) und ein in dem zylindrischen Körper (14) angeordnetes Schraubenlöseinstrument (26) umfasst, wobei der distale Teil (16) der Schraubenverlängerung (6) so ausgestaltet ist, dass das Schraubenlöseinstrument (26) den Schraubenkopf (2) durch nach unten gehenden Druck auf den Schraubenkopf (2) fortschreitend trennen kann, um den Schraubenkopf (2) in eine Richtung einer Hauptachse des zylindrischen Körpers (14) zu bewegen, bis er von dem distalen Teil (16) getrennt ist, ohne die Schraubenverlängerung (6) lateral zu expandieren.
     
    2. Schraubenverlängerung (6) nach Anspruch 1, wobei der innere Teil des distalen Endes (16) mindestens eine Aussparung, einschließlich einer Erhöhung (17) und/oder einer Nut, aufweist, die so bemessen ist, dass sie in einer Längsaussparung und/oder einer Nut eines Schraubenkopfs (2) aufgenommen wird.
     
    3. Schraubenverlängerung (6) nach einem der Ansprüche 1 bis 2, ferner umfassend ein Stangenrepositionsinstrument (8), das in dem zylindrischen Körper (14) angeordnet ist.
     
    4. Schraubenverlängerung (6) nach Anspruch 3, wobei das Stangenrepositionsinstrument Teil des Schraubenlöseinstruments (26) ist und im Wesentlichen aus einem Schaft mit einem distalen Gewindeteil (20) hergestellt ist.
     
    5. Schraubenverlängerung (6) nach einem der Ansprüche 1 bis 4, ferner umfassend einen Stellschraubendreher (26), der Teil des Schraubenlöseinstruments (26) ist und in dem zylindrischen Körper (14) angeordnet ist.
     
    6. Schraubenverlängerung (6) nach Anspruch 5, wobei der Stellschraubendreher (26) im Wesentlichen aus einem Schaft mit einem distalen Gewindeteil (20) hergestellt ist.
     
    7. Schraubenverlängerung (6) nach Anspruch 5 oder 6, wobei der Stellschraubendreher (26) einen Drehmomentbegrenzungsmechanismus (10, 28) umfasst.
     
    8. Schraubenverlängerung (6) nach Anspruch 7, wobei der Drehmomentbegrenzungsmechanismus einen zerbrechbaren Stift (28) und einen gewindelosen, drehbaren Schaft (10) aufweist, wobei der zerbrechbare Stift (28) den gewindelosen, drehbaren Schaft (10) seitlich kreuzt.
     
    9. Schraubenverlängerung (6) nach Anspruch 5, wobei das Schraubenlöseinstrument (26) im Wesentlichen aus einem Schaft mit einem distalen Gewindeteil (20) hergestellt ist.
     
    10. Schraubenverlängerung (6) nach Anspruch 9, ferner umfassend einen einzelnen Schaft mit einem distalen Gewindeteil (20), der den wesentlichen Teil des Stangenrepositionsinstruments (8), des Stellschraubendrehers (26) und des Schraubenlöseinstruments (26) bildet.
     
    11. Schraubenverlängerung (6) nach einem der Ansprüche 1 bis 8, wobei der zylindrische Körper (14) aus einem Einzelteil hergestellt ist, das an einem proximalen Teil des zylindrischen Körpers (14) einen vollen zylindrischen Teil bildet.
     
    12. Schraubenverlängerung (6) nach Anspruch 5 oder 6, wobei der Stellschraubendreher (26) einen Drehmomentbegrenzungsmechanismus einen zerbrechbaren Stift (28) und einen gewindelosen, drehbaren Schaft (10) umfasst, wobei der zerbrechbare Stift (28) den gewindelosen, drehbaren Schaft (10) und das Stangenrepositionsinstrument (8) seitlich kreuzt.
     


    Revendications

    1. Rallonge (6) de vis orthopédique pour kit d'implant, ladite rallonge (6) de vis comprenant un corps cylindrique (14) creux constitué de deux demi-tubes (23) séparés par deux fentes longitudinales (15) se faisant face et comportant une extrémité ouverte vers la partie distale (16) du corps cylindrique, ladite partie distale (16) étant dimensionnée pour recevoir et maintenir une tête (2) de vis, dans lequel ledit corps cylindrique (14) comprend une partie filetée interne (19) et un instrument (26) de libération de vis situé à l'intérieur du corps cylindrique (14), dans lequel la partie distale (16) de la rallonge (6) de vis est configurée de telle sorte que l'instrument (26) de libération de vis peut séparer progressivement la tête (2) de vis par une pression vers le bas sur la tête (2) de vis pour déplacer la tête (2) de vis dans la direction de l'axe principal du corps cylindrique (14) jusqu'à ce qu'elle soit séparée de ladite partie distale (16) sans expansion latérale de la rallonge (6) de vis.
     
    2. Rallonge (6) de vis selon la revendication 1, dans laquelle la partie interne de ladite extrémité distale (16) comprend au moins un relief, comprenant une crête (17) et/ou une rainure, qui est dimensionné pour être reçu à l'intérieur d'un relief longitudinal et/ou d'une rainure d'une tête (2) de vis.
     
    3. Rallonge (6) de vis selon l'une quelconque des revendications 1 et 2, comprenant en outre un instrument (8) de réduction de tige qui est situé à l'intérieur dudit corps cylindrique (14).
     
    4. Rallonge (6) de vis selon la revendication 3, dans laquelle ledit instrument de réduction de tige fait partie de l'instrument (26) de libération de vis et est essentiellement constitué d'une tige avec une partie distale (20) filetée.
     
    5. Rallonge (6) de vis selon l'une quelconque des revendications 1 à 4, comprenant en outre un tournevis (26) pour vis de calage qui fait partie de l'instrument (26) de libération de vis qui est situé à l'intérieur dudit corps cylindrique (14).
     
    6. Rallonge (6) de vis selon la revendication 5, dans laquelle ledit tournevis (26) pour vis de calage est essentiellement constitué d'une tige avec une partie distale (20) filetée.
     
    7. Rallonge (6) de vis selon la revendication 5 ou 6, dans laquelle ledit tournevis (26) pour vis de calage comprend un mécanisme (10, 28) de limitation de couple.
     
    8. Rallonge (6) de vis selon la revendication 7, dans laquelle ledit mécanisme de limitation de couple comprend une clavette (28) cassable et un arbre rotatif (10) sans filetage, ladite clavette (28) cassable traversant latéralement ledit arbre rotatif (10) sans filetage.
     
    9. Rallonge (6) de vis selon la revendication 5, dans laquelle ledit instrument (26) de libération de vis est essentiellement constitué d'une tige avec une partie distale (20) filetée.
     
    10. Rallonge (6) de vis selon la revendication 9, comprenant en outre une tige unique ayant une partie distale (20) filetée qui constitue la partie essentielle dudit instrument (8) de réduction de tige, dudit tournevis (26) pour vis de calage et dudit instrument (26) de libération de vis.
     
    11. Rallonge (6) de vis selon l'une quelconque des revendications 1 à 8, dans laquelle le corps cylindrique (14) est constitué d'une seule pièce formant une partie cylindrique complète au niveau de la partie proximale du corps cylindrique (14).
     
    12. Rallonge (6) de vis selon la revendication 5 ou 6, dans laquelle ledit tournevis (26) pour vis de calage comprend un mécanisme de limitation de couple comprenant une clavette (28) cassable et un arbre rotatif (10) sans filetage, ladite clavette (28) cassable traversant latéralement ledit arbre rotatif (10) sans filetage et l'instrument (8) de réduction de tige.
     




    Drawing













































































    Cited references

    REFERENCES CITED IN THE DESCRIPTION



    This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.

    Patent documents cited in the description