WO2011070243A1

WO2011070243A1 - System for osteosynthesis, in particular of the spinal column

Info

Publication number: WO2011070243A1
Application number: PCT/FR2010/000807
Authority: WO
Inventors: Hassan Razian
Original assignee: Hassan Razian
Priority date: 2009-12-07
Filing date: 2010-12-06
Publication date: 2011-06-16
Also published as: FR2953392B1; FR2953392A1

Abstract

The present invention relates to systems for osteosynthesis. The system according to the invention comprises a block 10, a hole 12 with axis 14 between the faces 24 and 44 and with radius "Pv", one end 16 of the hole opening out via an orifice 26 with cross section "Sc" less than "2 x Pv" and being bordered by a bearing surface 18, the other end 20 having an internal thread 22, a pedicle screw 30 having a shank 32, a head 38, a cylindrical connecting rod 40 with radius "Br"; a groove 41 with radius "Br" and axis 42, the groove 41 being situated from the first axis 14 by a distance at least equal to the sum "Br" + "Pv", and a locking screw 50 comprising a shank 52 with a thread 54 complementing the internal thread 22, a locking head 56 having at least one part 58 protruding with respect to the shank 52, in such a way that, in a first position of the screw 50 with respect to the block 10, the part 58 does not bear on the rod 40 and, in a second position, the part 58 does bear on the rod 40. Application in particular but not exclusively to osteosynthesis of the spinal column.

Description

SYSTEM FOR OSTEOSYNTHESIS

The present invention relates to systems for osteosynthesis which find a particularly advantageous application for spinal osteosynthesis.

Already known systems for osteosynthesis, including spinal, which comprise at least one pedicle screw and at least one bar defined along a longitudinal axis, the pedicle screw having a U-shaped head comprising two branches and a base uniting the two branches in defining an intersbranch space, the distance between the two branches being at least equal to the largest transverse thickness of the bar, so that the bar is able to be housed in the intersbranch space, a screw rod comprising a first penetrating end and, on its outer surface, a bone thread, means for coupling the second end of the opposite screw rod to the penetrating end with the base of the head, and means for locking the bar in the intersbranch space .

According to the prior art, illustrated in particular by US-A-5 443 467, the means for locking the bar in the intersbranch space are impractical to place by the practitioner, having a nut or the like to screw around the two branches either between the two branches.

With such a system known as "tuning fork", when the intervention requires the establishment of several pedicle screws each associated with a U-shaped part, all the U-shaped parts being connected by a single bar by means of screws of when, for whatever reason, the Practitioner is obliged to change the location or position of one of the pedicle screws, he must remove all locking screws, then the bar, and then return in place all these items after removing the pedicle screw source of the problem and have it delivered optimally. All these operations and manipulations prolong the time intervention, which is a source of extra work and fatigue for the Practitioner, and especially very harmful for the patient.

Systems such as those described in US2007 / 270810 and FR2762986 are also known.

Also, the present invention aims to provide a system for osteosynthesis, including spinal, which overcomes at least a large part the disadvantages mentioned above systems of the prior art, to facilitate the work of the practitioner and reduce the duration of the procedure while securing the blocking of the elements constituting the system, and this, for the best possible well-being of the patient, even in the case where the Practitioner is obliged, as described above, to modify the provision of one of the pedicle screws.

More specifically, the subject of the present invention is a system for osteosynthesis, comprising:

a fixing block,

A through breakthrough made in said fixing block between a first opposite face and a second opposite face of said fixing block, this through-hole being defined along a first axis and having a radius of value "Pv",

* the first end of this through-hole opening on the first face by an orifice of a section of value "Se" less than "2.Pv" being bordered by a bearing surface,

the second end of this through-hole opening on the second face being bordered by a first tapping,

A pedicle screw comprising:

^* a screw rod having a first penetrating end and, on its outer surface, a bone thread, this screw rod having a cross section of a value at most equal to "Se",

* a screw head secured to the end of the screw rod opposite its penetrating end and having a section of a value greater than "Se" and at most equal to "2.Pv", said pedicle screw being adapted to be plugged into said through-bore so that the screw rod emerges from the first face of the fixing block when the screw head is received in the bearing surface,

^• a substantially cylindrical connecting bar with a radius of value "Br" revolution,

A cylindrical trough of revolution of a radius of value "Br" and defined along a second axis forming a non-zero angle with respect to the first axis, said trough being made in said fixing block so as to open on the second opposite said fixing block and that the second axis is located at a distance from the first axis at least equal to the sum "Σ" of the two values "Br" and "Pv", and

^• a clamping screw comprising a locking pin defined along a third axis and comprising a first complementary thread of the first thread, and an integral locking head of one end of the locking pin, the locking head having at least a portion protruding offset from the locking pin, said locking screw being arranged such that:

for at least a first position of this locking screw relative to the fixing block, the offset part does not close said chute and, if said connecting bar is housed in said chute, does not rest on the lateral surface of said connecting bar and the free end of the locking rod are not in contact with the screw head, and that

for a second position of said locking screw relative to said block, said offset part rests on the lateral surface of said fixing bar when the latter is housed in said chute and the free end of the locking rod is at contact of said screw head.

Other features and advantages of the present invention will become apparent from the following description given with reference to the accompanying drawings, by way of illustration but in no way limiting, in which:

FIG. 1A is a sectional view of an embodiment of the osteosynthesis system according to the invention, FIG. 1B is a sectional view, referenced BB in FIG. 1A, of the osteosynthesis system according to the invention,

FIGS. 2 and 3 show two perspective views of the osteosynthesis system according to the invention in the embodiment illustrated in FIGS. 1A and 1B, FIG. 2 showing the system in an exploded view, FIG. fully assembled representative, and

FIG. 4 represents a sectional view of a second preferred embodiment of the osteosynthesis system according to the invention.

With reference to the four appended figures, the present invention relates to a system for osteosynthesis which finds a particularly advantageous application as a system for spinal osteosynthesis, that is to say to join together several vertebrae by osteosynthesis.

This system comprises at least one fixing block 10, a through-hole 12 made in this fixing block 10 between an opposite first face 24 and a second face 44 of this fixing block, this through-hole 12 being defined along a first axis 14 and having a radius of value "Pv".

In addition, this through-hole 12 is defined in the fixing block 10, so that its first end 16 opens onto the first face 24 through an orifice 26 which can be defined either in a plane or on a more complex surface by frustoconical example as illustrated in Figure 1A. This orifice 26 has a value section, minimum if it is not circular or similar, "Se" less than "2.Pv" and is bordered by a bearing surface 18 having a shoulder function for the head 38 a pedicle screw 30 as explained below.

The second end 20 of this through-hole 12 opens out onto the second face 44 of the fixing block 10 while being lined, on the wall of the through-hole, by a first tapping 22 defined in recess with respect to this wall, as illustrated in FIG. Figure 1A.

The system further comprises at least one pedicle screw 30, of a type known in itself, comprising a screw rod 32 comprising a first penetrating end 34 and, on its external surface, a thread bone 36, this screw rod having an overall cross section of a value at most equal to "Se", and a screw head 38 integral with the end 39 of the screw rod 32 opposite its penetrating end 34 , this screw head having a section of a value greater than "Se" and at most equal to "2.Pv".

The pedicle screw 30 defined above is able to be plugged into the through-hole 12 so that its screw rod 32 emerges from the first face 24 of the fixing block 10 when its screw head 38 is housed in the surface of the support 18.

The system further comprises a substantially cylindrical link rod 40 of revolution with a radius of value "Br" and a trough 41 of cylindrical revolution of a radius of value "Br" and defined along a second axis 42 forming an angle no, preferably a right angle, with respect to the first axis 14, the chute 41 being made in the fixing block 10 so that it opens on the second face 44 of the fixing block 10 and that its axis 42 is located at a distance from the first axis 14 at least equal to the sum "Σ" (Figure 1 A) of the two values "Br" and "Pv".

According to a preferred embodiment such as that illustrated in FIG. 1A, the chute 41 has a depth Pf of value less than "2Br".

The system also comprises a locking screw 50 comprising a locking rod 52 defined along a third axis 53 and having a first thread 54 complementary to the first thread 22, and a locking head 56 secured to one end of the locking rod 52. .

This locking screw 50 is intended to be screwed into the through-hole 12 so that the free end 59 of the locking rod 52 is able to abut against the screw head 38. A preferred embodiment of this characteristic is described below with reference to FIG.

The locking head 56 further comprises at least one portion 58 protruding offset from the locking rod 52.

In addition, the locking screw 50 is arranged so that, for at least a first position of the locking screw relative to the fixing block 10, the offset part 58 does not close the chute 41 and, if the bar link 40 is housed in the chute, does not rest on the lateral surface of the connecting bar and the free end 59 of the locking rod 52 is not in contact with the screw head 38, and that, for a second position of the locking screw 50 relative to the block 10, the offset portion 58 rests on the lateral surface of the fixing bar 40 when the latter is housed in the chute 41 and the free end 59 of the rod of blocking 52 is in contact with the screw head 38.

According to another advantageous characteristic, as illustrated, the offset portion 58 has a length at least equal to the distance separating the second axis 42 and the edge closest to the throughthrough 12 so that, in the second position of the screw 50, this offset portion is adapted to rest on the highest point of the connecting bar 40, as shown in Figure 1 A.

According to another particularly advantageous and preferred feature, the second axis 42 is located at a distance from the first axis 14 equal to the sum "Σ" defined above and the first tapping 22 is made hollow in the wall of the through-hole 12 .

In this case, the side wall of the connecting bar 40 is tangent to the through-hole 12 and the recessed tapping 22 is intersecting with the cylindrical envelope of the connecting bar 40. There then exists a window 49, FIG. which connects the through-hole 12 with the possible position of the connecting bar 40 in the trough 41.

It is therefore preferable for the first thread 54 to be made in such a way that, when the locking screw 50 is in one of its first positions defined above, there is no part of this thread 54 which plunges into the chute 41, this to facilitate the establishment of the connecting bar 40 in this chute. To do this, it is sufficient to remove the thread portion contained in a cylinder sector limited by the plane which is tangent both to the through-hole 12 and to the chute 41, this part removed from the thread 54 being illustrated by the cylindrical sector 52-SC in Figure 4. Thus, when the connecting bar 40 is positioned in the trough 41 and the locking screw 50 is screwed into the first internal thread 22, the thread of the first thread 54 is printed in the side wall of the bar 40. which contributes to its maintenance in the chute as will be explained below.

To further ensure the maintenance of the connecting bar 40 in the trough 41, according to a preferred embodiment, the fixing block 10 has a portion 60 secured to its second face 44 projecting from the second face 44 and bordering the trough 41, either tangentially or at a relatively small distance, as in the example illustrated in FIG. 1A, so as not to close off the inlet of this trough 41.

This block portion 60 is located at a distance from the first axis 14 by a value at least equal to the sum "Ω" of the "2.Br" and "Pv" values defined above, FIG. 1A.

According to this preferred embodiment, in addition, the offset part 58 of the locking head has a determined length so that, when the locking screw 50 is in its second position defined above, this offset part 58 is suitable for cooperate with the block portion 60 by temporary blocking means 70.

These temporary blocking means 70 may be of any type. However, very preferably, they are constituted, as illustrated in the figures, by a second tapping 72 made in the block portion 60 being centered on the first axis 14 and having the same pitch as the first tapping 22, and by a second thread 74 formed at the end of the offset portion 58 being centered on the first axis 14 and having the same pitch as the first thread 54 so that, when the locking screw 50 pivots about the pins 14 and 53, the second thread 74 is adapted to be screwed into the second thread 72.

For this screwing to be possible, the locking screw 50 is made in one piece, on which the first and second threads are made. 54, 74 during a single pass on a machining lathe. It will be the same in block 10 for the first and second threads 22 and 72.

According to a preferred embodiment, the locking screw 50 comprises an axial hole 80 defined along the third axis 53 and passing right through the blocking rod 52 and the locking head 56.

It is also preferred to make a blind hole 81 in the screw head 38, these two holes, the through axial hole and the blind hole, having polygonal cross sections to be able to receive a screwdriver such as a screwdriver or the like. According to a possible and preferred embodiment, these two holes have identical cross sections in the form of a "six-sided" shape.

As described above, the system comprises a bearing surface 18 for supporting the screw head 38 when the pedicle screw 30 is plugged into the through-hole 12. According to a second preferred embodiment, to adjust the position of the block of fixing 10 relative to the screw head 38 of the pedicle screw 30, this screw head 38 is of substantially spherical shape (FIG. 4) of radius "Pv" and the bearing surface 18 is of a spherical shape complementary concave of radius of value "Pv".

FIG. 4 represents a detail of the system according to this embodiment which is advantageous for allowing an easier orientation of the pedicle screw with respect to the fixation block 10 when the pedicle screw is of the polyaxial type well known in itself.

In this case, the free end 59 of the locking rod 52 is shaped concave spherical surface substantially of the same radius as the screw head 38 of the pedicle screw 30, to come to rest on it by marrying a spherical part of this head screw, as shown in Figure 4.

In this second embodiment, the axial through hole 80 is advantageously cylindrical of revolution and comprises, on its wall, a third thread 83 in which is screwable a fixing screw 85, shown in phantom in FIG. needle-like type or the like, for locking the screw head 38 of the pedicle screw 30. When it is screwed fully into the hole 80 until anchored in the screw head pedicle 38, this fixing screw 85 constitutes a second securing security of the pedicle screw head 38 with respect to the locking screw 50 and therefore with respect to the block 10.

The system according to the invention as described above is used as follows:

It is firstly specified that such a system generally comprises several fixing blocks 10 interconnected by a connecting bar 40, each block being connected to a vertebra with at least one pedicle screw 30.

This having been specified, to secure several vertebrae together, the Practitioner begins by defining the direction of the positioning of the connecting bar 40 and, on each vertebra, the implantation point of a pedicle screw 30.

He plugs a pedicle screw 30 into the through-hole 12 of each block 10 and, with a screwdriver plugged into the blind hole 81 of the screw head 38 through this through-hole, it screws each screw rod 32 into the corresponding vertebra .

Then, it positions a connecting bar 40 in the troughs 41 of all the fixing blocks 10 which are connected to the pedicle screws relatively loosely.

While maintaining the connecting bar 40 in the trough 41 of a first fixing block 10, it screws a first locking screw 50 so that its locking rod 52 having the first thread 54 complementary to the first thread 22, is screwed in this first tapping 22. It rotates the locking screw 50 about its axis 53 so that the second thread 74 of the offset part 58 comes to cooperate with the second tapping 72 of the block portion 60.

As the locking screw 50 pivots, its locking pin 52 sinks into the through-hole 12 and the thread of the first thread 54 is printed in the wall of the bar 40, until the free end 59 of this locking rod comes to rest on the pedicle screw head 38 and that the offset portion 58 bears on the connecting bar 40. This configuration defines the second position of the locking head relative to the fixing block mentioned above. It is then sufficient for the Practitioner to stop screwing the locking screw 50 after a relatively strong tightening, so that the pedicle screw 30, the locking screw 50, the connecting bar 40 and the fixing block 10 are all firmly attached. one another.

It practices in the same way with all the other connecting blocks 10 and all the locking screws 50 so that all sets "pedicle screw, locking screw, connecting bar, fixing block" are integral and allow to reach the purpose of such a system which, in known manner, is to bind severally several vertebrae together to prevent the patient from suffering.

By cons, it is also possible that the part of the system comprising a block 10, the pedicle screw 30 and the locking screw 50 is pre-assembled at the factory and delivered in this form to the Practitioner to facilitate the work and minimize the number of his interventions on the equipment, being specified that, of course, the pedicle screw 30 is not blocked by the locking screw 50 which is then in one of its first positions mentioned above.

More specifically, to facilitate the work of the Practitioner, the system is presented to the Practitioner so that the first position of the locking screw 50 is the one that is, when screwing, just before its second position.

Advantageously, this first position is further defined by means of a small stop 100 made on the face 44 of the block 10, FIG. 3, which is easily surmountable by the locking head 56 during the screwing of the locking screw 50 but which prevents this locking screw 50 from being easily unscrewed.

This therefore allows the practitioner to know that, to lock the bar 40 in the chute 41, it is sufficient, after having implanted the pedicle screw 30 and positioned the bar 40 in the chute 41, to rotate the locking head 58 only d a quarter of a turn, to block everything as explained above. In fact, such a quarter turn is largely sufficient because the pitch of the tapping 22 and the complementary thread 54 is relatively large.

After this manipulation on all locking screws, it is sufficient for the Practitioner to permanently block all implanted pedicle screws 30 relative to the blocks 10 by tightening the fixing screws 85 to bring them firmly into contact with the pedicle screw heads 38.

Such a system is very advantageous, especially compared to similar systems of the prior art which attempt to achieve the same purpose as that according to the invention, because, for any reason, one of the pedicle screws 30 implanted must be removed, simply remove the locking screw 50 which covers the head 38 of the pedicle screw creating problem, unscrew this pedicle screw out of the fixing block 10 through the through-hole 12, which can to be done without any difficulty and especially without having to act on the other fixing blocks 10 and the other locking screws 50, without having to remove and / or move the connecting bar 40. The fixing block 10 whose pedicle screw 30 has been removed can even be removed very easily.

This last advantage is obviously very appreciable for Practitioners, as well as for patients, since the duration of the intervention is greatly reduced compared with that required with similar systems of the prior art.

Claims

1. System for osteosynthesis comprising:

A fixing block (10),

A through-hole (12) made in said fixing block (10) between a first opposite face (24) and a second face (44) of said fixing block (10), this through-hole (12) being defined according to a first axis (14) and having a value radius "Pv",

* the first end (16) of this through-hole (12) opening on the first face (24) through an orifice (26) of a section of value "Se" less than "2.Pv" being bordered by a surface of support (18),

* the second end (20) of this through-hole (12) opening on the second face (44) being bordered by a first tapping

(22)

A pedicle screw (30) comprising:

^* A screw shaft (32) having a first penetrating end (34) and, on its outer surface, a bone thread (36), said screw shaft having a cross-section of a value at most equal to "Se",

* a screw head (38) integral with the end (39) of the screw rod (32) opposite its penetrating end (34) and having a section of a value greater than "Se" and at most equal to "2.Pv"

said pedicle screw (30) being adapted to be plugged into said through-hole (12) so that its screw shaft (32) emerges from the first face (24) of the fixing block (10) when its screw head (38) ) is housed in the bearing surface (18),

A substantially cylindrical connecting bar (40) of revolution having a radius of value "Br",

A chute (41) cylindrical of revolution of a radius of value "Br" and defined along a second axis (42) forming a non-zero angle with respect to the first axis (14), said chute (41) being made in said block of fixing (10) so that it opens on the second face (44) of said fixing block and that the second axis (42) is located at a distance from the first axis (14) at least equal to the sum "Σ" both "Br" and "Pv" values, and

A locking screw (50) comprising a locking rod (52) defined along a third axis (53) and having a first thread (54) complementary to the first internal thread (22), and a locking head (56) integral with one end of the locking pin (52), said locking head (56) having at least one portion (58) protruding offset from the locking pin (52), said locking screw being arranged than :

for at least a first position of this locking screw

(50) relative to the fixing block (10), the offset part (58) does not close said chute (41) and, if said connecting bar (40) is housed in said chute, does not rest on the lateral surface of said connecting bar and the free end (59) of the locking rod (52) is not in contact with the screw head (38), and that

for a second position of said locking screw (50) relative to said block (10), said offset part (58) rests on the lateral surface of said fixing bar (40) when the latter is housed in said chute (41) and the free end (59) of the locking rod (52) is in contact with said screw head (38).

2. System according to claim 1, characterized in that said offset portion (58) has a length at least equal to the distance separating the second axis (42) and the edge closest to the through-hole (12).

3. System according to one of claims 1 and 2, characterized in that the second axis (42) is located at a distance from the first axis (14) equal to the sum "Σ" and the first tapping (22) is hollowed out in the wall of the through-hole (12).

4. System according to one of claims 1 to 3, characterized in that said fixing block (10) comprises a portion (60) integral with said second face (44) and projecting from said second face (44) bordering said chute (41), said block portion (60) being located at a distance from the first axis (14) at least equal to the sum " Ω "values" 2.Br "and" Pv ", the offset part (58) of the locking head having a determined length so that when said locking screw (50) is in its second angular position, this offset portion (58) is adapted to cooperate with the block portion (60) by temporary locking means (70).

5. System according to claim 4, characterized in that the temporary locking means (70) are constituted by a second thread (72) formed in said block portion (60) being centered on the first axis (14) and having the same pitch as the first thread (22), and by a second thread (74) formed on the offset portion (58) being centered on the first axis (14) and having the same pitch as the first thread (54). ).

6. System according to one of the preceding claims, characterized in that the locking screw (50) comprises an axial hole (80) defined along the third axis (53) and passing right through the locking rod (52). ) and the locking head (56), and a blind hole (81) is formed in the screw head (38).

7. System according to one of the preceding claims, characterized in that the screw head (38) of the pedicle screw (30) is substantially convex spherical shape, said support surface (18) is concave shape concave spherical complement of said screw head (38) and that the free end (59) of the locking rod (52) is shaped concave spherical surface substantially of the same radius as said screw head (38) of the screw pedicle (30).

8. System according to claims 6 and 7, characterized in that said axial hole (80) comprises, on its wall, a third thread (83) in which is able to screw a fixing screw (85) to lock said screw head (38) of the pedicle screw (30).

9. System according to one of the preceding claims, characterized in that said chute (41) has a depth (Pf) of less than "2Br".

10. System according to one of the preceding claims, characterized in that the first position of the locking screw (50) which is, when screwing said locking screw (50), that just before the second position, is defined by a small stop (100) made on the second face (44) of the fixing block 10, this stop (100) being easily overcome by the locking head (56) during the screwing of the locking screw (50), but preventing this locking screw (50) from being easily unscrewed.