WO1990011727A1

WO1990011727A1 - Fixing device for orthopedic use

Info

Publication number: WO1990011727A1
Application number: PCT/FR1990/000251
Authority: WO
Inventors: Jean-Marie Hardy
Original assignee: Hardy Jean Marie
Priority date: 1989-04-11
Filing date: 1990-04-10
Publication date: 1990-10-18
Also published as: EP0423299A1; JPH03505295A; CA2031302A1; FR2645428A1

Abstract

Fixing device for orthopedic use comprising jaws (5) (9) (46) (47) which co-operate with fixing means (10) which in turn co-operate with the elements to be fixed, at least one main member (1), and intermediary elements (38) (52) (53) (60) (66) (78) (79) (82) (83) (85) designed to fulfil a specific function, said jaws (5) (9) (46) (47), said main member(s) (1) and said elements (38) (52) (53) (60) (66) (78) (79) (82) (85) having fittings which allow them to be joined together, as required either directly or by means of separate articulation members (3) (4) (7) (8) (2b) (27) (29), to constitute a modular structure with a capacity for angular orientation on different planes and/or linear adjustment.

Description

_ _ι _

Fixator for orthopedic intervention.

The invention relates to a monolateral fixative, in particular for orthopedic intervention. Of course, such a fixer can find applications in the very varied fields of the reconstruction of broken objects. However, to fix ideas and by way of example, reference will be made to the specific field of application of orthopedics.

A certain number of types of monolateral fixators are known, which generally present a certain number of drawbacks, the most important of which are: heaviness, while it is obviously advisable to lighten the patient as much as possible,

- a final rigidity when it is more and more frequently necessary to modify the geometry of the fixator during the post-operative period, the mounting complications which are incompatible with an ease of intervention of the surgeon.

This state of the art can be illustrated by the teaching of the patents EP N. 0024256 (JF ORTHOPEDIE) or GB N. 2168255 (0RTH0FIX). The fixers described in these documents are relatively heavy and very monolithic in the sense that they allow, during their installation, movements and limited amplitude adjustments. Once implanted, it is not allowed to make significant alterations or adjustments which are most often essential.

Due to their design, the various constituent elements can only be oriented according to a reduced angular range.

In ORTHOFIX patent N. 2168255, one cannot go beyond a conical solid angle of 34 ° of total opening. In the apparatus of the type of that taught by patent EP 0024256, even if the complete rotation around the axis of this conical solid angle is possible, the field of action is considerably limited.

With this type of fixator, we are practically in the absolute necessity to work on reduced fracture, which turns out to be very delicate in reality. It is indeed very difficult to reduce the fracture, to contain it by any means and to place the fixative on the reduced fracture. Generally, we proceed as follows:

The fracture is reduced and fixed on either side of the jaw fracture, by means of pins for example, said jaws being temporarily coupled by a jig. It is then necessary to remove the template and install the fixative. This system does not solve the problem of the reduction itself, nor the way in which the bone fragments are maintained during the installation of the template or during the removal of the templates and the installation of the fixator.

In these conditions, it is difficult to install this type of fixator for reduced fractures since, on the one hand, the reduction is delicate, and, on the other hand, it is random to temporarily contain the fracture. For these various reasons, such fixators are most often used, not for fresh fractures, but for lengthening, pseudo-arthritis or the like. Another drawback is that these fixers are not designed to be combined with other elements, which can also be inconvenient in some cases. For example, the fixation of certain bones may require the use of rings encircling the limb to be repaired, as is the case, for example, with the fixers described in patent application FR N. 8602818 filed on February 28, 1986 .

• The invention has set itself the aim of remedying these drawbacks in a simple, efficient and rational manner. The problem which the invention proposes to solve is to be able to work on unreduced fractures and to adapt the whole of the fixator as a function of the fractures, whatever the geometric shapes, while being capable of dealing with all cases. of figures, in particular by equipping a part of the fixer with relay elements of design determined according to the interventions to be carried out.

Such a problem is solved in that the fixator comprises jaws capable of cooperating with fixing means cooperating with the elements to be fixed, at least one main body and intermediate elements shaped to fulfill a specific function, said jaws, said one or more body and said elements having arrangements to allow direct or via attached articulation members, their coupling at will to constitute a modular assembly at the level of its structure with capacity for angular orientation in different planes and / or linear adjustment.

The articulation members are constituted by complementary parts with the capacity of angular movement over at least 180 ° and of disassembly with respect to each other to separate the body and / or the jaw and / or the elements at will.

The complementary parts of the articulation members are of the male and female type connected by a removable common axis.

The body receives free sliding at least one piston mounted free in rotation and one end of which is integral with one of the parts of the articulation members.

It therefore appears that the fixer according to the invention, taking into account the totally modular and removable nature of its constituent elements, makes it possible to cope with all the FR90 / 00251 m. 4 _.

cases and working on unreduced fractures. Not only do such arrangements prove advantageous intraoperatively, but also postoperatively.

An important problem which makes it possible to solve the characteristics of the invention, is to be able to adapt the fixator having regard to the constraints which appear post-operatively, but do not necessarily appear intra-operatively. It is difficult to predict the forces that will apply at the level of the fixator when the patient is lying down. It follows that after having correctly positioned the fixator, there may appear a certain offset under the effect of the loads caused in particular by the weight of the patient.

According to the invention, it is possible to equip the fixator with added elements capable of permanently adjusting said fixator. To resolve this problem, still having the objective of having a fully modular fixator, the added elements are fixed to a part of the body and / or of the jaws with a fixed angular position or with angular orientation capacity by means of the organs of 'coupling.

The elements consist of turnbuckles of variable length. The elements consist of a bar or rod on which moves in successive increments, a cursor constituted by a sleeve sliding on the bar or rod and provided with locking means in position, a threaded ring cooperating with a threaded part of the sleeve, and being mounted free in rotation on a second sleeve also sliding on the bar or rod on which it can be locked in position by means, the movement of the assembly being made by locking in position of one of the sleeves, screwing or unscrewing between ring and threaded part, blocking the other sleeve, unlocking the first, and and so on.

The turnbuckles comprise two parts mounted on a housing and for at least one, by means of a slider sliding transversely with respect to said parts along a worm screw rotating in a common housing, controlled in rotation by the exterior by rotation of the ends of the screws, thus ensuring a translational offset between said parts. Each slider has several fixing points for the turnbuckle parts.

The housing is separated into two parts articulated on a common axis substantially parallel to the parts of the turnbuckle.

Another problem which the invention proposes to solve lies in the jaws as such, avoiding inducing a line of weakness on the bone resulting from their method of fixation. Generally as is clear from GB patent 2168255, the jaws have a series of aligned positions allowing the passage of screws or pins. The disadvantage of such a system is that, in certain cases, the drilling of aligned holes and even with a coplanar axis, in particular in a long bone, can initiate cracking between the different holes which can lead to another fracture. It is therefore essential to be able to have jaws that do not have aligned holes.

Such a problem is solved in that the clamping holes situated at the interface between jaws are not with coplanar axes.

Another problem which the invention proposes to solve and which is not resolved according to the state of the art, is to give the fixer a so-called property, active dynamics. In conjunction with the use of particularly rigid elements, it is possible to incorporate at least one elastic element allowing not a pure droop but a droop with a stress which can be dosed and used at the chosen time.

Such a problem is solved in that a spring housed in the body is wedged between a part of the body and the piston. Said piston is pierced axially inwards and receives the spring there. A shim is inserted between the piston and the spring _*

Another problem which the invention proposes to solve is to correctly place the jaws on an unreduced fracture, namely a jaw above the fracture and a jaw below. The problem is to have a perfect alignment of the pins perpendicularly and horizontally on each of the parts above and below the fracture.

Such a problem is solved in that a viewfinder has been designed for the installation of fixing means for fixer. To this end, in a block transparent to X-rays, are drilled right through at least one guide hole identified by a reticular device opaque to X-rays and passing through the axis of the holes. The reticular device includes platelets and series of coplanar wires.

The invention is set out below in more detail using the appended drawings, in which:

Figure 1 shows a first embodiment of the modular .fixer according to the invention applied to a femur.

FIG. 2 is a plan view and in partial section of a fixator as shown in FIG. 1.

Figure 3 is a partial sectional view of the various main components. FIGS. 4a to 4e represent the stages of mounting a fixator as shown in FIGS. 1, 2 and 3.

Figure 5 is a perspective view of the main reticular part of the viewfinder according to the invention.

Figures 6 and 7 are respectively a sectional view and an elevational view of an epiphyseal assembly produced on a tibia.

Figures 8a to 8e show five variants of epiphyseal mounting on a tibia.

Figures 9a to 9e show the different phases of mounting a fixator in an osteotomy case.

Figures 10a to 10c are alternative arrangements for elongation. Figure 11 shows in section a cursor for bars.

Figure 12 is a sectional view of a body fitted with a spring.

Figure 13 is a sectional view of a basin equipped with a fixer according to the invention.

Figure 14 is a sectional view of an embodiment of the jaw according to the invention.

FIG. 15 shows in axial section a turnbuckle device with lateral offset according to the invention.

In Figure 1, there is shown a first embodiment of single-sided fixing device according to the present invention. It comprises a body (1) in which slides and rotates a piston (2) whose external end has the female part (3) of a joint whose male part (4) is connected to a jaw (5). At the other end of the body (1), a plug (6) carries the female part of a joint (7), the male part (8) of which is - o -

connected to a jaw (9). The jaws (5) and (9) enclose a number of pins, rods or screws 10 fixed in the bone under the conditions which will be described below.

It will be noted immediately that if, in this FIG. 1, the body (l) has a piston (2) and a plug (6), in variants which will be described below, the body may not be fitted with one piston but two; each being capable of both sliding to adjust the length of the assembly and of rotating 360 °. As also, the articulations (3), (4) and (7), (8) allow a movement of at least 180 ° around any axis perpendicular to the axis of the assembly, it is clear that, by relative to the body, the jaws (5) and (9) can take all the orientations in a solid angle covering at least one hemisphere.

Referring to Figure 2, we find most of the elements of Figure 1 with the same reference numbers. The body (1) has the shape of an elongated tube, preferably with flat faces so as to allow, on each of the faces, for example 4 faces, to drill holes (11) which will be seen to be useful in what follows. The body (1) is axially bored to allow the establishment of a piston (2), the other end being closed by a plug not shown in the figure, or two pistons (2) and (2 '). The piston (2 ') is shown here in section and it is noted that this piston is itself axially pierced at (12). The usefulness of this axial drilling will appear later in the description. The end of the pistons (2) and (2 ') is connected to the female parts (3) and (7) seen one in plan, the other turned 90 ° relative to the first.

In these female parts, the male parts (4) and (8) are articulated by means of axes (13) and (14) mounted by any conventional system but possibly of so that they can be removed easily. It may be, in particular, an axis whose end is threaded so that it can be screwed into one of the wings of the female part and whose head has, for example, a hexagonal hole to allow it fixation. The male parts (4) and (8) thus articulated in the female parts (3) and (7) are screwed into the jaws (5) and (9) either directly, as is the case of the jaw (9) , by means of a thread and a locking nut (15), either by means of a threaded length adjusting part, as is the case for the jaw (5), with a locking nut (16 ) and a length adjusting nut (17).

Each jaw (5) (9) is essentially composed of two jaws (5 ') and (5 ") (not visible in Figure 2), (9') and (9"), visible since the jaw is turned 90 ° relative to its axis by comparison with the jaw (5). These two parts are capable of coming together thanks to head screws having a polygonal hole (18), so as to allow the blocking between the jaws in grooves (19) provided for this purpose on either side of the interface between the parts (9 ') and (9 "), of rods, screws or pins such as (10) (figure 1). It will be noted that, in this figure 2, the grooves (19) provide holes for generally substantially circular shape which are aligned in the same plane, and could, without departing from the scope of the invention, affect other shapes, and in particular, for example, diamond sections to ensure better tightening. Like the body (1), the jaws (5) and (9) may have a series of holes such as 20, preferably threaded, on one or other of the parts (5 '), (5 ") , (9 '), (9 "), as well as axial holes such as the one where the male parts (4) and (8) are mounted and an opposite hole ^' at the other end of the macho ires, not shown in Figure 2. These different holes (20) allow the attachment of several jaws on top of each other, including - 10 -

we will see the usefulness later.

In FIG. 3, we will find, with the same reference numbers, a certain number of elements of FIGS. 1 and 2. The body (1) is bored longitudinally so as to be able to receive, as has been mentioned above, a piston (2) and a plug (21) or two shorter pistons. The translational locking of the pistons (2) can be carried out by means of a screw (22) for example, engaged in the thickness of the body (1) in a position of quasi-tangency with the generatrices of the piston (s), said screw with a flat. This allows, in particular, to adjust the length of the assembly, that is to say that corresponding to a more or less protrusion of the piston outward. One can also provide a wedge (23) on the piston, to allow either to wedge it longitudinally thanks to a screw tightened in a threaded hole (24) and coming to press on the external wall of the piston (2), or to wedge another element of the kit on said piston.

Here we find the different elements (3), (4), (13) of the joint and whose end (25) of the male part (4) is threaded and carries the timing nut (16) allowing a ^" blocking against the jaw (5) when the threaded part (25) is screwed into one of the holes (20) of the jaws. Leé two jaws (5 ') and (5") of the jaw (5) appear here in cut as well as the holes (20).

The holes (18) allow the threading of screws which tighten in the threaded part in the jaw (5 ") of the jaw (5). We also find here, the holes (19) for the passage of the pins, rods or screw (10). Also shown in this figure 3, a number of elements which can be screwed into the different holes (11) of the body (1) or the holes (20) of the jaws (5) or (9) (Figures i and 2). These various elements can be constituted by threaded rods (26) equipped with a tightening nut, with seals such as (27) making it possible to rotate around the axis and having a jaw system (28) making it possible to grip a smooth bar, or a bar or threaded rod if the jaws (28) are themselves threaded. The part (29) with two equally threaded ends is a simple articulation allowing a rotation of 90 ° around the axis and which can be used to support several accessories, as will be described below.

If we now refer to FIG. 4, we have shown the successive phases of setting up a modular fixing assembly in accordance with the preceding figures on a fractured tibia (30), the associated fibula (31) of which is also fractured. As will be seen, FIGS. 4a to e represent the phases of this setting up of the fixing assembly, the constituent elements of which are removable and easily interchangeable. The first phase consists of the respective positioning of the jaws (5) and (9) on the upper and lower parts of the tibia (30). To do this, a viewfinder as shown in FIG. 5 is used.

This viewfinder essentially comprises a block (32) transparent to X-rays in which are drilled one or more guide holes (33) perpendicular to the upper and lower parallel faces of the block, or, in certain particular cases, of a given inclination. This transparent block (32) is held on its periphery by any suitable support device, preferably a frame provided with a handle to facilitate handling. The frame is not necessarily transparent to X-rays. Each of the holes (33) is defined axially with respect to a reticular system constituted, for example, by strips (34) (35) crossing on the axis of the one of the holes (33), and which they are not radiolucent. In this way, when the viewfinder is placed under fluoroscopy, it is possible to easily define whether the axis (33) is placed upright or if it is inclined. If it is placed upright, the image of each of the strips (34) and (35) must be reduced to a line whereas if the hole (33) is inclined relative to the fluoroscopy, the strips (34) and ( 35) appear all the wider as they are oblique to the sight, for example, in the form of parallelograms if these slats are rectangular. We can also replace the slats by parallel wires in the upper part and in the lower part, which will play the same role or by more than two wires located in the same plane. According to the techniques used, this sight will allow either to pass a needle and to orient it during its penetration in the bone, or to ensure a drilling, or to pass a hollow drill around the needle once the sight removed, either to pass a screw. The viewfinder may include a number of holes side by side (33) whose spacing and position corresponds to the spacing and position of the holes (19) of the jaws (5) and (9) (see FIG. 14) . It is also possible to use a sight with a single hole combined either with a template corresponding to the holes (19) of the jaws (5) or (9), or a jaws itself; the aim being finally to fix the rods, pins or screws (10) in the upper and lower parts of the tibia (30) and in positions such that, when the jaws (5) and (9) are mounted, these elements (10) are located exactly in the holes (19) provided. This in particular avoids introducing twists or any other additional constraint by having to deform the elements (10) so as to pass them through the holes (19) provided in the jaws (5) or (9).

The screws (18) are then tightened and the jaws are thus fixed on the fixing elements (10). The choice of rods, pins or screws obviously depends on the operating conditions and the choice of the surgeon. When the jaws (5) and (9) are fixed, we are in the state shown in Figure 4b.

Then mounted on the jaws (5) and (9) (Figure 4c) rods (36) such as (26) shown in Figure 3, on which are fixed joints (37) having two elements, one of which is screwed at the desired distance on each of the rods (36) and the other in the form of a jaw allows the mounting and locking in position, by any suitable means, of a bar (38) of any conventional type. This bar (38) is, for example, constituted by two tubes (39) and (40) into which are screwed two parts with reverse threads of a part (41) having, in the central part, a fixed nut (41) by hexagon example. On either side of this fixed nut (41), two nuts (42) and (43) allow the piece (41) to be blocked respectively with respect to the tubes (40) and (39). When the fixed nut (41) is turned, it rotates the corresponding threaded part and the reverse threads make it possible to move apart or bring the tubes (39) and (40) apart according to the direction of rotation of the nut (41). When the bar (38) is mounted on the joints (37), it is left free, reduction is then practiced by fixing the bar at these two ends in the joints (37) and by acting under radioscopy on both 'nut (41) and on the tibia (30) and the fibula (32) to ensure a reconciliation in the best conditions.

When the reduction is considered to be correct, the bar is blocked by means of the nuts (42) and (43) and, therefore in relative position, the two jaws (5) and (9) and the body can then be mounted ( l) and its joints (3) and (7) between the two jaws (5) and (9). Since the piston or pistons allow a relative rotation of 360 ° between the articulations (3) and (7), and that they also allow an adjustment of the distance between these articulations (3) and (7), which allow elsewhere, a rotation of 180 ° by relative to perpendiculars to the axis of the body 1, there are sufficient degrees of freedom to be able to mount the assembly (1) (3) (7) by successive elements or in a single block between the jaws (5) and ( 9). When the installation is done, the different nuts and screws (15) (16) and (22) are blocked to stiffen the fixing assembly (5), (3), (l), (7), (9) . We are then in the situation represented in FIG. 4d.

We can then remove the bar (38) and its elements (36) and (37) dq support and connection to the jaws (5) and (9) and we are then in the position shown in Figure 4e.

Note that the jaws having, on their different faces, holes (20), it is possible to mount either a single bar (38) as shown in Figure 4, or two and even three bars. It will also be noted that the body (1) can, if desired, be replaced by bars such as (38) with adjustable length, and this with or without joints (3) and (7). The absence of joints obviously requires a coaxial mounting of all the jaws

(5), (9) and of this bar (38) interposed between them. This then allows, taking advantage of the holes (20) to mount not only a system with two or three bars, but also with four bars.

As a variant, with the provisions of the example which has just been described, and taking into account the modular nature of the fixator, an epiphyseal assembly can be carried out. For this, reference is made to FIGS. 6 and 7 which respectively represent such an assembly in section and in elevation.

In Figure 7, we find the jaws (5) and

(9), the body (1) and the joints (3) and (7), but, on the jaw (9), in the holes (20), we mounted joints (44) and (45) of the same type as those described above, and two jaws (46) and (47). Figure (6) shows the arrangement of the different jaws, the jaw (9) being axially substantially parallel to that of the tibia (30) while the jaws (46) and (47) are transverse.

Referring to Figures 8, there are shown different types of epiphyseal arrangements. In FIG. 8a, there are the three upper jaws (46), (9) and (47), the body (l) and the lower jaw (5). This is a centered monolateral system. We can also consider a three-bar system by fixing, in the holes (22) of the body (1) threaded rods (48) and (49), on which we mount the joints (50) and (51) equivalent to the joints (37) of Figure 4, as well as bars (52) and (53) which are fixed in the holes (20) of the jaws (46) and (47) (Figure 8b). It is therefore a three-bar system, two of which mounted on the central body allow axis recovery.

In FIG. 8c, a system with three bars is shown, two of which (52) and (53), respectively mounted between the jaw (5) and the jaw (46), the jaw (5) and the jaw (47). In FIG. 8d, a system with two bars has been shown on the center equivalent to that of FIG. 8b but without connection between the body (1) and the upper central jaw (9).

In Figure 8e is shown a two bar system, jaw to jaw, respectively mounted between the jaws (5) and the jaws (46) and (47), which corresponds to the assembly of Figure 8c but without the body (1 ). The assembly of FIG. 8c is the assembly, of course, the most rigid. In Figure 9, there is shown the application of a device according to Figures 1 and 2, in an osteotomy, performed on the tibia (30) and fibula (31). The fixing assembly comprising the body (l) and the jaws (5) and (9) equipped with the joints (3) and (7), is mounted as indicated above with the difference that the upper jaw (9) is mounted transversely, which allows the mounting of a threaded rod (54), or any equivalent element such as a joint (55) extended by a threaded rod (56). Between this rod (56) and a threaded rod (57) fixed to the body (1) (FIG. 2), it is possible to mount, by means of articulations (58) and (59), a bar (60) used as a turnbuckle which will allow a shortening after sawing the fibula (31) in (61) and the tibia (30) in (62), having spread the head of the tibia (30) in the direction of the arrow (FIG. 9c). We practice a gradual approximation using Figure 9c. It is thus possible, by playing on the articulation (7), to gradually reduce the assembly by shortening the turnbuckle. By acting in this way, it is therefore possible gradually to go from a state as shown in FIG. 9d to the final state in FIG. 9e when the ablation of the whole apparatus has been performed.

In FIG. 10a, the use of a device such as that which is the subject of FIGS.

(2) for the elongation of a tibia (30) and a fibula (31). The assembly of the device consisting of the body (1), the jaws (5) and (9) and their joints is mounted.

(3) and (7), as has been said in connection with FIG. 4. There is then, between the ring (23) of wedging and one of the holes (22) of the body (1), an extension device (63) having elements (64) and (65) of respective fixings in the holes (22) of the body (l) and of the ring (23).

This device (63) can be of any conventional type and have a screw along which a adjustable slider which allows the progressive spacing of the parts (65) and (64) and therefore the progressive exit of the piston (6) and, consequently, the elongation of the assembly. According to a variant shown in FIG. 10b, it is not possible to use the extension device (63) but a rigging screw (60) used as in FIG. 9, but in the opposite direction, to progressively move the body (1) away from the jaw ( 9) thanks to a controlled sliding of the piston (6) in the body (l).

In FIG. 10c, another variant represents an equivalent system in which the body (1) is replaced by a rigging screw (66) associated with a rigging screw (60) mounted as in FIG. 4.

Referring now to FIG. 11, we will describe a cursor device which makes it possible to move one element relative to another and can be used for elongation or reduction as in the cases of the preceding figures. On a bar (67), is mounted this device which essentially comprises, an externally threaded ring or sleeve (68) whose head (69) is polygonal, a nut (70) screwed onto a threaded seat (68) and mounted at free rotation on a sliding element or sleeve (71). The element or sleeve (71) can carry, in threaded holes such as (72) and (73), various elements in particular for fixing a jaw or a body, as has been the case in the previous figures relating to lengthening or shortening.

The nut (70) and the part (71) can be fixed to the bar (67) by means of screw systems (73) and (74). If the nut is deeply screwed onto the threaded seat (68), and if the nut (70) is blocked by means of the screw (73), the nut (74) being released when the screw is unscrewed nut (70), the part (71) moves upwards with respect to FIG. 11. The screw (74) is then fixed, the screw (73) is unscrewed and the nut (70) is screwed back. The part (71) then remains fixed, the part (68) amount. By successive iterations, an upward advancement is thus allowed relative to FIG. 11 of the cursor assembly (68), (70), (71). This allows to move in correspondence any element fixed in one of the holes (72) or (73).

It is therefore understandable that, by this route or by operating on the contrary in the other direction, it is possible gradually to move the cursor in a controlled manner. Such a cursor mounted on bars such as those encountered in the preceding figures therefore makes it possible to gradually move any element fixed in the holes (72) and (73). This allows relative movement between jaws or between a jaw and a body or any other element for example. It will be noted in this regard that, in accordance with the invention, all the nuts allow a movement bearing the indications corresponding to the effect produced according to the direction of rotation (lengthening or shortening, for example). In addition, the pistons, bars and rods are graduated to allow direct reading of distances and displacements.

In Figure 12, there is shown a body equipped with a spring. “This in fact makes it possible to obtain what is generally called active dynamization. This means that internal stresses can be applied allowing, in particular, the exit of the piston (6) relative to the body (1). We have seen that the piston had a central hole in which a shim (75) can be introduced, allowing a spring (76) to be wedged between this shim (75) and the plug (77). Depending on the length chosen for the shim (75) and the type of spring that can be calibrated at will, we will therefore obtain, on the piston (6), an expulsion constraint which can be perfectly controlled, whether in size and / or at the desired time. This can be used effectively . .

when you want a progressive advance of the piston. This also makes it possible to obtain a certain elasticity when a fixing which is not completely rigid is desired.

FIG. 13 represents a new example of application of the device according to the invention. The jaws (5) and (9) here allow the closure of disjunctions or fractures of a pelvis thanks to the modular nature of the devices according to the invention. After having placed the jaws (5) and (9) on their rods, pins or screws (10), the threaded rods (78) are mounted on these jaws at the end of the jaw (5) and (79) on the side of the jaw (9). Two joints (80) and (81) screwed at a desired distance to the respective threaded rods (78) and (79) allow the mounting of a threaded bar (82) in the joint (81) and of a turnbuckle (83 ) in the joint (80). The bars (82) and (83) are themselves connected by a joint (84), screwed on the one hand on the end of the bar (82) and on the other hand enclosing the bar (83). It will be noted that the joints such as (80),

(81) and (84), like those encountered previously between threaded rods and bars or turnbuckles, are preferably biocable in rotation thanks, for example, to a dog clutch system. Thus, by acting progressively on the turnbuckle in the direction of the arrows, the disjointed or fractured elements are gradually brought closer to the pelvis, as indicated by the arrows in the lower part of FIG. 13.

In Figure 14, there is shown a preferred embodiment of the jaws such as (5) or (9). In these jaws, the holes (19) are not placed in the same plane but are offset. Under these conditions, the pins, screws or rods attached to it are not in the same plane and are not likely, by successive perforations, to cause a cracking of the bone which may translate into an aggravation or even a new incident. The jaw shown in FIG. 14 has, of course, moreover the same characteristics as the previous jaws and, in particular, the fixing holes (20) allowing mounting with other jaws or with other elements.

In Figure 15 is shown in section a particular type of turnbuckle intended to ensure, when fixed between two parts to provide a lateral offset. This turnbuckle with lateral offset consists essentially of a body (85) in which two sliders (86) and (87) can slide transversely along worms (90) and (91) rotated by polygonal heads (92), (93), (94) and (95). These screws (90) and (91) are free to rotate, but its locked in translation by any suitable device.

On the sliders (86) and (87), bars (88) and (89) are respectively mounted, at least one of which may have an adjustable length and be constituted by a turnbuckle. It is obvious that if an apparatus such as that shown in FIG. 15 is mounted, instead of a simple turnbuckle, it is possible to offset laterally a jaw for example or any other element with respect to another or in particular to turn it angularly or in any other direction by playing on the joints and the rotation of the pistons in the ^* bodies. Such a side turnbuckle can thus be used for rotation adjustment when reducing a fracture.

Note that the sliders (86) and (87) may have a series of holes, preferably threaded, which allows, depending on the holes chosen to fix the various rods or bars, to change the range of possible spacings. We can also decompose this turnbuckle in Figure 15 into two independent parts, but mounted for rotation on a common axis, for example perpendicular to two threaded rods, which makes it possible to create an additional angular gap between them and allows not only a shift along the screws (90) and (91), but a shift in a plane according to polar coordinates (pivoting angle and distance from translation on the screws). It is also possible to envisage only one cursor, the other being replaced by a simple attachment to the housing of the assembly.

It is also obvious that the devices according to the invention can be combined with devices such as those according to the state of the art.

It is indeed possible, to mount on the one hand, a body (l) associated with a jaw (5) by means of a joint (3) and to connect the body (1) to a fixing ring. It can also be seen that one of the qualities of the fixers in accordance with the present invention is, because of their modular nature and the ease of assembly and disassembly, of being able to be associated with most of the existing fixers on the market. This can be useful in the case of complex arrangements.

According to another characteristic, whatever the mounting chosen of the fixator, provision is made to connect the jaws (5) and (9) to the body (1) or other element by means of an eccentric plate to allow the maintenance of the assembly of the fixator in a plane substantially parallel to that of the bone. This offset plate has the effect of compensating for the axial offset that may result from the fracture. Under these conditions, the support forces are fully collected by the fixer.

The advantages clearly emerge from the description, in particular it is emphasized and recalled:

- the totally modular nature of the fixative allowing to work on unreduced fractures and to build any and infinite geometrical figures allowing to adapt the fixative to the different pathological cases, as well in per-operative as in post-operative.

- the entirely removable nature of the constituent elements of the fixative, thus avoiding to act in a harmful way on the focus of fractures.

- the possibility of modifying at will the initial assembly by replacing some of the constituent elements of the fixator, without for this modifying the regime of the applied forces.

- the particular design of the jaws avoiding inducing a line of weakness on the bone when they are fixed.

- the possibility of using the jaws to reduce the fracture directly or through added elements.

- the dynamic nature of the fixator taking into account the sliding mounting of the pistons in the body against compression means allowing at a moment in the history of the fracture, to release certain elements of the fixator and to allow the weight of s 'express naturally.

Finally, particularly importantly, given the entirely modular nature of the fixative, it is possible intraoperatively to act on fractures initially displaced and to adjust certain post-operative elements of the fixative in the post-operative phase. adapt to actual conditions of use. This possibility __. -

of adjustment makes it possible to perform more complicated operative acts such as the tilting of a bony frage, by simply playing no longer on the bone structure, but on the elements of the fixator whose angular position it is possible to vary at will in the space.

Claims

R E V E N D I C A T I O N S

-1- Fixer comprising jaws (5) (9) (46) (47) able to cooperate with fixing means (10) cooperating with the elements to be fixed, at least one main body (1) and intermediate elements ( 38) (52) (53) (60) (66) (67) (78)

(79) (82) (83) (85) shaped to fulfill a specific function, said jaws (5) (9) (46) (47), said body or bodies (1) and said elements (38) (52) (53) (60)

(66) (78) (79) (82) (85) having arrangements for directly or via attached articulation members (3) (4) (7) (8) (26) (27) ) (29), their coupling at will to constitute a modular assembly at the level of its structure with capacity for angular orientation in different planes and / or for linear adjustment.

-2- Fixer according to claim 1, characterized in that the articulation members (3) (4) (7) (8) are constituted by complementary parts with capacity of angular movement over at least 180 ° and disassembly l 'one relative to the other to separate at will the body and / or the jaws and / or the elements.

-3- Fixer according to claim 2, characterized in that the complementary parts of the articulation members are of the male (4-8) and female (3-7) type connected by a common axis (13-14) removable.

-4- Fixer according to claim 1, characterized in that the body (l) receives free sliding at least one piston (2) mounted free in rotation and one end of which is integral with one of the parts of the articulation members (3) (4) (7) (8). -5- Fixer according to claim 1, characterized in that the added elements (38) (52) (53) (60) (66) (67) (78) (79) (82) (83) (85) are fixed to a part of the body (1) and / or of the jaws (5) (9) with a fixed angular position or with angular orientation capacity by means of the articulation members (26) (27) (29).

-6- Fixer according to any one of claims 1 and 5, characterized in that the elements consist of turnbuckles of variable length (38) (52) (53) (60) (66) (78) (79) (82) (83).

-7- Fixer according to any one of claims 1 and 5, characterized in that the elements consist of a bar or rod (67) on which moves in successive increments, a cursor consisting of a sleeve (68) sliding on the bar or rod (67) and provided with locking means (73) in position, a threaded ring (70) cooperating with a threaded part of the sleeve (68), and being mounted to rotate freely on a second sliding sleeve (72) also on the bar or rod (67) on which it can be locked in position by means (74), the movement of the assembly being effected by locking in position of one of the sleeves (68-71), the screwing or unscrewing between ring (70) and threaded part (68), blocking the other sleeve (71-68), unlocking the first, and so on.

-8- Fixer according to any one of claims 6 and 7, characterized in that the turnbuckles comprise two parts (88-89) mounted on a housing and for at least one, by means of a slider ( 86-87) sliding transversely with respect to said parts (88-89) along an endless screw rotating in a common housing, controlled in rotation from the outside by rotation of the ends (92- 93-94-95) of the screws, thus ensuring an offset by translation between said parts (88-89).

-9- Fixer according to claim 8, characterized in that each cursor has several fixing points of the parts (88-89.) Of the turnbuckle.

-10- Fixer according to any one of claims 7 and 9, characterized in that the housing is separated into two parts articulated on a common axis substantially parallel to the parts (88-89) of the turnbuckle.

-11- Fixer according to claim 1, characterized in that the clamping holes (19) located at the interface between jaws (5-9) are not with coplanar axes.

-12- Fixer according to claim 4, characterized in that a spring (74) housed in the body (1) is wedged between a part (77) of the body (1) and the piston (2).

-13- Fixer according to claim 12, characterized in that the piston (2-2 ') is pierced axially (12) inwardly and receives the spring (74) therein.

-14- Fixer according to claim 13, characterized in that a shim is inserted between piston (2) and spring (74).

-15- Viewfinder for the installation of the fixing means (10) for fixator according to any one of claims 1 to 14, characterized in that in a block transparent to X-rays are drilled right through at least one hole guide (33) identified by a reticular device (34-35) opaque to X-rays and passing through the axis of the holes (33).

-16- Viewfinder according to claim 15, characterized in that the reticular device includes platelets (34-35).

-17- Viewfinder according to claim 16, characterized in that the reticular device comprises series of coplanar wires.