FR2728155A1 - One-piece osteosynthesis element for use with fractures and osteotomies - Google Patents

Abstract

The element comprises a flexible pin with two branches (1,2) which are connected by an intermediate section (5) at their bases (6,7). The free ends (3,4) of the two branches can be of the same or different lengths and are maintained in their initial position by elasticity. One or more zones of the element can have bends in them, and the intermediate section (5) can be bent over to form a shoulder for attaching a connector. The element is made from round or variable-section rod of steel or other elastic and biocompatible material, or it can have a biocompatible coating with an adhesive or roughened surface. Its dimensions depend on the size of the bones in which it is to be used.

Description

The present invention relates to a device for
centromedullary osteosynthesis of fractures or osteotomies.

 The centromedullary osteosynthesis of fractures or osteotomies using a single monobloc material (centromedullary nail, rod, pin ...) does not allow by this material only satisfactory locking in axial rotation of the fracture or osteotomy focal point.

 On the other hand, this type of material also does not provide satisfactory stabilization of fractures or osteotomies of the metaphyseal or epiphyseal regions.

 Finally, the bone concerned may be too small to accept a nailing device. In this case, the use of centromedullary pinning, in addition to not providing satisfactory anti-rotatory locking, is often followed by spontaneous migration of the pins, leading to the risk of tendon damage and skin perforation, as well as discomfort. certain.

To overcome the limitations of nailing, two types of solutions have already been proposed:
- The first type of solution consists of adding a so-called locking device to the monobloc centromedullary device, comprising one or more complementary parts (screws, keys, fins, joints, etc.).

 - The second type of solution consists in the multiplication of intramedullary devices (so-called fasciculate nailing). In this solution, the rotary locking is obtained by securing the devices, which is achieved, by construction or during the surgical intervention, by the addition to the fasciculated device of one or more securing parts.

In these two types of solutions, the anti-rotation locking or of the metaphyso-epiphyseal region is obtained by the multiplication of the parts necessary for the realization of a complete locked osteosynthesis device and therefore has several disadvantages:
Need to machine several parts, storage of materials and multiple parts, frequent need of a particular ancillary material at each stage during the assembly of the parts especially if the assembly is carried out during surgical intervention, multiplication of times operating, multiplication of operating incisions, necessity of a radiological control of the good realization of each stage with as corollary an irradiation multiplied by the number of operating times, increased risk of mechanical failure of one of the components of the assembly.

 In the case of broaching, it has been proposed to limit the risk of spontaneous migration of the material various systems for capping the aggressive end of the material (welded ball, screwed or styling cap); these systems do not eliminate the risk of mobilization of the material, but only limit the tendon and skin consequences.

The device according to the invention overcomes these drawbacks:
Indeed, it has as a first characteristic to be a single piece consisting of a single rod folded over itself in a pin with two branches, and elastic: The two branches, of equal length or not according to the desired osteosynthesis, each have an end free, and are connected to each other at their origin by an intermediate zone formed by a fold of the device.

 Thus each of the two branches of the device can be introduced into the bone according to the medullary medullary technique, the device producing in one piece the equivalent of a pinning or nailing fasciculated with two elements, the intermediate zone of the device alone remaining outside of the bone. This zone, consisting of a simple foam fold of the device, is therefore in no way aggressive for the neighboring soft parts.

 In addition, if the intermediate zone is chosen to be wide enough with respect to the medullary canal into which the branches of the device engage, and if the branches are introduced into the bone via independent orifices, the branches of the device progressing through the canal medullary approach each other, thus enclosing the bone located between the two insertion holes and performing a clamp preventing the migration of the device and performing an automatic locking.

 On the other hand, the assembly thus produced is roughly triangular with two epi or metaphyseal anchors corresponding to the entry points of the branches, and a diaphyseal anchorage corresponding to the intra-diaphyseal part of the branches: this indeformable triangular assembly therefore allows stable osteosynthesis in rotation of epiphyseal or metaphyseal fractures.

 The device must be sufficiently elastic so that, if one fictitiously defines the "main axis of the device" as the straight line connecting the midpoint of the intermediate zone and the point located halfway between the ends of the branches, the device can be twisted along this main axis from any angle between plus and minus 180 degrees without persisting, after this twisting, no residual plastic deformation.

 Thus, during intervention the operator can control the progression of the device in the bone: twisting movements of the still extra-osseous part of the device are transmitted at its ends and allow control thereof, without altering the subsequent check necessary following the intervention which would result from plastic deformation of the device.

According to particular embodiments:
- One or both branches of the device, and / or one or both ends of the branches of the device, and / or the intermediate zone of the device, can (can) be curved (s) or angled (s). In the case of a curve or a crutch, the crutches or curves can be oriented differently on one branch and on the other. The branches of the device or their origin in the vicinity of the intermediate zone may or may not be parallel to the main axis of the device, convergent or not. The axis of the intermediate zone may or may not be perpendicular to the main axis of the device.

 - One or more curves or angulations of the branches make it possible, under certain conditions, to accentuate or cause a controlled divergence of the ends of the branches of the device engaged inside the bone, by acting only on the part of the device which remains outside bone. Such a divergence, caused when the device is almost completely engaged in the bone, makes it possible to enclose the diverging ends in the spongy metaphyseal or epiphyseal bone, and achieves an anti-rotation locking equivalent to fins, without recourse to any additional part.

 - The intermediate zone connecting the bases of the branches can be curved, angled, or have a shoulder. The curve, the angulation or the shoulder thus produced can be located in the plane of the branches of the device, or outside this plane. This conformation can be used for example for the passage of a strapping wire if it is sought to associate with the osteosynthesis a shroud effect or a dynamic compression effect of the osteosynthesis focal point. Such a conformation of the intermediate zone, associated with a curve of one or of the two branches makes it possible to cause the controlled divergence of the ends of the branches of the device, by a simple deformation of the intermediate zone; this effect allows for automatic distal locking equivalent to fins, without the use of any additional parts.

 - The connection area of the branches called "intermediate area" can be folded back on itself in one or more loops, or perforated with one or more orifices.

 This conformation can be used, for example, for the passage of screws through the device in order to recall a bone fragment located in the vicinity of the points of introduction of the device.

 - The device can have a part of its smooth surface, and another rough part. I1 can be partially or completely covered with a biocompatible or rehabitable coating by the bone, or even have spikes. Such a coating, or pins can be used for example to strengthen the anchoring of the device in the bone.

 - A particular variant of conformation of the ends of the branches of the device is characterized by the folding in on themselves of the ends of the branches, partially drawing an open hook, or completely drawing a closed loop. Thus, the device can be engaged on a guide rod housed in the concavity of the ends thus drawn, facilitating the positioning of the device.

The accompanying drawings illustrate the invention:
Figure 1 shows, from the front, the device according to the invention: With reference to this drawing, the device comprises two branches (1) and (2), having two free ends (3) and (4), in these figures represented crutches without this last conformation of (3) and (4) being compulsory. A fold of the device in the vicinity of the origin (6) of the branch (1), as well as another fold in the vicinity of the origin (7) of the branch (2), materialize an intermediate zone (5).

 FIG. 2 represents, in profile, a variant of the device in which there is an angulation of the branches (1) and (2) slightly beyond their origins (6) and (7).

 Figure 3 shows the device according to the invention shown in Figure 1, from the front, twisted on itself by 180 degrees; the ends (3) and (4) of the branches (1) and (2) being maintained in their initial position defined by construction, the region (5) has been turned on itself by 180 degrees along the main axis of the device defined above. The elasticity of the device according to the invention must be such that after such a twist, the device delivered to itself resumes its initial shape shown in Figure 1 without residual plastic deformation.

 Figures 26 and 27 show an example of the use of such a device: Figure 26 shows the device before its installation, Figure 27 the device in place for a fracture or osteotomy of the lower radius end: L ' elasticity of the branches (1) and (2) allows, during the introduction of the device into the bone, at the ends (3) and (4) to approach one another while progressing in the medullary canal. The branches (1) and (2) form with the intermediate zone (5) a roughly triangular forceps which prevents the spontaneous migration of the device towards the outside of the bone, and locks the rotation of the metaphyso-epiphyseal region.

The figures numbered from 4 to 17 represent variants of the intermediate zone (5):
FIG. 4 shows a front view of a variant configuration of the intermediate zone (5) in which the intermediate zone (5) is simply rectilinear, and perpendicular to the main axis of the device.

 FIG. 5 shows a front view of a variant configuration of the intermediate zone (5) in which the intermediate zone (5) is not perpendicular to the main axis of the device. For example, such a conformation could be used in the example described in FIG. 27, so that the intermediate zone adapts better to the anatomy of the radio-carpal joint.

 FIG. 6 shows a front view of a variant configuration of the intermediate zone (5) in which the intermediate zone (5) carries a shoulder or an angulation (8). Such a conformation is usable, for example, if it is desired to pass a strapping wire to associate a dynamic compression or guy line effect. When tightening the strapping, the strapping wire will spontaneously lodge in the concavity of the shoulder or the angle (8) and will not slip laterally.

 FIG. 7 is a front view of a variant configuration of the intermediate zone (5) in which the intermediate zone (5) is covered with spikes.

 Figure 8 shows a front view of a variant of the branches of the device by their origins (6) and (7) on the intermediate zone (5) in which the branches converge at their origin towards the main axis of the device.

 FIG. 9 shows a front view of a variant configuration of the intermediate zone (5) in which the intermediate zone (5) is pierced with an orifice (10) for example to pass a strapping wire.

 FIG. 10 shows a front view of a variant configuration of the intermediate zone (5) in which the intermediate zone (5) is folded back on itself in the form of a loop (9).

 FIG. 11 represents the conformation described in FIG. 10 in profile, FIG. 12 represents the conformation described in FIG. 11 in a use where a screw crosses the loop (9), for example to screw a reminder of a bone fragment located at a distance, FIG. 13 shows the configuration described in FIG. 11 in a use where a strapping wire is passed through the loop (9).

 FIG. 14 is a front view of a variant configuration of the intermediate zone (5) in which the intermediate zone (5) carries a shoulder (8) raised relative to the location of the branches of the device, as shown in FIG. Figure 15, side view of the variant drawn in Figure 14. Such a configuration of the intermediate zone (5) allows the passage of a return screw as drawn in Figure 16, or a strapping wire as drawn in Figure 17. figure 28 represents an example of use of the device with a zone (5) shaped as here described figure 14: in the example presented figure 28 of shrouding of a fracture or olecranon osteotomy, the strapping cannot slide laterally since housed in the concavity of the shoulder (8), while the intermediate zone (5) conforms to the anatomy of the region due to the elevation of the shoulder (8) relative to the branches of the device. The latter are housed in the medullary canal where they can slide, not impeding the dynamic compression of the osteosynthesis.

 FIG. 18 shows in profile a variant of the ends (3) and (4) of the branches (1) and (2) in which these ends (3) and (4) are bent in a hook. FIG. 19 represents the variant described in FIG from the front. FIG. 20 explains the possible use of the variant drawn in FIGS. 18 and 19: The ends (3) and (4) bent in a hook can be engaged on a guide rod, then slide to the end of the guide rod, guiding the path of the branches (1) and (2): Such a configuration can be used to facilitate the passage of the fracture site in the case of osteosynthesis of particularly complex fractures.

 FIG. 21 shows from the front a variant of the device in which the shoulder (8) is raised relative to the branches (1) and (2) as described in FIGS. 14 and 15. This conformation of the intermediate zone (5) is associated with a convergent conformation of the origins (6) of the branch (1) and (7) of the branch (2); the two branches (1) and (2) are angled or curved so that they are parallel except at their origin. The branches (1) and (2) are shown in FIG. 21, without being compulsory, of unequal lengths and with ends (3) and (4) crutches.

 FIG. 22 represents, in profile, the device according to the conformation described in FIG. 21.

 Figure 23 explains the operation of the device shown in Figures 21 and 22: After crushing the intermediate area (5) according to the arrows "E", the shoulder (8) sees its radius of curvature decrease. This results in a rapprochement of the origins (6) and (7) of the branches (1) and (2), while these branches deviate at their ends (3) and (4).

 FIG. 24 represents, in an enlarged view along the main axis of the device, the conformaton described in FIGS. 21 and 22. FIG. 25 represents the same device described in FIG. 23 after crushing according to the arrows "E" of the shoulder (8) of the intermediate zone (5), and explains the divergence thus transmitted to the ends (3) and (4) of the branches (1) and (2).

 A possible use of a device as shown in Figures 21,22,23,24,25, is shown, by way of example, Figures 29 and 30, for locked osteosynthesis of a fracture or tibial osteotomy: In Figure 29, the device is introduced through a single bone orifice. It is then in the configuration described in Figure 21. Figure 30 shows the same device at the end of osteosynthesis: when passing through the single introduction orifice, the origins (6) and (7) of the branches (1) and (2) have approached, resulting in a divergence of the ends (3) and (4) of the branches (1) and (2); The ends (3) and (4) can then be pushed into the lower metaphyso-epiphyseal cancellous bone, achieving an automatic anti-rotatory locking of the osteosynthesis.

 The device according to the invention can be produced on the basis of a cylindrical rod, or of a non-circular or variable section, provided that the elasticity conditions described above are fulfilled. This rod can be made of steel or some other biocompatible elastic material, or some other non-biocompatible material if it can be covered with a biocompatible coating. The device is obtained by shaping the rod, by stamping, folding, or curving. The rod is folded twice to materialize the area (5), the branches (1) and (2) as well as their ends (3) and (4). The origins (6) and (7) of the branches (1) and (2) can be materialized by folding or curving of the branches (1) and (2) in the vicinity of the intermediate zone (5). A bend or curve can be made on the branches (1) and (2) in the vicinity of the ends (3) and (4).

 An open shoulder (8) can be obtained by stamping, while a loop (9) of the zone (5) can be produced by winding around a cylinder of the zone (5), or of the region of the rod constitutive intended to become subsequently the area (5). One or more orifices (10) can be drilled on the zone (5) if the latter has been previously shaped large enough so that the drilling does not cause the section of the zone (5).

By way of nonlimiting examples:
- The device presented in Figure 27 in the osteosynthesis of a lower radius end can have dimensions of the order of 8 cm in its greatest length, about 1 cm in width, and can be produced on the basis of a cylindrical steel rod of section 15/10 mm
- The device presented in Figure 28 in the osteosynthesis of an olecranon may have dimensions of the order of 8 cm in its greatest length, about 1 cm in width, the shoulder (8) having a height of the of the order of 6 mm, and can be produced on the basis of a cylindrical steel rod with a section of the order of 20/10 mm.

 - The device presented in Figure 29 in the osteosynthesis of a tibia can have dimensions of the order of 25 cm to 40 cm in its greatest length, over approximately 3 cm in width, the shoulder (8) having a height of the order of 1.5 cm, and can be produced on the basis of a cylindrical steel rod with a section of the order of 4 mm to 5 mm.

 These devices are introduced into the bone by preparative cortical orifices, ends (3) and (4) of the branches (1) and (2) the first and introduced under radioscopic control into the medulla of the bone, or even into metaphyseal or epiphyseal cancellous bone. The progression of the device in the bone is controlled by movements of the intermediate zone (5) which communicate, via the origins (6) and (7) of the branches (1) and (2) at the ends (3 ) and (4).

 The device according to the invention is particularly intended for osteosynthesis of fractures or osteotomies

Claims (9)

 1) Device for osteosynthesis of fractures or osteotomies characterized in that, comprising a single component, it has the shape of an elastic pin with two branches (1) and (2) connected by their respective bases (6) and (7) to an intermediate zone (5), and having for the branch (1) a free end (3) and for the branch (2) a free end (4). The device can equally have branches (1) and (2) of equal or unequal lengths.  180 degrees.  any angle between plus and minus  (5) along the main axis of the device  performing a rotation of the intermediate zone  - or twisted the device on itself while  Having defined the "main axis of the device" as the straight line connecting the midpoint of the intermediate zone (5) and the point located midway between the ends (3) and (4) of the branches (1) and (2) , the device has an elasticity such that, the free ends (3) and (4) of the arms (1) and (2) of the device being maintained in their initial position defined by construction, and after having:  the device returns to its initial shape without residual plastic deformation.  (3) of branch (1),  of the main axis of the device that the end  and the origin (7) of the branch (2) on the same side  device that the end (4) of the branch (2)  branch (1) on the same side of the main axis of the  any angle bearing the origin (6) of the  (5) along the main axis of the device  performing a rotation of the intermediate zone  - or twisted the device on itself while  2) Device according to claim 1 characterized by the presence of a curve or an angle on one or more of the regions (1), (2), (3), (4), (5), (6 ), (7).  3) Device according to claim 1 or claim 2 characterized by the presence, on the intermediate zone (5), of a shoulder (8), possibly but not necessarily raised when the device rests on its branches (1) and (2 ) or their origins (6) and (7).  4) Device according to claim 1 or claim 2 characterized by the presence, on the intermediate zone (5), of one or more folds (s) in a loop (9)  5) Device according to claim 1 characterized by the presence, on the intermediate zone (5), of one or more orifices (10).  6) Device according to any one of the preceding claims, characterized by the presence of an angulation or a curve between the origin (6) of the branch (1) and the branch (1) and / or of an angulation or a curve between the origin (7) of the branch (2) and the branch (2).  7) Device according to any one of the preceding claims characterized by origins (6) of the branch (1) and (7) of the branch (2) oriented along converging axes, or oriented not parallel to the main axis of the device  8) Device according to any one of the preceding claims, characterized by an open or closed hook curvature of one or the other or of the two ends (3) and (4) of the branches (1) and (2).  9) Device according to any one of the preceding claims, characterized by the presence of a bio-compatible, adherent coating, or of pins on all or part of the surface of the device.