Orthopedic implant consisting of a support structure provided with at least an orifice for passing through a fixing screw associated with a nut

CA 02467887 2004-05-17 WO 03/043513 PCT / FR02 / 04020 ORTHOPEDIC IMPLANT CONSISTING OF A SUPPORT STRUCTURE EQUIPPED WITH AT LEAST ONE ORIFICE FOR THE PASSING OF A FIXATION SCREW ASSOCIATED WITH A NUT The present invention relates to a new orthopedic implant system of the type consisting of a support structure provided with at least one orifice for the passage of a fixing screw associated with a nut.

In general, orthopedic implants, in particular osteosynthesis implants, comprise a support structure in the form of a plate, shell or the like, provided with one or more orifices intended for the passage of fixing screws capable of coming s 'anchor in the receiving bone material.

The general shape and dimensions of this support structure are adapted to the installation constraints.

There are very many types of implants which differ in particular by the presence or absence of an attachment between the screw head and the support structure, to optimize the retention of the screw in place over time, and / or by the presence of means giving the fixing screw a possibility of angular orientation with respect to the axis of its receiving orifice, to allow the practitioner to best position said screw as a function of the implantation site and the corresponding spatial constraints.

A good quality of maintenance of the implant is obtained when the support structure is sandwiched between the screw head and a nut, as is known from document WO-A-99/09903.

But in this case the particular securing of the nut with the support structure requires a precise presentation of the fixing screws so as not to damage the thread of the nut at the time of screwing; and the practitioner has no possibility of spatial orientation of the screws.

The present invention proposes a new orthopedic implantable device, of simple, practical structure, having good locking and holding qualities in place, and allowing a certain possibility CA 02467887 2004-05-17 WO 03/043513 PCT / FR02 / 04020 2 spatial orientation of the fixing screws with respect to the axis of the reception orifices arranged in the support structure.

This orthopedic implant is of the type consisting of a support structure provided with at least one orifice for the passage of a fixing screw associated with a nut, the head of said screw being intended to come to rest on one side of said support , and said nut being intended to come to rest on the other side of said support, in a housing which allows its at least partial integration, so as to allow tightening of said support structure between the screw head and the nut, at the end of the tightening of the screw body in the receiving bone material; this implantable device also comprises means for maintaining said nut in its receiving housing facing the orifice of the support structure, and for locking said nut in rotation.

According to the present invention, the contours of the housing of the support structure and the contours of the nut are dimensioned to provide at least one degree of freedom to said nut in said housing, allowing ams ~ a self-centering of the fixing screw and the 'associated nut, regardless of the admissible orientation of the axis of said screw relative to the axis of the orifice of the support structure.

According to a first possible embodiment, the means for maintaining the nut in its receiving housing consist of a discharge of material partially closing said housing.

According to another embodiment, these holding means consist of an attached clip partially closing the nut receiving housing.

In this latter embodiment, the nut retaining clip is advantageously in the form of an open circular loop; this buckle comprises a snap-fastening rib which cooperates with a groove of suitable shape provided in the housing for integrating the nut.

According to another characteristic, the means for locking the nut in rotation in the receiving housing of the support structure consist of at least one relief arranged on one of said parts (nut or support structure), CA 02467887 2004- 05-17 WO 03/043513 PCT / FR02 / 04020 3 cooperating with a suitable notch, arranged on the other part (support structure or nut).

According to a particular embodiment, the implant comprises cylindrical contact surfaces between the screw head and the support structure, on the one hand, and between the support structure and the nut, on the other hand.

These cylindrical contact surfaces are adapted to give the fixing screw a possibility of orientation relative to the support structure, while maintaining contacts between surfaces (cylindrical contacts) making it possible to optimize the connection during tightening.

Preferably, these cylindrical contact surfaces have the same axis.

According to a preferred embodiment, the implant comprises spherical contact surfaces between the screw head and the support structure, on the one hand, and between the support structure and the nut, on the other hand, which are suitable for give the fixing screw a possibility of orientation relative to the support structure, while maintaining surface contacts (spherical contacts).

This particularity confers significant possibilities of angular adjustment of the screw and optimizes the mechanical connection during tightening.

Preferably, these spherical confiact surfaces, in the form of spherical caps, have the same center.

In order to obtain a compact assembly having an advantageous capacity for angular adjustment of the screws, the axis or the center of the cylindrical or spherical contact surfaces is located close to the upper plane of the support structure, or coincides with this plane.

According to yet another feature, the orthopedic implant according to the invention comprises a nut comprising a cylindrical barrel having a female thread, and a spherical cap or crown located at the periphery of said cylindrical barrel.

According to yet another feature, the fixing screw is provided with a body thread capable of cooperating with the receiving bone material, and a head thread capable of cooperating with the associated nut, the external diameter of the thread of body being less than or equal to the external diameter of the head thread to allow passage of the screw through the nut.

CA 02467887 2004-05-17 WO 03/043513 PCT / FR02 / 04020 To optimize the tightening, the fixing screw (s) are advantageously provided with a head thread composed of n threads offset by 1 / n turns, and of which the not cooperates with that of the nut thread and that of the body thread.

The invention will be further illustrated, without being in any way limited thereto, by the following description of several particular embodiments, given solely by way of example and represented in the appended drawings in which FIG. 1 generally represents an orthopedic plate positioned on the surface of a fractured bone, and intended to receive fixation screws;

- Figure 2 is a functional block diagram of a first possible embodiment of an implant according to the present invention;

- Figure 3 shows a top view of a possible embodiment of an orifice in the support structure for the passage of a fixing screw;

- Figures 4 to 7 illustrate four different functional diagrams of implants according to the present invention, allowing angular adjustments of the axis of the screw relative to the support structure;

- Figure 8 is an exploded sectional view of a preferred embodiment of the implant according to the functional block diagram of Figure 7;

FIG. 9 shows the implant of FIG. 8, at the end of straight screwing, that is to say that the screw is centered on the axis of the orifice of the support;

- Figure 10 shows the same implant as Figure 9 but at the end of inclined screwing, that is to say that the screw forms an angle with the axis of the orifice of the support;

- Figure 11 is a partial view on a large scale, from below of the support structure showing the housing for receiving the nut;

- Figure 12 is a sectional view along 12-12 of Figure 11;

- Figure 13 is a perspective, also on a large scale, of a nut for the implant illustrated in Figures 8 to 10;

- Figure 14 is a top view of the nut illustrated in Figure 13;

- Figure 15 is a diametral sectional view along 15-15 of Figure 14;

- Figure 16 is a side view of the nut shown in Figures 13 to 15;

- Figure 17 is a perspective on a large scale of the circular clip allowing the retention of the nut in the housing of the support structure;

CA 02467887 2004-05-17 WO 03/043513 PCT / FR02 / 04020 - figure 18 is a top view of the clip illustrated in figure 17;

- Figure 19 is a diametrical sectional view of the clip according to 19-19 of Figure 18.

In Figure 1 we note the orthopedic implant 0 consisting of a 5 ~ support structure in the form of an osteosynthesis plate 1 positioned on a fractured bone 2, for example an epiphysis of the radius, and having four circular holes 3 for reception of fixing screws 5.

Each screw 5 comprises a screw head 6 and a screw body 8.

In Figure 1, there is also illustrated the drilling barrel 9 which is used before the installation of the screws 5 to drill positioning holes in the bone material, through the holes 3.

Figure 2 is a functional block diagram which schematically shows the mounting of a screw 5 on the support plate 1.

In this figure, we note the presence of a nut 10 positioned in a housing 12 arranged in the support plate 1, so that at the end of screwing said plate 1 is sandwiched between the head 6 of the screw 5 and said nut 10.

The female thread of the nut 10 cooperates with the male thread of the screw body 8 to achieve a locked assembly at the end of screwing.

For this purpose, the screw 5 may have a single thread, on the one hand for anchoring in the bone material, and on the other hand for cooperation with the nut;

but it can also be provided with two different threads each providing one of the aforementioned functions.

The nut 10 can simply be partially integrated into the housing 12. It is held in place in said housing 12, facing the orifice 3, by suitable retaining means 13, and it is also immobilized in rotation by means. appropriate shown as a single spotted line 14.

The retaining means 13 may be in the form of a discharge of material or of an attached structure detailed below, of the locking clip type, implemented after the positioning of the nut 10 in the housing 12.

CA 02467887 2004-05-17 WO 03/043513 PCT / FR02 / 04020 6 The locking in rotation of the nut 10 is obtained either by the relative general shapes of the nut 10 and of the housing 12 of reception, or by cooperation of 'complementary members of the relief type) and notch (s), arranged on the surfaces facing the nut and the housing.

According to the invention, the contours of the housing 12 and the contours of the nut 10 are adapted and dimensioned to provide the latter, in said housing, at least one degree of freedom, greater than that of a simple functional clearance, thus allowing a self-centering of the screw 5 and of the nut 10, this whatever the admissible orientation of the axis of said screw with respect to the axis of the housing 3.

In FIG. 2, we see the two axis lines 15 illustrating the amplitude of the corresponding possible inclinations of the screw.

The middle position, normal to the support plate 1, is represented by the axis 16, which axis 16 corresponds to the axis of the housing 3.

~ As shown in Figure 3, the support plate 1 may include elongated orifices 3 'then allowing a possibility of additional longitudinal adjustment of the screws 5 relative to the support 1.

These elongated orifices 3 ′ may have a generally rectilinear or curvilinear shape.

Figures 4, 5, 6 and 7 are functional diagrams derived from that of Figure 2, illustrating the screw assembly according to the invention, but with cylindrical or spherical contact surfaces between the screw head 6 and the support plate 1, on the one hand, and between the support plate 1 and the nut 10, on the other hand, allowing a relatively large degree of freedom and possibilities of angular adjustment of the screw 5, while retaining a large contact surface promoting good cohesion of the assembly after screwing.

In all cases, the different parts are shaped as well as possible to obtain significant angular adjustment possibilities and to maintain the best possible contact between surfaces.

In the case of cylindrical contact surfaces, angular adjustment is possible in a plane if the orifice 3 is circular 3p, or in different parallel planes corresponding to a prismatic volume if there is an oblong orifice 3 'as illustrated in figure 3.

CA 02467887 2004-05-17 WO 03/043513 PCT / FR02 / 04020 7 In the case of spherical contact surfaces, a circular receiving orifice is preferably provided and the angular adjustment of the screw is then possible inside of a conical volume whose axis coincides with that of the circular orifice 3.

In Figure 4, the head 6 of the screw 5 is in contact with an intermediate member 18 which has a sliding surface in contact with the support plate 1.

The contact surfaces between the head 6 and this insert 18 correspond to a cylindrical portion centered on an axis 19, or to a spherical cap centered at a point 19, as the case may be. The axis or the center 19 is here positioned on the outside, above the support plate 1.

On the other hand, the nut 10 and the support plate 1 are also in contact on cylindrical or spherical surfaces, as the case may be. The axis or the center 20 of the cylinder portion or of the corresponding spherical cap portion is here positioned on the inner side, that is to say on the side of the bone structure.

The nut 10 is held in place by the means 13 and it is immobilized in rotation by means 14 shown schematically in the form of a single line.

FIGS. 5, 6 and 7 illustrate embodiments devoid of complementary part 18 and of which the spherical or cylindrical contact surfaces of the screw head / support plate and support plate / nut are centered on the same axis or have the same center.

For the embodiment illustrated in FIG. 5, the corresponding axis or center 21 is located between the two contact surfaces.

For the embodiment illustrated in FIG. 6, the corresponding axis or center 22 is located on the internal face side of the support structure 1.

For the embodiment of FIG. 7, the corresponding axis or center 23 is located on the external face side of the support structure 1.

The embodiment illustrated in FIG. 7 appears to be the most compact.

Preferably the axis or the center 23 is located near the upper surface of the support structure 1 to optimize the possibilities of 3p _dëbattement angular of the screw 5; the distance marked H in this figure then tends towards a zero value.

CA 02467887 2004-05-17 WO 03/043513 PCT / FR02 / 04020 8 In all cases, the nut 10 is held in its housing 12 by means 13 of the material discharge type or clip as detailed below, and it is immobilized in rotation by means shown schematically in the form of a single line 14 detailed further below.

Because of the general size of the parts, the corresponding cone of angular movement always gives the practitioner aes possia ~~~ zes interesting adjustment.

Figures 8 to 19 detail an embodiment according to that shown schematically in Figure 7.

FIG. 8 shows a fixing screw 5 in schematic longitudinal section.

This screw 5 has on the one hand a screw body 8 provided with a thread 25 and the end 26 of which is shaped like a pigtail, and on the other hand a screw head 6 provided with its own thread 27.

The upper part of the screw head 6 has a cavity 29 with polygonal walls cooperating with the installation instrument.

This screw head 6 has at its end a collar whose peripheral outline is in the form of a spherical crown 7, intended for contact with a surface of equivalent shape provided on the support structure 1.

The screw 5 passes through the plate 1, seen in section, at the level of the circular orifice 3, as well as the nut 10 and the retaining means 13, here in the form of a locking clip, also seen in section.

The support structure 1, the nut 10 and the locking clip 13 are shown exploded, separated from each other.

The thread 27 of the screw head 5 is matched to that of the nut 10.

This thread is composed of n threads 28 offset by 1 / n turn, the pitch of which is able to cooperate with that of the thread 30 of the nut 10, which pitch corresponds to that of the thread 25 of the body of the screw 8.

The thread 25 of the screw body 8 is able to come to achieve an anchoring by screwing in the bone material; the external diameter of this body thread CA 02467887 2004-05-17 WO 03/043513 PCT / FR02 / 04020 9 25 is less than or equal to the external diameter of the head thread 27 so as to allow the passage of the screw body 8 to the through the threaded hole of the nut 10.

FIG. 9 represents the fixing screw 5 at the end of screwing, in a configuration normal to the plate 1 (the receiving bone structure is not shown).

The plate 1 is then sandwiched between on the one hand the screw head 6, and on the other hand the nut 10 whose female thread 30 cooperates with the male thread 27 of said screw head 6.

FIG. 10 represents the fixing screw 5 at the end of screwing in a configuration inclined with respect to the axis 16 of the orifice 3.

This possibility of inclination is linked to the fact that the nut 10 has a degree of freedom in its receiving housing 12. On the other hand, the spherical contact surfaces of the screw head / support plate and support plate / nut allow to obtain a high quality of tightening whatever the admissible inclination of the axis of the screw 5 with respect to the axis 16 of the hole 3.

It is also possible to provide a spherical contact surface between the nut 10 and the locking clip 13 so as to optimize the guiding of the nut 10 during the positioning of the screw 5 at the start of screwing.

The corresponding contact surfaces are detailed below in connection with the description of each component part of the implant.

FIGS. 11 and 12 show in detail the configuration of the circular orifice 3 and of the housing 12 which is arranged in the support structure 1, which housing 12 is intended to receive the nut 10 detailed in FIGS. 13 to 16.

This nut 10 is preferably held by a locking clip detailed in FIGS. 17 to 19, which clip allows easier removal of the nut than in the case of holding it by crimping.

As shown in Figures 11 and 12, the support plate 1 comprises a spherical ring 312 consisting of a first spherical ring 31 for contact with the screw head 6, and a second spherical ring 32 for contact with the 'nut 10.

The peripheral portion 313 which extends between the two spherical rings 31 and 32, is of frustoconical shape, with an angle sufficient to allow the movement of the nut 10 and therefore of the screw 5 relative to the part CA 02467887 2004- 05-17 WO 03/043513 PCT / FR02 / 04020 support 1.

This portion 313 can constitute a stop for the nut 10 and in particular for its barrel 100 as detailed below.

On the circular periphery of the housing 12, we notice the presence of a circular groove 33 intended for the positioning and locking of the retaining clip 5 13.

The means for immobilizing the nut 10 in rotation relative to the support 1 consist of at least one lug or tenon.

FIG. 11 shows three tenons 34 regularly distributed in the bottom of the circular housing 12, between the periphery of said housing and the spherical crown 32.

These tenons 34 cooperate with female homologous shapes detailed below, arranged on the nut 10 to lock the latter in rotation.

As shown in Figures 13 to 16, the nut 10 has a spherical ring 35 intended for contact with the support structure 1 and in particular the spherical ring 32 of the ring 312.

It is also possible to provide an external spherical crown 36 intended for contact with the retaining clip 13.

Said spherical rings 35, 36 form part of a spherical ring 356 connected to the lower periphery of a cylindrical barrel 100 acting as a nut, which barrel is provided with the female thread 30.

The outer peripheral surface of the barrel 100 is housed with play in the frustoconical portion 313 of the support 1, so as not to alter the spherical patellar contacts between the nut 10 and said support.

Limiting the range of motion of. the nut 10 relative to the support 1 can be obtained by the frustoconical portion 313 of said support, which acts as a stop for the shank 100 of the nut 10.

The spherical surface 36 optimizes the correct spatial positioning of the nut when the screw 5 is inserted.

The degree of freedom of the nut 10 in its receiving housing 12 allows self-centering of the fixing screw 5 and of the associated nut when the implant is fixed.

In Figures 13 and 14, we see the female shapes mentioned above, in the form of cavities or notches 37 which are intended to cooperate with the tenons 34 of the support structure 1 to lock the nut 10 in CA 02467887 2004 -05-17 WO 03/043513 PCT / FR02 / 04020 rotation.

The sides of these cavities or notches 37 may be parallel or be slightly divergent, as illustrated in Figures 13, 14 and 15.

In the exemplary embodiment illustrated, the tenons 34 and the corresponding notches 37 are three in number, arranged at 120 ° respectively in the bottom of the housing 12 of the support structure 1, and at the periphery of the nut 10.

The cutting of the spherical crown 356 by the notches 37 gives a certain elasticity to the nut 10.

As shown in Figures 17 to 19, the clip 13 is in the form of a circular ring provided with a slot 38 giving it a certain radial elasticity.

On its outer periphery, this clip 13 is provided with a rib or peripheral boss 39 adapted to fit into the circular groove 33 of the housing 12 arranged in the support 1. The fitting of the clip 13 on the support structure 1 is made possible by the presence of the slot 38.

The clip 13 is sized to ensure that the nut 10 is held in the housing 12.

The clip 13 is also internally provided with a spherical crown 40 able to cooperate with the corresponding spherical crown 36 arranged on the nut 10.

As stated previously, at the end of screwing in the fixing screw 5, the various spherical crowns: - 7 on the head 6 of the screw 5, - 31 and 32 on the support 1, and - 35 and 36 on the nut 10, are concentric; once the assembly has been assembled, the corresponding center 23 is positioned substantially in the plane of the upper surface of the support plate 1, as shown in FIG. 9.