FR3143971A3 - Set of elements making it possible to constitute a subassembly in the form of a medullary part of a humeral prosthesis and an instrument for installing this medullary part - Google Patents

Abstract

The invention relates to a set (1) of elements making it possible to constitute a subassembly formed of a medullary part (10) of a humeral prosthesis with distal holes (25) and an instrument (13, 14; 13, 15 ) aiming. According to the invention, - at least one medullary part (10) has proximal means for its assembly to a first connecting branch (14) and means for its assembly to a second connecting branch (15), located on the external side of the metaphyseal part (20) of this spinal piece (10); - the set of elements comprises a sighting branch (13) formed by a part separated from the two connecting branches (14, 15), and which is capable of being connected to one or the other of the latter. The first connecting branch (14) provides on its distal side a clearance (50) allowing it to bypass the tuberosities of a humerus. Figure for abstract: Figure 1

Description

Set of elements making it possible to constitute a subassembly in the form of a medullary part of a humeral prosthesis and an instrument for fitting this medullary part

The present invention relates to a set of elements making it possible to constitute a subassembly formed of a medullary part of a humeral prosthesis and an instrument for fitting this medullary part.

A shoulder prosthesis frequently comprises a humeral implant and a scapula implant coming into articulation with each other. The humeral implant is formed by a tapered medullary rod and by an articular part mounted on the proximal end of this rod, this articular part being in particular a head forming a convex articulation surface. The medullary rod is intended to be inserted inside the humerus suitably resected, and has a flared metaphyseal portion, intended to bear against the bony wall at the level of the metaphyseal portion of the bone, and a diaphyseal portion tending to take a constant cross-section, in particular cylindrical or slightly conical. When the condition of the bone requires it, this medullary rod is locked to the diaphyseal part of the humerus by means of transverse screws engaged through holes which then comprise the distal part of the rod; the instrumentation for placing the medullary rod comprises in this case a so-called "aiming" instrument, including a branch for connecting to the medullary rod and a targeting branch connected to this targeting branch, this targeting branch comprising guide bushings for a bone drilling drill; when the connecting branch is connected to the medullary rod, these drilling bushings come into coincidence with the holes in the medullary rod, and when the medullary rod is engaged in the bone, the targeting branch extends along the bone; the drilling bushings can then be used to pierce the wall of the bone in coincidence with the distal holes in the medullary rod.

Existing equipment includes dedicated instrumentation specific to the types of spinal rods concerned; the possession of these separate instruments is a significant practical constraint in terms of storage and the need for sterilization.

The present invention aims to remedy this significant drawback.

The set of elements concerned comprises, in a manner known per se, at least one medullary part of a shoulder prosthesis, a distal portion of which has holes for locking the part to the bone, and a so-called "aiming" instrument having a branch for connecting to the medullary part and a sighting branch connected to the connecting branch, having drilling barrels, these barrels coming into coincidence with the holes in the medullary part when the medullary part is connected to the connecting branch.

According to the invention,

- at least one medullary part has two distinct means for its assembly to a connecting branch, namely:

(i) first assembly means intended to allow the assembly of the medullary part to the connecting branch, at the proximal end of this part;

(ii) second assembly means arranged on the external side of the metaphyseal part of this medullary part;

- the set of elements comprises a sighting branch formed by a part separate from the connecting branch, and which is capable of being connected to the latter and of being immobilized relative to the latter; and

- the set of elements includes two types of connecting branches capable of being connected, one in place of the other, to the aiming branch, namely:

(i) the aforementioned connecting branch, equipped with third assembly means capable of cooperating with said first assembly means for assembling the proximal part of the medullary part to the end of this connecting branch; this connecting branch, hereinafter called the first connecting branch, has a bent or curved shape such that it provides on its distal side a clearance allowing it to go around the tuberosities of a humerus when these tuberosities are not fractured;

(ii) a second connecting branch, having a curved distal portion equipped with fourth assembly means capable of cooperating with said second assembly means for assembling the metaphyseal part of the medullary piece at the end of this second connecting branch, by the external side of this metaphyseal part.

Said first connecting branch thus provides, on its distal side, a clearance which allows it, while it is connected to the aiming branch, to bypass the tuberosities of a humerus when these tuberosities are not fractured; said second connecting branch is designed to carry out a lateral gripping of the metaphyseal part of the medullary part, at the level of the external side of this metaphyseal part, and can be used when the tuberosities of a humerus are fractured. The aiming instrument according to the invention is, in this way, adapted to the type of fracture to be treated, such that it is optimal in all cases. The same aiming branch is used in either of the two cases, which contributes to making the use of the aiming instrument that the set of elements according to the invention makes it possible to constitute practical.

Preferably,

- said first assembly means comprise a proximal tapped bore provided at the proximal end of the medullary part, an adapter and a mounting screw, the mounting screw being intended to be received in said tapped bore and to tighten the adapter against the proximal end of the medullary part; and

- said third assembly means comprise a bore provided through said first connecting branch and an assembly screw, the assembly screw being intended to be engaged through said bore and to come into screw engagement with a tapped hole provided in said adapter.

Preferably,

- said second assembly means comprise a pair of notches provided at the external side and the anterior and posterior sides of the metaphyseal part of the medullary part; and

- said fourth assembly means comprise a fork arranged at the end of said second connecting branch, formed by two parallel pins, these pins being capable of being engaged in a fitted manner in said notches.

According to one embodiment of the invention, the set of elements includes means for locking the engagement of the medullary part on the fork formed by said second connecting branch.

These locking means ensure that the medullary part is held on the fork.

It would be conceivable that these locking means could be arranged on the pins forming this fork; preferably, however, these locking means comprise:

- a threaded locking bore, provided in the medullary part, in particular between said notches;

- a locking rod having a threaded free end capable of being screwed into said threaded locking bore, and

- means ensuring the axial immobilization of the locking rod relative to the second connecting branch and/or relative to the sighting branch when said threaded free end is screwed into said tapped locking bore.

Thus, the screwed connection of said locking rod with the medullary rod ensures that the medullary part is held on the aiming instrument.

For its assembly to the sighting branch, each connecting branch may in particular form an engagement portion capable of being received in an adjusted engagement conduit that the sighting branch has, this sighting branch including a means for clamping the engagement portion in the engagement conduit in order to immobilize the connecting branch relative to the sighting branch. This clamping means may in particular be in the form of a pressure screw opening into the engagement conduit.

According to one possibility,

- said first connecting branch forms a tubular extension coaxial with said bore, extending in the distal direction, capable of receiving the assembly screw through it, the free distal end of this extension having angular positioning means; and

- the adapter has angular positioning means complementary to those presented by said extension, capable of cooperating with the angular positioning means presented by the extension so as to angularly position the adapter relative to the extension.

The adapter can thus be connected to the connecting branch while being perfectly positioned angularly in relation to the latter,

The angular positioning means presented by said extension may in particular be constituted by two diametrically opposed teeth, projecting from the distal free end of the extension in the longitudinal direction of this extension, and the angular positioning means presented by the adapter are constituted by an assembly portion to said extension, having two diametrically opposed indentations, capable of receiving the aforementioned teeth of the extension in an adjusted manner.

The set of elements according to the invention may include several types of medullary rods, in particular a first-line medullary rod, the diaphyseal part of which has a determined length, and a revision medullary rod, the diaphyseal part of which has a length greater than said determined length.

As is well known, a so-called "revision" spinal rod is used to replace a primary spinal rod when this becomes necessary.

Brief description of the figures

The invention will be better understood, and other features and advantages thereof will become apparent, with reference to the attached schematic drawing, which represents, by way of non-limiting example, a preferred embodiment of various elements forming part of the set of elements concerned. In this drawing,

is an exploded perspective view of various elements forming part of the set of elements concerned;

is a side view of a subassembly formed by the assembly of elements forming part of said assembly, which comprises a medullary rod and a sighting instrument adapted to this rod, the view being in section passing through a median plane of the rod and the instrument; the silhouette of a fractured humerus is also shown, the medullary rod being engaged inside this humerus;

is a view similar to the of another subassembly formed by the assembly of elements forming part of said assembly, which comprises a medullary nail and a targeting instrument adapted to this nail;

is a perspective view of yet another subassembly, formed by the assembly of elements forming part of said assembly, including a different sighting instrument; and

is a view of the subset shown in the , with the medullary rod assembled to the aiming instrument; the silhouette of a fractured humerus is also shown, with the medullary rod engaged inside this humerus.

Detailed description

There represents various elements which are part of a set 1 of elements making it possible to constitute, when assembled, sub-sets 2, 3 or 4 shown in figures 2 to 5.

Set 1 of elements essentially includes:

- a first-line 10 medullary rod;
- a medullary rod 11 called “revision”;
- a 12 medullary nail;
- a sighting branch 13;
- a first connecting branch 14 and a second connecting branch 15;
- a screw assembly 16;
- a 17 adapter;
- a mounting screw 18; and
- a locking rod 19.

As visible on the , the medullary rod 10 is intended to be inserted inside the humerus 100 to be treated, after the latter has been suitably resected. It has a flared metaphyseal portion 20, intended to bear against the bone wall at the level of the metaphyseal portion of the bone, and a tapered diaphyseal portion 21, tending to take a constant cross section, in particular cylindrical or slightly conical. The metaphyseal portion 20 has a pair of notches 22 arranged on its external side and on its anterior and posterior sides; between these notches 22, it has a tapped bore 23 visible in FIGS. 2 and 5, intended to receive a threaded end 60 of the locking rod 19.

The diaphyseal portion 21 has three holes 25 intended to receive transverse screws (not shown) through them, these screws making it possible to lock the rod 10 to the diaphyseal portion of the humerus 100. On its proximal side, the rod 10 has a conical cavity 26 intended for mounting an articular part (not shown), in particular a prosthetic humeral head; a tapped bore 27, visible on the , is arranged in the bottom of this cavity 26 to receive the mounting screw 18.

The medullary rod 11 has a shape similar to that of the rod 10, except that its metaphyseal part 20 is devoid of the aforementioned notches 22 and that its diaphyseal part 30 is longer than that of the rod 10; this diaphyseal part 30 comprises only one transverse hole 25, proximal, for which an aiming is likely to be made by means of the aiming instrument according to the invention. This rod 11 has a conical cavity 26 and a tapped bore 27 identical to those of the rod 10. Furthermore, this rod 11, being intended to be fixed to the bone by means of a polymerizable cement, has a smooth metaphyseal part 20, that is to say devoid of cavities or surface reliefs, or other porous coating, intended to be invaded by the growing bone cells, which the rod 10 has, the latter being intended to be fixed to the bone by such cellular growth.

The medullary nail 12 has a circular section over its entire length and is therefore devoid of a flared metaphyseal portion as mentioned above. At its proximal end, it has a tapped bore 31 which is coaxial with it as well as two diametrically opposed indentations 32. In a proximal portion, the nail 12 has, in a well-known manner, screw-receiving conduits allowing its fixation to the bone or the reception of a cervical screw, and, in a distal portion, it has a transverse hole 25 intended to receive a distal locking screw as mentioned above.

The aiming branch 13 has a widened proximal portion 35 forming an engagement duct 36 intended to receive in a fitted manner an engagement portion 37 or 38 which respectively comprise the connecting branches 14 or 15. A tapped hole opens into this duct 36 on the proximal side and is intended for the engagement of a pressure screw 39 allowing the immobilization of one or the other of the connecting branches 14 or 15 relative to the aiming branch 13. The latter also has a distal portion in which are arranged orifices 40 for receiving removable drilling barrels (not shown). As is well known, such barrels come into coincidence with the distal holes 25 which comprise one or the other of the rods 10 or 11 or the nail 12 and make it possible to guide a bone drilling drill so as to arrange holes in the bone coming into coincidence with these holes.

The aiming branch 13 also has, below the aforementioned widened proximal portion, a conduit 41 for receiving the body 61 of the locking rod 19. This conduit 41 and this body 61 have respective spiral ribs along themselves, which allow a certain friction of the body 61 when it is engaged in this conduit. This friction allows a certain retention of the position of the locking rod 19 relative to the aiming branch 13, avoiding untimely movements of this rod when the free end 60 of the latter is not screwed into the tapped bore 23 of the medullary rod 10.

The connecting branch 14 is intended to be connected to the sighting rod 13 to constitute the sighting instrument 2 shown in the when either of the rods 10 or 11 is intended to be connected to this branch. It has, at its end opposite the engagement portion 37, a bore 45 for receiving the assembly screw 16 as well as a tubular extension 46 coaxial with this bore, intended to be crossed by the screw 16. The bore 45 and the extension 46 have an axis substantially parallel to the longitudinal extension direction of the aiming branch 13. At its distal end, the extension 46 has two diametrically opposed teeth 47, which are intended to be received in a fitted manner in the indentations 32 that the proximal end of the nail 12 has, or in those, homologous, that an assembly ferrule 48 that the adapter 17 includes for its assembly to the extension 46 is also present. The latter is assembled to the branch 14 by forced insertion into the bore 45, with possibly gluing, welding or connection by shrinking.

As visible on the , when it is the nail 12 which is assembled to the connecting branch 14, by screwing the screw 16 into the tapped proximal bore 31, it is the subassembly 3 visible on the which is then constituted.

The connecting branch 14 has a doubly bent shape allowing it to provide, with the extension 46, a clearance 50 on its distal side; this clearance 50 allows the branch 14, in use, as visible in the , to bypass the tuberosities 101 of the humerus 100 to be treated, when these tuberosities are not fractured, and this, both with a rod 10 or 11 and with the nail 12.

The connecting branch 15 is intended to be assembled to the sighting rod 13 in place of the connecting branch 14 to constitute the sighting instrument 4 shown in FIGS. 4 and 5. In addition to the engagement portion 38, homologous to that of the branch 14, it has, on the side opposite this portion 38, a portion 51 curved over substantially a quarter of a circle, ending in a fork formed by two parallel pins 52, these pins 52 being intended to be received in an adjusted manner, by sliding, in the notches 22.

Between the pins 52, a bore 53 is provided for the passage of the locking rod 19, to allow the end 60 of this rod to be screwed into the bore 23 of the rod 10.

Furthermore, as visible on the , the portion 51 of the branch 15 forms a cavity 54 coaxial with the bore 53, opening onto the side of the free end of this portion which is intended to be turned towards the sighting branch 13. As shown, this cavity 54 is intended to receive a cylindrical stop portion 62 formed by the locking rod 19, which comes to bear against the bottom of this cavity 54 when the threaded end 60 is screwed into the bore 23, thus ensuring that the pins 52 are maintained in the notches 22.

The adapter 17 has a body 55 of flattened shape, the outline of which corresponds to that of the proximal face of the metaphyseal part 20 of one or other of the medullary rods 10 or 11. The plane in which this body 55 extends forms an angle adapted to the adequate orientation of one or other of the rods 10 or 11 when the latter are connected to the branch 14, so that these rods extend in a longitudinal direction substantially parallel to the direction in which the aiming rod 13 extends, as can be seen in the figure. In practice, this angle is of the order of 135°.

The locking rod 19, for its part, has the threaded end 60, the body 61 and the cylindrical portion 62 already described.

As appears from the above, the invention provides a set 1 of elements making it possible to constitute a sub-assembly 2, 3 or 4 formed of a medullary part 10, 11 or 12 of humeral prosthesis and an instrument 13, 14 or 13, 15 for fitting this medullary part which has the following determining advantages:

- allow the assembly, on the same connecting branch 14 and by means of the same assembly screw 16, of either the medullary rod 10, 11, by means of the adapter 17, or of the medullary nail 12, which makes it possible to considerably reduce the requirements in terms of storage and sterilization of such installation equipment;

- allow the practitioner to easily choose, during the procedure, to implant either a medullary rod 10, 11, or a medullary nail 12, depending on the situation encountered, given that he uses substantially the same installation material in both cases;

- allow the aiming instrument to be adapted depending on whether the tuberosities 101 are fractured at the step, using one or other of the connecting branches 14 or 15, so that this instrument is always optimal in relation to the situation to be treated.

Claims (9)

Set (1) of elements making it possible to constitute a subassembly (2, 4) formed of a medullary part (10) of a humeral prosthesis and an instrument (13, 14; 13, 15) for fitting this medullary part, the medullary part (10) having, at its distal portion, holes (25) for locking the part to the bone; the fitting instrument is a so-called "aiming" instrument having a branch (14, 15) for connection to the medullary part (10) and a sighting branch (13) connected to the connection branch (14, 15), having drilling barrels, these barrels coming into coincidence with the holes (25) of the medullary part (10) when the medullary part is connected to the connection branch (14, 15);
characterized in that:
- at least one medullary part (10) has two distinct means for its assembly to a connecting branch (14, 15), namely:
(i) first assembly means (17, 18, 27) intended to allow the assembly of the medullary part (10) to the connecting branch (14, 15) at the proximal end of this part;
(ii) second assembly means arranged (22) on the external side of the metaphyseal part (20) of this medullary part (10);
- the set of elements comprises a sighting branch (13) formed by a part separate from the connecting branch (14, 15), and which is capable of being connected to the latter and of being immobilized relative to the latter; and
- the set (1) of elements includes two types of connecting branches capable of being connected, one in place of the other, to the aiming branch (13), namely:
(i) the aforementioned connecting branch (14), equipped with third assembly means (16, 45) capable of cooperating with said first assembly means (17, 18, 27) for assembling the proximal part of the medullary part (10) to the end of this connecting branch (14); this connecting branch (14), hereinafter referred to as the first connecting branch, has a bent or curved shape such that it provides on its distal side a clearance (50) allowing it to go around the tuberosities of a humerus when these tuberosities are not fractured;
(ii) a second connecting branch (15), having a curved distal portion (51) equipped with fourth assembly means (52) capable of cooperating with said second assembly means (22) for assembling the metaphyseal part (20) of the medullary part (10) at the end of this second connecting branch (15), by the external side of this metaphyseal part (20). Set (1) of elements according to claim 1, characterized in that
- said first assembly means comprise a proximal tapped bore (27) arranged at the proximal end of the medullary part (10), an adapter (17) and a mounting screw (18), the mounting screw (18) being intended to be received in said tapped bore (27) and to tighten the adapter (17) against the proximal end of the medullary part (10); and
- said third assembly means comprise a bore (45) provided through said first connecting branch (14) and an assembly screw (16), the assembly screw (16) being intended to be engaged through said bore (45) and to come into screw engagement with a tapped hole provided in said adapter (17). Set (1) of elements according to claim 1 or claim 2, characterized in that
- said second assembly means comprise a pair of notches (22) arranged at the external side and the anterior and posterior sides of the metaphyseal part (20) of the medullary part (10); and
- said fourth assembly means comprise a fork arranged at the end of said second connecting branch (15), formed by two parallel pins (52), these pins being capable of being engaged in a fitted manner in said notches (22). Set (1) of elements according to claim 3, characterized in that it includes means (19, 23) for locking the engagement of the medullary part (10) on the fork formed by said second connecting branch (15). Set (1) of elements according to claim 4, characterized in that the locking means comprise:
- a tapped locking bore (23), provided in the medullary part (10), in particular between said notches (22);
- a locking rod (19) having a threaded free end (60) capable of being screwed into said tapped locking bore (23), and
- means (54, 62) ensuring the axial immobilization of the locking rod (19) relative to the second connecting branch (15) and/or relative to the sighting branch (13) when said threaded free end (60) is screwed into said tapped locking bore (23). Set (1) of elements according to one of claims 1 to 5, characterized in that each connecting branch (14, 15) forms an engagement portion (37, 38) capable of being received in an adjusted engagement conduit (36) presented by the aiming branch (13), this aiming branch (13) including a means (39) for clamping the engagement portion (37, 38) in the engagement conduit (36) in order to immobilize the connecting branch (14, 15) relative to the aiming branch (13). Set (1) of elements according to claim 2, characterized in that
- said first connecting branch (14) forms a tubular extension (46) coaxial with said bore (45), extending in the distal direction, capable of receiving the assembly screw (16) through it, the free distal end of this extension (46) having means (47) for angular positioning; and
- the adapter (17) has angular positioning means complementary to those presented by said extension (46), capable of cooperating with the angular positioning means presented by the extension so as to angularly position the adapter (17) relative to the extension (46). Set (1) of elements according to claim 7, characterized in that the angular positioning means presented by said extension (46) are constituted by two diametrically opposed teeth (47), projecting from the distal free end of the extension (46) in the longitudinal direction of this extension, and in that the angular positioning means presented by the adapter (17) are constituted by a portion (48) for assembly to said extension (46), having two diametrically opposed indentations, capable of receiving the aforementioned teeth (47) of the extension (46) in an adjusted manner. Set (1) of elements according to one of claims 1 to 8, characterized in that it includes several types of medullary rods, in particular a first-line medullary rod (10), the diaphyseal part (21) of which has a determined length, and a revision medullary rod (11), the diaphyseal part (30) of which has a length greater than said determined length.