FR2743295A1 - Positioning implement for shoulder prosthesis - Google Patents

Abstract

The implement (1) has a sleeve (7) and a work head (8) for the glenoid bone (3). The work head has a pair of bosses (11) formed in the opposed ends of an elongated cavity (12) laterally defined by the grooved edges (13) of the osseous cut out and bordered by the bisectors (14) towards the interior of the cavity. The end bosses extend with respect to the edges and are adapted to engage in the corresponding holes (22) formed in the glenoid bone, when the head is forced into the latter and guides the implement during the forcing action on the edges.

Description

 The present invention relates to an ancillary device for orthopedic shoulder surgery, intended more particularly for the placement of a glenoid prosthesis on a scapula. Said prosthesis is intended to receive an articulation end of a humeral prosthesis. The ancillary includes a sleeve and a working head of the glenoid, and makes it possible to carry out in the glenoid cavity of the shoulder the bone cut necessary for the introduction and the installation of a keel to be cemented with a glenoid implant. artificial forming said glenoid prosthesis.

 According to the invention, the working head comprises a pair of bosses formed at the opposite ends of an elongated cavity, delimited laterally by cutting bone cutting edges, bevelled towards the inside of said cavity, the terminal bosses projecting by relative to these ridges and being adapted to engage in corresponding holes previously made in the glenoid, when the head is pressed into the latter, guiding the ancillary during the insertion of the edges.

 Other features and advantages of the invention will appear during the description which follows, given with reference to the accompanying drawings which illustrate an embodiment thereof by way of nonlimiting example.

 Figure 1 is a perspective view with cutaway and on an enlarged scale, of an embodiment of the ancillary according to the invention.

 Figure 2 is a sectional view along 2/2 of Figure 1.

 Figure 3 is a perspective view of a scapula showing in particular the glenoid or glenoid cavity.

 Figure 4 is a top view of the glenoid cavity after preliminary drilling of two holes in the glenoid, these holes being intended to receive the terminal bosses of the ancillary.

 FIG. 5 is a side elevation view of a glenoid prosthesis inserted into the glenoid cavity previously prepared by the tool shown in FIGS. 1 and 2.

 FIG. 6 is a cross-sectional view along 6/6 of FIG. 5.

 Figure 7 is a perspective view of the keel-shaped glenoid implant to be placed in the bone cut of the glenoid after its preparation by the ancillary according to the invention.

 The tool shown in the drawings is an ancillary device 1 intended to allow the fitting of a prosthesis 2 constituted by a keel on the glenoid 3 of a scapula 4 (FIG. 3). The keel 2 is constituted in a manner known per se by a plate 5 secured to a base 6, elongated and in the shape of a trapezoid (FIG. 5). The surface 5a of the plate 5 is concave and serves as a support seat for the articulation end of a humeral prosthesis not shown.

 The keel 2 has at least one transverse hole 25 in its base 6 and longitudinal grooves 26 on each of the large faces of the base. It is made of biocompatible polyethylene, but can also be made of any other biocompatible product. Such a keel 2 has the advantage of offering a maximum contact area with biological cement. In addition, the grooves 26 constitute means for hooking the cement, and the hole 25 forms a hooking bridge.

 The ancillary 1 includes a handle 7 and a head 8 adapted to prepare the glenoid 3 to receive the prosthesis 2.

The working head 8 comprises a body 9 elongated transversely to the handle 1, of which protrude, on the side opposite to the handle 1, a pair of bosses 11 formed at the opposite ends of an elongated cavity 12 formed in the face of the body 9 opposite to the round 1.

 The cavity 12 is delimited laterally by two cutting edges 13 of bone cut, bordered by bevels 14 extending towards the interior of the cavity 12.

On the other hand, the outer flanks 15 of the edges 13 are perpendicular to the surface of a peripheral shoulder 16 surrounding the base of the edges 13 and of the terminal bosses 11. The latter protrude relative to the edges 13 of a determined length I, and may have, as illustrated in the drawings, a semi-cylindrical outer surface 17 connecting to the outer sides 15 of the edges 13.

 Each boss 11 is also delimited by a flat inner wall 18 which constitutes a small side of the cavity 12, connecting the opposite ends of the edges 13, and by a flat end face 19, parallel to the cutting edges 13. Finally two holes 21 are arranged in the bottom of the cavity 12, preferably at the ends of the latter as shown.

 The preparation of the glenoid 3 for the installation of the keel 2 thereon, by means of the ancillary device 1, is carried out in the following manner.

 The surgeon drills a small hole in the center of the glenoid 3, through a passage in a template. Then he uses another template provided with a stud entering this hole (or the same template if he has this stud), this template being kept in the correct position by any suitable means such as a single clamp.

 In the template, on either side of the nipple, are formed two holes which correspond to the two semi-cylindrical bosses 11 of the head 8. The surgeon pierces through one of these holes the first hole 22 in the glenoid.

 I1 then places a second stud in the two coaxial holes of the template and the glenoid in order to fix the template. Then it drills the second cylindrical hole 22 in the same way, and it extracts the template.

 Then the surgeon takes the ancillary 1 and introduces the bosses 11 into the holes 22. When the latter have penetrated into the holes 22 of length 1, the cutting edges 13 come into contact with the bone surface of the glenoid 3. The surgeon continues to drive into the holes 22 of the bosses 11 which then serve as guides for the penetration of the edges 13 into the glenoid bone, until the shoulder 16 abuts on the surface of the glenoid 3. At the same time, the end faces 19 have practically reached the bottom of the holes 22 (Fig. 2).

 During the insertion of the edges 13 into the bone of the glenoid 3, bone debris is forced back by the pressure into the holes 21 and also into the part of the holes 22 left free by the substantially semi-cylindrical bosses 11. During the depression of the edges 13, the bevels 14 push the bone mass towards the interior of the cavity 12 and into the holes 21.

 The surgeon then removes the ancillary device 11 from the glenoid 3 and can put the keel 2 in place by inserting its base 6 into the housing thus prepared (Fig.5).

 The invention makes it possible to carry out a meticulous and progressive cutting while ensuring a frank and quality cut. This is of course obtained by the ancillary, but above all by the fact that this ancillary requires the surgeon, after having made his holes 22 with sufficient center distance, to partially bear on them to finally cut the bone part cleanly located between the two holes.

 The invention is not limited to the embodiment described and may include alternative embodiments. Thus the bosses 11 for guiding the tool could have a configuration different from that shown.

Claims (4)

 1. Ancillary (1) for placing a prosthesis (2) of glenoid on a scapula (4), said prosthesis being intended to receive an articulation end of a humeral prosthesis, comprising a handle (7) and a head (8) for working the glenoid (3), characterized in that the working head comprises a pair of bosses (11) formed at opposite ends of an elongated cavity (12), delimited laterally by cutting edges (13 ) of bone cut, bordered by bevels (14) towards the inside of said cavity, the terminal bosses projecting with respect to these edges and being adapted to engage in corresponding holes (22) previously made in the glenoid, when the head is inserted into the latter, guiding the ancillary device during the insertion of the edges (13).  2. Ancillary device according to claim 1, characterized in that the working head (8) is provided with a peripheral shoulder (16) surrounding the base of the edges and bosses (11) and forming a stop for sinking bosses in the holes (22) and cutting edges (13) in the bone.  3. Ancillary device according to claim 2, characterized in that holes (21) are arranged in the bottom of the aforementioned cavity (12) to receive bone debris during the insertion of the cutting edges (13) in the bone of the glenoid (3).  4. Ancillary device according to one of claims 1 to 3, characterized in that the bosses (11) have a substantially semi-cylindrical configuration with planar faces (18) facing the interior side of the cavity (12) and connecting the opposite ends of the edges (13).