FR2650174A1 - Artificial acetabulum for hip prostheses and system for putting it into position - Google Patents

Abstract

The present invention relation to an artificial acetabulum for hip prostheses, of the type comprising an outer face which is inscribable in a sphere and at least one element for anchoring in the acetabular cavity of the iliac bone. According to the invention, the said anchoring element 2 comprises an outer part in the form of a point or tooth intended to permit a straightforward positioning of the acetabulum 1 by driving it into the acetabular cavity of the iliac bone.

Description

Cotyte artificial for hip prostheses and system for its reading in place
The present invention relates to an artificial acetabulum for hip prostheses and a system for its implementation.

 The invention finds particular application in the field of orthopedic surgery.

 We know that a total hip prosthesis comprises an acetabular part called the acetabulum, of generally hemispherical hollow shape, intended to be fixed with or without cement in the acetabular cavity of the iliac bone, and a femoral part with a spherical head coming Stay in the acetabuar room to artificially reconstruct the hip joint.

 To avoid any risk of loosening of the artificial cups, many solutions have been proposed, to ensure safe and easy fixation of the cup in the cup cavity.

 Thus, for a long time, this fixing was ensured by means of a cement, in particular of acrylic nature. Patent No. 2,060,179 illustrates, for example, this state of the art.

 However, in particular in order to ensure better contact between the prosthetic part and the bone, we turned to cementless fixings, and new forms of acetabulum were developed.

 This is how, especially in French patent No. 2,099,259, cups have been described which can be screwed into the cotyloid cavity.

 We have also proposed so-called "impacted" acetabular cups generally fixed to the pelvis using screws or anchoring elements such as tenons.

 This state of the art is described in particular in French patent No. 70 25 848.

 The insertion of such acetabular cups requires, in addition to traditional milling of the acetabular cavity, precise drilling to provide a housing for each anchoring stud.

 Thus, the implementation of such cups is delicate and insecure, since there are still loosening of this type of cups.

 The present invention therefore aims to solve the aforementioned drawbacks by proposing an artificial cup of a new design which allows, by its particular conformation, a secure and easy attachment to the cup cavity.

The solution, in accordance with the present invention, to solve this technical problem, consists of an artificial acetabulum for hip prostheses, of the type comprising an external face which can be written in a sphere and at least one anchoring element in
The acetabular cavity of the iliac bone, characterized in that said anchoring element comprises an end portion in the shape of a point or tooth intended to ensure easy positioning of the acetabulum by pressing into the acetabular cavity of the iliac bone .

 According to a particular characteristic of the invention, this acetabulum further comprises means of assembly to a driving device produced for example in the form of an opening preferably arranged at the top of said acetabulum, shaped to receive a part of conjugate shape disposed at one end of said driving device.

 According to another particular characteristic, a cup according to the invention further comprises at least two oblong openings, extending substantially parallel to the opening plane of the cup, shaped to accommodate without head the anchor screw head intended to fix Said acetabulum in the acetabulum cavity.

 Advantageously, the number of aforementioned openings and their arrangement are chosen such that any hemispherical spindle of said cup has at least one opening whose dimensions are sufficient for the placement of a screw.

This advantageous conformation ensures the existence of an opening, and therefore the possibility of fitting a screw at any spindle of the acetabulum, that is to say in an angular position as seen in the opening plane. of the acetabulum.

 According to a second aspect of the invention, there is proposed a system for the place of a cup as described above, characterized in that it comprises a driving device constituted by a rod comprising at one end a shaped head for be housed in said cup, while being assembled therein.

According to another aspect, the invention provides a system for the establishment of a cup as described above, characterized in that it comprises a means forming a drilling guide for the installation of the fixing screws, shaped to be rotatably mounted inside said cup and comprising a set of internal channels arranged in predetermined directions allowing
The flat comfort of said screws without overflowing their head inside the acetabulum.

The invention will be better understood, and other objects, characteristics and advantages thereof will appear more clearly in the light of the explanatory description which follows, made with reference to the accompanying diagrammatic drawings given solely by way of nonlimiting example. and illustrating a currently preferred embodiment of the invention, and in which
- Figure 1 is a perspective view of a cup according to the invention;
- Your Figure 2 is a perspective view of a sinking device and a cup, before sinking into your cotyLoide cavity;
- Figure 3 is a front view of a device forming a drilling guide intended to allow the fixing by screw of a cup such as that shown in Figure I;
- Figure 3A is a side view;
- Figure 4 is a perspective view showing a device forming a drilling guide and a socket before assembly; and
- Figure 5 is a perspective view showing a device forming a drilling guide and a cup in the use position.

 FIG. 1 therefore shows a cup I according to a presently preferred embodiment of the invention.

 This acetabulum 1, of general shape The hemispherical comprises an external face which can be written in a sphere and three anchoring elements 2, intended to allow a primary fixation of the acetabulum in the acetabulum cavity by depression.

The anchoring elements 2 are made in the shape of a point or tooth projecting outside the acetabulum,
Slightly beyond the top of the latter, and are arranged substantially axially, that is to say in a direction substantially perpendicular to the plane P of opening of the acetabulum.

 Preferably, the anchoring elements 2 are regularly spaced angularly, around 1800 in the example shown.

 The anchoring elements 2 can be of various shapes, and are produced for example in the form of a tooth of substantially triangular cross section, with a thickness of approximately 0.5 to 1 mm. Any pointed shape can of course be considered.

 Likewise, the number of anchoring elements can be varied, but must be sufficient to allow effective primary anchoring to be ensured, intended to facilitate the subsequent final positioning of the acetabulum by means of screws.

 The cup 1 and the anchoring elements 2 will be made from the materials usually used for the manufacture of the cups, for example made of titanium, the external surface being optionally lined with porous metal to promote anchoring by reossification.

 As shown in Figure I, the cup 1 has at its aperture an opening 3 of substantially square shape in the example shown, intended to receive a part of conjugate shape disposed at one end of a driving device 4 such as that shown in figure 2.

 With reference to this FIG. 2, a driving device, in accordance with the invention, comprises a rod 10 extended at one end by a head 5 of generally hemispherical shape, the dimensions of which are chosen to allow it to fit inside the acetabulum. 1.

The head 5 of the driving device comprises at its top a projecting part 3a, of shape combined with that of
The opening 3, shaped to allow temporary non-rotating coupling of the driving device 4 and the cup 1.

 The driving device 4 further comprises at its other end a plate 6 to allow the driving of the acetabulum by means of a percussion tool such as a hammer or a mallet.

The primary fixation of the acetabulum in the acetabular cavity is therefore carried out in the following manner:
After having carried out the conventional operation of preparation by milling of your acetabular cavity, the acetabulum is positioned, the pointed portion of the anchoring elements 2 coming into contact with the acetabular cavity;

 Then the driving device 4 and the cup 1 are assembled, the head 5 of the driving device 4 being received in the opening 3 of the cup 1.

 Then, the cup is inserted by means of a percussion tool, until the external face of the cup comes into contact with the cup cavity and where the anchoring elements have been fully engaged in the cotyloid cavity.

 This primary fixation of the acetabulum is solidified by means of vRs, as iL will be described below, so as to oppose any displacement of the acetabulum in the acetabulum cavity.

 As shown in FIG. 1, the cup 1 comprises several oblong openings extending substantially parallel to the plane P of opening of the cup and shaped to accommodate without overhanging the head of the anchoring screw intended to fix the cup 1 in the cotyloid cavity. For this purpose, these openings will be milled according to the dimensions of the heads of the screws used for anchoring.

 In the example shown, the cup I comprises two series of openings 7a, 7b arranged in regular spaced apart, extending in two planes parallel to the opening plane P of the cup and spaced apart.

 Preferably, the number of openings and their arrangement are chosen so that any hemispherical spindle of the acetabulum 1 has at least one opening whose dimensions are sufficient for the placement of a screw.

 In the example shown, each series of openings comprises three openings angularly spaced by about 1200, the openings of one series being angularly offset with respect to the openings of the other series and arranged on the portion of hemispherical spindle defined between two consecutive openings of said other series.

 FIGS. 3, 3A and 4 show a means forming a drilling guide 9, intended to facilitate the fitting of the fixing screws.

 The drilling guide 9 is shaped so that it can be rotatably mounted inside the cup 1. For this purpose, it comprises a first substantially cylindrical portion II which can be received rotating inside the cup 1 and a second portion in the form of disc 12, the dimensions of which are slightly greater than the dimensions of the opening edge of the cup 1, this disc forming portion 12 constituting a cooperating shoulder, in the position of use with the opening plane of the cup, to prevent any movement of the guide of drilling relative to the acetabulum in a direction perpendicular to the opening plane P (see FIG. 5).

The drilling guide 9 includes a set of internal channels arranged in predetermined directions to allow the placement of the screws without overflowing their head.
The interior of the cup.

 In the example shown, the drilling guide 9 comprises two internal channels 13, 14 unidirectional threats in directions respectively forming angles of and with the plane P 'of the disc part 12.

 These channels 13, 14 open on the one hand, through orifices 13a, 14a on the disc part 12, and on the other hand, through orifices 13b, 14b on the external face of the upper part 11 of the drilling guide 9 .

 The directions of the channels 13, 14 are chosen according to the position of the openings of the acetabulum 1, so that the orifices 13b, 14b are, in the position of use of the drilling guide 9 (as shown in FIG. 5) , on the same plane of Latitude (plane, parallel to the plane P of opening of the acetabulum) as a series of openings.

 Thus, as shown in FIG. 5, the orifice 13b is located on the same plane of latitude as the series of openings 7b closest to the opening ptan P of the acetabulum, while the orifice 14b is located on the same plane of latitude as The other series of openings 7a.

 Generally, the number of channels of the drilling guide 9 will be equal to the number of series of acetabulum openings.

It should be noted that the piercing device 9, according to
The invention can be used ~ with other types of cup than that shown in Figure 1, for example, with a cup provided with anchor pins instead of the point anchor elements 2.

 As can be understood, in order to put the acetabulum fixing screws in place easily, the drilling guide 9 is introduced inside the acetabulum previously fixed by means of the anchoring elements 2, until the part forming a disc 11 of the drilling guide 9 comes into abutment against the opening edge of the acetabulum.

Then rotate the drilling guide 9 to
The interior of the cup 1, so as to coincide with the outlet 13b, 14b of one of the channels 13, 14 of the drilling guide 9 and an opening 7a, 7b of the cup.

 You can then drill the cotyloid cavity to introduce a fixing screw. The opening 7a, 7b being suitably milled and the drilling direction predetermined, the screw can be introduced without overflowing its head inside the acetabulum,

Claims (9)

 1. Artificial acetabulum for hip prostheses, of the type comprising an external face inscribable in a sphere and at least one anchoring element in the cotyLoid cavity of the iliac bone, characterized in that said anchoring element (2) has an end portion in the shape of a tip or tooth intended to allow easy fitting of the acetabulum (1) by pressing into the acetabular cavity of the iliac bone.  2. Cup according to claim 1, characterized in that it comprises three anchoring elements (2) substantially axial and regularly spaced angularly.  3. Cup according to your claim 1 or 2, characterized in that it comprises means of assembly to a driving device made for example in the form of an opening (3) preferably arranged at the top of said cup, and shaped to receive a part of conjugate form disposed at one end of a driving device (4).  4. Cup according to one of claims 1 to 3, characterized in that it comprises at least two oblong openings (7a, 7b), extending substantially parallel to the plane (P) of opening of the cup, shaped to accommodate without overflow the head of the anchoring screw intended to fix said acetabulum in the acetabular cavity.  5. CotyLe according to claim 4, characterized in that it comprises at least two series of openings (7a, 7b) preferably arranged in a regularly angularly spaced manner, and extending in two planes parallel to the plane tP) d ' cup opening and spaced.  6. Cup according to claim 4 or 5, characterized in that the number of aforementioned openings and their arrangement are chosen such that any hemispherical spindle of said cup has at least one opening whose dimensions are sufficient for the establishment of a screw.  7. Cup according to one of claims 4 to 6, characterized in that it comprises two series of openings (7a, 7b), preferably three openings, arranged in a regularly angularly spaced manner, the openings (7a) d 'A series being angularly offset relative to the openings (7b) of the other series and arranged on the portion of hemispherical spindle defined between two consecutive openings of said other series.  8. System for the establishment of a cup according to one of claims 1 to 7, characterized in that it comprises a driving device (4) constituted by a rod (10) having at one end (5 ) a head shaped to be housed in said cup by being assembled to it.  9. System for the establishment of a cup according to one of claims 1 to 7, characterized in that it comprises a means forming a drilling guide (9) for installing the fixing screws shaped to be rotatably mounted inside said cup (1) and comprising a set of internal channels arranged in predetermined directions allowing the positioning of said screws without overflowing their head inside said cup.