FR2967048A1 - Assembly for hip prosthesis elements to be implanted in femoral barrel for surgical kit utilized for patient during treatment, has stems whose dimension is in concordance with stem of another series so as to allow replacement of stem - Google Patents

Abstract

The assembly (1) has a series (2) of curved femoral stems (20) dimensioned to form a set of line stems, and another series (3) of femoral stems (30). Length between support shoulders and distal ends of the two series of stems are respectively different from a distal end of the other stems of the same series. Dimension of each stem of the former series is in concordance with one of the stems of the latter series so as to allow replacement of the stems of the former series with the predetermined corresponding stem of the latter series.

Description

BACKGROUND OF THE INVENTION The invention relates to the field of femoral prostheses, and more particularly to a family of hip prosthesis elements. [002] In conventional manner, a hip prosthesis mainly comprises a rod intended to be introduced into the femur and a neck arranged to receive directly or indirectly a cup for cooperating with the acetabulum of the iliac bone. There are different techniques for laying stems. The general principle, however, is to hollow out the femur to form a medullary canal, and to marry its anatomy by implanting in the medullary canal a stem which, by its curvatures, will ensure an intimate contact with the residual cortical bone (called femoral shaft or recipient bone). [3] In order to allow a satisfactory anchoring of the stem in the medullary canal on the one hand and to ensure an adequate restoration of the height of the femur on the other hand, the choice of a stem adapted to the morphology of the patient, is essential, especially when the stems are anchored by growth of bone cells around them and through the osteoconductive coating they are covered. [4] It is therefore common to provide the same range of femoral stems with several sizes so that the femoral stem having the size best suited to the morphology of the patient to be treated can be chosen. Among the ranges of the state of the art, French Patent Application FR2853524 is known in particular from a range of femoral stems comprising a tapered diaphyseal portion progressing in length, width and thickness in a homothetic manner from a stem size to an immediately superior stem size so that a stem as close as possible to the femoral shaft can be chosen, the one depending on the morphology of the patient. [5] In addition to this type of femoral stems of "conventional" lengths, there are also so-called first-line stems. These are stems shorter in length than conventional femoral stems. This type of short stems is used especially for "virgin" hips, ie hips that have not already been operated on or infected. This type of rods have the advantage of requiring little sacrifice of bone compared to conventional femoral stems.

Their use, however, requires a sufficient bone quality of the femur in which they are intended to be implanted. In some cases, first-line stems are eventually replaced by rods of conventional lengths (referred to as hip resumption). [6] Moreover, it is intraoperatively that existing bone damage and bone fragility are assessed. Similarly, if the choice of the length of the femoral stem is made prior to the surgical procedure, it is during the intervention that the final adjustment of the height of the reconstruction takes place. It may be that the initial choice of the first-line rod appears inappropriate during the surgical procedure (poor bone quality, greater bone damage than estimated, etc.) and in fact requires the use of a rod. classic femoral.

[7] The replacement of a femoral stem of first intention implanted, or in anticipation of being implanted, by a conventional femoral stem imposes to rework the femoral shaft to give it not only the height (or length) but also the adequate form for placement of the replacement femoral stem chosen. This recovery of the femoral shaft can be long, especially since the choice of the most suitable stem is made during the procedure, and thus have more or less important postoperative consequences. Indeed, none of the conventional rods currently on the market offer sufficiently similar shapes to allow the replacement of a first-line rod without making a sometimes important catch-up. [8] The invention aims to remedy these problems by proposing a family of elements of femoral prosthesis offering the installation of first-line femoral stems and conventional femoral stems capable of forming replacement rods of the first-line stems of the family by providing a minimum of bone sacrifice. [009] The invention also aims to provide a family of femoral prosthesis elements for a quick, accurate and easy replacement of a first-line rod by a rod of conventional size. For this purpose, and according to a first aspect, the invention provides a family of hip prosthesis elements to be implanted in a femoral shaft, comprising a first series of femoral stems, of curved shape, sized to form stems. first-line and a second series of femoral stems, and wherein: - each stem of the first series has, at the proximal end, a bearing shoulder to receive an ancillary for the purpose of implantation of the stem in the femoral shaft each stem of the second series comprises, at the proximal end, a bearing shoulder for an ancillary device for the purpose of implanting the stem in the femoral shaft, each stem of the first series having a length between the shoulder; and the distal end different from those of the other rods of the first series, - each rod of the second series has a length between the shoulder and the distal end different from the other rods of the second series, and - each rod of the first series having a dimensional concordance with one of the rods of the second series so as to allow the replacement of a rod of the first series with a predetermined corresponding rod of the second series, the rods of the first series differing from their corresponding rods of the second series by a lower length. This dimensional correspondence thus minimizes the catching of the femoral shaft and thus limit the intervention time required to achieve it. Advantageously, the dimensional correspondence of the rod of the first series with the corresponding rod of the second series is provided on the one hand by a diaphyseal upper portion of the rod of the first series of the same dimensions as the diaphyseal upper portion of the corresponding stem of the second series and secondly by a metaphyseal lower part of longitudinal axis of symmetry Al coincides with the longitudinal axis of symmetry B1 of the metaphyseal lower part of the corresponding rod of the second series.

This correspondence between the upper parts of a first-intention stem and an associated conventional stem thus imposes that only the lower zone of the femoral shaft corresponding to the metaphyseal lower part of the conventional stem must be reworked, and in particular lengthened and slightly enlarged to allow implantation of the conventional stem (ie of the second series) to replace the associated first-line rod. In a particular configuration, the ratio between the length of a rod of the first series with the length of the associated rod of the second series is between 0.65 and 0.75. According to a particular embodiment, there is provided rods of the first series having a length of between 85 millimeters and 115 millimeters. In this context, it will be advantageous to provide rods of the second series having a length between between 125 millimeters and 160 millimeters. Advantageously, the diaphyseal upper portion of each rod of the first series has a length corresponding to about two thirds of the length of the rod.

Advantageously, the first series of rods are covered, at least on the diaphyseal upper part, a porous coating with a rough surface state. Such a coating has the advantage of improving the bone reconstruction around the stem while facilitating the setting of the stem in the femoral shaft. In another aspect, the invention relates to a surgical kit for implanting a hip prosthesis, the kit comprising a family of hip prosthesis elements as described above. Advantageously, the surgical kit comprises a plurality of rasps, some allowing the realization of recesses adapted to the dimensions of the rods of the first series, the others allowing the realization of recesses adapted to the dimensions of the rods of the second series. [0019] Advantageously, the surgical kit comprises a plurality of test collars. Advantageously, the surgical kit comprises an ancillary for the implantation of each of the femoral stems of the first and second series in the femoral shaft formed for this purpose in the femur. Other objects and advantages of the invention will become apparent from the following description, made with reference to the accompanying drawings, in which:

FIG. 1 is a view in the frontal plane of a family of fourteen hip prosthesis elements according to the invention composed of seven first-line rods and seven conventional rods, the first-line rods being represented superimposed on the conventional rods; corresponding (associated);

FIG. 2 is a detail view, in the frontal plane, of one of the first-line rods constituting the family and illustrated in FIG. 1;

FIG. 3 is a view from behind, in the sagittal plane, of the first-line rod of FIG. 2; and

FIG. 4 is a detail view, in the frontal plane, of one of the conventional rods constituting the family and illustrated in FIG. 1. In relation to FIGS. 1 to 4, a family of FIG. hip prosthesis elements 1 to implant in a femoral shaft (not shown). The family of hip prosthesis elements 1 according to the invention comprises two series of femoral stems: a first series 2 of femoral stems 20, of curved shape, sized to form first-line stems and a second series 3 femoral stems 30, tapered shape. In the embodiment described, the family is composed of fourteen elements, ie seven femoral stems 20 constituting the first series 2 and seven femoral stems 30 composing the second series 3.

As shown in Figure 1, the rods 20, 30 of each of the series 2, 3 differ mainly by their length. Thus, each of the series 2, 3 respectively comprises rods whose lengths increase or decrease from one rod to another rod of size immediately higher or lower. Likewise, the femoral stems 20 of the first series 2 are of shorter length than the femoral stems 30 of the second series 3. In the present application, the length L is defined as the distance between the distal end 21, 31 rods 20, 30 and the shoulder 22, 32 formed at the proximal end 23, 33 of the rods 20, 30 (Figures 2 and 4). Advantageously, the femoral stems 20 of the first series 2 have a length of between 85 millimeters and 115 millimeters and the femoral stems 30 of the second series 3 a length between between 125 millimeters and 160 millimeters. More particularly, the ratio between the length of the rod of the first series and the length of the associated rod of the second series is between 0.65 and 0.75, a difference in length of between about 40 and 45 millimeters. Of course, the length and all the features in the present application are only exemplary and therefore may be different without departing from the scope of the invention. It should be noted that according to a particular configuration, it can be provided femoral rods having homothetically increasing or decreasing dimensions, in all directions (that is to say, according to the length, width and width). thickness) from one rod to another of immediately larger or smaller size. According to the invention, each femoral stem 20 of the first series 2 is associated, due to its size and shape, to one of the femoral stems 30 of the second series 3.

More particularly, and as shown in Figure 1, each femoral stem 20 of the first series 2 comprises a diaphyseal upper portion 24 of the same dimensions and substantially of the same shape as that of the femoral stem 30 of the second series to which she is associated. The diaphyseal upper part 24 is characterized by a height H varying from one stem to another rod of the same series. More particularly, the height H of a diaphyseal upper portion 24 increases or decreases from one rod to another of immediately larger or smaller size. As an illustration, for femoral stems having lengths in the range indicated above, the height H is between 68 and 75 millimeters. Furthermore, each femoral stem 20 of the first series 2 comprises a metaphyseal lower portion 25 of Al axis of symmetry. As illustrated in Figures 2 and 3, the axis A extends between the distal end. 21 of the femoral stem 20 and a cavity 26 formed in the shoulder 22, at the proximal end 23. The cavity 26 is intended to receive an ancillary which, by support or by impact, will allow the depression of the rod in the channel Medullary of the femur. Similarly, each femoral stem 30 constituting the second series 3 comprises a metaphyseal lower portion of axis of symmetry B,. As illustrated in FIG. 4, the axis B1 extends between the distal end 31 of the femoral stem 30 and a cavity 36 formed in the shoulder 32, at the proximal end 33 of the femoral stem 30. The cavity 36 exerts the same function as the cavity 26 formed on the femoral rods of the first series 20. In order to ensure the concordance between the femoral stems of first intention formed by the rods 20 of the first series 2 and the replacement rods constituted by the femoral stems 30 of the second series 3, the femoral stems 20, 30 of each of the series 2, 3 are arranged so as to have metaphyseal lower portions 25, with respectively symmetry axes Al and B, being illustrated in FIG. 1. In the embodiment described, and as shown in FIGS. 1 and 2, the diaphyseal upper portion 24 of each femoral stem 20 of the first series 2 has a length corresponding to about two-thirds of the length of the rod in question.

Furthermore, each femoral stem 20 of the first series 2 has a cervico-diaphyseal angle identical to that of the femoral stem 30 of the second series 3 with which it is associated. The cervicodiaphyseal angle α is defined between the axis of symmetry A1 and B1 of the lower part 25, metaphyseal and the axis of symmetry A2 and B2 of the cavity 27, 37 intended to receive the modular neck forming the prosthesis (cervix not shown). Advantageously, the cervico-diaphyseal angle is about 135 degrees. The realization of femoral stems 20 of first intention and femoral stems 30 adapted to be used as replacement rods having i) a shape concordance at the diaphyseal upper part of the rod of first intention, ii) axes of identical symmetry AI and B1 and iii) preferably having the same cervico-diaphyseal angle, makes it possible to ensure a single match between two femoral rods constituting each of the series and thus to provide for each first-line rod constituting the first series a specific replacement rod. [0036] Advantageously, the femoral stems 20, 30 are covered, at least on the diaphyseal upper part 24, 34 (ie in the embodiment described on the two-thirds proximal of the stem), with a porous coating, such as porous titanium, advantageously comprising a bioactive compound based on hydroxyapatite (PAH). Advantageously, the coating comprises reliefs formed of peaks separated by hollows, to allow a better grip and a greater contact area with the femoral shaft. In a particular configuration, the reliefs do not cover the entire surface of the femoral stem 20. The non-relief portion is delimited by an axis forming with the axis AI an angle 13 of the order of 30 degrees (FIG. ). In the embodiment described, the femoral stems 20, 30 of the first and second series 2, 3 comprise modular neck prostheses. In other words, each of the rods constituting the first and second series comprises a cavity 27, 37 of axis A2, B2 intended to receive a neck of conjugate form. It is of course obvious that the present invention is not limited to this type of prosthesis, and that rods provided with fixed necks can be provided without departing from the scope of the invention. The invention is described in the foregoing by way of example. It is understood that the skilled person is able to achieve different embodiments of the invention without departing from the scope of the invention.

Claims (10)

REVENDICATIONS1. A family of hip prosthesis elements (1) to be implanted in a femoral shaft, comprising a first series (2) of femoral stems (20), curved in shape, sized to form first-line stems and a second series (3) ) of femoral rods (30), each rod (20, 30) of the first series (2) and the second series (3) having, at the proximal end (23, 33), a bearing shoulder (22, 32 ) to receive an ancillary for the implantation of the rod in the femoral shaft, each rod (20, 30) of the first series (2) and the second series (3) respectively having a length between the shoulder of support (22, 32) and the distal end (21, 31) different from those of the other rods of the same series, and each rod (20) of the first series (2) having a dimensional concordance with one of the rods (20). ) of the second series (3) so as to allow the replacement of a rod (20) of the first series (2) with a e corresponding predetermined stem (30) of the second series (3). 2. Family of elements (1) of hip prosthesis according to claim 1, characterized in that the dimensional agreement of a rod (20) of the first series (2) with the rod (30) corresponding to the second series (3) is provided firstly by an upper portion (24) diaphyseal of the rod (20) of the first series (2) of the same dimensions as the upper portion (34) of the diaphyseal shaft (30) corresponding to the second series (3) and secondly by a lower part (25) metaphyseal having a longitudinal axis of symmetry Al coincides with the longitudinal axis of symmetry B1 of the lower part (35) metaphyseal of the corresponding rod (30) of the second series (3). 3. Family of hip prosthesis elements (1) according to claim 1 or claim 2, characterized in that the ratio between the length of the rod (20) of the first series (2) and the length of the rod (30) associated with the second series (3) is between 0.65 and 0.75. 4. Family of elements (1) of hip prosthesis according to any one of claims 1 to 3, characterized in that the rods (20) of the first series (2) have a length of between 85 millimeters and 115 millimeters and the rods (30) of the second series (3) have a length of between 125 millimeters and 160 millimeters. 5. Family of elements (1) of hip prosthesis according to 1 to 4, characterized in that the upper part (24) diaphyseal of each rod (20) of the first series (2) has a length corresponding to about two thirds. the length of the rod. 6. Family of elements (1) of hip prosthesis according to 1 to 5, characterized in that the rods (20) of the first series (2) are covered, at least on the upper part (24) diaphyseal of a coating porous offering a rough surface condition. 7. Surgical kit for implantation of a hip prosthesis, characterized in that it comprises a family of elements (1) of hip prosthesis according to any one of claims 1 to 6. 8. Surgical kit according to claim 7, characterized in that it comprises a plurality of rasps, some allowing the realization of recesses adapted to the dimensions of the rods (20) of the first series (2), the others allowing the realization recesses adapted to the dimensions of the rods (30) of the second series (3). 9. Surgical kit according to claim 7 or claim 8 characterized in that it comprises a plurality of test collars. 10. Surgical kit according to any one of claims 7 to 9, characterized in that it comprises an ancillary for the implantation of each of the femoral stems (20, 30) of the first and second series (2, 3) in the femoral stem prepared for this purpose in the femur.5