WO1998010720A1 - Femoral hip prosthesis with antepulsion-adapted seat - Google Patents

Abstract

A femoral prosthetic piece for the hip comprises a femoral rod (1) extending along a longitudinal axis (2) of the rod, a head adapting piece (4) provided with a Morse cone (9), and a spherical head (10) adapted by being clamped on the Morse cone (9). The Morse cone (9) axis (11) is in a plane substantially parallel to the longitudinal axis (2) of the femoral rod (1) and offset with respect to the said rod axis according to an appropriate anteroposterior offsetting distance (D). The head adapting piece (4) can be positioned on the femoral rod (1) in two different positions. By turning round the adapting piece (4) and interchanging the heads (10), the laterality and the length of the member is adjusted without interfering with the anteroposterior offset.

Description

 TECHNICAL FIELD OF THE INVENTION The present invention relates to total hip prostheses, comprising a femoral part of hip prosthesis adaptable to the proximal part of a femur, and an acetabulum adaptable to the pelvis.

The femoral parts of hip prosthesis generally comprise a diaphyseal part in the shape of a femoral rod developing along a longitudinal longitudinal axis of rod and shaped to be engaged in the medullary canal of a femur, and a metaphyseal part flared laterally and connected by a cervical part or neck with a generally spherical head shaped to engage and pivot in a corresponding cavity of the acetabulum.

The anatomical configuration of the normal femur is such that there is an angle in horizontal projection, called anteversion angle, between the axis of the neck of the femur and the bicondylar axis at the lower end of the femur, typically around 15 °.

This arrangement results in the positioning of the massive trochantéπen behind the head of the femur. This is intended to promote the functioning of the muscular stays formed by the range of the glutes and in particular, the medium and the small gluteus, and the tensor of the fascia-lata located in front of the large gluteus

Known femoral pieces of hip prosthesis, for example described in document FR-A-2 700 947, reproduce this offset by providing an anversed neck at its base, that is to say connecting the upper area of the metaphyseal part to the head in an orientation contained in a radial cervical plane passing through the mean longitudinal axis of the femoral stem and pivoted around said mean longitudinal axis This solution is effective in the case of short neck prostheses for dysplastic hips described in this document. However, these anteversion tests of the neck of the prosthesis relative to the axis of the prosthesis are apparently at the origin of anterior dislocations when they are applied to prostheses for normal hips, i.e. long neck

PRESENTATION OF THE INVENTION A first problem proposed by the invention is thus to design a new general form of femoral part of a hip prosthesis making it possible to significantly reduce the risks of dislocation. anterior, by optimizing the functioning of the gluteal fan by correct anteroposterior positioning of the trochanter.

On the other hand, when replacing a natural joint with a hip prosthesis, it is necessary to respect the following constraints:

- according to the first constraint, the members must have the same length according to the second constraint, the foot of the member must be oriented in normal orientation for both members, too strong anteversion causes internal rotation of the foot, too weak anteversion causes external rotation of the foot, -

- according to the third constraint, the member must have an appropriate lateral positioning, that is to say an appropriate distance between the mean longitudinal axis of the member and the sagittal plane,

- According to the fourth constraint, the risk of dislocation, that is to say the risk of the femur head coming out of the corresponding socket of the acetabulum, during movements of angular orientation of the member should be avoided.

The respect of the above constraints aims in particular to ensure a correct muscular tension of the muscles ensuring the movements of the femur relative to the pelvis. Abnormal muscle tension leads to lameness or dislocations.

It is understood that the above constraints can be respected by adjusting the relative position of the femur head, with respect to the mean longitudinal axis of the femur, in three directions a direction X for adjusting the anteroposterior position of the head, a direction Y of lateralization, and a direction Z of height.

The height Z can be adjusted easily, with known prostheses with a generally cylindrical femoral stem, by differential insertion of the femoral stem into the femur, by adapting the calibration of the femoral barrel in the diaphyseal canal.

On the other hand, known techniques do not allow easy adjustment of the lateralization Y In fact, in known prostheses, an attempt is made to make this adjustment by moving the prosthesis head more or less along the axis of the neck, by more or less deep engagement on a Morse taper The problem is that this adjustment simultaneously and necessarily modifies the anteroposterior position X, inducing a rotation of the limb by the effect of the muscles which remind to balance This rotation cannot be compensated for by rotation of the femoral stem in the femur, in particular in the case of self-locking prostheses

Similarly, known prostheses do not allow the anteroposterior position X of the head to be freely modified without modifying all of the other parameters.

An attempt has also been made, in document FR-A-2 700 947, to design femoral parts of hip prosthesis having an additional degree of freedom of adjustment, comprising a body of femoral part with inclined upper plate, an adaptation part head comprising a base configured for its attachment to the upper plate of the femoral part body and carrying a Morse cone for adapting the head, oriented along an oblique axis of Morse cone, and a generally spherical head with conical hole adaptable by jamming on the walrus cone The head adapter piece constitutes the neck, and has a traditional anteversion, that is to say with the neck axis located in a plane containing the axis of the femoral stem and pivoted around of said femoral stem axis The head adapter piece can also be fixed on the upper plate of the femoral piece body in two distinct positions achieving two distinc values pivots of the neck relative to the longitudinal median plane of the stem, offering an additional possibility of adjusting the anteversion or the retroversion of the neck This solution does not, however, allow the lateralization Y and the anteroposterior position X II to be adjusted separately difficulties in adjusting the prosthesis during installation, and the risk of subsequent dislocation

The document WO 89 10730 A describes a femoral prosthesis whose neck is an extension of a helical metaphyseal part The helical shape of metaphyseal part induces both an angular shift and an anteroposterior shift of the neck relative to the axis of femoral stem When the prosthesis is placed, the helical shape of the metaphyseal part, which is engaged in the bone, induces a rotation that is difficult to control, so that an adjustment in height Z by depression of the prosthesis disturbs all the others adjustments in X and Y In addition, the possible subsequent ablation of the prosthesis is made difficult A second problem proposed by the present invention is thus to design a new structure of the femoral part of the hip prosthesis allowing the simple and independent modification of the position anteroposterior X, lateralization Y and height Z of the prosthesis head relative to the femoral stem. An object of the invention is to multiply the adjustment possibilities while using a minimum number of parts. To achieve these and other objects, a femoral prosthesis piece according to the invention comprises.

- a diaphyseal part in the shape of a femoral rod developing along a longitudinal longitudinal axis of rod and shaped to be engaged in the medullary canal of a femur, - a metaphyseal part flared laterally and oriented substantially in the frontal plane containing the longitudinal axis way,

a cervical part comprising a Morse cone for adapting a head oriented along an oblique axis of a Morse cone, a head, generally spherical, with a conical hole adapting by wedging on the Morse cone,

the axis of the Morse taper being in a cervical plane P substantially parallel to the mean longitudinal axis of the femoral stem and to the frontal plane F which contains said mean longitudinal axis, and offset with respect to said mean longitudinal axis of femoral stem according to a appropriate anteroposterior offset distance D

Thanks to this arrangement, the slide ent of the head along the axis of the Morse taper, by more or less deep depression of the head on the cone, does not induce a significant displacement of the head perpendicular to the frontal plane F, that is to say in the direction of the anteroposterior offset X The height adjustment of the prosthesis by sinking into the medullary canal of the femur in the direction Z does not induce disturbing axial rotation of the adjustments in X and in Y Also , the risks of anterior dislocation are considerably reduced. It will be noted that, according to the invention, the offset of the axis of the morse taper is effected in the part of prosthesis external to the bone, at the base or in the distal part of the neck, at the interface or in the vicinity of the interface between the metaphyseal part and the cervical part

According to a first embodiment, the diaphyseal part, the metaphyseal part and the cervical part are in one piece

According to a second advantageous embodiment, the femoral part is such that - the diaphyseal part and the metaphyseal part form a single piece femoral part, comprising an inclined upper plate shaped for fixing a separate cervical part,

- The cervical part is a separate head adaptation part, comprising a shaped base for its attachment to the upper plate of the femoral part body, and comprising the Morse taper head adaptation.

Preferably, the adapter part is fixed to the plate of the femoral part body by fixing means allowing said fixing in two positions turned over with respect to each other and in which the axis of the Morse taper is present, relative to the mean longitudinal axis of the femoral stem, two distinct inclinations parallel to the same cervical plane.

Also, it can advantageously be provided that the inversion of the adaptation piece on the plate of the femoral piece body produces an anteroposterior displacement of the head.

In this way, a first adaptation piece can be fixed in a first position on a femoral piece body for left prosthesis, in order to ensure for example a medialization of the left femur with antepulsion of the head, this same first piece of adaptation which can be fixed by turning it in the other position on a body of the femoral part for a right prosthesis, thus ensuring lateralization of the right femur with the same antepulsion of the head. The same first adaptation piece can be used to lateralize a left femur with retropulsion of the head, or medialize a right femur with retropulsion of the head. Conversely, a second adaptation piece, symmetrical with the first adaptation piece, could be used to medialize a right femur or lateralize a left femur with antepulsion of the head, or to lateralize a right femur or medialize a left femur with retropulsion of the head.

It can advantageously be provided that the body of the femoral part is generally symmetrical with respect to the frontal plane containing the mean longitudinal axis of the femoral stem.

According to an advantageous embodiment, the means for fixing the adaptation piece to the plate of the femoral piece body comprise: - on the femoral part body plate, a front bearing face oriented along a plane substantially perpendicular to the frontal plane containing the mean longitudinal axis of the femoral stem,

- on the adaptation piece, a corresponding front face of support, oriented along a plane substantially perpendicular to the cervical plane containing the axis of the Morse taper,

- Male-female engagement means, arranged on the respective front faces of the plates of the femoral piece body and of the adapter piece, to ensure the integral assembly of the adapter piece on the plate of the femoral piece body .

The male-female engagement means can be of different types. Advantageously, it is possible to provide male-female engagement means comprising:

- on the femoral part body plate, a male cone oriented along an average axis of engagement substantially perpendicular to the plane of the front face of the plate,

- On the adapter piece, a corresponding female cone adapted to forcefully engage the male cone, with an axis substantially perpendicular to the plane of the front face of the adapter piece and angularly offset from the axis of the walrus cone.

According to the invention, the adjustment of the length of the lower limb is done by the more or less significant depression of the femoral stem, by the varisante or valgisante form of the adaptation piece, and by the use of the walrus cone which receives heads engaging more or less deeply on the cone.

Adjustment of the orientation of the neck can be ensured by the choice of the adaptation piece, to put the neck in position of varus or valgus.

The adjustment of the lateralization can be carried out by the choice of the positioning of the adaptation piece, and by more or less pressing of the head on the Morse cone.

The adjustment in anteroposterior translation can be ensured by the choice and the positioning of the adaptation piece.

To achieve these different modes of adjustment, the present invention provides a set of modular elements making it possible to constitute a femoral piece of hip prosthesis. The set includes: - at least one model of a femoral part body with an inclined upper plate, generally symmetrical with respect to the frontal plane containing the mean longitudinal axis of the femoral stem,

- At least three models of adapter part, each model of adapter part being adaptable on the upper plate of the body of the femoral part by fixing means allowing it to be fixed in two distinct positions obtained by pivoting 180 ° around an average axis of engagement located in the frontal plane containing the average longitudinal axis of the femoral stem, and each model of adaptation piece comprising a Morse taper of head adaptation oriented along a axis of Morse taper having the same antero offset -posténeur suitable with respect to said average axis of engagement, the three models of adapter piece having axes of Morse taper offset angularly according to respective angular values A ^* , zero, and A ^" relative to the axis of engagement medium, - a plurality of heads, each with a generally spherical external surface with a base with conical hole adapting by wedging on the Morse taper, the head models e having bases with conical holes of different diameters and depths to engage at different depths on the Morse taper. Such a set of modular elements allows, by interchangeability of the elements, to adjust the medialization or lateralization of the femur, without interfering with the anteroposterior shift between the femur and the head, by choosing the appropriate adaptation piece and its orientation around of the middle axis of engagement, and choosing the appropriate head retaining the limb length.

SUMMARY DESCRIPTION OF THE DRAWINGS Other objects, characteristics and advantages of the present invention will emerge from the following description of particular embodiments, made in relation to the attached figures, among which:

- Figure 1 is an exploded front view of a femoral part of right hip prosthesis according to an embodiment of the present invention;

- Figure 2 is another front view of the prosthesis of Figure 1, after assembly, illustrating the orientation adjustment of the neck by inverting the adapter piece;

- Figure 3 is a view of the inner face of the prosthesis for right femur of Figures 1 and 2; - Figure 4 illustrates the possible adjustment, obtained by reversing the adapter piece, seen from the right side of Figure 2, -

- Figure 5 is a top view of the femoral part illustrated in Figure 2; - Figure 6 is a front view of the same femoral part of hip prosthesis according to the invention, adapted either to lateralize a right femur or to medialize a left femur;

- Figure 7 illustrates the possible adjustments by adaptation of three types of heads engaging more or less deeply on the Morse taper of adaptation piece;

FIG. 8 illustrates, in front view, the adjustment possibilities resulting from the choices of prosthesis head and orientation of the neck by inversion of the adaptation piece, - and

- Figures 9 and 10 respectively illustrate, in top view, the lateral rotation freedoms of a known prosthesis with an anversed neck and a prosthesis according to the invention with an antipulsed neck.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the embodiment illustrated in FIG. 1, the femoral part of hip prosthesis comprises a body of femoral part 104 in one piece consisting of a dιaphysa ^* > re part in the form of femoral stem 1, developing along a mean longitudinal axis 2 of stem, shaped to be engaged in the medullary canal of a femur, and of a metaphyseal part 101 flared laterally and oriented substantially in the frontal plane containing the mean longitudinal axis 2 as illustrated in the figure. The body of the femoral part 104 comprises, at the upper part of its metaphyseal part 101, an upper plate 3 inclined inward and shaped for fixing a head adaptation part 4 forming the cervical part of the prosthesis

The body of the femoral part 104 is thus generally symmetrical with respect to the frontal plane containing the mean longitudinal axis 2 of the rod, or plane of FIG. 1.

On the upper plate 3 of the femoral part body 104, a front support face 5 is provided, oriented along a plane substantially perpendicular to the front plane containing the mean longitudinal axis 2 of the rod. A male cone 6, with an elliptical cross section for example, protrudes from the front bearing face 5 of the femoral stem 1 and is oriented along an average axis of engagement 7 substantially perpendicular to the plane of the front face 5 of platinum 3. The middle engagement axis 7 is located in the frontal plane containing the mean longitudinal axis 2 of rod.

The head adaptation part 4 comprises a base 8 shaped for its attachment to the upper plate 3 of the femoral part body 104, and comprises a Morse cone 9 for adapting a head 10. The Morse cone 9 is oriented according to an oblique axis 11 of Morse taper. The head 10 has a generally spherical external surface 112 and a base 12 with a conical hole 13 adapting by wedging on the Morse cone 9.

As can be seen in particular in FIGS. 3 and 5, the axis 11 of the walrus cone is in a cervical plane P substantially parallel to the mean longitudinal axis 2 of the femoral stem 1 and to the frontal plane F which contains it, and offset relative to said mean longitudinal axis 2 of femoral stem 1 at an appropriate anteroposterior offset distance D. It is thus understood that the possible sliding of the head 10 on the Morse cone 9, parallel to the axis 11, does not modify the distance D between the head 10 and the front plane F containing the mean longitudinal axis 2 of the rod, and therefore does not modify the anteroposterior position X of the head 10.

Referring again to FIG. 1, the base 8 of the head adaptation part 4 comprises a front support face 14, shaped to come to bear on the front support face 5 of the body of the femoral part 104, and oriented along a plane substantially perpendicular to the cervical plane P containing the axis 11 of the Morse taper The base 8 further comprises a female cone 15, of axis 16 substantially perpendicular to the plane of the front face 14 of the workpiece adaptation 4, and of cross section corresponding to that for example elliptical of the male cone 6. The adaptation part 4 can thus engage on the upper plate 3 of body of femoral part 104 according to two distinct positions obtained by pivoting by 180 ° around the middle axis of engagement 7 or axis of the male cone 6. Tou bear in this embodiment of Figure 1, we see that the axis 16 of the female cone 15 of adapter piece 4, which comes s '' align on the middle axis of engagement 7, is angularly d wedged at an angle A with respect to the axis 11 of the Morse taper 9. In this way, by rotation of the adaptation piece 4 around the mean engagement axis 7 in one or the other of the distinct adaptation positions, the axis 11 of the Morse taper 9 is found in two distinct orientations A ^* or A around the middle axis of engagement 7, making it possible to adjust the orientation of the neck of the femur in the frontal plane, to selectively increase medialization or lateralization.

As can be seen in FIGS. 2, 4 and 5, when the adaptation piece 4 is in its first position of engagement on the body of the femoral piece 104, the head 10 is propelled and is in a lateral position relatively spaced from the mean longitudinal axis 2 of the femoral stem l, ensuring the lateralization of the femur By turning the adaptation piece 4, the head takes the position illustrated by the reference 10a, and is then laterally brought closer to the mean longitudinal axis 2 of the femoral stem l, to ensure the medialization of a femur However, by this reversal, as can be seen in particular in FIGS. 4 and 5, the head 10 is then back-propelled, moved backwards along the antero axis -posténeur, and is not suitable any more for the treatment of the same member This configuration with retropulsed head can be used on a hip having after-effects of congenital dislocation But especially, by the fact that the body of part femoral 104 is generally symmetrical with respect to the frontal plane containing the mean longitudinal axis 2 of femoral stem 1, it is then possible to use the assembly for adaptation on the opposite limb, the head 10 then having the same antepulsion in the appropriate direction, and the same movement, side closer than in position 10a

This possibility is illustrated in FIG. 6, in which, on a pelvis 100 provided with acetabulum 110 and 111, the same body of the femoral part 104 is fitted with the same adaptation part 4 in a first position for lateralizing the right femur R , or we adapt the same adaptation piece 4 in its second position to medialize the left femur L The relative displacements of the femur relative to the center of the head 10 are illustrated in both positions by the respective arrows 17 and 18 There is no displacement of the femur in the anteroposterior direction

In FIG. 7, the possible adaptation has been illustrated, on the same adaptation piece 4, of different heads engaging more or less deeply on the Morse cone 9 the head 10 is a head with medium engagement The head 10b is a head with reduced engagement, making a longer neck The head 10c is a head with deeper engagement making a shorter neck FIG. 8 illustrates, in front view, the possibilities of adjusting the position of the center of the prosthesis head 10, relative to the femur, by the adaptation of the different heads illustrated in FIG. 7, and by the change of orientation of the adaptation piece 4 between its two fixing positions. We can thus move the center of the head 10 in a zone 19.

FIG. 9 illustrates in top view the possibilities of lateral rotation of a femoral prosthesis with an anversed neck 4 with respect to an acetabulum 110. The acetabulum 110 is naturally off-axis along axis II with respect to the anteroposterior axis I , and the neck 4 is angularly offset along the axis III at rest. In maximum lateral rotation, the neck 4 comes along axis IV. The anteversion of the neck 4 reduces the amplitude of lateral rotation, and increases the risk of dislocation by the fact that the neck 4 comes to bear against the edge 210 of the cup 110. FIG. 10 illustrates in top view the improved possibilities of lateral rotation of the prosthesis according to the invention, the antepulsion of the neck 4 retaining the amplitude of lateral rotation and reducing the risks of dislocation by the fact that, for the same limit rotation IV, a space 310 is preserved between the neck 4 and the edge 210 of the cup 110. Referring again to FIG. 1, a threaded hole 20 <_st provided in the upper plate 3 of the femoral stem 1, intended to cooperate with devices for gripping and extracting the rod Similarly, a hole 21 is provided in the morse cone 9, to cooperate with a gripping and extraction device. To obtain particularly wide adjustment possibilities by means of a reduced number of parts to be used, there is little t advantageously provide a set of modular elements comprising the following elements: - at least one femoral part body model 104 with upper plate 3 inclined, generally symmetrical with respect to the frontal plane F containing the mean longitudinal axis 2 of the femoral stem 1, - at least three models of adaptation piece 4, two of which are symmetrical to each other each model of adaptation piece is adaptable to the upper plate 3 of the body of the femoral piece 104 by fixing means authorizing its fixing in two distinct positions obtained by pivoting 180 ° around the average axis of engagement 7 located in the frontal plane F containing the average longitudinal axis 2 femoral stem 1; each model of adaptation piece comprises a morse cone 9 for adapting a head 10, the respective axes 11 of morse cone 9 having the same anteroposterior shift D appropriate with respect to the average axis of engagement 7; the three models of adaptation part 4 each have axes 11 of morse taper 9 angularly offset according to respective angular values A ^* , zero and A with respect to 1 axis of average engagement 7;

- And a plurality of head models, each having an external surface 112 of head 10, generally spherical, with a base 12 with conical hole 13 adapting by wedging on the Morse cone 9, the head models 10 having bases 12 with conical holes 13 of different diameters and depths to engage at different depths on the Morse taper 9.

The present invention is not limited to the embodiments which have been explicitly described, but it includes the various variants and generalizations which are within the reach of those skilled in the art.

Claims

1 - Femoral part of hip prosthesis, comprising: - a diaphyseal part in the form of a femoral stem (1) developing along a mean longitudinal axis (2) of the stem and shaped to be engaged in the medullary canal of a femur, a metaphyseal part (101) flared laterally and oriented substantially in the frontal plane (F) containing the average longitudinal axis (2), - a cervical part (4) comprising a Morse cone (9) for head adaptation oriented along an oblique axis (11) of the Morse cone (9), - a head (10), generally spherical, with a conical hole (13) which fits by wedging onto the Morse cone (9), characterized in that: - the axis (11) of the Morse cone (9) is in a cervical plane (P) substantially parallel to the average longitudinal axis (2) of the femoral stem (1) and to the frontal plane (F) which contains said longitudinal axis means (2), and offset relative to said mean longitudinal axis (2) of femoral stem (1) according to an appropriate antero-posterior offset distance (D). 2 - Femoral part according to claim 1, characterized in that the diaphyseal part (1), the metaphyseal part dOl) and the cervical part (4) are in one piece. 3 - Femoral part according to claim 1, characterized in that: - the diaphyseal part (1) and the metaphyseal part (101) form a one-piece femoral part body (104), comprising an upper plate (3) inclined shaped for the fixation of a distinct cervical part (4), - the cervical part is a separate head adaptation part (4), comprising a base (8) shaped for its attachment to the upper plate (3) of the femoral part body (104), and comprising the Morse cone (9) ) head adaptation 4 - Femoral part according to claim 3, characterized in that the adaptation part (4) is fixed on the plate (3) of the body of the femoral part (104) by fixing means (5, 6, 8, 14 ) authorizing said fixing in two positions reversed relative to each other and in which the axis (il) of the Morse cone (9) presents, for example relative to the average longitudinal axis (2) of the femoral stem (1), two distinct inclinations parallel to the same cervical plane (P). 5 - Femoral part according to claim 4, characterized in that the body of the femoral part (104) is generally symmetrical with respect to the frontal plane (F) containing the average longitudinal axis (2) of the femoral stem (1). 6 - Femoral part according to one of claims 4 or 5, characterized in that the means for fixing the adaptation part (4) on the plate (3) of the body of the femoral part (104) comprise: - on the plate (3) of the body of the femoral part (104), a frontal support face (5) oriented along a plane substantially perpendicular to the frontal plane (F) containing the average longitudinal axis (2) of the femoral stem (1), on the adaptation piece (4), a corresponding front support face (14), oriented along a plane substantially perpendicular to the cervical plane (P) containing the axis (11) of the Morse cone (9), - male-female engagement means (6, 15), arranged on the respective front faces (5, 14) of the body plates of the femoral part (104) and of the adaptation part (4), to ensure the integral assembly of the adaptation part (4) on the plate (3) of the body of the femoral part (104). 7 - Femoral part according to claim 6, characterized in that the male-female engagement means comprise: - on the plate (3) of the femoral part body (104), a male cone (6), oriented along a mean engagement axis (7) substantially perpendicular to the plane of the front face (5) of plate (3) , - on the adaptation part (4), a corresponding female cone (15) adapted to engage forcefully on the male cone (6), with an axis (16) substantially perpendicular to the plane of the front face (14) of adaptation piece (4) and angularly offset relative to the axis (il) of the Morse cone (9). 8 - Set of modular elements for constituting a femoral part of a hip prosthesis according to any one of claims 3 to 7, characterized in that it comprises: - at least one body model of a femoral part (104) with an inclined upper plate (3), generally symmetrical with respect to the frontal plane (F) containing the average longitudinal axis (2) of the femoral stem (1), - at least three models of adaptation part (4), each model of adaptation part being adaptable on the upper plate (3) of the body femoral part (104) by fixing means allowing its fixing in two distinct positions obtained by pivoting 180° around a mean engagement axis (7) located in the frontal plane (F) containing the mean longitudinal axis ( 2) of femoral stem (1), and each model of adaptation part comprising a morse cone (9) for head adaptation (10) oriented along an axis (11) of morse cone (9), the respective axes ( 11) of Morse cone (9) having the same antero-posterior offset (D) appropriate relative to said average engagement axis (7), the three models of adaptation part (4) having cone axes (11) morse (9) angularly offset according to respective angular values A ^* , zero and A ^" relative to the average engagement axis (7), a plurality of heads (10), each with an external surface (112) generally spherical with a base (12) with a conical hole (13) which fits by wedging onto the Morse cone (9), the head models (10) having bases (12) with conical holes (13) of different diameters and depths for s engage different depths on the Morse cone (9). 9 - Set of modular elements according to claim 8, characterized in that it allows, by interchangeability of the elements, to adjust the medialization or lateralization of the femur, without interfering with the antero-posterior offset between the femur and the head (10 ), by choosing the appropriate adaptation piece (4) and its orientation around the average engagement axis (7), and by choosing the appropriate head (10) maintaining the limb length.