FR2941613A1 - SURGICAL DEVICE FOR IMPLANTATION OF A RESURFACING PROSTHESIS. - Google Patents

Abstract

In order to implant a resurfacing prosthesis for a joint between a long bone (F) and another bone (B), this device (1) comprises: first measuring means adapted to measure, with respect to an axis of reference (XX) fixedly associated with the long bone (F), and intraoperatively memorizing the position of anatomical points (F) of the anatomical neck (F) of this long bone, - second measuring means adapted to measure , relative to the other bone, and memorize peroperatively several positions of the reference axis, in particular corresponding to extreme articular configurations of the joint, specific to the operated patient, and - adapted means of comparison to compare, in a perioperative manner, the relative position between, on the one hand, at least one of the anatomical points of the anatomic neck of the long bone virtually provided with the prosthetic head of the resurfacing prosthesis and, on the other hand , the edge of a cavity that is fixedly attached to the other bone and wherein the prosthetic head is provided to articulate substantially substantially, and at least in each of said plurality of positions of the reference axis. By using this device, the surgeon can easily and quickly determine, during the surgical procedure itself, a preferred configuration for implanting the prosthetic head, in order to reduce the risk of subsequent dislocation of the implanted prosthesis.

Description

SURGICAL DEVICE FOR IMPLANTATION OF A RESURFACING PROSTHESIS

The present invention relates to a surgical device for implanting a resurfacing prosthesis, as well as a surgical method for implanting such a prosthesis. The resurfacing prostheses of the invention comprise a prosthetic head to be attached to the end of a long bone of a patient, to articulate in a substantially complementary manner in a cavity fixedly attached to another bone which is associated with the long bone forming between these two bones an altered joint, that the resurfacing prosthesis is intended to treat to restore the patient operated a satisfactory joint mobility. The aforementioned cavity of the other bone can also be defined by a prosthetic cup belonging to the resurfacing prosthesis, this prosthetic cup being then to be fixed on this other bone, that correspond to a pre-existing anatomical bone cavity of the patient, in particularly when the patient has such a cavity with a surface state little or no alteration. The invention can thus be applied, inter alia, to a shoulder joint and a hip joint. In the latter case, taken as an example, a hip resurfacing prosthesis conventionally comprises a prosthetic resurfacing head of the anatomical head of the femur. If the anatomical acetabular cotyloid cavity of the operated patient allows it, it receives directly this prosthetic head to articulate and we can then speak of a resurfacing hemi-prosthesis. Otherwise, the prosthesis also comprises a prosthetic cup to be implanted in the acetabular zone of the pelvis, the head and prosthetic cup forming a joint hard / hard couple, each being typically made of a metal alloy: the prosthetic cup thus generally has a shape half-sphere, inside which is articulated the prosthetic head. When laying such a hip resurfacing prosthesis, the surgeon implants, on the one hand, the prosthetic head at the upper end of the femur, previously prepared, for example milled to receive a bone anchor keel extending rigidly from the face of the prosthetic head, opposite to the prosthetic cup, and, secondly, the prosthetic cup in a generally hemispherical cavity dug in the pelvic bone. It is generally accepted that an optimal positioning of the prosthetic head corresponds to the alignment of the keel of this head on the central axis of the femoral neck or in slight valgus: this positioning of the prosthetic head is deemed to meet the anatomical criteria. , while ensuring a good mechanical strength of the prosthetic component and limiting the weakening of the femur to reduce the risk of subsequent fracture of the femoral neck. In practice, this positioning is determined either at a pre-operative stage, on the basis of analysis of hip radiographs, or at an intraoperative stage, by means of computer assistance, as proposed in EP-A-1. 859 755. This being said, it is found that, especially when a hip resurfacing prosthesis is put in place in a young patient who tends to regain as normal a physical activity as possible after implantation, it happens that the prosthesis is requested in extreme joint configurations causing a bearing contact between the neck of the patient's femur and the edge of the acetabulum, whether the latter is in its anatomical shape or defined by a prosthetic cup: the dislocation of the prosthesis is then present . The purpose of the present invention is to provide a surgical device that assists the surgeon in a simple and quick way during the surgery of implantation of a resurfacing prosthesis, in order to limit the risk of subsequent dislocation of the prosthesis best adapting to the anatomy of each treated patient. To this end, the subject of the invention is a surgical device for implanting a resurfacing prosthesis for a joint of a patient between a long bone and another bone of a patient, such as a hip joint between a femur and a pelvis, this resurfacing prosthesis comprising a prosthetic head adapted to be fixed to one end of the long bone and to articulate in a substantially complementary manner in a cavity fixedly bonded to the other bone, this device being characterized in that it comprises: first measuring means adapted to measure, with respect to a reference axis that is fixedly associated with the long bone, and to memorize, in a per-operative manner, the position of anatomical points of the anatomical neck of this bone; long, second measurement means adapted to measure, with respect to the other bone, and to memorize peroperatively several positions of the reference axis, corresponding in particular to configurations articular extremes of the joint, specific to the patient, and - comparison means adapted to compare, peroperatively, the relative positioning between, on the one hand, at least one of the anatomical points of the anatomical neck of the long bone virtually provided with the prosthetic head and, secondly, the edge of the cavity of the other bone in which the prosthetic head is intended to articulate, and this at least in each of said several positions of the axis reference. Applied to the hip of an operated patient, the idea underlying the invention is to allow the surgeon, during the actual surgery, to compare the position of the anatomical neck of the virtually prosthetic femur and the border of the acetabular cavity of the pelvis, whether this cavity is in its actual anatomical shape or virtually defined by a prosthetic cup, and in different measured and stored positions of the femur relative to the pelvis, these positions corresponding in practice to extreme hip joint configurations of the operated patient, namely articular configurations combining flexion / extension, abduction / adduction and / or internal / external rotation movements, such as for example the tailor-made configuration which combines flexion, abduction and external rotation. In the same way, the invention applies, inter alia, to the shoulder of an operated patient, allowing, while the shoulder is considered in extreme joint configurations, to compare intraoperatively the position of the patient. anatomical neck of the humerus virtually prosthetic by a prosthetic resurfacing head and the position of the border of the glenoid cavity, anatomical or prosthetic, of the scapula. The surgeon then chooses, during the surgical procedure of fitting the prosthesis itself, a preferential configuration for implanting the prosthetic head, allowing the subsequent solicitation of the prosthesis into these extreme joint configurations without risking dislocation. In other words, the surgical device according to the invention allows the surgeon to determine this preferred implantation configuration, or several of these preferred configurations, which the surgeon will then respect at the end of the surgical procedure to implant the prosthetic head.

Note that the reference axis associated with the long bone is independent of the embodiment of the interface between the prosthetic head and the end of the long bone. In other words, this reference axis can be arbitrarily chosen as an axis totally disconnected from the long bone or an axis having any anatomical correspondence. Thus, in the case of an example of the hip, the reference axis associated with the femur is independent of the presence of a bone anchor pin, which the prosthetic femoral head may have on its side facing the femur. Of course, the surgeon ensures that the implantation configuration finally retained for the prosthetic head does not induce significant risk for the mechanical strength of this head vis-à-vis the long bone, especially without weakening the cervix anatomical of this long bone. This criterion is all the more easily respected when the operated patient is young and does not suffer from a degenerative pathology of his bones. Moreover, according to an advantageous aspect of the device according to the invention, the latter incorporates the possibility of adjusting the implantation configuration of a prosthetic cup belonging to the resurfacing prosthesis, especially in order to meet the aforementioned criterion. According to advantageous features of the implantation device according to the invention, taken separately or in any technically possible combination: the device comprises means of communication to a surgeon of the result of the comparison means; the communication means comprise a display means adapted to represent, in a relative and simultaneous manner, both the long, virtually prosthetic bone, the cavity of the other bone and the reference axis; the device comprises means for adjusting the virtual implantation of the prosthetic head on the long bone; - In the case where the cavity of the other bone is defined by a prosthetic cup belonging to the resurfacing prosthesis, the device further comprises means for adjusting the virtual implantation of this prosthetic cup on the other bone; the comparison means comprise appropriate calculation means, at least in each of said plurality of positions of the reference axis, for calculating the distance between at least one of the anatomical points of the anatomical neck of the long bone that is virtually prosthetic, and the cavity of the other bone; the device further comprises extrapolation means of a trajectory curve passing substantially through each of the said plurality of positions of the reference axis, and the comparison means are adapted to compare the relative positioning between at least one of the anatomical points; the anatomical neck of the virtually prosthetic long bone and the cavity of the other bone as the reference axis traverses this trajectory curve; - The device further comprises selection means adapted both for selecting, by a surgeon and on the basis of the result of the comparison means, and for storing a preferred implant configuration of the prosthetic head on the long bone; the device further comprises determination means adapted both for calculating, on the basis of the result of the comparison means, and for memorizing a preferential implantation configuration of the prosthetic head on the long bone; the device further comprises a forest guide or similar ancillary device for guiding the application of a tool for preparing the end of the long bone in order to place the prosthetic head on the long bone, this guide -forêt or this similar ancillary being equipped with means for locating in space, and the device further comprises navigation means adapted to position this forest guide or this ancillary similar to the long bone for implantation the prosthetic head in the preferred implantation configuration provided either by the selection means or by the determination means. The invention also relates to a surgical method for implanting a resurfacing prosthesis for a joint between a long bone and another bone of a patient, this resurfacing prosthesis comprising a prosthetic head, a method in which, per -operatively, successively: - one locates in space the long bone and the other bone of a patient to be treated, - one measures and memorizes, with respect to a reference axis associated fixedly the long bone, the position of anatomical points of the anatomical neck, this long bone, - is measured, relative to the other bone, and is stored several positions of the reference axis, in particular corresponding to extreme articular configurations of the joint, own to the patient, - the relative positioning is compared between, on the one hand, at least one of the anatomical points of the anatomical neck of the long bone virtually provided with the prosthetic head and, on the other hand, the edge of a cavity which is bound to the self and in which the prosthetic head is provided to articulate in a substantially complementary manner, and this at least in each of said plurality of positions of the reference axis, in order to determine at least one preferred configuration of implantation of the head prosthetic on the long bone, and - the prosthetic head is actually implanted on the long bone of the patient in the preferred implantation configuration. According to an advantageous characteristic of this method, on the basis of the result of the comparison of the relative positioning between at least one of the anatomical points of the anatomical neck of the virtually prosthetic long bone and the edge of the cavity of the other bone, in each said plurality of positions of the reference axis is determined, in addition to the preferred implantation configuration of the prosthetic head, a preferential implantation configuration on the other bone of a prosthetic cup defining the cavity. It is then possible to actually implant the prosthetic cup on the other bone in the aforementioned preferential implantation configuration. This method is advantageously applied to a hip joint or shoulder joint. The invention will be better understood on reading the description which follows, given solely by way of example and with reference to the drawings in which: FIG. 1 is a schematic view of a part of a surgical device according to the invention, applied to the hip of a patient to operate; FIG. 2 is an exploded perspective view of a hip resurfacing prosthesis to be implanted by means of the device of FIG. 1; FIG. 3 is a schematic view illustrating a representation provided by the device of FIG. 1 during a surgical procedure for implanting the prosthesis of FIG. 2; and FIG. 4 is a view similar to FIG. 3, illustrating a situation of potential subsequent dislocation of the prosthesis during implantation. The surgical device 1 of Figure 1 comprises a computer 2 associated with a unit for transmitting and receiving infrared radiation. This unit comprises a sensor 3 connected to the computer and an infrared emission source 4 covering the operative field in which is partially represented a hip of a patient to be treated. The hip comprises the upper part of a femur F and a corresponding part of the pelvic bone B. To allow the computer 2 to locate in the space the bones of the femur F and the pelvis B, the device 1 comprises respective groups of markers 5 and 6 which passively pass the infrared radiation back to the sensor 3. Each group of markers 5 or 6 forms a three-dimensional marking system enabling the 2-sensor computer assembly 3 to follow in space the respective displacements of the femur and pelvis. The use of such markers is well known in the field of computer-assisted orthopedics, for example from EP-A-1,249,213, and will not be described further here. The computer 2 is also associated with one or more screens 7 able to display information useful to the surgeon, in particular the information relating to the position of the bones F and B, as well as other data described below, preferably under graphical representations, as detailed below. The device 1 also comprises control means 8, for example in the form of a pedal capable of being actuated by the foot of the surgeon.

The device 1 further comprises other components which will be detailed below in the description of an example of use of the device for the implantation of a hip resurfacing prosthesis 10 shown alone in FIG. 2. This prosthesis 10 consists of a femoral prosthetic head 11 to be implanted at the upper end of the femur F and an acetabulum acetabulum 12 to be implanted in the pelvic bone B. The prosthetic head 11 comprises a main body 13 globally spherical, both hollow and truncated, defining an axis of revolution AA. In the example considered here, the body 13 internally comprises a keel 14, which extends rigidly from the inner bottom of the body along the axis A-A. This keel 14 is intended to be housed and retained in a complementary cavity dug in the upper epiphysis F1 of the femur F.

The cup 12 comprises, meanwhile, a substantially hemispherical main body 15 intended to be secured in a complementary cavity dug in the bone of the pelvis B. The concave inner surface of this body, whose axis of revolution is noted BB , thus defines a cavity 16 shaped substantially complementary to the outer surface of the body 13 of the head 11, so that the latter is articulated in the manner of a ball with respect to the cup 12 when the body 13 is received in the cavity 16. The prosthesis 10 described above is given by way of example only and other hip resurfacing prostheses, of different geometries and / or natures, can be implanted by means of the device 1 according to the surgical method of implantation described below. In particular, the invention applies to the installation of resurfacing prosthesis, the prosthetic head has bone anchoring means complementary to the keel 14 or whose prosthetic head is devoid of such a keel. Similarly, the prosthetic cup 12 may have specific bone anchoring means.

Firstly, the surgeon incises the patient and collects a certain amount of data relating to the anatomical geometry of the bones of femur F and pelvis B. For this purpose, various means of acquiring this data are possible. For example, the surgeon uses a probe 9 identified by the computer 2-sensor 3 and previously calibrated: this probe is brought to the remarkable places of the two bones and, at each of these implementations, the surgeon operates the control pedal 8 so that the computer records the position of the probe and thereby deduce the anatomical characteristics of the femur F and pelvis B. From these data and the tracking of the markers 5 and 6, the computer is then able to locate in space the bones of the femur of the pelvis. In particular, the computer 2 defines a reference axis XX fixedly associated with the femur F, as indicated in FIG. 1. In practice, this reference axis XX may correspond globally to the longitudinal central axis of the anatomical neck F2 of the femur, which connects the F1 epiphysis and the upper end of the F3 diaphysis. As a variant, this reference axis may correspond substantially to the mechanical axis of the femur F, that is to say to the axis connecting the anatomical articular centers of the F1 epiphysis and the lower femoral epiphysis. Preferably, this femoral reference axis XX is determined while the hip joint is in a neutral position, that is to say while the patient's leg extends in length in a direction parallel to the direction longitudinal trunk. In this way, this reference axis can be used by the computer 2 to define a reference axis fixedly associated with the pool B, referenced Y-Y in Figure 1, the X-X and Y-Y axes being merged in this figure.

Advantageously, at the end of the first operating time, the computer 2 displays on the screen 7 graphical representations corresponding to the F and B bones, as well as the X-X and Y-Y axes, in particular for purposes of visual control by the surgeon. This display is for example made in a sagittal plane to the patient, as illustrated in FIG.

In a second operative step, the surgeon acquires mapping data specifically relating to the anatomical neck F2 of the femur F. For this purpose, various means of acquiring these data are possible. In particular, the surgeon can again use the probe 9 identified by the 2-sensor computer assembly 3, bringing it at a large number of different points of the surface of the neck F2. The various anatomical points thus mapped are indicated schematically by the references F4 in FIGS. 1 and 3. Advantageously, at the end of the second operating time, the computer 2 displays on the screen 7 the map thus produced.

As variants of the different possibilities for acquiring both the mapping data relating to the femur F and the pelvis B, during the implementation of the first operating procedure described above, the mapping data specifically relating to the anatomical geometry of the Femoral neck F2, during the implementation of the second operating time, one can consider extracting such data from pre-operative images of the patient, for example scanner images. Such data can moreover be combined with data obtained by palpation as above, possibly associating them with predetermined data provided by databases available in the field of hip surgery. In a third operating time, several hip joint configurations of the patient are measured and memorized. To do this, the surgeon solicits the hip so that it occupies successively several configurations considered extreme, that is to say, configurations that the local morphology of the patient imposes on him as natural limits. The patient's hip is thus solicited in several configurations combining flexion / extension, abduction / adduction and / or internal / external rotation movements, for example in the tailor configuration. Each of these extreme configurations characterizes a range of motion specific to the hip of the operated patient, that the prosthesis 10 to be implanted is supposed, thereafter, to reproduce without the risk of being dislocated. When the surgeon solicits the hip joint to one of these extreme configurations, he actuates the control pedal 8 and the computer set 2-sensor 3 physically measures and stores the position of the femoral reference axis XX relative to at the bone of the pelvis B. In a fourth operative time, the surgeon indicates to the computer 2 the model and the size of the prosthesis 10 he plans to implant. The choice of this prosthesis is either left to the sole discretion of the surgeon, or suggested by the computer taking into account the morphological characteristics, in particular bone, of the operated patient. For the rest of the description, it is assumed that the surgeon selects the prosthesis 10 of Figure 2 as the one he wishes to implant.

The computer 2 then provides the surgeon, via the screen 7, a virtual representation of the implantation configuration of the head 11 and the implantation configuration of the cup 12. More precisely, the computer represents on its screen 7 the femur F virtually provided with the prosthetic head 11 and the basin B virtually provided with the prosthetic cup 12. An example of this virtual representation is provided in Figure 3. To understand the interest of the device 1, assume that the virtual implantations of the head 11 and of the cup 12, as shown in FIG. 3, are initially independent of the mapping data corresponding to the anatomical points F4 of the F2 neck of the femur F: for example, these virtual implantations correspond to the fact that on the one hand, the prosthetic axis AA is aligned with the femoral reference axis XX while the prosthetic axis BB is aligned with the reference axis of the pelvis YY. While the prosthesis 10 is virtually implanted according to this configuration, the computer 2 is made to simulate the movement of the hip in each of the extreme configurations measured and stored during the third operating time. For example, in Figure 4, the hip joint is shown in such an extreme configuration. In each of these extreme configurations, the computer compares the relative positioning between, on the one hand, the anatomical points F4 of the neck F2 of the femur F virtually provided with the head 11 and, on the other hand, the basin B provided with virtually the cup 12: the computer 2 is then able to determine whether a contact occurs or not between one of these anatomical points F4 and the edge of the virtual prosthetic cavity 16 of the pelvis, in particular the free end edge of the prosthetic cup 12. Such a contact is illustrated in FIG. 4, being referenced C. In practice, to do this, the computer 2 includes calculation means making it possible to calculate, in each of the positions of the axis XX corresponding to the extreme configurations memorized during the third operating time, the distance between the anatomical points F4 of the virtually prosthetic femur and the edge of the cavity 16 of the virtually prosthetic pelvis. Advantageously, it is understood that only some of the anatomical points F4 can be the subject of this computation treatment provided that the computer 2 is able to determine, among all the anatomical points F4, the one or those most concerned by a risk contact with the virtually prosthetic pelvis according to the extreme joint configuration considered. As an advantageous optional arrangement, rather than testing the risks of contact only in each of the extreme joint positions, the computer 2 advantageously incorporates calculation means for extrapolating a trajectory curve passing substantially through each of the positions of the axis XX corresponding to the different extreme joint configurations, so that the comparison of the relative positioning between the neck F2 of the femur F virtually prosthesis and the edge of the cavity 16 of the virtually prosthetic pelvis is performed while the axis XX follows the aforementioned trajectory curve. If a contact between the neck F2 of the virtually prosthetic femur F and the margin of the cavity 16 of the virtually prosthetic pelvis B is thus determined by the computer 2, this implies that the implantation configuration of the head 11 and / or the configuration implantation of the cup 12 is not satisfactory, in the sense that the prosthesis 10 may be dislocated in at least one of the extreme joint configurations associated with the third operating time. In this case, the computer 2 can warn the surgeon and, using specific means integrated in the computer 2, controlled for example by touching on the screen 7, the surgeon can adjust the virtual implantation of the head 11 and / or the virtual implantation of the cup 12, until the surgeon finds preferential implantation configurations for the head and the cup, which he then recorded on the computer 2 and in which the risk of subsequent dislocation of the prosthesis 10 are reduced or even advantageously zero. By way of example, in FIG. 3, the double-arrow 20 indicates a possibility of adjusting the implantation of the head 11 in an anteroposterior direction. In practice, it is understood that other adjustment directions can be envisaged, in particular by means of representations, on the screen 7, of the hip virtually prosthetic in other planes than that considered in FIGS. 3 and 4. In practice, understands that, through advantageous optional arrangements, the intervention of the surgeon 2 during this fourth operation can be further restricted. To do this, rather than letting the surgeon control the means for adjusting the virtual implantation of the head 11 and / or the virtual implantation of the cup 12, the computer 2 can integrate automated calculation means, allowing to determine one or more preferred implantation configurations as defined above. Advantageously, the preferred implantation configuration for the head 11 is appreciated by the surgeon with regard to its impact on a possible weakening of the neck F2 of the femur F. Where appropriate, another preferred implantation configuration is determined, being either to be selected by the surgeon or proposed by the computer 2. To do this, the preferred implantation configuration of the prosthetic head 11 can be adjusted by adjusting the implantation configuration of the prosthetic cup 12. In a fifth During the operation, the surgeon prepares the F1 epiphysis of the femur F. For this purpose, the surgeon uses a forest guide or a similar ancillary, not shown in the figures, to guide the application of a femur preparation tool for set up the prosthetic head 11 on the femur, this forest guide or similar ancillary being permanently identified by the computer 2 , being provided for this purpose with locating means in space. The computer 2, by means of navigation means which it is equipped, guides the surgeon's gestures in order to prepare the femoral epiphysis F1, in particular with a view to dig in this epiphysis the receiving cavity of the keel 14, and this according to the preferred implantation configuration determined for the head 11 at the end of the fourth operating time. Similarly, during this fifth operation, the surgeon prepares the implantation area of the cup 12 in the basin B, using a suitable ancillary, identified by the computer 2 so that the latter guides the surgeon's gestures to implant. the cup 12 according to the preferential implantation configuration determined for the cup at the end of the fourth operating time.

In a sixth operating mode, the surgeon actually implants the head 11 and the cup 12 of the prosthesis 10 at the correspondingly prepared zones of the bones F and B. The device 1 according to the invention thus enables the prosthesis 10 to be positioned. optimally to reproduce as much as possible the kinematic capabilities of the anatomical hip of the operated patient. Various arrangements and variants of the implantation device 1 and method described above are furthermore possible. By way of examples: - rather than leaving the possibility of adjusting the implantation of the prosthetic cup 12, this implantation can be predetermined before the implementation of the fourth operating time, so that the device 1 then makes it possible to determine exclusively one or more preferred implantation configurations for the prosthetic head 11; the means for locating the bones of femur F and pelvis B are not limited to markers reflecting the infrared; markers sensitive to ultrasound or electromagnetic fields are for example usable; other means than a display screen are possible for communicating to the surgeon a feedback on the comparison of the relative positioning between the anatomical points F4 of the neck F2 of the femur F virtually prosthesis and the basin B virtually prosthesis; audible or tactile indications can thus make the surgeon understand the state of this comparison and guide him in the determination of one or more preferential implantation configurations of the prosthesis 10; the device 1 and the method can be applied to other joints than the hip, for example to the shoulder; and / or - as mentioned in the introductory part of this document, the device 1 can be used to implant a resurfacing hemi-prosthesis, that is to say a resurfacing prosthesis whose head articulates directly in a cavity anatomical bone, without the need for the implantation of a cupule such as the cup 12.

Claims (1)

CLAIMS1.- A surgical device (1) for implanting a resurfacing prosthesis (10) for a joint between a long bone and another bone of a patient, such as a hip joint between a femur (F) and a pelvis (B), this resurfacing prosthesis comprising a prosthetic head (11) adapted to be fixed to one end (F2) of the long bone (F) and to articulate in a substantially complementary manner in a cavity (16) fixedly attached to the other bone (B), this device being characterized in that it comprises: first measuring means (2, 3) adapted to measure, with respect to a reference axis (XX) fixedly associated with the long bone (F), and to memorize intraoperatively the position of anatomical points (F4) of the anatomical neck (F2) of this long bone, - second measuring means (2, 3) adapted to measure, by relative to the other bone (B), and to memorize peroperatively several positions of the reference axis (XX), c corresponding in particular to extreme articular configurations of the joint, specific to the patient, and - comparison means (2) adapted to compare, peroperatively, the relative positioning between, on the one hand, at least one of the anatomical points (F4) of the anatomical neck (F2) of the long bone (F) virtually provided with the prosthetic head (11) and, on the other hand, the edge of the cavity (16) of the other bone (B) ) in which the prosthetic head is provided to articulate, and at least in each of said plurality of positions of the reference axis (XX). 2.- Device according to claim 1, characterized in that it comprises means (7) for communicating to a surgeon the result of the comparison means (2). 3.- Device according to claim 2, characterized in that the communication means comprise a display means (7) adapted to represent, relatively and simultaneously, both the long bone (F) virtually prosthetic, the cavity (16) of the other bone (B) and the reference axis (XX). 4.- Device according to any one of the preceding claims, characterized in that it comprises means (2) for adjusting the virtual implantation of the prosthetic head (11) on the long bone (F). 5.- Device according to any one of the preceding claims, characterized in that, in the case where the cavity (16) of the other bone (B) is defined by a prosthetic cup (12) belonging to the resurfacing prosthesis (10), the device (1) further comprises means (2) for adjusting the virtual implantation of this prosthetic cup on the other bone. 6. Device according to any one of the preceding claims, characterized in that the comparison means comprise calculation means (2) adapted, at least in each of said plurality of positions of the reference axis (XX), to calculate the distance between at least one of the anatomical points (F4) of the anatomical neck (F2) of the long bone (F) virtually prosthetic, and the cavity (16) of the other bone (B). 7.- Device according to any one of the preceding claims, characterized in that it further comprises means (2) for extrapolation of a trajectory curve passing substantially through each of said plurality of positions of the reference axis ( XX), and in that the comparison means (2) are adapted to compare the relative positioning between at least one of the anatomical points (F4) of the anatomical neck (F2) of the virtually prosthetic long bone (F) and the cavity (16) of the other bone (B) while the reference axis (XX) traverses this trajectory curve. 8.- Device according to any one of the preceding claims, characterized in that it further comprises selection means (2) adapted both for selecting, by a surgeon and on the basis of the result of the comparison means ( 2), and to memorize a preferred implantation configuration of the prosthetic head (11) on the long bone (F). 9.- Device according to any one of claims 1 to 7, characterized in that it further comprises determining means (2) adapted both to calculate, on the basis of the result of the comparison means (2) , and to memorize a preferred implantation configuration of the prosthetic head (11) on the long bone (F). 10.- Device according to one of claims 8 or 9, characterized in that it further comprises a forest guide or a similar ancillary, to guide the application of a tool for preparing the end (F2) of the long bone (F) for positioning the prosthetic head (11) on the long bone, this forest guide or similar ancillary being equipped with means for locating in the space, and in that the device comprises in in addition to navigation means (2) adapted to position this forest guide or similar ancillary with respect to the long bone (F) in order to implant the prosthetic head (11) in the preferred implantation configuration provided either by the selection means, or by the determination means.