Device for extracting a prosthetic element such as a femoral rod

Abstract

The invention relates to an extraction device (D) for a prosthetic element (100) having an external projection, which is characterised in that it comprises: - a flange (400) including at least two movable jaws which cover said external projection; - a sleeve (300) which slides over the flange positioned on the external projection in order to hold it in the closed position; - a fastening screw equipped with a distal end and ensuring the fastening of the sleeve (300) to the flange (400) and thus of the assembly to the prosthetic element (100); and - extraction means (200) which fasten removably to said sleeve (300).

Description

Description Title of the invention: DEVICE FOR EXTRACTION OF A PROSTHETIC ELEMENT SUCH AS A FEMORAL STEM

[0001] FIELD OF APPLICATION OF THE INVENTION

[0002] The present invention relates to a device for extracting prosthetic elements such as femoral stems and in particular to adaptations making it possible to facilitate this extraction.

[0003] DESCRIPTION OF THE PRIOR ART

[0004] Among the prosthetic elements, femoral stems intended to be implanted in the femur of a patient are well known in the orthopedic field. They are composed of an intramedullary part introduced into the medullary canal of the femur and an extramedullary part consisting of a neck extended by a cone on which a prosthetic spherical head is assembled.

[0005] Femoral stems have smooth, polished surfaces for options with cementing in the femoral shaft (i.e., in the femoral medullary canal opened during cutting). Do stems intended for cementless implantation have surfaces with coatings compatible with osseointegration?

[0006] The preparation of the bone site is carried out with instruments adapted to the surgical approaches. The choice of the approach is motivated by the surgeon's practice, the surgical indication, and the patient's morphology. The main approaches used are posterior, anterior, and others between posterior and anterior. The patient's positioning is adapted for each approach, for each side to be operated on. During the incision, the successive muscular planes are dissected following precise trajectories that differ from each other. The visual and anatomical context is different for each approach, the operating environment, and the axes of introduction of the instruments are different for each surgical technique.

[0007] After sectioning and removing the femoral neck, several femoral rasps are inserted into the medullary canal until a stable match is achieved between the rasp size and the bone. The final prosthetic stem is then installed in the patient's femur. The prosthetic head is then installed on the cone of the stem, the joint is reduced in the acetabular cup, the closure of the surgical site is the final process of the intervention.

[0008] Two situations require the extraction of the femoral stem from the femur after a period of time distant from the intervention, or during the intervention. After a more or less significant delay, the indication for surgical revision may be necessary for reasons dependent or independent of the implant. The position of the components, wear, rupture, infection can motivate the extraction of the prosthetic parts. Intraoperatively, even if this risk is rare, it is sometimes necessary to extract the femoral stem already installed in the femur when, for example, the adjustment is not the desired one (a blockage of the stem in the femur having occurred too early).

[0009] To attach the femoral stem to an instrument in order to extract it, there are currently several technical solutions.

[0010] Among these, femoral stems usually include features that can be exploited for extraction purposes. These femoral stems include a threaded hole located at the external base of the neck that allows mechanical connection with a threaded rod equipped with a small mobile mass called a weight. This principle has limits in terms of forces exerted on this small diameter rod that can lead to its breakage. In addition, the axis of this threaded hole is not accessible in certain approaches.

[0011] There are also so-called universal systems that are fixed by firmly closing the jaws on the neck and cone region, extraction is achieved with a weight connected to the instrument. These systems have several disadvantages, among them:

[0012] - the jaws are not adapted to the various configurations of necks and cones,

[0013] - significant force must be exerted on the jaw closing system to obtain a reliable connection with the prosthesis,

[0014] -the weight separates the assembly, and finally

[0015] - the instrument is very bulky, it does not allow easy installation in all common and minimally invasive approaches.

[0016] Another system described in EP0645127 involves removably surrounding the neck region with a locking device that adapts to different prosthesis stem diameters. The adjustment force is transmitted along the head of the tool. Such a system has several disadvantages, including:

[0017] - Due to the different neck and cone configurations, the device does not fit optimally,

[0018] - the handling of this instrument is made difficult by the indirect surgical approaches which bypass soft and bony tissues, very short incisions,

[0019] - the curved head is invasive and close to the greater trochanter, which leads to a risk of contact and damage to the latter,

[0020] -the instrument is massive, it requires a wide incision with a single weight axis for extraction,

[0021] - the mechanical design of the device is complex and does not allow internal cleaning of the components.

[0022] The same problems can be encountered when extracting other prosthetic elements such as humeral stems.

[0023] BRIEF DESCRIPTION OF THE INVENTION

[0024] Having observed this, the applicants conducted research aimed at finding a new solution for the extraction of prosthetic elements, including a reliable, rapid and simple connection between the prosthetic element and the extraction device.

[0025] Such a device is intended for use in all surgical approaches to the hip; right side, left side, posterior, anterior, anterolateral, minimally invasive incision.

[0026] This research resulted in the design and production of an extraction device for a prosthetic element which comprises a body defining a first axis and an external projection defining a second axis, said projection being composed of a distal portion adopting the shape of a cone and a narrower proximal portion called the neck,

[0027] said device cooperating punctually with the prosthetic element for the purpose of extracting the latter.

[0028] This extraction device is remarkable in that it includes

[0029] - a flange including at least two movable jaws covering said external projection,

[0030] the two jaws being movable between an open position and a closed position,

[0031] the open position allowing the flange to slide axially on the external projection,

[0032] the closed position allowing the flange to be fixed to the external projection,

[0033] - a sheath sliding over the flange positioned on the external projection in order to keep it in the closed position,

[0034] - a fixing screw equipped with a distal end and ensuring the fixing of the sheath to the flange and therefore of the assembly to the prosthetic element,

[0035] - extraction means which can be removably attached to said sheath. The assembly consisting of the closed flange on the external projection of the prosthetic element covered with the sheath is locked by the fixing screw.

[0036] Such a design allows the device to be separated into two parts:

[0037] - a first part or flange dedicated to the external projection of the prosthetic element and its dimensions with the volume of the cone and the surface of the neck behind the large base of the cone and

[0038] a second part or sheath intended for cooperation with the extraction means.

[0039] This design allows us to consider an extraction kit described below with dedicated parts and common parts.

[0040] The opening of the jaws is conditioned to allow the cone to pass into the flange, the two parts close on the cone when the flange is pushed along a certain stroke.

[0041] The flange covers the external projection and is itself covered by the sheath.

[0042] There is no risk of detachment once the sheath covers the flange.

[0043] This cover sheath is installed on the flange in the same axis as it, in an intuitive and secure manner up to the stop materialized by the bottom of the cover sheath.

[0044] According to another particularly advantageous characteristic of the invention, the at least two jaws are equipped with an internal rim projecting transversely relative to the second axis, the closed position allowing the creation of an axial stop by means of the internal rims of the jaws which come to bear on the projection under the cone. Thus, the flange is installed on the prosthetic femoral stem is kept closed on the cone and with its internal rims facing each other around the neck behind the cone to bear on the base of the cone and thus create said axial stop.

[0045] The extraction device can be:

[0046] Available in the ancillary box on the operating table,

[0047] Available sterile in suitable packaging.

[0048] According to another particularly advantageous characteristic of the invention, the at least two jaws are preformed with a hollow core allowing them to match the shape of the cone of said external projection in the closed position.

[0049] The use of a flange inserted into the external volume defined by the external projection of a prosthetic element such as a femoral stem is particularly advantageous in that it increases, by matching said external volume, the adhesion surface for gripping purposes without making the resulting assembly larger than an anatomical femoral head.

[0050] According to another particularly advantageous characteristic of the invention, the flange is designed in such a way that a first jaw is preformed with a transverse groove into which a transverse rib preformed on the second jaw is introduced, the rib in the groove forming a pivot connection guiding the opening and closing.

[0051] The installation and positioning of the flange can thus be described as intuitive because guided from the first millimeters engaged on the cone of the prosthetic femoral stem, the manipulation is secured by an axis materialized by a cutout in the flange itself.

[0052] According to another particularly advantageous characteristic of the invention, said sheath is preformed to accommodate the extraction means along the two axes defined by the prosthetic element. The extraction means will participate in the extraction of the prosthetic femoral stem along the axis appropriate to the surgical approach.

[0053] In addition, as the sheath initially slides onto the flange, it will be able to rotate around its axis and position the locations for the extraction means according to previously inaccessible intermediate access routes. Thus, the most appropriate access route can be chosen.

[0054] According to another particularly advantageous characteristic of the invention, the sheath is provided with a transverse threaded hole into which the fixing screw is screwed, the distal end of which cooperates with a peripheral groove provided in the external surface of the flange so as to hold the sheath in position, which holds the flange in the closed position.

[0055] According to another particularly advantageous characteristic of the invention, the sheath is provided with an axial hole into which the fixing screw slides, the distal end of which is screwed into an axial threaded hole provided in the flange so as to hold the sheath in position, which holds the flange in the closed position.

[0056] The extraction means can be fixed to the sheath or to the fixing screw provided for this purpose.

[0057] However, according to another particularly advantageous characteristic of the invention, the extraction means comprise a threaded end ensuring the function of the fixing screw. The device thus adopts a design that is simple to use, the fixing of the extraction means according to the chosen approach route on the sheath ensuring that said sheath is held on the flange and therefore locked in the closed position.

[0058] It is understood that the design of the device makes its components of the extraction device thus easily removable and cleanable.

[0059] Additionally, some of the low volume components can be offered in sterile packaging, available upon request.

[0060] Thus, another object of the invention relates to an extraction kit where the device comprises:

[0061] - a sheath,

[0062] - extraction means which are screwed onto said sheath,

[0063] - a plurality of flanges with hollow cores preformed to the shapes and dimensions of the external projections of a plurality of different prosthetic elements.

[0064] According to another particularly advantageous characteristic of the invention, the extraction means consist of a rod equipped with a weight

[0065] One end of this rod is equipped with a threaded portion allowing it to be fixed to said sheath and, if necessary, ensuring the sheath is locked onto the flange.

[0066] The rod and its weight will therefore be fixed along an appropriate extraction axis.

[0067] According to a preferred embodiment, the various constituent elements of the device are made of metal.

[0068] The fundamental concepts of the invention having just been set out above in their most elementary form, other details and characteristics will emerge more clearly on reading the description which follows and with reference to the appended drawings, giving by way of non-limiting example, an embodiment of a device in accordance with the invention.

[0069] BRIEF DESCRIPTION OF THE DRAWINGS

[0070] [fig.1 a] is a schematic drawing of a side view of an embodiment of a device according to the invention fixed to a prosthetic element with a fixing of the rod along the axis of the body of the prosthetic element;

[0071] [fig.1 b] is a schematic drawing of a side view of an embodiment of a device according to the invention fixed to a prosthetic element with a fixing of the rod along the axis of the external projection of the prosthetic element;

[0072] [fig.2] is a schematic drawing of an exploded side view of the assembly of figure 1a;

[0073] [fig.3] is a schematic drawing of a partial exploded perspective view of the connection end of the device of figure 1a;

[0074] [fig.4a] is a schematic drawing of a sectional view of the assembly of figure 1a;

[0075] [fig.4b] is a schematic drawing of a sectional view of the assembly of figure 1b;

[0076] [fig.5] is a schematic drawing of an exterior side view of a flange above a prosthetic femoral stem;

[0077] [fig.6] is a schematic drawing of an exterior side view of a cover module over a flange over a prosthetic femoral stem;

[0078] [fig.7] is a schematic drawing of an external side view of the installation of the rod with moving mass according to the position of figure 1 a;

[0079] [fig.8] is a schematic drawing of an external side view of the installation of the rod with moving mass according to the position of figure 1 b;

[0080] [fig.9] is a schematic drawing of an exterior side view of a flange according to the invention;

[0081] [fig.10] is a schematic drawing of an external side view of a sheath according to the invention;

[0082] [fig.11] is a schematic drawing of an exterior side view of a femoral stem below the flange of [fig.2];

[0083] [fig.12] is a schematic drawing of an external side view of the rod with moving mass and with threaded end;

[0084] [fig.13] is a schematic drawing of an exterior side view of an embodiment of an extraction kit according to the invention.

[0085] DESCRIPTION OF A PREFERRED EMBODIMENT

[0086] As illustrated by figures 1 a and 1 b, the device referenced D as a whole is associated punctually with a prosthetic element, here a femoral stem 100, for the purpose of extracting the stem 100 from the femur referenced F.

[0087] As illustrated in Figure 2, this device D includes:

[0088] - a rod 200 with a moving mass 210,

[0089] - a 300 sheath,

[0090] - a 400 flange.

[0091] As illustrated in more detail by Figure 11, said femoral stem 100 is a conventional prosthetic element which has a body cooperating with the femoral bone F (see Figure 1) and an external projection. Said projection is composed of a distal portion adopting the shape of a cone 101 and a narrower proximal portion called neck 102 connecting the cone to the body.

[0092] The body is elongated and defines a first longitudinal axis and the cone defines a second axis.

[0093] As illustrated in more detail by Figure 12, the rod 200 comprises:

[0094] - at a first end, a shoulder 205, a threaded portion 203 of diameter smaller than that of the rest of the rod and a rounded end 204 at the distal end of the threaded portion;

[0095] - at the other end, a screw handle 201 with a face 202 serving as a striker with which comes into contact with the face 211 of the mobile mass 210 actuated according to the arrow F1 by the user.

[0096] The sheath 300 adopts a substantially cylindrical shape closed at one end with a lateral protrusion. It is illustrated in more detail in sectional view by Figures 4a and 4b and in external view by Figure 10. It comprises:

[0097] - a hollow cylindrical core 301,

[0098] - a transverse threaded orifice 302 formed in said protrusion, passing through and opening into the hollow core 301 cooperating with the threaded end 203 of the rod 200,

[0099] - a smooth axial orifice 303 passing through the closed end and opening into the hollow core 301.

[0100] The flange 400 is illustrated in more detail in sectional view by Figures 4a and 4b and in exterior view by Figure 9. It comprises:

[0101] - two jaws 401 and 402 articulated around an axis 407 materialized and cut out following a cutout 408 made in the flange 400 to form a transverse rib and groove cooperating to allow pivoting,

[0102] - a peripheral external groove 403 with which the rounded end 204 of the rod 200 cooperates,

[0103] - a hollow core defined by the internal surfaces 404 and the internal rims 405 which cooperate respectively with the surfaces of the cone 101 and the neck 102 of the femoral stem 100,

[0104] - a threaded orifice 406 cooperating with the threaded end 203 of the rod 200,

[0105] - an external surface 409 cooperating with the hollow core 301 of the sheath 300.

[0106] As illustrated by figures 2, 3, 5 and 6, the flange 400 covers the external projection of the femoral stem 100, the sheath 300 is installed on it and the stem 200 is fixed to the sheath 300.

[0107] More precisely, as illustrated in FIG. 5, the flange 400 is presented above the cone 101 of the femoral stem 100 following the arrow F2. Continuing the movement following the arrow F2 results in an outward rotation of the two jaws 401 and 402 around the axis 407 following the arrow F3.

[0108] As illustrated by Figure 6, when the surfaces 404 and 405 of the flange 400 cooperate completely with the surfaces 101 and 102 of the femoral stem 100, that is to say when the bottom of the hollow core of the flange 400 is positioned at the top of the cone 101, the internal edges 405 close around the neck 102 under the base of the cone 101 (see Figures 4a and 4b).

[0109] When the sheath 300 is presented on the flange 400 according to the arrow F4, it thus opposes, according to the arrow F5, the opening of the jaws 401 and 402 of the flange 400.

[0110] As illustrated by figures 4a and 4b, this constraint according to arrow F5 is reflected on the external surface 409 of the flange 400 as well as on the internal surfaces 404 and 405 guaranteeing cooperation with the external surfaces of the cone 01 and the neck 102 of the femoral stem 100 and the maintenance of the axial stop that they constitute.

[0111] The method of fixing the flange 400 through the sheath 300 is linked to the choice of the extraction axis by the user.

[0112] Indeed, either the rod 200 is fixed to the sheath 300 in the longitudinal axis of the body of the femoral rod 100 as illustrated by figures 1 a, 2, 4a and 7, or the rod 200 is fixed to the flange 400 by bearing on the sheath 300 in the axis of the cone 101 of the external projection of the femoral rod 100 as illustrated by figures 1 b, 4b and 8.

[0113] As the sheath 300 can rotate on the flange 400, intermediate extraction axes are also possible.

[0114] Figure 4a illustrates the attachment, when the rod 200 is attached to the sheath 300 along an axis parallel to the longitudinal axis of the body of the femoral rod 100, that is to say by screwing into the threaded orifice 302 formed in the lateral protrusion of the sheath 300.

[0115] The length of the portion of the threaded end 203 allows the rounded end 204 to come into the hollow core 401 of the sheath 300 to be in contact with the flange 400 housed inside and thus ensure the locking of the sheath 300 on the flange 400 and guarantee the maintenance in the closed position of the latter despite the constraints of the impacts of the weight 210 during extraction.

[0116] To optimize this locking, the axis of the threaded hole 302 opens into the hollow core 301 so that the rounded end 204 enters the peripheral groove 403 from which the flange 400 is preformed. The rounded end 204 then constitutes an axial stop between the sheath 300 and the flange 400. Thus, even without clamping stress exerted by the rod 200, the sheath 300 cannot be released from the flange 400 which cannot therefore open while being held in the closed position on the external projection of the femoral stem 100.

[0117] Figure 4b illustrates the attachment when the rod 200 is attached to the sheath 300 along the axis of the cone 101 of the femoral rod 100, that is to say by screwing into the threaded orifice 406 formed in the axis of the flange, passing through the smooth hole 303 formed in the sheath 300.

[0118] The shoulder 205 comes to bear on the sheath 300 around the smooth hole 303 and the screwing comes to exert a constraint tending to make the flange 400 return into the sheath 300. The flange ensuring by its internal edges 405 an axial stop under the cone 101, the sheath 300 is locked on the flange 400 which is held in the closed position on the external projection of the femoral stem 100.

[0119] Figure 13 illustrates a device in the form of an extraction kit sharing a single rod 200 with mobile mass 210 and a single sheath 300 associated with a plurality of flanges 400a, 400b, 400c, 400d dedicated to the dimensions and profiles of external projections of different prosthetic elements.

[0120] It is understood that the device which has just been described and represented above has been done so with a view to disclosure rather than limitation. Of course, various arrangements, modifications and improvements may be made to the above examples, without departing from the scope of the invention.

Claims

Demands

1. Extraction device (D) for a prosthetic element (100) comprising a body defining a first axis and an external projection defining a second axis, said projection being composed of a distal portion in the shape of a cone (101) and a narrower proximal portion called the neck (102), said device cooperating occasionally with the prosthetic element (100) for the purpose of extracting the latter, and comprising - a flange (400) including at least two movable jaws (401, 402) fitting over said external projection, the two jaws being movable between an open position and a closed position, the open position allowing the flange (400) to slide axially on the external projection, the closed position allowing the flange (400) to be fixed on the external projection, - a sleeve (300) that slides onto the flange positioned on the external projection in order to hold it in the closed position, - a fixing screw equipped with a distal end and ensuring the fixing of the sheath to the flange and therefore of the assembly to the prosthetic element, - extraction means (200) which can be attached in a removable manner to said sheath (300), CHARACTERIZED BY THE FACT THAT - said extraction means (200) comprise a threaded end (203) which serves as a fixing screw, - said sheath (300) is pre-formed to accommodate the extraction means along the two axes defined by the prosthetic element, - the sleeve (300) being provided: with a transverse threaded hole (302) into which the threaded end is screwed, the distal end of which cooperates with a peripheral groove (403) provided in the outer surface of the flange (400) so as to hold the sleeve (300) in position which holds the flange (400) in the closed position, of an axial hole (303) into which the threaded end slides, the distal end of which screws into an axial threaded hole (406) provided in the flange (400) so as to hold in position the sleeve (300) which holds the flange (400) in closed position,

2. Device (D) according to claim 1, CHARACTERIZED IN THAT the at least two jaws (401, 402) are equipped with an internal rim (405) projecting transversely with respect to the second axis, the closed position allowing the creation of an axial stop by means of the internal rims (405) of the jaws (401, 402) which come to rest on the projection under the cone (101).

3. Device (D) according to any one of claims 1 to 2, CHARACTERIZED BY THE FACT THAT the at least two jaws (401, 402) are pre-formed with a hollow core (404) enabling them to conform in closed position to the shape of the cone (101) of said external projection.

4. Device (D) according to any one of claims 1 to 3, CHARACTERIZED IN THAT the flange (400) is designed such that a first jaw (401) is pre-formed with a transverse groove into which a pre-formed transverse rib on the second jaw is inserted, the rib in the groove forming a pivot joint guiding the opening and closing.

5. Device (D) according to any one of claims 1 to 4, CHARACTERIZED IN THAT it comprises - a sheath (300), - extraction means (200) which are fixed by screwing to said sheath, - a plurality of flanges (400a, 400b, 400c, 400d) with hollow cores preformed to the shapes and dimensions of the external projections of a plurality of different prosthetic elements.

6. Device (D) according to any one of claims 1 to 5, characterized in that the extraction means consist of a rod (200) equipped with a weight (210).

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