EP4493125A1 - Device for extracting a prosthetic element such as a femoral rod - Google Patents

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 EXTRACTING A PROSTHETIC ELEMENT SUCH AS A FEMORAL ROD

[0001] FIELD OF APPLICATION OF THE INVENTION

The present invention relates to a device for extracting prosthetic elements such as femoral stems and in particular to adaptations making this extraction easier.

[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 intra-medullary part introduced into the medullary canal of the femur and an extra-medullary part consisting of a neck extended by a cone on which a prosthetic spherical head is assembled.

[0005] The femoral stems have smooth, polished surfaces for options with cementing in the femoral shaft (that is to say in the femoral medullary canal opened during cutting). Do the stems intended to be implanted without cement have surfaces with coatings compatible with osseointegration?

[0006] The preparation of the bone site is carried out with instruments adapted to surgical approaches. The choice of 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 installation 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 are different from each other. The visual and anatomical context is different for each approach, the operating environment, the axes of introduction of the instruments are different for each surgical technique.

[0007] After having cut and extracted the neck of the femur, several femoral rasps are introduced into the medullary canal until a stable match is obtained between the size of the rasp and the bone. The definitive prosthetic stem is then installed in the patient's femur. The prosthetic head is in turn installed on the cone of the stem, the joint is reduced in the acetabular acetabulum, closure of the surgical site is the final process of the procedure.

[0008] Two situations impose the need to extract the femoral stem from the femur after a period distant from the intervention, or during the intervention. After a more or less significant delay, the indication for surgical revision may become necessary for reasons dependent or independent of the implant. The position of the components, wear, breakage, infection can motivate the extraction of 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 as desired (a blockage of the stem in the femur having occurred too early) .

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

[0010] Among these, the femoral stems usually include characteristics capable of being exploited for extraction purposes. These femoral stems include a threaded hole located at the external base of the neck allowing the mechanical connection with a threaded stem equipped with a small mobile mass called a weight. This principle presents limits on the forces exerted on this small diameter rod which 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 which are fixed by firmly closing the jaws on the region of the neck and the cone, extraction is obtained with a flyweight connected to the instrument. These systems have several disadvantages, including:

[0012] - the jaws are not adapted to the various neck and cone configurations,

[0013] - it is necessary to exert a significant force on the jaw closing system to obtain a reliable connection with the prosthesis,

[0014] - the weighting 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 document EP0645127 consists of removably encircling the neck region with a locking device which adapts to different prosthesis stem diameters. The adjustment force is transmitted along the tool head. Such a system has several disadvantages, including:

[0017] - Due to the different neck and cone configurations, the adaptation of the device is not optimal,

[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 weighting 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 for the extraction of other prosthetic elements such as humeral stems.

[0023] BRIEF DESCRIPTION OF THE INVENTION

[0024] Observing this, the applicants have carried out research aimed at a new solution for the extraction of prosthetic elements including a reliable, rapid and simple connection between the prosthetic element and the extraction device.

Such a device is intended to be used in all surgical approaches to the hip; right side, left side, posterior, anterior, anterolateral incision, minimally invasive.

[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 portion distal adopting the shape of a cone and a narrower proximal portion called the neck, [0027] said device cooperating occasionally 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 fixing of the flange on the external projection,

[0033] - a sheath sliding on the flange positioned on the external projection in order to maintain 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 are fixed in a removable manner to said sheath.

The assembly composed 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 makes it possible to separate the device into two parts:

[0037] - a first part or flange dedicated to the external projection of the prosthetic element and to 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 makes it possible to envisage an extraction kit described below with dedicated parts and common parts.

The opening of the jaws is conditioned to allow the cone to pass through the flange, the two parts close on the cone when the flange is pushed according to a certain stroke. [0041] The flange covers the external projection and is itself covered by the sheath.

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

[0043] This covering sheath is installed on the flange in the same axis as the latter, intuitively and securely up to the stop materialized by the bottom of the covering 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 rims internal parts of the jaws which bear on the projection under the cone. Thus, the flange is installed on the prosthetic femoral stem and is kept closed on the cone and with its internal edges facing each other around the neck behind the cone to rest 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 which is introduced 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 surface of adhesion for gripping purposes without making the resulting assembly more bulky 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 preformed transverse rib is inserted on the second jaw, 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 it -even.

[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] Furthermore, as the sheath initially slides on the flange, it will be able to rotate around its axis and position the reception locations for the extraction means according to intermediate access routes hitherto inaccessible. In this way, the most appropriate approach 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 formed in the exterior surface of the flange so as to hold in position the sheath 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 to maintain in position the sheath 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 simple to use design, the fixing of the extraction means according to the approach chosen on the sheath ensuring the maintenance of said sheath on the flange and therefore its locking in the closed position. [0058] We understand that the design of the device makes its components of the extraction device thus removable and easy to clean.

[0059] In addition, some of the low volume components can be offered in sterile packaging, made available on request.

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

[0061] - a sheath,

[0062] - extraction means which are fixed by screwing to 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 are constituted by 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, to ensure the locking of the sheath to the flange.

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

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

[0068] The fundamental concepts of the invention having just been explained above in their most basic 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 according to 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 fixing of the rod along the axis of the prosthetic element body; [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 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 above a flange above a prosthetic femoral stem;

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

[0079] [fig.8] is a schematic drawing of an exterior side view of the installation of the rod with movable 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 exterior 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 exterior side view of the rod with movable 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 punctually associated with a prosthetic element here a femoral stem 100 for the purpose of extracting the stem 100-out of the femur referenced F.

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

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

[0089] - a sheath 300,

[0090] - a 400 flange.

[0091] As illustrated in more detail by Figure 11, said femoral stem 100 is a classic 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 the neck 102 connecting the cone to the body.

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

[0093] As illustrated in more detail in 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 screwing handle 201 with a face 202 serving as a knocker with which the face 211 of the mobile mass 210 comes into contact activated according to the arrow F1 by the user.

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

[0097] - a cylindrical hollow core 301,

[0098] - a transverse threaded orifice 302 formed in said protuberance, 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 in Figures 4a and 4b and in exterior view in Figure 9. It includes:

[0101] - two jaws 401 and 402 articulated around an axis 407 materialized and cut according to a cutout 408 made in the flange 400 to form a rib and a transverse groove cooperating to authorize 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 edges 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 in 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 Figure 5, the flange 400 is presented above the cone 101 of the femoral stem 100 following the arrow F2. Continuing the movement following arrow F2 results in an outward rotation of the two jaws 401 and 402 around axis 407 following arrow F3.

[0108] As illustrated in 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 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 along the arrow F4, it thus opposes, along 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 along the 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 maintaining 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 on 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 on the flange 400 by bearing on the sheath 300 in the axis of the cone 101 of the external projection of the femoral stem 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 fixation, when the rod 200 is fixed 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 projection 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 locking of the sheath 300 on the flange 400 and guarantee that the latter is maintained in the closed position despite the constraints of the impacts of the flyweight 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 a axial stop between the sheath 300 and the flange 400. Thus, even without tightening stress exerted by the rod 200, the sheath 300 cannot free itself 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 fixation when the rod 200 is fixed to the sheath 300 along the axis of the cone 101 of the femoral stem 100, that is to say by screwing into the threaded orifice 406 provided in the axis of the flange passing through the smooth hole 303 provided in the sheath 300.

[0118] The shoulder 205 comes to rest on the sheath 300 around the smooth hole 303 and the screwing exerts a stress tending to make the flange 400 enter the sheath 300. The flange ensuring, through 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 dimensions and profiles of external projections of different prosthetic elements.

[0120] We understand that the device which has just been described and represented above was done with a view to disclosure rather than limitation. Of course, various adjustments, modifications and improvements could be made to the examples above, without departing from the scope of the invention.

Claims

Claims [Claim 1] Extraction device (D) for a prosthetic element (100) 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 (101) and a narrower proximal portion called neck (102), said device cooperating punctually 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) covering 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 fixing of the flange (400) on the external projection, - a sheath (300) sliding on the flange positioned on the external projection in order to maintain 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 are fixed in a removable manner to said sheath (300), CHARACTERIZED BY THE FACT THAT - said extraction means (200) comprise a threaded end (203) ensuring the function of the fixing screw, - said sheath (300) is preformed to accommodate the extraction means along the two axes defined by the prosthetic element, - the sheath (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) formed in the exterior surface of the flange (400) ) so as to hold in position the sheath (300) which holds the flange (400) in the closed position, 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 the sheath (300) in position which keeps the flange (400) in the closed position, [Claim 2] Device (D) according to claim 1, CHARACTERIZED BY THE FACT 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 edges (405) of the jaws (401, 402) which come to rest on the projection under the cone (101). [Claim 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 preformed with a hollow core (404) allowing them to fit in closed position the shape of the cone (101) of said external projection. [Claim 4] Device (D) according to any one of claims 1 to 3, CHARACTERIZED BY THE FACT THAT the flange (400) is designed in such a way that a first jaw (401) is preformed with a transverse groove in which inserts a preformed transverse rib on the second jaw, the rib in the groove forming a pivot connection guiding the opening and closing. [Claim 5] Device (D) according to any one of claims 1 to 4, CHARACTERIZED BY THE FACT 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. [Claim 6] Device (D) according to any one of claims 1 to 5, CHARACTERIZED BY THE FACT THAT the extraction means consist of a rod (200) equipped with a weight (210). i