EP2330984A1

EP2330984A1 - Set of ancillaries for implanting a knee prosthesis

Info

Publication number: EP2330984A1
Application number: EP09740485A
Authority: EP
Inventors: Francis Guillaume
Original assignee: Individual
Current assignee: Individual
Priority date: 2008-08-25
Filing date: 2009-08-24
Publication date: 2011-06-15
Also published as: FR2935092A1; WO2010023399A1; FR2935092B1

Abstract

This set of ancillaries comprises, among other things, an ancillary (10) for tensioning the knee, which ancillary (10) comprises: two branches (13', 14') for femoro-tibial spreading of the knee; a device (12) for marking, on the front face of the femur (F), the implantation of extramedullary pins, first (70), second and third ancillaries for femoral cutting, which are respectively provided with an anterior cutting slit, a distal cutting slit, and a posterior cutting slit, the first and third ancillaries for femoral cutting being designed to be positioned with respect to the femur by cooperating with those parts, projecting from the front face of the femur, of pins that are implanted in the femur in respective directions. Moreover, the marking device comprises a block (43) for extramedullary targeting of the directions of implantation of the pins, which block (43) is designed to be supported by the rest of the tensioning ancillary and on which the first and/or the second ancillaries for femoral cutting are designed to be fixed.

Description

ANCILLARY SET TO IMPLEMENT A KNEE PROSTHESIS

The present invention relates to a set of ancillaries for implanting a knee prosthesis, in particular a so-called "moving plate" prosthesis.

In Figure 9A is shown an example 1 of such a knee prosthesis "movable plate". In known manner, this prosthesis 1 comprises a tibial component in the form of a metal base 2, a femoral component in the form of a metal cap 3 and a polyethylene insert 4 constituting the movable plate of the prosthesis. As shown in FIGS. 9B and 9C, the tibial base 2 is designed to be firmly attached to the upper end of the tibia T and delimits for this purpose a bearing surface 2A on and of attachment to a corresponding resected surface T _A of the tibia while the femoral cap 3 is firmly attached to the lower end of the femur F delimiting for this purpose a multi-planar face 3A of support on and securing to a corresponding resected face F _A of the femur. The face 4A of the plate 4 turned towards the base 2 rests movably on the upper face 2B of this base while the opposite face 4B of the plate defines two concave surfaces 4B ₁ and 4B ₂ intended to articulately receive two convex surfaces. associated 3B ₁ and 3B ₂ defined by the corresponding face 3B of the cap 3 and approximately reproducing the geometry of two internal and external anatomical femoral condyles.

The prosthesis 1 makes it possible to reproduce a kinematics close to that of the anatomical knee, guaranteeing the patient a good comfort in use. However, the freedom of movement internal to this prosthesis require a high accuracy of implantation prosthetic components and require to take into account the ligamentous environment of the knee. In particular, in order to ensure the best possible range of motion and the best possible stability, the surgeon seeks as much as possible the equality of the values of the gap in use between the femur and the tibia, both in flexion, in particular at 90 °. than in extension. This spacing corresponds in practice to the place available to the prosthetic parts being stressed, that is to say the parts of the prosthesis in contact with each other which, by their dimensioning, have a total thickness, following the direction of solicitation, substantially identical in bending at 90 ° and in extension. This circumvention is, as a result, commonly referred to as "prosthetic crowding". These prosthetic bulges in flexion and extension are respectively denoted by EPi and EP ₂ in FIGS. 9B and 9C, the prosthetic bulkiness EPi in flexion being substantially equal to the distance between the resected tibial surface T _A and the posterior cutting plane F _AP of the femoral resected face F _A , while the prosthetic footprint EP ₂ in extension is substantially equal to the distance between the same tibial surface T _A and the distal cutting plane F _AD of the multi-plane femoral face F _A. In addition, to avoid any excess pressure on one of the inner or outer sides of the movable plate 4, or dislocation of this plate, the ligament stresses, including those due to the lateral ligaments must be balanced on each inner and outer side of the knee prosthesis.

To implant a knee prosthesis such as prosthesis 1, the surgeon uses successively and / or simultaneously several different ancillaries. For example, among them, there may be mentioned an ancillary resection of the upper end of the tibia T.

By WO-A-2005/092205 in the name of the present Applicant, there is known an ancillary tensioning allowing the surgeon both to check the ligament balance internal / external of the knee flexion at 90 ° and extension and d automatically impose equal prosthetic congestion in flexion and extension. For this purpose, this ancillary tensioning comprises a locating device for setting in a controlled manner extra-medullary pins on each inner and outer side of the femur. These pins form spacial markers for subsequent cuts of the lower end of the femur, especially at its anterior, distal and posterior. This ancillary tensioning, associated with a femoral cutting ancillary able to cooperate, on each inner and outer side of the femur, with protruding parts of extra-medullary pins implanted using the ancillary tensioning , significantly improves the accuracy of placement of a knee prosthesis.

US-A-2007/0293868 proposes, for its part, to locate the realization of the femur sections by pins implanted in the front side of the femur using of an ancillary of tensioning. However, the surgical approach of the knee is extended because of the use of large femoral cutting blocks, which are to be put in place using the aforementioned pins previously implanted and then fixed firmly to the femur before performing the cutting operations. bone proper.

The object of the present invention is to improve the existing sets of ancillaries, by reducing the extent of the surgical approach of the operated knee, in particular by making the use of this set of ancillaries less invasive.

For this purpose, the invention relates to a set of ancillaries for implanting a knee prosthesis, as defined in claim 1.

The idea underlying the invention is, as in WO-A-2005/092205, to locate, with respect to the tibia, a reference plane which, with respect to the femur according to whether the knee is in flexion or in extension, corresponds to two substantially perpendicular planes, thanks to pins implanted in the femur, but, rather than implanting these pins on each inner and outer side of the femur, the invention provides for implanting these pins on the front side. of the femur, that is to say on the side of the knee that the surgeon can approach easily and minimally invasive, knowing that, at the time of actual implantation of extramedullary pins, the patella of the patient may or may not be dislocated. Of course, the front side of the femur includes the strictly median zone of the front of the femur, whether the latter is flexion or extension, but also the adjacent zones of this median zone, which can thus be described as antero -lateral and anteromedial. Note that here, the term "pins" is not limited to the shape of the mechanical parts that the surgeon reports on the front side of the femur using the tracking device to define the two femoral planes. Thus, in practice, the extra-medullary spindles concerned by the invention can also be presented, without limitation of shape, as pointed stems at one of their ends, flat-headed pawns, small forest type trees , or screws, for example. Thanks to the invention, the surgeon does not have to release the soft parts of the knee located on each inner and outer side of the femur, the action of the claimed ancillaries, in particular the aiming block integrated in the ancillary setting. voltage, being located essentially, or even exclusively on the front side of the femur. This provision, however, requires the surgeon to perform the femoral sections, including the distal section and either the anterior section or the posterior section, using several separate cutting ancillaries: as explained in detail below with examples, these ancillaries Femoral cutters are positioned on the femur by means of the pins implanted on the front side of the femur with the aid of the tracking device and are, at least for some of them, directly supported by the aiming block, which makes it possible to limit the size of these ancillary cutting, while ensuring the accuracy and stability of their positioning vis-à-vis the femur. Other advantageous features of this set of ancillaries, taken individually or in any technically possible combination, are specified in the dependent claims 2 to 15.

The subject of the invention is also a method for fitting a knee prosthesis, as defined in claim 16. The invention will be better understood on reading the description which follows, given solely by way of example and made with reference to the drawings in which:

- Figure 1 is an exploded perspective view of an ancillary tensioning belonging to a set of ancillaries according to the invention; - Figure 2 is a perspective view illustrating the stressing of a knee bending at 90 ° by the ancillary of Figure 1;

- Figure 3 is a view similar to Figure 2, illustrating the tensioning of the same knee in extension, by the ancillary of Figure 1;

FIGS. 4A and 4B are views respectively in perspective and in elevation of the ancillary device of FIG. 1, in use on the knee in flexion, in order to identify the implantation of extramedullary femoral pins;

FIGS. 5A and 5B are views respectively in perspective and in elevation of an anterior femoral cutting ancillary belonging to the set of ancillaries according to the invention, positioned on the bending femur provided with implanted pins according to the identification of Figures 4A and 4B;

FIGS. 6A and 6B are views respectively similar to FIGS. 4A and 4B, illustrating the use of the ancillary device of FIG. 1 on the knee in extension, in order to identify the implantation of other extramedullary femoral pins;

FIGS. 7A and 7B are views respectively in perspective and in elevation of a distal femoral cutting ancillary belonging to the set of ancillaries according to the invention, positioned on the extended femur provided with implanted pins according to the identification of Figures 6A and 6B;

FIGS. 8A and 8B are views respectively in perspective and in elevation of a third femoral section ancillary belonging to the set of ancillaries according to the invention, positioned on the bending femur with the aid of the following implanted pins. the registration of FIGS. 4A and 4B;

Fig. 9A is an exploded perspective view of a movable platen knee prosthesis;

FIGS. 9B and 9C are elevational views, taken internally, of the knee provided with the prosthesis of FIG. 9A, respectively in flexion and in extension;

- Figure 10 is a perspective view, partially in section, of an alternative embodiment, according to the invention, the tensioning ancillary; and

- Figure 11 is a view similar to Figure 6A, illustrating the use of the ancillary of Figure 10.

In Figure 1 is shown an ancillary 10 of knee tensioning, for use in implanting the prosthesis 1 of Figure 9A. This ancillary device 10 essentially comprises a main tensioning device 11 and a tracking device 12 adapted to be removably attached to the main device 11, as explained later in detail.

The main device 11 comprises two elongated rigid branches 13 and 14, of curved shape along their length. These branches are articulated in rotation with respect to one another about an axis ZZ substantially perpendicular to the longitudinal direction of the branches, so that by bringing the proximal portions of the branches closer to one another, that is to say their part intended to be turned to the surgeon during the use of the device 11, their respective distal portion is closer to each other, and vice versa. To allow adjustment and maintenance of a separated configuration of the parts proximal branches, and therefore a configuration spaced apart from the distal portions of these branches, the device 11 is advantageously equipped, for example, with a compression spring, not shown, which is interposed between the proximal portions of the branches and which, at rest , spreading the branches apart, while compressing the spring, the distal parts are brought closer to each other so as to allow their introduction into the femoro-tibial space. In this case, the aforementioned compression spring is dimensioned so that, during the relaxation of the proximal portions of the branches of the ancillary, the tensioning of the joint is performed with an anatomically appropriate value, being preferably adjustable to the using dynamometric measurement means provided between the branches 13 and 14 to quantify the powering of the knee.

In its distal portion, the branch 13 is secured to a cylindrical rigid rod 20 having a non-circular base of axis XX and which extends substantially perpendicular to both the longitudinal direction of this branch and the direction of the ZZ axis. This rod 20 is for example welded to the branch 13 or is directly material with it. In variant not shown, it can be removable. The rod 20 has along its entire length two flats 22 diametrically opposed and belonging to planes substantially perpendicular to the axis Z-Z.

The rod 20 passes right through the distal portion of the branch 14, through an oblong hole 23 whose largest dimension is directed along the length of the branch 14 while its smallest dimension is substantially equal to the distance between the flats 22. No significant transverse deflection is thus allowed between the stem and the branch 14.

At its distal end, the branch 13 is integral with a metal pallet 26, for example integral with the rest of the branch. This pallet is in the form of a flat plate, rigid and thin in relation to the rest of the branch. It thus defines a flat lower face 26A which belongs to a plane substantially perpendicular to the axis XX and which is intended to bear against the resected surface T _A of the tibia T. For this purpose, the peripheral contour of the pallet 26 is shaped to best fit the current geometry of a tibial resection, including Distal notch 27 provided to receive the posterior ligaments of the knee joint when placing the pallet in the femorotibial space.

At its distal end, the branch 14 is in the form of a rigid finger 28 integral with the rest of the branch, in the longitudinal extension of the latter. The lower surface of this finger is substantially planar, which allows plane-plane contact with the upper face of the pallet 26 when the proximal portions of the branches 13 and 14 are brought closer together. The upper surface 28A of the finger 28 is of convex shape and is dimensioned to be accommodated in the anatomical inter-condylar notch of the femur, as explained below. This surface is for example semi-cylindrical.

As indicated above, the marking device 12 is adapted to be removably attached to the device 11, more precisely around its rod 20. This device 12 comprises a tubular sleeve 30 whose inner section is substantially adjusted on the section 20. The sleeve 30 is thus reported around the rod 20 movably in translation along the axis XX, while being permanently connected to the rod. More generally, it is understood that the sleeve 30 may be connected to the rod 20 by any other means or shape than the flats 22, as long as its angular position around this rod is stable, at an angular displacement of a few degrees around the XX axis.

To immobilize the sleeve in translation relative to the rod, a locking screw 35 is provided to wedge against one of the flats 22 being screwed in a radial bore to the sleeve 30. The head of this screw 35 is advantageously under the shape of a hexagonal print 36.

At its upper end, the sleeve 30 is surrounded by an outer ring 37 fixed in translation and free to rotate relative to the sleeve. The ring is designed to be immobilized relative to the sleeve by a locking screw 38. In addition, this ring is traversed radially by a bent rod 40. The portion of the rod 40 inserted through the ring 37 is freely translatable. inside the ring, as indicated by the double arrow Fi. This rod portion delimits a flat portion adapted to extend facing a radial orifice delimited in the ring. Inside this hole, a locking screw 39 can be introduced to lock the rod 40 relative to the ring so that the axis of its bent portion 40a extends perpendicular to the axis XX.

In its lower part, the sleeve 30 is provided with a transverse base 41 traversed from one side by two bores which extend perpendicularly to the direction of the central axis of the sleeve, therefore to the direction of the axis XX when the sleeve is attached around the rod 20, being located on either side of this axis. The base 41 is thus adapted to carry a sighting unit 43 integral with two rods 42 complementary to the bores of the base. This block 43 can thus be connected to the sleeve 30 in rotation around the axis XX so that, in use, when the sleeve is attached around the rod 20, the aiming block is placed vertically in the vertical plane of the parts. distal branches 13 and 14 of the tensioning device 11. Advantageously, the block 43 is displaceable in translation, in the longitudinal direction of the rods 42, relative to the sleeve 30, here by sliding in the bores of the base 41.

For the presence of the block 43 does not interfere by contact or the branch 14 when the distal portion thereof is spaced from the branch 13, nor, in use, with the patella and tendon patellar, the block 43 has a lower recess 44 open downward and adapted to receive with clearance the distal portion of the branch 14. This recess 44 gives the section of the block 43, in a plane perpendicular to the rods 42, a U-shape returned downward. In the aiming block 43 are hollowed out at least one pair, here two pairs, of through holes 46 and 48 located on either side of the recess 44. The respective axes of the holes 46 extend parallel to the longitudinal direction rods 42 and thus belong to the same plane perpendicular to the axis XX when the sleeve 30 is attached to the rod 20. Similarly, the respective axes of the holes 48 extend parallel to the longitudinal direction of the rods 42 and thus belong to the same plane perpendicular to the axis XX, the plane associated with the holes 48 being located below the plane associated with the holes 46, these two planes being separated from each other by a distance d for example equal to 15 mm approx. The use of the tensioning ancillary device 10 shown in FIG. 1 will now be described with reference to FIGS. 2 to 5B, for implanting the prosthesis 1 of FIG. 9A.

After having incised the knee area of a patient to operate and considering for example that the preferred approach is antero-internally, the surgeon resects the upper end of the tibia T, for example by means of an ancillary conventional tibial cut. At the end of this preliminary step, the tibia T has, at its upper end, the resected surface T _A substantially flat, in principle substantially perpendicular to the mechanical axis of the tibia which passes through the central zone of this surface and the corresponding ankle of the patient. The lower end of the femur F is for the moment intact.

In a first step, the surgeon lodges the distal ends of the branches 13 and 14 of the device 11 within the femoro-tibial space. More specifically, as shown in FIG. 2, the lower surface 26A of the pallet 26 is resting against the resected surface T _A of the tibia T, while the finger 28 is slid in line with the inter-condylar notch F _E of the femur F. While the knee is bending at 90 ° the surgical separates the proximal portions of the branches 13 and 14 of the ancillary 1 so that the finger 28 is housed between the inner and outer condyles of the femur and it adjusts the tension of the device 11 to obtain a stable femoro-tibial distance. The device 11 of the ancillary device 10 is then in the configuration of FIG.

The surgeon then has access to the retro-condylar spaces of the joint and, if necessary, resects posterior tibial and / or femoral osteophytes and / or takes off the lateral ligaments of the flanks of the condyles and condylar shells. In the case where the surgeon visually observes that one of the retro-condylar spaces is larger than the other, which indicates that a differential ligament tensions remains on either side of the knee joint, it makes appropriate surgical corrections, including the additional removal of osteophytes and / or more extensive ligamentous detachments. Alternatively, even before using the device 11, the surgeon resects the lateral and posterior tibial and femoral osteophytes and releases the lateral ligaments and the condylar shells, then controls its intervention using the device 11. It will be noted that it is necessary to dislocate the patient's patella in order to observe the retro-condylar spaces. However, once the surgical corrections have been made, the patella can be reduced: as shown, the branches 13 and 14, between their respective distal end members 26 and 28 and the rod 20, are not rectilinear but each have a generally in U whose bottom is separated from the rest of the branch in the direction of the axis ZZ. The respective recesses of these U-shaped shapes can thus receive without contact the lower part of the patellar tendon while the patella is in place. The ligament balance is thus obtained without significant disturbance of the ligamentous environment of the knee.

Moreover, if there was, before the operation, a subluxation, generally external, of the patella of the patient, the surgeon can be brought to release posterior condylar bone material more importantly, in this case, internally externally, maintaining an equality of external and internal retro-condylar spaces. The femoral cap 3 of the prosthesis 1 subsequently implanted will then be slightly offset in rotation outward so as to be centered vis-à-vis the patella of the patient.

In a second step, once the ligament balance in flexion thus controlled, the surgeon brings the knee joint in extension, as in Figure 3, until this joint is subjected to a stress of substantially tensioning. opposed to the ligamentous tension anatomical, then he gets the ligament balance on both sides of the knee joint. In particular, the surgeon resects, if necessary, posterior osteophytes that interfere with the condylar shells of the knee. Here, the surgeon may use an extra-medullary aiming piece of the anatomical head of the femur F, reported on the ancillary 10, as explained in WO-A-2005/092205.

Optionally and not shown, the surgeon can further verify that the mechanical axis of the femur and the mechanical axis of the tibia are substantially merged by bringing back on the ancillary 10 an additional tibial aiming rod, which extends since the ancillary 10 to the patient's ankle.

As for the first operating time, once the joint is distracted, the patella is reduced during the verification of ligament balance. Thirdly, once the ligament balance in extension is thus obtained, the surgeon again brings the knee joint into bending at 90 ° and maintains the tensioning intensity of the knee substantially opposite to the ligamentous tension. anatomical. The locating device 12, which until now was not necessary to report on the device 11, is attached around the rod 20. The rod 40 is moved to extend substantially in the longitudinal extension of the femur while the sleeve 30 is displaced in translation downwards along the rod 20 until the bent portion 40a of the rod 40, thus forming a feeler, comes into contact with the anterior cortical F ₀ of the femur F, as shown 4A and 4B, where it is blocked by the screws 38 and 39. It will be noted that the bent shape of the rod 40 allows to overhang the epithelium of the femur, without being hindered by it. The sleeve 30 is then immobilized in translation along the rod 20 by means of the locking screw 35. The ancillary 10 is then in the configuration illustrated in Figures 4A and 4B. This configuration is frozen until the end of the determination of the reference planes relative to the femur, as explained below.

In this configuration, the aiming block 43 is arranged facing the front side of the femur F, more precisely horizontally opposite the distal face F ₀ of the lower epiphysis of the femur F. The surgeon then introduces the drill of a drill inside the holes 46, as indicated by the arrows F ₄₆ , so as to drill extra-medullary cavities in the bone, of respective axis noted A and a few tens of millimeters deep. The two axes A define a reference geometrical plane, which contains these two axes and which is substantially parallel to the tibial bearing surface 26A and situated, with respect to this surface 26A, at a distance K related to the adjustment of the position. translation of the sleeve 30 along the stem 20. With regard to the 90 ° flexed configuration of the knee, this reference plane corresponds to a femoral plane P _F ι_ which is indicated by its trace in FIG. 4B and which is thus, at the same time, parallel to the surface portion of the anterior cortical F ₀ of the femur F, on which the bent portion 40a of the rod 40 has been placed in contact to adjust the translational position of the sleeve 30, and substantially perpendicular to the bending ligament tension axis due to the ligament balance sought at the first operative stage and the displacement in rotation of the intercondylar notch F _E on the surface 28A of the finger 28.

Advantageously, the surgeon also introduces the drill of the drill inside the holes 48, as indicated by the arrows F ₄₈ , so as to drill two other extra-medullary cavities in the epiphysis of the femur F, of respective axis noted B parallel to the plane P _F ι_, being away from the value d. Moreover, depending on the quality of the epiphyseal bone, only two of the four extra-medullary cavities defined above can be made, being noted that two of these four cavities are sufficient to define the plane P _F ι_ arranged parallel to the surface 26A, being separated from the latter by the distance K.

In a fourth operation time, if appropriate after clearing the device 12, a first cutting block 70 is positioned on the femur F, as shown in Figures 5A and 5B. This cutting block 70 is adapted to guide a cutting blade of the femur so as to produce an anterior femoral cutting plane adapted to the anterior plane 3A _A of the multi-plane face 3A of the cap 3 to be implanted.

More specifically, this block 70 comprises a main body 72 adapted to be fixedly attached to the upper side of the sighting block 43, for example by means of an assembly screw 74. The body 72 defines a slot 76 anterior cut.

To obtain an anterior femoral cut plane properly positioned for the implantation of the prosthesis 1, the block 70 is fixed to the aiming block 43 after the latter is released from the rest of the sighting device 12 and then fixed to the femur F then that the knee is bent at 90 °. To do this, two extra-medullary pins 61 and 62 are implanted in the A-axis cavities and possibly two extra-medullary pins 63 and 64 are implanted in the cavities of axis B. The aiming block 43 is then reported on these pins, by threading in the holes 46 and 48 the parts of the pins projecting from the distal face F ₀ of the femoral epiphysis. The cutting block 70, fixedly supported by the aiming block 43, is then in the configuration shown in FIGS. 5A and 5B. In practice, at least two of the four pins 61 to 64 are thus put in place, according to the number of cavities available and the intensity required for fixing the sighting block 43. Moreover, to enhance the stability of the assembly of the block 43 on the femur, this block can advantageously remain attached to the ancillary 10 held in place.

By then introducing a cutting blade into the slot 76, the anterior face F _A of the femur F is resected along a cutting plane F _AA disposed at a distance Δ from the reference plane P, as shown in FIG. 5B.

The body 72 of the cutting block 70 has here the advantage of extending facing only one of the two inner and outer sides of the front face of the femur F, which limits the bulk. To do this, the body 72 is fixed on the upper side or, as a variant, not shown, laterally of the aiming block 43, projecting from this aiming block, in a mediolateral direction, a single of the two lateral sides of the sighting block 43, as clearly visible in FIG. 5A. This limitation of the mediolateral extent of the block 70 also makes it possible to produce the cutting plane F _AA while the kneecap is in place and / or the knee is distracted by the tensioning device 11, being Note that the latter is however not shown in Figures 5A and 5B for reasons of visibility. Under these conditions, the surgeon can perform the anterior cut of the femur F while controlling the ligamentous tension of the knee using the device 1 1, in particular to reduce the duration of the intervention because, in this case, the third and fourth operating times can be performed concomitantly. The use of the block 70 is thus faster, more precise, less invasive and less traumatic for the knee.

Of course, because of the limitation of the mediolateral dimension of the slot 76, the cutting blade is to be introduced into this slot with a lateral kinematic component, in order to produce the cutting plane F _AA on the side of the front face. the femur opposite the side of this face facing the body 72. For this purpose, the body 72 is here made in a curved overall shape, partially surrounding one of the sides, internal or external, of the front face of the femur F.

In a fifth step, the surgeon determines the size of the femoral implant adapted to the anatomy of the patient. This determination is visual or instrumental, for example by measuring the distance between the anterior cut and the posterior edge of the condyles.

In a sixth operating time, without modifying the positioning in translation of the sleeve 30 with respect to the rod 20, the feeler rod 40 is pivoted and the knee joint is extended, if necessary by relaxing and then retensioning the device 1 1 so as to tension the joint as during the second operating time. The aiming block 43 is then applied to the anterior cutting plane F _AA which ensures the orthogonality between the anterior cut and the distal cut to come.

The ancillary 10 is then in the configuration illustrated in Figures 6A and 6B.

The holes 46 and / or 48 of the sighting block 43 are then used in the same way as they were previously during the third operating time, that is to say to guide the application of the above-mentioned drill bit. so as to realize, on the front side of the femur F, more precisely in its anterior cortical F ₀ , at least two extra-medullary cavities, of respective axis C and / or D. The definition of the axes C and / or D is linked to the abovementioned reference plane: these axes C and / or D extend substantially perpendicularly to the femoral plane P _FL defined above, in other words, having regard to the extension configuration of the knee, substantially parallel to a femoral plane P _E χ which, vis-à-vis the tibia T, corresponds to the aforementioned reference plane and which, with respect to the femur F, is substantially perpendicular to both the mechanical axis of the femur and the Ligamentary tension axis in extension due to ligament balance in ex tension sought at the second operating time and displacement in rotation of the intercondylar notch F _E on the surface 28A of the finger 28.

In a seventh operation, after removing the cutting block 70, a second cutting block 80 is positioned on the femur F, as shown in Figs. 7A and 7B. This cutting block 80 is adapted, according to the implant size determined at the fifth operating time, to guide a cutting blade of the femur so as to achieve a distal femoral cutting plane adapted to the distal plane 3A _D of the face multi-plan 3A of the cap 3 to implant.

More specifically, this block 80 comprises a main body 82 adapted to be fixedly attached to one of the two lateral sides or, alternatively not shown, to the lower edge of the sighting block 43, for example using a assembly screw 84. This body 82 defines a slot 86 of distal section.

To obtain a distal femoral cutting plane suitably positioned for the implantation of the prosthesis 1, the block 80 is fixed to the aiming block 43 while the latter may or may not be clear of the rest of the sighting device 12 and is fixed to the femur F, while the knee is extended. To do this, two extra-medullary pins 65 and 66 are implanted in the C-axis cavities and two extra-medullary pins 67 and 68 are implanted in the cavities of axis D. The aiming block 43 is then attached to these pins. pins, by threading in the holes 46 and 48 the parts of the protruding pins, from the anterior femoral cutting plane F _AA - The cutting block 80, fixedly supported by the aiming block 43, is then in the configuration shown on the Figures 7A and 7B. In practice, as for the pins 61 to 64, at least two of the four pins 65 to 68 are thus put in place, as a function of the number of cavities available and the desired intensity for fixing the sighting block 43.

By then introducing a cutting blade into the slot 86, the distal face F ₀ of the femur F is resected along a cutting plane F _AD disposed at a distance Δ 'of the reference plane P, as shown in FIG. 7B. In a similar manner to the cutting block 70, the cutting block 80 has a small footprint, its body 82 extending only one side, internal or external, of the front face of the femur. In the same way as for the body 72, the body 82 does in fact extend in projection from the sighting unit 43, in a mediolateral direction, only from one of the two lateral sides of this aiming block, having an arched shape that partially surrounds the front of the femur. In the same way as for the slot 76, the slot 86 makes it possible to guide the cutting blade introduced into this slot in a movement including a lateral component.

Under these conditions, as seen before for the third and fourth operating time, the sixth and seventh operative time can be performed concomitantly, holding in place the ancillary 10.

Furthermore, the fixing position of the body 82 on one of the lateral sides of the sighting unit 43 is adjustable in the vertical direction. Here, the body 82 is provided, in its portion pressed against the sighting block 43, with several through holes 88 regularly distributed in the vertical and in each of which can be received the assembly screw 84. It is understood that, depending on the hole 88 used, the value of the distance Δ 'is changed, as immediately apparent from the observation of Figure 7B. The choice of this value of Δ 'by the surgeon is linked at the size of the femoral component 3 of the prosthesis 1 that the surgeon aims to implant, particularly according to the morphology of the patient. In addition, taking into account this information, the surgeon is able to determine the thickness of the plate 4 of the prosthesis 1 to implant: indeed, the identification, during the third and fourth operating time, the position of the sleeve 30 along the rod 20, in particular with the aid of graduations provided along this rod, gives an information representative of the distance K defined above while, as it immediately follows from FIG. 7B, the prosthetic bulkiness in FIG. extension, that is to say the value of EP ₂ , is related to the values of the distances K and Δ 'by the relation EP ₂ + Δ' = K. In other words, the surgeon is able to choose sizes for the femoral component 3 and for the tray 4 most appropriate to the patient operated in the sense that these sizes induce a prosthetic thickness substantially equal to the prosthetic space available. In an eighth operating time, after removing the cutting block 80, the sighting block 43, as well as the pins 65 to 68, a third cutting block 90 is positioned on the femur F, as shown in FIGS. 8A and 8B . This cutting block 90 is adapted to guide cutting blades of the femur so as to produce, in addition to the earlier sectional planes F 1 and of the distal section F _AD made previously, the femoral section planes adapted to the other planes as the planes previous 3A _A and distal 3A _D of the multi-plane face 3A of the femoral cap 3 to be implanted.

To this end, the cutting block 90 comprises a main body 92 generally parallelepiped, which defines: - at its end intended to be turned upwards in service, a slot 94 for checking the previous cut, as explained in detail below ,

at its end intended to be turned down in use, a slot 96 of posterior cut, and

- In its intermediate part, slots 98 and 99 chamfered cut, respectively intended to make an inclined cut from the distal section to the anterior side of the femur and an inclined cut from the distal section to the posterior side of the femur. Advantageously, the cutting slots 96 and 99 are interrupted in their central zone, which amounts to saying that each of these slots 96, 99 consists of two elementary slits 96 ₁ and 96 ₂ , 99 ₁ and 99 ₂ which are arranged in the extension from each other, being separated by a body portion 92. In this way, the aforesaid portion of the body 92 protects soft areas of the knee during use of the cutting block 90.

To properly position the cutting block 90 for the implantation of the prosthesis 1, the extra-medullary pins 61 and 62 are reimplanted in the cavities of axis A while the knee is bent at 90 °. The body 92 is then attached to these pins, by threading in through holes of this body the parts of the pins projecting from the distal cutting plane F _AD - The body 92 is then immobilized on the femur by oblique pins 100, by lateral example, threaded into complementary holes delimited laterally by the body 92, to be anchored in the lateral edges of the resected distal face of the femoral epiphysis F or in the lateral faces of the epiphysis. The cutting block 90 is then in the configuration shown in FIGS. 8A and 8B.

Before proceeding to the actual cuts, the pins 60 and 62 are advantageously removed, which does not affect the positioning of the cutting block 90 due to the presence of the lateral pins 100. The removal of the pins 61 and 62 facilitates handling subsequent cutting blades, specified below.

In practice, instead of pins 61 and 62, pins 63 and 64 which are reimplanted into the D-axis cavities can be used, provided that corresponding through holes are provided in the body 92. More generally, at least two four pins 61 to 64 are to be used to properly position the cutting block 90 on the femur.

By then introducing a cutting blade in the slot 96, the posterior face of the femoral epiphysis is resected along a cutting plane F _A p, spaced from the anterior cutting plane F _AA by a distance AP, as represented in FIG. 8B. Moreover, in the example considered here, the section planes F _AP and F _AA are parallel to each other, which is related to the fact that the posterior planes 3A _P and the front plane 3A _A of the multi-face 3A shots of the femoral cuff 3 are parallel to each other. In a variant, according to the geometrical positioning of these planes 3A _P and 3AA, the posterior sectional planes F _A p and anterior FAA may not be strictly parallel.

During the same operating time, cutting blades are also introduced into the slots 98 and 99 in order to chamfer the femoral epiphysis, respectively along an inclined cutting plane connecting the distal cutting planes.

F _AD and anterior cut F _AA , and in an inclined sectional plane connecting the distal sectional planes F _A D and posterior section F _A p.

At the end of this eighth operating time, the distance between the posterior section plane F _A p and the resected tibial surface T _A is equal to the difference between, on the one hand, the sum of the values K and Δ and, d On the other hand, the distance AP when the knee is bent at 90 ° as in Figure 9B. At the same time, with regard to the seventh operating time, the distance between the distal cutting plane F _AD and the tibial surface T _A is equal to the difference between the values K and Δ 'when the knee is in extension as in the figure 9C. Under these conditions, the prosthetic encroachments in flexion EP ₁ and in extension EP ₂ are substantially equal to each other insofar as the relation Δ + Δ '= AP is satisfied. As this relation is only related to the size of the femoral implant 3, it is easily obtained by means of a suitable dimensioning of the sighting block 43 and the cutting blocks 70, 80 and 90. In particular, by predetermining a size single for the sighting block 43 and the cutting blocks 70 and 80, it is possible to associate with each femoral implant size 3 available a corresponding size for the cutting block 90. In this way, the surgeon obtains quickly and easily the equal prosthetic congestion in flexion EPi and in extension EP ₂ . Thanks to the ancillaries according to the invention, the duration of the surgical procedure to place the knee prosthesis 1 is reduced, only one help may be sufficient next to the surgeon, while resulting in a remarkable implantation quality. Moreover, only the front side of the femur is approached during the surgical procedure, and this as well for the sighting block 43 as for the cutting blocks 70, 80 and 90, which makes the intervention less invasive and less traumatic. for the operated knee. Of course, the intervention can also be implemented by more invasive ancillaries, according to the surgical practices. Moreover, as an optional arrangement, the surgeon uses, during the eighth operating time, the slot 94 to control the anterior cutting plane F _AA - To do this, while the cutting block 90 is fixed on the femur F as in FIGS. 8A and 8B, it introduces into the slot 94 a control wafer intended to come flush with the resected front face of the femur epiphysis F. This optional control operation enables the surgeon to check the quality of the anterior cut performed at the fifth operating time and to ensure that the positioning of the cutting block 90 is suitable with respect to the previous cutting plane F _AA - The presence of the slot 94 in the cutting block 90 makes it possible to clearly understand a variant, not shown, for the realization of the ancillaries according to the invention. Indeed, rather than the cutting blocks 70 and 90 are distinct from one another as considered above, it is conceivable to integrate these two cutting blocks to one another, a single taking. This double cutting block can in particular take the form of the cutting block 90, replacing its slot 94 with an earlier cutting slot, functionally similar to the cutting slot 74. In this case, during the eighth operating time, this double block The cutter is used to make all the femoral cutting planes, including the distal cutting plane, the fourth and, if necessary, the seventh operating time described above being absent. We are talking about a "four-in-one" or even "five-in-one" cutting block.

The embodiment variant mentioned just above finds particular application in the context of a computer-assisted surgical procedure. Indeed, the ancillaries 10, 70, 80 and 90 described above are suitable for computer-assisted navigation, in the context of which the position in the space of the ancillaries as well as the femur F and the tibia T is identified and analyzed. in real time by computer means. As an example of the implementation of such a computer-assisted navigation, it can be considered that the above-mentioned computer means locate in space the resected tibial surface T _A and, on the basis of this information, locate the implantation in the femur of the various pins 61 to 68, then used to position the femur cutting blocks, such as the cutting blocks 70, 80 and 90, as well as the cutting blocks "four in one" and "five in one" Mentioned above. Another variant is to use the cutting block 80 to determine the size of the implant, and then perform the posterior cut at the end of the fifth operating time. The knee is then extended until the aiming block is applied to the anterior cut and the distal cut is made through the slot 86 of the block 80. The chamfer cutter block 90 is then reduced to anterior size. posterior, comprising only the slots 98 and 99, which makes it more suitable for a minimal approach.

In Figure 10 is shown a variant of the voltage setting device 11 described so far, referenced 11 '. This device 11 'is designed to support the tracking device 12, in the same way that the latter is supported by the device 11. However, the device 11' differs from the device 11 essentially by its arrangements for distracting the articulation of knee between the femur F and the tibia T. Indeed, as shown in Figures 10 and 11, the device 11 'comprises two elongate legs 13' and 14 'which are slidably mounted one along the other . More specifically, the branch 13 'includes a tubular proximal portion within which the proximal portion of the limb 14' moves. This proximal part of the limb 14 'includes, on the one hand, a threaded rod 14'i screwed through the proximal end of the limb 13', and, on the other hand, a compression spring 14 ' ₂ , interposed between the distal end of the threaded rod 14'i and the proximal end of a rigid distal portion 14 ' ₃ of the branch 14'. When the rod 14'i is rotated on itself about its longitudinal axis, the distal portion 14 ' ₃ is driven in translation along the aforementioned axis relative to the branch 13' within the elastic limits of the interposed spring 14 ' ₂ . The compression system, here the spring 14 ' ₂ , may alternatively be different, for example pneumatic or fluidic.

At its distal end, the branch 13 'is rigidly secured to a metal pallet 26' similar to the pallet 26 of the branch 13. The pallet 26 'defines in particular a flat lower face 26'A which is similar to the face 26A and which is adapted to bear against the resected T _A surface of the tibia T, as shown in FIG. 11.

At its distal end, the branch 14 'is provided with a rigid finger 28' connected to the remainder of the branch 14 'by a scissors mechanism 29': the distal end of the portion 14 ' ₃ of the branch 14' is articulated to the base of the mechanism 29 'so that, when this branch portion 14' is translated in the longitudinal direction of the branch 14 ', the mechanism 29' is deployed or s 'retracts on itself so as to move the finger 28' in a translational movement perpendicular to the face 26'A. In practice, the finger 28 'has a geometry similar to that of the finger 28, in particular in order to be housed in the inter-condylar notch F _E of the femur F, as shown in FIG. 11.

In addition, in its middle part, the branch 13 'is rigidly secured to a rod 20' similar to the rod 20 described above, around which the marking device 12 can be removably attached.

In use, the tensioning device 11 'is functionally similar to the device 11: by relative movement of the branches 13' and 14 ', namely by relative sliding, the spacing between the pallet 26' and the finger 28 'makes it possible to distract the femur F and the tibia T during the implementation of the first, second, third, fourth, fifth, sixth and seventh stages of operation described above, as illustrated for the fourth operating time by Figure 11 on which are visible the locating device 12, with its sleeve 30 and its palpating rod 40, the aiming block 43 and the anterior cutting block 70 fixed on the aiming block 43. Moreover, although the ancillaries described above were used in order to implant the prosthesis 1 with movable plate, these ancillaries are of course usable for implanting a knee prosthesis devoid of such a movable plate.

Various arrangements and variants ancillaries described above are also possible. For this purpose, the reader may in particular refer to WO-A-2005/092205. In addition, as other possible options:

rather than locating the positioning of the aiming block 43 along the stem 20 with respect to the anterior cortex F _c of the femur F, in particular by palpation of this cortex with the aid of the stem 40, an anatomically positioning reference the opposing block may be considered, that is to say that the sighting block 43 may be associated with means for locating its positioning relative to the posterior condyles or to the distal condyles of the femur F, these two pairs of condyles occupying similar positions with respect to the tibia T depending on whether the knee is flexed or extended;

the feeler can be attached to the sighting block 43; this probe can in particular be removably attached, to identify the reference or the reference posterior or distal, as mentioned just above;

the cutter block 90 and the "four in one" and "five in one" blocks mentioned above may include a blade guiding device in order to resect the excess of posterior, anterior or distal cut vis-à-vis the the relative angulation of the sections specific to the femoral implant to be applied; if it is decided not to maintain the presence of the ancillary 10 during the fourth and / or the seventh time, the block 70 and / or the block 80 may be positioned before the aiming block 43; and or

the block 90 may, like the blocks 70 and 80, be adapted to be positioned laterally to the femur, in particular by having a shape adapted to the anterior and distal cuts.

Claims

A set of ancillaries (10, 70, 80, 90) for implanting a knee prosthesis (1), including, inter alia, an ancillary (10) for tensioning the knee, which comprises:

two branches (13, 14; 13 ', 14') movable relative to one another and respectively provided, at their distal end, with tibial support means (26) defining a tibial bearing surface ( 26A; 26'A) substantially planar, and femoral bearing means (28; 28 '), - a device (12) for locating, on the front side of the femur (F), implantation in the femur of pins extramedullary (61, 62, 63, 64, 65, 66, 67, 68) in respective directions (A, B, C, D) defining a reference geometrical plane (PFL / PEX) substantially parallel to the surface plane of tibial support (26A) and located at an adjustable distance (K) from this tibial bearing surface, and

first (70), second (80) and third (90) femoral cutting ancillaries, which are respectively provided with an anterior cutting slot (76), a distal cutting slot (86) and a posterior cut slot (96), the first and third femoral cutting abutments (70, 90) being adapted to be positioned relative to the femur by cooperating with portions, projecting from the front side of the femur, of pins (61, 62). , 63, 64) implanted in the femur in respective directions (A, B) which are marked by the locating device (12) when the knee is bent at 90 ° while the upright of the second femoral cutting tool (80) is adapted to be positioned relative to the femur by cooperating with portions, projecting from the front side of the femur, of pins (65, 66, 67, 68) implanted in the femur in respective directions (C, D) which are marked by the tracking device when the knee is in extension, characterized characterized in that the locating device (12) comprises a block (43) for extra-medullary targeting of the pin implantation directions (A, B, C, D) (61, 62, 63, 64, 65, 66 , 67, 68), which is adapted to be worn by the rest of the tensioning ancillary (10) and on which the first (70) and / or the second (80) femoral cutting ancillary are adapted to be set.

2. Set of ancillary according to claim 1, characterized in that the aiming block (43) is adapted to be removably carried by the rest of the tensioning ancillary (10).

3. Ancillary set according to one of claims 1 or 2, characterized in that the first (70) and / or the second (80) femoral cutting ancillary are adapted to be fixed on the aiming block (43) protruding from this aiming block, in a mediolateral direction, only one of the two lateral sides of the aiming block.

An ancillary assembly according to claim 3, characterized in that the anterior cutting slot (76) and / or the distal (86) and / or posterior cutting slot are shaped to guide a cutting blade inserted into this slot following a motion including a lateral component.

5. set of ancillaries according to any one of the preceding claims, characterized in that the first (70) and third (90) femoral cutting ancillaries are distinct from each other.

An ancillary assembly according to claim 5, characterized in that the third femoral cutting abutment (90) is provided with an anterior cutting verification slot (94) adapted to control an anterior cutting plane (F _AA ) of the femur (F) previously made by the anterior cutting slit (76) of the first femoral cutting ancillary (70).

An ancillary set according to any one of claims 1 to 4, characterized in that the first (70) and third (90) femoral cutting ancillaries are integral with each other in one piece, in the form of a double ancillary cup.

8. set of ancillaries according to claim 7, characterized in that said double cutting aid is adapted to be also used as a replacement for the second cutting ancillary (80).

9. set of ancillaries according to any preceding claim, characterized in that the two branches (13, 14) of the tensioning ancillary (10) are articulated in rotation relative to the another around an axis of articulation (ZZ) substantially perpendicular to the longitudinal direction of the branches, and in that the femoral bearing means comprise a finger (28) rigidly connected with the rest of the corresponding branch (14).

10. Set of ancillaries according to any one of claims 1 to 8, characterized in that the two legs (13 ', 14') of the tensioning ancillary (10) are mounted relative to sliding relative to each other. along the other, and in that the femoral bearing means comprise a finger (28 ') connected to the rest of the corresponding branch (14') by a scissors mechanism (29 ') adapted to move this finger according to a translational movement perpendicular to the tibial bearing surface (26'A) under the action of sliding between the branches.

11. Set of ancillaries according to any one of the preceding claims, characterized in that the aiming block (43) delimits holes (46, 48) for extra-medullary guidance of the pins (61, 62, 63, 64, 65, 66, 67, 68) and means, such as a drill, for digging pin receiving cavities.

12. Set of ancillaries according to any one of the preceding claims, characterized in that the tensioning ancillary (10) further comprises a rod (20; 20 '), which is integral with the branch (13; 13 ') provided with tibial bearing means (26; 26') and which extends in length in a direction (X-X) substantially perpendicular to the plane containing the flat tibial bearing surface (26A; 26'A) and in that the target block (43) is, in use, mechanically connected to the shaft so that the sight block is disposed on the same side of the shaft as the distal portions of the branches (13, 14). ', 14').

Ancillary unit according to Claim 12, characterized in that the aiming block (43) is displaceable relative to the rod (20; 20 ') in translation along the longitudinal direction (XX) of this rod, and the marking device (12) comprises means for adjusting (40) and blocking (35) the position of the aiming block along the rod.

14. set of ancillaries according to claim 13, characterized in that the adjusting means (40) are adapted to locate the positioning of the target block (43) relative to the anterior cortex (F ₀ ) of the femur (F) , especially by palpating this cortex.

15. Set of ancillaries according to claim 13, characterized in that the adjusting means are adapted to locate the positioning of the aiming block (43) relative to the posterior condyles or the distal condyles of the femur (F).

16. A method of placing a knee prosthesis, which, after resection of the upper end of the tibia, comprises steps during which:

- By means of an ancillary tensioning, the knee joint is distracted by bending at 90 ° and then the ligament tension between the inner and outer sides of the knee is balanced, in particular by visual comparison of the retro-condylar spaces. internal and external ;

- By means of the same tensioning instrument, the knee joint is distracted in extension and the ligament tension is then balanced between the inner and outer sides of the knee, in particular by using an extra-medullary aiming piece of the femoral head. , reported on this ancillary of tensioning;

- Thanks to a tracking device carried by the ancillary tensioning and while this ancillary tension of the knee in flexion after ligament balance, is located on the front side of the femur, the implementation of a first series extramedullary pins, in respective directions defining a reference geometric plane both substantially parallel to the tibial resection plane and located at a given distance from this surface, adjusted from the position of the anterior femoral cortex;

- An anterior section of the femur is made using an ancillary section positioned on the femur by cooperation with a portion, projecting from the front side of the femur, the pins of said first series;

the size of the femoral implant of the knee prosthesis to be implanted is chosen;

- Thanks to the same tracking device worn by the ancillary and while this ancillary tension in the knee extension after its ligament balancing, is located on the front side of the femur, the implantation of a second series of pins extra- medullaries, following directions parallel to said reference plane;

depending on the size of the femoral implant of the knee prosthesis to be implanted, a distal cut of the femur is made using the same cutting aid as that used to make the anterior cut or using another ancillary section, positioned on the femur by cooperation with a portion, projecting from the front side of the femur, the pins of said second series; and also depending on the size of the femoral implant, a posterior cut of the femur is made, and, if appropriate, one or more chamfers, using the same cutting aid as that used to make the anterior cut or using at least one other ancillary cutting, positioned on the femur by cooperation with a portion, projecting from the front side of the femur, pins of said first series.