Cutting guide device for cutting the distal end of the femur prior to total knee replacement, and method for manufacturing at least a part of said device

Abstract

Cutting guide device for cutting the distal end of the femur prior to knee replacement and method for manufacturing at least a part of said device. The invention relates to a cutting guide device (1) for the distal end (21) of the femur (2), said device (1) comprising a first (3) and a second part (4) that can be assembled to define a cutting plane for said end (21). Said second part has a slot (5) for a blade and means for cooperating with said first part, which includes a plate (8) constituting a support surface tangent to the femoral condyles, provided with a guide pin (9) for a point, said first part having means (14) for securing the second (4) to the first (3) such that the parts are in perpendicular planes and the slot is oriented perpendicular to the femoral mechanical axis KH. Fig. 3

Description

Title of the invention: Cutting guide device for cutting the distal end of the femur bone prior to the installation of a total knee prosthesis, and method of manufacturing at least a part of said device

[0001] The present invention relates to the general field of the fitting of orthopedic prostheses at the knee level, also referred to as total knee arthroplasty.

[0002] The invention relates, more particularly, to an instrument for guiding a distal femoral cut, this cut being carried out prior to the fitting of a prosthesis, said cut being specifically adapted to patients, and based on standard radiographs.

[0003] The invention also relates to a method for manufacturing said guiding instrument using only standard two-dimensional radiographs.

[0004] A knee arthroplasty consists of a surgical operation aimed at replacing, either partially (partial arthroplasty) or totally (total arthroplasty), the damaged articular surfaces of the knee.

[0005] Such a surgical operation is generally indicated in cases of osteoarthritis of the knee, which results in degeneration of the cartilage present in the knee. Osteoarthritis causes significant pain and, when drug treatments no longer have an effect, the installation of a partial or total prosthesis becomes necessary.

[0006] In a schematic and simplified manner, a complete knee prosthesis is traditionally made up of a plurality of parts.

[0007] On the one hand, such a prosthesis comprises two metal implants, in particular made of CrCo alloy. The first metal implant consists of a tibial prosthesis, positioned at the upper end of the tibia, and the second implant consists of a femoral prosthesis, positioned at the lower end of the femur.

[0008] An intermediate part separates the two metal implants mentioned above, and consists of a plastic insert, particularly polyethylene, which is articulated between the femur and the tibia, allowing the prosthesis to slide correctly.

[0009] The two metal implants must be placed at the femoral and tibial level so as to have an axis of 180°, and therefore an alignment between the mechanical axis of the femur and the mechanical axis of the tibia.

[0010] For this purpose, a tibial cut is made at the time of fitting the prosthesis. proximal, also called resection, and a distal femoral cut resulting in a balanced knee in extension, with or without ligament release.

[0011] Then, the anteroposterior femoral cuts are made taking into account the femoral rotation. The patellar preparation is then carried out and, finally, the tibial preparation.

[0012] Thus, the femoral cut consists more particularly of making five cuts corresponding to the five faces that comprise the concave profile of the femoral prosthesis part.

[0013] One of these five cuts, called the “femoral distal cut”, must be absolutely perpendicular to the mechanical axis of the extended leg, at an angle of 180° (plus or minus 3°), relative to a straight line hip-knee-ankle (HKA for “Hip-Knee-Ankle”).

[0014] Otherwise, a significant deviation of the limb increases the risks of premature wear of the intermediate polyethylene prosthesis part, and can be a source of pain for the patient.

[0015] Therefore, planning the bone cuts is a crucial step. Indeed, the orientation of the cutting planes must be optimal to obtain a normal-axis, stable and mobile joint.

[0016] Conventionally, this planning is carried out on the basis of standard codified radiographs, carried out preoperatively, this planning being associated with conventional mechanical installation instrumentation.

[0017] This instrumentation used during the intervention is composed in particular of a centromedullary aiming device, essentially in the form of a rod, which is inserted into the medullary canal of the femur, in order to orient the distal femoral cut. A cutting guide is temporarily fixed to the end of the centromedullary aiming device, in order to transfer the cutting angle which was previously measured by the radiographs.

[0018] Thus, from European patent EP 0 315 338, we know a surgical instrument suitable for use in total knee arthroplasty.

[0019] Such an instrument comprises a rod designed to be inserted into the medullary canal of a bone to be cut, in particular the femur, and means for locking said rod in a desired position inside the bone. A guide means for positioning a device for implementing bone cutting in a desired position and a means for locking said guide means relative to the rod are also provided.

[0020] In this instrument, the guide means can cooperate with the rod to support the bone cutting device to allow free rotation of the guide means and the cutting implementing device about the longitudinal axis of the rod.

[0021] That being said, this technique, based on the use of an instrument to be inserted into the Bone canal, although highly developed for cutting the femur for knee replacement, is particularly invasive. Therefore, such a technique is not suitable for all patients.

[0022] In particular, such a rod for centromedullary aiming cannot be used in the case of knee surgery to be performed on a patient already wearing a hip prosthesis with a long femoral rod, or even orthopedic nails, but also in the case of a very curved femur.

[0023] Currently, there are certain alternatives to the use of mechanical ancillaries of the centromedullary aiming type as mentioned above.

[0024] The first of these alternatives is computer-assisted navigation, with or without imaging, which makes it possible to determine the different axis parameters of the lower limb, thanks to an optical localization system.

[0025] In the case of assisted navigation without imaging, sensors are placed on the tibia and femur to create a reference. A probe then makes it possible to locate bone landmarks in space, which results in an acquisition of femoral and tibial morphology.

[0026] Cutting guides can then be positioned.

[0027] Computer-assisted navigation advantageously allows control, throughout the intervention, of the mechanical axis and the orientation of the bone cuts. The positioning of the prosthesis implants is therefore improved in the frontal and sagittal planes.

[0028] The main disadvantage of this technique lies in the fact that the operating time is significantly increased, in particular during the surgeon's training period.

[0029] Furthermore, the rotational placement of the femoral part is not significantly improved compared to conventional surgery, and the equipment required for navigation presents a substantial cost, adding to the additional cost already incurred due to the longer duration of the intervention.

[0030] In an attempt to overcome, at least in part, these drawbacks, personalized cutting guides have been proposed for several years, which are developed from CT or MRI sections of the patient to be operated on.

[0031] Such imaging makes it possible, from a plurality of 2D images and by means of ad hoc software, to create a virtual three-dimensional reproduction of the bone surfaces and thus to obtain a cutting guide adapted specifically to the patient, produced by rapid prototyping and additive manufacturing.

[0032] The positioning of the prosthesis implants is thus optimized in the three planes of space, particularly in rotation, while limiting the aggressiveness of the surgical intervention, the integrity of the femoral intramedullary canal being preserved.

[0033] However, such custom cutting guides must necessarily be made by prosthesis manufacturers, and are therefore only suitable for their products.

[0034] Furthermore, since these guides are, by definition, personalized, they cannot be reused for other surgical operations; they are therefore more expensive than mechanical ancillaries which can be reused for several interventions.

[0035] It is also appropriate to add to the cost of these guides the cost relating to the performance of the imaging, MRI or scanner, which is higher than that of a standard radiograph, such imaging being essential for the acquisition of bone morphology prior to the manufacture of said guides.

[0036] Furthermore, the manufacturing times for these custom cutting guides can be relatively long, generally on the order of several weeks.

[0037] Consequently, many orthopedic surgeons continue to perform knee prosthesis placements using conventional mechanical instrumentation, combining the performance of standard preoperative radiographs with the use of femoral intramedullary aiming, despite the disadvantages of such instrumentation.

[0038] The present invention is intended to be able to remedy, at least in part, the drawbacks of the devices and methods known in the state of the art for making a distal femoral cut with a view to fitting a knee prosthesis.

[0039] To this end, the present invention relates to inexpensive instrumentation, while being specifically adapted to a patient, easier and faster to implement than current techniques, and capable of being carried out directly in the orthopedic surgery department, without necessarily requiring the intervention of an external manufacturer.

[0040] Thus, more particularly, the present invention relates to a cutting guide device for cutting the distal end of the femur bone prior to fitting a knee prosthesis, said cutting guide device comprising a first single-piece part and a second single-piece part which can be assembled together to define a cutting plane of said distal end of the femur.

[0041] Said device is characterized by the fact that said second single-piece part consists of a metal blade guide which comprises a means for passing the blade of a saw, at least two bores designed to each receive a pin for fixing and immobilizing said second single-piece part to the femur, and means for cooperating with said first single-piece part, the latter consisting of a means for positioning said blade guide and comprising a rectangular plate constituting a bearing surface tangent T to the femoral condyles, said rectangular plate being provided, substantially in its center, with a central tubular stud for guiding a point square protruding from the surface of the plate opposite that of support for the condyles, said rectangular plate further comprising at least two bores designed to each receive a pin for fixing said first single-piece part to the femur, said first part also comprising means for securing the second to the first so that, on the one hand, said second and said first are in perpendicular planes and, on the other hand, said securing means are configured so that said blade passage means is oriented perpendicular to the femoral mechanical axis KH.

[0042] According to particular embodiments:

[0043] - said first single-piece part is made to measure so that the central stud tubular guide either coaxial with the femoral diaphyseal axis KS;

[0044] - the means for securing the second part to the first part, which comprises said first part, consist of a rail projecting from the surface of the rectangular condyle support plate, said rail being in a plane perpendicular to the plane of the plate and being inclined so as to allow orientation of the blade passage means perpendicular to the femoral mechanical axis KH;

[0045] - said rail is part of an inverted L-shaped foot surmounting said rectangular plate, said inverted L-shaped foot being coaxial with the femoral mechanical axis KH;

[0046] - said rail comprises a plurality of graduation notches defining the thickness of cut of the bone to be made;

[0047] - said rail which comprises said first part cooperates by sliding with a slide that said second part comprises so that said means for securing said second part to said first part constitute the reversible means of cooperation of said second to said first, said means for passing the blade of a saw consists of a slot.

[0048] The present invention also relates to a method of manufacturing, to measure, a first single-piece part of a cutting guide device for cutting the distal end of a patient's femur, the characteristics of said part having been described previously.

[0049] Said manufacturing method more particularly comprises at least the following steps:

[0050] - At least one X-ray of said femur is taken at the level of which the cut distal femoral must be performed, said radiograph consisting of a frontal radiograph of said femur;

[0051] - On the basis of said radiography carried out in the previous step, it is determined at less the following physiological data relating to the patient: - the HKS angle between the anatomical diaphyseal femoral axis (KS) and the mechanical femoral axis (KH), - the angle a between the diaphyseal femoral axis (KS) and the tangent (T or OSAFD - Orientation of the Distal Femoral Articular Surface) to the femoral condyles (22, 23),

[0052] - We determine, taking into account the physiological data previously determined completed, the plans of said first single-piece part of the cutting guide device by means of suitable software, so that said stud forms an angle equal to a with the plane of the rectangular plate of said part and that said rail, positioned in a plane perpendicular to the plane of the plate, is inclined relative to said plane of the plate by an angle equal to a-HKS, so as to be coaxial with the femoral mechanical axis KH once said part is positioned;

[0053] - Said first single-piece part of the cutting device is manufactured by manufacturing additive, in particular by laser sintering, using a 3D printer.

[0054] In a particular embodiment of the method for manufacturing a first single-piece part, on the front radiograph of said femur, in addition to the HKS angle and the angle α, at least the following physiological data is determined:

[0055] - the distance x corresponding to the distance between the most prominent point of the femoral condyles relative to the mechanical femoral axis (KH).

[0056] Most preferably, in the method for manufacturing a first single-piece part of the invention, in addition to the front X-ray of said femur, during the first step of the method, a second profile X-ray of said femur is taken, and in that, on the basis of said profile X-ray, at least the following physiological data are determined:

[0057] - the height d on the profile radiograph of the femur, d corresponding to the distance between the anterior cortex and the diaphyseal axis AD, and

[0058] - the distance y, corresponding to the distance between the most prominent point of the femoral condyles and the femoral diaphyseal axis AD in profile.

[0059] Advantageously, said first single-piece part of the cutting device is manufactured from a material chosen from ABS (acrylonitrile butadiene styrene), PA 12 (Polyamide), POM (polyoxymethylene), PC (polycarbonate), PEEK (polyether ether ketone).

[0060] Other aims and advantages of the present invention will appear during the description which follows relating to embodiments which are given only as indicative and non-limiting examples.

[0061] Understanding of this description will be facilitated by referring to the attached drawings in which:

[0062] [Fig.l] schematically represents, on the left, the articulation between the femur and the bones of the proximal part of the leg, tibia and fibula, with the angle a between the tangent T to the femoral condyles (or OSAFD for Orientation Surface Articulaire Femorale Distal) and the femoral anatomical axis, or femoral diaphyseal axis, KS, also represented, as well as the HKS angle in the illustration on the right, which symbolizes the divergence between the anatomical axis KS and the mechanical axis KH of the femur;

[0063] [Fig.2] represents, schematically, and seen from above, a particular embodiment of a part of the device for cutting the distal end of the femur in accordance with the present invention, in this case the first single-piece part, assemblable to a second single-piece part not shown in this figure, said first part being custom-made and being positioned, through a bearing surface which it comprises, according to the tangent T to the femoral condyles;

[0064] [Fig.3] schematically represents a sectional view in the sagittal plane, of an embodiment of the cutting guide device comprising a first single-piece part similar to that shown in [Fig.l], assembled with a second single-piece part through suitable means, the point of passage of the blade that a bone cutting device comprises also being shown, thus illustrating the portion of the bone to be cut;

[0065] [Fig.4] schematically represents two perspective views of a particular embodiment of a part of the cutting guide device according to the present invention, in this case the first single-piece part of said device which is intended to be made to measure;

[0066] [Fig.5] is a photograph in which the two parts are visible, once assembled together by sliding the second part on an element of the first part, making up the cutting guide device according to the invention, said two parts visible in the photograph having been obtained by implementing an additive manufacturing method using a 3D printer operating on the molten material deposition method, the latter consisting of ABS polymer (acrylonitrile butadiene styrene);

[0067] [Fig.6] represents, schematically and in perspective, a particular embodiment of a cutting guide device according to the invention, the two parts of the latter being assembled, reversibly, at the level of a femur whose distal end is to be cut;

[0068] [Fig.7] comprises four radiographs of a femur on which are represented the physiological data, angles and distances, which can be determined at the time of the manufacturing process of the first part of the cutting guide device according to the invention.

[0069] The purpose of the cutting guide device 1 according to the present invention is to allow optimal determination of the cutting plane of the distal end 21 of a femur bone 2, such a distal femoral cut having to be carried out, as well as other cuts, prior to the fitting of a prosthesis in a patient suffering from osteoarthritis. knee level.

[0070] The femoral cuts, like the tibial cuts, aim to embed the prosthesis in the bone while respecting the patient's anatomy as much as possible.

[0071] To achieve this objective, it is necessary for the distal femoral cut to be perfectly orthogonal, in other words perpendicular, to the mechanical axis of the femur bone, this axis corresponding to the KH axis (“Knee-Hip” axis) which is represented, in particular on the right-hand part of [Fig.l] of the attached drawings.

[0072] By respecting this perpendicularity prescription at the time of the distal femoral cut, it is possible to ensure alignment between the femoral mechanical axis and the tibial axis, i.e. an HKA angle (“Hip-Knee-Ankle”, not shown in the figures) equal to 180°.

[0073] It is, therefore, essential to determine at least the orientation of the mechanical axis KH of the femur, and to transfer, as precisely as possible, this orientation to a cutting guide device in order to be able to make a cut perpendicular to this femoral mechanical axis KH.

[0074] With reference to the figures of the attached drawings, in particular figures 2 to 6, and in a particularly advantageous manner, it has been chosen, in the cutting guide device 1 according to the present invention, which comprises two parts which can be assembled together, to transfer the orientation by means of only one of the two parts of said device 1 of the cutting guide, the latter then being custom-made taking into account the anatomical bone characteristics of the patient to be treated.

[0075] Furthermore, the transfer of this orientation of the femoral mechanical axis KH is carried out, essentially, in connection with a reference plane constituted here, in a manner specific to the invention, by the tangent T (also called OSAFD - "Orientation Surface Articular Femoral Distale") to the condyles 22, 23 of the femur bone 2, or condylar tangent T. Indeed, on these condyles 22, 23, more particularly along the tangent T to them, at least part of the cutting guide device 1 according to the invention rests.

[0076] The present invention therefore relates, according to a first aspect, to a cutting guide device 1 for cutting, along a plane perpendicular to the mechanical axis KH of the femur 2, a part of the bone, and more specifically the distal end 21 of the femur 2.

[0077] The present cutting device 1 according to the invention is constituted, for this purpose, of a first single-piece part 3 and a second single-piece part 4.

[0078] Said first single-piece part 3 and said second single-piece part 4 are assemblable, one to the other, so as to define, in an optimal manner, the cutting plane of the distal end 21 of the femur 22, this cutting plane necessarily being orthogonal to the femoral mechanical axis KH.

[0079] In the cutting guide device 1 according to the invention, the second single-piece part 4, preferably a metal part, will constitute the “blade guide” element for carrying out the distal femoral cut in question.

[0080] For this purpose, said second single-piece part 4 of the device 1 comprises a means 5 for passing a motorized oscillating saw blade.

[0081] Such a passage means 5 is preferably in the form of a slot 5, the width of which is adapted to the thickness of the saw blade used to carry out the resection, while its height is sufficient to guarantee the guidance of the blade.

[0082] Furthermore, the second part 4 comprises at least two bores 61, 62, preferably four bores 61, 62, 63, 64, as shown in the attached figures 5 and 6.

[0083] Each of these bores 61, 62, 63, 64 is designed to allow the passage of a pin for fixing and immobilizing said second part 4 at the level of the femur bone 2.

[0084] In [Fig. 3] of the drawings are shown two fixing and immobilization pins 71, 72 of the second part 4 to the femur 2, each passing through a bore, respectively 61, 62, formed at the level of said second part 4.

[0085] It should also be noted that said second single-piece part 4 of the device 1 of the invention comprises means of cooperation with the first single-piece part 3, the latter then constituting, more particularly, a means of positioning the blade guide represented by the second part 4.

[0086] This first single-piece part 3 comprises, more specifically, a plate 8, preferably of rectangular shape, as visible in the attached figures.

[0087] This plate 8 will constitute, at least in part, a support surface T tangent to the femoral condyles 22, 23 for the first part 3 of the device 1.

[0088] The rectangular plate 8 comprises, substantially in its center, a tubular central stud 9. This allows the guidance of a square tip, not shown in the figures, and not forming part of the cutting guide device 1 of the invention.

[0089] The function and interest of the square tip will be described in more detail later in this description.

[0090] To return now to the central tubular guide stud 9, this more particularly projects from one of the two surfaces of the rectangular plate 8 of the first single-piece part 3, in this case the surface 82 of the plate which is opposite the bearing surface 81 on the femoral condyles 22, 23.

[0091] In addition to said central tubular guide stud 9, said rectangular plate 8 is also provided with at least two bores 10, 11, for the passage, inside each, of a pin 12, 13 for fixing and immobilizing said first part. monobloc 3 to the femur bone 2.

[0092] Such an embodiment is notably shown in the attached [Fig.2]. However, it should not be considered as limiting the present invention. Indeed, as illustrated in [Fig.6], four bores can for example pass through the rectangular plate 8.

[0093] The first single-piece part 3 of the cutting guide device 1 according to the invention also comprises means for securing the second part 4 to said first part 3.

[0094] These means for securing one to the other part constituting the cutting guide device 1 must be designed to ensure that, on the one hand, said second single-piece part 4 and said first single-piece part 3 are positioned in perpendicular planes, and, on the other hand, that the blade passage means, in this case the slot 5, is oriented perpendicular to the femoral mechanical axis KH.

[0095] By means of the cutting guide device 1 having such characteristics, the cutting plane of the distal femoral end is defined by means of the slot 5 that the second part 4 (blade guide) has, positioned on the bone 2 by means of the first single-piece part 3 (blade guide positioner, or template), so that said cutting plane is perfectly perpendicular to the mechanical axis KH of the femur 2. This is illustrated in particular in the attached [Fig. 3], the axis KS being shown in profile (diaphyseal axis AD), as is the portion 24 of the femur 2 which must, finally, be eliminated after cutting with a view to fitting a prosthesis.

[0096] More particularly, in the cutting guide device 1 of the invention, the plate 8 of the first part 3 serves as a fixed support point on the condylar tangent T, while the connecting elements (means of securing and / or cooperation) between said first part 3 and the second part 4 that said device 1 comprises are advantageously configured so as to allow an angular correction of the positioning of said second part 4, relative to the condylar tangent T taken as a reference.

[0097] The correction of the angular positioning of said second part 4, at the level of which the means 5 for passing the saw blade is arranged, makes it possible to ensure that the cutting plane of the bone 2 is orthogonal to KH.

[0098] According to a preferred embodiment of the cutting guide device 1 according to the present invention, said first monobloc part 3 is made to measure and is specifically adapted to the patient who must undergo the distal femoral cut, prior to the fitting of his prosthesis, while the second monobloc part 4, which cooperates with said first part 3, is a standard part which can be reused for the production of other distal femoral cuts, to be carried out on other patients. It will then be necessary to comply with hygiene regulations, in particular the need to sterilize this second part 4 between two uses.

[0099] Thus, by means of the present cutting guide 1, it is advantageous to partially overcome the bone morphology as a whole, while the cutting guide 1 still remains personalized, based solely on certain key physiological data of the patient's femur 2, in particular the orientation of the femoral mechanical axis KH relative to the condylar tangent T, and, possibly, the angle HKS which measures the divergence between said mechanical axis HK and the anatomical axis KS and the angle a between the tangent to the condyles (T or OSAFD) and the femoral anatomical axis KS.

[0100] Indeed, when said first single-piece part 3 is custom-made, it is particularly advantageous that the central tubular guide stud 9 of the square tip, with which the plate 8 is provided substantially in its center, has an orientation along the anatomical diaphyseal axis KS of the femur 2, so that the measurement of the angle a constitutes a particularly interesting characteristic to know.

[0101] In other words, the central tubular guide stud 9 of the square tip materializes here, at the level of the plate of the first part, the anatomical diaphyseal axis KS of the femur 2.

[0102] The axial orientation of the central tubular guide stud 9, relative to the plane of the rectangular plate 8, consequently has an angle equal to the angle a between the tangent T and the axis KS.

[0103] Such an embodiment is shown in the attached figures 2, 3 and 6.

[0104] Thus, the square tip will be inserted into the central tubular guide stud 9 in an orientation coaxial with the anatomical diaphyseal axis KS.

[0105] This will allow optimized positioning and stabilization of the first single-piece part 3 of the device 1 at the level of the condylar tangent T, by following, in the central stud 9, the path of the diaphyseal axis KS, prior to the introduction of the pins 12, 13 into the bores 10, 11 and the securing of said part 3 on the bone 2 by means of the pins 12, 13, without however penetrating the bone medullary canal.

[0106] That being said, such an embodiment, in which the first single-piece part 3 of the device 1 is made to measure, although particularly preferential, should not be considered as being limiting of the invention.

[0107] It is indeed entirely conceivable that the second part 4 that comprises said device 1 is made to measure, while the first single-piece part 3 consists of a standard part capable of being reused for different resection operations.

[0108] In this case, the angular correction with respect to the condylar tangent T, so that the cutting plane of the distal end 21 of the femur 2 is perpendicular to the femoral mechanical axis KH, can be provided by an inclination of the means of passage 5 of blade relative to the general axis of blade guide 4.

[0109] This alternative, although conceivable, is however not shown in the figures of the attached drawings.

[0110] To return, now, to the securing means that comprise the first single-piece part 3 of the cutting guide device 1, for securing said first 3 to the second single-piece part 4, these advantageously comprise at least one rail 14.

[0111] This protrudes more particularly from the surface 81 of the rectangular plate 8 serving as a support on the femoral condyles 22, 23.

[0112] This rail 14 is advantageously located in a plane which is perpendicular to the plane of the rectangular plate 8.

[0113] Furthermore, considering the embodiment in which said first part 3 is custom-made, said rail 14 is most preferably inclined so as to allow orientation of the passage means 5 of the saw blade perpendicular to the mechanical axis KH of the femur 2.

[0114] According to a particularly interesting embodiment of the cutting guide device 1 of the invention, which is that shown in the attached figures 2 to 6, the rail 14 is part of an inverted L-shaped foot 15, which comes to surmount the rectangular plate 8.

[0115] In this case, the entire inverted L-shaped foot 15 is oriented such that the rail 14 is coaxial with the femoral mechanical axis KH.

[0116] Most preferably, a plurality of graduation notches 141, 142, 143, 144 are provided on the upper surface of the rail 14.

[0117] These graduation notches 141, 142, 143, 144 on the securing means, in this case the rail 14, make it possible to define, when securing the second single-piece part 4 to the first 3, the thickness of the distal femoral cut to be made, this generally being between 8 and 12 mm.

[0118] In this regard, it should be noted that the attachment of the second single-piece part 4 to the first 3 is reversible.

[0119] Indeed, most preferably, once the blade guide 4, or second part of the device 1, is positioned on the femur 2 and secured to it through the pins 71, 72, the blade guide positioner 3 is removed, prior to the operation of resection of the distal femoral end.

[0120] Once the operation has been carried out, the blade guide 4 is in turn detached from the bone 2.

[0121] In order to allow reversible joining of the first 3 and second 4 single-piece parts of the present cutting guide device 1, and when said first part 3 is provided with a rail 14, said second part 3 consists of a slide.

[0122] Consequently, the slide of said second part 4 constitutes the means of cooperation of the latter with the first single-piece part 3. The cooperation between said two parts 3, 4 of the device 1 is then a reversible cooperation by sliding of the first 3 and second 4 parts, one relative to the other.

[0123] It is clear from the above that said means for securing the second 4 to the first part 3, which comprises said first part 3, may constitute, in the particularly preferred embodiment described here, complementary means of cooperation (rail) to the means of cooperation (slide) with the first part 3, which this time comprises said second part 4.

[0124] The cutting guide device 1 according to the present invention and, in particular the first custom-made one-piece part 3 thereof, is preferably manufactured from a plastic polymer.

[0125] The blade guide, corresponding to the second single-piece part 4 of the device 1, can in fact be standard and made of a metallic material. However, it can also be made of a plastic polymer.

[0126] The material from which the first single-piece part 3 of the cutting guide device 1 is manufactured, in particular, preferably meets the following criteria: - The polymer must be a biocompatible material; in fact, despite the short duration during which said cutting guide device 1 is in contact with the body, this contact remains invasive; - The polymer must be sterilizable, in particular by means of an autoclave, for example using a cycle lasting 30 min at a temperature of 134°C, with the application of a water vapour pressure of 3 bars; - The polymer must be rigid, and have a high modulus of elasticity, reflecting a capacity not to deform under stress; - It must also be resistant to heating and abrasion, so as to avoid the formation of wear debris when making the distal femoral cut; - The polymer must preferably be compatible with 3D printing; in particular, the material chosen must ensure control of dimensional tolerances, in order to ensure the angulations are as precise as possible.

[0127] Thus, with regard to the criteria to be respected mentioned above, the polymer material from which the cutting guide device 1 of the invention is manufactured, in particular the first single-piece part 3 of said device 1, is chosen from the group consisting of polyamide (PA), polycarbonate (PC), polyether ether ketone (PEEK), polyoxymethylene (POM), or even acrylonitrile butadiene styrene (ABS).

[0128] In particular, polyamide PA, and more specifically polyamide PA12, which is certified biocompatible, or PA 2200, constitutes a particularly interesting polymer for the manufacture of the cutting guide device 1 of the invention, because it has interesting properties in terms of rigidity, as well as a particularly low wear factor. The bio-sourced and 100% plant-based PAU polyamide, produced from castor oil, can also be used in the manufacture of the device 1 of the invention.

[0129] Thus, according to a second aspect, the present invention relates to a method of manufacturing at least one first single-piece part 3 of a cutting guide device 1 for cutting the distal end 21 of a femur 2 of a patient, such cutting having to be carried out prior to the fitting of a knee prosthesis.

[0130] In order to form the cutting guide device 1 as a whole, said single-piece part 3 can be assembled with a second single-piece part 4, which can be a standard, reusable part, while the first part 3 is custom-made.

[0131] The assembly of the two parts 3, 4 must allow, as mentioned above in connection with the first aspect of the invention, the adjustment of the cutting plane of said distal end 21 of the femur 2, which must be orthogonal to the mechanical axis KH.

[0132] Said first single-piece part 3 comprises at least one rectangular plate 8 constituting a bearing surface 81 tangent T to the femoral condyles 22, 23 when said part 3 is placed on the femur.

[0133] This rectangular plate 8 is provided, substantially in its center, with a central tubular guide stud 9. This projects from the surface 82 of the plate 8 opposite the support surface 81 at the condyles 22, 23.

[0134] Said rectangular plate 8 further comprises at least two bores 10, 11 each designed to receive a fixing pin 12, 13 of said first single-piece part 3 to the femur 2.

[0135] This first part 3 also comprises means for securing, to it, the second 4 to the first 3 for the formation of the cutting guide device 1.

[0136] These securing means may consist of a rail 14 projecting from the rectangular plate 8, on the side of the surface 81 of the plate 8 which serves as a support for the condyles 22, 23, in a plane perpendicular to the plane of the plate 8.

[0137] With reference to [Fig.7], the method of manufacturing this part 3 is, more specifically, characterized in that it comprises, at least, the following steps: - At least one standard, two-dimensional, front-facing radiograph of the femur 2 at the level of which the distal femoral cut is to be made is carried out according to a conventional procedure; - On the basis of said X-ray of the femur 2, from the front and from the side, carried out in the previous step, at least the following physiological data relating to the patient are determined: • the HKS angle between the anatomical diaphyseal femoral axis KS and the axis mechanical femoral KH; the measurement of this HKS angle is shown on radiograph no. 1, top left, of figure 7, which corresponds to a front radiograph of femur 2; • the angle a between the diaphyseal femoral axis KS and the tangent T (or OSAFD - Orientation Surface Articular Femoral Distale) to the femoral condyles 22, 23; the measurement of this angle a is shown on radiograph no. 2, top right, of figure 7, this also corresponding to a frontal radiograph of the femur 2;

[0138] On the basis of the physiological data which were collected in the previous step, the plans of the first single-piece part 3 of the cutting guide device 1 to be manufactured are determined.

[0139] This step is carried out by means of suitable software, which is also preferably configured to analyze the radiograph(s) of the femur 2 and extract therefrom the key physiological data mentioned above.

[0140] The plans of the first single-piece part 3 to be manufactured are established so that: - On the one hand, that the central tubular guide stud 9, which the part 3 comprises at the level of the plate 8, forms an angle equal to a with the plane of said plate 8, so that, once said part 3 is positioned tangent to the femoral condyles, said stud 9 is coaxial with the femoral diaphyseal axis KS; - On the other hand, the rail 14, being in a plane perpendicular to the plane of this plate 8, is inclined relative to said plane of the plate 8, by an angle equal to a-HKS, so as to be coaxial with the femoral mechanical axis KH once said part 3 is put in place at the level of the distal end 21 of the femur 2.

[0141] In other words, the angular divergence HKS between the anatomical axis KS and the mechanical axis KH of the patient's femur 2 is reflected, at the time of implementation of the manufacturing method, on the first single-piece part 3 of the cutting guide device 1, between the central tubular guide stud 9 (allowing, at the time of positioning of the part 3, the passage of a square tip along, then, the axis KS) and the rail 14 which will allow the positioning of the cutting guide 4 which completes, with the part 3, the device 1 of the invention.

[0142] On a single piece 3, the two anatomical angles a and HKS can therefore be ensured in a particularly advantageous manner, for the production of a distal femoral cut perfectly orthogonal to the mechanical axis KH.

[0143] In the last step of the manufacturing process of the single-piece part 3, this part is produced, on the basis of the previously established plans, by additive manufacturing.

[0144] This step can be carried out in particular by selective laser sintering, by deposition of molten material, by stereolithography, using an additive manufacturing machine, such as a 3D printer.

[0145] According to a particularly preferred embodiment of the method of the invention, the last step of the method of the invention consists of additive manufacturing by the molten material deposition method, the material used being, in particular but not limited to, a plastic polymer chosen from polyamide (PA), in particular PA12, polyoxymethylene (POM), or even acrylonitrile butadiene styrene (ABS).

[0146] In particular, ABS has interesting mechanical properties, as well as good printability.

[0147] As illustrated in photograph 3) of [Fig.7], on the basis of the radiograph of the femur 2 taken from the front, in addition to the angle HKS and the angle a, the distance x corresponding to the distance between the most prominent point of the femoral condyles 22, 23 relative to the mechanical femoral axis KH is determined, in order to facilitate the production of the rectangular plate 8 of said first single-piece part 3, in particular with regard to the positioning of the central tubular guide stud 9.

[0148] In a preferred embodiment of the method of the invention, during the first step thereof, two X-rays of the patient's femur 2 are taken.

[0149] In this case, in addition to the first X-ray of the femur 2, which is taken from the front, a second, standard, two-dimensional X-ray is taken, so as to obtain a profile image of said femur 2.

[0150] In [Fig.7] of the attached drawings, at the bottom right, such a profile radiograph is shown, numbered 4).

[0151] Carrying out such a profile radiograph makes it possible in particular to measure the physiological parameter d. The latter corresponds to the distance between the anterior cortex of the femur 2 and the diaphyseal axis AD of the latter.

[0152] Knowing this distance d will make it possible to best center the entry point of the square tip in the stud 9 and to calculate the height h, this being equal, most preferably, to d+10 mm, this height h making it possible to provide sufficient space to slide the part 4 on the inverted L of the part 3.

[0153] By means of the profile radiograph, it is also possible to measure the distance y, which corresponds more specifically to the distance between the diaphyseal axis AD and the most tangent point of the condyles on the profile radiograph.

[0154] The measurement of this parameter also makes it possible to center the pad 9 as best as possible on the single-piece part 3.

Claims

Claims

1. Cutting guide device (1) for cutting the distal end (21) of the femur bone (2) prior to fitting a knee prosthesis, said cutting guide device (1) comprising a first single-piece part (3) and a second single-piece part (4) which can be assembled together to define a cutting plane of said distal end (21) of the femur (2), said device (1) being characterized in that said second single-piece part (4) consists of a metal blade guide which comprises a means (5) for passing the blade of a saw, at least two bores (61, 62) each designed to receive a pin (71, 72) for fixing and immobilizing said second single-piece part (4) to the femur (2), and means for cooperating with said first single-piece part (3), the latter consisting of a means for positioning said blade guide (4) and comprising a rectangular plate (8) constituting a bearing surface (81) tangent to the femoral condyles (22, 23),said rectangular plate (8) being provided, substantially in its center, with a central tubular stud (9) for guiding a square point, said stud (9) projecting from the surface (82) of the plate opposite that of support for the condyles (22, 23), said rectangular plate (8) further comprising at least two bores (10, 11) each designed to receive a fixing pin (12, 13) of said first single-piece part (3) to the femur (2), said first single-piece part (3) also comprising means (14) for securing the second single-piece part (4) to the first single-piece part (3) so that, on the one hand, said second single-piece part (4) and said first single-piece part (3) are in perpendicular planes and, on the other hand, said securing means (14) are configured so that said blade passage means (5) is oriented perpendicular to the femoral mechanical axis KH.,

2. Cutting guide device (1) according to claim 1, characterized in that said first single-piece part (3) is made to measure so that the central tubular guide stud (9) is coaxial with the femoral diaphyseal axis KS when the bearing surface (81) is resting on the femoral condyles (22, 23).

3. Cutting guide device (1) according to claim 2, characterized in that the means (14) for securing the second single-piece part (4) to the first single-piece part (3), which said first single-piece part (3) comprises, consist of a rail projecting from the surface (81) of the rectangular plate (8) supporting the condyles (22, 23), said rail (14) being in a plane perpendicular to the plane of the plate (8) and being inclined so as to allow an orientation of the blade passage means (5) perpendicular to the femoral mechanical axis KH.

4. Cutting guide device (1) according to claim 3, characterized in that said rail is part of an inverted L-shaped foot (15) surmounting said rectangular plate (8), said inverted L-shaped foot (15) being coaxial with the femoral mechanical axis KH.

5. Cutting guide device (1) according to claim 3 or claim 4, characterized in that said rail (14) comprises a plurality of graduation notches (141,142,143,144) defining the cutting thickness of the bone (2) to be produced.

6. Cutting guide device (1) according to any one of claims 3 to 5, characterized in that said rail (14) which comprises said first single-piece part (3) cooperates by sliding with a slide which comprises said second single-piece part (4) so ​​that said means for securing said second single-piece part (4) to said first single-piece part (3) constitute the means for reversible cooperation of said second single-piece part (4) to said first single-piece part (3).

7. Cutting guide device (1) according to any one of the preceding claims characterized in that said passage means (5) of the blade of a saw consists of a slot.

8. Method for manufacturing, to measure, a first single-piece part (3) of a cutting guide device (1) for cutting the distal end (21) of a femur (2) of a patient prior to the fitting of a knee prosthesis, said first single-piece part (3) being assemblable to a second standard single-piece part (4) for the formation of said cutting guide device (1) and for adjustment of the cutting plane of said distal end (21) of the femur (2), said first single-piece part (3) comprising at least one rectangular plate (8) constituting a tangent bearing surface (81) T to the femoral condyles (22, 23), said rectangular plate (8) being provided, substantially in its center, with a central tubular guide stud (9) projecting from the surface (82) of the plate (8) opposite that of the bearing surface (81) to the condyles (22, 23), said stud (9) being coaxial with the femoral diaphyseal axis KS,said rectangular plate (8) further comprising at least two bores (10, 11) each designed to receive a fixing pin, (12,13) ​​of said first single-piece part (3) to the femur (2), said first single-piece part (3) also comprising means for securing the second single-piece part (4) to the first single-piece part (3), consisting of a rail (14) projecting from the surface (81) of the rectangular plate (8) supporting the condyles (22, 23), said rail (14) being in a plane perpendicular to the plane of the plate (8) and being inclined so as to be coaxial with the femoral mechanical axis KH, said manufacturing method being characterized in that it comprises, at least, the following steps: - At least one X-ray is taken of said femur (2) at the level of which the distal femoral cut is to be made, said X-ray consisting of a front X-ray of said femur (2); - On the basis of the said X-ray carried out in the previous step, at least the following physiological data relating to the patient are determined: • the HKS angle between the anatomical diaphyseal femoral axis (KS) and the mechanical femoral axis (KH), • the angle a between the diaphyseal femoral axis (KS) and the tangent (T or OSAFD - Orientation Distal Femoral Articular Surface) to the femoral condyles (22, 23), - The planes of said first monobloc part (3) of the cutting guide device (1) are determined, taking into account the previously determined physiological data, by means of suitable software, so that said stud (9) forms an angle equal to a with the plane of the rectangular plate (8) of said first monobloc part (3) and that said rail (14), positioned in a plane perpendicular to the plane of the plate (8), is inclined relative to said plane of the plate (8) by an angle equal to a-HKS, so as to be coaxial with the femoral mechanical axis KH once said first monobloc part (3) is positioned; - Said first single-piece part (3) of the cutting device (1) is manufactured by additive manufacturing, in particular by laser sintering, using a 3D printer.

9. Method of manufacturing a first single-piece part (3) according to claim preceding claim, characterized in that, in addition to the HKS angle and the angle a, at least the following physiological data is determined: - the distance x corresponding to the distance between the most prominent point of the femoral condyles (22, 23) in relation to the mechanical femoral axis (KH).

10. Method for manufacturing a first single-piece part (3) according to claim 8 or claim 9, characterized in that, in addition to the front X-ray of said femur (2), during the first step, a second profile X-ray of said femur (2) is taken, and in that, on the basis of said profile X-ray, at least the following physiological data are determined: - the height d on the lateral radiograph of the femur (2), d corresponding to the distance between the anterior cortex and the diaphyseal axis AD, and - the distance y, corresponding to the distance between the most prominent point of the femoral condyles (22, 23) and the femoral diaphyseal axis AD in profile.

11. Method of manufacturing a first single-piece part (3) according to claim 10 characterized in that said first single-piece part of the cutting device (1) is manufactured from a material chosen from ABS (acrylonitrile butadiene styrene), PA 12 (Polyamide), POM (polyoxymethylene), PC (polycarbonate), PEEK (polyether ether ketone).

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