Distal femoral cutting guide positioning aid device

Abstract

A device for assisting in positioning a distal femoral cutting guide (1), characterized in that it is in the form of a kit comprising a base (2) as a main part, and a cutting guide holder (3) and a distal cutting guide (4) as secondary parts, the base (2) comprising an adjustment element (10) for the degree of femoral varus-valgus, and a column (14) intended to receive the cutting guide holder (3), the cutting guide holder (3) comprising a fixing element (15) allowing adjustable fixing of said holder (3) on said column (14). Figure 8

Description

Title of the invention: Device for assisting in positioning a distal femoral cutting guide

[0001] The invention relates to the field of knee prostheses. In particular, it relates to a device for assisting in the positioning of a distal femoral cutting guide, enabling in particular the production of a distal femoral cut in preparation for the operation of fitting the prosthesis.

[0002] The knee is the joint between the femur and the tibia. The patella is a third bony part located towards the front and is part of the joint. The sliding articular surfaces are covered with cartilage and numerous muscles and tendons surround this joint and allow the knee to be extended and bent.

[0003] Osteoarthritis is a wear and tear of the cartilage present at the sliding surfaces. This wear and tear is also accompanied by changes in the femur, tibia and patella. These changes cause pain in the knee as well as stiffness and difficulty walking, requiring the extensive use of anti-inflammatories, painkillers and sometimes even a cane.

[0004] The wear and tear of the cartilage is irreversible and osteoarthritis does not heal spontaneously. The natural progression is towards a progressive deterioration of the joint, an increasingly significant limitation of mobility and increasingly difficult walking.

[0005] Anti-inflammatory and painkillers that may initially be sufficient eventually become ineffective. This is when the question of surgery arises.

[0006] The aim of the surgical operation is to relieve pain, restore joint mobility and resume normal walking, by removing areas of bone and cartilage that are worn, and replacing them with artificial parts having the same shapes.

[0007] An incision is made at the anterior part of the knee. A passage is made through the inner part of the kneecap to access the joint, then the worn cartilage is removed. The femur, tibia, and kneecap are then prepared to receive the prosthesis.

[0008] Bone preparation begins with femoral preparation, which allows all of the cartilage to be removed and the shape of the femur to be adapted so that it can receive the prosthesis. This preparation is carried out in particular using cutting templates of a size adapted to the operated femur.

[0009] To do this, a specific instrument is used, which is a cutting guide and which allows a distal femoral cut to be made. This cut will then serve as a positioning reference for the cutting template of the size adapted to the implant to make the smallest possible cuts at the level of the femur and to prepare the placement of the femoral implant of the prosthesis.

[0010] The surgeon successively performs the distal, anterior, then posterior femoral cuts and finally the chamfers. The angulation and rotational orientation of these cuts is personalized for each patient and determined by the imaging examinations carried out before the operation.

[0011] A tibial cutting guide is then positioned on the anterior surface of the tibia and the upper tibial cut removing the worn cartilage is made. After checking with plastic trial implants that the thickness and orientation of the cuts made were correct, the final implants are placed, starting with the positioning of the tibial implant on which a polyethylene insert is fixed. Once the femoral implant is in place, the sliding of the femoral implant on the polyethylene insert allows movements of the knee. The worn cartilage of the patella must also be removed. A polyethylene patellar implant is fixed on the articular surface allowing painless sliding of the patella along the femoral implant during movements of the knee.

[0012] Total knee prostheses are sold in different markets (in Europe and outside Europe) with different pricing and regulations. For example, in some markets the instrumentation for fitting the prosthesis is loaned, while in other markets it can be sold.

[0013] The invention proposes an ancillary device, in particular a device for assisting in the positioning of a distal femoral cutting guide, which makes it possible to adapt to the different target markets, while maintaining the same level of safety and performance.

[0014] The invention thus relates to a device for assisting in the positioning of a distal femoral cutting guide. The device according to the invention is in the form of a kit comprising a base as a main part, and a cutting guide support and a distal cutting guide as secondary parts, the base comprising an element for adjusting the degree of femoral varus-valgus (i.e. the angle between the mechanical axis of the femur and the axis of the femoral diaphysis), and a column intended to accommodate the cutting guide support, the cutting guide support comprising a fixing element allowing adjustable fixing of said support on said column.

[0015] Thus, the kit structure of the device is advantageous: the main part of the device allows several versions of the secondary parts to be received, these parts having production costs adapted to the target markets, the column ensuring the modality of the whole.

[0016] The fixing element allowing adjustable fixing of said support on said column may be a wheel.

[0017] The cutting guide holder may include a fastening element allowing the cutting guide to be secured to the cutting guide holder.

[0018] The fixing element allowing the cutting guide to be fixed to the cutting guide support may be a wheel or a clip.

[0019] The base may comprise a body of elongated shape in an axial direction and intended to be aligned with the medullary axis of the femur, and a tube housed in the body, intended to accommodate a centromedullary rod, and mounted to rotate around an axis orthogonal to the axial direction of the body, the axis being located at a first axial end of the tube.

[0020] The column may extend orthogonally to the axial direction of the body.

[0021] The femoral varus-valgus degree adjustment element may be located at a second axial end of the tube.

[0022] The body may comprise at the first axial end of the tube a bearing surface making it possible to position the device against a femoral condyle.

[0023] The cutting guide may be a standard cutting guide, a single-use cutting guide, a custom cutting guide, or a minimally invasive cutting guide.

[0024] The device may further comprise a centromedullary rod.

[0025] Other characteristics and advantages of the present invention will appear on reading the detailed description below, of a non-limiting example of implementation, made with reference to the appended figures in which:

[0026] [Fig-1] is a top perspective view of a cutting guide device distal femoral according to the invention,

[0027] [Fig.2] is a perspective view from below of the guide device,

[0028] [Fig.3] is a perspective view of the base of the guide device,

[0029] [Fig.4] is a perspective view of the guidance device, in the operable configuration tional of the device,

[0030] [Fig.5] is a first view of a femur-tibia assembly,

[0031] [Fig.6] is a second view of a femur-tibia assembly,

[0032] [Fig.7] is a third view of a femur-tibia assembly,

[0033] [Fig.8] is an exploded perspective view of a guide device according to the invention, according to a first embodiment,

[0034] [Fig.9] is an exploded perspective view of a guide device according to the invention, in accordance with a second embodiment,

[0035] [Fig. 10] illustrates a first step of a femoral preparation,

[0036] [Fig. 11] illustrates a second stage of a femoral preparation,

[0037] [Fig. 12] illustrates a third stage of a femoral preparation,

[0038] [Fig. 13] illustrates a fourth step of a femoral preparation,

[0039] [Fig. 14] illustrates a fifth step of a femoral preparation,

[0040] [Fig. 15] illustrates a sixth step of a femoral preparation,

[0041] [Fig. 16] illustrates a seventh step of a femoral preparation,

[0042] [Fig. 17] illustrates an eighth step of a femoral preparation, and

[0043] [Fig. 18] illustrates a ninth step of a femoral preparation.

[0044] As illustrated in Figures 1 to 9, a cutting guide device 1, in particular for distal femoral cutting, is in the form of a kit comprising a main part which is a base 2, and secondary parts comprising a cutting guide support 3 and a cutting guide 4.

[0045] The base 2 is elongated in shape and is intended to be aligned with the medullary canal of the femur.

[0046] The base 2 comprises a shaped body 5 in which a tube 6 is mounted for rotation about an axis 11 for receiving a centromedullary rod 7. The axis 11 is located at a first axial end of the tube 6. The centromedullary rod 7 makes it possible to guide the cutting guide device 1 to the femur. For this purpose, an opening 8 made in the femur 9 using a drill 18 allows the rod 7 to be inserted (Figures 5 and 6).

[0047] The base 2 allows the adjustment of the femoral varus-valgus. For this purpose, it comprises a wheel 10 secured to the tube 6, and arranged at a second longitudinal end of the base 2. The wheel 10 allows the inclination of the tube 6 to be adjusted relative to the axial direction of the body 5.

[0048] At the end of growth, the lower limbs are either oriented, varus, or valgus. This is what is called the morphotype. The varus morphotype corresponds to the bowed legs of riders. With age, it can lead to wear of the internal compartment of the knee, due to the increase in pressure on this compartment. On oriented legs, the pressure is equivalent on the internal compartment and the external compartment. On valgus, X-shaped legs, the wear will be more on the external compartment than on the internal compartment.

[0049] [Fig.7] illustrates a femur 9, a tibia 12, with femoral valgus angle A, a distal femoral section plane B, a tibial section plane C, as well as the axis D of the femoral centromedullary canal.

[0050] The body 5 comprises a longitudinal main surface 26 which is parallel to the tube 6 and towards the rear a radial bearing surface 13 which is orthogonal to the main surface of the body 5 and making it possible to position the device 1 against a femoral condyle. The bearing surface 13 is provided with an opening at which one end of the tube 6 opens.

[0051] The base 2 further comprises a radial vertical column 14 which extends orthogonally to the main surface 26 of the body 5. The column 14 makes it possible to adjust the vertical position of the cutting guide support 3. The column 14 further ensures the modularity of the assembly. It allows several versions of the secondary parts to be connected, which consist of the cutting guide support 3 and the distal femoral cutting guide 4.

[0052] The cutting guide support 3 is configured to receive the cutting guide 4 so that the cutting plane of the cutting guide 4 is a radial cutting plane, orthogonal to the axial direction of the support 5.

[0053] In a first embodiment, illustrated in [Fig.8], the cutting guide support 3 comprises a first wheel 15 for fixing the cutting guide support 3 on the column 14 and a second wheel 16 for fixing the cutting guide 4 on the support 3.

[0054] In a second embodiment, the cutting guide support 3 comprises a wheel 15 for fixing the cutting guide support 3 to the column 14 and a system for fixing the cutting guide 4 to the support 3 using a clip 17 comprising a jaw which is positioned in a slot of the cutting guide 4 ([Fig.9]).

[0055] The remainder of the description is devoted to an example of the production of a femoral preparation.

[0056] The femoral preparation begins by making a distal cut, using the device for assisting in positioning the distal femoral cutting guide according to the invention.

[0057] We begin by adjusting the degree of femoral valgus using the wheel 10 which can be operated on the right or left side from 3° to 9°, in increments of 1° ([Fig.10]). We use the HKS angle (for "Hip-Knee center of femoral-Shaft" in English), the angle between the anatomical axis of the femur and its mechanical axis, calculated before the operation, which is the angle formed by the mechanical axis of the femur and the axis of the femoral diaphysis. It gives the measurement of the femoral valgus which will be taken into account during the femoral cut.

[0058] The cutting guide 4 is assembled on its support 3 and the assembly is then positioned on the base 2 of the device 1 ([Fig.l 1]).

[0059] An entry hole 8 is then drilled in the notch of the femur 9 using a drill bit 18 of 8 mm diameter, in the axis D of the femoral centromedullary canal.

[0060] The 8 mm diameter centromedullary rod 7 is inserted into the entry hole 8 using a removable T-shaped handle, taking care to leave at least 10 cm inside the bone.

[0061] The T-handle is removed and the cutting guide device 1 is inserted onto the rod 7 until contact with at least one femoral condyle is obtained ([Fig.4]).

[0062] The position of the cutting guide 4 is fixed using two pins 19.

[0063] The wheel 16 of the cutting guide support 3 is unlocked, the centromedullary rod 7 is removed using the T-handle, then the cutting guide device 1 is removed.

[0064] The cutting guide 4 is brought as close as possible to the anterior part of the femur 9 and is then locked by a headed pin 20. The femoral cut is carried out ([Fig. 12]), then the cutting guide 4 is removed ([Fig. 13]).

[0065] The femoral preparation continues by making the anterior and posterior cuts and the chamfers.

[0066] A cutting template 21 is used to make an anterior cut, a posterior cut, an anterior chamfer and a posterior chamfer. The cutting template 21 is positioned in the previously formed holes ([Fig. 14]).

[0067] The cutting template 21 is impacted in contact with the distal femoral cut. A final check can be carried out on the anterior cortex using the control plate. Two convergent head fixation pins 22 are used to lock the guide 21 in position ([Fig. 15]).

[0068] The cuts are made using the cutting template 21, using a saw blade 23 1.27 mm thick and ideally 25 mm wide and 90 mm long ([Fig. 16]). Preferably, the following cutting order is used: the anterior cut, the posterior cut, the anterior chamfer, and the posterior chamfer.

[0069] Finally, the head pins 22 and the cutting guide 21 are removed using the universal extractor ([Fig. 17]).

[0070] The upper tibial cut is then made, removing the worn cartilage.

[0071] The recommended order of implant placement is as follows: tibial base, femoral implant 24, tibial insert and patellar implant.

[0072] The knee is placed in full extension, which keeps the femur and the tibial base under pressure to ensure good impaction.

[0073] If the patellar implant is placed, the cement is deposited on the implant or the bone cut according to the operator's habits.

[0074] The femoral implant 24 is then placed in the three holes and is held under pressure using the ball joint clamp fitted with the cementing tip.

[0075] The femoral impactor 25 is used only for the placement of the trial implant and the definitive implant ([Fig. 18]).

[0076] After checking with plastic trial implants that the thickness and orientation of the cuts made were correct, the final implants are put in place, starting with the positioning of the tibial implant on which a polyethylene insert is fixed. Once the femoral implant is in place, the sliding of the femoral implant on the polyethylene insert allows movement of the knee. The worn cartilage of the patella must also be removed. A polyethylene patellar implant is fixed on the articular surface allowing painless sliding of the patella along the implant. femoral during knee movements.

Claims

Claims

1. Device for assisting in positioning a distal femoral cutting guide (1), characterized in that it is in the form of a kit comprising a base (2) as a main part, and a cutting guide support (3) and a distal cutting guide (4) as secondary parts, the base (2) comprising an element (10) for adjusting the degree of femoral varus-valgus, and a column (14) intended to accommodate the cutting guide support (3), the cutting guide support (3) comprising a fixing element (15) allowing adjustable fixing of said support (3) on said column (14).

2. Device (1) according to claim 1, characterized in that the fixing element (15) allowing adjustable fixing of said support on said column (14) is a wheel (15).

3. Device (1) according to claim 1 or 2, characterized in that the cutting guide support (3) comprises a fixing element (16, 17) allowing the fixing of the cutting guide (4) on the cutting guide support (3).

4. Device (1) according to claim 3, characterized in that the fixing element (16, 17) allowing the fixing of the cutting guide (4) on the cutting guide support (3) is a wheel (16) or a clip (17).

5. Device (1) according to one of claims 1 to 4, characterized in that the base (2) comprises a body (5) of elongated shape in an axial direction and intended to be aligned with the medullary axis of the femur (9), and a tube (6) housed in the body (5), intended to accommodate a centromedullary rod (7), and mounted to rotate around an axis (11) orthogonal to the axial direction of the body (5), the axis (11) being located at a first axial end of the tube (6).

6. Device (1) according to claim 5, characterized in that the column (14) extends orthogonally to the axial direction of the body (5).

7. Device (1) according to claim 5 or 6, characterized in that the adjustment element (10) of the degree of femoral varus-valgus is located at a second axial end of the tube (6).

8. Device (1) according to one of claims 5 to 7, characterized in that the body (5) comprises at the first axial end of the tube (6) a bearing surface (13) allowing the device (1) to be positioned against a femoral condyle.

9. Device (1) according to one of claims 1 to 8, characterized in that The cutting guide (4) is a standard cutting guide, a single-use cutting guide, a custom cutting guide or a minimally invasive cutting guide.

10. Device (1) according to one of claims 1 to 9, characterized in that it further comprises a centromedullary rod (7).