FR3071147A1 - DEVICE FOR ASSEMBLING KNEE PROSTHESIS, DISTILING TOOL AND BALANCING LIGAMENTARY KNEE SYSTEM - Google Patents

Abstract

Device for assisting the placement of a knee prosthesis comprising: - a column (6) extended orthogonally by a plate (5) having a lower tibial bearing surface, the column (6) being graduated from said bearing face; a first slider (7) slidably mounted around the column (6), and comprising an axis (7a) extending parallel to the plate (5), and a rocker (8) pivotally mounted about the axis (7a) , the rocker (8) comprising two pads (4) in opposition to the plate (5) and having upper condylar bearing surfaces, the rocker (8) and the first slide (7) comprise markers (12) indicating the angle of rotation of the rocker (8) with respect to the first slide (7) from a position in which the pads (4) are parallel to the plate (5), the first slide (7) forming a cursor indicating on the graduation of the column (6) the spacing between the bearing surface of the plate (5) and the bearing surfaces of the pads (4); - A second slide (21) slidably mounted around the first slide (7) and comprising a probe (24) parallel to the plate (5) and having an end intended to abut on the anterior cortex of the femur, the first slide (7). ) is graduated from the bearing surface of the pads (4), and the second slide (21) forms a cursor indicating on said graduation the distance between the bearing surfaces of the pads (4) and the end of the probe (24) corresponding to the size of the femoral condyle; locking means (14) of the first slide (7) on the column (6); - Locking means (23) of the second slider (21) on the first slider (7); - means (11) for locking in rotation of the balance (8); means (15) for slidably driving the first slider (7).

Description

Aid device for the installation of a knee prosthesis, distractor tool and BALANCER OF THE KNEE LIGAMENT SYSTEM

TECHNICAL AREA

The present invention relates to the technical field of orthopedic surgery, and more particularly relates to a device for assisting the fitting of a knee prosthesis, in the form of an ancillary distractor balancing the knee.

PRIOR STATE OF THE ART

To implant a knee prosthesis, it is known that the surgeon uses a distracting device, to tension the knee joint. In practice, this ancillary is generally in the form of two branches articulated with respect to each other, the ends of which are respectively provided with tibial support means and condylar support means. Thus, by interposing a spacing mechanism between the branches, it is possible, after having disposed inside the femoro-tibial space the ends of said branches, to tension the knee joint, for example by bending and to be able to pre-position the positioning holes of the femoral guide which will perform the anterior, posterior and chamfer cuts of the condylar box of the femoral implant.

This restores the femur / tibia line space and balances the internal and external lateral ligaments to adjust the size and thickness of an implant for optimal flexion.

Document FR 2 867 963 describes a type of distractor for implanting a knee prosthesis. This ancillary allows to balance the internal and external lateral ligaments, as well as to adjust the femur / tibia line spacing.

However, this ancillary is of complex design, and does not allow to adjust or give the angle of rotation of the femur of the operated patient, nor the size of the condyle to be implanted.

Indeed, it should be remembered that, on an anatomical level, the condyles of the femur are in external rotation relative to the tibial plane, at an angle varying according to the patient from 2 ° to 8 °.

As far as possible, the rotation of the condyle of the patient's femur must be respected during the implantation of a knee prosthesis to have a good arthroplasty.

STATEMENT OF THE INVENTION

One of the aims of the invention is therefore to remedy the aforementioned drawbacks by proposing a device for assisting in the fitting of a knee prosthesis, in the form of an auxiliary distractor making it possible to balance the internal lateral ligaments and external, measure the femur / tibia line spacing, adjust and give the angle of rotation of the femur relative to the tibial plane, as well as give the size of the condyle.

The objective of the invention is therefore to allow the correct orientation of the prosthetic femur relative to the tibia to have good flexion, and to avoid knee joint pain when walking, while pre-positioning the positioning holes of the femoral guide anterior, posterior cuts and chamfers of the condylar box.

To this end, a remarkable device has been developed in that it includes:

- a column extended orthogonally by a plate having a lower tibial support face, the column being graduated from said support surface;

a first slide mounted sliding around the column, and comprising an axis extending parallel to the plate, and a pendulum mounted pivoting about the axis, the balance comprising two pads in opposition to the plate and having upper surfaces of condylar support, the pendulum and the first slide include marks indicating the angle of rotation of the pendulum with respect to the first slide from a position in which the pads are parallel to the plate, the first slide forms a cursor indicating on the scale from the column the spacing between the bearing face of the plate and the bearing surfaces of the pads;

a second slide mounted to slide around the first slide and comprising a feeler parallel to the plate and having one end intended to come to bear on the anterior cortex of the femur, the first slide is graduated from the bearing surface of the pads, and the second slide forms a cursor indicating on said graduation the distance between the bearing surfaces of the pads and the end of the probe, corresponding to the size of a condyle of the femur;

- means for locking the first slide on the column;

- means for locking the second slide on the first slide;

- means for locking the balance in rotation;

- sliding drive means of the first slide.

In this way, the placement of the distractor ancillary in a knee joint in 90 ° flexion allows a surgeon to come and restore the femur / tibia line spacing, while allowing the internal and external lateral ligaments to be balanced, measure the thickness of the tibial implant and the size of the condyle to be implanted, and adjust the angle of rotation of the femur relative to the tibia.

According to a particular embodiment, the means for locking the first slide on the column include a locking screw passing through the thickness of the first slide to come into contact with the column.

Preferably, the means for locking the second slide on the first slide comprise a locking screw passing through the thickness of the second slide to come into contact with the first slide.

According to a particular embodiment, the column comprises a lower blind hole, and a longitudinal lumen, centered and formed from a face opposite the plate.

In this configuration, the means for blocking the rotation of the balance comprises a locking screw passing through the first slide and the longitudinal lumen to block the rotation of the balance.

Preferably, the sliding drive means of the first slide comprise an opening rack clamp, which comprises two tubular ends, one of which is intended to penetrate into the blind hole, and a second which is intended to penetrate into the longitudinal lumen, so that the actuation of the clamp separates the two ends from one another and causes the sliding of the first slide.

Advantageously, the second slide has oriented through holes to form guides for drilling the femur, such as for example guides for drilling holes in a femoral cut for the subsequent positioning of a cut guide.

Preferably, the pendulum has holes for guiding threaded pins to fix the pendulum to the femur.

According to a particular embodiment, the feeler is in the form of a rod received in an upper orifice presented by the second slide, and with capacity for parallel sliding and in the direction of the pads, the end of the rod being bent towards the skates.

BRIEF DESCRIPTION OF THE DRAWINGS

Other characteristics and advantages of the invention will emerge clearly from the description which is produced below, for information and in no way limitative, with reference to the appended figures in which:

- Figure 1 is a schematic view illustrating, in perspective, an ancillary distractor placed in a knee joint in flexion, between a proximal tibial section and a femur;

- Figure 2 is a schematic view similar to that of Figure 1, showing in perspective the ancillary distractor alone;

- Figure 3 is a schematic view illustrating in perspective a graduated column extended by a tibial support plate;

- Figure 4 is a schematic view similar to that of Figure 3, illustrating the column and the tibial plateau in perspective and seen from behind;

- Figure 5 is a schematic view illustrating in perspective a first slide comprising a pendulum and two condylar support pads;

- Figure 6 is a schematic view illustrating the first slide and the pendulum mounted on the column of the tibial support plate;

- Figure 7 is a schematic view similar to that of Figure 6, the first slide mounted on the column being seen from behind;

- Figure 8 is a schematic view illustrating in perspective a second slide comprising a feeler for measuring the size of the condyles;

- Figure 9 is a schematic perspective view illustrating sliding drive means of the first slide, being in the form of an opening clamp with rack.

DETAILED PRESENTATION OF THE INVENTION

With reference to FIGS. 1 and 2, the invention relates to a device (1) for assisting with the fitting of a knee prosthesis, in the form of a distracting device intended to be positioned between a proximal tibial cut (2 ) and the condyles (3) of a femur of a knee joint in 90 ° flexion.

The ancillary distractor according to the invention makes it possible to separate the femur and the tibia to restore the femur / tibia line space and balance the internal and external lateral ligaments. To this end, and with reference to FIGS. 1 to 7, the ancillary device comprises pads (4) having condylar support surfaces, in opposition to a plate (5) having a lower tibial support face, the plate ( 5) and the pads (4) being mounted with the ability to separate one from the other.

More specifically, with reference to Figures 3 and 4, the plate (5) comprises a column (6) extending orthogonally relative to the plate (5), and graduated from the bearing face of said plate (5). Referring to Figures 5 to 7, the pads (4) are, in turn, joined by a body extending orthogonally to the pads (4). The body is pivotally mounted about an axis (7a) extending parallel to the plate (5) and orthogonally to a part forming a first slide (7). The body then forms a balance (8), and is advantageously perforated to reduce its weight.

According to a particular embodiment, the first slide (7) has a generally parallelepiped shape, hollow and open at its two small lower and upper faces, to be fitted and mounted to slide around the column (6) of the plate (5 ) tibial support.

The graduated column (6) comprises a lower blind hole (9) and a longitudinal opening (10), centered with respect to the width of the column (6), and formed from a face opposite the plate (5). The first slide (7) comprises means for locking the balance (8) in rotation comprising a locking screw (11) passing through the first slide (7) and the longitudinal slot (10) to block the rotation of the balance (8) .

Referring to Figures 5 to 7, the balance (8) and the first slide (7) comprise marks (12) indicating the angle of rotation of the balance (8) relative to the first slide (7), in particular from 'a reference position in which the pads (4) are parallel to the plate (5). By way of example, the pins (12) are formed on an upper face of the balance (8), so as to indicate the left and right directions, opposite angular pins formed on an upper face of the first slide (7), indicating angles 0 ° to 8 °.

The lower end of the first slide (7), for example aligned with the upper condylar support surfaces of the pads (4), forms a cursor indicating on the graduation of the column (6) the spacing between the support face of the plate (5) and said bearing surfaces of the pads (4), corresponding in particular to the femur / tibia line space and therefore to the thickness of the tibial implant to be implanted.

The first slide (7) comprises, at one of these lateral faces, a threaded bore (13) receiving a locking screw (14) intended to pass through the thickness of said wall and come into contact and abut against the column (6) to prevent the sliding of the first slide (7) and lock its position.

The ancillary distractor also comprises means (15) for driving the sliding of said first slide (7), for example in the form of an opening clamp with rack. More specifically, the clamp (15) comprises two branches articulated (16) around an axis and extended by tubular ends, including a first end (17) intended to penetrate into the lower blind hole (9) made in the column ( 6), and a second end (18) intended to penetrate the longitudinal lumen (10) so that the actuation of the clamp (15) separates the two ends (17, 18) from one another and causes the sliding of the first slide (7) along the column (6). The clamp (15) comprises a rack (19) allowing the spacing of the tubular ends (17, 18) to be locked when a certain angular force is reached. Preferably, and with reference to FIG. 7, the first slide (7) comprises an oblong lower notch (20) intended to receive the end of the clamp (15) engaged in the longitudinal lumen (10) of the column (6 ).

The distractor ancillary comprises a second slide (21) slidably mounted around the first slide (7). To this end, and with reference to FIG. 8, the first slide (7) comprises a general inverted U shape, the lateral branches (21a) of which are intended to cover the side walls of the first slide (7). The second slide (21) comprises, at the ends of the lateral branches (21a), orifices (22) passing through and oriented to open at the femur, and form drilling guides, for example holes in a femoral cut for the subsequent positioning of a cutting guide.

The second slide (21) also comprises means (23) for locking said second slide (21) on the first slide (7). These means are for example in the form of at least one locking screw (23), passing through the thickness of the second slide (21), and in particular one of its lateral branches (21a), to come into contact and abut with at least one of the side walls of the first slide (7).

The second slide (21) includes a feeler (24) in the form of a rod received in an upper orifice (25) and with sliding capacity inside said orifice (25). The feeler rod (24) extends parallel to the pads (4), and in the same direction, and has a curved end in the direction of said pads (4) and intended to come to bear on the anterior cortex of the femur.

With reference to FIG. 7, the first slide (7) comprises, for example on one of its front or rear faces, a scale (26) whose bearing surfaces of the pads (4) form the reference, and the second slide (21) comprises a cursor (27) indicating on said graduation the distance between the bearing surfaces of the pads (4) and the end of the probe (24), corresponding in particular to the size of the condyles (3) of the femur .

Thus, in practice the ancillary distractor (1) according to the invention is positioned in a knee joint in 90 ° flexion, after having made a proximal tibial cut. In particular, the plate (5) comes to bear on the tibial cut (2), and the pads (4) are positioned under the two condyles (3) of the femur. In this configuration, the balance (8) is free to rotate.

The feeler rod (24) is then slid under the skin, so that the tip of the curved end comes to rest on the anterior cortex of the femur, between the two condyles on the anterior flat surface of the femur.

At this stage, the surgeon penetrates the tubular ends of the clip (15) opening with rack, respectively in the lower blind hole (9) and in the longitudinal lumen (10) of the column (6). Thus, the actuation by the surgeon of said clamp (15) makes it possible to separate the tubular ends (17, 18) so as to make the first slide (7) slide on the column (6) until the equilibrium is obtained of the pendulum (8) which pivots under the tension corresponding to the ligament balance of the internal and external lateral ligaments.

In this configuration, the knee is balanced, the femur has notably rotated externally relative to the tibial plateau (5). The clamp (15) is then locked in position by the rack (19), the surgeon then blocks the sliding of the first slide (7) by tightening the locking screw (14), as well as the rotation of the pendulum (8) by rotating the locking screw (11), before being able to remove the rack clamp (15).

In this configuration, and in order to improve the stability of the distractor ancillary, it is possible to fix the pendulum (8) to the femur by means of threaded pins (28), see FIG. 8, passing through guide holes that presents said pendulum (8).

The surgeon can then drill reference holes in the distal femoral cut previously made with a drill bit (29), passing through the guide holes (22) that include the lateral branches (21a) of the second slide (21), which will be used for example to position a guide of posterior, anterior femoral cuts and chamfers of the condylar box of the implant.

The ancillary distractor also makes it possible to read, on the graduated column (6), the distance between the tibial bearing surface of the plate (5) and the condylar bearing surface of the pads (4), corresponding to the thickness of the tibial tray (5) to be implanted. In the same way, the ancillary distractor makes it possible, by means of the pendulum (8), to adjust and give the angle of rotation of the femur relative to the tibia. Finally, the surgeon can also read, on the scale (26) of the first slide (7), the distance between the condylar bearing surface of the pads (4) and the end of the feeler (24), corresponding in particular to the size condyle (3) to be implanted.

It emerges from the above, that the invention provides a device (1) for assisting in the fitting of a knee prosthesis, in the form of a distractor, which is reliable and which allows optimal repeatability of the surgical gesture. The ancillary distractor according to the invention also allows a reliable balancing of the ligament balance since it is physiological in the sense that it is the internal and external lateral ligaments which give the rotation, the balancing and the height of the line space between the tibial cut and the posterior side of the condyles (3). This prevents any laxity or tension in the knee, which plays on stability or flexion. The distractor instrument is simple in design and easy to use.

Claims (10)

1. Device (1) for assisting in the placement of a knee prosthesis, characterized in that it comprises: - A column (6) extended orthogonally by a plate (5) having a lower tibial support face, the column (6) being graduated from said support face; - A first slide (7) mounted sliding around the column (6), and comprising an axis (7a) extending parallel to the plate (5), and a balance (8) mounted pivoting around Tax (7a), the pendulum (8) comprising two pads (4) in opposition to the plate (5) and having upper condylar support surfaces, the pendulum (8) and the first slide (7) include marks (12) indicating the angle of rotation of the balance (8) relative to the first slide (7) from a position in which the pads (4) are parallel to the plate (5), the first slide (7) forming a cursor indicating on the graduation of the column (6) the spacing between the bearing face of the plate (5) and the bearing surfaces of the pads (4); a second slide (21) mounted to slide around the first slide (7) and comprising a feeler (24) parallel to the plate (5) and having an end intended to come to bear on the anterior cortex of the femur, the first slide (7 ) is graduated from the bearing surface of the pads (4), and the second slide (21) forms a cursor indicating on said graduation the distance between the bearing surfaces of the pads (4) and the end of the probe (24) corresponding to the size of the condyle of the femur; - locking means (14) of the first slide (7) on the column (6); - locking means (23) of the second slide (21) on the first slide (7); - Means (11) for locking the balance (8) in rotation; - Means (15) for sliding the first slide (7). 2. Device (1) according to claim 1, characterized in that the second slide (21) has through holes (22) oriented to form drilling guides for positioning holes of a guide for preparing the posterior anterior cuts and chamfers of the condylar box of the total knee replacement. 3. Device (1) according to claim 1, characterized in that the locking means (14) of the first slide (7) on the column (6) comprise a locking screw passing through the thickness of the first slide (7) for come into contact with the column (6). 4. Device (1) according to claim 1, characterized in that the means (23) for locking the second slide (21) on the first slide (7) comprise a locking screw passing through the thickness of the second slide (21) to come into contact with the first slide (7). 5. Device (1) according to claim 1, characterized in that the column (6) comprises a lower blind hole (9) and a longitudinal slot (10), centered and formed from a face opposite the plate (5 ). 6. Device (1) according to claim 5, characterized in that the means for blocking the balance in rotation (8) comprise a blocking screw (11) passing through the first slide (7) and the longitudinal lumen (10) to come block the rotation of the pendulum (8). 7. Device (1) according to claim 5, characterized in that the sliding drive means of the first slide (7) comprise a clamp (15) opening with rack, comprising two tubular ends including a first end (17) intended to penetrate into the blind hole (9), and a second end (18) intended to penetrate into the longitudinal lumen (10) so that the actuation of the clamp (15) spreads the two ends (17, 18) one of the other and causes the sliding of the first slide (7). 8. Device (1) according to claim 1, characterized in that the second slide (21) has through holes (22) oriented to form guides for piercing the femur. 9. Device (1) according to claim 1, characterized in that the balance (8) has orifices for guiding threaded pins (28) for fixing the balance (8) on the femur. 10. Device (1) according to claim 1, characterized in that the feeler (24) is in the form of a rod received in an upper orifice (25) that has the second slide (21), and with the capacity to parallel sliding and in the direction of the pads (4), the end of the rod being bent in the direction of the pads (4).