WO1996020656A1

WO1996020656A1 - Sliding knee prosthesis

Info

Publication number: WO1996020656A1
Application number: PCT/FR1995/001744
Authority: WO
Inventors: Jean-François JEANSON; Marc Ameil; Yves Catonne; Loup DE LEOBARDY; Francis DEMIGNEUX; Alain-Noël DUBART; Daniel LAJOIE; Arnaud LEGRAND; Pierre-Louis Peyrou; Yves THIRION
Original assignee: Jbs S.A.
Priority date: 1994-12-30
Filing date: 1995-12-27
Publication date: 1996-07-11
Also published as: ITMI952648A0; KR960020953A; BR9507119A; ITMI952648A1; ES2095813A1; GB2296443A; IT1277091B1; TR199501708A2; JPH09511675A; GB2296443A8; CA2166379A1; ES2095813B1; CN1137882A; GB9526267D0

Abstract

Sliding knee endoprosthesis comprising a femoral implant (1), a tibial implant (2) and a meniscal element (3) movable on the tibial implant. The femoral implant comprises two condyles (14, 15) whose bearing surfaces are spherical portions which articulate in the spherical cavities (31, 32) having the same diameter, on the meniscal element. The meniscal element is provided in several thicknesses. It is adaptable to the various sizes of femoral implants of which the condyles have the same diameter and the same spacing. In a postero-stabilized embodiment, a stud (4) fixed to the tibial implant comprises a spherical head (40) articulated in a hemispherical cavity (50) fixed between the femoral condyles. A cutting guide providing for the setting in place of the femoral implant comprises two positioning pins on the distal cut of the femur and slots for guiding a saw in order to make the back cut and the chamfers. The guide has also a plurality of guiding slots for the front cut, which are each adapted to a size of a femoral implant.

Description

SLIDING KNEE PROSTHESIS

The subject of the present invention is a sliding knee orthotic capable of being used as a posterior stabilized prosthesis, in particular in the case where it is used as a recovery prosthesis.

The knee prostheses known to date all include a femoral implant comprising two condyles and a trochlea, and a tibial implant whose plate is covered with a meniscal element, mobile or not, on which the condyles take a sliding support.

In order to be able to adapt a prosthesis to the anatomy of a patient, it is necessary to have femoral and tibial implants of different sizes.

In addition, in order to respect ligament tensions, it is essential to have meniscal elements of different thicknesses, which multiplies the number of pieces necessary for an intervention.

On the other hand, the knee joint can be subject to dislocations, or drawers, due to a certain laxity of the ligaments or to an accidental absence of these, in particular the posterior cruciate ligament.

The laxity of the ligaments is generally noted in the case of a resumption, that is to say during the placement of a prosthesis to replace another previously implanted.

To overcome the drawbacks of anterior drawers and lateral laxities, post-stabilized prostheses have been proposed, that is to say comprising, substantially in the center of the tibial plateau. a central lug against which abuts, during bending, a transverse piece positioned in the intercondylar notch. Prostheses of this type are described in documents US-A-950,298 and GB-A-1,067,412.

The Dostero-stabilized prostheses existing to date, however, only prevent the drawer anterior in flexion and are almost exclusively reserved for cases where the posterior cruciate ligament is aosent.

Prostheses have also been proposed, the tibial plateau of which has a substantially central location with a stud provided at its end with a sphere cooperating with a hemispherical cup placed in the femoral implant. Such prostheses, described in particular in documents US-A-3,868,730 and GB-A-2,088,724, however have drawbacks in terms of comfort and longevity.

Indeed, in the prosthesis which is the subject of document US-A-3,868,730, the joint is produced jointly on the one hand between the condyles and the meniscal plateau, and on the other hand between the sphere and the cup , which poses ligament tension problems, amplified when there is premature wear of one or the other of the friction surfaces.

The prosthesis described in document GB-A-2 088 724 uses a sphere only as a stop, the articulation being produced between the condyles and the tibial plateau. However, this prosthesis has the disadvantage of a possible phenomenon of shearing between the condyles and the plate during axial pivoting, leading to the risk of premature wear of the surfaces with friction. In addition, the flexion is limited because the cup is extended posteriorly to avoid a possible drawer in extension.

In addition, due to the non-constant ray of the condyles, it is necessary to specify a mobility of the spherical head, which is obtained by securing it to a piston, with the drawbacks of this type of device.

The aim of the present invention is to remedy these drawbacks by proposing a sliding knee prosthesis capable of being adapted to recovery and to postero-stability, making it possible to considerably reduce nominate him qe parts necessary for a surgical intervention.

A prosthesis according to the present invention, comprising a femoral implant, a tibial implant and a meniscal element, is essentially characterized, on the one hand in that the meniscal element comprises two spherical support cavities, and on the other hand that the femoral implant comprises two condyles whose bearing faces are spherical segments of distinct centers and of radius equal to that of the spherical cavities, said centers being spaced apart, whatever the size of said femoral implant, by the same distance, allowing that the meniscal element be, with the exception of the thickness, of constant dimensions whatever the size of the femoral implant.

According to an additional characteristic of the prosthesis according to the invention, the meniscal element comprises at its upper face, in its anterior central region, a stop having a superiorly inclined plane towards the rear against which comes to bear, when the knee is in extension, the base of the trochlea at the end of the intercondylar notch.

According to another additional characteristic of the prosthesis according to the invention, the tibial plateau has on its upper Diane face a frusto-conical projection which is housed in a cavity formed in the flat lower face of the meniscal element, allowing, depending on the dimensions and the form of said ca / ity, a pivoting in rotation or a free sliding movement of said memscal element on said tibial pediatric plate.

In a particular embodiment of the prosthesis according to the invention, a stud, the end of which is furnished with a spherical head, is placed on the tibial plateau in the central posterior region thereof, the center of said head spherical being aligned with the centers of the sheric segments constituting the support surfaces of the condyles; the meniscal plate, subject to said tibial olateau, being centrally secured to allow passage with clearance of said stud, while an insert comprising a hemispherical cavity in which takes place, without play, the spherical head of said stud, is introduced and fixed in the femoral implant between the two condyles, in the middle of the intercondylar notch.

According to a first variant of this embodiment of the prosthesis according to the invention, the cavity of the insert is retentive when the knee is in extension.

According to a second variant of this embodiment of the prosthesis according to the invention, the cavity of the insert is not retentive in extension, so as to allow a distal clearance of the femoral implant relative to the tibial implant .

The spherical head stud implemented in this embodiment of the prosthesis according to the invention can be secured to the tibial olateau by an assembly of the Morse cone type completed with a screw. in combination with an anti-pivoting lug.

The screw for fixing said olot to the tibial olateau also makes it possible to fix an intramedullary keel to said plate, said keel being of shape and dimensions adapted to the anatomy of the patient and to the quality of the bone material.

The fixation of the keel to the tibial plateau is then also ensured by an assemDiage of the Morse taper type supplemented by an anti-pivoting lug.

The prosthesis according to the invention offers the advantage, on the prostheses known to date, of having perfect congruence between the meniscal element and the condyles for flexion, and between the meniscal element and the tibial olateau for rotation.

It offers the additional advantage of making it possible to considerably reduce the number of rooms necessary for surgical intervention, since it requires only these femoral implants of different dimensions and meniscal elements which only differ in thickness.

The prosthesis according to the invention also makes it possible to limit the instrumentation, in particular by requiring only a single cutting guide, to the fact that. whatever the size of the femoral implant, the anchoring studs of the latter are equidistant, while the posterior cut and the chamfer are the same, only the height of the anterior cut being variable.

In the most simole configuration of the prosthesis according to the invention, the dimensions and the shape of the lower cavity of the meniscal element are different from those of the frustoconical projection of the tibial plateau, which allows a displacement of said meniscal element over ' he tibial plateau, while retaining a perfect congruence of the meni scal element with the condy s of a part and with the tibi al plate on the other hand.

The postero-stability of the prosthesis according to the invention is obtained by using a meniscal plate whose lower cavity is of dimensions and shape corresponding to the truncated projection of the tibial plate, which only allows the pivoting of the mehiscal element around said projection.

In the case of a revision prosthesis, that is to say comprising a stud with a spherical head and an insert, the articulation is produced on the one hand between the concvies and the meniscal element and on the other hand between the head spnerique and insert.

The cross of the cavity of the insert, resounding or not, is a function of the state of the ligaments, a retentive cavity allowing the insert and the spherical head to act like a ball joint, preventing any dislocation.

The advantages and features of the The present invention will become more apparent from the description which follows and which relates to the attached drawing, which represents several non-limiting embodiments.

In the attached drawing:

FIG. 1 represents a front view of a prosthesis according to the invention, in the flexion position at 90, on which several femoral implants of different dimensions have been shown.

- 1a 2 shows a side view of the same prosthesis.

FIG. 3 shows in front view a representation of several superimposed femoral implants of

The same prosthesis.

FIG. 4 shows the same representation in profile view.

FIG. 5 represents a view from above of a meniscal element of a prosthesis according to the invention.

- 1a Figure 5 shows a top view of a variant of the same meniscal element.

- 1a Figure 7 shows a rear er er exploded view of a prosthesis according to the invention in its postero-stabilized version.

- 1a Figure 8 shows a view of Drofil and exploded, with partial sections, of the same prosthesis.

FIG. 9 represents a side view, with partial sections, of the same protesis in an extended position.

FIG. 10 represents a side view with partial sections of the same protesis in the flexior position at 90.

FIG. 11a represents a plan view of a meniscal element of the oresis represented in FIG. 7.

- 1a Figure 11b shows a view of a tibial pediatric: equipped with the same meniscal plate. - 1a Figure 11c shows a clan view of the same tibial plateau equipped with the same meniscal plateau in a different position.

Figures 12a and 12c respectively show a side view and a plan view of a first embodiment of the keel of the tioial implant of the prosthesis according to the invention.

Figures 13a and 13D respectively show a side view and a plan view of a second embodiment of the keel of the tibial implant of the prosthesis according to the invention.

Figures 14a and 14b respectively show a rear view and a plan view of a third embodiment of the keel of the tibial implant of the prosthesis according to the invention.

FIG. 15 represents a profile view of a cutting guide allowing the fitting of a prosthesis according to

The invention.

FIG. 16 represents a front view of the same cutting guide.

If we refer to Figures 1 and 2 we can see that a prosthesis according to the invention comprises a bicondylar femoral implant 1, a tibial base 2 with a keel 20, and a meniscal element 3.

The femoral implant 1 has two condyles 10 and

II separated by an intercondylar notch 12, and extended by a trochlea 13.

The bearing faces 14 and 15 of the ccndyles, respectively 10 and 11, have a certain curvature in the longitudinal direction and another in the transverse direction, these curvatures being of constant and identical radius P, so that the bearing faces 14 and 15 are spherical segments with centers a and b respectively.

Figures 3 and 4, where these overlays of three femoral implants 1 of sizes are represented different, allow to better understand that the bearing surfaces 14 and 15 of the condyles, respectively 10 and 11, are, whatever the size of the femoral implant 1, spherical sectors of two soheres A and B of center respectively a and B.

The meniscal element 3, placed on the plate 21 of the tibial base 2, has in its upper face 30 two spherical cavities 31 and 32 of the same radius R, intended to receive the condyles, by sliding support 10 and 11 respectively.

This results in perfect congruence of the condyles 10 and 11 with the meniscal element 3, whatever the angle of flexion.

In FIGS. 1 and 2, four femoral implants 1 of increasing sizes are represented. This difference in size results in an enlargement of the trochlea 13 and condyles 10 and 11 by external lateral extensions, respectively 17 and 18, while the distance which separates the centers a and b from the spherical segments formed by the faces of support 14 and 15, remains identical regardless of the size of the femoral implant 1, which makes it possible to use the same meniscal implant 3.

It will also be noted that the anchoring dots 10 ′ and 11 ′ of the femoral implant 1 are, whatever the size of the latter, of identical center-to-center and positions, and that the necessary posterior cut and cenfrein are the same, and that only the height of the anterior cut varies, which will be described more precisely with FIGS. 15 and 16.

For example, the installation of a current prosthesis requires for fear a patiert of a given size, four femoral implants of different dimensions, a tibia1 implant and meniscal implants with the corresponding dimensions and in five different thicknesses, ie in total twenty -five pieces, while a prosthesis according to the invention requires only di, scit four femoral iriplants, a tibial implant and 5 mem seauk elements which differ only in thickness.

On the other hand, it can be seen in FIGS. 1 and 2 that the tibial plateau 21 includes, above the anterior central region, a frustoconical projection 22, which makes it possible either to fix the meniscal element 3 or to limit its displacement , according to the transverse dimensions and the shape of the cavity 36 formed in the meniscal element 3 and in which the frustoconical projection 22 is housed, as shown in FIGS. 5 and 6.

FIG. 5 represents a meniscal element 3 whose cavity 36 is of shape and dimensions corresponding to the frustoconical projection 22, so that the movement of the meniscal element 3 on the tibial plateau 21, not shown, is limited to pivoting, for a posterior stabilized prosthesis for example.

FIG. 6 represents a meniscal element 3 whose cavity 36 is of dimensions much greater than those of the frustoconical projection, which allows the translation of the meniscal element 3 on the tibial plateau 21, not shown.

It can also be seen in FIGS. 1 and 2 that the meniscal element 3 comprises, above the front part of the notch 33, a stop 34 having a tilted plane 35 above, against the base comes to rest on the base 19 of the trochlee 13 at the bottom of the notch i ntercondy 1 i enne 14 when the knee is extended, in order to prevent a possible "anterior drawer.

If we now refer to Figures 7 and 8, we can see that, in the case of a response, on the olateau 21 of the tibial base 2 is fixed a plct 4 whose free end is provided with a head spherical 40.

The connection of the stud 4 to the plate 21 is carried out on the one hand by interlocking, on the projection frustoconical 22 of the plate 21, of an anterior extension 41 of the stud 4 which for this purpose i nfen ejrement a frustoconical cavity 42, and on the other hand by a screw 43 tightened in a tapped hole 23, which also allows the fixing αe the keel 20 which is attached.

In order to avoid pivoting of the stud 4, a lug 44, projecting under the stud 4, is introduced into a hole 25 made in the upper face 24 of the plate 21 in its rear central region.

It should be noted that the plate 21 may not have a hole 25, in which case the lug 44 is positioned at the rear end of the pad 4 and fits into the notch of the plate 21 in order to prevent the pivoting of the pad 4 .

The meniscal element 3, as can be seen more precisely in FIGS. 11a, 11b and 11c, has a central rear notch 33 allowing the passage of the stud 4 and separating the two spherical cavities 31 and 32.

The notch 33 is such that there is a certain clearance between the stud 4 and the meniscal element 3, so that the latter can slide on the plate 21 and pivot around the extension 41 with a degree of freedom of the order 10 °, as shown in Figure 11c.

In FIGS. 7, 8, 9 and 10, it can be seen that between the condyles 10 and 11 of a femoral implant 1 ′, opposite the intercondylar notch 12, is introduced and fixed by suitable means, not shown. , an insert 5 comprising a hemispherical cavity 50 intended to accommodate the spherical head 40 of the stud 4. the center o of this hemispherical cavity 50 being aligned with the centers of the spherical segments which form the bearing surfaces 14 and 15 of the condyles 10 and 11.

As can be seen in FIG. 5, the cavity 50 is not retentive, that is to say that the introduction of the spherical head 40 is produced in the axis of the femoral implant 1 ′, so that there can be a distal play in extension.

However, in a variant, not shown, the cavity 50 is retentive in extension, that is to say that the spherical head 40 is introduced posteriorly into the cavity 50 when the knee is in flexion, so that the head 40 and insert 5 act as a patella, maintaining the femoral implant 1 'and the tibial implant 2, which is possible due to the alignment of the centers a, b and c.

The configuration of the prosthesis can be improved by choosing a keel that best suits the patient's anatomy and the state of the bone material.

The choice of keel can be made from those shown in Figures 12a, 12b, 13a, 13a, 13b, 14a and 14b.

In these figures, it can be seen that the ground i dan sation of the pins 200, 201 and 202 to the tibial plateau 21, visible only in FIG. 12a, is produced by interlocking of the Morse cone type completed by a tightening screw and a anti-pivoting lug 203.

In FIGS. 12a and 12b we can see a keel 200 of generally square cross section, laterally having longitudinal ribs 204.

In Figures 13a and 13b we can see a keel 201 of round cross section of decreasing diameter from top to bottom, and whose surface is striated with grooves 205, not shown in Figure 13a, whose depth is constant.

In FIGS. 14a and 14b, a keel 202 should be seen comprising a substantially cylindrical body 206 comprising radially three wings, two lateral wings 207 and a rear wing 208, the lateral wings 207 each forming an angle of 70 with the rear wing 208 °, the wings 207 and 208 being of decreasing width from top to the bottom, the rear wing 208 being narrower than the lateral wings 207.

If we finally refer to FIGS. 15 and 16, we can see a cutting guide 6 allowing the anterior and posterior cuts and the chamfer to be made for the placement of the femoral implant 1 whatever its size, different sizes being shown in Figure 15.

The cutting guide 6 comprises on the one hand two rods 60 and 61 for positioning, or holes allowing the insertion of pins, intended to be introduced into the bores provided for housing the anchoring pads 10 ′ and 11 ′ of the femoral implant 1, and on the other hand, to guide the saw, slots 62, 63 and 64 for the posterior cut and the chamfers, and three slots 65, 66 and 67 for the anterior cut for three sizes of femoral implant 1, the upper edge 68 serving as a guide for a fourth size.

Claims

1) Sliding knee prosthesis comprising a femoral implant, a tibial implant and a meniscal element. characterized on the one hand in that the meniscal element (3) comprises two spherical support cavities (31, 32), and on the other hand in that the femoral implant (1) comprises two condyles (10, 11 ) whose bearing faces (14, 15; are spherical segments of separate centers la, b) and of radius (R) equal to that of these spneric cavities (31, 32), said centers (a, b) being separated , whatever the size of said femoral implant M), oe the same distance, allowing the meniscal element (3) to be, with the exception of the thickness, of constant dimensions regardless of the size of the femoral implant (1).

2) Prosthesis according to claim 1 characterized in that the anchoring studs (10 ′, 11 ′) of the femoral implant (1 have the same distance and the same dosages whatever the size of the femoral implant

(1).

3) Protnesis according to claim 1 or claim 2 characterized in that the anterior cut and the chamfers necessary for the establishment of the femoral implant (1) are identical as is the size of said femoral implant (1), only the depth of the previous cut being variable.

4) Prosthesis according to any one of the preceding claims, characterized in that the meriscal element (3) has on its upper face, in its anterior central region. a stop (34. presenting above an inclined plane (35) center which comes to bear, when the knee is in extension, the box

(15) of the trochlee (13) at the end of the intercondylar notch (12).

5) Prosthesis if one conquers these previous claims characterized in ow due to the tibial plateau (21) has on its upper side olane (24) a frustoconical projection (22) intended to be housed in a space (36) formed in the flat lower face 30; meniscal element (3).

6) Protnesis according to claim 5 characterized in that the qimensions of the cavity (36) of the meniscal element (3) are greater than the dimensions ee the frustoconical projection (22) of the tibial plateau (21), so as to allow a free movement sliding to said meniscal element (2) on said tibial plateau (21).

7) Prosthesis according to claim 5 characterized in that the shape and dimensions of the cavity (36) of the meniscal element (3) correspond to the shape and dimensions of the frustoconical projection (22) of the tibial plateau (21) , so as to allow only the pivoting in rotation of said meniscal element (3) on said tibial plateau (21).

8) Prosthesis according to any one of claims 1 to 4 characterized in that on the one hand a stud (4), the end of which is furnished with a sonéπque head (40), is fixed on the tibial plateau ( 21) in the central posterior region thereof, the center (c) of said spherical head (40) being aligned with the centers (a, b) of the spherical segments constituting the appul surfaces (14, 15) of the condyles (10, 11); on the other hand the meniscal plate (21), subject to said tibial olateau (21), is swapped centrally to allow passage with clearance to said olot (4); and on the other hand also an insert (5), comprising a hemispherical cavity (50) in the channel takes place, without play, the spherical head (10) of said stud (4). is inserted and fixed in the femoral implant (11) between those condyles (10, 11), opposite the intercondylar notch (12).

9) Prosthesis according to claim 6 characterized in that the cavity (50) of the insert (5) is retentive when the knee is in extension, the head spherical (40) being introduced posteriorly into the insert (5).

10) Prosthesis according to claim 8 characterized in that the cavity (50) of the insert (5) is not retentive when the knee is in extension so as to allow a distal play, the spherical head (40) being introduced in said insert (5) in the axis of the femoral implant (1 ').

11) Prosthesis according to any one of claims 8, 9 and 10, characterized in that the stud

(4) is secured to the tibial flag (21) by an assemDiage of the Morse taper type completed by a screw (43), associated with a lug (44) anti-pivoting.

12) Prosthesis according to any one of claims 8 to 11 characterized in that the notch

(33) of the meniscal element (3.) is of dimensions such that there remains a certain clearance between the stud (4) and the meniscal element (3), so that said meniscal element (3) can slide on the tibial plateau (21) and pivot around the stud (4) with a degree of freedom of the order of 10.

13) Prosthesis according to any one of the preceding claims, characterized in that the keel (200, 201, 202) of the tibial implant (2) is secured to the tibial plateau (21) by an assembly of the Morse cone type supplemented with a clamping screw and a pin (203) anti pi vote.

14) Cutting guide allowing the placement of the femoral implant (1) of the prosthesis according to any one of claims from 1 to 7, characterized in that it comprises two positioning rods (60, 61), and slots (62, 63, 54) for guiding a saw for making the rear cut and the chamfers, and slots (65, 65, 57) for guiding the saw for making the front cut in depending on the size of said femoral implant (1).