JPH0360653A - Tibial element for exchangeable, artificial knee - Google Patents

Abstract

PURPOSE: To make it possible to use together with the natural condylar pivotal face of cooperating thighbone or the artificial condyle presented by artificial thighbone by alternating offset of a middle sideways direction and back and forth directions, frontal and rear slanting, rotation of the tibia or the shape of the tibia condylar hollow. CONSTITUTION: The artificial knee is composed of a tibia tray 1 having an upper tray part 2 and a device to joint the tibia tray with the tibia presented by a spigot 3. This kind of trays usually has the raised up tray walls 5. Inside of the upper tray part 2 is placed a pivot element 6 equipped with two formed pivotal faces 7, in which the pivotal faces fit the condyle of the thighbone cooperating as a hollow. Natural or artificial condyle is applied to such a condyle when applied onto the cooperating artificial highbone element. The pivot means 6 is made available to either press into between the tray walls 5 or snap engage onto a specified position by means of a screw, peg or other optional means which is desirable free to move off after application. This means is generally made of synthetic plastic material.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field] The present invention relates to a tibial element for a replacement knee prosthesis. Can be used in conjunction with other types.

[Conventional technology]

Tibial components are available including metal tibial basins with removable and interchangeable bearing surface elements of synthetic plastic material of different thicknesses, with alternating bearing surfaces to achieve precise UJ band tension. provided.

The femoral component of the cosmetic-only replacement prosthesis is primarily positioned and oriented relative to the bone itself. There are three types of medial position variables: anteroposterior, lateral, and vertical, and three orientation variables: flexion/extension, clubfoot/valgium, and femoral axis centerline. There is a rotation around the . Furthermore, the shape of the tibial recess influences the stability and trajectory of knee motion.

The tibial component is similarly positioned and oriented relative to the tibia.

Once these elements are in place, the only way a surgeon can currently adjust the knee is by selecting bearing surfaces of different thicknesses to create the desired ligament tension, or by removing the elements and re-skating the bone. It is done.

Adjustments are therefore not easily made if the surgeon realizes that he has made a mistake or changes his mind about optimal knee alignment; Force a compromise in directional positioning. The fixation must be at or close to the lateral skin wall of the bone, which does not lend itself to an ideal location relative to the bearing surface.

[Problem to be solved by the invention]

The present invention provides a device that allows the surgeon to change the alignment of the knee during surgery.

According to the invention, the tibial component of the replacement prosthesis includes a tibial basin connected to a suitably prepared tibia, an upper surface of said basin having one or more bearing elements, and one or more of the following variables: Lateral offset, anteroposterior offset, anteroposterior tilt,
It includes a device that changes the position of the tibia relative to its cooperating femur by alternating the rotation of the tibia or the shape of the tibial depression.

Devices that vary combinations of two or more types of offset or inclination may also be included.

Preferably, the device for changing the relative position of the tibia with respect to its cooperating femur includes two or more alternating bearing elements, one or more of the bearing elements being selectable and positionable within the tray. Possibly, the bearing element has alternating shaped and/or positioned bearing surfaces to accommodate the cooperating natural condyle or prosthesis of the femur.

Preferably, standard neutral support elements are also included if no modifications are required.

Preferably, the separate bearing element provides variation in at least the mid-lateral and anteroposterior slopes, which are the two most common variables required.

If desired, this assembly can include bearing elements for all variable variables or combinations thereof.For example, it can include elements that not only include a medium lateral offset but also include a medium lateral slope. It will be appreciated that combinations of two or more variables can be introduced.

SUMMARY OF THE INVENTION In one preferred embodiment, the tray has a single bearing element with two shaped bearing surfaces and another unit with bearing surfaces of different shapes and/or locations. Modification is provided by one element.

In another embodiment according to the invention, the tray has two bearing elements, each bearing element having a mono-molded bearing surface for cooperating with a single condyle on the cooperating femur. . Each element has at least two bearing surfaces of different shapes and/or positions.
are independently selectable from one alternating element to the other.

Therefore, once the bone has been implanted, the surgeon can take measurements of the fixation element on the femur and the tibia, or perform X-ray or computer-aided tomographic scans to check for accurate joint motion and soft tissue tension. Supporting elements can be selected. Thus, a reliable implantable bearing element can be installed.

While the invention may be embodied in various ways, one embodiment will now be described, by way of example only and with reference to the accompanying drawings, in which: FIG.

〔Example〕

FIGS. 1, 2 and 3 show a replacement prosthesis from a tibial tray 1 with an upper tray portion 2 and a device for connecting the tibial tray to a suitably prepared tibia provided in the Svigot 3. This type of basin, representing the tibial element, is well known in itself and usually has a raised basin wall 5. In the upper tray-shaped part 2 a bearing element 6 is installed which is provided with two bottom-shaped bearing surfaces 7, which are in the form of depressions and adapted to the cooperating condyles of the femur. Such a condyle, when placed on a cooperating prosthetic femoral component, may be a natural condyle or an artificial condyle. The support element 6 can be press-fitted between the basin walls 5 or snap-fitted or held in place by any other device, such as screws or pegs or other devices, which can be subsequently installed later. , it is desirable that it be removable. This element is usually made of synthetic plastic material.

The configuration and location of the bearing surfaces represent optimal knee alignment.

It is known to provide a bearing element, as shown in FIG. 9, where like reference numerals are used to indicate like parts. In Figure 4, the standard element depth is indicated by the dotted line 8.
It will be appreciated that the thickness of the element shown in FIG. 9 is somewhat increased.

After a tibial element of the type shown in FIG. 1 has been installed, one way in which a surgeon prior to the present invention could adjust the knee was to install a bearing element 9 shown in FIG. 9 to create the desired ligament tension. The purpose was to replace the bearing element 6 shown in FIG. The only other alternative is to remove and bone these elements. Therefore, if the surgeon realizes that he has made a mistake or changes his mind about optimal knee alignment, he cannot easily perform Hlff, as shown in Figure 6, to provide another modification in the mid-lateral slope. It is proposed to provide a bearing element, the bearing surface being designated with reference number 15 and the original standard bearing surface being designated again with reference number 7.

However, the present invention provides a number of alternative bearing elements that can be inserted into the upper tray portion 2 to replace the standard bearing element 6 and allow relative adjustment of the tibia to the femur. FIG. 4 shows a bearing element 1o which is similar in general shape to bearing element 6, the bearing surface designated by reference numeral 11 being provided with a medium lateral offset. The position of the standard bearing surface is indicated by reference numeral 7 in dashed lines. This moderate lateral offset is extremely important for establishing knee alignment.

FIG. 5 shows the bearing element 12 and the bearing surface 13 offset in the anteroposterior direction, which is also an important modification in providing optimal knee alignment. Once again, the position of the standard bearing surface is indicated in dashed lines by reference numeral 7.

FIG. 7 shows a bearing element 16 in which the bearing surface 17 introduces an inclination in the longitudinal direction. In this case too, the standard bearing surface 7 is shown in broken lines.

The bearing element 18 shown in FIG. 8 is provided with a bearing surface 19 that provides tibial rotation to accommodate valgus, metatarsal varus or splayed toes, and which provides optimal knee alignment. This is an important aspect of

FIG. 10 shows a bearing element in which the bearing surface 21 is of a different shape from the standard bearing surface, also indicated by reference numeral 7. The bearing surface 21, which provides a tibial depression, influences the stability of the knee and the trajectory of knee motion. Thus, they can have different shapes which influence, for example, the height of the outer rim at different positions and the shape slope which brings about the desired effect. As shown in FIG. 10, another alternative shape is shown with dashed lines 22 providing a high rim for a deep recess.

A kit for making a tibial element according to the invention can incorporate the alternative bearing elements shown in the drawings, preferably comprising at least two of them, and, of course, also the standard bearing element 6.

Perhaps the most important alternative bearing elements are medium lateral slope and anteroposterior slope, as these two variables tend to be the most common, and are shown in Figures 6 and 7 to accommodate these two variables. The element shown.

Two of the alternative bearing surface configurations can be introduced simultaneously and other or alternative bearing elements can be provided. Accordingly, an element can be provided that introduces not only the mid-lateral offset shown in FIG. 4, but also the tibial rotation shown in FIG.

The same element can also be provided in different thicknesses as shown in FIG. It will be appreciated that there are many combinations that can be provided and used for a particular element. FIG. 11 is a plan view showing a combination of mid-lateral offset and tibial rotation. The dimensions have been enlarged to make them more clear.

As can be seen from the drawings, the tray is substantially rectangular in plan, and under certain circumstances modifications can be provided by reversing the bearing element 6. Accordingly, FIG. 12 shows the same elements as FIG. 4, but inserted in the opposite direction so that the medium lateral offset shown on the right side of FIG. 4 appears on the left side. This reversal is possible due to the symmetrical shape of the tray and can be employed with other inserts.

13, 14 and 15, these three top views show alternative tray shapes, in each case with an insert 30 supported within a flanged tray 31. In FIGS. The bearing surface 32 is shown in a neutral position in FIG.
In FIG. 14 it is shown in the toe medial position and in FIG. 15 it is shown in the toe medial position. Again, these structures can also introduce one or more other configurations, such as anteroposterior offsets and alternative depths.

For the structure described above, a considerable number of modifications and different dimensions and configurations can be made, and FIGS. 16-23 show alternatives that provide easy modification at reduced cost to the extent that the range of the insert can be reduced. It will be understood that the structure of

In this type of construction, the tibial basin l is
1 has been replaced by an element with an upper tray-shaped head 40 connected to 1. There are two spaced depressions 42 on the top of the tray.
．． 43, the recess is generally oval in plan and has a pair of bearing elements 44 within the recess.
．． 45 can be snapped into place. For example screws or pegs or other devices could be employed to hold the bearing elements 44,45 in place. Again, the components will usually be made of synthetic plastic material.

Figures 16, 19 and 20 show a standard insert with the bearing surface in a neutral or standard position. FIG. 17 shows an insert shaped to provide a medium slope in one direction, and FIG. 18 shows a slope in the other direction.

This inclination may be achieved by a higher insert 46 instead of the standard insert bearing element 44 or by a standard insert 4.
5 can be provided by a shorter insert 47. Thus, on one side there is a standard insert bearing element 44.
．． A modified insert can be employed on the other side employing 45, and various such combinations can be achieved as desired.

In Figures 21 and 22, the bearing surface is shaped and positioned to provide rotation of the tibia. Accordingly, FIG. 21 shows an inverted toe with appropriate inserts 48 and 49. The amount of inward toe could be reduced by using a standard insert bearing element 45 instead of insert 49. Similarly, in Figure 22, insert 49 can be placed in place of insert 48, with insert 48 replacing insert 49 to provide structure for the outward toe. FIG. 20 shows insert bearing elements 44 and 45 which provide a neutral position.

Although a range of inserts can be provided for the mid-offset and lateral offset and other variations described above with respect to the first type of configuration, for this arrangement the number of inserts required is as well as on the opposite side of the tray head 40.
It will be appreciated that due to the oval shape of the recess 43, which allows it to be installed in reverse positions, these inserts can normally be rotated to opposite positions, thereby reducing the number of inserts.

In this case too, each insert bearing element 44 and 45 can incorporate more than one variant; FIG. 50 is shown. However, in this insert,
The bearing surface 51 is provided with not only a longitudinal offset but also a longitudinal inclination.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional front view of a prosthetic neutral tibial element for a replacement knee prosthesis. 2 is a cross-sectional side view of the element shown in FIG. 1; FIG. FIG. 3 is a plan view of the elements shown in FIG. 1; FIG. 4 is a cross-sectional front view of another bearing element configured to provide a medium lateral offset; FIG. 5 is a cross-sectional side view of the bearing element in which an anteroposterior offset is introduced. FIG. 6 is a cross-sectional front view of a bearing element with a medium lateral inclination introduced; FIG. 7 is a cross-sectional side view of a bearing element with an inclination in the longitudinal direction. FIG. 8 is a plan view of the bearing element through which rotation of the tibia is introduced. Figure 2 is a cross-sectional front view of a known type of bearing element of variable thickness for adjusting the height of the joint; FIG. 1O is a cross-sectional front view of a bearing element in which a differently shaped tibial condyle recess is introduced. Figure 1r is a plan view of an alternative structure. 12 is a cross-sectional front view of the bearing element positioned within its tray in the opposite direction shown in FIG. 4; FIG. Figures 13, 14 and 15 are plan views of alternative tray shapes. FIG. 16 is a cross-sectional front view of an alternative structure. Figures 17 and 18 show the first bearing insert having an alternative bearing insert.
FIG. 7 is a cross-sectional front view of the structure shown in FIG. 6; FIG. 19 is a cross-sectional side view of the structure shown in FIG. 16. 20, 21 and 22 are plan views of the structure shown in FIGS. 16 and 19 with alternative bearing inserts. FIG. 23 is a side view of an insert with two variables. 1: Tibial basin, 2: Upper basin-shaped portion 6.9.
10.12, 16, 18, 44, 45: Supporting element? ,
11.13.15.17.19,21,32.51
: Bearing surface.

Claims (1)

Claims: 1) A tibial element for a replacement knee prosthesis, consisting of a fibular basin connected to an optimally prepared fibula, the upper surface of said basin having the following variables: medium lateral offset, anteroposterior directional offset,
one or more bearing elements provided with a device for alternating the position of the tibia relative to its cooperating femur by alternating one or more of anteroposterior tilt, tibial rotation, and tibial condylar depression shape; Replacement prosthetic knee tibial element with. 2) The tibial component of claim 1, including a device for changing the combination of either said two offsets or inclinations. 3) said device for changing the relative position of the tibia with respect to its cooperating femur includes two or more alternating bearing elements;
a bearing in which one or more such bearing elements are selectable and positionable within the tray, said bearing elements being alternately shaped and/or positioned to receive the natural or artificial condyles of the femur with which they cooperate; The tibial element of claim 1 having a surface. 4) The tibial element of claim 3, wherein the alternating bearing elements alternate at least a moderate lateral slope and an anteroposterior slope. 5) The tibial element of claim 1, comprising bearing elements providing alternating medial lateral inclination and/or vertical offset. 6) The tibial element of claim 5, wherein alternating bearing elements are provided for all alternating variables or combinations thereof. 7) The tibial element of claim 3 comprising a standard neutral bearing element. 8) The basin bears a single bearing element with two shaped bearing surfaces, and modified configurations are provided by alternating single elements having bearing surfaces of different shapes and/or positions thereon. A tibial element according to claim 3. 9) The tray has two bearing elements, each bearing element having a bearing surface shaped to cooperate with a cooperating condyle on the femur, each element having a bearing of a different shape and/or position. 4. The tibial element of claim 3, wherein the tibial element is selectable from at least two alternating elements having faces independently of the other element.