DE8136619U1 - Prosthesis for a knee joint - Google Patents

Description

Boehmert & Boehmert, P.O. Box / P. O. Box 10 71 27. D-2800 Ba-men

To the

German Patent Office Zweibrückenstr. 12th

8000 Munich 2

PATENT LAWYER DR-ING. KARL BOEHMERT (1933-1973) PATENT Attorney DIPL.-ING. ALBERT BOEHMERT, BREMEN LAWYER WILHELM J. H. STAHLBERG. BREMEN PATENT ADVOCATE DR.-ING. WALTER HOORMANN. BREMEN PATENT ADVOCATE D1PL.-PHYS. DR HEINZ GODDAR BREMEN PATENT Attorney DIPL-ING. EDMUND F. EITNEK MUNICH LAWYER WOLF-DIETER KUNTZE, BREMEN LAWYER DIPL.-ING. JAN TÖNNIES, BREMEN

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O 225

Bremen, Hollerallee 32

December 16, 1981

Orthoplant Orthopädische Implantate GmbH & Co. KG, Leerkämpe 12, 2 800 Bremen 66

Prosthesis for a knee joint

The invention relates to a prosthesis for a knee joint, with a tibial bearing arranged on the tibial head for Positioning of the natural or artificial end of the thigh bone facing the knee.

Knee joint prostheses are total endoprostheses, sled prostheses, etc. in a wide variety of designs known, the application of a certain design of various factors, in particular also the type of clinical picture, i.e. the type of a certain fracture, the stage of wear and tear or a deformation etc. depends.

The design of knee joint prostheses has been compared

512
Bremen / Bremen Office:

P.O. Box 10 71 27 Hollerallee 3Z D-2800 Bremen 1 Telephone: (0421) * 34 90 71 Telecopier / Telecopier CCITT 2 Telegr. / Cables: diagram Bremen Telex: 244 958 bopald

Accounts Bremen: Bremer Bank. Bremen
(BLZ 290 800 10) 100 144 900 Deutsche Bank. Bremen
(Sort code 290 700 50) 111 2002

pSrJiA «kriiburg '··'

fBLZ 200100 20) 1260 83-202

Munich Office / Munich Office {nurPaiaiüum-ä

Postfach / P.O.Box 22 0137 SchlotthauerstraRc 5. D-8000 Munich 22 Telephone: (0S9) 22 3311 Telecop .: (089) 2215 69 CC1TT2 Telegr./Cables: Forbopat Munich Telex: 524 282 fort »d

BOEHMDERT

with other joint prostheses, for example hip joint prostheses, causes particular difficulties from the start, because it is the natural movement of the interacting bone ends in the knee area is a kinematically particularly complex movement in which a rolling movement is a Sliding movement is superimposed.

There is also the fact that the knee joints are exposed to particularly high loads, since they not only due to the weight of a person and their load, for example when carrying loads static forces, but also when walking and especially jumping or the like. occurring dynamic Have to absorb loads.

Commonly known total or partial knee joint prostheses have the disadvantage that their damping properties and their elastic properties are not yet satisfactory compared to the natural conditions, regardless of whether only the tibial head with a partial. prosthesis is provided, while the one with the Tibial head cooperating end section of the femur is still the natural tissue, whether this Bone end is provided with a shell partial prosthesis that interacts with the tibial prosthesis bearing, or whether it is a total endoprosthesis.

The present invention is accordingly based on the object of the known knee joint prostheses or partial prostheses to improve so that their elastic and / or damping properties compared to the previously known Knee joint prostheses are considerably improved.

BOEHMERT

The solution to this problem is characterized according to the invention by an elastic and / or damping buffer layer, such a buffer layer being practical in every configuration of a knee joint prosthesis at a suitable location and in a suitable configuration can be provided.

In a preferred embodiment of the present invention, the buffer layer, which is preferably made of Silicone or the like. consists, part of the prosthetic ^ tibial bearing.

To the buffer layer according to the invention in particular To be able to keep such a configuration in an optimal manner and to allow it to take effect is preferred provided that the buffer layer between a lower bearing plate to be attached to the tibial tissue and an upper bearing plate which is held in a suitable manner on this is arranged, the two bearing plates preferably at the one facing the buffer layer Side are formed essentially flat and in such a configuration then preferably also the Buffer layer an essentially flat top and bottom and thus an essentially uniform thickness having, the buffer layer having a plurality of through openings to improve the elastic or buffer properties can be provided, which is particularly preferred in the load area, i.e. in the middle area the buffer layer can be arranged essentially distributed over the buffer layer.

Has on its upper side facing away from the buffer layer the upper bearing plate, which is also preferably made of _ a fabric-compatible plastic such as polyethylene

BQKHNiERT "&

stands, on the other hand a concave curved recess, while the lower bearing plate, which is preferably made of a tissue-compatible metal, is preferably attached to it Underside has approaches by means of which it is cemented into the tibial tissue and in this way on this is to be held tightly.

In order to take into account the desired elastic and damping effects of the buffer layer, according to the invention provided that the upper bearing plate - and thus C the buffer layer arranged below it - in the normal direction, i.e. in the longitudinal direction of the bone, held to a limited extent movably and positively on the lower bearing plate is. For this purpose, there is preferably a bearing cage that is connected to the lower bearing plate and that has at least the upper Surrounding part of the lower bearing plate, the buffer layer and the lower part of the upper bearing plate in a ring shape and has at least one portion that positively holds the upper bearing plate. In this section it is preferably an inwardly directed one arranged at the upper end section of the bearing cage Flange, with the upper bearing plate preferably at its lower portion in such a configuration a radially outwardly protruding flange or the like. may have which overlapped by the flange of the bearing cage is, then between the top of the bearing cage flange and the top of the flange of the upper bearing plate in the loaded state when the buffer layer is compressed a certain amount of play arises, as will be explained in detail below.

Preferred embodiments of the present invention are described in the subclaims.

BOEHMEKF &

The invention is further explained below using an exemplary embodiment with reference to a drawing. It shows:

1 shows a side view of a knee joint prosthesis according to the invention in the direction of of the arrow I seen in Fig. 2;

Fig. 2 is a somewhat enlarged

Front view of the prosthesis according to Figure 1 in section;

3 shows an enlarged illustration of the one in FIG. 2 with a dash-dotted line Circle framed part of the tibial bearing marked III;

4 shows a side plan view of the lower bearing plate of the tibial bearing in the direction of the arrow IV seen in Fig. 5;

FIG. 5 shows a view of the tibial bearing according to FIG. IV in the direction of arrow V. FIG seen in Figure 4;

6 shows a plan view of the lower bearing plate of the tibial bearing according to FIGS. 4 and 5 seen in the direction of arrow VI in Fig. 4;

Fig. 7 is a side view of the buffer layer;

8 is a plan view of the buffer layer

7 in the direction of arrow VIII in FIG. 7;

FIG. 9 shows a side view of the upper bearing plate in the direction of the arrow TX in FIG. 10 seen;

10 is a front view of the upper bearing plate in the direction of arrow X in FIG Fig. 9 seen;

11 is a plan view of the lower bearing plate seen in the direction of arrow XI in Fig. 9;

Fig. 12 is a side view of the bearing cage

' : - B0EHM EFST. & BOEHMERT

in the direction of arrow XII in FIG

seen;

13 shows a front view of the bearing cage according to FIG. 12 in the direction of the arrow XIII seen in Figure 12;

14 is a plan view of the bearing cage

.) according to the. 12 and 13 ~ .p, direction

of the arrow XIV in "ia. -? seen;

and

15 is an exploded view of the tibial bearing.

The drawing shows an embodiment of the knee joint prosthesis according to the invention on the Bed game of a sled prosthesis. In particular from FIGS. 1 to 3 it can be seen that the tibial head of the lower leg bone to Recording of the tibial bearing designated as a whole with 2 has been treated so that it is in the area of the tibial

bearing 2 has a substantially flat, horizontal surface.

The tibial bearing 2 consists essentially of four parts, namely a lower bearing plate 3, an upper bearing plate 4, one between the lower bearing plate 3 and the buffer layer 6 arranged on the upper bearing plate 4 and a bearing cage 7.

The lower bearing plate 3, which can also be seen in particular in FIGS. 4 to 6, consists of a tissue-compatible one Metali and has a flat surface 8. Extend from the underside of the lower bearing plate 3 two webs 9 and 10 down, each provided with bores 12, in which later cancellous bone grows in or first gets when attaching the lower bearing plate 3 bone cement, with which the lower bearing plate 3 is anchored to the tibial head during the operation.

BQEHMERT

As can be seen in particular from FIGS. 4 to 6, on the end face 13 of the lower bearing plate 3 Bores 14 formed, which receive 2 pins 16 in the assembled state of the tibial bearing (see Fig. 2, 3), by means of which the bearing cage 7, described in detail below, with the lower bearing plate connected.

The buffer layer 6, which can be seen in particular from FIGS. 7 and 8, has at least an essentially - (_ · Borrowed uniform thickness and is provided with evenly distributed holes 17. Their shape is adapting to the physiological conditions essentially semicircular, as in particular from FIG. 8 is recognizable. The buffer layer 6 consists of silicone, in other words, a material that is not only compatible with tissue, but also elastic and cushioning.

The upper bearing plate 4 can be seen in particular from FIGS. It is made of polyethylene and has a flat bottom 18, the flat lower portion 19 of the upper bearing plate 4 as it were Forms a flange or a shoulder which interacts with the bearing cage 7 in a manner to be described below. On its upper side, the upper bearing plate 4 can be seen in particular from FIGS. 9 and 10 Provided with a curved recess, to be precise in adaptation to the cup-shaped prosthesis shell 21 of the end of the femur 22 cooperating with the tibial bearing 2, the prosthesis shell 21 Has lugs 23 which are cemented into the bone tissue of the femur 22.

As already mentioned and in particular from FIGS. 9 and

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BQEHMERT

recognizable, the lower section 19 of the upper bearing plate 4 forms a shoulder 24 in the edge area, which in the assembled State cooperates with a flange 26 of the bearing cage 7, which in particular from the rest of the Fig. 14 recognizable, essentially semicircular Has ring configuration, which from the side wall

27 of the bearing cage 7 is formed and with holes

28 is provided.

As can be seen in particular from FIGS. 2 and 3, the pins 16 are after the assembly of the lower bearing plate 3, the buffer layer 6, the upper bearing plate 4 and the bearing cage 7 from the outside through the bores 28 of the bearing cage 7 is inserted into the bores 14 of the lower bearing plate 3, so that the buffer layer 6 is held between the lower bearing plate 3 and the upper bearing plate 4 and the upper bearing plate 4 in turn is positively held within the bearing cage 7, although they are in the longitudinal direction of the Bone, i.e. can move in the direction of arrow 29 to a limited extent, as discussed below.

If there is a load in the direction of arrow 29 when the knee ring prosthesis is in place, this is done for demonstration purposes at a distance from the upper bearing plate 4 drawn prosthesis shell 21 a corresponding Pressure is exerted on the upper bearing plate 4, which is held at the top by the flange 26 of the bearing cage 7. There the upper bearing plate 4 is supported in an elastic and damping manner by the buffer layer 6 arranged downstream of it is, this pressure is transferred to the buffer layer 6, which leads to a compression of the buffer layer 6 leads, whereby this compression is not necessarily _ evenly, but in the natural knee

· 'B'GÖHMfiR * & BOE ¹ HMERT

movement (rolling movement with superimposed sliding movement) of different strengths, as in the detail drawing according to FIG. 3, the unloaded starting position there with a dashed line 31 is indicated. The upper bearing plate has moved downwards by the dimension a, at least in the edge area, while the compression in the middle area is lower in the load position shown. Because of the buffer layer 6 results in an extraordinary- -jjj lent smooth, elastic movement with at the same time (cushioning properties, which the prosthesis wearer

is felt to be extremely pleasant, the also has an extraordinarily positive effect on the inevitable signs of wear under load.

In Fig. 15 the tibial bearing 2 is again in an exploded view before assembly or installation shown.

,;, ElCiEHyERit. & Ö.QlEHjiyiERT

File: O

December 16, 1981

REFERENCE LIST (LIST OF REFERENCE NUMERALS)

y, tibial head 1 2 tibial arteries P. 5 lower Laaerpl afi-p (of 2) τ> 4 upper bearing plate (of 2) 4th 5 " 5 5 buffer layer 6th η bearing cage 7th ■ g surface (of 3) 8th Q bridge (of 3) 9 10 bar (of 3) 10 11th 11th 12 holes (from 9, 10) 12th 15 face 15th 14 holes 14th 15 - 15th 16 pens 16 17 holes 17th 18 bottom (of 4) 18th 19 lower section (of 4) 19th 20 - 20th 21 prosthetic shell 21 22 thigh bones ?? 25 approaches 25th 24 shoulder 24 25 - 25th ? 6 flange 26th 27 side wall (of 7) 27 28 holes 28 29 arrow 29 30 - 30th 31 Ausaanasstelluno

Claims (1)

ι 2. Prosthesis according to claim 1, characterized in that f that the buffer layer (6) made of silicone or the like. consists. .: # G> £ Hm £ «* t"& BOEHMERT 0 225 December 16, 1981 Expectations 1. Prosthesis for a knee joint, with one on the head of the tibia arranged tibial bearing for positioning the knee facing natural or artificial end of the thigh bone, characterized by an elastic and / or damping buffer layer (6). 3. Prosthesis according to claim 1 or 2, characterized in that the buffer layer (6) has a substantially has a uniform thickness (s). 4. Prosthesis according to one of claims 1 to 3, characterized in that the buffer layer (6) has a substantially has flat top and bottom. 5. Prosthesis according to one or more of the claims 1 to 4, characterized in that the buffer layer (6) is provided with several through openings (17). 512 bqehmert 6. Prosthesis according to claim 5, characterized in that the through opening (17) is substantially uniform are arranged distributed over the buffer layer (6). 7. Prosthesis according to one or more of the preceding Claims, characterized in that the buffer layer (6) is part of the tibial bearing. 8. Prosthesis according to claim 7, characterized in that 'the buffer layer (6) between one on the tibial tissue (1) to be attached lower bearing plate (3) and an upper bearing plate (4) held on this is arranged. 9. Prosthesis according to claim 8, characterized in that the two bearing plates (3, 4) each at their the side facing the buffer layer (6) are essentially flat. 10. Prosthesis according to claim 8 or 9, characterized in that the upper bearing plate (4) at its the Buffer layer (6) facing away from the top has a concavely curved recess. 13. Prosthesis according to one or more of the claims 8 to 10, characterized in that the upper bearing plate (4) is made from a tissue-compatible plastic like polyethylene. 12. Prosthesis according to one or more of claims 8 to 11, characterized in that the lower bearing plate (3) consists of a tissue-compatible metal and has lugs (9, 10) by means of which it can be cemented into the tibial tissue (1). Λ · 2 "- . 13. Prosthesis according to one or more of claims 8 to 12, characterized in that the upper Bearing plate (4) and thus the buffer layer (6) in the normal direction (29) so as to be movable in a form-fitting manner to a limited extent is held on the lower bearing plate (3). 14. Prosthesis according to claim 13, characterized in that that a bearing cage (7) connected to the lower bearing plate (3) is present, which at least the upper part of the lower bearing plate (3), the buffer layer (6) and the lower part of the upper Bearing plate (4) surrounds ring-shaped and has at least one section (26) which the upper bearing plate (4) holds positively. 15. Prosthesis according to claim 14, characterized in that that the section (26) of the bearing cage (7) holding the upper bearing plate 4 consists of an upper end section of the bearing cage (7) arranged, inwardly directed flange. 16. Prosthesis according to claim 15, characterized in that the upper bearing plate (4) at its lower portion (19) has a radially outwardly projecting flange (24) or the like - that of the flange (26) of the bearing cage (7) is overlapped.