CA1264901A

CA1264901A - Joint prosthesis and tool to be used herewith

Info

Publication number: CA1264901A
Application number: CA000470256A
Authority: CA
Inventors: Jonas Lindwer
Original assignee: Individual
Current assignee: Individual
Priority date: 1983-12-16
Filing date: 1984-12-17
Publication date: 1990-01-30
Also published as: JPS60153855A; NL8304339A; US5032134A; EP0146192A1

Abstract

ABSTRACT
.

A joint prosthesis comprising two co-operating prosthesis members fastening each to a different joint bone. At least one of the prosthesis members is formed by at least two prosthesis elements one surrounding the other, the one prosthesis element adjacent the bone being provided with fastening means distributed along the outer face and being located inside the outer face when the joint prosthesis is being applied, out of which outer face they can subsequently be moved in order to cause them to penetrate into the bone.
The fastening means are formed by pins guided in passages of the prosthesis element. The tipform of these pins could be chosen in relation to the hardness of the bone to be penetrated.
Furthermore, the contact faces of the two prosthesis elements could be provided with coating mimicing the elastic and/or resilient features of bone.

Description

12~9~1 The invention relates to a jolnt prosthesis comprising two co-operating prosthesls members each to be fastened to a different joint bone at least one of the prosthesis members consisting of at least two prosthesis elements, the first prosthesis element being adjacent to the joint bone and surrounding a second prosthesis element, whereby the first prosthesis element is provided with pins having rounded oH tips and residing in passages provided in and distributed over the outer surface facing the joint bone and residing within the outer lo surface when the prosthesis element is being applied to the joint bone, out of which surface these pins are movable in order to bring the pins in contact with the joint bone and locked against rotation and translation in this contacting situation with the second prosthesis element.
At present at least two different methods are known to fasten the prosthesis members to a joint bone. A first method consists of applying a layer of cement between a pro~thesis member and a joint bone, which layer firmly fixes this prosthesis member to the jolnt bone after curing. The use of cement i~ attended with various disadvantages. In the first place the cement becomes brittle in the course of time, it scales off and due to these aging phenomena the prosthesis member gets loose from the joint bone. In the second place the cement affects the adjacent bone layer. Finally a patient may be allergic to constituents of the cement.
In a further method of fastening a prosthesis member to ~26~9~3 ~ 1766-439 a joint bone the use of cement is dispensed with; the method uses a prosthesis member, the material of which stimulates bone growth on a coating applied thereto so that after some time the prosthesis member has grown in the joint bone in a natural manner.
A disadvantage of this second method is that the natural growth to the prosthesis member takes a particularly long time, whilst this growth stops and has to start completely anew if due to any movement whatever a relative displacement has taken place between the pros~hesis member and the ~oint bone. In practice this means that after the application of a join~ prosthesis a patient must not fully charge the prosthesis for a very long time. This gives rise to various psychical problems in the patient.
DE-A-2.305.442 discloses a joint prosthesls comprising a single prosthesis member in which a wedged rigid shaft is mounted for longitudinal translation. This translation motion urges pins residing in passages in the prosthesis member radially outwardly and causes them to be pressed against the inner bone wall. The number of pins of the length of thls known prosthesis member is limite~ due to the use of thls wedged shaft, so that relatively large loads must be transmitted to the surrounding bone per fastening pin. Furthermore, this prosthesis member comprises large interstitial spaces accessible for body fluid and cells.
Accordingly, there is a risk to infections and unwanted ingrowth~
of tissue, specifically bone tissue resulting in a blocking of the movable parts of the mechanical system.
The invention has for lts object to improve the joint lX~;~901 prosthesis of the kind set forth in the preamble such that, the aforementioned drawbacks are overcome. According ~o the invention this is obtained in that in the a~sembled form said prosthesis member has a massive foxm substantially void of interstitial spaces accessible for body fluid and cells and that the shape and size of the relative contact surfaces are the same for rela~ively dlfferent types of the first and the second prosthesis elements.
US-A-4.237.875 discloses a dynamic lntramedullary compression nailing for fixing a temporary prosthesis member in a long bone, such as a femur. Thls prosthesis member comprises sliding blades having lateral, pointed pro~ections. The blades are coupled operatively to a shaft axially slidable within the hollow prosthesis member. The axial movement re6ults ln an outward projecting of the projections through passage~ in the prosthesls member, and causes the projections to penetrate into the bone. The projections will easily penetrate into the bone, and are apt to hold in a stable fashion bone fragments at a fracture site in a compressed situation, but are not capable to couple two joint bones when a load ls transferred to the joint.
This primary fixation of the prosthesis members to the joint bone is particularly reliable because along the whole outer face of one prosthesis element the fastening means penetrate into the bone and since a large number of fastening means are used, the depth of penetration of the fastening means into the bone can be limited, for example, to an order of magnitude of 1 to ~ mms. In this way the disadvantages of the use of long screws are also 2a ~26~9~)1 avolded.
Preferably the pins are split pins and a split partition is provided in the passages, or the pins have a conical, rounded-off tip, these pins can be introducecl in a simple manner into the bone, whilst the fixation is particularly effective since there 2b ~r,~

i4~
21766-43g is no need for prevlously making holes for the pins.
In a very simple manner a :Large number of pins can be simultaneously arranged inside the pxosthesis member, when sequences of pins are fastened to a strip material, whilst a prosthesis element i3 preferably provided with a slot for recelving the strip of material.
When a strlp of material is fastened at one end to the prosthesis element, it is possible, in a later stage, for example for applying a new prosthesis member, to simultaneously remove lQ large series of pins from the prosthesis member.
~ ince the bone has a definite elastlcity and resilience and the prosthesls members, and certainly those used as a hip prosthesi~, are mainly made of metal, it is preferred to impart to these prosthesis members the elasticlty and resilience approaching those of the bone. This can be achieved in that at least one of the relative contact faces of the two prosthesis elements i8 provided with a coating of a resilient synthetic resin, preferably polyethylene.
When a coating of resilient synthetic resin is used the fastening means can be advantageously arranged in the prosthesis member, when the synthetic resin coating is fastened to one prosthesis element and forms a force fit to the fasteninq means at the level of the passages provided therein.
In order to prevent the prosthesis elements surrounding one another from performing a relative displacement it is preferred to releasably guard the one and the other prosthesis ~, . ,~

lZÇ~901 element with ~he aid of guard means.
A par~icularly advantageo~s embodiment of the invention is characterized in that the joint prosthesis is a hip prosthesis in whlch the prosthesis member to be arranged in the bone is formed by ~he one prosthesis element in the form of an envelope having a passage, the internal shape of the envelope substantially corresponding wlth the external shape of the part of the other prosthesis element to be inserted into it in the form of a stem, the other part of which designed as a head and fastened to said stem corresponding wlth the second prosthesis member to be arranged in the pelvis in the form of a socket.
The above mentioned and further features will become apparent from flve embodiments given by way of non-limitatiYe examples of the hip prosthesis in accordance wlth the lnventlon with reference to the accompanying drawing.
The drawing shows in Fig. 1 and Fig. 2 an elevational view and partly a sectional view of a prosthesis member to be arranged and arranged respectively in accordance with the invention;
Fig. 3 an elevational view like Fig. 1 of a second embodiment of a prosthesis member in accordance with the invention;
Figs. 4 and 11 each an elevational view of the prosthesis member of Fig. 3 co-operating with a second member fastened in another joint bone;

126~90~ `

.

Figs. 5, 6 and 7 the component parts of a third - embodiment of a pros~hesis member ln accordance with the invention;
E'ig. 8 on an enlarged scale a variant of detail VIII of Fig. 6 of a fourth embodiment of a prosthesis member in accordance with the invention;
Fig. 9 a knee joint comprising a joint prosthesis having two co-operating prosthesis members in a fifth embodiment of the invention; and Fig. 10 on an enlarged scale a fastening means in accordance with the invention.
Figs. 1 and 2 illustrate the application of a joint prosthesis 1 comprising two co-pending prosthesis members 3, 7 each to be fastened in another joint bone 10, 11. As is shown in further detail in Flg. 2`the prosthesis member 3 is formed by two prosthesis elements 12, 13, in which one prosthesis element 1 receiving the other element and being adjacent the bone 10 is provided with fastening means 1-5 distributed along its outer surface adjacent the bone 10 and formed, as is shown in Fig. 10, by pins 16 having a conical, rounded-off tip 17. Since the prosthesis element 12 may be adjacent to parts of the ~one 10 which differ in hardness, the form of the tip of the pins to be used, could be chosen optimally with respect to these bone parts.
Pins 16 with an acute tip for hard bone parts, a blunt tip for relatively softer bone parts. Accordingly, an optimum fixation ~26'~!~0~

for generally all pins 16 is obtained. Prior to implanting the prosthesis element 13 the hardness of various bone parts may be determined using tools known in the art. The pins are guided in passages 18. When the joint prosthesis 1, more particularly the prosthesis member 3 is applied, the pins 16 are located inside the outer surface 14. As is shown in Fig. 1, after the application of the prosthesis element 12 the pins are moved outside the outer surface 14 with the aid of a punch 19. The pins guided in the passages 18 penetrate into the bone 10. Because the pins are distributed mainly along the entire outer surface 14 in the prosthesis element 12, it is not necessary for all pins to penetrate into the bone 10. At the place of a cavity 2~ a pin 16' projecting there can extend only up to the ~one 10. After the pins 16 have been pushed outwards with the aid of the punch 19 and after the removal of the punch 19 the prosthesis element 13, which is surrounded by the prosthesis element 12 is arranged therein.
The prosthesis element 13 is provided with an external coating 21 of a resilient synthetic resin, for example, polyethylene, so that inside the prosthesls member 3 elastic and resilient properties are generated which correspond with those of the bone 10. After the application of the prosthesis element 13 a spherical ball 23 can be arranged on the stub 22. As an alternative the prosthesis element 13 and the ball 23 may be integral with one another.
Thus the prosthesis member 3 consists of a prosthesis element 12 mainly having the form of a sleeve and a stem-shaped 1~6~90~

prosthesis element 13 arranged in said sleeve. The prosthesis elements 12 and 13 together mainly correspond with a stem of a known stem-shaped prosthesis member, the difference being that in accordance w~th the lnvention ~he prosthesis member is provided with outwardly displaceable fastening means.
Figs. 3 and 4 show a second embodiment of prosthesis members 4 and 7 associated with the joint prosthesis 1, a hip prosthesis.
The prosthesis member 4 has substantially the same constructlon as the prosthesis member 3 (Figs. 1 and 2), the difference being that the synthetic resin coating 24 between the relatlve contact faces 25 and 26 forms part of the sleeve-shaped prosthesis element 27, in which the stem-shaped prosthesis element 28 is arranged. This construction has the advantage that ~he one prosthesis element 27 provided with the internal synthetic resin coating 24 establishes at the passages 18 provided therein a force fit with the fastening pins 16 so that during the application of the prosthesis element 27 in the bone 10 said means are retained therein without being able to get free from the passages 18 or to protrude from the outer face 14. Since the prosthesiæ element 28 has a smooth metal surface, the use of a punch 19 can be dispensed with when the fastening pins 16 are being expelled. Moreover by their ends 29 the fastening pins exert pressure on the metal surface 25 æo that between the fastening means 16 and the prosthesis element 28 no or hardly any resilience and hence no ' ~s 12~i~901 relative displacement are possible as compared to the situation ! illustrated in Figs. 1 and 2.
Fig. 4 shows the prosthesis member 7 co-operating with the prosthesis member 4 of Fig.3 and arranged in the jolnt bone 11, in this case the pelvis. The prosthesis member 7 comprises the prosthesis elements 30 and 31. The prosthesis element 30 co-operating with the spherical ball 23 consists of a synthetic resin layer 32 surrounded by a metal coating 33. In this way the pins 16 are prevented from penetrating into the synthetic resin layer 32. From the exploded view of Fig. 11 it will be apparent that the fastening means 16 are expelled with the aid of the prosthesis element 30, whilst a rim 81 for the fastening pins is received in an annular groove 80.
Figs. 5, 6 and 7 show a thlrd embodiment of a prosthesis member 5 in accordance with the invention which comprises a sleeve-shaped prosthesis element 34 recelving a stem-shaped prosthesis element 35.
In this case the fastening pins 16 are arranged on a strip of material 36, 37 of different lengths dependent on the shape of the prosthesis element 34. Also in this case strips of material could be used, having pins 16 with a tipform adapted to the hardness of the bone to be penetrated. If the strips are to be provided with pins having different tipforms, then it is advantageous that these pins are mounted releasably on the strip.
Thus the sequences of pins 16 can be accommodated in the iZ~i4901 21766-43g prosthesis element 34, which for thls purpose has ln its lnternal ~ace 39 slots 40 for receiving the strips of material 36 and 37, respectively. The strips o~ material 36, 37 can be fixed with the aid of appropriate fastening means 41, 42 in the prosthesis element 34. Since the strips of materlal 36, 37 are located in the slots 40, a smooth internal surface 43 is ~ormed inside the prosthesis element 34, said surface having a shape matching the external face 44 of the prosthesis element 35.
Fig. 8 shows a detail of a prosthesis member 6 in a fourth embodiment of the inventlon comprising a prosthesis element 45 having a plurality of bores 47 adapted to receive prosthesis ele~ents 46. In this case the prosthesis elements 46 are surrounded by the prosthesls element 45. The bores 47 also have slots 48 for receiving strips of material 49 provided in this case with sequences of fastening means 15 in the ~orm of split pins 50.
In order to ensure splitting of the split plns 50 when they are expelled by the action of the prosthesis element 46 splitting partitions 52 are provided in passages 51. These splitting partitions form part of a metal strip 71 to be arranged in a groove 70. The passages 51 may also be formed by gaps extending in the direction of length of the prosthesis element 45. This has the advantage that several series of fastening means can be moved to the outside through a gap. Moreover, the tolerance in the direction of length of a gap is less critical with respect to the fastening means to be passed through.

8a lX6~9~

A fifth embodiment of prosthesis members 8, 9 of, in this case, a knee prosthesis 2 in accordance with the invention is shown in Fig. 9. The prosthesis member ~ comprises a prosthesis elemen~
53 surrounding a prosthesis element 54. The prosthesis element 54 consists of a metal layer 55 and a synthetic resin coating 56.
The prosthesis element 9 comprises a prosthesis element 57 surrounding a synthetic resin prosthesis element 58, the part 59 of which co-operates with the prosthesis element 53. The prosthesis element 57 comprises a metal layer 60 and an inner synthetic resin coating 61 applied thereto. Since the prosthesis element 5~ is made from a synthetic resln, the coating 61 may, if desired, be dispensed with.
It will be obvious that for the various metal parts o~ the joint prosthesis 1 and 2 metals are chosen which do not reac~ or react only to a negliglble extent with respect to neighbouring bone or soft tissue. Those materials are known in the art and are stainless steel, titanium, cobalt chromium alloys. As is shown by way of example in Fig. 5, the external surface of the prosthesis element a~jacent the bone, for example in this case the prosthesis 23 element 34 may be provided on the surface 62 with pellets 63 of, for example, cobalt chromium molybdenum alloys such as Francobal (trade mark) having a secondary, bone growth stimulating effect so that not only by the primary fixation with the aid of the fastening meanæ 15 but also secondary bone growth additionally fixes the prosthesis element 34 inside the bone in a natural manner.

~b

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A joint prosthesis comprising two co-operatling prosthesis members each to be fastened to a different joint bone, at least one of the prosthesis members consisting of at least two prosthesis elements, the first prosthesis element being adjacent to the joint bone and surrounding a second prosthesis element, whereby the first prosthesis element is provided with pins having rounded oH tips and residing in passages provided in and distributed over the outer surface facing the joint bone, and residing within the outer surface when the prosthesis element is being applied to the joint bone, out of which surface these pins are movable in order to bring the pins in contact with the joint bone and locked against rotation and translation in this contacting situation with the second prosthesis element, characterized in that in the assembled form said prosthesis member has a massive form substantially void of interstitial spaces accessible for body fluid and cells and that the shape and size of the relative contact surfaces are the same for relatively different types of the first and the second prosthesis elements.

2. A joint prosthesis as claimed in claim 1, characterized in that the second prosthesis element is linked with the other co-operating prosthesis member.

3. A joint prosthesis as claimed in claim 1 or 2 characterized in that the pins are split pins and a splitting partition is provided in the passages.

4. A joint prosthesis as claimed in claim 2, characterized in that the pins have tips with an acute blunt form, chosen in relation to the hardness of the bone to be penetrated.

5. A joint prosthesis as claimed in claim 2 characterized in that series of pins are fastened to a strip of material.

6. A joint prosthesis as claimed in claim 5, characterized in that a prosthesis element has a slot for receiving the strip of material.

7. A joint prosthesis as claimed in claim 5 or 6 characterized in that the strip of material is fastened at one end to the prosthesis element.

8. A joint prosthesis as claimed in claim 1, characterized in that at least one of the relative contact faces of the two prosthesis elements is provided with a coating of a resilient synthetic resin.

9. A joint prosthesis as claimed in claim 8, characterized in that the synthetic resin is polyethylene

10. A joint prosthesis as claimed in claim 8 or 9 characterized in that the synthetic resin coating is fastened to the first prosthesis element and establishes a force fit with the fastening pins at the level of the passages provided therein.

11. A joint prosthesis as claimed in claim 1 or 2, characterized in that the joint prosthesis is a hip prosthesis in which the prosthesis member to be arranged in the thigh bone is formed by the first prosthesis element formed by a sleeve with the passages, the inner shape of the sleeve substantially matching the external shape of the part of the second prosthesis element formed by a stem to be inserted into said sleeve, the other part formed by a head and connected with the stem corresponding with the second prosthesis member formed by a socket to be arranged in the pelvis.