CA1078551A

CA1078551A - Bone prosthesis

Info

Publication number: CA1078551A
Application number: CA251,891A
Authority: CA
Inventors: Per I. Branemark; Bo T. Af Ekenstam
Original assignee: Individual
Current assignee: Individual
Priority date: 1975-04-22
Filing date: 1976-04-22
Publication date: 1980-06-03
Also published as: FR2310121B1; SE7504625L; FR2310121A1; DE2617749A1; SE403884B; DE2617749C2; GB1525667A

Abstract

"BONE PROSTHESIS"

ABSTRACT OF DISCLOSURE
A bone prosthesis and the method of securing it in place, in which the prosthesis is formed as a tubular support member having perforations therein, the end of the bone is bored, a tubular support member is introduced into the bore and cement is then introduced into the interior of the tubular support and passes out through the perforations to provide the midterm anchor on the walls of the bone. The cement will damage the tissue where it contacts the tissue, but the remainder of the tissue of the bore is undamaged and this grows inwardly to form a long term anchor between the tubular support and the bone. A prosthesis body is located and secured in place e.g. mechanically or by cement, in the tubular support member.

Description

`` 1C1~7~3S51 The present invention relate~ to a bone prosthe~is and a method of forming a bone joint utilizing such a prosthesis.
It is known to permanently reconstruct the bone joints of a human which are malformed either from birth, or due to disease or accident, by various means.
One techni~ue involves the substitution of the components of a joint from a biologically accep~able material ~such as metal or plastics which is inserted in a bore formed in the ends of the boné and is held in place by a cementing procedure. The conventional form of cement utilized are plastics material cement, based on modern polymers which are capable of forming organic-chemical monomers. These cements ; are prepolymerised in order to ensure sufficient plasticity for putting them in place. However, when the cements are finally cured, they need to be xaised to a high reaction temperature and this, together with the side effects produced by the monomers has a disadvantageous ~iological effect on the bone, killing the bone tissue. Thus, this technique although it is satisfactory in the short term is not suitable for long term use.
The modern prosthetic devices themselves have been satis~actorily manufactured from biologically compatible metal such as titanium and titanium alloys or vitallium.
Plastics materials are also used to form the components of the prosthesis themselves, although these are normally only suitable for smaller joints, such as finger joints. The actual retention of the device in the bone is a function of the cement itself, and it ha~ been conventional to use methyl acrylic and polymethyl acrylic, or methyl metacrylic-styxene copolymers with or without the addition of barium sulphate.

1071~SS~
As mentioned, the boncl provi~ed previously is not entirely satisfclctory ~or the rea~ons outlined.
According to the present invention, we provide a bone prosthesi.s comprising a tubular support member having a plurality of lateral openings disposed at spaced locations along the leng~h and around the periphery of the ~upport member through the wall thereof, the prosthesis body locatable at least in part in said support member and means for securing the body in place in the support body.
With such a prosthesis, the bone to be treated is brought out as is conventional, and the tubular support member is inserted in place. A suitable cement of the kind mentioned abo~e .is introduced into the tubular support member so that it passes locally through the openings and contact the bor~
lS at the location of these openings only. The cement is cur~d, - the prosthesis body is either prior to this curing or during this curing located and secured in place in the tubular support member.
With such an arrangement, the only portion of the bone tissue which is in any way damaged is that portion which is touched by the cement. The cement serves to hold the - tubular support member in position for a ~hort term or midterm period. This is sufficient to allow the bone tissue to grow inwardly and anchor the remainder of the tubular support member in place. Thus, when the bond between the cement and the bone breaks down, as it will in due course, the tissue will hold the support member in place.
The tubular support membex may take a number of different forms and may, ~or example, comprise an inner tube and an outer ~ube, the outer tube having a plurality of --- ~L07855~

lateral openings through the wall thereof,'ancl the inner tube having a smaller number of openinys therein, these openings being in register with the openings of the outer tube. The cement passes through the registering openings and the other openings serve to assist in anchoring the ~upport member to the tissue when it grows. In another construction, the support member may comprise a mesh material which again forms a good anchor for the growing tissue. The inner surface of the mesh material may be formed with a wall of ceramic material having holes therein in register with the lateral openings and this serves to form a heat barrier to the heat of the cement.
~ The tube may be formed to have an inner portion and ! an outer portion by punching so that the cement executed a tortuous path from the interior to the exterior and provides a better bond.
¦ The tubular support member may, alternatively, be formed,of a helix, and in any o~ thei ; constructions may be radially expansible.
Various means may be provided for securing the body of the prosthesis to the tubular support member, for example radially inwardly extending projections may be provided from the interior of the support member and these may cooperate with members on the prosthesis body itself.
In oxder that the invention may be more readily understood, the following description is given, merely by way of example, reference being made to the accompanying drawings, in which~
Figure 1 iB a section through a pair o~ bones provided with a prosthesis joint accordiny to ~he invention, 107~
Figure 2 is a perspective view of the f~upport member o~ the device of Figure ~, Figures 3 and l~ are end views of two ~urther embodiments of support tube, Figur~s 5 and 6 are elevations of two further forms o~
support tube: .
Figure 7 is a transverse section of a further embodiment of support tube, and Figure 8 illustrates a modified construction of prosthesi.s showing the method of holding the prosthesis member in place~
Referring now to Figure 1 of the drawings there is illustrated two portions of bone 10 and 11 to be secured together by a ball and socket type joint. The bones 10 and 11 are provided with bores 12 and 13 respectively and a tubular support member 14 is inserted in the bore 12 and a further tubular support member 15 in the bore 13.
The tubular support member 14 and 15 are each provided with a plurality of lateral openings 16 which are disposed at spaced locations both along the length and around the periphery of the support member. The support member 15 has a closed end 17 which is also provided with similar openings 16.
A prosthesis body having a stem 18 and a head 19 is inserted with the stem into the support member 16. A
complementary prosthesis in the form of a cup 20 is inserted in the bore 13.
Cement o~ the type described earlier is introduced into the #pace between the 3tem and support member and the space betwe~n the member 20 and the suppor~ member 15, and 785~
is forced in through the ~penings l~ into corltact with the wall of the bore adjacent these openings only. The remainder of the bore is not contacted by the cement.
The cement serves to secure the support member in - 5 place for a short term or mid term period. ~he bone tissue at these locations i9 killed either by the telnperature o~
the c~ment or by the chemical reaction thereof. However, this is sufficient to hold the prosthesis in place for a period of time. During this period of time the bone tissue which has not been killed, that is the material opposite the unperforated portion of the support, grows inwardly and anchor~ ~he support ~irmly on a permanent basis. The c~ment ~r also serves to hold the prosthesis member 18, l9, 20 in position.
As can be seen from Figure 2 the holes 16 are arranged along a helix. l~e holes shown are round, althou gh these may be of any other shape, for example, elongate slots.
As-seen in Figure 3, a tubular support member comprises a mesh material 2~, with a plurality of lateral openings 16 therein, and a wall of ceramic materials 29 provided with holes 30 therein.
The construction illustrated in Figure 4 has an inner tube 24 and an outer tube 25, the outer tube having a plurality of openings 26 therein through the wall thereof and the inner tube having a smaller number of openings 27, these openings being in register with the openings of the outer tube. Thus, the remaining opening~ of the outer tube form an anchoring poink for the bone tissuQ.
Figure 5 show~ a ~urther form o~ support tubQ which is radially e~pan~ihle and being provided with a crenalated , ~855~

periphery in w~llch the openings 16 ar~ ~ormed.
In the construction of Figure 6 the support is formed as a helix, the initial diameter of which is slightly larger than the bore but it can be radially conkracted by twisting. This forms a fuxther mechanical anchor on the bore. rrhe opening can be considered as laterally spaced between turns, although in fac~ it i5 a continuous helix.
Figure 7 shows a further form of tube 30 having an inner portion 31 and an outer portion 32 ~ormed by punching the outQr tube outwardly from the inner tube. In this wa;y the apertures formed are nok aligned and the cement is caused to execute a somewhat tortuous path between the two tubes on its way from the interior to contact with the bore in the ,~ bone.
Figure 8 shows a further construckion in which the ! support tube is provided with radially inwardly extending projections 34 and cooperating member~ 35 on the prosthesis body. A spring 36 is provided at the end to reduce axial shocks.

' ~ - 7 -'., '.'' , :

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A bone prosthesis comprising, in combination:-a) a tubular support member;
b) a plurality of lateral openings disposed at spaced locations along the length and around the periphery of said support member and through the wall thereof;
c) a prosthesis body having at least a part locatable in part in said tubular support member, said part having an outer surface dimensioned to be spaced from the inner surface of said tubular support member, whereby bone cement can be introduced into said tube support member when the prosthesis body is in place and flows through said lateral opening; and d) means for securing said body in place in said support member.

2. A prosthesis as claimed in claim 1, wherein the tubular support member comprises an inner tube and an outer tube, the outer tube having a plurality of lateral openings through the wall thereof, and the inner tube having a smaller number of openings therein, these openings being in register with the openings of the outer tube.

3. A prosthesis as claimed in claim 1, wherein the tubular support member comprises a mesh material with a plurality of lateral openings therethrough.

4. A prosthesis as claimed in claim 3, and further comprising, on the inner surface of said mesh material, a wall of ceramic material having holes therein in register with the lateral openings.

5. A prosthesis as claimed in claim 1, wherein the tubular support member comprises a tube having an inner portion and outer portion radially spaced therefrom by punching.

6. A prosthesis as claimed in claim 1, wherein the tubular support member is formed as a helix.

7, A prosthesis as claimed in claim 1, wherein the tubular support member is radially resilient.

8. A prosthesis as claimed in claim 1, wherein the means for securing the body in place comprise radially in-wardly extending projections on the tubular support member and co-operating members on the prosthesis body.

9. A prosthesis as claimed in claim 7, wherein the tubular support member has a crenelated periphery.

10. A bone prosthesis comprising, in combination:-a) a tubular support member formed of mesh material providing a plurality of lateral openings disposed at spaced locations along the length and around the periphery of said support member and through the wall thereof;
b) a wall of ceramic material having holes therein in register with the lateral openings disposed on the inner surface of said mesh material;
c) a prosthesis body having at least a part locatable in said tubular mesh support member; and d) means for securing said body in place in said support member.

11. A bone prosthesis comprising in combination:-a) a tubular support member comprising a tube having an inner portion and an outer portion radially spaced therefrom by punching;
b) a plurality of lateral openings disposed at spaced locations along the length and around the periphery of said support member and through the wall therof;
c) a prosthesis body having at least a part locatable in said inner portion of said tube; and d) means for securing said body in place in said inner portion of the tubular support member.