Abstract
An acetabular cup prosthesis comprising: an inner cup surface and an outer cup surface, said inner cup surface meeting said outer cup surface at a rim of said cup, wherein said inner cup surface, said outer cup surface or both said inner cup surface and said outer cup surface comprises an engagement formation located proximal to said rim, said engagement formation extending around at least a portion of the circumference of the cup; and a Sip member comprising an engagement formation configured to cooperate with the engagement formation of the cup.
Claims
1. An acetabular cup prosthesis comprising: an inner cup surface and an outer cup surface, said inner cup surface meeting said outer cup surface at a rim of said cup, wherein at least one of the inner cup surface and the outer cup surface comprises an engagement formation of the cup located proximal to said rim, said engagement formation extending around at least a portion of the circumference of the cup; and a lip member comprising an engagement formation of the lip member configured to cooperate with the engagement formation of the cup.
2. An acetabular cup prosthesis according to claim 1 wherein the cup is formed from ceramic.
3. An acetabular cup prosthesis according to claim 1 wherein the lip member is formed from a polymeric material.
4. An acetabular cup prosthesis according to claim 3 wherein the polymeric material is a polyaryletherketone or nylon.
5. An acetabular cup prosthesis according to claim 1 wherein the engagement formation en of the cup is of a female configuration and the engagement formation of the lip member is of a cooperating male configuration.
6. An acetabular cup prosthesis according to claim 1 wherein the engagement formation of the cup and the engagement formation of the lip member are co-operating faces which have a transverse S-cross section.
7. An acetabular cup prosthesis according to claim 1 wherein engagement formation of the cup and the engagement formation of the lip member are bonded together.
8. An acetabular cup prosthesis according to claim 1 wherein the lip member is configured such that when it is in position on the cup, a profile of the outer cup surface and an outer surface of the lip member are contiguous.
9. An acetabular cup prosthesis according to claim 1 wherein the lip member is configured such that when it is in position on the cup, a profile of the inner cup surface and an inner surface of the lip member are contiguous.
10. An acetabular cup prosthesis according to claim 1 wherein the lip member extends upwardly from the outer surface of the cup and is directed inwardly to provide a free edge.
11. An acetabular cup prosthesis according to claim 10 wherein the free edge of the lip member comprises shaping.
12. An acetabular cup prosthesis according to claim 11 wherein the shaping is selected from a crenalation configuration and an undulation configuration.
13. An acetabular cup prosthesis according to claim 1 wherein an outer circumference of the lip member includes at least one formation to restrict rotation of the acetabular cup prosthesis when implanted.
14. An acetabular cup prosthesis according to claim 13 wherein the at least one formation comprises a plurality of ribs.
15. An acetabular cup prosthesis according to claim 1 wherein the cup additionally comprises a plug component which interlocks with the lip member.
16. An acetabular cup prosthesis according to claim 15 wherein the plug component is formed from a polymeric material.
17. An acetabular cup prosthesis according to claim 16 wherein the plug component is formed from polyurethane.
18. An acetabular cup prosthesis according to claim 1 wherein the cup includes a sacrificial portion above an engagement formation.
19. A kit comprising the acetabular cup prosthesis of claim 1 and an impaction cap or introducer tool, said impaction cap or introducer tool comprising an engagement formation configured to cooperate with the engagement formation of the cup or the engagement formation of the lip member.
20. A kit according to claim 19 wherein the impaction cap or introducer tool extends into a bowl of the cup.
21. A kit according to claim 20 wherein the impaction cap or introducer tool includes a protuberance which in use interlocks with a recess or aperture in the bowl of the cup.
22. A kit according to claim 19 further comprising additional fixation to hold the impaction cap in the acetabular cup prosthesis.
Description
[0077] The present invention will now be described, by way of example, with reference to the following drawings in which:
[0078] FIG. 1 is a perspective view of an acetabular cup prosthesis according to one aspect of the present invention;
[0079] FIG. 2 is a perspective view of the prosthesis of FIG. 1 taken through a cross-section thereof;
[0080] FIG. 3 is an enlarged illustration of portion B of FIG. 2;
[0081] FIG. 4 is a perspective view of an acetabular cup prosthesis according to a second aspect of the present invention;
[0082] FIG. 5 is a perspective view of the prosthesis of FIG. 4 taken through a cross-section thereof;
[0083] FIG. 6 is an enlarged illustration of portion B of FIG. 5;
[0084] FIG. 7 is a perspective view of an acetabular cup prosthesis according to a third aspect of the present invention;
[0085] FIG. 8 is a perspective view of the prosthesis of FIG. 7 taken through a cross-section thereof;
[0086] FIG. 9 is an enlarged illustration of portion B of FIG. 8;
[0087] FIG. 10 is a perspective view of an alternative lip member;
[0088] FIG. 11 is a perspective view of a section of the alternative lip member of FIG. 10;
[0089] FIG. 12 is a perspective view of an acetabular cup prosthesis comprising the lip member of FIG. 10;
[0090] FIG. 13 is a perspective view from above of one example of an impaction cap;
[0091] FIG. 14 is a view from above with of the impaction cap in position;
[0092] FIG. 15 is an enlarged view of part D of FIG. 14;
[0093] FIG. 16 is a cross section on line A-A of FIG. 14;
[0094] FIG. 17 is an enlarged view of part C of FIG. 16;
[0095] FIG. 18 is a cross section on line B-B of FIG. 16;
[0096] FIG. 19 is an enlarged view of part E of FIG. 18;
[0097] FIG. 20 is an enlarged view of part F of FIG. 18;
[0098] FIG. 21 is a perspective view from above with the plug component in position;
[0099] FIG. 22 is a schematic perspective view on cross section of FIG. 21;
[0100] FIG. 23 is a view on line A-A of FIG. 21
[0101] FIG. 24 is an enlarged view of section C of FIG. 23;
[0102] FIG. 25 is a cross section on line B-B of FIG. 23;
[0103] FIG. 26 is an enlarged view of part D of FIG. 25;
[0104] FIG. 27 is a view from above of a further configuration of lip member with an impaction cap in position;
[0105] FIG. 28 is a side view of the arrangement of FIG. 27 with a portion cut away;
[0106] FIG. 29 is an enlarged view of portion A of FIG. 28;
[0107] FIG. 30 is a perspective view in cross-section on line B-B of FIG. 27;
[0108] FIG. 31 is an alternative embodiment of the acetabular cup prosthesis of the present invention;
[0109] FIG. 32 is a perspective view of the acetabular cup prosthesis of FIG. 31 including an impaction cap;
[0110] FIG. 33 is a view of the arrangement of FIG. 32 from above;
[0111] FIG. 34 is a section view on line A-A of FIG. 33;
[0112] FIG. 35 is a view of the acetabular cup of FIG. 32 from above;
[0113] FIG. 36 is a section view on line B-B of FIG. 35;
[0114] FIG. 37 is a perspective view of a still further embodiment of an acetabular cup prosthesis of the present invention;
[0115] FIG. 38 is an impaction cap for use in the cup of FIG. 37;
[0116] FIG. 39 is a locking component for use with the impaction cap of FIG. 38;
[0117] FIG. 40 is a view from above illustrating the impaction cap and locking member in place on the prosthesis of FIG. 37;
[0118] FIG. 41 is a section view on line A-A of FIG. 40;
[0119] FIG. 42 is an enlarged view of portion C from FIG. 41;
[0120] FIG. 43 is a section view on line B-B of FIG. 41;
[0121] FIG. 44 is an enlarged view of portion D of FIG. 43; and
[0122] FIG. 45 is an illustration of the embodiment having a sacrificial portion.
[0123] One arrangement of an acetabular cup prosthesis in accordance with the present invention is illustrated in FIGS. 1 to 3. The cup prosthesis 1 which may be formed from a ceramic comprises an inner cup wall 2 and an outer cup wall 3. The inner cup wall 2 and the outer cup wall 3 meet at rim 4. It will be understood that whilst the cup is described as having inner and outer walls meeting at a rim, the cup will be solid. In this arrangement, an engagement formation 5 is provided on the outer cup wall 3.
[0124] A lip member 6, having a cooperating engagement formation 7, is located such that engagement formation 7 interconnects with engagement formation 5 such that the lip member is held in place. In this arrangement, the lip member extends upwardly and then inwardly in a horizontal orientation. In use, this lip member which is formed of a low modulus material such as polyetheretherketone, serves as an artificial labrum,
[0125] An alternative configuration of the lip member 6 is illustrated in FIGS. 4 to 6. In this arrangement, the lip member interconnects with the outer cup wall 3 via the respective engagement portions 7 and 5. In this arrangement, the lip member extends upwardly and then slopes inwardly. In use, this lip member which is formed of a low modulus material such as polyetheretherketone, serves as an artificial labrum.
[0126] A still further alternative configuration of the lip member 6 is illustrated in FIGS. 7 to 9. In this arrangement, a plurality of ribs 8 is located on the outer surface of the lip member. These assist with the initial fixation of the acetabular cup prosthesis and serve to resist rotation of the cup once it is implanted. The ribs illustrated in this embodiment may be applied in other embodiments. It will be noted that the engagement formations 7 and 5 in this embodiment are of a different shape to those illustrated in FIGS. 2 and 3 or FIGS. 5 and 7. It will be understood that the engagement formations may be of any shape provided that they function and thus any illustrated configuration can be used with any embodiment.
[0127] A still further arrangement of lip member 6 is illustrated in FIGS. 10 and 11. In this arrangement, the configuration of the lip member is similar to that of FIGS. 1 to 3 except that the inward portion rather than being of a consistent size has undulations such that it has a waved edge 8 having peaks 9 and troughs 10. FIG. 11 illustrates a portion of the lip member 6 such that its profile can be seen in cross-section.
[0128] The undulations of the lip member as illustrated in FIGS. 10 and 11 enable an impaction cap to be readily interlocked with the acetabular cup. One example of a suitable impaction cap 20 is illustrated in FIG. 13. Here the impaction cap is triangular in shape and the three lobes a, b, c, are sized such that they can pass between the troughs 10 of the wavy edge 6 of the lip 6 until the impaction cap is below the edge of the lip 6. It will then be rotated so that the lobes become situation beneath the peaks 9 of the waved edge such that the impaction cap 20 is held in position. In another alternative to increase strength a disc may be mounted beneath the triangular portion.
[0129] The cap 20 in position but prior to rotation is illustrated in FIG. 14 and an enlarged portion is illustrated in FIG. 15.
[0130] A central core 21 on the impaction cap enables it to be interlocked with an impaction tool (not shown). As illustrated in FIGS. 16 and 18, in one arrangement, the impaction cap 20 may include a central core 22 which in use extends into the cup and sits on the base of the inner cup surface 2 to provide additional support during impaction. Detail of the interaction between the impaction cap and the lip is illustrated in FIGS. 15, 17, 19 and 20.
[0131] Once the acetabular cup prosthesis 1 has been introduced into the pelvis, the cap 20 is removed. A plug component 9 is then put in place. The plug component 9 also has an undulated configuration such that it when it is in position it fits against the undulations of the lip member 6. This is illustrated in detail in FIGS. 24 to 26.
[0132] An alternative arrangement is illustrated in FIGS. 27 to 30. In this arrangement, rather than the lip member having undulations, it has a crenelated profile. The impaction cap may have cooperating crenels or it may have a plurality of tabs. The crenels on the cap or the tabs can be inserted through the spaces in the crenels in the lip member. When the cap is rotated it is locked under the crenels of the lip member. In an alternate arrangement, the cap may be a snap fit under the crenels of the lip member. As illustrated in FIG. 30 the internal structure of the impaction cap may be different to that illustrated in FIG. 18. However, it will be understood that the cap may be of any suitable configuration.
[0133] FIG. 31 illustrates an alternative acetabular cup prosthesis 30 which has an inner cup surface 31 and an outer cup surface 32. Engagement formation 33 extends around the circumference of the outer cup surface 32 proximal to the rim 34 of the cup. In this embodiment, the impaction cap 35 does not engage with a lip member but rather extends over the rim 34 such that the corresponding impaction engagement formation 36 on the impaction cap engages with that on the outer cup wall such that the impaction cap is held in position.
[0134] In the illustrated arrangement the impaction cap has a webbed structure. However, it will be understood that this webbed structure for the impaction cap cab be utilised with the lip member arrangements provided that it is provided with cooperating lobes to interact with the lip member. Similarly a more solid impaction cap such as those discussed above can be used in this embodiment provided that it is configured to extend over the rim of the cup and engage with the engagement formations 33.
[0135] Once the acetabular cup prosthesis 30 is in position, the impaction cap will be removed to leave a cup as illustrated in FIGS. 35 and 36. However, it will be understood that other configurations of cup may also be used. A lip member may then be placed in position to provide an artificial labrum.
[0136] A still further arrangement is illustrated in FIG. 37. In this arrangement, the acetabular cup which has an inner cup surface 41 and an outer cup surface 42 prosthesis 40 does not have engagement formations extending around the entire circumference. In contrast, there are three discrete areas in which the formations extend, 43a, 43b and 43c. In this arrangement, an impaction cap 44 is provided which extends over the rim 45 of the cup 40 and has three cooperating engagement formations 46a, 46b and 46c (not shown). As illustrated, the impaction cap 44 has a webbed configuration. However, it will be understood that any configuration of impaction cap.
[0137] The impaction cap 44 may be held in place simply by the interaction of the respective engagement formations, 43a and 46a, 43b and 46b and 43c and 46c. However, an additional locking member 50 may be used. Details of the components as assembled are illustrated in FIGS. 40 to 44.
[0138] A further arrangement is illustrated in FIG. 45. In this arrangement, the wall of the cup extends in a sacrificial portion 50 above the rim 51 of the cup. As illustrated, the engagement formation for engagement with the impaction cap or tool is on the inner wall surface 52 but it may alternatively or additionally be on the outer wall 53. The sacrificial portion may extend around the entire circumference or it may be made up of a plurality of tabs. Any number of tabs may be used but generally about 3 or 4 will suffice. Once the cup is impacted, the sacrificial portion may be removed.
