AU2021106303A4

AU2021106303A4 - Modular acetabular cup augment apparatus

Info

Publication number: AU2021106303A4
Application number: AU2021106303A
Authority: AU
Inventors: Declan Brazil; Christopher Burgess
Original assignee: Signature Orthopaedics Europe Ltd
Current assignee: Signature Orthopaedics Europe Ltd
Priority date: 2020-09-24
Filing date: 2021-08-21
Publication date: 2021-11-04
Anticipated expiration: 2029-08-21
Also published as: WO2022061416A1

Abstract

Apparatus comprising an acetabular cup having inner and outer surfaces, wherein: the outer surface comprises a plurality of buttresses having profiled inner side edges defining a plurality of respective recessed augment slide-in slots therebetween; and the acetabular cup comprises bone fixation screw cup apertures for respective slots, the cup apertures formed between the inner surface and respective slot outer surfaces between respective inner sides edges, the cup apertures being elongate and having a longitudinal axis aligned with that of a respective slot; and augments, each having a slide-in portion having profiled outer side edges conforming to inner side edges of the slots to slide-into any one of the slide-in slots, the slide-in portion having a bone fixation screw augment aperture formed between inner and outer surfaces thereof. 11 1/5 6 ~ Figure 1 Fiur1 Figure 2

Description

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Modular acetabular cup augment apparatus Field of the Invention

[1] This invention relates generally to modular acetabular cup augment apparatus.

Background of the Invention

[2] Severe bone loss in revision total hip arthroplasty may require patient-specific custom manufactured implants such as the Zimmer BiometTM Triflange TM Acetabular Component which is manufactured according to patient CT scan data.

[3] As patient specific manufacture is expensive and time-consuming, modular acetabular cup augment systems have been proposed including that disclosed in US 20080021568 Al (Tulkis et al., 2008) which uses a dovetail profile coupling element to slidably engage a groove formed within an augment.

[4] EP2242450B1(Meridew et al., 2010) and US 20190231539 Al (Justin et al., 2019) proposes an acetabular cup comprising an elongate slot or channel within which a coupling element can be engaged therealong.

[5] The present invention seeks to provide modular acetabular cup augment apparatus, which will overcome or substantially ameliorate at least some of the deficiencies of the prior art, or to at least provide an alternative.

[6] It is to be understood that, if any prior art information is referred to herein, such reference does not constitute an admission that the information forms part of the common general knowledge in the art, in Australia or any other country.

Summary of the Disclosure

[7] There is provided herein a modular acetabular cup augment apparatus comprising an acetabular cup having inner and outer surfaces. The outer surface comprises a plurality of buttresses having profiled inner side edges defining a plurality of respective recessed augment slide-in slots therebetween.

[8] The acetabular cup further comprises bone fixation screw cup apertures for respective slots. The apertures extend through the cup between an inner surface of the cup and a respective slot outer surface. The apertures are furthermore elongate and have a longitudinal axis aligned with that of the respective slot.

[9] The apparatus further comprises augments each having a slide-in portion having profiled outer side edges to slide into any one of the slide-in slots.

[10] The slide-in portion further comprises a bone fixation screw augment aperture between inner and outer surfaces of the slide-in portion.

[11] The augments may comprise a spacer-type augments comprising an outer surface

which extends away from the outer surface of the acetabular cup and having an inner

surface bearing conforming against an outer surface of the acetabular cup.

[12] The augments may further comprise a flange-type augment comprising a radial arm

comprising bone screw fixation apertures therethrough and an orthogonal insertion portion

configured to fit within any one of the slide-in slots and preferably continuously augment

the outer surface of the acetabular cup.

[13] The augments may further comprise a spacer plate type augment configured to

accommodate unused slots.

[14] As such, the present apparatus allows for the insertion of bone screws through the

acetabular cup at various angles with respect to the transverse plane. Furthermore, the

elongate nature of the apertures may allow for simultaneous insertion of more than one

bone screw therethrough if required. The bone screws may insert through elongate cup

apertures with or without augments attached thereto.

[15] Furthermore, the bone screws may insert through adjacently coupled augments so

as to secure the augments to the cup as opposed to necessitating augment independent

bone screws.

[16] Preferably, the augment apertures may be similarly elongate so as to allow for angle

adjustment of the bone screw therethrough also.

[17] Preferably, the cup and augment apertures comprise inner channels which may be

respectively sized such that a conical screw head comprising locking threading thereon may

lock against both apertures simultaneously, thereby locking the augment, especially the

flange-type augment) with respect to the acetabular cup.

[18] Other aspects of the invention are also disclosed.

Brief Description of the Drawings

[19] Notwithstanding any other forms which may fall within the scope of the present

invention, preferred embodiments of the disclosure will now be described, by way of

example only, with reference to the accompanying drawings in which:

[20] Figure 1 shows modular acetabular cup augment apparatus in accordance with an

embodiment;

[21] Figure 2 shows a top rear side perspective view of an acetabular cup of the apparatus

in accordance with an embodiment;

[22] Figure 3 shows a top frontside perspective view of the acetabular cup;

[23] Figure 4 shows a top plan view of the acetabular cup;

[24] Figures 5 and 6 illustrate a spacer-type augment being slidably engaged by the

acetabular cup in accordance with an embodiment;

[25] Figure 7 and 8 show different types of flange-type augments being slidably engaged

by the acetabular cup in accordance with an embodiment; and

[26] Figure 9 illustrates a spacer plate type augment being slidably engaged by the

acetabular cup in accordance with an embodiment.

Description of Embodiments

[27] Acetabular prosthesis apparatus 100 comprises an acetabular cup 101, typically of

metal such as titanium. The acetabular cup 101 comprises a concave inner surface 102 and

a convex outer surface 103.

[28] The acetabular cup 101 may comprise a rim 131 comprising a plurality of inner anti

rotation formations 132 which non-rotatably engaged respective protrusions of a polymeric

liner (not shown) inserted therein in use.

[29] In embodiments, the rim 131 may comprise a raised edge which may rise at an angle

of approximately 200across an arc of approximately 1800 of the rim 131.

[30] The cup 101 may comprise a plurality of perpendicular bone screw fixation apertures

for inserting rim bone screws 135 perpendicularly therethrough. The rim bone screws 135

may be 5 mm diameter rim screws in embodiments.

[31] The acetabular cup 101 may further comprise non-elongate bone fixation screw

apertures 136 therethrough. The non-elongate bone fixation screw apertures 136 may

comprise an inner channel 137 at the inner surface 102 of the cup 101. The non-elongate

bone fixation screw apertures 136 may be configured for engaging 6.5 mm diameter bone

fixation screws in embodiments.

[32] The cup 101 may comprise a threaded insertion tool engaging aperture 138.

[33] The outer surface 103 comprises a plurality of buttresses 104. The buttresses 104

comprise profiled outer side edges 105 defining a plurality of respective recessed augment

slide-in slots 106 therebetween. The buttresses 104 may diminish in width inferiorly such

that the slots 106 are of uniform cross-section for slide-in of augments.

[34] The cup 101 comprises a plurality of bone fixation screw cup apertures 107 for

respective slots 106.

[35] The apertures 107 extend through the cup 101 from the inner surface 102 to

respective slot outer surfaces 108.

[36] Each aperture 107 is preferably elongate and furthermore orientated such that a

longitudinal axis thereof is aligned with that of the respective slot 106.

[37] As such, bone fixation screws 109 may be engaged at various angles with respect to

the transverse plane.

[38] The bone fixation screw 109 may comprise a threaded shaft terminating in self

tapping flutes 110 at a distal end thereof. In embodiments, the shaft 109 may comprise a

diameter of 6.5 mm. A proximal end of the screw 109 may comprise a screw head 111. The

screw head 111 may comprise a star or hex drive socket.

[39] The screw head 111 may comprise locking threads thereon. Each cup aperture 107

may comprise a channel 112 thereabout at the inner surface 102. In embodiments, the

locking threads may lock against the channel 112.

[40] The apertures 107, channels 112 and screw head 111 may be configured such that

when secured, the screw head 111 is recessed within the channel 112 with respect to the

inner surface 102 of the cup 101 so as to not to interfere with a liner inserted therein.

[41] Each aperture 107 may comprise sufficient length to accommodate at least two bone

fixation screws 109 therebetween. In this regard, the aperture 107 may comprise a length

of greater than twice that of the diameter of the screw head 111. In embodiments, the

length of the aperture 107 is greater than 15 mm.

[42] The apparatus 100 further comprises at least one augment.

[43] Each augment comprises a slide-in portion 119 comprising profiled side edges 120 to

slide between the side edges 105 of the slide-in slots 106. In this regard, the side edges 120

may be parallel and uniformly spaced so as to slide-in tightly between the side edges 105 of

the slots 106.

[44] Figures 5 and 6 illustrate a spacer-type augment 113. The spacer-type augment 113

comprises an outer surface 123 extending away from the outer surface 103 of the cup 101.

Furthermore, the spacer-type augment 113 comprises a first inner surface 121 conforming

with the shape of the slot outer surface 108 to bear flush thereagainst and a second outer

surface 139 bear against the outer surface 103 of the cup 101 two simultaneously bear flush

thereagainst.

[45] The spacer-type augment 113 may comprise an exterior portion 114 comprising

osseo-integration material, such as porous titanium. The osseointegrated material may have

a porous structure on the bone contacting outer surface 123 for enhancing bone ingrowth

and fixation.

[46] The spacer-type augment 113 may comprise an interior portion 115 of polymeric

material.

[47] Spacer-type augments 113 may be provided of various sizes, including various

thicknesses and arc radius. In embodiments, a spacer-type augment 113 of relatively large

arc radius may comprises a pair of adjacent slide-in portions 119 so as to engage adjacent

slide-in slots 106 simultaneously.

[48] Figure 7 and 8 illustrate a flange-type augment 116. The flange-type augment 116

comprises a radial arm 117 comprising at least one bone fixation aperture 118 therein. The

radial arm 117 may be of uniform width and comprise a series of apertures 110 in alignment

therealong. Alternatively, the radial arm 117 may widen and comprise a plurality of bone

fixation apertures 118 adjacent with respect to a longitudinal axis thereof.

[49] The flange-type augment 116 may be integrally formed from a shaped metal plate

and a proximal end thereof bent through substantially 900 to form the sliding portion 119.

[50] An inner surface 121 of the slide-in portion 119 may comprise a curvature

conforming with that of the respective slot outer surface 108.

[51] The slide-in portion 119 comprises a bone fixation screw aperture 122 through from

between the inner surface 121 to an outer surface 123 of the augment.

[52] The aperture 122 may be elongate, having a longitudinal axis aligned with a length

of the slide-in portion 119.

[53] With reference to Figure 1, a slide-in slot 106 may engage a spacer-type augment

113 and wherein at least one, and in the embodiment shown two, bone fixation screws 109

are inserted through the respective cup aperture 107. Both screws 109 may extend through

the aperture 122 of the spacer-type augment 113. Alternatively, a superior screw 109 may extend through the aperture 122 and an inferior screw extend underneath a lower edge 124

of the spacer-type augment 113.

[54] As is further illustrated in Figure 1, two flange-type augments 116 are engaged to

slide-in slots 116 adjacent the spacer-type augment 113. The flange-type augments 116

illustrated comprise the uniform width and the widened flange-type augment 116.

[55] A lower edge 124 of the flange-type augment 116 may be rounded so as to conform

with a respective rounded edge 127 of the slide-in slot 106.

[56] Furthermore, the slide-in slot 106 may comprise a depth between the cup outer

surface 103 and the slide-in slot outer surface 108 and the insertion portion 119 of the

flange-type insert 116 may comprise a thickness such that an outer surface 123 of the slide

in portion 119 is substantially continuous with that of the outer surface 103 of the cup 102.

[57] Each flange-type augment 116 may be engaged by a single screw 109 extending

through the acetabular cup aperture 107 and the flange-type augment aperture 122.

[58] Screws 109 with threaded frustoconical locking heads 111 may be utilised to lock

against the channel112 of the cup aperture 107 and a channel125 of the augment aperture

122. The apertures 107, 122 and respective channels 112, 125 may be respectively sized

such that the augment channel 125 has a narrower cross-section as compared to the

acetabular cup channel 112 such that a frustoconical screw head 111 comprising locking

threads thereon may engage both channels 112, 125 simultaneously to thereby lock the

flange-type augments 116 in position with respect to the slot 106.

[59] In alternative embodiments, the cup apertures 107 (and, in embodiments, additionally or alternatively the augment apertures 122) may comprise formations for

engaging the bone fixation screws 109. In embodiments, at least one interval along the

elongate aperture 107, 122 may comprise bone screw engagement formations comprising

opposing helical threading portions through which the corresponding threads of the bone

screw shaft or head 111 may be turned. With regards to the embodiment shown in Figure

1, each aperture 107 may comprise a pair of adjacent bone screw engagement formations

for engaging to bone screws adjacently as shown. In further embodiments, the aperture 107

may comprise an intermediate bone screw engagement formation between the adjacent

bone screw engagement formations such that a single bone screw 109 may be engaged

centrally in isolation.

[60] In embodiments, the augments 113, 116 may be configured such that a flange-type

augment 116 and a spacer-type augment 113 may overlap when engaged to the cup 101.

With regards to the embodiment shown in Figure 1, there is shown the insertion portion 119 of the larger flange-type augment 116 extending between the outer surface 103 of the

cup 101 and the inner surface of the spacer-type augment 113 at an edge of the spacer-type

augment 113.

[61] In further embodiments, the slide in slots 106 and/or insertion portions 119 may be

configured such that an insertion portion 119 of a spacer-type augment 113 may slide into

a slot 106 behind an insertion portion 119 of a flange-type augment 116, thereby allowing

both a spacer-type augment 113 and a flange-type augment 116 to be engaged by the same

slide in slot 106 and engaged with a common bone screw 109.

[62] With reference to Figure 4, the slot 106 may encompass approximately half of the

periphery of the cup 101. In a preferred embodiment, the cup 101 comprises at least four

slots 106 and, in the embodiment shown, the cup 101 comprises 5 augments.

[63] In embodiments, the augments may comprise a blanking plate-type augment 126 for

covering unused slots 106. The blanking plate-type augment 126 may comprise a platelike

body having an upper edge 141 which, when the plate type augment 126 is engaged within

the slot 126, lies at or beneath the upper edge of the rim 131.

[64] The blanking plate-type augment 126 may comprise an inner surface conforming

with the slot outer surface 108 to bear flush thereagainst.

[65] The blanking plate-type augment 126 may similarly comprise outer profiled side

edges 128 which conform with the inner profiled side edges 105 of the slots 106 so as to be

slidably engaged therein. Each blanking plate-type augment 126 may similarly comprise a

rounded lower edge 129 conforming with the rounded lower edge 126 of the slot 105.

[66] Furthermore, the blanking plate-type augment 126 may comprise a thickness equal

or less than the depth of the slot 106 so as to continuously augment the outer surface 106

of the cup 101.

[67] The foregoing description, for purposes of explanation, used specific nomenclature

to provide a thorough understanding of the invention. However, it will be apparent to one

skilled in the art that specific details are not required in order to practise the invention.

Thus, the foregoing descriptions of specific embodiments of the invention are presented for

purposes of illustration and description. They are not intended to be exhaustive or to limit

the invention to the precise forms disclosed as obviously many modifications and variations

are possible in view of the above teachings. The embodiments were chosen and described

in order to best explain the principles of the invention and its practical applications, thereby

enabling others skilled in the art to best utilize the invention and various embodiments with

various modifications as are suited to the particular use contemplated. It is intended that the following claims and their equivalents define the scope of the invention.

[68] The term "approximately" or similar as used herein should be construed as being

within 10% of the value stated unless otherwise indicated.

Claims

Claims 1. Apparatus comprising: an acetabular cup having inner and outer surfaces, wherein: the outer surface comprises a plurality of buttresses having profiled inner side edges defining a plurality of respective recessed augment slide-in slots therebetween; and the acetabular cup comprises bone fixation screw cup apertures for respective slots, the cup apertures formed between the inner surface and respective slot outer surfaces between respective inner sides edges, the cup apertures being elongate and having a longitudinal axis aligned with that of a respective slot; and augments, each having a slide-in portion having profiled outer side edges conforming to inner side edges of the slots to slide-into any one of the slide-in slots, the slide-in portion having a bone fixation screw augment aperture formed between inner and outer surfaces thereof.
2. Apparatus as claimed in claim 1, further comprising bone fixation screws each comprising a head and wherein the cup aperture comprises a length greater than twice that of a diameter of the head.
3. Apparatus as claimed in claim 2, the cup aperture comprises a length of greater than mm.
4. Apparatus as claimed in claim 1, wherein the cup aperture comprises an interior peripheral cup channel at the inner surface of the cup.
5. Apparatus as claimed in claim 4, wherein the augment aperture comprises an interior peripheral augment channel at an inner surface of the augment.
6. Apparatus as claimed in claim 5, further comprising a bone fixation screw comprising a frustoconical head comprising locking threading thereon and wherein the channels are respectively sized such that the locking threading engages both channels simultaneously.
7. Apparatus as claimed in claim 4, further comprising a bone fixation screw comprising a head and wherein the channel and the head are configured such that the head is recessed with respect to the inner surface of the cup when engaged within the cup aperture.
8. Apparatus as claimed in claim 1, wherein each slide-in slot has a uniform cross section along a longitudinal axis thereof.
9. Apparatus as claimed in claim 1, wherein the augment aperture is elongate.
10. Apparatus as claimed in claim 1, wherein the augments comprise a spacer-type

augment comprising an outer surface configured to extend away from the outer surface of

the cup and an inner surface conforming in shape with an outer surface of the cup to bear

thereagainst.
11. Apparatus as claimed in claim 10, wherein the outer surface of the spacer-type

augment comprises osseo-integration material.
12. Apparatus as claimed in claim 11, wherein the osseo-integration material comprises

porous titanium.
13. Apparatus as claimed in claim 10, wherein an inner surface of the spacer-type

augment comprises polymeric material.
14. Apparatus as claimed in claim 1, wherein the augments comprise a flange-type

augment comprising a radial arm having at least one bone fixation screw aperture

therethrough.
15. Apparatus as claimed in claim 14, wherein the radial arm is of uniform with

comprising a plurality of bone fixation screw apertures and alignment there along.
16. Apparatus as claimed in claim 14, wherein the radial arm widens towards a distal end

thereof and comprises at least two bone fixation screw adjacent with respect to a

longitudinal axis thereof.
17. Apparatus as claimed in claim 14, wherein the slide-in portion is formed by an end

extending substantially orthogonally with respect to the radial arm.
18. Apparatus as claimed in claim 17, wherein each slot comprises a depth between the

outer surface of the cup and the respective slot outer surface and wherein the slide-in

portion comprises a thickness such that an outer surface of the slide-in portion continuously

augments the outer surface of the cup.
19. Apparatus as claimed in claim 17, wherein the slide-in portion comprises a rounded

lower edge and wherein each slot comprises a conforming rounded lower edge.
20. Apparatus as claimed in claim 1, wherein the augments comprise a blanking plate

type augment comprising a curved platelike body forming the slide-in portion, the augment comprising profiled outer side edges configured to slide within the respective profiled inner side edges of any one of the slots.
21. Apparatus as claimed in claim 20, wherein the augment defines an upper edge and

wherein, when the augment is engaged within a slot, the upper edge is at or beneath an

edge of the cup.
22. Apparatus as claimed in claim 21, wherein the augment defines a rounded lower

edge and wherein each slot comprises a rounded lower edge.
23. Apparatus as claimed in claim 1, wherein at least one of the cup and augment

apertures comprise bone screw engagement formations at at least one interval therealong.
24. Apparatus as claimed in claim 23, wherein the bone screw engagement formations

comprise opposing helical threading portions through which a corresponding thread or head

of a bone screw may be screwed.
25. Apparatus as claimed in claim 23, wherein the apertures comprise adjacent bone

screw engagement formations for the simultaneous adjacent insertion of two bone screws.
26. Apparatus as claimed in claim 25, wherein apertures may further comprise an

intermediate bone screw engagement formation between the adjacent bone screw

engagement formations.
27. Apparatus as claimed in claim 1, wherein the augments comprise a spacer-type

augment comprising an outer surface configured to extend away from the outer surface of

the cup and an inner surface conforming in shape with an outer surface of the cup to bear

thereagainst and wherein the augments comprise a flange-type augment comprising a radial arm having at least one bone fixation screw aperture therethrough and wherein the

apparatus is configured such that the insertion portion of the flange-type augment can

insert between the acetabular cup and the inner surface of the spacer-type augment.
28. Apparatus as claimed in claim 27, wherein the insertion portion is of the spacer-type

augment in the flange-type augment are configured to simultaneously engage the same slide

in slot and be secured by a common bone screw.
29. The method of assembling apparatus as claimed in claim 1, the method comprising

sliding slide-in portions of a plurality of augments into respective slide-in slots and inserting

bone fixation screws through respective collocating apertures of the cup and augments.