WO2024194376A1

WO2024194376A1 - Insert for setting cement mantle thickness

Info

Publication number: WO2024194376A1
Application number: PCT/EP2024/057496
Authority: WO
Inventors: James Anderson; David Horne
Original assignee: DePuy Ireland ULC
Current assignee: DePuy Ireland ULC
Priority date: 2023-03-22
Filing date: 2024-03-20
Publication date: 2024-09-26
Anticipated expiration: 2025-09-22
Also published as: CN120857920A; AU2024240086A1

Abstract

A surgical implant aperture insert (20) for use in a surgical implant system; and a surgical implant system for use in joint arthroplasty is provided including an aperture (8) and a surgical implant aperture insert. The insert increases the surface area of surgical components available for bone regrowth and can provide adaption means to allow the use of different fixings within the aperture.

Description

INSERT FOR SETTING CEMENT MANTLE THICKNESS

CROSS-REFERENCE

The present application is related to co-pending application serial number, presently unknown, filed on the same date as the present application at the same patent office by the same applicant, entitled "Insert for Locking Screw Adaption". These applications and the patents arising therefrom are incorporated herein by reference, including their specification and drawings.

FIELD

The present specification relates to an insert for positioning inside a through hole of a surgical device. In particular, an insert for setting the cement mantle thickness is provided. The disclosure also relates to a kit including at least two inserts of the disclosure. This disclosure also relates to a method of setting the cement mantle thickness of a cemented liner during surgery.

BACKGROUND

Joint arthroplasty is a well-known surgical procedure by which a diseased and/or damaged natural joint is replaced by a prosthetic joint. For example, in a hip arthroplasty surgical procedure, a patient's natural hip joint is partially or totally replaced by a prosthetic hip prosthesis.

The orthopaedic implants used in joint arthroplasty can be fixed in place in contact with bone using a cement composition (e.g., a polymethyl methacrylate cement). A cement composition can also be used to fix in place two co-operating implants, for example an acetabular cup and liner used during hip arthroplasty.

The cement/implant interface and bone/cement interface form mechanical interlocking interfaces which are accountable for implant fixation. When cementing a liner, it is necessary to ensure there is a sufficient cement mantle around it. If the cement mantle is not sufficient, there is a risk that increased shear forces might damage the cement locking mechanism, which may lead to failure of the construct.

The cement mantle is the space required between a first surgical implant and a second surgical implant, or a first surgical implant and the bone, which will be filled with cement for fixation, stability and strength.

The minimum cement mantle thickness is the minimum space required between a first surgical implant and a second surgical implant, in which to provide adequate fixation, stability and strength. A cement mantle that is too thin may weaken the durability and fixation strength of a prosthesis, whereas a cement mantle that is too thick may increase the risk of thermal-induced osteonecrosis.

An adequate cement mantle can be achieved by ensuring that the acetabular shell diameter and liner are compatible. For example, if the liner is too big, this will prevent an adequate cement mantle being formed between the liner and shell. Conversely, if the liner is too small, the cement mantle is likely to be too thick in at least part of the mantle.

SUMMARY

According to a first aspect of this disclosure there is provided a surgical implant aperture insert, the insert comprising: a body portion, the body portion providing a distal surface and a proximal surface, the body portion further providing an intermediate surface extending between the distal surface and the proximal surface; wherein a proximal portion of the intermediate surface includes a surgical implant aperture contacting portion; wherein a distal portion of the intermediate surface is provided which is distal to and extends beyond the surgical implant contacting portion, the distal portion of the intermediate surface providing a cement contacting portion; wherein the distal surface is a further surgical implant opposing portion. The body portion may have an axial extent, for instance a height. The axial extent may be considered between the distal surface and the proximal surface of the insert and/or along an axis of the surgical implant aperture and/or along an axis of the insert. The axial extent, for instance height, may be greater than the axial extent, for instance height, of a surgical implant aperture.

The extent of the distal portion of the intermediate surface and/or the extent of the cement contacting portion may define a minimum cement mantle thickness.

The insert may provide a proximal portion of the body portion that has an axial extent or height hl which may be at least as great as the surgical implant aperture axial extent or height. The insert may provide a distal portion that has an axial extent or height h2 which, in use, may provide a space above a surrounding distal surface of the surgical implant for setting the minimum cement mantle thickness.

The distal surface of the insert may shaped to be proud of a section of the surgical implant, for instance proud of the profile of an adjacent, in use, section of the surgical implant. The section of the surgical implant may be planar, for instance a flange, or may be curved, for instance a plate. Where inserts are provided having different axial extents, for example height h2, for setting different minimum cement mantle thicknesses, the distal surface of the insert may be shaped to distinguish the insert from other distal surfaces of inserts having a greater or lesser axial extent. For example, the distal surface of the insert may be domed, pyramidal, or cuboidal in shape.

At least part of the insert may be formed of a porous material. The porous material may be selected and/or be adapted to promote cement interdigitation. In addition, some or all of the porous material may also be selected and/or adapted to promote bone ingrowth.

At least a part of the insert may be formed of a deformable material. The deformable material may be selected and/or adapted to deform on engagement by a surgical fixing. The deformable material may be selected and/or adapted to deform on engagement with a surgical implant aperture. The porous material and the deformable material may be the same material or may be different materials.

The insert may provide a first part of the body portion that is formed of a first material and a second part of the body portion that is formed of a second material. The first and second materials may be different from each other in their porosity and/or deformability. The distal portion may be formed of a material having a higher porosity than the proximal portion. The distal surface and/or the proximal surface may be partially defined by the first material and partially defined by the second material. The body portion may include a core of first material. The body portion may include a core surrounded radially by a second material.

The distal surface and/or further surgical implant opposing surface may be shaped to be complimentary to the profile of an adjacent, in use, section of a further surgical implant, wherein the further surgical implant may be for example an acetabular cup liner that may, in use, be positioned within the acetabular cup.

The shape of the distal surface and/or further surgical implant opposing surface, or distal portion may be angled to correspond to the curvature of a further surgical implant such as an acetabular cup and/or an acetabular cup liner. The distal portion may be convex or concave.

The further surgical implant opposing surface may be a further surgical implant contacting surface.

The distal portion of the insert may include a first cross-sectional profile in a plane. The proximal portion of the insert may define a second cross-sectional profile in a plane. The first cross-sectional profile may be larger than the second cross-sectional profile. The first cross-sectional profile may be a regular shape, for instance a circle. The second cross- sectional profile may be a regular shape, potentially the same type of regular shape, for instance a circle. The regular shapes may be concentric, for instance concentric circles. The insert may provide that the first cross-sectional profile in a plane is a circular profile. The insert may provide that the second cross-sectional profile in that plane is also a circular profile. The insert may provide that the second cross-sectional profile has a diameter less than that of the first cross-sectional profile.

The distal portion may be wedge shaped, for example, the distal portion of the insert may include a third cross-sectional profile in a plane perpendicular to the first and second cross-sectional profile and a fourth cross-sectional profile in a plane perpendicular to the first and second cross-sectional profiles. The third cross-sectional profile may be a regular shape, for instance a triangle. The second cross-sectional profile may be a regular shape, potentially the same type of regular shape, for instance a triangle. The third cross- sectional profile may be larger than the fourth cross-sectional profile.

The distal portion of the insert may further be provided a flange portion. The flange may include a distal surface and a proximal surface. The distal surface of the flange may be shaped to be complimentary to the profile of an adjacent, in use, section of a further surgical implant, for example an acetabular cup liner. The proximal surface of the flange may be shaped to be complimentary to the profile of an adjacent, in use, section of the surgical implant, for example, an acetabular cup.

One or both of the distal surface and/or the proximal surface of the flange may shaped to be flush with a section of at least one surgical implant, for instance to the profile of an adjacent, in use, section of a surgical implant. The section of the surgical implant may be planar or may be curved, for instance part hemispherical. The curvature of one or both of the distal surface and/or the proximal surface of the insert may have a radii, for instance a radii which is greater that the radii of the section of the surgical implant.

The proximal surface of the insert may shaped to be recessed relative to a section of the surgical implant, for instance to the profile of an adjacent, in use, section of the surgical implant. The section of the surgical implant may be planar or may be curved, for instance part hemispherical. The insert may further comprise a through bore extending between the distal surface and the proximal surface. The through bore may be defined by a through bore surface. The through bore surface may include a surgical fixing contacting portion. The intermediate surface may define a first cross-sectional profile in a plane. The through bore surface may define a second cross-sectional profile in that plane. The second profile may lie within the first profile.

At least a part of the insert may be formed of a deformable material. The deformable material may have a first pre-deformation state for the through bore surface and a first post-deformation state for the through bore surface. The shape of the through bore surface may be different in the first post-deformation state to the shape of the through bore surface in the first pre-deformation state. The through bore surface in the first postdeformation state may be adapted to engage with one or more surfaces of a surgical fixing. The through bore surface may include a bone engaging surgical fixing contacting portion.

The insert may provide that the through bore surface includes a bone engaging surgical fixing contacting portion. The contacting portion may be provided by deformation of the through bore surface and/or by a thread provided by the through bore surface and/or by the surgical fixing cutting a thread in the through bore surface.

At least a part of the insert may be formed of a deformable material, the deformable material having a second pre-deformation state for the intermediate surface. The deformable material may have a second post-deformation state for the intermediate surface. The shape of the intermediate surface may be different in the second postdeformation state to the shape of the intermediate surface in the second pre-deformation state. For instance, the shape of the intermediate surface may be deformed to engage with a surgical implant aperture, for instance one or more contact surfaces thereof, for instance a through hole thereof. The insert may provide the through intermediate surface in the second post-deformation state is adapted to engage with one or more surfaces of a surgical implant aperture. The one or more surfaces may include or be: a surface defining the surgical implant aperture; a surface defining a through bore in the surgical implant; a distal surface of the surgical implant; a proximal surface of the surgical implant.

The through bore surface may be provided with a tapered bore, for instance with a screw thread.

The first cross-sectional profile in a plane of the intermediate surface may be a circular profile. The second cross-sectional profile in that plane of the through bore surface may be a circular profile and have a diameter less than that of the first cross-sectional profile.

The cross-section of the second cross-sectional profile may reduce along the axis of the through bore, for instance due to the tapering of the bore from distal to proximal ends. The cross-section of the first cross-sectional profile may reduce along the axis of the through bore, for instance due to the tapering of the intermediate surface over part of the transition from distal to proximal ends. The intermediate surface may have a maximum first cross-sectional profile at the distal surface. The intermediate surface may have a minimum first cross-sectional profile at the proximal surface. The intermediate surface may have a minimum first cross-sectional profile from an intermediate position to the proximal surface, for instance to provide a cylindrical section. The intermediate surface may transition from the maximum cross-sectional profile to a minimum cross-sectional profile to provide a curved intermediate surface, for instance a bowl like section.

The insert may be a 3D printed insert. The insert may be 3D printed with one or more other components, for instance the surgical implant aperture and/or surgical implant.

The first aspect of the disclosure may include any of the features, options and possibilities set out elsewhere in this document, including in the other aspects and description of the embodiments.

According to a second aspect of the disclosure, there is provided a surgical kit, the kit comprising: one or more surgical implant aperture inserts, the insert comprising: a body portion, the body portion providing a distal surface and a proximal surface, the body portion further providing an intermediate surface extending between the distal surface and the proximal surface; wherein a proximal portion of the intermediate surface includes a surgical implant aperture contacting portion; wherein a distal portion of the intermediate surface is provided which is distal to and extends beyond the surgical implant contacting portion, the distal portion of the intermediate surface providing a cement contacting portion; wherein the distal surface is a further surgical implant opposing portion; and the kit further comprising one or more surgical implants, at least one of the surgical implants including at least one surgical implant aperture.

The surgical implant may be an orthopaedic implant. The surgical implant may be one or more of an acetabular shell; a partial acetabular shell; an acetabular shell liner; or a acetabular cage.

The surgical implant, for instance a surgical implant aperture thereof, may be provided with a threaded insert retention element.

The surgical implant may include at least one surgical implant aperture which is a through hole, and at least one surgical implant aperture which is a blind bore. The surgical implant may include a grid of blind bore surgical implant apertures.

The surgical kit may further include one or more further surgical implants, for example of different types and/or different sizes of the same type of surgical implant. For example, the surgical kit may further include one or more acetabular cup liners of different sizes. In use, the liner may, for example, be inserted into the acetabular cup so that the insert, which has been inserted into an aperture of the acetabular cup, prevents the liner from coming into direct contact with the acetabular cup. The insert provides a space between the surgical implant and the further surgical implant, into which cement can be placed, the space being the minimum cement mantle. The surgical kit may further comprise one or more surgical fixings, for instance one or more screw fixings, for instance one or more non-lockable fixings and/or one or more lockable fixings. Two or more different types and/or different sizes of surgical fixings may be provided.

The kit may comprise at least two surgical implant aperture inserts including distal portions shaped to be complimentary to the profile of different portions of an adjacent, in use, section of a surgical implant.

The kit may comprise a first surgical implant aperture insert having a distal portion having an axial extent, for instance a height, and a second surgical implant aperture insert having a distal portion having an axial extent, for instance height, and wherein the axial extent, for instance height, of the first surgical implant aperture insert may be greater than the axial extent, for instance height, of the second surgical implant aperture insert. The kit may comprise a variety of inserts having a variety of different axial extents, for instance heights. The axial extents, for instance heights, may range from 1 mm to 7mm. The kit may comprise a variety of inserts having a variety of different axial extents, for instance heights, suitable for insertion into a blind bore surgical implant aperture and/or the kit may comprise a variety of inserts having a variety of different axial extents, for instance heights, suitable for insertion into a through hole surgical implant aperture.

The kit may comprise a first surgical implant aperture insert having a distal portion shaped to be complimentary to a specific area of a surgical implant surface, and a second surgical implant aperture insert having a distal portion shaped to be complimentary to a specific area of a different surgical implant surface. The kit may comprise a variety of inserts having a variety of different shapes to correspond to a surgical implant having an angled surface, for example. The variety of inserts may comprise inserts having different shaped cement contacting portions. The different shapes can be used by the surgeon to differentiate between different sizes of insert, wherein the size may refer to the differing axial extents, for instance heights, of the inserts. The kit may comprise one or more surgical implants comprising at least one blind surgical implant aperture for use with the variety of inserts.

The second aspect of the disclosure may include any of the features, options and possibilities set out elsewhere in this document, including in the other aspects and description of the embodiments.

According to a third aspect of the disclosure, there is provided an orthopaedic implant system comprising one or more surgical implant aperture inserts according to any part of the first aspect, together with one or more orthopaedic implants, at least one of the orthopaedic implants including at least one surgical implant aperture.

The orthopaedic implant system may provide that: a. the one or more orthopaedic implants includes a first orthopaedic implant having a concave inner surface, a convex outer surface positioned opposite the concave inner surface, and at least one surgical implant aperture extends between the concave inner surface and the convex outer surface, the at least one surgical implant aperture extending a length between the concave inner surface and the convex outer surface, and/or b. the surgical implant aperture insert has an axial length greater than the length of the at least one surgical implant aperture such that the surgical implant aperture insert extends an axial extent or height beyond the concave inner surface when the surgical implant aperture insert is coupled to the first orthopaedic implant, the axial extent or height defining a minimum cement mantle thickness.

The orthopaedic implant system may further comprise a second orthopaedic implant including a convex outer surface, wherein: a. the concave inner surface of the first orthopaedic implant defines a cavity sized to receive the second orthopaedic implant, and/or b. the convex outer surface of the second orthopaedic implant is sized to engage a cement mantle positioned on the concave inner surface of the first orthopaedic implant having the minimum cement mantle thickness.

The third aspect of the disclosure may include any of the features, options and possibilities set out elsewhere in this document, including in the other aspects and description of the embodiments.

According to a fourth aspect of the disclosure there is provided a method of adapting a surgical implant aperture to create a minimum cement mantle, the method comprising a) selecting a surgical implant aperture insert to insert into a surgical implant aperture of a first surgical implant; b) inserting a surgical implant aperture insert into the surgical implant aperture; c) applying cement to the surgical implant, so that the cement is level with a distal surface of the insert; d) inserting a further surgical implant into the first surgical implant, wherein the insert comprises: a body portion, the body portion providing a distal surface and a proximal surface, the body portion further providing an intermediate surface extending between the distal surface and the proximal surface; wherein a proximal portion of the intermediate surface includes a surgical implant aperture contacting portion; wherein a distal portion of the intermediate surface is provided which is distal to and extends beyond the surgical implant contacting portion, the distal portion of the intermediate surface providing a cement contacting portion; wherein the distal surface is a further surgical implant opposing portion.

The method may include selecting: a) one or more surgical implant aperture inserts to correspond with the minimum cement mantle required for a particular surgical procedure; b) one or more surgical implant aperture inserts to correspond with a specific profile of one or more surgical implants; c) one or more surgical implant apertures to receive an insert, but not receive a surgical fixing; d) one or more surgical implant apertures to receive a first size or first type of fixing, for instance for insertion into an insert in a surgical implant aperture; e) one or more surgical implant apertures to receive a second size or second type of fixing, for instance for insertion into a surgical implant aperture devoid of an insert.

The method may include that the first surgical implant includes one or more through hole surgical implant apertures and one or more blind bore surgical implant apertures.

The method may include that a plurality of blind bore surgical implant apertures are provided and that the plurality of blind bore surgical implant apertures are in a grid formation.

The method may include selecting one or more through hole surgical implant apertures to receive an insert. The method may include selecting one or more blind bore surgical implant apertures to receive an insert. The method may include selecting a combination of through hole and blind bore surgical implant apertures to receive an insert.

The method may include that the insert provides at least a part of the insert formed of a porous material. The method may include selecting an insert having a particular porosity adapted for optimal cement interdigitation.

The method may include that the insert further provides a distal portion which is a flange portion. The method may include selecting an insert having a flange shaped to be complimentary to the profile of an adjacent section of a surgical implant and the proximal surface of the flange that is shaped to be complimentary to the profile of an adjacent section of a different surgical implant.

The method may include that the insert further provides that the intermediate surface defines a first cross-sectional profile in a plane, wherein the through bore surface defines a second cross-sectional profile in that plane and wherein the second profile lies within first profile.

The method may include that the insert provides at least a part of the insert formed of a deformable material. The method may include a deformable material being deformed by engagement by a surgical fixing with the deformable material and/or by insertion of the insert into the surgical implant aperture.

The method may further include that the insert provides a through bore surface which engages with one or more surfaces of a surgical fixing.

The method may further include that the insert provides at least a part of the insert formed of a deformable material, the deformable material having a first pre-deformation state for the through bore surface and a first post-deformation state for the through bore surface. The method may further provide that the shape of the through bore surface is different in the first post-deformation state to the shape of the through bore surface in the first pre-deformation state. The difference in shape may be caused by engagement by the surgical fixing with the deformable material and/or by insertion of the surgical fixing into the through bore.

The method may provide that the through bore surface includes a bone engaging surgical fixing contacting portion.

The method may provide that the insert comprises a cement contacting portion and wherein a first insert of a first size has a different shaped cement contacting portion to a second insert of a second size.

The method may further provide that the insert provides at least a part of the insert formed of a deformable material, the deformable material having a second predeformation state for the intermediate surface and a second post-deformation state for the intermediate surface. The method may further provide that the shape of the intermediate surface is different in the second post-deformation state to the shape of the intermediate surface in the second pre-deformation state. The difference in shape may be caused by engagement by the surgical implant aperture with the deformable material and/or by insertion of the insert into the surgical implant aperture.

The deformable material may be polymethyl methacrylate (PMMA) cement. PMMA inserts may be 3D printed or injection moulded.

The method may further provide that insert provides an intermediate surface in the second post-deformation state which engages with one or more surfaces of a surgical implant aperture.

The fourth aspect of the disclosure may include any of the features, options and possibilities set out elsewhere in this document, including in the other aspects and description of the embodiments.

According to a fifth aspect of the disclosure there is provided a method of implanting a first surgical implant and a further surgical implant, the method comprising: a) selecting the first surgical implant, the first surgical implant having at least one surgical implant aperture; b) implanting the first surgical implant at a surgical site in a patient; c) selecting a surgical implant aperture insert to insert into the surgical implant aperture of the first surgical implant; d) inserting the surgical implant aperture insert into the surgical implant aperture of the first surgical implant; e) applying cement to the first surgical implant; f) inserting a further surgical implant into the first surgical implant to implant the further surgical implant at a surgical site in a patient; wherein the insert comprises: a body portion, the body portion providing a distal surface and a proximal surface, the body portion further providing an intermediate surface extending between the distal surface and the proximal surface; wherein a proximal portion of the intermediate surface includes a surgical implant aperture contacting portion; wherein a distal portion of the intermediate surface is provided which is distal to and extends beyond the surgical implant contacting portion, the distal portion of the intermediate surface providing a cement contacting portion; wherein the distal surface is a further surgical implant opposing portion.

The method of implanting, wherein step e) provides for applying the cement to the first surgical implant, so that the cement is level with a distal surface of the insert. The method of implanting, wherein the surgical implant apertures creates a minimum cement mantle between the first surgical implant and the second surgical implant.

The method of implanting may provide that step c) and/or step d) are provided before step b). The method of implanting may provide that step c) and/or step d) are provided after step b). The method of implanting may provide that step e) is applied to the first surgical implant before step b). The method of implanting may provide that step e) is applied to the first surgical implant after step b).

The method of implanting may include using: a) one or more surgical implant aperture inserts to correspond with the minimum cement mantle required for a particular surgical procedure; b) one or more surgical implant aperture inserts to correspond with a specific profile of one or more surgical implants; c) one or more surgical implant apertures to receive an insert, but not receive a surgical fixing; d) one or more surgical implant apertures to receive a first size or first type of fixing, for instance for insertion into an insert in a surgical implant aperture; e) one or more surgical implant apertures to receive a second size or second type of fixing, for instance for insertion into a surgical implant aperture devoid of an insert. The method of implanting may include that the first surgical implant includes one or more through hole surgical implant apertures and one or more blind bore surgical implant apertures.

The method of implanting may include that a plurality of blind bore surgical implant apertures are provided and that the plurality of blind bore surgical implant apertures are in a grid formation.

The method of implanting may include providing one or more inserts in one or more through hole surgical implant apertures. The method of implanting may include providing one or more inserts in one or more blind bore surgical implant apertures to receive an insert. The method of implanting may include providing one or more inserts in a combination of through hole and blind bore surgical implant apertures.

The method of implanting may include the use of one or more inserts that provide at least a part of the insert formed of a porous material. The method of implanting may include using one or more inserts having a particular porosity adapted for optimal cement interdigitation.

The method of implanting may include using one or more inserts that further provide a distal portion which is a flange portion. The method of implanting may include using one or more inserts having a flange shaped to be complimentary to the profile of an adjacent section of a surgical implant and the proximal surface of the flange that is shaped to be complimentary to the profile of an adjacent section of a different surgical implant.

The method of implanting may include using one or more inserts that further provide that the intermediate surface defines a first cross-sectional profile in a plane, wherein the through bore surface defines a second cross-sectional profile in that plane and wherein the second profile lies within first profile.

The method of implanting may include using one or more inserts that provide at least a part of the insert formed of a deformable material. The method of implanting may include using a deformable material being deformed by engagement by a surgical fixing with the deformable material and/or by insertion of the insert into the surgical implant aperture.

The method of implanting may further include using one or more inserts that provide a through bore surface which engages with one or more surfaces of a surgical fixing.

The method of implanting may further include using one or more inserts that provide at least a part of the insert formed of a deformable material, the deformable material having a first pre-deformation state for the through bore surface and a first post-deformation state for the through bore surface. The method of implanting may further provide that the shape of the through bore surface is different in the first post-deformation state to the shape of the through bore surface in the first pre-deformation state. The difference in shape may be caused by engagement by the surgical fixing with the deformable material and/or by insertion of the surgical fixing into the through bore.

The method of implanting may use one or more inserts that provide that the through bore surface includes a bone engaging surgical fixing contacting portion.

The method of implanting may use one or more inserts that provide that the insert comprises a cement contacting portion and wherein a first insert of a first size has a different shaped cement contacting portion to a second insert of a second size.

The method of implanting may use one or more inserts that further provide that the insert provides at least a part of the insert formed of a deformable material, the deformable material having a second pre-deformation state for the intermediate surface and a second post-deformation state for the intermediate surface. The method of implanting may use one or more inserts that further provide that the shape of the intermediate surface is different in the second post-deformation state to the shape of the intermediate surface in the second pre-deformation state. The difference in shape may be caused by engagement by the surgical implant aperture with the deformable material and/or by insertion of the insert into the surgical implant aperture. The method of implanting may use a deformable material which may be polymethyl methacrylate (PMMA) cement. PMMA inserts may be 3D printed or injection moulded.

The method of implanting may use one or more inserts that further provide that insert provides an intermediate surface in the second post-deformation state which engages with one or more surfaces of a surgical implant aperture.

The fifth aspect of the disclosure may include any of the features, options and possibilities set out elsewhere in this document, including in the other aspects and description of the embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of this disclosure will be described hereinafter, by way of example only, with reference to the accompanying drawings in which like reference signs relate to like elements and in which:

Figure 1 is an illustration of a variety of surgical implants for which the disclosure is useful;

Figure 2a a side view of an insert according to a first embodiment;

Figure 2b is a cross-sectional view of the insert of Figure 2a;

Figure 3 is an illustration of a further embodiment of the disclosure in which different parts of the insert are formed of different materials;

Figure 4 is a cross-sectional elevation of an embodiment of the insert, shown inserted into a through hole of an acetabular shell;

Figure 5 is a cross-sectional view of an embodiment of the insert, shown inserted into a through hole of an acetabular shell with a liner cemented into position (cement not illustrated);

Figure 6 is a perspective view of an acetabular cup with the insert of the first embodiment inserted into a screw hole of the acetabular shell; Figures 7a and 7b are an illustration of a variety of sizes and types of fixing which can be used with the disclosure;

Figure 8 is an illustration of an acetabular cup with the insert inserted and a locking screw driven into the through bore of the insert;

Figure 9a is a cross-sectional view of an acetabular shell including blind bore surgical implant apertures in addition to through hole surgical implant apertures;

Figure 9b is a cross-sectional view of three different shaped inserts, each shown inserted into a blind bore surgical implant aperture of the acetabular shell of Figure 9a.

DETAILED DESCRIPTION

Referring to the drawings, Figure 1 shows a series of perspective views of examples of surgical implants, these being an acetabular revision cage 2, partial acetabular cup 4 and acetabular cup 6. Each of these surgical implants 2, 4, 6 are provided with a significant number of through holes 8 to accommodate fixings [not shown] in use. Only a small number of the through holes 8 would be used in most surgical instances, with the others being left as open through holes 8.

These are just some examples of the wide variety of surgical implants that the disclosure is relevant to, as for example, the disclosure can be used in surgical implants in which a minimum cement mantle is required between two components, such as an acetabular cup and a liner 70. The minimum cement mantle ranges from 1 mm to 7mm, depending on the type of implant and location.

Figure 2a provides a side perspective view of an embodiment of an insert 20 described with reference to an acetabular context of use. The insert 20 comprises a body portion 22 having a distal surface 24 which is provided with a distal opening 26 located at the distal end of a through bore 28 which extends through the body portion 22 to a proximal opening 30 provided in a proximal surface 32 of the body portion 22; see Figure 2b. The insert 20 is suitable for insertion into the through hole 8 of a variety of surgical implants, for example an acetabular shell, part shell or cage.

To retain the insert 20 in the surgical implant 2, 4, 6, the outside diameter di of at least a section S of the insert 20 is an interference fit with a complimentary section of the surgical implant 2, 4, 6. The section could be another section to the section S illustrated or could be the whole of the profile of the outer surface 34. This retention provides a first level of retention of the insert 20 relative to the surgical implant 2, 4, 6. A further and increased level of retention is described below.

The body portion 22 of the insert 20 includes a proximal portion 21 and a distal portion 23, as shown in Figure 4. The total height of the body portion 22 is greater than the height of the through hole 8 in the surgical implant 2, 4, 6 so that when the implant is retained within the implant 2, 4, 6, the distal portion 23 of the insert 20 protrudes from the surrounding distal surface 50 of the acetabular cup 6, as shown in Figure 4. The proximal portion 21 of the insert 20 has a height h 1 up to and including the height of a complimentary section of the surgical implant 2, 4, 6. The distal portion 23 of the insert 20 has a height h2 which provides a minimum cement mantle thickness when a liner 70 is positioned inside the surgical implant 2, 4, 6 and abuts distal surface 24. Typical heights of the distal portion 23 would be 1 mm to 7mm beyond the internal surface of the shell, as examples.

A minimum cement mantle thickness is the minimum space required between a first surgical implant and a second surgical implant, which will be filled with cement for fixation, stability and strength. A cement mantle that is too thin may weaken the durability and fixation strength of a prosthesis, whereas a cement mantle that is too thick may increase the risk of thermal-induced osteonecrosis.

The insert 20 is formed from a porous material, for allowing cement interdigitation. Cement interdigitation is the penetration of cement into a bone or an implant. The depth of interdigitation depends on factors such as the porosity of the bone or implant, the viscosity of the bone cement, and the temperature and humidity of the surgical environment. The porous material may promote bone growth, for instance on the proximal surface.

In this embodiment, the entire body portion 22 is formed from a porous material, for promoting cement interdigitation. Thus, the provision of the insert 20 in a through hole 8 in the surgical component 2, 4, 6 has a benefit in increasing the surface area of the surgical component 2, 4, 6 available for cement interdigitation. The insert 20 can be used largely to fill the through hole 8, even if no further use of the insert 20 is made, beyond its role in defining a minimum cement mantle thickness; visible in Figure 4 as this corresponds to the height in brackets of the distal portion 23 projecting above the surgical component 6.

In the embodiment illustrated in Figure 3, the body portion 22 of the insert is formed from different materials in different areas. For example, the outer volume 60 of the body portion 22 may be formed from the porous material, for promoting cement interdigitation, and the inner volume 62 of the body portion 22 which may comprise a through bore 28, may be formed from a different material, for instance optimised for deformation. The different material may be a non-porous material, or a porous material having different properties to the porous material of the outer volume 60. For any of the embodiments of the insert 20, the material from which it is constructed may also be deformable in surgical use. This ability to deform may apply to the entirety of the insert 20.

As shown in Figures 4 and 6, the insert 20 is shown in position within an opening, such as a through hole 8, in a surgical implant in the form of an acetabular cup 6 in this instance.

The geometry of the insert 20 is shaped so that its distal surface 24 is complimentary to the proximal surface 71 of a cement liner 70, as shown in Figure 5. In this way, the distal portion 23 of the insert 20 provides a minimal cement mantle that does not interfere with the seating of the liner 70, in use.

In the example shown in Figure 5, the distal surface 24 of the body portion 22 is concave so that when the insert 20 is positioned within the through hole 8 and a liner 70 is positioned on top, the curvature of the liner 70 is complimentary to the distal surface 24 of the body portion 22.

The height hz of the distal portion 23 can be varied so that different minimum cement mantle thicknesses can be selected, as appropriate for the surgical procedure. In some instances, each insert 20 positioned within the through hole 8 of the surgical implant has a single height such that when the liner 70 is positioned on top, the same minimum cement mantle thickness is present across the surface of the liner 70, for example a 2mm cement mantle.

Alternatively, it is possible to utilise inserts 20 having different heights in order to vary the minimum cement mantle thickness around the surface of the surgical implant resulting in a construct with eccentric bearing and shell centres which reduces the incidence of dislocations and/ or reduces joint pain.

For example, inserts 20 of different heights can bias the liner 70, for instance by 1 mm inferiorly and 7mm superiorly, in order to change the head centre relative to the cup. In this example, the head centre would be altered by 3mm relative to the cup.

The inserts 20 may also be used to vary joint tension. For example, if insert(s) 20 resulting in a minimum cement mantle of 7mm were inserted at the pole, and inserts 20 resulting in a minimum cement mantle of 2mm were inserted into through holes 8 around the periphery of the surgical implant, the effect would be to latera lise the bearing, which would increase the joint tension.

As shown in Figure 6, the through hole 8 of the surgical implant 6 is tapered. As such, the body portion 22 of the insert 20 may have a corresponding taper and a complimentary shape to the through hole 8 so that at least the proximal portion 21 of the insert 20 fills the through hole 8 once inserted.

The insert 20 can also act as an adaptor to allow a different size and/or type of fixing to cooperate with the insert 20, and hence the surgical implant 2, 4, 6, than would normally cooperate with the surgical implant 2, 4, 6 directly by being inserted in a through hole 8 without any insert 20 present. As shown in Figure 4, the through bore 28 has a diameter dz which is less than a diameter of the through hole 8 of the surgical device 2, 4, 6; which is equivalent to the external diameter di of the insert 20 plus a tolerance. Typical diameters for dz would be 2mm to 3.5mm, as examples only.

Whilst the through hole 8, without the insert 20 present, can securely receive fixings with an external diameter matching di, with the insert 20 present, the through bore 28 allows a smaller diameter fixing, such as a locking screw, to be engaged securely with the through bore 8 and hence with the surgical implant 2, 4, 6. This provides a second enhanced level of retention. This means that the surgeon can select those through holes 8 from amongst the full set of such through holes 8, which are: best to receive the larger size or first type of fixing; best to receive the smaller size or second type of fixing and so should have an insert 20 provided; and those through holes 8 which do not need to be provided with a fixing, but in which an insert 20 is to be provided to provide a minimum cement mantle across the surface of the implant 6. The surgeon may still select some through holes 8 not to receive a fixing or an insert 20. This flexibility of selection allows for provision of a minimum cement mantle across the surface of the implant, good stability for the implant, optimal fixing sizes and/or types to be used and maximum cement interdigitation to be promoted.

In some embodiments, which are not shown, the through bore 28 is unthreaded. In this construction, the thread of the fixing, such as a locking screw, may be a self-tapping screw and cut a thread into the side wall 36 of the bore to secure the fixing to the insert 20.

In other constructions which are not shown, the through bore 28 may comprise a thread formed in its side wall 36 along at least part of its length. In other constructions which are also not shown, the thread may only extend part way along the length of the side wall 36. The thread is complimentary to the thread of a fixing.

Figure 2b shows a thread 36 formed in the entire length of the side wall 38. The thread 36 in Figure 2a and 2b has a constant diameter and is complementary to the external thread of a fixing, such as a locking screw. When the fixing, in this case a locking screw, is driven through the through bore 28 of the insert 20, the locking screw deforms the porous material that the insert 20 is formed from resulting in the head of the locking screw 22 being captured within the deformed material, locking the insert 20 in place to both the locking screw and the surgical implant 6.

In the embodiment shown in Figure 4, as previously described for the earlier embodiment, the through bore 28 of the insert 20 still extends through the through hole 8 of the surgical implant 6, but in doing so it narrows the diameter which receives the fixing to the d? diameter of the through bore 28. In this embodiment, by virtue of the tapering, from distal to proximal sides, of the through bore 28, the diameter reduces to a minimum value ds. When the fixing, in this case a locking screw, is driven through the through bore 28 of the insert 20, the locking screw deforms the porous material that the insert 20 is formed from resulting in the head of the locking screw 22 being captured within the deformed material, locking the insert 20 in place to both the locking screw and the surgical implant 6.

Figure 7a illustrates a typical fixing 40 for cooperating directly with the surgical implant 2, 4, 6.

Figure 7b illustrates a reduced diameter fixing 42, compared with the typical fixing in Figure 7a, for cooperating with the insert 20, as an adapter, and hence the surgical component 2, 4, 6. The diameter d? of the through bore 28 corresponds to the diameter ds of a locking screw head 30, but with the diameter ds increased slightly to cause deformation of the insert 20 as the fixing is inserted. Deformation is controlled by the structure, porosity, and density of the insert 20 material. Both the fixings 42 are shown only partially inserted and so they still project above the distal surface 24. When fully inserted the distal end of the fixings 42 is flush with or recessed relative to the distal surface 42 of the insert 20.

Figure 8 illustrates a surgical implant 6 with the insert 20 inserted and a locking screw 42 being driven into the through bore 28 of the insert 20, for two inserts. As the head of the locking screw 42 enters the distal end of the bore 28, the bore 28 and the surrounding part of the distal surface 42 is deformed to accommodate and allow the flush or recessed positioning of the head of the fixings 42.

Figure 9a illustrates a surgical implant 10 such as a partial acetabular cup or an acetabular cup. These are just some examples of the wide variety of surgical implants that the disclosure is relevant to, as for example, the disclosure can be used in surgical implants in which a minimum cement mantle is required between two components, such as an acetabular cup and a liner 70. The minimum cement mantle ranges from 1 mm to 7mm, depending on the type of implant and location.

Similarly to the surgical devices discussed previously, the surgical implant 10 shown in the embodiment of Figure 9a is provided with a significant number of through holes 8 to accommodate fixings [not shown] in use. Only a small number of the through holes 8 would be used in most surgical instances, with the others being left as open through holes 8. In addition to the through holes 8, the surgical implant 10 is also provided with a number of surgical implant apertures 80. At least some of the surgical implant apertures 80 are blind holes that do not extend through the full thickness of the implant 10.

In some embodiments, the blind bore surgical implant apertures 80 are evenly spaced across the surface of the surgical implant 10. In some embodiments, the blind bore surgical implant apertures 80 are distributed so that they form a grid across the surface of the surgical implant 10. For example, the grid may consist of two or more levels, with at least 4 or more blind bore surgical implant apertures 80 spaced equally around the implant 10 on each level.

As shown in Figure 9a, the blind bore surgical implant apertures 80 are the same diameter, however the blind bore surgical implant apertures 80 may be different. As shown in Figure 9a, the surgical implant aperture 80 has a diameter which is equivalent to the external diameter of the surgical implant aperture contacting portion of the inserts 20a, 20c plus a tolerance. Typical diameters would be 2mm to 3.5mm, as examples only. Insert 20b includes a tapered surgical implant aperture contacting portion. In some instances, the surgical implant apertures 80 are tapered (not shown). As described previously, the inserts 20a, 20b, 20c provide a distal portion that has an axial extent or height h2 which, in use, provides a space above a surrounding distal surface of the surgical implant for setting the minimum cement mantle thickness. The distal portion is the cement contacting portion. Figure 9a shows inserts 20a, 20b, 20c having different shaped cement contacting portions. The different shapes can be used by the surgeon to differentiate between different sizes of insert. For example, the insert 20a has a distal portion which has an axial extent, for instance a height, and insert 20b has a distal portion having an axial extent, for instance height, which is greater than the axial extent, for instance height, of insert 20a. Similarly, the axial extent, for instance height, of insert 20c is greater than the axial extent, for instance height, of inserts 20b and 20a.

At least a part of the insert 20a, 20b, 20c may be formed of a deformable material. The deformable material may be selected and/or adapted to deform on engagement with the surgical implant aperture 80 of the surgical implant. The deformable material may be PMMA. Alternatively, or in addition, at least a part of the insert 20a, 20b, 20c may include orthogonal slits (not shown) along the axis of the insert to promote deformation upon insertion of the insert 20a, 20b, 20c into the surgical implant aperture 80.

In the embodiment shown in Figure 9a, the surgeon can select those blind bore surgical implant apertures 80 which are: best to receive an insert 20a, 20b, 20c and of which size; and those through holes 8 from amongst the full set of such through holes 8, which are: best to receive the larger size or first type of fixing; best to receive the smaller size or second type of fixing and so should have an insert 20 provided; and those through holes 8 which do not need to be provided with a fixing, but in which an insert 20 is to be provided to provide a minimum cement mantle across the surface of the implant 6. The surgeon may still select some through holes 8 and/or blind bore surgical implant apertures 80 not to receive a fixing or an insert 20, 20a, 20b, 20c. This flexibility of selection allows for provision of a minimum cement mantle across the surface of the implant, good stability for the implant, optimal fixing sizes and/or types to be used and maximum cement interdigitation to be promoted. The insert 20 in any of the embodiments may be 3D printed. The insert 20 may be 3D printed so that it is already in situ within the through hole 8 of a surgical implant 2, 4, 6, or can be inserted separately into a specific through hole 8.

The disclosure also relates to a method of adapting a through hole 8 in a surgical device to create a minimum cement mantle. The method additionally comprises the steps of adapting said through hole 8 suitable for a first size or type of fixing, such as a nonlocking screw, to be suitable for a second size of type of fixing, such as a locking screw. The method comprises the steps of first, providing a surgical implant including through holes 8, for instance for non-locking screw holes, and then providing an insert 20 according to any of the examples provided above. The insert 20 is then inserted into one of the through holes 8 and a liner 70 is cemented into place. If it would be preferential to use a second type of fixing before the liner 70 is cemented in place, an additional step includes inserting a second type of fixing, for instance a locking screw, into the through bore 28 of the insert 20 and subsequently cementing the liner 70 into place.

The disclosure also relates to a method of adapting a blind bore surgical implant aperture in a surgical device to create a minimum cement mantle. The method additionally comprises the steps of adapting a through hole 8 in the surgical device suitable for a first size or type of fixing, such as a non-locking screw, to be suitable for a second size of type of fixing, such as a locking screw. The method comprises the steps of first, providing a surgical implant including blind bore surgical implant apertures 80, and then providing an insert 20, 20a, 20b, 20c, according to any of the examples provided above. The insert 20, 20a, 20b, 20c is then inserted into one of the surgical implant apertures 80 and a liner 70 is cemented into place. If the surgical implant also includes through holes 8, for instance for non-locking screw holes, then it may be preferential to use a second type of insert before the liner 70 is cemented into place. An additional step includes providing an insert 20 according to any of the examples provided above. The insert 20 is then inserted into one of the through holes 8 and a liner 70 is cemented into place. If it would be preferential to use a second type of fixing before the liner 70 is cemented in place, a further additional step includes inserting a second type of fixing, for instance a locking screw, into the through bore 28 of the insert 20 and subsequently cementing the liner 70 into place.

There is also provided, a kit for adapting a through hole 8 to create a minimum cement mantle between an implant and a liner 70. The kit comprises at least two inserts 20 according to the insert described above and at least two different types of fixing.

There is also provided, a kit for creating a minimum cement mantle between an implant and a liner 70. The kit comprises a surgical implant including blind bore surgical implant apertures and at least two inserts 20, 20a, 20b, 20c according to the inserts described above. The kit may include inserts 20a, 20b 20c having different axial extents, or heights, to vary the thickness of the minimum cement mantle. The kit may further at least two inserts 20 according to the insert 20 described above and at least two different types of fixing, for adapting a through hole 8 to create a minimum cement mantle between an implant and a liner 70.

Although particular embodiments of this disclosure have been described, it will be appreciated that many modifications/additions and/or substitutions may be made within the scope of the claims. While the concepts of the present disclosure are susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and will be described herein in detail. It should be understood, however, that there is no intent to limit the concepts of the present disclosure to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives consistent with the present disclosure and the appended claims.

Claims

1. A surgical implant aperture insert, the insert comprising: a body portion, the body portion providing a distal surface and a proximal surface, the body portion further providing an intermediate surface extending between the distal surface and the proximal surface; wherein a proximal portion of the intermediate surface includes a surgical implant aperture contacting portion; wherein a distal portion of the intermediate surface is provided which is distal to and extends beyond the surgical implant contacting portion, the distal portion of the intermediate surface providing a cement contacting portion; wherein the distal surface is a further surgical implant opposing supporting portion.

2. A surgical implant aperture insert according to claim 1, wherein the proximal portion has an axial extent or height hl which is at least as great as the surgical implant aperture axial extent or height, and the distal portion has an axial extent or height h2 which, in use, provides a space above a surrounding distal surface of the surgical implant for setting the minimum cement mantle thickness.

3. A surgical implant aperture insert according to claim 1 or claim 2, wherein at least a part of the insert is formed of a porous material, the porous material being adapted to promote cement interdigitation.

4. A surgical implant aperture insert according to any preceding claim, wherein a first part of the body portion is formed of a first material and a second part of the body portion is formed of a second material, the first and second materials being different from each other in their porosity and/or deformability.

5. A surgical implant aperture insert according to any preceding claim, wherein the distal portion is formed of a material having a higher porosity than the proximal portion.

6. A surgical implant aperture insert according to any preceding claim, wherein the distal surface is shaped to be complimentary to the profile of an adjacent, in use, section of a surgical implant.

7. A surgical implant aperture insert according to any preceding claim, wherein the distal portion defines a first cross-sectional profile in a plane, and the proximal portion defines a second cross-sectional profile in a plane, and wherein the first cross-sectional profile is larger than the second cross-sectional profile.

8. A surgical implant aperture insert of any preceding claim, wherein the distal portion is a flange portion, the flange having a distal surface and a proximal surface and wherein the distal surface of the flange is shaped to be complimentary to the profile of an adjacent, in use, section of a further surgical implant and the proximal surface of the flange is shaped to be complimentary to the profile of an adjacent, in use, section of the surgical implant.

9. A surgical implant aperture insert of any preceding claim, further comprising a through bore extending between the distal surface and the proximal surface the through bore being defined by a through bore surface; wherein the through bore surface includes a surgical fixing contacting portion; and wherein the intermediate surface defines a first cross-sectional profile in a plane, wherein the through bore surface defines a second cross- sectional profile in that plane and wherein the second profile lies within the first profile.

10. A surgical implant aperture insert according to any preceding claim, wherein at least a part of the insert is formed of a deformable material, the deformable material having a first pre-deformation state for the through bore surface and a first post-deformation state for the through bore surface, the shape of the through bore surface being different in the first post-deformation state to the shape of the through bore surface in the first pre-deformation state.

11. A surgical implant aperture insert according to claim 9, wherein the through bore surface in the first post-deformation state is adapted to engage with one or more surfaces of a surgical fixing.

12. A surgical implant aperture insert according to any preceding claim, wherein the through bore surface includes a bone engaging surgical fixing contacting portion.

13. A surgical implant aperture insert according to any preceding claim, wherein at least a part of the insert is formed of a deformable material, the deformable material having a second pre-deformation state for the intermediate surface and a second post-deformation state for the intermediate surface, the shape of the intermediate surface being different in the second post-deformation state to the shape of the intermediate surface in the second pre-deformation state.

14. A surgical implant aperture insert according to claim 13, wherein the intermediate surface in the second post-deformation state is adapted to engage with one or more surfaces of a surgical implant aperture.

15. A surgical implant aperture insert according to any preceding claim, wherein the through bore surface is provided with a screw thread.

16. A surgical implant aperture insert according to any preceding claim, wherein the first cross-sectional profile in a plane of the intermediate surface is a circular profile and wherein the second cross-sectional profile in that plane of the through bore surface is also a circular profile and has a diameter less than that of the first cross- sectional profile.

17. A surgical implant aperture insert according to any preceding claim, wherein the cross-section of the second cross-sectional profile reduces along the axis of the through bore, for instance due to the tapering of the bore from distal to proximal ends.

18. A surgical implant aperture insert according to any preceding claim, wherein the cross-section of the first cross-sectional profile reduces along the axis of the through bore, for instance due to the tapering of the intermediate surface over part of the transition from distal to proximal ends.

19. A surgical implant aperture insert according to any preceding claim, wherein the insert is 3D printed.

20. A surgical kit, the kit comprising one or more surgical implant aperture inserts according to any of claim 1 to 19, and one or more surgical implants, at least one of the surgical implants including at least one surgical implant aperture.

21. A surgical kit according to claim 20, wherein the surgical implant is one or more of: an acetabular shell; a partial acetabular shell; an acetabular shell liner; a acetabular cage.

22. A surgical kit according to claim 20 or claim 21, wherein the kit comprises at least two surgical implant aperture inserts including distal portions shaped to be complimentary to the profile of different portions of an adjacent, in use, section of a surgical implant.

23. A surgical kit according to any of claims 20 to claim 22, wherein the kit comprises a first surgical implant aperture insert having a distal portion having an axial extent, and a second surgical implant aperture insert having a distal portion of a second axial extent, and wherein the first axial extent is greater than the second axial extent.

24. A surgical kit according to any of claims 20 to claim 23, wherein the kit further comprises one or more surgical fixings.

25. A surgical kit according to any of claims 20 to 23, wherein the one or more surgical implants comprises at least one blind bore surgical implant aperture.

26. An orthopaedic implant system comprising one or more surgical implant aperture inserts according to any of claim 1 to 19 and one or more orthopaedic implants, at least one of the orthopaedic implants including at least one surgical implant aperture.

27. An orthopaedic implant system of claim 26, wherein: a. the one or more orthopaedic implants includes a first orthopaedic implant having a concave inner surface, a convex outer surface positioned opposite the concave inner surface, and at least one surgical implant aperture extends between the concave inner surface and the convex outer surface, the at least one surgical implant aperture extending a length between the concave inner surface and the convex outer surface, and b. the surgical implant aperture insert has an axial length greater than the length of the at least one surgical implant aperture such that the surgical implant aperture insert extends an axial extent or height beyond the concave inner surface when the surgical implant aperture insert is coupled to the first orthopaedic implant, the axial extent or height defining a minimum cement mantle thickness.

28. An orthopaedic implant system of claim 27, further comprising a second orthopaedic implant including a convex outer surface, wherein: a. the concave inner surface of the first orthopaedic implant defines a cavity sized to receive the second orthopaedic implant, and b. the convex outer surface of the second orthopaedic implant is sized to engage a cement mantle positioned on the concave inner surface of the first orthopaedic implant having the minimum cement mantle thickness.

29. A method of adapting a surgical implant aperture to create a minimum cement mantle, the method comprising a) selecting a surgical implant aperture insert to insert into a surgical implant aperture of a first surgical implant; b) inserting a surgical implant aperture insert into the surgical implant aperture; c) applying cement to the surgical implant, so that the cement is level with a distal surface of the insert; d) inserting a further surgical implant into the first surgical implant, wherein the insert comprises: a body portion, the body portion providing a distal surface and a proximal surface, the body portion further providing an intermediate surface extending between the distal surface and the proximal surface; wherein a proximal portion of the intermediate surface includes a surgical implant aperture contacting portion; wherein a distal portion of the intermediate surface is provided which is distal to and extends beyond the surgical implant contacting portion, the distal portion of the intermediate surface providing a cement contacting portion; wherein the distal surface is a further surgical implant opposing portion.

30. A method of implanting a first surgical implant and a further surgical implant, the method comprising: a) selecting the first surgical implant, the first surgical implant having at least one surgical implant aperture; b) implanting the first surgical implant at a surgical site in a patient; c) selecting a surgical implant aperture insert to insert into the surgical implant aperture of the first surgical implant; d) inserting the surgical implant aperture insert into the surgical implant aperture of the first surgical implant; e) applying cement to the first surgical implant; f) inserting a further surgical implant into the first surgical implant to implant the further surgical implant at a surgical site in a patient; wherein the insert comprises: a body portion, the body portion providing a distal surface and a proximal surface, the body portion further providing an intermediate surface extending between the distal surface and the proximal surface; wherein a proximal portion of the intermediate surface includes a surgical implant aperture contacting portion; wherein a distal portion of the intermediate surface is provided which is distal to and extends beyond the surgical implant contacting portion, the distal portion of the intermediate surface providing a cement contacting portion; wherein the distal surface is a further surgical implant opposing portion.