WO2017067925A1

WO2017067925A1 - Clamping device

Info

Publication number: WO2017067925A1
Application number: PCT/EP2016/074972
Authority: WO
Inventors: Jeremy Whiting; Roderick John Mathias
Original assignee: Jri Orthopaedics Limited
Priority date: 2015-10-21
Filing date: 2016-10-18
Publication date: 2017-04-27
Also published as: GB201518632D0; GB2536520A

Abstract

A clamping device (20) for clamping to an implant, the clamping device comprising a base component (21) having a first edge (22) engageable with said implant; a clamping component (24) having engaging means engageable with said implant beyond said first edge so as to define an island of implant material therebetween; and a sliding interface (27) between said base component and clamping component capable of causing a pulling force to pull said engaging means towards said first edge upon application of an actuating force on the clamping component so as to grip said island of material between said base component and clamping component.

Description

CLAMPING DEVICE

TECHNICAL FIELD

The present disclosure relates to a clamping device for clamping to an implant. Aspects of the invention relate to a device and to an implant.

BACKGROUND

Degenerative changes in a hip joint may ultimately necessitate a total hip replacement in which the head of the femur, the acetabulum, or both, are replaced with prostheses, otherwise known as orthopaedic implants. An acetabular prosthesis generally comprises a metal or metal alloy cup or "shell" having a non-bearing bone- implant interface which sits against the host bone. The shell has an internal bearing surface for bearing against the head of the femur or a femoral prosthesis. The internal bearing surface of the shell is usually a liner of different material to the shell, the liner being selected for its bearing properties. The shell-liner interface could be a taper lock arrangement; in some cases the shell and liner comprise an integral or unitary component.

Occasionally, some patients that undergo a total hip replacement require subsequent revision surgery to replace the prosthesis with a new prosthesis known as a revision prosthesis. Owing to likely additional bone loss or defects, a revision prosthesis will normally need additional mounting points such as extension members or hooks for sufficient stability. Many types of prostheses suitable for revision are known.

One example is the "Capitole U" product from Evolutis France, see http://www.evolutisfrance.com/products/hip/acetabulum qb/dual-mobilitv-cup- capitole-u.html The shell of the Capitole U product includes a plurality of fixation plates and/or an obturator hole hook (these plates and hook being generally known as "augments") which can be fixed to the rim of the cup. These augments provide additional stability and offer a selection of fixing points to the surgeon who can select the most appropriate augment and fixings for the individual patient's needs. It can be difficult to fix a revision prosthesis to a badly degenerated site because there may be few available or suitable fixing sites for a conventional prosthesis if there is severe bone loss. The augments of the Capitole U product give the surgeon more options and make the prosthesis more adaptable to the specific patient.

However one problem with the Capitole U product is that there are a discrete number of fixing points for the augments. Each augment and the cup to which they are fixed will be subjected to significant forces when the surgery is over and the repaired joint is in use. A discrete number of fixing points for the augments is necessary to provide the required strength for use. The surgeon may need to try one augment arrangement at the surgical site, remove it, and then try another until the best arrangement is found. This adds time to the surgical procedure. Furthermore, the discrete number of fixing points for the augments may mean that an ideal arrangement cannot be found at all and the "best available" will need to be used.

It is an object of embodiments of the invention to at least mitigate one or more of the problems of the prior art.

SUMMARY OF THE INVENTION

Aspects and embodiments of the invention provide a clamping device for clamping to an implant and an implant to which the clamping device can be clamped as claimed in the appended claims.

According to an aspect of the invention, there is provided a clamping device for clamping to an implant, the clamping device comprising

a base component having a first edge engageable with said implant; a clamping component having engaging means engageable with said implant beyond said first edge so as to define an island of implant material therebetween; and

a sliding interface between said base component and clamping component capable of causing a pulling force to pull said engaging means towards said first edge upon application of an actuating force on the clamping component so as to grip said island of material between said base component and clamping component.

The clamping device of the present invention has numerous advantages over the known prior art. The engagement of the clamping component to the top face of the implant means that there is no impingement upon or detrimental effect on the bone- interfacing part of the outer surface of the implant. The sliding interface between the base component and clamping component and gripping of an island of implant material is unexpectedly able to provide a sufficiently strong clamping arrangement on the implant to cope with the in-use demands once the joint is active. In an embodiment said pulling force pulls said engaging means radially outwardly with respect to the implant to which the device is being clamped. The radially- outward direction is defined with respect to the centre of the implant which may be a part-spherical acetabular cup. Preferably said actuating force is a downwards force.

The base component may be a plate and/or the engaging means may be a hook.

The device may further comprise means to exert the actuating force, for example a spring. In another embodiment, the clamping device is formed from a shape memory alloy and the means to exert an actuating force is a memorised shape of said shape memory alloy. In another embodiment, the means to exert an actuating force is at least one screw, screwable through said base component and clamping component. In an embodiment, the clamping device is a unitary component.

In an embodiment, the base component is provided with an augment extending therefrom. The base component and augment may be formed as a unitary component. In an embodiment, the augment comprises at least one arm extending from said base component, the arm further comprising at least one hole for receiving a fixing therethrough to fasten the arm to bone. In another embodiment, the augment comprises at least one arm extending from said base component, the arm further comprising a hook. According to another aspect of the invention there is an implant, for example an acetabular cup, to which the clamping device of any of the preceding paragraphs can be clamped, the implant having an outer surface, an inner surface and a top face and further comprising:

a groove on its outer surface with which the first edge of the base component can engage;

a continuous notch on its top face with which the engaging means can engage; and wherein said island of implant material is defined between the groove and continuous notch.

The continuous notch and groove give the advantage that the clamping device can easily be located at any position around the periphery of the implant. There are potentially infinite placement "positions", in contrast to prior art devices having a discrete number of possible placement positions (such as the Capitole U product). In turn, this means that any augments attached to the clamping device can also readily be placed at any position around the periphery of the implant.

If the clamping device is placed in one position and it is desired to try another position, it is not necessary to completely remove the clamping device and implant from the surgical site, before re-positioning in another position. Loosening of the clamping device by partially releasing the actuating force to cause the engaging means to move slightly radially inwardly (i.e. away from the island of implant material) allows the clamping device to be moved around the implant, using the notch and/or groove as a "track" to guide movement, until a new position is selected at which point the clamping device is tightened again. This gives great flexibility to the surgeon in selecting the best position for augments.

Another advantage is that the clamping device does not require any increase in the amount of material needed for the implant (e.g. by way of additional material to give an increased wall thickness to provide sufficient strength). On the contrary, the arrangement described herein actually uses less material in the implant from which the groove and notch are cut out.

Preferably the groove on the outer surface is annular.

In an embodiment, the implant is a part-spherical cup, having an equator wherein the cup extends above the equator. The portion of the cup above the equator may be rotationally symmetrical. In an embodiment, the groove on the outer surface is at or above the equator.

Locating the notch and groove in a portion of the cup above the equator means that a clamping device attached thereto has no impact or effect on the normal bone- interface outer surface of the cup. The implant may be a joint replacement component, such as an acetabular cup. The acetabular cup may comprise an outer shell having said groove and continuous notch and an inner liner, receivable by the shell. According to another aspect of the invention there is provided a method of clamping a clamping device as described in any of the paragraphs above to an implant having an outer surface, an inner surface and a top face comprising:

engaging the first edge of the base component with a groove on the outer surface of the implant;

engaging the engaging means with a continuous notch on the top face of the implant; and

applying said actuating force on the clamping component so that the sliding interface between said base component and clamping component causes a pulling force to pull said engaging means towards said first edge so as to grip said island of material between said base component and clamping component.

Further features are defined in the appended claims.

Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and/or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and/or features of any embodiment can be combined in any way and/or combination, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and/or incorporate any feature of any other claim although not originally claimed in that manner. BRIEF DESCRIPTION OF THE DRAWINGS

One or more embodiments of the invention will now be described by way of example only, with reference to the accompanying drawings, in which:

Figures 1A and 1 B are a cross-sectional view and a plan view, respectively, of a clamping device and implant according to embodiments of the invention, wherein the clamping device is in a loose configuration; Figures 2A and 2B are a cross-sectional view and a plan view, respectively, of the clamping device of Figures 1 A and 1 B, wherein the clamping device is in a tightened configuration Figure 3A is a side view of a cup according to embodiments of the invention; Figure 3B is an enlarged partial view of the cup of Figure 3A;

Figure 4 is a perspective view of a clamping device and implant according to embodiments of the invention;

Figure 5 is an enlarged view of the clamping device of Figure 4; and

Figures 6A - 6C are perspective views of clamping devices according to other embodiments of the invention.

DETAILED DESCRIPTION

With reference to the Figures, an implant 1 comprises an acetabular cup 2 made from coated metal and defining an outer surface 4. The outer surface 4 has an annular groove 7 therein which extends around the circumference of the cup.

The implant has a bearing liner 3 defining an inner surface 5.

With reference to Figures 3A and 3B, the cup 2 is part-spherical having an equator 9 with a portion 10 of the cup extending upwardly beyond the equator 9. The majority 1 1 of the cup lies below the equator 9. The top face 6 of the cup has a continuous annular notch 8 formed therein, as can be seen in Figures 1 A and 1 B.

With reference to Figures 1A and 2A, a clamping device 20 comprises a base component 21 in the form of a plate having a first edge 22 which can engage with the annular groove 7 of the implant. The base component 21 has a screw-threaded aperture therein for receiving a fixing such as a screw 23.

The clamping device 20 also includes a clamping component 24 which sits on top of the base component 21 and also has an aperture therethrough to receive the screw 23 so that the base component and clamping component can be screwed together. The clamping component 24 has an engaging means in the form of a hook 25 for engaging with the notch 8 in the top surface of the implant. The relative positioning of the groove 7 and notch 8 is such that, when the first edge 22 and hook 25 respectively are engaged therein, the hook 25 is beyond the first edge 22, radially inwardly nearer to the centre of the implant. This means there is a portion of implant material, described herein as "an island" 26 of material at the top surface of the implant and located between the first edge 22 and hook 25 of the clamping component 24. This island 26 of material can be gripped firmly by the clamping device as will be described in more detail below.

The clamping component 24 includes a tapered surface which engages with a correspondingly tapered surface on the base component 21 at a sliding interface 27.

When the screw 23 is tightened to apply an actuating force on the clamping device 20, the clamping component 24 moves by sliding down the base component 21 at the sliding interface 27. This causes a pulling force on the hook 25 engaged in the notch 8. The hook 25 is pulled radially outwardly (with respect to the centre of the implant) and towards the first edge 22 of the base component. This grips or pinches the island 26 of implant material tightly.

Surprisingly, if the screw 23 is tightened sufficiently, the gripping of the island 26 is sufficient to hold the clamping device on the implant. It is easy to loosen the screw slightly if it is desired to reposition the clamping device with respect to the implant. Once the grip on the island 26 is released, it is possible to slide the clamping device around the periphery of the implant, using the groove 7 and/or notch 8 as "tracks" to guide the clamping device and then simply to retighten the screw 23 when the desired position is reached.

The base component 21 may include one or more radially-extending augments 30. Figures 4 and 6B shows two augments 30 of known type (commonly referred to as "screw plates") each having a number of fixing holes 31 to give the surgeon choice. The augments 30 may be of different lengths and are usually non-resiliently flexible so they can be bent to a desired shape by the surgeon. Another type of augment is shown in Figure 6C, this having a hook arrangement 32. Other types of augments are known and could equally be used. Indeed, with reference to Figures 6A, 6B and 6C, different types and/or numbers of augments may be used in alternative embodiments of the present invention. In the example shown in Figure 6A, a single screw plate 30 is used with the clamping device 20, whereas in the example shown in Figure 6B, two screw plates 30 are used.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed in this specification (including any accompanying claims, abstract and drawings), may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features. The invention is not restricted to the details of any foregoing embodiments. The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed. The claims should not be construed to cover merely the foregoing embodiments, but also any embodiments which fall within the scope of the claims.

Claims

1 . A clamping device for clamping to an implant, the clamping device comprising

2. A clamping device as claimed in claim 1 wherein said pulling force pulls said engaging means radially outwardly with respect to the implant to which the device is being clamped.

3. A clamping device as claimed in claim 1 or claim 2 wherein said actuating force is a downwards force.

4. A clamping device as claimed in any of the preceding claims wherein said base component is a plate.

5. A clamping device as claimed in any of the preceding claims wherein said engaging means is a hook.

6. A clamping device as claimed in any of the preceding claims, further comprising means to exert an actuating force.

7. A clamping device as claimed in claim 6, wherein the means to exert an actuating force is a spring

8. A clamping device as claimed in claim 6, wherein the clamping device is formed from a shape memory alloy and the means to exert an actuating force is a memorised shape of said shape memory alloy.

9. A clamping device as claimed in claim 6, wherein the means to exert an actuating force is at least one screw, screwable through said base component and clamping component.

10. A clamping device as claimed in any of the preceding claims, wherein the clamping device is a unitary component.

1 1 . A clamping device as claimed in any of the preceding claims, wherein the base component is provided with an augment extending therefrom.

12. A clamping device as claimed in claim 1 1 , wherein the base component and augment are formed as a unitary component.

13. A clamping device as claimed in claim 1 1 or claim 12, wherein the augment comprises at least one arm extending from said base component, the arm further comprising at least one hole for receiving a fixing therethrough to fasten the arm to bone.

14. A clamping device as claimed in claim 1 1 or claim 12, wherein the augment comprises at least one arm extending from said base component, the arm further comprising a hook.

15. An implant, for example an acetabular cup, to which the clamping device of any of claims 1 -14 can be clamped, the implant having an outer surface, an inner surface and a top face and further comprising:

a continuous notch on its top face with which the engaging means can engage; and

wherein said island of implant material is defined between the groove and continuous notch.

16. An implant as claimed in claim 15 wherein the groove is annular.

17. An implant as claimed in claim 16, wherein the implant is a part-spherical cup, having an equator wherein the cup extends above the equator.

18. An implant as claimed in claim 17, wherein the portion of the cup above the equator is rotationally symmetrical.

19. An implant as claimed in claim 17 or claim 18, wherein the groove is at or above the equator.

20. An implant as claimed in any of claims 15-19, wherein the implant is a joint replacement component.

21 . An implant as claimed claim 20, wherein the joint replacement component is an acetabular cup.

22. An implant as claimed in claim 21 , wherein the acetabular cup comprises an outer shell having said groove and continuous notch and an inner liner, receivable by the shell.

23. A kit comprising

a clamping device as claimed in any one of claims 1 to 14; and

an implant as claimed in any one of claims 15 to 22.

24. A method of clamping a clamping device as claimed in any of claims 1 -14 to an implant having an outer surface, an inner surface and a top face comprising:

25. A clamping device or implant substantially as described herein with reference to and as illustrated by any appropriate combination of the accompanying Figures.