WO2014118283A1

WO2014118283A1 - Instrument for use in manipulating an implant component

Info

Publication number: WO2014118283A1
Application number: PCT/EP2014/051813
Authority: WO
Inventors: Sarvesh CHINAGI; Hitendra PUROHIT
Original assignee: Depuy (Ireland)
Priority date: 2013-02-04
Filing date: 2014-01-30
Publication date: 2014-08-07

Abstract

An instrument (100) for manipulating an implant component (200) such as a femoral component includes a body (3) with a seat (24) mounted thereon and upon which bearing surfaces (201, 201 ') of the component sit. A pair of arms (27, 28) with return flanges (31, 32) can be used to grip the component. The arms include perpendicularly extending shafts (29, 30) with threaded portions at their end. A rotating thumb wheel (40) has a threaded internal bore (41) provided in a cavity (4) in the body. The shafts are received in the body and the threaded portions engage with the internal bore. Rotation of the thumb wheel causes the arms to move towards and away from each other and, as such, the separation between the arms can be adjusted to accommodate components are varying widths. The advantage is that the instrument enables prosthesis components of varying sizes to be manipulated but does not have excessive width which may limit the situations in which it can be used, or require excessively large incisions.

Description

INSTRUMENT FOR USE IN MANIPULATING AN IMPLANT COMPONENT

This invention relates to a surgical instrument for use in manipulating an implant component of an orthopaedic joint prosthesis, such as the femoral component of a knee joint prosthesis.

An implant component of an orthopaedic joint prosthesis that is to be implanted in a patient must be manipulated prior to and during the implantation procedure. It can be important to grip the component securely and in such a way as to not damage the surface of the component and in particular the highly polished bearing surface which engages another component of the joint prosthesis.

A knee joint prosthesis includes a femoral component and a tibial component. It is common to manipulate the femoral component using an instrument in which the component is held securely. An impaction force can be applied to the femoral component through the instrument. It is important that the polished bearing surface of the component is not damaged by the instrument during manipulation and application of the impaction force.

Femoral components come in different sizes and instruments need to be able to adapt to components of different sizes. They also need to grip the components securely without damaging the bearing surface.

US -5732992 discloses an instrument for gripping and manipulating a prosthesis component. It includes a handle and at least one jaw that can be moved to grip the prosthesis component. Each jaw has a pivot post retained in an aperture in the jaw and which facilitates a slight rotation of the jaw about an axis. This rotation occurs after gripping of the component to draw the component towards the base upon which it is seated to retain it in place. The pivot posts are threadably mounted on the ends of a threaded shaft member. The shaft member is rotated by means of a thumbwheel fixed to the shaft member, and rotation of the shaft member with respect to the posts moves the jaws together to grip the prosthesis component and effects rotation of the jaw. The width of the instrument is defined by the length of the threaded shaft.

According to a first aspect of the present invention, there is provided an instrument for manipulating an implant component of an orthopaedic joint prosthesis, the instrument comprising:

a body,

a seat mounted on the body for contacting a bearing surface of the implant component during manipulation of the implant component,

a first arm having a transversely extending first gripping member towards one end and a transversely extending first shaft member towards its opposite end, mounted on the body on one side of the seat with the first gripping member and the first shaft member facing towards the body,

a second arm having a transversely extending second gripping member towards one end and a transversely extending second shaft member towards its opposite end, mounted on the body on opposite side of the seat with the second gripping member and the second shaft member facing towards the body, so that inward movement of the first and second arms towards the body causes the first and second gripping members to engage the implant component in contact with the seat, and

an actuation member which is mounted for rotation on the body, each of the first and second shaft members on the first and second arms being connected to the actuation member so that rotation of the actuation member in a first rotational direction causes the first and second arms to move inwardly and rotation of the actuation member in a second rotational direction causes the first and second arms to move outwardly.

The first and second arms provide a jaw arrangement which can be adjusted to

accommodate implant components of varying widths. This means that the width of the instrument can be varied according to the width of the component.

An advantage of the present invention is that the instrument enables implant components of varying sizes to be manipulated, and that the size of the instrument will be

commensurate with the size of implant component being used. This in turn may allow a smaller incisions to be possible than with an instrument of constant width. For example, when smaller implant components are to be manipulated by the instrument, the instrument will have a smaller width which will reduce the need to make larger incisions than are really necessary in a patient's knee. In addition, the instrument is symmetrical in the coronal plane and can therefore be used reversibly.

Each of the first and second shaft members have a thread and the actuation member may have a first threaded portion for cooperation with the thread on the first shaft member and the actuation member may have a second threaded portion for cooperation with the thread on the second shaft member

The first and second threaded portions of the actuation member may be collinear.

As such, the actuating member and the threaded shaft members form a turnbuckle arrangement.

The threads on the first and second shaft members may be external and the actuation member may have an internal thread. Alternatively, the threads may be internal on the first and second shaft members with the actuating member having external threads.

As a further alternative, the actuation member can be provided with cam surfaces with cam followers provided on the first and second shaft members that cooperate with the cam surfaces. Detents may be provided on the cam surfaces to provide set widths.

The body may include at least one limiting slot provided in one of the shaft members which cooperates with a dowel provided in the body. The dowel can be received in the limiting slot, for example through an aperture in the body. This limits the distance by which the shaft member or each of the first and second shaft members can be translated thus mitigating against over extension. Preferably, each of the first and second shaft members has a limiting slot formed in it and the body includes first and second dowels, the first dowel being received in the slot in the first shaft member and the second dowel being received in the slot in the second shaft member. The dowels and the slots can limit the translation of the first and second members.

The first and second arms can be provided with guide pins that cooperate with apertures in the body to further assist in guiding and retaining the arms in the body.

The handle may be realeasably attached to the body using a pivoting latch that engages with a groove provided in the neck of the body. The pivoting latch is preferably biased towards the position in which it is retained in the groove. This can facilitate manipulation of the instrument.

The actuating member may have a ribbed external contour. This assists in rotating it with the use of a thumb while holding the instrument in the same hand.

The seat may have a concave bearing surface and a lug and the body may have a dowel inserted into the lug to secure the seat to the body.

The seat may be made of a material that doesn't damage the bearing surfaces of the implant component. Preferably, this is a heat resistant thermoplastic such as polyarylethersulphone (PAES) (as sold under the trade mark RADEL by Amoco Polymers Inc and Piedmont Plastics Inc).

The thread profile may be selected to facilitate self-locking.

Embodiments of the invention will now be described by way of example only with reference to the accompanying drawings of which:

Figure 1 is a perspective view of a surgical instrument of the invention when gripping a femoral component of a knee joint prosthesis;

Figure 2 is a front view of the instrument of Figure 2; Figure 3 is a side view of the instrument of Figure 2 in the direction of arrow III in Figure 2;

Figure 4 is a plan view of the instrument of Figure 2 in the direction of arrow IV in Figure 2;

Figure 5 is a cross-section along the line A- A in Figure 2; Figure 6 is a cross-section along the line B-B in Figure 4;

Figure 7 is a perspective view of the head of the instrument of Figure 1, with the arms in an extended position with respect to the body of the head;

Figure 8 is an exploded view of the head of Figure 7;

Figure 9 is a front view of the head of Figure 7;

Figure 10 is a plan view in the direction of arrow X in Figure 9;

Figure 11 is an underside view in the direction of arrow XI in Figure 10;

Figure 12 is a cross-section along the line C-C in Figure 9; and

Figure 13 is a cross-section along the line D-D in Figure 10.

Referring to the drawings, Figures 1 to 13 show a surgical instrument 100 which can be used to manipulate, and apply an implantation force to, a femoral component 200 of a knee joint prosthesis.

The surgical instrument 100 includes a head 1 and a handle 2. The head 1 comprises a substantially cuboid-shaped hollow body 3. The hollow body 3 has front and rear faces 5, 6, side walls 7, 8, an upper wall 9 and a lower wall 10 which define a cavity 4.

The lower wall 10 is shaped to define a collar 11 extending outwardly with a bore 12 running through it. The bore 12 is arranged to receive the neck 13 of the handle 2 for mounting the head 1 thereon.

The collar 11 includes a groove 43 for receiving a lip 50 of a head retaining mechanism 45 for retaining the handle 2 to the body 3.

The upper wall 9 has a substantially centrally located rectangular shaped aperture 21 provided therein extending into the cavity 4.

Each of the side walls 7, 8 have one aperture of a first pair of collinear circular apertures 17, 18 that extend through the side wall 7, 8 into the cavity 4.

One aperture of a second pair of collinear apertures 19, 20 is also provided in each of the side walls 7, 8 which extend longitudinally within the upper wall 9 and into the rectangular shaped aperture 21.

The front face 5 has three circular apertures 14, 15, 16 provided thereon. The first and second 14, 15 of the three circular apertures are provided at the same height, one in each of the side walls 7, 8 and extending longitudinally therein. The third aperture 16 extends within the upper wall 9 substantially equidistantly between the side walls 7, 8.

Corresponding circular apertures 14', 15', 16' are provided on the rear wall 6 so that each of the first, second, and third apertures 14, 15, 16 on the front wall 5 are collinear with the respective first, second and third 14', 15', 16' on the rear wall 6.

The first and second apertures 14, 15; 14', 15' are arranged to be contiguous with the first pair of collinear circular apertures 17, 18 in the respective side walls 7, 8. A seat 24 is configured for mounting on the upper wall 9 of the hollow body 3. The seat 24 has a concave bearing surface 22 upon which a distal bearing surface 201, 20 Γ of the femoral component 200 can sit.

The seat 24 includes a U-shaped lug 23 extending perpendicular from the underside 25 of the seat 24 and opposite from the bearing surface 22. The lug 23 is dimensioned to be received in the rectangular aperture 21 provided in the upper wall 9 of the body 3. The lug 23 is provided with a cylindrical aperture 26 extending across the width of the lug 23 and which is located so as to be collinear with the third circular apertures 16, 16' in the front and rear faces 5, 6 respectively when the seat 24 is mounted upon the upper wall 9 and the lug 23 received in the rectangular aperture 21.

The seat 24 is secured to the body 3 by means of a dowel 39 inserted through the third circular apertures 16, 16' and the cylindrical aperture 26 provided in the lug 23.

The body 3 includes a jaw arrangement 42 which comprises a pair of first and second arms 27, 28 mounted on the body 3.

The first and second arms 27, 28 are identical and are configured to face each other on opposite sides of the body 3 adjacent the side walls 7, 8 as will be described in further detail below.

Each of the first and second arms 27, 28 have respective first and second transversely extending threaded shaft members 29, 30 at a proximal end, and respective first and second transversely extending gripping members in the form of a return flange 31, 32 at the opposite distal end.

In the embodiment described herein, the first and second shaft members 29, 30 and the return flanges 31, 32 are perpendicular to the first and second arms 27, 28. However, in alternative embodiments, the first and second arms 27, 28 could by inclined and subtend selected angles to the first and second shaft members 29, 30 and the return flanges 31, 32. The first and second threaded shaft members 29, 30 are fixed to the respective first and second arms 27, 28. In the present embodiment, the first and second threaded shaft members 29, 30 are fixed to the respective first and second arms 27, 28 by means of projections 55, 56 received in apertures 57, 58 in the first and second arms 27, 28.

Alternatively, they could be formed as unitary bodies with the first and second arms 27, 28.

In this way, as the first and second threaded shaft members 29, 30 move, the first and second arms 27, 28 translate with them in the same direction.

The return flanges 31, 32 are structured to engage with holding means provided on the femoral component 200 to thereby grip the femoral component 200 when the bearing surface 201 of the femoral component 200 are resting against the seat 24. In the case of the embodiment described herein, the flanges 31, 32 are shaped to engage with holding recesses 52, 53 provide on the sides of the femoral component 200.

The threaded shaft members 29, 30 have externally threaded portions 62, 63 at a distal end for cooperation with an actuating member in the form of an internally threaded

thumbwheel 40. Each threaded portion 62, 63 includes a thread 59, 60.

The first and second threaded shaft members 29, 30 serve to effect translational movement of the first and second arms 27, 28 relative to each other to adjust the separation between them in response to manipulation of the rotating thumbwheel 40.

The first and second arms 27, 28 also include a respective transversely extending first and second guide pin 33, 34 extending parallel to, and at a predetermined distance from, a respective threaded shaft member 29, 30.

A limiting slot 35, 36 is provided in each threaded shaft member 29, 30 that extends lengthways along a portion of the threaded shaft member 29, 30. A circumferential groove 37 is also provided on the first and second threaded shaft members 29, 30 towards the respective arm 27, 28. The first arm 27 is configured so that the respective first threaded shaft member 29 is received into the respective circular aperture 17 of the first pair of collinear circular apertures provided in one of the side walls 7, while the first guide pin 33 is received into the respective circular aperture 19 of the second pair of collinear circular apertures provided in the same side wall 7.

Similarly, the second arm 28 is configured so that the respective second threaded shaft member 30 is received into the respective circular aperture 18 of the first pair of collinear circular apertures provided in the other of the side walls 8, while the second guide pin 34 is received into the respective circular aperture 20 of the second pair of collinear circular apertures provided in the same side wall 8.

When the threaded shaft members 29, 30 and guide pins 33, 34 are received into the respective circular apertures 17, 18; 19, 20, the elongate limiting slots 35, 36 are in alignment with the respective first and second circular apertures 14, 14'; 15, 15' and are arranged to receive a dowel pin 37, 38 which serves to limit lateral movement of the arms 27, 28 when the dowel pin 37, 38 abuts the ends of the limiting slots 35, 36.

The rotating thumbwheel 40 is located within the cavity 4. The thumbwheel 40 has a cylindrical body with an internal bore 41 running longitudinally through it which receives the respective threaded portions 62, 63 of threaded shaft members 29, 30 at each end. The internal bore 41 has internal threaded portions 61, 6 Γ for engaging with the threaded shaft members 29, 30.

The thumbwheel 40 has a ribbed outer contour to assist with manual rotation.

The first and second shaft members 29, 30 are inserted through the respective circular apertures 17, 18, into the cavity 4 and the threaded portions 62, 63 of the shaft members 29, 30 are inserted into the threaded internal bore 41, one at each end. The threads 59, 60 provided on the threaded shaft members 29, 30 engage with the internal threaded portions 61, 6 of the bore 41. The thumbwheel 40 and the threaded shaft members 29, 30 are coUinear along a common longitudinal axis Y with the thumbwheel 40 being rotatable around this axis Y. The thread 59 provided on the first threaded shaft member 29 is in the opposite direction to the thread 60 of the second threaded shaft member 30 so that rotation of the thumbwheel 40 around the axis Y causes the threaded shaft members 29, 30 to move towards each other or apart from each other within the bore 41 depending upon the direction in which the thumbwheel 40 rotates. This is illustrated in Figure 6 by the double-headed arrows. As such, the threaded shaft members 29, 30 and the thumbwheel 40 act as a turnbuckle arrangement.

The threaded portions 61, 61 ', 62, 63 are indicated in Figures 6, 12 and 13 by the dashed lines. In this way, manipulation of the thumbwheel 40 causes translational movement of the threaded shaft members 29, 30 relative to each other and to the thumbwheel 40.

As a consequence of the first and second arms 27, 28 being fixed relative to the threaded shaft members 29, 30 the first and second arms 27, 28 move towards and away from each other as the threaded shaft members 27, 28 move within the bore 41 in response to rotation of the thumbwheel 40.

Thus, the first and second arms 27, 28 can be caused to either move apart or towards each other to thereby vary the separation between them. When the thumbwheel 40 rotates in a first direction, the first and second arms 27, 28 move together, and when the thumbwheel 40 rotates in a second direction, the first and second arms 27, 28 move apart.

The pitch of the thread, the diameter of the shaft members 29, 30 and the profile of the thread are chosen to facilitate self-locking of the first and second arms 27, 28.

As the threaded shaft members 29, 30 move towards and away from each other in response to the turning of the thumbwheel 40, there is relative translational movement of the limiting slots 35, 36 with respect to the dowels 37, 38 received therein. When the dowel 37, 38 abuts the end of the limiting slot 35, 36 further movement of the threaded shaft members 29, 30 is prohibited. In this way, the separation of the first and second arms 27, 28 cannot be overextended.

By providing this translational movement of the the first and second threaded shafts 29, 30, the first and second arms 27, 28 can be used to accommodate and grip a femoral component 200, using the return flanges 31, 32.

The handle 2 has an elongate body portion 46 suitable contoured for gripping with one hand. At one end, the handle includes a neck 13 for mounting the head 1 thereon.

At the end of the handle 2 towards the neck 13 a handle cavity 47 is formed.

The head retaining mechanism 45 is mounted on the handle 2 towards the neck 13 and includes a latch 49 pivotably mounted within the cavity 47 around a crossways-mounted pin 48. The lip 50 is provided at one end of the latch 49 for engaging with the groove 43 provided on the collar 11. A compression spring 51 connected between latch 49 and the handle 2 biases the latch 49 to the position in which the lip 50 engages the groove 43 thus retaining the head 1 in attachment to the handle 2.

To remove the head 1 from the handle 2, the latch 49 is depressed to compress the spring 51 and pivots around the pin 48, disengaging the lip 50 from the groove 43 thus allowing the head to be removed.

The cavity 47 also provides for better cleaning of the instrument.

The instrument 100 is made from metallic materials which are known to be used for surgical instruments. One such material is stainless steel.

To use the instrument 100, a user holds the handle 2 in one hand and manually operates the head retaining mechanism 45 to depress the latch 49 so that it pivots around the pin 48 and moves the lip 50 away from the neck 13. The user places the head 1 onto the handle 2 by placing the collar 11 over the neck 13. The user releases the latch 49 so that the spring 51 biases the lip 50 towards the collar 11 so that it engages the groove 43.

With the head 1 in place, the user manually rotates the thumbwheel 40 using the thumb to operate the jaw arrangement 42 and to move the first and second arms 27, 28 apart so that they can accommodate the width of the femoral component 200 to be gripped by the instrument 100.

The instrument 100 is then placed around the femoral component 200 such that the flanges 31, 32 are approximately level with holding recesses 52, 53 provided on the femoral component 200.

The user rotates the thumbwheel 40 using the thumb to translate the first and second arms 27, 28, towards each other until the flanges 31, 32 engage with the holding recesses 52, 53 in the femoral component 200. The first and second arms 27, 28 continue to be translated until the femoral component 200 is gripped securely between the first and second arms 27, 28.

The user is able to manipulate the femoral component 200 into place against the resected femur and to then use the instrument 100 to impact the femoral component 200 in place in the usual manner.

Variations are possible within the scope of the present invention. For example, the handle 2 can be of any suitable shape and structure with appropriate retention means to retain the head to the handle. The seat 24 can be shaped and dimensioned to accommodate various shapes of femoral component. The return flanges 31, 32 can be substituted by any suitable means for gripping the femoral component 200.

The thumbwheel 40 can be provided in a variety of shapes and dimensions. For example, the thumbwheel 40 can have external threaded portions to engage with internal threads on the shaft members. Alternatively, a cam arrangement with a cam surface on the actuating member and a cooperating cam a follower on the shaft members could be used.

Claims

1. An instrument for manipulating an implant component of an orthopaedic joint prosthesis, the instrument comprising:

a body;

a seat mounted on the body for contacting a bearing surface of the implant component during manipulation of the implant component;

2. An instrument as claimed in claim 1, wherein the first and second shaft members have a thread and the actuation member has a first threaded portion for cooperation with the thread on the first shaft member and a second threaded portion for cooperation with the thread on the second shaft member, the first and second threaded portions of the actuation member being collinear.

3. An instrument as claimed in claim 2, wherein the threads on the first and second shaft members are external and the actuation member has an internal bore, the first and second threaded portions being received within the internal bore.

4. An instrument as claimed in any preceding claim, wherein at least one of the first and second shaft members has a limiting slot formed in it, and the body includes at least one dowel which is received in the slot in one of the shaft members to limit translation of the first and second shaft members.

5. An instrument as claimed in any preceding claim, wherein the body has side walls and includes a cavity for housing the actuating member therein, the body further including a first pair of collinear apertures provided on the side walls through which the first and second shaft members extend to cooperate with the actuating mechanism.

6. An instrument as claimed in any preceding claim, wherein each of the first and second arms has a guide pin extending from it and the body has a second pair of collinear apertures provided on the side walls through which a respective guide pin extends.

7. An instrument as claimed in any preceding claim, which includes a handle releasably attached to the body.

8. An instrument as claimed in claim 7, wherein the handle includes a neck portion and the body has a collar extending outwardly from the body with a bore running through the collar and arranged to receive the neck portion therein.

9. An instrument as claimed in claim 8, wherein the collar includes a groove and the handle includes a pivotable latch with a lip for engaging with the collar to secure the head to the handle.

10. An instrument as claimed in claim 9, wherein the pivotable latch is biased towards a position in which the lip is engaged in the groove.

11. An instrument as claimed in any preceding claim wherein the actuating member has a ribbed external contour.