GB2594466A

GB2594466A - Trial neck and method

Info

Publication number: GB2594466A
Application number: GB2006155.2A
Authority: GB
Inventors: Anderson James
Original assignee: DePuy Ireland ULC
Current assignee: DePuy Ireland ULC
Priority date: 2020-04-27
Filing date: 2020-04-27
Publication date: 2021-11-03
Also published as: GB202006155D0

Abstract

A trial femoral neck 100 comprising a proximal part 2 including an elongate neck 10 configured to be connected to a trial head, and a distal part 4 slidably coupled to the proximal part to allow movement of the proximal part relative to the distal part in a medial/lateral direction 36, 38. The trial neck further includes a bore 15A,B extending through the distal part and at least partially through the proximal part for receiving a proximal end 14 of a reamer 16. The trial neck further includes a locking mechanism configured to lock the proximal end of the reamer within the bore by urging the proximal part in the medial or the lateral direction relative to the distal part to urge an inner surface of the bore located in the proximal part against the proximal end of the reamer. A method of attaching a reamer to the neck is also taught.

Description

TRIAL NECK AND METHOD

BACKGROUND

The present specification relates to a trial neck and to a method of attaching a trial neck to a reamer.

Flip replacement is a surgical procedure in which the hip joint is replaced by a prosthetic implant. Total replacement of the hip joint involves installing an acetabular cup implant in the acetabulum of a patient and installing a prosthetic in the femur of the patient.

The prosthetic typically includes a stem, which is received in the medullary canal of the femur, and a head having a bearing surface which is received in the acetabulum or acetabular cup implant. The prosthetic typically also includes a neck which extends between a proximal end of the stem and the head Successful hip replacement surgery requires correct positioning and alignment of the acetabular cup implant as well as the prosthetic itself Misalignment and/or the selection of an inappropriately sized acetabular cup implant and/or the prosthetic may result is restricted movement of the prosthetic and/or accelerated wear and tear of the bearing surfaces of the acetabular cup implant and the bearing surface of the head. Various factors are involved in achieving this correct positioning and alignment At least some of these factor relate to the neck of the prosthetic. These factors may include, for instance, the length of the neck, and an angular orientation (offset) of the neck relative to the stem.

Hip replacement surgery usually involves trialling the various components of the acetabular cup implant and the prosthetic. As part of this, various sizes of broach/reamer may be used to prepare the medullary canal of the femur. Once the broach/reamer is inserted in the femur, a trial neck and trial head may also be attached to the broach/reamer, in order to evaluate whether a prosthetic having a neck and head of that type (e.g in terms of the size and offset of the neck) would appropriate for the patient.

After the surgeon is satisfied that the chosen combination of broach/reamer, trial neck and trial head are correctly positioned and aligned, they may be removed and replaced with the implant itself

SUMNIARY

Aspects of the present disclosure are set out in the accompanying independent and dependent claims. Combinations of features from the dependent claims may be combined with features of the independent claims as appropriate and not merely as explicitly set out in the claims.

According to an aspect of the present disclosure, there is provided a trial neck for hip surgery, the trial neck comprising: a proximal part including an elongate neck, wherein a proximal end of the elongate neck is configured to be connected to a trial head; a distal part slidably coupled to the proximal part to allow movement of the proximal part relative to the distal part in a medial/lateral direction; a bore extending through the distal part and at least partially through the proximal part for receiving a proximal end of a reamer; and a locking mechanism configured to lock the proximal end of the reamer within the bore by urging the proximal part in the medial or the lateral direction relative to the distal part to urge an inner surface of the bore located in the proximal part against the proximal end of the reamer.

According to another aspect of the present disclosure, there is provided a method of attaching a trial neck to a reamer, the trial neck comprising: a proximal part including an elongate neck, wherein a proximal end of the elongate neck is configured to be connected to a trial head; a distal part slidably coupled to the proximal part to allow movement of the proximal part relative to the distal part in a medial/lateral direction; a bore extending through the distal part and at least partially through the proximal part for receiving a proximal end of a reamer; and a locking mechanism configured to lock the proximal end of the reamer within the bore by urging the proximal part in the medial or the lateral direction relative to the distal part to urge an inner surface of the bore located in the proximal part against the proximal end of the reamer, the method comprising: inserting the proximal end of the reamer into the bore; and operating the locking mechanism to urge the proximal part in the medial or the lateral direction relative to the distal part to urge an inner surface of the bore located in the proximal part against the proximal end of the reamer.

According to a further aspect of the present disclosure, there is provided a surgical kit comprising: a reamer; and a trial neck comprising: a proximal part including an elongate neck, wherein a proximal end of the elongate neck is configured to be connected to a trial head; a distal part slidably coupled to the proximal part to allow movement of the proximal part relative to the distal part in a medial/lateral direction; a bore extending through the distal part and at least partially through the proximal part for receiving a proximal end of the reamer; and a locking mechanism configured to lock the proximal end of the reamer within the bore by urging the proximal part in said medial or said lateral direction relative to the distal part to urge an inner surface of the bore located in the proximal part against the proximal end of the reamer.

The trial neck may allow for convenient connection to a reamer. The locking mechanism may provide a secure connection to the reamer in a manner that is easily lockable and unlockable to allow the angle of the elongate neck of the trial neck around a longitudinal axis of the reamer to be adjusted before the trial neck is (again) locked down.

The locking mechanism may include a further bore extending through the proximal part and at least partially through the distal part. The locking mechanism may also include a threaded surface located in a part of the further bore extending through the distal part. The locking mechanism may further include an engagement surface located on the proximal part. The locking mechanism may also include a locking member comprising an elongate shaft.

The elongate shaft may include a longitudinal axis extending between a proximal end and a distal end of the elongate shaft. The elongate shaft may also include a threaded surface for engaging with the threaded surface located in the part of the further bore extending through the distal part. The elongate shaft may further include a tapered flange having a surface extending at an angle relative to the longitudinal axis of the elongate shaft to engage with the engagement surface as the locking member is rotated within the further bore to urge the proximal part in the medial or the lateral direction relative to the distal part The tapered flange may be located at the proximal end of the elongate shaft.

The proximal end of the elongate shaft may include a connection feature for connecting to a tool for rotating the locking member within the further bore.

A diameter of the further bore within the proximal part may be larger than a diameter of the further bore within the distal part. This can provide clearance between the locking member and the internal surface of the further bore within the proximal part to ensure a degree of movement of the proximal part relative to the distal part to engage the locking mechanism.

A longitudinal axis of the further bore may extend at a non-zero angle relative to a longitudinal axis of the bore that receives the proximal end of the reamer.

The distal part may be slidably coupled to the proximal part by a protrusion extending from either the proximal part or the distal part, and a slot located in either the distal part or the proximal part. The slot may be shaped to conform with the shape of the protrusion. The protrusion may be slideably received within the slot.

The protrusion and the slot may be substantially T-shaped when viewed along the medial direction. This shape may prevent disengagement of the proximal part from the distal 25 part.

The protrusion and the slot may be elongate and may extend along a direction substantially parallel to a medial-lateral axis of the trial neck.

The bore for receiving the proximal end of the reamer may be substantially cylindrical. This can allow the trial neck to be rotated freely on the reamer (while the locking mechanism id disengaged), so that the angle of the elongate neck around the longitudinal axis of the reamer can be adjusted.

S

The bore for receiving the proximal end of the reamer may extend completely through the proximal part The further bore may extend completely through the distal part This can simplify the manufacture of the trial neck.

The distal part may have a profiled surface located at a distal end of the bore for receiving the proximal end of the reamer, to engage with a corresponding profiled surface of the reamer. This can improve the robustness of the connection of the trial neck of the reamer by opposition rotation of the trial neck around the longitudinal axis of the reamer while the trial neck is locked down. The profiled surface of the distal part may include a saw-tooth profile or a plurality of axial splines.

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 S elements and in which: Figure 1 shows a trial neck according to an embodiment of this disclosure; Figure 2 shows an anterior view of the trial neck of Figure I; Figure 3A shows a view of the trial neck of Figure 1 along the medial direction; Figure 3B shows a detail of the vial neck in Figure 3A; Figure 4 shows a superior view of the trial neck of Figure I; Figure 5 shows another anterior view of the trial neck of Figure I; Figure 6 shows a further view of the trial neck of Figure 1; and Figure 7 shows a cross section of the trial neck of Figure 1

DETAILED DESCRIPTION

Embodiments of this disclosure are described in the following with reference to the accompanying drawings.

Figures 1 to show various views of a trial neck 100 according to an embodiment of this disclosure. The trial neck 100 may be connected to a proximal end 14 of a reamer 16. As will be described in more detail below, the trial neck 100 has a locking mechanism, which can provide a secure connection between the trial neck 100 and the reamer 16 in a manner that is easily lockable and unlockable to allow adjustment of the orientation of the trial neck around a longitudinal axis 13 of the reamer 16.

The trial neck 100 has a proximal part 2. The proximal part 2 has an elongate neck 10. The elongate neck 10 has a proximal end 8, which is configured to be connected to a trial head (not shown in the figures). The connection features used to connect the proximal end 8 of the trial neck 100 to the trial head in this example include an annular groove (e.g. see Figure 1), although it is envisaged that any suitable connection features may be used. With the trial neck 100 connected to the reamer 16, the elongate neck 10 extends along a neck axis that is oriented generally medially, at a non-zero angle to the longitudinal axis 13 of the reamer 16.

The trial neck also has a distal part 4. The distal part 4 is slideably coupled to the proximal part 2. The interface/connection between the proximal part 2 and the distal part 4 may be substantially linear (to allow the sliding movement of the distal part 4 relative to the proximal part 2) and is generally indicated in the drawings using reference numeral 6. In this embodiment, with the trial neck 100 connected to the reamer 16, the interface/connection between the proximal part 2 and the distal part 4 is oriented substantially orthogonally to the longitudinal axis 13 of the reamer 16 (e.g. see Figure 2).

The slideably coupling between the proximal part 2 and the distal part 4 allows movement of the proximal part 2 relative to the distal part 4 in a medial direction 38 and/or a lateral direction 36. A stop 30, 32 may be provided at either end of the coupling between the proximal part 2 and the distal part 4 to prevent the proximal part 2 and the distal part 4 from sliding beyond a certain distance. This can prevent the proximal part 2 and the distal part 4 from becoming inadvertently detached. In this embodiment, the stops 30, 32 are provided on the distal part 4, but is envisaged that they may be provided on the proximal part The stops 30, 32 in this embodiment abut the medial/lateral ends of the proximal part 2 when the proximal part 2 has reached its maximum distance of travel relative to the distal part 4.

The trial neck 100 further includes a bore 15. The bore 15 has two parts.

A first part 15A of the bore 15 extends at least partially though the proximal part 2. Note that while, in the present embodiment, the bore part 15A extends completely through the proximal part 2, this is not essential. In some embodiments, for example, the bore part 15A may extend into the proximal part 2 in a proximal direction, from the interface/connection 6 between the proximal part 2 and the distal part 4, and only partly through the proximal part 2. In embodiments in which the bore 15 extends completely through the proximal part 2, the manufacture and cleaning of the trial neck 100 may be simplified. This arrangement would also allow the proximal end 14 of the reamer 16 to be viewed at the proximal surface of the proximal part 2, as shown in e.g. Figure 4. In some embodiments, the proximal end 14 of the reamer 16 may be provided with a mating feature 17 for attaching the reamer 16 to a reamer driver. In embodiments in which the bore 15 extends completely through both the distal part 4 and the proximal part 2, the reamer driver may be attached to the reamer 16 using the mating feature 17 even when the trial neck 100 is attached to the reamer 16.

A second part 15B of the bore 15 extends (completely) through the distal part 4.

The bore 15 is shaped and sized so as to allow a proximal end 14 of the reamer 16 to be received within the bore 15, for connecting the trial neck 100 to the reamer 16. Note that when the trial neck is attached to the proximal end 14 of the reamer 16, the proximal end 14 extends through the second part 15B of the bore 15 and at least partially into the first part 15A of the bore 15. The bore 15 may extend along a direction that is substantially parallel to the longitudinal axis 13 of the reamer 16, when the trial neck 100 is connected to the reamer 16.

The trial neck also includes a locking mechanism. The locking mechanism is configured to lock the proximal end 14 of the reamer 16 within the bore 15 by urging the proximal part 2 in either medial direction 38 or the lateral direction 36 relative to the distal part 4, to urge an inner surface of the bore 15 located in the proximal part 2 (i.e. an inner surface of the first bore part 15A) against the proximal end 14 of the reamer 16. In the present embodiment, the locking mechanism urges the proximal part 2 in the lateral direction 36, although it will be appreciated that this is not essential and that in other embodiments the proximal part may be urged in the medial direction 38 to perform the locking function.

In this embodiment, the locking mechanism includes a further bore 12. The further bore 12 extends through the proximal part 2 and at least partially through the distal part 4.

Note that the further bore 12 extends across the interface/connection 6 between the proximal part 2 and the distal part 4. The bore 12 shown in the figures extends completely through the distal part 4, which may simplify the manufacture of the trial neck 100 and also aid cleaning. The further bore 12 may have a proximal opening at a superior surface of the proximal part. In this embodiment, the further bore 12 has a distal opening at the inner surface of the second part 15B of the bore 15 in the distal part 4. With the trial neck 100 attached to the reamer 16, the further bore 12 in this embodiment extends in a proximal/medial to distal/lateral direction, at a non-zero angle with respect to the longitudinal axis 13 of the reamer 16.

The further bore 12 may include a threaded inner surface 11 located in at least part of the further bore 12 extending through the distal part 4 (see Figure 7).

The locking mechanism in this embodiment further includes an engagement surface 23, which is located on the proximal part 2. As may be seen in, for example, Figure 7, the engagement surface 23 in this embodiment is located at the proximal opening of the further bore 12, although this is not essential. The engagement surface 23 in this embodiment is oriented such that it has a surface normal which points generally towards the medial direction 38. This orientation of the engagement surface allows the engagement surface 23 to be used to urge the proximal part in 2 the lateral direction 36, as will be described below. In embodiments in which the locking mechanism urges the proximal part 2 in the medial direction 38 to perform the locking function, it will be appreciated that the surface normal of the engagement surface 23 may point generally towards the lateral direction 36 and the orientation of the further bore 12 may be altered with respect to the embodiment shown in the figures such that it extends in a proximal/lateral to distal/medial direction, at a non-zero angle with respect to the longitudinal axis 13 of the reamer 16.

The locking mechanism in this embodiment also includes a locking member 20. The locking member 20 comprises an elongate shaft. The elongate shaft has a longitudinal axis which extends between a proximal end and a distal end of the elongate shaft. The elongate shaft also has a threaded surface 25. The locking member 20 may be received within the further bore 12 so that the threaded surface 25 threadingly engages with the threaded inner surface 11. The locking member 20 may thus be rotated within the further bore 12 so as to adjust the depth of the locking member 20 within the further bore 12. A proximal end of the locking member 20 may be provided with features to assist in rotating the locking member 20 within the further bore 12. For instance, the proximal end of the locking member may be provided with gripping parts to allow the surgeon manually to rotate the locking member 20 and/or (as is in the embodiment shown in the drawings) may be provided with connection features such as a slot or faceted opening for connecting the a tool (e.g. a screw driver) to the locking member 20 to assist in rotating the locking member 20.

The locking member 20 further includes a tapered flange. In this embodiment, the tapered flange is located at the proximal end of the locking member 20, although this is not essential. The tapered flange has a surface 21 which extends at an angle relative to the longitudinal axis of the elongate shaft to engage with the engagement surface 23 as the locking member 20 is rotated within the further bore 12. In particular, as the depth of the locking member 20 within the further bore 12 increases (on rotation of the locking member 20 within the further bore 12 as noted above) the surface 21 of the tapered flange urges against the engagement surface 23. This urges the proximal part 2 in the lateral direction 36 relative to the distal part 4. When the proximal end 14 of the reamer 16 is received within the bore 15, the operation of the locking mechanism as described above causes an inner surface (in this embodiment a laterally facing part of the inner surface) of the bore part 15A located in the proximal part 2 to urge against the proximal end 14 of the reamer 16, thereby to lock the proximal end 14 within the bore 15. Note that the locking mechanism may also generally involve an opposite inner surface (in this embodiment a medially facing part of the inner surface) of the bore part 15B urging against the proximal end 14 of the reamer 16. In this way, the inner surfaces of the bore parts 15A, 15B may exert a force on the proximal end 14 of the reamer 16 in opposite, respective directions, thereby generating a shear force to lock the proximal end 14 within the bore 15.

Accordingly, to attach the trial neck 100 to the reamer 16, the proximal end 14 of the reamer 16 may first be inserted into the bore 15. The surgeon may then rotate the trial neck 100 around the longitudinal axis 13 of the reamer 16 to reach a desired orientation of the elongate neck 10 around a longitudinal axis 13. To assist in the rotation, the bore 15 may be substantially cylindrical, as may be the proximal end 14 of the reamer 16. Once the desired orientation is reached, the locking mechanism may be operated, to secure the trial neck 100 to the reamer 16, also preventing any further rotation of the trial neck 100 around the longitudinal axis 13 of the reamer 16. As noted above, in the embodiment shown in the drawings, this may be achieved by screwing the locking member 20 into the further bore 12 so that the surface 21 urges against the engagement surface 23.

During the surgical procedure, it may be desired to alter the orientation of the elongate neck 10 around the longitudinal axis 13 of the reamer 16. To do so, the surgeon may first unlock the locking mechanism (e.g. by unscrewing the locking member to disengage the surface 21 from the engagement surface 23), then adjust the orientation of the trial neck 100, and then re-lock the locking mechanism (e.g. by screwing the locking member 20 back into the further bore 12).

In some embodiments, in order to allow free medial/lateral movement of the proximal part 2 relative to the distal part 4 as the surface 21 urges against the engagement surface 23, diameter of the part of the further bore 12 located within the proximal part 2 may be larger than a diameter of the part of the further bore 12 located within the distal part 4. This can provide some clearance between the locking member 20 and the internal surface of the part of the further bore 12 located within the proximal part 2 to ensure a degree of movement of the proximal part 2 relative to the distal part 4 to engage the locking mechanism. Note that the diameter of the locking member 20 may be smaller than the diameter of the part of the further bore 12 located within the proximal part in such embodiments.

In some embodiments, the slidable coupling between the proximal part 2 and the distal part 4 may include a protrusion extending proximally from the proximal surface of the distal part 4. The protrusion may be elongate along the medial-lateral axis. The protrusion may be received within a correspondingly shaped slot located in the distal surface of the proximal part 2. An upper edge 34 of the slot can be seen in Figure 3B. The slot may also be elongate along the medial-lateral axis. This arrangement can allow the protrusion to slide medially/laterally within the slot (and vice versa), thereby providing a slideable coupling between the proximal part 2 and the distal part 4 at the interface 6. It is envisaged that the arrangement described above may be reversed in some embodiments, so that the protrusion extends distally from a distally facing surface of the proximal part 2 and the slot is located in the distal part 4. In some embodiments, the protrusion and the slot may be substantially T-shaped when viewed along the medial direction 38. This configuration may prevent the proximal part and the distal part from becoming inadvertently decoupled by preventing movement of the proximal part 2 away from the distal part 4 in the superior direction.

In the embodiment shown in the figures, the protrusion and the slot extend along a direction that is substantially parallel to a medial-lateral axis of the trial neck 100. However, this is not essential, and the interface 6 including the protrusion and the slot may extend at a non-zero (typically shallow) angle with respect to the medial-lateral axis of the trial neck 100.

The distal end 22 of the distal part 4 may, in some embodiments include a profiled surface 22A (e.g. see Figure 5). The profiled surface 22A may in particular be located at a distal end of the bore 15 and may be configured to engage with a corresponding profiled surface 22B of the reamer 16. The profiled surface 22B may be located at a most distal part of the proximal end 14 of the reamer 16, e.g. on a lip of flange that faces proximally. The profiled surfaces 22A, 22B may be shaped to conform with each locate. In this embodiment, the profiled surfaces 22A, 22B each have a saw-tooth profile, however it is also envisaged that the profiled surfaces 22A, 22B may include axial splines on the proximal end 14 of the reamer 16 for mating with correspondingly shaped axial splines located on the trial neck 100 (e.g. inside the bore 15 (e.g. inside the bore part 15B)). The engagement of the profiled surfaces 22A, 22B, when the proximal end 14 of the reamer 16 is fully received within the bore 15 may provide an additional locking force between the distal part 4 of the trial neck 100 and the reamer 16. In particular, the engagement of the profiled surfaces 22A, 22B may resist rotation of the trial neck 100 around the longitudinal axis 13 of the reamer 16 when the locking mechanism of the trial neck 100 is locked down. Furthermore, the toothed/splined configuration of the profiled surfaces 22a, 22B may allow the rotation angle of the trial neck around the longitudinal axis 13 of the reamer 16 to be indexed in a plurality of discrete positions.

A method of attaching the trial neck 100 may thus include inserting the proximal end 14 of the reamer 16 into the bore 15 of the trial neck 100 so that the proximal end extends through the bore part 15B and at least partially into the bore part 15A. The method may also include operating the locking mechanism to urge the proximal part 2 in the medial direction 38 (in the embodiment described above) or the lateral direction 36 (in other embodiments) relative to the distal part 4 to urge an inner surface of the bore part 15A in the proximal part 2 against the proximal end 14 of the reamer 16. As noted above, operating the locking mechanism may involve rotating the locking member 20 within the further bore 12 so as to urge the surface 21 of the tapered flange against the engagement surface 23 The trial neck 100 may be provided as part of a surgical kit. The kit may include the trial neck 100 and the reamer 16. The kit may include further components for use in the hip replacement procedure.

The trial neck 100 and reamer 16 described herein may be made from any suitable material, for instance a surgical wade stainless steel.

In several of the Figures described above (Figures 5, 6 and 7), the locking member 20 is not shown as being inserted into the further bore 12, and the proximal end of the reamer 16 is not shown as being received within the bore 15. In these drawings, the proximal part 2 is shown displaced in the medial direction 38 relative to the distal part 4 (i.e. displaced in the opposite direction to the direction in which the proximal part 2 moves to engage the locking mechanism as described above in relation to this embodiment), so as clearly to illustrate the slideable coupling between the proximal part 2 and the distal part 4.

Accordingly, there has been described a trial neck and a method of attaching a trial neck to a reamer. The trial neck includes a proximal part including an elongate neck. A proximal end of the elongate neck is configured to be connected to a trial head. The trial neck also includes a distal part slidably coupled to the proximal part to allow movement of the proximal part relative to the distal part in a medial/lateral direction. The trial neck further includes a bore extending through the distal part and at least partially through the proximal part for receiving a proximal end of a reamer. The trial neck further includes a locking mechanism configured to lock the proximal end of the reamer within the bore by urging the proximal part in the medial or the lateral direction relative to the distal part to urge an inner surface of the bore located in the proximal part against the proximal end of the reamer.

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

Claims

CLAIMSA trial neck for hip surgery, the trial neck comprising: a proximal part including an elongate neck, wherein a proximal end of the elongate neck is configured to be connected to a trial head; a distal part slidably coupled to the proximal part to allow movement of the proximal part relative to the distal part in a medial/lateral direction; a bore extending through the distal part and at least partially through the proximal part for receiving a proximal end of a reamer; and a locking mechanism configured to lock the proximal end of the reamer within the bore by urging the proximal part in said medial or said lateral direction relative to the distal part to urge an inner surface of the bore located in the proximal part against the proximal end of the reamer.
2. The trial neck of claim 1, wherein the locking mechanism comprises a further bore extending through the proximal part and at least partially through the distal part; a threaded surface located in a part of the further bore extending through the distal part; an engagement surface located on the proximal part; and a locking member comprising an elongate shaft having: a longitudinal axis extending between a proximal end and a distal end of the elongate shaft; a threaded surface for engaging with the threaded surface located in the part of the further bore extending through the distal part; and a tapered flange having a surface extending at an angle relative to the longitudinal axis of the elongate shaft to engage with the engagement surface as the locking member is rotated within the further bore to urge the proximal part in said medial or said lateral direction relative to the distal part.
The trial neck of claim 2, wherein the tapered flange is located at the proximal end of the elongate shaft.
The trial neck of claim 2 or claim 3, wherein the proximal end of the elongate shaft includes a connection feature for connecting to a tool for rotating the locking member within the further bore.
The trial neck of any of claims 2 to 4, wherein a diameter of the further bore within the proximal part is larger than a diameter of the diameter of the further bore within the distal part.
6. The trial neck of any of claims 2 to 5, wherein a longitudinal axis of the further bore extends at a non-zero angle relative to a longitudinal axis of the bore that receives the proximal end of the reamer.
7. The trial neck of any preceding claim, wherein the distal part is sl dably coupled to the proximal part by: a protrusion extending from either the proximal part or the distal part; and a slot located in either the distal part or the proximal part, wherein the slot is shaped to conform with the shape of the protrusion, and wherein the protrusion is slideably received within the slot.
8. The trial neck of claim 7, wherein the protrusion and the slot are substantially T-shaped when viewed along the medial direction.
The trial neck of claim 7 or claim 8, wherein the protrusion and the slot are elongate and extend along a direction substantially parallel to a medial-lateral axis of the trial neck.
10. The trial neck of any preceding claim, wherein the bore for receiving the proximal end of the reamer is substantially cylindrical.
11. The trial neck of any preceding claim, wherein: the bore for receiving the proximal end of the reamer extends completely through the proximal part; and/or wherein the further bore extends completely through the distal part.
12. The trial neck of any preceding claim, wherein the distal part has a profiled surface located at a distal end of the bore for receiving the proximal end of the reamer, to engage with a corresponding profiled surface of the reamer.
13. The trial neck of claim 12, wherein the profiled surface of the distal part comprises a saw-tooth profile or a plurality of axial splines.
14. A surgical kit comprising: a trial neck according to any preceding claim; and a reamer.
15. A method of attaching a trial neck to a reamer, the trial neck comprising: a proximal part including an elongate neck, wherein a proximal end of the elongate neck is configured to be connected to a trial head; a distal part slidably coupled to the proximal part to allow movement of the proximal part relative to the distal part in a medial/lateral direction; a bore extending through the distal part and at least partially through the proximal part for receiving a proximal end of a reamer; and a locking mechanism configured to lock the proximal end of the reamer within the bore by urging the proximal part in said medial or said lateral direction relative to the distal part to urge an inner surface of the bore located in the proximal part against the proximal end of the reamer, the method comprising: inserting the proximal end of the reamer into the bore; and operating the locking mechanism to urge the proximal part in said medial or said lateral direction relative to the distal part to urge an inner surface of the bore located in the proximal part against the proximal end of the reamer.