GB2516674A

GB2516674A - Orthopaedic Apparatus

Info

Publication number: GB2516674A
Application number: GB1313526.4A
Authority: GB
Inventors: Ramesh Chandra
Original assignee: Individual
Current assignee: Individual
Priority date: 2013-07-29
Filing date: 2013-07-29
Publication date: 2015-02-04
Also published as: GB201313526D0

Abstract

An orthopaedic apparatus 1 for use in assessing alignment of bone cuts during an orthopaedic surgical procedure is provided. The apparatus 1 comprises a first paddle 2 to contact a surface of a first bone cut, a second paddle 3 displaceable relative to the first paddle to contact a surface of a second bone cut, and an angle measurement device 30 for determining the angle between the surfaces of the first and second paddles. The paddles may be pivotally connected by an extension member (see figure 3) and a spring mechanism 12 may bias the paddles apart. A gauge 31 may be provided on one paddle and a needle 32 may be provided on the other paddle. There may be a visual indication 75, 75 of the separation between the paddles. There may be apertures in the paddles which allow for connection of separation instrument (see figure 4) or an alignment instrument. A method of determining the alignment of bone cuts using the apparatus is also provided.

Description

ORTHOPAEDIC APPARATUS

Background to the invention

The present invention relates to apparatus for use in the performance of orthopaedic procedures, such as knee replacement surgery.

Summary of the Invention

A number of different methods and apparatus have been developed in order to enable a surgeon to resect bones, such as for example the femur and tibia, in order to attach a prosthesis. During a total or partial knee replacement, an incision is made in the leg of a patient to obtain access to the joint. The incision is sized to enable various instrumentation, such as a fenioral alignment guide, anterior resection guide, distal resection guide, femoral cutting guide, and femoral anterior, posterior and chamfer resection guide to be positioned relative to a distal end portion of the femur. In addition, the incision must enable a tibial resection guide to O be positioned relative to the proximal end portion of the tibia. a,

In order to restore the normal function of a joint, such as for example a knee joint, it is critical that the implant's location and orientation be consistent with the state of the ligaments, tendons and other soft tissue remaining in the knee joint after completion of the surgery. The orientation of the implant is largely dependent on the orientation of the resected bone surfaces. In order to align the implant correctly, the surfaces of the resected bone within the joint are ideally arranged to extend parallel to each other Conventional systems for determining the orientation of surfaces of bone cuts typically require the use of spacer blocks or computer navigation in order to assess the distance between bone surfaces and to ensure the surfaces are parallel to each other. Computer navigation systems are however expensive, time consuming and require specialist computer equipment. Spacer blocks may indicate lack of parallelism, but they do not give the actual angular variation. As a result, in a number of cases the procedure is carried out without any measurement of the angle between the surfaces of the bone cuts.

The present invention seeks to address the problems of the prior art.

According to a first aspect of the present invention, there is provided an orthopaedic apparatus for use in assessing bone cuts during an orthopaedic surgical procedure on a patient, the apparatus comprising: a. a first paddle providing a first surface configured to contact a surface ofafiist bone cut and b. a second paddle in communication with and displaceable relative to the a first paddle, in which the second paddle provides a first surface configured to ___ contact a surface of a second bone cut; in which the apparatus thrther comprises an angle measurement device for o detemiining the angle between the first surfaces of the first and second paddles. 0)

According to a further aspect, the present invention provides an orthopaedic system for use in assessing bone cuts during an orthopaedic surgical procedure on a patient, comprising apparatus as described herein; and a separation instrument arranged to engage the apparatus, in which the separation instrument is configured to reduce the separation between the first and second paddles of the apparatus prior to insertion between the bone cuts.

The angle measurement device of the present invention thereibre provides an immediate visual indication to the surgeon of the relative angles of the first and second paddles during the procedure without requiring additional expensive apparatus. The surgeon can therefore take the necessary steps in order to correct the orientation and/or alignment of the bone cut surfaces. Additionally, the device will allow the surgeon to choose the correct angle for the 4-in-i femoral cutting block, which can vary commonly between 0 and 7 degrees. Some instances where the angle lies beyond this range can also be detected through the use ofthis device.

The apparatus and system of the present invention may be used in surgery of any dcsircd typc. Although thc prcscnt invcntion is discusscd hcrcin in rclation to kncc replacement surgery, it is to be understood that the apparatus and system disclosed hcrcin may bc used in connection with any surgery carried out on any bone or joint which requires two surfaces provided by adjacent bones to be aligned at a predetermined angle, such as for example to extend parallel, relative to one another. Preferably, the apparatus and system are used to accurately determine the orientation of two surfaces provided by adjacent bones which are required to extend parallel to one another. The apparatus and system of the present invention can be used during replacement surgery of for example vertebral joints, ankle joint or shoulder joints. When used for the knee, the first bone cut is preferably a femur cut. The second bone cut is preferably tibia cut.

Each paddle may be formed as a single unit. Alternatively, each paddle may comprise a plurality, for example two, paddle portion in communication with each other. Each of the paddles may have any suitable shape for engaging the surface of the bone cut. For example, each of the paddles may be contoured to provide a first surface which corresponds substantially to the cross-sectional shape of the resected bone.

The angle measurement device may comprise any suitable arrangement for indicating the angle between the first surface of the first paddle and the first surface of the second paddle. For example, one of the first and second paddle(s) may provide a gauge. The other paddle(s) may provide an indicator feature, such as for example a needle, aligned \vith and niovcablc relative to the gauge to indicate the angle between the first surfaces of the paddles. The gauge is preferably provided by the paddle arranged to contact the tibia. The indicator feature is preferably provided by the paddle arranged to contact the femur.

The angle measurement device may be provided on any suitable surface of the paddle. For example, the angle measurement device may be provided on at least one of the anterior or posterior surfaces of the paddle, or a combination thereof.

Preferably, the angle measurement device is provided on the anterior surface of the paddle.

Prior to insertion, the first suifaces of the first and second paddle(s) preferably extend substantially parallel to each other. The apparatus may further comprise a calibration device for calibrating the indicator feature relative to the gauge.

The apparatus may comprise at least one, for example a plurality of indicator marks for indicating the separation of the first surfaces of the first and second paddles.

C For example, each paddle may comprise two spaced apart indicator marks. The 0) indicator marks may be provided on the first surface of each paddle. A first 04 indicator mark may be located towards the medial side of the paddle. A second indicator mark may be located towards the lateral side of the paddle. This arrangement therefore enables accurate measurements of the separation of the paddles, for example the first surfaces of the paddles, to be carried out in relation to the medial side and lateral side of the paddles. The indicator marks may be equally spaced apart from the central region of each paddle. The indicator marks provided by the first paddle are preferably aligned with the indicator marks of the second paddle. The aligned indicator marks of the paddles may be used us fixed points at or adjacent the medial and lateral sides of the paddles to indicate the separation of the paddles, for example to indicate the separation of the first surfaces of the paddles. The indicator marks may be any suitable feature for providing a point of reference, such as for example visual markings, notches, slits, projections, or any combination thereof The apparatus may further comprise at least one extension member connected at a first end to a first paddle and connected at a second end to a second paddle. For example, the first end of the extension member(s) may be connected to a first end of a first paddle and the second end of the extension member (s) may be connected S to thc opposed cnd of a sccond paddle. The cxtcnsion mcmbcr(s) may for cxample be arranged to extend from a medial side towards the lateral side of the apparatus.

The at least one extension member may be pivotally connected to the paddles at least one of the first and second ends. The extension member(s) is preferably arranged to restrict the separation of the paddles, such that the paddles are not separated by more than a maximum predetermined limit. The extension member(s) is preferably composed of resilient material.

The apparatus may comprise a biasing mechanism, for example at least one spring mechanism, configured to bias the first paddle away from the second paddle. The biasing mechanism preferably extends between adjacent first and paddle(s).

The apparatus may further comprise a separation measurement device configured to determine the separation between the first surface of the first paddle and the first surface of the second paddle. The displacement measurement device provides a visual indication of the separation of the first surfaces of the first and second paddle(s) within the site of the resection.

At least one of the first and second paddles may provide at least one alignment aperture for engaging a portion of an alignment member which is in use arranged to extend along or adjacent at least one of the first or second bones. The aperture(s) maybe provided by any suitable surface of the paddle(s) in order to enable at least a portion of the alignment member to be arranged in use to extend along or adjacent at least one of the first or second bones. Preferably, the alignment member is arranged in use to extend along or adjacent the length of at least one of the first or second bones. The aperture(s) are preferably provided by the anterior surface of one or more of the first or second paddles. At least one of the paddle, for example each paddle, preferably provides two spaced apart apertures for engaging the alignment member. The two spaced apart apertures provided by a first paddle may be aligned with two spaced apart apertures provided by a second paddle.

The alignment member preferably comprises an elongate portion. The alignment member preferably comprises at least one engagement feature at a first end thereof for engaging the at least one alignment aperture. Once engaged within the aperture(s), the elongate portion is arranged to extend along or adjacent at least one of the first or secondbones, forexample along the length of at least one of the first or second bones. The alignment member therefore provides an immediate visual indication of the alignment of the bone, for example of the tibia or femur, relative to the surfaces of the bone cut. The alignment member therefore enables the surgeon to assess whether thrther resection of the bone(s) are required in order to o provide correct alignment of the bone, for example the femur or tibia, relative to the surfaces of the bone cuts.

The first and second paddles preferably each provide at least one separation aperture or recess for receiving a separation instrument arranged in use to reduce the separation between the paddles prior to insertion between the bone cuts. For example, the at least one separation aperture or recess receives a separation instrument for exerting a compressive force on the first and second paddles in order to reduce the separation of the paddles.

The separation aperture(s) or recess(es) may be provided at any suitable location on the paddles. For example, the separation aperture(s) or recess(es) may be provided at or adjacent an end of a paddle arranged in use to be located at or adjaccnt the medial or lateral surfaces of the bone cut. For example, the separation aperture(s) or recess(es) may be provided by the medial and/or lateral surfaces of at least one of the paddles. Preferably the separation aperture(s) orrecess(es) may be provided by the anterior and/or posterior surfaces of the at least one paddle. The at least one separation aperture or recess may be the same as the at least one alignment aperture.

According to a still further aspect of the present invention, there is provided a method of determining the alignment of surfaces of bone cuts during a surgical procedure comprising: inserting an apparatus as herein described between two bone cuts; aligning a first surface of the first paddle adjacent a first bone cut; aligning a second surface of the second paddle adjacent a second bone cut; and determining the alignment of the first and second bone cuts from the angle provided between the first and second paddle as indicated by the angle measurement device.

The method may further comprise engaging a separation instrument with the first and second paddles prior to insertion so as to reduce the separation therebetween.

The separation instrument may be engaged with at least one separation aperture provided by each of the first and second paddles.

The method may also further comprise inserting a portion of an alignment member into at least one aperture provided by one of the first or second paddles, such that the alignment member extends in use along or adjacent at least one of the first and second bones. The alignment member may be received within an alignment aperture provided by at least one of the paddles.

Brief Description of the Drawings

An embodiment of the invention will now be described, by way of example only, and with reference to the accompanying drawings, in which: Figure 1 illustrates a view from above of the apparatus according to one embodiment of the present invention; Figure 2 illustrates a perspective view of the apparatus of Figure 1; Figure 3 iflustrates a side view of the apparatus of Figure 1; Figure 4 illustrates a side view of a separation instrument for use with the apparatus according to Figure I; Figure 5 illustrates a schematic view of the system according to a further embodiment of the present invention.

Detailed Description of the Invention

With reference to Figures I to 3, the apparatus I comprises a first paddle 2 and a second paddle 3. The first and second paddles 2,3 are in communication and displaceable relative to each other. The first and second paddles 2,3 are contoured to correspond in shape to the bone cuts of the tibia and femur which the paddles 2,3 o are to be placed in contact with. The first paddle 2 is arranged in use to be contacted with the bone cut of the femur and the second paddle is arranged in use to be contacted with the bone cut of the tibia. Prior to insertion, the first paddle 2 extends substantially parallel to the second paddle 3.

Each paddle 2,3 is formed of a single integral unit having an anterior side 4,5; a posterior side 6,7; a medial side 8,9; and a lateral side 10,11. The first and second paddles 2,3 are biased apart from each other by a spring mechanism 12. The spring mechanism 12 comprises two spaced apart coiled springs 13,13' located adjacent opposing sides of the paddles 2,3.

The apparatus 1 further comprises an extension member 14 attached at a first end to the first paddle 2 and attached at the second end to the second paddle 3. The extension member 14 is composed of resilient material. The extension member 14 is pivotally connected to the first and second paddles 2,3. The extension member 14 is aftached adjacent to the medial side 8 of the first paddle and the lateral side 11 of the second paddle. The extension member 14 is arranged in use to restrict the separation of the first and second paddles 2,3 such that the paddles 2,3 do not separate by more than a predetermined maximum limit.

The first paddle 2 comprises a first surface 15 arranged in use to contact the surface of the first bonc cut. The second paddle 3 comprises a first surface 16 arranged in use to contact the surface of the second bone cut. The first and second paddles 2,3 are arranged such that the first surfaces 15,16 of the paddles 2,3 extend substantially parallel to each other prior to insertion within a joint.

The apparatus I ifirther comprises an angle measurement device 30 for indicating the angle between the first surface of the first paddle and the first surface of the second paddle 3. The second paddle 3 provides a gauge 31 located adjacent the anterior side 5 of the second paddle 3. The first paddle 2 provides a needle 32 o located on the anterior side 4 of the first paddle 2. The needle 32 is aligned with and moveable relative to the gauge 31 to indicate the angle between the first surfaces 15,16 of the paddles 2,3.

The first paddle 2 comprises two spaced apart indicator marks 75,75' on the first surface 15. A first indicator mark 75 is located towards the medial side 8 of the first paddle 2. A second indicator mark 75' is located towards the lateral side 10 of the first paddle 2. The second paddle 3 comprises two spaced apart indicator marks 76,76' on the first surface 16. A first indicator mark 76 is located towards the medial side 9 of the second paddle 3. A second indicator mark 76' is located towards the lateral side 11 of the second paddle 3. The indicator marks are equally spaced from the central region of each paddle. The indicator marks 75,75' of the first paddle 2 are aligned with the indicator marks 76,76' of the second paddle 3.

The aligned indicator marks 75,76 and 75',76' of the paddles 2,3 may therefore be used as fixed points at or adjacent the medial and lateral sides of the paddles to indicate the separation of the first surfaces 15,16 of the paddles 2,3. k Figure 3, the indicator marks 75, 75', 76, 76' are visual markings, it is however to be understood that the indicator marks may be any suitable feature for providing a point of reference, for example the indicator marks may be notches, slits, projections, or any other suitable feature.

The sccond paddle 3 provides an alignment aperture (not shown) shaped and dimensioned for engaging an alignment member (not shown). The aperture is provided on the anterior surface 5 of the second paddle 3. The alignment member fits into aperture 18 on the surface 5 of pedal 3.

The first and second paddle 2 and 3 provides four apertures 18, each shaped and dimensioned for receiving a first engagement feature 19 of a separation instrument v" 20. The apertures 18 are provided by the anterior surfaces 4, 5 of the first and second paddIes 2,3.

The separation instrument 20 comprises two first engagement features 19 and two second engagement features 21 pivotally connected at pivot point 22. The second engagement features 21 are arranged in use to engage the apertures 18 provided by the second paddle 3. The first engagement features 19 are arranged to engage the apertures provided by the first paddle 2.

Tn use, the separation instrument 20 engages the first and second paddles 2,3 of the apparatus in order to compress the first and second paddles 2,3 together in order to reduce the separation therebetween. The second engagement features 21 of the separation instrument 20 are received within and engage the apertures 18 provided by the second paddle 3. The first engagement features 19 of the separation instrument 20 are received within and engage the apertures 18 provided by the first paddle 2. The user applies pressure to handles 23 of the separation instrument 20 in order to move first and second engagement features 19,21 towards each other.

As a result, the first and second paddles 2,3 are moved towards each other.

In the compressed position, the apparatus 1 is inserted within the site of the resccted joint such that the first surface 15 of the first paddle 2 is aligned with the bone cut of the femur, and the first surface 16 of the second paddle 3 is aligned with the bone cut of the tibia. The separation instrument 20 is disengaged from the apparatus I. The biasing mechanism 12 provided by springs 13,13' causes the first and second paddles 2,3 to separate within the joint region such that the first surfaces 15,16 of the first and second paddles 2,3 contact the bone cuts of the femur and tibia co respectively.

The needle 32 located on the anterior side 4 of the first paddle 2 moves relative to o the a gauge 31 located adjacent the anterior side 5 of the second paddle 3 to indicate the angle between the first surfaces 15,16 of the paddles 2,3 when in contact with the respective bone cuts. The needle 32 and gauge 31 therefore provide an immediate, visual indication of the alignment of the first surfaces 15,16 within the joint and therefore providing an indication to the surgeon of the relative angles of the bone cuts. The surgeon can therefore see whether further balancing of soil tissues is required in order to provide two substantially parallel bone cuts of the joint. If further soft tissue release is impractical or deemed unnecessary, the device allows the surgeon to choose the angle displayed on the gauge 31 for sefting the rotation of the femoral component. This is done before the anterior, posterior and chamfer cuts are made on the femur.

An engagement feature of an alignment member (not shown) may be inserted within alignment aperture (not shown) provided on the anterior surface 5 of the second paddle 3. The alignment member extends from the second paddle 3 along the length of the tibia. The alignment member therefore provides a further visual indication of the alignment of the bone cuts with respect to the length, or longitudinal axis of the adjacent bones. This enables the surgeon to carry out further resection of the bone, if necessary, in order to correct the alignment of the bone cuts relative to the length, or longitudinal axis ofthe bone.

The distance between the indicator markings 75, 75', 76, 76' of the paddles 2,3 can be measured using for example a caliper to determine the spacing between the first surfaces 15,16 of the first and second paddles 2,3 in use.

figure 5 illustrates a thrther embodiment of a system of the present invention. The apparatus 50 comprises a first paddle SI, a second paddle 52, an extension member 53 and a biasing mechanism 54 comprising two spaced apart springs 55,55'. The first and second paddles 51,52 are similar in form and thnction to the first and second paddles 2,3 described in relation to Figures ito 3.

The first paddle 51 of apparatus 50 provides two spaced apart alignment apertures 56 provided on the anterior surface 57 of the paddle 51. The second paddle 52 provides two spaced apart alignment apertures 58 provided on the anterior surface 59 of the paddle 52. The alignment apertures 56 provided by the first paddle 51 are each aligned with a corresponding aperture 58 provided by the second paddle 52.

The apparatus 50 further comprises an angle measurement device 60 for indicating the angle between the first surface 61 of the first paddle 51 and the first surface 62 of the second paddle 52. The second paddle 52 provides a gauge 63 located adjacent the anterior surface 59 of the second paddle 52. The first paddle 51 provides a needle 64 located on the anterior surface 57 of the first paddle 51. The needle 64 is aligned with and moveable relative to the gauge 63 to indicate the angle between the first surfaces 6 I, 62 of the paddles 51,52.

The apertures 58 provided by the second paddle 52 also function as alignment apertures shaped and dimensioned for engaging an alignment member 65. The alignment member 65 comprises a substantially U-shaped portion providing two spaced apart engagement features 66,66' shaped and dimensioned and spaced apart for engagement with the apertures 58 provided by the second paddle 52. The alignment member 65 further comprises an elongate portion 67.

The separation instrument 68 comprises a first engagement feature 69 for engagement with the first paddle SI and a second engagement feature 70 for engagement with the second paddle 52 of the apparatus 50.

The first engagement feature 69 and a second engagement feature 70 arc pivotally connected at pivot point 71 located between the engagement features 69,70 and handle portions 72. The first engagement feature 69 provides two protrusions 73 each arranged in use to engage one of the apertures 56 provided by the first paddle o 51. The second engagement feature 70 provides two protrusions 74 each arranged in use to engage one of the apertures 58 provided by the second paddle 52.

In use, the separation instrument 68 engages the first and second paddles 5 1,52 of the apparatus in order to compress the first and second paddles 5 1,52 together in order to reduce the separation therebetween. The profrusions 73 of the first engagement feature 69 of the separation instrument 68 are received within and engages the apertures 56 provided by the first paddle 51. The protrusions 74 of the second engagement feature 70 of the separation instrument 68 are received within and engage the apertures 58 provided by the second paddle 52.

The user applies pressure to handles 72 of the separation instrument 68 in order to move first and second engagement features 69,70 towards each other. As a result, the first and second paddles 51,52 of the apparatus 50 are moved towards each other.

In the compressed position, the apparatus 1 is inserted within the site of the resected joint such that the first surfitce of the first paddle 51 is aligned with the bone cut of the femur, and the first surface of the second paddle 52 is aligned with S the bone cut of the tibia. The separation instrument 68 is then disengaged from the apparatus 1.

The biasing mechanism 54 provided by springs 55,55' causes the first and second paddles 51,52 to separate within the joint region such that the first surfices of the first and second paddles 51,52 contact the bone cuts of the femur and tibia rcspcctively.

As the first and second paddles 51,52 separate within the joint region, the angle ___ between the paddles 51,52 varies. As the angle between the paddles 51,52 varies the needle 64 located on the anterior side of the first paddle 51 moves relative to o the gauge 63 located adjacent the anterior side of the second paddle 52. When the 0) first surfltces of the first and second paddles 51,52 abuts the adjacent bone cut the CtsJ needle 64 moves relative to the gauge 63 to define the angle between the first surfaces of the paddles 5 1,52 when in contact with the respective bone cuts. The needle 64 and gauge 63 thereibre provide an immediate, visual indication of the alignment of the first surfitces within the joint and therefore providing an indication to the surgeon of the relative angles of the bone cuts. The surgeon can thereibre see whether further resection of the bone surfices is required in order to provide two substantially parallel bone cuts of the joint Engagement features 66,66' of the alignment member 65 may then be inserted within apertures 58 provided by the second paddle 52. The elongate portion 67 of the alignment member 65 extends from the second paddle 52 along the length of the tibia. The alignment member theivibit provides a further visual indication of the alignment of the bone cuts with respect to the length, or longitudinal axis of the adjacent bones, such as for example the tibia. This enables the surgeon to carry out further resection of the bone, if necessary, in order to correct the alignment of the bone cuts relative to the length, or longitudinal axis of the bone. The alignment member 65 may then be engaged with the apertures 56 provided by the first paddle 51 in ordcr forthc surgcon to assess thc alignmcnt of thc othcr surface of thc bonc cut relative to the length, or longitudinal axis of the other bone, such as for

example the femur.

Although aspects of the invention have been described with reference to the embodiment shown in the accompanying drawings, it is to be understood that the invention is not limited to the precise embodiment shown and that various changes and modifications may be effected without thrther inventive skill and effort, for example, although the present invention is discussed herein in relation to pmviding bone surfaces which extend parallel to each other, it is to be understood that the apparatus may be used during surgery to accurately resect bone joints such that the 0 bone surfaces extend at any predetermined angle relative to each other. a)

Claims

CLAIMS1. An orthopaedie apparatus for use in assessing bone cuts during an ortbopaedic surgical procedure on a patient, the apparatus cowj.nising: a. a first paddle providing a first surfitce configured to contact a suthce of a first bone cut; and b. a second paddle in communication with and displaceable relative to the first paddle, in which the second paddle provides a first suite configured to contact a surthce of a second bone cut; in which the apparatus thrther comprises an angle measurement device for deteimining the angle bctween the first surfaces of the first and second paddles.
2. Anapparatusasclaimedinclaiml,inwhichthefirstbonecutisafemur cut, and the second bone cut is a tibia cut.o
3. Anapparatusaselaimedineitherofclaimsl and2,inwhichagaugeis 0) provided by one of the first or second paddle(s), and an indicator frature is CJ provided by the other paddle(s) to be in communication with and moveable with respect to said gauge.
4. An apparatus as claimed in any preceding claim, in which the apparatus further comprises at least one extension member connected at a first end to a first paddle and connected at a second end to a second paddle.
5. An apparatus as claimed in claim 4, in which the at least one extension member is pivotally connected to the paddles at least one of the first and second ends.
6. Ai apparatus as claimed in any preceding claim, in which the apparatus further comprises at least one spring mechanism configured to bias the first paddle away from the second paddle.
7. An apparatus as claimed in any preceding claim, in which the apparatus further comprises a separation measurement device configured to provide a visual indication of the separation between the first surface of the first paddle and the first surface of the second paddle.
8. An apparatus as claimed in any preceding claim, in which the first and second paddles provide at least one alignment aperture for engaging a portion of an alignment member.
9. An apparatus as claimed in claim 8, in which the at least one alignment aperture is provided to engage an alignment member such that at least a portion of o the alignment member is arranged in use to extend along or adjacent at least one of the first or second bones.
10. Ai apparatus as claimed in claim 9, in which the alignment member is an elongate member comprising an engagement feature at a first end thereof for engaging the at least one alignment aperture.
II. An apparatus as claimed in any preceding claim, in which each of the first and second paddles provides at least one separation aperture for receiving instrumentation for reducing the separation between the paddles prior to insertion between the bone cuts.
12. An apparatus as claimed iii claim II, in which the at least one separation aperture is provided by the at least one alignment aperture.
13. An orthopaedic system for use in assessing bone cuts during an orthopaedic surgical procedure on a patient, comprising apparatus as claimed in any one of claims 1 to 12; and a separation instrument arranged to engage the apparatus, in which the instrument is configured to reduce the separation between the paddles of the apparatus prior to insertion between the bone cuts.
14. A system as claimed in claim 13, in which each of the at least one first and second paddles of the apparatus provides at least onc separation aperture for receiving the separation instrumcnt; and in which thc instrument is configured to cxcii a compressive force between the first and second paddles.
15. A mcthod of dctcmuining the alignment of surfaces of bone cuts during a surgical procedure comprising: inserting an apparatus as claimed in any one of claims 1 to 13 between two bone cuts; o aligning a first surface of the first paddle adjacent a first bone cut; aligning a second surface of the second paddle adjacent a second bone cut; and determining the alignment of the first and second bone cuts from the angle provided between the first paddle and the second paddle as indicated by the angle measurement device.
16. A method as claimed in claim IS, thrthcr comprising engaging a separation instrument with the first paddle and the second paddle prior to insertion so as to reduce the separation therebetween.
17. A method as claimed in either of claims 15 and 16, thrther comprising inserting an engagement feature of an alignment member into an opening provided by one of the first or second paddles, such that the alignment member extends along or adjacent at least one ofthe first and second bones.