Knee replacement instrumentation

Abstract

There is provided instruments for use during knee replacement surgery. Amongst other instruments, there is provided a clamp (100) for use in knee replacement surgery, the clamp (100) being operable to engage with a femoral sizing spoon (60) and a tibial resection guide (70) so as to enable positioning of the tibial resection guide (70) relative to a tibia (3) of a patient, the clamp (100) comprising an adjustment means configured to enable a thickness of a locking element (150) between a lower surface (154) and an upper surface (152) to be varied.

Description

[0001] KNEE REPLACEMENT INSTRUMENTATION

[0002] FIELD OF THE INVENTION

[0003] The present invention relates to instruments for use in knee replacement surgery, in particular unicompartmental (partial) knee replacement surgery.

[0004] BACKGROUND

[0005] Knee replacement surgery, and in particular unicompartmental or partial knee replacement surgery, can significantly improve the quality of life for people suffering from damage, disease or age-related degradation to their knee or knees. Systems such as the Oxford® Partial Knee can greatly reduce pain and improve mobility, while providing relative non-invasive installation and faster recovery times compared to traditional full knee replacement.

[0006] However, for any knee replacement system, it is vital that components are correctly sized to fit the patient, appropriately positioned relative to the bones of the knee, and securely attached as necessary, to ensure that the replacement knee functions correctly. Systems typically require many different instruments in order to properly install the replacement knee components. Providing variability of the components (e.g., varying the size / thickness of the tibial, femoral or bearing components) and positioning these appropriately for each patient with differing anatomy can significantly increase the number of components that are required. Many duplicate instruments may need to be provided to a surgeon (or in a hospital equipment inventory) in alternative sizes to enable this variability.

[0007] Additionally, and despite this variability, correct operation of instruments and installation of the components is vital to ensure that the replacement knee is installed safely and securely. Any modifications to these instruments that can improve the ease of use or effectiveness of knee replacement systems can drastically improve the overall process for installing said knee replacements, even more so when these improvements are taken in aggregate across all of the instruments that are used.

[0008] SUMMARY

[0009] According to a first aspect of the invention, there is provided a clamp for use in knee replacement surgery, the clamp being operable to engage with a femoral sizing spoonand a tibial resection guide so as to enable positioning of the tibial resection guide relative to a tibia of a patient. The clamp comprises:

[0010] an adjustable locking element for insertion in use between the femoral sizing spoon and the tibial resection guide;

[0011] a body comprising an upper portion and a lower portion, the upper portion being movably coupled to the locking element;

[0012] a retaining member, the retaining member being coupled to the upper portion of the body;

[0013] a locking mechanism, wherein the locking mechanism is movable between: an unlocked position, wherein the clamp is free to move relative to the femoral sizing spoon and the tibial resection guide; and

[0014] a locked position, wherein the tibial resection guide is clamped between the lower portion of the body and a lower surface of the locking element, and the femoral sizing spoon is clamped between the retaining member and an upper surface of the locking element; and

[0015] an adjustment means, or adjustor, wherein the adjustment means is configured to enable a thickness of the locking element between the lower surface and the upper surface to be varied.

[0016] The clamp can allow for stabilisation and positioning of the tibial resection guide relative to the femoral sizing spoon. I.e., the tibial resection guide can be positioned with respect the femur - similarly to using known clamps - prior to the tibial resection guide being coupled to the tibia using removeable pins or the like. Correct positioning of the tibial resection guide can allow for the correct depth of resection to be performed on a tibial condyle, i.e., deep enough to enable secure attachment of a tibial knee replacement component but not too deep so as to cause damage.

[0017] However, the adjustable locking element of the present invention advantageously allows the tibial resection guide to be variably positioned further up / down the tibia. Such variation may be used to: accommodate tibial components of a knee replacement that are different thicknesses; and / or accommodate bearings - the component that sits between the tibial component and the femoral component of the knee replacement - of different thicknesses, including both mobile bearings (bearings that are not fixed to the tibial or femoral component) and fixed bearings (e.g., bearings fixedly coupled to the tibial component); and / or to allow desirable tibial resection depth as determined by asurgeon (e.g., a greater cutting depth may be required if the tibial condyle of the patient is very diseased or, alternatively, a lesser cutting depth may be required if the tibial condyle is weakened).

[0018] Thus, the clamp of the present invention can provide a convenient means for installing knee replacement components, for example the Oxford Partial Knee from Zimmer Biomet, in a repeatable and controlled manner. The present invention may achieve this using fewer components than existing instrumentation kits. Existing clamps comprising rigid locking guides may require additional components - e.g., multiple sized clamps and / or femoral sizing spoons of different thickness - in order to achieve the appropriate positioning of the tibial resection guide relative to the knee of the patient. The Oxford Partial Knee from Zimmer Biomet is described at

[0019]

[0020]

[0021] including an animation of the installation of said knee using known instrumentation. The Oxford Partial Knee implant and associated surgery methods are also described in “Unicompartmental arthroplasty with the Oxford knee”, Goodfellow et al., 2nd edition 2015. The content of this disclosure is incorporated by reference herein.

[0022] For a surgeon performing a partial knee replacement surgery, the adjustable G-clamp of the present invention can allow for improved ease of use. By adjusting the thickness of the clamp, the tibial resection guide can be better positioned prior to fixation to the tibia. This adjustment is done in a controllable and defined manner using the clamp of the present invention, thereby reducing the need for the surgeon to make manual adjustments. For a patient undergoing said partial knee replacement surgery, the use of the adjustable G-clamp of the present invention can reduce the likelihood of damage to the knee during surgery (which may be caused by incorrect cutting if the tibial resection guide is not properly positioned) Following the surgery, the patient may recover more quickly and / or achieve a better quality of life as a result of the partial knee replacement being installed optimally. For healthcare providers and hospitals, the adjustable G-clamp of the present invention may reduce the number of surgical instruments that must be purchased, stored and maintained; the adjustable nature of the clamp may reduce the number of instruments needed.The locking element may comprise a first portion comprising the upper surface and a second portion comprising the lower surface, the first portion and second portion of the locking element being movably coupled to one another. The adjustment means may comprise a first adjustment component, the first adjustment component comprising a threaded screw portion located between the first portion and the second portion of the locking element.

[0023] The first portion and the second portion of the locking element may be moved relative to one another prior to or during positioning of the clamp relative to the femoral sizing spoon and the tibial resection guide. The first portion and second portion may then be retained in the same position while the tibial resection guide is pinned to the tibia. Providing the locking element as a first portion and a second portion that are threaded together can provide a convenient means for adjusting the thickness of the locking element; the thickness can be easily varied by rotating the first portion relative to the second portion. The adjustment means may comprise a different mechanism. For example, the locking element may be telescopically extending.

[0024] The adjustment means may further be configured to enable a distance between the retaining member and the upper portion of the body to be varied, the variation in the distance between the retaining member and the upper portion of the body being equal to the variation in the thickness of the locking element between the lower surface and the upper surface.

[0025] Varying the distance between the retaining member and the upper portion of the body by an amount equal to the variation in the thickness of the locking element between the lower surface and the upper surface can allow the separation between the retaining means and the upper surface of the locking element to be maintained constant, despite the movement of these components. This can allow the femoral sizing spoon to be suitably clamped between the retaining member and the upper surface of the locking element when the clamp is in the locked position.

[0026] The adjustment means may further comprise a second adjustment portion, preferably the second adjustment portion comprising a threaded screw portion. The threaded screw portion of the second adjustment portion may have a pitch equal to that of the threadedscrew portion of the first adjustment portion when the first adjustment component comprises a threaded screw portion.

[0027] Providing threaded screw portions that have equal pitch can allow for the variation of the thickness of the locking element and the variation of the height of the retaining member relative to the upper portion of the body to be performed equally in a convenient manner. Equal rotation of the first portion of the locking member and the retaining member will result in equal movement / variation.

[0028] The pitch of the threaded screw portions may be between 2 mm and 4 mm. The pitch of the threaded screw portions may be 3 mm.

[0029] A 3 mm pitch may be preferably as this will allow 3 mm of variance in just one full turn of the first portion of the locking element. 3 mm variation in thickness of the locking element may be sufficient for a typical knee replacement system.

[0030] For example, tibial components may come in a range of sizes with thicknesses ranging from 2 mm to 3mm, with the smallest size used with the smallest femoral component and the largest with the largest femoral component. The amount of rotation of the first portion of the locking element relative to the second portion of the locking element between each femoral size would be 30 degrees, requiring 120 degrees of rotation across the 1 mm range. Additionally, different sized bearings may be used. Mobile bearings have a range of thicknesses, for example for 3 mm to 5 mm. 3.5 mm or 4.5 mm bearings are often used, requiring a further 120 degrees of rotation of the locking element accordingly. Furthermore, fixed bearings may have a thicker construct thickness. The thinnest fixed bearing may require a 0.5 mm thicker resection, thereby requiring another 60 degrees of rotation of the locking element. Thus, the total rotation to cover these multiple variations is 300 degrees for a 3 mm pitch. All variations can therefore be achieved in < 1 full turn of the locking element adjustment means.

[0031] The second portion of the locking element and the upper portion of the body may comprise a first rotation prevention means, such that the second portion of the locking element is prevented from rotating relative to the upper portion of the body.This may mean that when the first portion of the locking element is rotated, the second portion remains in place relative to the body of the clamp, thereby allowing the first portion to be moved up / down via the threaded screw portion. Despite being rotationally restricted, the second portion of the locking element can move axially relative to the upper portion of the body (e.g., the second portion locking element / the lower surface can move up and down relative to the upper portion of the body, along an axis in the direction of the thickness of the locking element). The first rotation prevention means may comprise the upper portion of the body extending through a slot or recess in the side of the second portion of the locking element.

[0032] The first portion of the locking element and the retaining member may comprise a second rotation prevention means, such that the retaining member is prevented from rotating relative to the first portion of the locking element.

[0033] This may mean that as the first portion of the locking element is rotated (to adjust the thickness of the locking element), the retaining member is also necessarily rotated by the same amount. In effect, the first portion of the locking element and the retaining member may be prevented from being rotated independent of one another. Thus, equal variation of the position of the two components may be achieved automatically - e.g., if the thickness of the locking element by a certain distance, the retaining member moves away from the lower surface of the locking element by an equal distance). The second rotation prevention means may comprise corresponding engagement surfaces on the first portion of the locking element and the retaining member.

[0034] The adjustment means may comprise a locking element securing mechanism, the securing mechanism being configured so that, when engaged, the thickness of the locking element is fixed.

[0035] The locking element securing mechanism can allow the thickness of the locking element to be fixed in position once a desired thickness is achieved. Therefore, the tibial resection guide can be maintained in one position relative to the tibia once the locking mechanism is in the locked position. The securing mechanism may be operated to prevent rotation of the first portion of the locking element with respect to the second portion.The locking engagement securing mechanism may comprise a protrusion and at least one notch, wherein one of the said protrusion or notch is located on a surface of the locking element, the protrusion being engageable with the notch so as to prevent movement of the locking element relative to the body.

[0036] For example, the protrusion may be a flexible protrusion located on the body of the clamp and a plurality of notches may be provided on a lower surface of the first portion of the locking element. The flexible protrusion and notches may provide a convenient securing mechanism. The flexible protrusion may be strong enough to hold the first portion of the locking element in position but may be overcome when sufficient rotational force is applied (similar to a snap-fit mechanism). Alternative securing mechanisms may be used, such as a latch that can be optionally engaged with the notches or a ratchet mechanism having one or more non-flexible protrusions. Either the protrusion or the at least one notch may be located on the surface of the locking element.

[0037] The retaining member may comprise a first portion and a second portion, and the locking element may comprise a hole passing through the upper surface. The first portion and the second portion of the retaining member may be detachably couplable such that: the first portion of the retaining member can be located on a first side of the upper surface of the locking element;

[0038] the second portion of the retaining member can be located on a second side of the upper surface of the locking element; and

[0039] the first portion and the second portion of the retaining member may be coupled to one another through the hole of the upper surface of the locking element, such that the first portion and second portion of the retaining member are retained on either side of the upper surface of the locking element.

[0040] The upper portion of the body may comprise a first portion and a second portion, and the locking element may comprise a slot or recess for receiving the upper portion of the body. The first portion and the second portion of the upper portion of the body may be detachably couplable such that:

[0041] the first portion of the upper portion of the body can be received within the slot; andthe second portion of the upper portion of the body can be coupled to the first portion of the upper portion of the body, such that the upper portion of the body are prevented from being removed from slot of the locking element.

[0042] The first portion and the second portion of the retaining member being detachably couplable may allow for easier assembly of the clamp. Likewise, the first portion and the second portion of the upper portion of the body being detachably couplable may allow for easier assembly of the clamp. The retaining member and / or the upper portion of the body may be interfaced / engaged with the locking element before the detachable components are reattached.

[0043] According to a second aspect of invention there is provided a kit of parts for positioning of a tibial resection guide relative to a tibia of a patient during knee replacement surgery. The kit comprises:

[0044] a clamp according to the first aspect;

[0045] a tibial resection guide configured to be received between the upper portion of the body and a lower surface of the locking element of the clamp; and

[0046] at least one femoral sizing spoon configured to be received between the upper surface of the locking element and the retaining member of the clamp, and wherein the femoral sizing spoon comprises:

[0047] a head configured to be inserted between the femoral and tibial condyles of the patient’s knee;

[0048] a shaft comprising a hole therethrough, the hole being configured to receive the retaining member of the clamp.

[0049] As discussed above, the clamp of the present invention may allow for greater variability of the tibial resection guide placement with fewer components. However, the kit may comprise additional components as needed. For example, the kit may comprise five femoral sizing spoons of various sizes (i.e., having heads of varying size for fitting to different sized femurs) and / or three universal spoons of 1 mm, 2 mm and 3 mm thickness.

[0050] The kit may comprise any further instruments disclosed herein and / or used in known knee replacement systems. The kit may be provided as part of a wider kit of parts for performing full and / or partial knee replacement surgery and may comprise drillingtools, cutting tools, other cutting and / or drilling guides, pins / nails, and rasps, for example.

[0051] According to another aspect of the invention, there is provided an assembled kit for positioning of a tibial resection guide, the assembled kit comprising the kit of parts of the second aspect, the kit of parts having been coupled to a knee, wherein:

[0052] one of the at least one femoral sizing spoons has been received between femoral and tibial condyles of the knee;

[0053] the retaining member of the clamp has been coupled to the femoral sizing spoon; the tibial resection guide has been received by the clamp; and

[0054] the clamp has been moved to the locked position, such that the tibial resection guide is clamp in position relative to the tibia at the knee.

[0055] The knee in question may be non-living, e.g., a knee of a cadaver or a prosthetic / simulated knee. Alternatively, the knee may be a knee of a living patient, for example during a knee replacement surgery.

[0056] According to a third aspect of the invention, there is provided a method performing partial knee replacement surgery, wherein the surgery comprises performing a tibial resection, the tibial resection comprising:

[0057] inserting a femoral sizing spoon between femoral and tibial condyles of the knee; coupling a clamp to the femoral sizing spoon;

[0058] receiving a tibial resection guide within the clamp;

[0059] adjusting the thickness of the clamp, such that vertical position of the tibial resection guide relative to the tibial condyle is adjusted; and

[0060] locking the clamp in the adjusted position.

[0061] The tibial resection may be performed using any of the apparatuses of the first or second aspect. The partial knee replacement surgery may be performed on a non-living knee, e.g., a knee of a cadaver or a prosthetic / simulated knee, such as during surgical training. The partial knee replacement surgery may be performed on a knee of a living patient during surgery to treat disease, damage or wear of the knee.

[0062] The method of partial knee replacement surgery may comprise any and all steps associated with known partial knee replacement surgeries. For example the surgery maybe performed using an Oxford Partial Knee from Zimmer Biomet, as shown in the Oxford Partial Knee Microplasty Instrumentation Shortened Animation available at the content of which is incorporated by reference

[0063]

[0064] herein. The method may be performed using any of the additional instruments described in the following aspect. The skilled person will understand that each of the instruments of the present disclosure may be used as appropriate instead of the corresponding / similar conventional instruments, thereby providing the advantages described herein.

[0065] According to a fourth aspect of the invention, there is provided a femoral drill guide for guiding a drill during a knee replacement surgery, the femoral drill guide comprising:

[0066] a body comprising a drill guide hole, the drill guide hole being configured to guide the drill when in use;

[0067] a foot configured to be placed upon a portion of a tibial condyle, thereby positioning the drill guide hole relative to a femoral condyle;

[0068] wherein the body comprises a window that is configured such that a user can view a surface of the femoral condyle through the body when in use.

[0069] During drilling of the holes in which a femoral component is attached to the femoral condyle, it is important that said holes are correctly positioned. Failure to do so may result in damage to the femur and / or the femoral component being incorrectly positioned or aligned. As part of the femoral component positioning, a line may be drawn down the middle of the femoral condyle as a reference. Conventional drill guides can make this line difficult to see as it is largely covered once the femoral drill guide is nearly in position. Providing a window through the body can therefore assist a surgeon in positioning the drill guide relative to the reference line, thereby reducing the likelihood that the holes will be drilled incorrectly.

[0070] The foot may comprise a pin (or otherwise more generally a protrusion) located upon an upper surface of the foot, the pin being configured to slide into a groove made in the femoral condyle when in use. In addition to the window (which can assist with alignment of the femoral drill guide relative to a reference line drawn on the femoral condyle), the pin may further assist in correctly positioning the drill guide. The groove in the femoral condyle may be made with the assistance of a cutting block, as described below.According to a fifth aspect of the invention, there is provided a cutting block for guiding the cutting of a groove in a femoral condyle during a knee replacement surgery, the cutting block comprising:

[0071] a body comprising a lower surface and a side surface for positioning respectively against a horizontal cut and a vertical cut made in a tibial condyle when in use;

[0072] at least one channel in an upper surface of the body, the at least one channel being configured such that when a cutting instrument is disposed therein during use, the cutting instrument produces a groove in a surface of the femoral condyle.

[0073] The cutting block can be used alongside the femoral drill guide of the fourth aspect, discussed above. The groove can be used to reference the pin of the femoral drill guide foot, thereby ensuring appropriate positioning (particularly the medio-lateral positioning) of the femoral drill guide with respect to the femoral condyle.

[0074] The cutting block may comprise a single channel in the upper surface of the body, the channel being angled perpendicularly to the upper surface of the body. The single channel may allow for an appropriate single groove to be formed by the cutting instrument in the femoral condyle. The single groove may be wider than a dual -grove cutting block (discussed further below). This may allow the cutting block to accommodate a wider cutting instrument (e.g., a thicker saw blade), so that the groove produced in the femoral condyle is still able to receive the femoral drill guide reference pin.

[0075] Alternatively, the cutting block may comprise a pair of channels in the upper surface of the body. The pair of channels may be angled such that when the cutting instrument is disposed therein during use, the cutting instrument produces an inverted V-shaped groove in the surface of the femoral condyle. An inverted V-shaped groove may similarly provide appropriate positioning of the femoral drill guide, as discussed above.

[0076] According to a sixth aspect of the invention, there is provided a vertical wall rasp for removing bone from a vertical tibial cut made during a knee replacement surgery, the vertical wall rasp comprising a:

[0077] a head comprising a cutting surface; and

[0078] a handle, the handle being detachably coupled to the head;wherein a rear surface of the head opposite the cutting surface is conformally shaped so as to fit around a femoral condyle during use.

[0079] The vertical wall rasp may be used to remove bone from the vertical tibial cut. A surgeon may make a filing motion with the vertical wall rasp in order to achieve this, altering pressure and / or duration of the filing to vary the amount of bone removal. The vertical wall rasp may be used to smooth the surface of the vertical tibial cut and / or adjust the lateral position of the tibial component of the knee replacement. This can enable the tracking of a bearing of the replacement to be optimised and / or optimise tibial loading by the replacement.

[0080] The cutting surface may be at least partially curved. By providing a curved cutting surface, a surgeon may be able to more easily select a particular area of the vertical tibial cut to be acted upon by the vertical wall rasp by altering the angle of the vertical wall rasp with respect to the vertical tibial cut. A flat cutting surface may only be capable of acting upon the entire length of the vertical tibial cut when held flat thereagainst. Furthermore, a flat cutting surface may tend to result in a convex surface at the vertical tibial cutting surface as it is difficult to ensure that the flat cutting surface of the rasp remains flat / parallel to the surface during the bone removal.

[0081] The handle may be detachably coupled to either a first end of the head or to a second end of the head via a common attachment means. By coupling the handle to either a first end or a second end of the head of the vertical wall rasp, the directionality of the cutting surface can be reversed. Thus, a single vertical wall rasp may be used on a left knee or a right, and / or for a medial or a lateral partial knee replacement.

[0082] According to a seventh aspect of the invention, there is provided femoral sizing spoon for use during knee replacement surgery, the femoral sizing spoon comprising;

[0083] a handle, the handle having a hole for receiving a retaining member of a clamp; and

[0084] a head for insertion into an inter-femur / tibia space in use, wherein the head comprises a protrusion located centrally along at least part of the length of the head.

[0085] The protrusion may be sharp cutting edge located upon a top surface of the head and may be configured to engage with a surface of the femoral condyle so as to preventmoving sideways during use of the clamp. The femoral sizing spoon may be used with a clamp according to above aspects of the invention, so as to position a tibial resection guide.

[0086] The width of the head about the protrusion may be no more than 5 mm across, or nor more than 4 mm across, or no more than 3 mm across. Providing a femoral sizing spoon with a narrower head than existing femoral sizing spoons can reduce the amount of separation of the femur and tibia caused by rotation of the femoral sizing spoon during clamping with the clamp.

[0087] Additionally or alternatively to the narrower head discussed above, the head may have a cross-section wherein edge portions of the head are less thick than central portions of the head (the central portions being the surface of the head not including the central protrusion). In other words, the head of the femoral sizing spoon may have a convex-shaped cross-sectional profile. This cross section may also reduce the amount of force applied to surfaces of the knee joint as the femoral sizing spoon is rotated; some rotation may be possible without the head of the spoon forcing the knee joint apart at all.

[0088] According to an eighth aspect of the invention, there is provided a tibial cutting guide for enabling cutting of a tibial condyle, the tibial cutting guide comprising:

[0089] a generally L-shaped body, the L-shaped body having a vertical slot for enabling a vertical cut of the tibial condyle and a horizontal slot for enabling a horizontal cut of the tibial condyle; and

[0090] a locking mechanism, the locking mechanism being configured so that the tibial cutting guide can be detachably and securely coupled to a tibial guide during use.

[0091] Conventionally, it can be difficult providing the tibial cuts that are needed for seating a tibial component of a partial knee transplant (particularly a vertical tibial cut). Making the cut in the correct position and to the correct depth can require significant skill by a surgeon. The tibial cutting guide of the present invention can assist in making tibial cuts in the correct position. A cutting instrument / saw blade can be inserted through the vertical and horizontal slots of the tibial cutting guide, such that the slots provide a guide for the required vertical and horizontal tibial cuts. The locking mechanism (e.g.,a cam mechanism) can secure the cutting guide in the desired position relative to a tibial guide, such as the tibial resection guide used for positioning the clamp discussed above.

[0092] The L-shaped body may comprise a hole therethrough, the hole being provided at a corner where the vertical slot and horizontal slot converge, the hole being configured to receive a pin. The pin, once received in the hole, may act an end stop for the saw blade. The saw blade may be prevented from cutting to deep into the tibial condyle by the pin, thereby ensuring that the tibial resection is performed to the desired depth.

[0093] According to a ninth aspect of the invention, there is provided a tibial cutting guide kit comprising:

[0094] the tibial cutting guide of the eighth aspect; and

[0095] a pin, the pin being configured to be received by the hole of the tibial cutting guide and having plurality of markings at a distal end, the plurality of markings indicating a level of insertion of the pin into the hole of the tibial cutting guide.

[0096] As discussed above, the pin may act as an end stop of the saw blade. The plurality of markings (e.g., notches on a shaft of the pin) can provide an indication of how far into the hole / tibial condyle the pin is inserted, and thus the depth of the resulting tibial cutting. By inserting the pin to a desired depth based on the markings, the cutting may enable a range of different size components to be fitted correctly.

[0097] According to a tenth aspect of the invention, there is provided a keel rasp for removing bone from a trench cut into a surface of the tibia during knee replacement surgery, the keel rasp comprising:

[0098] a handle; and

[0099] a cutting end, the cutting end comprising a curved portion across which a cutting surface is provided.

[0100] The cutting end may be generally tear drop shaped or oval shaped, for example. The curved portion of the cutting end may enable for easier removal of bone from the trench cut into the surface of the tibia, particularly at either end of said trench.

[0101] According to a eleventh aspect of the invention, there is provided a pin for use in knee replacement surgery for coupling a tibial resection guide to a tibia, the pin comprising:a shaft; and

[0102] a head, the head being coupled to the shaft at one end and being offset from a central axis running along the length of the shaft.

[0103] The pin may be used in the same manner as a conventional pin. However, by providing the head offset relative to the shaft, the pin may be more easily rotated. The offset head may be used to secure a shim to the tibial resection guide. By rotating the head, the shim may be released, for example. The offset head may comprise a plate extending perpendicularly to the shaft of the pin.

[0104] A lower surface of the head may comprise sloped edges. In other words, the lower surface of the head may have a convex profile, such that edges of the head are thinner than the centre of the head. This may reduce the likelihood of the head catching a shim as the head is rotated, for example.

[0105] According to a twelfth aspect of the invention, there is provided an anti-impingement guide for use in the preparation of a femoral condyle during knee replacement body, the anti-impingement guide comprising:

[0106] a body;

[0107] a peg, the peg being configured to be received within a hole drilled into a surface of the femoral condyle; and

[0108] a posterior extension portion, the posterior extension portion having a slot at a rear end, the posterior extension portion being configured to be placed between a femur and tibia when in use such that a chisel-like instrument can be received in the slot for removing bone at a posterior surface of the femoral condyle; and

[0109] an anterior mill pin configured to receive a milling device when in use for removing bone at an anterior surface of the femoral condyle;

[0110] wherein the posterior extension portion is provided at an angle of 1.5 degrees downwards relative to the peg.

[0111] The anti-impingement guide can be used to assist a surgeon during removal of bone from the anterior and posterior surfaces of the femoral condyle. Such bone removal is typically required to ensure that a bearing of the partial knee implant does not impact the femoral condyle during full extension or full flexion of the knee. The angle between the posterior extension portion and the peg is downwards (i.e ., angled away from eachother) and may be between 1 degree and 2 degrees or between 0.5 degrees and 2.5 degrees, for example. The 1.5 degree angle may allow the anti-impingement guide to correctly fit onto a femoral condyle that has had a posterior say cut at an angle of 1.5 degrees relative to the aforementioned hole. The 1.5 degree angle may provide more secure fixation of a femoral implant component, as discussed further herein.

[0112] The peg may have a flattened lower surface. The flattened lower surface of the peg may reduce the likelihood of damage to hole in which it is received. Completely round pegs may cause damage to a lower surface of the receiving hole, which may reduce the effectiveness of subsequent femoral component fixation within said hole.

[0113] The anterior mill pin may have a length of at least 15 mm, at least 17 mm or at least 19 mm. The length of the anterior mill pin may be 19.75 mm, for example. The longer anterior mill pin length, compared to previous devices (which may have an anterior mill pin length of 14 mm), may reduce the likelihood of the milling device slipping or jamming during bone removal of the anterior surface of the femoral condyle.

[0114] According to an thirteenth aspect of the invention, there is provided a slap hammer for use in knee replacement surgery, the slap hammer comprising:

[0115] a pair of jaws; and

[0116] a shaft comprising a sliding hammer;

[0117] wherein a first jaw of the pair of jaws is located on a first side of the shaft and is coupled to the shaft via a pivot located on a second side of the shaft, and wherein a second jaw of the pair of jaws is located on the second side of the shaft and is coupled to the shaft via a pivot located on the first side of the shaft.

[0118] Conventional slap hammers, where the pivot for each jaw is located on the same respective side, can become loose during use; the action of the sliding hammer can cause the jaws to be pulled apart. By providing the pivot for each jaw on an opposing side, the jaws may be less likely to be pulled apart.

[0119] According to a fourteenth aspect of the invention, there is provided a bone collar remover for use in knee replacement surgery, the bone collar remover comprising: a handle;

[0120] a shaft coupled to the handle, the shaft comprising a cutting portion comprising:a plurality of cutting teeth; and

[0121] an end stop configured to prevent the cutting teeth from cutting below a desired depth relative to a surrounding surface.

[0122] The bone collar remove of the present invention may reduce the likelihood of causing damage to the patient. The end stop may prevent the cutting teeth from cutting too deep into a bone of the patient.

[0123] The shaft may be made of at least two separate components that are detachably coupled to one another. For example, an end portion of the shaft may be like a cap and may be configured to be coupled to remainer of the shaft by sliding onto an inner shaft portion. The shaft being formed by multiple components may assist in the manufacturing or preparation of the cutting teeth.

[0124] According to a fifteenth aspect of the invention, there is provided a tibial component adjustor for use in knee replacement surgery, the tibial component adjustor comprising:

[0125] a handle; and

[0126] a shaft coupled to the handle, the shaft having an engagement portion at an end opposite to the handle, the engagement portion configured to engage with a corresponding portion located on a tibial component.

[0127] By providing an engagement portion configured to engage with a corresponding portion of the tibial component, the position of the tibial component may be more accurately located and / or may be repositioned with a reduced likelihood of damage compared to using a chisel and a hammer. The engagement portion of the tibial component adjustor may be made of a material (e.g., a plastic) that is softer than the tibial component of the implant, so that the adjustor does not scratch / damage the implant.

[0128] BRIEF DESCRIPTION OF DRAWINGS

[0129] Embodiments of the invention will be described, purely by way of example, with reference to the accompanying drawings, in which:

[0130] Figures 1 to 3 show schematic diagrams of an existing clamp used for positioning of a tibial resection guide;Figure 4 shows a schematic diagram of a clamp according to the present invention being used to position a tibial resection guide;

[0131] Figures 5 and 6 show cross-sectional diagrams of a locking element of a clamp according to the present invention;

[0132] Figures 7 to 9 show perspective views of some components of a clamp according to the present invention;

[0133] Figure 10 shows a locking element securing mechanism for use in a clamp according to the present invention;

[0134] Figure 11 shows a perspective view of a knee having undergone a tibial resection, wherein a tibial resection guide is coupled to the tibia;

[0135] Figure 12 shows schematic diagrams of a femoral drill guide according to the present invention;

[0136] Figures 13a, 13b and 14 show schematic diagrams of a cutting block according to the present invention;

[0137] Figure 15 shows a schematic diagram of a vertical wall rasp according to the present invention;

[0138] Figure 16 shows a schematic diagram of a femoral sizing spoon according to the present invention;

[0139] Figure 17a shows a schematic diagram of a tibial cutting guide according to the present invention;

[0140] Figure 17b shows a picture of the tibial cutting guide of Figure 17b in use;

[0141] Figure 18 shows a schematic diagram of a keel rasp according to the present invention;Figure 19 shows a schematic diagram of an eccentric pin / nail according to the present invention;

[0142] Figure 20a shows a schematic diagram, with two different perspectives, of an antiimpingement guide according to the present invention;

[0143] Figure 20b shows illustrations of the anti-impingement guide of Figure 20a being used with an anterior milling device and a chisel-like device;

[0144] Figure 21 shows a schematic diagram of a slap hammer according to the present invention;

[0145] Figure 22 shows a schematic diagram of a bone collar remover according to the present invention; and

[0146] Figure 23 shows a schematic diagram of a tibial adjustor according to the present invention.

[0147] The same reference signs are generally used to refer to corresponding or similar feature in modified and different embodiments.

[0148] DETAILED DESCRIPTION

[0149] Figures 1 to 3 show an existing clamp 10 being used to position a tibial resection guide 70 relative to a tibia 3 of a patient, so that the plateau of the tibial condyle 4 can be resected / cut away for attaching a tibial component as part of a unicompartmental / partial knee replacement. The positioning of the tibial resection guide 70 is performed using a femoral sizing spoon 60 (also referred to as a stylus) that is inserted into the space 5 between the femur 1 and the tibia 3. In this example, the femoral sizing spoon 60 is engaged with the medial condyle 2a of the femur 1 so as to enable replacement of the medial compartment of the knee. By engaging the medial condyle 2a, the femoral sizing spoon 60 essentially acts as a reference (relative to a posterior surface of the femur 1 of the patient) for positioning the clamp 10 and consequently the tibial resection guide 70. The clamp 10 may similarly be used for replacement of the lateral compartment, with the femoral sizing spoon being engaged with the lateral condyle 2b of the femur 1. Asdiscussed further below, the use of a clamp and a femoral sizing spoon can allow for more controlled or repeatable positioning of the tibial resection guide compared to simply position the tibial resection guide with no reference.

[0150] The clamp 10 comprises a generally C or G shaped body 20 (and thus may be referred to as a G-clamp). The body 20 comprises an upper portion 22 and a lower portion 24. The clamp 10 further comprises a retaining member 30 and a locking element 50, the locking element 50 having an upper surface 52 and a lower surface 54. The locking element 50 is also generally C shaped, such that the upper portion 22 of the body 20 is received within a recess or aperture of the C-shaped locking element 50. A hole (not shown) extends through the upper surface 52 of the locking element 52, through which the retaining member 30 extends, the retaining member 30 being coupled to the upper portion 22 of the body and having a head 31 protruding from the upper surface 52 of the locking element 50. The upper portion 22 of the body 20 and the retaining member 30 are able to move up and down relative to the locking element 50 within the confines of the locking element’s C shaped recess, typically by approximately 1-5 mm, for example.

[0151] With the femoral sizing spoon 60 held within the space 5 between the femur 1 and tibia 3 and protruding from the knee, the retaining member 30 of the clamp 10 can engage the femoral sizing spoon 60. The femoral sizing spoon 50 comprises a head 62 that is inserted into the inter-femur / tibia space 5 and a shaft or handle 64. The shaft 64 may comprise a flange or protrusion 65 proximate to the head 62 to prevent a surgeon from inserting the femoral sizing spoon too far into the space 5 of the knee, as shown in Figure 3. The shaft 64 comprises a hole extended therethrough for receiving the head of the retaining member 30. The hole comprises a large opening 66 at a distal end of the shaft 64. The opening 66 opens into an elongated slot 68 that runs along the majority of the length of the shaft 64. The head of the retaining member 30 is passed through the opening 66 from below and the clamp 10 is then slid along the elongated hole 68 so that the clamp 10 abuts or is at least proximate to the tibial condyle 4. Figure 1 shows the clamp 10 engaged with a femoral sizing spoon 60 for illustration only, the clamp and spoon are not engaged with a knee as they would be when in use.

[0152] The upper portion 22 and lower portion 24 of the body 20 define a space 21 for receiving the tibial resection guide 70. Figure 3 shows a three-dimensional diagram of the clamp10 having been coupled to femoral sizing spoon 60 and moved into position proximate to the tibia 3, with the tibial resection guide 70 having been positioned appropriately. The tibial resection guide 70 is to be placed on the surface of the tibia, and may be curved so as to contact a greater portion of the tibia 3. The tibial resection guide 70 may comprise a plurality of parts, such as a body 72 and an upper surface 74 configured for guiding subsequent cutting of the tibial condyle 4. The tibial resection guide 70 may comprise one or more holes 76. Following the positioning discussed above, pins / nails may be inserted through said holes 76 and engaged with the tibia 3 such that the tibial resection guide 70 is fixed to the tibia 3. The clamp 10 and femoral sizing spoon 60 can then be detached and removed (by reversing the locking procedure discussed below) so that resection of the tibial condyle 4 can be performed. Figure 2 shows the clam 10, femoral sizing spoon 60 and tibial resection guide 70 engaged with a knee from a side-on view. Figure 3 shows the same arrangement, but from a perspective view.

[0153] The clamp 10 and femoral sizing spoon 60 enable the tibial resection guide 70 to be positioned correctly prior to pinning in place and therefore may be removed and of no longer use once the tibial resection guide 70 is coupled to the tibia 3 via pins / nails. The tibial resection guide 70 may comprise a handle 71 that can be used for holding / positioning the tibial resection guide 70 prior to being clamped in position by the clamp 10. The handle 71 may be coupled to the body 72 via a screw thread, for example. The handle 71 can thus be decoupled from the body 72 once the tibial resection guide 70 is pinned to the tibia 3, prior to resection.

[0154] The clamp 10 comprises a cam lever 40 hingeably coupled to the lower portion 24 of the body 20. The cam lever 40 comprises a cam 42 located at the lower portion 24 and a lever arm 44. Figures 1 to 3 all show the cam lever in a locked position, whereby the cam 42 partially protrudes into the space 21 between the upper portion 22 and lower portion 24 of the body 20. As shown most clearly in Figure 2, the cam 42 engages with the locking element 70 when the cam lever 40 is in the locked position. The cam 42 forces the body 20 downwards relative to the locking element 50. The result is that the tibial resection guide 70 is clamped between the cam 42 / lower portion 24 and the lower surface 54 of the locking element 50. Likewise, the femoral sizing spoon 60 is clamped between the head of the retaining member 30 and the upper surface 52 of the locking element 50. Thus, the femoral sizing spoon 60, clamp 20 and tibial resection guide 70are all secured in place relative to the tibia 3 for securing the tibial resection guide 70, as shown in Figure 3.

[0155] In an unlocked position (not shown), the lever arm 44 is rotated towards the body 20 and the cam 42 retracts from the space 21. Thus, there is no secure engagement with the tibial resection guide 70; the tibial resection guide 70 is free to move within the space 21 of the body 20. The clamp 10 and tibial resection guide 70 are free to move relative to one another (e.g., when said apparatus is being moved into position or when the clamp 10 is being removed following the tibia resection guide 70 being attached to the tibia 3).

[0156] Figure 4 shows a clamp 100 according to the present invention. The disclosure made above in relation to Figures 1 to 3 is incorporated by reference in relation to the embodiment of the present invention described in Figure 4 onwards. The clamp 100 is coupled to a femoral sizing spoon 60 and a tibial resection guide 70 so that the tibial resection guide 70 is positioned relative to the tibia 4, similarly as discussed with regards to Figures 1 to 3. Likewise, the clamp 100 comprises a cam lever 140 -comprising a cam 142 and a lever arm 144 - that can be moved between a locked position (as shown in Figure 4) and an unlocked position. The clamp 100 can be used with known femoral sizing spoons 60 and tibial resection guides 70, like those discussed in relation to Figures 1 to 3.

[0157] The clamp 100 comprises body 120. The body 120 is generally C or G shaped, comprising an upper portion 122 and a lower portion 124 that define a space 121 for receiving the tibial resection guide 70 therein. The clamp further comprises a retaining member 130 that is coupled to the upper portion 122 of the body 120. The retaining member 130 is couplable to the femoral sizing spoon 60 (e.g., via an opening / slot in the shaft 64 of the femoral sizing spoon, as described in relation to Figures 1 to 3). The clamp 100 further comprises an adjustable locking element 150, discussed further below.

[0158] Figure 5 shows the locking element 150 and other components in greater detail, during adjustment of the thickness (or vertical height) of the locking element 150. The locking element 150 comprises a first portion 151 (having an upper surface 152) and a second portion 153 (having a lower surface 154). The first portion 151 and the second portion153 of the locking element 150 are arranged coaxially to one another, in this example with the second portion 153 inside the first portion 151 (though the opposing arrangement may equally be provided). The two portions 151, 153 comprise a threaded screw portion 155 on respective surfaces, such that the first portion 151 can be screwed relative to the second portion. In doing so, the thickness of the locking element 150 -i.e., the distance between the upper surface 152 and the lower surface 154 - can be adjusted.

[0159] The upper portion 122 of the body 120 comprises a first portion (e.g., an arm portion) that extends from the body through a slot 158 in the side of the lower portion 153 of the locking element 150. The upper portion 122 of the body 120 further comprises a second portion 123 (as shown in Figure 5); a portion that sits within the locking element 150. The retaining member 130 of this example generally comprises a body portion 132, a neck 134 and a head 136. The body portion 132 of the retaining member is located within the locking element 150 and is coupled to the upper body portion 122. A threaded screw portion 133 is provided on respective surfaces of the body portion 132 of the retaining member and the second portion 123 of the upper portion 122 of the body 120, such that the retaining member 130 can be screwed relative to the upper body portion 122 (e.g., up or down). In this example, the upper portion 122, 123 of the body 120 fits within the retaining member body 132, but the opposing arrangement may equally be provided. The neck 134 of the retaining member 130 extends through a hole in the upper surface 152 of the first portion 151 of the locking element 150.

[0160] The left-hand image of Figure 5 shows the locking element (locking element 150 of Figure 4) at its minimum extension - the first portion 151 is fully retracted with respect to the second portion 153. The right-hand image shows the locking element 150 partially extended; the first portion 151 has been unscrewed partially, moving the first portion 151 upwards from the second portion 153. The distance between the upper surface 152 and the lower surface has been increased by Ad. The retaining member 130 has also been moved upwards by a distance of Ad relative to the upper portion 122 of the body 120. As a result, the separation between the upper surface 152 of the locking element 150 and the head 136 of the retaining member 130 has remained the same; both have moved upwards by Ad. By ensuring that the separation between the upper surface 152 of the locking element 150 and the head 136 remains constant, despite the thickness of the locking element being varied, the handle of the femoral sizing spoon 64 can be clamped.In essence, compared to the clamp 10 shown in Figures 1 to 3: the upper portion 22 of the body 20 is similarly the upper portion 122 of the body 120; the retaining member 30 has been replaced by the retaining member 130; and the rigid, block-like locking element 50 has been replaced with the adjustable locking element 150 comprising first portion 151 and second portion 153.

[0161] Figure 6 shows the locking element 150 and associated components as the locking mechanism (i.e., the cam lever 140 of Figure 4) is moved from the unlocked position (left-hand image) to the locked position (right-hand image). In this instance, the adjustable locking element 150 is partially extended; the first portion 151 is moved away from the second portion 153, as in the right-hand image of Figure 5.

[0162] As discussed above, the action of the cam 142 pushes up against the tibial resection guide (not shown) that is received in the space 121 of the body 120, thereby forcing the body 120 of the clamp 100 downwards relative to the tibial resection guide. As a result, the upper body portion 122 is moved down within the slot 158, thereby also moving the head 136 of the retaining member 130 down towards the upper surface 152 of the locking element. Thus, the clamping action of the clamp 100 is similar to that of the clamp 10 shown / discussed in Figures 1 to 3. The clamp 100 can, in use, engage a femoral sizing spoon between the head 136 of the retaining member 130 and the upper surface 152 locking element 150, and a tibial resection guide between the lower surface 152 of the locking element 150 and the cam / lower portion 124 of the body 120 (as seen in Figure 4).

[0163] Figure 7 shows the first portion 151 of the locking element 150 and the retaining member 130 in greater detail and in a disassembled state. The retaining member 130 may be coupled to the first portion 151 of the locking element 150 as shown in Figures 3 to 6. The retaining member body 132 may be held within the locking member, with the retaining member neck 134 extending through a hole 156 in the upper surface 152 of the first portion 151 of the locking element 150, such that the retaining member head 136 protrudes atop the locking element 150.

[0164] The retaining member neck 134 and the hole 156 of the locking element first portion 151 comprise corresponding flat regions 135, 157. The flat regions 135, 157 preventrotational motion of the retaining member 130 relative to the first portion 151 of the locking element 150, while still permitting axial / vertical movement of the retaining member 130 relative to the first portion 151 of the locking element 150 (e.g., when the retaining member 130 is pulled down under the action of the cam lever). As a result, when the first portion 151 of the locking element 150 is rotated relative to the second portion 153 during adjustment of the locking element 150 - via the screw threaded portion 155, as shown in Figure 5 - the retaining member 130 will also be forced to rotate. Thus, the retaining member 130 will correspondingly rotate relative to the upper portion 122 of the body 120, via the threaded screw portion 133. The pitch of the threaded screw portions 133, 155 may be equal (e.g., 3 mm) such that rotation of the first portion 151 during adjustment of the thickness of the locking element 150 results in an equal displacement of the locking element first portion 151 relative to the second portion 153 and of the retaining member 130 to the upper portion 122 of the body 130. Thus, the retaining member head 134 is maintained the same separation away from the upper surface 152 of the locking element 150, so that the femoral sizing spoon can be clamped therebetween. Without the above mechanism, the retaining member 130 may need to be separately adjusted in position as the thickness of the locking element 150 is varied. For example, if the locking element 150 was increased in thickness (i.e., the first portion 151 was moved upwards), the separation between the upper surface 152 of the locking element 150 and the head 136 of the retaining member 130 would be decreased, meaning that the handle 46 of the removal spoon may not be able to fit therebetween as shown in Figure 4.

[0165] Figure 8 shows some components of the clamp 100 having been assembled. The upper portion 122 of the body 120 has been inserted into the slot 158 of the lower portion 153 of the locking element 150. The retaining portion 130 has then been slid into the second portion 153 of the locking element 150 from above, so that the retaining member body 132 is coupled to the upper portion 122 of the body 120 (e.g., via the threaded screw portion 133 shown in Figures 5 and 6. The first portion 151 of the locking element 150 is not shown in Figure 8, but would be coupled to the second portion 153 by sliding the first portion 151 over the retaining member neck 134 and then engaging the threaded screw portion 155.

[0166] In order to assist assembly of the clamp 100, some of the aforementioned components may comprise a plurality of parts that can be disassembled so as to allow interaction.Figure 9 shows an example of the retaining member 130, comprising a body 132 (with threaded screw portion 133 inside for coupling to the upper portion 122 of the body 120), a neck 134 and a head 136. The head 136 is detachably coupled to the neck 134 via a threaded screw 137, for example, so that the head 136 can be removed from the rest of the retaining member 130. This may allow the neck 134 to be threaded through the hole 156 in the first portion 151 of the locking element 150. A detachable head 134 and neck 136 may also enable fine adjustment of the clamp 100 locking mechanism. The position of the head 134 relative to the neck 136 may be optimised (e.g., the head 134 screwed to a greater or lesser extent onto the neck 136) such that, when the clamp 100 is in the locked position, the femoral sizing spoon 60 is securely and rigidly held relative to the cutting guide 20. Once said fine adjustment has been performed, the head 134 and the neck 136 may be fixedly secured to one another in the optimal position. The head 134 and neck 136 may be glued or pinned together, for example.

[0167] The upper portion 122 of the body 120 may be similarly disassembleable (not shown). The second portion 123 of the upper portion 122 of the body 120 may be detachably coupled to the rest of the body 120 (e.g., to the arm or first portion of the upper portion 120) via a threaded screw, for example. The end of the upper portion 122 may comprise a threaded protrusion and the second portion 123 may comprise a corresponding threaded recess - or vice versa - so that the second portion 123 can be removed (similar to how the head 136 can be removed from the retaining member 130 as shown in Figure 9). Alternatively, the second portion 123 of the upper portion 122 and the remainder of the upper portion 122 may be constructed as a single piece. For example, the threaded second portion 123 may be formed on an end of the upper portion 122 via moulding or cutting of the upper portion 122. The lower surface 154 of the second portion 153 of the locking element 150 may have a hole therethrough (not shown in the above Figures). The hole may allow access to the interior of the locking element 150, which may improve the ease of assembly of the components discussed above.

[0168] An example method of assembling the clamp may comprise:

[0169] i) with the second portion 123 removed from the upper portion 122 of the body 120, inserting the upper portion 122 into the slot 158 of the second portion 153 of the locking element 150;

[0170] ii) inserting the second portion 123 of the upper portion 122 of the body 120 into the top of the second portion 153 of the locking element 150, androtating the second portion 123 of the upper portion 122 of the body 120 so that the second portion 123 is coupled to the upper portion 122 via the threaded screw;

[0171] iii) with the head 136 removed from the retaining member 130, passing the neck 134 of the retaining member 130 up through the hole 156 of the first portion 151 of the locking element 150, and then coupling the head 136 to the neck 134 so that the retaining member 130 and the first portion 151 of the locking element 150 are coaxially intercoupled;

[0172] iv) placing the coaxially intercoupled retaining member 130 and the first portion 151 of the locking element 150 onto the second portion 153 of the locking element 150, so that the retaining member body 132 is inserted into the second portion 153 of the locking element 150 and the second portion 153 of the locking element 150 is inserted into the first portion 151 of the locking element 150;

[0173] v) simultaneously rotating the retaining member 130 and the first portion 151 of the locking element 150, so that the retaining member 130 is coupled to the upper portion 122 of the body via threaded screw portion 133 and the first portion 151 of the locking element 150 is coupled to the second portion 153 of the locking element 150 via the threaded screw portion 155; and vi) adjusting the amount of rotation so as the vary the thickness of the locking element 150 (as shown in Figure 5).

[0174] Figure 10 shows an example of a locking element securing mechanism 180, configured to hold the locking element 150 at a set thickness. The securing mechanism 180 comprises a flexible protrusion 182 (e.g., a pin-like member made of a flexible and / or deformable material). The flexible protrusion may comprise a resilient biasing component, for example a spring, so that it is biased upwards. The locking element securing mechanism may pass around the outside of the second portion 153 of the locking element 150 and may coupled to an opposing side thereof (not shown in Figure 10).

[0175] A lower collar / edge 159 of the first portion 151 of the locking element 150 comprises a plurality of notches 184. As the first portion 151 is rotated relative to the second portion 153 of the locking element 150 (so as to adjust the thickness, as described above), the flexible protrusion 182 engages with the notches 184, thereby securing the rotationalposition of the first portion 151 in discrete positions. Each of the plurality of notches 184 may be located at determined positions such that rotation by one notch produces a desired changes in thickness of the locking element 150. For example, where the threaded screw portion 155 has a 3 mm pitch, the notches 184 may be placed 30 degrees apart so that each notch corresponds to 0.25 mm of thickness variance.

[0176] Indicators, such as engraved or printed letters / numbers, may be provided adjacent to each notch 184 (not shown in Figure 10), which may assist a surgeon in selecting the correct thickness of the locking element 150.

[0177] The lower collar 159 may be sloped, and the slope may match the pitch of the threaded screw portion 155 within the locking element 150, so that as the first portion 151 moves up / down relative to the second portion 153 during rotation the height of the collar 159 at the flexible protrusion 182 remains constant, such that the flexible protrusion 182 can correctly engage with the notch 184. The flexible protrusion 182 may be slightly bent or curved in the direction of the lower collar slope so, when sufficient twisting force is applied, the flexible protrusion 182 is able to pass over an end stop protrusion 185 on the lower collar 159. This may allow the locking element 150 to be disassembled more easily, which may assist with cleaning of the device, for example.

[0178] The locking element securing mechanism 180 is just one example of a suitable mechanism. Any mechanism that enables the first portion 151 of the locking element to be retained in one position relative to the body 120 of the clamp 100 may be used instead. For example, the notches 184 and the protrusion 182 of Figure 10 may be switched, such that a plurality of protrusions are provided on the first portion for selectively engaging with a single. Likewise, the flexible protrusion 182 may instead be replaced by a non-flexible protrusion, with the notches 184 instead being flexible / at least partially deformable. The protrusion may instead comprise a biasing mechanism (e.g., a spring) that provides a retaining force against the notches, or the protrusion may be manually operable like a latch or bolt, for example.

[0179] Figure 11 shows the tibial resection guide 70 (as described above) pinned to the tibial condyle 4 using a pair of pins 77. Any suitable pin may be used. For example, rather than the pins 77 shown in this Figure, nails 800 as discussed further below (as shown in Figure 19), may be used. The tibial resection guide 70 has been positioned using aclamp and femoral sizing spoon as discussed, but these are removed following the pinning of the tibial resection guide 70. The tibial resection guide 70 has the been used to resect an upper portion of the tibial condyle 4 using a saw. A vertical cut 4y and a horizontal cut 4x are made during the resection. Following the resection, the pins 77 can be extracted and the tibial resection guide 70 removed. The resection itself can be performed using existing methods and is shown here to provide context to the below instrumentation.

[0180] Figure 12 shows a femoral drill guide 200 in a perspective view (right hand side) and an end on view (left hand side). The femoral drill guide 200 comprises a body 210 that is coupled to a foot 220. In use, the foot 200 can be placed on top of the horizontal cut 4x of the femoral condyle 4 shown in Figure 11, in abutment with the vertical cut 4y. The femoral drill guide 200 is orientated such that the body 210 protrudes from the front of the knee, as per conventional drill guides of this type. The foot 220 may be coupled to body 210 via an adjustment means 212. The adjustment means 212 may comprise a ratcheting mechanism, for example, and may be used to adjust the height of the body 210 relative to the foot 220. Thus, the height of the drilling relative to the tibial condyle may be adjusted. As shown in Figure 12, the body 210 may have markings showing the selected height.

[0181] The femoral drill guide comprises one or more drill guide holes 230, 232 that pass through the body 210 of the drill guide 200. Once in position, a drill can be inserted through the drill guide holes 230, 232 and operated to produce drill holes in the femoral condyle accordingly. The drill guide holes may be of different sizes so as to correctly receive a femoral component of a replacement knee. For example, a lower hole 230 may be configured to receive a 6 mm diameter drill, while an upper hole 232 may be configured to receive a 3 mm diameter drill. For existing femoral drill guides, the drill guide holes were positioned so that when the femoral component is inserted, an inferior surface of the femoral component is aligned with the corresponding surface of the femoral condyle. For the femoral drill guide of the present invention, the drill guide holes 132, 134 have been moved upwards by approximately 1 mm. This may allow for some variation / inaccuracy in the system, thereby ensuring that the bearing is not set too tightly.During femoral hole drilling, a reference line is typically drawn down the centre of the femoral condyle 2a, 2b so as to indicate correct alignment of the drill holes. This line can be obscured by the body of conventional drill guides, which can interfere with a surgeon’s practice. The femoral drill guide 200 comprises a window 231 through a portion of the body 210. As shown in Figure 12, the window 231 comprises a cutout or gap within the body of the femoral drill guide, e.g., along the path of the drill guide hole 230. The window 231 can allow light into the drill guide hole 230, such that the surgeon is able to view the reference line as the femoral drill guide 200 is moved into position at the knee.

[0182] When using the femoral drill guide 200, it is important not to subluxate the patella too far lateral, as this tends to subluxate the tibia laterally. For conventional femoral drilling guides, where the drilling guide is resting against the vertical cut 4y of the tibial condyle 4, this will tend to result in the femoral drill holes being too far lateral. The femoral drill guide 200 comprises an upper portion 214 having an indented surface. In essence, material has been removed from the body 210 in this region compared to conventional femoral drill guides so that the drill guide 200 does not contact the patella when in use.

[0183] During femoral drill hole drilling, the femoral drill guide 200 is typically coupled to an intramedullary rod (not shown) that has been placed in the femur 1, protruding between the femoral condyles 2a, 2b. The femoral drill guide 200 is coupled to the intramedullary rod via an adaptor or connection link, the adaptor having a first end of coupling to the intramedullary rod and a second end for coupling to the femoral drill guide 200. The body 210 of the femoral drill guide 200 is provided with one or more attachment points 216; holes that may receive an end of the adaptor / link.

[0184] For a medial partial / unicompartmental knee replacement, for example, the adaptor may be attached to the femoral drill guide via the attachment holes 216 on the appropriate side. Pairs of adaptors / holes may be flexed 10 degrees and 7 degrees varus so that the drill is aimed towards the femoral head but flexed relative to this. For a lateral partial / unicompartmental knee replacement, for example, the adaptor may be attached to the femoral drill guide 200 so that, when linked to the intramedullary rod, the drill holes and thus the femoral component are approximately 5 degrees flexed (soft tissues are often too tight for 10 degrees) and parallel to a mechanical axis of the knee. As the entrance to the femoral canal is far lateral, no valgus is required in the adaptor. Thefemoral drill guide 200 comprises at least one attachment point 216 located above the upper drill guide hole 232, thereby simplifying attachment of the adaptor.

[0185] Conventional femoral drill guides may not reliably position the femoral component in the optimal medial-lateral position. The optimal position, with the knee flexed, is approximately 1 mm from the vertical cut 4y. This position may minimise the risk of: wear, by avoiding bearing overhang); dislocation, by avoiding bearing spinning; and subluxation, by avoiding bearing impingement on a vertical wall of the tibial component. Aligning conventional drill guides up with the condyle centre often results in the femoral component being too medial. Conversely, resting the drill guide against the vertical cut 4y will make it too lateral if the intramedullary rod causes subluxation in the knee.

[0186] The femoral drill guide 200 may be provided with a pin or a peg 222 located on an upper surface of the foot 220. The pin 222 may be slotted into a groove in a surface of the femoral condyle 2a, 2b, the groove having been made to enable correct positioning of the femoral drill guide 200 about the pin 222. The groove in the femoral condyle may be formed using a cutting block, as described below. The pin 222 may be detachably couplable to the foot 220 (e.g., using a screw thread) such that it can be removed if a surgeon chooses to not use it and the cutting block for aligning the femoral drill guide 200.

[0187] Although referred to as a ‘pin’, in some examples the pin 222 may instead be a sheet-like or ridge-like protrusion. The sheet-like protrusion may protrude from the surface of foot 220 and run generally in the direction of the holes 230, so that it can be slotted into a groove in a surface of the femoral condyle 2a, 2b as above. The protrusion may have a height from the foot 220 of approximately 5 mm and may have a thickness of approximately 1 mm. The protrusion may be free to rotate relative to the foot (e.g., using a rotatable coupling) by up to 20 degrees, for example, so as to provide some rotational movement of the drill guide 200 when being moved into position within the femoral condyle groove. This alternative example may be used with a single channel cutting block, as discussed below. The sheet-like protrusion may be thinner than the pin 222 shown in Figure 12, enabling it to be slid into the single channel.Alternative to the above sheet-like protrusion, the pin 222 may have a narrower top portion than that shown in Figure 12. The pin 222 may have a diameter of approximately 1 mm, such that it can fit within grooves cut by existing saw blades that are approximately 1.2 mm thick. The narrow part of the pin 222 may be approximately 3 mm long and protrude approximately 3 mm above the upper surface of the foot 220. Such a pin may still be sufficiently strong for positioning the femoral drill guide 200 relative to a groove in a surface of the femoral condyle 2a, 2b, but would be thin enough to fit within a groove made by a single channel cutting block as discussed above.

[0188] In one example, the distance between the lower drill guide hole 230 and the upper surface of the foot 220 is the sum of a+b+c below (where b+c is approximately 1 mm):

[0189] a. the distance between the centre of the pin 222 and the internal posterior surface of the appropriately sized component;

[0190] b. the posterior offset of the component resulting from the 1.5 degree angle of the posterior cut; and

[0191] c. a small offset so variability in the position of the cut will tend to result in the use of selected bearing or a thicker bearing rather than the selected bearing or a thinner one.

[0192] The 1.5 degree angle above refers to the angle between the slope of the posterior saw cut of the femoral condyle and the drill hole produced by the drill hole guide 230, the posterior saw cut being angled downwards from the drill hole. I.e., the angle at which a portion of the femoral condyle is resected is not parallel to the 6 mm drill hole discussed above. As a result, when the femoral component of the implant is impacted, the resultant angle between the bearing surface and the 6 mm peg causes the femoral component to securely engage the femoral condyle.

[0193] Figures 13a, 13b and 14 show a cutting block 300 that can be used to position a femoral drill guide comprising a pin, as discussed above. The cutting block 300 comprises a body 310, having a lower surface 312, upper surface 313 and a side surface 314. The cutting block 300 is positioned on top of the resected portion of the tibial condyle 4 (shown in Figure 11) such that the lower surface 312 rests on the horizontal cut 4x and the side surface 314 abuts the vertical cut 4y.In the example of Figure 13a, the upper surface 313 of the body 310 comprises a pair of channels 316, said channels being angled towards one another at their tops. With the cutting block 300 positioned as above, a saw blade can be inserted into the channels 316 and then engaged with the surface of the femoral condyle above. By cutting in both channels 316, an inverted V-shaped groove is formed in the femoral condyle. Said groove can be used to slide the pin of the femoral drill guide foot into, thus providing positioning, in the medio-lateral direction, of the femoral drill guide. The cutting block 300 may be configured to ensure that the groove is appropriately positioned (e.g., distance between groove centre and vertical cut 4x may be half the bearing width + thickness of wall + 1 mm). The groove may be made using the cutting block 300 the femoral condyle, referenced off the vertical cut 4x, without the intramedullary rod in place. Then, with the intramedullary rod in place, the femoral drill guide can be aligned with the groove.

[0194] Alternatively, as shown in the example of Figure 13b, the body 310 may comprise a single channel 316. The channel 316 may be arranged substantially perpendicularly to the upper surface 313 so that, when used with a cutting instrument, a single vertical groove is produced in the surface of the femoral condyle. The single channel may be wider than each of the pair of channels 316 shown in Figure 13a, so that it can accommodate a wider saw blade, therefore ensuring that the single groove is sufficiently wide enough to receive the pin of the femoral drill guide foot. Alternatively a ‘standard’ saw blade (e.g., a saw blade like that used with the double channel example of Figure 13a) may be used, but the pin of the femoral drill guide foot may have a narrower upper region (e.g., approximately 1 mm thick) so that it can fit in the single groove that is formed in the femoral condyle.

[0195] The cutting block 300 may further comprise an attachment point 320 and handle 322. The handle may be detachably coupled to the body 310 of the cutting block 300 so as to hold the cutting block in place when in use. The attachment point 320 may comprise a threaded hole, for example, with the handle 322 comprising a corresponding threaded portion. The body 310 may comprise two attachment points, so that the handle 322 can be selectively coupled to either side of the body 310, as shown respectively in Figures 13a and 13b (i.e., the attachment point 320 is on either side of the body as shown in these Figures). This may allow the cutting block to be used for the left or right knee, and / or for the lateral or medial condyle. Figure 14 shows the handle 322 attached to thebody 310 of the cutting block 300 of Figure 13a at one side, with a second attachment point 320a visible on the opposing side.

[0196] Figure 15 shows a vertical wall rasp 400 that can be used to remove bone from a vertical tibial cut. The vertical wall rasp comprises a head 410 and a handle 420. The head 410 comprises a cutting surface 412, which may comprise an abrasive or serrated surface, for example. The cutting surface 412 may comprise a plurality of metal teeth, for example. The cutting surface 412 is capable of removing or filing down bone from the vertical tibial cut (e.g., vertical cut 4y shown in Figure 11) by running the vertical wall rasp 400 back and forth against said cut in a filing action. The cutting surface 412 may be curved, for example, convex in profile. The curved cutting surface thus may not engage with the entire length of the vertical tibial cut at any one time. The area of the vertical tibial cut that is being addressed by the curved cutting surface 412 may be adjusted by varying the angle of the vertical wall rasp 400 with respect to the vertical tibial cut.

[0197] A rear surface 414 of the head (a surface opposite to that of the cutting surface 412) may be shaped so as to conform around a femoral condyle when the vertical wall rasp is used. The rear surface 414 may comprise a curved cut out or a fillet of one corner of the rear of the head 412, such that the rear surface 414 does not strike the femoral condyle during use. “Conformally shaped” may just mean that the head 410 is sufficiently thin such that it is able to fit beside the femoral condyle during use. E.g., the head 410 is able to fit into the space 5 between the femur 1 and tibia 3 (as shown in Figure 11, for example), without the rear surface 414 of the head 410 striking the femoral condyle.

[0198] The handle 420 is coupled to the head 410 and generally comprises a gripping portion 412 (to be held by a surgeon) and a neck 414. The handle 420 may be detachably coupled to the head 410 at either a first end 416a (as shown in Figure 15) or at an opposing second end 416b of the head 410. The handle 420 and the head 410 may be coupled to one another using any suitable means. For example, the neck 424 of the handle 424 may comprise a threaded portion at an end opposite to the gripping portion 422. The head may comprise a corresponding threaded hole at the first end 416a and another corresponding threaded hole at the second end 416b. both holes being configured to receive the threaded portion of the neck 424 for detachable coupling.Figure 16 shows a femoral sizing spoon 500 comprising a head 510 and a handle 520. The femoral sizing spoon 500 may be used during positioning of a tibial resection guide as described above, for example as shown in Figure 4. For example, the head of a retaining member of the clamp may be inserted through a widened hole 522 at a distal end of the handle 520. The retaining member can then be slid along an elongated slot 524 in the handle 524, so that the clamp can engage the femoral sizing spoon proximate to the knee. The femoral sizing spoon 500 may be made available in a plurality of different sizes and thickness. Where conventional femoral sizing spoons are provided as a kit of various thickness, these may be replaced by femoral sizing spoons 500 of the present invention provided in the same thicknesses.

[0199] For conventional femoral sizing spoons, when the surfaces of the knee bones are in varus (either due to its shape or to disease) the femoral sizing spoon may not function as designed. When the handle is clamped by the G clamp, it may rotate and thereby force the joint surfaces apart. This stretches the medial collateral ligament and results in the tibial resection being too high.

[0200] The head 510 of the femoral sizing spoon 500 comprises a central protrusion 512 (also known as a cutting edge). The protrusion 512 is located in the ‘bowl’ 514 of the head. By providing the protrusion / cutting edge 512 along the centre of the head 510, it is able to better engage the surface of the femoral condyle, thereby reducing lateral movement or rotation of the spoon.

[0201] Shown inset in Figure 16 is a cross-section through the head 510 of the femoral sizing spoon 500. The protrusion / cutting edge 512, discussed above, is shown located along the centre of the bowl 514. As shown in this cross-section, the edges of the bowl 514 may be thinner than the centre of the bowl proximate to the protrusion 512. I.e., the surface of the bowl may have a convex profile across its cross-section. An upper surface, a lower surface, or both surfaces (as shown in Figure 16) may have said convex profile. E.g., alternatively, the top or bottom surface of the bowl 514 may be flat, with the other surface tapered at the edges. The convex cross-sectional profile of the head 510 may reduce the amount of force applied to surfaces of the knee if the femoral sizing spoon 500 is rotated about an axis along the length of the handle 520. Some rotation may be acceptable without the joint surface being forced apart.Additionally, or alternatively to the convex cross-sectional profile discussed above, the width of the head 510 may be reduced compared to known femoral sizing spoons. The head 510 may have a width of less than 5 mm, for example. A narrower spoon 500 may also reduce the amount of separation of the knee joint surfaces should the spoon rotate at all during clamping. The width of the head may be at least 3 mm, or at least 4 mm, for example. Preferably the width of the head is approximately 5 mm. If the head 510 is much narrower than this, it may not be sufficiently stiff enough for engaging the knee and clamp.

[0202] Figures 17a and 17b show a tibial cutting guide 600 (which may also be referred to as a horizontal -vertical cutting guide). The tibial cutting guide 600 can be used to guide the vertical tibial cut 4y and / or the horizontal tibial cut 4y, like those shown in Figure 11. Making the tibial cuts, particularly the vertical cut, in the correct position and to the correct depth can be difficult using existing tools. The tibial cutting guide 600 may therefore assist a surgeon during the fitting of a tibial component of a partial knee implant.

[0203] The tibial cutting guide 600 comprises a generally L-shaped body 610. Two arms of the body 610 have, respectively, a vertical slot 612 and a horizontal slot 614; narrow slots that pass through the body 610 and can receive a cutting instrument such as a saw blade. Thus, the vertical slot 612 can act as a guide for the vertical tibial cut 4y, while the horizontal slot 614 can act as a guide for the horizontal tibial cut 4x. Figure 17b shows the tibial cutting guide with a saw blade 613 inserted into the vertical slot 612.

[0204] The tibial cutting guide 600 further comprises a locking mechanism that is configured to hold the guide 600 in a desired position during tibial resection. In this example, the body 610 comprises a hooked portion 611 which is configured to fit around a tibial guide, e.g., an extra-medullary tibial guide or the tibial resection guide 70 shown in Figure 11. Figure 17b shows the tibial cutting guide 600 having been positioned onto the tibial resection guide 70; the hooked portion 611 of the body 610 engages upper and lower surfaces of the tibial resection guide.

[0205] The locking mechanism comprises a lever mechanism. A lever arm 620 is provided below the hooked portion 611 of the body 610, the lever arm 620 being pivoted at anend so as to provide a cam 622 which can be moved between a locked and unlocked position by the lever arm 620. Figure 17a shows the tibial cutting guide in a locked configuration; the lever arm 620 is moved downwards so that the cam 622 moved up into the hooked portion 611. If a tibial resection guide 70 were received within the hooked portion 611 prior to this, the cam 622 would engage with the tibial resection guide 70, securing it between the cam 622 and the body 610. The cam 622 is moved to the unlocked position by rotating the lever arm 620 rearwards such that the cam 622 retracts from the hooked portion 611.

[0206] The tibial cutting guide 600 further comprises a hole 616 through the body 610. The hole 610 is provided at a corner where the vertical and horizonal slots 612, 614 meet. The hole 616 is configured to receive a pin 630, shown separately in Figure 17a and with the pin 630 passed through the hole 616 in Figure 17b. When received in the hole 616, the pin 630 acts as an end stop for the cutting depth of the saw blade; the cutting instrument will not be able to move any further into the vertical or horizontal slot 612, 614 than the pin 630 allows. The pin 630 has a plurality of indicators / markings on a distal end (i.e., the end of the pin 630 opposite to the sharp end that is received in the hole 616). In this example, the markings are shown as notched rings on the shaft of the pin 630. The pin can be inserted into the hole 616 to varying depth, with the markings 632 providing an indication to a surgeon of said depth. Thus, using the markings 632, the surgeon can select how far the pin 630 is to be inserted and thus the maximum cutting depth of the tibial resection. The markings 632 may preferably indicate how far the pin 630 should go into the hole 616 to just go through the posterior cortex so that, when cut accordingly, different sizes of femoral component can be used appropriately. Therefore, the combination of the tibial cutting guide 600 and the pin 630 can assist a surgeon in achieving the correct position and depth of the horizonal and vertical tibial cuts 4x, 4y.

[0207] The tibial cutting guide 600 may be used according to the following method, for example. It is assumed that a tibial guide, e.g., a tibial resection guide 70, has been appropriated positioned and affixed to the tibia, as discussed above. The cam 622 of the tibial cutting guide 600 is put into the unlocked position (lever arm 620 moved rearwards) and the tibial cutting guide 600 is then placed onto the tibial resection guide 70. A saw blade 613 is then placed into the vertical slot 612 and the position of the tibial cutting guide 600 adjusted so that the saw blade 613 is position just medial toapex of medial tibial spine, aiming towards the anterior superior iliac spine (ASIS). The cam 622 is then moved to the locked position by moving the lever arm 620 downwards, securing the tibial cutting guide 600 on the tibial resection guide 70. The pin 630 is drilled into the hole 616 and then hammered further until a desired depth is reached, as indicated by the markings on the pin 632. The blade 613 is removed, attached to a cutting instrument, and the vertical cut 4y made through the vertical slot 612 with the pin 630 acting as an end stop. The horizontal cut 4y is then made through the horizontal slot 614 with the pin 630, again, acting as an end stop. The pin 630 is then be removed (e.g., using pliers or a slap hammer), the cam 622 unlocked and the tibial cutting guide 600 removed from the tibial resection guide 70.

[0208] Figure 18 shows a keel rasp comprising a handle 710 and a cutting end 720. During knee replacement surgery, a trench may be cut into a surface of the tibia for receiving a keel of a tibial component of the replacement knee. Referring to Figure 11, following the resection of the tibial condyle, the trench may be cut in the surface formed by the horizontal cut 4x, the trench being situated near the centre of said surface and running in a direction parallel to the vertical cut 4y. Using a keel rasp 700 may allow for fine adjustments of the trench such that the keel of the tibial component is correctly received therein. Bone can be removed from the trench by moving the cutting end 720 of the keel rasp 700 within the trench in a filing motion.

[0209] The keel rasp 700 of the present invention comprises a curved portion 722. The curved portion 722 provides the cutting end 720 with a tear-drop like shape. A cutting surface 724 is provide on the curved portion 722. The cutting surface 724 may be an abrasive surface or may comprise serrated teeth, for example. The tear-drop shaped cutting end 720 may be able to more easily remove bone from the trench (particularly at the ends of the trench) compared to other shaped keel rasps or picks.

[0210] Figure 19 shows a pin or nail 800 that may be used to secure a tibial resection guide to the tibia of a patient during knee replacement surgery, like the pins 77 shown in Figure 11. The pin 800 comprises a shaft 810 and a head 820. The shaft 810 may comprise a pointed or tapered end 812 to assist with securing the pin 800 to the surface of the tibia.

[0211] The head 820 is coupled to an end of the shaft opposite the tapered end 812 and offset therefrom (i.e., relative to an axis passing through the shaft 810 along its length, thehead 820 is not central). An offset head 820 may enable the pin 800 to be rotated more easily. The offset head 820 may be rotated to hold a shim in place against the tibial resection guide (thereby removing the need for other clips or clamps) and can be rotated in the other direction to remove said shim. The pin 800 of the present invention may be rotated easily using pliers or similar devices. As shown in Figure 19, a lower surface of the head 820 may have generally convex profile (e.g., sloped edges). This may reduce the likelihood of the head 820 getting caught on the shim.

[0212] Figures 20a and 20b show an anti-impingement guide 900 (two different views are shown in Figure 20a). The anti-impingement guide 900 comprises a body 910, the body 910 being generally curved / having a concave interior, so that it can be seated onto a femoral condyle. On the interior of the body 910 is provided a first peg 912, a second peg 914 and an anterior mill pin 916. The first peg 912 and the second peg 914 are configured to be received by holes drilled into the femoral condyle when the antiimpingement guide is used (as shown in Figure 20b).

[0213] The first peg 912 and the second peg 914 each have a diameter of 6 mm and 3 mm respectively, so that they can be received within the 6 mm lower hole 230 and the 3 mm upper hole 232 discussed above in relation to the drill guide shown in Figure 12. A lower surface 913 of the first peg 912 may be flattened. Likewise, an upper surface 915 of the second peg 914 may be flattened. The flattened surfaces may help reduce damage to the respective surfaces of the drilled holes in which the pegs 912, 914 are received.

[0214] The anterior mill pin 916 is located on an opposing external side of the body 910. The anterior mill pin 916 is configured to receive an anterior milling device; a device that is configured to fit onto the pin 916 and remove bone from the anterior surface of the femoral condyle. The anterior mill pin has a length of at least 15 mm, e.g., 19.75 mm. This is longer than existing devices and may reduce the likelihood of the anterior milling device slipping and / or jamming. The first peg 912 may be longer (e.g., 18 mm compared to 13.4 mm in previous versions) and / or the second peg 914 may also be longer (e.g., 8.7 mm compared to 6.6 mm in previous versions).

[0215] The anti-impingement guide 900 further comprises a posterior extension portion 920. This is a generally flat extension of the body 910, located at the bottom of the body 910, that extends rearwards from the body in the same direction as the first and second pegs912, 914. The posterior extension portion 920 is angled downwards from the first peg 912 by an angle of 1.5 degrees, so that the anti-impingement guide 900 can be fitted onto a femoral condyle that has been cut at an angle of 1.5 degrees relative to the 6mm drill hole (as discussed above). At a rear end of the posterior extension portion 920 is a slot 922. The slot 922 passes through the posterior extension 920 and is angled upwards rearwardly so that a chisel or similar device can be passed through the slot 922 for removing bone from the posterior surface of the femoral condyle.

[0216] Referring to Figure 20b, the aforementioned anti-impingement guide 900 is shown seated on a femoral condyle; the first peg 912 and second peg 914 have been inserted into holes drilled into the femur 3 and the posterior extension portion 920 is disposed between the tibia 1 and the femur 3. Vertical and horizontal cuts have already been made to the tibia 1, as discussed previously.

[0217] The left-hand image of Figure 20b shows the anti-impingement guide 900 being engaged by an anterior milling device 930. The milling device 930 comprises a cutting head with a hole in the centre, said hole being fitted onto the anterior mill pin 916 of the antiimpingement guide 900. The milling device can then be advanced and used to remove bone from an anterior surface of the femoral condyle around the mill pin 916.

[0218] The right-hand image of Figure 20b shows the anti-impingement guide 900 being engaged by a chisel or similar device 940. The chisel 940 is inserted between the tibia 1 and femur 3 below the posterior extension portion 920. The end of the chisel 940 (which is angled upwards) is then passed through the slot 922. The chisel 940 can then be moved within the slot 922, thereby removing bone from an anterior surface of the femoral condyle.

[0219] Figure 21 shows a slap hammer 1000 comprising a pair of jaws 1010 and a shaft 1020. An abutment or end stop 1022 is located at an end of the shaft 1020 opposite to the jaws 1010. A sliding hammer 1024 is provided upon the shaft 1020 and is free to move along its length. During use, the jaws 1010 can be used to engage an item, for example a pin or a structural member that has been used as part of the knee replacement surgery. The sliding hammer 1024 is then sharply pulled along the shaft 1020 away from the jaws 1010, until it collides with the end stop 1022. The action of the sliding hammer 1024 thereby provides a strong pulling force upon the item engaged by the jaws 1010.Each of the jaws 1010 is provided with a jaw arm 1012 that can be used to open the jaws 1010. In this example, the jaws 1010 can be opened by squeezing both arms 1012 towards the shaft 1020. The jaws 1010 may be coupled to one another with a biasing element (e.g., a spring), which acts to urge the jaws closed so as to provide a secure engagement with the item in question.

[0220] The jaws 1010 are coupled to the shaft 1020 via a pair of pivots 1016 at an upper shaft portion 1026. The pivot 1016 for each jaw 1010 is located on an opposing side of the shaft 1020 relative to said jaw. In the example shown in Figure 21, an upper jaw is coupled to the upper shaft portion 1026 via a pivot 1016 located below the shaft 1020. Likewise, a lower jaw is coupled to the upper shaft portion 1026 via a pivot 1016 located below the shaft 1020. This opposing pivoting may be achieved by the upper shaft portion 1026 having a T-shaped end, and by the arms 1012 each having a flared or protruding portion such that they extend across the shaft 1020. As a consequence of the opposing pivots 1016, when the sliding hammer 1024 is used to apply force, the jaws 1010 may be forced together rather than being pulled apart. As such, the slap hammer 1000 of the present invention may be less likely to slip or to become decoupled from an item being engaged (e.g., a pin or a peg) during use.

[0221] Figure 22 shows a bone collar remover 1100 in an assembled form (upper image) and zoomed in, disassembled form (lower images). During knee replacement surgery, some tools and apparatuses that are used for drilling into the bones of the patient may leave a collar; a raised portion around the edge of the drilled hole. It may be desirable to remove this collar so that the entrance to the hole is flush with the surrounding bone surface, but doing so can cause damage to the hole (particularly in elderly or osteoporotic patients). As discussed above, the hole and the posterior cut may diverge at 1.5 degrees. The hole is critical for secure fixation of the femoral component. If a tooth of a bone collar remover catches on the edge of the hole, the device may rotate about this point, thereby damaging the hole.

[0222] The bone collar remover 1100 comprises a handle 1102 and a shaft 1110. The handle 1102 may be concentric with the shaft 1110. A cutting portion 1120 is located part way along the shaft 1110. During use, the end of the shaft 1110 is inserted into the drilledhole such that the cutting portion engages with the bone collar. The handle 1102 is then twisted, so as to cut and remove the bone collar.

[0223] The cutting portion comprises a plurality of teeth 1122 located around the shaft 1110. In this example, four teeth are provided, but this may vary. The teeth 1122 may be sharper than teeth of existing apparatuses. The teeth 1122 may have a cutting angle of approximately 15 degrees (e.g., between 10 degrees and 20 degrees); compared to previous apparatuses that have cutting teeth angled at approximately 30 degrees. The cutting angle of previous apparatuses can cause the teeth to dig in or ‘catch’.

[0224] Alongside the teeth 1122 there is provided an end stop 1124, configured to prevent the cutting teeth 1122 from cutting below a certain depth. The end stop 1124 comprises a plurality of raised portions located next to each of the cutting teeth 1122; when the end stop 1124 abuts the surface of the bone surrounding the hole / collar, the cutting teeth 1122 will be prevented from cutting any deeper. The tops of the raised portions may be at the same height as the leading edge of the cutting teeth 1122, for example, such that the cutting teeth 1122 can only cut to the level of the surrounding bone surface. Alternatively, the tops of the raised portions may be slightly below or above (e.g., 1 mm or 2 mm) the leading edge of the cutting teeth 1122, such that cutting teeth 1122 can cut more or less deeply respectively. The sharper cutting teeth 1122 and / or the end stop 1124 may mean that the bone collar remover 1100 is less likely to catch, thereby reducing the likelihood of damage to the drilled hole as discussed above.

[0225] The shaft 1110 may be formed from a plurality of separate components, rather than as a single solid member. In particular, an end portion 1112 of the shaft may be detachable. In the example of Figure 21, the end portion 1112 is provided as a cap-like component, configured to concentrically couple with an inner shaft portion 1114. The skilled person will understand however that any suitable means for detachably coupling a shaft may be used. For example, the components of the shaft may have threaded portions (e.g., threaded pins and / or holes) for screwing said components together. The end portion 1112 may be fixedly coupled to the shaft (e.g., using glue or pins) once the components are assembled.

[0226] By manufacturing the shaft 1110 in a plurality of parts, it may be easier to manufacture, prepare or maintain the cutting portion 1120. In the disassembled state shown in thelower images, with the end portion 1112 removed, it may be easier to machine or sharpen the cutting teeth 1122. Thus, the bone collar remover 1100 may be provided with sharper cutting means than conventional devices. The length of the shaft 1100 may also be longer than conventional devices. E.g., the end portion 1112 may be long enough that it is nearly able to reach the bottom of a drilled hole when in use. Providing deeper engagement with the hole may reduce the probability that the bone collar remover 1100 will catch the hole as it is used, thereby reducing the likelihood of damage.

[0227] Figure 23 shows a tibial component adjustor 1200. During placement of a tibial replacement component (e.g., a component to replace the resected portion shown in Figure 11) it may be necessary to reposition the tibial component prior to fixing it into position. Typically, this may be done using a simple plastic block (or other chisel-like device) and a hammer. The plastic block may be a plastic handle of a cement removing chisel, which is inefficient and prone to slipping. Thus, existing adjustment tools may cause the component to be poorly positioned if they were to slip.

[0228] The tibial component adjustor 1200 comprises a handle 1202 and a shaft 1204. At an end of the shaft opposite to the handle 1202, there is provided an engagement portion 1206. The engagement portion 1206 of this example comprises a forked protrusion, which would engage with a corresponding notch located on the tibial component. However, it will be understood that the exact configuration of the engagement portion 1206 and the corresponding portion of the tibial component may vary. By providing the engagement portion 1206, the tibial component adjustor 1200 may be easier to use - it may be more controllably engaged with the tibial component, thereby reducing the likelihood of slipping. The engagement portion 1206 may be formed of hardened plastic. This may be a resin-based polymer, such as Pomalux ®. Preferably, the engagement portion 1206 will be softer than the tibial component of the implant (which may be made of cobalt and / or chrome) so that the adjustor 1200 does not damage or scratch the surface of the implant.

[0229] Although specific examples have been described, the skilled person will appreciate that variations are possible, within the scope of the invention, which should be determined with reference to the accompanying claims.

Claims

CLAIMS1. A clamp for use in knee replacement surgery, the clamp being operable to engage with a femoral sizing spoon and a tibial resection guide so as to enable positioning of the tibial resection guide relative to a tibia of a patient, the clamp comprising:an adjustable locking element for insertion in use between the femoral sizing spoon and the tibial resection guide;a body comprising an upper portion and a lower portion, the upper portion being movably coupled to the locking element;a retaining member, the retaining member being coupled to the upper portion of the body;a locking mechanism, wherein the locking mechanism is movable between: an unlocked position, wherein the clamp is free to move relative to the femoral sizing spoon and the tibial resection guide; anda locked position, wherein the tibial resection guide is clamped between the lower portion of the body and a lower surface of the locking element, and the femoral sizing spoon is clamped between the retaining member and an upper surface of the locking element; andan adjustment means, wherein the adjustment means is configured to enable a thickness of the locking element between the lower surface and the upper surface to be varied.

2. The clamp of claim 1, wherein:the locking element comprises a first portion comprising the upper surface and a second portion comprising the lower surface, the first portion and second portion of the locking element being movably coupled to one another; andthe adjustment means comprising a first adjustment component, the first adjustment component comprising a threaded screw portion located between the first portion and the second portion of the locking element.

3. The clamp of claim 1 or claim 2, wherein the adjustment means is further configured to enable a distance between the retaining member and the upper portion of the body to be varied, the variation in the distance between the retaining member and the upper portion of the body being equal to the variation in the thickness of the locking element between the lower surface and the upper surface.

4. The clamp of claim 3 as it depends upon claim 2, wherein the adjustment means further comprises a second adjustment portion, the second adjustment portion comprising a threaded screw portion, the threaded screw portion of the second adjustment portion having a pitch equal to that of the threaded screw portion of the first adjustment portion.

5. The clamp of claim 4, wherein the pitch of the threaded screw portions is between 2 mm and 4 mm, and optionally wherein the pitch of the threaded screw portions is 3 mm.

6. The clamp of any of claims 2 to 5, wherein the second portion of the locking element and the upper portion of the body comprise a first rotation prevention means, such that the second portion of the locking element is prevented from rotating relative to the upper portion of the body.

7. The clamp of any of claims 4 to 6, wherein the first portion of the locking element and the retaining member comprise a second rotation prevention means, such that the retaining member is prevented from rotating relative to the first portion of the locking element.

8. The clamp of any preceding claim, wherein the adjustment means comprises a locking element securing mechanism, the securing mechanism being configured so that, when engaged, the thickness of the locking element is fixed.

9. The clamp of claim 8, wherein the locking engagement securing mechanism comprises a protrusion and at least one notch, wherein one of the said protrusion or notch is located on a surface of the locking element, the protrusion being engageable with the notch so as to prevent movement of the locking element relative to the body.

10. The clamp of any preceding claim, wherein the retaining member comprises a first portion and a second portion, and the locking element comprises a hole passing through the upper surface, wherein the first portion and the second portion of the retaining member are detachably couplable such that:the first portion of the retaining member can be located on a first side of the upper surface of the locking element;the second portion of the retaining member can be located on a second side of the upper surface of the locking element; andthe first portion and the second portion of the retaining member may be coupled to one another through the hole of the upper surface of the locking element, such that the first portion and second portion of the retaining member are retained on either side of the upper surface of the locking element.

11. The clamp of any preceding claim, wherein the upper portion of the body comprises a first portion and a second portion, and the locking element comprises a slot for receiving the upper portion of the body, wherein the first portion and the second portion of the upper portion of the body are detachably couplable such that:the first portion of the upper portion of the body can be received within the slot; andthe second portion of the upper portion of the body can be coupled to the first portion of the upper portion of the body, such that the upper portion of the body are prevented from being removed from slot of the locking element.

12. A kit of parts for positioning of a tibial resection guide relative to a tibia of a patient during knee replacement surgery, the kit comprising:a clamp according to any of claims 1 to 11;a tibial resection guide configured to be received between the upper portion of the body and a lower surface of the locking element of the clamp; andat least one femoral sizing spoon configured to be received between the upper surface of the locking element and the retaining member of the clamp, and wherein the femoral sizing spoon comprises:a head configured to be inserted between the femoral and tibial condyles of the patient’s knee;a shaft comprising a hole therethrough, the hole being configured to receive the retaining member of the clamp.

13. A femoral drill guide for guiding a drill during a knee replacement surgery, the femoral drill guide comprising:a body comprising a drill guide hole, the drill guide hole being configured to guide the drill when in use;a foot configured to be placed upon a portion of a tibial condyle, thereby positioning the drill guide hole relative to a femoral condyle;wherein the body comprises a window that is configured such that a user can view a surface of the femoral condyle through the body when in use.

14. The femoral drill guide of claim 13, wherein the foot comprises a protrusion located upon an upper surface of the foot, the protrusion being configured to slide into a groove made in the femoral condyle when in use.

15. A cutting block for guiding the cutting of a groove in a femoral condyle during a knee replacement surgery, the cutting block comprising:a body comprising a lower surface and a side surface for positioning respectively against a horizontal cut and a vertical cut made in a tibial condyle when in use;at least one channel in an upper surface of the body, the at least one channel being configured such that when a cutting instrument is disposed therein during use, the cutting instrument produces a groove in a surface of the femoral condyle.

16. The cutting block of claim 15, wherein:i) the cutting block comprises a single channel in the upper surface of the body, the channel being angled perpendicularly to the upper surface of the body; orii) the cutting block comprises a pair of channels in the upper surface of the body, the pair of channels being angled such that when the cutting instrument is disposed therein during use, the cutting instrument produces an inverted V-shaped groove in the surface of the femoral condyle.

17. A vertical wall rasp for removing bone from a vertical tibial cut made during a knee replacement surgery, the vertical wall rasp comprising a:a head comprising a cutting surface; anda handle, the handle being coupled to the head;wherein a rear surface of the head opposite the cutting surface is conformally shaped so as to fit around a femoral condyle during use.

18. The vertical wall rasp of claim 17, wherein the cutting surface is at least partially curved.

19. The vertical wall rasp of claim 17 or 18, wherein the handle is detachably coupled to either a first end of the head or to a second end of the head via a common attachment means.

20. A femoral sizing spoon for use during knee replacement surgery, the femoral sizing spoon comprising;a handle, the handle having a hole for receiving a retaining member of a clamp; anda head for inserting into an inter-femur / tibia space in use, wherein the head comprises a protrusion located centrally along at least part of the length of the head.

21. The femoral sizing spoon of claim 20, wherein the width of the head about the protrusion is no more than 5 mm across.

22. The femoral sizing spoon of claim 20 or claim 21, wherein the head has a cross-section wherein edge portions of the head are less thick than central portions of the head.

23. A tibial cutting guide for enabling cutting of a tibial condyle, the tibial cutting guide comprising:a generally L-shaped body, the L-shaped body having a vertical slot for enabling a vertical cut of the tibial condyle and a horizontal slot for enabling a horizontal cut of the tibial condyle; anda locking mechanism, the locking mechanism being configured so that the tibial cutting guide can be detachably and securely coupled to a tibial guide during use.

24. The tibial cutting guide of claim 23, whether the L-shaped body comprises a hole therethrough, the hole being provided at a corner where the vertical slot and horizontal slot converge, the hole being configured to receive a pin.

25. A tibial cutting guide kit comprising:the tibial cutting guide of claim 24; anda pin, the pin being configured to be received by the hole of the tibial cutting guide and having plurality of markings at a distal end, the plurality of markings indicating a level of insertion of the pin into the hole of the tibial cutting guide.

26. A keel rasp for removing bone from a trench cut into a surface of the tibia during knee replacement surgery, the keel rasp comprising:a handle; anda cutting end, the cutting end comprising a curved portion across which a cutting surface is provided.

27. A pin for use in knee replacement surgery for coupling a tibial resection guide to a tibia, the pin comprising:a shaft; anda head, the head being coupled to the shaft at one end and being offset from a central axis running along the length of the shaft.

28. The pin of claim 27, wherein a lower surface of the head comprises sloped edges.

29. An anti-impingement guide for use in the preparation of a femoral condyle during knee replacement body, the anti-impingement guide comprising:a body;a peg, the peg being configured to be received within a hole drilled into a surface of the femoral condyle; anda posterior extension portion, the posterior extension portion having a slot at a rear end, the posterior extension portion being configured to be placed between a femur and tibia when in use such that a chisel-like instrument can be received in the slot for removing bone at a posterior surface of the femoral condyle; andan anterior mill pin configured to receive a milling device when in use for removing bone at an anterior surface of the femoral condyle;wherein the posterior extension portion is provided at an angle of 1.5 degrees downwards relative to the peg.

30. The anti-impingement guide of claim 29, wherein the peg has a flattened lower surface.

31. The anti-impingement guide of claim 29 or claim 30, wherein anterior mill pin has a length of at least 15 mm.

32. A slap hammer for use in knee replacement surgery, the slap hammer comprising:a pair of jaws; anda shaft comprising a sliding hammer;wherein a first jaw of the pair of jaws is located on a first side of the shaft and is coupled to the shaft via a pivot located on a second side of the shaft, and wherein a second jaw of the pair of jaws is located on the second side of the shaft and is coupled to the shaft via a pivot located on the first side of the shaft.

33. A bone collar remover for use in knee replacement surgery, the bone collar remover comprising:a handle;a shaft coupled to the handle, the shaft comprising a cutting portion comprising:a plurality of cutting teeth; andan end stop configured to prevent the cutting teeth from cutting below a desired depth relative to a surrounding surface.

34. The bone collar remover of claim 33, wherein the shaft is made of at least two separate components that are detachably coupled to one another.

35. A tibial component adjustor for use in knee replacement surgery, the tibial component adjustor comprising:a handle; anda shaft coupled to the handle, the shaft having an engagement portion at an end opposite to the handle, the engagement portion configured to engage with a corresponding portion located on a tibial component.

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