AU2023222926A1 - Veterinary surgical jig and corresponding bone plate - Google Patents

Abstract

A surgical jig for use in a tibial plateau levelling osteotomy in which a bone plate is used post osteotomy for securing plateau segments of separated tibial bone, the jig 5 comprising: a blade guide comprising a guide body having a concave upper guide surface; a leg coupled to the blade guide and comprising an elongate leg body extending away from the blade guide; and a head comprising a head body having one or more side walls, at least one of the one or more side walls comprising an outwardly curved guide bearing surface having a curvature corresponding to a curvature of the 10 upper guide surface; wherein one or more drill holes are provided on each of the head and leg and wherein, in use, the head is selectively positionable on the blade guide with the guide bearing surface located on the concave upper guide face for facilitating drilling of plate fixing holes. 15 (Fig. 2) 12 82 10 11a to 11 g 11h 14 Figure 2 23 10 12 14 Figure 3

Description

82 10

11a to 11 g

11h 14

Figure 2

23 10

12 14

Figure 3

VETERINARY SURGICAL JIG AND CORRESPONDING BONE PLATE

Technical Field

This disclosure relates to a veterinary surgical jig and more particularly to a jig and method for performing a tibial plateau levelling bone osteotomy in which a plate is used post osteotomy for securing portions of separated tibial bone.

Background

The tibial plateau osteotomy (TPLO) was proposed by Barlcay Slocum in the 1980s. Slocum realised that the cranial cruciate deficient stifle has a tendency to subluxate at the normal standing angle, during weightbearing. The Slocum TPLO reduces the tibial plateau angle (TPA) to (ideally) 6 degrees post operatively.

Various jigs have been proposed to assist with aspects of the TPLO procedure, including to prevent varus or valgus mal-position post operatively. However, such jigs can be complicated to use and typically only show where the osteotomy will occur.

It would be advantageous if there was provided an improved jig that could prevent varus/valgus angulation of the osteotomy. It would also be advantageous if the jig additionally or alternatively acted as a guide for locating screw holes for plate positioning. It would also be advantageous if the jig additionally or alternatively acted as a guide for guiding a saw blade used to perform the osteotomy.

Summary

In a first aspect, embodiments are disclosed of a surgical jig for use in a tibial plateau levelling osteotomy in which a bone plate is used post osteotomy for securing plateau segments of separated tibial bone, the jig comprising: a blade guide comprising a guide body having a concave upper guide surface; a leg coupled to the blade guide and comprising an elongate leg body extending away from the blade guide; and a head comprising a head body having one or more side walls, at least one of the one or more side walls comprising an outwardly curved guide bearing surface having a curvature corresponding to a curvature of the upper guide surface; wherein one or more drill holes are provided on each of the head and leg and wherein, in use, the head is selectively positionable on the blade guide with the outwardly curved guide bearing surface located on the concave upper guide surface for facilitating drilling of plate fixing holes.

In a second aspect there is provided a method for performing a tibial plateau levelling osteotomy using the surgical jig of the first aspect, the method including the steps of: a) determining a desired post operative tibial plateau angle; b) selectively positioning the head on the blade guide bearing to achieve the desired post operative tibial plateau angle; c) locating the jig over the tibial plateau; d) drilling plate screw holes in the underlying tibial plateau through each of the drill holes; e) removing the head from the jig; and f) making the osteotomy with the blade guide used for guiding the cutting blade.

In another aspect there is provided an osteotomy plate for use with the jig as described in accordance with the first aspect, wherein the plate comprises a body having a head portion and a leg portion with through holes in corresponding locations to the screw holes in the jig when the head and leg of the jig are in a predefined orientation.

In yet another aspect there is provided a surgical jig for use in a tibial plateau levelling osteotomy in which a bone plate is used post osteotomy for securing plateau segments of separated tibial bone, the jig comprising: a blade guide comprising a guide body having a concave upper guide surface; a leg coupled to the blade guide and comprising an elongate leg body extending away from the blade guide; and a head configured to detachably couple to the blade guide; and wherein one or more drill holes are provided on each of the head and leg and wherein, in use, the head is selectively positionable on the blade guide for facilitating drilling of plate fixing holes and wherein the head is thereafter removable to allow a radial blade saw to be positioned on the blade guide for carrying out the osteotomy.

In a still further aspect there is provided an osteotomy kit for use in a tibial plateau levelling osteotomy in which a bone plate is used post osteotomy for securing plateau segments of separated tibial bone, the kit comprising: a saw blade used for the osteotomy; and surgical jig, the jig comprising: a head comprising a head body having one or more side walls, at least one of the one or more side walls comprising an outwardly curved guide bearing surface; a blade guide comprising a guide body having a concave upper guide surface, a curvature of at least a portion of the concave upper guide surface corresponding to a curvature of the sawblade; and a leg coupled to the blade guide and comprising an elongate leg body extending away from the blade guide; and wherein one or more drill holes are provided on each of the head and leg and wherein, in use, the head is selectively positionable on the blade guide with the guide bearing surface seated on the concave upper guide surface for facilitating drilling of plate fixing holes and wherein the head is thereafter removable for locating a blade over the blade guide for carrying out the osteotomy.

In another aspect there is provided an osteotomy kit for use in a tibial plateau levelling osteotomy in which a bone plate is used post osteotomy for securing plateau segments of separated tibial bone, the kit comprising: a surgical jig comprising: a head comprising a head body having one or more side walls, at least one of the one or more side walls comprising an outwardly curved guide bearing surface; a blade guide comprising a guide body having a concave upper guide surface, a curvature of at least a portion of the concave upper guide face corresponding to a curvature of the sawblade; and a leg coupled to the blade guide and comprising an elongate leg body extending away from the blade guide; and a bone plate; and wherein through holes are provided on each of the jig and bone plate and wherein, when the head of the jig is mounted to the blade guide in a predefined alignment position, the relative location of through holes in the jig correspond to the relative location of through holes in the bone plate and wherein the through holes in the jig are used for drilling screw holes in the tibial bone and the through holes in the plate are used for receiving bone screws that screw into the screw holes for fixing the plate to the separated tibial bone segments.

In a still further aspect there is provided a surgical jig for use in a tibial plateau levelling osteotomy in which a bone plate is used post osteotomy for securing plateau segments of separated tibial bone, the jig comprising: a leg comprising an elongate blade guide disposed at an upper end thereof and an elongate body having a bone facing face and an opposite face, the leg extending from the upper end to a lower end, and wherein an upper surface of the elongate blade guide has a concave longitudinal profile configured to receive a radial saw blade for carrying out the osteotomy; and a head having a bone facing face and an opposite face, the head comprising a circumferential wall connecting the bone facing and opposite faces and wherein a portion of the circumferential wall has a convex profile complimentary to the concave longitudinal profile of the upper surface of the elongate blade guide; wherein one or more drill holes on each of the head and leg extend between the respective bone and opposite faces and wherein, in use, the head is selectively positioned on the blade guide with the portion of the circumferential wall located on the concave upper surface of the blade guide for facilitating drilling of plate fixing holes.

Other aspects, features, and advantages will become apparent from the following detailed description when taken in conjunction with the accompanying drawings, which are a part of this disclosure and which illustrate, by way of example, principles of the inventions disclosed.

Description of the Figures

The accompanying drawings facilitate an understanding of the various embodiments:

Figures 1a to 1c illustrate a typical tibial plateau levelling osteotomy (TPLO) procedure;

Figure 2 is a front view of an assembled right side surgical jig, in accordance with an embodiment;

Figure 3 is an isometric view of the assembled surgical jig of Figure 2 in a second configuration;

Figures 4 is an isometric view of the jig head shown in Figure 2;

Figures 5 through 7 are front, isometric and side views respectively of the leg of Figure 2;

Figure 8 is an isometric view of a plate in accordance with an embodiment;

Figure 9 is a side view of the plate of Figure 8;

Figure 10 is a front view of the jig of Figure 2 in the zero-degree alignment position; Figure 11 shows the jig of Figure 2 placed over a tibial bone;

Figure 12a shows the jig of Figure 2 with the head removed ready for performing osteotomy;

Figure 12b is an illustrative example of a radial saw blade used to perform the osteotomy;

Figure 13 shows the plate of Figure 8 attached to the proximal segment of tibial bone ready for rotation;

Figures 14a and 14b show the plate post rotation ready for securing to the distal tibial bone segment;

Figure 15 is a front view of a left side jig in accordance with an embodiment;

Figure 16 is an exploded front view of a right side jig in accordance with an alternative embodiment;

Figure 17 is an isometric view of the jig shown in Figure 16;

Figure 18 is an assembled front view of the jig shown in Figure 16;

Figures 19a to 19c are various engineering views of the Figure 16 jig head; and

Figure 20 is a side view of the Figure 16 jig leg.

Detailed Description

Embodiments described herein relate to surgical jig assemblies for use by veterinarians in performing a tibial plateau levelling osteotomy (TPLO). More particularly, the jig assembly is configured for use as both an osteotomy cutting guide, as well as a tool for achieving a predetermined post-operative tibial plateau angle (TPA). Embodiments also relate to a corresponding bone plate used post osteotomy for securing plateau segments of separated tibial bone.

Before describing operation of the jig assemblies, a representative example of a TPLO procedure will first be described with reference to Figures 1a through 1c. In Figure 1a, a TPA 6 between a plane 2 defined by the tibial plateau 4 and a horizontal reference plane 5 is illustrated. As stated in the preamble, it can be beneficial to rotate

.5 the plane 2 of the tibial plateau 4 to reduce the angle between the tibial plateau and the reference plane 5. This is achieved by making a radial cut 7 in a proximal portion 6 of the tibia 7 and rotating the excised portion 8 such that the angle between the tibial plateau 4 and the horizontal reference plane 5 is lowered, ideally to approximately 6 degrees.

With reference to Figures 2 and 3 there is shown a jig assembly 10 (hereafter jig 10) in accordance with a first aspect of the invention. The jig 10 consists of two parts, namely a jig head 12 and jig leg 14. It is noted that the jig 10 shown in Figures 2 and 3 is a "right side" jig and accordingly the following description will be described in the context of performing a right side osteotomy. It will be understood that the same procedure is applicable for performing a left side osteotomy using a "left side" jig as shown in Figure 15 (which is a mirror of the right side jig of Figure 2). The parts of the jig 10 may be formed from stainless steel, plastic, or any other material suitable for use in veterinary surgery.

As is particularly evident from Figure 4, the head 12 comprises a body (in this case have a generally triangular shape) having an inner bone facing face 16 and an opposite outer face 18. According to the illustrated embodiments, a circumferential wall 20 separates the faces 16, 18, with a plurality of drill holes 22 extending therebetween. In this example embodiment a trio of drill holes 22 are provided in a triangular arrangement adjacent corresponding rounded edges of the wall 20. Cylindrical drill guides 23 extend from each hole 22 away from the outer face 18.

A bottom portion 21 of the wall 20 comprises an arcuate guide bearing surface 24. More particularly, the guide bearing surface 24 has a convex profile as it extends from a first end 24a to a second end 24b of the bottom portion 21 (see particularly Figure 4). The bottom portion 21 also comprises one or more threaded apertures 26 for receiving securing grub screws, the provision of which will become evident in subsequent paragraphs.

With further reference to Figures 5 through 7, a blade guide 30 is disposed at an upper end of the leg 14. The blade guide comprises an elongate guide body 31 preferably having an arcuate longitudinal profile. The guide body 31 has an upper guide surface 32 configured to receive and guide a radial saw blade 37 (also referred to as a TPLO saw blade, such as depicted in Figure 12b) that is used to perform the osteotomy. In this regard, the upper guide surface 32 has a concave profile as it extends longitudinally from a first end 32a to a second end 32b. Preferably, the upper guide surface 32 has a curvature corresponding to blade of the radial saw blade (e.g., the internal radius of the upper guide surface may correspond to the outer radius of the radial saw blade), thereby allowing the saw blade 37 to be stabilized and guided as it oscillates for cutting the bone (See particularly Figure 12a). A centrally located adjustment slot 33 extends longitudinally along the upper guide surface 32 and through the guide body 31 to a lower surface for receiving grub screws used to secure the head 12 to the leg 14. It will be understood that jigs having guide bodies of varying internal radii can be provided depending on the desired TPLO saw blade size. It will also be understood that the upper guide surface 32 may take on various curved or arcuate shapes depending on the blade being used.

The jig leg 14 further comprises an elongate leg body 36 which extends away from a lower face 35 of the blade guide 30 adjacent a bone facing edge 32c of the upper guide surface 32. The elongate leg body 36 comprises an inner bone facing leg face 38 and an opposite outer leg face 40. Both the inner and outer leg faces 38, 40 lie in a plane substantially orthogonal to the upper guide surface 32 of the blade guide 30. A plurality of drill holes 42 (extending between the faces 38, 40) are disposed along the length of the leg 14. As for the head, cylindrical drill guides 44 extend from each hole 42 away from the outer face 40.

Also evident from the figures are one or more threaded apertures 45 extending through the faces 38, 40 of the leg body 36. The apertures 45 are configured to receive grub screws that can be adjusted (i.e., screwed into and out of the apertures 45) until the bone facing faces of the jig 10 are generally perpendicular to the tibia.

As described above, the head 12 is slidably movable with respect to the leg 14 for achieving a range of a range of post operative TPA states. To this end, and as is particularly evident from Figure 2, the arcuate guide bearing surface 24 of the head 12 has a radius of curvature corresponding to that of the upper guide surface 32. Outer facing surfaces of the head 12 and leg 14 include visual markers 11a to 11h for indicating a particular rotational alignment state. More particularly, the markers 11 are used to select a degree by which the the plane 2 of the tibial plateau 4 will be rotated using the configured jig 10. According to the illustrated example, markers 11a to 11g on the head 12 indicate the degree of rotation (increasing in degrees from 0 to 30, left to right) when aligned with the single marker 11h on the leg 14. It will be understood that other marking conventions and arrangements could equally be implemented to indicate the post-operative angle of rotation. For example, the markers 11a to 11g could be disposed on the leg 14 while a single maker 11h could be disposed on the head 12.

Turning to Figures 8 and 9 there is shown a "right side" osteotomy plate 60 for securing plateau segments of separated tibial bone (it will be understood that the left side plate is simply a mirror of the right side plate). The plate 60 has a body 61 comprising a head 62 and leg 64. The plate body 61 is made from a suitable implant quality material, such as stainless steel or sterile titanium alloy. Like the jig 10, the plate 60 has holes 22a, 42a extending between inner and outer faces 66, 68 of the head 62 and leg 64. The relative location of holes 22a, 24a corresponds to that of the holes 22, 24 in the jig 10 when configured in the 0-degree rotation position (as shown in Figure 10). A rotation pin hole 63 extends diagonally into the outer face 68 for receiving a rotation pin, as will be described in subsequent paragraphs. One or more threaded apertures 65 extend through the faces 66, 68 for receiving grub screws that can be adjusted to correct for patellar luxation.

Prior to performing an osteotomy using a jig 10 as described herein, a scan is taken of the patient's tibia to determine a pre-operative medial lateral angle (i.e., the pre-operative TPA 6, as previously described with reference to Figure 1).

The head 12 of the jig 10 is suitably positioned on the leg (i.e., with the concave upper guide surface 32 located/seated on the guide bearing surface 24) to select a degree of rotation that will result in a desired post-operative TPA 6 (preferably 6 degrees) and subsequently secured in placed using the grub screws. For example, if the pre-operative TPA is 30 degrees, then the head will be rotated clockwise by 24 degrees to the corresponding marker (i.e., from the 0-degree position). It will be understood that the positioning and securing of the head 12 to leg 14 may occur either before or during placement of the jig 10 against the tibia 17.

The jig 10 is then placed against the proximal tibia as shown in Figure 11. A drill is then used to drill screw holes in the proximal segment of the tibial bone through the drill holes 22. Distal screw holes are drilled through the holes 42 in the leg 14. Bone screws are then screwed into the distal screw holes before the head 12 is removed from the jig 10 (by unscrewing the jig screws). The resultant jig configuration, with the saw blade rested thereon, is shown in Figure 12a.

Once the head 12 has been removed from the jig 10, osteotomy is performed using a corresponding TPLO radial blade 37. The jig 10 is then removed by removing the bone screws.

As shown in Figure 13, the bone plate 60 is placed on the proximal segment of the tibia 17 and secured thereto using locking screws (i.e., screwed through holes 22a into the previously drilled screw holes). A 3.5mm rotation pin (e.g., K wire) is then placed through the pin hole 63 and the plate 60 rotated until screw holes 42a in the distal segment align with the screw holes previously drilled into the distal segment of the bone. This is best shown in Figures 14a and 14b. If patellar luxation is to be corrected, grub screws (i.e., screwed into the threaded holes 65) can be adjusted to lateralise tibial tuberosity. Bones screws are subsequently used to secure the distal segment of the plate 60 to the distal segment bone. The final step of the procedure is to remove the pin and perform a standard soft tissue closure.

An alternative embodiment of a jig 10' is shown in Figures 16 to 20. Again, the jig 10' shown in the Figures is a "right side" jig, with the left side jig being a mirror image thereof. Like elements between the two embodiments are indicated by an apostrophe next to the relevant numeral in Figures 16 to 20.

As is evident from the views shown in Figures 16 to 18 (with relevant hidden detail shown in dotted outline), the main difference between the two embodiments is the way in which the jig head 12' and jig leg 14' are coupled together. Notably, according to the alternative embodiment, the convex guide bearing surface 24' of the jig head 12' comprises a longitudinally extending slide rail 80 which projects outwardly from and along the bearing surface 24' (see particularly Figures 19a to 19c). A corresponding longitudinally extending slide rail receiving channel 82 projects inwardly from and along the concave upper guide surface 32' of the jig leg 14' to permit sliding movement between the slide rail 80 and said slide rail receiving channel 82 (and to thereby permit the jig head 12' and jig leg 14' to be slidingly interconnected). The slide rail 80 and receiving channel 82 both follow the curvature of the respective corresponding surfaces 24', 32'. In an embodiment, upper surface portions on either side of the slide rail receiving channel 82 may arc downwardly as they extend away from the channel edge to their respective outer edge (i.e., either bone facing or opposite edge).

In an embodiment, the slide rail 80 and slide rail receiving channel 82 have corresponding cross-sectional profiles that prevent the two elements from being separated once the slide rail 80 has been slidingly received in the receiving channel 82. According to the illustrated embodiment, the rail 80 and channel 82 have circular cross sectional profiles, however other cross-sectional profiles may be chosen depending on the desired implementation. For example, the cross-sectional profiles may include various trapezoidal shapes (e.g., such as for dovetail slides). An advantage of this embodiment is that the need for securing grub screws is obviated and thus assembly of the jig 10' is simplified.

It will be understood that in an alternative embodiment to that depicted in Figures 16 to 20, the rail 80 may instead be disposed on the upper guide surface of the jig leg with the receiving channel disposed on the bearing surface of the jig head.

It will also be understood that the process for performing an osteotomy using the jig 10' is much the same as previously described for jig 10, however once the jig head 12' and leg 14' have been interconnected there is no need insertion or removal of grub screws for preventing or facilitating separation of the two elements (rather the elements are simply slid into or out of engagement with one another).

Various advantages arise through use of one or more embodiments of the invention, including:

- a jig that results in a predictable location of the osteotomy and plate prior to making a cut; - a jig than can prevent varus/valgus angulation of the osteotomy; - a jig that allows for perpendicular osteotomy using an outer diameter osteotomy guide and grub screws that can be adjusted to allow a better "fit" against the bone thereby keeping the osteotomy perpendicular irrespective of the patient anatomical variation; - a plate having grubs screws allowing for medialisation or lateralisation of the distal segments; - a jig that results in a perpendicular osteotomy thus allowing ease of rotation of the proximal segment.

In the foregoing description of certain embodiments, specific terminology has been resorted to for the sake of clarity. However, the disclosure is not intended to be limited to the specific terms so selected, and it is to be understood that each specific term includes other technical equivalents which operate in a similar manner to accomplish a similar technical purpose. Terms such as "upper" and "lower", "above" and "below" and the like are used as words of convenience to provide reference points and are not to be construed as limiting terms.

In this specification, the word "comprising" is to be understood in its "open" sense, that is, in the sense of "including", and thus not limited to its "closed" sense, that is the sense of "consisting only of". A corresponding meaning is to be attributed to the corresponding words "comprise", "comprised" and "comprises" where they appear.

The preceding description is provided in relation to several embodiments which may share common characteristics and features. It is to be understood that one or more features of any one embodiment may be combinable with one or more features of the other embodiments. In addition, any single feature or combination of features in any of the embodiments may constitute additional embodiments.

In addition, the foregoing describes only some embodiments of the inventions, and alterations, modifications, additions and/or changes can be made thereto without departing from the scope and spirit of the disclosed embodiments, the embodiments being illustrative and not restrictive.

Furthermore, the inventions have described in connection with what are presently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not to be limited to the disclosed embodiments, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the inventions. Also, the various embodiments described above may be implemented in conjunction with other embodiments, e.g., aspects of one embodiment may be combined with aspects of another embodiment to realize yet other embodiments. Further, each independent feature or component of any given assembly may constitute an additional embodiment.

Claims (35)

1. A surgical jig for use in a tibial plateau levelling osteotomy in which a bone plate is used post osteotomy for securing plateau segments of separated tibial bone, the jig comprising: a blade guide comprising a guide body having a concave upper guide surface; a leg coupled to the blade guide and comprising an elongate leg body extending away from the blade guide; and a head comprising a head body having one or more side walls, at least one of the one or more side walls comprising an outwardly curved guide bearing surface having a curvature corresponding to a curvature of the upper guide surface; wherein one or more drill holes are provided on each of the head and leg and wherein, in use, the head is selectively positionable on the blade guide with the outwardly curved guide bearing surface located on the concave upper guide surface for facilitating drilling of plate fixing holes.

2. A surgical jig in accordance with claim 1, wherein the head has an inner bone facing head face and an opposite outer head face with the one or more side walls separating said faces and wherein the drill holes in the head extend between the inner and outer head faces.

3. A surgical jig in accordance with claim 2, wherein the outwardly curved guide bearing surface slopes inwardly as it extends from the inner head face to the outer head face, thereby causing the inner head face to line in a plane that is offset with respect to a longitudinal plane of the leg, when the head is located on the upper guide surface.

4. A surgical jig in accordance with claim 2, wherein a thickness of the head body narrows at it extends away from the guide bearing surface, thereby causing the inner head face to line a plane that is offset with respect to a longitudinal plane of the leg, when the head is located on the upper guide surface.

5. A surgical jig in accordance with any one of claims 2 to 4, wherein the elongate leg body comprises an inner bone facing leg face and an opposite outer leg face, the inner and outer leg faces lying in a plane substantially orthogonal to the upper guide face of the blade guide and wherein the drill holes extend between the inner and outer leg faces.

6. A surgical jig in accordance with any one of claims 2 to 5, wherein the head is slidably coupled to the blade guide.

7. A surgical jig in accordance with claim 6, wherein the head is slidable longitudinally along the upper guide face for achieving a range of rotational alignment positions.

8. A surgical jig in accordance with claim 7, wherein, when in a first rotational alignment position, the relative location of drill holes in the head and leg correspond to the relative location of through holes in the bone plate that are used for receiving fixing and/or compression screws.

9. A surgical jig in accordance with claim 8, wherein markers on the head and an outer edge of the guide body are used to indicate one or more specific alignment positions within the range of rotational alignment positions.

10. A surgical jig in accordance with claim 9, wherein the markers are used to indicate jig alignments for achieving a specific post operative tibial plateau angle.

11. A surgical jig in accordance with claim 10, wherein at least one of the indicated jig alignments is used to indicate a 6 degree post operative tibial plateau angle.

12. A surgical jig in accordance with any one of claims 6 to 11, further comprising a slide rail which projects outwardly from and along said outwardly curved guide bearing surface and a corresponding longitudinally extending slide rail receiving channel projects inwardly from and along the concave upper guide surface to permit sliding movement between the slide rail and said the slide rail receiving channel and in turn permit the jig head and jig leg to be slidingly interconnected.

13. A surgical jig in accordance with any one of claims 6 to 11, further comprising a longitudinally extending slide rail which projects outwardly from and along the concave upper guide surface and a corresponding slide rail receiving channel projects inwardly from and along the outwardly curved guide bearing surface to permit sliding movement between the slide rail and the slide rail receiving channel and in turn permit the jig head and jig leg to be slidingly interconnected.

14. A surgical jig in accordance with claim 12 or 13, wherein the slide rail and slide rail receiving channel have corresponding cross-sectional profiles that are shaped to prevent the two elements from being separated once the slide rail has been slidingly received in the receiving channel.

15. A surgical jig in accordance with claim 14, wherein the slide rail and slide rail receiving channel have generally circular cross-sectional profiles.

16. A surgical jig in accordance with claim 14, wherein the slide rail and slide rail receiving channel have trapezoidal cross-sectional profiles.

17. A surgical jig in accordance with any one of claims 6 to 11, wherein the blade guide comprises a centrally located slot extending in length along the upper guide face and through the guide body to a lower face and wherein the head has one or more threaded apertures disposed in the wall carrying the guide bearing surface, and wherein the adjustment member comprises a screw configured to pass through the centrally located slot and into threaded engagement with one of the threaded apertures for tightening and thereby securing the head to the blade guide.

18. A surgical jig in accordance with any one of the preceding claims, wherein the blade guide is configured to receive a radial saw blade used for the osteotomy.

19. A surgical jig in accordance with claim 18, wherein once the head of the jig has been removed, a lower surface of the radial saw blade seats on the upper guide face for aligning and guiding the saw as it cuts through the tibial bone.

20. A surgical jig in accordance with claim 19, wherein a radius of the saw blade corresponds to an internal radius of the upper guide face.

21. A surgical jig in accordance with any one of the preceding claims, wherein at least one of the drill holes in the head and leg of the jig have cylindrical drill guides that extend from the respective outer faces.

22. A surgical jig in accordance with any one of the preceding claims, wherein a proximal end of the leg is integrally connected to a lower surface of the blade guide and wherein the drill holes are spaced along a longitudinal length of the leg body.

23. A surgical jig in accordance with any one of the preceding claims, further comprising one or more threaded apertures located in the leg, the threaded apertures configured to receive grub screws that can be screwed into the threaded apertures from the outer leg face for engagement with an underlying tibia bone, thereby facilitating adjustment of the concave upper guide face for perpendicular alignment with the tibia bone.

24. A method for performing a tibial plateau levelling osteotomy using the surgical jig according to any one of claims 1 to 23, the method including the steps of: a) determining a desired post operative tibial plateau angle; b) selectively positioning the head on the blade guide bearing to achieve the desired post operative tibial plateau angle; c) locating the jig over the tibial plateau; d) drilling plate screw holes in the underlying tibial plateau through each of the drill holes; e) removing the head from the jig; and f) making the osteotomy with the blade guide used for guiding the cutting blade.

25. A method in accordance with claim 24 when dependent on claim 23, further comprising adjusting the grub screws so that the blade guide lies generally perpendicular to the underlying bone, thereby preventing varus/valgus angulation of the osteotomy.

26. A method in accordance with claim 24 or 25, further comprising (g) removing the jig and thereafter placing the plate on the proximal osteotomy segment of the tibia whereafter locking screws are screwed through a head of the plate into corresponding head screw holes made in step d).

27. A method in accordance with claim 26, further comprising (h) correctively rotating the plate and attached proximal bone segment relative to the distal segment until leg holes disposed in the plate are aligned with leg screw holes made in step d) and thereafter screwing locking screws through the plate and into the leg screw holes for securing the leg portion of the plate to the distal osteotomy segment of the tibia.

28. A method in accordance with claim 27, wherein the plate comprises an aperture for receiving a rotation pin and wherein the rotation pin is utilised for step (h).

29. A method in accordance with claim 27 or 28, wherein the plate comprises one or more threaded apertures configured to receive grub screws and wherein the method further comprises adjusting grub screw(s) to lateralise tibial tuberosity if required.

30. A kit comprising a jig as claimed in any one of claims 1 to 23 and an osteotomy plate having a head and a leg with through holes in corresponding locations to the screw holes in the jig when the head and leg of the jig are in a predefined orientation.

31. An osteotomy plate for use with the jig as claimed in any one of claims 1 to 23, wherein the plate comprises a body having a head portion and a leg portion with through holes in corresponding locations to the screw holes in the jig when the head and leg of the jig are in a predefined orientation.

32. A surgical jig for use in a tibial plateau levelling osteotomy in which a bone plate is used post osteotomy for securing plateau segments of separated tibial bone, the jig comprising: a blade guide comprising a guide body having a concave upper guide surface; a leg coupled to the blade guide and comprising an elongate leg body extending away from the blade guide; and a head configured to detachably couple to the blade guide; and wherein one or more drill holes are provided on each of the head and leg and wherein, in use, the head is selectively positionable on the blade guide for facilitating drilling of plate fixing holes and wherein the head is thereafter removable to allow a radial blade saw to be positioned on the blade guide for carrying out the osteotomy.

33. An osteotomy kit for use in a tibial plateau levelling osteotomy in which a bone plate is used post osteotomy for securing plateau segments of separated tibial bone, the kit comprising: a saw blade used for the osteotomy; and surgical jig, the jig comprising: a head comprising a head body having one or more side walls, at least one of the one or more side walls comprising an outwardly curved guide bearing surface; a blade guide comprising a guide body having a concave upper guide surface, a curvature of at least a portion of the concave upper guide surface corresponding to a curvature of the sawblade; and a leg coupled to the blade guide and comprising an elongate leg body extending away from the blade guide; and wherein one or more drill holes are provided on each of the head and leg and wherein, in use, the head is selectively positionable on the blade guide with the guide bearing surface seated on the concave upper guide face for facilitating drilling of plate fixing holes and wherein the head is thereafter removable for locating a blade over the blade guide for carrying out the osteotomy.

34. An osteotomy kit for use in a tibial plateau levelling osteotomy in which a bone plate is used post osteotomy for securing plateau segments of separated tibial bone, the kit comprising: a surgical jig comprising: a head comprising a head body having one or more side walls, at least one of the one or more side walls comprising an outwardly curved guide bearing surface; a blade guide comprising a guide body having a concave upper guide surface, a curvature of at least a portion of the concave upper guide surface corresponding to a curvature of the sawblade; and a leg coupled to the blade guide and comprising an elongate leg body extending away from the blade guide; and a bone plate; and wherein through holes are provided on each of the jig and bone plate and wherein, when the head of the jig is mounted to the blade guide in a predefined alignment position, the relative location of through holes in the jig correspond to the relative location of through holes in the bone plate and wherein the through holes in the jig are used for drilling screw holes in the tibial bone and the through holes in the plate are used for receiving bone screws that screw into the screw holes for fixing the plate to the separated tibial bone segments.

35. A surgical jig for use in a tibial plateau levelling osteotomy in which a bone plate is used post osteotomy for securing plateau segments of separated tibial bone, the jig comprising: a leg comprising an elongate blade guide disposed at an upper end thereof and an elongate body having a bone facing face and an opposite face, the leg extending from the upper end to a lower end, and wherein an upper surface of the elongate blade guide has a concave longitudinal profile configured to receive a radial saw blade for carrying out the osteotomy; and a head having a bone facing face and an opposite face, the head comprising a circumferential wall connecting the bone facing and opposite faces and wherein a portion of the circumferential wall has a convex profile complimentary to the concave longitudinal profile of the upper surface of the elongate blade guide; wherein one or more drill holes on each of the head and leg extend between the respective bone and opposite faces and wherein, in use, the head is selectively positioned on the blade guide with the portion of the circumferential wall located on the concave upper surface of the blade guide for facilitating drilling of plate fixing holes.

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Figure 1a Figure 1a Figure 1b Figure 1b Figure 1c Figure 1c

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Figure 19a Figure 19a Figure 19b Figure 19b

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