Osteotomy operations are performed on individuals everyday in an attempt to correct misaligned bones. While osteotomy operations are typically performed in relation to the tibia they can be performed in relation to other bones such as the femur. However, for ease of description the operations will be described with reference to tibial osteotomy operations.

A typical osteotomy operation is performed on the proximal end of the tibia and there are many systems known in the prior art for performing this type of operation. This operation typically involves the removal of a wedge of bone from the tibia towards the proximal end thereof. Following the removal of the wedge of bone a plate is inserted into the tibia perpendicular to the longitudinal axis thereof above the site from where the wedge of bone was removed. The open wedge is then drawn closed and a screw is provided extending from the osteotomy plate to the bone beneath the wedge.

A number of disadvantages are encountered in using the systems of the prior art. These include difficulties in ensuring that the plate does not deviate during insertion into the bone. In addition, the prior art systems generally lead to other than optimum positioning of the plate inside and external to the proximal end of the tibia during the operation procedure. This typically leads to patient discomfort caused by the positioning of the external features of the implants.

The present inventors have designed a novel osteotomy plate which aids in the amelioration of a number of the disadvantages of the prior art.

Accordingly, in a first aspect, the present invention consists in an osteotomy plate adapted for insertion into a bone comprising an elongate longitudinally extending web provided with a cutting edge at one end and screw receiving means at the other end; a flange provided on each side of the web, each flange extending substantially parallel to the longitudinal axis of the web; and guide receiving means formed integral with the web and extending along the longitudinal axis thereof, said guide receiving means being adapted to receive a guide member in a manner such that on insertion into the bone the plate passes along the guide member.

In a second aspect the present invention consists in an osteotomy system comprising a guide member adapted for insertion into a bone perpendicular to the longitudinal axis of said bone; and an osteotomy plate, said osteotomy plate comprising an elongate longitudinally extending web provided with a cutting edge at one end and screw receiving means at the other end, a flange provided on each side of the web, each flange extending substantially parallel to the longitudinal axis of the web, and guide receiving means formed integral with the web and extending along the longitudinal axis thereof, said guide receiving means being adapted to receive the guide member in a manner such that on insertion into the bone the plate passes along the guide member.

In a third aspect, the present invention consists in an osteotomy kit, said kit comprising: -

1. A guide member adapted for insertion into a bone; and

2. An osteotomy plate comprising an elongate longitudinally extending web provided with a cutting edge at one end and a screw receiving means at the other end; a flange provided on each side of the web, each flange extending substantially parallel to the longitudinal

axis of the web; and a guide receiving means formed integral with the web and extending along the longitudinal axis thereof, said guide receiving means being adapted to receive the guide member in a manner such that on insertion into the bone the device passes along the guide member. In a fourth aspect the present invention consists in a method of correcting misalignment of a bone, the method comprising the following steps: - 1. Removing a bone wedge from the bone;

2. Inserting a guide member into the bone fragment proximal to the wedge and perpendicular to the longitudinal axis of the bone;

3. Inserting an osteotomy plate into the bone along the guide member; and

4. Connecting the bone fragment distal to the wedge to the osteotomy plate by means of a screw; characterised in that the osteotomy plate comprises an elongate longitudinally extending web provided with a cutting edge at one end and means adapted to receive the screw at the other end; a flange provided on each side of the web, each flange extending substantially parallel to the longitudinal axis of the web; and guide receiving means formed integral with the web and extending along the longitudinal axis thereof, said guide receiving means being adapted to receive the guide member in a manner such that on insertion into the bone the plate passes along the guide member.

In a preferred embodiment of the present invention the osteotomy plate is pressed from sheet metal. As would be readily appreciated by a person skilled in the art, the metal used will be relatively biologically compatible. In a further preferred embodiment of the present invention the guide receiving means comprises a groove extending part the way along the longitudinal axis of the

web and an inverted groove extending the remainder of the longitudinal axis of the web.

In a further preferred embodiment of the present invention the screw receiving means is provided on a lip which extends out of the plane web. The lip is preferably formed integrally with the web and is flexible. Further, the lip is preferably of such a length that upon insertion into the bone the screw receiving means is positioned inferior to the osteotomy wedge cut in the bone. The screw receiving means preferably comprises a seat for the screw head and an aperture through which the screw passes, the seat and the aperture being arranged in a manner such that the screw can be adjusted through 80 degrees. In some situations it is preferred that the screw receiving means is adapted to receive 2 screws. As would be appreciated use of 2 screws results in finer attachment of the osteotomy plate to the bone fragment distal to the wedge. In yet a further preferred embodiment of the present invention the cutting edge is bevelled in a manner such that on insertion into the bone the guide receiving means is urged into contact with the guide member.

In order that the nature of the present invention may be more clearly understood, preferred forms thereof will now be described with reference to the accompanying drawings, in which: -

Fig. 1 is a side elevation view of the osteotomy plate of the present invention; Fig. 2 is a view from below of the osteotomy plate of Fig. 1;

Fig. 3 is a end view of the osteotomy plate of Fig. 1; Fig. 4 is a side elevation of a further embodiment of the osteotomy plate of the present invention; Fig. 5 is a view from underneath of the osteotomy

plate shown in Fig. 4;

Fig. 6 is an end view of the osteotomy plate of Fig.

4;

Fig. 7 is a side view of the osteotomy plate of the present invention in association with a guide member;

Fig. 8 is a view from above of the osteotomy plate and guide member of Fig. 7; and

Fig. 9 is a schematic representation showing the osteotomy plate of the present invention used in a tibial osteotomy operation.

As shown in Figure 1, the osteotomy plate 10 includes a web 11, flanges 12, a lip 13 provided with screw receiving means 14.

As is more clearly shown in Figure 2 end 15 of web 11 is bevelled to form a cutting edge.

As is shown in Figure 3 the screw receiving means 14 include a seat 16 with a screw head and an aperture 17 through which the screw may extend.

In some cases, in order to more firmly secure the osteotomy plate to the bone beneath the wedge, the screw receiving means is adapted to receive two screws. This embodiment is shown in Figures 5 and 6.

As is most clearly shown in Figures 7 and 8, the guide member receiving means 18 of the osteotomy plate 11 extends along the longitudinal axis of the web 11. The guide member receiving means 18 is adapted to receive the guide member 19. In the embodiment shown in Figures 7 and 8, the guide member receiving means comprises a groove 20 in which the guide member 19 lies and an inverted groove or bridge 21 under which the guide member 19 passes. The lower surface of the web 11 is provided with a ridge 27 which is the base of groove 20.

As is most clearly shown in Figure 9, a guide member 19 is inserted into the proximal end 22 of the tibia 23. In this Figure the dashed lines represent the alignment of

the tibia 23 prior to insertion of the osteotomy plate 10.

As can be seen in Figure 9 a wedge of bone 24 has been removed. The osteotomy plate 10 has been inserted into the tibia 23 proximal to the wedge of bone 24. The osteotomy plate is then connected to the bone fragment 28 distal to the wedge 24 by means of screw 25, the screw 25 passing through the screw receiving means 14. As can be clearly seen the head 26 of screw 25 lies inferior to the osteotomy wedge 24. This results in the portion of the head of the screw projecting beyond the bone being minimised thereby resulting in decreased patient discomfort.

As will be understood by a person skilled in the art lateral movement of the osteotomy plate 10 is substantially prevented by flanges 12 and ridge 27.

In addition the bevel of cutting 15 is such that it allows a forward cutting whilst displacing the web 11 upwards towards the guide member 19 which prevents movement upward out of the plane of the guide member 19. It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the invention as shown in the specific embodiments without departing from the spirit or scope of the invention as broadly described. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.