GB2546089A - A bone stabilisation device and uses thereof - Google Patents

Abstract

The present invention relates to a bone stabilisation device comprising a longitudinally extending arm 1 having a first bone mounting portion 5 and a first bone fixing element 7, and a locating portion 3 having a second bone mounting portion 15 and a second bone fixing element 17. The locating portion 3 is adapted to receive the arm 1, such that longitudinal movement is permitted as the arm slides within the locating portion. The location portion may particularly be a discontinuous sleeve with n-shaped brackets 21. Use of the bone stabilisation device to correct alignment of an ulna osteotomy in a method of veterinary surgery is also contemplated. Suitable methods of such surgery are also provided. Such devices, methods and uses are particularly suited for veterinary treatment of dogs in cases of elbow dysplasia.

Description

A bone stabilisation device and uses thereof

The present invention relates to a bone stabilisation device, suitable for use in canine elbow dysplasia surgery, where an ulna osteotomy is deemed a desirable method of treatment. The device allows an ulna bone subject to osteotomy to move in a longitudinal direction, whilst the axial alignment of the ulna bone is maintained. The bone stabilisation device comprises a) an extending arm having a first bone mounting portion and a first bone fixing element, and b) a locating portion adapted to receive the extending arm, configured such that it is in moveable communication with said extending arm, having a second bone mounting portion and a second bone fixing element. The invention also relates to use of such a bone stabilisation device for correct alignment of an ulna osteotomy in a method of veterinary surgery.

Canine elbow dysplasia is a common condition affecting the forelimb of a dog, with some breeds being over-represented. Whilst the aetiology of the condition is poorly understood, this condition can occur when the ulna and radius bones of the canine are of disproportionate length and do not meet the humeral condyle in the correct way. When this bone length condition arises the elbow is said to be "incongruent", conversely, where the two bones are of the correct length and no elbow dysplasia is exhibited, then the elbow is said to be congruent. The elbow dysplasia condition may arise where the ulna bone is short relative to the length of the radius bone, or visa versa, where the radius bone is short relative to the length of the ulna bone.

Elbow dysplasia is a known developmental condition in dogs. The condition may result in an unusual gait, and may be accompanied by Medial Coronoid Process Disease, Ununited Anconeal Process and joint cartilage damage; joint swelling (effusion), arthritis, pain, stiffness and lameness are also common clinical features. It is common for dogs with a genetic predisposition to elbow dysplasia to have both elbows affected.

At present, where canine elbow dysplasia is suspected, diagnosis is by means of radiography, arthroscopy, computed tomography, or similar to assess congruity between the patient’s ulna, radius and humeral condyles area. Once diagnosis of elbow dysplasia has been made a number of treatment methods are currently open to the veterinary practitioner. These will be briefly described below: 1. Non-surgical treatment may be employed to control secondary inflammation and pain. Such methods of treatment are not long lasting, and do not overcome the elbow dysplasia its self. 2. Total elbow replacement may be suggested. This procedure is in its infancy, and has associated problems including; potential complications which are numerous and severe, it is costly, recovery is slow and a permanent limp or detrimental change in gait is usually observed. This method of treatment is currently reserved only for the very worst cases. 3. Elbow arthroscopy whereby the elbow joint is inspected and accompanied by "keyhole” surgery. Cartilage damage can be visualised and documented and some abnormalities of the Medial Coronoid Process can be addressed, including fragment removal if necessary. 4. If an Ununited Anconeal Process is present, this ununited process can be rigidly attached to the ulna using a screw and occasionally a pin. 5. Ulna osteotomy may be performed where the ulna bone is judged to be too short relative to the radius bone i.e. in most cases of Ununited Anconeal Process, and in cases of elbow dysplasia if the ulna is judged to be short and the joint incongruent. Where a more distal (i.e. that furthest away from the elbow) ulna osteotomy is thought less likely to permit sufficient movement between radius and ulna to restore elbow congruity, the proximal end (i.e. that closest to the elbow) of the ulna is cut just a short distance below the elbow. In theory, as the ulna osteotomy opens (effectively lengthening the ulna bone), the load bearing, articular surfaces of the proximal radius and ulna can re-align to achieve congruity with the humeral condyles.

One problem with the currently performed proximal ulna osteotomy surgical method is that following performance of the osteotomy procedure, the pull on the triceps brachii muscle group will often cause the proximal (i.e. that closest to the elbow) bone segment to swing caudally, or oscillate, and lose its alignment with the distal (i.e. that furthest from the elbow) bone segment. This has a number of serious potential consequences: - This is very painful for the patient. - The ulnar osteotomy site takes longer to heal than normal and heals via development of a very large bone callus (healing bone) that can be painful and disfiguring. - In the worst cases, the ulna never heals at all, and atrophies (resorbs) which causes chronic bone pain. - The elbow becomes unstable and elbow congruity is lost (or may be rendered worse than it was before the ulna osteotomy procedure). - Instability between the radius and humerus occurs secondary to stretching / weakness of the lateral collateral ligament. This results in subluxation (partial dislocation) of the radio-humeral joint during weight bearing, severe instability and a debilitating lameness. - Malunion of the osteotomy may limit the range of motion and in particular full extension of the elbow joint, with adverse consequences to patient gait.

Current solutions to the problem of this ulnar instability have a relatively high complication rate. Current solutions include: a. Making the ulnar osteotomy in a specific orientation (so-called bi-oblique ulnar osteotomy), or using a domed osteotomy blade. In theory, this means that the obliquity of cut of the ulna is such that the avulsion force of the triceps forces the ends of ulna bone together rather than pulling them apart. b. Placement of an external skeletal fixator (ESF) structure which is cumbersome and rarely performed. Unless dynamic, the fixator “locks” the ulna into a fixed position determined by the ESF and does not allow the ulna to find its own resting point relative to the radius and humerus. In other words, final ulna length may not be correct. c. Placement of a pin within the medullary cavity of the ulna (intramedullary pin). The pin can bend, break or migrate proximally out of the ulna, d. Rigid plate fixation which requires careful pre-operative and intra-operative measurements to be taken and increases the length of time of surgery. Like the ESF, the plate “locks” the ulna in a position determined by the plate and does not allow it to find its own resting point relative to the radius and humerus. In other words, final ulnar length may not be correct.

Procedure (a) above is frequently performed but the complication of ulnar instability can still arise. Procedures (b-d) above are performed less frequently as their disadvantages are thought to outweigh their advantages.

There is, therefore, a need for improved surgical procedures, especially in relation to improvements to the preferred ulna osteotomy procedure to prevent the undesirable bone fragment oscillation or caudal movement.

Furthermore, it is desirable that improvements in surgical procedures are achieved by a means that can easily be introduced to veterinary surgeons, without the veterinary surgeon needing to re-train in a complicated new surgical procedure. Also, it is desirable that the improvement be achieved by a cost effective means.

According to one aspect of the present invention there is provided a bone stabilisation device comprising; a) an extending arm having a first bone mounting portion and a first bone fixing element, and b) a locating portion adapted to receive the extending arm, configured such that it is in moveable communication with said extending arm, having a second bone mounting portion and a second bone fixing element.

In use, the extending arm and locating portion in combination control movement of bone fragments; this control is achieved by allowing movement in an axial direction relative to the axes of the proximal and distal ulna bone segments, whilst movement perpendicular to the long axis of the bone, that is cranial to caudal (front to back) or medial to lateral (side to side) movement of the bone fragments to which the device is affixed is limited. As such, the extending arm is movable in a longitudinal direction relative to the locating portion (and vice versa); this allows for the ulna bone to find it own length, whilst caudal movement, and instability, is limited.

The device is suitable for use in existing surgical methods, particularly those concerning ulna osteotomy. More especially, the device is designed to limit bone fragment oscillation and in particular caudal movement once an ulna osteotomy has been performed. In particular, the device is designed such that the extending arm can be affixed to one bone segment, and the locating portion affixed to the alternate bone segment and the extending arm positioned in moveable communication within the locating portion to maintain alignment of the bone segments to which the device is affixed, and limit oscillation of the bone segments relative to one another. In particular, the present device is particularly suited for use in ulna osteotomy, however, it may also find utility in other bone osteotomy surgical procedure where axial alignment needs to be maintained and/or bone segment oscillation may be a problem.

As will be appreciated by the skilled person, the breeds of canine affected by elbow dysplasia, and which may benefit from ulna osteotomy surgery and the implantation of a bone stabilisation device according to the present invention, are of varied size and weight. As such, there is contemplated, as particularly preferable, a bone stabilisation device comprising; a) an extending arm having a first bone mounting portion and a first bone fixing element, having an overall length of between 19 and 250 millimetres (mm), suitably 75 and 125 mm for an average medium weight breed of dog, and b) a locating portion adapted to receive the extending arm, configured such that it is in moveable communication with said extending arm, having a second bone mounting portion and a second bone fixing element, having an overall length of between 4 and 80 millimetres (mm), suitably 15 and 40 millimetres mm for an average medium weight breed of dog. Preferably, the extending arm will have an overall length of between 40 and 180 mm, most preferably 90 and 110 mm, and preferably the locating portion will have an overall length of between 9 and 50 mm, most preferably 19 and 25 mm.

The skilled person will appreciate that devices having lengths at the upper ends of the size ranges stated above will be suitable for larger breeds of dogs, whilst devices having lengths at the lower ends of the size ranges stated above will be suitable for smaller breeds of dogs.

Suitably, the locating portion is configured such that it is in moveable communication with said extending arm, such that the extending arm can reversibly extend and retract within the locating portion upon subsequent movement of the bone segments to which the device is affixed during use. The veterinary surgeon is able to position the extending arm in a position to facilitate the moveable communication relative to the location portion prior to fixing the two parts of the device in place on the ulna bone segments. Most preferably, the extending arm can be considered to comprise a distal end, and a proximal end; and it is preferably the distal end which is in communication with the locating portion.

The locating portion may be provided with a continuous or discontinuous sleeve member. In use the extending arm distal end is housed within the sleeve member such that the position of the extending arm relative to the sleeve member achieves the moveable communication between the two parts of the bone stabilisation device. More preferably the sleeve is discontinuous, this allows for a lighter device to be manufactured, as such, preferably the sleeve member defines an aperture; the extending arm may be received by said aperture. Most preferably the sleeve member is discontinuous and comprises two or more sections. Suitably two discontinuous sleeve member sections are provided, and one section is provided so as to be distal and one section is provided so as to be proximal relative to the humeral bone when in use.

Preferably the continuous or discontinuous sleeve member is integral to the locating portion, as this will provide the strongest device configuration, and be less likely to break when in situ.

It should be understood that the sleeve member defines a channel or aperture into which the extending arm can be position in moveable communication. As such, the locating portion and extending arm are preferably mounted relative to one another, and most preferably the locating portion and extending arm are slidably mounted to one another, such that the two components of the bone stabilisation device can move independently of one another in the longitudinal direction relative to the bone segments to which they are attached, however, oscillation or caudal movement of the bone segments is restricted. Preferably the sleeve member may be a closed "n” shape, or closed horseshoe shaped, to define an aperture or channel. The aperture or channel may be closed or open at its distal end. Where the aperture or channel is closed at the distal end, this will limit the amount of movement permitted by the extending arm in the longitudinal direction.

Alternatively, or additionally, preferably the extending arm is provided with a stop member. The stop member is most preferably provided at the distal end of the extending arm, and is preferred in a configuration where the extending arm runs through the locating portion and the stop member limits the movement of the extending arm in the longitudinal direction relative to the device and ulna bone by coming in to contact with the distal end of the locating portion. Such a configuration of the device may be preferred to prevent dislocation of the extending arm from the locating portion where an open ended sleeve member is utilised, and the possibility of hyper extension of the bone segments is present, such that during use, the two parts of the device may not be separated from each other, i.e. the stop member limits the longitudinal movement of the extending arm. This problem may also be addressed by merely providing the extending arm of suitable overall length to not be at risk of being dislocated from the locating portion during use. The latter option may have manufacturing and ease of use advantages; the stop member option may be advantageous for keeping the device small and light, which may be beneficial for use in young dogs, or certain breeds of dog.

Preferably the extending arm is provided with a spacer element. The spacer element may be provided by a crank, spacer or step. The spacer element is preferably integral to the body of the extending arm, such that the extending arm distal end is in communication with, but spaced in relation to, the extending arm proximal end. In some embodiments the spacer element may be considered to be the central portion of the extending arm, being present in between the proximal and distal end portions, however, such an arrangement is not essential.

Suitably, the spacer element is utilised to facilitate the orientation of longitudinal axis of the proximal bone segment, when in use, in parallel with the longitudinal axis of the distal bone segment. This allows the veterinary surgeon to align the two bone segments during the ulna osteotomy procedure, and the alignment may be maintained by the affixation of the device. This retention of alignment renders the bone segments more stable. This bone stabilisation aspect of the present invention will be appreciated more readily by reference to the accompanying drawings. The purpose of the extending arm spacer element is to keep the alignment of the bone fragments in the same desirable axial orientation, even where the relative heights of the extending arm bone mounting portion and the locating portion bone mounting portion may be out of alignment, for example.

More especially, the spacer element may allow the extending arm distal end to align within the aperture defined by the sleeve member, such that the two bone segments to which the device is affixed are kept aligned. As such, the presence of the extending arm spacer element is particularly preferred in combination with the presence of the locating portion sleeve member embodiment, as described above. Optionally, the device may comprise anti-rotation means, which may be applied to said extending arm, and/or locating portion. The anti-rotation means are employed to provide a more rigid device. Additionally, bone rotation may preferably be limited by use of such a modified device - this may be preferable for some surgical interventions and not preferable for others. Rotation can be prevented by providing any suitable locking means to the constituent parts of the device, most preferably, angles within the cross-sectional shape of the component parts of the device are provided, for example the extending arm, marker element and spacer element may be triangular, square, or hexagonal shaped in cross-section and lock into similarly correspondingly shaped interfaces on the locating portion part of the device, for example the sleeve member, with which they physically communicate.

As mentioned above he bone stabilisation device comprises a first and second bone mounting portion with corresponding first and second bone fixing element, which can be provided to facilitate the affixing of the two component parts of the device to the two bone segments. These first and second bone mounting portion with corresponding first and second bone fixing elements may be selected to be the same or different for each of the component parts of the device.

Suitably, the first bone mounting portion and the first bone fixing element are provided at the proximal end of the extending arm. Suitably, the second bone mounting portion and the second bone fixing element are provided along the length of the locating portion. Such an arrangement allows for the locating portion to be strongly affixed to the bone segment, which allows the locating portion to withstand the forces resulting from the bone movement, when in use.

Suitably the first and/or second mounting portions are configured to receive the first and/or second fixing elements, accordingly.

Preferably the first, and/or second mounting portions comprise one or more receiving holes, and preferably the first and/or second bone fixing elements comprise one or more screws. As such, the two component parts of the bone stabilisation device may be affixed to the relative bone segments via locking screws. Most preferably, an arrangement of two or three holes and screws is provided, depending on the size of the overall device, i.e. a relative larger device for a larger breed of dog will preferably comprise three holes and screws of a larger size, a relatively smaller device for a smaller breed, or young dog, will preferably comprise two holes and screws of a smaller size.

Alternatively, the first, and/or second mounting portions comprise a bone contacting surface, and preferably the first and/or second bone fixing elements comprise a bone cement. As such, the two component parts of the bone stabilisation device may be affixed to the relative bone segments via "glue", in the form of a bone cement. In this embodiment, the bone contacting surface is preferably textured to provide a key for the bone cement. As current bone cements are not found to be sufficiently strong to provide the necessary strength needed for retention of a bone stabilisation device in an animal fore leg, this embodiment is less preferred. However, it is anticipated that improvements in bone cements may make this a commercially viable alternative device in the future.

Most preferably, the first and second bone mounting portions comprise receiving holes, and the first and second bone fixing elements comprise screws, typically locking screws.

Suitably, the device is formed from a bio-compatible material. Most preferably, the device is formed substantially of surgical stainless steel. Alternatively, the device is formed substantially of titanium (alloy), cobalt chrome, nitinol or other bio-compatible metal. Alternatively, the device may be formed substantially from a rigid plastic material.

As the device is to be used in surgical procedures it is preferable that the material chosen for the device is such that the device can be sterilised prior to use. More especially, it is envisaged that the device will either be supplied pre-sterilised in a packet for use in a surgical procedure or (most commonly) sterilised on site of use by the veterinary surgeon in an autoclave.

The invention also relates to use of such a bone stabilisation device for correct alignment of an ulna osteotomy in a method of veterinary surgery. As such, according to a further embodiment of the present invention there is provided a method of utilising a bone stabilisation device, as described above, in a veterinary surgical method.

Such a surgical method may involve the steps of making a standard caudal surgical approach to the ulna including medially and laterally, and extend it a suitable length proximally and distally (up and down) to enable the bone stabilization device to be affixed directly to the bone.

Optionally, once the position of the osteotomy is identified, the bone stabilisation device may be placed on the bone, (usually the lateral aspect of the ulna i.e. the outer facing side) to ensure adequate exposure for affixing the device has been provided. When the surgeon places the device, it is important to ensure that adequate exposure has been provided, such that the position does not interfere with elbow function,

Placing the locating portion of the stabilisation device in a position about 5mm distal to the ulna is particularly preferred.

Typically the surgeon will mark the bone where the locating portion of the device is to be positioned.

The method may comprise completing an oblique ulna osteotomy such that the ulna bone is cut to provide two bone fragments. The bone fragments are then allowed to assume their new corrected alignment; usually the proximal (upper) segment of the ulna moves a little caudally (backwards). As an alternative, an ulnar ostectomy (whereby a short section of bone is removed) may be performed instead of the ulna osteotomy; in this case the bone will still have been cut to provide two bone fragments.

Subsequent to the ulna osteotomy, or osteotomy, method step the bone stabilization device locating porting is affixed onto the distal ulna segment and secured to the bone utilising the said second bone mounting portion and second bone fixing element. As descried above, in relation to describing embodiments of the device, the fixing element is most preferably provided by the use of screws.

Once the locating portion has been affixed to one bone fragment, the extending arm is reintroduced to the bone stabilization device by inserting it fully into the locating portion. The extending arm should be positioned so that said first bone mounting portion is in contact with the bone. This ensures correct positioning of the extending arm part of the device, and means that the working length of the screws (if used) is short and therefore the screws should be less likely to break in use.

In addition, it is essential that the extending arm of the device be positioned so that is can slide, relative to the locating portion, to lengthen or shorten the working length of the overall bone stabilisation device.

Subsequent to positioning the extending arm, it may then be fixed to the bone fragment via the extending arm first bone mounting portion and a first bone fixing element to the proximal ulna. As descried above, in relation to describing embodiments of the device, the fixing element is most preferably provided by the use of screws.

Following the affixing of the bone stabilization device to the two bone fragments, a check that elbow range of movement is unaffected should be performed.

Preferably the method will include routine flush and suction of the surgical site.

Ultimately, the method will include the step of closing the soft tissues over the device.

Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings provided, in which; - Figure 1 illustrates a side view of a bone stabilisation device according to one embodiment of the present invention - Figure 2 illustrates a side view of a bone stabilisation device according to an alternative embodiment of the present invention positioned as in use mounted to an ulna bone in a patient.

Throughout the following description, and in the accompanying drawings, similar components have been designated with identical numbers.

The bone stabilisation device, as depicted in Figures 1 and 2, is constructed of surgical grade stainless steel, and comprises of two parts: an extending arm (1), and a locating portion (3) which is adapted to receive the extending arm. Figure 2 show the device in use, amounted to two ulna bone segments (25, 27) following an ulna osteotomy.

The means of adaptation of the locating portion (3) is provided by an integrally formed discontinuous sleeve member (21) comprising two “n” shaped sections which define an aperture through which a section of the extending arm (the distal end, 11) may be housed in a slidable manner when the device is in use. Longitudinal movement of the two parts of the device (1 and 3) relative to one another in the direction of the shown double headed arrow (as shown in both Figures 1 and 2) is permitted, but caudal movement of the two parts of the device, and hence any bone segment to which the device parts are affixed (25 and 27), is limited. This device arrangement allows the ulna bone subjected to osteotomy to define a new bone length, which is advantageous. Simultaneously, caudal swing (oscillation) of the bone segments is limited which prevents further complications for the canine operated on, as the bone is stabilised.

It should be noted that “distal” and “proximal” are used to help identify the position of the relative parts of the device in comparison to one another, and also in relation to their position relative to the humeral condyles when in use. As such, “proximal” is used to describe components positioned closer to the humeral head when in use, and “distal” is used to describe those comments positioned further away from the humeral head, when in use. No limitation on the scope of protection is intended by such a description, as the device could be used in the alternative orientation without needing modification.

In the stabilisation device as shown in Figures 1 and 2 a spacer element (9) is provided in the form of a crank. In use, the spacer element (9) allows the two bone segments (25 and 27) to be retained at the same orientation relative to one another. As such, the spaced element (9) provides an “off set” to the height of the distal end of the extending arm (11), relative to the proximal end (5) such that it can be mounted correctly within the discontinuous sleeve member (21) whilst maintaining the bone segments (25 and 27) in a parallel orientation. As will be appreciated from Figure 2 this arrangement allows the two bone segments (25 and 27) to be aligned.

The proximal end of the extending arm also provides the first bone mounting portion (5) of the extending arm (1). The first bone mounting portion (5) is provided in combination with a first bone fixing element in the form of two receiving holes and corresponding locking screws (7). The receiving holes may be countersunk such that the heads of the locking screws do not protrude above the main body of the first bone mounting portion part of the extending arm (5).

The locating portion (3) is provided with a second bone mounting portion (15), which is provided with a second bone fixing element in the form of two receiving holes and corresponding locking screws (17). The receiving holes may be countersunk such that the heads of the locking screws do not protrude above the body of the second bone mounting portion part of the locating portion (15); by providing the locking screws in a countersunk arrangement it is ensured that the heads of the screws do not impede the movement of the distal end of the extending arm (11) through the discontinuous sleeve member components (21) of the locating portion (3).

In most common breeds of canines anticipated to benefit from the utilisation of such a device as described above are listed below, with an indication of typical approximate adult weights, expressed in kilograms (kg): - Chihuahuas - 2-2.5kg. - Springer Spaniel - 18-20kg. - Labradors - 30kg. - Rottweiler - 40-45kg. - Newfoundland - 50-55kg. - Great Dane / Bernese Mountain Dog / Pyrenean - 60-70kg.

Naturally, a smaller, lighter breed of dog will require a smaller overall device than a larger, heavier breed of dog. As such, the overall size of the may be provided dependent upon its final intended use. However, in Figure 2, the overall length of the extending arm (1) is 100 millimetres, and the overall length of the locating portion is 22 millimetres.

The device as shown in Figures 1 and 2 may optionally be provided with additional or alternative features, in accordance with the embodiments provided above.

Claims (27)

Claims.

1. A bone stabilisation device comprising; a) an extending arm having a first bone mounting portion and a first bone fixing element, and b) a locating portion adapted to receive the extending arm, configured such that it is in moveable communication with said extending arm, having a second bone mounting portion and a second bone fixing element.

2. A bone stabilisation device according to any one of the preceding claims, wherein the locating portion and extending arm are slidably mounted to one another.

3. A bone stabilisation device according to claim 1 or 2, wherein; a) the extending arm having a first bone mounting portion and a first bone fixing element has an overall length of between 19 and 250 millimetres (mm), and b) the locating portion adapted to receive the extending arm, configured such that it is in moveable communication with said extending arm, having a second bone mounting portion and a second bone fixing element, has an overall length of between 4 and 80 millimetres (mm).

4. A bone stabilisation device according to any preceding claim, wherein the extending arm has an overall length of between 40 and 180 mm, and the locating portion has an overall length of between 9 and 50 mm.

5. A bone stabilisiation device according to claim 4, wherein the extending arm has an overall length of between 90 and 110 mm, and the locating portion has an overall length of between 19 and 25 mm.

6. A bone stabilisation device according to any preceding claim, wherein the locating portion is provided with a continuous or discontinuous sleeve member.

7. A bone stabilisation device according to claim 6, wherein the sleeve member is discontinuous.

8. A bone stabilisation device according to claim 6 or 7, wherein the continuous or discontinuous sleeve member is integral to the locating portion.

9. A bone stabilisation device according to any one of claims 6 to 8, wherein the sleeve member may be a closed "n" shape, or closed horseshoe shaped, to define an aperture or channel, and wherein the aperture or channel may be closed or open at its distal end.

10. A bone stabilisation device according to claim 9 wherein the aperture or channel is closed at the distal end.

11. A bone stabilisation device according to any preceding claim, wherein the extending arm is provided with a stop member.

12. A bone stabilisation device according to any preceding claim, wherein the extending arm is provided with a spacer element.

13. A bone stabilisation device according to claim 12, wherein the spacer element is provided by a crank, spacer or step.

14. A bone stabilisation device according to claim 12 or 13, wherein the spacer element is integral to the body of the extending arm, such that the extending arm distal end is in communication with, but spaced in relation to, the extending arm proximal end.

15 A bone stabilisation device according to any preceding claim, further comprising an anti-rotation means.

16. A bone stabilisation device according to any preceding claim, wherein said first bone mounting portion and said first bone fixing element are provided at the proximal end of the extending arm.

17. A bone stabilisation device according to any preceding claim, wherein said second bone mounting portion and said second bone fixing element are provided along the length of the locating portion.

18. A bone stabilisation device according to any preceding claim, wherein said mounting portions are configured to receive said fixing elements.

19. A bone stabilisation device according to any preceding claim, wherein said mounting portions comprise receiving holes, and said bone fixing elements comprise screws.

20. A bone stabilisation device according to any one of claims 1 to 17, wherein said mounting portions comprise a bone contacting surface, and said bone fixing elements comprise a bone cement.

21. A bone stabilisation device according to any preceding claim, wherein the device is formed from a bio-compatible material.

22. A bone stabilisation device according to claim 21, wherein the device is formed substantially of surgical stainless steel.

23. A bone stabilisation device according to claim 21, wherein the device is formed substantially of titanium (alloy), cobalt chrome, nitinol or other bio-compatible metal.

24. A bone stabilisation device according to claim 21, wherein the device is formed substantially from a rigid plastic material.

25. Use of a bone stabilisation device according to any one of claims 1 to 24 for correct alignment of an ulna osteotomy in a method of veterinary surgery.

26. A method of utilising a bone stabilisation device according to any one of claims 1 to 24 in a veterinary surgical method.

27. A method according to claim 26 including the steps of making a standard caudal surgical approach to the ulna including medially and laterally, and extend it a suitable length proximally and distally to enable said bone stabilization device to be affixed directly to the bone.