WO2023102609A1

WO2023102609A1 - Bone fixation device

Info

Publication number: WO2023102609A1
Application number: PCT/AU2022/051474
Authority: WO
Inventors: Alistair George Royse; Colin Forbes ROYSE
Original assignee: Innovate Surgical Pty Ltd
Current assignee: Innovate Surgical Pty Ltd
Priority date: 2021-12-09
Filing date: 2022-12-08
Publication date: 2023-06-15
Anticipated expiration: 2024-06-09

Abstract

The present invention relates to a bone fixation device comprising: a plate; a tensioning band having a first end substantially fixed to the plate; and a tensioning block mounted to the plate, wherein a second end of the tensioning band is passed through the tensioning block, in use. The bone fixation device of the present invention may be adapted to be fixed to and encircle a bone that requires fixation to allow repair.

Description

BONE FIXATION DEVICE

FIELD OF INVENTION

[0001 ] The present invention relates to the field of medical surgery and to the fixation of bones in order to facilitate repair.

[0002] It will be convenient to hereinafter describe the invention in relation to a bone fixation device adapted to be fixed to and encircle the sternum, however it should be appreciated that the present invention is not limited to that use only.

BACKGROUND

[0003] Following a bone fracture, whether as a result of trauma or orthopaedic surgery, it is vitally important to keep the bone edges of the fracture aligned, adjacent and without movement for a 6 to 8 week period. This time is sufficient for new bone to form and provide strength to the union. Any foreign aids like metal plates or wires, or indeed external splints (like plaster of Paris splints) are used to achieve nothing more than prevention of movement at the fracture site, that is, stabilization. However, if movement occurs and the newly formed bone is broken at an early stage, proper healing will be delayed. If this happens frequently enough, then the two bone edges are adherent by scar tissue only (i.e. not by bone to bone union). The development of scar tissue between the two bone edges results in poor strength of the fracture site as well as chronic tenderness or pain.

[0004] More than 99% of cardiac surgery involves a midline division of the sternum into two halves (left and right), using a saw to divide the bone. This is a "fracture" of the bone. In 99.9% of cases worldwide, the two bone edges are reapposed using stainless steel wire which is passed through or around the bone, and tensioned by twisting the wire (wire cerclage).

[0005] Traditionally, closure of the sternum using stainless steel wires is associated with some degree of chronic pain in approximately 25% of cases, long-term. This may reflect imperfect bone to bone union from imperfect stabilization of the bone edges. [0006] Further, the sternum (or ribs) may in fact represent the most difficult of all bones to immobilize at the fracture site. This is because people must continue to breathe, cough and move around. All of these activities result in distracting forces of the fracture site, and the most notable one is coughing (or sneezing). However, even breathing provides a reasonably large distraction force and moving (such as getting out of a chair using one's arms to assist) or many other activities such as opening a car door, the fridge door and so on, result in some distracting forces at the fracture site. Unlike many other fractures in orthopaedic surgery, one is not able to disable the use of the chest. For example, if a person fractured their arm, it may be placed in a sling and movement avoided in this manner, or if the leg was broken, crutches would be provided to prevent any weight-bearing and so on.

[0007] Finally, the events that create the greatest forces of distraction on the sternum or ribs are coughing and sneezing. Furthermore, the forces are not evenly distributed with far more force being applied to the lower chest than the upper chest due to the elasticity of the chest wall, cartilage components of ribs and the so called “bucket handle” movement of the ribs.

[0008] While there are bone fixation devices and systems currently available these are typically difficult to use, or require specialized tools, or do not provide the necessary degree of stabilization/immobilization to achieve high strength bone re-joining. Further, certain prior art devices allegedly provide easily removable components to allow for rapid removal should, for example, the patient’s chest needs to be opened again. The present invention seeks to address one or more of the apparent shortcomings of previously available bone fixation devices.

[0009] It is to be appreciated that any discussion of documents, devices, acts or knowledge in this specification is included to explain the context of the present invention. Further, the discussion throughout this specification comes about due to the realisation of the inventor and/or the identification of certain related art problems by the inventor. Moreover, any discussion of material such as documents, devices, acts or knowledge in this specification is included to explain the context of the invention in terms of the inventor’s knowledge and experience and, accordingly, any such discussion should not be taken as an admission that any of the material forms part of the prior art base or the common general knowledge in the relevant art, on or before the priority date of the disclosure and claims herein.

SUMMARY OF INVENTION

[0010] It is an object of this invention to provide an improved bone fixation device.

[0011 ] A further object of the present invention is to alleviate at least one disadvantage associated with the related art.

[0012] It is an object of the embodiments described herein to overcome or alleviate at least one of the above noted drawbacks of related art systems or to at least provide a useful alternative to related art systems.

[0013] In a first aspect of embodiments described herein there is provided a fixation device comprising: a plate; a tensioning band having a first end associated with, preferably substantially fixed, to the plate; and a tensioning block mounted to the plate, wherein a second end of the tensioning band is passed through the tensioning block in use. Preferably, the tensioning block comprises a band entry port, a band exit port, a roof located therebetween, and a roller located beneath the roof. More preferably, the roof of the tensioning block comprises a retention flange and an angled section, and wherein the roller is maintained within the tensioner block between the retention flange and the roof. Yet more preferably, the plate comprises bone engagement members.

[0014] In a second aspect of embodiments described herein there is provided a method of clamping a bone using the bone fixation device comprising a plate comprising bone engagement members, a tensioning band and a tensioning block, the method comprising:

• applying the plate to the bone, wherein the bone engagement members engage the bone;

• passing a second end of the tensioning band around or through the bone; • inserting the second end of the tensioning band into a band entry port of the tensioning block and out of a band exit port of the tensioning block;

• pulling on the second end of the tensioning band, whereby the tensioning band tightens around the bone to pull the bone engagement members into the bone; and

• cutting the tensioning band to remove excess band.

[0015] Other aspects and preferred forms are disclosed in the specification and/or defined in the appended claims, forming a part of the description of the invention. While the present description focusses primarily on reapposition of the sternum, it is to be understood that the device and methodology described herein may find application in many orthopaedic situations where rigid fixation of a bone to allow efficient repair is required.

[0016] Further scope of applicability of embodiments of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the disclosure herein will become apparent to those skilled in the art from this detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Further disclosure, objects, advantages and aspects of preferred and other embodiments of the present application may be better understood by those skilled in the relevant art by reference to the following description of embodiments taken in conjunction with the accompanying drawings, which are given by way of illustration only, and thus are not limitative of the disclosure herein, and in which:

Figure 1 illustrates a prior art bone fixation device. A - the device prior to installation; B - devices in use on a sternum; and C - illustration of tensioning device.

Figure 2 is a top perspective view of a bone fixation device according to an embodiment of the present invention. Figure 3 is bottom perspective view of the device illustrated in Figure 2.

Figure 4 is a lateral cross-sectional view of the plate and tensioning block of the device illustrated in Figure 2.

Figure 5 is a medial cross-sectional view of the plate and tensioning block of the device illustrated in Figure 2.

Figure 6 shows various views of a device according to an embodiment of the present invention, incorporating a crimp on the second end of the tensioning band.

Figure 7 shows various views of a device according to an embodiment of the present invention, incorporating a crimp for fixing the second end of the tensioning band to a position near the first end of the tensioning band.

Figure 8 shows various views of a device according to an embodiment of the present invention, incorporating a crimp co-formed with the plate.

Figure 9 is a perspective view of a bone fixation device according to an embodiment of the present invention, comprising connecting bars according to an embodiment of the present invention.

Figure 10 is a medial view of the device illustrated in Figure 9.

Figure 1 1 shows perspective views of a bone fixation device according to an embodiment of the present invention, comprising a connecting panel according to an embodiment of the present invention.

Figure 12 shows perspective views of a bone fixation device according to an embodiment of the present invention, comprising a connecting panel according to a further embodiment of the present invention. DETAILED DESCRIPTION

[0018] The inventors have performed a randomised controlled study into the use of the inventive device and compared it to conventional wire cerclage. They found that the inventive device had superior healing. The implication of this finding is that the inventive device provides better stabilization of the fracture than the conventional wire treatment.

[0019] Prior art devices typically involve the use of conventional orthopaedic plate technology which comprises a device that spans the fracture and is fixed to both sides of the fracture by the use of screws. A more recent development has been the addition of a band system to wrap around the fractured bone to provide additional support. The use of a band spreads forces across a larger surface area of the bone than that achievable with conventional stainless-steel wires.

[0020] The SternaLock360 device (see Figure 1 A) is a currently available device which is designed for use in supporting the sternum during fracture repair. This device uses an orthopaedic plate 10 in combination with a band 20. The combination of plate 10 and band 20 is used on the sternum because the forces acting on the sternum during normal activities are substantially greater than those encountered in other typically fractured bones, such as the arm or leg. Further, simply breathing results in movement of the ribs and sternum. It is clear that standard technologies are insufficient to immobilize the chest during fracture healing. For example, one patient coughed so hard that the titanium band surrounding the sternum snapped completely.

[0021 ] As illustrated in Figure 1 B, the plate 10 and band 20 of the SternaLock360 are used to appose the left 32 and the right 33 halves of the sternum. It is further shown that the Sternalock360 uses screws 15 to attach the plate 10 to the bone.

[0022] The principle of orthopaedic screw length measurement is that the screw should pass through the first thick cortical layer of bone, then through the soft marrow and then to engage (but not pass through) the deeper cortical bone. In this way, the sharp tip of the screw does not injure any structure underlying the bone. [0023] The SternaLock360 also requires the use of a specialized tensioning device 40 with a screw thread to provide tension on the band bringing the two edges of the bone together, and then there are screws 15 placed through the plate 20 to hold the plate in place across the fracture line 34 in the sternum.

[0024] Another key consideration for closing the sternum is how does one get back into the chest in a very rapid fashion under emergency circumstances on some select rare occasions. This would include, for example, when there is a blood clot around the heart compressing the heart. When a SternaLock360 device has been used, the surgeon requires a heavy-duty metal cutter to divide the band 20 and the plates 10. While this a rare event, it is particularly difficult but must be performed without delay.

[0025] The device of the present invention seeks to provide an improved bone fixation device suitable for sternal fixation. While the present invention is described herein with specific reference to sternal fixation, the principles described are readily adaptable for use in relation to additional bone fractures. These additional applications are intended to be encompassed by the present description.

[0026] The invention described herein is a major simplification of the technology (and technique) required to internally fixate the sternum (breastbone) following cardiac surgery. The technology simplifies both the manufacturing process leading to cheaper production, as well as to simplification of the technique of insertion leading to improved surgeon acceptance.

[0027] The present invention provides a bone fixation device comprising a plate; a tensioning band, having a first end and a second end; and a tensioning block attached to or co-formed with, the plate. The first end of the tensioning band is immobilized at or adjacent to the plate and/or tensioning block. The second end of the tensioning band is adapted to be received through a band entry port into the tensioning block. The tensioning block includes a mechanism which allows only unidirectional movement of the tensioning band through the tensioning block. Specifically, the second end of the band may only pass through the tensioning block in a single direction, this allows the band to be pulled tight and to essentially remain at a specific location, whereby tension on the tensioning band is maintained. In some embodiments, the tensioning band is passed around the fractured bone and inserted into the band entry port of the tensioning block, through the tensioning block and out a band exit port. The tensioning band is then pulled tight whereby the tensioning band is brought to bear upon the outer surfaces of the fractured bone and the edges of the fractured bone are thereby brought into contact. As a consequence of the tightening of the tensioning band, the plate is brought into close contact with the fractured bone.

[0028] In certain embodiments of the present invention, the plate further comprises substantially circular openings adapted to receive screws whereby the plate may be fixed to the fractured bone by way of screws, in a manner analogous to that illustrated in Figure 1 B.

[0029] In preferred embodiments of the present invention, the plate further comprises bone engagement members. When the plate is brought into close contact with the fractured bone, the bone engagement members bear against, and preferably pierce, the bone, thereby fixing the fractured bone in the position in which it is to repair.

[0030] In further embodiments of the present invention, a supplementary band restraint may be incorporated into the device, either as a separate component or co-formed therewith. The supplementary band restraint may be employed to maintain a greater tension in the tensioning band than would be possible in the absence of the supplementary band restraint. Preferably, the supplementary band restraint is in the form of a crimp applied to the tensioning band. More preferably, the supplementary band restraint is situated around the tensioning band to prevent the second end of the tensioning band being able to pass, backwards, through the band exit port.

[0031 ] An exemplary embodiment of the present invention is illustrated in Figure 2. A bone fixation device 100 of the present invention comprises a plate 110, a tensioning band 120 and a tensioning block 130. In use, the tensioning band 120 is fixed at or near its first end 121 to the plate 1 10 and/or tensioning block 130. The free, second end of the tensioning band is passed around the sternum, or through the manubrium, then back into the tensioning block 130. Once the two halves of the sternum are aligned, the tensioning band 120 is pulled through the tensioning block 130. The tightening of the tensioning band 120 assists in bringing the two halves of the sternum together. As the tensioning band 120 is tightened, bone engagement members 11 1 of the plate 1 10 are forced into the underlying bone. The bone engagement members 1 1 1 essentially fix the plate to the underlying bone and thereby eliminates the need for screws to fix the plate 110 relative to the bone.

[0032] The plate 1 10 of the inventive device performs a similar function to that of previous devices in that it is intended to span the bone fracture, engage the bone whereby the bone is fixed in position for healing or repair. Unlike previous devices, the plate 1 10 of the inventive device is not screwed to the bone. Engagement with the fractured bone is preferably achieved through bone engagement members 1 1 1 which are preferably coformed with the plate 1 10. In the illustrated embodiment, the bone engagement members 1 1 1 are in the form of pointed projections, or teeth.

[0033] In certain embodiments of the present invention, the bone engagement members may be forcibly engaged to the bone prior to the tightening of the tensioning band 120, for example, by pushing the plate 1 10 against the bone, or through the use of a hammer or mallet. In other embodiments, the tightening of the tensioning band 120 may force the bone engagement members into the bone.

[0034] The tensioning band 120 comprises a first end 121 and a second end 122. The tensioning band is preferably a substantially flexible, flat band having a narrow rectangular cross-section. In order to function within the present invention, the first end 121 of the tensioning band must be securely fixed to or adjacent to the plate 1 10 and/or tensioning block 130. For example, in the illustrated embodiment, the first end 121 is looped around a portion of the tensioning block 130, which is attached to the plate 1 10.

[0035] In an alternative embodiment, the first end 121 may comprise a thickened or tapered portion. In such an embodiment, the second end 122 band may be passed through an opening in the plate 1 10 or tensioning block 130 that will only permit passage of the nonthickened portion of the tensioning band. Accordingly, when the tensioning band 120 is pulled further, the first end 121 will engage firmly with the plate 1 10 or tensioning block 130. This alternative embodiment may be suitable for use when the plate 1 10 is engaged with the bone prior to tightening of the tensioning band 120, as discussed above.

[0036] In use, the tensioning band 120 is adapted to be passed around the fractured bone and back to the plate 110 and/or tensioning block 130. Alternatively, the band may be passed through the manubrium (upper part of the sternum). Typically, a plurality of fixation devices would be used to fix the sternum, for example, one through the manubrium, and two or three around the body of the sternum. The fracture would run at right angles to the tensioning band, and the plate would straddle the fracture. The bone engagement members of the plate would pass into (or even through) the superficial cortex layer of the sternum and provide rigid fixation of the plate to the bone.

[0037] The tensioning block 130 comprises a band entry port 131 , a band exit port 132; a roof 133; a retention flange 134; and a roller 135. Wherein the band entry port is adapted to receive a second end 122 of the tensioning band 120. The tensioning band 120 is then threaded through the tensioning block 130 and exits the tensioning block 130 via a band exit port 132. Between the band entry port 131 and the band exit port 132 is located a roof

133 and retention flange 134 connected thereto. The roof 133 is angled or curved, substantially as illustrated in Figure 4, whereby the roof 133 begins near the band entry port 131 and rises to an apex where the retention flange 134 begins. The retention flange

134 is an extension of the roof 133 that is bent downwards towards the band exit port 132. Located beneath the roof 133 is a roller 135, preferably the roller 135 is in the form of a roughened ball. The roof 133 and retention flange 134 are sized and positioned whereby the roller 135 is loose but retained within the tensioning block 130, beneath the roof 133. When the tensioning band 120 is passed through the tensioning block 130, the roller 135 is located between the roof 135 and the tensioning band 120. As the tensioning band is pulled or pushed through the tensioning block 130, the roller 135 is caused to move towards the retention flange 134, at which position, the roller 135 is free to rotate and the tensioning band 120 is able to move through the tensioning block 130. When the tensioning band 120 is released, it moves in the opposite direction. The roughened surface of the roller 135 allows it to be gripped by the tensioning band 120, thereby moving the roller towards the band entry port 131 . Due to the slope of the roof 133, movement of the roller 133 towards the band entry port 131 is restricted and the roller 133 becomes wedged between the tensioning band 120 and the roof 133. As the roller 133 is moved closer to the band entry port 131 , the roller 133 becomes more tightly wedged between the tensioning band 120 and the roof 133, thereby preventing further movement of the tensioning band 120 and locking it in place.

[0038] Figure 3 illustrates the depth of the bone engagement members 11 1 from the plate 110. It will be apparent to the skilled person how the bone engagement members 1 1 1 are intended to penetrate the cortex of the bone when force is applied. As noted above, a small hammer can be used to further apply downward pressure on the plate 1 10 to assist with penetration of the bone engagement members 1 1 1 into the bone.

[0039] Figure 4 is a cross-sectional view of an embodiment of the tensioning block 130 according to an embodiment of the present invention. Preferably, as described above, the tensioning block 130 contains a roughened roller 133 which acts as a one-way valve in that when the tensioning band 120 is passed through the tensioning block, the tension force is retained, and the redundant length of the band may then be cut short. The first end 121 of the tensioning band 120 is retained firmly by the tensioning block 130. In certain embodiments of the invention, the first end 121 may be folded over a portion of the plate 1 10 or tensioning block 130 wherein tensioning of the tensioning band 120 causes the first end 121 to be held securely against the plate 1 10 or tensioning block 130.

[0040] An advantage over previous devices is that the present inventive device may be readily removed in an emergency. Typically, an emergency re-entry occurs within hours to a couple of days after surgery, whereby there is no solid new bone formation as yet. Usually, the patient is about to arrest or has arrested, and the circumstances are extremely dire, and urgency is substantial. The present device would be easily removed if required by simply lifting up the band to the side of the plate and dividing the band with a metal cutter. Thereafter, the entire device would simply be removed from the chest with a single forceful traction on the plate itself. This would be considerably superior to the existing devices, which require screws to be removed, and even to the conventional wire cerclage technique. [0041 ] In summary, the presently described band and plate system could provide for all of the stability of standard plating engagement with the bone by way of the sharp projections passing into the bone cortex itself, as well as all of the compression force being applied to the two halves of the sternum, and that force being retained.

[0042] Figures 6A and 6B show views of an embodiment of the present invention which incorporates a supplementary restraint in the form of a deformable crimp 136 located on the second end 122 of the tensioning band, ie the part that protrudes from the band exit port 132. In the illustrated embodiment, the crimp 136 is a metal component that is positioned around the band 120. In some further embodiments, a gap in the crimp 136 allows for easy manipulation and installation adjacent the second end 122 of the band, after deployment of the tensioning band 120 and preliminary tensioning using the tensioning block 130 mechanism. Once the tensioning band 120 has been tensioned to the required level, a laterally directed force on both sides of the crimp 136 may be applied bringing the central portion of the crimp 136 closer together to fix it to the tensioning band 120 and thus deforming the crimp to form a "waist" which would then permanently retain that applied force. Notably, this embodiment could employ a continuous crimp (not illustrated), since the tensioning band 120 could be cut to length before slipping the crimp on the second end 122 of the tensioning band.

[0043] Figure 6B illustrates the position of the crimp 136 and its position adjacent to the plate 1 10. Once fixed in place adjacent the second end 122 of the tensioning band, the crimp 136 would prevent the tensioning band 120 being drawn back through the band exit port 132 in the event of a failure of the tensioning block 130 and roller 135 to securely restrict movement of the tensioning band 120.

[0044] Figure 7 shows views of embodiments of the present invention that incorporate a supplementary restraint in the form of a deformable crimp 136 positioned to fix the second end 122 of the tensioning band to a portion of the tensioning band 120 close to its first end 121 , whereby a continuous loop of tensioning band is formed (i.e. effectively joins the first end 121 and second end 122). The crimp 136 may include a gap 137 to allow easy manipulation after an initial deployment and tensioning of the tensioning band 120. Figures 7A and 7B show the gap 137 being superficial (i.e. away from the bone surface). This embodiment necessitates manipulation from the bone-side of the band prior to significant tensioning occurring. This may provide an advantage of being able to easily remain in position as the tensioned band 120 would press this crimp 136 against the bone.

[0045] The embodiment illustrated in Figures 7C and 7D , like the embodiment illustrated in Figures 7A and 7B, illustrates a supplementary restraint that involves a crimp 136 that is employed to form a loop of tensioning band. In contrast to the embodiment illustrated in Figures 7A and 7B, the gap 137 in the crimp 136 is illustrated facing the bone surface. In this embodiment, the crimp 136 could be applied after initial tensioning of the band 120 with the initial approximation of the bone edges, as retained initially by block 130. By minor adjustment to the crimp 136, it can be manoeuvred into position, which would then allow for further tensioning of the band 120, downward pressure on the continuous part of the crimp 136 against the bone to stop it from dislodging, and subsequent crimping to retain the position.

[0046] Figure 8 illustrates a further embodiment of a device comprising a supplementary restraint. As illustrated, a crimp 136 is co-formed and continuous with the plate 110, rather than being present as a separate component. This embodiment of the invention operates in a manner similar to the embodiment illustrated in Figures 7C and 7D.

[0047] The embodiments illustrated in Figures 6 to 8 provide additional protection against slipping of the tensioning band through the tensioning block. However, those embodiments still retain the above-described advantage in that the present inventive device may be readily removed in an emergency. Since no part of the device is fixed to the bone, simply cutting the band will allow removal of the entire device.

[0048] In alternative embodiments, even greater rigidity of the chest wall could be achieved through the use of connecting bars 140, as illustrated in Figures 9 and 10. For example, the plates at the upper end of the sternum will allow for retardation of movement at the lower end of the sternum due to the redistribution of lateral force along the length of the connecting bars 140. In other words, the rigid joining of a device at each end of the sternum provides rigidity along the full length of the sternum. The devices therefore act as a single unit rather than each individual band and plate acting in isolation to redistribute a distracting force from a first plate to second, adjacent, plate.

[0049] As illustrated, the connecting bars 140 may be locked in position by teeth 141 that interlock with the bone engagement members 11 1 . In alternative embodiments, the connecting bars 140 do not have teeth. In such embodiments, it is envisaged that the connecting bars 140 may engage a flange 142 on the plate 1 10 (for example see Figures 6 to 8), in an insertable fashion which would allow for some repositioning of the plates 1 10 during deployment, but later having sufficient grip on the plate 1 10, via the flange 142, to allow full redistribution of lateral forces between plates 1 10. In this embodiment, the number of teeth on the side of plate 110 are reduced to affect the use of a wider bar which then engages with end and central teeth as in Figure 6A, 6B.

[0050] While the device and inventive concept described herein has been described with reference to fractures of the sternum, the device and adaptations thereof may be used in other “flexible” bone systems. Fractured ribs, particularly ribs displaced due to more substantial force of injury, cause considerable morbidity in patients. The importance of rib fractures is generally underappreciated or underreported, and this is primarily because they are so difficult to treat.

[0051 ] There is no “non-operative” approach to the reduction (realignment) and fixation of rib fractures because there is no way of being able to satisfactorily stabilise the fracture externally. Since the patient still needs to breathe, move, cough, undergo activities of daily living and so on, it is simply not possible to immobilise the fracture edges, non-invasively. This results in significant pain (pain at a fracture site is principally related to movement). Also, in order to avoid pain, marked reduction in the excursion of breathing on the affected side frequently results in severe lung dysfunction due to interference in the normal mechanics of ventilation, pneumonia et cetera.

[0052] Therefore, whilst most severe and displaced rib fractures are not treated by operative intervention, considerable discomfort results. Usually, surgery is reserved for those where the lung dysfunction is so great that it interferes with the ability to breathe independently. Typically, a motor vehicle accident victim with a major chest injury will be on the ventilator in the ICU, and have multiple fractures at the front and the back of the chest, resulting in the chest wall being “sucked in” during inspiration, and “blown out” during expiration, which seriously interferes with the mechanics of breathing and can result in respiratory failure. Therefore, the principle of surgical intervention is to rigidly fix the fracture site to re-establish the bony integrity of the chest wall, and facilitate breathing, as a way of being able to wean from the ventilator.

[0053] While there are a number of proprietary stabilisation devices to be used with rib fixation, these are far from satisfactory.

[0054] Using the same principles as applied to the sternum, and described above, the band in this instance is passed around the rib on one side of the fracture, and then is passed through the tensioning block, and tensioned. The bone engagement members of the plate will then further add to stability by passing into the bone of the rib. The same process is then applied to the rib on the other side of the fracture.

[0055] Given that ribs are smaller than the sternum, a range of plate sizes is available so that a selection appropriate to the patient could be made. In other words, the two rib ends are mobilised and reduced so that they now align correctly, and the intended sites for encirclement of the rib on either side of the fracture is identified, then a measurement is made of the distance between these two points, and an appropriate length of plate selected from a range of sizes available. Appropriately sized and curved connecting bars are also employed to provide support for the correct curvature of the ribs across the fracture site and to assist with the distribution of forces exerted in a novel manner.

[0056] The bands are then passed around the rib on either side of the fracture, and the bands passed through both of the tensioning blocks, and then tensioned sequentially. Apart from the specific design features, the critical element here is the ease of use by the surgeon in deploying these two devices.

[0057] As noted above, the connecting bars can be used in respect of fractures of the sternum and ribs. In the case of the sternum, since each side of the sternum is a single piece of bone, one could deploy the band and block/plate device in isolation without the connecting bar which runs parallel to the long axis of the sternum (thereby relying on the hemi-sternum to provide strength between these devices), i.e. the devices are not deployed on either side of the fracture. But if there is a problem, and the band “cuts through” the bone (not uncommon) then each side of the sternum is now effectively fractured in the short axis of the sternum in addition to the long axis. Hence, the use of connecting bars would act to distribute this lateral distracting force across the whole of the sternum rather than just in one site (greatest at the lower end).

[0058] Connecting bars may have other uses. For fixation of every other fracture by the device of the present invention, the two bands/blocks would be installed on either side of the fracture. Thus, having a rigid connecting bar between the two bands/blocks is necessary in order to bridge the fracture and connect the two bands and blocks together rigidly, i.e. it acts as the “plate” used in contemporary devices, crossing from one side of the fracture to the other. In this scenario it would be much stronger (but less flexible) to manufacture two blocks and a connecting bar(s) than to use a separate serrated bar as in the case of the sternum; although this would still be possible and of course more flexible as fewer bespoke sizes would need to be manufactured.

[0059] Additionally, the “bar” is present on one side of the bone only, and logically the strength of the bar would be greater in one direction (force directed towards the bar) than in the opposite direction (force directed away from the bar). However, the skilled person could deploy two band/block and bar devices - on both sides of a fractured bone (or even more than two). Take for example, fixation of a rib, clavicle or humerus, if two devices of the present invention, on diametrically opposite sides of the bone (180 degrees apart), then there would be bars present on both sides of the bone and this would result in considerably greater strength. However, there are surgical reasons why this may not often be undertaken, since the degree of surgery separating tissues from the bone would be greater, the devascularisation (loss of blood supply) to the bone is potentially greater, and if the intent was to subsequently remove the metal device after 6 - 12 months, this would require greater surgical intervention in order to do so. Nevertheless, from the mechanics of bone strength this is a theoretical possibility. [0060] Accordingly, the present invention also encompasses a bone fixation system comprising: a first fixation device; and a second fixation device; and a connector bar linking the first and second fixation devices. The bone fixation system may be employed in a method of clamping a bone, the method comprising the steps of:

• applying the plate of the first fixation device to the bone, wherein the bone engagement members bear against the bone;

• adjusting the connector bar to permit correct positioning of the plates of the first and second fixation devices;

• applying the plate of the second fixation device to the bone, wherein the bone engagement members bear against the bone;

• passing the second end of each tensioning band around or through the bone;

• inserting the second end of each tensioning band into a respective band entry port of a respective tensioning block and out of a band exit port of the tensioning block;

• pulling on the second end of each tensioning band, whereby the tensioning band tightens around the bone to pull the bone engagement members into the bone; and

• cutting each tensioning band to remove excess band.

[0061] As discussed in detail above, each tensioning band is held in place by a roller located within a respective tensioning block. The above method of using the bone fixation system may further comprise the step of fixing a supplementary restraint adjacent to the second end of each tensioning band.

[0062] The above description focusses on the use of the present invention in respect of fractures of the sternum and ribs. However, the present invention is not intended to be so limited in its application. The present invention may be used for any bone that allows for “encirclement” by the band as the force of retention mechanism. Therefore, bones that are most suitable for devices of the present invention include the sternum and cylindrical bones such as larger/longer bones - femur, tibia, fibula, humerus, radius, ulna; smaller/shorter bones - hands/feet: metacarpals, phalanges (fingers/toes); ribs; and clavicle (collar bone). In all of these cases the connecting bars seek to maintain rigid orientation of the plates for forces of all vectors thereby maintaining the relative position of the adjacent bone edges at all times irrespective of the nature or direction of forces applied.

[0063] The mechanism of this aspect of the present invention allows blocks to be rigidly fixed on either side of a fracture by the band and plate/block mechanism being a combination of encirclement and direct engagement of the cortical bone and a connecting bar of metal to then rigidly fix these two blocks together which crosses from one side of the fracture to the other.

[0064] In further embodiments of the present invention illustrated in Figures 1 1 and 12, an elongated plate 150 may be employed, wherein the elongated plate 150 comprises tensioning blocks 130, and associated tensioning bands 120, adjacent each end of the elongated plate 150. Two exemplary embodiments of such a device are shown herein. It will be apparent to the skilled person, that these embodiments may be used in similar situations to a device comprising one or more connecting bars. In particular, the device may be installed wherein a bone fracture is located between the tensioning bands 120, and the elongated plate 150 prevents or at least severely restricts relative movement of the fractured bone during healing. The device illustrated in Figure 12 includes an opening 151 in the elongated plate 150. In use, the opening 151 may allow examination of the underlying fracture and/or bone during healing. For example, ultrasound may be used to image the underlying fracture and/or bone through the opening 151. In the absence of an opening (see Figure 1 1 ), examination of the underlying fracture and/or bone would be difficult.

[0065] The device of the present invention has been described and illustrated in a manner that implies only encircling of bones by the tensioning band(s) 120. The skilled person will readily recognise that this is not always possible. For example, in some situations the tensioning band 120 must be passed through a bone in order to avoid other internal structures such as connected bones, or to provide a stronger installation. It is therefore envisaged that, in certain embodiments of the present invention, prior to installation the tensioning band 120 may include at its second end 122 a needle for passing through a bone. In such embodiments, the needle may be removed prior to the second end 122 being received in the band entry port 131 . [0066] As is typical for implanted devices, the bone fixation devices of the present invention are made of titanium, titanium alloys or medical grade stainless steel.

[0067] For purposes of description herein, the terms “upper,” “lower,” “right,” “left,” “rear,” “front,” “vertical,” “horizontal,” “interior,” “exterior,” and derivatives thereof shall relate to the invention as oriented in Figure 2. However, it is to be understood that the invention may assume various alternative orientations, except where expressly specified to the contrary. It is also to be understood that the specific devices and processes illustrated in the attached drawings, and described in the following specification are simply exemplary embodiments of the inventive concepts defined in the appended claims. Hence, specific dimensions and other physical characteristics relating to the embodiments disclosed herein are not to be considered as limiting, unless the claims expressly state otherwise. Additionally, unless otherwise specified, it is to be understood that discussion of a particular feature of component extending in or along a given direction or the like does not mean that the feature or component follows a straight line or axis in such a direction or that it only extends in such direction or on such a plane without other directional components or deviations, unless otherwise specified.

[0068] While this invention has been described in connection with specific embodiments thereof, it will be understood that it is capable of further modification(s). This application is intended to cover any variations uses or adaptations of the invention following in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practice within the art to which the invention pertains and as may be applied to the essential features hereinbefore set forth.

[0069] As the present invention may be embodied in several forms without departing from the spirit of the essential characteristics of the invention, it should be understood that the above-described embodiments are not to limit the present invention unless otherwise specified, but rather should be construed broadly within the spirit and scope of the invention as defined in the appended claims. The described embodiments are to be considered in all respects as illustrative only and not restrictive. [0070] Various modifications and equivalent arrangements are intended to be included within the spirit and scope of the invention and appended claims. Therefore, the specific embodiments are to be understood to be illustrative of the many ways in which the principles of the present invention may be practiced. In the following claims, means-plus- function clauses are intended to cover structures as performing the defined function and not only structural equivalents, but also equivalent structures. For example, although a nail and a screw may not be structural equivalents in that a nail employs a cylindrical surface to secure wooden parts together, whereas a screw employs a helical surface to secure wooden parts together, in the environment of fastening wooden parts, a nail and a screw are equivalent structures.

[0071 ] When a Markush group or other grouping is used herein, all individual members of the group and all combinations and sub-combinations possible of the group members are intended to be individually included in the disclosure. Every combination of components described or exemplified herein can be used to practice the invention, unless otherwise stated.

[0072] Whenever a range is given in the specification, for example, a temperature range, a time range, or a composition or concentration range, all intermediate ranges and subranges, as well as all individual values included in the ranges given are intended to be included in the disclosure. It will be understood that any subranges or individual values in a range or subrange that are included in the description herein can be excluded from the claims herein.

[0073] As used herein, "comprising" is synonymous with "including," "containing," or "characterized by," and is inclusive or open-ended and does not exclude additional, unrecited elements or method steps. As used herein, "consisting of excludes any element, step, or ingredient not specified in the claim element. As used herein, "consisting essentially of does not exclude materials or steps that do not materially affect the basic and novel characteristics of the claim. The broad term "comprising" is intended to encompass the narrower "consisting essentially of and the even narrower "consisting of." Thus, in any recitation herein of a phrase "comprising one or more claim element" (e.g., "comprising A), the phrase is intended to encompass the narrower, for example, "consisting essentially of A" and "consisting of A" Thus, the broader word "comprising" is intended to provide specific support in each use herein for either "consisting essentially of or "consisting of." The invention illustratively described herein suitably may be practiced in the absence of any element or elements, limitation or limitations which is not specifically disclosed herein.

[0074] One of ordinary skill in the art will appreciate that materials and methods, other than those specifically exemplified can be employed in the practice of the invention without resort to undue experimentation. All art-known functional equivalents, of any such materials and methods are intended to be included in this invention. The terms and expressions which have been employed are used as terms of description and not of limitation, and there is no intention that in the use of such terms and expressions of excluding any equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the invention claimed. Thus, it should be understood that although the present invention has been specifically disclosed by examples, preferred embodiments and optional features, modification and variation of the concepts herein disclosed may be resorted to by those skilled in the art, and that such modifications and variations are considered to be within the scope of this invention as defined by the appended claims.

List of parts - Figures 2 to 12:

Claims

1 . A fixation device comprising: a plate; a tensioning band having a first end substantially fixed to the plate; and a tensioning block mounted to the plate, wherein a second end of the tensioning band is passed through the tensioning block in use.

2. The fixation device of claim 1 , wherein the tensioning block comprises a band entry port, a band exit port, a roof located therebetween, and a roller located beneath the roof.

3. The fixation device of claim 2, wherein the roof of the tensioning block comprises a retention flange and an angled section, and wherein the roller is maintained within the tensioner block between the retention flange and the roof.

4. The fixation device of any one of claims 1 to 3, wherein the plate comprises bone engagement members.

5. The fixation device of any one of claims 1 to 4 further comprising a supplementary restraint.

6. The fixation device of claim 5, wherein the supplementary restraint is a crimp of deformable metal.

7. A method of clamping a bone using a bone fixation device comprising a plate comprising bone engagement members, a tensioning band and a tensioning block, the method comprising:

• applying the plate to the bone, wherein the bone engagement members bear against the bone;

• passing a second end of the tensioning band around or through the bone;

• inserting the second end of the tensioning band into a band entry port of the tensioning block and out of a band exit port of the tensioning block; • pulling on the second end of the tensioning band, whereby the tensioning band tightens around the bone to pull the bone engagement members into the bone; and

• cutting the tensioning band to remove excess band. The method of claim 7, wherein the tensioning band is held in place by a roller located within the tensioning block. The method of claim 7 or claim 8, further comprising the step of fixing a supplementary restraint adjacent to the second end of the tensioning band. A bone fixation system comprising:

(i) a first fixation device according to any one of claims 1 to 6; and

(ii) a second fixation device according to any one of claims 1 to 6; and

(iii) a connector bar linking the first and second fixation devices. A method of clamping a bone using the bone fixation system of claim 10, the method comprising the steps of:

• passing the second end of each tensioning band around or through the bone;

• cutting each tensioning band to remove excess band. The method of claim 11 , wherein each tensioning band is held in place by a roller located within a respective tensioning block. The method of claim 11 or claim 12, further comprising the step of fixing a supplementary restraint adjacent to the second end of each tensioning band.