GB2402883A - Apparatus for assisted percutaneous fracture fixation - Google Patents

Abstract

A device 13,16 to assist in the percutaneous fixation of bone fractures comprises a plurality of elongate tubes 14,17 each with a bore adapted to receive a fixation wire 15. Each tube 14,17 extends within a common plane and substantially parallelly to each other tube. Each tube 14,17 comprises either a material opaque to X-rays, or a material transparent to X-rays, in which case it has an elongate opaque marker wire 18 extending parallelly to its bore. The device is provided with aiming wires (19,20 fig 6), which are laid in a desired direction across a surface of the patient's body and inserted into any tube 14,17 of the device. The fixation wire 15 is then passed through any other tube 14,17 of the device, into the bone and across the fracture, parallelly to the aiming wire. The device may comprise a pair of support plates (6,10 figs 2 and 3), to be applied across a fracture on opposite sides of a limb (2), to support a reduced fracture and maintain it in reduction. Alternatively, it may comprise units (31, fig11) mountable to the bone (25) distally and proximally of the fracture which may be drawn one towards the other, for example with a ratchet mechanism (33), to reduce the fracture.

Description

1 2402883

APPARATUS FOR ASSISTED PERCUTANEOUS FIXATION

The present invention relates to apparatus to facilitate the reduction, holding in reduction, wiring together and fixation ol' fractured bones. More particularly but not exclusively, it relates to apparatus to guide the percutaneous fixation of unstable fractures adjacent joints, such as the ankle and the elbow. The invention also relates to apparatus to aid the reduction of such fractures, and to methods of reduction and percutaneous fixation using such apparatus.

In orthopaedic surgery, it is frequently necessary to hold unstable fracture fragments of a fractured bone by implanting a wire or wires, extending across the fracture, to maintain the fragments of the bone in alignment as they knit together. The fracture is first reduced, bringing the fracture surfaces into correctly aligned contact one with the other. Then one or more wires are passed across the fracture fragments. It is prel'erahle to carry out such wiring percutaneously, involving only minor punctures in the skin. This avoids added trauma to surrounding tissues and the risk of infections to the bone.

Percutaneous wiring is normally carried out under X-ray visualization. Although modern X- ray equipment uses relatively low radiation intensities, any X-ray exposure is still undesirable, and the potential cumulative exposure to a surgeon's hands, and to those of any assistant, is considerable. It is therefore important to carry out wiring with as few attempts as possible, consistent with accuracy. Inaccurately-placed wires must be removed and replaced, increasing X-ray exposure, the trauma to the patient and the time for which the patient must be kept under a general anaesthetic (which should also be minimised).

In my co-pending UK patent application No. GB ()307021.6, apparatus is disclosed which assists significantly in the percutaneous wiring of many fractures which are otherwise difficult to handle. However, particular fractures have peculiar features and problems which the above apparatus may not be best suited to address, and an alternative form of apparatus and method for its use may be superior thereto.

For example, a f'racturc of the ankle is a case where open fixation may often be inadvisable - for example, due to the general condition of the patient (particularly for the frail and elderly), due to poor local skin condition, due to poor vascular supply to the limb or poor venous drainage therefrom, or due to poor bone quality, for example associated with osteoporosis.

Minimally invasive percutaneous techniques may therefore be the only advisable option.

Simple Type B ankle fractures with talar shift can be fixed percutaneously, as may be undisplaced fractures of one or both malleoli, the lowest extremities of the fibula and tibia at the lateral and medial sides of the ankle. Where malleolar fragments are displaced, it may be necessary to make a very small incision to ensure that no ligamentary tissue has become trapped between the fragments, but the fixation can still be carried out percutaneously.

Ilowever, there is still a need to carry out the percutaneous wiring as rapidly and accurately as possible, particularly as it is often necessary to insert several wires, substantially in parallel one with another, across the fracture. For bimalleolar fractures, it would be convenient to wire troth malleoli in a single procedure, but the optimum alignment of the wires for each malleolus will be very different, so suitable apparatus will need to be very versatile in use.

Another type of fracture in which percutaneous techniques would be beneficial, as long as they can be carried out rapidly and accurately, is a fracture of the oleocranon or of the upper ulna, adjacent the elbow.

These fractures are difficult to reduce and maintain in reduction because of the pull of the adjacent triceps muscle, and the optimum elbow position for conventional reduction is not convenient for percutaneous wiring.

It would therefore be beneficial if it were possible so to reduce such fractures that percutaneous fixation could easily be carried out. As for any percutaneous fixation, it would be preferable if the procedure could be performed as rapidly and accurately as possible.

It is therefore an object of the present invention to provide apparatus for assisting the percutaneous fixation of fractured bones, and a method for its use, which obviate the above disadvantages and provide the above benefits.

According to a first aspect oi'the present invention, there is provided a device to assist in the percutaneous fixation of bone fractures comprising a plurality of elongate tube means comprising a bore adapted to receive a fixation wire or the like of a preselected gauge and extending within a common plane and substantially parallelly one to the other.

Preferably, all said tube means are substantially identical one to the others.

Advantageously, each said tube means comprise a material substantially opaque to X-rays.

Alternatively, each said tube means comprises a material substantially transparent to X-rays, and is provided with elongate marker means substantially opaque to X-rays extending longitudinally thereof.

Said marker means may comprise metal wire means embedded in a wall of the tube means.

Each said tube means may be mounted directly to its neighbour or neighbours.

I'hc device preferably comprises aiming wire means, detachably mountable to a surface of the patient's body and engageable with tube means of the device.

In a lrst embodiment of the invention, the device further comprises a pair of support plate means, mountable to extend across a fracture or fractures on generally opposite sides of a fractured limb.

The pair of support plate means may thus support a reduced fracture and maintain it in reduction.

Preferably, each support plate means comprises a material transparent to X-rays.

Advantageously, one or each support plate means is provided on at least one surface with a plurality of groove means to assist in the positioning of aiming wires on the skin.

One or each support plate means may be configured on one surface conformably with a preselected part of a limb to aid its accurate positioning thereon.

In a second, alternative embodiment of the present invention, the device further comprises means to reduce a fracture and hold it in reduction.

Said reduction means preferably comprises a unit comprising two mounting elements, one mountable to bone distally of a fracture and the other mountable to bone proximally of a fracture, and means controllably to draw the mounting elements one towards the other.

Advantageously, the reduction means comprises two said units.

The two units may be mountable one to the other and to the bone by means of fixation wire means extending from each mounting element of a first unit, through a respective part of the bone to a corresponding mounting element of a second unit.

The means to draw the mounting elements one towards the other may comprise a ratchet mechanism.

Each mounting element may be provided with a plurality of apertures adapted to receive fixation wire means, each aperture being provided with fastening means, such as screw means with which to fasten fixation wire means to the mounting element.

According to a second aspect of the present invention, there is provided a method of mending a fractured bone comprising the steps of bringing together the fractured parts of the bone; applying aiming wire means supercutaneously along a desired first alignment of a plane for a reinforcing wire to be inserted across the fracture; mounting to the aiming wire means a device as described in the first aspect above; aligning said device such that one or more tube means thereof indicate a desired second alignment within the plane for the reinforcing wire; and inserting a reinforcing wire through the bone along the second alignment.

Preferably, the method comprises taking an X-ray or other scan of the fracture.

In this case, a first X-ray image may be taken while applying the aiming wire means and a second X-ray image may then be taken from a direction transverse, preferably substantially orthogonal, to the first.

The method may comprise applying a pair of support plate means, as described in the first embodiment of the first aspect above, to generally opposite sides of the bone to extend across the fracture and fastening them one to the other to maintain the reduction of the fracture.

The method may comprise the step of inserting a plurality of reinforcing wires through the bone.

At least one of said plurality of reinforcing wires may be passed into the bone so as to hold the device in position.

A remainder of the plurality of reinforcing wires are then passed into the bone and across the fracture to fixate it.

Optionally, the method comprises passing one or more cannulated fixation screws into the bone over the said reinforcing wire or wires.

The step of bringing together the fractured parts of the bone may comprise applying reduction means as described in the second embodiment of the first aspect above across the fracture and bringing the fractured parts together therewith.

The method may then comprise the step of leaving the reduction means in place during at least part of the healing ol the bone.

Embodiments of the present invention will now be more particularly described by way of example and with reference to the accompanying drawings in which: Figure I is an anterior-posterior view oi a right lower leg and ankle with malleolar fractures of both tibia and fibula; Figure 2 is an elevation oi a first, medial plate of a fixation guide device for the ankle; Figure 3 is an elevation of a second, lateral plate of the guide device of Figure 2; Figure 4A and Figure 4B are side and end elevations of a first targeting guide for use with the guide device of Figures 2 and 3; Figures 5A and 5B are side and end elevations of a second, alternative targeting guide for use with the guide device of Figures 2 and 3; Figure his an anterio-posterior view of the lower leg shown in Figure 1 with aiming wires in place on the skin adjacent each fracture; Figure 7 is an anterio-posterior view of the lower leg shown in Figure 6 with a targeting guide as shown in Figures 4A/4B engaged with each aiming wire; Figure 8 is a lateral view of the lower leg shown in Figure 6 with fixation wires implanted into the lateral malleolus of the fibula; Figure 9 is a medial view of the lower leg shown in Figure 6 with fixation wires implanted into the medial malleolus of the tibia; Figure 10 is a lateral elevation of a proximal portion of an ulna showing both upper ulnar and oleocranon fractures; Figure 11 is a plan view of a fracture reduction and stabilization apparatus embodying the invention; Figure 12 is an anterio-posterior view of a proximal part of an ulna having a fracture of the oleocranon, with the apparatus of Figure 11 in the process of being attached thereto; Figure 13 is an anterio-posterior view of the ulna shown in Figure 12 with the apparatus of F igurc 11 attached thereto and the fracture reduced; Figure 14 is a lateral view of a proximal portion of an ulna with the apparatus of Figure 11 attached across a reduced upper ulnar fracture and with the targeting guide shown in Figures 5A/5B in position; Figure 15 is a lateral view of the ulna shown in Figure 14 with a guide wire implanted across the upper ulnar fracture, and Figure 16 is a lateral view of the ulna shown in Figure 14 with a cannulated screw implanted across the upper ulnar fracture.

Referring now to the Figures, and to Figure 1 in particular, there is shown a right lower leg and ankle, having fractures of both the medial malleolus I of the tibia 2 and the lateral malleolus 3 of the fibula 4. The talus 5 of the respective foot, to which both tibia 2 and fibula 4 are articulated, is here undisplaced, although some fractures around the ankle involve talar shift, which must be corrected by the fixation procedure to be described.

Figure 2 shows a first, medially applicable, plate 6 of a fixation guide device for the ankle.

The medial plate 6 comprises a rectangular plate of radiolucent plastics material, measuring approximately twenty centimetres by five centimetres for use on an adult's ankle. A first, skin contact surface thereof has a generally semicircular depression 7 adjacent one end of one shorter edge 8. A series of substantially parallel guide grooves 9 extends obliquely across the first surface from said shorter edge 8 or adjacent thereto. An opposite surface of the medial plate 6 is plain.

A second, laterally applicable, plate] O of the ankle fixation guide device is shown in Figure 3. It also comprises a rectangular plate of radiolucent plastics material, for an adult's ankle measuring about twenty centimetres by five centimetres. A first, skin contact surface thereof is provided with a series of substantially parallel guide grooves 11 extending along the rectangular plate 10 substantially normally to its shorter edges 12. Again, an opposite surface of the plate 10 is plain.

Figures 4A and 4B show a first form of targeting guide 13 comprising an array of identical elongate guide tubes 14, each of which has a bore sized to receive snugly a desired gauge of fixation wire 15 (for the ankle, typically a 2mm K wire), as shown in Figure 4B. Each guide tube 14 comprises a radio-opaque material such as a plastics material containing radio- opaque filler. The guide tubes 14 extend parallelly, each with the others, and in a common plane (compare Figures 4A and 4B).

A second form of targeting guide 16, shown in Figures SA and 5B, is similar to the first targeting guide 13, except that it comprises an array of identical elongate guide tubes 17, each comprising a radiolucent plastics material. Each radiolucent guide tube 17 is provided with a marker wire 18 extending longitudinally within its wall. Again, the bore of each guide tube 17 is dimensioned to receive snugly a desired gauge of fixing wire 1 5, such as a 2mm K wire.

Both the first 13 and second 16 targeting guides are shown with all their guide tubes 14, 17 of the same length, which gives them greater versatility. A tube length of about three centimetres is preferred. However, targeting guides with tubes of different lengths may be preferred in some applications, thus forming a non-linear end profile which may conform more closely to a particular part of the body.

The use of the fixation guide device (including the targeting guides 13, 16) on the malleolar fractures of Figure 1 is shown in Figures 6 to 9.

The fractures are first reduced conventionally, and the medial plate 6 and lateral plate 10 of the fixation guide device are applied to the medial and lateral surfaces of the ankle respectively, their longer axes extending generally parallelly to a longitudinal axis of the lower leg. The depression 7 of the medial plate 6 locates over the medial malleolus 1 of the tibia 2, to assist in accurate location of the plate 6. The plates 6, 10 are held together with sterile tape, strapping or a compression clamp, and act as temporary external splintage to maintain reduction of the fractures during fixation.

In Figure 6, aiming wires 19, 20 have been placed over the skin of the ankle under anterio- posterior X-ray visualization, extending across each of the fractures. The plates 6, 10 and their respective guide grooves 9, 11 (not shown for clarity) allow the aiming wires 19, 20 to be aligned correctly, extending from the medial malleolus 1 to the proximal fragment of the tibia 2 and from the lateral malleolus 3 to the proximal fragment of the fibula 4, respectively.

The aiming wires 19, 20 are each taped to the skin once they indicate a correct anterio posterior alignment for a subsequent fixation wire or wires. Each aiming wire 19, 20 extends outwardly beyond a respective malleolus I, 3 as shown.

Turning first to the lateral malleolus 3, a targeting guide 13, 16 is slid over the aiming wire 2O, and is then rotated until it lies in a plane perpendicular to the anterio-posterior view shown. For the first targeting guide 13, this is when the radio-opaque guide tubes 14 are each obscured by the nearest; for the second targeting guide 16, this is when the marker wires 18 embedded in each guide tube 17 line up. The marker wires 18 may be positioned to extend along a line of contact between adjacent guide tubes 17. In this case, the correct alignment of the targeting guide 16 is shown by each of these marker wires 18 being obscured by the aiming wire 20. In either case, the guide tubes 14, 17 of the targeting guide 13, 16 are now impacted in a straight line against the lateral malleolus 3. A locating wire 21 (obscured in this view) is now passed through an unoccupied guide tube 14, 17 and the skin into the malleolus 3, to hold the targeting guide 13, 16 in position.

The ankle is now viewed under lateral X-ray visualization, as in Figure 8. Two or more fixation wires 22 are now passed through selected guide tubes 14, 17, into the lateral malleolus 3, across the fracture and into the proximal fragment of the fibula 4. The targeting guide 13, ]6 is constrained by the aiming wire 20 and locating wire 21 to remain in the correct anterio-posterior alignment, and the user may choose between the available guide tubes 14, 17 to select a suitable lateral position for each fixation wire 22.

The medial malleolus I is treated similarly. As shown in Figure 7, a targeting guide 13, 16 is mounted over the aiming wire 19 taped across the medial malleolar fracture, and is swung round to lie in a plane perpendicular to the anterio-posterior view shown. A locating wire 23 is then passed into the medial malleolus 1 to hold the targeting guide 13, 16 in alignment in the anterio/posterior direction.

The ankle is now visualised by X-ray in a lateral/medial direction, as shown in Figure 9.

Two or more fixation wires 24 are now passed through selected unoccupied guide tubes 14, 17 into the medial malleolus] and into the proximal fragment of the tibia 2 in a desired lateral orientation.

In each case, depending on the number, condition and configuration of the fragments to be fixated, cannulated screws must be inserted to follow the fixation wires 22, 24 (partially threaded 3.5mm or 4.5mm cannulated screws are generally found to be suitable for fractures around the ankle region).

Rapid and accurate percutaneous fixation can thus be achieved in situations in which it has heretofore been impractical or inconvenient. This is of particular value where open fixation is contraindicated for reasons of poor general condition of the patient, poor condition of the limb in particular, or of the skin and/or bone local to the fracture. In such cases, it has often been necessary to allow a fracture to knit without the support of internal fixation, leading to suboptimal results.

Another part of the body where fractures can cause particular problems is the proximal end of the ulna. As shown in Figure 10, the ulna 25 has a characteristic form at its proximal end to allow articulation to the distal end of the humerus (not shown). The most proximal part of the ulna 25 is the oleocranon 26. The humerus actually articulates to semi-lunar notch 27, which extends between the olecranon 26 and the coronoid process 28. The oleocranon 26 forms the "point" of the elbow and so is potentially vulnerable to impacts, which can lead to a fracture 29 of the oleocranon 26 itself, or an upper ulnar fracture 30 extending across the shalt of the ulna 25 immediately distal to the coronoid process 28.

For either fracture 29 or 30, reduction and alignment of the oleocranon 26 fragment with the ulna 25 can be difficult, as the pull of the powerful triceps muscle must be overcome.

In this situation, therefore, the targeting guides 13, 16 are used in conjunction with a fracture reduction and stabilization apparatus comprising two identical fastening elements 31, as shown in Figure 11. Each fastening element 31 comprises two collinear elongate rods 32 connected by a ratchet mechanism 33 so that they may be moved controllably one towards the other along their mutual longitudinal axis. Each rod 32 is provided at an end remote from the ratchet mechanism 33 with an array of mounting blocks 34. Each mounting block 34 has an aperture 35 extending therethrough, transversely to the rods 32, dimensioned to receive a fixation wire of preselected gauge (typically a 2mm K wire). A holding screw 36 extends through each mounting block 34 so that its tip may be brought into contact with a wire passing through the respective aperture 35, to hold the wire securely in place.

The attachment of the fastening elements 31 across a fracture 29 of the oleocranon 26 is shown in Figure 12. A heavy K wire 37 (e.g. 2mm gauge) is passed, percutaneously, through the proximal oleocranon fragment 26 from lateral to medial aspects. A second K wire 38 is passed, percutaneously, through the distal fragment of the ulna 25.

A first fastening element 31 is ol'f'ered up to a lateral surface of the forearm, and a lateral end of the oleocranon K wire 37 is inserted through a suitably located aperture 35 through a mounting block 34 and fastened in position with the corresponding holding screw 36. A lateral end of the ulna K wire 38 is similarly fastened in position within an aperture 35 of a mounting block 34 adjacent an opposite end of the fastening element 31. A second fastening element 31 is then offered up to the medial surface of the forearm, and a medial end of each K wire 37, 38 is similarly fastened thereto.

In each case, the fastening element 31 is brought into close contact with the skin, and any excess portion of the K wires 37, 38 extending beyond a respective mounting block 34 away from the forearm may be cut off and discarded. For added security of fixing, each end of each K wire 37, 38 may be bent over away from the ratchet mechanism 33 of a respective fastening element 31.

Once both fastening elements 31 are in place, the ratchet mechanisms 33 are operated to draw the two arrays of mounting blocks 34 of each fastening element 31 one towards the other.

This also draws the oleocranon 26 and ulna 25 fragments together, reducing the fracture 29 as shown in Figure 13. It is important to operate the ratchet mechanisms 33 substantially symmetrically, to ensure that the fracture 29 is reduced evenly and in the correct alignment.

The K wires 37, 38 and fastening elements 31 may be removed after fixation of the fracture 29 (see below), or may be left in position during at least the initial stages of healing. This is preferable where the bone itself is weak, for example in cases of osteoporosis or where there is severe comminution, and conventional internal fixation wires and/or screws might not be sufficiently securely anchored at first.

Once the fracture is reduced, either form of the targeting guide 13, 16 may be used to assist in implantation of fixation wires across the fracture. Figures 14 and 15 show this procedure for a reduced upper ulna fracture 30.

An aiming wire 39 is positioned on the skin of' the forearm under anterioposterior X-ray visualization, and with the elbow extended, such that it extends across the fracture 30 from the oleocranon 26 to the ulna 25. It is then taped in place.

The elbow is then viewed under lateral X-ray visualization, as shown in Figure 14 and 15; the elbow may now be partially flexed to keep the humerus clear of the procedure. A targeting guide (here the second form of targeting guide 16, comprising radiolucent guide tubes 17 provided with radio-opaque marker wires 18) is mounted over the aiming wire 39, and brought into contact with a proximal end of the oleocranon 26. One of the unoccupied guide tubes 17 is selected, the marker wire 18 of which aligns most closely with a longitudinal axis of the oleocranon 26 and ulna 25. As shown in Figure 15, a fixation wire 40 may now be passed through this guide tube 17, into the oleocranon 26, across the fracture 30 and into the ulna 25.

The targeting guide 16 is then removed, and a conventional partially threaded cannulated screw 41 can be passed over the fixation wire 40 to extend across the fracture 30, as shown in Figure 16.

The only significant incision through the skin required for this procedure is that to allow the head of the cannulated screw 41 to reach the bone 26. Otherwise, soft tissue trauma and incisions which may permit infection are kept to a minimum.

Conventional treatment of such fractures frequently requires open fixation and the implantation of metal plates across the outer surface of the bone or tension bond wiring may require subsequent open surgery lor their removal once bone healing is complete. The percutaneous approach is also advantageous where the skin is compromised (e.g. by eczema, steroid usage, anticoagulant use or fracture blisters), or where the arterial supply or the venous drainage from the limb is problematical so that open surgery incisions would be slow to heal.

In a "bag-of-bones" type fracture of the elbow, both the proximal end of the ulna and the distal end of the humerus are fractured. The humeral fracture can be fixated using the apparatus and methods of my co-pending UK application No. 0307021.6, and the ulnar fracture can be fixated as described above. As a result, each fracture will become sufficiently strong for the elbow to be mobilised much sooner than with conventional treatments. This in turn reduces the loss in triceps function which occurs during immobilization of the elbow.

I'his is particularly important for the elderly, as without triceps/elbow mobility it can be very difficult for therm even to raise themselves from a chair, for example.

The targeting guide 13, 16 may also be used on its own, for example to wire a fracture of a most distal bone of a digit. An aiming wire is taped to the skin of the digit, extending generally longitudinally thereof. The targeting guide 13, 16 is then mounted over the aiming wire and swung round until an unoccupied guide tube 14, 17 is aligned with a tip ofthe digit.

A fixation wire may then be passed down that guide tube 14, 17, into the distal fracture fragment and across the fracture into the proximal fragment.

Claims (19)

1. A device to assist in the percutaneous fixation of bone fractures comprising a plurality of elongate tube means each comprising a bore adapted to receive a fixation wire or the like of a predetermined gauge and each extending within a common plane and substantially parallelly to each other tube means.

2. A device as claimed in claim 1, wherein each said tube means is substantially identical to each other tube means.

3. A device as claimed in either claim I or claim 2, wherein each said tube means comprises a material substantially opaque to X-rays.

4. A device as claimed in either claim I or claim 2, wherein each said tube means comprises a material substantially transparent to X-rays, and is provided with elongate marker means substantially opaque to X-rays extending longitudinally thereof.

5. A device as claimed in claim 4, wherein said marker means comprises metal wire means embedded in a wall of the respective tube means.

6. A device as claimed in any one of the preceding claims, wherein each said tube means is mounted directly to its neighbour or neighbours.

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7. A device as claimed in any one of the preceding claims, comprising aiming wire means, detachably mountable to a surface of the patient's body and engageable with a tube means of the device.

8. A device as claimed in any one of the preceding claims, further comprising a pair of support plate means, mountable to extend across a fracture or fractures on generally opposite sides of a fractured limb.

9. A device as claimed in claim 8, wherein the pair of support plate means is adapted to support a reduced fracture and maintain it in reduction.

10. A device as claimed in either claim 8 or claim 9, wherein each support plate means comprises a material transparent to X-rays.

11. A device as claimed in any one of claims 8 to 10, wherein one or each support plate means is provided on at least one surface with a plurality of groove means adapted to assist in the positioning of aiming wires on the skin.

12. A device as claimed in any one of claims 8 to 11, wherein one or each support plate means is cony gured on one surface conformably with a predetermined part of a limb to aid its accurate positioning thereon.

13. A device as claimed in any one of claims 1 to 7, f urther comprising means to reduce a fracture and hold it in reduction.

14. A device as claimed in claim 13, wherein said reduction means comprises a unit I comprising two mounting elements, one mountable to bone distally of a fracture and the other mountable to bone proximally of a fracture, and means controllably to draw the mounting elements one towards the other.

15. A device as claimed in claim 14, wherein the reduction means comprises two said units.

16. A device as claimed in claim 15, wherein the two units are mountable one to the other i and to the bone by means of fixation wire means extending from each mounting element of a first unit, through a respective part of the bone, to a corresponding mounting element of a second unit.

17. A device as claimed in any one of claims 14 to 16, wherein the means to draw the mounting elements one towards the other comprises a ratchet mechanism. i

18. A device as claimed in any one of claims 14 to 17, wherein each mounting element is provided with a plurality of apertures adapted to receive fixation wire means, each aperture being provided with fastening means, such as screw means, with which to i fasten said fixation wire means to the mounting element.

19. A device to assist in the percutaneous fixation of bone fractures substantially as described herein and with reference to any one of Figures 2 to 9 and 11 to 16 of the accompanying drawings.

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