DE20217647U1 - Fixing implement for bone fractures has fixing nail with alignment guide having rigid arm with spaced holes to match hole spacing of nail - Google Patents

Abstract

The fixing implement for bone fractures has a fixing nail (20) and an alignment guide (10) to which the nail is attached at one of its ends. The other end of the nail has two fixing holes (22,24) and an outer groove (28) parallel to the hole axes. The alignment guide has a rigid arm with a free end having three parallel alignment bores (60,62,64). The outer bore has a spacing matching that of the distal fixing hole of the nail.

Description

Implantation system and target device
The invention relates to an implantation system according to claim 1.

Locking nails are widely used to treat fractures of long bones. Their use is described in "The Journal of Trauma" from 1993, Vol. 35, No. 5, pages 772 to 775. Typical for such locking nails is the arrangement of two transverse holes at one end (e.g. distal end) and at least one transverse hole (e.g. proximal end). Bone screws are passed through the transverse holes and screwed into the cortex on opposite sides. This secures the locking nail axially and against rotation.

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GerntaVBafe'rit'AttoraSys, •.fiusope'an.PateiiianS'iemmunityJrrade'Maik Attorneys ··

Approved by the European Council and the European Food Safety Authority for the

Deutsche Bank AG Hwnbu^No. 05 5««97*(BL2?2eo 700«?4} ■ PostbanRHambTirg, No. 28 42^06 (BLZ 200 100 20)

Dresdner Bank AG Hamburg, No. 933 60 35 (bank code 200 800 00)

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When using such locking nails, the position of the cross-drillings or locking holes in the locking nail must be identified so that the cortex is drilled from the outside in the right place. For this purpose, a number of targeting devices have become known, which usually work with X-rays to determine the position of the cross-drillings relative to the targeting device. If this is the case, the bone is drilled in the right place using the targeting device and a so-called drill or targeting sleeve so that the bone screws can be screwed in. Known targeting devices are usually connected to one end (e.g. proximal end) of the nail. In this way, the assignment of the locking holes to target drillings in the targeting device is approximately predetermined. However, it must be taken into account that due to the curvature of the bone and possible torsion of the nail when driving in, the assumed position of the locking holes does not correspond to the actual one.

It has therefore not been possible to identify the exact position of the locking holes using mechanical means alone.

A locking nail has become known from WOO1/60272 Al, in which an axially parallel groove is formed in the nail shaft only in the distal section in the area of the locking holes. The steering axis of the groove intersects the axis of the hole almost vertically. The mentioned publication also describes an aiming device whose aiming arm has two aiming holes. The aiming holes are in a

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the targeting arm of the targeting device, which is elastically flexible. With the help of a thin rod-like feeler, the actual position of the nail in the bone is determined using the locking holes and the groove between them. By turning the nail and moving it axially, it can be determined when the feeler is in the area of a locking hole.

It has been found that this purely mechanical procedure still causes problems for the surgeon, since he cannot always determine the actual position of the nail precisely enough by operating the feeler.

The invention is therefore based on the object of creating an implantation system or a targeting device with which the position of the locking holes can be determined in a simple manner and the holes can be drilled in the bone at the correct location.

This problem is solved by the features of patent claims 1 and 2.

The locking nail in the implantation system according to the invention has means with which the position of the locking holes can be found. One means is, for example, to arrange an axially parallel groove between the locking holes. Another possibility is to

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Circumferential grooves must be provided or, alternatively, suitable stops that can be detected by means of a sensor.

The special feature of the system according to the invention, however, is the targeting device in that the targeting arm is rigid and has a targeting section in which three targeting holes are provided. The axes of the targeting holes lie in a plane that runs in the longitudinal axis of the targeting arm or parallel to it. The distance between the outer targeting holes corresponds to the distance between the locking holes. The middle targeting hole can be located anywhere between the outer targeting holes, for example halfway along the distance. The locking nail can be detachably connected to a nail adapter, for example by means of a suitable screw connection, and the nail adapter can be detachably connected to a connecting part, which in turn can be detachably connected to the rigid targeting arm. The detachable connection of the nail adapter to the targeting arm enables the targeting device according to the invention to be used for a large number of different locking nails without a separate targeting device being required for each type of locking nail. By adjusting the adapter on the one hand and the target arm on the other, the nail can be adjusted relative to the target arm before implantation. This is done in a simple way by aligning the outer target holes of the target section of the target arm with the locking holes of the nail, for example using a calibration pin. The nail can then be implanted, whereby the nail adapter can remain attached to the nail. The locking nail is now either further inserted or

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driven further than its final position requires or less than the desired final position. The targeting device is then reassembled and the facing cortex is drilled out via the middle target hole. The targeting device is then detached from the nail adapter and a rod-like feeler is pushed through the bone hole. The feeler is pushed against the closed wall of the locking nail and, in the best case, into the groove that connects the locking holes. By turning the nail, for example, the groove can be found and it can be determined that this is actually the groove. The nail is then pulled out or driven in further until the feeler interacts with the associated locking hole. The targeting device is then reassembled and one of the outer target holes is aligned with the locking hole found. Various options are conceivable for this. A fixing sleeve is preferably used which has a front section whose diameter corresponds to the diameter of the locking hole and another section whose diameter corresponds to the target hole. The inner diameter of the fixation sleeve is dimensioned so that it can be pushed onto the rod-shaped feeler, which is still in the locking hole and the bone hole. In this way, a fairly precise alignment of a target hole with a locking hole can be achieved by reassembling the target arm and pushing one of its target holes onto the fixation sleeve. Once this has been done, the second target hole in the target arm is also aligned with the second locking hole, and the cortical bone can be removed via the second locking hole in the known manner.

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so that the locking screw can then be inserted. Once the first locking has been carried out, the second locking can also be carried out by drilling out the cortex in a known manner via the target hole used for the initial alignment in order to insert the second locking screw.

As already mentioned, the locking nail has means in the area of the locking holes that make it easier to feel the nail and palpate a locking hole. However, it is theoretically possible to do without such means, but only if the locking nail was not twisted by the diameter of the locking hole when driven in. If this is the case, the surgeon does not know how far the nail has to be pulled out or driven in until the axial position of the locking hole is reached.

For calibration, it is advantageous according to the invention if the target section is mounted so as to be pivotable about an axis perpendicular to the longitudinal axis of the target arm and has first locking means for fixing the target section in a predetermined pivot position. The pivot axis preferably lies on the axis of the target bore that is closest to the other end of the nail.

According to a further embodiment of the invention, the target section has an axially parallel slot in the area of the target holes, which is perpendicular to the axis of the

-7-Target drilling
and divides the target section into a narrower and a wider section. This creates a clamping effect when inserting a calibration pin, drill sleeve or the like, so that these parts do not accidentally slip or fall out.

According to one embodiment of the invention, calibration is further facilitated if the nail adapter is mounted in the connecting part so that it can pivot about its longitudinal axis and second locking means are provided to fix the relative pivot position. According to a further embodiment of the invention, adjustment means are provided between the connecting part and the nail adapter to adjust the relative pivot position. The adjustment means can contain, for example, an adjustment screw or the like.

The rigid aiming arm of the aiming device according to the invention is preferably designed as an elongated rod with a non-circular cross-section, which is inserted into a complementary opening in the connecting part, with one wall of the opening being formed by a clamping element that can be actuated by a clamping screw. In this way, the connecting element can be continuously adjusted axially on the aiming arm, with the rotational position remaining unchanged. Further embodiments of the invention are specified in further subclaims.

The invention is explained in more detail below with reference to drawings.

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Fig. 1 shows a targeting device according to the invention in side view. Fig. 2 shows a side view of the targeting device according to Fig. 1 rotated by 90°. Fig. 3 shows the targeting device according to Figures 1 and 2 in perspective. Fig. 4 shows the end of the targeting arm of the targeting device according to Figures 1 to 3.

Fig. 5 shows an end view of a target section of the targeting device according to Figures 1 to 3.

Fig. 6 shows a section through the representation according to Fig. 5 along the line 6-6. Fig. 7 shows an end view of the target section according to Fig. 5 rotated by 90°.

Fig. 8 shows in perspective the connection and calibration part of the target device according to Figures 1 to 3.

Fig. 9 shows the connecting part of the arrangement according to Fig. 8.

Fig. 10 shows a section through the connecting part according to Fig. 9.

Fig. 11 shows a side view of the calibration and connecting part according to Fig. 8. Fig. 12 shows a detail of the arrangement according to Fig. 11. Fig. 13 shows the side view of a calibration pin.
Fig. 14 shows the side view of a sensor.

Fig. 15 shows the side view of the sensor according to Fig. 14 rotated by 90°. Fig. 16 shows the side view of a fixing sleeve.

Fig. 17 shows the side view of a locking nail and an attached nail adapter.

Fig. 18 shows the end of a nail in another embodiment.

Fig. 19 shows another embodiment of an end of the locking nail.

Fig. 20 shows the side view of a nail adapter for the system according to the previous figures.

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Figures 1 to 3 show a target arm 10 which has a square cross-section. At the left end of the target arm 10 there is a calibration and connecting part 12, and at the right end there is a target section 14 which is pivotally mounted on a suitable bearing section 16 at the right end of the target arm 10.

Locking nails for which the targeting device according to Figures 1 to 3 can be used are shown in Figures 17 to 19. In Fig. 17, a locking nail 20 can be seen, for example a femoral nail. It has two axially spaced locking holes 22, 24 at the distal end and a locking hole 26 at the proximal end. An axially parallel groove 28 of, for example, a U- or V-shaped cross-section extends between the locking holes 22, 24. The diameter of the locking holes 22 to 26 is the same. In the example shown, the proximal end of the locking nail 20 is connected to an elongated nail adapter, namely with the aid of a screw 32 that can be screwed into the proximal end of the nail 20. The nail adapter has opposing flats 34 at the other end.

In Fig. 18, the end of a locking nail 43 is shown with locking holes 40, 41 and circumferential grooves 50, 52 in the area of the locking holes 40, 41. In Fig. 19, locking holes 41, 40a are shown, which are formed in a reduced-diameter distal end section of the locking nail 43a. To the left of the locking holes 40a, 41a, a radially diameter collar 56, 58 is formed.

whereby the collar 58 is bevelled towards the left end. The function of the nail formations shown will be discussed further below.

As can be seen in particular from Figures 5 to 7, the target section 14 has three target bores 60, 62, 64, the axes of which lie in a plane that passes through the longitudinal axis of the target arm 10 or runs parallel to it. The axial distance of the outer target bores 60, 64 corresponds to the distance of the locking holes 22, 24, or 40, 41, or 40a, 41a. As can be seen from Figures 6 and 7, the target section 14 has a first relatively wide slot 66, the width of which is slightly larger than the width of the bearing section 16. As can be seen from Fig. 4, the bearing section is fork-shaped with arms 70, 71, which have between them an extension 72 near the ends of the arms 70, 71 and an arcuate transverse slot 74 at the end of the arms 70, 71. From Figures 6 and 7 it can be seen that the slot 66 is penetrated by the shaft of a locking screw 76, the diameter of the shaft being slightly smaller than the width of the arcuate slot 74 of the bearing section 16. At the inner end, the slot 66 is penetrated by a bearing sleeve 68. If the bearing section 16 is inserted into the slot, the shaft of the locking screw 76 enters the arcuate slot 74 and the sleeve 68 enters the extension 72. The target section 14 is thus mounted in the bearing section 16 so as to be pivotable about the axis of the sleeve 68. The relative pivot position is determined by the locking screw 76.

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By means of a relatively narrower slot 78, which is introduced from the free end of the target section 14, the target section 14 is divided into a relatively wide section 80, which has the slot 66, and a relatively narrower section 82. The latter is bendable to a limited extent relative to the former and has bores which are aligned with the target bores 60 to 64.

Figures 8 to 10 show a connecting part 84 by means of which the nail adapter can be held adjustably and detachably on the target arm 10, for example according to Figure 17. The connecting part 84 has a square opening 86 with a cross-section that corresponds to the cross-section of the target arm 10. A clamping section 88 is slidably mounted in the connecting part 84 and forms a corner section of the opening 86. The section 88 is actuated by a clamping screw 90 that acts on a relatively thin section 92 of the section 88 that is separated from the rest of the section 88 by a slot to obtain a yielding effect. A pin 94 that sits in a groove in the section 88 limits the adjustment of the section 88.

The connecting part 84 also has a bearing sleeve 96, the axis of which runs perpendicular to the axis of the receiving opening 86. A slot 98 is formed in the bearing sleeve 96, which has a certain extension in the circumferential direction. Furthermore, a pin 100 is inserted in the press fit, which protrudes slightly beyond the interior of the bearing sleeve 96.

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In Fig. 11, the other side of the calibration and connecting part according to Fig. 8 is shown in side view. In Fig. 12, a sleeve section 102 can be seen which has a slot 104 which extends partially in the circumferential direction. The sleeve section 102 is dimensioned such that it can be inserted into the bearing sleeve 96, wherein the slots 98 and 104 can at least partially coincide. At one end of the sleeve section, an arm 106 is attached, which pivotally supports an adjusting screw 110 at 108, which is provided with a cylindrical toggle 112 which has an internal thread. The screw 110 is operated via a rotary knob 114. Opposite the arm 106, at the same end of the sleeve section 102, an arm 116 is formed which has a curved slot 118 which is open on one side. Inside the sleeve section 102 there is another sleeve section 120, onto which an arm 122 is formed. At the free end of the arm 122 there is a circular recess 124 which accommodates the round toggle 112. When the knob 114 is turned, a relative pivoting takes place between the arms 108 and 122. A knob 126 operates a locking screw 128 which engages in a threaded hole (not shown) in the sleeve section 120. The shaft of the screw 128 extends through the slots 98 and 104 of the bearing sleeve 96 and the sleeve section 102. The sleeve section 120 has a non-circular opening 130 for receiving the end section of the nail adapter 30. The axial position of the nail adapter in the opening 130 can be fixed with the aid of the locking screw 128. By pivoting the arm

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122 relative to the connecting part 84, the nail adapter can be rotated about its axis and in doing so pivot the nail 20. The relative pivoting position of the sleeve section 102 or the arms 106 and 116 with respect to the connecting part 84 is effected by the locking screw 90, the shaft of which extends through the curved slot 118.

In Fig. 13, a calibration pin 132 is shown with a left section 134 of smaller diameter and a relatively long section 136 of larger diameter. The diameter of the section 134 corresponds to the diameter of the locking bores 26, 24 or 40, 41 or 40a, 41a. The diameter of the section 136 corresponds to the diameter of the target bores 60, 62 or 64.

In Figures 14 and 15, a feeler 138 is shown which has a circular cross-section along its length and a relatively small diameter, which is significantly smaller than the diameter of the locking holes. At one end, the feeler 138 is bevelled, as shown at 140, to form a kind of cutting edge. At the other end, the feeler pin 138 has opposite flats 142 for the purpose of clamping in a handle section (not shown).

In Fig. 16, a fixing sleeve 144 is shown with a section 146, the outer diameter of which corresponds to the diameter of the locking holes 22, 24 or 41, 40, 41a, 40a. A section 148 has a larger diameter, which corresponds to the diameter

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which corresponds to the target bores 60 to 64. At the right end, the target sleeve 144 is provided with a clamping section 150 for the purpose of detachable connection to a handle. The target sleeve 144 has a continuous axial bore of a diameter such that the feeler pin 138 can be inserted through it approximately snugly.

The nail adapter 160 shown in Fig. 20 has a shaft 162 whose cross section is complementary to the cross section of the opening 130 in the connecting part 84 (see e.g. Fig. 8). An adapter section 164 is attached to the left end of the shaft 162 by means of a screw connection (not shown). It has two projections 166 at the free end which engage in corresponding recesses in the nail (not shown here) in order to specify its rotational position. The nail is then attached to the adapter 160 by means of a screw connection which extends through the hollow section 164.

At 168 and 170, holes are indicated through the shaft 182, which can also be used as target holes.

The implantation system described is used as follows. First, calibration is carried out. The nail to be implanted, for example the nail 20 according to Fig. 17, is connected to the nail adapter 30. The nail adapter 30 is inserted into the opening 130 of the connecting part and is secured with the aid of the clamping screw 126

By axially adjusting the connecting part 84 on the target arm 10 and if necessary by pivoting the nail by operating the adjusting screw 114, the locking holes 22, 24 are aligned with the target holes 60, 64. First, alignment with respect to the target hole 60 is carried out by passing a calibration pin through it as shown in Fig. 13. Optionally, a drill guide sleeve and a drill can also be used for this purpose. In this process, the section 134 of the calibration pin 132 enters the locking hole 22. The target section 14 is then pivoted until the target hole 84 is also aligned with the locking hole 24, which can be determined using the calibration pin. The target section 76 is then fixed in the pivoted position it has adopted using the locking screw 76. The position of the nail was previously set using the clamping screw 126, the locking screw 90 and the adjustment screw 114. The nail adapter 30 is then removed by loosening the clamping screw 126 and the locking nail 20 is driven into the bone in the usual way, for example from proximally into the femoral canal. The nail adapter 30 remains attached to the locking nail 10. The locking nail 20 is driven in a certain distance further than the desired end position. This excess corresponds to a distance that is smaller than the distance between the locking holes 22, 24. After the nail has been driven in, the target arm 10 is attached to the nail adapter 30 in the manner already described. Now a hole is drilled through the middle target hole 62 into the facing cortex of the bone using a suitable drill sleeve and, if necessary, a tissue protection sleeve.

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It must be avoided that the drill comes into contact with the nail 20. Once this has happened, the targeting device is then removed from the nail adapter again and an attempt is made to feel the groove 28 with the help of the feeler 138, which is inserted through the bone hole. If this is not the case, the groove 28 can be felt by slightly turning the nail 20 in the bone canal. As soon as this is the case, the nail 20 is pulled out slightly until the feeler 22 feels the locking hole 24. If this is the case, the fixing sleeve 16 is pushed over the feeler 138. The section 146 thereby passes through the bone hole into the locking hole 24. With the locking sleeve 144 seated in this way, the targeting device is then reassembled, with the target hole 64 being aligned with the fixing sleeve 144. Once the targeting device has been attached, the inner target hole 60 is automatically aligned with the inner locking hole 22. Now, using the usual methods, the bone can be drilled on opposite sides of the locking hole 22 and a locking screw can be inserted to fix the nail in the bone. Once this has been done, the cortical bone can also be drilled on the other side by removing the fixation sleeve 144 and using the usual methods in order to insert a locking screw in this area as well.

As soon as the distal locking is completed, locking in the area of the proximal locking hole 26 can also be carried out in a known manner.

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Claims (19)

1. Implantation system comprising at least one locking nail and a target device, wherein the locking nail is designed at one end for detachable attachment to the target device, has two locking holes at the other end and an outer axially parallel groove connecting the locking holes or circumferentially extending depressions or elevations in the region of the locking holes, and wherein the target device has a rigid target arm with a free end section which has three target holes arranged in an axially parallel plane, of which the outer target holes are at a distance from one another that corresponds to the distance between the distal locking holes of the locking nail, furthermore a connecting part which can be moved on the target arm but can be fixed in any position, wherein the connecting part has a receiving opening for a detachable attachment of a rod-like nail adapter, which in turn has means for detachably attaching the locking nail. 2. A targeting device for a locking nail, which can be detachably connected to the targeting device at one end and has two spaced locking holes at the other end, with a targeting arm which extends approximately parallel to the locking nail and has an end section with target holes which can be aligned with the locking holes of the locking nail attached to the targeting device, characterized by the following features: - an elongated nail adapter ( 30 ) to which the nail ( 20 ) can be detachably fastened and which is slidably and lockably received in a receiving opening ( 130 ) of a connecting part ( 84 ) between the nail adapter ( 30 ) and the target arm ( 10 ), - the aiming arm ( 10 ) is rigid and longitudinally displaceable and lockable in a further opening ( 86 ) of the connecting part ( 84 ) - the end section ( 14 ) has three target bores ( 60 , 62 , 64 ) whose axes lie in a plane which extends through or parallel to the axis of the target arm ( 10 ), the distance between the two outer target bores ( 60 , 64 ) corresponding to the distance between the locking holes ( 22 , 24 ). 3. System according to claim 1, characterized in that the target section ( 14 ) is mounted pivotably about an axis perpendicular to the longitudinal axis of the target arm ( 10 ) and has first locking means ( 76 ) for fixing the target section ( 14 ) in the predetermined pivot position. 4. System according to claim 3, characterized in that the pivot axis coincides with the axis of the inner target bore ( 60 ). 5. System according to one of claims 1 to 4, characterized in that the target section ( 14 ) in the region of the target bores ( 60 to 64 ) is divided by an axially parallel slot ( 78 ) perpendicular to the axis of the target bores into a narrower section ( 82 ) and a wider section ( 80 ). 6. System according to one of claims 1 to 5, characterized in that the nail adapter ( 30 ) is mounted in the connecting part so as to be pivotable about its longitudinal axis and second locking means determine the relative pivoting position of the nail adapter and the connecting part to one another. 7. System according to claim 6, characterized in that adjustment means ( 110 , 114 ) are provided between the connecting part and the nail adapter ( 30 ) for adjusting the relative pivot position. 8. System according to one of claims 1 to 7, characterized in that the aiming arm ( 10 ) is designed as a rod with a non-circular cross-section which extends through a complementary opening ( 86 ) of the connecting part ( 84 ), wherein a wall of the opening ( 86 ) is formed by a clamping element ( 88 ) which can be actuated by a clamping screw ( 90 ). 9. System according to one of claims 1 to 8, characterized in that the nail adapter has a non-circular shaft section which is slidably and lockably received in a complementary receiving opening ( 130 ) of a sleeve section ( 120 ), the sleeve section ( 120 ) is rotatably received in a bearing sleeve ( 96 ) of the connecting part ( 84 ), the axis of which runs approximately perpendicular to the axis of the other opening ( 86 ) of the connecting part ( 84 ), and third locking means are provided which fix the relative rotational position of the sleeve section and the bearing sleeve. 10. System according to claim 9, characterized in that a first arm ( 122 ) is connected to the first sleeve section ( 120 ), a second sleeve section ( 102 ) is arranged between the bearing sleeve ( 96 ) and the first sleeve section ( 120 ), which is provided with a second arm ( 108 ), the second sleeve section ( 102 ) has a third arm ( 116 ) which can be fixed in different pivot positions on the connecting part ( 84 ), and an adjusting screw is arranged between the first and second arms ( 122 , 108 ) for adjusting the distance between the arms ( 108 , 122 ). 11. System according to claim 10, characterized in that the third arm ( 116 ) has an arcuate slot ( 118 ) through which a locking screw extends, which engages in a threaded bore of the threaded part ( 84 ). 12. System according to claim 11, characterized in that the locking screw ( 90 ) simultaneously fixes the aiming arm ( 10 ) to the connecting part ( 84 ) in the lapping and pivoting direction. 13. System according to claim 10, characterized in that a second locking screw extends through the bearing sleeve ( 96 ) and the second sleeve portion ( 102 ) and sits in a threaded bore of the first sleeve portion ( 120 ) to secure the nail adapter ( 30 ). 14. System according to one of claims 1 to 13, characterized in that a calibration pin ( 132 ) is provided with an end portion ( 134 ) whose diameter corresponds to the diameter of the locking holes ( 22 , 24 ), while the remaining shaft ( 136 ) has a diameter which corresponds to the diameter of the target bores ( 60 to 64 ). 15. System according to one of claims 1 to 14, characterized in that a feeler pin ( 138 ) is provided, the outer diameter of which is smaller than the diameter of the locking holes ( 20 , 24 ) and has a tip or a cutting edge ( 140 ) at one end. 16. System according to one of claims 1 to 15, characterized in that an elongate fixing sleeve ( 144 ) is provided, the inner diameter of which corresponds to the outer diameter of the feeler pin ( 138 ), which has a front section ( 146 ) whose outer diameter corresponds to the diameter of the locking holes ( 22 , 24 ) and a section ( 148 ) whose outer diameter corresponds to the diameter of the target bores ( 60 to 64 ). 17. System according to one of claims 12 to 16, characterized in that the connecting part ( 84 ) has a clamping element ( 88 ) which engages the target arm ( 10 ) and has a yielding section against which the locking screw ( 90 ) rests. 18. System according to claim 17, characterized in that the yielding portion is formed by a slot ( 92 ). 19. System according to one of claims 1 to 18, characterized in that the pivot axis of the target arm ( 10 ) and the connecting part ( 84 ) are in the same plane as the longitudinal axis of the nail.