DE20200705U1 - Intramedullary osteosynthesis implant - Google Patents

Description

A 56 537 u Aesculap AG & Co. KG

u - 223/248 Am Aesculap Platz

17 January 2002 78532 Tuttlingen

INTRAMEDULLAR SOSTEOSYNTHESIS IMPLANT

The invention relates to an intramedullary osteosynthesis implant with a plate that can be inserted into the medullary cavity of a bone and has several openings for receiving bone fixation elements.

Such intramedullary osteosynthesis implants are used to reposition fractures in the joint and metaphyseal area of a long bone, for example on the distal radius or on the distal tibia. For this purpose, locking nails are known that have a head section that is bevelled on one side and is detachably or integrally connected to the shaft and that, like the shaft of the locking nail itself, is essentially circular-cylindrical in shape (WO 99/20195).

It is also known to fix the parts of the long bone to be repositioned using screw-like bone fixation elements that are passed through openings in a bone plate (angle-stable plate for distal radius from Königssee Implantate und Instrumente für Osteosynthese GmbH, US-4,790,302). It is difficult to attach these plates to the long bone itself in order to ensure a secure connection between the long bone and the fragments.

A 56 537 u
17 January 2002
u-223/248

It is the object of the invention to design a generic intramedullary osteosynthesis implant in such a way that, on the one hand, it is suitable for accommodating as many bone fixation elements as possible for fixing the bone fragments and, on the other hand, can nevertheless be inserted into the respective bone in a space-saving and positionally stable manner.

This object is achieved according to the invention in an intramedullary osteosynthesis implant of the type described above in that the plate carries a shaft at one end which has at least one locking bore running transversely to its longitudinal axis.

This shaft can be inserted into the medullary cavity of the long bone like a known locking nail and secured there by locking elements. The osteosynthesis implant described thus provides a component that on the one hand has the properties of a locking nail for securing the implant, but on the other hand has the properties of a bone plate in the area of the bone fragments to be repositioned with the option of securing the bone fragments using a larger number of bone fixation elements, whereby the entire implant is inserted intramedullary, i.e. the plate is located inside the bone fragment area to be repositioned.

According to a first preferred embodiment, the plate can be flat, but it is also possible for it to be curved, either in the longitudinal direction or in the transverse direction.

A 56 537 u
17 January 2002
u-223/248

The plate is usually between 1 mm and 5 mm thick, with a thickness of around 2 mm being particularly advantageous. The choice of thickness also depends on the anatomy of the long bone to be treated, so the surgeon can choose the right thickness for optimal treatment.

The shaft can be inclined relative to the plate, with the angle of inclination preferably being between 10° and 60°; a particularly advantageous arrangement is obtained with an inclination in the order of 30°.

The inclination can occur in a plane that runs perpendicular to the extension of the plate, but it is also possible for the inclination to occur in a plane that runs in the extension of the plate; these two inclinations can also be combined if necessary.

The plate can be rotated relative to the shaft about an axis passing through the connection point between the shaft and the plate and lying in the plane of the plate.

All these inclination and rotation options serve to optimally adjust the relative arrangement of the shaft and plate, so that when a shaft is inserted into the medullary cavity of a long bone, the plate can be adjusted according to the anatomy of the bone to be treated.

A 56 537 u
17 January 2002
u-223/248

and can be optimally arranged according to the course of the fracture surfaces.

The plate can have an oval outer edge, giving it a contour whose longitudinal extension between the shaft on the one hand and the distal end of the locking nail on the other is greater than the width extension running across it. The contour can be directly oval-shaped or can be approximated by an outer edge with straight or only slightly curved sections. It is advantageous if the length of the plate from the shaft end to the opposite end is between 1 cm and 15 cm; a length of around 8 cm is particularly advantageous. Here, too, it is sensible to adapt the length to the anatomy of the indication being treated.

The maximum width of the plate can be between 0.5 cm and 5 cm. The dimensions should preferably be chosen so that the plate is completely accommodated inside the bone and does not break through the bone wall at any point. Depending on the size and shape of the long bone to be treated, very different dimensions are possible. For example, a dimension of 1 cm can be suitable for a radius, 1.5 cm for the distal tibia and about 3 cm for the proximal tibia.

In a preferred embodiment, it is provided that in the plate in its transverse direction at least two openings for bone fixation elements are arranged next to each other, i.e. the width of the

A 56 537 u
17 January 2002
u-223/248

The plate is selected so that at least two such openings can be placed next to each other.

The openings can be designed so that bone fixation elements can be inserted through them essentially parallel to one another, but in a particularly preferred embodiment it is provided that the longitudinal axes of several openings designed as cylindrical bores are inclined relative to one another. As a result, the inserted bone fixation elements are forcibly held in a position inclined relative to one another in the bone and can thus stabilize the individual bone fragments particularly effectively.

For example, the longitudinal axes of the openings can be inclined such that the tips of the bone fixation elements protruding through these openings converge.

It is advantageous if the longitudinal axes of the openings are inclined relative to one another in such a way that bone fixation elements inserted into the openings cross over in a projection plane running transversely to the longitudinal axis of the shaft. To be more precise, the projections of the bone fixation elements cross over in this projection plane.

It is also advantageous if the longitudinal axes of the openings are inclined towards each other in such a way that bone fixation elements inserted into the openings are positioned in a direction defined by the longitudinal axis of the shaft.

-6-

A 56 537 u
17 January 2002
u-223/248

nated projection plane without crossing over. The convergence is therefore only so large that no crossing over of the bone fixation elements occurs.

In a modified embodiment, at least two openings are provided whose longitudinal axes diverge in a projection plane running transversely to the longitudinal axis of the shaft, so that bone fixation elements inserted into these openings do not cross each other.

The bone fixation elements can be simple pins, but they are advantageously bone screws, in particular self-tapping bone screws.

It is advantageous if the bone fixing elements designed as bone screws have a larger thread in the area of a screw head than in the rest of the area. Larger can be understood both in terms of the diameter and in terms of the geometry of the screw threads, so that such a bone screw with its area near the head is held securely and fixed in its angular position in the outer wall of the bone when fully screwed in. This results in particularly good stability of the repositioned bone fragments.

The openings can have an internal thread, which also contributes to stabilization.

A 56 537 u
17 January 2002
u-223/248

In a first preferred embodiment, the shaft can be designed to be straight, but it is also possible for the shaft to be curved at least in some areas in order to achieve optimal adaptation to the geometry of the bone cavity.

In a preferred embodiment, the plate has an engagement area for a handling tool at its end opposite the shaft. The handling tool can be firmly connected to the plate in this engagement area, so that the osteosynthesis implant is practically connected to a handle or an impact instrument, with the aid of which the osteosynthesis implant can be brought into the desired position in the bone.

It is particularly advantageous if the handling tool includes a collet that can be placed on the area of application and clamped around it. It is then possible to firmly connect the handling tool to the osteosynthesis implant by tightening the collet; this connection can be easily removed again by loosening the collet.

In particular, it can be provided that the handling tool is connected to a drilling jig which, when the handling tool is in contact with the attack area, has openings for a drilling tool which are aligned with the openings in the plate and/or the shaft. This then produces a structural unit from the

• · · · ' ¹ JJ ₁ ¹

-8th-

A 56 537 u
17 January 2002
u-223/248

Osteosynthesis implant, the handling tool and the drilling jig, this assembly comprises rigidly connected components and not only enables the surgeon to bring the osteosynthesis implant into the desired position, but also ensures that the surgeon can use the drilling jig to drill holes in the bone that are aligned with the openings in the plate and/or the openings in the shaft. The connection between the handling tool and the osteosynthesis implant can then be separated again.

The following description of preferred embodiments of the invention serves to explain in more detail in conjunction with the drawing. They show:

Figure 1: a side view of a very schematically shown

long bone with an osteosynthesis implant comprising a plate and a shaft with a large number of bone screws penetrating the plate;

Figure 2: a plan view of the bone of Figure 1;

Figure 3: a side view of an intramedullary osteosynthesis

implant with a straight shaft and a flat plate in side view;

-9 -

A 56 537 u
17 January 2002
u-223/248

Figure 4: a front view of the osteosynthesis implant of the

Figure 3 with inserted, converging bone screws;

Figure 5: a view of the plate of the osteosynthesis implant

Figure 4 with bone screws diverging in the laterally direction and converging in the longitudinal direction;

Figure 6: a modified embodiment of an intramedullary

lary osteosynthesis implant with a curved shaft and parallel openings for bone fixation elements in the plate;

Figure 7: a plan view of the osteosynthesis implant of Figure 6;

Figure 8: a view similar to Figure 3 with a sideways inclined

Plate;

Figure 9: a plan view of the osteosynthesis implant of Figure 8;

Figure 10: a view similar to Figure 8 with a plate rotated about its longitudinal axis;

Figure 11: a plan view of the osteosynthesis implant of Figure 10;

- 10-A
56 537 u
17 January 2002
u-223/248

Figure 12: a schematic side view of an osteosynthesis implant inserted into a long bone and a handling tool connected to it;

Figure 13: a front view of the upper part of the handling tool of Figure 12 and

Figure 14: an enlarged longitudinal sectional view of the handling tool of Figure 12 in the connection area with the plate of the osteosynthesis implant.

The intramedullary osteosynthesis implant shown in Figures 1 to 5, hereinafter referred to as implant 1, comprises a straight shaft 2 with a circular cross-section and a length between 1 cm and 30 cm, whereby this length is adapted to the respective anatomical conditions, and with a flat, level plate 3 adjoining this shaft 2, which is angled by approximately 30° with respect to the longitudinal axis of the shaft 2 in a plane running perpendicular to the plane of the plate 3. The plate 3 has a width which, in the embodiment shown, corresponds to approximately three times the diameter of the shaft 2, and a length which is significantly greater than the width, for example the plate 3 is twice as long as it is wide. The outer contour is formed approximately oval by bevels 4 at the opposite ends of the plate 3, whereby

- 11 A
56 537 u
17 January 2002
u-223/248

the oval shape is approximated by shorter straight boundary lines (Figure 4).

The diameter of the shaft 2 is approximately between 2 mm and 12 mm and the thickness of the plate is between 1 mm and 5 mm. These dimensions are preferably individually adapted to the anatomy of the respective indication to be treated and the resulting biomechanical loads. For example, the diameter of the shaft can be around 4 mm for the radius, 6 mm for the distal tibia or 10 mm for the proximal tibia, the thickness of the plate can be 2 mm for the radius, 3 mm for the distal tibia or 4 mm for the proximal tibia. Of course, these dimensions can also be changed according to individual differences.

The shaft and plate are preferably designed as one piece, but it is also possible to design the shaft and plate as independent components that are connected to one another. In this case, it is possible to combine shafts and plates of different dimensions and shapes as required. In particular, kits with different shaft geometries and different plate geometries can be used, from which the surgeon selects the necessary individual parts and then combines them to form the desired intramedullary osteosynthesis implant.

The osteosynthesis implant is usually made of the usual metallic materials, for example titanium or a titanium

- 12 -

A 56 537 u

17 January 2002

u-223/248

alloy, but plastics can also be used, for example the osteosynthesis implant can consist of polyetheretherketone or other biocompatible plastics, in particular resorbable plastics.

In the shaft 2, two locking holes 5 are arranged at a distance from one another, penetrating transversely through the shaft 2, and in the plate 3 there are a large number of holes 6, which are at least partially designed as internally threaded holes. These holes 6 are distributed over the surface of the plate both longitudinally and transversely, and the longitudinal axes of the holes 6 are inclined towards one another in the embodiment shown in Figures 1 to 5. In a longitudinal plane in which the longitudinal axis of the shaft 2 runs, the longitudinal axes of the holes 6 converge in such a way that bone screws 7 inserted into the holes 6 converge towards one another, but do not cross over or touch one another (Figure 1). In a plane running transversely to the longitudinal axis of the shaft 2, the holes 6 can converge more strongly, so that bone screws 7 inserted into the holes cross over one another in this plane (Figure 2). However, it is also possible for the longitudinal axes of bores 6 to diverge, so that bone screws 7 inserted through them diverge in the transverse plane running transversely to the longitudinal axis of the shaft 2 (Figure 5). In this embodiment of Figure 5, the diverging arrangement in the transverse plane is therefore combined with a converging arrangement in the longitudinal plane.

Φ ft t f. · S φ mm

- 13-A
56 537 U
17 January 2002
u-223/248

The implant 1 is inserted with its shaft 2 into the medullary cavity of a long bone 8 until the plate 3 is completely positioned inside the bone, in the area of the head of this bone. After insertion, the implant 1 can be secured in the long bone 8 by locking screws (not shown in the drawing), which are screwed from the outside of the long bone 8 through the bone wall and then through the locking holes 5 of the shaft 2. The bone fragments to be repositioned and fixed to the long bone 8 can be secured to the plate 3 by bone screws 7; for this purpose, the bone screws 7 are screwed through the bone fragments and the holes 6. The large number of holes 6 and their different orientations give the surgeon a variety of positioning options for bone screws, so that optimal adaptation to the different geometries of the fracture parts is possible. Preferably, the bone screws 7 have a threaded area with larger dimensions adjacent to their screw heads 9, either due to a larger diameter or due to larger dimensions of the screw threads, so that the screwed-in bone screw 7 is securely fixed and angularly fixed in the stable outer wall of the long bone 8 by this enlarged threaded area. This results in the bone screw being fixed on the one hand by the outer wall of the bone and on the other hand by the plate 3 inside the bone. This fixation is particularly effective when the bore 6 is designed as an internally threaded bore.

- 14-A
56 537 u
17 January 2002
u-223/248

In this design, the versatility that is made possible by bone plates in osteosynthesis is combined with the secure fixation of the plate inside the bone by the shaft 2, thus resulting in an implant 1 that combines the advantages of a bone plate and a locking nail. What is particularly advantageous in this design is that the bone plate can be positioned inside the bone, thus avoiding irritation of the surrounding soft tissue, which cannot be avoided when using external bone plates.

The embodiment shown in Figures 6 and 7 is constructed similarly to that of Figures 1 to 5, corresponding parts therefore bear the same reference numerals.

In the embodiment of Figure 6, the holes 6 are aligned parallel to one another, with the longitudinal direction running approximately perpendicular to the longitudinal axis of the shaft 2, i.e. inclined relative to the inclined plate 3 at an angle that approximately corresponds to the angle of inclination of the plate relative to the shaft. In addition, the outer contour of the plate 3 in this embodiment is oval, i.e. not only approximated to an oval by straight sections, but precisely oval in shape.

Finally, in this embodiment, the shaft 2 is not straight but is bent in its distal area, this

- 15-A
56 537 u
17 January 2002
u-223/248

However, bend 10 runs in the same direction as the inclination of plate 3.

The embodiment of an osteosynthesis implant shown in Figures 8 and 9 largely corresponds to that of Figures 3 and 4, corresponding parts therefore have the same reference numerals. In this embodiment, the plate 3 is inclined relative to the shaft 2 not only in a plane that is perpendicular to the surface of the plate 3, but also in the plane of the plate 3.

In the embodiment of Figures 10 and 11, which in turn is similar to that of Figures 3 and 4 and is therefore identified by the same reference numerals, the plate 3 is rotated about its longitudinal axis relative to the shaft 2, i.e. about an axis which runs through the connection point between the shaft 2 and the plate 3 and describes the longitudinal central axis of the plate 3.

The different inclinations and angular positions of the plate 3 relative to the shaft 2 shown in the embodiments can be combined with one another, so that overall the plate 3 can assume any position relative to the shaft 2, which is selected by the surgeon depending on the anatomical conditions.

All of the above-described features of the implant 1 can be implemented together or individually; it is also possible to combine the configurations of all embodiments with one another.

- 16-A
56 537 U
17 January 2002
u-223/248

, for example the shaft shape, the plate shape, the relative arrangement of plate and shaft and the different dimensions of plate and shaft. The shaft can have any cross-section, for example a circular, oval, trihedral or tetrahedral cross-section with rounded edges.

In order to be able to bring the implant 1 into the desired position in the long bone, a handling tool 11 can be used, as shown in Figures 12 to 14. This handling tool 11 comprises an elongated housing 12 with a through hole 13 through which a threaded spindle 14 is passed. This has at one end a collet-like fork 15 with two parallel prongs 16, 17, which can be placed on the plate 3 on opposite sides at the upper end of the plate 3, i.e. at the end of the plate 3 opposite the shaft 2, so that the plate 3 is received in a contact area 18 located between the prongs 16, 17 between the prongs 16 and 17. To clamp the prongs 16, 17, the collet 15 can be drawn into the housing 12 by means of the threaded spindle 14, namely by means of an adjusting nut 19 supported on the housing 12 and screwed onto the threaded spindle 14, and the outer sides of the prongs 16, 17 increasingly come into contact with clamping surfaces 20 of the housing 12, which press the prongs 16, 17 together when the collet 15 is pushed in between the clamping surfaces 20. In this way, it is possible to produce a rigid clamping connection between the handling tool 11 and the implant 1.

- 17-A
56 537 u
17 January 2002
u-223/248

A drilling jig 21 is held on the side of the housing 12, which extends essentially parallel to the implant 1 when the latter is held in the collet 15, in such a way that openings 22 in the drilling jig 21 are aligned with the holes 6 in the plate 3 and with the locking holes 5 in the shaft 2. It is thus possible, using the drilling jig 21, to drill holes in the long bone 8, which are also aligned with the locking holes 5 and the holes 6 and thus enable bone screws 7 to be inserted.

The representation of Figures 12 to 14 is schematic, it is understood that the collet 15 is to be placed on the contact area 18 of the plate 3 in a precisely defined position in order to achieve alignment of the openings 22 with the holes 6 and the locking holes 5, this can be achieved by suitable stops or by a positive connection between the parts of the handling tool 11 on the one hand and the plate 3 on the other hand, but this is not shown in the drawing.

Claims (26)

1. Intramedullary osteosynthesis implant with a plate which can be inserted into the medullary cavity of a bone and has a plurality of openings for receiving bone fixation elements, characterized in that the plate ( 3 ) carries a shaft ( 2 ) at one end which has at least one locking bore ( 5 ) running transversely to its longitudinal axis. 2. Osteosynthesis implant according to claim 1, characterized in that the plate ( 3 ) is flat. 3. Osteosynthesis implant according to claim 1 or 2, characterized in that the plate ( 3 ) has a thickness between 1 mm and 5 mm. 4. Osteosynthesis implant according to one of the preceding claims, characterized in that the shaft ( 2 ) is inclined relative to the plate ( 3 ). 5. Osteosynthesis implant according to claim 4, characterized in that the angle of inclination is between 15° and 60°. 6. Osteosynthesis implant according to claim 4 or 5, characterized in that the inclination occurs in a plane which is perpendicular to the extension of the plate ( 3 ). 7. Osteosynthesis implant according to one of claims 4 to 6, characterized in that the inclination occurs in a plane which runs in the extension of the plate ( 3 ). 8. Osteosynthesis implant according to one of the preceding claims, characterized in that the plate ( 3 ) is rotated relative to the shaft ( 2 ) about an axis passing through the connection point between the shaft ( 2 ) and the plate ( 3 ) and lying in the plane of the plate ( 3 ). 9. Osteosynthesis implant according to one of the preceding claims, characterized in that the plate ( 3 ) has an oval outer edge. 10. Osteosynthesis implant according to one of the preceding claims, characterized in that the length of the plate ( 3 ) from the shaft end to the opposite end of the plate ( 3 ) is between 1 cm and 15 cm. 11. Osteosynthesis implant according to one of the preceding claims, characterized in that the maximum width of the plate ( 3 ) is between 0.5 cm and 5 cm. 12. Osteosynthesis implant according to one of the preceding claims, characterized in that in the plate ( 3 ) in its transverse direction at least two openings ( 6 ) for bone fixation elements ( 7 ) are arranged next to one another. 13. Osteosynthesis implant according to one of the preceding claims, characterized in that the longitudinal axes of several openings ( 6 ) designed as cylindrical bores are inclined relative to one another. 14. Osteosynthesis implant according to claim 13, characterized in that the longitudinal axes of the openings ( 6 ) are inclined such that the tips of the bone fixation elements ( 7 ) projecting through these openings ( 6 ) converge. 15. Osteosynthesis implant according to claim 14, characterized in that the longitudinal axes of the openings ( 6 ) are inclined towards each other such that bone fixation elements ( 7 ) inserted into the openings ( 6 ) cross over in a projection plane running transversely to the longitudinal axis of the shaft ( 2 ). 16. Osteosynthesis implant according to claim 14 or 15, characterized in that the longitudinal axes of the openings ( 6 ) are inclined towards each other such that bone fixation elements ( 7 ) inserted into the openings ( 6 ) converge in a projection plane defined by the longitudinal axis of the shaft ( 2 ) without crossing over. 17. Osteosynthesis implant according to claim 13, characterized in that at least two openings ( 6 ) are provided, the longitudinal axes of which diverge in a projection plane running transversely to the longitudinal axis of the shaft ( 2 ). 18. Osteosynthesis implant according to one of the preceding claims, characterized in that the bone fixing elements ( 7 ) are bone screws. 19. Osteosynthesis implant according to claim 18, characterized in that the bone fixing elements ( 7 ) have a larger thread in the region of a screw head ( 9 ) than in the remaining region. 20. Osteosynthesis implant according to one of the preceding claims, characterized in that the openings ( 6 ) have an internal thread. 21. Osteosynthesis implant according to one of the preceding claims, characterized in that the shaft ( 2 ) is of straight design. 22. Osteosynthesis implant according to one of claims 1 to 20, characterized in that the shaft ( 2 ) is bent at least in regions. 23. Osteosynthesis implant according to claim 22, characterized in that the bend ( 10 ) of the shaft ( 2 ) and a bend of the plate ( 3 ) run in the same direction. 24. Osteosynthesis implant according to one of the preceding claims, characterized in that the plate ( 3 ) has an engagement region ( 18 ) for a handling tool ( 11 ) at its end opposite the shaft ( 2 ). 25. Osteosynthesis implant according to claim 24, characterized in that the handling tool ( 11 ) comprises a collet ( 15 ) which can be placed on the engagement region ( 18 ) and surrounds it in a clamping manner. 26. Osteosynthesis implant according to one of claims 23 or 24, characterized in that the handling tool ( 11 ) is connected to a drilling jig ( 21 ) which, when the handling tool ( 11 ) rests against the engagement region ( 18 ), has openings ( 22 ) for a drilling tool which are aligned with the openings ( 6 ; 5 ) in the plate ( 3 ) and/or the shaft ( 2 ).