Flexible device for treating a bone fracture

Abstract

The invention relates to a device (1) for treating a bone fracture, in particular a femur fracture such as a femoral neck break, comprising a holding part (4) which is able to be fastened in or on a first bone part, wherein the holding part (4) has at least one opening (5) through which a bone screw (6) and an adjusting screw (7) are guided, wherein the opening (5) has, on the inner side, a surface with a threaded surface, in which the adjusting screw (7) engages, with the bone screw (6) being able to slide freely in the opening, and the adjusting screw (7) is configured to let the bone screw (6) rest against at least one stop (26) of the adjusting screw (7) optionally after lateral sliding of the bone screw (6). According to the invention, an adapter (10) that is able to be laterally releasably fixed in the bone screw (6) is provided and forms a barrier (11) for the adjusting screw (7) in the event of lateral movement of the adjusting screw (7).

Description

[0001] Flexible device for treating a bone fracture

[0002] The invention relates to a device for treating a bone fracture, in particular a femur fracture such as a femoral neck fracture, comprising a holding part which can be fastened in or on a first bone part, wherein the holding part has at least one opening through which a bone screw and an adjusting screw are guided, wherein the opening has on the inside a surface with a threaded surface into which the adjusting screw engages when the bone screw can slide freely in the opening and the adjusting screw is designed to allow the bone screw to rest against at least one stop of the adjusting screw, if necessary after lateral sliding of the bone screw.

[0003] Femoral fractures, especially femoral neck fractures, are fractures that are often difficult to treat properly. Furthermore, femoral neck fractures are more likely to occur in older, often elderly individuals, making proper treatment even more difficult. Femoral neck fractures are often the result of a bone structure that is no longer fully intact, for example, due to progressive osteoporosis.

[0004] One challenge in treating femoral fractures is that the broken bone fragments must be brought into a suitable position relative to each other and secured in this position, at least immediately after treatment. This is further complicated by the fact that the muscles surrounding the bone are not in an ideal position due to the fracture. Therefore, this muscular component must also be considered with regard to tensile and compressive forces, as well as any torsional forces that may occur, which must be prevented.

[0005] When treating femoral neck fractures, holding devices such as nails or plates are used which have openings through which a bone screw is passed. After drilling, the bone screw runs through a first, lateral bone part and is screwed into a second, medial bone part that has been separated from it due to a fracture. In order to move the bone screw after it has been screwed into the second, medial bone part and thus achieve an alignment of the second bone part against the first bone part, it is known from the prior art to use a compression screw which engages in a thread that runs along one side of the bone screw and interacts with it. By screwing the compression screw adjacent to the bone screw, the compression screw can initially be screwed in until it abuts the holding device.Further rotation then causes the compression screw to be pulled laterally, thus bringing the bone pieces closer together. However, a disadvantage of this approach has been shown to be that there is no limit to the degree of compression, and the degree of compression is left to the discretion of the medical staff. Particularly in elderly patients, the problem can arise that the bone screw simply tears out of a previously damaged and therefore no longer intact bone piece if the compression is too high. Nevertheless, excessive compression can also lead to suboptimal bone healing.

[0006] AT 524767 A4 discloses an alternative device for treating a bone fracture, which corresponds to the type mentioned above. In such a device, there is also an interaction between a bone screw and another screw, in this case an adjusting screw. The bone screw is mounted in the opening of the holding part so that it can move laterally. The adjusting screw initially blocks any medial movement as well as any rotation of the bone screw. However, lateral movement of the bone screw is possible to a predetermined extent, which is determined by a stop on the adjusting screw, which is set at an angle of several degrees and thus acts obliquely on the bone screw. This play can, for example, be adjusted within limits of 0 mm to 12 mm.This makes it possible for the second, medial bone portion, into which the bone screw is screwed, to react to applied forces within predetermined limits during the healing process. This allows for different constellations to be taken into account, depending on patient-specific parameters such as height, weight, bone density and / or type of fracture. A device according to AT 524767 A4 enables targeted adjustment of the lateral mobility of the bone screw when medially blocked. However, it is not possible to apply an additional tensile force to the medial bone portion, even if this were desired. This is where the invention comes in. The object of the invention is to further develop a device of the type mentioned at the outset in such a way that compression can also be generated if necessary.

[0007] This task is solved if, in a device of the type mentioned above, an adapter is provided which can be releasably fixed laterally in the bone screw and which forms a barrier for the adjusting screw during lateral movement of the adjusting screw.

[0008] The invention offers the particular advantage that a desired compression can now be actively adjusted, if desired. This can be achieved with a relatively simple design, as only an adapter is required which acts as a barrier when the adjusting screw is moved laterally, usually when it is unscrewed, so that the adjusting screw comes into contact with the adapter. If the adjusting screw is then moved further laterally, usually by unscrewing the adjusting screw on the thread in the opening, the adjusting screw moves the adapter and thus also the bone screw connected to the adapter in a lateral direction, so that the bone screw can be moved laterally and thus the two bone parts can be adjusted or compressed.The adjustment screw, which is positioned in such a way that it allows the bone screw to rest on the screw after it has glided laterally, can be used in conjunction with the adapter to bring the broken bone parts closer together and, if necessary, to compress them, thus significantly expanding the functionality of the device.

[0009] Within the scope of the invention, the holding part is preferably designed to be elongated. The holding part can be a bone plate or a nail, in particular an intramedullary nail.

[0010] The holding part has at least one opening for the bone screw. The opening can be designed such that both the bone screw and the adjusting screw are guided through the opening and are thus positioned as a unit in the opening. However, it is also possible to provide separate openings for the bone screw on the one hand and the adjusting screw on the other. If a single, common opening is provided for the bone screw and the adjusting screw, this is usually designed such that the opening in the contact area of ​​the bone screw is thread-free so that the bone screw can slide in the opening. In the area of ​​the adjusting screw, however, a thread is provided so that the adjusting screw can be screwed into the opening. If a single opening is provided for the bone screw and the adjusting screw, the cross-section of the opening can be approximately pear-shaped.The cross-sectional shape results from two circular arc-shaped opening elements that merge into one another to form an opening for both the bone screw and the adjustment screw. One or both of the circular arcs can sweep an angle of more than 180°, preferably more than 270°. The two opening elements merge into one another, creating a single opening. The larger circular arc-shaped opening element is intended for the bone screw, which bears the greater load, whereas the adjustment screw is primarily intended, apart from the compression mechanism, to block medial movement and to specifically adjust lateral movement of the bone screw and is therefore designed with a smaller diameter, for which the second circular arc-shaped opening element serves.

[0011] In particular, if the holding part is elongated, as is the case with bone nails or bone plates, further openings can be provided to accommodate further screws, with which the holding part can be fixed to the first bone part without penetrating or touching the second bone part.

[0012] It is preferred that the adapter region of a first adapter end has an external thread, and that the bone screw has an internal thread at a lateral bone screw end that interacts with the external thread. In this case, the adapter can be easily and detachably fastened to or in the bone screw. The adapter is advantageously designed to be wider than the bone screw in a region spaced from the fastening region, thus forming a barrier for the adjustment screw. The adapter can, for example, have a cross-section that is approximately 2% to 15%, for example 3% to 10%, wider than that of the bone screw.

[0013] The adapter can basically be designed in any way as long as it is ensured that the adapter can form a barrier for the adjusting screw during lateral movement of the latter. Since the adapter must first be fastened and then released again during use, it is preferred for the sake of good handling that the adapter is designed as an elongated pin. In this case in particular, the adapter can be designed with a tip in an area of ​​the first end of the adapter, which is arranged in front of the external thread when viewed in the lateral direction. With the tip, which is narrower than the external thread of the adapter, the adapter can be easily inserted into the bone screw, especially in the case of a pin-shaped design. The bone screw has a suitable opening for this purpose. In particular, the bone screw can be designed with a central opening, which is usually necessary anyway.

[0014] The adjustment screw can be designed with a receptacle for a wrench or similar tool at one lateral end. This allows the adjustment screw to be easily operated, both for adjusting the lateral play of the bone screw and for adjusting or compressing the two fractured bone segments.

[0015] It is advantageous if the adjustment screw is designed with a widened collar at the lateral end. The collar is multifunctional. Firstly, the collar forms a stop surface for the bone screw to limit its lateral mobility during the healing process. Secondly, when the two bone parts are brought together or compressed, the collar serves as a stop, which rests against a projection of the adapter and thus initiates the described mechanism of targeted, active lateral movement of the bone screw.

[0016] The bone screw can be formed with a groove into which the adjusting screw engages to limit, in particular prevent, rotation of the bone screw. Furthermore, the adjusting screw can be positioned at an angle to the bone screw and engage a laterally tapered groove in the bone screw to block medial movement of the bone screw. Furthermore, the bone screw, the adjusting screw, and the openings can be designed, in particular, as described in AT 524767 A4, the contents of which are hereby incorporated in their entirety.

[0017] Further features, advantages, and effects of the invention will become apparent from the following exemplary embodiments. Reference is made to the drawings, which show:

[0018] Fig. 1 an intramedullary nail;

[0019] Fig. 2 shows the intramedullary nail from Fig. 1 in another view;

[0020] Fig. 3 shows an intramedullary nail and an adjusting screw with a bone screw and a schematic representation of the interaction of an adjusting screw with a bone screw in a first position;

[0021] Fig. 3 is a further schematic representation of the interaction of an adjusting screw with a bone screw in a second position;

[0022] Fig. 5 is a further schematic representation of the interaction of an adjusting screw with a bone screw in a third position;

[0023] Fig. 6a to Fig. 6c a bone screw with grooves and an interaction of the bone screw with bone screws of different lengths;

[0024] Fig. 7a to Fig. 7c are schematic representations of a unit comprising an intramedullary nail as well as a bone screw and an adjusting screw, wherein the adjusting screw specifies a different play;

[0025] Fig. 8 shows a section of a unit comprising a bone screw and an adjusting screw as well as an adapter;

[0026] Fig. 9 the unit from Fig. 8 after movement of the adjusting screw;

[0027] Fig. 10 an adapter.

[0028] Fig. 1 and Fig. 2 show a holding part 4. The holding part 4 is designed as a bone nail, in particular an intramedullary nail. However, the holding part 4 could also be designed as a bone plate, although within the scope of the invention, a design of the holding part 4 as a bone nail is preferred.

[0029] The holding part 4 or intramedullary nail is, as can be seen in Fig. 1 and Fig. 2, elongated with a longitudinal axis X. The intramedullary nail has an opening 5 with a first transverse axis Y1. The first transverse axis Y1 can, for example, enclose an angle of 30° to 40° with the longitudinal axis X. In the case of a bone plate as the holding part 4, an analogous opening 5 is provided. As can be seen from Fig. 1, the opening 5 is formed with two circular arc-shaped sections 51, 52. An upper, first circular arc-shaped section 51 is provided for a bone screw 6. An underlying, circular arc-shaped section 52 of the opening 5 is provided for an adjusting screw 7. The two sections 51, 52 of the opening 5 merge into one another, so that a single opening 5 is formed for both screws. The circular arc sections each cover more than 270°.The section of the opening 5 for the bone screw 6 is larger in cross-section than that for the adjusting screw 7. This results from the fact that the bone screw 6 absorbs forces and is therefore stronger, whereas the adjusting screw 7 serves for a targeted control of the mobility of the bone screw 6 and can therefore be less strong.

[0030] The opening 5 can also be designed so that the larger opening section for the bone screw 6 is at the bottom and the smaller opening section for the adjustment screw 7 is at the top.

[0031] The opening 5 has a surface 8 on the inside which is smooth in the area in which the bone screw 6 is or is positioned. This allows the bone screw 6 to slide in the opening 5 as long as medial or lateral movement is not blocked. In the area of ​​the smaller opening section for the adjusting screw 7, a threaded surface 9 is provided, into which the adjusting screw 7 engages in a manner to be explained below. The unit thus comprises, in addition to the holding part 4, which is designed as an intramedullary nail in Fig. 1 and Fig. 2, the bone screw 6 and the adjusting screw 7. A second transverse axis Y2, which coincides with a longitudinal axis of the adjusting screw 7 or runs offset parallel to it, forms an angle other than 0° with the first transverse axis Y1.

[0032] An assembled unit is shown in Fig. 3 in a first position. Next to the holding part 4, again in the form of an intramedullary nail, the inserted bone screw 6 can be seen. The bone screw 6 generally has a thread on a medial bone screw end 15, which serves to fasten the bone screw 6 in a first bone part 2, for example a femoral head. The intramedullary nail is fastened in a second bone part 3, which is no longer connected to the first bone part 2. Fig. 3 schematically shows a fracture line between the two bone parts 2, 3. In the lateral direction L, the bone screw 6 is essentially smooth following the medially arranged thread, but has recessed grooves 24. These grooves 24 widen towards a medial bone screw end 15 and, viewed conversely, taper towards a lateral bone screw end 14.This allows lateral play to be set for the bone screw 6 by, as shown in Fig. 3 to Fig. 5, the oblique positioning of the adjusting screw 7 of the groove 24 creates a medial block and specifies maximum movement for the bone screw 6 in the lateral direction L up to a stop 26 of the adjusting screw 7. The adjusting screw 7 has a lateral adjusting screw end 18 and a medial adjusting screw end 19. The further the lateral adjusting screw end 18 is moved in the lateral direction L, the more lateral play the bone screw 6 has.

[0033] As mentioned, the adjusting screw 7 can engage in the grooves 24. The grooves 24 of the bone screw 6 and the interaction of the screws are particularly evident in Fig. 6a to Fig. 6c. Fig. 6a shows a bone screw 6a with two grooves 24. Fig. 6b and Fig. 6c show the corresponding arrangements for two adjusting screws 7 of different lengths. The respective adjusting screw 7 comes to rest in one of the grooves 24. Due to the conically widened or tapered design of the grooves 24, the bone screw 6 can be passively moved in the lateral direction L by occurring forces until it comes to rest on a stop surface, or possibly several stop surfaces, of the adjusting screw 7. Movement in the medial direction M, however, is not possible due to the contact of the adjusting screw 7. Rotation is also at least largely prevented, and advantageously prevented completely.Thus, the interaction of bone screw 6 and adjusting screw 7 results in a fixation of a medial mobility of the bone screw 6 as well as its rotation with simultaneous possibility of movement in the lateral direction L, provided that a corresponding play is set by the adjusting screw 7.

[0034] For a favorable interaction between the holding part 4, the bone screw 6, and the adjusting screw 7, it is advantageous if the adjusting screw 7 is positioned at a relatively small angle a against the bone screw 6, as shown exemplarily in Fig. 6b. For this purpose, the corresponding longitudinal axes of the bone screw 6 and the adjusting screw 7 are arranged at an angle a to each other in the medial direction M, which can, for example, be in the range of 1° to 5°. The opening 5 is suitably designed for this purpose.

[0035] Fig. 7a to Fig. 7c show highly schematically various configurations in which a movement of the bone screw 6 in the lateral direction L is predetermined by the adjusting screw 7 and the stop 26. A gap S between the bone screw 6 and the adjusting screw 7 can be adjusted so that, during a healing process, a movement of the bone screw 6 in the lateral direction L is possible depending on patient-specific parameters.

[0036] By default, the clearance between at least one stop 26 of the adjustment screw 7 and a corresponding stop of the bone screw 6 is approximately 0 mm, 5 mm, or 10 mm. A corresponding clearance of 0 mm to 10 mm adequately covers the required variability with respect to patients.

[0037] The previously explained unit comprising holding part 4, bone screw 6 and adjusting screw 7 can be provided with additional functionality if an adapter 10 is provided in a device 1, which is shown in detail in Fig. 8 and Fig. 9, which forms a barrier 11 when the adjusting screw 7 is moved laterally. This is explained with reference to Fig. 8 and Fig. 9. Fig. 8 and Fig. 9 show a holding part 4 designed as an intramedullary nail, in the opening 5 of which a bone screw 6 and an adjusting screw 7 are arranged in the manner already explained. The adjusting screw 7 subsequently limits any lateral movement of the bone screw 6 and prevents any medial movement thereof as well as any rotation of the bone screw 6. In addition, an adapter 10 is provided which can be releasably fixed in the bone screw 6.For this purpose, the adapter 10 has an external thread 16 in the region of a first adapter end 12, which interacts with an internal thread of the bone screw 6, so that the adapter 10 can be guided into the bone screw 6, which is formed with a central opening 21, and can be releasably fixed therein. For this purpose, the adapter 10 can also have a tip 20 on the first adapter end 12, which enables the adapter 10 to be inserted into the central opening 21 of the.

[0038] Bone screw 6 is made possible. Towards a second adapter end 13, as can be seen in Fig. 10, the adapter 10 is initially designed with a constant cross-section from the direction of view of the external thread 16, which widens out so that the adapter 10 is designed in this area with a barrier 11 in the form of a projection which, as can be seen, can extend over the remaining length of the adapter 10, although this is not mandatory. The barrier 11 is designed to cooperate with the adjusting screw 7 for the purpose of positioning the second bone part 2 against the first bone part 1. For this purpose, the adjusting screw 7 is turned out of the opening 5 using a wrench 23. The adjusting screw 7 has a suitable receptacle 22 to accommodate the wrench 23. If the adjusting screw 7 is turned out of the opening 5, it initially has some free space before the adjusting screw 7 comes into contact with the barrier 11 of the adapter 10.Since, as mentioned, the adjusting screw 7 is set at an angle to the bone screw 6, the barrier 11 is designed to project sufficiently so that a collar 25 or, if appropriate, another stop surface of the adjusting screw 7 can come into contact with the barrier 11, as shown in Fig. 9. As soon as this is the case, the adjusting screw 7 takes the adapter 10 and thus ultimately also the bone screw 6 with it in the lateral direction L, so that the bone screw 6 slides laterally in the opening 5 and thus moves the second bone part 2 in the direction of the first bone part 1, as indicated by the arrows. As soon as a desired adjustment, or compression if necessary, is achieved, the adapter 10 can be detached from the bone screw 6. The adjusting screw 7 can then, if necessary, be moved or screwed in again in the medial direction M in the opening 5 in order to limit any lateral play of the bone screw 6.

[0039] Fig. 10 shows an adapter 10 as is useful within the scope of the invention. Due to the elongated design of the adapter 10, it can be easily handled and, in particular, can easily bridge the distance of a fabric sleeve 27, which can be seen in Fig. 8.

[0040] A device according to the invention extends the spectrum of possibilities of a unit comprising holding part 4, bone screw 6 and adjusting screw 7, since a tensile force can also be applied to the bone screw 6 while simultaneously limiting a medial movement and a rotational movement and specifically adjusting a lateral movement.

Claims

Patent claims 1. A device (1) for treating a bone fracture, in particular a femur fracture such as a femoral neck fracture, comprising a holding part (4) that can be fastened in or on a first bone part (2), wherein the holding part (4) has at least one opening (5) through which a bone screw (6) and an adjusting screw (7) are guided, wherein the opening (5) has on its inside a surface (8) with a threaded surface (9) into which the adjusting screw (7) engages when the bone screw (6) can slide freely in the opening (5), and the adjusting screw (7) is designed to allow the bone screw (6) to rest against at least one stop (26) of the adjusting screw (7), optionally after lateral sliding of the bone screw (6), characterized in that an adapter (10) that can be laterally releasably fixed in the bone screw (6) is provided, which adapter forms a barrier (11) for the adjusting screw (7) during lateral movement of the adjusting screw (7). trained.

2. Device (1) according to claim 1, characterized in that the holding part (4) is designed to be elongated.

3. Device (1) according to claim 1 or 2, characterized in that the holding part (4) is designed as an intramedullary nail.

4. Device (1) according to one of claims 1 to 3, characterized in that the adapter (10) has an external thread (16) in the region of a first adapter end (12) and the bone screw (6) has an internal thread (17) at a lateral bone screw end (14) which cooperates with the external thread (16).

5. Device (1) according to claim 4, characterized in that the adapter (10) is formed in a region of the first adapter end (12) with a tip (20) which, viewed in the lateral direction (L), is arranged in front of the external thread (16).

6. Device (1) according to one of claims 1 to 5, characterized in that the bone screw (6) is formed with a centrally extending opening (21).

7. Device (1) according to one of claims 1 to 6, characterized in that the adjusting screw (7) is formed at a lateral adjusting screw end (18) with a receptacle (22) for a wrench (23).

8. Device (1) according to one of claims 1 to 7, characterized in that the adjusting screw (7) is formed at the lateral adjusting screw end (18) with a widened collar (25).

9. Device (1) according to one of claims 1 to 8, characterized in that the bone screw (6) is formed with a groove (24) into which the adjusting screw (7) to limit, in particular prevent, rotation of the bone screw (6).

10. Device (1) according to one of claims 1 to 9, characterized in that the adjusting screw (7) is set at an angle to the bone screw (6) and engages in a laterally tapered groove (24) of the bone screw (6) in order to block a medial movement of the bone screw (6).

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