Device with telescopic bone screw for treating bone fractures

Abstract

The invention relates to a device (1) for treating a bone fracture, in particular a proximal femur fracture, comprising a base (2) for attachment to a femur and at least one bone screw (4) and an adjustment screw (5), wherein the base (2) has an opening (6) through which the bone screw (4) can be guided in order to be fastened in the femoral head and the opening (6) receives the adjustment screw (5), wherein the bone screw (4) is in particular slidably supported in the opening (6) and wherein the adjustment screw (5) is configured to in particular predefine a maximum lateral sliding movement of the bone screw (4) in the fastened state. According to the invention, in order to allow a targeted lateral movement of the femoral head without the lateral end of the bone screw (4) having to move, the bone screw (4) comprises a first bone screw portion (41) and a second bone screw portion (42), wherein the bone screw portions (41, 42) are displaceable relative to one another with a change in the bone screw length (L).

Description

Technical Field

[0001] The present invention relates to an apparatus for treating fractures, particularly proximal femoral fractures, comprising a base for attachment to the femur and at least one bone screw and an adjusting screw, wherein the base has an opening through which the bone screw can be guided for fastening in the femoral head, and the opening receives the adjusting screw, wherein the bone screw is slidably supported in the opening, and wherein the adjusting screw is configured to, in the fastened state, predefine a maximum lateral sliding movement of the bone screw. Background Technology

[0002] Fractures in the proximal femur region are often challenging to treat. This is particularly often attributed to the fact that this type of fracture tends to occur in older patients, whose bone quality is no longer optimal due to age. Furthermore, the healing process takes longer in older patients.

[0003] When treating proximal femoral fractures, it is also necessary to consider that the surrounding muscles are no longer in their optimal position due to the fracture. Therefore, the forces acting on the fracture area may change during the healing process. To take this into account, devices for treating proximal femoral fractures have been developed that allow the femoral head to move during healing, thereby dynamizing the healing process. For this purpose, a base such as an intramedullary nail or a plate attached laterally to the femur is typically used. The base has an opening into which a bone screw can be inserted or guided through. The bone screw is used to fix the femoral head and is supported to slide within the opening. To prevent lateral slippage of the bone screw and rotation of the femoral head, an adjusting screw is also provided. The adjusting screw is configured, for example, to engage in a groove in the bone screw. As a result, the bone screw, and consequently the femoral head, cannot rotate, thus providing rotational stability. Furthermore, the adjusting screw is configured to restrict lateral movement of the bone screw, for example by a stop or by forming the aforementioned groove in a tapered manner laterally, so that the bone screw can only move laterally within a predetermined gap.

[0004] The gap can be, for example, from 5 mm to 15 mm. Therefore, a specific lateral gap for the bone screw can be predetermined based on given anatomical conditions and to match the specific fracture. Subsequently, during healing, if the applied forces require or induce this movement, the femoral head can move laterally while maintaining rotational stability.

[0005] Although devices based on the prior art convert static healing devices into dynamic ones by allowing bone screws and thus lateral movement of the femoral head, they still have the following drawbacks: lateral movement of bone screws, for example, 15 mm, causes significant changes in tissue, which is uncomfortable for the patient and ultimately leads to changes in conditions as the healing process progresses. Summary of the Invention

[0006] This invention begins here. The object of this invention is to eliminate or at least reduce the disadvantages of the prior art described above.

[0007] This objective is achieved by the following method: in a device of the type described at the beginning, the bone screw includes a first bone screw portion and a second bone screw portion, wherein the bone screw portions are displaced relative to each other as the length of the bone screw changes. Specifically, it can be specified that, in the tightened state of the first bone screw portion, the first bone screw portion and the second bone screw portion are displaced relative to each other as the length of the bone screw shortens.

[0008] The device according to the invention achieves the following advantages: in the tightened state of the device, i.e., when the first bone screw portion is engaged in the femoral head, only the first bone screw portion needs to be moved to allow lateral sliding in the base, and thus allows movement of the femoral head in the lateral direction. The movement of the first bone screw portion is independent of the movement of the second bone screw portion. In other words, the first bone screw portion can slide laterally together with the femoral head, while the position of the second bone screw portion remains unchanged. Lateral movement of the second bone screw portion is prevented by the adjusting screw, for example, the adjusting screw may have a suitable stop for blocking the lateral movement of the second bone screw portion.

[0009] Advantageously, the first bone screw portion is configured to include a lateral piston extension that slides into the second bone screw portion. Therefore, the bone screw can be shortened while maintaining a constant outer diameter. According to the invention, the total length of the bone screw generally decreases as the bone screw portions move relative to each other. The piston extension can be configured to be circular in a cross-section perpendicular to the longitudinal axis of the bone screw. However, a non-circular configuration is preferred, such as an oval or elliptical shape, in which the inner side of the second bone screw portion is correspondingly configured. Thus, anti-rotation is provided by a rotational locking engagement, wherein the piston extension slides within the cylindrical cavity of the second bone screw portion.

[0010] The bone screw portions may be configured to loosely interlock with each other. Specifically, the bone screw may consist of only two parts: a first bone screw portion and a second bone screw portion. In use or in a tightened state, the assembled bone screw is then laterally held by an adjusting screw that prevents lateral movement of the second bone screw portion, for example, by a stop against which the second bone screw portion rests. The first bone screw portion is attached to the femoral head. The two bone screw portions can then slide within predetermined limits, i.e., until the gap between the bone screw portions closes. This primarily involves lateral movement of the first bone screw portion together with the femoral head to which it is fastened. Medial movement of the second bone screw portion is possible but unrelated to the healing process.

[0011] The first bone screw portion typically has external threads at its medial end. These external threads allow the first bone screw portion to engage with the femoral head. For this purpose, a suitable hole is first formed in the femoral head. Thus, the first bone screw portion can be secured to the femoral head.

[0012] The first bone screw portion is preferably configured to narrow, for example, taper at its outer end. This narrowing, or tapering configuration allows the first bone screw portion to slide into the recess of the second bone screw portion. In this case, the second bone screw portion does not move, thus shortening the length of the bone screw.

[0013] Specifically, to ensure the rotational stability of the bone screw and thus prevent rotation of the femoral head, it is preferably specified that the first bone screw portion has at least one groove on its outer side, the groove being configured to allow the adjusting screw to engage therein. For this purpose, the adjusting screw can be tilted at a small angle greater than 0° and not exceeding 5° relative to the longitudinal axis of the bone screw. The adjusting screw then engages the groove of the bone screw at a small angle. As a result, although slippage is possible, pivotal movement of the bone screw, and consequently the femoral head, is prevented.

[0014] The first bone screw portion may have at least two grooves on its outer side, preferably located in a plane including the longitudinal axis of the bone screw. The bone screw may also have more grooves, such as three or four. This facilitates adjustment during surgery.

[0015] More preferably, the first bone screw portion is provided with a narrowing, particularly tapering, piston-like protrusion at its outer end, which engages in the second bone screw portion, and in the region adjacent to the piston-like protrusion, the outer diameter of the first bone screw portion corresponds to the outer diameter of the second bone screw portion. As a result, in the fully shortened or retracted state, a bone screw with a constant diameter at the transition from the first bone screw portion to the second bone screw portion is obtained, thus providing uniform conditions.

[0016] Although not strictly necessary as described above, it may be specified that the first bone screw portion is connected to the second bone screw portion by a fixation element. This fixation element may be particularly advantageous during surgery because the two bone screw portions thus cannot be separated from each other. However, in the simplest embodiment, the device does not require a fixation element and only consists of two bone screw portions that can be loosely inserted into each other. To prevent the two bone screw portions from dislodging during surgery when the bone screw has been inserted but the adjusting screw has not yet been inserted, the bone screw is held in place during the procedure until the adjusting screw is secured, for example by means of a screwdriver that prevents rotational fixation. Once the adjusting screw is secured, the screwdriver can be released. Due to the lateral fixation of the first bone screw portion in the femoral head and because the adjusting screw prevents lateral displacement of the second bone screw portion, the bone screw cannot be separated into its individual parts during healing.

[0017] The base may be configured as a plate, but it is preferably configured as an intramedullary nail.

[0018] In one variation, a screw may be provided, and the first bone screw portion may have a stop surface for the screw, wherein the screw is connected to the second bone screw portion. In this embodiment variation, the screw and its connection to the second bone screw portion provide the additional function of the possibility of lateral compression. When assembling the two bone screw portions, the shank of the provided screw can first be guided over the stop surface and screwed into the second bone screw portion. The device is then ready for use. When treating a fracture, the second bone screw portion engages with and is thus fixed to the femoral head. If the screw simultaneously abuts against the stop surface, the second bone screw portion and the femoral head can be pulled laterally by rotating the screw. As a result, adjustment can be performed, and desired compression can also be applied. Lateral sliding movements that may occur in the later stages of healing are not thereby impaired.

[0019] It is desirable to form a tapered portion in the first bone screw portion, which includes the stop surface. This results in a structurally simple construction for both the first bone screw portion and the stop surface for the screw head. The stop surface may extend circumferentially within the first bone screw portion, although this is not mandatory. However, a circumferentially extending stop surface can be easily produced through machining operations. The free inner diameter of the stop surface and the tapered portion matches the screw to be inserted, and vice versa.

[0020] The screw head is preferably configured to abut against the inside of the first bone screw portion and can then be slidably guided therein until the screw head reaches the stop surface. The free inner diameter of the tapered portion can be configured such that the portion of the screw adjacent to the screw head and not yet threaded has a corresponding outer diameter. As a result, the interaction of the screw head against the inside of the first bone screw portion also ensures good guidance of the screw.

[0021] For the screw to be connected to the second bone screw portion, it is suitable if the second bone screw portion has an internal thread that mates with the external thread of the screw.

[0022] The screw is typically attached to the second bone screw portion, allowing the screw to slide together with the second bone screw portion. As explained, this embodiment variation thus provides versatility because, in addition to sliding, the second bone screw portion can also be moved laterally by means of the screw.

[0023] Similarly, in order to properly guide the components that are supported and can slide relative to each other, the outer surface of the second bone screw portion may be specified to abut against the inner side of the first bone screw portion. Attached Figure Description

[0024] Further features, advantages, and effects of the present invention will become apparent from the exemplary embodiments described below. In the accompanying drawings with reference to the figures:

[0025] Figure 1 A cross-sectional view of the device according to the invention in a first state is shown;

[0026] Figure 2 A cross-sectional view of the device according to the invention in a second state is shown;

[0027] Figure 3 A first perspective view of the device according to the invention in a first state is shown;

[0028] Figure 4 A second perspective view of the device according to the invention in a first state is shown;

[0029] Figure 5 A perspective view of the device according to the invention in a second state is shown;

[0030] Figure 6 A variation of the device according to the invention is shown. Detailed Implementation

[0031] Figure 1 A device 1 according to the present invention is shown. Device 1 includes a base 2, which, according to... Figures 1 to 5 In an exemplary embodiment, the base 2 is configured as an intramedullary nail 3. The intramedullary nail 3 is typically an insertable medullary nail into the femur. The intramedullary nail 3 is elongated and has an opening 6. Furthermore, the intramedullary nail 3 has an additional distal opening 8. The additional opening 8 is used to receive a distal screw by which the intramedullary nail 3 is distally fixed in the femur. Multiple distal openings 8 may also be provided.

[0032] Opening 6 receives bone screw 4 and adjusting screw 5. Opening 6 is configured such that bone screw 4 is supported and can slide within opening 6. Bone screw 4 can slide within opening 6. For this purpose, the inner side of opening 6 in the region where bone screw 4 is located is smooth, so that bone screw 4 can slide along the portion of its abutment against the inner side of opening 6.

[0033] The bone screw 4 is a two-part construction, but may also include fixation elements, which will be explained in more detail below, if necessary. The bone screw 4 includes a first bone screw portion 41 that mates with the second bone screw portion 42. The first bone screw portion 41 is configured for insertion into the femoral head. For this purpose, the first bone screw portion 41 has external threads 45 in the region of its medial end 44. These external threads 45 engage in the femoral head (not shown). For this purpose, a guide wire is first inserted into the femoral head, and then a hole is formed around the guide wire using a suitable drilling tool. The bone screw 4 is then inserted into the hole to anchor the first bone screw portion 41 in the femoral head.

[0034] At the opposite, lateral end 46, the first bone screw portion 41 has a narrowed structure. According to... Figures 1 to 5 In an exemplary embodiment, the narrowing configuration may be designed such that the first bone screw portion 41 has a narrowed piston extension 43. The outer diameter D1 of the first bone screw portion is larger than the outer diameter of the tapered region including the piston extension 43.

[0035] The second bone screw portion 42 is configured to receive the outer end of the first bone screw portion 41. If as... Figures 1 to 5The diagram shows a narrowed piston extension 43, with its outer side abutting against the inner side of the second bone screw portion 42. The outer diameter D2 of the second bone screw portion 42 substantially corresponds to the outer diameter D2 of the first bone screw portion 41 in the region adjacent to the narrowed piston extension 43. The outer diameter of the piston extension 43 corresponds to the inner diameter of the second bone screw portion 42, such that the piston extension 43 slides along the inner side of the second bone screw portion 42. The piston extension 43 can be circular or oval. The inner side of the second bone screw portion 42 is constructed accordingly.

[0036] The first bone screw portion 41 has two grooves 47. An adjusting screw 5 can engage in one of these grooves 47. The adjusting screw 5 has an external thread 51 that mates with the internal thread of the opening 6. In other words, the opening 6 is smooth in the region of the bone screw 4, but threaded in the region of the adjusting screw 5. The adjusting screw 5 is prevented from rotating by means of a pin 9. The external thread 51 of the adjusting screw 5 engages in one of the grooves 47 of the first bone screw portion 41. As a result, the bone screw 4, and consequently the femoral head, is prevented from rotating. However, lateral movement of the first bone screw portion 4 and the femoral head fastened thereto is possible because this movement is not blocked by the external thread 51 of the adjusting screw 5 within the range of a predetermined gap S or within the region of the gap L1 between the first bone screw portion 41 and the second bone screw portion 42. However, the lateral movement of the first bone screw portion 41 can only continue until the gap S or the gap L1 is closed. Ideally, the length of the gap S is exactly equal to the length of the gap L1, thus achieving double stop. The second bone screw portion 42 is prevented from lateral displacement by means of a stop 7 by means of the adjusting screw 5. Therefore, the second bone screw portion 42, which also engages with the external thread 51 via the corresponding groove, can theoretically move inward; however, this requires a corresponding force. However, for lateral movement, this movement is prevented by the stop 7 of the adjusting screw 5.

[0037] Figure 2 A second state is shown, in which the first bone screw portion 41 has moved toward the second bone screw portion 42 along a possible gap S or gap L1. Therefore, the lateral displacement travel has been exhausted; the first bone screw portion 41, and consequently the femoral head, cannot move further laterally. Thus, the maximum lateral movement can be predetermined by the gaps S and L1. A particular advantage of the two-part construction is that tensile and compressive forces can be effectively absorbed. In principle, it is conceivable to simply construct the bone screw 4 shorter and allow it to move all the way to the stop of the adjusting screw 5. However, in this case, the tensile and compressive forces, as well as the bending moment, would be more unevenly distributed. The solution according to the invention provides a balanced force introduction.

[0038] Figure 3 and Figure 4 A three-dimensional diagram is shown based on Figure 1 The first state. Figure 5 Also shown in a 3D diagram according to Figure 1 The second state.

[0039] Figure 6 A variant of the device 1 according to the invention is schematically shown. Device 1 again includes a bone screw 4 having a first bone screw portion 41 and a second bone screw portion 42, and an adjusting screw 5. The intramedullary nail 3 has an opening 6 through which both the bone screw 4 and the adjusting screw 5 are guided. For additional functionality, in this variant, the first bone screw portion 41 has an internally formed tapered portion 10, which faces laterally and defines a stop surface 9 for the screw 8. The tapered portion 10 has a free inner diameter smaller than the free inner diameter of the first bone screw portion 1 in the remaining region. In principle, the first bone screw portion 41 can generally be approximately cylindrical. The second bone screw portion 42 is connected to the screw 8. For this purpose, the screw 8 has a suitable external thread, and the second bone screw portion 42 has a corresponding internal thread that mates with the external thread of the screw 8. As a result, as shown, the screw 8 can be connected to the second bone screw portion 42. At the inner end, the second bone screw portion 42 has an outer diameter corresponding to the outer diameter of the first bone screw portion 41, such that when… Figure 6 The distance 11 shown is bridged to obtain a continuous surface. Towards the outer end, the second bone screw portion 42 forms a step where the outer diameter decreases. (As shown...) Figure 6 As shown, the outer diameter can be designed such that the outer surface of the second bone screw portion 42 abuts against the inner side of the first bone screw portion 41 in this region, and thus is stably guided in a straight line during lateral sliding. The distance 11 thus defines the maximum lateral sliding movement of the second bone screw portion 42 together with the screw connected thereto. For this purpose, the cone is positioned sufficiently far in the lateral direction within the first bone screw portion 41 such that even when the maximum lateral position is reached and the distance 11 is thereby closed, the head of the screw 8 will not protrude laterally beyond the outer end of the first bone screw portion 41. The first bone screw portion 41 itself is secured by an adjusting screw 5, which may be configured at its end to have a collar, as shown, which engages in a groove in the first bone screw portion 41, preventing the first bone screw portion 41 from sliding in the opening 6.

[0040] according to Figure 6 The versatility of device 1 stems from the interaction between screw 8 and the second bone screw portion 42. If the second bone screw portion 42 is inserted into the femoral head and there is... Figure 6The distance 11 shown allows the femoral head to be laterally pulled by rotating the screw 8. As long as the distance 11 is not completely closed due to corresponding compression, during the healing process, on the one hand, the second bone screw portion 42, together with the screw, can slide laterally, and on the other hand, the femoral head can slide laterally. Therefore, device 1 provides the possibility of optimally treating the fracture.

Claims

1. A device (1) for treating fractures, particularly proximal femoral fractures, comprising a base (2) for attachment to the femur and at least one bone screw (4) and an adjusting screw (5), wherein the base (2) has an opening (6) through which the bone screw (4) can be guided for fastening in the femoral head, and the opening (6) receives the adjusting screw (5), wherein the bone screw (4) is slidably supported in the opening (6), and wherein the adjusting screw (5) is configured to, in the fastened state, pre-limit a maximum lateral sliding movement of the bone screw (4), characterized in that, The bone screw (4) includes a first bone screw portion (41) and a second bone screw portion (42), wherein the bone screw portions (41, 42) are capable of shifting relative to each other as the length (L) of the bone screw changes.

2. The apparatus (1) according to claim 1, characterized in that, With the first bone screw portion (41) fastened, the first bone screw portion (41) and the second bone screw portion (42) are able to shift relative to each other as the length (L) of the bone screw shortens.

3. The apparatus (1) according to claim 1 or 2, characterized in that, The first bone screw portion (41) includes a lateral piston extension (43) that can slide into the second bone screw portion (42), wherein the piston extension (43) is non-circular in cross-section perpendicular to the longitudinal axis of the bone screw, in particular oval or elliptical, and the inner side of the second bone screw portion is correspondingly constructed.

4. The apparatus (1) according to any one of claims 1 to 3, characterized in that, The first bone screw portion (41) has external threads (45) at the inner end (44).

5. The apparatus (1) according to any one of claims 1 to 4, characterized in that, The first bone screw portion (41) is constructed to be narrowed at the outer end (46), in particular to be tapered.

6. The apparatus (1) according to any one of claims 1 to 5, characterized in that, The first bone screw portion (41) has at least one groove (47) on its outer side, the groove (47) being configured such that the adjusting screw (5) can engage in the groove.

7. The apparatus (1) according to any one of claims 1 to 6, characterized in that, The first bone screw portion (41) has at least two grooves (47) on its outer side, the grooves (47) preferably being located in a plane.

8. The apparatus (1) according to any one of claims 1 to 7, characterized in that, The bone screw portion (41) has a narrowed, particularly tapered, piston extension (43) at its outer end, which engages in the second bone screw portion (42), and in the adjacent region (4) of the first bone screw portion (41), the outer diameter (D1) of the first bone screw portion (41) corresponds to the outer diameter (D2) of the second bone screw portion (42).

9. The apparatus (1) according to any one of claims 1 to 8, characterized in that, The first bone screw portion (41) is connected to the second bone screw portion (42) by a fixing element.

10. The apparatus (1) according to any one of claims 1 to 9, characterized in that, The base (2) is configured as an intramedullary nail (3).

11. The apparatus (1) according to claim 1 or 2, characterized in that, A screw (8) is provided, the first bone screw portion (41) has a stop surface (9) for the screw (8), and the screw (8) is connected to the second bone screw portion (42).

12. The apparatus (1) according to claim 11, characterized in that, A cone (10) is formed in the first bone screw portion (41), the cone (10) including the stop surface (9).

13. The apparatus (1) according to claim 11 or 12, characterized in that, The second bone screw portion (42) has an internal thread that mates with the external thread of the screw (8).

14. The apparatus (1) according to any one of claims 11 to 13, characterized in that, The screw (8) is connected to the second bone screw portion (42) such that the screw (8) slides together with the second bone screw portion (42).

15. The apparatus (1) according to any one of claims 11 to 14, characterized in that, The outer surface (10) of the second bone screw portion (42) abuts against the inner side of the first bone screw portion (41).

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