Spiral drill for medical applications
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- I T S
- Filing Date
- 2026-02-02
- Publication Date
- 2026-08-06
Smart Images
Figure AT2026060027_06082026_PF_FP_ABST
Abstract
Description
[0001] Spiral drill bits for medical applications
[0002] The invention relates to a drill for medical applications, in particular for drilling into bones, comprising a first end and a second end, a cutting area arranged at the first end with cutting edges such as main cutting edges and secondary cutting edges, a shank area downstream of the cutting area with a drill bit arranged between the cutting area and the second end, wherein the drill bit is wider relative to the cutting area.
[0003] Furthermore, the invention relates to a method for drilling a hole, in particular a hole, wherein the hole is drilled into an object such as a bone.
[0004] Proximal femur fractures are common in older individuals. Surgical treatment can involve an intramedullary nail, which has at least one opening for a bone screw or femoral neck screw. This screw is inserted through the opening and anchored, in particular, in the femoral head. The bone screw can be fixed with a second screw to prevent rotation. More recent developments have led to treatments for such femur fractures in which the additional screw controls not only rotational stability but also lateral movement of the bone screw. The bone screw is usually referred to as a "lag screw," and the second screw as a "set screw." In German, the terms "Knochenschraube" or "Schenkelhalsschraube" can be used for the "lag screw," and "Stellschraube" or "Setzschraube" for the "set screw."Depending on its function, the "set screw" can also be called something else, such as an adjusting or fixing screw. In this context, the "set screw" is consistently referred to as a setting screw. In addition to these screws, which are usually inserted through a proximal opening or openings of an intramedullary nail, one or more further openings may be provided distally for the insertion of distal fixing screws. These, however, are relatively simple in design and serve only to fix the bone nail distally. The interaction between the bone screw and the setting screw can be configured in various ways. For example, it is possible for the bone screw and the setting screw to work together in such a way that compression can be applied to the separated bone fragments, such as fractured bone fragments in the region of a femoral neck.Sets for the treatment of proximal femur fractures can also be designed so that the positioning screw not only prevents rotation of the bone screw around an axis other than its longitudinal axis (thus ensuring rotational stability), but also allows lateral migration of the bone screw during the healing process within predetermined limits that can be adjusted during surgery. This enables a healing process with a dynamic component.
[0005] Additional instruments in the applicant's sets for the treatment of proximal femur fractures also allow for the approximation (apposition) and / or compression of broken bone fragments. This provides a wide range of treatment options for proximal femur fractures and, if necessary, other fractures, provided the corresponding sets are suitable for this purpose.
[0006] When a set from the applicant is used, for example according to WO 2024 / 098081 A1, a typical surgical procedure is abbreviated as follows: First, an intramedullary bone nail is inserted into a femur using a targeting device. The intramedullary bone nail has an opening near its proximal end, which provides a superior receptacle for the bone screw. This receptacle is designed without threads in the area of the superior receptacle, allowing the bone screw to slide smoothly within it. Adjacent to the distal end, the opening seamlessly transitions into another, inferior receptacle, which is equipped with an internal thread for the set screw. After the bone nail is inserted, an incision is made, and tissue protection sleeves are inserted via a so-called master sleeve located in the targeting device. These sleeves extend approximately to the femur.Next, guide sleeves for two drill wires are inserted into the tissue protection sleeves. The drill wires are then placed into the bone, specifically the femoral head. At this stage of the operation, two drill wires are in place. The two drill wires are positioned parallel to each other, which is achieved by designing the guide sleeves accordingly, even though the tissue protection sleeves are slightly angled or converged towards each other for the functions that will be explained later. The superior drill wire is intended to guide the bone screw, while the inferior drill wire provides rotational stability during screw insertion (interoperative rotational stability). The bone screw is then inserted into the femoral head. For this purpose, the bone screw has a suitable shape at one medial end to accommodate a screwdriver or similar tool.The bone screw is cannulated and guided over the superior drill wire, which serves as a guide. After the bone screw is inserted, the inferior drill wire and its guide sleeve are removed, and a new guide sleeve for a drill bit is inserted. This drill bit is used to create a blind hole for the set screw. The bone screw must be properly aligned for this purpose. This can be achieved, for example, by aligning a mark on a positive-locking screwdriver for the bone screw with a mark on the tissue protection sleeve. This ensures that the outer grooves of the bone screw, into which the set screw will later engage, are correctly aligned.This allows the drill to be guided past the bone screw even if the drill axis, corresponding to the later insertion of the set screw, forms a slight angle with the longitudinal axis of the bone screw, generally less than 5°, and especially less than 3°, for example, 2° or less. Once the corresponding blind hole has been created, the set screw, which has an external thread that engages in the inferior receptacle of the opening, which, as mentioned, has an internal thread, can then be inserted. With this, the fracture is essentially treated, apart from any final surgical steps.
[0007] The drill bit for the adjusting screw has cutting edges at its head or medial end, which allow it to cut or drill into bone. This is followed by a shaft with a first section extending to a widened drill bit located on the shaft. The primary purpose of this drill bit is to stop the drill bit against the bone nail, preventing further axial insertion. Adjacent to the drill bit, towards the opposite end of the drill bit, a recess, notch, or other type of textured area with a smaller diameter may be incorporated. This allows the surgeon to not only feel when the drill bit hits the bone nail, but also to visually verify this using imaging techniques. This adheres to the principles of a simple and controllable surgical technique.
[0008] Despite these principles, problems can arise in practice, either way. Imaging procedures can present difficulties in precisely identifying the groove or other markings, as contrasts are often low and can vary depending on the relative position. Regarding the drill bit, which removes bone until it contacts the bone screw at the proximal opening, it is designed to be relatively blunt to avoid damaging the bone nail. While this is desirable, in cases of relatively hard cortex, high resistance during drilling can be misinterpreted as the drill bit contacting the bone nail, when this is not actually the case.
[0009] This is where the invention comes in. The object of the invention is to further develop a drill of the type mentioned above in such a way that contact between the drill bit and the bit, and thus a stop position, can be reliably detected using simple means.
[0010] Another objective of the invention is to further develop a method of the type mentioned above in such a way that the contact of a drill bit with an object and thus a stop position can be reliably detected.
[0011] The object of the invention is achieved if, in a drill of the type mentioned above, at least one external thread is arranged in the shank area between an end face of the drill bit and the second end.
[0012] An advantage of the solution according to the invention is that the additional external thread allows the drill bit to be drawn in towards the bone nail or, if applicable, another object, at least when the drill bit is not guided orthogonally, but at a specific angle (usually, viewed medially, an angle of 100° to 140°, in particular 110° to 130°, exists between the bone nail and the medially projecting part of the bone screw) through the opening of the bone nail. As soon as the drill bit, with its end face facing the cutting area, comes to rest in a blind hole of the bone screw or another object, in particular another implant, further rotation of the drill bit, when the axial feed of the drill bit is no longer present, causes the thread to overtighten and the borehole to be cleaned out. Thus, a roller function is also present.
[0013] In particular, the external thread allows the drill bit to be inserted smoothly until the end face of the drill bit rests against the opening of the bone nail. This ensures that the stop position, defined by the blocking of axial forward movement due to the drill bit hitting the stop, can be reliably identified. Optical aids can, of course, be used for verification, although this is not strictly necessary.
[0014] The drill bit typically consists of a cutting section and a shank section adjoining the cutting section. The core bit is also located within the shank section, serving as a stop across its end face. This gives the core bit multiple functions. Thus, the drill bit has a first end, from which the cutting section extends, and a second end, the shank section. In addition to the core bit and the external thread, the shank section may incorporate other structural features. Advantageously, the second end of the shank section is designed to accommodate a tool that rotates the drill bit around its longitudinal axis.
[0015] Typically, the cutting area and the adjoining first section of the shank, extending to the drill bit, have a substantially constant maximum outer diameter. The first section of the shank can be substantially cylindrical. This cylindrical section preferably has a circular cross-section when viewed perpendicular to the drill's longitudinal axis. The cutting area has a corresponding maximum outer diameter. The outer diameter of the cutting area is, of course, variable, especially since flutes connect to the main and secondary cutting edges. In the flute area, the outer diameter, viewed perpendicular to the drill's longitudinal axis, is significantly smaller. The secondary cutting edges can be wire-tipped. The main cutting edges can be straight.
[0016] The drill bit is made of a solid material and therefore, unlike the bone screw, is not guided over a drill wire.
[0017] It is particularly advantageous that an external thread is already incorporated into the drill bit. As explained, the stop, designed as a drill bit, is wider than the cutting area and thus also wider than the adjoining first section of the shank, and therefore, in its design as a drill bit, it also removes material. The maximum outer diameter of the drill bit can correspond to the outer diameter of the setscrew to be inserted later. The at least one external thread can connect to and / or extend into the end face of the drill bit. It is preferable for the external thread to transition directly into the end face of the drill bit so that the drill can be easily inserted axially and drilled as described.On the other hand, it is necessary to maintain a facet sufficiently large to ensure not only that the drill bit rests against the bone nail, but also, and more importantly, to prevent the drill bit from being forced through the lower part of the opening despite the drill bit, thus preventing damage to the internal thread of the opening. Even if an external thread transitions directly into the facet, this can be achieved through appropriate dimensioning and design of the individual sections of the shank and, correspondingly, the adjusting screw. The facet can be designed, at least in part, with a surface extending transversely to the longitudinal axis of the drill bit. This surface serves as a stop and can, for example, be annular.This surface can be interrupted, in particular by chip spaces or flutes, and can consist of several separate sectors located between interruptions formed by the chip spaces or flutes. The at least one external thread can be interrupted, preferably multiple times, in particular by chip spaces. The chip spaces can be elongated and extend from the first end to the second end, and can be curved. It is also possible for a first external thread and a second external thread to be present, with the external threads separated by a groove running between them. The groove can be shorter in its longitudinal extension from the first end to the second end of the drill than the second external thread, which is closer to the second end than the first external thread.The preferably circumferential groove can serve to additionally determine, using imaging techniques, whether the drill bit has correctly positioned itself against a bone screw or, if applicable, another object in the desired manner. In principle, other types of markings that can be visually detected using imaging techniques are also possible; however, a groove approximately the width of the drill bit, viewed longitudinally from the first end to the second end, has proven effective. The second external thread can be positioned between the groove and the second end and, in particular, connect directly to the groove. The second external thread can be longer than the first external thread. If the first external thread is shorter than the second external thread, the drill bit with the first external thread can first be fitted with a groove of approximately the same width.Viewed longitudinally, a groove of approximately the same length is connected before an even longer section of the second external thread can follow. The second external thread can be formed along the longitudinal axis of the drill bit with at least twice the length of the first external thread, preferably at least three times the length, and in particular at least four times the length of the first external thread. During the drilling process, the second external thread assists in drawing in the drill bit during axial forward movement and subsequently, with the drill bit axially fixed but continuing to rotate, it serves to clear the borehole.
[0018] The external thread(s) can be single-start or, advantageously, multi-start. It is also possible for the external thread(s) to have a variable core diameter and / or variable thread pitch. The external thread(s) are specifically designed to ensure smooth operation of the drill bit, while preventing it from engaging too quickly axially, thus avoiding an abrupt stop and, more importantly, a difficult-to-control drilling process. A design with an increasing or decreasing thread pitch allows adjustment of how quickly the thread is stripped, thereby controlling the drilling progress.
[0019] In a further aspect, the invention provides a drill, in particular a twist drill, designed for medical applications, especially for drilling into bone, comprising a first end and a second end, a cutting area arranged at the first end with cutting edges such as main and secondary cutting edges, and a shank area downstream of the cutting area, which extends to a second end, wherein a thread is formed on the cutting edges, in particular the secondary cutting edges, the thread being designed with a variable thread pitch and / or a variable core diameter. This allows a high-quality hole with high surgical safety to be achieved when drilling into a bone, in particular a human bone, especially for inserting an adjusting screw in the manner described above.The thread, located particularly on the secondary cutting edges, determines how quickly the drill bit, especially a twist drill, can penetrate human bone and also improves chip removal. A core bit may be included, but is not mandatory. The thread, particularly on the secondary cutting edges, can be single-start or multi-start. For precise adjustment, the thread pitch can vary from the first end to the second. Preferably, this variation in the thread pitch is continuous. Alternatively, the core diameter can vary, advantageously increasing from the first end to the second. This increase is advantageously continuous along the length of the twist drill. The thread can extend partially or completely across the cutting area from the first end.As a rule, a partial extension, beginning approximately at the first end, is sufficient, for example up to 25%, and in particular up to 20%, of the longitudinal extension of the cutting area from the first end to the second end. Accordingly, another aspect of the invention lies in a method for drilling a hole in a bone, particularly a human bone, using a suitable twist drill. A particularly preferred use of the twist drill is that it is used for drilling holes in human bone.
[0020] In a further aspect, the invention relates to a set for treating a bone fracture, in particular a proximal femur fracture, which includes a drill according to the invention. The set can, in particular, comprise a targeting device for connection with a bone nail, the bone nail itself, a master sleeve positioned or positionable in the targeting device, tissue protection sleeves that can be inserted into the master sleeve, a bone screw, and an adjusting screw. Various drill wires, distal screws, guides, and screwdrivers, and in particular a drill according to the invention, are provided for inserting the bone screw and the adjusting screw. The set can, in particular, be configured according to application WO 2024 / 098081 A1 of the applicant, the contents of which are hereby fully incorporated with regard to the set and the surgical steps performed with it.
[0021] The further objective of the invention is achieved when, in a method of the type mentioned at the outset, a drill bit according to the invention is used to drill the hole. The method can otherwise be carried out as described above.
[0022] As explained, the advantages are that the drill bit can be easily inserted into the material to be drilled and, due to the smoothness of the drilling process, a stop of the drill bit against an obstacle or barrier is easily noticeable.
[0023] In particular, it can be provided that an object with an opening, such as an intramedullary nail, is inserted into the object. The hole is then drilled through the opening, with the drill being axially shifted through the opening during drilling until the drill bit comes into contact with the object. This allows the drill bit to initially remove material. Once the drill bit is in contact, reaming can be performed via the external thread(s) to clear the drilled hole, especially the area for an adjusting screw to be inserted. During this process, the drill bit rotates, particularly when in contact with the object. This rotation occurs around a longitudinal axis of the drill bit.
[0024] Further advantages, features, and effects of the invention will become apparent from the exemplary embodiments described below. The drawings referenced therein show:
[0025] Figs. 1a to 1c show various imaging studies during the treatment of a femur fracture, in which a bone nail and a bone screw are inserted and a drill bit for a set screw is guided in the bone; Fig. 2 shows a drill bit;
[0026] Fig. 3 shows an enlarged section corresponding to circle III in Fig. 2;
[0027] Fig. 4 shows another enlarged section of a different drill bit;
[0028] Fig. 5 shows a spiral drill bit for medical applications;
[0029] Fig. 6 shows an enlarged section corresponding to circle VI in Fig. 5.
[0030] Figures 1a to 1c show various situations during surgery to treat a proximal femur fracture, with a bone screw already placed in the femoral head. Figures 1a to 1c depict the current surgical situation after the bone screw has been inserted. Next to the bone screw, a spiral drill is visible, which is used to create a blind hole adjacent to the already placed bone screw, which passes through a visible bone nail embedded in the femur. This blind hole is for a later-inserted set screw, which prevents rotation of the bone screw and can also be configured to limit lateral movement of the bone screw to a predetermined degree.
[0031] The spiral drill shown in Figures 1a to 1c has a widened section which, after a predetermined penetration of the drill into the bone, is intended to come into contact with the bone nail. This should be noticeable, firstly, as increased resistance during drilling; secondly, the imaging techniques serve to identify a groove on the spiral drill that, upon contact of the widened section of the drill, should rest against the bone nail, as the groove follows directly after the widened section. As can be seen in Figures 1a to 1c, depending on the position of the spiral drill and the resolution of the imaging technique used, the groove may be barely visible, also due to poor contrast.Even if the impact of the widened section of the spiral drill on the bone nail cannot be clearly felt, for example because the drilling process is already associated with high resistance due to hard material, the exact determination of an end position of the spiral drill during the drilling process can be difficult or even prevented.
[0032] Figure 2 shows a drill 1 according to the invention, which solves this problem. The drill 1 has a first end 11 and a second end 12. The drill 1 can be made of steel and is formed from a solid material, thus lacking a central channel. Essentially, the drill 1 extends longitudinally from the first end 11 to the second end 12 along and about a longitudinal axis of the drill 1. At its end face, the drill 1 has a cutting area 2. This cutting area 2 forms the initially engaging tip of the drill 1 when drilling into a bone, particularly a human bone. For this purpose, the cutting area 2 is equipped with main cutting edges 3 and secondary cutting edges 4, as is known from twist drills. A shank section 5 adjoins the cutting area 2 in the direction of the second end 12, thus in a direction from medial (first end 11) to lateral (second end 12).The shank section 5 can be subdivided into several sections 51, 52, 53. A third section 53, adjacent to or encompassing the second end 12, serves to secure the drill bit 1 in a tool that allows the drill bit 1 to rotate about its longitudinal axis to perform a drilling operation. A second section 52 adjoins the third section 53 medially, towards the first end 11. This second section 52 has a essentially constant circular cross-section, viewed transversely to the longitudinal axis of the drill bit 1. This second section 52 primarily serves to bridge the distance. Finally, the first section 51 adjoins the second section 52 medially, again towards the first end 11, before the cutting area 2 follows.The first section 51 is essentially formed with a circular cross-section (perpendicular to the longitudinal axis of the drill 1) following the cutting area 2.
[0033] The first section 51 then transitions into a drill bit 6, which, as can be seen in the enlarged detail in Fig. 3, is wider than the leading part of this first section 51. The drill bit 6 serves to allow the drill 1 to come into contact with a bone nail when drilling a blind hole, as shown, for example, in Figs. 1a to 1c. This is achieved by a stop on an end face 7 of the drill bit 6. Furthermore, due to its wider design relative to the cutting area 2, the drill bit 6 also removes material, which is important for the subsequent insertion of an adjusting screw that interacts with the bone screw. For correct centering between the cutting area 2 and the drill bit 6, the drill 1 may also have molded-in threads, which center the drill 1 in the opening of the bone screw.
[0034] Unlike the prior art, the drill bit 6 has a first external thread 8. This external thread 8 allows the drill bit 1 to engage more easily with the bone material when drilling or creating a blind hole. This smoother drilling action makes it easier to determine when the drill bit 6, or rather its end face 7, comes into contact with the bone nail. Once this occurs, the drill bit 1 can no longer advance axially. However, further rotation of the drill bit 1, due to the first external thread 8, causes the drill bit 1 to clear the hole, which later facilitates the insertion of an adjusting screw.
[0035] As can also be seen in Fig. 3, a second external thread 9 can be provided. This second external thread 9 results from a groove 14 adjoining the first external thread 8. This is not mandatory; the first external thread 8 could also be designed to extend to a lateral end of the second external thread 9. The additional groove 13 can, however, be used in the known manner to be located for additional verification using imaging techniques. Fig. 3 also shows that chip flutes 10 can be provided for material removal. These flutes extend over the length of the external threads 8, 9, and optionally, as shown in Figs. 3 and 4, beyond, thus interrupting the external threads 8, 9. A number of the circumferentially arranged chip flutes 10 are positioned to ensure efficient material removal.For example, three to six chip spaces 10 can be provided, which are advantageously distributed evenly around the circumference.
[0036] As can be seen in Fig. 1, the first section 51 is longer than the cutting area 2. The second section 52, in turn, is significantly longer than the first section 51 and the third section 53.
[0037] Figure 4 shows an alternative variant for the external threads 8 and 9. As can be seen, the second external thread 9 has a different thread pitch. This may be desirable, for example, to prevent the drill bit 1 from cutting into bone too quickly. Furthermore, the core diameter also increases in the direction from the first end 11 to the second end 12.
[0038] The cutting area 2 can also be suitably adapted. Besides a conventional design with continuous main cutting edges 3 and secondary cutting edges 4, a design with interrupted secondary cutting edges 4 is also possible, as shown in Fig. 6. This may be intended for the medical treatment of fractures, depending on the intended use. The spiral drill shown in its entirety in Fig. 5 and partially in Fig. 6 can be designed without the described drill bit 6. The spiral drill according to Fig. 5 allows a surgeon to easily and safely create a hole in a human bone. An advantage is that, due to the thread 14 provided on the secondary cutting edges 4, the hole is thoroughly cleaned.Another advantage, especially when variations are made, for example through changing thread pitch, is that the insertion behavior of the spiral drill is adjusted to the respective application.
[0039] A drill 1 according to the invention is preferably used to create a hole in the treatment of proximal femur fractures, but is not limited to this application. A drill 1 according to the invention can be used particularly when, during drilling into a bone, the impact of the drill 1 with the drill bit 6 should be easily detectable and the drill 1 should be easily drawn into or inserted into the material.
Claims
Patent claims 1. Drill (1) for medical applications, in particular for drilling in bone, comprising a first end (11) and a second end (12), a cutting area (2) arranged at the first end (11) with cutting edges such as main cutting edges (3) and secondary cutting edges (4), a shank area (5) downstream of the cutting area (2) with a drill bit (6) arranged between the cutting area (2) and the second end (12), wherein the drill bit (6) is widened relative to the cutting area (2), characterized in that at least one external thread (8, 9) is arranged in the shank area (5) between an end face (7) of the drill bit (6) and the second end (12).
2. Drill (1) according to claim 1 , characterized in that the shank area (5) is longer than the cutting area (2).
3. Drill (1) according to claim 1 or 2, characterized in that the cutting area (2) and a first section (51) of the shank area (5) adjoining it and extending to the drill bit (6) are formed with a substantially constant maximum outer diameter.
4. Drill (1) according to one of claims 1 to 3, characterized in that an external thread (8, 9) is arranged on the drill bit (6).
5. Drill (1) according to one of claims 1 to 4, characterized in that the at least one external thread (8, 9) connects to and / or merges into the end face (7) of the drill bit (6).
6. Drill (1) according to one of claims 1 to 5, characterized in that the at least one external thread (8, 9) is interrupted, preferably interrupted several times, in particular by chip spaces (10).
7. Drill (1) according to one of claims 1 to 6, characterized in that a first external thread (8) and a second external thread (9) are provided, wherein the external threads (8, 9) are separated by a groove (13) extending between the external threads (8, 9).
8. Drill (1) according to claim 7, characterized in that the second external thread (9) is arranged between the drill bit (6) and the second end (12) and that the second external thread (9) is longer than the first external thread (8).
9. Drill (1) according to one of claims 1 to 8, characterized in that the at least one external thread (8, 9) is designed to be multi-start.
10. Drill (1) according to one of claims 1 to 9, characterized in that the at least one external thread (8, 9) is designed with a variable core diameter and / or variable thread pitch.
11. Drill (1), in particular twist drill, for medical applications, especially for drilling in bone, comprising a first end (11) and a second end (12), a cutting area (2) arranged at the first end (11) with cutting edges such as main cutting edges (3) and secondary cutting edges (4) and a shank area (5) downstream of the cutting area (2), which extends to a second end (12), characterized in that a thread (14) is formed on the cutting edges, in particular the secondary cutting edges (4), wherein the thread (14) is formed in particular with a variable thread pitch and / or a variable core diameter.
12. Set for the treatment of a bone fracture, in particular a proximal femur fracture, comprising a drill (1) according to any one of claims 1 to 11.
13. Method for drilling a hole, in particular a blind hole, wherein the hole is drilled into an object such as a bone, characterized in that a drill (1) according to one of claims 1 to 11 is used for drilling the hole.
14. Method according to claim 13, characterized in that an object with an opening such as an intramedullary bone nail is inserted into the object, after which the hole is drilled through the opening with the drill (1), wherein the drill (1) is axially displaced through the opening during drilling until the drill bit (6) of the drill (1) comes into contact with the object.
15. Method according to claim 14, characterized in that the drill (1) is rotated when placed against the object.