Drill bit and drill bit kit

Abstract

The present application discloses a drill bit, a drill bit kit and a method for drilling a skull pocket hole or recess, wherein the drill bit (2) is for drilling a skull pocket hole (36) or recess configured to receive an implantable fixture screw unit of a hearing aid system, the drill bit (2) comprising: a first portion (4) comprising a drill tip (14) having a first bore diameter (d1), wherein the drill tip (14) comprises a top cone angle (a) along a longitudinal axis (X) of the drill bit (2) of between 137 degrees and 143 degrees, wherein the drill tip (14) comprises a back rake angle of between -1 degree and +1 degree, in particular substantially 0 degrees; a second portion (8) comprising a plurality of flutes (22) having a second bore diameter (d2), wherein the second bore diameter (d2) is larger than the first bore diameter (d1); a transition portion (6) disposed between the first portion (4) and the second portion (8) along the longitudinal axis (X), wherein the transition portion (6) comprises a drill body clearance (20).

Description

Technical Field

[0001] This invention relates to the field of drill bits, drill bit kits, and methods for drilling. More specifically, this invention relates to drill bits, drill bit kits, and methods for drilling cavities or recesses in the skull, wherein the cavities or recesses are configured to receive implantable fixation screw units of a hearing aid system. Background Technology

[0002] Medical implants such as bone-anchored hearing aid systems are used for the rehabilitation of patients suffering from hearing loss for whom conventional hearing aids are insufficient. A typical bone-anchored hearing aid system includes an external hearing aid with a vibrator transducer coupled to a bridge base inserted into the skin. The bridge base may have interconnections to an implantable fixation device screw unit anchored in the skull. The implantable fixation device is typically made of titanium and may have a flange to prevent the fixation device from being pushed through the skull in the event of exposure to a sudden, accidental impact.

[0003] The bridge abutment is inserted into the skin and subcutaneous tissue to establish a direct connection from the hearing aid processor to the skull (direct bone conduction).

[0004] Methods for installing bone-anchored hearing aid implantation systems are evolving towards minimally invasive approaches that can be performed quickly to minimize intraoperative and postoperative problems, achieve predictable outcomes, and deliver better cosmetic results.

[0005] However, existing incision techniques are quite complex and require a flap area to be created through the incision. Typically, a surgical scalpel is used to make an incision along the marked area down to the periosteum and separate the tissue from the underlying periosteum. Furthermore, all subcutaneous tissue in the graft area is separated from the tympanic membrane. Additionally, the subcutaneous tissue needs to be carefully separated from the skin graft, and all hair follicles must be removed. Moreover, a certain degree of artificial skin thinning is usually required.

[0006] Several attempts have been made to avoid using linear incision techniques for implanting bone-anchored hearing aids. Some of these attempts involve perforation techniques. These techniques utilize standard biopsy perforators to provide a 5-12mm circular incision.

[0007] These technologies have several drawbacks. These drawbacks include the risk of tissue damage due to friction, heat, and tearing caused by the movement of the drill bit.

[0008] Perforation techniques utilize perforations larger than 5 mm to allow for the introduction of irrigation fluid (to cool the bone tissue) during drilling and to provide adequate visibility. These large perforation diameters are not optimal for soft tissue bridging. Large, circular incisions will prolong healing time and introduce the risk of granulation tissue formation and subsequent infection. Furthermore, skin thickness needs to be determined preoperatively and / or intraoperatively.

[0009] Additionally, the minimally invasive Ponto surgical technique is known for implanting bone-anchored hearing aids. In this procedure, the incision is formed using a biopsy puncturist. Subsequently, the periosteum and soft tissue are removed from the implantation site. The drilling procedure involves two distinct drilling steps. A first drill bit is used to create the first cavity or recess. A widened drill bit is then used to widen the first cavity or recess and prepare the cavity or recess for the bone-anchored hearing aid implant. The use of different drill bits prolongs the procedure, and the switching, restarting, and realigning of the widened drill bit can lead to adverse outcomes for the cavity or recess to be drilled.

[0010] Therefore, a solution is needed that addresses at least some of the problems mentioned above. Summary of the Invention

[0011] According to a first exemplary aspect, a drill bit is provided for drilling cavities or grooves in the skull. The drill bit may include a first portion comprising a drill tip having a first bore diameter, wherein the drill tip includes a apex cone angle between 137 and 143 degrees along the longitudinal axis of the drill bit. An apex cone angle between 137 and 143 degrees facilitates drilling into relatively hard skull material. An apex cone angle between 137 and 143 degrees allows the cutting edge of the drill tip to engage sufficiently with the skull material. The first portion of the drill bit is the portion of the drill bit closest to the bone during drilling. The drill tip may include a point that engages with the bone; although the term "point" is used, a point includes any known structure that engages with the bone at the start of drilling, which facilitates penetration into the bone to create an initial hole. The drill tip may include a backslope angle between -1 and +1 degrees, particularly a substantially 0-degree backslope angle. The backslope angle describes the angle of the cutting face of the drill tip relative to the skull. A negative drill tip backslope angle results in a slightly blunt cutting edge design. This allows for increased tactile feedback while feeding the drill bit. Zero or positive inclination angles result in a sharper and more pointed drill bit. Consequently, the cutting forces and power required for the drilling step can be reduced. The length along the longitudinal axis of the first section can be less than the length along the longitudinal axis of the second section.

[0012] The drill bit may also include a second portion comprising a plurality of flutes having a second bore diameter, wherein the second bore diameter is larger than the first bore diameter. By providing a drill bit comprising a first bore diameter and a second bore diameter, wherein the second bore diameter is larger than the first bore diameter, a fossa or recess for an implantable fixation screw unit for a hearing aid system can be drilled in the skull in a single drilling step. This allows for a one-step final osteotomy of the implant. The bore diameter of the first or second portion of the drill bit can be defined as the maximum diameter along the longitudinal axis of the first or second portion of the drill bit.

[0013] The drill bit may also include a transition portion disposed along the longitudinal axis between the first portion and the second portion, wherein the transition portion includes a drill body clearance.

[0014] According to another aspect, a drill bit kit is provided, comprising a drill bit according to a first exemplary aspect and a guide tool. The guide tool may include a hollow tube, wherein the diameter of the hollow tube is larger than a second borehole diameter. Thereby, soft tissue can be protected from the impact of the drill bit. Additionally, brine or coolant can be filled into the guide tool for cooling during the drilling process. The guide tool can serve as a hard stop for the drill bit, allowing for control of the drilling depth.

[0015] According to another aspect, a method is provided for drilling a cavity or recess in the skull, wherein the cavity or recess is configured to receive an implantable fixation screw unit of a hearing aid system. The method may include forming an incision hole in the bone layer of the skull using a first tool. The incision hole may be formed using a perforating tool.

[0016] The method may further include cleaning the incision hole using a cleaning tool. Additionally, the step of cleaning the cavity or recess may include removing the periosteum and soft tissue. The method may also include placing a guide tool within the cleaned cavity or recess, wherein the guide tool comprises a hollow tube. The method may further include applying a drill bit into the hollow tube and drilling the cavity or recess in a single step. The step of drilling the cavity or recess in a single step can be performed without switching drill bits. The cavity or recess has a diameter and depth that matches the size of the implant, such that the implant can be screwed into the cavity or recess. In an embodiment, the implant includes an implant for a bone-anchored hearing aid.

[0017] Further exemplary features of all aspects of the invention will be described in more detail below.

[0018] Hearing aid systems are generally understood to include hearing aids (also referred to as hearing devices, hearing instruments, or hearing aids) that are adapted to improve or enhance a user's hearing ability. This is achieved by receiving sound signals from the user's environment, generating corresponding audio signals, possibly modifying those audio signals, and providing the possibly modified audio signals as audible signals to at least one of the user's ears. "Improving or enhancing a user's hearing ability" may include compensating for the specific hearing loss of an individual user. "Hearing aid" may also refer to a device adapted to electronically receive audio signals, possibly modify those audio signals, and provide the possibly modified audio signals as audible signals to at least one of the user's ears, such as wearable devices, headphones, or headsets. The audible signals may be provided, for example, as sound signals radiating into the user's outer ear, sound signals transmitted as mechanical vibrations through the bone structures of the user's head and / or through parts of the middle ear to the user's inner ear, and electrical signals transmitted directly or indirectly to the user's cochlear nerve and / or auditory cortex.

[0019] Hearing aids for the hearing system are suitable for wearing in any known manner. This may include: attaching the hearing aid unit to a fixed structure implanted within the skull, such as in a bone-anchored hearing aid; or having the hearing aid unit as a whole or part of the implanted unit, such as in a bone-anchored hearing aid. Hearing aids may be implemented in a single unit (shell) or in multiple units individually connected to each other.

[0020] In embodiments of the invention, each of the plurality of flutes in the second portion of the drill bit may include at least one cutting edge, wherein the second portion includes a parabolic or substantially parallel opposing surface, particularly forming a cross-section, extending between the cutting edges of the plurality of flutes. The cutting edge of a flute may be defined as the outer portion of the flute between two adjacent flutes. The parabolic or substantially parallel surface of the second portion results in improved bone fragment extraction. Additionally, the total drilling work can be reduced, enabling efficient removal of bone volume.

[0021] The second part may include multiple fluting edges having a thickness between 0.10 mm and 0.40 mm. The thickness of the cutting edges of the multiple fluting edges is beneficial to the cutting efficiency of the drill bit.

[0022] A pair of adjacent flutes can form a groove between them, wherein the thickness of the groove or flute can vary along the drill bit, particularly along its longitudinal axis. This allows for optimization of the drill bit's thickness distribution with respect to force and torque. The thickness of the groove can vary between 0.8 mm and 1.2 mm.

[0023] The second part of the drill bit may include at least two fluting edges, such as two, three, four or more fluting edges, along the longitudinal axis of the drill bit.

[0024] The second or transition section of the drill bit may include a positive or negative rake angle. The rake angle describes the angle of the cutting face relative to the workpiece (such as a skull). A negative rake angle in the second or transition section results in increased tactile feedback when feeding the drill bit. A positive rake angle results in a reduction in cutting force and power required. The rake angle of a fluting edge can be between -3 degrees and +3 degrees, but not 0 degrees.

[0025] The second part of the drill bit may include a helix angle between the longitudinal axis and the fluting direction, particularly the fluting plane, which is between 20 and 30 degrees, especially between 24 and 26 degrees. The second part of the drill bit may also include a 25-degree helix angle between the longitudinal axis and the direction of the fluting along the longitudinal axis. The aforementioned helix angle results in increased bone fragment removal and is beneficial to the drill bit's feed rate.

[0026] The transition portion of the drill bit may include a region with a constant diameter along the longitudinal axis. The length of the region with a constant diameter along the longitudinal axis may be between 1.05 mm and 1.55 mm. Preferably, the region with a constant diameter does not have a cutting edge.

[0027] The drill body clearance of the transition section of the drill bit may include a minimum diameter equal to, preferably equal to, the minimum diameter of the first section, and a maximum diameter equal to, the diameter of the second section. This provides a smooth transition between the first and second sections of the drill bit.

[0028] The drill body clearance of the transition section may include a transition angle of 7 to 13 degrees along the longitudinal axis and between the minimum and maximum diameters of the transition section. The transition angle can be defined as the angle between a plane perpendicular to the longitudinal axis of the drill bit and the drill body clearance of the transition section of the drill bit. This transition angle facilitates the creation of a cavity or groove in the skull using a single drill bit in a drilling step.

[0029] The first length along the longitudinal axis and between the drill tip and the maximum diameter of the transition portion can be between 4.65 mm and 4.75 mm. The drill bit can have a first borehole diameter between 3.78 mm and 3.82 mm.

[0030] Drill tips may include cutting edge angles ranging from 7 to 13 degrees. A cutting edge angle can be defined as the angle formed by the side face of the drill tip and a plane perpendicular to the longitudinal axis. The cutting edge angle provides advantageous strength and stiffness to the cutting edge. The cutting edge angle can also be defined as the clearance angle of the drill tip.

[0031] The drill tip may include a web thickness between 0.20 mm and 0.30 mm, particularly between 0.24 mm and 0.26 mm. Web thickness refers to the thickness of the drill tip in a plane perpendicular to the longitudinal axis. The aforementioned web thickness facilitates the thrust required when applying the drill bit to penetrate the skull.

[0032] Guide tools protect soft tissue during drilling, ensure the correct drilling depth (thus preventing excessively deep grooves or cavities), and contribute to adequate flushing. Furthermore, guide tools ensure that grooves or cavities form perpendicular to the bone and / or skin surface.

[0033] The guide tool or hollow tube therein may include external threads for securing the guide tool to the operating position by screwing it into soft tissue.

[0034] The thickness of the hollow tube of the guide tool can be varied to support the drill bit and provide space for flushing or for coolant within the hollow tube. The hollow tube of the guide tool may include an upper portion having a first inner diameter, a lower portion having a second inner diameter, and a middle portion located between the upper and lower portions. The inner diameter of the middle portion can be varied to connect the upper portion to the lower portion. The first inner diameter may be larger than the second inner diameter. Similarly, the first inner diameter may be smaller than the second inner diameter.

[0035] The guiding tool may include a hollow channel connected to a hollow tube to provide coolant or saline to the bottom of the osteotomy. The hollow channel may be positioned substantially perpendicular to the hollow tube. The guiding tool may also include multiple hollow channels and / or gaps to enable the transport of bone fragments outside the guiding tool. The hollow channels and / or gaps for bone fragments may be located in the upper part of the guiding tool such that soft tissue does not cover the hollow channels and / or gaps during the drilling process.

[0036] The drill bit may include a region with an extended diameter that contacts a hard stop of the guide tool upon reaching a predetermined drilling depth. This prevents the drill bit from spinning freely upon reaching the bottom of the bone cut.

[0037] A guide tool can be attached to the drill bit, wherein the guide tool and the drill bit are connected such that the guide tool does not rotate with the drill bit to protect soft tissue. Alternatively, the guide tool and the drill bit can be connected such that the guide tool rotates with the drill bit. The drilling depth can be controlled via a flexible tube mechanism integrated into the lower part of the hollow tube.

[0038] The perforator can be integrated into the bottom of the hollow tube of the guide tool, allowing the drill kit to also be used to provide incision holes in the bone layers of the skull.

[0039] The drill bit can be connected to and / or coupled to a handheld device via a spring mechanism. When force is applied to the drill bit, for example, when the drill bit is pressed against the skull during drilling, the spring connection can be activated, allowing the handheld device to drive the drill bit. When no force is applied to the drill bit, the spring connection can disengage the drill bit from the handheld device, stopping the drill bit's rotation. This prevents the drill bit from rotating while drilling through the skull.

[0040] The spring mechanism may include a spring coupling, wherein the spring coupling may include at least two spring elements. The spring elements may be arranged relative to each other in a horizontal or vertical plane.

[0041] The slit hole is created in the soft tissue by pressing the sharp blade of the cylindrical hollow perforated piece through it. The cylindrical hollow perforated piece is then pulled out, and the soft tissue removed during the perforation is removed from the slit hole.

[0042] The implantable fixation screw unit can be configured to receive a bone conduction hearing aid system. The implantable fixation screw unit may include an elongated portion, a first end of which is threaded and configured to anchor in the recipient's skull via a recess or groove drilled in the skull. The elongated portion may include a second end configured to receive a skin bridge unit, which is also configured to receive a bone conduction hearing aid system. Variations in the patient's skin thickness are addressed using skin bridge units of varying lengths. The outer surface of the elongated portion can be modified using laser ablation to roughen the outer surface, thereby improving osseointegration of the implantable fixation screw unit.

[0043] The unthreaded portion of the elongated section can have a length ranging from 3mm to 12mm, 3mm to 9mm, or 3mm to 8mm. The length of the unthreaded portion of the elongated section can be perpendicular to the skull. This length can be adapted to the thickness of the soft tissue on the patient's skull.

[0044] The skin bridge unit can have a thickness of 3mm to 12mm, 3mm to 9mm, or 3mm to 8mm, perpendicular to the skull.

[0045] The skin bridge base unit can be attached to the elongated portion by screwing it onto the elongated portion or by a snap-fit ​​connection, wherein the skin bridge base unit is pressed onto the elongated portion by movement along an axis perpendicular to the skull.

[0046] The implantable fixation screw unit can be made of shape memory metal, such as Nitinol, or one or more alloys of the following combinations: Ag–Cd, Au–Cd, Cu-Al–Ni, Cu–Sn, Cu–Zn, Cu-Zn-(Si,Sn,Al), In–Ti, Ni–Al, Ni–Ti, Fe–Pt, and Mn–C.

[0047] The skin bridge unit can be formed together with the elongated portion as a single piece (integral).

[0048] The diameter of the unthreaded portion of the slender section is smaller than the diameter of the threaded portion of the slender section. The diameter of the unthreaded portion of the slender section is smaller than the diameter of the skin bridge base unit.

[0049] The unthreaded portion of the slender section can be made of an elastic material, such as a NiTi alloy, a superelastic polymer, or a superelastic ceramic. However, the disadvantages of using such materials are as follows:

[0050] - Forces applied to the slender portion during use or trauma will not be fully transmitted to the implant, but will instead cause the slender portion to bend;

[0051] Compared to titanium or steel, hyperelastic materials such as NiTi alloys exhibit e-modulus and stress-strain behavior more similar to those of microstructures. Actions such as scratching, chewing, turning the head, and speaking will cause movement of the soft tissue around the bridge abutment, thereby generating interfacial stresses around the abutment.

[0052] The disadvantages of having a flexible implantable fixation screw unit can be reduced by reducing the diameter and / or length of the implantable fixation screw, for example, the slender portion. Reducing the diameter of the implantable fixation screw leads to another challenge, such as how to attach a bone conduction hearing aid to the implantable fixation screw unit.

[0053] To address the issues caused by reduced diameter, the implantable fixation screw unit may include two or more elongated portions, wherein the unthreaded portion of the elongated portion is made of an elastic material such as a NiTi alloy, a hyperelastic polymer, or a hyperelastic ceramic. In this example, the diameter of the unthreaded portion of the elongated portion is smaller than the diameter of the threaded portion of the elongated portion. The diameter of the unthreaded portion of the elongated portion is smaller than the diameter of the skin bridge base unit.

[0054] A bone conduction hearing aid system can be configured to connect either directly or via an adapter unit to two or more elongated portions. The adapter unit is configured to interconnect the two or more elongated portions on a first surface and connect to the bone conduction hearing aid system on a second surface, wherein the first and second surfaces are opposite each other. Instead of connecting a skin bridge unit to each of the two or more elongated portions, it is advantageous to interconnect the two or more elongated portions with the adapter unit without connecting the skin bridge unit to the two or more elongated portions. This reduces the distance from the skin surface to the bone conduction hearing aid system applied to the implantable fixation screw unit.

[0055] The shape of two or more elongated sections can be straight. In another example, the two or more elongated sections can be irregular or conical, resulting in a smaller diameter at the first end of the elongated section where the skin bridge unit or transition unit is applied. Conical or irregular shapes are beneficial for stability because only a limited portion of the elongated section (near the first end) bends / flexes when subjected to lateral forces from the bone conduction hearing aid system.

[0056] The slender portion may have a diameter that varies along its length according to the profile, which may be an irregular profile, a conical profile, or an hourglass profile.

[0057] The features mentioned above should be considered as disclosed in any combination of each other. Furthermore, disclosure of any means for performing the method steps should be understood as also disclosing the corresponding method steps, and disclosure of the method steps should be understood as also disclosing the corresponding means for performing those steps. Attached Figure Description

[0058] Various aspects of the invention will be best understood from the following detailed description taken in conjunction with the accompanying drawings. For clarity, these drawings are schematic and simplified, showing only the details necessary for understanding the invention while omitting other details. Throughout the specification, the same reference numerals are used for the same or corresponding parts. Features of each aspect may be combined with any or all features of other aspects. These and other aspects, features, and / or technical effects will be apparent from and illustrated in the following figures, wherein:

[0059] Figure 1 A perspective view of a drill bit according to an embodiment of the present invention is shown schematically;

[0060] Figure 2 schematically shown Figure 1 Detailed illustrations of the embodiments shown;

[0061] Figure 3 schematically shown Figure 2 AA section diagram;

[0062] Figure 4 schematically shown Figure 1 Side view of the embodiment shown;

[0063] Figure 5A The diagram schematically illustrates a cavity or groove drilled using two drill bits according to the prior art.

[0064] Figure 5B The illustration schematically shows a hole or groove drilled using a drill bit according to an embodiment of the present invention;

[0065] Figure 6 A perspective view of a guide tool according to an embodiment of the present invention is shown schematically;

[0066] Figure 7 A cross-sectional view of a guiding tool according to an embodiment of the present invention is shown schematically;

[0067] Figure 8 A schematic front view of a guide tool according to an embodiment of the present invention is shown;

[0068] Figures 9A-9C An example of an implantable fixation device screw unit is shown;

[0069] Figures 10A-10B An example of an implantable fixation device screw unit is shown;

[0070] Figure 11A-11C Examples of implantable fixation device screw units and adapter units are shown. Detailed Implementation

[0071] The detailed description below, taken in conjunction with the accompanying drawings, serves as a description of various different configurations. This detailed description includes specific details to provide a thorough understanding of several different concepts. However, it will be apparent to those skilled in the art that these concepts can be implemented without these specific details. Several aspects of the apparatus and method are described by various different blocks, functional units, modules, elements, circuits, steps, processes, algorithms, etc. (collectively, “elements”). Depending on the specific application, design constraints, or other reasons, these elements may be implemented using electronic hardware, computer programs, or any combination thereof.

[0072] Now for reference Figure 1The illustration shows a perspective view of a drill bit 2 for drilling holes or grooves in the skull according to an embodiment of the present invention. The drill bit 2 includes a first portion 4, a transition portion 6, and a second portion 8. The transition portion 6 is disposed between the first portion 4 and the second portion 8. The drill bit 2 includes a shank 10 for connecting the drill bit 2 to a handheld device. An annular flange 12 is provided between the second portion 8 and the shank 10.

[0073] The first length of the first part 4 of the drill bit 2 is less than the second length of the second part 8 of the drill bit 2. The length l1 along the longitudinal axis X and between the end of the drill tip 14 and the maximum diameter of the transition part 6 can be between 4.65 mm and 4.75 mm.

[0074] like Figure 2 As shown, the first portion 4 of the drill bit 2 includes a drill tip 14 having a tip cone angle α between 137 degrees and 143 degrees along the longitudinal axis X of the drill bit 2. The first portion 4 of the drill bit 2 is the part of the drill bit 2 closest to the bone during drilling.

[0075] The first part 4 also includes a first drilling diameter d1, which is the boundary side 16 of the drill tip 14. The drill tip 14 may have a first drilling diameter d1 between 3.78 mm and 3.82 mm. The second part 8 may have a second drilling diameter d2, which is larger than the first drilling diameter d1. By providing a drill bit 2 including a first drilling diameter d1 and a second drilling diameter d2, wherein the second drilling diameter d2 is larger than the first drilling diameter d1, a socket or recess for an implantable fixation screw unit for a hearing aid system can be drilled in the skull in a single drilling step. This allows for a one-step final osteotomy of the implant.

[0076] The first part 4 of drill bit 2 also includes a cutting edge angle β. For example... Figure 3 As shown, the cutting edge angle β can be defined as the angle formed by the side 16 of the drill tip and a plane perpendicular to the longitudinal axis X. The cutting edge angle can be between 7 degrees and 13 degrees.

[0077] The drill tip 14 of drill bit 2 includes a back rake angle of essentially 0 degrees. The essentially 0-degree back rake angle results in a sharp drill tip 14, thereby reducing the cutting force and power required for the drilling step.

[0078] The transition portion 6 includes a region 18 with a substantially constant diameter along the longitudinal axis X. The length l of region 18 is... rBetween 1.05 mm and 1.55 mm, and in region 18, the cutting edge may be excluded. The transition portion 6 may also include a drill body clearance 20, wherein the drill body clearance 20 includes a transition angle γ of 7 to 13 degrees. The transition angle γ is defined as the angle between a plane perpendicular to the longitudinal axis X of the drill bit 2 and the drill body clearance 20 of the transition portion 6 of the drill bit 2. The aforementioned transition angle γ is advantageous for providing a fossa or groove in the skull with a single drill bit 2 in a single drilling step.

[0079] Figure 4 It shows Figure 1 A side view of the embodiment shown. (As shown) Figure 4 As shown, the second part 8 of the drill bit 2 includes two flutes 22 having a second drilling diameter d2. Since the drilling diameter d2 is larger than the drilling diameter d1, it is advantageous to drill a cavity or groove for an implantable fixation screw unit for a hearing aid system within the skull in a single drilling step.

[0080] Each of the notches 22 includes a cutting edge 24. The cutting edge 24 can be defined as the exterior of the body of the second portion 8 that forms the boundary of the notch 22. Two notches 26 are provided between the two notches 22. The opposing surfaces of the notches 22 extending between their cutting edges 24 may include parabolic or substantially parallel cross sections. The parabolic or substantially parallel surfaces of the notches 22 or the notches 26 result in improved bone fragment extraction. In addition, the total drilling work of the drill bit 2 can be reduced, enabling efficient removal of bone volume.

[0081] Each fluting edge 22 includes a cutting edge 28. The cutting edge 28 confines the fluting band 24 to the cutting side of the fluting edge 22. The thickness of the cutting edge 28 can be between 0.10 mm and 0.40 mm. Cutting edge thicknesses within the aforementioned range are beneficial to the cutting efficiency of the drill bit 2.

[0082] The thickness of the flute 22 can vary along the drill bit 2, especially along the longitudinal axis X of the drill bit 2. This allows for optimization of the thickness distribution of the drill bit 2 with respect to force and torque. The thickness of the flute can be between 0.8 mm and 1.2 mm.

[0083] The second part 8 of the drill bit 2 includes a helix angle δ between 24 and 26 degrees, particularly a helix angle δ of substantially 25 degrees, between the longitudinal axis X and the plane of the fluting edge 22. This range of helix angles δ can facilitate bone fragment removal and the feed rate of the drill bit 2.

[0084] Figure 5A and 5B A schematic cross-sectional view shows the fossa or groove drilled into the skull. Figure 5AThe cavity 30 is drilled using two drill bits according to the prior art. Initially, a first drill bit is used to create a first cavity 32. Subsequently, a widening drill bit is used to widen the first cavity or recess 32 and drill a wider cavity 34, thus preparing the cavity or recess 30 for the implant in a bone-anchored hearing aid. The use of different drill bits prolongs the procedure, and the switching, restarting, and realigning of the widening drill bit can lead to adverse results for the cavity or recess to be drilled. By using the drill bit 2 according to the invention, the cavity 36 can be drilled in one step. Therefore, the aforementioned disadvantages are avoided.

[0085] Figure 6 A perspective view of a guide tool 38 according to an embodiment of the present invention is schematically shown. The guide tool 38 is preferably part of a drill bit kit including the drill bit 2 and the guide tool 38. The guide tool 38 can protect soft tissue during drilling, ensure the correct drilling depth (thus preventing excessively deep cavities 36), and contribute to adequate flushing. In addition, the guide tool 38 can ensure that the cavities 36 are formed perpendicular to the bone and / or skin surface.

[0086] The guide tool 38 includes a hollow tube 40 having an externally threaded portion 42 for securing the guide tool 38 to an operating position by screwing it into soft tissue. The guide tool 38 also includes a portion 44 with an enhanced width, which can serve as a mechanical stop for at least one drill bit 2. This portion 44 is limited by two vertical flanges 46 that can be used when manipulating the guide tool 38.

[0087] The diameter of the hollow tube 40 can be varied to support the drill bit 2 and provide space for a flushing chamber or for coolant within the hollow tube 40. Figure 7 A cross-sectional view of a guide tool 38 according to an embodiment of the present invention is schematically shown. The guide tool 38 has a hollow tube 40 with a varying inner diameter. The hollow tube 40 includes an upper portion 48 having a first inner diameter, a lower portion 52 having a second inner diameter, and a middle portion 50 located between the upper and lower portions. The inner diameter of the middle portion 50 is variable to connect the upper portion 48 to the lower portion 52. Figure 7 In the hollow tube 40 shown, the first inner diameter of the upper part 48 is smaller than the second inner diameter of the lower part 52.

[0088] Figure 8 A schematic front view of a guide tool 38 according to an embodiment of the present invention is shown. The guide tool 38 includes a hollow channel 56 connected to a hollow tube 40 for supplying coolant or saline to the bottom of the osteotomy. The hollow channel 56 may be configured substantially perpendicular to the hollow tube 40.

[0089] Figure 9A , 9BFigure 9C schematically illustrates an implantable fixation screw unit 60 configured to receive a bone conduction hearing aid system. The implantable fixation screw unit 60 may include an elongated portion 62, wherein a first end of the elongated portion is threaded 63 and configured to be anchored in the recipient's skull via a notch or groove drilled in the skull. The elongated portion 62 may include a second end configured to receive skin bridge units (64, 64A, 64B), which are configured to receive the bone conduction hearing aid system. Variations in the patient's skin thickness are addressed by skin bridge units of different lengths (64, 64A, 64B).

[0090] The skin bridge base unit 64 can be connected to the elongated portion by screwing (64A) onto it or by a snap-fit ​​connection (64B), wherein the skin bridge base unit (64, 64A, 64B) is pressed onto the elongated portion 62 by movement along an axis perpendicular to the skull.

[0091] Figure 10A and 10B Another example of an implantable fixation device screw unit 60 is shown. The implantable fixation device screw unit 60 includes two or more elongated portions (62A, 62B), wherein the unthreaded portions (62A, 62B) are made of an elastic material. Figure 10A In the middle, the slender portions (62A, 62B) are straight. Figure 10B In this context, the elongated portions (62A, 62B) are either irregularly shaped or conical. In other examples, two or more elongated portions may have the same or different shapes. The diameter of the unthreaded portions (62A, 62B) is smaller than the diameter of the threaded elongated portion 63. The diameter of the unthreaded portions (62A, 62B) of the elongated portions is smaller than the diameter of the skin bridge base unit (64, 64A, 64B).

[0092] The bone conduction hearing aid system can be configured to connect to two or more elongated sections (62A, 62B), or directly to the skin bridge unit (64, 64A, 64B), or via the adapter unit 65. Figure 11A-11C An example of an adapter unit 65 is shown. The adapter unit 65 is configured to interconnect two or more elongated portions (62A, 62B) on a first surface 67 and to connect to a bone conduction hearing aid system 70 on a second surface 66, wherein the first surface 67 and the second surface 66 are opposite each other. See [reference needed] Figure 11B Instead of connecting the skin bridge base units (64, 64A, 64B) to each of the two or more elongated portions, it would be advantageous to connect the two or more elongated portions to the transition unit 65 without connecting the skin bridge base units to the two or more elongated portions. See [link to relevant documentation]. Figure 11BThis reduces the distance from the skin surface to the bone conduction hearing aid system applied to the implantable fixation screw unit.

[0093] When appropriately replaced by a corresponding process, the structural features of the apparatus described above, in detail in the "Detailed Description" section, and as defined in the claims can be combined with the steps of the method of the present invention.

[0094] Unless explicitly stated otherwise, the singular forms “a” and “the” used herein include the plural forms (i.e., meaning “at least one”). It should be further understood that the terms “having,” “comprising,” and / or “including” as used in the specification indicate the presence of the stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or combinations thereof. It should be understood that, unless explicitly stated otherwise, when an element is referred to as “connected” or “coupled” to another element, it may be a direct connection or coupling to the other element, or there may be intermediate inserting elements. The term “and / or” as used herein includes any and all combinations of one or more of the listed related items. Unless explicitly stated otherwise, the steps of any method disclosed herein do not necessarily have to be performed in the exact order disclosed.

[0095] It should be understood that references to "an embodiment," "an embodiment," "an aspect," or "may" in this specification mean that a particular feature, structure, or characteristic described in connection with that embodiment is included in at least one embodiment of the invention. Furthermore, particular features, structures, or characteristics may be suitably combined in one or more embodiments of the invention. The foregoing description is provided to enable those skilled in the art to implement the various aspects described herein. Various modifications will be apparent to those skilled in the art, and the general principles defined herein may be applied to other aspects. Unless expressly stated, elements referred to in the singular do not mean "one and only one," but rather "one or more." Unless expressly stated, the term "some" means one or more.

[0096] Therefore, the scope of this invention should be determined based on the claims.

Claims

1. A drill (2) for drilling a cavity (36) or groove in the skull, wherein the cavity (36) or groove is configured to receive an implantable fixation screw unit of a hearing aid system, the drill (2) comprising: The first part (4) includes a drill tip (14) having a first borehole diameter (d1), wherein the drill tip (14) includes a top cone angle (α) between 137 degrees and 143 degrees along the longitudinal axis (X) of the drill bit (2), wherein the drill tip (14) includes a backslope angle between -1 degree and +1 degree; The second part (8) includes a plurality of grooves (22) having a second bore diameter (d2), wherein the second bore diameter (d2) is greater than the first bore diameter (d1); A transition portion (6) is disposed along the longitudinal axis (X) between the first portion (4) and the second portion (8), wherein the transition portion (6) includes a drill body clearance portion (20).

2. The drill bit according to claim 1, wherein, Each of the plurality of fluted edges (22) of the second portion (8) includes at least one cutting edge (24), wherein the second portion (8) includes parabolic or substantially parallel opposing surfaces extending between the cutting edges (24) of the plurality of fluted edges (22).

3. The drill bit according to claim 1 or 2, wherein, The plurality of grooving edges (22) include cutting edges (28) having a thickness between 0.10 mm and 0.40 mm.

4. The drill bit according to claim 1, wherein, The slot (26) is provided between adjacent slotting edges (22), wherein the thickness of the slot (26) varies along the drill bit (2) and / or wherein the thickness of the slot (26) is between 0.8 mm and 1.2 mm.

5. The drill bit according to claim 1, wherein, The second part (8) or the transition part (6) includes a positive or negative backslope angle, and / or the backslope angle of the grooved edge (22) is in the range of -3 degrees to +3 degrees but does not include 0 degrees.

6. The drill bit according to claim 1, wherein, The second part (8) includes a helix angle (γ) between 20 and 30 degrees between the direction of the longitudinal axis (X) and the groove (22).

7. The drill bit according to claim 1, wherein, The transition portion (6) includes a region (18) having a substantially constant diameter along the longitudinal axis (X), and / or the length (l) of the region (18) having a constant diameter along the longitudinal axis. r The area (18) of the constant diameter is between 1.05 mm and 1.55 mm and / or does not have a cutting edge.

8. The drill bit according to claim 1, wherein, The drill body clearance (20) includes a minimum diameter equal to the minimum diameter of the first part (4) and a maximum diameter equal to the diameter of the second part (8).

9. The drill bit according to claim 1, wherein, The drill body clearance (20) includes a transition angle (γ) of 7 to 13 degrees along the longitudinal axis (X) and between the minimum and maximum diameters of the transition portion (6).

10. The drill bit according to claim 1, wherein, The length (l1) along the longitudinal axis (X) and between the tip of the drill bit (14) and the maximum diameter of the transition portion (6) is between 4.65 mm and 4.75 mm.

11. The drill bit according to claim 1, wherein, The drill tip (14) has a first borehole diameter (d1) between 3.78 mm and 3.82 mm, and / or the drill tip (14) includes a cutting edge angle (β) between 7 degrees and 13 degrees.

12. The drill bit according to claim 1, wherein, The drill tip (14) includes a backslope angle of approximately 0 degrees.

13. The drill bit according to claim 6, wherein, The helix angle (γ) is between 24 and 26 degrees.

14. A drill bit kit comprising a drill bit according to any one of claims 1-13, wherein the drill bit kit further comprises a guide tool (38), wherein the guide tool (38) comprises a hollow tube (40), wherein the diameter of the hollow tube (40) is greater than the diameter of a second borehole (d2).

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