Skull Drill Bit Geometry for Single-Step Hearing Implant Cavities
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Solution Overview
Problem
Existing methods for installing bone anchored hearing aid implants are complicated, risk tissue damage, require large incisions, prolong healing time, and increase infection risk due to friction and heat, and involve multiple drilling steps that prolong surgery time.
Innovation Solution
A drill bit with a specific tip angle and diameter configuration, combined with a guiding tool, allows for a single-step drilling of a cavity or recess in the skull for an implantable fixture screw unit, minimizing tissue damage and reducing surgery time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Difficulty of detecting and measuring
If a standard biopsy punch is used to create a circular incision of 5-12 mm, then the incision provides sufficient visibility and allows irrigation fluid introduction, but the large circular incision prolongs healing time and introduces infection risk
Solution Approach 1:
The drill bit incorporates a reamer section with specific geometric features (land, parabolic surface) that locally enhance cutting efficiency and bone chip removal in the critical drilling zone, while the overall drill bit design maintains minimal incision size to reduce healing time and infection risk
2Manufacturing precision
If a first drill is used to generate a first cavity and then a widening drill is used to widen the cavity, then the cavity is properly prepared for the implant, but the operation surgery time is prolonged and switching drills may cause adverse consequences
Solution Approach 1:
The drill bit merges the functions of a first drill and a widening drill into a single integrated tool. The reamer section with its specific geometry allows the drill bit to perform both initial cavity creation and widening in one continuous operation, eliminating the need to switch tools and reducing surgery time while maintaining cavity preparation quality
Solution Approach 2:
The drill bit is designed with pre-configured geometric features (land, parabolic surface, flute blades) that enable it to perform multiple drilling functions from the outset. The reamer section is pre-formed to facilitate efficient bone chip removal and cavity widening without requiring subsequent intervention by a different drill tool
3Ease of manufacture
If the drill tip has a conventional angle, then the drill bit can be manufactured easily, but the cutting engagement with the skull material is insufficient
Solution Approach 1:
The drill bit employs a reamer section with specific geometric parameters including a land with a first angle (5-15 degrees), a parabolic surface with a second angle (10-30 degrees), and a helix angle (20-45 degrees). These optimized parameters enhance cutting engagement with the skull material while remaining manufacturable using conventional drilling and machining processes
4Manufacturing precision
If manual skin thinning is performed to achieve proper skin thickness, then the skin graft can be properly positioned, but the procedure becomes more complex and time-consuming
Solution Approach 1:
The drill bit design allows the surgeon to control skin thickness indirectly through the drilling process itself. By optimizing the drill bit geometry (reamer section angles, flute blade configuration) to efficiently remove bone and create the cavity, the procedure eliminates the need for separate manual skin thinning steps while still achieving proper skin thickness control through the drilling action and irrigation fluid flow
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables efficient, single-step drilling of a precise cavity for the implant, protecting soft tissue and reducing surgery time, while ensuring proper depth and alignment, thus minimizing complications and improving cosmetic outcomes.
Implementation Method 1
The drill tip comprises a tip angle of between 137 degrees to 143 degrees along a longitudinal axis of the drill bit. A tip angle of between 137 degrees and 143 degrees enables a sufficient engagement of the cutting lips of the drill tip with the skull material.
Data Source
AI summary
A drill bit for drilling a cavity or a recess into a skull, wherein the cavity or the recess is configured to receive an implantable fixture screw unit of a hearing aid system, is disclosed. The drill bit includes a first part including a drill tip with a first drill diameter, wherein the drill tip comprises a tip angle of between 137 degrees to 143 degrees along a longitudinal axis of the drill bit and wherein the drill tip comprises a back rake angle of between −1 degree and +1 degree, in particular a back rake angle of substantially 0 degrees, a second part including a plurality of flute blades with a second drill diameter, wherein the second drill diameter is greater that the first drill diameter, and a transition part which is arranged between the first part and the second part and along the longitudinal axis, wherein the transition part includes a body clearance.