Self-Drilling Bone Anchor Thread Cutting Structure
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing bone anchor technologies require multiple procedural steps and often necessitate the use of additional instruments like pilot holes, K-wires, or awls, which increase the complexity and time required for insertion.
Innovation Solution
A self-drilling and/or self-tapping bone anchor with an additional cutting structure featuring a recess in the thread turn, which reduces the axial thickness of the thread and provides a sharper cutting edge, allowing for single-step insertion without pre-drilled pilot holes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If a self-drilling bone screw is used to insert directly into bone without pre-drilled pilot holes, then insertion time is reduced and procedural steps are simplified, but insertion torque increases and engagement with cortical bone becomes more difficult
Solution Approach 1:
The thread is divided into a first portion with first pitch and a second portion with second pitch. The first portion (deeper in bone) has a coarser pitch for stronger engagement, while the second portion (shallower, entering cortical bone first) has a finer pitch to reduce insertion torque and facilitate easier engagement with the denser cortical bone surface.
Solution Approach 2:
Different sections of the thread have different pitch characteristics tailored to their specific functional requirements. The shallower portion uses a finer pitch optimized for cortical bone engagement, while the deeper portion uses a coarser pitch optimized for cancellous bone engagement, allowing each region to perform its specific function optimally.
2Ease of operation
If additional cutting structure with recess in thread turn is added to reduce axial thickness and sharpen cutting edge, then penetration into bone is facilitated and insertion torque is reduced, but manufacturing complexity increases
Solution Approach 1:
The recess in the thread turn automatically performs the cutting function during insertion. As the bone anchor is driven into the bone, the recessed portion of the thread acts as a self-sharpening cutting edge that removes bone material, eliminating the need for separate cutting instruments or complex multi-component systems.
3Reliability
If multiple procedural steps including pilot hole preparation and use of additional instruments are used, then engagement with bone is ensured, but procedural complexity and time required increase
Solution Approach 1:
The bone anchor integrates multiple functions into a single device: the threaded shank provides both anchoring engagement and self-drilling capability, the recessed cutting structure provides self-sharpening cutting action, and the thread pitch variation provides both insertion facilitation and secure engagement. This eliminates the need for separate pilot holes, K-wires, or awls.
Solution Approach 2:
The bone anchor serves multiple functions simultaneously: it drills its own path through the self-sharpening recessed thread, taps its own thread engagement through the helical threading, and provides secure anchoring through the dual-pitch thread design. This multi-functional design replaces multiple specialized instruments with a single versatile device.
Data Source
AI summary
A bone anchor includes a shank having a longitudinal axis, a core, a tip at one end of the core, and a thread forming a helix that extends around the core with a lower flank directed towards the tip and an upper flank directed away from the tip. A recess in a first turn of the thread forms a cutting structure, the recess being defined by first and second surfaces directly connected to one another at an angle. The first and second surfaces are spaced apart from every other turn of the thread above or below the first turn. A majority of the first surface is positioned higher axially than and circumferentially aligned with part of the second surface. At least one of the first or second surfaces extends circumferentially around the shank by a greater distance than an axial height of the at least one surface.