Self-drilling bone screw tip angle optimization
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Solution Overview
Problem
Self-drilling bone screws used in the craniofacial region often experience bending or breaking issues due to their tip angle, especially with longer screws, which complicates their insertion and stability during surgical operations.
Innovation Solution
A self-drilling bone screw with a thread pitch of approximately 0.7 to 1.0 mm and a tip angle of 34 to 43°, combined with a conical or cylindrical thread core and a large crest diameter, ensures the screw tip is robust and can be easily screwed into bone without bending or breaking, and features a torque-receiving structure for enhanced handling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a small tip angle is used to enable easy screwing into bone, then the screw can be easily inserted, but the screw tip bends or breaks during insertion
Solution Approach 1:
The patent optimizes the tip angle parameter to a specific range (34-43 degrees) and positions the first thread flank at a distance of 0.2-0.5 mm from the tip. This parameter optimization allows the screw to achieve both easy insertion and tip integrity by finding the optimal balance between cutting efficiency and structural strength.
2Length of moving object
If a longer screw length is used for better fixation, then the fixing stability is improved, but the screw tip is more prone to bending or breaking
Solution Approach 1:
The patent addresses this contradiction by optimizing the geometric parameters of the screw tip and thread structure. By positioning the first thread flank at 0.2-0.5 mm from the tip and using a tip angle of 34-43 degrees, the screw achieves adequate fixation length while preventing tip bending or breaking through improved structural design.
3Strength
If a smaller thread pitch is used for better bone engagement, then the pull-out resistance is improved, but the screwing speed decreases
Solution Approach 1:
The patent selects a thread pitch in the range of 0.7-1.0 mm, which provides an optimal balance between bone engagement strength and screwing speed. This parameter optimization ensures adequate pull-out resistance while maintaining efficient insertion speed for craniofacial applications.
Data Source
AI summary
A self drilling bone screw (10) comprises a shank (16) provided with a thread (14), a pitch of the thread (14) being in the region of approximately 0.7 to 1.0 mm. A tip angle is selected such that a thread flank (20) of a first flight (22) adjacent to a tip (18) of the bone screw (10) is arranged at a distance of approximately 0.2 to 0.5 mm from the tip (18) of the bone screw (10).