Cannulated Bone Screw Flute Angles for Cleaner Bone Penetration
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Solution Overview
Problem
Cannulated bone screws with existing cutting flutes struggle to efficiently penetrate bone material, often causing damage and generating cutting fragments due to their scraping action rather than slicing, which affects insertion efficiency and tactile feedback during bone surgery.
Innovation Solution
A cannulated bone screw design featuring cutting flutes and teeth that extend to the distal end, oriented at specific angles (5-25 degrees) to facilitate a slicing action, minimizing bone damage and improving insertion efficiency by providing self-drilling functionality and reducing cutting fragments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If cannulation is extended through the bone screw body to allow guidewire guidance, then the ability to reach target location is improved, but the ability of the distal end to penetrate bone material deteriorates
Solution Approach 1:
The patent applies local quality by providing cutting flutes only at the distal end of the bone screw where penetration is needed, while the proximal portion maintains smooth cannulation for guidewire guidance. This localized differentiation allows each region to perform its specific function optimally without interfering with the other.
Solution Approach 2:
The cutting flutes are segmented from the main cannulated body, creating distinct functional zones. The flutes are positioned circumferentially around the distal end, separating the cutting function from the guidance function, allowing independent optimization of both capabilities.
2Productivity
If conventional cutting flutes are used in cannulated bone screws, then insertion is facilitated, but bone damage and fragment generation increase
Solution Approach 1:
The patent changes the geometric parameters of the cutting flutes, specifically the angle of the cutting faces relative to the longitudinal axis. By optimizing this angle, the cutting action becomes more efficient and produces cleaner cuts with fewer fragments, reducing bone damage while maintaining insertion efficiency.
3Productivity
If cutting flutes circumferentially interrupt the external thread, then cutting performance is improved, but threading engagement may be compromised
Solution Approach 1:
The cutting flutes are localized to specific circumferential positions and lengths, interrupting the threads only where cutting action is required at the distal end. This localized interruption provides cutting performance where needed while preserving thread engagement strength in the proximal regions where threads remain continuous.
Data Source
AI summary
A bone screw, comprising a proximal end and a distal end spaced from the proximal end in a distal direction along a longitudinal axis of the bone screw and a cannulation extending from the proximal end to the distal end. The bone screw further including a threaded region extending along at least a portion of a length of the screw, the length extending from the proximal end to the distal end. The threaded region defining at least one external thread that extends about the longitudinal axis along a helical path. The threaded region includes at least one flute that extends to the distal end of the bone screw. The at least one flute defines an associated at least one cutting tooth that, in turn, defines a cutting face oriented so as to define an angle with respect to the longitudinal axis. The angle is in the range of about 5 degrees and about 25 degrees, and the flute circumferentially interrupts at least a portion of the external thread.