Bone Plate Fastener With Serrated Thread For Selectable Angle Attachment
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Solution Overview
Problem
Existing bone plate systems lack the ability to securely attach fasteners to bone plates at a selectable angle, leading to instability and protrusion issues under load, and difficulty in customization for patient anatomy.
Innovation Solution
A bone plate system with apertures featuring internal threads and fasteners having a tapered proximal region with serrated threads, allowing for both coaxial threaded engagement and cross-threaded interference fit at various angles, providing stable locked engagement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a bone screw is cross-threaded into an aperture at a selectable angle, then the surgeon can customize the trajectory for a particular patient's anatomy, but the bone screw may wiggle and/or unlock under load
Solution Approach 1:
The proximal region of the fastener is given a different geometric quality (tapered conical shape) compared to the distal region (cylindrical). This local differentiation creates an interference fit at the proximal end while maintaining threaded engagement at the distal end, thereby stabilizing the fastener under load while preserving customizable trajectory.
Solution Approach 2:
The fastener is divided into two functional segments: a proximal tapered conical region that provides interference fit and stability, and a distal cylindrical region with external thread that provides threaded engagement. This segmentation allows each region to fulfill its specific function without compromising the other.
2Adaptability or versatility
If a bone screw is cross-threaded into an aperture at a selectable angle, then the surgeon can customize the trajectory, but the bone screw may protrude above the bone plate after installation
Solution Approach 1:
The patent changes the geometric parameters of the fastener by incorporating a tapered conical proximal region with a specific angle of taper. This parameter modification allows the fastener to engage at various angles while controlling the protrusion height through the interference fit mechanism.
3Reliability
If the angle of the proximal region taper is increased, then the interference fit and locked engagement are improved, but the fastener becomes more difficult to install
Solution Approach 1:
The proximal region is tapered at a moderate angle (less than 5 degrees) to provide sufficient interference fit without creating excessive resistance during installation. This partial tapering action achieves the desired locked engagement while maintaining ease of installation through controlled friction.
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
Enables secure and customizable attachment of fasteners to bone plates at selectable angles, reducing the likelihood of protrusion and instability under load, while allowing for effective bone fixation and alignment.
Implementation Method 1
the serrated thread is cross-threaded with the internal thread to create an interference fit and locked engagement
Implementation Method 2
The proximal region may be tapered conically toward the distal region... create an interference fit and locked engagement
Data Source
AI summary
Bone plate system, including methods and apparatus, for attaching a fastener to a bone plate at a selectable angle. In an exemplary method, a bone plate and a fastener may be selected. The bone plate may define an aperture having an internal thread. The fastener may include a proximal region and a distal region. The proximal region may be tapered conically toward the distal region. The fastener may be disposed in the aperture and in bone, such that the serrated thread is cross-threaded with the internal thread to create an interference fit and locked engagement of the proximal region with the aperture.