Bone Plate Elastic Screw Hole Fixation
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Solution Overview
Problem
Existing bone plates with screw fixation systems have limited adjustment ranges, leading to potential over-tightening or screw sticking, and existing solutions either lack secure engagement or cause material damage due to thread mismatch and plastic deformation.
Innovation Solution
A bone plate design with elastically deformed areas surrounding screw holes that adapt to the screw head's cone, allowing secure screw engagement without irreversible deformation, and a screw head with a conical external thread and cylindrical internal thread, ensuring the screw head can be fully seated without protruding, and the plate remains undamaged.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conical external thread of the screw head engages in a cylindrical internal thread of the plate, then the screw can be tightened and fixed in the screwing direction, but the adjustment range of the screw is limited and the screw may become stuck suddenly
Solution Approach 1:
The patent introduces an elastic deformation area in the plate surrounding the screw hole that dynamically adapts to the conical screw head during tightening. This elastic area allows the plate to flex and accommodate the screw head's conical shape, enabling continuous adjustment throughout the entire screw path without sudden sticking, while still providing firm fixation when tightened.
Solution Approach 2:
The patent changes the physical state of the plate material in the screw hole area from rigid to elastically deformable. By designing the plate with an elastic deformation area that can reversibly change its shape and size, the system achieves both secure engagement (when deformed to match the screw head) and wide adjustment range (throughout the elastic deformation path).
2Strength
If the area surrounding the screw hole is made rigid to maintain plate structural integrity, then the plate strength is maintained, but the screw head cannot be fully seated without causing plastic deformation or material damage
Solution Approach 1:
The patent applies local quality by creating a differentiated structure: the majority of the plate remains rigid to maintain overall strength and structural integrity, while a specific local area surrounding the screw hole is designed with elastic deformability. This localized elastic area allows the screw head to be fully seated with precise engagement, while the surrounding rigid plate structure maintains its strength and prevents plastic deformation.
3Reliability
If the screw head is allowed to protrude beyond the plate surface to ensure full engagement, then secure fixation is achieved, but the plate does not nestle smoothly against the bone
Solution Approach 1:
The elastic deformation area dynamically adjusts during the tightening process, allowing the screw head to sink into the plate as the elastic area deforms. This dynamic adaptation ensures the screw head achieves full engagement and secure fixation while simultaneously maintaining a smooth plate contour that nestles against the bone surface without protrusions.
4Ease of manufacture
If a conventional threaded hole design is used, then manufacturing is simple, but the thread cuts into the plate producing material chips that endanger the patient
Solution Approach 1:
The patent changes the mechanical behavior of the plate material in the screw hole area from purely rigid to elastically deformable. This parameter change allows the material to flex and accommodate the screw thread engagement without fracturing or producing chips, while still maintaining ease of manufacture through conventional drilling and threading processes.
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 design enhances screw adjustment range, prevents over-tightening, and ensures a secure, non-disruptive fit with the bone, minimizing the risk of material deformation and breakage, while maintaining anti-rotation stability and smooth conformation to the bone surface.
Implementation Method 1
The area adjoining the external thread of the plate is elastically deformed in such a way that it adapts to the outside diameter of the cone of the internal thread
Data Source
Figure 1~2
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AI summary
Disclosed is a bone plate comprising at least one screw that is to be fixed at a stable angle to at least one through-hole and at least one bone screw which is provided with an external thread in the top region. Said external thread tapers more in the screwing direction than a mating thread of the through-hole embodied as an internal thread such that the top of the bone screw is clamped in a stable direction in a torsion-proof manner when the bone screw is screwed in. The bone plate (1) is configured elastically in at least one area adjoining the through-hole such that the material of the bone plate is not deformed in the ductile area because of the expansion resulting from the head of the bone screw being screwed in. As a consequence, the area surrounding the through-hole is not overstretched in any position of the bone screw (6) along the entire length of the threads because of the interaction between the external thread of the top of the bone screw and the internal thread of the plate while the torsion-proof condition is maintained.