Bone Fixation Plate With Resilient Interference Locking
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Solution Overview
Problem
Current bone fixation systems face issues with screw loosening due to dynamic loading, limited ability to compress bone fragments, difficulty in adapting to bone shape, high material thickness causing tissue irritation, and non-reusable screw holes, especially with variable angle locking mechanisms that function independently of compression mechanisms.
Innovation Solution
A bone fixation system with a plate featuring resiliently deformable interference portions along its inner walls, allowing for variable angle locking of bone screws without the need for threading, enabling secure fixation and reusability while reducing plate thickness and improving adaptation to bone shape.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If locking screws are used to secure the screw to the plate, then the angular relationship between screw and plate is fixed and resistance to shear and torsional forces is improved, but the ability to compress bone fragments is limited
Solution Approach 1:
The screw head is divided into two functional zones: an upper non-threaded smooth region that engages with the plate's locking mechanism for shear and torsional resistance, and a lower threaded region that provides bone compression capability. This segmentation allows the single screw to perform both locking and compression functions simultaneously.
2Adaptability or versatility
If variable angle fixation is allowed, then the adaptability to different bone shapes and orientations is improved, but the plate thickness increases
Solution Approach 1:
The plate incorporates a dynamic locking mechanism where the inner walls can deform elastically to accommodate screws at various angles. The resilient interference portions allow the plate to adapt to different insertion angles without requiring a thick multi-hole design, maintaining a lower profile while providing variable angle fixation capability.
Solution Approach 2:
The plate's inner wall geometry is designed with variable thickness and resilient interference portions that can deform to accommodate different screw angles. This parameter variation in the wall structure enables angle adjustment without increasing overall plate thickness, as the material properties and geometric parameters are optimized locally.
3Device complexity
If threads are provided on inner walls for locking screws, then the locking mechanism is simplified, but the screw holes cannot be reused after single use
Solution Approach 1:
The plate's inner walls are designed as flexible resilient structures rather than rigid threaded holes. The elastic material allows the walls to deform during screw insertion and then return to their original shape, enabling repeated use of the same hole without permanent damage. This flexible wall design replaces the traditional threaded mechanism while providing both simplicity and reusability.
4Strength
If thicker bone plates are used, then stability and force absorption are improved, but tissue irritation increases leading to high removal rates
Solution Approach 1:
The plate utilizes composite construction with varying material properties in different regions. Thinner sections are used where full strength is not required to reduce tissue irritation, while strategically placed thicker reinforcement zones provide necessary stability and force absorption. This composite approach optimizes the balance between mechanical strength and biocompatibility.
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 system provides stable fixation, allows for multiple angle orientations of screws, reduces material thickness for less tissue irritation, and enables repeated use of screw holes without damage, enhancing clinical outcomes and patient comfort.
Implementation Method 1
resiliently deformable interference portions located along an in-use upper portion of the one or more inner walls... to achieve deformation of the interference portions and interference between the head of the bone screw and the inner walls to lock the head of the bone screw within the passage
Data Source
AI summary
A bone fixation system for bone repair, the system comprising a bone fixation plate with upper and lower surfaces and at least one opening formed on the upper and lower surfaces to form a passage extending from the upper surface to the lower surface to receive a bone screw. The passage is defined by one or more non-threaded inner walls extending from the upper surface to the lower surface. At interference portions, the passage has a width between the walls smaller than the diameter of the head of the bone screw to achieve interference between the head of the bone screw and the inner walls at interference portions to lock the bone screw within the passage upon its insertion into the passage at a variable angle of rotation relative to a longitudinal axis of the passage.