Orthopedic Locking Screw Plastically Deformable Casing
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Solution Overview
Problem
In orthopedic procedures, there is a radial gap between orthopedic locking screws and the implants they secure, leading to shifting and movement that can hinder healing, often requiring additional screws to minimize this issue.
Innovation Solution
An orthopedic locking screw with a shaft and a casing made of plastically deformable material, where the casing forms a press-fit with the implant's bore to reduce movement and provide a stable connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a standard locking screw is used with a bore, then the screw can be easily inserted, but a radial gap exists between the screw and bore causing shifting and movement
Solution Approach 1:
The casing material is changed to a plastically deformable material that can change its dimensional parameters (outer diameter) to match the bore inner diameter, eliminating the radial gap and providing a stable connection without additional screws
Solution Approach 2:
The casing is designed to dynamically adapt its outer diameter during insertion - initially larger than the bore to create an interference fit, then deformable to conform to the bore's inner diameter, providing a press-fit connection that eliminates movement
2Reliability
If additional screws are used to eliminate radial gap, then shifting and movement are minimized, but the number of parts and insertion complexity increases
Solution Approach 1:
The locking and gap-elimination functions are merged into a single integrated component - the deformable casing that simultaneously provides structural support and eliminates the radial gap through its plastic deformation capability, replacing the need for multiple separate screws
3Reliability
If the casing outer diameter is larger than the bore inner diameter, then a press-fit connection is formed, but insertion force is required
Solution Approach 1:
The casing is pre-formed with an outer diameter that is larger than the bore inner diameter to create an interference fit, but the plastically deformable material allows it to yield and conform to the bore during insertion, reducing the required insertion force while maintaining connection stability
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 solution effectively minimizes radial shifting and movement between the screw and the implant, potentially reducing the number of additional screws needed and enhancing healing by providing a secure, stable connection.
Implementation Method 1
The casing is formed of a plastically deformable material
Implementation Method 2
The casing forms a press-fit with the bore
Data Source
Figure 1
Figure 2~2B
Figure 3
AI summary
An orthopedic locking screw is be configured to be retained inside the bore of an orthopedic implant provided as part of an orthopedic fastening system. The orthopedic locking screw includes a shaft extending axially, a drive member, and a casing secured around an outer surface of the shaft. The casing is formed of a plastically deformable material. The casing has an outer cross-sectional width that is larger than a cross-sectional width of the shaft adjacent the casing. When operably disposed in the bore, an axial and/or radial press-fit pressure is formed between the casing and the bore. A method of securing an orthopedic screw in a bore of an orthopedic implant is provided, in which the shaft is rotated to operably engage the casing to the bore to achieving a deformable press-fit of the casing against the bore.