Orthopedic Locking Screw Deformable Casing Radial Play
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Solution Overview
Problem
In orthopedic procedures, orthopedic locking screws often experience radial play due to gaps between the screw and the implant, leading to shifting and movement that can hinder healing, necessitating additional components to minimize this play, which increases the number of parts and healing time.
Innovation Solution
An orthopedic locking screw design featuring a shaft with a casing that is rotationally fixed around it, having a deformable thread and a forward external thread with different pitches, which engages with the implant's bore to reduce movement by creating a press-fit pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional locking screw with a simple cylindrical shape is used, then the device complexity is low and ease of manufacture is high, but radial play occurs between the screw and implant bore leading to shifting and movement
Solution Approach 1:
The patent applies a deformable casing surrounding the shaft of the locking screw. This casing is configured to deformably engage with the implant bore, creating a press-fit connection that eliminates radial play. The flexible nature of the casing allows it to conform to the bore dimensions while maintaining a stable, movement-free connection between the screw and implant.
2Reliability
If additional screws or components are added to eliminate radial play, then the stability of connection improves, but the number of parts increases and healing time is extended
Solution Approach 1:
The patent combines the functions of multiple separate components into a single integrated locking screw structure. The deformable casing is integrated with the shaft to form one unified component that provides both structural support and radial play elimination. This merging eliminates the need for additional separate screws or components, reducing the total number of parts while maintaining connection stability.
3Reliability
If a deformable casing with different pitch threads is used, then shifting and movement between components is reduced, but the manufacturing precision requirements increase
Solution Approach 1:
The patent utilizes changes in thread pitch parameters along the length of the casing to achieve different functional zones. The deformable casing incorporates threads with varying pitches that allow for controlled deformation and engagement. This parameter variation enables the casing to transition from a rigid engagement zone to a deformable press-fit zone, reducing shifting while managing manufacturing precision requirements through functional gradation.
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
This design reduces shifting and movement between orthopedic components, potentially decreasing the number of additional components needed and enhancing healing by providing a stable connection.
Implementation Method 1
The deformable thread is configured to engage a substantially complementary internal thread feature of the bore... creating a press-fit pressure
Implementation Method 2
A deformable thread is disposed along an outer surface of the casing... the deformable thread of the casing against the orthopedic implant
Data Source
AI summary
An orthopedic locking screw is configured to be retained inside a bore of an orthopedic implant. The orthopedic locking screw includes a shaft extending axially, a casing secured around an outer surface of the shaft, a deformable thread disposed along an outer surface of the casing, and a forward external thread disposed on the shaft. The forward external thread has a pitch that is different from a pitch of the deformable thread of the casing. Further, an orthopedic locking screw is provided, wherein projections and the casing are alternately arranged on the outer surface of the shaft. Methods of securing an orthopedic screw in a bore of an orthopedic implant are also provided.