Implant Fastener Interference Fit Backout Prevention
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Solution Overview
Problem
Existing implant-fastener systems face challenges with backout prevention due to subsidence of the bone or unthreading of the fastener, and existing mechanisms like snap rings and movable projections are either prone to detachment or require additional surgical steps, making it difficult to ensure proper positioning.
Innovation Solution
An implant with a passage featuring interference sections of different hardnesses, where the fastener's interference section modifies the implant's passage section during insertion, creating a self-locking interference fit to prevent backout, eliminating the need for additional surgical steps and ensuring secure attachment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a snap ring mechanism is used to prevent backout, then backout prevention is improved, but the device complexity increases and the snap ring may become detached or fail to rebound properly
Solution Approach 1:
The patent removes the separate snap ring component entirely and integrates the backout prevention function directly into the fastener body. The fastener's distal end is shaped to engage with a corresponding feature in the implant, creating an integrated locking mechanism that eliminates the need for a separate snap ring while maintaining backout prevention reliability.
Solution Approach 2:
The patent combines the fastener and locking mechanism into a single integrated component. The distal end of the fastener incorporates engagement features that directly interact with the implant, merging the function of the fastener and the previously separate snap ring into one unified structure, thereby reducing device complexity while maintaining reliability.
2Reliability
If a movable projection mechanism is used to prevent backout, then backout prevention is improved, but additional surgical steps are required and the surgeon may have difficulty determining proper positioning
Solution Approach 1:
The patent incorporates the locking engagement features directly into the fastener structure before insertion. The distal end of the fastener is pre-configured with engagement features that automatically interact with the implant upon insertion, eliminating the need for additional surgical steps to position a separate projection while ensuring proper locking engagement.
Solution Approach 2:
The fastener's distal end is designed to automatically engage with the implant's corresponding feature during the insertion process itself. The engagement occurs self-actuatingly as the fastener is inserted, without requiring additional surgical manipulation or positioning steps, thereby simplifying the surgical procedure while maintaining reliable backout prevention.
3Ease of manufacture
If the fastener and implant have the same hardness, then manufacturing is easier, but the fastener may backout due to lack of interference fit
Solution Approach 1:
The patent applies different material properties to different parts of the fastener-implant system. The fastener is made of a harder material than the implant, creating a localized hardness difference at the engagement interface. This allows the fastener to create an interference fit and locking engagement with the implant while the rest of the components can be manufactured with appropriate materials for their specific functions.
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 self-locking interference fit effectively prevents fastener backout, enhancing the stability and reliability of the implant-fastener system by ensuring a secure attachment without requiring additional surgical steps or complex mechanisms.
Implementation Method 1
During insertion of the fastener through the passage and into the bone, the second interference section of the fastener contacts against and modifies or is modified by the first interference section of the passage. This modification creates an interference fit between the implant and the fastener that prevents backout.
Data Source
AI summary
An implant with an interference fit fastener for attaching the implant to a bone. The interference fit prevents backout of the fastener after the attachment. The implant may include a passage with a first end and second end. The passage may include a first interference section between the first and second ends. A fastener with an elongated shape may be sized to extend through the passage to attach the implant to the bone. The fastener may include a second interference section. During insertion of the fastener through the passage and into the bone, the second interference section of the fastener may contact against and modify or be modified by the first interference section of the passage. This modification may create the interference fit between the implant and the fastener that prevents backout. The interference sections may remain in contact or may move apart once the fastener is fully attached to the bone.