Bone Fixation Shaft Lockable Coupling Steep Pitch Blade Alignment
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Solution Overview
Problem
Existing bone fixation devices face challenges in aligning and stabilizing helical blades with steep pitches during surgical implantation, as they require excessive rotation for alignment, leading to difficulties in achieving a parallel position with the femur, especially when using conventional sleeve tabs.
Innovation Solution
A bone fixation system with a lockable coupling between the shaft and anchoring element allows for rotational adjustment while maintaining axial stability, using axial locking-in-position means such as snap-in blades or pins, and frictional or positive locking mechanisms to secure the components, enabling the use of helical blades with steep pitches alongside conventional screws.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If helical blades with steep pitch are used to improve anchoring stability, then anchoring strength is improved, but alignment difficulty increases due to excessive rotation during insertion
Solution Approach 1:
The device is divided into two independent but connectable parts: a shaft that can be inserted and rotated independently, and an anchoring element (helical blade) that is initially separable. This allows the shaft to be aligned and positioned first, then the anchoring element to be attached separately, solving the alignment difficulty while maintaining anchoring strength
Solution Approach 2:
The coupling between shaft and anchoring element transitions from a dynamic (loose, rotatable) state during insertion to a static (locked, fixed) state after positioning. The lockable coupling mechanism enables this transition, allowing rotation during alignment then preventing rotation for stable anchoring
2Device complexity
If the shaft and anchoring element are firmly connected to simplify the structure, then device complexity is reduced, but rotational adjustability is lost
Solution Approach 1:
The coupling mechanism provides dynamic adaptability by allowing the connection between shaft and anchoring element to change from loose to locked state. This enables rotational adjustability during insertion while providing firm connection for final positioning, achieving both adaptability and structural simplicity
Solution Approach 2:
The frictional connection parameter changes from low friction (allowing rotation) during insertion to high friction (preventing rotation) after positioning. This parameter change enables the system to provide both rotational adjustability and firm connection without increasing structural complexity
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 solution allows for the secure and stable implantation of helical blades with steep pitches, reducing the risk of implant dislodgment and enhancing clinical outcomes by minimizing bone cutting and preventing femur head rotation, while maintaining compatibility with conventional bone screws.
Implementation Method 1
The interacting means may be equipped frictionally or positively. In the case of a frictional configuration, the following, for example, are suitable: conical elements, which may be wedged in a complementary conical borehole.
Data Source
AI summary
The invention relates to a bone fixation means (1) comprising: A) a longtitudinal shaft (2) with longtitudinal axis (3), and; B) an anchoring element (4), which can be fixed inside a bone and which has the same longitudinal axis (3) and is characterized in that; C) interacting means (5; 6) are provided on the shaft (2) and on the anchoring element (4), which either permit or prevent a rotation of the anchoring element (4) about the longitudinal axis (3) relative to the shaft (2).