Bone Anchoring Receiving Part Locking Ring Design
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Solution Overview
Problem
Existing bone anchoring devices lack sufficient locking force and safety features, particularly in designs that use tapered surfaces, which can lead to instability and risk of head removal during use.
Innovation Solution
A receiving part for a bone anchoring device with a locking ring that applies a clamping force perpendicular to the central axis, utilizing a combination of cylindrical and ring-shaped bulges to enhance locking, and incorporating a pre-locking mechanism that allows pivoting while preventing removal, with a compact and low-profile design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If tapered surfaces are used to clamp the head, then the device structure is simplified, but the locking force is insufficient and safety is compromised
Solution Approach 1:
The locking mechanism is divided into separate functional elements: a locking ring with radial flanges that engage with corresponding grooves in the receiving part, and a head receiving portion with a cavity. This segmentation allows each component to be optimized independently - the locking ring provides strong clamping force through its flange-groove engagement, while the receiving part maintains structural simplicity.
Solution Approach 2:
The locking ring features asymmetric radial flanges positioned at specific locations, and the receiving part has correspondingly positioned grooves. This asymmetric configuration creates a positive locking mechanism where the flanges engage with the grooves to prevent head removal, providing enhanced locking force while maintaining manufacturing simplicity through the use of basic geometric forms.
2Reliability
If a locking ring with radial flanges is used to engage grooves in the receiving part, then locking force is enhanced, but the device complexity increases
Solution Approach 1:
The locking ring combines multiple functions into a single component: it provides the clamping force through its radial flanges, maintains the head in the receiving part through groove engagement, and allows for angular positioning. This merging of functions into one element reduces overall device complexity while achieving enhanced locking force.
Solution Approach 2:
The radial flanges of the locking ring engage with grooves in the receiving part at multiple discrete locations around the circumference. This distributed engagement pattern creates multiple contact points that work together to provide uniform clamping force and prevent head removal, achieving enhanced locking force without requiring a complex multi-component mechanism.
3Force
If the head receiving portion is compressed to lock the head, then locking force is generated, but the risk of head removal during use increases
Solution Approach 1:
The locking ring with its radial flanges engaging the grooves in the receiving part creates a pre-locking mechanism that prevents head removal before any harmful action can occur. The flange-groove engagement establishes a mechanical interlock that counteracts any forces that might attempt to remove the head, thereby eliminating the risk of head removal during use.
Solution Approach 2:
The radial flanges act as intermediary elements between the locking ring and the receiving part grooves. These flanges transfer the clamping force and mechanical interlock to securely hold the head in place, preventing removal while maintaining the necessary locking force. The flanges serve as the mediating structure that eliminates head removal risk without compromising locking strength.
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 provides a higher locking force and improved safety by ensuring the head is securely locked within the receiving part, allowing for adjustable angular positioning while preventing accidental removal, and enabling easy manufacturing with simple mechanical elements.
Implementation Method 1
The locking ring has an interior surface portion that engages the exterior surface portion in a contact region to clamp the head
Implementation Method 2
The head receiving portion has an exterior surface portion and the locking ring has an interior surface portion that engages the exterior surface portion in a contact region to clamp the head
Data Source
AI summary
A receiving part for coupling a rod to a bone anchoring element includes a receiving part body including a head receiving portion having an open end and a first exterior surface portion, the head receiving portion being flexible to allow introduction and clamping of a head of a bone anchoring element, and a locking ring having a first interior surface portion configured to engage the first exterior surface portion of the head receiving portion in a first contact region to lock an angular position of the head, wherein the first interior surface portion is spaced apart from an end of the locking ring, and wherein one of the first exterior surface portion or the first interior surface portion includes a cylindrical surface, and the other one of the first exterior surface portion or the first interior surface portion includes another cylindrical surface or a ring-shaped bulge portion.