Polyaxial Bone Anchoring Device Dynamic Locking Ring

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Solution Overview

Problem

In spinal surgery, polyaxial bone anchoring devices require frequent adjustments of bone anchoring elements and rods relative to their receiving parts, which can be cumbersome and may cause damage to surrounding tissues due to the need for large forces during repeated adjustments.

Innovation Solution

A polyaxial bone anchoring device with an outer locking ring that allows for improved handling, combined with an instrument that enables the locking ring to be moved relative to the receiving part from a non-locking to a locking position and vice versa, allowing for independent adjustment of the head and rod positions without the need for a temporary locking element, facilitating controlled adjustments and re-adjustments during surgery.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If repeated adjustments of bone anchoring elements and rods are performed during surgery, then the angular position can be optimized, but large forces are required that may damage surrounding tissues

Engineering Contradiction:

Improveangular position adjustment precisionVSAvoidtissue damage from large forces

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The head receiving portion is designed with dynamic characteristics, allowing it to be compressed and expanded. During adjustment, the portion is compressed to release the head, enabling repositioning without requiring large external forces that could damage surrounding tissues. The dynamic compliance of the receiving part facilitates smooth adjustments while protecting adjacent anatomical structures from excessive mechanical stress.

Inventive Principle:

Principle #15Dynamics

2Reliability

If a locking element is used to secure the rod, then the rod is firmly fixed, but the device complexity increases and temporary locking becomes cumbersome

Engineering Contradiction:

Improverod fixation stabilityVSAvoidlocking mechanism complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The locking function is merged into the head receiving portion itself, which can be compressed to release the head and expanded to lock it securely. This integration eliminates the need for separate temporary locking elements, reducing overall device complexity while maintaining reliable rod fixation. The receiving part performs both the clamping function and the locking function through its compressible structure.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The locking element is extracted from the system by using the compressible head receiving portion to provide the locking function inherently. The receiving part's ability to be compressed and expanded replaces the need for additional locking components, simplifying the device while ensuring stable rod fixation.

Inventive Principle:

Principle #2Taking out (Extraction)

3Stability of the object's composition

If the head is locked in the receiving part, then the angular position is fixed, but repeated adjustments become difficult and may require damaging forces

Engineering Contradiction:

Improveangular position stabilityVSAvoidrepeated adjustment ease

Core Design Contradiction:

Stability of the object's compositionVSEase of operation

Solution Approach 1:

The head receiving portion is designed as a dynamic, compressible structure that transitions between locked and unlocked states. When compressed, it releases the head to allow angular repositioning; when expanded, it secures the head firmly. This dynamic mechanism enables repeated adjustments without requiring forces that could damage surrounding tissues, maintaining both stability and operational ease.

Inventive Principle:

Principle #15Dynamics

4Ease of operation

If the receiving part is made flexible for clamping the head, then the head can be inserted easily, but the structural strength may be compromised

Engineering Contradiction:

Improvehead insertion easeVSAvoidreceiving part structural strength

Core Design Contradiction:

Ease of operationVSStrength

Solution Approach 1:

The head receiving portion exhibits dynamic mechanical properties, being compliant during insertion to facilitate easy head placement, yet capable of withstanding operational loads when in the locked position. The portion compresses during insertion to accommodate the head, then maintains sufficient structural strength to secure the rod and withstand surgical forces, balancing ease of operation with structural integrity.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS20250000552A1Polyaxial bone anchoring device and instrument for use with the same

Publication Date: 2025.01.02 BIEDERMANN TECH GMBH & CO KG

AI summary

A bone anchoring device includes a receiving part with a rod receiving portion having a first end, a second end, a recess for the rod, an outer surface, and a first engagement structure on the outer surface that extends farther radially outwardly than other parts of the rod receiving portion, and a flexible head receiving portion for inserting and clamping the head. The bone anchoring device also includes a locking ring configured to be arranged around the head receiving portion for locking the head, the locking ring having an outer surface and a second engagement structure on the outer surface that extends farther radially outwardly than the outer surface of the rod receiving portion. The engagement structures are configured to be engaged by an instrument to move the locking ring from a locking position to a position where the inserted head is pivotable.