Bone Anchor Receiving Part With Expandable Head Locking Structure

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Solution Overview

Problem

Existing polyaxial bone anchoring devices require multiple parts for secure locking of a bone anchor head, limiting versatility and ease of manufacturing.

Innovation Solution

A receiving part with an expandable and compressible head receiving portion, utilizing an expansion limiting member and a locking device to securely lock the bone anchor head without additional compression members, allowing for various surgical correction steps and compatibility with different bone anchors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a compression member is used to lock the bone anchor head, then the locking reliability is improved, but the device complexity and number of parts increases

Engineering Contradiction:

Improvelocking reliabilityVSAvoidnumber of parts

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the compression member function into the receiving part itself by making the receiving part expandable and compressible. The receiving part directly compresses the bone anchor head through its deformable legs, eliminating the need for a separate compression member while maintaining locking reliability.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent extracts the compression member from the system entirely, replacing it with the intrinsic expandable-compressible mechanism of the receiving part. This reduces the number of parts while achieving the same locking function.

Inventive Principle:

Principle #2Taking out (Extraction)

2Reliability

If multiple parts are used for secure locking, then the locking reliability is improved, but the ease of manufacture deteriorates

Engineering Contradiction:

Improvelocking securityVSAvoidmanufacturing ease

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The receiving part is designed as an integrated component with built-in expandable and compressible features. The single-piece construction with deformable legs eliminates the need for separate compression members, simplifying manufacturing while maintaining secure locking capability.

Inventive Principle:

Principle #5Merging (Combining)

3Reliability

If the head receiving portion is always compressed, then the locking force is improved, but the ease of operation deteriorates

Engineering Contradiction:

Improvelocking forceVSAvoidinsertion ease

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The receiving part is designed to dynamically change its state: expandable during insertion to accommodate the bone anchor head, then compressible during locking to apply locking force. This dynamic behavior enables both easy insertion and secure locking.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The receiving part is preliminarily expanded to allow easy insertion of the bone anchor head, then subsequently compressed to apply locking force. This preliminary expansion-compression sequence facilitates both ease of operation and secure locking.

Inventive Principle:

Principle #10Preliminary action

4Ease of manufacture

If the receiving part structure is simplified, then the ease of manufacture is improved, but the versatility for surgical correction steps deteriorates

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidsurgical option versatility

Core Design Contradiction:

Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The receiving part with expandable-compressible legs serves multiple functions: receiving the bone anchor head, locking it in place, and providing versatile surgical options. This multi-functional design achieves both manufacturing simplicity and surgical versatility.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 secure, versatile, and efficient locking mechanism with a minimal number of parts, enhancing manufacturing ease and enabling multiple surgical options.

Implementation Method 1

The head receiving portion is expandable to permit insertion of the head and is compressible to lock an inserted head in the seat

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

When the legs are spread apart, the head receiving portion is compressed to exert a locking force onto an inserted head

Methodology Applied

Scientific EffectMechanical Force: Mechanical Force

Data Source

PatentUS12514620B2Receiving part for coupling a rod to a bone anchor

Publication Date: 2026.01.06 BIEDERMANN TECH GMBH & CO KG

AI summary

A bone anchoring device includes a receiving part with a head receiving portion defining a seat for pivotably receiving a head of a bone anchor, and a rod receiving portion defining a recess for receiving a rod, the recess forming two legs each having an engagement surface for engaging a locking device to lock the rod in the recess, and an expansion limiting member having a surface configured to engage a portion of the receiving part spaced apart from the engagement surfaces of the legs. When the legs are urged radially outwardly, the head receiving portion is urged radially inwardly to compress and lock the head. The expansion limiting member is adjustable from a first configuration relative to the receiving part where the head receiving portion is expandable to permit the insertion of the head, to a second configuration where expansion of the head receiving portion is restricted.