Polyaxial Bone Anchor Locking Ring for Easier Rod Adjustment

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Solution Overview

Problem

Existing polyaxial bone anchoring devices require repeated adjustments of the bone anchoring element and rod relative to the receiving part during spinal surgery, leading to cumbersome handling and increased pressure on vertebrae.

Innovation Solution

A polyaxial bone anchoring device with a locking ring that can be rotated to lock and unlock independently of rod fixation, allowing for reduced profile and easier adjustments, and featuring extended tabs for minimally invasive surgery guidance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If repeated adjustments of bone anchoring element and rod relative to receiving part are performed during spinal surgery, then the ability to correct spinal alignment is improved, but handling becomes cumbersome and pressure on vertebrae increases

Engineering Contradiction:

Improveability to correct spinal alignmentVSAvoidhandling convenience

Core Design Contradiction:

Adaptability or versatilityVSEase of operation

Solution Approach 1:

The device is divided into functionally independent components: the bone anchoring element with head, the receiving part with rod receiving portion, and the locking mechanism with locking ring. This segmentation allows the head to be locked independently from the rod, enabling repeated adjustments of the rod relative to the receiving part without requiring adjustment of the bone anchoring element itself, thereby improving handling convenience while maintaining alignment correction capability

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The locking ring is designed to be rotatable around the head receiving portion, transitioning between a locked position (where the head is secured) and an unlocked position (where the head can be adjusted). This dynamic locking mechanism allows surgeons to quickly lock or unlock the head without complex operations, facilitating repeated adjustments during surgery while reducing handling burden

Inventive Principle:

Principle #15Dynamics

2Adaptability or versatility

If repeated adjustments are performed using conventional devices, then spinal alignment correction is achieved, but pressure on vertebrae increases

Engineering Contradiction:

Improvespinal alignment correctionVSAvoidpressure on vertebrae

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

By separating the locking function into an independent locking ring that operates around the head receiving portion, the device allows rod adjustments without manipulating the bone anchoring element itself. This eliminates the need to repeatedly insert and remove instruments from the vertebrae, thereby reducing pressure and trauma to the vertebral bone while maintaining the ability to correct spinal alignment

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The locking ring acts as an intermediary mechanism between the head and the rod. It provides a external locking interface that allows the rod to be secured or adjusted without directly manipulating the bone anchoring element embedded in the vertebrae, thus protecting the vertebrae from repeated instrument insertion and reduction of mechanical pressure

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If locking mechanism requires moving locking ring downward for locking, then head is secured, but profile size increases and force requirement increases

Engineering Contradiction:

Improvehead locking securityVSAvoidprofile size

Core Design Contradiction:

ReliabilityVSLength of stationary object

Solution Approach 1:

Instead of moving the locking ring downward along the axis to achieve locking, the design inverts the approach: the locking ring rotates around the head receiving portion in a circumferential direction. The locking engagement is achieved through radial movement of locking protrusions into engagement recesses during rotation, rather than axial movement. This inversion reduces the axial profile length while maintaining secure locking

Inventive Principle:

Principle #13The other way round (Inversion)

4Reliability

If locking ring is rotated in conventional devices, then locking is achieved, but significant force is required

Engineering Contradiction:

Improvelocking securityVSAvoidforce required for rotation

Core Design Contradiction:

ReliabilityVSForce

Solution Approach 1:

The locking ring features a spherical outer surface portion that engages with a corresponding spherical recess in the receiving part. This spherical interface allows for smooth rotational movement with reduced friction compared to flat or tapered surfaces. The curved contact surfaces distribute the locking forces more evenly, reducing the peak force required to rotate and lock the mechanism while maintaining secure locking

Inventive Principle:

Principle #14Spheroidality (Curvature)

Data Source

PatentUS20260033870A1Polyaxial bone anchoring device and system including an instrument and a polyaxial bone anchoring device

Publication Date: 2026.02.05 BIEDERMANN TECH GMBH & CO KG

AI summary

A bone anchoring device includes a receiving part having a central axis, two legs defining a recess for receiving a rod, and a head receiving portion that is at least partially expandable and having an opening for inserting and pivotably holding a head of a bone anchoring element therein, and a locking ring mountable around the head receiving portion in an axial direction while a rotational orientation of the locking ring relative to the receiving part remains constant. When the locking ring is around the head receiving portion, the locking ring is rotatable around the central axis from a first rotational orientation to a second rotational orientation where a compressive force exerted by the locking ring on the head receiving portion is greater than at the first rotational orientation.