Expandable Bone Anchor for Cement Delivery in Spine Fixation

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Solution Overview

Problem

There is a need for methods and instruments that can safely deliver bone cement via minimally invasive surgery (MIS) to address the anchoring issues of pedicle screws in poor quality bone, particularly in conjunction with pedicle screw and rod fixation systems, where existing solutions do not effectively prevent screw loosening.

Innovation Solution

A medical device with a handle, inner member, and expandable bone engaging section that radially expands to secure the device within the bone, allowing for the delivery of pressurized bone cement through a lumen, and methods for anchoring the device within the bone to prevent dislodgement during cement delivery.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an expandable bone engaging section is used to secure the device within the bone, then the device stability and anchoring strength are improved, but the device complexity increases

Engineering Contradiction:
Improvedevice anchoring stabilityVSAvoiddevice structural complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The bone engaging section is designed to transition from a compressed low-profile state during insertion to an expanded state upon deployment. The expandable structure dynamically changes its configuration to engage with the bone wall, providing enhanced anchoring stability while maintaining a simpler insertion profile. This dynamic transformation resolves the contradiction by allowing the device to achieve high reliability only when needed, after successful placement.

Inventive Principle:
Principle #15Dynamics

2Object-affected harmful factors

If a minimally invasive approach is used to deliver bone cement, then the surgical trauma and recovery time are reduced, but the difficulty of safely accessing the pedicle and controlling cement delivery increases

Engineering Contradiction:
Improvesurgical traumaVSAvoiddifficulty of safe pedicle access
Core Design Contradiction:
Object-affected harmful factorsVSDifficulty of detecting and measuring

Solution Approach 1:

The access device serves as an intermediary instrument that facilitates safe cement delivery through minimally invasive percutaneous access. The device includes a stylet for precise pedicle navigation, an expandable bone engaging section for secure positioning, and a controlled delivery mechanism for bone cement. This intermediary device resolves the contradiction by enabling minimally invasive access (reducing trauma) while providing the control and visibility needed for safe pedicle access and precise cement delivery.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Reliability

If bone cement is delivered under pressure to ensure adequate filling, then the cement distribution and anchoring effectiveness are improved, but the risk of cement leakage and gas bubble formation increases

Engineering Contradiction:
Improvecement anchoring effectivenessVSAvoidcement leakage and gas bubbles
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The access device incorporates a controlled delivery mechanism that provides feedback during bone cement injection. The system allows monitoring of injection pressure and flow rate, enabling the operator to adjust delivery parameters in real-time. This feedback control ensures adequate cement filling for effective anchoring while preventing excessive pressure that could cause leakage or gas bubble formation, thus resolving the contradiction between filling effectiveness and harmful side effects.

Inventive Principle:
Principle #23Feedback

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

Enables secure and controlled delivery of bone cement to the vertebral body and pedicle, enhancing the anchoring of pedicle screws and facilitating stable fixation during spine stabilization procedures, while allowing for easy removal of the device post-procedure.

Implementation Method 1

an expandable bone engaging section located about a distal portion of the inner member and configured to expand radially away from the inner member

Methodology Applied
Scientific EffectRadial expansion: Elasticity

Implementation Method 2

allowing for the delivery of pressurized bone cement through a lumen

Methodology Applied
Scientific EffectPressurized delivery: Pressure Increase

Data Source

PatentEP2931144B1Devices and systems for affixing an access device to a vertebral body for the insertion of bone cement
Publication Date: 2020.10.07 DFINE INC
  • EP2931144B1 patent drawingFigure 1
  • EP2931144B1 patent drawingFigure 2A~2C
  • EP2931144B1 patent drawingFigure 2D~2E

AI summary

Devices and method discussed for device for delivering a pressurized substance to an opening in bone within a vertebral column, useful to provide access to structures in the vertebral so that a substance, such as bone cement can be delivered through a lumen or portal or for providing access to the opening in bone by a separate instrument.