Spinal Anchor Assembly With Flexible Member for Stress Reduction

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Solution Overview

Problem

Existing spinal implant anchor assemblies often result in suboptimal outcomes due to stress on anchors from patient activity, as they do not adequately accommodate dynamic movement and alignment with the complex spinal anatomy.

Innovation Solution

The development of a bone anchor assembly with a flexible member positioned between the anchor member and receiver, allowing multi-axial motion and limited movement after the connecting element is secured, which includes a tether and ferrule assembly to secure the receiver to the anchor member, enabling dynamic connection and stress distribution.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If a rigid anchor assembly is used to secure the implant to the vertebral column, then the implant is firmly fixed in position, but high stress is placed on the anchor during patient activity and movement

Engineering Contradiction:

Improvefirm fixation of implantVSAvoidstress on anchor

Core Design Contradiction:

Stability of the object's compositionVSStress or pressure

Solution Approach 1:

The anchor assembly transitions from a static rigid connection to a dynamic system that allows controlled movement. The flexible member enables the receiver to move relative to the anchor member, accommodating physiological movements and reducing stress concentration during patient activity while maintaining overall stability.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes the mechanical parameters of the connection between anchor and receiver by introducing flexibility. This allows the connection to adapt its stiffness and movement characteristics based on operational conditions, reducing peak stresses while maintaining adequate fixation.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If a fixed rigid connection is used between the anchor and receiver, then the implant is securely locked in position, but it cannot accommodate multi-axial motion and alignment with complex spinal anatomy

Engineering Contradiction:

Improvesecure locking of implantVSAvoidalignment with spinal anatomy

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The connection between anchor and receiver is made dynamic through the flexible member, allowing multi-axial motion and angular adjustment. This enables the implant to be aligned with complex spinal anatomy while maintaining secure fixation through the locking mechanism that engages after positioning.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The flexible member allows preliminary positioning and alignment adjustments to be made before final locking. The receiver can be oriented in multiple directions relative to the anchor during implantation, and then locked into the desired position, combining adaptability with secure fixation.

Inventive Principle:

Principle #10Preliminary action

3Adaptability or versatility

If multiple components are used in the anchor assembly to allow angular movement and locking, then alignment flexibility is improved, but the device complexity increases and may result in less than optimal outcomes

Engineering Contradiction:

Improveangular movement capabilityVSAvoidnumber of components

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The flexible member integrates multiple functions into a single component: it provides flexibility for angular movement, acts as a shock absorber to reduce stress, and serves as part of the locking mechanism interface. This consolidation reduces the overall number of separate components while maintaining adaptability.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The flexible member serves multiple purposes simultaneously: it enables multi-axial motion, absorbs stresses during patient activity, and facilitates the locking mechanism. This multi-functionality reduces device complexity by eliminating the need for separate components for each function.

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

This solution provides a stable and flexible interface that reduces stress on the anchor assembly, allowing for optimal alignment and movement compatibility with the spinal anatomy, thereby improving the effectiveness and durability of spinal stabilization systems.

Implementation Method 1

a flexible member positioned at an interface between the receiver and the anchor member

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentUS8292934B2Dynamic anchor assembly for connecting elements in spinal surgical procedures

Publication Date: 2012.10.23 WARSAW ORTHOPEDIC INC

AI summary

Devices and methods include a multi-axial anchor assembly engageable to a vertebra and a connecting element positionable through a receiver of the anchor assembly. The anchor assembly includes a flexible member between the receiver and an anchor member of the anchor assembly, thereby providing a flexible joint in the anchor assembly for allowing limited movement after primary multi-axial capability between the receiver and the anchor member has been arrested.