Spinal Rod Coupling Assembly with Tulip Design

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Solution Overview

Problem

Conventional pedicle screw systems are bulky, difficult to install, and lack a predetermined locking position, leading to overtorquing and increased tissue damage during minimally invasive surgery, with polyaxial fixation devices providing inadequate support and stability before full locking of the rod.

Innovation Solution

A low-profile coupling assembly with a tulip-shaped design, featuring a cylindrical insert and annular outer member, allows for provisional and full locking of the anchor and rod, enabling independent locking of components and minimizing the assembly's height, using flexible arms and a compression cap to secure the rod and anchor in place.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional pedicle screw systems are used, then the assembly provides secure bone fixation, but the assembly becomes bulky and increases tissue damage during surgery

Engineering Contradiction:

Improvebone fixation securityVSAvoidtissue damage

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The coupling assembly is divided into separate components: an outer member, an insert member, and a locking member. These segments can be independently manipulated and assembled, allowing for minimally invasive insertion while maintaining structural integrity for secure bone fixation.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The insert member is received within the outer member, and the rod is received within the insert member, creating a nested configuration. This nesting reduces the overall profile and bulk of the assembly, minimizing tissue damage while maintaining fixation security.

Inventive Principle:

Principle #7Nested doll (Nesting)

2Reliability

If set-screw type locking mechanisms are used, then the assembly can lock components, but the assembly height increases and patient discomfort occurs

Engineering Contradiction:

Improvelocking capabilityVSAvoidassembly height

Core Design Contradiction:

ReliabilityVSLength of stationary object

Solution Approach 1:

Instead of using a set-screw that protrudes outward to lock components, the locking member is received within the outer member and applies locking force from the inside. This inverted approach maintains locking capability while reducing assembly height and preventing patient discomfort.

Inventive Principle:

Principle #13The other way round (Inversion)

3Adaptability or versatility

If polyaxial fixation devices are used, then the assembly allows angle adjustment, but the assembly lacks stability and support before full locking

Engineering Contradiction:

Improveangle adjustment capabilityVSAvoidassembly stability

Core Design Contradiction:

Adaptability or versatilityVSStability of the object's composition

Solution Approach 1:

The insert member is preliminarily secured within the outer member before the rod is fully locked. This preliminary action provides initial stability and support, preventing assembly splaying while still allowing for angle adjustment. The insert member acts as a temporary structural support during the assembly process.

Inventive Principle:

Principle #10Preliminary action

4Reliability

If conventional assembly procedures are used, then components can be connected, but the installation becomes difficult and time-consuming

Engineering Contradiction:

Improvecomponent connectionVSAvoidsurgical efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The insert member is pre-loaded with the rod before insertion into the outer member. This preliminary action simplifies the assembly process, allowing for quick installation while ensuring reliable component connection. The pre-loaded configuration eliminates the need for complex in-surgery assembly procedures.

Inventive Principle:

Principle #10Preliminary action

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 enhances the efficiency of spinal fixation surgeries by reducing tissue trauma, allowing for precise angle adjustment and secure locking without obstructing the surgical site, facilitating minimally invasive procedures and reducing post-operative complications like assembly splaying.

Implementation Method 1

flexible arms and a compression cap to secure the rod and anchor in place

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

flexible arms and a compression cap to secure the rod and anchor in place

Methodology Applied

Scientific EffectCompression: Compression

Data Source

PatentUS9186191B2Rod coupling assembly and methods for bone fixation

Publication Date: 2015.11.17 XTANT MEDICAL HOLDINGS INC

AI summary

A coupling device for securing an elongate member to the spine is provided. The coupling device comprises a compressible inner member that secures an anchor member therein when the inner member is axially shifted within an outer member. Structures are provided to prevent disassembly of the anchor and coupling device prior to locking of the elongate member.