Spinal Rod Bend Planning for Precise 6-DOF Implant Shaping

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Solution Overview

Problem

Current methods for bending spinal rods in orthopedic surgery are laborious, require significant skill, and often result in mechanical failures due to arbitrary bending and metal fatigue, as they do not account for the six degrees of freedom necessary for precise anatomical alignment.

Innovation Solution

A system that determines the relative spatial location of attachment points on the spine, converts this information into a digital format, and uses a computer to calculate and output the necessary shape parameters for the spinal rod, allowing for precise bending with a lever-based device that measures bend position, angle, and rotation, enabling accurate attachment to bony structures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If manual bending methods like French Bender are used, then the rod can be bent with available tools, but the bending process becomes arbitrary and time-consuming, increasing the risk of mechanical failure

Engineering Contradiction:

Improverod bending capabilityVSAvoidrod mechanical integrity

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The system performs preliminary digital planning and calculation of bend parameters before actual rod bending. The computer calculates precise bend location, angle, and rotation based on attachment point coordinates, allowing the surgeon to execute bends accurately without arbitrary manual adjustments that cause metal fatigue

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system incorporates feedback through digital measurement of attachment point locations and computer-calculated bend parameters. The measured coordinates feed into the calculation algorithm, which outputs specific bend instructions that can be verified and adjusted before implementation, creating a closed-loop system that reduces errors

Inventive Principle:

Principle #23Feedback

2Device complexity

If manual bending with French Bender is used, then the tool is simple and available, but the process requires significant skill and time, increasing operating room duration

Engineering Contradiction:

Improvebending tool simplicityVSAvoidbending efficiency

Core Design Contradiction:

Device complexityVSProductivity

Solution Approach 1:

The system replaces manual mechanical judgment and skill-based bending with an automated computer calculation system. The computer automatically calculates bend parameters based on input coordinates, eliminating the need for surgeon skill in estimating bend geometry and significantly reducing the time required

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The computer acts as an intermediary between the measured attachment point coordinates and the final bend execution. It translates raw coordinate data into processed bend instructions (location, angle, rotation), serving as a mediator that bridges measurement and implementation while improving accuracy and speed

Inventive Principle:

Principle #24Intermediary (Mediator)

3Adaptability or versatility

If arbitrary bending is performed, then the rod can be shaped to fit attachment points, but mistakes require rebending that imposes metal fatigue and stress risers

Engineering Contradiction:

Improverod shape adaptabilityVSAvoidrod resistance to mechanical failure

Core Design Contradiction:

Adaptability or versatilityVSStrength

Solution Approach 1:

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

Inventive Principle:

Principle #23Feedback

4Measurement precision

If six degrees of freedom calculation is implemented, then precise anatomical alignment is achieved, but the system complexity increases with digital measurement and computer calculation

Engineering Contradiction:

Improveattachment point location accuracyVSAvoidsystem digital infrastructure

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The system uses universal coordinate geometry and mathematical algorithms that can handle any spatial configuration of attachment points. The computer calculation method is universally applicable to different spinal regions and patient anatomies, providing precise six-degree-of-freedom alignment without requiring complex specialized equipment for each case

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS20240189886A1Systems, devices, and methods for designing and forming a surgical implant

Publication Date: 2024.06.13 NUVASIVE INC

AI summary

A method is provided for determining the shape of a surgical linking device that is to be attached to a bony body structure such as the spinal column based on digitized locations of a plurality of attachment elements engaged to the bony structure. The method is implemented by a computer system through a GUI to generate an initial bend curve to mate with the plurality of attachment elements. The initial bend curve may be simplified based on user input to the GUI to reduce the number of bends necessary to produce a well-fitting linking device and may be altered to help obtain the goals of surgery.