Spinal Rod Shape Planning for Precise Multi-Axis Bending

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Solution Overview

Problem

Current methods for bending spinal rods in orthopedic surgery are inefficient and prone to mechanical failure due to the lack of precise control over six degrees of freedom, leading to increased surgical time and risk of morbidity.

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 bending the spinal rod, allowing for precise shaping and attachment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If manual bending methods (French Bender) are used to shape spinal rods, then the rods can be bent to fit anatomical structures, but the process requires extreme physician skill, takes extremely long time, and produces arbitrary bend locations and angles

Engineering Contradiction:

Improvebending precisionVSAvoidsurgical time

Core Design Contradiction:

Manufacturing precisionVSLoss of time

Solution Approach 1:

The system performs preliminary digital planning and calculation of bend parameters (location, angle, rotation) before surgery. The computer calculates optimal bend parameters based on desired attachment points and rod configuration, allowing the surgeon to simply execute pre-determined bending parameters during surgery rather than making arbitrary decisions in real-time.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The invention replaces the manual mechanical French Bender system with a computer-based calculation and control system. The computer calculates bend parameters and guides a bending device, substituting the skill-dependent manual mechanical process with an automated system that provides precise, repeatable bending parameters.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Ease of operation

If manual bending with French Bender is used, then rods can be shaped, but the process requires extreme physician skill and produces arbitrary bend parameters

Engineering Contradiction:

Improveease of bendingVSAvoidbend parameter accuracy

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The system incorporates feedback by allowing the surgeon to input desired attachment points and rod parameters, then the computer calculates and provides specific bend parameters. This closed-loop approach ensures both ease of operation (surgeon controls the process) and measurement precision (computer provides accurate parameters).

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The computer acts as an intermediary between the surgeon's intent (desired attachment points) and the physical bending process. It translates surgical goals into precise bend parameters, mediating between the need for ease of operation and the requirement for measurement precision.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If multiple bends are made manually to achieve proper rod shape, then the rod can fit attachment points, but rebending to fix mistakes imposes metal fatigue and stress risers

Engineering Contradiction:

Improverod reliabilityVSAvoidbending accuracy

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The system performs preliminary calculation of all bend parameters before surgery, determining the exact location, angle, and rotation of each bend. This pre-planning eliminates the need for trial-and-error rebending during surgery, thereby preventing metal fatigue and stress risers that would compromise rod reliability.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The computer-based system replaces the error-prone manual bending process with precise, calculated bending parameters. This substitution eliminates the need for corrective rebending operations that cause metal fatigue, thereby improving rod reliability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Ease of manufacture

If arbitrary bend parameters are used in manual bending, then the process is simpler, but the rod may not properly fit the attachment points

Engineering Contradiction:

Improvebending simplicityVSAvoidattachment fit accuracy

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The computer-based calculation system replaces arbitrary manual bending decisions with precise, calculated bend parameters. The computer determines exact bend location, angle, and rotation based on attachment point coordinates, maintaining simplicity of execution while ensuring accurate fit.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The system uses feedback from the specified attachment points to calculate appropriate bend parameters. The computer takes the desired attachment point locations as input and determines the precise bends needed to connect them, ensuring both ease of manufacture and attachment fit accuracy.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS11453041B2Systems, devices, and methods for designing and forming a surgical implant

Publication Date: 2022.09.27 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.