Variable-Dimension Spinal Fixation Rod With Smooth Transitions

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Solution Overview

Problem

Conventional spinal stabilization systems with constant cross-sectional rods constrain surgeons by requiring uniform rigidity and are prone to fatigue at connection points, leading to potential failure and the need for surgical intervention.

Innovation Solution

A fixation rod with regions of varying cross-sectional dimensions and a tapered transition region, allowing for secure attachment to skeletal structures with a monolithic structure and reducing stress concentrations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a fixation rod with constant cross-sectional area is used, then the manufacturing process is simple and the rod can be easily produced, but the rod cannot accommodate varying spinal anatomy and requires uniform rigidity throughout, reducing adaptability

Engineering Contradiction:

Improveadaptability to spinal anatomyVSAvoidrod structure complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The fixation rod is divided into multiple segments with different cross-sectional areas along its longitudinal axis. Each segment can be independently designed to match the anatomical requirements of specific spinal regions, allowing the rod to adapt to varying spinal anatomy while maintaining structural integrity through integral construction.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different portions of the fixation rod are given different cross-sectional dimensions to provide locally optimized rigidity. The rod includes a first portion with a first cross-sectional area and a second portion with a second cross-sectional area, allowing each region to be tailored to the specific anatomical and mechanical requirements of the spinal segment it stabilizes.

Inventive Principle:

Principle #3Local quality

2Adaptability or versatility

If multiple different rods with different cross-sectional areas are coupled together, then the system can accommodate varying spinal anatomy, but the connection points become weak due to fatigue and require surgical intervention

Engineering Contradiction:

Improveadaptability to spinal anatomyVSAvoidconnection reliability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

Multiple rod segments with different cross-sectional areas are merged into a single integral fixation rod structure. This eliminates the need for separate couplers and connection points between rods, thereby removing the fatigue-related weakness at connection interfaces while maintaining the ability to accommodate varying spinal anatomy through the graduated cross-sectional design.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The fixation rod is pre-designed with pre-calculated cross-sectional variations that anticipate and accommodate the mechanical demands of different spinal regions. This preliminary structural preparation allows the rod to handle varying anatomical requirements without requiring post-installation reinforcement or surgical intervention at connection points.

Inventive Principle:

Principle #10Preliminary action

3Adaptability or versatility

If multiple rods are coupled with fasteners, then the system can provide varied rigidity, but the fastener location must be considered during implantation and may interfere with placement

Engineering Contradiction:

Improvevaried rigidityVSAvoidimplantation ease

Core Design Contradiction:

Adaptability or versatilityVSEase of operation

Solution Approach 1:

The fixation rod integrates varied rigidity characteristics directly into its continuous structure, eliminating the need for separate fasteners and coupling mechanisms. This integration removes the constraint of fastener placement locations during surgery, allowing the rod to be implanted as a single piece without interference from connection hardware.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The fixation rod serves multiple functions simultaneously: it provides varied rigidity through its graduated cross-section, acts as its own structural connector, and eliminates the need for separate fastening components. This multi-functionality simplifies the implantation process by removing the need to account for fastener locations and their potential interference with surgical access.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS20250241683A1Variable-dimension fixation rod and implantable stabilization system including a variable-dimension fixation rod

Publication Date: 2025.07.31 SPINAL RESOURCES INC

AI summary

An implantable, elongated fixation rod that, when coupled to a spinal column in a living patient, stabilizes a portion of the spinal column. The elongated fixation rod includes a plurality of different rod regions formed from surgical stainless steel that are aligned along a longitudinal axis of the elongated fixation rod. The different rod regions include different dimensions tailored to provide the different rod regions with different rigidities specific to support regions of the spinal column where the elongated fixation rod is to be installed. A smooth transition region at least 5 mm in length is integrally formed as part of a common monolithic structure with the different rod regions, and is devoid of a full, sharp step that forms a 90° angle relative to the longitudinal axis of the elongated fixation rod and separates the different rod regions along the longitudinal axis of the fixation rod.