Gradient Spinal Implant Matching Vertebral Stiffness

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Solution Overview

Problem

Conventional spinal implants have mechanical properties that mismatch those of vertebral contact surfaces, leading to subsidence and increased risk of vertebral injury due to uneven load distribution, which can nullify the benefits of fusion surgery and require costly revision surgeries.

Innovation Solution

A patient-specific spinal implant device is manufactured with customized spatial mechanical properties matching the vertebral contact surface, using computed tomography to determine the actual mechanical properties and forming individual discrete surface sections with specific mechanical stiffness members to align with the vertebral surface, reducing the risk of subsidence and vertebral injury.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If conventional solid or porous implants are used with high mechanical stiffness and strength, then the implant provides sufficient structural support, but the implant sinks into the vertebral endplates due to mismatched mechanical properties

Engineering Contradiction:

Improveimplant mechanical strengthVSAvoidimplant stability (subsidence prevention)

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The implant incorporates a gradient structure where the distal end portion has lower mechanical stiffness and strength properties compared to the proximal end portion. This local differentiation allows the distal end to better match the mechanical properties of the vertebral endplate, distributing loads more evenly and preventing subsidence, while the proximal end maintains sufficient strength for structural support.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The implant utilizes controlled variations in material properties along its length, specifically creating a gradient in mechanical stiffness and strength. This parameter change from uniform to gradient structure enables the implant to adapt to the varying mechanical demands at different locations, reducing stress concentration and preventing endplate collapse.

Inventive Principle:

Principle #35Parameter changes

2Ease of manufacture

If uniform mechanical properties are used throughout the implant, then manufacturing is simplified, but uneven load distribution occurs across the vertebral surface increasing injury risk

Engineering Contradiction:

Improveimplant manufacturing simplicityVSAvoidvertebral surface injury risk

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The implant features a gradient structure with varying mechanical properties along its length, where the distal end has lower stiffness and strength to match weaker vertebral bone, while the proximal end has higher properties for structural support. This local differentiation optimizes load distribution across the vertebral surface, reducing the risk of stress concentration and vertebral injury.

Inventive Principle:

Principle #3Local quality

3Reliability

If revision surgery is performed to address subsidence, then the implant problem is corrected, but the success rate decreases with each additional revision

Engineering Contradiction:

Improverevision surgery success rateVSAvoidtime for multiple surgeries

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The gradient structure is designed in advance based on pre-operative assessment of the patient's specific vertebral bone quality. By anticipating the mechanical property mismatch before surgery, the implant is customized to prevent subsidence from occurring in the first place, eliminating the need for revision surgeries and avoiding the decreased success rates associated with multiple 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 customized spinal implant device reduces the risk of post-operative vertebral surface injury and subsidence by matching the mechanical properties of the implant to the vertebral contact surface, enhancing the success rate of spinal fusion surgery and minimizing the need for revision surgeries.

Implementation Method 1

determining the actual spatial mechanical properties of the vertebral contact surface comprises utilizing computed tomography to determine at least one of size, shape, and distribution of the actual spatial mechanical properties

Methodology Applied

Scientific EffectComputed tomography: Tomography

Data Source

PatentUS12042394B2Patient-specific spinal implants

Publication Date: 2024.07.23 THE REGENTS OF THE UNIVERSITY OF COLORADO

AI summary

A spinal implant device comprising a frame and a plurality of mechanical stiffness members extending from the frame, with the plurality of mechanical stiffness members being individually customized to provide a specific axial stiffness. The plurality of mechanical stiffness members may be coupled to the frame, and the plurality of mechanical stiffness members may be a plurality of wave-spring modules. A method of treating spinal disease includes determining actual spatial mechanical properties across a vertebral contact surface of a vertebra of a patient. The method may also include manufacturing a spinal implant device that has conforming spatial mechanical properties that are specific to the patient and that are based on the actual spatial mechanical properties of the vertebral contact surface. The method may include surgically implanting the spinal implant device against the vertebral contact surface such that the actual spatial mechanical properties and the conforming spatial mechanical properties align.