Shape Memory Polymer Scaffold for Bone Defect Repair

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Solution Overview

Problem

Current bone graft substitutes for critically sized defects in warfighters, such as those resulting from military injuries, face challenges including limited osseointegration, inferior mechanical strength, and complications like infection and amputation, with no reliable treatments for segmental defects.

Innovation Solution

A shape memory polymer (SMP) system comprising a scaffold for defect filling and expansion, an osteoconductive sleeve for stabilization, and a two-dimensional cell culture substrate for periosteal sheet engineering, which together facilitate osseointegration, osteogenesis, and remodeling, providing mechanical properties comparable to native bone and promoting healing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If synthetic bone graft substitutes are used, then ease of manufacture is improved, but mechanical strength and fracture resistance deteriorate

Engineering Contradiction:

Improveease of manufactureVSAvoidmechanical strength

Core Design Contradiction:

Ease of manufactureVSStrength

Solution Approach 1:

The patent employs composite materials combining calcium phosphate ceramics with polymer matrices to create bone graft substitutes that achieve both ease of manufacture and superior mechanical strength. The composite structure allows synthetic materials to be molded into complex shapes while maintaining fracture resistance comparable to native bone.

Inventive Principle:

Principle #40Composite materials

2Adaptability or versatility

If allograft is used, then availability is improved, but osseointegration and reliability deteriorate

Engineering Contradiction:

ImproveavailabilityVSAvoidosseointegration

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent utilizes porous materials with controlled pore structures that enhance osseointegration by facilitating bone ingrowth and vascularization. The porous architecture allows synthetic grafts to achieve reliable integration with host bone, overcoming the limitations of allograft while maintaining availability.

Inventive Principle:

Principle #31Porous materials

3Reliability

If autograft is used, then osseointegration is improved, but donor site morbidity and ease of operation deteriorate

Engineering Contradiction:

ImproveosseointegrationVSAvoidease of operation

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The patent extracts the essential osteoinductive and osteoconductive properties of autograft through biochemical treatments and surface modifications of synthetic materials. This allows synthetic grafts to achieve autograft-level osseointegration without requiring donor site harvesting, significantly improving ease of operation.

Inventive Principle:

Principle #2Taking out (Extraction)

4Productivity

If the scaffold is designed for rapid expansion, then productivity is improved, but manufacturing precision deteriorates

Engineering Contradiction:

ImproveproductivityVSAvoidmanufacturing precision

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent applies preliminary action by pre-programming the scaffold structure with shape memory features during manufacturing. The scaffold is fabricated in a compressed state with predetermined expansion patterns, allowing rapid in-situ expansion to precise geometries without compromising manufacturing precision or requiring complex post-processing.

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 SMP system enables effective repair of critically sized bone defects by conforming to the defect shape, stabilizing the site, and promoting healing, reducing the need for multiple surgeries and minimizing complications like infection and amputation, while offering a biodegradable and resorbable solution.

Implementation Method 1

Shape memory polymer (SMP) materials that, together, enable repair of critically sized bone defects

Methodology Applied

Scientific EffectShape memory polymer effect: Shape Memory Polymer

Implementation Method 2

linked together into a well-defined covalent network through photoinitiated addition of the vinyl termini with a multifunctional thiol crosslinker

Methodology Applied

Scientific EffectPhotoinitiated addition reaction: Photopolymerisation

Data Source

PatentUS10368993B2Shape-memory-actuated materials for accelerated healing of orthopedic injuries

Publication Date: 2019.08.06 SYRACUSE UNIVERSITY

AI summary

A three component system for repairing critically sized bone defects having a first shape memory polymer (SMP) component formed as a scaffold that fills the defects, a second SMP component formed as a restricting sleeve that stabilizes and supports osseointegration and osteoconduction, and a third SMP component formed as a two-dimensional cell culture substrate for engineering periosteal grafts.