Asymmetric Implants for Stress Shielding Reduction
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Solution Overview
Problem
Current orthopedic and dental implants fail to address stress shielding, a significant issue leading to bone loss due to the mechanical mismatch between implants and bone, resulting in reduced bone density and implant failure, as they are designed without consideration for the variability of internal bone architecture.
Innovation Solution
The development of asymmetric implant designs and coatings that match the anatomy and quality of individual bones, using imaging techniques to quantify bone quality and adjust material properties such as modulus of elasticity and surface coatings to minimize stress shielding and improve implant fixation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If rigid implant materials (high elastic modulus) are used to provide structural support, then implant strength is improved, but stress shielding and bone loss worsen due to mechanical mismatch
Solution Approach 1:
The implant incorporates regions with different elastic moduli to match the spatial variation of bone quality. High-modulus regions are positioned in areas of strong bone to provide structural support, while low-modulus regions are positioned in areas of weaker bone to reduce stress shielding and allow physiological loading. This local differentiation resolves the contradiction by providing strength where needed while minimizing harmful stress shielding in other regions.
Solution Approach 2:
The implant uses composite material construction combining metals with different elastic moduli (e.g., titanium and cobalt-chrome) or metal with polymer coatings. This composite structure enables the implant to simultaneously provide high strength in critical load-bearing regions while presenting lower modulus surfaces to bone to reduce stress shielding effects, thereby resolving the contradiction between strength and stress shielding.
2Ease of manufacture
If symmetric implant designs are used to simplify manufacturing and reduce inventory costs, then ease of manufacture is improved, but adaptability to individual bone architecture worsens
Solution Approach 1:
The implant system transitions from static symmetric designs to dynamic asymmetric designs that can be customized for individual patients. Digital planning tools and patient-specific imaging data enable the creation of asymmetric implant configurations that adapt to each patient's unique bone architecture, while modern manufacturing techniques like selective laser melting maintain ease of production. This resolves the contradiction by making adaptability achievable without sacrificing manufacturing efficiency.
3Device complexity
If uniform material properties are used throughout the implant, then device complexity is reduced, but the ability to address variable bone quality worsens
Solution Approach 1:
The implant features spatially varying material properties with different elastic moduli distributed according to the patient's bone quality map. Regions of high bone quality receive high-modulus implant material, while regions of low bone quality receive low-modulus material. This local differentiation addresses variable bone quality effectively while maintaining relatively simple overall device structure through systematic material distribution patterns.
Data Source
AI summary
Systems and methods are provided for implant design and manufacturing to address stress shielding and/or implant fixation. The implant design and methodology may include accounting for the anatomy and quality of a bone of a subject to address stress shielding and/or implant fixation considerations for the subject. Implants or components may be asymmetrically designed to better match the associated anatomy as well as decrease stress shielding or improve implant fixation, such as by quantifying bone quality and matching properties of the implant or coatings of the implant to optimize engagement between the implant and the highest quality bone. Information derived from the methodology can be used to guide the design of the implant resulting in an asymmetric design that minimizes or eliminates stress shielding or improves implant fixation.