Modular Stemmed Implant Assembly for Stress Shielding Reduction
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Solution Overview
Problem
Existing stemmed prosthetic implants for joint replacement procedures suffer from stress shielding and periprosthetic bone loss, leading to implant loosening and complex secondary arthroplasties due to limited customization and poor fixation to patient-specific bone anatomy.
Innovation Solution
A stemmed modular implant system with a customizable stem component and accessory components that engage cortical and cancellous bone, allowing surgeons to select and assemble components based on patient-specific bone characteristics to distribute stress forces effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a universal stemmed implant design is used, then manufacturing and inventory are simplified, but the implant cannot be customized to patient-specific bone anatomy, leading to stress shielding and periprosthetic bone loss
Solution Approach 1:
The implant is divided into multiple modular components: a stem component with coupling surface and multiple accessory components (first, second, third accessory components) that can be selectively assembled. Each accessory component has different engagement features for cortical and cancellous bone, allowing customization based on patient anatomy while maintaining a manageable component system.
Solution Approach 2:
The stem component serves as a universal base that can accommodate multiple different accessory components through standardized coupling surfaces. This allows a single stem design to work with various accessory components, achieving patient-specific customization without requiring multiple complete implant systems.
2Reliability
If a stemmed implant is implanted, then joint replacement functionality is restored, but stress shielding occurs causing periprosthetic bone loss and implant loosening
Solution Approach 1:
Different accessory components are designed with specific engagement features for different bone types: some components have features for engaging cortical bone while others engage cancellous bone. This allows the implant to distribute stress forces appropriately to different bone regions, preventing stress shielding and maintaining bone health while ensuring implant stability.
3Object-generated harmful factors
If accessory components are selectively assembled to match patient anatomy, then stress distribution is optimized preventing bone loss, but the assembly process becomes more complex
Solution Approach 1:
The appropriate accessory component is selected and assembled to the stem component before implantation into the patient. This preliminary assembly allows the surgical team to optimize stress distribution based on preoperative planning and patient anatomy, while simplifying the actual implantation process by having the custom configuration ready in advance.
Data Source
AI summary
A stemmed implant system can include a stem component and an accessory component. The stemmed component can include a first portion adapted to be anchored within a medullary canal of a bone and a second portion including a mounting boss defining an inner coupling surface. The accessory component can define an outer coupling surface adapted to engage the inner coupling surface of the mounting boss of the stem component to secure the accessory component to the stem component.