Expandable Conforming Interbody Spacer for Vertebral Endplates
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Solution Overview
Problem
Current interbody spinal implants face challenges such as subsidence, endplate fractures, and stress shielding due to improper sizing and stiffness mismatch with vertebral endplates, leading to reduced effectiveness and increased costs.
Innovation Solution
The development of expandable, conformable interbody spacers with segmented endplate-contacting segments and a locking mechanism that distribute load equally, allowing the implant to conform to vertebral endplates and approximate the stiffness of bone, reducing the need for multiple implant sizes and minimizing stress concentrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single fixed-size implant is used, then device complexity and inventory costs are reduced, but the implant cannot conform to varying vertebral endplate shapes and sizes, leading to stress concentrations and implant failure
Solution Approach 1:
The implant is divided into multiple expandable segments or struts that can be independently adjusted to match the contours of vertebral endplates. This segmentation allows the single implant to adapt to various sizes and shapes without requiring multiple pre-fabricated implant sizes, thereby improving conformability while maintaining manageable device complexity through modular design
Solution Approach 2:
The implant incorporates expandable elements that can dynamically change size and shape after insertion to conform to the specific vertebral anatomy. This dynamic adaptability allows a single implant design to replace multiple fixed-size implants, improving versatility without significantly increasing overall device complexity
2Reliability
If multiple implant sizes are carried in inventory, then the correct sized implant can be selected for each patient, but inventory costs and device complexity increase
Solution Approach 1:
The implant is designed as a universal device that can be adjusted to fit multiple vertebral sizes and configurations through its expandable mechanism. This multi-functionality allows a single implant type to replace multiple size-specific implants in inventory, reducing the quantity of different implant sizes needed while maintaining the ability to achieve correct sizing for each patient
3Measurement precision
If trial-and-error implant selection is performed, then the surgeon can find the best fit, but incorrectly sized implants are contaminated and wasted, increasing costs
Solution Approach 1:
The implant allows preliminary insertion in a compact state followed by expansion to the final configured size after proper positioning is confirmed. This eliminates the need for trial-and-error selection of pre-sized implants, as the single implant can be adjusted to the correct size after insertion, preventing contamination and waste of incorrectly sized implants
4Ease of manufacture
If current fixed-stiffness implants are used, then manufacturing is simplified, but stiffness mismatch with vertebral endplates causes stress shielding and implant failure
Solution Approach 1:
The implant incorporates mechanisms that allow the stiffness parameter to be adjusted or varied after manufacturing, through expansion or configuration changes that modify the mechanical properties to match the specific vertebral endplate stiffness. This maintains manufacturing simplicity while achieving reliable stiffness matching through post-manufacturing parameter adjustment
Data Source
AI summary
An expanding, conforming interbody implant includes a plurality of superior and a plurality of inferior segments. The segments are adapted to individually expand, contact, and conform to endplates of vertebral bodies to distribute forces equally over the implant and across the vertebral endplates. Once a proper extension of the segments has been achieved, the segments are locked in position. The implant has a stiffness that approximates the stiffness of bone, and the implant minimizes problems with subsidence, endplate fractures, and stress shielding.