Expandable Interbody Fusion Device with Nested Wafer Stack
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Solution Overview
Problem
Existing interbody fusion devices face challenges in achieving stable fusion without additional stabilizing devices, are often bulky, and require pre-distraction to fit anatomically, leading to larger surgical sites and inefficiencies in minimally invasive procedures.
Innovation Solution
An expandable interbody fusion device with upper and lower plates that support expansion members, allowing sequential insertion of wafers to distract and stabilize the intervertebral space, featuring releasable engagement features and resilient interlocking mechanisms for stability and anatomical fit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If interbody fusion devices are made bulky to completely fill the intervertebral space and restore normal spinal anatomy, then stability and anatomical fit are improved, but the device requires pre-distraction of opposed vertebrae and increases surgical site size
Solution Approach 1:
The device transitions from a static, fixed-size structure to a dynamic, expandable structure. The interbody fusion device begins in a compressed state for easy insertion through the spinal canal, then expands to its full anatomical size within the vertebral body to provide stability and restore disc height, eliminating the need for pre-distraction and reducing surgical site requirements
Solution Approach 2:
The device employs a nested configuration where multiple expansion members (wafer-like structures) are stacked within a single implant body. These nested expansion members can be sequentially inserted and expanded to achieve the desired disc height, allowing the device to start small for insertion and grow to the required size for stability
2Adaptability or versatility
If a collection of differently sized IBFDs is provided to fit every intervertebral disc space height, then anatomical adaptability is improved, but the device becomes unwieldy and impractical
Solution Approach 1:
Instead of providing multiple fixed-size devices, this invention uses a single dynamic device that can change its size. The expandable mechanism allows the same device to adapt to different intervertebral disc space heights by expanding to the required dimensions, eliminating the need for multiple different device sizes
Solution Approach 2:
The device achieves universality by designing a single implant that can serve multiple anatomical sizes and configurations. The expandable mechanism enables one device to perform the function of multiple different-sized devices, making it universally applicable to various patient anatomies
3Device complexity
If existing interbody fusion devices are used without additional stabilizing devices, then surgical simplicity is improved, but fusion stability is insufficient
Solution Approach 1:
The device is segmented into multiple functional components: endplates for vertebral attachment, expansion members for height adjustment, and internal support structures for stability. This segmentation allows each component to perform its specific function independently, providing both surgical simplicity and fusion stability without requiring additional external stabilizing devices
Solution Approach 2:
The device utilizes composite construction combining rigid materials for structural support and stability, with expandable elements that provide controlled distraction. This composite approach integrates multiple functions (stability, distraction, fusion promotion) into a single device, eliminating the need for separate stabilizing hardware
Data Source
AI summary
An expandable interbody fusion device includes superior and inferior plates that are configured to receive a sequentially inserted stack of expansion members or wafers. The superior and inferior plates include features that at least initially interlock the two plates until the superior plate is dislodged by pressure from the growing wafer stack. The wafers include features on their top and bottom surfaces that interlock the wafers in multiple degrees of freedom so that the wafer stack is not disrupted when the fusion device is fully expanded. Each wafer also includes features that interlock with the inferior plate until the wafer is dislodged by sequential introduction of another wafer.