Expandable Spinal Implant Fixation
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Solution Overview
Problem
Conventional spinal implants fail to effectively stabilize vertebral motion segments, as they cannot expand to distract endplates, maintain interbody lordosis, and often lead to nonunion due to poor bone-implant interface, contributing to issues like 'flatback syndrome' and neuropraxia.
Innovation Solution
An expandable spinal implant with extendable fixation elements that can be deployed between vertebral endplates, using hydraulic fluid expansion to securely engage the endplates and provide controlled spinal correction in three dimensions, promoting bone growth and fusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional static spacers are used for interbody stabilization, then the implant can be inserted between vertebral bodies, but the implant cannot expand to distract endplates and maintain interbody lordosis
Solution Approach 1:
The implant transitions from a static structure to a dynamic expandable structure. The cage body includes expandable features that allow it to change volume after insertion, enabling distraction of the vertebral endplates while maintaining structural integrity. This dynamic capability resolves the contradiction by allowing the implant to adapt post-insertion without requiring a complex multi-component system.
Solution Approach 2:
The expandable mechanism is nested within the cage body structure. The expansion elements are contained within the cage and can be deployed inward or outward depending on the design, allowing the implant to expand from a compact insertion size to a larger stabilization size without requiring separate external components.
2Reliability
If conventional static cages are used, then the implant provides initial stabilization, but the interface between bone and biomaterial is weak leading to nonunion
Solution Approach 1:
The implant incorporates protrusions or fixation elements that are designed to engage with the vertebral bone surface before full loading occurs. These features are pre-positioned on the cage body to create immediate mechanical interlocking with the bone, preventing micromotion and enhancing the bone-implant interface from the moment of insertion.
Solution Approach 2:
The cage body incorporates porous or textured surfaces that facilitate bone ingrowth and enhance mechanical bonding. The porous structure allows bone tissue to penetrate and anchor into the implant surface, creating a strong biological and mechanical interface that prevents nonunion and enhances pullout strength.
3Volume of moving object
If conventional implants are used, then the procedure can be performed, but there is no reliable space creation for neural elements
Solution Approach 1:
The expandable cage allows the surgeon to insert a compact device and then expand it in situ to create the desired volume for neural element protection. This dynamic expansion capability enables reliable space creation without requiring a large insertion corridor, as the implant grows to its functional size after placement.
Solution Approach 2:
The expansion mechanism may involve segmented or articulated components that allow controlled volumetric increase. The cage can expand in a controlled manner to create uniform space distribution, ensuring adequate room for neural elements while maintaining ease of insertion in a minimally invasive fashion.
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 implant achieves enhanced pullout strength, maintains neural element space, reduces the risk of nonunion, and allows for minimally invasive procedures with improved spinal alignment and fusion outcomes, minimizing trauma and promoting early patient mobilization.
Implementation Method 1
using hydraulic fluid expansion to securely engage the endplates
Data Source
AI summary
A spinal implant which is configured to be deployed between adjacent vertebral bodies. The implant has at least one fixation element with a retracted configuration to facilitate deployment of the implant and an extended configuration so as to engage a surface of an adjacent vertebral body and secure the implant between two vertebral bodies. Preferably, the implant is expandable and has a minimal dimension in its unexpanded state that is smaller than the dimensions of the neuroforamen through which it must pass to be deployed within the intervertebral space. Once within the space between vertebral bodies, the implant can be expanded so as to engage the endplates of the adjacent vertebrae to effectively distract the anterior disc space, stabilize the motion segments and eliminate pathologic spine motion. Angular deformities can be corrected, and natural curvatures restored and maintained.