Expandable Spinal Implant Locking Mechanism
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Solution Overview
Problem
Existing spinal implants for intervertebral body stabilization lack the ability to expand and distract vertebral end plates, fix the device in place, and maintain interbody lordosis, leading to issues like 'flatback syndrome' and poor bone integration due to weak interfaces between bone and biomaterial.
Innovation Solution
A selectively expandable spinal implant with locking elements that can be expanded using fluid pressure or mechanical force to engage vertebral end plates, providing controlled spinal correction in three dimensions and locking the implant in place to prevent relative movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional static spacers are used for interbody stabilization, then the device can be inserted between vertebral bodies, but the device cannot expand or distract the end plates and cannot fix itself in place
Solution Approach 1:
The implant transitions from a static structure to a dynamic one through the inclusion of an expandable cage mechanism. The cage can be compressed for insertion and then expanded within the intervertebral space to distract end plates and maintain lordosis, providing adaptability while remaining a single integrated device structure.
Solution Approach 2:
The locking elements are nested within the implant structure itself. The locking surfaces are formed as integral parts of the expandable cage and end plates, with locking elements that can engage with each other through rotational or translational movement, allowing the locking mechanism to be contained within the overall device footprint.
2Strength
If conventional static cages are used, then the implant can be inserted, but poor interface between bone and biomaterial results in weak bonding and nonunion
Solution Approach 1:
The end plates incorporate localized surface features such as ridges, grooves, or coated regions that enhance bone-implant interface strength. These surface modifications are applied specifically at the bone-contacting surfaces rather than throughout the entire implant, providing enhanced bonding where needed while maintaining overall structural integrity.
Solution Approach 2:
The end plates feature curved or contoured surfaces that match the natural anatomy of vertebral end plates. This curvature enhances contact area and distributes loads more evenly, improving the bone-implant interface strength and promoting osseointegration.
3Stability of the object's composition
If conventional static spacers are used, then the device can be placed between vertebral bodies, but the device cannot maintain interbody lordosis and contributes to flatback syndrome
Solution Approach 1:
The expandable cage provides dynamic control over the restoration and maintenance of interbody lordosis. By adjusting the expansion程度, the surgeon can precisely control the height and angle of the spinal segment, ensuring proper lordotic curvature is maintained while preventing flatback syndrome.
Solution Approach 2:
The implant is divided into functional segments including end plates for bone engagement, an expandable cage body for volume adjustment, and locking mechanisms for stabilization. This segmentation allows each component to be optimized for its specific function while working together to maintain interbody lordosis.
4Adaptability or versatility
If conventional static spacers are used, then the device can be inserted, but the device cannot provide controlled spinal correction in three dimensions
Solution Approach 1:
The expandable cage mechanism enables dynamic adjustment of the implant volume and shape, allowing controlled spinal correction in three dimensions. The cage can be expanded to distract end plates vertically, while the overall device geometry can be selected or adjusted to correct sagittal, coronal, and transverse plane deformities.
Solution Approach 2:
The implant is designed as a multi-functional device that combines distraction, stabilization, and correction capabilities in a single structure. The expandable cage can address multiple deformity types (scoliosis, kyphosis, listhesis) and can be used in various spinal levels, providing universal applicability across different clinical scenarios.
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 effectively distracts intervertebral spaces, restores neural element space, stabilizes the motion segment, and enhances spine arthrodesis by promoting bone fusion and correcting spinal deformities such as scoliosis and kyphosis.
Implementation Method 1
The locking elements can be spring biased against the locking surfaces to lock the implant in the expanded configuration
Implementation Method 2
a force applied to the at least one moveable lock member forces the moveable locking surface into engagement with the fixed locking surface
Implementation Method 3
The implant includes: first and second pistons disposed on one the bone engaging member and cooperating with mating cylinders disposed on the opposite bone engaging member
Data Source
AI summary
A spinal implant which is configured to be deployed between adjacent vertebral bodies. The implant has at least one extendable support element with a retracted configuration to facilitate deployment of the implant and an extended configuration so as to expand the implant and effectively distract the disc space, stabilize the motion segments and eliminate pathologic spine motion. The implant has a minimal dimension in its unexpanded state that is smaller than the dimensions of the neuroforamen through which it typically passes to be deployed within the intervertebral space. The implant is provided with a locking system having a plurality of linked locking elements that work in unison to lock the implant in an extended configuration. Bone engaging anchors also may be provided to ensure secure positioning.