Flexible Interbody Spacer for Load Sharing and Controlled Motion
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Solution Overview
Problem
Existing interbody cage devices cause graft stress shielding, graft overloading, subsidence, and graft failure due to static components, leading to complications such as fibrous tissue formation, bone resorption, and pseudarthrosis, while dynamic stabilization devices fail to provide adequate load sharing and motion preservation.
Innovation Solution
The development of an interbody cage with flexible connecting members that allow elastic deformation and relative translation between superior and inferior members, featuring a posterior-to-anterior design with open anterior ends and apertures, facilitating load sharing and minimizing excessive motion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If static components are used in interbody cage devices, then structural stability is improved, but graft stress shielding and graft overloading occur leading to graft failure
Solution Approach 1:
The interbody cage incorporates flexible connecting members that enable dynamic motion between superior and inferior members, allowing the device to adapt to physiological spinal movements. This dynamic capability prevents stress shielding and overloading by distributing loads more naturally, thereby maintaining structural stability while avoiding graft failure.
Solution Approach 2:
The flexible connecting members change their mechanical parameters (flexibility, deformation) in response to applied loads, allowing the device to transition between rigid and compliant states. This parameter adjustment enables the cage to maintain stability under normal conditions while accommodating motion to prevent graft damage.
2Adaptability or versatility
If dynamic stabilization devices are used, then motion preservation is improved, but adequate load sharing is not provided
Solution Approach 1:
The flexible connecting members provide dynamic stabilization by allowing controlled motion between vertebral levels while maintaining load-bearing capacity. The members deform elastically under physiological loads, preserving natural spinal kinematics while distributing mechanical forces across the fusion construct.
Solution Approach 2:
The interbody cage combines rigid endplates for load bearing with flexible connecting members for motion preservation. This composite structure integrates materials or components with different mechanical properties to simultaneously achieve both load sharing and motion preservation functions.
3Force
If flexible connecting members allowing elastic deformation are used, then load sharing is improved, but device complexity increases
Solution Approach 1:
The interbody cage is segmented into superior and inferior rigid members connected by flexible connecting members. This segmentation allows each component to perform its specific function (load bearing or motion accommodation) while simplifying the overall design by dividing the complex mechanical requirements into manageable segments.
Solution Approach 2:
The flexible connecting members function as flexible elements that provide elastic deformation capability. These members are designed with appropriate geometry and material properties to achieve the desired flexibility while maintaining structural integrity, balancing load sharing performance with design simplicity.
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 interbody cage provides balanced load sharing, reduces stress shielding, and promotes effective bone fusion by allowing controlled motion, thereby minimizing graft failure and enhancing osseointegration.
Implementation Method 1
The connecting member is comprised of a shape that facilitates elastic deformation and relative translation between the superior and inferior members
Data Source
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AI summary
The present disclosure includes implant systems, devices, and implants. The interbody spacers including a first endplate, a second endplate, and a coupling member coupled to and extending between the first endplate and the second endplate. Methods of using the interbody spacers are also disclosed.