Spinal Interbody Cage with Flexible Barb Endplate
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Solution Overview
Problem
Current interbody cages for spinal fusion often fail due to insufficient endplate support, leading to subsidence and loss of fixation, as they cannot effectively distribute the stress across the vertebral surfaces without weakening the disc space.
Innovation Solution
A spinal interbody cage design featuring a separately attachable endplate with flexible barbs that grip vertebral surfaces, reducing the force per unit area and enhancing fixation by using serrations and internal threading for secure attachment, while the cage itself is made from biocompatible materials like titanium or PEEK.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the endplate is made to support the full stress of the cage, then the cage can be securely fixed, but the endplate fails due to inability to support the stress, leading to subsidence and loss of fixation
Solution Approach 1:
The invention divides the load-bearing function into two separate components: the rigid cage structure provides primary mechanical support and stress distribution, while the flexible barbs provide secondary anchoring into the vertebral bone. This segmentation allows the endplate to focus on interfacing with the vertebral surface rather than bearing the full cage load alone, preventing endplate failure and subsidence.
Solution Approach 2:
The barbs are designed to be flexible rather than rigid, allowing them to dynamically adapt to the vertebral bone surface during insertion and loading. This flexibility enables the barbs to bend and conform to irregular bone surfaces, maximizing contact area and anchoring effectiveness while reducing stress concentration on the endplate.
2Stress or pressure
If the force per unit area on the cage endplate is decreased, then endplate failures and cage subsidence are reduced, but the fixation strength may be compromised
Solution Approach 1:
The invention transitions from a two-dimensional endplate-cage interface to a three-dimensional anchoring system by adding flexible barbs that extend into the vertebral bone volume. This dimensional addition creates multiple anchoring points distributed throughout the bone, distributing loads across a larger volume and reducing stress concentration at the endplate-bone interface while maintaining strong fixation.
Solution Approach 2:
The endplate assembly combines rigid cage material (for structural integrity and stress distribution) with flexible barb material (for adaptive anchoring). This composite structure allows the rigid component to distribute loads evenly while the flexible component provides secure bone engagement, achieving both low stress per unit area and high overall fixation strength.
3Reliability
If flexible barbs are added to the endplate, then fixation is enhanced and subsidence is minimized, but the device complexity increases
Solution Approach 1:
The flexible barbs are integrated directly into the endplate structure, merging the anchoring function with the existing endplate component rather than adding separate attachment mechanisms. This integration reduces the number of discrete parts and assembly steps while achieving enhanced fixation reliability through the combined endplate-barb system.
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 design improves fixation and reduces endplate failures by distributing stress more evenly across the vertebral surfaces, minimizing subsidence and enhancing the stability of the interbody cage implant.
Implementation Method 1
flexible barbs that grip vertebral surfaces
Implementation Method 2
Upper and lower surfaces of the cage and endplate include serrations or the like that grip respective upper and lower vertebral surfaces
Implementation Method 3
The head has internal threading that aids in inserting the barb into the cage during implantation
Data Source
AI summary
A spinal interbody cage implant includes a cage, an endplate, and flexible barbs. The endplate is separately attached to the cage and is configured to receive, hold and direct a flexible barb into an upper vertebral surface and a flexible barb into a lower adjacent vertebral surface. Each proximal leg of the cage is configured to receive the endplate, and has a lateral bore that receives a pin which retains the endplate. The endplate directs a first flexible barb upwardly toward an upper vertebral surface, and directs a second flexible barb downwardly toward a lower vertebral surface. Each flexible barb has a proximal head, a shaft extending from the head with a bore extending from the head to its distal end. Teeth are provided along the exterior surface of the shaft with two flats disposed on opposite sides thereof with a slit extending from the distal end towards the head.