Spinal Implant Inserter Reduces Local Stress
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Solution Overview
Problem
Spinal implants face significant stresses during implantation, which can limit the size of the cage and interior chamber, restricting the use of larger cannulated instruments and tissue ingrowth due to the need for substantial manipulation forces.
Innovation Solution
A spinal implant system with an inserter that attaches to the distal end of the implant, reducing local stresses and allowing for a larger access port and interior chamber, and an access tube for post-implantation access, enabling broader instrument use and tissue ingrowth without compromising structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the spinal implant is designed with a larger interior chamber and access port to accommodate broader instruments and promote tissue ingrowth, then the adaptability and tissue integration are improved, but the structural integrity and stress resistance during implantation deteriorate
Solution Approach 1:
The spinal implant is segmented into a cage body and a separate insertable component (cage or rod) that passes through the access port. This allows the exterior structure to maintain strength while the interior chamber can be larger for tissue ingrowth. The segmentation enables the implant to have both structural integrity and adaptability simultaneously.
Solution Approach 2:
The design employs a nested structure where one component (the insertable cage or rod) is placed inside another component (the main implant body). This nesting allows the exterior to maintain structural integrity while the interior chamber accommodates the insertable component and promotes tissue ingrowth, resolving the contradiction between strength and adaptability.
2Reliability
If the cage members are made thicker to withstand substantial stresses during implantation, then the strength and reliability are improved, but the size of the interior chamber is reduced, limiting instrument access and tissue ingrowth
Solution Approach 1:
The implant system is divided into stress-bearing external components and insertable internal components. The thicker cage members provide structural integrity for withstanding implantation stresses, while the insertable component (cage or rod) occupies the interior chamber space, allowing the chamber to be larger than it would be if all structural elements were solid thick walls.
Solution Approach 2:
Different parts of the implant have different thicknesses and properties. The exterior cage members are thicker to withstand stresses during implantation, while the interior chamber is designed with appropriate volume for tissue ingrowth. The local quality variation allows simultaneous optimization of strength and interior volume.
3Strength
If the access port is made smaller to maintain structural integrity, then the strength is improved, but the ability to accommodate cannulated instruments and promote tissue ingrowth is reduced
Solution Approach 1:
The implant system separates the access port function from the main structural body. The access port can be optimized for instrument passage while the main cage structure maintains structural integrity. The insertable component provides additional structural support, allowing the access port to be larger without compromising overall strength.
4Productivity
If substantial manipulation forces are applied to insert the spinal implant, then the implantation process is completed, but high compressive and torsional loads are imposed on the implant body, potentially compromising structural integrity
Solution Approach 1:
The inserter acts as an intermediary tool that transfers manipulation forces from the surgeon's hands to the implant. The inserter is designed to withstand these forces and transfer them to the implant in a controlled manner, protecting the implant body from direct exposure to high compressive and torsional loads during insertion.
Solution Approach 2:
The implant system includes a separate insertable component that can be pushed through the access port using the inserter. This segmentation allows the main implant body to remain stationary while the insertable component is manipulated, reducing the loads imposed on the main body during the insertion process.
Data Source
AI summary
A spinal implant system includes an inserter that passes through a spinal implant for attachment to a distal end of the spinal implant. By this arrangement, stability of the implant system is enhanced for placement of the spinal implant while reducing local stresses imparted at the attachment. The disclosed spinal implant system may include an access tube that is coupled to a proximal end of the spinal implant. After placement of the spinal implant, the inserter may be removed from the spinal implant and access tube, providing access via the access tube to an interior of the spinal implant and the corresponding space between the vertebral endplates.