Tethered Restraint of Vertebral Bodies With Friction-Groove Anchoring
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Solution Overview
Problem
Current vertebral body tethering systems lack predictability in the response of spinal growth plates to guided growth, and there are limitations in existing designs that do not account for segmental tension and long-term effects on discs, with potential risks to spinal cord blood supply and complications in surgical access.
Innovation Solution
The use of a tethering system with a flexible connector and a tether restraining member that includes a channel with converging grooves to provide controlled compression and frictional restraint, allowing for relative motion between vertebrae while minimizing damage and surgical complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed head bicortical screw is used to secure the tether, then the tether is firmly anchored to the vertebrae, but the surgical access is more complex and the risk to spinal cord blood supply is increased
Solution Approach 1:
The device is divided into separate functional components: a bone anchor that secures to the vertebrae and a tether restraining member that controls tether movement. This segmentation allows the bone anchor to be placed through simpler surgical access while the tether restraining member provides the anchoring function, reducing overall surgical complexity and risk to spinal cord blood supply.
2Reliability
If the channel for the flexible connector is enclosed, then the flexible connector is securely restrained, but the installation process becomes more difficult
Solution Approach 1:
The tether restraining member is pre-configured with an open top pathway that allows the flexible connector to be installed before the pathway is closed. The cap is then placed to close the pathway, securing the flexible connector in position. This preliminary action approach simplifies installation by allowing easy access during implantation while maintaining secure restraint in the final configuration.
3Ease of operation
If the channel walls are parallel, then the flexible connector can move freely, but the frictional compression is insufficient to restrain movement
Solution Approach 1:
The channel walls are configured with asymmetric grooves that are not perpendicular or parallel to the channel axis. These angled grooves create differential friction forces on the flexible connector, providing controlled restraint that allows necessary movement while preventing excessive displacement. The asymmetric geometry optimizes both movement capability and restraint reliability.
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 system enables controlled vertebral movement with reduced risk of spinal cord compromise and improved surgical accessibility, providing a biocompatible and effective long-term solution for vertebral body tethering.
Implementation Method 1
The movement of the flexible connection is opposed by placing the flexible connection in a channel that converges in a first direction so as to laterally and frictionally compress the flexible connection within the channel
Data Source
AI summary
Methods and devices for the tailored restraint of two separate bones, in which the bones are generally permitted to rotate relative to one another, or move toward each other, but are restrained from separating beyond a predetermined, fixed distance. In some embodiments, the restraint is provided by compressing a tether into a notched groove.