Spinal Tether Cross-Member Stabilization
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Solution Overview
Problem
Current spinal implants that restrict flexion for discogenic pain often lose symmetry and displacement, leading to ineffective elastic force distribution, which can exacerbate spinal flexion instability in patients with discogenic pain and spondylolisthesis.
Innovation Solution
The use of a tether structure with compliance members and a cross-member that stabilizes the device by maintaining symmetry and preventing circumferential displacement, ensuring uniform elastic force application during spinal flexion, while allowing unrestricted extension.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a tether structure with compliance members is used to restrict spinal flexion, then elastic force is applied to reduce pain and instability, but the device may lose symmetry and undergo circumferential displacement, reducing effectiveness
Solution Approach 1:
The tether structure is divided into multiple discrete compliance members (first compliance member, second compliance member, third compliance member, fourth compliance member) that are independently attached to the spinous processes. This segmentation allows each compliance member to function independently while collectively maintaining device symmetry and preventing circumferential displacement, thereby resolving the contradiction between providing elastic force and maintaining structural stability.
Solution Approach 2:
The patent combines multiple compliance members with a central tether structure to create an integrated system. The compliance members are attached to opposite sides of the tether structure and to opposite sides of the spinous processes, merging the elastic restraint function with the symmetry-maintaining function into a single unified device that simultaneously provides pain relief and structural stability.
2Adaptability or versatility
If the tether structure is made compliant to allow elastic elongation, then it can apply tension during flexion, but it may deform and lose its intended configuration
Solution Approach 1:
Different parts of the device have different mechanical properties: the compliance members are designed to be elastic and compliant to allow movement and apply tension during flexion, while the tether structure and attachment points are designed to be more rigid to maintain overall structural integrity and prevent deformation. This local differentiation of mechanical properties allows the device to simultaneously adapt to flexion and maintain its intended configuration.
Solution Approach 2:
The device incorporates dynamic elements (compliance members) that can change their mechanical state in response to loading conditions. During spinal flexion, the compliance members elongate and apply tension; during extension, they return to their original configuration. This dynamic behavior allows the device to adapt to physiological movements while maintaining structural integrity through the rigid tether structure that constrains the overall geometry.
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 solution effectively restricts spinal flexion, reducing pain and instability in patients with discogenic pain and spondylolisthesis by providing consistent elastic tension without compromising spinal extension, thus improving treatment outcomes for these conditions.
Implementation Method 1
at least a portion of the tether structure is adapted to elastically elongate to apply tension to the spinous processes as the spine undergoes flexion
Data Source
AI summary
A spinal implant for limiting flexion of the spine includes a tether structure for encircling adjacent spinal processes. Usually, a pair of compliance members will be provided as part of the tether structure for elastically limiting flexion while permitting an extension. A cross-member is provided between the compliance member or other portions of the tether structure to stabilize the tether structure and prevent misalignment after implantation.