Spinal Fixation Connectors With Flexible Extensions for PJK/PJF
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Solution Overview
Problem
Proximal junctional kyphosis (PJK) and proximal junctional failure (PJF) are complications arising from spinal surgeries, characterized by undesired kyphosis and potential failure at the uppermost instrumented vertebra, leading to increased pain, neurologic deficits, and the need for revision surgery.
Innovation Solution
A longitudinal extension is added to the primary fixation construct, attached to a first attachment point superior to the primary construct and a second attachment point inferior to it, providing a more flexible and less restrictive transition to natural patient anatomy, minimizing soft tissue disruption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a rigid primary fixation construct is implanted to stabilize the spine, then spinal stability is improved, but the risk of proximal junctional kyphosis and proximal junctional failure increases due to excessive forces on the uppermost instrumented vertebra
Solution Approach 1:
The patent changes the mechanical parameter of flexibility by introducing a longitudinal extension with different material properties or structural characteristics than the primary construct. The extension is configured to be more flexible, allowing it to absorb and distribute forces differently, thereby reducing stress concentration at the UIV while maintaining overall spinal stability.
Solution Approach 2:
The patent creates a composite fixation system combining the primary rigid construct with a secondary flexible extension. This composite structure integrates two different mechanical behaviors - the rigid primary construct provides foundational stability while the flexible extension provides force distribution and protection against junctional failure, creating a synergistic system that addresses both stability and reliability.
2Stability of the object's composition
If the primary construct is extended rigidly to additional vertebral levels, then spinal support is improved, but soft tissue disruption increases
Solution Approach 1:
The patent employs a flexible longitudinal extension that can conform to the natural curvature and movement of the spine without requiring rigid fixation. This flexible structure provides spinal support while minimizing interference with surrounding soft tissues, as it can accommodate physiological motion and requires less aggressive surgical implantation compared to rigid extensions.
3Reliability
If the extension is made more flexible to provide gradual transition, then the risk of PJK/PJF is reduced, but the degree of motion restriction decreases
Solution Approach 1:
The patent applies local quality by creating a gradient of stiffness along the spinal construct. The primary construct near the instrumented vertebrae maintains higher rigidity for stable fixation, while the longitudinal extension becomes progressively more flexible to provide gradual transition to natural anatomy. This spatial variation in mechanical properties allows the system to simultaneously restrict harmful motion at critical interfaces while permitting physiological movement in more distant regions.
Data Source
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AI summary
Systems and methods for reducing the risk of PJK, PJF, and other conditions are disclosed herein. In some embodiments, a longitudinal extension can be added to a primary fixation construct to extend the construct to one or more additional vertebral levels. The extension can be attached to a first attachment point, such as a spinous process of a vertebra that is superior to the primary construct. The extension can also be attached to a second attachment point, such as a component of the primary construct or an anatomical structure disposed inferior to the first attachment point. The extension can be more flexible than the primary construct and/or can limit motion to a lesser degree than the primary construct, thereby providing a more-gradual transition from the instrumented vertebrae to the natural patient anatomy adjacent thereto. The extension can be placed with little or no soft tissue disruption.