Spinal Fusion Transition Member for Adjacent Flexion Load Attenuation
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Solution Overview
Problem
Post-surgical complications such as proximal junctional kyphosis (PJK) and distal junctional kyphosis (DJK) are common following spinal fusion, resulting from increased flexion loads on the spine proximal to the terminal instrumented vertebra, which can lead to radiographic changes, aesthetic issues, back pain, and disability.
Innovation Solution
A transition member with a tension component is coupled to fused and adjacent unfused vertebrae, allowing for the modulation of flexion range of motion by transferring loads onto the fused vertebrae, thereby attenuating hypermobilization and reducing the risk of PJK and DJK.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If spinal fusion is performed to stabilize the spine, then spinal stability is improved, but increased flexion loads are transferred to adjacent unfused vertebrae leading to hypermobilization and kyphosis
Solution Approach 1:
A transition member is introduced as an intermediary element between the fused instrumented vertebrae and the adjacent unfused vertebrae. This transition member includes a tension component that couples to both the fusion implant and the adjacent vertebra, serving as a mediator to distribute and attenuate the flexion loads that would otherwise be concentrated on the adjacent unfused vertebrae, thereby reducing hypermobilization and kyphosis risk while maintaining spinal stability
2Object-affected harmful factors
If the tension component is tensioned to a higher value to better attenuate flexion loads, then protection against kyphosis is improved, but the device complexity and surgical procedure complexity increase
Solution Approach 1:
The tension component is designed with adjustable tensioning capabilities, allowing the surgeon to modify the tension parameter to achieve the desired load attenuation effect. The system includes mechanisms for tensioning and locking the tension component at specific values, enabling parameter optimization to balance protective effect against kyphosis with device complexity and surgical procedure requirements
3Strength
If a rigid fusion implant is used to maximize fusion stability, then spinal stability is improved, but the adjacent unfused vertebrae experience increased stress and hypermobilization
Solution Approach 1:
The transition member provides localized quality modification by creating a gradient transition between the rigid fusion implant and the more mobile adjacent vertebrae. The tension component distributes loads locally at the junction zone, reducing stress concentration on the adjacent unfused vertebrae while maintaining the overall strength and stability of the fusion construct
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3
AI summary
Implementations described herein include devices and systems for attenuation of increased spinal flexion loads post-fusion that include a transition member. The transition member may have a tension component coupleable to a fused vertebra of a plurality of fused vertebra of a fusion implant and to an adjacent unfused vertebra. The tension component may be tensionable to a selected value. The tension component may modulate a flexion range of motion of the adjacent unfused vertebra as a function of the selected value of tension of the tension component. The transition member may attenuate spinal flexion loads on adjacent unfused vertebra post-operatively.