Lemniscate Spinal Rod Loop for Stress Distribution
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Solution Overview
Problem
Spinal rod fractures are a common failure in spinal fusion procedures due to fatigue over time, particularly in corrective osteotomy and long-segment spinal fusion, where the use of multiple rods and additional bone anchoring screws increases complexity and risk of structural failure at connector points.
Innovation Solution
A spinal fixation assembly that uses a lemniscate-shaped spinal rod loop with pedicle screws and a telescopic mechanism to provide increased rigidity and support, reducing the need for additional bone penetrating connections and fixture devices by allowing multiple coupling locations for pedicle screws, thereby distributing stress and minimizing deflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If multiple rods and rod-to-rod connectors are used to increase rigidity, then the structural strength is improved, but the device complexity and number of potential failure points increase
Solution Approach 1:
The single rod is segmented into multiple loops connected in series, where each loop can independently engage with pedicle screws. This segmentation allows the structure to achieve the rigidity of multiple rods while maintaining a unified, simpler configuration without requiring rod-to-rod connectors.
Solution Approach 2:
The invention transitions from a one-dimensional linear rod to a two-dimensional loop structure with multiple engagement points. Each loop provides additional spatial dimensions for screw engagement, effectively increasing structural strength without adding linear complexity through multiple connectors.
2Reliability
If multiple rods and connectors are used to prevent fatigue failure, then the reliability is improved, but the surgery time and operational complexity increase
Solution Approach 1:
The loop structure is pre-configured with multiple engagement points along its circumference, allowing surgeons to selectively engage screws at optimal positions without requiring complex intraoperative assembly of multiple separate rods and connectors. This preliminary design reduces surgical time while maintaining reliability.
Solution Approach 2:
The loop structure serves multiple functions simultaneously: it provides structural support, distributes stress across multiple engagement points, and allows flexible configuration for different surgical needs. This multi-functionality reduces the need for additional specialized components and procedures.
3Strength
If additional bone anchoring screws are used to increase rigidity, then the structural strength is improved, but the invasiveness and potential complications increase
Solution Approach 1:
The loop structure allows for localized engagement at specific positions around the rod, enabling surgeons to place screws only where structural support is needed rather than uniformly distributing screws along the entire rod length. This reduces unnecessary bone penetration while maintaining strength where required.
Solution Approach 2:
The invention changes the geometric parameter from a linear rod to a loop configuration, which fundamentally alters how structural strength is achieved. Instead of requiring additional screws along the length, the loop's closed geometry provides inherent structural advantage with fewer engagement points.
Data Source
AI summary
Disclosed herein are a spinal fixation assembly and method to provide adequate rigidity and support for a vertebral column without requiring additional pedicle screws and spinal rods. The spinal fixation assembly includes a spinal rod loop with multiple sides configured to be attached to a vertebral body with two or more pedicle screws. Each pedicle screw is adapted to fit at various locations along the spinal rod loop.