Spinal Connector Assembly for Multi-Planar Rod Adjustment
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Solution Overview
Problem
Current spinal fixation systems face challenges in the lower lumbar spine and thoracolumbar region due to varying pedicle locations in coronal and axial planes, leading to difficulties in instrumentation assembly, rod weakening, inconsistent curvature, suboptimal screw placement, and compromised stability.
Innovation Solution
A pedicle screw system with a connector assembly that provides axial, coronal, and sagittal adaptability, allowing for precise positioning and locking of rods, using a posted screw with a vertically-splined shank and a connector assembly that can be adjusted and locked in multiple planes, accommodating variability in patient anatomy and deformity correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If surgeons bend the rods in the coronal plane to address varying pedicle locations, then assembly is facilitated, but the rods are weakened and the bend is inconsistent
Solution Approach 1:
The connector assembly divides the rod into segments, allowing each rod segment to remain straight and strong while the connector provides the necessary coronal plane adjustment through its articulated design with multiple degrees of freedom
Solution Approach 2:
The connector assembly introduces an additional dimension of adjustment by allowing rotation and articulation in the coronal plane while maintaining rod integrity, effectively moving the bending function from the rod to the connector mechanism
2Ease of operation
If surgeons rotate the rods into the coronal plane to address varying pedicle locations, then assembly is facilitated, but the lordotic shape is lost and stabilization effectiveness is lowered
Solution Approach 1:
The connector assembly separates the rod from the adjustment mechanism, allowing the rod to maintain its lordotic curvature while the connector provides independent coronal plane rotation and positioning capabilities
Solution Approach 2:
The connector assembly acts as an intermediary between the rod and the pedicle screw, providing the necessary rotational and positional adjustments without compromising the rod's lordotic shape or the overall stabilization effectiveness
3Ease of operation
If surgeons compromise the screw insertion path into the pedicle to facilitate assembly, then assembly is easier, but fixation is suboptimal and screw loosening or separation risk increases
Solution Approach 1:
Instead of compromising the screw insertion path for ease of assembly, the connector assembly is designed to accommodate natural anatomical variations in pedicle location through its multi-planar adjustment capabilities, allowing optimal screw placement while facilitating assembly
Solution Approach 2:
The connector assembly provides dynamic adjustment capabilities in multiple planes, allowing the surgeon to optimize both screw insertion path and assembly ease by adjusting the connector position and orientation after initial placement
4Ease of operation
If surgeons skip levels to facilitate assembly, then assembly is easier, but spinal stabilization system stability is compromised and rod breakage risk increases
Solution Approach 1:
The connector assembly enables independent adjustment at each vertebral level, allowing surgeons to address varying pedicle locations at consecutive levels without skipping, thereby maintaining system stability while facilitating assembly through localized adaptation
5Adaptability or versatility
If connector-based systems are used to address varying pedicle locations, then adaptability is improved, but the connector rotates around the screws in the coronal plane when compression is applied
Solution Approach 1:
The connector assembly is designed with pre-configured articulation points and locking mechanisms that prevent rotation around screws during compression, while still allowing necessary adjustments for varying pedicle locations through controlled degrees of freedom
Solution Approach 2:
The connector assembly provides controlled dynamic movement capabilities, allowing adjustment for varying pedicle locations through specific degrees of freedom while maintaining stability and preventing unwanted rotation during compression through mechanical constraints
Data Source
AI summary
A posted anchor and connector-based system including a splined shank headless anchor, various width adjustable connectors for use in open or minimally invasive thoracolumbar spine surgery. The connectors have a high degree of coronal, vertical, as well as sagittal adaptability. In one example, each plane of motion is individually secured for maximum versatility.