Multi-Axial Vertebral Fixation Fastener Assembly
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Solution Overview
Problem
Existing vertebral fixation systems for connecting fastener elements, such as pedicle screws, to elongated supports like rods lack effective mechanisms for multi-axial movement and secure angular orientation, leading to instability and potential complications in spinal fixation procedures.
Innovation Solution
A fastener assembly that includes a deformation element, a retention ring, and a compression element, allowing for an interference fit between the fastener head, retention ring, and rod, which enables multi-axial movement and secure angular locking by deforming the deformation element when the compression element is applied, thereby stabilizing the fastener relative to the rod.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional rigid connection methods are used to connect fastener elements to rods, then structural strength is improved, but multi-axial adjustability is lost
Solution Approach 1:
The connection system transitions from a rigid fixed state to a dynamic adjustable state. The fastener assembly allows multi-axial movement during installation to achieve proper alignment, then locks into a stable fixed position once the desired angular relationship is achieved, providing both adjustability and strength
Solution Approach 2:
The system changes the angular parameter between the fastener element and rod during installation. The connection allows adjustment of the angular relationship in multiple axes, then maintains the selected parameter configuration through interference fit and deformation locking mechanisms
2Adaptability or versatility
If multi-axial movement freedom is increased, then adaptability is improved, but connection stability deteriorates
Solution Approach 1:
The connection exhibits dynamic behavior where it is mobile during adjustment but becomes fixed after positioning. The interference fit mechanism and deformation element create a transition from a movable state (allowing multi-axial adjustment) to a stable locked state (maintaining angular relationship)
Solution Approach 2:
The deformation element automatically locks the fastener head at the desired angular position without requiring additional locking components. The interference fit between components self-adjusts to maintain the selected angular relationship, providing inherent stability
3Stability of the object's composition
If interference fit is applied to lock angular relationship, then connection stability is improved, but ease of adjustment deteriorates
Solution Approach 1:
The system allows preliminary adjustment of the angular relationship before final locking occurs. The fastener can be positioned and oriented in the desired multi-axial configuration, and only after this preliminary positioning is achieved does the interference fit and deformation element engage to lock the position
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 provides enhanced stability and secure angular locking of the fastener relative to the rod, enabling precise multi-axial adjustment and improved fixation in spinal procedures, particularly useful for cannulated pedicle screws where traditional methods may compromise adjustability.
Implementation Method 1
deforming the deformation element when the compression element is applied
Implementation Method 2
interference fit between the fastener head, retention ring, and rod
Data Source
AI summary
In one embodiment of the present invention a system for connecting a fastener element (e.g., a pedicle screw) relative to a rod for the purposes of vertebral fixation is provided. The system may permit multi-axial movement between the fastener element and the rod. Further, the system may permit the angular relationship between the fastener element and the rod to be held in a desired orientation. For the purposes of describing and claiming the present invention, the term “rod” is intended to refer to any elongated structure. Such an elongated structure may be solid or hollow and may have any desired cross-section (e.g., circular, oval, square, rectangular). Further, for the purposes of describing and claiming the present invention, the term “interference fit” is intended to refer to physical contact between two or more components.