Multi-Axial Screw Assembly for Spinal Fusion Fixation
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Solution Overview
Problem
Current spinal treatment methods lack effective solutions for securely attaching longitudinal members to vertebral members while allowing for multi-axial movement and stress distribution, which is crucial for spinal fusion and motion preservation.
Innovation Solution
A multi-axial screw assembly comprising a screw with a threaded shank and enlarged head, a receiver with a channel and chamber to accommodate the screw head, and a set screw to capture a longitudinal member, allowing for secure attachment and movement in various angular positions through deformation of the receiver.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a rigid attachment method is used to securely fix the longitudinal member to the vertebral member, then the fixation strength is improved, but the ability to accommodate multi-axial movement and spinal fusion is reduced
Solution Approach 1:
The receiver is designed with deformation capability to transition from an initial state that allows multi-axial movement to a deformed state that provides rigid fixation. This dynamic transformation enables the system to adapt between flexible and rigid attachment modes based on surgical needs.
Solution Approach 2:
The mechanical properties of the receiver are changed through deformation, altering its geometric parameters and structural characteristics. This parameter change enables the receiver to provide both initial flexibility for multi-axial movement and subsequent rigidity for secure fixation.
2Adaptability or versatility
If a deformable receiver is used to accommodate multi-axial movement, then the adaptability is improved, but the secure fixation capability is reduced
Solution Approach 1:
The receiver's deformation capability is utilized to transition from a flexible state that accommodates multi-axial movement to a rigid deformed state that provides secure fixation. This dynamic behavior resolves the contradiction between adaptability and fixation strength.
Solution Approach 2:
The receiver is pre-designed with specific deformation characteristics that allow it to be initially flexible for positioning and movement accommodation, then deformed to lock in place providing secure fixation. The preliminary design enables both flexible attachment and rigid fixation in sequence.
3Device complexity
If a simple attachment structure is used, then the device complexity is reduced, but the ability to distribute stress and accommodate movement is reduced
Solution Approach 1:
The receiver performs multiple functions within a single component: it provides initial flexible attachment, accommodates multi-axial movement, enables precise positioning, and upon deformation provides secure rigid fixation with stress distribution. This multi-functionality reduces the need for multiple separate components.
Solution Approach 2:
The receiver's dynamic deformation capability allows a simple initial structure to transform into a complex stress-distributing fixation structure, achieving both simplicity and functionality without requiring multiple separate components.
Data Source
AI summary
The present application is directed to multi-axial screw assemblies to connect a longitudinal member to a vertebral member. In one embodiment, the multi-axial screw assembly includes a screw comprising a threaded shank and an enlarged head. The assembly may also include a body with an upper channel sized to receive the longitudinal member, a lower chamber to receive the head. The body is constructed to maintain the head in the lower chamber.