Spinal Screw Assembly with Rotatable Ball Joint and Pressure Cap
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Solution Overview
Problem
Conventional spinal fasteners tend to loosen or reverse rotate due to patient activity, necessitating repeated procedures and prolonged recovery, leading to increased pain and treatment duration.
Innovation Solution
A screw assembly for spinal implants featuring a rotatable second unit connected to a first unit with a pressure cap and C-ring mechanism, allowing for adjustable angle and position settings, and secure fixation to prevent loosening or escape.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If conventional spinal fasteners are used to fix screws into vertebral bodies, then the initial fixation is achieved, but the screws may loosen or reverse rotate due to patient activity
Solution Approach 1:
The invention introduces a rotatable second unit with a ball joint head that allows dynamic adjustment of the rod angle and position. The pressure cap mechanism dynamically secures the rod at the desired angle by pressing against the ball joint head, transforming from a static fixed-angle screw to a dynamic adjustable-angle system that maintains stability through controlled movement and locking.
Solution Approach 2:
The spinal fastener is divided into multiple functional units: a first unit with insertion holes, a rotatable second unit with ball joint head, a pressure cap mechanism, and a C-ring retention system. This segmentation allows each component to perform its specific function - the second unit provides angle adjustment, the pressure cap secures the position, and the C-ring prevents loosening - thereby resolving the contradiction between initial fixation and long-term retention.
2Adaptability or versatility
If the screw assembly allows angle and position adjustment for various patient types, then adaptability is improved, but device complexity increases
Solution Approach 1:
The rotatable second unit with ball joint head provides dynamic angle adjustment capability, allowing the rod to be positioned at various angles suitable for different patient anatomies. The pressure cap mechanism adds a locking function that secures the adjusted position, creating a versatile yet controllable system that adapts to various patient types without excessive complexity.
Solution Approach 2:
The second unit serves multiple functions: it allows angle adjustment, position adjustment, and works with the pressure cap and C-ring to provide secure retention. This multi-functionality reduces the need for multiple separate components, thereby achieving adaptability for various patient types while controlling overall device complexity.
Data Source
AI summary
A screw assembly for a spinal implant comprises a first unit including insertion holes and an inner space, a rod having a side whose outer circumference surface is positioned on the insertion holes of the first unit and another side whose outer circumference surface is positioned on insertion holes of another first unit positioned adjacent to the first unit, a second unit having an upper portion rotatably received in a lower portion of the inner space and a lower portion screwed to a vertebral body, a third unit screwed to an upper portion of the inner space to hold the rod, and a fourth unit positioned between the inner space and the upper portion of the second unit and including a pressure cap seated in the inner space.