Polyaxial Pedicle Screw Fastener Assembly
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Solution Overview
Problem
Current polyaxial pedicle screw assemblies in spinal surgery often require additional connections between fusion rods, limiting direct attachment to existing pedicle screws, which can complicate surgical procedures and reduce flexibility.
Innovation Solution
A fastener assembly that includes a polyaxial head with a prosthetic member, a fastening portion such as a wedge, closed, or open ring, and a connector element allowing direct connection to the pedicle screw, enabling secure attachment of fusion rods or crossbars to the spinal structure without intermediate connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If additional connections are used between fusion rods, then connection flexibility is improved, but device complexity increases
Solution Approach 1:
The patent extracts the connection function from the fusion rod system and relocates it directly to the polyaxial pedicle screw head. The fastening portion with wedge ring and conical ring enables direct attachment of fusion rods to the screw head, eliminating the need for intermediate connections between fusion rods and reducing procedural complexity.
Solution Approach 2:
The fastening portion acts as an intermediary mechanism between the polyaxial pedicle screw and the fusion rod. The wedge ring and conical ring configuration provides a reliable intermediate connection that simplifies the overall assembly by enabling direct screw-to-rod attachment without requiring additional connection elements.
2Device complexity
If direct attachment to pedicle screw is enabled, then device complexity is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The polyaxial head is pre-configured with a recess that receives the fastening portion during the initial screw installation. This preliminary preparation ensures that when the fastening portion is inserted, it automatically aligns with the recess, reducing the precision requirements for subsequent fastening operations and enabling direct attachment without complex alignment procedures.
Solution Approach 2:
The wedge ring and conical ring configuration provides a self-aligning and self-locking mechanism. The conical periphery of the wedge ring fits into the corresponding conical recess, and the wedge action automatically secures the fastening portion in place, reducing the need for high-precision manual alignment during surgery.
3Reliability
If wedge ring and conical ring fastening mechanism is used, then fastening reliability is improved, but device complexity increases
Solution Approach 1:
The fastening portion combines multiple fastening functions into a single integrated component. The wedge ring with conical periphery and the conical ring work together as a unified fastening mechanism that provides reliable attachment while minimizing the number of separate parts. The connecting member is integrated into the conical ring, eliminating the need for additional separate connection elements.
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
Enables flexible and secure attachment of spinal elements directly to existing polyaxial pedicle screws, enhancing surgical precision and reducing procedural complexity by providing a robust and versatile connection method.
Implementation Method 1
the conical ring wedges the wedge ring onto the polyaxial head
Implementation Method 2
a second mechanical fastener that fastens to the first mechanical fastener and is tightened against the closed ring
Implementation Method 3
a mechanical fastener that fastens end portions of the open ring towards each other so as to clamp the open ring onto the polyaxial head
Data Source
AI summary
A fastener assembly including an existing polyaxial pedicle screw that has been previously installed in a spinal structure, the polyaxial pedicle screw including a polyaxial head to which a prosthetic member is secured, a fastening portion fastened to the polyaxial head over the prosthetic member, and a connector element that extends from the fastening portion, the connector element being connected to another spinal structure.