Pedicle Screw Tulip Head Alignment
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Solution Overview
Problem
Existing pedicle screws for spinal immobilization procedures are complex and difficult to use, requiring multiple steps and tools, and often lead to complications in securing spine rods to vertebrae, especially in varying anatomical and clinical situations.
Innovation Solution
A pedicle screw system featuring a cannulated screw with aggressive threads and a tulip head with a locking cap and nut assembly, allowing for easy alignment and secure attachment of a spine rod at various angles, with a low-profile design to minimize impact on adjacent body structures and accommodate precurved rods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If traditional pedicle screw designs are used, then secure attachment to spine rod is achieved, but the procedure becomes complex and difficult to use
Solution Approach 1:
The pedicle screw is divided into distinct functional segments: a cannulated body with aggressive threads for bone engagement, a low-profile spherical head for rod alignment, and a separate locking mechanism. This segmentation allows each component to perform its specific function independently, simplifying the overall assembly and insertion process while maintaining secure attachment capabilities.
Solution Approach 2:
The screw head is designed with a low-profile spherical contour that facilitates easy alignment and coupling with the spine rod at various angles. The spherical geometry allows the rod to be inserted from multiple directions without requiring precise angular alignment, significantly simplifying the surgical procedure and reducing operational complexity.
2Productivity
If aggressive threads are used for faster implantation, then fewer turns are required, but thread engagement precision may be compromised
Solution Approach 1:
The screw features aggressive threads with larger pitch in the distal portion for rapid bone engagement and purchase, while the proximal portion near the head maintains finer thread geometry for precise engagement and controlled advancement. This local variation in thread quality allows the screw to achieve both fast implantation and precise thread engagement simultaneously.
3Stability of the object's composition
If the screw head is designed for secure rod attachment, then stability is improved, but the profile increases impacting adjacent structures
Solution Approach 1:
The screw head employs a low-profile spherical design that provides a large surface area for rod contact and stable attachment while maintaining a compact overall volume. The spherical geometry distributes contact forces evenly, ensuring stable rod attachment without requiring a large head profile that would impinge on adjacent neural or vascular structures.
4Adaptability or versatility
If the tulip head design allows pivoting for angle adjustment, then adaptability to varying anatomy is improved, but the connection stability may be reduced
Solution Approach 1:
The tulip head incorporates a pivoting mechanism that allows dynamic adjustment to various angles during rod insertion to accommodate different anatomical configurations. Once the rod is properly positioned, a locking mechanism engages to transform the dynamic pivoting capability into a stable, fixed connection, thereby maintaining both adaptability and connection stability throughout the procedure.
Data Source
AI summary
The pedicle screw assembly includes a threaded screw extending from a tip to a head. A tulip head is coupled to the head of the screw. A hollow interior of the tulip head has a slot which receives a spine rod therein. A locking nut and preferably also a saddle and locking cap bear on the spine rod and secure the spine rod within the slot of the tulip head and against the head of the screw. The head of the screw is semi-spherical. Portions of the tulip head and structures residing within the tulip head which abut against the head are also preferably semi-spherical. The saddle and locking cap abut against the spine rod with semi-cylindrical surfaces, such that surface contact is provided against the spine rod for secure coupling of the spine rod to the pedicle screw.