Dual Tulip Assembly for Polyaxial Rod Alignment
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Solution Overview
Problem
Current spinal surgical procedures face challenges in securely attaching tulip assemblies to bone screws, especially when fixing multiple vertebrae segments, as existing devices require bending rods or custom fitting, which can be cumbersome and insecure without clear visual confirmation of proper attachment.
Innovation Solution
A dual tulip assembly with a single bone screw and two tulips, featuring a saddle with arcuate fingers that flex to secure the screw head, allowing for secure attachment and alignment of two rods without the need for bending, using a single piece structure that accommodates two rods and a bone screw with a hemispherical or spherical head.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single bone screw is used to attach two rods to multiple vertebrae segments, then the number of components and surgical steps is reduced, but the complexity of the tulip structure increases to accommodate two rods
Solution Approach 1:
The patent combines two separate tulip structures into a single integrated dual tulip assembly that can accommodate two rods simultaneously. The shared bone screw head with multiple attachment points merges the function of two separate screws, reducing component count while maintaining the capability to secure two rods to multiple vertebrae segments
Solution Approach 2:
The dual tulip structure serves multiple functions: it can accommodate two separate rods, allow for polyaxial inclination adjustments for each rod, and secure multiple vertebrae segments simultaneously. The bone screw head is designed with universal attachment features that can interface with both tulips and accommodate various rod configurations
2Ease of operation
If the tulip assembly is designed to fit down onto the projecting screw head without clear path of vision, then the initial screw placement flexibility is maintained, but the ability to confirm proper attachment is compromised
Solution Approach 1:
The tulip structure incorporates visual feedback mechanisms such as visible alignment features, engagement indicators, and transparent or semi-transparent components that allow the surgeon to confirm proper attachment of the tulip to the bone screw head even when direct line of sight is limited. The mechanical engagement of the set screw with the bone screw head provides tactile and visual confirmation of secure attachment
3Adaptability or versatility
If a bent rod or custom fitting is required for long spans fixing three vertebrae segments, then the fit to patient anatomy is improved, but the surgical procedure complexity and time increase
Solution Approach 1:
The dual tulip assembly incorporates adjustable and dynamic features that allow the rods to be positioned at various angles and orientations to accommodate different anatomical configurations. The polyaxial inclination capability of the bone screw and tulip structure enables adaptation to patient-specific anatomy without requiring pre-bending of rods or custom fitting, allowing for intraoperative adjustment to achieve optimal anatomical fit
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 secure and customizable attachment of rods to multiple vertebrae segments using a single bone screw, ensuring stability and ease of assembly by allowing for angular alignment and secure locking without additional components, improving surgical efficiency and reducing the need for custom rod bending.
Implementation Method 1
The plurality of arcuate fingers collectively are larger in diameter than the tapered end annular opening of the first tulip. Upon insertion of the dual tulip, the first tulip moves over the head of the bone screw. The saddle moves proximally over the head simultaneously causing the arcuate fingers to flex and move past a maximum diameter of the head holding the head in the complimentary shaped interior receiving chamber of the first tulip.
Implementation Method 2
The recess of the first tulip has a conical surface tapering inward distally, the conical surface compresses the plurality of arcuate fingers when tightening the set screw.
Implementation Method 3
The bone screw has at least a partially hemispherical head. The bone screw has one of the following head shapes; at least partially a hemispherical or spherical head, or any other bulbous head. This ability is often used in devices having a modular head assembly.
Data Source
AI summary
A dual tulip assembly has a bone screw and a dual tulip. The dual tulip has a first tulip and a second tulip. Each first and second tulip has a slotted opening for receiving a rod. Each tulip is defined by a pair of sides, one side being common to both first and second tulips. On each side of each slotted opening, the sides have a proximal end with threads for engaging a set screw to secure a rod. The first tulip has an annular tapered distal end with an opening for receiving and securing the bone screw. The second tulip has a base forming a closed distal end. The bone screw has at least a partially hemispherical head. The bone screw has one of the following head shapes; at least partially a hemispherical or spherical head, or any other bulbous head. The dual tulip is a single piece structure.