Spinal Rod Connector Single-Step Locking Mechanism
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Solution Overview
Problem
Existing spinal rod connector assemblies for vertebral bone screws lack a simple and efficient mechanism for securing spinal rods, requiring multiple steps and compromising operative time and flexibility during spinal surgery.
Innovation Solution
A spinal rod connector assembly that provides a single-step lock-up mechanism allowing 360° rotation of the spinal rod, utilizing a combination of V-shaped components, a pull-up ring, locking ring, rod clamp, collet, and drive nut to securely attach the spinal rod to the vertebral bone screw through axial movement and tapered surfaces, enabling easy assembly and adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a multi-step locking mechanism is used in spinal rod connector assemblies, then the spinal rod can be securely attached to the vertebral bone screw, but the operative time increases and surgical efficiency decreases
Solution Approach 1:
The connector assembly is pre-assembled with the spinal rod and locking mechanism already in place before surgery. The pre-assembled unit requires only a single insertion and locking action during surgery, eliminating the need for multi-step assembly procedures in the operating room and thereby reducing operative time while maintaining secure attachment.
Solution Approach 2:
The connector assembly merges multiple functional components (rod holder, locking mechanism, vertebral bone screw interface) into a single integrated unit. This consolidation allows the assembly to be installed as one piece with a single locking action, reducing the number of surgical steps required while ensuring reliable securing of the spinal rod.
2Strength
If a complex locking mechanism is used to secure the spinal rod, then the attachment strength is improved, but the device complexity increases making assembly more difficult
Solution Approach 1:
The locking mechanism is segmented into distinct functional elements (locking arm, engagement surface, spring, and handle) that work together through a simple sequential motion. This segmentation allows each component to perform its specific function efficiently while keeping the overall assembly simple to operate and install, avoiding unnecessary complexity.
Solution Approach 2:
Instead of requiring complex multi-step procedures to achieve secure attachment, the design inverts the approach by using a simple single-action locking mechanism that achieves strong attachment through an elegant mechanical advantage system, where a small input force applied through the handle generates sufficient locking force through the spring-loaded arm.
3Productivity
If the spinal rod connector assembly is designed for pre-assembly, then operative time is decreased, but the adaptability for individual case customization is reduced
Solution Approach 1:
The connector assembly incorporates adjustable elements that allow dynamic customization after insertion. The spinal rod can be rotated to different angular positions, and the locking mechanism can be adjusted to accommodate varying rod diameters and configurations. This dynamic adjustability maintains pre-assembly benefits while preserving the ability to customize for individual patient requirements.
Solution Approach 2:
The connector assembly is designed with universal features that can accommodate multiple spinal rod configurations and patient-specific requirements. The adjustable locking mechanism and rotational capability allow a single pre-assembled unit to serve multiple functions and adapt to different surgical scenarios, maintaining versatility without requiring custom assembly for each case.
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
Facilitates quick and secure attachment of spinal rods to vertebral bone screws with 360° rotation, reducing operative time and enhancing surgical flexibility by providing a pre-assembled, bio-compatible solution that locks the spinal rod in place effectively.
Implementation Method 1
The locking nut cooperates with the pull-up ring though tapered surfaces of the pull-up ring and the locking nut to achieve spinal rod fixation. Axial constraint of the locking nut by the head causes axially downward movement of the locking nut to make the outer tapered surface of the locking nut contact the inner tapered surface of the pull-up ring to pull the pull-up ring transverse to the longitudinal axis of the drive nut
Implementation Method 2
a drive nut configured for threaded reception in an upper threaded bore of the head, wherein axial movement of the drive nut into the pull-up ring causes the pull-up ring to move inward
Data Source
AI summary
A spinal rod connector provides single step locking of a spinal rod relative to a bone screw. The single step lock-up is in line with the vertebral bone screw while still allowing for effectively 360° of rotation of a portion of the spinal rod connector assembly with the spinal rod (but functionally 180° or +/−90° of the 0° position depicted in the various figures). The present spinal rod connector assembly utilizes components having V-shapes of various angles to provide holding of the spinal rod. A pulling and compression force locks the spinal rod onto the spinal rod connector and thus relative to the vertebral bone screw to which the spinal rod connector assembly is attached. The present spinal rod connector allows easy sliding down on guides of the spinal rod connector assembly since spinal rod rotation locks up from the rod being pulled towards the vertebral bone screw.