Spinal Rod Reducer Levers for Seating Fixation
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Solution Overview
Problem
Current spinal fixation systems face difficulties in aligning and seating rods within rod-receiving portions of spinal implants due to the rigidity and variability of vertebral structures, necessitating the use of rod reducers to facilitate the process.
Innovation Solution
The development of a rod reducer with a gripping assembly and a rod reducing assembly, featuring levers that pivot to translate the rod reducing assembly distally, allowing for easy seating of the rod into the spinal implant, along with a lock/release mechanism for secure fixation, and an inline-style reducer with a locking sleeve for enhanced mechanical advantage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If traditional rod reducers are used to seat spinal rods, then rod alignment and seating can be achieved, but the process requires significant force and time, increasing surgical complexity and duration
Solution Approach 1:
The rod reducer employs dynamic lever arms that can be adjusted in length to provide variable mechanical advantage. The levers pivot about an axis to convert rotational motion into linear displacement, allowing the rod to be pushed distally with reduced manual force requirements while maintaining control over the seating process
Solution Approach 2:
The device is divided into distinct functional modules: a gripping assembly for holding the implant, a rod reducing assembly with levers for applying force, and a locking mechanism for securing the rod. This segmentation allows each component to be optimized independently and facilitates easy cleaning and sterilization by disassembly
2Manufacturing precision
If force is applied to seat the rod into the rigid vertebral structure, then proper fixation is achieved, but the rigidity of the vertebrae and variability in shape make alignment difficult, requiring repeated adjustments
Solution Approach 1:
The rod reducer acts as an intermediary device between the surgeon's hands and the rigid vertebral structure. The gripping assembly provides a stable interface with the implant, while the lever system translates and amplifies applied force in a controlled manner, bridging the gap between manual operation and the rigid target structure
Solution Approach 2:
The lever arm lengths can be adjusted to change the mechanical advantage parameter, allowing optimization of force application based on the specific implant geometry and vertebral characteristics. This parameter adjustment enables adaptation to varying surgical conditions without requiring repeated trial-and-error adjustments
3Reliability
If complex locking mechanisms are added to secure the rod, then fixation reliability is improved, but device complexity increases, making cleaning and sterilization more difficult
Solution Approach 1:
The locking mechanism is designed as a separate, modular component that can be independently assembled and disassembled from the lever system. This segmentation maintains the reliability of the fixation while enabling complete disassembly of all components for thorough cleaning and sterilization, eliminating the trade-off between reliability and ease of maintenance
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
The rod reducers enable efficient and force-reducing rod seating, reducing surgical time and expense, and can be easily disassembled for cleaning and sterilization, facilitating rapid and precise spinal rod placement across multiple vertebral levels.
Implementation Method 1
The first lever can be pivotally coupled to the proximal end of the gripping assembly. The second lever can be pivotally coupled to the first lever and the proximal end of the rod reducing assembly. Movement of the first lever and the second lever towards one another can cause the first and second levers to pivot about the proximal end of the gripping assembly.
Implementation Method 2
The distal end of the rod reducing assembly can be configured to engage a rod. Movement of the first and second lever towards one another can also cause the rod reducing assembly to translate distally relative to the gripping assembly, thereby pushing a rod distally into a rod-receiving portion of a spinal implant held by the gripping assembly.
Data Source
AI summary
Kerrison-style rod reducers, inline-style rod reducers, and related methods of using the disclosed rod reducers for holding a spinal implant and seating a fixation rod in a rod-receiving portion of the spinal implant are provided for herein. The disclosed rod reducers can also be configured for applying a set screw or other closure mechanism to secure the rod within the rod-receiving portion of the spinal implant. The disclosed embodiments can be easy to use, not require significant force to operate, and be efficient, thereby reducing the time and expense necessary to perform spinal surgery. The disclosed rod reducers can be readily dissembled, thereby making these surgical instruments easy to clean and sterilize.