Dual-Torque Set Screw Tightening for Pedicle Screw Fixation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing orthopedic tools for spinal surgery face challenges in applying the right amount of torque to set screws under different circumstances, which can lead to issues like screw loosening and implant breakage.
Innovation Solution
A method and orthopedic implant kit that includes a first torque limiting mechanism for a initial torque level and a second torque limiting mechanism for a higher final torque level, ensuring precise torque application during the attachment of a spinal rod to a pedicle screw using a set screw driver.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single torque limiting mechanism is used for tightening the set screw, then the device complexity is reduced, but the manufacturing precision and reliability are compromised due to inability to apply different torque levels for different surgical conditions
Solution Approach 1:
The torque limiting mechanism is segmented into multiple independent mechanisms (first torque limiting mechanism and second torque limiting mechanism), each capable of limiting torque to a different predetermined level. This allows the system to apply different torque levels (first torque and second torque) during the tightening process, achieving precise torque control for different surgical conditions while maintaining modular device architecture
Solution Approach 2:
The system transitions from a static single torque limit to a dynamic multi-level torque control system. The torque limiting capability changes during operation, allowing the surgeon to switch between different torque levels based on the tightening stage and surgical requirements, making the device adaptable to varying operational conditions
2Reliability
If higher torque is applied to ensure secure attachment, then the reliability of the connection is improved, but the risk of implant breakage or screw loosening increases due to excessive force
Solution Approach 1:
The first torque limiting mechanism applies a lower predetermined torque level during the initial tightening phase to securely attach the set screw without risking damage. This preliminary action ensures proper engagement before the second torque limiting mechanism is engaged to apply higher torque for final securing, thereby achieving reliable connection while preventing implant damage
Solution Approach 2:
The dual torque limiting mechanisms serve as protective measures built into the system. The first torque limit acts as a cushion during initial tightening, preventing excessive force application. The second torque limit provides an additional safety layer, ensuring that even if the first limit is exceeded, the maximum torque remains controlled and safe for the implant materials
Data Source
AI summary
An orthopedic implant kit for tightening a set screw to a head of a pedicle screw for holding a spinal rod to the pedicle screw, the kit including a screw extender for holding the head of the pedicle screw, a set screw driver for engaging with the set screw to threadably tighten the set screw to the head of the pedicle screw, a first torque limiting mechanism for limiting a torque between the set screw driver and the screw extender to a first torque value or a first torque indication mechanism for indicating that the first torque has been reached, and a second torque limiting mechanism for limiting a torque between the set screw driver and the screw extender to a second torque value, the second torque value being higher than the first torque value.