Rod Reduction Assemblies with Screw-Driven Anchor Disengagement
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Solution Overview
Problem
Existing rod reduction instruments for spinal fixation constructs are bulky, time-consuming, and difficult to disengage from anchors, especially in limited surgical access, and often fail to provide sufficient reduction depth and force.
Innovation Solution
A dual rod spinal fixation system with a rod reducer featuring a translation unit and coupling unit, including a drive knob and attachment arms, allows for efficient seating and disengagement of a spinal rod into a fixation anchor, utilizing a lock mechanism for controlled reduction and easy detachment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If traditional rod reduction instruments are used to provide stable interaction with the anchor during reduction, then reduction stability is improved, but device complexity and ease of operation deteriorate due to bulky structure and difficulty in disengagement
Solution Approach 1:
The reduction instrument is divided into distinct functional segments: a coupling unit with anchor engagement features, a lock mechanism with drive knob, and a translation unit with rod engagement features. This segmentation allows each component to perform its specific function independently while maintaining overall stability during reduction, and facilitates easier disengagement by allowing individual components to be manipulated separately.
Solution Approach 2:
The instrument incorporates dynamic elements including rotatable attachment arms that can pivot between engaged and disengaged positions, a translatable pusher member that moves along the rod, and a rotatable drive knob that converts rotational motion to linear displacement. These dynamic features enable the instrument to adapt to different reduction force requirements and facilitate easy release from the anchor by reversing the engagement sequence.
2Manufacturing precision
If reduction force requirements are increased to achieve sufficient rod seating in misaligned vertebrae, then reduction depth is improved, but device complexity and ease of operation worsen due to need for bulky structures
Solution Approach 1:
The instrument replaces bulky mechanical leverage structures with a compact screw mechanism. The drive knob with threaded engagement converts rotational input into precise linear displacement of the pusher member, generating high reduction forces in a compact package. This eliminates the need for large lever arms or complex mechanical advantage systems while achieving sufficient reduction depth for misaligned vertebrae.
3Manufacturing precision
If reduction time is extended to ensure proper rod alignment and seating, then reduction precision is improved, but productivity deteriorates due to time-consuming procedures
Solution Approach 1:
The instrument is pre-configured with the rod engaged in the pusher member before approach to the anchor, and the attachment arms are pre-positioned for immediate engagement with the anchor features. This preliminary setup eliminates time-consuming adjustments during the reduction process, allowing the surgeon to simply activate the lock mechanism and begin reduction immediately, thus maintaining high precision while improving productivity.
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 simple and efficient rod manipulation during spinal fixation, enabling quick alignment and secure engagement/disengagement of the rod within anchors, even in constrained surgical environments.
Implementation Method 1
a lock mechanism with a drive knob, where the drive knob has a groove along the distal edge of an interior surface and a pair of apertures on opposite sides of the knob with a drive pin passing through and into the lumen to engage the helical grooves of the base member
Implementation Method 2
a pair of multi-pitch helical grooves arranged on opposite sides of the base member
Data Source
AI summary
This disclosure describes example embodiments of rod reduction instrumentation and other rod and vertebrae manipulation instruments. The rod reducers can be used during the installation of a rod based surgical fixation system to help urge the rod into the fixation anchors. The reducers described provide various configurations delivering large reduction distance capabilities, strong controlled reduction coupled with an ability to quickly advance the reducer if desired, and reduction of bulk through the surgical corridor.