Spinal Rod Pusher Instrument with Nested Shaft Roller Mechanism
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Solution Overview
Problem
In minimally invasive spinal surgeries, accurately and precisely placing a stabilization rod within vertebral anchors is challenging due to the small incisions used, requiring in situ adjustment of the rod to achieve proper alignment and fixation.
Innovation Solution
A rod pusher instrument comprising an outer shaft, inner shaft, roller, and actuator, where the roller engages the fixation rod to impart linear movement, allowing for precise adjustment and locking of the rod within the vertebral anchors, utilizing a friction-enhancing surface and serrated design to facilitate controlled rod displacement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a minimally invasive surgical approach is used with small incisions, then patient trauma and recovery time are reduced, but accurate and precise placement of the stabilization rod within vertebral anchors becomes difficult
Solution Approach 1:
The instrument employs a nested structure where an inner shaft is disposed within an outer shaft, both extending through the small surgical incision. The inner shaft can move independently within the outer shaft to provide precise rod advancement while the outer shaft maintains stable positioning through the incision site, enabling accurate rod placement despite minimal access.
Solution Approach 2:
A roller mechanism acts as an intermediary between the surgeon's manual input and the fixation rod. The roller engages with the rod and converts rotational motion into precise linear advancement, providing controlled rod placement through the constrained access of minimally invasive surgery.
2Object-affected harmful factors
If the rod is inserted through small incisions in minimally invasive surgery, then surgical invasiveness is reduced, but in situ adjustment of the rod becomes necessary to achieve proper alignment
Solution Approach 1:
The adjustment mechanism utilizes nested shafts where the inner shaft moves within the outer shaft. This compact nested design enables complex adjustment functionality (advancement, retraction, positioning) through a small profile that can pass through minimal incisions, avoiding the need for larger open surgical approaches.
Solution Approach 2:
The roller mechanism provides self-contained adjustment capability directly at the rod insertion site. The instrument can advance, retract, and position the rod in situ without requiring removal through the incision or additional surgical exposure, allowing the system to service itself through the constrained access.
3Manufacturing precision
If the roller engages the fixation rod to impart linear movement, then precise rod adjustment is achieved, but friction between the roller and rod must be carefully controlled
Solution Approach 1:
The roller mechanism transitions between different engagement states dynamically. During advancement, the roller engages the rod with sufficient friction to transmit driving force. During retraction or repositioning, the engagement can be reduced or released. This dynamic control of friction enables precise bidirectional adjustment without requiring excessive force in either direction.
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 precise and controlled advancement and locking of the fixation rod within the vertebral anchors, improving the accuracy and efficiency of spinal rod placement during minimally invasive surgeries, addressing the challenges of rod alignment and stabilization.
Implementation Method 1
The roller rotatably is coupled with the distal end at an axis and configured to engage the fixation rod. The actuator operably couples with the inner shaft to translate the inner shaft within the lumen and cause rotation of the roller to impart linear movement on the fixation rod.
Data Source
AI summary
The instruments and methods of the present disclosure include an outer shaft, an inner shaft, a roller, and an actuator. In some examples, the outer shaft includes a lumen extending from a proximal end to a distal end. The inner shaft is disposed within the lumen. The roller rotatably is coupled with the distal end at an axis and configured to engage the fixation rod. The actuator operably couples with the inner shaft to translate the inner shaft within the lumen and cause rotation of the roller to impart linear movement on the fixation rod.