Vertebral Osteotomy Saw Guide with Polyaxial Mount
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Solution Overview
Problem
Existing vertebral osteotomy techniques using thread-wire saws pose a risk to critical structures like the spinal cord, aorta, and vena cava due to the directional cutting action, which can lead to potential injuries during en bloc resections of spinal tumors.
Innovation Solution
A vertebral osteotomy saw guide featuring interdigitated pulley wheels with a 1:1 gear connection and a polyaxial mount allows the thread-wire saw to be oriented away from critical structures, using a unique tandem gear configuration to minimize friction and wear, and is securely attached to spinal instrumentation for precise osteotomy performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a thread-wire saw is used to perform osteotomy from the ventral aspect of the spinal column to the posterior aspect, then the osteotomy can be performed through the vertebral column, but the spinal cord is placed at risk as the thread-wire is drawn towards it
Solution Approach 1:
The patent inverts the traditional cutting direction by performing osteotomy from the posterior aspect of the spinal column towards the ventral aspect, rather than from ventral to posterior. This reversal ensures that the thread-wire saw moves away from the spinal cord during cutting, eliminating the risk of the wire being drawn into and injuring the spinal cord while maintaining effective osteotomy performance
2Object-affected harmful factors
If a guard (retractor) is placed between the dura and the spinal cord to protect the cord, then the spinal cord is protected during osteotomy, but the potential space is small and insertion of the retractor adds mass and places the spinal cord in potential risk
Solution Approach 1:
The patent extracts and eliminates the need for the guard (retractor) device by fundamentally changing the cutting direction. Instead of trying to protect the spinal cord with an additional device that requires insertion into a tight space, the solution removes the hazard entirely by orienting the cut so the thread-wire moves away from the spinal cord, making protective retractors unnecessary
3Strength
If the osteotomy is performed with the thread-wire cutting from the ventral aspect to the posterior aspect, then the vertebral column can be cut effectively, but the cutting action is towards the spinal cord and the dura and spinal cord are placed at risk
Solution Approach 1:
The patent applies the inversion principle by reversing the cutting direction from ventral-to-posterior to posterior-to-ventral. This maintains the effectiveness of the thread-wire saw in cutting the vertebral column while ensuring the cutting action moves away from rather than toward the spinal cord and dura, eliminating the harmful effect
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 guide effectively reduces the risk of spinal cord and vascular injuries by directing the cutting action laterally, ensuring a safer and more controlled osteotomy process, thereby minimizing morbidity and mortality associated with vertebral osteotomies.
Implementation Method 1
A vertebral osteotomy saw guide featuring interdigitated pulley wheels with a 1:1 gear connection
Implementation Method 2
A first pulley defining a channel. The channel is configured such that a threadwire can be disposed therein. A second pulley defines a channel such that the threadwire can be disposed therein
Implementation Method 3
These saws are wire saws that have industrial diamonds attached to the wire, and cutting is achieved with these diamonds as they are drawn across a surface
Data Source
AI summary
The Vertebral Osteotomy Saw Guide allows precise osteotomies to be performed through the vertebral column in conjunction with a thread-wire saw. The guide is designed so that it can mount to rods commonly used during spinal surgery for spinal stabilization. The mount of the guide is a polyaxial mount, allowing the angle of the guide mount to be adjusted and locked to create a desired cutting plane to produce a precise osteotomy. The guide itself consists of two interdigitated pulley wheels that allow the thread-wire saw to pass smoothly through the guide. The simple, but unique design of the guide allows a surgeon to perform an osteotomy through the vertebral column cutting from one side of the vertebral column to the other. This unique orientation allows the osteotomy to be performed away from critical structures in the region (the spinal cord, aorta, and inferior vena cava).