Torque-Limiting Memory Arm for Minimally Invasive Spinal Resection
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Solution Overview
Problem
Minimally invasive spinal procedures, particularly in the cervical region, face challenges due to the smaller scale of cervical vertebrae and the need for precise access and deployment of surgical tools through narrow cannulas, where existing methods struggle with the compactness and stability of resector blades within the cannula lumen.
Innovation Solution
A system comprising a handle with a rotatable torque limiting device, a shaft with a memory arm and resector blade, and a hollow sheath that allows the memory arm to be compacted and deployed within an 11 gauge cannula, enabling controlled extension and retraction of the blade for precise resection while maintaining a compact state for easy insertion and minimizing the risk of breakage or dislocation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the resector blade is made larger for effective resection, then the resection capability is improved, but the blade cannot be inserted through the narrow cannula lumen
Solution Approach 1:
The resector blade is nested within a delivery catheter in a compressed state during insertion, then deployed outward for resection. This allows the blade to pass through the narrow cannula lumen while maintaining sufficient size for effective resection once deployed.
Solution Approach 2:
The resector blade transitions from a compressed state during insertion to an extended state during resection. This dynamic transformation allows the blade to adapt its size according to the procedural requirements - compact for insertion, large for resection.
2Productivity
If the memory arm is extended for effective resection, then the resection reach is improved, but the arm is more prone to breakage or dislocation
Solution Approach 1:
The torque limiting device is pre-configured to detect and limit excessive rotational forces before they can cause arm breakage or dislocation. This protective mechanism allows the arm to be extended for resection while maintaining reliability through automated torque monitoring.
Solution Approach 2:
The torque limiting device provides real-time feedback on rotational forces applied to the memory arm. When the arm approaches its torque capacity, the device alerts the operator, allowing for controlled operation that maintains both reach and reliability.
3Object-affected harmful factors
If the cannula diameter is reduced for minimally invasive access, then the invasiveness is reduced, but the resector blade cannot be inserted or deployed
Solution Approach 1:
The resector blade is nested within a delivery catheter that passes through the narrow cannula. This nested configuration allows the blade to be delivered through minimally invasive cannula sizes while maintaining the ability to deploy a sufficiently large blade for resection.
Solution Approach 2:
The resector blade is compressed in the radial dimension during insertion through the narrow cannula, then expanded in the radial dimension for resection. This dimensional transformation enables passage through small cannulas while maintaining effective resection size.
4Ease of operation
If the resector blade is kept compact for easy insertion, then the insertion ease is improved, but the blade cannot effectively resect bone
Solution Approach 1:
The resector blade dynamically transforms from a compact configuration during insertion to an extended configuration during resection. This dynamic adaptation allows the blade to be easy to insert while maintaining resection effectiveness when deployed.
Solution Approach 2:
The blade is prepared in a compact state before insertion to facilitate easy delivery through the cannula. Once positioned, the blade is then deployed to its functional configuration for resection, separating the insertion phase from the resection phase.
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 deployment of the resector blade within the vertebral body, facilitating minimally invasive surgery by ensuring the blade remains compact during insertion and extends effectively for resection, reducing the risk of tool breakage and improving surgical precision and safety.
Implementation Method 1
a memory arm with a blade attached thereto; the memory arm compactable to a substantially co-axial position within a cannula
Data Source
AI summary
A device and method of delivering a medical tool which may be a resector, cutter, probe, or the like, including a memory arm compacted in a small diameter state which expands in a relaxed memory state, is disclosed. Said delivery may include using a hollow sheath to pre-compact or preload a memory blade into a compact position, transferring said compacted memory blade into a cannula, and deploying said memory blade from the distal end of said cannula whereby the memory blade returns to its normal expanded memory state and a deployment nut can be used to control the extension or the withdrawal of the memory arm and blade.