Vertical Cutter with Deflecting Blade for Spinal Disc Preparation
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Solution Overview
Problem
Existing cutting devices for spinal disc space preparation in minimally invasive surgery are limited by their rotational cutting mechanism, which makes it difficult to achieve the necessary vertical reach and can result in broken blades and metal fragments, especially in larger patients.
Innovation Solution
A vertical cutter with a single, inclined cutting blade made from shaped memory alloy, designed to deflect into a cylindrical tube for insertion and extraction, allowing for linear cutting and scraping of disc material without rotational motion, enabling greater vertical reach and reducing the risk of blade breakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If rotational cutting devices are used, then disc material can be removed, but vertical reach is limited and blade breakage risk increases
Solution Approach 1:
The patent inverts the conventional rotational cutting approach by implementing a linear reciprocating cutting motion. The cutting blade moves vertically in a straight line between the vertebral bodies rather than rotating, which eliminates the structural weaknesses of rotational blades while achieving the same disc material removal function. This inversion allows for greater vertical reach and eliminates blade breakage associated with rotational mechanisms.
Solution Approach 2:
The cutting blade is designed as a separate, removable component that can be independently replaced if damaged. This segmentation allows the blade to be optimized for linear cutting without compromising the overall device structure, and enables easy replacement rather than replacing the entire device, thus improving reliability.
2Ease of operation
If multiple separate cutting blades are used, then cutting function is improved, but device complexity increases and deflection into tube becomes difficult
Solution Approach 1:
The patent merges the cutting function into a single integrated cutting blade that performs all necessary cutting actions through linear reciprocating motion. This eliminates the need for multiple separate blades and their associated complexity, while the blade's design with cutting edges on opposite sides allows it to effectively perform the work of multiple blades through its back-and-forth motion.
Solution Approach 2:
The cutting blade is designed with flexible properties that allow it to dynamically deflect into the narrow access tube for insertion and then extend outward for cutting. The blade's dynamic behavior - transitioning from a compressed flexible state during insertion to an extended rigid state during cutting - enables simplified single-blade design while maintaining ease of operation.
3Ease of operation
If cutting blade is made flexible to deflect into tube, then insertion is enabled, but blade strength is reduced and breakage risk increases
Solution Approach 1:
The cutting blade exhibits dynamic mechanical properties, being flexible enough to deflect into the narrow access tube during insertion but rigid enough to perform cutting when extended. This dynamic behavior is achieved through careful material selection and geometric design that allows the blade to transition between flexible and rigid states based on operational requirements.
Solution Approach 2:
The blade's effective stiffness is changed through its position and configuration - flexible during insertion when deflected into the tube, and rigid during cutting when extended outward. This parameter change allows the blade to satisfy both contradictory requirements of flexibility for insertion and strength for cutting without compromise.
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 vertical cutter efficiently prepares the spinal disc space for fusion implant devices by allowing for greater vertical reach and safer operation, reducing the risk of blade breakage and metal fragments, and improving bone surface preparation for fusion implant devices.
Implementation Method 1
The cutting blade has a cutting edge, a portion of which when extended free of the cylinder or tube will extend a distance greater than the tube outside diameter. The cutting edge when pushed inwardly and pulled outwardly between adjacent vertebrae scrapes and cuts disc material. When retracted the cutting blade deflects into the cylinder or tube for insertion or extraction into or from the disc space.
Data Source
AI summary
A detachable vertical cutter for insertion into a cylinder or tube is formed as a single unitary structure. The single blade has a pair of tool attachment end portions and a cutting blade extending in a loop between the attachment ends. The cutting blade is inclined vertically relative to a longitudinal axis of a cylinder or tube into which the attachment ends can slide into. The cutting blade has a cutting edge, a portion of which when extended free of the cylinder or tube will extend a distance greater than the tube outside diameter. The cutting edge when pushed inwardly and pulled outwardly between adjacent vertebrae scrapes and cuts disc material. When retracted the cutting blade deflects into the cylinder or tube for insertion or extraction into or from the disc space.