Spine Rod Cutter With Chip Capture for In-Situ Length Adjustment
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Solution Overview
Problem
Current surgical protocols require multiple surgeries and are time-consuming and costly due to the difficulty in precisely determining the length of spine rods before implantation, necessitating an efficient method to adjust the length of implanted spine rods in-situ.
Innovation Solution
A cutter device comprising a handle, drill guide, mill, and catch cup, designed for in-situ cutting of spine rods, featuring an hourglass-shaped handle, stippling or texturing, and a mill with a helical transport groove to maintain chip removal, allowing for precise cutting and efficient chip management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the spine rod length is determined before surgery, then the implant can be prepared in advance, but the precision of length determination is difficult or impossible to predict
Solution Approach 1:
The cutter device is prepared and assembled before surgery with all components (handle, drill guide, mill, catch cup) ready for immediate use. The drill guide is pre-configured with the appropriate diameter to match the specific spine rod, allowing the surgeon to perform precise in-situ cutting without needing to predict the exact final length beforehand.
2Manufacturing precision
If the spine rod is removed, cut off-site, and re-implanted, then the length can be precisely adjusted, but the procedure becomes time-consuming and requires multiple surgeries
Solution Approach 1:
The cutting function is extracted from the implant itself and performed in-situ using a dedicated cutter device. The mill removes material directly from the spine rod at the surgical site, eliminating the need to extract the entire implant for off-site modification. This allows precise length adjustment while maintaining surgical continuity.
Solution Approach 2:
The cutter device serves as an intermediary tool between the spine rod and the surgeon's cutting action. It provides controlled, precise material removal through the mill while the catch cup manages chips, enabling accurate in-situ length adjustment without removing the implant.
3Device complexity
If a simple cutting tool is used, then the device complexity is reduced, but chip management becomes problematic during surgery
Solution Approach 1:
The catch cup is integrated with the drill guide to form a unified chip management system. The catch cup circumscribes the drill guide and collects chips generated during cutting, while the drill guide's windows allow chips to be contained and subsequently removed as a unit. This merging of functions provides effective chip management without significantly increasing overall device complexity.
4Ease of operation
If the mill rotates freely in the handle coupler, then the cutting action is smooth and controlled, but precise positioning and depth control are challenging
Solution Approach 1:
The handle coupler is designed with a central bore that provides a specific geometric relationship with the mill. This localized structural feature, combined with the drill guide's positioning, creates natural depth stops and alignment references that enable precise cutting depth control while maintaining smooth mill rotation.
Data Source
AI summary
A cutter for cutting an implant is provided. The cutter includes a handle; a handle coupler coupled to the handle; a drill guide coupled to the handle coupler and including at least one window; a mill extending through the handle coupler and the drill guide and disposed to rotate freely therein; and a catch cup circumscribing the drill guide to maintain chips of the implant removed by the mill.