Implant Rod Bending and Cutting With Compact Dual Holder Actuation
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Solution Overview
Problem
Existing bending and cutting tools for implants are large, imprecise, and require significant input force from surgeons, leading to increased fatigue and reduced rod strength due to repeated adjustments, and are not capable of bending or cutting rods that are partially implanted in patients.
Innovation Solution
A portable instrument that converts rotational input force into movement between rod holders using mechanisms like worm drive and conical gear systems, allowing for precise bending and cutting of implants near the surgical site with reduced surgeon effort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If existing bending and cutting tools are used, then the rod can be bent or cut, but the tools are very large and cannot be used near the patient, requiring multiple trips between the patient and back table
Solution Approach 1:
The bending and cutting functions are segmented into separate, compact modules that can be attached to the rod at different stages. The bending device includes rollers and forming mechanisms that can be applied distally, while cutting tools can be attached proximally, allowing sequential operations near the patient without requiring a single large device.
Solution Approach 2:
The instrument delivers bending and cutting capabilities through a minimally invasive access path, transitioning from the traditional back table approach to a percutaneous delivery method. This dimensional change allows the tools to reach the rod at the surgical site through small incisions, eliminating the need for large external equipment.
2Ease of operation
If existing bending tools are used, then the rod can be bent, but significant input force from the surgeon is required, increasing surgeon fatigue
Solution Approach 1:
The manual bending mechanism is replaced with a self-contained actuation system that uses a motor or spring-loaded mechanism to generate the bending force. The surgeon simply activates the device, which then automatically applies the necessary force to form the rod to the desired shape, eliminating the need for the surgeon to manually apply significant force.
Solution Approach 2:
The bending device is designed to be self-actuating, where the instrument itself generates and applies the bending force without requiring continuous manual input from the surgeon. The device includes its own power source or energy storage mechanism that performs the work, allowing the surgeon to simply guide and control the process rather than provide the physical effort.
3Manufacturing precision
If existing bending tools are used, then the rod can be bent through iterative adjustments, but the tools lack precision, increasing the number of adjustments needed and reducing rod strength
Solution Approach 1:
The bending device incorporates sensors and control systems that provide real-time feedback on the rod's position and shape during the bending process. This allows the device to automatically adjust and refine the bending to achieve the precise desired geometry in a single operation, eliminating the need for repeated iterative adjustments that would compromise rod strength.
Solution Approach 2:
The imprecise manual bending mechanism is replaced with a controlled actuation system that uses motors, servos, or programmable mechanisms to apply precise bending forces. The device can be programmed with the exact bending parameters and can execute them with high accuracy, achieving the desired rod shape in one precise operation rather than multiple approximate adjustments.
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 instrument enables quicker, more precise, and efficient bending and cutting of implants with reduced surgeon fatigue and improved rod strength by allowing for precise control and fewer iterations, while being compact enough to be used near the patient.
Implementation Method 1
The gear can include a worm gear and the drive shaft can include a worm screw configured to rotate the worm gear when the drive shaft rotates
Implementation Method 2
The gear can include a first conical gear and the drive shaft can include a second conical gear enmeshed with the first conical gear
Implementation Method 3
The first rod holder can include a main roller and a secondary roller configured to orbit the main roller when the gear rotates
Data Source
AI summary
Devices and methods for bending or cutting implants are disclosed herein. In some embodiments, an instrument can convert a rotational input force (e.g., supplied by a powered driver tool) into movement of a first rod holder with respect to a second rod holder. Such movement can form a bend in a rod or other implant held by the first and second rod holders. Various mechanisms for converting this movement are disclosed, such as a worm drive mechanism and a conical gear mechanism, as are various types of rod holders, including orbiting rollers, lid-type rod holders, fixed and pivoting half-pipe rod holders, and full-pipe rod holders. In some embodiments, the instrument can also be used for cutting, for example by rotating a cutting wheel with respect to a cutting plate to cut a rod or other implant inserted through openings formed in the cutting wheel and the cutting plate.