Ratchet Rod Bender Gear Train for High-Force Spinal Rod Contouring
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional rod benders are limited in their ability to achieve large bending forces or displacements, making it difficult to shape spinal rods made from high-strength materials.
Innovation Solution
The development of ratchet-style rod bender instruments that utilize a gear train with compound gears and a ratchet wheel, driven by a single actuator handle, to symmetrically move bending elements and apply greater bending force and displacement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If conventional French rod benders are used to bend spinal rods, then the device structure remains simple, but the bending force and displacement are insufficient for high-strength materials
Solution Approach 1:
A gear train mechanism is introduced as an intermediary between the actuator handle and the bending elements. This gear train includes a ratchet wheel and multiple compound gears that transmit and amplify the force applied by the user, providing significant mechanical advantage to bend high-strength spinal rods while maintaining a manageable device structure
Solution Approach 2:
The design transitions from a direct linear force application in conventional benders to a rotational dimension through the ratchet wheel and gear train. The actuator handle rotates the ratchet wheel, which drives the compound gears to move the bending elements, adding a rotational dimension that enables greater force multiplication and displacement control
2Strength
If high-strength materials are used for spinal rods, then implant strength and durability are improved, but the force required to bend the rod increases beyond conventional bender capabilities
Solution Approach 1:
The gear train mechanism changes the force parameters by providing significant mechanical advantage. The compound gears with different tooth counts transform the input force from the actuator handle into a multiplied output force at the bending elements, enabling the bending of high-strength materials that would otherwise require excessive force
Solution Approach 2:
The ratchet wheel configuration allows for multiple actuator handle movement cycles to achieve the desired bending. Each cycle of handle movement advances the gears incrementally, applying periodic force that accumulates to achieve the total bending force and displacement needed for high-strength implants
3Power
If a gear train with compound gears is used to increase bending force, then mechanical advantage is significantly improved, but the device complexity increases
Solution Approach 1:
Multiple compound gears are merged into a single integrated gear train system that is driven by one actuator handle. The ratchet wheel connects to the first compound gear, which is engaged with the second compound gear, combining multiple force multiplication stages into a unified mechanism that provides significant mechanical advantage without requiring separate actuation systems
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 ratchet-style rod bender instruments provide a significant mechanical advantage, allowing for greater rod bending force and displacement, and enabling the shaping of implants made from materials that were previously too strong for conventional benders.
Implementation Method 1
the gear train can provide significant mechanical advantage and the ratchet wheel configuration can allow for multiple actuator handle movement cycles, thereby enabling greater rod bending force and displacement relative to conventional French-style rod bending tools
Implementation Method 2
a gear train having a plurality of compound gears that can be driven by a ratchet wheel using one or more movements of the actuator handle
Implementation Method 3
the gear train can provide significant mechanical advantage and the ratchet wheel configuration can allow for multiple actuator handle movement cycles
Implementation Method 4
bending the rod... Movement of the actuator handle relative to a housing of the rod bender can rotate the ratchet wheel, thereby driving the plurality of compound gears to move the bending elements and bend an implant received within an implant-receiving channel
Data Source
AI summary
Implant bending instruments disclosed herein can have a plurality of bending elements that can be symmetrically driven to bend or contour an implant, such as a spinal rod. A single actuator handle can be moved to drive a compound gear train and move the bending elements to intersect an implant-receiving channel and bend an implant received therein. Instruments of the present disclosure can have an increased mechanical advantage than conventional bending instruments thereby allowing for an increased amount of force to bend an implant. A locking pawl can selectively prevent counter rotation of the gear train such that the handle can be actuated a plurality of times to achieve a desired contour angle.