Spinal Fixation Rod Bending Lever for One-Handed Control
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Solution Overview
Problem
Conventional hand-operated instruments for bending spinal fixation rods, such as French benders, require significant force and often lead to awkward hand positioning, making it difficult for physicians to apply the correct force and maintain control, especially when bending rods made of materials like titanium.
Innovation Solution
A medical hand-driven bending instrument featuring a handle with a movable carriage and lever system, including a pawl mechanism that engages with ratchet teeth or a friction surface, allowing for controlled bending of the rod with reduced manual effort and improved ergonomics, enabling the physician to view the bending process without rotating their wrist.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a hand-operated French bender is used to bend spinal fixation rods, then bending capability is achieved, but significant manual force is required and awkward hand positioning occurs
Solution Approach 1:
The instrument introduces a lever arm extending perpendicular to the handle axis, transforming the bending operation from a direct hand-squeezing action into a rotational lever action. This dimensional change allows the physician to apply force in a more ergonomic orientation while generating sufficient bending moment through the lever arm mechanism.
Solution Approach 2:
The instrument introduces a lever arm as an intermediary between the physician's hand and the rod-bending action. This lever arm mediates the force application, allowing the physician to apply force at a convenient location while the lever mechanism transmits and amplifies this force to the rod, eliminating the need for direct hand positioning at the bending point.
2Force
If both hands are used to operate the French bender, then adequate bending force is applied, but the physician cannot use a free hand for manipulating the rod
Solution Approach 1:
By extending the lever arm perpendicular to the handle, the instrument allows the physician to apply bending force with one hand in a rotational motion, freeing the other hand for rod manipulation. This dimensional reconfiguration transforms a two-handed squeezing operation into a one-handed lever operation.
3Loss of information
If the physician rotates their hand to view the rod curve during bending, then the changing curve can be observed, but the appropriate amount of force cannot be applied or slippage occurs
Solution Approach 1:
The lever arm acts as an intermediary that decouples the physician's hand position from the rod bending location. The physician can maintain a stable, ergonomic hand position on the lever grip while the lever mechanism transmits force to the rod, allowing continuous visual monitoring of the rod curve without compromising force application or causing slippage.
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 facilitates precise and efficient bending of spinal fixation rods by providing a mechanical advantage and improved ergonomics, allowing for effective bending of rods with reduced slippage and increased control, enhancing the surgical process.
Implementation Method 1
a row of ratchet teeth or a friction surface which row or surface extends along the other side of the carriage in the longitudinal direction of the handle
Implementation Method 2
a pawl pivotably connected to the lever in its lever effector portion and having a meshing tooth or a friction lining at its one free end portion being prepared to interact with the row of ratchet teeth or friction surface
Implementation Method 3
a lever provided with a lever grip portion and with a lever effector portion
Implementation Method 4
allowing for controlled bending of the rod with reduced manual effort
Data Source
Figure 1
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AI summary
An instrument for bending a surgical implant about a bending axis includes a handle defining a receiving area for receiving the surgical implant. A lever is pivotably connected to the handle about a pivot axis that can be orthogonal to the bending axis. A movable linkage can be connected to the lever for movement with the lever. The moveable linkage can be configured to bend the surgical implant about the bending axis upon pivoting the lever about the pivot axis.