Orthopedic Impactor Lever Arm Thread Damage
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Solution Overview
Problem
Conventional orthopedic cup impactors risk damaging the acetabular cup's threads during impaction due to the transfer of impaction forces, leading to potential disconnection of the surgical implant from the tool.
Innovation Solution
A spindle-type orthopedic impactor with a connection rod that minimizes contact with the impactor body's inner surface, utilizing a lever arm subassembly and ratchet locking mechanism to securely engage and position the prosthetic cup, distributing impaction forces effectively and preventing damage to the cup's connection mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the connection rod is threaded to engage the cup, then secure engagement is achieved, but the threads are damaged by impaction forces causing disconnection
Solution Approach 1:
The device is divided into distinct functional segments: the impactor body for delivering impact forces, the connection rod for transmitting forces, and the cup for implantation. This segmentation allows each component to be optimized for its specific function, with the connection rod designed to minimize contact with the impactor body's inner surface, thereby reducing thread damage during impaction while maintaining secure engagement.
Solution Approach 2:
The connection rod acts as an intermediary element between the impactor body and the cup. By minimizing contact between the connection rod and the impactor body's inner surface, the design reduces the transmission of harmful impaction forces to the threaded engagement interface, thereby protecting the threads from damage while still allowing effective force transmission to the cup.
2Strength
If the connection rod contacts the impactor body's inner surface, then structural support is provided, but impaction forces damage the cup's connection mechanism
Solution Approach 1:
The connection rod is designed with specific local characteristics: it minimizes contact with the impactor body's inner surface along its length. This localized quality control ensures that impaction forces are not transmitted through contact points that could damage the cup's connection mechanism, while still maintaining adequate structural support for force transmission.
3Measurement precision
If the lever arm subassembly is used to position the cup, then precise positioning is achieved, but device complexity increases
Solution Approach 1:
The lever arm subassembly introduces dynamic adjustability to the impactor device. The lever arm can be positioned at different locations along the connection rod, allowing dynamic adjustment of the cup's positioning during the surgical procedure. This dynamic capability enables precise positioning while keeping the overall device design relatively simple through modular construction.
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 design ensures secure fixation and minimal damage to the prosthetic cup during impaction, allowing for precise positioning and easy disassembly, while preventing component misplacement and facilitating thorough cleaning.
Implementation Method 1
a ratchet locking mechanism (126) engaged to secure the lever arm subassembly (106) in the second position
Implementation Method 2
a spring (114) residing between the strike plate (58) and the proximal ring (94) biased away from the strike plate (58)
Implementation Method 3
The wedge portion (122) of the lever arm (108) is positioned such that the angled end of the wedge (122) is positionable between the distal ring (96) and the distal end of the handle portion (64). As the lever arm (108) is depressed, the wedge portion (122) moves the handle portion (64) along a longitudinal axis (A-A)
Data Source
Figure 1
Figure 2~2A
Figure 3
AI summary
An orthopedic impactor device (50) for positioning an orthopedic prosthetic cup implant during a hip replacement surgery is described. The impactor is designed with a "one piece" elongated body portion (60), having a distal prosthetic cup engagement portion (66) which is separated from a proximal strike plate (58) by an annular sidewall (68). A handle portion (64) is positioned circumferentially around the annular sidewall of the elongated body in a slidable relationship along a longitudinal axis. A rod (62), connectable to an orthopedic prosthetic cup, is positioned within a cavity (70) of the body and connected to the proximal ring. A lever arm (108) having a distal wedge portion (122) is pivotally connected to the handle portion such that when the lever arm is pivoted towards the annular sidewall of the handle portion, the distal end of the rod moves within the body cavity. This rod movement within the body cavity enables a prosthetic cup to be selectably connected and disconnected from the rod distal end for insertion into a body during a surgical procedure.