Four-Bar Chain Surgical Tool for Femoral Head Removal
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Solution Overview
Problem
Current surgical tools for removing femoral heads from femoral stems in hip revision surgery often apply excessive force, risking stem displacement or fracture, and are not adaptable for various implant sizes and positions, leading to potential damage and inefficiency.
Innovation Solution
A surgical tool featuring a four-bar chain mechanism with pivotally connected handles and jaws, allowing for high mechanical advantage and adjustable positioning to accommodate different sizes and positions of femoral stems and heads, ensuring stable and controlled separation with minimal rotational movement and high force application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If excessive force is applied to remove the femoral head, then the head can be separated from the stem, but the stem may be displaced or fractured
Solution Approach 1:
The tool employs a dynamic four-bar chain mechanism with movable links and joints that allow the application of controlled separating force. The mechanism transforms the surgeon's manual input force into a amplified separating force between the femoral head and stem, enabling force application that is sufficient for separation but controlled to prevent stem damage
Solution Approach 2:
The tool allows adjustment of the mechanical advantage ratio by changing the configuration of the four-bar chain mechanism. This enables the surgeon to optimize the force multiplication factor according to the specific implant size and interference fit strength, applying the minimum necessary force to achieve separation without excessive force that could damage the stem
2Adaptability or versatility
If a fixed mechanical advantage tool is used, then the structure is simple, but it cannot accommodate various sizes and positions of implants
Solution Approach 1:
The four-bar chain mechanism includes adjustable links and joints that can be reconfigured to accommodate different implant sizes and positions. The mechanical advantage can be dynamically adjusted by changing the positions of the joints along the links, allowing the same tool to adapt to various surgical scenarios without requiring multiple specialized tools
Solution Approach 2:
The tool is designed as a universal device that can handle different sizes and positions of femoral heads and stems through its adjustable mechanism. Rather than requiring separate tools for different implant configurations, this single tool with reconfigurable four-bar chain can accommodate various surgical situations
3Ease of operation
If lateral wedge tools are used to separate the head, then access is improved, but force is applied to only one side and stem damage may occur
Solution Approach 1:
The separation force is applied through two distinct jaw elements that can engage different surfaces of the femoral head and stem assembly. This segmented approach distributes the separating force across multiple contact points rather than concentrating it on one side, reducing the risk of localized stem damage while maintaining good access
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 tool enables safe and efficient removal of femoral heads from stems with a high mechanical advantage, minimizing the risk of stem displacement and damage, and is adaptable for a range of implant sizes and positions, improving surgical precision and efficacy in revision surgeries.
Implementation Method 1
A surgical tool featuring a four-bar chain mechanism with pivotally connected handles and jaws, allowing for high mechanical advantage
Data Source
AI summary
A surgical tool for separating two components, for example removing a femoral head from a femoral stem, having a four bar chain whose four bars are a first handle (L1), an crossover component (L2), a second handle (L3) and a crossbar (L4) pivotally connected respectively by: a first joint (J1) between the first handle and the crossover component; a second, crossover joint (J2) between the crossover component and the second handle; a third joint (J3) between the second handle and the crossbar, and a fourth joint (J4) between the crossbar and the first handle, and wherein, upon application of a gripping force to the first and second handles, the first and second jaws separate from one another so as to separate the two components engaged therewith.