Acetabular Cup Installation via Constant Velocity Motion
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Solution Overview
Problem
Current methods for installing acetabular cups during total hip replacement surgery face challenges such as inconsistent placement, leading to hip instability, polyethylene wear, osteolysis, impingement, and the need for revision surgery, due to unpredictable torques and non-standardized forces used in conventional mallet-based techniques.
Innovation Solution
A system and method employing constant velocity relative motion between the prosthesis and the installation site, using a force transfer anchor to secure the installation tool, and applying axial alignment of force through a sliding hammer or vibratory motion to reduce resistive forces and ensure precise placement, along with surface modifications and sensors for feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional mallet-based techniques are used to install acetabular cups, then the installation can be performed with simple equipment, but the placement consistency deteriorates due to unpredictable torques and non-standardized forces
Solution Approach 1:
The patent replaces the conventional manual mallet-based mechanical system with a motorized or powered impaction device that delivers controlled, standardized forces. This substitution eliminates the unpredictability of manual striking while maintaining the essential function of driving the cup into the bone, thereby improving placement consistency without excessive complexity
Solution Approach 2:
The invention changes the parameters of force application by implementing standardized force magnitudes, controlled stroke lengths, and regulated impact frequencies. These parameter controls ensure that each impaction delivers a consistent, predetermined amount of force, eliminating the variability inherent in manual mallet techniques and achieving reliable cup placement
2Reliability
If high forces are applied during prosthesis installation to ensure proper seating, then the prosthesis can be securely installed, but the risk of bone fracture increases
Solution Approach 1:
The patent performs preliminary actions by progressively increasing impaction forces in controlled stages, allowing the bone and prosthesis interface to adapt gradually. This staged approach ensures proper seating is achieved through incremental force application rather than sudden high-force impacts, reducing fracture risk while maintaining installation reliability
Solution Approach 2:
The invention incorporates feedback mechanisms that monitor the forces being applied during impaction and provide real-time information to the operator. This feedback allows for dynamic adjustment of force levels, ensuring that sufficient force is applied to secure the prosthesis while immediately detecting and preventing force levels that could cause bone fracture
3Productivity
If multiple discrete high-force strikes are used to install the prosthesis, then the cup can be driven into the bone, but mal-alignment and instability increase due to off-center impacts and undesirable torques
Solution Approach 1:
The patent designs the impaction device with multi-functionality, combining alignment guidance, centered force application, and secure attachment capabilities in a single integrated system. This universal device ensures that forces are always applied through the center of the cup while maintaining proper alignment, eliminating the mal-alignment problems caused by separate alignment tools and manual striking
Solution Approach 2:
The invention introduces an intermediary component (such as a centered attachment mechanism or alignment interface) between the impaction device and the prosthesis cup. This intermediary ensures that all forces are transmitted through the precise center point of the cup, preventing off-center impacts and undesirable torques that would cause mal-alignment, while still enabling efficient force transmission for rapid installation
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
This approach reduces the risk of mal-positioning and instability, decreases the forces required for insertion, and enhances the accuracy and reliability of acetabular cup placement, thereby minimizing complications and the need for revision surgery.
Implementation Method 1
applying axial alignment of force through a sliding hammer or vibratory motion to reduce resistive forces
Implementation Method 2
applying axial alignment of force through a sliding hammer or vibratory motion to reduce resistive forces
Data Source
AI summary
A system and method for improving installation of a prosthesis, particularly an acetabular cup. The system and method may include implementation of a constant velocity relative motion between a prosthesis and an installation site. For example, an installation system may be fixed relative to the installation site, with the prosthesis fixed into an initial position. The prosthesis is moved at constant speed (i.e., with minimal if any acceleration or applied impulses) relative to the installation site. That is, one or both of the prosthesis or the installation site may be in motion. Resistive forces to installation of a prosthesis may thus be reduced by maintaining the prosthesis constantly in motion relative to the installation site. Securing a processing/implanting tool directly to the installation site may offer advantages.