Acetabular Cup Installation via Constant Velocity Motion
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Solution Overview
Problem
Current methods for installing prostheses, particularly acetabular cups during 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 and non-standardized forces applied during the process, which result in undesirable torques and moment arms.
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 tool and apply controlled, axial forces, potentially aided by robotic systems and surface modifications like unidirectional surface elements or vibratory systems to reduce resistive forces and ensure precise alignment and seating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a surgeon employs a mallet to strike a rod mechanically coupled to the prosthesis through discrete high force strikes, then the prosthesis is driven into the living bone, but the forces are non-quantified and may fracture the bone at the installation site and/or may not properly seat the prosthesis within the bone
Solution Approach 1:
The patent replaces the manual mallet striking system with a motorized rod driving system that applies controlled rotational and axial forces. The motorized system converts rotational motion into linear advancement, providing quantified and controlled forces instead of unpredictable manual strikes, thereby ensuring proper prosthesis seating without bone fracture.
Solution Approach 2:
The patent incorporates sensors and control systems that monitor the installation process in real-time. The system measures forces applied, rod advancement, and prosthesis seating status, using this feedback to adjust motorized forces dynamically. This ensures forces remain within safe limits while achieving complete prosthesis insertion, resolving the contradiction between installation speed and proper seating reliability.
2Productivity
If a surgeon employs a mallet to strike a rod mechanically coupled to the prosthesis, then the prosthesis is driven into the living bone, but the amount of force utilized is non-standardized leading to inconsistent acetabular cup placement
Solution Approach 1:
The patent replaces manual mallet striking with a motorized rod driving system that applies standardized, quantified forces. The motorized system delivers consistent rotational and axial forces according to predetermined parameters, eliminating the non-standardized force application of manual mallet strikes and achieving consistent cup placement accuracy.
Solution Approach 2:
The patent transforms the installation process from variable manual force application to controlled parameter-driven force application. The system uses predetermined force magnitudes, rotational speeds, and advancement rates as controllable parameters, ensuring standardized and repeatable cup placement while maintaining installation efficiency.
3Productivity
If discrete high force strikes are used to install the prosthesis, then the prosthesis is driven into the bone, but undesirable torques and moment arms are created leading to mal-alignment
Solution Approach 1:
The patent replaces discrete mallet strikes with continuous motorized rod driving that applies forces along the central axis of the prosthesis. This eliminates the off-axis torque generation inherent in manual striking, maintaining alignment accuracy while achieving installation at controlled rates through sustained axial force application.
Solution Approach 2:
The patent incorporates preliminary alignment mechanisms that position the prosthesis and rod along the correct anatomical axis before force application begins. This preliminary positioning prevents mal-alignment from the start, allowing subsequent force application to maintain accurate alignment while driving the prosthesis into the bone at the desired installation rate.
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 by applying consistent, controlled forces, potentially lowering the incidence of complications like polyethylene wear and osteolysis, and improving the accuracy and reliability of prosthesis installation.
Implementation Method 1
aided by robotic systems and surface modifications like unidirectional surface elements or vibratory systems 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.